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1

isotopic ratio | EMSL  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

isotopic ratio isotopic ratio Leads No leads are available at this time. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide. Abstract: As a candidate...

2

Regional And Local Trends In Helium Isotopes, Basin And Range...  

Open Energy Info (EERE)

Range Province, Western North America- Evidence For Deep Permeable Pathways Abstract Fluids from the western margin of the Basin and Range have helium isotope ratios as high as...

3

EMSL - isotopic ratio  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

isotopic-ratio en Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide. http:www.emsl.pnl.govemslwebpublicationsmagnesium-behavior-and-structural-def...

4

ARM - Measurement - Isotope ratio  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc Documentation RUC : XDCResearch Related InformationAciddropletgovMeasurementsIsotope ratio ARM

5

A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal...  

Open Energy Info (EERE)

A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal System Abstract Fluids from springs, fumaroles, and wells throughout Dixie Valley, NV were analyzed for noble...

6

Compact hydrogen/helium isotope mass spectrometer  

DOE Patents [OSTI]

The compact hydrogen and helium isotope mass spectrometer of the present invention combines low mass-resolution ion mass spectrometry and beam-foil interaction technology to unambiguously detect and quantify deuterium (D), tritium (T), hydrogen molecule (H.sub.2, HD, D.sub.2, HT, DT, and T.sub.2), .sup.3 He, and .sup.4 He concentrations and concentration variations. The spectrometer provides real-time, high sensitivity, and high accuracy measurements. Currently, no fieldable D or molecular speciation detectors exist. Furthermore, the present spectrometer has a significant advantage over traditional T detectors: no confusion of the measurements by other beta-emitters, and complete separation of atomic and molecular species of equivalent atomic mass (e.g., HD and .sup.3 He).

Funsten, Herbert O. (Los Alamos, NM); McComas, David J. (Los Alamos, NM); Scime, Earl E. (Morgantown, WV)

1996-01-01T23:59:59.000Z

7

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal...  

Open Energy Info (EERE)

we present the helium and carbon isotope results from the initial study of a fluid chemistry-monitoring program started in the summer of 2001 near the South Sister volcano in...

8

Helium Isotopes in Geothermal and Volcanic Gases of the Western...  

Open Energy Info (EERE)

fluid as it flows eastward over the caldera. Decreasing Hecondensible-gas ( HeCO2) ratios accompanying this trend suggest that CO2 addition andor preferential helium...

9

Theory of the helium isotope shift  

E-Print Network [OSTI]

Theory of the isotope shift of the centroid energies of light few-electron atoms is reviewed. Numerical results are presented for the isotope shift of the $2^3P$-$2^3S$ and $2^1S$-$2^3S$ transition energies of $^3$He and $^4$He. By comparing theoretical predictions for the isotope shift with the experimental results, the difference of the squares of the nuclear charge radii of $^3$He and $^4$He, $\\delta R^2$, is determined with high accuracy.

Yerokhin, Vladimir A

2015-01-01T23:59:59.000Z

10

Helium and lead isotope geochemistry of oceanic volcanic rocks from the East Pacific and South Atlantic  

E-Print Network [OSTI]

The isotopic evolution of helium and lead in the Earth is coupled by virtue of their common radioactive parents uranium and thorium. The isotopic signatures in oceanic volcanic rocks provide constraints on the temporal ...

Graham, David W. (David William)

1987-01-01T23:59:59.000Z

11

Oxygen And Carbon Isotope Ratios Of Hydrothermal Minerals From...  

Open Energy Info (EERE)

boiling or by isotopic exchange at low waterrock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are...

12

System and method for high precision isotope ratio destructive analysis  

DOE Patents [OSTI]

A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).

Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R

2013-07-02T23:59:59.000Z

13

Helium isotope study of geothermal features in Chile with field and laboratory data  

SciTech Connect (OSTI)

Helium isotope and stable isotope data from the El Tatio, Tinginguirica, Chillan, and Tolhuaca geothermal systems, Chile. Data from this submission are discussed in: Dobson, P.F., Kennedy, B.M., Reich, M., Sanchez, P., and Morata, D. (2013) Effects of volcanism, crustal thickness, and large scale faulting on the He isotope signatures of geothermal systems in Chile. Proceedings, 38th Workshop on Geothermal Reservoir Engineering, Stanford University, Feb. 11-13, 2013

Dobson, Patrick

2013-02-11T23:59:59.000Z

14

The use of carbon stable isotope ratios in drugs characterization  

SciTech Connect (OSTI)

Isotopic Ratio Mass Spectrometry (IRMS) is an effective toll to be used for drug product authentication. The isotopic composition could be used to assist in the differentiation between batches of drugs and assist in the identification of counterfeit materials on the market. Only two factors affect the isotopic ratios in pharmaceutical components: the isotopic composition of the raw materials and the synthetic processes performed upon them. Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products companies' economical well-being. In this preliminary study, the analyzed samples consist in two types of commercially available analgesics, which were purchases from Romanian pharmacies. Differences in ?{sup 13}C between batches from ?29.7 to ?31.6% were observed, demonstrating that this method can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. On the other hand, carbon isotopic ratios differences among producers were recorded, the variations being between ?31.3 to ?34.9% for the same type of analgesic, but from different manufactures.

Magdas, D. A., E-mail: gabriela.cristea@itim-cj.ro; Cristea, G., E-mail: gabriela.cristea@itim-cj.ro; Bot, A., E-mail: gabriela.cristea@itim-cj.ro; Mirel, V., E-mail: gabriela.cristea@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca (Romania)

2013-11-13T23:59:59.000Z

15

The consequences of helium production and nickel additions on microstructure development in isotopically tailored ferritic alloys  

SciTech Connect (OSTI)

A series of alloys have been made adding various isotopes of nickel in order to vary the production of helium during irradiation by a two step nuclear reaction in a mixed spectrum reactor. The alloys use a base composition of Fe-12Cr with an addition of 1.5% nickel, either in the form of {sup 60}Ni which produces no helium, {sup 59}Ni which produces helium at a rate of about 10 appm He/dpa, or natural nickel which provides an intermediate level of helium due to delayed development of {sup 59}Ni. Specimens were irradiated in the HFIR at Oak Ridge, TN to 7.5 dpa at 300 and 400 C. Microstructural examinations indicated that nickel additions promote precipitation in all alloys, but the effect appears to be much stronger at 400 C than at 300 C. There is sufficient dose by 7 dpa (and with 2 appm He) to initiate void swelling in ferritic/martensitic alloys. Little difference was found between response from {sup 59}Ni and natural nickel. Also, helium bubble development for high helium generation conditions appeared to be very different at 300 and 400 C. At 300 C, it appeared that high densities of bubbles formed whereas at 400 C, bubbles could not be identified, possibly because of the complexity of the microstructure, but more likely because helium accumulated at precipitate interfaces.

Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)

1999-10-01T23:59:59.000Z

16

The consequences of helium production on microstructural development in isotopically tailored ferritic alloys  

SciTech Connect (OSTI)

A series of alloys have been made adding various isotopes of nickel in order to vary the production of helium during irradiation by a two step nuclear reaction in a mixed spectrum reactor. The alloys use a base composition of Fe-12Cr with an addition of 1.5% nickel, either in the form of {sup 60}Ni which produces no helium, {sup 59}Ni which produces helium at a rate of about 10 appm He/dpa, or natural nickel ({sup Nat}Ni) which provides an intermediate level of helium due to delayed development of {sup 59}Ni. Specimens were irradiated in the HFIR at Oak Ridge, TN to {approx}7 dpa at 300 and 400{degrees}C. Microstructural examinations indicated that nickel additions promote precipitation in all alloys, but the effect appears to be much stronger at 400{degrees}C than at 300{degrees}C. There is sufficient dose by 7 dpa (and with 2 appm He) to initiate void swelling in ferritic/martensitic alloys. Little difference was found between response from {sup 59}Ni and {sup Nat}Ni. Also, helium bubble development for high helium generation conditions appeared to be very different at 300 and 400{degrees}C. At 300{degrees}C, it appeared that high densities of bubbles formed whereas at 400{degrees}C, bubbles could not be identified, possibly because of the complexity of the microstructure, but more likely because helium accumulated at precipitate interfaces.

Gelles, D.S. [Pacific Northwest Lab., Richland, WA (United States)

1996-10-01T23:59:59.000Z

17

Isotope Effects on Delayed Annihilation Time Spectra of Antiprotonic Helium Atoms in Low-Temperature Gas  

E-Print Network [OSTI]

The delayed annihilation time spectra (DATS) of antiprotonic helium atoms have been studied in isotopically pure low temperature ^3He and ^4He gas at various densities. The DATS taken at 5.8~K and 400~mbar are very similar in shape except for i) a small difference in the time scale and ii) the presence of a distinct fast decay component in the case of ^3He. The ratio of overall trapping times (mean lifetimes against annihilation), R = T_{\\mathrm{trap}}(\\mbox{^{4}He})/T_{\\mathrm{trap}}(\\mbox{^{3}He}), has been determined to be 1.144 \\pm 0.009, which is in good agreement with a theoretical estimate yielding R = [(M^*(\\mbox{\\overline{\\mathrm{p}}}\\mbox{^{4}He})/ M^*(\\mbox{\\overline{ \\mathrm{p}}}\\mbox{^{3}He})]^2=1.14, where M^* denotes the reduced mass of the \\mbox{\\overline{\\mathrm{p}}}\\mbox{He^{++}}\\ system. The presence of a short-lived component with a lifetime of (0.154\\pm 0.007)\\ \\mbox{\\mus} in the case of \\mbox{^{3}He}\\ suggests that the \\mbox{\\overline{\\mathrm{p}}}\\mbox{^{3}He^{+}}\\ atom has a state of in...

Ketzer, B; Daniel, H; Von Egidy, T; Niestroj, A; Schmid, S; Schmid, W; Yamazaki, T; Sugai, I; Nakayoshi, K; Hayano, R S; Maas, F E; Torii, H A; Ishikawa, T; Tamura, H; Morita, N; Horváth, D; Eades, John; Widmann, E

1996-01-01T23:59:59.000Z

18

Magnesium Isotope Ratios in omega Centauri Red Giants  

E-Print Network [OSTI]

We have used high resolution observations obtained at the AAT with UHRF (R ~ 100,000) and at Gemini-S with b-HROS (R ~ 150,000) to determine magnesium isotope ratios for seven omega Centauri red giants that cover a range in iron abundance from [Fe/H] = --1.78 to --0.78 dex, and for two red giants in M4 (NGC 6121). The omega Centauri stars sample both the "primordial" (i.e., O-rich, Na and Al-poor) and the "extreme" (O-depleted, Na and Al-rich) populations in the cluster. The primordial population stars in both omega Centauri and M4 show (25Mg, 26Mg)/24 Mg isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the omega Centauri extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the 26Mg/24Mg ratio is highest at intermediate metallicities ([Fe/H] < --1.4 dex), and for the highest [Al/Fe] values....

Da Costa, G S; Yong, David

2013-01-01T23:59:59.000Z

19

MAGNESIUM ISOTOPE RATIOS IN {omega} CENTAURI RED GIANTS  

SciTech Connect (OSTI)

We have used the high-resolution observations obtained at the Anglo-Australian Telescope with Ultra-High Resolution Facility (R {approx} 100,000) and at Gemini-S with b-HROS (R {approx} 150,000) to determine magnesium isotope ratios for seven {omega} Cen red giants that cover a range in iron abundance from [Fe/H] = -1.78 to -0.78 dex, and for two red giants in M4 (NGC 6121). The {omega} Cen stars sample both the ''primordial'' (i.e., O-rich, Na- and Al-poor) and the ''extreme'' (O-depleted, Na- and Al-rich) populations in the cluster. The primordial population stars in both {omega} Cen and M4 show ({sup 25}Mg, {sup 26}Mg)/{sup 24}Mg isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the {omega} Cen extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the {sup 26}Mg/{sup 24}Mg ratio is highest at intermediate metallicities ([Fe/H] < -1.4 dex), and for the highest [Al/Fe] values. Further, the relative abundance of {sup 26}Mg in the extreme population stars is notably higher than that of {sup 25}Mg, in contrast to model predictions. The {sup 25}Mg/{sup 24}Mg isotopic ratio in fact does not show any obvious dependence on either [Fe/H] or [Al/Fe] nor, intriguingly, any obvious difference between the primordial and extreme population stars.

Da Costa, G. S.; Norris, John E.; Yong, David [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 0200 (Australia)

2013-05-20T23:59:59.000Z

20

Helium Isotopes In Geothermal And Volcanic Gases Of The Western...  

Open Energy Info (EERE)

be qualitative criteria for the absence of a magmatic heat source. To first order, He(CO2 + H2S) ratios are inversely correlated with 3He4He and are consistent with a...

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

The Ratio of Helium- to Hydrogen-Atmosphere White Dwarfs: Direct Evidence for Convective Mixing  

E-Print Network [OSTI]

We determine the ratio of helium- to hydrogen-atmosphere white dwarf stars as a function of effective temperature from a model atmosphere analysis of the infrared photometric data from the Two Micron All Sky Survey combined with available visual magnitudes. Our study surpasses any previous analysis of this kind both in terms of the accuracy of the Teff determinations as well as the size of the sample. We observe that the ratio of helium- to hydrogen-atmosphere white dwarfs increases gradually from a constant value of ~0.25 between Teff = 15,000 K and 10,000 K to a value twice as large in the range 10,000 > Teff > 8000 K, suggesting that convective mixing, which occurs when the bottom of the hydrogen convection zone reaches the underlying convective helium envelope, is responsible for this gradual transition. The comparison of our results with an approximate model used to describe the outcome of this convective mixing process implies hydrogen mass layers in the range log M_H/M_tot = -10 to -8 for about 15% of the DA stars that survived the DA to DB transition near Teff ~ 30,000 K, the remainder having presumably more massive layers above log M_H/M_tot ~ -6.

P. -E. Tremblay; P. Bergeron

2007-10-04T23:59:59.000Z

22

O isotopic composition of CaCO3 measured by continuous ow isotope ratio mass spectrometry  

E-Print Network [OSTI]

for the stable isotopes of carbon-13 and oxygen-18 to determine the ratios of the rare (usually the heavy The reaction of acid with calcite produces solid calcium hydrogen phosphate, liquid water, and two gases, water then are exposed to a dry- ice slush, and the carbon dioxide sublimates while the water stays frozen. After two

23

A helium-cooled blanket design of the low aspect ratio reactor  

SciTech Connect (OSTI)

An aggressive low aspect ratio scoping fusion reactor design indicated that a 2 GW(e) reactor can have a major radius as small as 2.9 m resulting in a device with competitive cost of electricity at 49 mill/kWh. One of the technology requirements of this design is a high performance high power density first wall and blanket system. A 15 MPa helium-cooled, V-alloy and stagnant LiPb breeder first wall and blanket design was utilized. Due to the low solubility of tritium in LiPb, there is the concern of tritium migration and the formation of V-hydride. To address these issues, a lithium breeder system with high solubility of tritium has been evaluated. Due to the reduction of blanket energy multiplication to 1.2, to maintain a plant Q of > 4, the major radius of the reactor has to be increased to 3.05 m. The inlet helium coolant temperature is raised to 436 C in order to meet the minimum V-alloy temperature limit everywhere in the first wall and blanket system. To enhance the first wall heat transfer, a swirl tape coolant channel design is used. The corresponding increase in friction factor is also taken into consideration. To reduce the coolant system pressure drop, the helium pressure is increased from 15 to 18 MPa. Thermal structural analysis is performed for a simple tube design. With an inside tube diameter of 1 cm and a wall thickness of 1.5 mm, the lithium breeder can remove an average heat flux and neutron wall loading of 2 and 8 MW/m(2), respectively. This reference design can meet all the temperature and material structural design limits, as well as the coolant velocity limits. Maintaining an outlet coolant temperature of 650 C, one can expect a gross closed cycle gas turbine thermal efficiency of 45%. This study further supports the use of helium coolant for high power density reactor design. When used with the low aspect ratio reactor concept a competitive fusion reactor can be projected at 51.9 mill/kWh.

Wong, C.P.; Baxi, C.B.; Reis, E.E. [General Atomics, San Diego, CA (United States); Cerbone, R.; Cheng, E.T. [TSI Research, Solana Beach, CA (United States)

1998-03-01T23:59:59.000Z

24

Stable carbon isotope ratio of polycyclic aromatic hydrocarbons (PAHs) in the environment: validation of isolation and stable carbon isotope analysis methods  

E-Print Network [OSTI]

, purification and compound specific isotope analysis methods were developed to accurately measure the stable carbon isotope ratio of individual PAHs. Development of the method included improving accuracy and precision of the isotopic measurement by producing...

Kim, Moon Koo

2004-11-15T23:59:59.000Z

25

Measurement of lithium isotope ratios by quadrupole-ICP-MS: application to seawater and natural carbonates  

E-Print Network [OSTI]

Measurement of lithium isotope ratios by quadrupole-ICP-MS: application to seawater and natural method for lithium isotope ratio (7 Li/6 Li) determinations with low total lithium consumption ( lithium from all matrix elements using small volume resin (2 ml/3.4 meq AG 50W-X8) and low volume elution

Weston, Ken

26

The effect of fusion-relevant helium levels on the mechanical properties of isotopically tailored ferritic alloys  

SciTech Connect (OSTI)

The yield and maximum strengths of an irradiated series of isotopically tailored ferritic alloys were evaluated using the shear punch test. The composition of three of the alloys was Fe-12Cr-1.5Ni. Different balances of nickel isotopes were used in each alloy in order to produce different helium levels. A fourth alloy, which contained no nickel, was also irradiated. The addition of nickel at any isotopic balance to the Fe-12Cr base alloy significantly increased the shear yield and maximum strengths of the alloys, and as expected, the strength of the alloys decreased with increasing irradiation temperature. Helium itself, up to 75 appm over 7 dpa appears to have little effect on the mechanical properties of the alloys.

Hankin, G.L. [Loughborough Univ. (United Kingdom); Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)] [and others

1997-04-01T23:59:59.000Z

27

Carbon isotope ratio of Cenozoic CO2: A comparative evaluation of available geochemical proxies  

E-Print Network [OSTI]

Click Here for Full Article Carbon isotope ratio of Cenozoic CO2: A comparative evaluation 2009; revised 16 February 2010; accepted 1 March 2010; published 17 July 2010. [1] The carbon isotope that these factors act to offset one another. Our reconstruction suggests that Cenozoic d13 CCO2 averaged -6.1 ± 0

Tipple, Brett

28

Bayesian Integration of Isotope Ratios for Geographic Sourcing of Castor Beans  

SciTech Connect (OSTI)

Recent years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 6 0 . 9 {+-} 2 . 1 % versus 5 5 . 9 {+-} 2 . 1 % and 4 0 . 2 {+-} 1 . 8 % for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.

Webb-Robertson, Bobbie-Jo M.; Kreuzer, Helen W.; Hart, Garret L.; Ehleringer, James; West, Jason B.; Gill, Gary A.; Duckworth, Douglas C.

2012-08-15T23:59:59.000Z

29

Measurements of electron density and temperature in the H-1 heliac plasma by helium line intensity ratios  

SciTech Connect (OSTI)

Electron density and temperature distributions in the H-1 heliac plasma are measured using the helium line intensity ratio technique based on a collisional-radiative model. An inversion approach with minimum Fisher regularization is developed to reconstruct the ratios of the local emission radiances from detected line-integrated intensities. The electron density and temperature inferred from the He I 667.8/728.1 and He I 728.1/706.5 nm line ratios are in good agreement with those from other diagnostic techniques in the inner region of the plasma. The electron density and temperature values appear to be a little high in the outer region of the plasma. Some possible causes of the discrepancy in the outer region are discussed.

Ma Shuiliang; Howard, John; Blackwell, Boyd D.; Thapar, Nandika [Plasma Research Laboratory, Australian National University, Canberra ACT 0200 (Australia)

2012-03-15T23:59:59.000Z

30

Relation between hydrogen isotopic ratios of bone collagen and rain  

SciTech Connect (OSTI)

The hydrogen isotopic value ([delta]D) of deer bone collagen is related to both [delta]D of rain during the growing season and growing season relative humidity (RH). With correction for the effects of RH, bone [delta]D is related to growing season rain [delta]D in a simple manner with a slope of 1.0. This indicates that, with RH correction, there are no additional sources of bias in the [delta]D of bone due to unaccounted for biologic or climatic effects. Due to a low sensitivity of bone [delta]D to RH effects, both yearly and growing season rain [delta]D can be estimated with considerable accuracy (R = 0.97 and R = 0.96) from bone collagen [delta]D and [delta][sup 15]N. Here, [delta][sup 15]N is used to correct bone [delta]D for the effects of RH. From these estimates of rain [delta]D, it may then be possible to evaluate temperature since the [delta]D of rain primarily reflects local temperature. Therefore, the measurement of bone collagen [delta]D has good potential for evaluating paleoclimates.

Cormie, A.B.; Schwarcz, H.P. (McMaster Univ., Hamilton, Ontario (Canada)); Gray, J. (Univ. of Alberta, Edmonton (Canada))

1994-01-01T23:59:59.000Z

31

Determination of Light Water Reactor Fuel Burnup with the Isotope Ratio Method  

SciTech Connect (OSTI)

For the current project to demonstrate that isotope ratio measurements can be extended to zirconium alloys used in LWR fuel assemblies we report new analyses on irradiated samples obtained from a reactor. Zirconium alloys are used for structural elements of fuel assemblies and for the fuel element cladding. This report covers new measurements done on irradiated and unirradiated zirconium alloys, Unirradiated zircaloy samples serve as reference samples and indicate starting values or natural values for the Ti isotope ratio measured. New measurements of irradiated samples include results for 3 samples provided by AREVA. New results indicate: 1. Titanium isotope ratios were measured again in unirradiated samples to obtain reference or starting values at the same time irradiated samples were analyzed. In particular, 49Ti/48Ti ratios were indistinguishably close to values determined several months earlier and to expected natural values. 2. 49Ti/48Ti ratios were measured in 3 irradiated samples thus far, and demonstrate marked departures from natural or initial ratios, well beyond analytical uncertainty, and the ratios vary with reported fluence values. The irradiated samples appear to have significant surface contamination or radiation damage which required more time for SIMS analyses. 3. Other activated impurity elements still limit the sample size for SIMS analysis of irradiated samples. The sub-samples chosen for SIMS analysis, although smaller than optimal, were still analyzed successfully without violating the conditions of the applicable Radiological Work Permit

Gerlach, David C.; Mitchell, Mark R.; Reid, Bruce D.; Gesh, Christopher J.; Hurley, David E.

2007-11-01T23:59:59.000Z

32

Standards for publication of isotope ratio and chemical data in Chemical Geology  

E-Print Network [OSTI]

Editorial Standards for publication of isotope ratio and chemical data in Chemical Geology Abstract reporting data for internation- al standards that were analyzed in the same laboratory, using the same and trace elements, there are a large number of reasonably well-characterized whole rock standards from

Rudnick, Roberta L.

33

High-precision optical measurements of 13 isotope ratios in organic compounds at  

E-Print Network [OSTI]

range with an average precision of 0.95 and 0.67 for ethane and propane, respec- tively. The calibrated accuracy for methane, ethane, and propane is within 3 of the values determined using isotope ratio mass place in chemistry, especially in geochemistry, for determining reaction mechanisms and pro- viding

Zare, Richard N.

34

Discrimination of nuclear explosions against civilian sources based on atmospheric xenon isotopic activity ratios  

SciTech Connect (OSTI)

A global monitoring system for atmospheric xenon radioactivity is being established as part of the International Monitoring System that will be used to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) once the treaty has entered into force. This paper studies isotopic activity ratios to support interpretation of observed atmospheric concentrations of 135Xe, 133mXe, 133Xe and 131mXe. The goal is to distinguish nuclear explosion sources from civilian releases. Simulations of nuclear explosions, empirical data for both test and reactor releases as well as observations by measurement stations of the International Noble Gas Experiment (INGE) are used to provide a proof of concept for the isotopic ratio based method for source discrimination.

Kalinowski, Martin B.; Axelssson, A.; Bean, Marc; Blanchard, X.; Bowyer, Ted W.; Brachet, G.; McIntyre, Justin I.; Peters, Jana; Pistner, Christoph; Raith, Maria; Ringbom, Anders; Saey, P. R.; Schlosser, C.; Stocki, Trevor J.; Taffary, T.; Ungar, R. Kurt

2010-05-01T23:59:59.000Z

35

Isotopic 32S/33S ratio as a diagnostic of presolar grains from novae  

E-Print Network [OSTI]

Measurements of sulphur isotopes in presolar grains can help to identify the astrophysical sites in which these grains were formed. A more precise thermonuclear rate of the 33S(p,gamma)34Cl reaction is required, however, to assess the diagnostic ability of sulphur isotopic ratios. We have studied the 33S(3He,d)34Cl proton-transfer reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. Deuteron spectra were measured at ten scattering angles between 10 and 55 degrees. Twenty-four levels in 34Cl over Ex = 4.6 - 5.9 MeV were observed, including three levels for the first time. Proton spectroscopic factors were extracted for the first time for levels above the 33S+p threshold, spanning the energy range required for calculations of the thermonuclear 33S(p,gamma)34Cl rate in classical nova explosions. We have determined a new 33S(p,gamma)34Cl rate using a Monte Carlo method and have performed new hydrodynamic nova simulations to determine the impact on nova nucleosynthesis of remaining nuclear physics uncertainties in the reaction rate. We find that these uncertainties lead to a factor of less than 5 variation in the 33S(p,gamma)34Cl rate over typical nova peak temperatures, and variation in the ejected nova yields of S--Ca isotopes by less than 20%. In particular, the predicted 32S/33S ratio is 110 - 130 for the nova model considered, compared to 110 - 440 with previous rate uncertainties. As recent type II supernova models predict ratios of 130 - 200, the 32S/33S ratio may be used to distinguish between grains of nova and supernova origin.

A. Parikh; K. Wimmer; T. Faestermann; R. Hertenberger; J. Jose; H. -F. Wirth; C. Hinke; R. Krucken; D. Seiler; K. Steiger; K. Straub

2014-09-01T23:59:59.000Z

36

Helium isotope study of geothermal features in Chile with field and laboratory data  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Dobson, P.F., Kennedy, B.M., Reich, M., Sanchez, P., and Morata, D. (2013) Effects of volcanism, crustal thickness, and large scale faulting on the He isotope signatures of geothermal systems in Chile. Proceedings, 38th Workshop on Geothermal Reservoir Engineering, Stanford University, Feb. 11-13, 2013

Dobson, Patrick

37

he stable-hydrogen isotope ratio (D/H or 2H/1H, conventionally expressed as  

E-Print Network [OSTI]

T he stable-hydrogen isotope ratio (D/H or 2H/1H, conventionally expressed as D) in bird feathers; Bowen et al. 2005; Votier et al. 2009). Because hydrogen in consumer tissues can ultimately be traced feathers (showing stable-hydrogen isotope characteristics typical of Siberia) and first-winter feathers

Green, Andy J.

38

Isomer residual ratio of odd-odd isotope {sup 180}Ta in supernova nucleosynthsis  

SciTech Connect (OSTI)

The nucleosynthesis of {sup 180}Ta has remained an unsolved problem and as its origin many nucleosynthesis mechanisms have been proposed. This isotope has the unique feature that the naturally occurring abundance of {sup 180}Ta is actually a meta-stable isomer (half-life of >=10{sup 15} yr), while the ground state is a 1{sup +} unstable state which beta-decays with a half-life of only 8.15 hr. We have made a new time-dependent calculation of {sup 180}Ta meta-stable isomer residual ratio after supernova neutrino-induced reactions. This residual isomer ratio is crucial for understanding the production and survival of this naturally occurring rare isotope. We have constructed a new model under temperature evolution after type II supernova explosion. We include the explicit linking between the isomer and all known excited states and found that the residual ratio is insensitive to astrophysical parameters such as neutrino energy spectrum, explosion energy, decay time constant. We find that the explicit time evolution of the synthesis of {sup 180}Ta avoids the overproduction relative to {sup 138}La for a neutrino process neutrino temperature of 4 MeV.

Hayakawa, Takehito [Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Kajino, Toshitaka [National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, Satoshi [Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-11 (Japan); Mathews, Grant [Enter for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2010-06-01T23:59:59.000Z

39

Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.  

SciTech Connect (OSTI)

Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of any separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg equivalents. AMS provides an sensitive, accurate and precise method of measuring drug compounds in biological matrices.

Keck, B D; Ognibene, T; Vogel, J S

2010-02-05T23:59:59.000Z

40

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability  

SciTech Connect (OSTI)

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

Isselhardt, B H

2011-09-06T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Guidelines and recommended terms for expression of stable-isotope-ratio and gas-ratio measurement results, {  

E-Print Network [OSTI]

(VIM, 3rd edition). The recom- mendations presented herein are approved by the Commission on Isotopic and Associated Terms (VIM, 3rd edn.),[5] both published by BIPM (Bureau Interna- tional des Poids et Mesures

42

An instrumental and numerical method to determine the hydrogenic ratio in isotopic experiments in the TJ-II stellarator  

SciTech Connect (OSTI)

The isotope effect is an important topic that is relevant for future D-T fusion reactors, where the use of deuterium, rather than hydrogen, may lean to improved plasma confinement. An evaluation of the ratio of hydrogen/deuterium is needed for isotope effect studies in current isotopic experiments. Here, the spectral range around H{sub ?} and D{sub ?} lines, obtained with an intensified multi-channel detector mounted to a 1-m focal length spectrometer, is analyzed using a fit function that includes several Gaussian components. The isotopic ratio evolution for a single operational day of the TJ-II stellarator is presented. The role of injected hydrogen by Neutral Beam Injection heating is also studied.

Baciero, A., E-mail: alfonso.baciero@ciemat.es; Zurro, B. [Laboratorio Nacional de Fusión, CIEMAT, Madrid (Spain); Martínez, M. [Departamento de Física, Universidad Carlos III de Madrid, Leganés (Spain)

2014-11-15T23:59:59.000Z

43

Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania  

SciTech Connect (OSTI)

Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The ?{sup 18}O and ?{sup 2}H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher ?{sup 18}O and ?{sup 2}H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

Magdas, D. A., E-mail: gabriela.cristea@itim-cj.ro; Cristea, G., E-mail: gabriela.cristea@itim-cj.ro; Bot, A.; Puscas, R.; Radu, S.; Mirel, V. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca (Romania); Cordea, D. V.; Mihaiu, M. [University of Agricultural Science and Veterinary Medicine, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania)] [University of Agricultural Science and Veterinary Medicine, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania)

2013-11-13T23:59:59.000Z

44

Assessment of Non-traditional Isotopic Ratios by Mass Spectrometry for Analysis of Nuclear Activities: Annual Report Year 2  

SciTech Connect (OSTI)

The objective of this work is to identify isotopic ratios suitable for analysis via mass spectrometry that distinguish between commercial nuclear reactor fuel cycles, fuel cycles for weapons grade plutonium, and products from nuclear weapons explosions. Methods will also be determined to distinguish the above from medical and industrial radionuclide sources. Mass spectrometry systems will be identified that are suitable for field measurement of such isotopes in an expedient manner. Significant progress has been made with this project within the past year: (1) Isotope production from commercial nuclear fuel cycles and nuclear weapons fuel cycles have been modeled with the ORIGEN and MCNPX codes. (2) MCNPX has been utilized to calculate isotopic inventories produced in a short burst fast bare sphere reactor (to approximate the signature of a nuclear weapon). (3) Isotopic ratios have been identified that are good for distinguishing between commercial and military fuel cycles as well as between nuclear weapons and commercial nuclear fuel cycles. (4) Mass spectrometry systems have been assessed for analysis of the fission products of interest. (5) A short-list of forensic ratios have been identified that are well suited for use in portable mass spectrometry systems.

Biegalski, S; Buchholz, B

2009-08-26T23:59:59.000Z

45

Analyzing Nuclear Fuel Cycles from Isotopic Ratios of Waste Products Applicable to Measurement by Accelerator Mass Spectrometry  

SciTech Connect (OSTI)

An extensive study was conducted to determine isotopic ratios of nuclides in spent fuel that may be utilized to reveal historical characteristics of a nuclear reactor cycle. This forensic information is important to determine the origin of unknown nuclear waste. The distribution of isotopes in waste products provides information about a nuclear fuel cycle, even when the isotopes of uranium and plutonium are removed through chemical processing. Several different reactor cycles of the PWR, BWR, CANDU, and LMFBR were simulated for this work with the ORIGEN-ARP and ORIGEN 2.2 codes. The spent fuel nuclide concentrations of these reactors were analyzed to find the most informative isotopic ratios indicative of irradiation cycle length and reactor design. Special focus was given to long-lived and stable fission products that would be present many years after their creation. For such nuclides, mass spectrometry analysis methods often have better detection limits than classic gamma-ray spectroscopy. The isotopic ratios {sup 151}Sm/{sup 146}Sm, {sup 149}Sm/{sup 146}Sm, and {sup 244}Cm/{sup 246}Cm were found to be good indicators of fuel cycle length and are well suited for analysis by accelerator mass spectroscopy.

Biegalski, S R; Whitney, S M; Buchholz, B

2005-08-24T23:59:59.000Z

46

Use of plutonium isotope activity ratios in dating recent sediments. [/sup 238/Pu//sup 239/Pu + /sup 240/Pu  

SciTech Connect (OSTI)

The majority of plutonium presently in the biosphere has come from the testing of nuclear devices. In the early 1950s, the Pu-238/239+240 activity ratio of fallout debris was > 0.04; in the more extensive test series of 1961 to 1962, the Pu-238/239+240 activity ratios were quite consistent at 0.02 to 0.03 and maximum fallout delivery occurred in mid-1963. A significant perturbation in Pu isotope activity ratios occurred in mid-1966 with the deposition of Pu-238 from the SNAP-9A reentry and burn-up. Recently deposited sediments have recorded these events and where accumulation rates are rapid (> 1 cm/y), changes in Pu isotope activity ratios can be used as a geochronological tool.

Beasley, T. M.

1982-01-01T23:59:59.000Z

47

Isotopic Analysis- Fluid At Dixie Valley Geothermal Area (Kennedy...  

Open Energy Info (EERE)

permeable fluid flow pathways and the helium Isotopic composition of the surface fluids. The authors suggest that helium isotopes are the best and possibly the only...

48

Strontium isotope ratios of the Eastern Paratethys during the Mio-Pliocene transition; Implications for interbasinal connectivity  

E-Print Network [OSTI]

Strontium isotope ratios of the Eastern Paratethys during the Mio-Pliocene transition; Implications investigate the biogenically produced carbonates of the Dacian basin for strontium analyses to monitor changes evaluation showed that not all contamination could be removed, but that the strontium content of our samples

Utrecht, Universiteit

49

Accelerated Helium and Hydrogen Production in Fe-54 Doped Alloys - Measurements and Calculations for the FIST Experiment  

SciTech Connect (OSTI)

F-82H alloys isotopically enriched in 54Fe up to 86% were irradiated in the High Flux Isotope Reactor (HFIR) to determine the accelerated production of helium and hydrogen due to isotopic effects. Results are compared to calculations using isotopic helium production cross sections from ENDF/B-VI or GNASH and measured neutron spectra. Helium measurements demonstrated an accelerated helium (appm)/dpa ratio of 2.3 after a 1.25-year irradiation, an increase of a factor of 4.3 over natural iron. The accelerated helium production is due to higher helium production cross sections for 54Fe and 55Fe. Alloys doped with 55Fe could achieve helium/dpa ratios up to about 20, well above the fusion reactor ratio of 10. Hydrogen measurements were performed using a newly developed quadrupole mass spectrometer system at PNNL capable of detecting 5-appm hydrogen in milligram-sized irradiated specimens. Calculations predict that hydrogen production will be accelerated by about a factor of 13 over natural iron. However, measurements show that most of this hydrogen is not retained in the samples.

Greenwood, Lawrence R.; Oliver, Brian M.; Ohnuki, Somei; Shiba, K.; Kohno, Yutaka; Kohyama, Akira; Robertson, J. P.; Meadows, J. W.; Gelles, David S.

2000-12-01T23:59:59.000Z

50

Carbon isotope ratios of organic compound fractions in oceanic suspended particles  

E-Print Network [OSTI]

Radiocarbon evidence of fossil-carbon cycling in sediments1968), Metabolic fractionation of carbon isotopes in marineof particulate organic carbon using bomb 14 C, Nature,

Hwang, Jeomshik; Druffel, Ellen R. M

2006-01-01T23:59:59.000Z

51

O Isotopic Composition of CaCO3 Measured by Continuous Flow Isotope Ratio Mass Spectrometry: Statistical Evaluation and  

E-Print Network [OSTI]

of carbon-13 and oxygen-18 to determine the ratios of the rare (usually the heavy) to the more common water, and two gases, water vapor, and carbon dioxide. First, both gases are frozen in liquid nitrogen. The frozen gases then are exposed to a dry ice slush, and the carbon dioxide sublimates while the water stays

52

The Transport and Fate of Helium in Martensitic Steels at Fusion Relevant He/DPA Ratios and DPA Rates  

SciTech Connect (OSTI)

Understanding, modeling and managing the effects of He and displacement damage on microstructural evolution and property changes are primary objectives of fusion materials research. We recently implemented an approach for producing controlled He-to-dpa ratios under neutron irradiation using a novel ?-implantation technique. Thin 1-4 µm NiAl coatings were deposited on Eurofer-97 TEM discs to produce a uniform He deposition zone of 6 to 8 µm. The test matrix is aimed at characterizing the transport, fate and consequences of He and He-to-dpa ratio variation on alloys with a wide range of starting microstructure. We explore the effect He-to-dpa ratio and temperature on the microstructure of conventionally processed Eurofer-97. Bubbles were found at all irradiation temperatures, with estimated maximum diameters of ~12, 6.9 and 1.4 nm at 500°C (~9 dpa and 372 appm He), 400°C (~3.9 dpa and 82 appm He) and 300°C (~3.9 dpa and 89 appm He), respectively.

Kurtz, Richard J.; Odette, George R.; Yamamoto, Takuya; Gelles, David S.; Miao, Pifeng; Oliver, Brian M.

2007-08-01T23:59:59.000Z

53

Caution on the Use of Liquid Nitrogen Traps in Stable Hydrogen Isotope-Ratio Mass Spectrometry  

E-Print Network [OSTI]

-mail: tbcoplen@usgs.gov. (1) Kirshenbaum, I. In Physical Properties and Analysis of Heavy Water; Urey, H. C with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Al- though the cause of this isotopic fractionation

54

E-Print Network 3.0 - ar isotopic ratios Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and Ecology 71 arXiv:1001.0944v2physics.atom-ph7May2010 Single-Photon Atomic Sorting: Isotope Separation with Maxwell's Demon Summary: arXiv:1001.0944v2physics.atom-ph7May201...

55

Isotopic ratios and effective power determined by gamma-ray spectroscopy vs mass spectroscopy for molten salt extraction residues  

SciTech Connect (OSTI)

Impure plutonium metal is routinely processed by molten salt extraction (MSE) to reduce the amount of americium in the metal product. Throughput at various facilities where similar processes are performed has made it essential to evaluate uncertainties and possible discrepancies in the analyses of these difficult MSE materials. In an effort to evaluate the plutonium isotopic ratios and americium concentrations obtained from gamma-ray spectral data analyzed by the computer code GRPAUT, measurements were made on ten MSE salts as received and after pulverization and blending. These results were then compared to the specific powers obtained from isotopic ratios determined by mass spectrometry on these same ten samples. Americium values ranged from a few thousand parts-per-million of total plutonium to greater than 50,000 ppM. Our results indicate a small discrepancy between specific powers as determined by GRPAUT on as received'' vs pulverized and blended MSE salts. The specific powers obtained via GRPAUT on the pulverized salts agree somewhat better with specific powers obtained from the mass spectroscopy data. This work may indicate that a small discrepancy exists in the specific powers by using GRPAUT on heterogeneous, high americium samples. 5 refs., 6 tabs.

Longmire, V.L.; Cremers, T.L.; Sedlacek, W.A.; Long, S.M.; Scarborough, A.M.; Hurd, J.R.

1990-01-01T23:59:59.000Z

56

E-Print Network 3.0 - actinide isotope ratios Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

boost... produced in the r-process. In all cases, the abundance ratios among the rare earth elements and the third r... to successfully reproduce both the stable solar system...

57

E-Print Network 3.0 - actinide isotopic ratio Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

boost... produced in the r-process. In all cases, the abundance ratios among the rare earth elements and the third r... to successfully reproduce both the stable solar system...

58

Earth Planets Space, 54, 265273, 2002 Iodine isotope ratios and halide concentrations in fluids  

E-Print Network [OSTI]

is best preserved in the high-temperature fumaroles collected in 1998 and has a 129 I/I ratio of 756 ± 47 recent meteoric water from the fumarolic system after 1993. The acid hot springs on the flanks by mixing with old meteoric water and seawater. Fumarolic gases and hot spring waters were also analyzed

Fehn, Udo

59

D/H isotope ratios of kerogen, bitumen, oil, and water in hydrous pyrolysis of source rocks containing kerogen types I, II, IIS, and III  

SciTech Connect (OSTI)

Immature source rock chips containing different types of kerogen (I,II,IIS,III) were artificially matured in isotopically distinct waters by hydrous pyrolysis and by pyrolysis in supercritical water. Converging isotopic trends of inorganic (water) and organic (kerogen, bitumen, oil) hydrogen with increasing time and temperature document that water-derived hydrogen is added to or exchanged with organic hydrogen, or both, during chemical reactions that take place during thermal maturation. Isotopic mass-balance calculations show that, depending on temperature (310--381 C), time (12--144h), and source rock type, between ca. 45 and 79% of carbon-bound hydrogen in kerogen is derived from water. Estimates for bitumen and oil range slightly lower, with oil-hydrogen being least affected by water-derived hydrogen. Comparative hydrous pyrolyses of immature source rocks at 330 C for 72h show that hydrogen in kerogen, bitumen, and expelled oil/wax ranks from most to least isotopically influenced by water-derived hydrogen in the order IIS {gt} II {approximately} III {gt} I. Pyrolysis of source rock containing type II kerogen in supercritical water at 381 C for 12 h yields isotopic results that are similar to those from hydrous pyrolysis at 250 C for 72 h or 330 C for 133 h. Bulk hydrogen in kerogen contains several percent of isotopically labile hydrogen that exchanges fast and reversibly with hydrogen in water vapor at 115 C. The isotopic equilibration of labile hydrogen in kerogen with isotopic standard water vapors significantly reduces the analytical uncertainty of D/H ratios when compared with simple D/H determination of bulk hydrogen in kerogen. If extrapolation of their results from hydrous pyrolysis is permitted to natural thermal maturation at lower temperatures, the authors suggest that organic D/H ratios of fossil fuels in contact with formation water are typically altered during chemical reactions, but that D/H ratios of generated hydrocarbons are subsequently little or not affected by exchange with water hydrogen at typical reservoir conditions over geologic time. It will be difficult to utilize D/H ratios of thermally mature bulk or fractions or organic matter to quantitatively reconstruct isotopic aspects of paleoclimate and paleoenvironment. Hope resides in compound-specific D/H ratio of thermally stable, extractable biomarkers (molecular fossils) that are less susceptible to hydrogen exchange with water-derived hydrogen.

Schimmelmann, A.; Lewan, M.D.; Wintsch, R.P.

1999-11-01T23:59:59.000Z

60

Accurate determination of Curium and Californium isotopic ratios by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 248Cm samples for transmutation studies  

SciTech Connect (OSTI)

The French Atomic Energy Commission has carried out several experiments including the mini-INCA (INcineration of Actinides) project for the study of minor-actinide transmutation processes in high intensity thermal neutron fluxes, in view of proposing solutions to reduce the radiotoxicity of long-lived nuclear wastes. In this context, a Cm sample enriched in {sup 248}Cm ({approx}97 %) was irradiated in thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). This work describes a quadrupole ICP-MS (ICP-QMS) analytical procedure for precise and accurate isotopic composition determination of Cm before sample irradiation and of Cm and Cf after sample irradiation. The factors that affect the accuracy and reproducibility of isotopic ratio measurements by ICP-QMS, such as peak centre correction, detector dead time, mass bias, abundance sensitivity and hydrides formation, instrumental background, and memory blank were carefully evaluated and corrected. Uncertainties of the isotopic ratios, taking into account internal precision of isotope ratio measurements, peak tailing, and hydrides formations ranged from 0.3% to 1.3%. This uncertainties range is quite acceptable for the nuclear data to be used in transmutation studies.

Gourgiotis, A.; Isnard, H.; Aubert, M.; Dupont, E.; AlMahamid, I.; Cassette, P.; Panebianco, S.; Letourneau, A.; Chartier, F.; Tian, G.; Rao, L.; Lukens, W.

2011-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Mon. Not. R. Astron. Soc. 347, 807812 (2004) Combined element (H and C) stable isotope ratios of methane  

E-Print Network [OSTI]

of methane in carbonaceous chondrites Anna L. Butterworth,1 Olivier Aballain,2 Jerome Chappellaz2 and Mark A-element stable isotopic measurements of ex- traterrestrial molecules. Methane from two carbonaceous chondrites isotopic composition of meteoritic methane reveals information about the indigenous nature of volatile

Chappellaz, Jérôme

62

Characterization of Diesel Fuel by Chemical Separation Combined with Capillary Gas Chromatography (GC) Isotope Ratio Mass Spectrometry (IRMS)  

SciTech Connect (OSTI)

The purpose of this study was to perform a preliminary investigation of compound-specific isotope analysis (CSIA) of diesel fuels to evaluate whether the technique could distinguish between the diesel samples from different sources/locations. The ability to differentiate or correlate diesel samples could be valuable for detecting fuel tax evasion schemes. Two fractionation techniques were used to isolate the n-alkanes from the fuel. Both ?13C and ?D values for the n-alkanes were then determined by CSIA in each sample. Plots of ?D versus ?13C with sample n-alkane points connected in order of increasing carbon number gave well separated clusters with characteristic shapes for each sample. Principal components analysis (PCA) with ?13C, ?D, or combined ?13C and ?D data on the yielded scores plots that could clearly differentiate the samples, thereby demonstrating the potential of this approach for fingerprinting fuel samples using the ?13C and ?D values.

Harvey, Scott D.; Jarman, Kristin H.; Moran, James J.; Sorensen, Christina M.; Wright, Bob W.

2011-09-15T23:59:59.000Z

63

Modeling hydrogen and helium entrapment in flowing liquid metal surfaces as plasma-facing components in  

E-Print Network [OSTI]

Modeling hydrogen and helium entrapment in flowing liquid metal surfaces as plasma the PFC surface (helium and hydrogen isotopes) while accommodating high heat loads. To study this problem rather than requiring a standard vacuum system. Hydrogen isotope (DT) particles that strike the surface

Harilal, S. S.

64

Hydrogen and helium entrapment in flowing liquid metal plasma-facing surfaces  

E-Print Network [OSTI]

Hydrogen and helium entrapment in flowing liquid metal plasma-facing surfaces Ahmed Hassanein the PFC surface (helium and hydrogen isotopes) while accommodating high heat loads. To study this problem. Hydrogen isotope (DT) particles are likely be trapped in the liquid metal surface (e.g., lithium) due

Harilal, S. S.

65

Uranium 238U/235U isotope ratios as indicators of reduction: Results from an in situ biostimulation experiment at Rifle, Colorado, USA  

E-Print Network [OSTI]

sandstone-type uranium deposits. Economic Geology; 1962; (5)uranium ore deposits: Isotopic signatures of the U reduction process? ; Geology,

Bopp IV, C.J.

2010-01-01T23:59:59.000Z

66

Comparison between IRMS and CRDS methods in the determination of isotopic ratios {sup 2}H/{sup 1}H and {sup 18}O/{sup 16}O in water  

SciTech Connect (OSTI)

Traditionally, the method used for measuring the isotope ratios is the Isotope Ratio Mass Spectrometers (IRMS). A new method has been used to determine the isotopic abundances, the Cavity Ring-Down Spectroscopy (CRDS). It consists of a technique of direct absorption, of high sensitivity, which is based on measuring the absorption ratio, as a function of time, of the light confined in a high finesse optical cavity, instead of the magnitude of light beam absorption. The values of {sup 18}O/{sup 16}O and D/H ratios are determined with respect to international standards VSMOW, GISP and SLAP from the International Atomic Energy Agency (IAEA). In this work, the IRMS and CRDS techniques are compared, verifying that the CRDS technique is promising and has some advantages compared to IRMS. It uses a smaller amount of sample, the isotope measurements are made simultaneously from the steam, reducing the analysis time. It also shows good reproducibility and accuracy, and it does not require a preliminary sample preparation.

Santos, T. H. R.; Zucchi, M. R.; Lemaire, T.; Azevedo, A. E. G. [University Federal of Bahia (UFBA), Institute of Physic, Salvador, Bahia (Brazil)

2013-05-06T23:59:59.000Z

67

Burnup estimation of fuel sourcing radioactive material based on monitored Cs and Pu isotopic activity ratios in Fukushima N. P. S. accident  

SciTech Connect (OSTI)

After the severe core damage of Fukushima Dai-Ichi Nuclear Power Station, radioactive material leaked from the reactor buildings. As part of monitoring of radioactivity in the site, measurements of radioactivity in soils at three fixed points have been performed for {sup 134}Cs and {sup 137}Cs with gamma-ray spectrometry and for Pu, Pu, and {sup 240}Pu with {alpha}-ray spectrometry. Correlations of radioactivity ratios of {sup 134}Cs to {sup 137}Cs, and {sup 238}Pu to the sum of {sup 239}Pu and {sup 240}Pu with fuel burnup were studied by using theoretical burnup calculations and measurements on isotopic inventories, and compared with the Cs and Pu radioactivity rations in the soils. The comparison indicated that the burnup of the fuel sourcing the radioactivity was from 18 to 38 GWd/t, which corresponded to that of the fuel in the highest power and, therefore, the highest decay heat in operating high-burnup fueled BWR cores. (authors)

Yamamoto, T.; Suzuki, M.; Ando, Y. [Japan Nuclear Energy Safety Organization, Toranomon Towers Office, 14F, 4-1-28, Toranomon, Minato-ku, Tokyo 105-0001 (Japan)

2012-07-01T23:59:59.000Z

68

Uranium 238U/235U isotope ratios as indicators of reduction: Results from an in situ biostimulation experiment at Rifle, Colorado, USA  

SciTech Connect (OSTI)

The attenuation of groundwater contamination via chemical reaction is traditionally evaluated by monitoring contaminant concentration through time. However, this method can be confounded by common transport processes (e.g. dilution, sorption). Isotopic techniques bypass the limits of concentration methods, and so may provide improved accuracy in determining the extent of reaction. We apply measurements of {sup 238}U/{sup 235}U to a U bioremediation field experiment at the Rifle Integrated Field Research Challenge Site in Rifle, Colorado (USA). An array of monitoring and injection wells was installed on a 100 m{sup 2} plot where U(VI) contamination was present in the groundwater. Acetate-amended groundwater was injected along an up-gradient gallery to encourage the growth of dissimilatory metal reducing bacteria (e.g. Geobacter species). During amendment, U concentration dropped by an order of magnitude in the experiment plot. We measured {sup 238}U/{sup 235}U in samples from one monitoring well by MC-ICP-MS using a double isotope tracer method. A significant {approx}1.00{per_thousand} decrease in {sup 238}U/{sup 235}U occurred in the groundwater as U(VI) concentration decreased. The relationship between {sup 238}U/{sup 235}U and concentration corresponds approximately to a Rayleigh distillation curve with an effective fractionation factor ({alpha}) of 1.00046. We attribute the observed U isotope fractionation to a nuclear field shift effect during enzymatic reduction of U(VI){sub (aq)} to U(IV){sub (s)}.

Bopp IV, C.J.; Lundstrom, C.C.; Johnson, T.M.; Sanford, R.A.; Long, P.E.; Williams, K.H.

2010-02-01T23:59:59.000Z

69

Evolution of the geothermal fluids at Los Azufres, Mexico, as traced by noble gas isotopes, 18  

E-Print Network [OSTI]

Evolution of the geothermal fluids at Los Azufres, Mexico, as traced by noble gas isotopes, 18 O, D: Noble gases Strontium isotopes Helium isotopes Geothermal energy Los Azufres Araró Mexico Isotopes of noble gases, CO2, H2O and Sr were measured in 10 geothermal wells and 8 hot springs, fumaroles and mud

Long, Bernard

70

A reassessment of the effects of helium on Charpy impact properties of ferritic/martensitic steels  

SciTech Connect (OSTI)

To test the effect of helium on Charpy impact properties of ferritic/martensitic steels, two approaches are reviewed: quantification of results of tests performed on specimens irradiated in reactors with very different neutron spectra, and isotopic tailoring experiments. Data analysis can show that if the differences in reactor response are indeed due to helium effects, then irradiation in a fusion machine at 400 C to 100 dpa and 1000 appm He will result in a ductile to brittle transition temperature shift of over 500 C. However, the response as a function of dose and helium level is unlikely to be simply due to helium based on physical reasoning. Shear punch tests and microstructural examinations also support this conclusion based on irradiated samples of a series of alloys made by adding various isotopes of nickel in order to vary the production of helium during irradiation in HFIR. The addition of nickel at any isotopic balance to the Fe-12Cr base alloy significantly increased the shear yield and maximum strengths of the alloys. However, helium itself, up to 75 appm at over 7 dpa appears to have little effect on the mechanical properties of the alloys. This behavior is instead understood to result from complex precipitation response. The database for effects of helium on embrittlement based on nickel additions is therefore probably misleading and experiments should be redesigned to avoid nickel precipitation.

Gelles, D.S.; Hamilton, M.L. [Pacific Northwest National Lab., Richland, WA (United States); Hankin, G.L. [Loughborough Univ. (United Kingdom)

1998-03-01T23:59:59.000Z

71

55Fe effect on enhancing ferritic steel He/dpa ratio in fission reactor irradiations to simulate fusion conditions  

SciTech Connect (OSTI)

How to increase the ferritic steel He(appm)/dpa ratio in a fission reactor neutron spectrum is an important question for fusion reactor material testing. An early experiment showed that the accelerated He(appm)/dpa ratio of about 2.3 was achieved for 96% enriched 54Fe in iron with 458.2 effective full power days (EFPD) irradiation in the High Flux Isotope Reactor (HFIR), ORNL. Greenwood suggested that the transmutation produced 55Fe has a thermal neutron helium production cross section which may have an effect on this result. In the current work, the ferritic steel He(appm)/dpa ratio is studied in the neutron spectrum of HFIR with 55Fe thermal neutron helium production taken into account. The available ENDF-b format 55Fe incident neutron cross section file from TENDL, Netherlands, is first input into the calculation model. A benchmark calculation for the same sample as used in the aforementioned experiment was used to adjust and evaluate the TENDL 55Fe (n, a) cross section values. The analysis shows a decrease of a factor of 6700 for the TENDL 55Fe (n, a) cross section in the intermediate and low energy regions is required in order to fit the experimental results. The best fit to the cross section value at thermal neutron energy is about 27 mb. With the adjusted 55Fe (n, a) cross sections, calculation show that the 54Fe and 55Fe isotopes can be enriched by the isotopic tailoring technique in a ferritic steel sample irradiated in HFIR to significantly enhance the helium production rate. The results show that a 70% enriched 54Fe and 30% enriched 55Fe ferritic steel sample would produce a He(appm)/dpa ratio of about 13 initially in the HFIR peripheral target position (PTP). After one year irradiation, the ratio decreases to about 10. This new calculation can be used to guide future isotopic tailoring experiments designed to increase the He(appm)/dpa ratio in fission reactors. A benchmark experiment is suggested to be performed to evaluate the 55Fe (n, a) cross section at thermal energy.

Liu, Haibo; Abdou, Mohamed A.; Greenwood, Lawrence R.

2013-11-01T23:59:59.000Z

72

UV-frequency metrology on CO (a{sup 3}{Pi}): Isotope effects and sensitivity to a variation of the proton-to-electron mass ratio  

SciTech Connect (OSTI)

UV-frequency metrology has been performed on the a{sup 3}{Pi} - X{sup 1}{Sigma}{sup +} (0,0) band of various isotopologues of CO using a frequency-quadrupled injection-seeded narrow-band pulsed titanium:sapphire laser referenced to a frequency comb laser. The band origin is determined with an accuracy of 5 MHz ({delta}{nu}/{nu}=3x10{sup -9}), while the energy differences between rotational levels in the a{sup 3}{Pi} state are determined with an accuracy of 500 kHz. From these measurements, in combination with previously published radio-frequency and microwave data, a set of molecular constants is obtained that describes the level structure of the a{sup 3}{Pi} state of {sup 12}C{sup 16}O and {sup 13}C{sup 16}O with improved accuracy. Transitions in the different isotopologues are well reproduced by scaling the molecular constants of {sup 12}C{sup 16}O via the common mass-scaling rules. Only the value of the band origin could not be scaled, indicative of a breakdown of the Born-Oppenheimer approximation. Our analysis confirms the extreme sensitivity of two-photon microwave transitions between nearly degenerate rotational levels of different {Omega} manifolds for probing a possible variation of the proton-to-electron mass ratio, {mu}=m{sub p}/m{sub e}, on a laboratory time scale.

Nijs, Adrian J. de; Salumbides, Edcel J.; Eikema, Kjeld S. E.; Ubachs, Wim; Bethlem, Hendrick L. [Institute for Lasers, Life and Biophotonics Amsterdam, VU University, De Boelelaan 1081, NL-1081 HV Amsterdam (Netherlands)

2011-11-15T23:59:59.000Z

73

The effects of He I 10830 on helium abundance determinations  

E-Print Network [OSTI]

Observations of helium and hydrogen emission lines from metal-poor extragalactic H II regions provide an independent method for determining the primordial helium abundance, Y_p. Traditionally, the emission lines employed are in the visible wavelength range, and the number of suitable lines is limited. Furthermore, when using these lines, large systematic uncertainties in helium abundance determinations arise due to the degeneracy of physical parameters, such as temperature and density. Recently, Izotov, Thuan, & Guseva (2014) have pioneered adding the He 10830 infrared emission line in helium abundance determinations. The strong electron density dependence of He 10830 makes it ideal for better constraining density, potentially breaking the degeneracy with temperature. We revisit our analysis of the dataset published by Izotov, Thuan, & Stasinska (2007) and incorporate the newly available observations of He 10830 by scaling them using the observed-to-theoretical Paschen-gamma ratio. The solutions are b...

Aver, Erik; Skillman, Evan D

2015-01-01T23:59:59.000Z

74

Creep properties of Hastelloy-X in impure helium environments  

SciTech Connect (OSTI)

In impure helium environments, Hastelloy-X is susceptible to carburization and oxidation. These effects are investigated separately, and are related to the creep behavior of the alloy. Experiments were carried out at 900/sup 0/C in both helium and air. Carburization resulted in a slight increase of the creep strength up to the onset of the tertial creep. Suppression of the creep crack growth by oxidation was confirmed using notched plate specimens of Inconel alloy 600 and Hastelloy-X. Although the difference of creep strength in air and in helium was very small and considered to be inclusive in the usual scatter, a pessimistic ratio of rupture stress in helium to that in air was estimated to be 0.9.

Nakanishi, T.; Kawakami, H.

1984-08-01T23:59:59.000Z

75

Helium in Chemically Peculiar Stars  

E-Print Network [OSTI]

For the purpose of deriving the helium abundances in chemically peculiar stars, the importance of assuming a correct helium abundance has been investigated for determining the effective temperature and gravity of main sequence B-type stars, making full use of the present capability of reproducing their helium lines. Even if the flux distribution of main sequence B-type stars appears to depend only on the effective temperature for any helium abundance, the effective temperature, gravity and helium abundance have to be determined simultaneously by matching the Balmer line profiles. New MULTI NLTE calculations, performed adopting ATLAS9 model atmospheres and updated helium atomic parameters, reproduce most of the observed equivalent widths of neutral helium lines for main sequence B-type stars and they make us confident of the possibility to correctly derive the helium abundance in chemically peculiar stars. An application of previous methods to the helium rich star HD 37017 shows that helium could be stratified in the magnetic pole regions, as expected in the framework of the diffusion theory in the presence of mass loss.

F. Leone

1998-05-05T23:59:59.000Z

76

Ultra high vacuum pumping system and high sensitivity helium leak detector  

DOE Patents [OSTI]

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10.sup.-13 atm cc s.sup.-1. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces backstreaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium.

Myneni, Ganapati Rao (Yorktown, VA)

1997-01-01T23:59:59.000Z

77

Ultra high vacuum pumping system and high sensitivity helium leak detector  

DOE Patents [OSTI]

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10{sup {minus}13} atm cc/s. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces back streaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium. 2 figs.

Myneni, G.R.

1997-12-30T23:59:59.000Z

78

Helium Ion Microscope | EMSL  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-SeriesFlickr FlickrGuidedCH2M HILL SecretaryHazmat workFAQsHelium Ion Microscope

79

Helium Ion Microscope | EMSL  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun with Bigfront.jpgcommunity200cellHeat Transfer inHeiko LoksteinHe!andHelium

80

Helium dilution refrigeration system  

DOE Patents [OSTI]

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

Roach, Patrick R. (Darien, IL); Gray, Kenneth E. (Naperville, IL)

1988-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Helium dilution refrigeration system  

DOE Patents [OSTI]

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

Roach, P.R.; Gray, K.E.

1988-09-13T23:59:59.000Z

82

E-Print Network 3.0 - analysing pb isotopes Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Mobile Pb-isotopes in Proterozoic sedimentary basins as guides for exploration of uranium deposits... isotope ratios and associated trace element concentrations (U, Th and...

83

The role of helium implantation induced vacancy defect on hardening of tungsten  

SciTech Connect (OSTI)

Vacancy-type defects created by helium implantation in tungsten and their impact on the nano-hardness characteristics were investigated by correlating the results from the positron annihilation spectroscopy and the nano-indentation technique. Helium implantation was performed at room temperature (RT) and at an elevated temperate of 600?°C. Also, the effect of post-annealing of the RT implanted sample was studied. The S parameter characterizing the open volume in the material was found to increase after helium irradiation and is significantly enhanced for the samples thermally treated at 600?°C either by irradiation at high temperature or by post-annealing. Two types of helium-vacancy defects were detected after helium irradiation; small defects with high helium-to-vacancy ratio (low S parameter) for RT irradiation and large defects with low helium-to-vacancy ratio (high S parameter) for thermally treated tungsten. The hardness of the heat treated tungsten coincides with the S parameter, and hence is controlled by the large helium-vacancy defects. The hardness of tungsten irradiated at RT without thermal treatment is dominated by manufacturing related defects such as dislocation loops and impurity clusters and additionally by trapped He atoms from irradiation effects, which enhance hardness. He-stabilized dislocation loops mainly cause the very high hardness values in RT irradiated samples without post-annealing.

Ou, Xin, E-mail: x.ou@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200250 (China); Anwand, Wolfgang, E-mail: w.anwand@hzdr.de; Kögler, Reinhard, E-mail: r.koegler@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Zhou, Hong-Bo [Department of Physics, Beihang University, Beijing 100191 (China); Richter, Asta, E-mail: asta.richter@th-wildau.de [Technische Hochschule Wildau, Hochschulring1, 15745 Wildau (Germany)

2014-03-28T23:59:59.000Z

84

Chemical reactions studied at ultra-low temperature in liquid helium clusters  

SciTech Connect (OSTI)

Low-temperature reaction rates are important ingredients for astrophysical reaction networks modeling the formation of interstellar matter in molecular clouds. Unfortunately, such data is difficult to obtain by experimental means. In an attempt to study low-temperature reactions of astrophysical interest, we have investigated relevant reactions at ultralow temperature in liquid helium droplets. Being prepared by supersonic expansion of helium gas at high pressure through a nozzle into a vacuum, large helium clusters in the form of liquid droplets constitute nano-sized reaction vessels for the study of chemical reactions at ultra-low temperature. If the normal isotope {sup 4}He is used, the helium droplets are superfluid and characterized by a constant temperature of 0.37 K. Here we present results obtained for Mg, Al, and Si reacting with O{sub 2}. Mass spectrometry was employed to characterize the reaction products. As it may be difficult to distinguish between reactions occurring in the helium droplets before they are ionized and ion-molecule reactions taking place after the ionization, additional techniques were applied to ensure that the reactions actually occurred in the helium droplets. This information was provided by measuring the chemiluminescence light emitted by the products, the evaporation of helium atoms by the release of the reaction heat, or by laser-spectroscopic identification of the reactants and products.

Huisken, Friedrich; Krasnokutski, Serge A. [Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the University of Jena, Institute of Solid State Physics, Helmholtzweg 3, D-07743 Jena (Germany)

2012-11-27T23:59:59.000Z

85

Helium-cooled lithiuim compound suspension blanket concept for ITER  

SciTech Connect (OSTI)

This blanket concept uses a dilute suspension of fine solid breeder particles (Li/sub 2/O, LiAlO/sub 2/, or Li/sub 4/SiO/sub 4/) in a carrier gas (He) as the coolant and the tritium breeding stream. A small fraction of this stream is processed outside the reactor for tritium recovery. The blanket consists of a beryllium multiplier and carbon/steel reflector. A steel clad is used for all materials. A carbon reflector is employed to reduce the beryllium thickness used in the blanket for a specific tritium breeding ratio. The breeder particle size has to exceed few microns (greater than or equal to2 microns) to avoid sticking problems on the cold surfaces of the heat exchanger. The helium gas pressure is in the range of 2 to 3 MPa to carry the blanket and the heat exchanger loop. The solid breeder concentration in the helium stream is 1 to 5 volume percent. A high lithium-6 enrichment is used to produce a high tritium breeding ratio and to reduce the breeder concentration in the helium gas. At a lithium-6 enrichment of 90%, the local tritium breeding ratio is 2.03 based on a one-dimensional poloidal model. The total thickness of the helium stream is only 4 cm out of the 50 cm total blanket thickness. The blanket uses a 35 cm of beryllium for neutron multiplication. A simple multi-layer design is employed where the blanket sector has the helium coolant flowing in the poloidal direction. The blanket concept has several unique advantages which are very beneficial for fusion reactors including ITER. 10 refs., 2 tabs.

Gohar, Y.; Baker, C.C.; Attaya, H.; Billone, M.; Clemmer, R.C.; Finn, P.A.; Hassanein, A.; Johnson, C.E.; Majumdar, S.; Mattas, R.F.

1988-08-01T23:59:59.000Z

86

Helium isotopes in geothermal systems- Iceland, The Geysers,...  

Open Energy Info (EERE)

MOR type magmatic He again implying an active volcanic source possibly a "leaky" transform related to the San Andreas Fault System. Raft River contains only crustal He...

87

Electric Dipole Polarizabilities of Hydrogen and Helium Isotopes  

E-Print Network [OSTI]

The electric dipole polarizabilities of $^3$H, $^3$He, and $^4$He are calculated directly using the Schr\\"odinger equation with the latest generation of two- and three-nucleon interactions. These polarizabilities are necessary in order to obtain accurate nuclear-polarization corrections for transitions involving S-waves in one- and two-electron atoms. Our results are compared to previous results, and it is shown that direct calculations of the electric polarizability of $^4$He using modern nuclear potentials are smaller than published values calculated using experimental photoabsorption data. The status of this topic is assessed in the context of precise measurements of transitions in one- and two-electron atoms.

I. Stetcu; S. Quaglioni; J. L. Friar; A. C. Hayes; P. Navrátil

2009-04-23T23:59:59.000Z

88

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs,  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy Resources Jump to:46 - 429Lacey,(MonasterLowellis a town in CarrollManteca, California: Energy

89

A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating SolarElectric Coop,SaveWhiskey Flatshydro

90

8 2. Helium und Tritium in der Geosphre 2. Helium und Tritium in der Geosphre  

E-Print Network [OSTI]

8 2. Helium und Tritium in der Geosphäre 2. Helium und Tritium in der Geosphäre 2.1. Spezielle Einheiten und Konstanten An dieser Stelle sollen die speziellen für Helium und Tritium verwendeten Einheiten definiert und dazugehörige Umrechnungen angegeben werden. Die Wahl der Werte einiger für Helium und Tritium

Aeschbach-Hertig, Werner

91

Phase and density dependence of the delayed annihilation of metastable antiprotonic helium atoms in gas, liquid and solid helium  

E-Print Network [OSTI]

Phase and density dependence of the delayed annihilation of metastable antiprotonic helium atoms in gas, liquid and solid helium

Widmann, E; Yamazaki, T; Hayano, R S; Iwasaki, M; Nakamura, S N; Tamura, H; Ito, T M; Kawachi, A; Nishida, N; Higemoto, W; Ito, Y; Morita, N; Hartmann, F J; Daniel, H; Von Egidy, T; Schmid, W; Hoffmann, J; Eades, John

1995-01-01T23:59:59.000Z

92

Isotopic Analysis-Fluid At Long Valley Caldera Geothermal Area...  

Open Energy Info (EERE)

1971) prior to analysis by mass spectrometry. Water samples were analyzed for their oxygen isotope ratios using the carbon dioxide-equilibration method. Waters analyzed from the...

93

The use of otolith strontium isotopes (87Sr/86Sr) to identify nursery habitat for a threatened estuarine fish  

E-Print Network [OSTI]

9672-3 The use of otolith strontium isotopes ( 87 Sr/ 86 Sr)relationship between strontium isotope ratios ( 87 Sr/ 86indicate that otolith strontium isotopes ( 87 Sr/ 86 Sr) are

Hobbs, James A.; Lewis, Levi S.; Ikemiyagi, Naoaki; Sommer, Ted; Baxter, Randall D.

2010-01-01T23:59:59.000Z

94

from Isotope Production Facility  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Cancer-fighting treatment gets boost from Isotope Production Facility April 13, 2012 Isotope Production Facility produces cancer-fighting actinium 2:32 Isotope cancer treatment...

95

THE GREEN BANK TELESCOPE H II REGION DISCOVERY SURVEY. IV. HELIUM AND CARBON RECOMBINATION LINES  

SciTech Connect (OSTI)

The Green Bank Telescope H II Region Discovery Survey (GBT HRDS) found hundreds of previously unknown Galactic regions of massive star formation by detecting hydrogen radio recombination line (RRL) emission from candidate H II region targets. Since the HRDS nebulae lie at large distances from the Sun, they are located in previously unprobed zones of the Galactic disk. Here, we derive the properties of helium and carbon RRL emission from HRDS nebulae. Our target sample is the subset of the HRDS that has visible helium or carbon RRLs. This criterion gives a total of 84 velocity components (14% of the HRDS) with helium emission and 52 (9%) with carbon emission. For our highest quality sources, the average {sup 4}He{sup +}/H{sup +} abundance ratio by number, (y {sup +}), is 0.068 {+-} 0.023(1{sigma}). This is the same ratio as that measured for the sample of previously known Galactic H II regions. Nebulae without detected helium emission give robust y {sup +} upper limits. There are 5 RRL emission components with y {sup +} less than 0.04 and another 12 with upper limits below this value. These H II regions must have either a very low {sup 4}He abundance or contain a significant amount of neutral helium. The HRDS has 20 nebulae with carbon RRL emission but no helium emission at its sensitivity level. There is no correlation between the carbon RRL parameters and the 8 {mu}m mid-infrared morphology of these nebulae.

Wenger, Trey V.; Bania, T. M. [Astronomy Department, 725 Commonwealth Avenue, Boston University, Boston, MA 02215 (United States)] [Astronomy Department, 725 Commonwealth Avenue, Boston University, Boston, MA 02215 (United States); Balser, Dana S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903-2475 (United States)] [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903-2475 (United States); Anderson, L. D. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)] [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)

2013-02-10T23:59:59.000Z

96

Helium process cycle  

DOE Patents [OSTI]

A unique process cycle and apparatus design separates the consumer (cryogenic) load return flow from most of the recycle return flow of a refrigerator and/or liquefier process cycle. The refrigerator and/or liquefier process recycle return flow is recompressed by a multi-stage compressor set and the consumer load return flow is recompressed by an independent consumer load compressor set that maintains a desirable constant suction pressure using a consumer load bypass control valve and the consumer load return pressure control valve that controls the consumer load compressor's suction pressure. The discharge pressure of this consumer load compressor is thereby allowed to float at the intermediate pressure in between the first and second stage recycle compressor sets. Utilizing the unique gas management valve regulation, the unique process cycle and apparatus design in which the consumer load return flow is separate from the recycle return flow, the pressure ratios of each recycle compressor stage and all main pressures associated with the recycle return flow are allowed to vary naturally, thus providing a naturally regulated and balanced floating pressure process cycle that maintains optimal efficiency at design and off-design process cycle capacity and conditions automatically.

Ganni, Venkatarao (Yorktown, VA)

2008-08-12T23:59:59.000Z

97

Helium process cycle  

DOE Patents [OSTI]

A unique process cycle and apparatus design separates the consumer (cryogenic) load return flow from most of the recycle return flow of a refrigerator and/or liquefier process cycle. The refrigerator and/or liquefier process recycle return flow is recompressed by a multi-stage compressor set and the consumer load return flow is recompressed by an independent consumer load compressor set that maintains a desirable constant suction pressure using a consumer load bypass control valve and the consumer load return pressure control valve that controls the consumer load compressor's suction pressure. The discharge pressure of this consumer load compressor is thereby allowed to float at the intermediate pressure in between the first and second stage recycle compressor sets. Utilizing the unique gas management valve regulation, the unique process cycle and apparatus design in which the consumer load return flow is separate from the recycle return flow, the pressure ratios of each recycle compressor stage and all main pressures associated with the recycle return flow are allowed to vary naturally, thus providing a naturally regulated and balanced floating pressure process cycle that maintains optimal efficiency at design and off-design process cycle capacity and conditions automatically.

Ganni, Venkatarao (Yorktown, VA)

2007-10-09T23:59:59.000Z

98

Fission Product Ratios as Treaty Monitoring Discriminants  

SciTech Connect (OSTI)

The International Monitoring System (IMS) of the Comprehensive Test Ban Treaty Organization (CTBTO) is currently under construction. The IMS is intended for monitoring of nuclear explosions. The radionuclide branch of the IMS monitors the atmosphere for short-lived radioisotopes indicative of a nuclear weapon test, and includes field collection and measurement stations, as well as laboratories to provide reanalysis of the most important samples and a quality control function. The Pacific Northwest National Laboratory in Richland, Washington hosts the United States IMS laboratory, with the designation “RL16.” Since acute reactor containment failures and chronic reactor leakage may also produce similar isotopes, it is tempting to compute ratios of detected isotopes to determine the relevance of an event to the treaty or agreement in question. In this paper we will note several shortcomings of simple isotopic ratios: (1) fractionation of different chemical species, (2) difficulty in comparing isotopes within a single element, (3) the effect of unknown decay times. While these shortcomings will be shown in the light of an aerosol sample, several of the problems extend to xenon isotopic ratios. The result of the difficulties listed above is that considerable human expertise will be required to convert a simple mathematical ratio into a criterion which will reliably categorize an event as ‘reactor’ or ‘weapon’.

Miley, Harry S.; Bowyer, Ted W.; Greenwood, Lawrence R.; Arthur, Richard J.

2008-05-15T23:59:59.000Z

99

Hydrogen isotope fractionation during lipid biosynthesis by Tetrahymena thermophila  

E-Print Network [OSTI]

Hydrogen isotope fractionation during lipid biosynthesis by Tetrahymena thermophila Sitindra S Accepted 7 September 2013 Available online 16 September 2013 a b s t r a c t Hydrogen isotope ratio values from recording the hydrogen isotope composition of ambient water, dD values of lipids also depend

100

Magnesium Isotopes in Halo Stars  

E-Print Network [OSTI]

We have determined Mg isotope ratios in halo field dwarfs and giants in the globular cluster M71 based on high S/N high spectral resolution (R = 10$^5$) Keck HIRES spectra. Unlike previous claims of an important contribution from intermediate-mass AGB stars to the Galactic halo, we find that our $^{26}$Mg/$^{24}$Mg ratios can be explained by massive stars.

Jorge Melendez; Judith G. Cohen

2007-08-29T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Helium stratification in HD 145792: a new Helium strong star  

E-Print Network [OSTI]

In this paper we report on the real nature of the star HD 145792, classified as He weak in {\\it ``The General Catalogue of Ap and Am stars''}. By means of FEROS@ESO1.52m high resolution spectroscopic data, we refined the atmospheric parameters of the star, obtaining: T$_{\\rm eff}$ = 14400 $\\pm$ 400 K, $\\log g$ = 4.06 $\\pm$ 0.08 and $\\xi$ = 0 $^{+0.6}$ km s$^{-1}$. These values resulted always lower than those derived by different authors with pure photometric approaches. Using our values we undertook an abundance analysis with the aim to derive, for the first time, the chemical pattern of the star's atmosphere. For metals a pure LTE synthesis (ATLAS9 and SYNTHE) has been used, while for helium a hybrid approach has been preferred (ATLAS9 and SYNSPEC). The principal result of our study is that HD 145792 belongs to He strong class contrary to the previous classification. Moreover, helium seems to be vertically stratified in the atmosphere, decreasing toward deepest layers. For what that concerns metals abundances, we found the following: overabundance of oxygen, neon, silicon, phosphorus, sulfur and calcium; carbon, nitrogen, magnesium, aluminum, titanium, chromium and nickel are normal, being the discrepancies from the solar values within the experimental errors; iron resulted to be slightly underabundant.

G. Catanzaro

2007-11-28T23:59:59.000Z

102

Helium bubble bursting in tungsten  

SciTech Connect (OSTI)

Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz.

Sefta, Faiza [University of California, Berkeley, California 94720 (United States); Juslin, Niklas [University of Tennessee, Knoxville, Tennessee 37996 (United States); Wirth, Brian D., E-mail: bdwirth@utk.edu [University of Tennessee, Oak Ridge National Laboratory, Knoxville, Tennessee 37996 (United States)

2013-12-28T23:59:59.000Z

103

Telling friends from foes : strontium isotope and trace element analysis of companion burials from Pusilhá, Toledo District, Belize  

E-Print Network [OSTI]

Local Variability in Strontium Isotope Ratios of Human ToothDifferential Diagenesis of Strontium in Archaeological HumanThe ratio of barium to strontium as a paleodietary indicator

Somerville, Andrew D.

2010-01-01T23:59:59.000Z

104

ablation-absorption ratio spectrometry: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

isotopes 2 A gas chromatographypyrolysisisotope ratio mass spectrometry system for high-precision dD measurements Environmental Sciences and Ecology Websites Summary: of...

105

Enhancement of the helium resonance lines in the solar atmosphere by suprathermal electron excitation I: non-thermal transport of helium ions  

E-Print Network [OSTI]

Models of the solar transition region made from lines other than those of helium cannot account for the strength of the helium lines. However, the collisional excitation rates of the helium resonance lines are unusually sensitive to the energy of the exciting electrons. Non-thermal motions in the transition region could drive slowly-ionizing helium ions rapidly through the steep temperature gradient, exposing them to excitation by electrons characteristic of higher temperatures than those describing their ionization state. We present the results of calculations which use a more physical representation of the lifetimes of the ground states of He I and He II than was adopted in earlier work on this process. New emission measure distributions are used to calculate the temperature variation with height. The results show that non-thermal motions can lead to enhancements of the He I and He II resonance line intensities by factors that are comparable with those required. Excitation by non-Maxwellian electron distributions would reduce the effects of non-thermal transport. The effects of non-thermal motions are more consistent with the observed spatial distribution of helium emission than are those of excitation by non-Maxwellian electron distributions alone. In particular, they account better for the observed line intensity ratio I(537.0 A)/I(584.3 A), and its variation with location.

G. R. Smith; C. Jordan

2002-08-16T23:59:59.000Z

106

Superfluid helium as a technical coolant  

E-Print Network [OSTI]

The characteristics of superfluid helium as a technical coolant, which derive from its specific transport properties, are presented with particular reference to the working area in the phase diagram (saturated or pressurised helium II). We then review the principles and scaling laws of heat transport by equivalent conduction and by forced convection in pressurised helium II, thus revealing intrinsic limitations as well as technological shortcomings of these cooling methods. Once properly implemented, two-phase flow of saturated helium II presents overwhelming advantages over the previous solutions, which dictated its choice for cooling below 1.9 K the long strings of superconducting magnets in the Large Hadron Collider (LHC), a 26.7 km circumference particle collider now under construction at CERN, the European Laboratory for Particle Physics near Geneva (Switzerland). We report on recent results from the ongoing research and development programme conducted on thermohydraulics of two-phase saturated helium II...

Lebrun, P

1997-01-01T23:59:59.000Z

107

The Helium-Core Mass at the Helium Flash in Low-Mass Red Giant Stars: Observations and Theory  

E-Print Network [OSTI]

The method developed by Raffelt (1990a,b,c) to estimate a possible increase in the standard values of the helium-core mass at the tip of the red giant branch, $\\Mc$, from properties of the color-magnitude diagrams of Galactic globular clusters is employed. In the present study, we revise and update Raffelt's database, including also constraints from RR Lyrae pulsation, and find that a small increase, by $\\Delta\\Mc \\approx 0.01\\pm 0.015 \\Msun$, cannot be ruled out with the present data and evolutionary models. Our new upper limits on $\\Delta\\Mc$ are less restrictive than those previously obtained by Raffelt, as are the corresponding constraints on novel astroparticle phenomena which may affect the evolution of low-mass red giants. Within the estimated uncertainties, however, the standard values of $\\Mc$ may also be acceptable. Raffelt's method does not rule out a low envelope helium abundance in globular cluster giants, though again the standard values are compatible with the available constraints. The influence of a non-solar ratio for the $\\alpha$-capture elements upon these results is also investigated. In addition, we review several aspects of the input physics employed in red giant stellar evolutionary calculations, with the purpose of evaluating possible sources of uncertainty in the value of the helium-core mass at the helium flash that is obtained from evolutionary computations, such as: heat conduction by electrons in the degenerate core; Coulomb effects upon the Equation of State; triple-$\\alpha$ reaction rates and screening factors; neutrino emission rates, both standard and enhanced by a possible non-zero magnetic moment; stellar rotation; microscopic element diffusion; and energy losses by axions and Weakly Interacting Massive Particles.

M. Catelan; J. A. de Freitas Pacheco; J. E. Horvath

1995-09-12T23:59:59.000Z

108

Strontium isotope prole of the early Toarcian (Jurassic) oceanic anoxic event, the duration of ammonite biozones,  

E-Print Network [OSTI]

Strontium isotope pro¢le of the early Toarcian (Jurassic) oceanic anoxic event, the duration% TOC) sediments � 2000 Elsevier Science B.V. All rights reserved. Keywords: strontium; isotope ratios

Fouke, Bruce W.

109

Helium refrigeration considerations for cryomodule design  

SciTech Connect (OSTI)

Many of the present day accelerators are based on superconducting radio frequency (SRF) cavities, packaged in cryo-modules (CM), which depend on helium refrigeration at sub-atmospheric pressures, nominally 2 K. These specialized helium refrigeration systems are quite cost intensive to produce and operate. Particularly as there is typically no work extraction below the 4.5-K supply, it is important that the exergy loss between this temperature level and the CM load temperature(s) be minimized by the process configuration choices. This paper will present, compare and discuss several possible helium distribution process arrangements to support the CM loads.

Ganni, V.; Knudsen, P. [Thomas Jefferson National Accelerator Facility (JLab), Newport News, VA 23606 (United States)

2014-01-29T23:59:59.000Z

110

Enhancement of the helium resonance lines in the solar atmosphere by suprathermal electron excitation II: non-Maxwellian electron distributions  

E-Print Network [OSTI]

In solar EUV spectra the He I and He II resonance lines show unusual behaviour and have anomalously high intensities compared with other transition region lines. The formation of the helium resonance lines is investigated through extensive non-LTE radiative transfer calculations. The model atmospheres of Vernazza, Avrett & Loeser are found to provide reasonable matches to the helium resonance line intensities but significantly over-estimate the intensities of other transition region lines. New model atmospheres have been developed from emission measure distributions derived by Macpherson & Jordan, which are consistent with SOHO observations of transition region lines other than those of helium. These models fail to reproduce the observed helium resonance line intensities by significant factors. The possibility that non-Maxwellian electron distributions in the transition region might lead to increased collisional excitation rates in the helium lines is studied. Collisional excitation and ionization rates are re-computed for distribution functions with power law suprathermal tails which may form by the transport of fast electrons from high temperature regions. Enhancements of the helium resonance line intensities are found, but many of the predictions of the models regarding line ratios are inconsistent with observations. These results suggest that any such departures from Maxwellian electron distributions are not responsible for the helium resonance line intensities.

G. R. Smith

2003-06-20T23:59:59.000Z

111

Stable isotope studies  

SciTech Connect (OSTI)

The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

Ishida, T.

1992-01-01T23:59:59.000Z

112

Isotope Science and Production  

E-Print Network [OSTI]

of Energy National Isotope Program http://www.nuclear.energy.gov/isotopes/nelsotopes2a.html Isotopes for Environmental Science Isotopes produced at Los Alamos National Laboratory are used as environmental tracers change and its effects. Los Alamos National Laboratory can produce Si-32 needed for oceanographic tracing

113

Quantum Cavitation: a comparison between superfluid helium-4 and normal liquid helium-3  

E-Print Network [OSTI]

Quantum Cavitation: a comparison between superfluid helium-4 and normal liquid helium-3 S. Balibar Department of Physics, Brown University, Providence RI 02912, USA Cavitation has now been studied cases and discuss the existence of a crossover from quantum cavitation, where bubbles are nucleated

Caupin, Frédéric

114

Helium-Cooled Refractory Alloys First Wall and Blanket Evaluation  

SciTech Connect (OSTI)

Under the APEX program the He-cooled system design task is to evaluate and recommend high power density refractory alloy first wall and blanket designs and to recommend and initiate tests to address critical issues. We completed the preliminary design of a helium-cooled, W-5Re alloy, lithium breeder design and the results are reported in this paper. Many areas of the design were assessed, including material selection, helium impurity control, and mechanical, nuclear and thermal hydraulics design, and waste disposal, tritium and safety design. System study results show that at a closed cycle gas turbine (CCGT) gross thermal efficiency of 57.5%, a superconducting coil tokamak reactor, with an aspect ratio of 4, and an output power of 2 GWe, can be projected to have a cost of electricity at 54.6 mill/kWh. Critical issues were identified and we plan to continue the design on some of the critical issues during the next phase of the APEX design study.

Wong, C.P.C.; Nygren, R.E.; Baxi, C.B.; Fogarty, P.; Ghoniem, N.; Khater, H.; McCarthy, K.; Merrill, B.; Nelson, B.; Reis, E.E.; Sharafat, S.; Schleicher, R.; Sze, D.K.; Ulrickson, M.; Willms, S.; Youssef, M.; Zinkel, S.

1999-08-01T23:59:59.000Z

115

abundance isotopic: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

24 Abundances and Isotope Ratios in the Magellanic Clouds: The Star Forming Environment of N113 Astrophysics (arXiv) Summary: With the goal of deriving the physical and...

116

Development of a Micropyrolyzer for Enhanced Isotope Ratio Measurement. |  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData FilesShape, Density,TiO2(110).Development ofMotors

117

Oxygen And Carbon Isotope Ratios Of Hydrothermal Minerals From Yellowstone  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy ResourcesLoading map...(UtilityCounty,Orleans County, Vermont:OttawaCounty,2.8247524°,is a city inDrill

118

A direct and rapid leaf water extraction method for isotopic analysis  

E-Print Network [OSTI]

Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot, Israel for isotopic analysis via pyrolysis gas chromatography isotope ratio mass spectrometry (PYR/GC/IRMS). The new-scale studies that require high-throughput leaf water isotopic analysis. Copyright # 2008 John Wiley & Sons, Ltd

Yakir, Dan

119

A New Wide Range Equation of State for Helium-4  

E-Print Network [OSTI]

and has effectively replaced electron-beam melting, which was the traditional method. The same combination of helium?s inertness and high thermal conductivity is useful in other heat treatment processes. For example, nickel-base superalloys cool...

Ortiz Vega, Diego O

2013-08-01T23:59:59.000Z

120

Slow isocharged sequence ions with helium collisions: Projectile core dependence  

SciTech Connect (OSTI)

The collisions of the isocharged sequence ions of q=6 (C{sup 6+}, N{sup 6+}, O{sup 6+}, F{sup 6+}, Ne{sup 6+}, Ar{sup 6+}, and Ca{sup 6+}), q=7 (F{sup 7+}, Ne{sup 7+}, S{sup 7+}, Ar{sup 7+}, and Ca{sup 7+}), q=8 (F{sup 8+}, Ne{sup 8+}, Ar{sup 8+}, and Ca{sup 8+}), q=9 (F{sup 9+}, Ne{sup 9+}, Si{sup 9+}, S{sup 9+}, Ar{sup 9+}, and Ca{sup 9+}) and q=11 (Si{sup 11+}, Ar{sup 11+}, and Ca{sup 11+}) with helium at the same velocities were investigated. The cross-section ratios of the double-electron transfer (DET) to the single-electron capture (SEC) {sigma}{sup DET}/{sigma}{sup SEC} and the true double-electron capture (TDC) to the double-electron transfer {sigma}{sup TDC}/{sigma}{sup DET} were measured. It shows that for different ions in an isocharged sequence, the experimental cross-section ratio {sigma}{sup DET}/{sigma}{sup SEC} varies by a factor of 3. The results confirm that the projectile core is another dominant factor besides the charge state and the collision velocity in slow (0.35-0.49v{sub 0}; v{sub 0} denotes the Bohr velocity) highly charged ions (HCIs) with helium collisions. The experimental cross-section ratio {sigma}{sup DET}/{sigma}{sup SEC} is compared with the extended classical over-barrier model (ECBM) [A. Barany et al., Nucl. Instrum. Methods Phys. Res. B 9, 397 (1985)], the molecular Coulombic barrier model (MCBM) [A. Niehaus, J. Phys. B 19, 2925 (1986)], and the semiempirical scaling laws (SSL) [N. Selberg et al., Phys. Rev. A 54, 4127 (1996)]. It also shows that the projectile core properties affect the initial capture probabilities as well as the subsequent relaxation of the projectiles. The experimental cross-section ratio {sigma}{sup TDC}/{sigma}{sup DET} for those lower isocharged sequences is dramatically affected by the projectile core structure, while for those sufficiently highly isocharged sequences, the autoionization always dominates, hence the cross-section ratio {sigma}{sup TDC}/{sigma}{sup DET} is always small.

Yu Deyang; Cai Xiaohong; Shao Caojie; Lu Jun; Yang Zhihu [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lu Rongchun; Ruan Fangfang [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang Hongqiang; Cui Ying; Xu Xu; Shao Jianxiong; Ding Baowei; Chen Ximeng; Liu Zhaoyuan [Department of Modern Physics, Lanzhou University, Lanzhou 730000 (China)

2007-08-15T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

THE ISOTOPES OF AMERICIUM  

E-Print Network [OSTI]

spectrographic analysis of the americium samples. It is a48 J'---_I" THE ISOTOPES OF AMERICIUM K. Street, Jr. , A.Elements THE ISOTOPES OF AMERICIUM K. Street, Jr. , A.

Street, K.; Ghiroso, A.; Seaborg, G.T.

2008-01-01T23:59:59.000Z

122

Potential applications of high temperature helium  

SciTech Connect (OSTI)

This paper discusses the DOE MHTGR-SC program`s recent activity to improve the economics of the MHTGR without sacrificing safety performance and two potential applications of high temperature helium, the MHTGR gas turbine plant and a process heat application for methanol production from coal.

Schleicher, R.W. Jr.; Kennedy, A.J.

1992-09-01T23:59:59.000Z

123

Potential applications of high temperature helium  

SciTech Connect (OSTI)

This paper discusses the DOE MHTGR-SC program's recent activity to improve the economics of the MHTGR without sacrificing safety performance and two potential applications of high temperature helium, the MHTGR gas turbine plant and a process heat application for methanol production from coal.

Schleicher, R.W. Jr.; Kennedy, A.J.

1992-09-01T23:59:59.000Z

124

HELIUM COMPRESSOR MONITORING SYSTEM Donna Kubik  

E-Print Network [OSTI]

Compressor #9 Connectors Compressor #10 Connectors Compressor #11 Connector (LEDs) LED Timer and LED PowerHELIUM COMPRESSOR MONITORING SYSTEM Donna Kubik Arecibo Observatory #12;1 CONTENTS 1. Design goals 3 1.1 Features of the compressor monitoring system 4 2. EDAS: The basis of data acquisition 5 2

125

The Neon DSEL for mining Helium programs  

E-Print Network [OSTI]

studies We consider three case studies to illustrate how Neon can be used to data mine the collectionThe Neon DSEL for mining Helium programs Jurriaan Hage Peter van Keeken Department of Information and Computing Sciences, Utrecht University Technical Report UU-CS-2007-023 www.cs.uu.nl ISSN: 0924-3275 #12

Utrecht, Universiteit

126

The liquid helium storage system for the Large Hadron Collider.  

E-Print Network [OSTI]

The cryogenic system of the Large Hadron Collider (LHC) under operation at CERN has a total helium inventory of 140 t. Up to 50 t can be stored in gas storage tanks. The remaining inventory will be stored in a liquid helium storage system consisting of six 15-t liquid helium tanks in 4 locations. The two liquid helium tanks of specific low heat inleak design and the required infrastructure of the first location were recently commissioned. Four additional tanks shall be operational end 2010. The paper describes the features and characteristics of the liquid helium storage system and presents the measurement of the thermal performance of the two first tanks.

Benda, V; Fathallah, M; Goiffon, T; Parente, C; Perez-Duenas, E; Perret, Ph; Pirotte, O; Serio, L; Vullierme, B

2011-01-01T23:59:59.000Z

127

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass  

E-Print Network [OSTI]

Metastable pionic helium ($\\pi{\\rm He}^+$) is a three-body atom composed of a helium nucleus, an electron occupying the $1s$ ground state, and a negatively charged pion $\\pi^-$ in a Rydberg state with principal- and orbital angular momentum quantum numbers of $n\\sim \\ell+1\\sim 16$. We calculate the spin-independent energies of the $\\pi{\\rm ^3He}^+$ and $\\pi{\\rm ^4He}^+$ isotopes in the region $n=15$--19. These include relativistic and quantum electrodynamics corrections of orders $R_{\\infty}\\alpha^2$ and $R_{\\infty}\\alpha^3$ in atomic units, where $R_{\\infty}$ and $\\alpha$ denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the $\\pi^-$, and the radiative and Auger decay rates of the states are also calculated. Some states $(n,\\ell)=(16,15)$ and $(17,16)$ retain nanosecond-scale lifetimes against $\\pi^-$ absorption into the helium nucleus. We propose to use laser pulses to induce $\\pi^-$ transitions from these metastable states, to states with large ($\\sim 10^{11}$ s$^{-1}$) Auger rates. The $\\pi{\\rm He}^{2+}$ ion that remains after Auger emission of the $1s$ electron undergoes Stark mixing with the $s$, $p$, and $d$ states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the $\\pi^-$. The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge....(continued)

Masaki Hori; Anna Sótér; Vladimir I. Korobov

2014-04-30T23:59:59.000Z

128

Isotopic abundance in atom trap trace analysis  

DOE Patents [OSTI]

A method and system for detecting ratios and amounts of isotopes of noble gases. The method and system is constructed to be able to measure noble gas isotopes in water and ice, which helps reveal the geological age of the samples and understand their movements. The method and system uses a combination of a cooled discharge source, a beam collimator, a beam slower and magneto-optic trap with a laser to apply resonance frequency energy to the noble gas to be quenched and detected.

Lu, Zheng-Tian; Hu, Shiu-Ming; Jiang, Wei; Mueller, Peter

2014-03-18T23:59:59.000Z

129

Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions  

E-Print Network [OSTI]

New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics, and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high (n=6-10) principal quantum numbers affects some helium-like line ratios from low-lying (n=2) transitions.

Randall K. Smith; Nancy S. Brickhouse; Duane A. Liedahl; John C. Raymond

2001-06-26T23:59:59.000Z

130

SPECTRA OF COSMIC-RAY PROTONS AND HELIUM PRODUCED IN SUPERNOVA REMNANTS  

SciTech Connect (OSTI)

Data obtained in the Advanced Thin Ionization Calorimeter (ATIC-2), Cosmic Ray Energetics and Mass (CREAM), and Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiments suggest that the elemental interstellar spectra of cosmic rays below the knee at a few times 10{sup 6} GeV are not simple power laws, but that they experience hardening at a magnetic rigidity of about 240 GV. Another essential feature is the difference between proton and helium energy spectra, such that the He/p ratio increases by more than 50% in the energy range from 10{sup 2} to 10{sup 4} GV. We consider the concavity of the particle spectrum resulting from the nonlinear nature of diffusive shock acceleration in supernova remnants (SNRs) as a possible reason for the observed spectrum hardening. The increase of the helium-to-proton ratio with energy can be interpreted as a consequence of cosmic-ray acceleration by forward and reverse shocks in SNRs. The contribution of particles accelerated by reverse shocks makes the concavity of the produced overall cosmic-ray spectrum more pronounced. The spectra of protons and helium nuclei accelerated in SNRs and released into the interstellar medium are calculated. The derived steady-state interstellar spectra are in reasonably good agreement with observations.

Ptuskin, Vladimir; Zirakashvili, Vladimir [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Science (IZMIRAN), Troitsk, Moscow Region 142190 (Russian Federation)] [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Science (IZMIRAN), Troitsk, Moscow Region 142190 (Russian Federation); Seo, Eun-Suk [Department of Physics and Institute of Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)] [Department of Physics and Institute of Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)

2013-01-20T23:59:59.000Z

131

THE IMPACT OF HELIUM-BURNING REACTION RATES ON MASSIVE STAR EVOLUTION AND NUCLEOSYNTHESIS  

SciTech Connect (OSTI)

We study the sensitivity of presupernova evolution and supernova nucleosynthesis yields of massive stars to variations of the helium-burning reaction rates within the range of their uncertainties. The current solar abundances from Lodders are used for the initial stellar composition. We compute a grid of 12 initial stellar masses and 176 models per stellar mass to explore the effects of independently varying the {sup 12}C({alpha}, {gamma}){sup 16}O and 3{alpha} reaction rates, denoted R{sub {alpha},12} and R{sub 3{alpha}}, respectively. The production factors of both the intermediate-mass elements (A = 16-40) and the s-only isotopes along the weak s-process path ({sup 70}Ge, {sup 76}Se, {sup 80}Kr, {sup 82}Kr, {sup 86}Sr, and {sup 87}Sr) were found to be in reasonable agreement with predictions for variations of R{sub 3{alpha}} and R{sub {alpha},12} of {+-}25%; the s-only isotopes, however, tend to favor higher values of R{sub 3{alpha}} than the intermediate-mass isotopes. The experimental uncertainty (one standard deviation) in R{sub 3{alpha}}(R{sub {alpha},12}) is approximately {+-}10%({+-}25%). The results show that a more accurate measurement of one of these rates would decrease the uncertainty in the other as inferred from the present calculations. We also observe sharp changes in production factors and standard deviations for small changes in the reaction rates, due to differences in the convection structure of the star. The compactness parameter was used to assess which models would likely explode as successful supernovae, and hence contribute explosive nucleosynthesis yields. We also provide the approximate remnant masses for each model and the carbon mass fractions at the end of core-helium burning as a key parameter for later evolution stages.

West, Christopher; Heger, Alexander [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Austin, Sam M., E-mail: west0482@umn.edu, E-mail: alexander.heger@monash.edu, E-mail: austin@nscl.msu.edu [Joint Institute for Nuclear Astrophysics, Notre Dame, IN 46556 (United States)

2013-05-20T23:59:59.000Z

132

Deciphering the measured ratios of Iodine-131 to Cesium-137 at the Fukushima reactors  

E-Print Network [OSTI]

We calculate the relative abundance of the radioactive isotopes Iodine-131 and Cesium-137 produced by nuclear fission in reactors and compare it with data taken at the troubled Fukushima Dai-ichi nuclear power plant. The ratio of radioactivities of these two isotopes can be used to obtain information about when the nuclear reactions terminated.

T. Matsui

2011-12-13T23:59:59.000Z

133

An MCMC determination of the primordial helium abundance  

SciTech Connect (OSTI)

Spectroscopic observations of the chemical abundances in metal-poor H II regions provide an independent method for estimating the primordial helium abundance. H II regions are described by several physical parameters such as electron density, electron temperature, and reddening, in addition to y, the ratio of helium to hydrogen. It had been customary to estimate or determine self-consistently these parameters to calculate y. Frequentist analyses of the parameter space have been shown to be successful in these parameter determinations, and Markov Chain Monte Carlo (MCMC) techniques have proven to be very efficient in sampling this parameter space. Nevertheless, accurate determination of the primordial helium abundance from observations of H II regions is constrained by both systematic and statistical uncertainties. In an attempt to better reduce the latter, and continue to better characterize the former, we apply MCMC methods to the large dataset recently compiled by Izotov, Thuan, and Stasi?ska (2007). To improve the reliability of the determination, a high quality dataset is needed. In pursuit of this, a variety of cuts are explored. The efficacy of the He I ?4026 emission line as a constraint on the solutions is first examined, revealing the introduction of systematic bias through its absence. As a clear measure of the quality of the physical solution, a ?{sup 2} analysis proves instrumental in the selection of data compatible with the theoretical model. Nearly two-thirds of the observations fall outside a standard 95% confidence level cut, which highlights the care necessary in selecting systems and warrants further investigation into potential deficiencies of the model or data. In addition, the method also allows us to exclude systems for which parameter estimations are statistical outliers. As a result, the final selected dataset gains in reliability and exhibits improved consistency. Regression to zero metallicity yields Y{sub p} = 0.2534 ± 0.0083, in broad agreement with the WMAP result. The inclusion of more observations shows promise for further reducing the uncertainty, but more high quality spectra are required.

Aver, Erik; Olive, Keith A.; Skillman, Evan D., E-mail: aver@physics.umn.edu, E-mail: olive@umn.edu, E-mail: skillman@astro.umn.edu [School of Physics and Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States)

2012-04-01T23:59:59.000Z

134

Combined cold compressor/ejector helium refrigerator  

DOE Patents [OSTI]

A refrigeration apparatus having an ejector operatively connected with a cold compressor to form a two-stage pumping system. This pumping system is used to lower the pressure, and thereby the temperature of a bath of boiling refrigerant (helium). The apparatus as thus arranged and operated has substantially improved operating efficiency when compared to other processes or arrangements for achieving a similar low pressure.

Brown, D.P.

1984-06-05T23:59:59.000Z

135

Combined cold compressor/ejector helium refrigerator  

DOE Patents [OSTI]

A refrigeration apparatus having an ejector operatively connected with a cold compressor to form a two-stage pumping system. This pumping system is used to lower the pressure, and thereby the temperature of a bath of boiling refrigerant (helium). The apparatus as thus arranged and operated has substantially improved operating efficiency when compared to other processes or arrangements for achieving a similar low pressure.

Brown, Donald P. (Southold, NY)

1985-01-01T23:59:59.000Z

136

Development of charcoal sorbents for helium cryopumping  

SciTech Connect (OSTI)

Improved methods for cryopumping helium were developed for application to fusion reactors where high helium generation rates are expected. This study period evaluated charcoal particle size, bonding agent type and thickness, and substrate thickness. The optimum combination of charcoal, bond, and substrate was used to form a scaled-up panel for evaluation in the Tritium Systems Test Assembly (TSTA) at Los Alamos. The optimum combination is a 12 x 30 mesh coconut charcoal attached to a 0.48 cm thick copper substrate by a 0.015 cm thick silver phosphorus copper braze. A copper cement bond for attaching charcoal to a substrate was identified and tested. Helium pumping performance of this combination was comparable to that of the charcoal braze system. Environmental tests showed the charcoal's susceptibility to vacuum chamber contamination. Performance degradation followed exposure of ambient temperature charcoal to a vacuum for prolonged periods. Maintaining a liquid nitrogen-cooled shield between the charcoal and the source of contamination prevented this degradation. A combination of bake-out and LN shielding effected recovery of degraded performance.

Sedgley, D.W.; Tobin, A.G.

1985-09-30T23:59:59.000Z

137

Hybrid isotope separation scheme  

DOE Patents [OSTI]

A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus. 2 figures.

Maya, J.

1991-06-18T23:59:59.000Z

138

Hybrid isotope separation scheme  

DOE Patents [OSTI]

A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus.

Maya, Jakob (Brookline, MA)

1991-01-01T23:59:59.000Z

139

Stable isotope enrichment  

SciTech Connect (OSTI)

Brian Egle is working to increase the nation's capacity to produce stable isotopes for use including medicine, industry and national security.

Egle, Brian

2014-07-14T23:59:59.000Z

140

Stable isotope enrichment  

ScienceCinema (OSTI)

Brian Egle is working to increase the nation's capacity to produce stable isotopes for use including medicine, industry and national security.

Egle, Brian

2014-07-15T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Strontium isotope evidence of Neanderthal mobility at the site of Lakonis, Greece using laser-ablation PIMMS  

E-Print Network [OSTI]

Strontium isotope evidence of Neanderthal mobility at the site of Lakonis, Greece using laser the measurement of strontium isotope ratios in tooth enamel using laser- ablation, which allows us to use much in a coastal limestone cave, yet the strontium isotope values indicate the enamel was formed while

Smith, Tanya M.

142

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western Palaeo-Pacific, northwest Borneo  

E-Print Network [OSTI]

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western-Pacific a b s t r a c t Strontium and carbon isotope stratigraphy was applied to a 202 m-thick shallow marine, which was deposited in the western Palaeo-Pacific. Strontium isotopic ratios of rudist specimens suggest

Gilli, Adrian

143

Physics of Aquatic Systems II, 3. Stable Isotopes -Theory Universitt HeidelbergInstitut fr Umweltphysik Physics of Aquatic Systems II  

E-Print Network [OSTI]

­ Notation and definitions ­ Origin and description of fractionation ­ Fractionating processes ­ Rayleigh distillation Literature: Mook Vol. I, ch. 3 and 4 Physics of Aquatic Systems II, 3. Stable Isotopes - Theory "concentration" or mixing ratio: Fractional abundance of given isotope relative to all isotopes of the element

Aeschbach-Hertig, Werner

144

In situ controlled modification of the helium density in single helium-filled nanobubbles  

SciTech Connect (OSTI)

We demonstrate that the helium density and corresponding pressure can be modified in single nano-scale bubbles embedded in semiconductors by using the electron beam of a scanning transmission electron microscope as a multifunctional probe: the measurement probe for imaging and chemical analysis and the irradiation source to modify concomitantly the pressure in a controllable way by fine tuning of the electron beam parameters. The control of the detrapping rate is achieved by varying the experimental conditions. The underlying physical mechanisms are discussed; our experimental observations suggest that the helium detrapping from bubbles could be interpreted in terms of direct ballistic collisions, leading to the ejection of the helium atoms from the bubble.

David, M.-L., E-mail: marie-laure.david@univ-poitiers.fr; Pailloux, F. [Institut Pprime, UPR 3346 CNRS-Université de Poitiers, SP2MI, 86962 Futuroscope-Chasseneuil cedex (France); Canadian Centre for Electron Microscopy, Mc Master University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Alix, K.; Mauchamp, V.; Pizzagalli, L. [Institut Pprime, UPR 3346 CNRS-Université de Poitiers, SP2MI, 86962 Futuroscope-Chasseneuil cedex (France); Couillard, M.; Botton, G. A. [Canadian Centre for Electron Microscopy, Mc Master University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Department of Materials Science and Engineering, Mc Master University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada)

2014-03-28T23:59:59.000Z

145

Discovery of the Tungsten Isotopes  

E-Print Network [OSTI]

Thirty-five tungsten isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; A. Shore; M. Thoennessen

2009-03-25T23:59:59.000Z

146

Discovery of the Tin Isotopes  

E-Print Network [OSTI]

Thirty-eight tin isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

S. Amos; M. Thoennessen

2010-09-08T23:59:59.000Z

147

Discovery of the tungsten isotopes  

SciTech Connect (OSTI)

Thirty-five tungsten isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Fritsch, A.; Ginepro, J.Q.; Heim, M.; Schuh, A.; Shore, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Thoennessen, M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: thoennessen@nscl.msu.edu

2010-05-15T23:59:59.000Z

148

Discovery of the Tungsten Isotopes  

E-Print Network [OSTI]

Thirty-five tungsten isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Fritsch, A; Heim, M; Schuh, A; Shore, A; Thoennessen, M

2009-01-01T23:59:59.000Z

149

An Experimental Study of Cold Helium Dispersion in Air  

E-Print Network [OSTI]

The Large Hadron Collider (LHC) presently under construction at CERN, will contain about 100 tons of helium mostly located in the underground tunnel and in caverns. Potential failure modes of the accelerator, which may be followed by helium discharge to the tunnel, have been identified and the corresponding helium flows calculated. To verify the analytical calculations of helium dispersion in the tunnel, a dedicated test set-up has been built. It represents a section of the LHC tunnel at a scale 1:13 and is equipped with a controllable helium relief system enabling the simulation of different scenarios of the LHC cryogenic system failures. Corresponding patterns of cold helium dispersion in air have been observed and analysed with respect to oxygen deficiency hazard. We report on the test set-up and the measurement results, which have been scaled to real LHC conditions.

Chorowski, M; Riddone, G

2002-01-01T23:59:59.000Z

150

MODELING SPACE-TIME DEPENDENT HELIUM BUBBLE EVOLUTION IN TUNGSTEN ARMOR UNDER IFE CONDITIONS  

E-Print Network [OSTI]

MODELING SPACE-TIME DEPENDENT HELIUM BUBBLE EVOLUTION IN TUNGSTEN ARMOR UNDER IFE CONDITIONS Qiyang dependent Helium transport in finite geometries, including the simultaneous transient production of defects of Helium bubbles. I. INTRODUCTION Helium production and helium bubble evolution in neutron

Ghoniem, Nasr M.

151

OBSERVATIONAL CONSTRAINTS ON RED AND BLUE HELIUM BURNING SEQUENCES  

SciTech Connect (OSTI)

We derive the optical luminosity, colors, and ratios of the blue and red helium burning (HeB) stellar populations from archival Hubble Space Telescope observations of nineteen starburst dwarf galaxies and compare them with theoretical isochrones from Padova stellar evolution models across metallicities from Z = 0.001 to 0.009. We find that the observational data and the theoretical isochrones for both blue and red HeB populations overlap in optical luminosities and colors and the observed and predicted blue to red HeB ratios agree for stars older than 50 Myr over the time bins studied. These findings confirm the usefulness of applying isochrones to interpret observations of HeB populations. However, there are significant differences, especially for the red HeB population. Specifically, we find (1) offsets in color between the observations and theoretical isochrones of order 0.15 mag (0.5 mag) for the blue (red) HeB populations brighter than M{sub V} {approx} -4 mag, which cannot be solely due to differential extinction; (2) blue HeB stars fainter than M{sub V} {approx} -3 mag are bluer than predicted; (3) the slope of the red HeB sequence is shallower than predicted by a factor of {approx}3; and (4) the models overpredict the ratio of the most luminous blue to red HeB stars corresponding to ages {approx}< 50 Myr. Additionally, we find that for the more metal-rich galaxies in our sample (Z {approx}> 0.5 Z{sub sun}), the red HeB stars overlap with the red giant branch stars in the color-magnitude diagrams, thus reducing their usefulness as indicators of star formation for ages {approx}> 100 Myr.

McQuinn, Kristen B. W.; Skillman, Evan D. [Department of Astronomy, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Holtzman, Jon, E-mail: kmcquinn@astro.umn.edu [Department of Astronomy, New Mexico State University, Box 30001-Department 4500, 1320 Frenger Street, Las Cruces, NM 88003 (United States)

2011-10-10T23:59:59.000Z

152

ON QUANTIFICATION OF HELIUM EMBRITTLEMENT IN FERRITIC/MARTENSITIC STEELS  

SciTech Connect (OSTI)

Helium accumulation due to transmutation has long been considered a potential cause for embrittlement in ferritic/martensitic steels. Three Charpy impact databases involving nickel- and boron-doped alloys are quantified with respect to helium accumulation, and it is shown that all predict a very large effect of helium production on embrittlement. If these predictions are valid, use of Ferritic/Martensitic steels for Fusion first wall applications is highly unlikely. It is therefore necessary to reorient efforts regarding development of these steels for fusion applications to concentrate on the issue of helium embrittlement.

Gelles, David S.

2000-12-01T23:59:59.000Z

153

Isotopic Composition of Solar Wind Calcium: First in Situ Measurement by CELIAS/MTOF on Board SOHO  

E-Print Network [OSTI]

We present first results on the Ca isotopic abundances derived from the high resolution Mass Time-of-Flight (MTOF) spectrometer of the charge, element, and isotope analysis system (CELIAS) experiment on board the Solar and Heliospheric Observatory (SOHO). We obtain isotopic ratios 40Ca/42Ca = (128+-47) and 40Ca/44Ca = (50+-8), consistent with terrestrial values. This is the first in situ determination of the solar wind calcium isotopic composition and is important for studies of stellar modeling and solar system formation since the present-day solar Ca isotopic abundances are unchanged from their original isotopic composition in the solar nebula.

R. Kallenbach; F. M. Ipavich; P. Bochsler; S. Hefti; P. Wurz; M. R. Aellig; A. B. Galvin; J. Geiss; F. Gliem; G. Gloeckler; H. Grunwaldt; M. Hilchenbach; D. Hovestadt; B. Klecker

1998-02-07T23:59:59.000Z

154

Laser isotope separation  

DOE Patents [OSTI]

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Munich, DE); Boyer, Keith (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM)

1988-01-01T23:59:59.000Z

155

Photochemical isotope separation  

DOE Patents [OSTI]

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

1987-01-01T23:59:59.000Z

156

Photochemical isotope separation  

DOE Patents [OSTI]

A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

1987-04-28T23:59:59.000Z

157

AGR-2 AND AGR-3/4 RELEASE-TO-BIRTH RATIO DATA ANALYSIS  

SciTech Connect (OSTI)

A series of Advanced Gas Reactor (AGR) irradiation tests is being conducted in the Advanced Test Reactor at Idaho National Laboratory in support of development and qualification of tristructural isotropic (TRISO) low enriched fuel used in the High Temperature Gas-cooled Reactor (HTGR). Each AGR test consists of multiple independently controlled and monitored capsules containing fuel compacts placed in a graphite cylinder shrouded by a steel shell. These capsules are instrumented with thermocouples embedded in the graphite enabling temperature control. AGR configuration and irradiation conditions are based on prismatic HTGR technology distinguished primarily by the use of helium coolant, a low-power-density ceramic core capable of withstanding very high temperatures, and TRISO coated particle fuel. Thus, these tests provide valuable irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, and support development and validation of fuel performance and fission product transport models and codes. The release-rate-to-birth-rate ratio (R/B) for each of fission product isotopes (i.e., krypton and xenon) is calculated from release rates in the sweep gas flow measured by the germanium detectors used in the AGR Fission Product Monitoring (FPM) System installed downstream from each irradiated capsule. Birth rates are calculated based on the fission power in the experiment and fission product generation models. Thus, this R/B is a measure of the ability of fuel kernel, particle coating layers, and compact matrix to retain fission gas atoms preventing their release into the sweep gas flow, especially in the event of particle coating failures that occurred during AGR-2 and AGR-3/4 irradiations. The major factors that govern gaseous radioactive decay, diffusion, and release processes are found to be material diffusion coefficient, temperature, and isotopic decay constant. For each of all AGR capsules, ABAQUS-based three-dimensional finite-element thermal models are created to predict daily averages of fuel compact temperatures for the entire irradiation period, which are used in establishing the R/B correlation with temperature and decay constant. This correlation can be used by reactor designers to estimate fission gas release from postulated failed fuel particles in HTGR cores, which is the key safety factor for fuel performance assessment.

Binh T. Pham; Jeffrey J. Einerson; Dawn M. Scates; John T. Maki; David A. Petti

2014-09-01T23:59:59.000Z

158

Alternatives for Helium-3 in Multiplicity Counters  

SciTech Connect (OSTI)

Alternatives to helium-3 are being actively pursued due to the shortage and rising costs of helium-3. For safeguards applications, there are a number of ongoing investigations to find alternatives that provide the same capability in a cost-effective manner. One of the greatest challenges is to find a comparable alternative for multiplicity counters, since they require high efficiency and short collection or die-away times. Work has been progressing on investigating three commercially available alternatives for high efficiency multiplicity counters: boron trifluoride (BF3) filled proportional tubes, boron-lined proportional tubes, and lithium fluoride with zinc sulfide coated light guides. The baseline multiplicity counter used for the investigation is the Epithermal Neutron Multiplicity Counter with 121 helium-3 filled tubes at 10 atmosphere pressure, which is a significant capability to match. The primary tool for the investigation has been modeling and simulation using the Monte Carlo N-Particle eXtended (MCNPX) radiation transport program, with experiments to validate the models. To directly calculate the coincidence rates in boron-lined (and possibly other) detectors, the MCNPX code has been enhanced to allow the existing coincidence tally to be used with energy deposition rather than neutron capture reactions. This allows boron-lined detectors to be modeled more accurately. Variations of tube number and diameter along with variations in the amount of inter-tube moderator have been conducted for the BF3 and boron-lined cases. Tube pressure was investigated for BF3, up to two atmospheres, as well as optimal boron thickness in the boron-lined tubes. The lithium fluoride was modeled as sheets of material with light guides in between, and the number and thickness of the sheets investigated. The amount of light guide, which in this case doubles as a moderator, was also optimized. The results of these modeling and simulation optimization investigations are described and results presented.

Ely, James H.; Siciliano, Edward R.; Lintereur, Azaree T.; Swinhoe, Martyn T.

2013-04-01T23:59:59.000Z

159

Kosterlitz-Thouless Transition in Helium Films  

E-Print Network [OSTI]

and the Materials Science Center, Cornell University, Ithaca, Xetv York 14853 (Received 4 November 1988) The superAuid response of helium Alms with transition temperatures ranging from 70 mK to 0.5 K has been studied using a torsional oscillator technique. A... KOSTERLITZ- THOULESS TRANSITION IN. . . 8935 =n ~Koln(R/ro)+E, (T), (1.2) where R is the size of the system and Ko =p, o( T)(A'/m) . In the above expression the core radius ro serves to cut off the divergence of the flow fields at small distances...

Agnolet, Glenn; MCQUEENEY, DF; REPPY, JD.

1989-01-01T23:59:59.000Z

160

Production of thorium-229 using helium nuclei  

DOE Patents [OSTI]

A method for producing .sup.229Th includes the steps of providing .sup.226Ra as a target material, and bombarding the target material with alpha particles, helium-3, or neutrons to form .sup.229Th. When neutrons are used, the neutrons preferably include an epithermal neutron flux of at least 1.times.10.sup.13 n s.sup.-1cm.sup.-2. .sup.228Ra can also be bombarded with thermal and/or energetic neutrons to result in a neutron capture reaction to form .sup.229Th. Using .sup.230Th as a target material, .sup.229Th can be formed using neutron, gamma ray, proton or deuteron bombardment.

Mirzadeh, Saed (Knoxville, TN) [Knoxville, TN; Garland, Marc Alan (Knoxville, TN) [Knoxville, TN

2010-12-14T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Collisional Thermalization of Hydrogen and Helium in Solar Wind Plasma  

E-Print Network [OSTI]

In situ observations of the solar wind frequently show the temperature of $\\alpha$-particles (fully ionized helium), $T_\\alpha$, to significantly differ from that of protons (ionized hydrogen), $T_p$. Many heating processes in the plasma act preferentially on $\\alpha$-particles, even as collisions among ions act to gradually establish thermal equilibrium. Measurements from the $\\textit{Wind}$ spacecraft's Faraday cups reveal that, at $r=1.0\\ \\textrm{AU}$ from the Sun, the observed values of the $\\alpha$-proton temperature ratio, $\\theta_{\\alpha p} \\equiv T_\\alpha\\,/\\,T_p$ has a complex, bimodal distribution. This study applied a simple model for the radial evolution of $\\theta_{\\alpha p}$ to these data to compute expected values of $\\theta_{\\alpha p}$ at $r=0.1\\ \\textrm{AU}$. These inferred $\\theta_{\\alpha p}$-values have no trace of the bimodality seen in the $\\theta_{\\alpha p}$-values measured at $r=1.0\\ \\textrm{AU}$ but are instead consistent with the actions of the known mechanisms for $\\alpha$-particle p...

Maruca, Bennett A; Sorriso-Valvo, Luca; Kasper, Justin C; Stevens, Michael L

2013-01-01T23:59:59.000Z

162

Liquid uranium alloy-helium fission reactor  

DOE Patents [OSTI]

This invention describes a nuclear fission reactor which has a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200 to 1800/sup 0/C range, and even higher to 2500/sup 0/C.

Minkov, V.

1984-06-13T23:59:59.000Z

163

Liquid uranium alloy-helium fission reactor  

DOE Patents [OSTI]

This invention teaches a nuclear fission reactor having a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200.degree.-1800.degree. C. range, and even higher to 2500.degree. C., limited only by the thermal effectiveness of the structural materials, increasing the efficiency of power generation from the normal 30-35% with 300.degree.-500.degree. C. upper limit temperature to 50-65%. Irradiation of the circulating liquid fuel, as contrasted to only localized irradiation of a solid fuel, provides improved fuel utilization.

Minkov, Vladimir (Skokie, IL)

1986-01-01T23:59:59.000Z

164

Helium nanobubble release from Pd surface: An atomic simulation  

SciTech Connect (OSTI)

Molecular dynamic simulations of helium atoms escaping from a helium-filled nano-bubble near the surface of crystalline palladium reveal unexpected behavior. Significant deformation and cracking near the helium bubble occur initially, and then a channel forms between the bubble and the surface, providing a pathway for helium atoms to propagate towards the surface. The helium atoms erupt from the bubble in an instantaneous and volcano-like process, which leads to surface deformation consisting of cavity formation on the surface, along with modification and atomic rearrangement at the periphery of the cavity. The present simulation results show that, near the palladium surface, there is a helium-bubble-free zone, or denuded zone, with a typical thickness of about 3.0 nm. Combined with experimental measurements and continuum-scale evolutionary model predictions, the present atomic simulations demonstrate that the thickness of the denuded zone, which contains a low concentration of helium atoms, is somewhat larger than the diameter of the helium bubbles in the metal tritide. Furthermore, a relationship between the tensile strength and thickness of metal film is also determined.

Wang, Liang; Hu, Wangyu; Deng, Huiqiu; Xiao, Shifang; Yang, Jianyu; Gao, Fei; Heinisch, Howard L.; Hu, Shilin

2011-02-14T23:59:59.000Z

165

RECENT ADVANCES IN HEAT TRANSFER TO HELIUM 1  

E-Print Network [OSTI]

509 RECENT ADVANCES IN HEAT TRANSFER TO HELIUM 1 C. JOHANNES Service de Recherches Appliquées, L boiling, forced convection heat transfer. Relations between critical nucleate flux and some parameters confronted with the problem of calculating the heat transfer from the helium to the superconducting material

Paris-Sud XI, Université de

166

Diss. ETH Nr. 10714 Helium und Tritium als Tracer fr  

E-Print Network [OSTI]

Diss. ETH Nr. 10714 Helium und Tritium als Tracer für physikalische Prozesse in Seen ABHANDLUNG zur Zürich 1994 #12;Kurzfassung ix Kurzfassung Der radioaktive Zerfall von 3H (Tritium) zu 3He mit einer Fluide aus dem Erdinnern. Helium und Tritium werden massenspektrometrisch analysiert. Im Rahmen dieser Ar

Aeschbach-Hertig, Werner

167

DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI  

SciTech Connect (OSTI)

A direct measure of the helium abundances from the near-infrared transition of He I at 1.08 {mu}m is obtained for two nearly identical red giant stars in the globular cluster Omega Centauri. One star exhibits the He I line; the line is weak or absent in the other star. Detailed non-local thermal equilibrium semi-empirical models including expansion in spherical geometry are developed to match the chromospheric H{alpha}, H{beta}, and Ca II K lines, in order to predict the helium profile and derive a helium abundance. The red giant spectra suggest a helium abundance of Y {<=} 0.22 (LEID 54064) and Y = 0.39-0.44 (LEID 54084) corresponding to a difference in the abundance {Delta}Y {>=} 0.17. Helium is enhanced in the giant star (LEID 54084) that also contains enhanced aluminum and magnesium. This direct evaluation of the helium abundances gives observational support to the theoretical conjecture that multiple populations harbor enhanced helium in addition to light elements that are products of high-temperature hydrogen burning. We demonstrate that the 1.08 {mu}m He I line can yield a helium abundance in cool stars when constraints on the semi-empirical chromospheric model are provided by other spectroscopic features.

Dupree, A. K.; Avrett, E. H., E-mail: dupree@cfa.harvard.edu, E-mail: eavrett@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2013-08-20T23:59:59.000Z

168

Heterogeneous cavitation in liquid helium 4 near a glass plate  

E-Print Network [OSTI]

Heterogeneous cavitation in liquid helium 4 near a glass plate X. Chavanne, S. Balibar and F wave to study cavitation, i.e. the nucleation of bubbles, in liquid helium 4 near a clean glass plate and threshold pressures in the range 0 to -3 bar, significantly less negative than for homogeneous cavitation

Caupin, Frédéric

169

A VACANCY MODEL IN SOLID HELIUM IV B. CASTAING  

E-Print Network [OSTI]

536 A VACANCY MODEL IN SOLID HELIUM IV B. CASTAING Groupe de Physique des Solides de l here a new approach to the problem of vacancies in solid Helium 4, describing them as small liquid droplets. In this model the vacancy effective mass is very small : 0.1 mHe, where mHe is the atomic mass

Boyer, Edmond

170

Significance of Isotopically Labile Organic Hydrogen in Thermal Maturation of Organic Matter  

SciTech Connect (OSTI)

Isotopically labile organic hydrogen in fossil fuels occupies chemical positions that participate in isotopic exchange and in chemical reactions during thermal maturation from kerogen to bitumen, oil and gas. Carbon-bound organic hydrogen is isotopically far less exchangeable than hydrogen bound to nitrogen, oxygen, or sulfur. We explore why organic hydrogen isotope ratios express a relationship with organic nitrogen isotope ratios in kerogen at low to moderate maturity. We develop and apply new techniques to utilize organic D/H ratios in organic matter fractions and on a molecular level as tools for exploration for fossil fuels and for paleoenvironmental research. The scope of our samples includes naturally and artificially matured substrates, such as coal, shale, oil and gas.

Arndt Schimmelmann; Maria Mastalerz

2010-03-30T23:59:59.000Z

171

Stable isotopes of authigenic minerals in variably-saturated fractured tuff  

SciTech Connect (OSTI)

Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ({sup 18}O/{sup 16}O) and carbon ({sup 13}C/{sup 12}C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs.

Weber, D.S.; Evans, D.D.

1988-11-01T23:59:59.000Z

172

Back-Trajectory Analysis and Source-Receptor Relationships: Particulate Matter and Nitrogen Isotopic Composition in  

E-Print Network [OSTI]

sources of nitrogen in rainwater collected at an urban receptor site in Raleigh, NC. The 15 N isotope Isotopic Composition in Rainwater Chris Occhipinti, Viney P. Aneja, William Showers, and Dev Niyogi ratio signa- tures of each sample were used to further differentiate between sources of the rainwater

Niyogi, Dev

173

Ca and 87/86 Sr isotopes as tracers of silicate weathering in small  

E-Print Network [OSTI]

44/40 Ca and 87/86 Sr isotopes as tracers of silicate weathering in small catchments of the Massif, Laboratory Division, Orléans, France 2 U.S. Geological Survey, Water Resources Division, Menlo Park, CA 94025).Measurements of 44/40 Ca isotope ratios (44/40 Ca measured by the double spike method on TIMS and normalized

Paris-Sud XI, Université de

174

Constraint of the CO2 rise by new atmospheric carbon isotopic measurements during the last deglaciation  

E-Print Network [OSTI]

Click Here for Full Article Constraint of the CO2 rise by new atmospheric carbon isotopic increase of atmospheric carbon dioxide (CO2) during the last glacialinterglacial climatic transition remain debated. We analyzed the parallel evolution of CO2 and its stable carbon isotopic ratio (d13 CO2

Chappellaz, Jérôme

175

Environmental isotope investigation of groundwater flow in the Honey Lake Basin, California and Nevada  

SciTech Connect (OSTI)

The hydrology of Honey Lake Basin was studied using environmental isotope measurements of approximately 130 water samples collected during 1995 and 1996. The principal analytical methods included hydrogen, oxygen and carbon stable isotope ratio measurements, radiocarbon and tritium dating, and measurements of dissolved noble gas abundances.

Rose, T.P.; Davisson, M.L.; Hudson, G.B.; Varian, A.R.

1997-07-01T23:59:59.000Z

176

Mollusc shell periostracum as an alternative to tissue in isotopic studies  

E-Print Network [OSTI]

such as mollusc shells, however, are often abundant because of their ease of storage. We used stable isotope ratios of carbon and nitrogen to determine if there was a relationship between the isotopic composition of the periostracum of the shell and soft body...

Delong, Michael D.; Thorp, James H.

2009-06-01T23:59:59.000Z

177

Vegetation succession and carbon sequestration in a coastal wetland in northwest Florida: Evidence from carbon isotopes  

E-Print Network [OSTI]

Vegetation succession and carbon sequestration in a coastal wetland in northwest Florida: Evidence from carbon isotopes Yonghoon Choi and Yang Wang Department of Geological Sciences, Florida State. Measurements of stable carbon isotopic ratios as well as carbon (C), nitrogen (N), and phosphorus (P) contents

Wang, Yang

178

Strontium isotopic variations of Neoproterozoic seawater: Implications for crustal evolution  

SciTech Connect (OSTI)

The authors report high precision Sr isotopic data on carbonates from the Neoproterozoic Shaler Group, Victoria Island, Northwest Territories, Canada. Samples with low {sup 87}Rb/{sup 86}Sr ratios (<0.01) were selected for Sr isotopic analysis. {delta}{sup 18}O, Mn, Ca, Mg, and Sr data were used to recognize altered samples. The altered samples are characterized by high Mn/Sr ({ge}2) and variable {delta}{sup 18}O; most are dolomites. The data indicate that between ca. 790-850 Ma the {sup 87}Sr/{sup 86}Sr ratio of seawater varied between 0.70676 and 0.70561. The samples show smooth and systematic variation, with the lowest {sup 87}Sr/{sup 86}Sr value of 0.70561 at ca. 830 Ma. The low {sup 87}Sr/{sup 86}Sr ratio of carbonates from the lower parts of the section is similar to a value reported for one sample from the Adrar of Mauritania ({approx}900 Ma), West African Craton. Isotopic ratios from the upper part of the Shaler section are identical to values from the lower part of the Neoproterozoic Akademikerbreen Group, Spitsbergen. Although a paucity of absolute age determinations hinders attempts at the precise correlation of Neoproterozoic successions, it is possible to draw a broad outline of the Sr isotopic composition of seawater for this period. Data from this study and the literature are used to construct a curve of the {sup 87}Sr/{sup 86}Sr ratio of Neoproterozoic seawater. The Sr isotope composition of seawater reflects primarily the balance between continental Sr input through river input and mantle input via hydrothermal circulation of seawater through mid-ocean ridges. Coupling of Nd and Sr isotopic systems allows the authors to model changes in seafloor spreading rates (or hydrothermal flux) and continental erosion. The Sr hydrothermal flux and the erosion rate (relative to present-day value) are modeled for the period 500-900 Ma.

Asmerom, Y.; Jacobsen, S.B.; Knoll, A.H.; Butterfield, N.J. (Harvard Univ., Cambridge, MA (United States)); Swett, K. (Univ. of Iowa, Iowa City (United States))

1991-10-01T23:59:59.000Z

179

The Modular Helium Reactor for Hydrogen Production  

SciTech Connect (OSTI)

For electricity and hydrogen production, an advanced reactor technology receiving considerable international interest is a modular, passively-safe version of the high-temperature, gas-cooled reactor (HTGR), known in the U.S. as the Modular Helium Reactor (MHR), which operates at a power level of 600 MW(t). For hydrogen production, the concept is referred to as the H2-MHR. Two concepts that make direct use of the MHR high-temperature process heat are being investigated in order to improve the efficiency and economics of hydrogen production. The first concept involves coupling the MHR to the Sulfur-Iodine (SI) thermochemical water splitting process and is referred to as the SI-Based H2-MHR. The second concept involves coupling the MHR to high-temperature electrolysis (HTE) and is referred to as the HTE-Based H2-MHR.

E. Harvego; M. Richards; A. Shenoy; K. Schultz; L. Brown; M. Fukuie

2006-10-01T23:59:59.000Z

180

HELIUM EFFECTS ON DISPLACEMENT CASCADE IN TUNGSTEN  

SciTech Connect (OSTI)

Molecular dynamics (MD) simulations were performed to investigate He effects on displacement cascades in W. Helium content, proportion of interstitial and substitutional He and temperature were varied to reveal the various effects. The effect of interstitial He on the number of self-interstitial atoms (SIAs) produced during cascade damage appears to be insignificant. However, interstitial He tends to fill a vacancy (V). Nevertheless, this process is less favorable than SIA-V recombination particularly when excess SIAs are present before a cascade. The efficiency of He filling and SIA-V recombination increases as temperature increases due to increased point defect mobility. Likewise, substitutional He is more susceptible to displacement during a collision cascade than W. This susceptibility increases towards higher temperatures. Consequently, the number of surviving V is governed by the interplay between displaced substitutional He and SIA-V recombination. The temperature dependence of these processes results in a minimum number of V reached at an intermediate temperature.

Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.; Heinisch, Howard L.; Kurtz, Richard J.; Wirth, Brian D.

2013-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Helium solubility in SON68 nuclear waste glass  

SciTech Connect (OSTI)

Helium behavior in a sodium borosilicate glass (SON68) dedicated to the immobilization of high-level nuclear waste is examined. Two experimental approaches on nonradioactive glass specimens are implemented: pressurized helium infusion experiments and {sup 3}He ion implantation experiments. The temperature variation of helium solubility in SON68 glass was determined and analyzed with the harmonic oscillator model to determine values of the energy of interaction E(0) at the host sites (about -4000 J/mol), the vibration frequency (about 1.7 x 10{sup 11} s{sup -1}), and the density of solubility sites (2.2 x 10{sup 21} sites cm{sup -3}). The implantation experiments show that a non diffusive transport phenomenon (i.e., athermal diffusion) is involved in the material when the helium concentration exceeds 2.3 x 10{sup 21} He cm{sup -3}, and thus probably as soon as it exceeds the density of solubility sites accessible to helium in the glass. We propose that this transport mechanism could be associated with the relaxation of the stress gradient induced by the implanted helium profile, which is favored by the glass damage. Microstructural characterization by TEM and ESEM of glass specimens implanted with high helium concentrations showed a homogeneous microstructure free of bubbles, pores, or cracking at a scale of 10 nm. (authors)

Fares, Toby; Peuget, Sylvain; Bouty, Olivier; Broudic, Veronique; Maugeri, Emilio; Bes, Rene; Jegou, Christophe [CEA, DEN, DTCD SECM LMPA, F-30207 Marcoule, Bagnols Sur Cez, (France); Chamssedine, Fadel; Sauvage, Thierry [CNRS, CEMHTI, F-245071 Orleans, (France); Deschanels, Xavier [LNAR, Marcoule Inst Separat Chem, F-30207 Bagnols Sur Ceze, (France)

2012-12-15T23:59:59.000Z

182

Modeling atmospheric stable water isotopes and the potential for constraining cloud processes and  

E-Print Network [OSTI]

a significant part of the observed offset from pure Rayleigh distillation. Isotope fields are shown cycle. These ratios are primarily affected by the fractionation occurring at changes of phase

183

Understanding denitrification with stable isotope measurements of N2: proof of concept study  

E-Print Network [OSTI]

show that the use of [DELTA]¹?N-N? isotope ratios can be used in conjunction with N? concentrations and environmental conditions to elucidate the mechanisms of denitrification in both estuarine and coastal waters. Additionally, MRP results imply...

Downer, Roswell Curtis

2004-01-01T23:59:59.000Z

184

Chemical, multi-isotopic (Li-B-Sr-U-H-O) and thermal characterization of Triassic formation waters from the Paris Basin  

E-Print Network [OSTI]

of around 45 to 50°C. The study of uranium activity ratios for these Triassic formation waters allows us, uranium isotopes, oxygen isotopes, hydrogen isotopes, geothermometry, Trias, Paris Basin 1 hal-00563924,version1-7Feb2011 Author manuscript, published in "Chemical Geology 283, 3-4 (2011) 226-241" DOI : 10

Boyer, Edmond

185

Molecular Dynamics Simulation of Cascade-Induced Ballistic Helium Resolutioning from Bubbles in Iron  

SciTech Connect (OSTI)

Molecular dynamics simulations have been used to assess the ability of atomic displacement cascades to eject helium from small bubbles in iron. This study of the ballistic resolutioning mechanism employed a recently-developed Fe-He interatomic potential in concert with an iron potential developed by Ackland and co-workers. The primary variables examined were: irradiation temperature (100 and 600K), cascade energy (5 and 20 keV), bubble radius (0.5 and 1.0 nm), and He-to-vacancy ratio in the bubble (0.25, 0.5 and 1.0). Systematic trends were observed for each of these variables. For example, ballistic resolutioning leads to a greater number of helium atoms being displaced from larger bubbles and from bubbles that have a higher He/vacancy ratio (bubble pressure). He resolutioning was reduced at 600K relative to 100K, and for 20 keV cascades relative to 5 keV cascades. Overall, the results indicate a modest level of He removal by ballistic resolutioning. The results can be used to provide guidance in selection of a resolution parameter that can be employed in cluster dynamics models to predict the bubble size distribution that evolves under irradiation.

Stoller, Roger E [ORNL] [ORNL

2013-01-01T23:59:59.000Z

186

Flow of mantle fluids through the ductile lower crust: Helium isotope trends  

E-Print Network [OSTI]

particularly for geothermal energy development. Mantlex 10 kWh of accessible geothermal energy. This is a sizable

Kennedy, B. Mack; van Soest, Matthijs C.

2008-01-01T23:59:59.000Z

187

The Statistics of Helium Isotopes Along the Global Spreading Ridge System and the Central Limit Theorem  

E-Print Network [OSTI]

are associated with long-lived or abandoned ridges. The median, a more robust measure of the average, is 8.51 Ra implies "excess-3 He" and `therefore' a #12;2 deep, undegassed reservoir. The alternative hypotheses are a

Anderson, Don L.

188

Flow of mantle fluids through the ductile lower crust: Helium isotope trends  

E-Print Network [OSTI]

particularly for geothermal energy development. Mantlex 10 kWh of accessible geothermal energy. This is a sizableBasic Energy Sciences and Office of Geothermal Technologies

Kennedy, B. Mack; van Soest, Matthijs C.

2008-01-01T23:59:59.000Z

189

Isotopes of helium, hydrogen, and carbon as groundwater tracers in aquifers along the Colorado River  

E-Print Network [OSTI]

hard rock formations and unconsolidated sediments can act asand Cherry, 1979). Unconsolidated deposits, particularlySemi-Pervious Good Unconsolidated Sand & Gravel Consolidated

Haber, Samuel Ainsworth

2009-01-01T23:59:59.000Z

190

Helium Isotopes In Geothermal And Volcanic Gases Of The Western United  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy Resources Jump to: navigation,Ohio:Greer CountyCorridorPart AInformationHelioDynamics

191

Helium Isotopes in Geothermal and Volcanic Gases of the Western United  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy Resources Jump to: navigation,Ohio:Greer CountyCorridorPart AInformationHelioDynamicsStates, II. Long

192

Regional And Local Trends In Helium Isotopes, Basin And Range Province,  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revisionEnvReviewNonInvasiveExplorationUT-g Grant of Access Permit5-ID-aRECRaton,RFPs|Reflection

193

Flow Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublicIDAPowerPlantSitingConstruction.pdfNotify98.pdf JumpFlix Solar

194

Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision hasInformation Earth's Heat Jump to:Photon Place:NetHealth DivisionHelio MicroHeliotronics Jump

195

Fermi-liquid droplets in liquid-solid solutions of the helium isotopes  

SciTech Connect (OSTI)

For temperatures below phase separation of 1000-ppm /sup 3/He in solid /sup 4/He we measure a heat capacity ..gamma..T for a pressure between melting of pure /sup 3/He and /sup 4/He. Together with the confined sample geometry this results in liquid /sup 3/He droplets (phiapprox.10/sup 3/A) either dilute or pure depending on the phase diagram topology which is discussed theoretically. In the case of a pure /sup 3/He droplet we find an anomalously high effective mass m*/m=10, which could be explained by paramagnon effects enhanced by the confined geometry.

Hebral, B.; Greenberg, A.S.; Beal-Monod, M.T.; Papoular, M.; Frossati, G.; Godfrin, H.; Thoulouze, D.

1981-01-05T23:59:59.000Z

196

Helium-like ions as powerful X-ray plasma diagnostics  

E-Print Network [OSTI]

We revisited the calculations of the ratios of the Helium-like ion ``triplet'' (resonance, intercombination, and forbidden lines) for Z=6 to 14 (C V, N VI, O VII, Ne IX, Mg XI, Si XIII) in order to provide temperature, density and ionization diagnostics for the new high-resolution spectroscopic data of Chandra and XMM-Newton. Comparing to earlier computations, collisional rates are updated and the best experimental values for radiative transition probabilities are used. The influence of an external radiation field (photo-excitation) and the contribution from unresolved dielectronic satellite lines to the line ratios are discussed. Collision-dominated plasmas (e.g. stellar coronae), photo-ionized plasmas (e.g. AGNs) or transient plasmas (e.g. SNRs) are considered.

D. Porquet; R. Mewe; A. J. J Raassen; J. S. Kaastra; J. Dubau

2000-12-12T23:59:59.000Z

197

Transportation of medical isotopes  

SciTech Connect (OSTI)

A Draft Technical Information Document (HNF-1855) is being prepared to evaluate proposed interim tritium and medical isotope production at the Fast Flux Test Facility (FFTF). This assessment examines the potential health and safety impacts of transportation operations associated with the production of medical isotopes. Incident-free and accidental impacts are assessed using bounding source terms for the shipment of nonradiological target materials to the Hanford Site, the shipment of irradiated targets from the FFTF to the 325 Building, and the shipment of medical isotope products from the 325 Building to medical distributors. The health and safety consequences to workers and the public from the incident-free transportation of targets and isotope products would be within acceptable levels. For transportation accidents, risks to works and the public also would be within acceptable levels. This assessment is based on best information available at this time. As the medical isotope program matures, this analysis will be revised, if necessary, to support development of a final revision to the Technical Information Document.

Nielsen, D.L.

1997-11-19T23:59:59.000Z

198

Peak power ratio generator  

DOE Patents [OSTI]

A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

Moyer, Robert D. (Albuquerque, NM)

1985-01-01T23:59:59.000Z

199

Study on Off-Design Steady State Performances of Helium Gas Turbo-compressor for HTGR-GT  

SciTech Connect (OSTI)

The high temperature gas-cooled reactor (HTGR) coupled with direct gas turbine cycle is a promising concept in the future of nuclear power development. Both helium gas turbine and compressor are key components in the cycle. Under normal conditions, the mode of power adjustment is to control total helium mass in the primary loop using gas storage vessels. Meanwhile, thermal power of reactor core is regulated. This article analyzes off-design performances of helium gas turbine and compressors for high temperature gas-cooled reactor with gas turbine cycle (HTGR-GT) at steady state level of electric power adjustment. Moreover, performances of the cycle were simply discussed. Results show that the expansion ratio of turbine decreases as electric power reduces but the compression ratios of compressors increase, efficiencies of both turbine and compressors decrease to some extent. Thermal power does not vary consistently with electric power, the difference between these two powers increases as electric power reduces. As a result of much thermal energy dissipated in the temperature modulator set at core inlet, thermal efficiency of the cycle has a widely reduction under partial load conditions. (authors)

Qisen Ren; Xiaoyong Yang; Zhiyong Huang; Jie Wang [Tsinghua University, Beijing, 100084 (China)

2006-07-01T23:59:59.000Z

200

GENERATION OF RADIOXENON ISOTOPES  

SciTech Connect (OSTI)

With the continued population of the International Monitoring System (IMS) network and the certification of radioxenon laboratory systems it has become necessary to calibrate and test these systems using as many of the radioxenon isotopes as possible. Several very promising techniques have been explored recently that allow for convenient production of Xe-133, Xe-131m, the short-lived isotope Xe-135, and even the difficult to obtain Xe-133m. IMS national and international laboratories have traditionally obtained Xe-133 from medical isotope suppliers. The activity of these medical dose samples is extremely high (~ 740 MBq) and requires very careful fume hood work to dilute down to appropriate levels (~ 10 Bq). By waiting for 10 or more half-lives it is possible to reduce the handling regimen considerably, while also obtaining a strong Xe-131m signature due to its longer half-life (11.9 days). The short-lived isotope Xe-135 (9.14 hrs) and the longer lived parent nuclide Xe-133m (2.2 day half-life) are never present in these samples. To obtain these isotopes another source or technique is required. This paper will discuss the two techniques developed and implemented at Pacific Northwest National Lab (PNNL) and show the results obtained from each technique. The first is an in-house method that allows for on demand production of two of these isotopes, Xe-133 and Xe-135, using HEU and a modest flux neutron source. The second method uses a research reactor at the Pullman campus of Washington State University to produce Xe-133, Xe-133m and Xe-135.

McIntyre, Justin I.; Pratt, Sharon L.; Bowyer, Ted W.; Cooper, Matthew W.; Hayes, James C.; Heimbigner, Tom R.; Hubbard, Charles W.; Miley, Harry S.; Ripplinger, Mike D.

2008-09-23T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Etching of Graphene Devices with a Helium Ion Beam  

E-Print Network [OSTI]

We report on the etching of graphene devices with a helium ion beam, including in situ electrical measurement during lithography. The etching process can be used to nanostructure and electrically isolate different regions ...

Baugher, Britton William Herb

202

The helium abundances in HgMn and normal stars  

E-Print Network [OSTI]

The parameter-free model of diffusion in the atmospheres of HgMn stars (Michaud 1986; Michaud et al 1979) predicts that helium should sink below the He II ionization zone in order that diffusion of other elements may take place, and that all HgMn stars should have deficits of helium in their photospheres, with a minimum deficit of 0.3 dex. In this study, the Smith & Dworetsky (1993) sample of HgMn stars and normal comparison stars is examined, and the helium abundances determined by spectrum synthesis using echelle spectra taken at Lick Observatory and the AAT. The prediction is confirmed; all HgMn stars are deficient in He by as much as 1.5 dex. Also, two HgMn stars, HR7361 and HR7664, show clear evidence of helium stratification.

M. M. Dworetsky

2004-07-26T23:59:59.000Z

203

Process Options for Nominal 2-K Helium Refrigeration System Designs  

SciTech Connect (OSTI)

Nominal 2-K helium refrigeration systems are frequently used for superconducting radio frequency and magnet string technologies used in accelerators. This paper examines the trade-offs and approximate performance of four basic types of processes used for the refrigeration of these technologies; direct vacuum pumping on a helium bath, direct vacuum pumping using full or partial refrigeration recovery, cold compression, and hybrid compression (i.e., a blend of cold and warm sub-atmospheric compression).

Peter Knudsen, Venkatarao Ganni

2012-07-01T23:59:59.000Z

204

Superfluid helium cryogenic systems for superconducting RF cavities at KEK  

SciTech Connect (OSTI)

Recent accelerator projects at KEK, such as the Superconducting RF Test Facility (STF) for R and D of the International Linear Collider (ILC) project and the compact Energy Recovery Linac (cERL), employ superconducting RF cavities made of pure niobium, which can generate high gradient acceleration field. Since the operation temperature of these cavities is selected to be 2 K, we have developed two 2 K superfluid helium cryogenic systems for stable operation of superconducting RF cavities for each of STF and cERL. These two 2 K superfluid helium cryogenic systems are identical in principle. Since the operation mode of the cavities is different for STF and cERL, i.e. the pulse mode for STF and the continuous wave mode for cERL, the heat loads from the cavities are quite different. The 2 K superfluid helium cryogenic systems mainly consists of ordinary helium liquefiers/refrigerators, 2 K refrigerator cold boxes, helium gas pumping systems and high-performance transfer lines. The 2 K refrigerators and the high-performance transfer lines are designed by KEK. Some superconducting RF cavity cryomodules have been already connected to the 2 K superfluid helium cryogenic systems for STF and cERL respectively, and cooled down to 2 K successfully.

Nakai, H.; Hara, K.; Honma, T.; Hosoyama, K.; Kojima, Y.; Nakanishi, K. [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0033 (Japan); Kanekiyo, T. [Hitachi Plant Technologies, Ltd., Toshima-ku, Tokyo 170-8466 (Japan); Morita, S. [Hitachi Plant Mechanics Co., Ltd., Kudamatsu, Yamaguchi 744-0061 (Japan)

2014-01-29T23:59:59.000Z

205

Energy Profit Ratio Compared  

SciTech Connect (OSTI)

We need more oil energy to take out oil under the ground. Limit resources make us consider other candidates of energy source instead of oil. Electricity shall be the main role more and more like electric vehicles and air conditioners so we should consider electricity generation ways. When we consider what kind of electric power generation is the best or suitable, we should not only power generation plant but whole process from mining to power generation. It is good way to use EPR, Energy Profit Ratio, to analysis which type is more efficient and which part is to do research and development when you see the input breakdown analysis. Electricity by the light water nuclear power plant, the hydrogen power plant and the geothermal power plant are better candidates from EPR analysis. Forecasting the world primly energy supply in 2050, it is said that the demand will be double of the demand in 2000 and the supply will not be able to satisfy the demand in 2050. We should save 30% of the demand and increase nuclear power plants 3.5 times more and recyclable energy like hydropower plants 3 times more. When the nuclear power plants are 3.5 times more then uranium peak will come and we will need breed uranium. I will analysis the EPR of FBR. Conclusion: A) the EPR of NPS in Japan is 17.4 and it is the best of all. B) Many countries will introduce new nuclear power plants rapidly may be 3.5 times in 2050. C) Uranium peak will happen around 2050. (author)

Amano, Osamu [2-11-1, Iwado Kita, Komae-shi, Tokyo 201-8511 (Japan)

2007-07-01T23:59:59.000Z

206

Detecting infiltration and impacts of introduced water using strontium isotopes  

SciTech Connect (OSTI)

Water introduced to surface drainages, such as agricultural and roadway runoff, mine drainage, or coalbed natural gas (CBNG)-produced water, potentially can be of environmental concern. In order to mitigate potential environmental effects, it may be important to be able to trace water discharged to the surface as it infiltrates and interacts with near-surface aquifers. We have chosen to study water withdrawn during CBNG production for isotope tracing in the hyporheic zone because it poses a variety of economic, environmental, and policy issues in the Rocky Mountain states. Ground water quality must be protected as CBNG water is added to semiarid ecosystems. Strontium (Sr) isotopes are effective fingerprints of the aquifer from which water originates. In this study, CBNG water was found to have a higher Sr-87/Sr-86 ratio than the local alluvial aquifer water. This measurable difference allows the strontium isotope ratio and concentration to be used as tracers of CBNG water following its discharge to the surface. The dissolution and mobilization of salts from soil are an important contributor to ground water quality degradation. In the Powder River basin of Wyoming, the soils are calcium carbonate-buffered systems. The chemical similarity of strontium to calcium allows it to substitute into calcium minerals and enabled us to use strontium isotopes to identify calcium salts mobilized from the soil. Strontium isotopes are an effective monitor of the source of ions and the volume and direction of introduced water flow in the hyporheic zone.

Brinck, E.L.; Frost, C.D. [University of Wyoming, Laramie, WY (United States). Dept. of Geology & Geophysics

2007-09-15T23:59:59.000Z

207

Detection of significant differences between absorption spectra of neutral helium and low temperature photoionized helium plasmas  

SciTech Connect (OSTI)

In this work, spectral investigations of photoionized He plasmas were performed. The photoionized plasmas were created by irradiation of helium stream, with intense pulses from laser-plasma extreme ultraviolet (EUV) source. The EUV source was based on a double-stream Xe/Ne gas-puff target irradiated with 10 ns/10 J Nd:YAG laser pulses. The most intense emission from the source spanned a relatively narrow spectral region below 20 nm, however, spectrally integrated intensity at longer wavelengths was also significant. The EUV radiation was focused onto a gas stream, injected into a vacuum chamber synchronously with the EUV pulse. The long-wavelength part of the EUV radiation was used for backlighting of the photoionized plasmas to obtain absorption spectra. Both emission and absorption spectra in the EUV range were investigated. Significant differences between absorption spectra acquired for neutral helium and low temperature photoionized plasmas were demonstrated for the first time. Strong increase of intensities and spectral widths of absorption lines, together with a red shift of the K-edge, was shown.

Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Fok, T.; Jarocki, R.; Szczurek, M. [Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)] [Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

2013-11-15T23:59:59.000Z

208

Fragment Isotope Distributions and the Isospin Dependent Equation of State  

E-Print Network [OSTI]

Calculations predict a connection between the isotopic composition of particles emitted during an energetic nucleus-nucleus collision and the density dependence of the asymmetry term of the nuclear equation of state (EOS). This connection is investigated for central 112Sn+112Sn and 124Sn+124Sn collisions at E/A=50 MeV in the limit of an equilibrated freezeout condition. Comparisons between measured isotopic yields ratios and theoretical predictions in the equilibrium limit are used to assess the sensitivity to the density dependence of the asymmetry term of the EOS. This analysis suggests that such comparisons may provide an opportunity to constrain the asymmetry term of the EOS.

W. P. Tan; B-A. Li; R. Donangelo; C. K. Gelbke; M-J. van Goetherm; X. D. Liu; W. G. Lynch; S. Souza; M. B. Tsang; G. Verde; A. Wagner; N. S. Xu

2001-04-21T23:59:59.000Z

209

Investigation of particle diffusion and suprathermal electrons in a magnetized helium plasma column  

SciTech Connect (OSTI)

Studying radiative properties of magnetized helium plasma via high-resolution spectroscopy identified close correlations between the particle diffusion and suprathermal electrons for different modes of operation of the MISTRAL installation. The standard diagnostic emission lines in neutral helium (1s3d {sup 3}D-1s2p {sup 3}P, 1s3s {sup 3}S-1s2p {sup 3}P, 1s3d {sup 1}D-1s2p {sup 1}P, and 1s3s {sup 1}S-1s2p {sup 1}P) show anomalous ratios that are related to enhanced particle diffusion and suprathermal electron generation. The supplementary investigation of singlet/triplet Rydberg series (transitions 1snd {sup 3}D-1s2p {sup 3}P and 1s5p {sup 1}P-1s2s {sup 1}S) as well as ionic lines (HeII, transitions n?=?3–4 at 469?nm and n?=?4–6 at 656?nm) allowed quantitative characterization. Simulations carried out with the atomic physics code SOPHIA demonstrate that simultaneous implementation of diffusion processes and suprathermal electrons matches all experimental findings. Single consideration, however, of either diffusion or hot electrons is in contradiction to the proposed extended set of HeI and HeII emission lines. The high precision achieved with the LSJ-split level structure of SOPHIA coupled to Langmuir probe measurements allowed to conclude to a Bohm type diffusion in MISTRAL.

Lefevre, T.; Escarguel, A.; Stamm, R.; Godbert-Mouret, L. [Aix-Marseille Université, CNRS, PIIM UMR 7345, F13397 CEDEX 20, Marseille (France)] [Aix-Marseille Université, CNRS, PIIM UMR 7345, F13397 CEDEX 20, Marseille (France); Rosmej, F. B. [Sorbonne Universités, Pierre et Marie Curie, UMR 7605, LULI, case 128, 4 place Jussieu, F-75252 Paris Cedex 05 (France) [Sorbonne Universités, Pierre et Marie Curie, UMR 7605, LULI, case 128, 4 place Jussieu, F-75252 Paris Cedex 05 (France); LULI, Ecole Polytechnique, CNRS, CEA, Physique Atomique dans les Plasmas Denses PAPD, Route de Saclay, F-91128 Palaiseau (France)

2014-02-15T23:59:59.000Z

210

Spectra of helium clusters with up to six atoms using soft-core potentials  

SciTech Connect (OSTI)

In this paper, we investigate small clusters of helium atoms using the hyperspherical harmonic basis. We consider systems with A=2,3,4,5,6 atoms with an interparticle potential which does not present a strong repulsion at short distances. We use an attractive Gaussian potential that reproduces the values of the dimer binding energy, the atom-atom scattering length, and the effective range obtained with one of the widely used He-He interactions, the Aziz and Slaman potential, called LM2M2. In systems with more than two atoms, we consider a repulsive three-body force that, by construction, reproduces the trimer binding energy of the LM2M2 potential. With this model, consisting of the sum of a two- and three-body potential, we have calculated the spectrum of clusters formed by four, five, and six helium atoms. We have found that these systems present two bound states, one deep and one shallow, close to the threshold fixed by the energy of the (A-1)-atom system. Universal relations between the energies of the excited state of the A-atom system and the ground-state energy of the (A-1)-atom system are extracted, as well as the ratio between the ground state of the A-atom system and the ground-state energy of the trimer.

Gattobigio, M. [Universite de Nice-Sophia Antipolis, Institut Non-Lineaire de Nice, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France); Kievsky, A.; Viviani, M. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, I-56100 Pisa (Italy)

2011-11-15T23:59:59.000Z

211

OPTIMAL DESIGN AND OPERATION OF HELIUM REFRIGERATION SYSTEMS USING THE GANNI CYCLE  

SciTech Connect (OSTI)

The constant pressure ratio process, as implemented in the floating pressure - Ganni cycle, is a new variation to prior cryogenic refrigeration and liquefaction cycle designs that allows for optimal operation and design of helium refrigeration systems. This cycle is based upon the traditional equipment used for helium refrigeration system designs, i.e., constant volume displacement compression and critical flow expansion devices. It takes advantage of the fact that for a given load, the expander sets the compressor discharge pressure and the compressor sets its own suction pressure. This cycle not only provides an essentially constant system Carnot efficiency over a wide load range, but invalidates the traditional philosophy that the (‘TS’) design condition is the optimal operating condition for a given load using the as-built hardware. As such, the Floating Pressure- Ganni Cycle is a solution to reduce the energy consumption while increasing the reliability, flexibility and stability of these systems over a wide operating range and different operating modes and is applicable to most of the existing plants. This paper explains the basic theory behind this cycle operation and contrasts it to the traditional operational philosophies presently used.

Venkatarao Ganni, Peter Knudsen

2010-04-01T23:59:59.000Z

212

Isotopes Tell Origin and Operation of the Sun  

E-Print Network [OSTI]

The Iron Sun formed on the collapsed core of a supernova and now acts as a magnetic plasma diffuser, as did the precursor star, separating ions by mass. This process covers the solar surface with lightweight elements and with lighter isotopes of each element. Running difference images expose rigid, iron-rich structures below the fluid photosphere made of lightweight elements. The energy source for the Sun and ordinary stars seems to be neutron-emission and neutron-decay, with partial fusion of the decay product, rather than simple fusion of hydrogen into helium or heavier elements. Neutron-emission from the solar core and neutron-decay generate about sixty five percent of solar luminosity and H-fusion generates about thirty-five percent. The upward flow of H ions maintains mass-separation in the Sun. Only about one percent of this neutron decay product survives its upward journey to depart as solar-wind hydrogen.

O. Manuel; Sumeet A. Kamat; Michael Mozina

2005-09-28T23:59:59.000Z

213

Asteroseismic determination of helium abundance in stellar envelopes  

E-Print Network [OSTI]

Intermediate degree modes of the solar oscillations have previously been used to determine the solar helium abundance to a high degree of precision. However, we cannot expect to observe such modes in other stars. In this work we investigate whether low degree modes that should be available from space-based asteroseismology missions can be used to determine the helium abundance, Y, in stellar envelopes with sufficient precision. We find that the oscillatory signal in the frequencies caused by the depression in \\Gamma_1 in the second helium ionisation zone can be used to determine the envelope helium abundance of low mass main sequence stars. For frequency errors of 1 part in 10^4, we expect errors \\sigma_Y in the estimated helium abundance to range from 0.03 for 0.8M_sun stars to 0.01 for 1.2M_sun stars. The task is more complicated in evolved stars, such as subgiants, but is still feasible if the relative errors in the frequencies are less than 10^{-4}.

Sarbani Basu; Anwesh Mazumdar; H. M Antia; Pierre Demarque

2004-02-15T23:59:59.000Z

214

Coexistence of superfluid and solid helium in aerogel  

SciTech Connect (OSTI)

The results of recent neutron scattering studies of solid helium in silica aerogel are discussed. Previously I.V. Kalinin et al., Pis'ma Zh. Eksp. Teor. Fiz. 87 (1), 743 (2008) [JETP Lett. 87 (1), 645 (2008)], we detected the existence of a superfluid phase in solid helium at a temperature below 0.6 K and a pressure of 51 bar, although, according to the phase diagram, helium should be in the solid state under these conditions. This work is a continuation of the above studies whose main goal was to examine the detected phenomenon and to establish basic parameters of the existence of a superfluid phase. We have determined the temperature of the superfluid transition from solid to superfluid helium, T{sub C} = 1.3 K, by analyzing experimental data. The superfluid phase excitation parameters (lifetime, intensity, and energy) have a temperature dependence similar to that of bulk helium. The superfluid phase coexists with the solid phase in the entire measured temperature range from T = 0.05 K to T{sub C} and is a nonequilibrium one and disappears at T{sub C}.

Kalinin, I. V. [Institute for Physics and Power Engineering (Russian Federation); Kats, E. I.; Koza, M. [Institut Laue-Langevin (France); Lauter, V. V. [Oak Ridge National Laboratory (United States); Lauter, H. [Institut Laue-Langevin (France); Puchkov, A. V., E-mail: puchkov@ippe.r [Institute for Physics and Power Engineering (Russian Federation)

2010-08-15T23:59:59.000Z

215

ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.  

SciTech Connect (OSTI)

The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

BULLOCK,R.M.; BENDER,B.R.

2000-12-01T23:59:59.000Z

216

Laser isotope separation of erbium and other isotopes  

DOE Patents [OSTI]

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of .sup.167 Er. The hyperfine structure of .sup.167 Er was used to find two three-step photoionization pathways having a common upper energy level.

Haynam, Christopher A. (3035 Ferdale Ct., Pleasanton, CA 94566); Worden, Earl F. (117 Vereda del Ciervo, Diablo, CA 94528)

1995-01-01T23:59:59.000Z

217

investigating the source, transport, and isotope fractionation of water vapor in the atmospheric boundary layer  

E-Print Network [OSTI]

investigating the source, transport, and isotope fractionation of water vapor in the atmospheric-portable mixing ratio generator and Rayleigh distillation device, Agricultural and Forest Meteorology, 150, 1607 ratio generator. Incom- ing dry air passes through a molecular sieve and then a stainless steel frit (a

Minnesota, University of

218

Water isotopes and the general circulation  

E-Print Network [OSTI]

is depleted. #12;Distillation: vapor and condensate Isotopic fractionation -35 -30 -25 -20 -15 -10 -5 0 5 0 0 of idealized isotopic fractionation Expression of isotopic fractionation in nature Attributing signals" 18 = (R/Rstandard-1)x1000 R = moles of H2 18O/moles of H2 16O #12;Isotopic fractionation Isotopic

Noone, David

219

Helium and mercury in the central Seward Peninsula  

SciTech Connect (OSTI)

The central Seward Peninsula, Alaska, has one Known Geothermal Resource Area (KGRA) at Pilgrim Springs, and has recent volcanic flows, fault systems, topographic and tectonic features which can be explained by a rift model. As part of a geothermal reconnaissance of the area we used helium and mercury concentrations in soil as indicators of geothermal resources. The largest helium concentrations were found in the vicinity of the Pilgrims Springs KGRA, and indicate prime drilling sites. Five profile lines were run across the suspected rift system. Significant helium anomalies were found on several of the traverses, where future exploration might be concentrated. Mercury values showed a great range of variability on the traverses, and seem unreliable as geothermal indicators except in the vicinity of the Pilgrim Springs. Permafrost at the surface resulting in variations in sampling depth may contribute to the mercury variations.

Wescott, E.; Ruscetta, C.A.; Foley, D. (eds.)

1981-05-01T23:59:59.000Z

220

A cryogenic axial-centrifugal compressor for superfluid helium refrigeration  

E-Print Network [OSTI]

CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.

Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L

1997-01-01T23:59:59.000Z

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221

Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction  

SciTech Connect (OSTI)

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ?375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (?Sr SW = +13.8 to +41.6, where ?Sr SW is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

Elizabeth C. Chapman,† Rosemary C. Capo,† Brian W. Stewart,*,† Carl S. Kirby,‡ Richard W. Hammack,§

2012-02-24T23:59:59.000Z

222

Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction  

SciTech Connect (OSTI)

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of 375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (?{sub Sr}{sup SW} = +13.8 to +41.6, where ?{sub Sr}{sup SW} is the deviation of the {sup 87}Sr/{sup 86}Sr ratio from that of seawater in parts per 10{sup 4}); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

Chapman, Elizabeth C; Capo, Rosemary C.; Stewart, Brian W.; Kirby, Carl S.; Hammack, Richard W.; Schroeder, Karl T.; Edenborn, Harry M.

2012-03-20T23:59:59.000Z

223

Spectroscopy of barium atoms in liquid and solid helium matrices  

SciTech Connect (OSTI)

We present an exhaustive overview of optical absorption and laser-induced fluorescence lines of Ba atoms in liquid and solid helium matrices in visible and near-infrared spectral ranges. Due to the increased density of isolated atoms, we have found a large number of spectral lines that were not observed in condensed helium matrices before. We have also measured the lifetimes of metastable states. The lowest {sup 3}D{sub 1} metastable state has lifetime of 2.6 s and can be used as an intermediate state in two-step excitations of high-lying states. Various matrix-induced radiationless population transfer channels have been identified.

Lebedev, V.; Moroshkin, P.; Weis, A. [Departement de Physique, Universite de Fribourg, Chemin du Musee 3, CH-1700 Fribourg (Switzerland)

2011-08-15T23:59:59.000Z

224

Supercritical Helium Cooling of the LHC Beam Screens  

E-Print Network [OSTI]

The cold mass of the LHC superconducting magnets, operating in pressurised superfluid helium at 1.9 K, must be shielded from the dynamic heat loads induced by the circulating particle beams, by means of beam screens maintained at higher temperature. The beam screens are cooled between 5 and 20 K by forced flow of weakly supercritical helium, a solution which avoids two-phase flow in the long, narr ow cooling channels, but still presents a potential risk of thermohydraulic instabilities. This problem has been studied by theoretical modelling and experiments performed on a full-scale dedicated te st loop.

Hatchadourian, E; Tavian, L

1998-01-01T23:59:59.000Z

225

White Dwarfs in NGC 6791: Avoiding the Helium Flash  

E-Print Network [OSTI]

We propose that the anomalously bright white dwarf luminosity function observed in NGC 6791 (Bedin et al 2005) is the consequence of the formation of 0.5 Msun white dwarfs with Helium cores instead of Carbon cores. This may happen if mass loss during the ascent of the Red Giant Branch is strong enough to prevent a star from reaching the Helium flash. Such a model can explain the slower white dwarf cooling (relative to standard models) and fits naturally with scenarios advanced to explain Extreme Horizontal Branch stars, a population of which are also found in this cluster.

Brad Hansen

2005-07-12T23:59:59.000Z

226

Isotopic Scaling and the Symmetry Energy in Spectator Fragmentation  

E-Print Network [OSTI]

Isotopic effects in the fragmentation of excited target residues following collisions of $^{12}$C on $^{112,124}$Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4$\\pi$ detector. The measured yield ratios for light particles and fragments with atomic number $Z \\leq$ 5 obey the exponential law of isotopic scaling. The deduced scaling parameters decrease with increasing centrality to values as low as $\\alpha = 0.25 \\pm 0.02$ for the central event group at 600 MeV per nucleon. Symmetry term coefficients, deduced from these data within the statistical description of isotopic scaling, are near $\\gamma =$ 25 MeV for peripheral and $\\gamma <$ 10 MeV for central collisions.

Auger, G; Begemann-Blaich, M L; Bellaize, N; Bittiger, R; Bocage, F; Borderie, B; Bougault, R; Bouriquet, B; Charvet, J L; Chbihi, A; Dayras, R; Durand, D; Frankland, J D; Galíchet, E; Gourio, D; Guinet, D; Hudan, S; Imme, G; Lautesse, P; Lavaud, F; Legrain, R; López, O; Lynen, U; Müller, W F J; Nalpas, L; Orth, H; Plagnol, E; Raciti, G; Rosato, E; Saija, A; Schwarz, C; Seidel, W; Sfienti, C; Tamain, B; Trautmann, W; Trzcinski, A; Turzó, K; Vient, E; Vigilante, M; Volant, C; Zwieglinski, B; Botvina, A S; The INDRA Collaboration

2004-01-01T23:59:59.000Z

227

High-Resolution Triple Resonance Autoionization of Uranium Isotopes  

SciTech Connect (OSTI)

The near-threshold autoionization (AI) spectrum of uranium has been investigated by triple-resonance excitation with single-mode continuous lasers. Spectra were recorded over the first {approx}30 cm-1 above the first ionization limit at a resolution of 3x10-4 cm 1 using intermediate states with different J values (6, 7, 8) to assign AI level total angular momentum JAI = 5 to 9. Resonances with widths ranging from 8 MHz to 30 GHz were observed; the strongest ones have JAI = 9 and widths of {approx} 60 MHz. Hyperfine structures for 235U and isotope shifts for 234,235U have been measured in the two intermediate levels and in the final AI level for the most favorable excitation path. These measurements were performed using aqueous samples containing sub-milligram quantities of uranium at natural isotopic abundances, indicating the potential of this approach for trace isotope ratio determinations.

Schumann, Philipp G.; Wendt, K; Bushaw, Bruce A.

2005-11-01T23:59:59.000Z

228

Implications of Fast Reactor Transuranic Conversion Ratio  

SciTech Connect (OSTI)

Theoretically, the transuranic conversion ratio (CR), i.e. the transuranic production divided by transuranic destruction, in a fast reactor can range from near zero to about 1.9, which is the average neutron yield from Pu239 minus 1. In practice, the possible range will be somewhat less. We have studied the implications of transuranic conversion ratio of 0.0 to 1.7 using the fresh and discharge fuel compositions calculated elsewhere. The corresponding fissile breeding ratio ranges from 0.2 to 1.6. The cases below CR=1 (“burners”) do not have blankets; the cases above CR=1 (“breeders”) have breeding blankets. The burnup was allowed to float while holding the maximum fluence to the cladding constant. We graph the fuel burnup and composition change. As a function of transuranic conversion ratio, we calculate and graph the heat, gamma, and neutron emission of fresh fuel; whether the material is “attractive” for direct weapon use using published criteria; the uranium utilization and rate of consumption of natural uranium; and the long-term radiotoxicity after fuel discharge. For context, other cases and analyses are included, primarily once-through light water reactor (LWR) uranium oxide fuel at 51 MWth-day/kg-iHM burnup (UOX-51). For CR<1, the heat, gamma, and neutron emission increase as material is recycled. The uranium utilization is at or below 1%, just as it is in thermal reactors as both types of reactors require continuing fissile support. For CR>1, heat, gamma, and neutron emission decrease with recycling. The uranium utilization exceeds 1%, especially as all the transuranic elements are recycled. exceeds 1%, especially as all the transuranic elements are recycled. At the system equilibrium, heat and gamma vary by somewhat over an order of magnitude as a function of CR. Isotopes that dominate heat and gamma emission are scattered throughout the actinide chain, so the modest impact of CR is unsurprising. Neutron emitters are preferentially found among the higher actinides, so the neutron emission varies much stronger with CR, about three orders of magnitude.

Steven J. Piet; Edward A. Hoffman; Samuel E. Bays

2010-11-01T23:59:59.000Z

229

Microsoft PowerPoint - Module 10c - Helium Purification and Supply...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

- Requirements - Design approach - Design description * Helium Transfer and Storage System (HT&SS) design design - Functions - Design description Design description *...

230

Half-life and gamma abundance ratio measurements of Sm-153  

SciTech Connect (OSTI)

The measurement of the decay of 153Sm was observed by gamma spectrometry, liquid scintillation counting and gas proportional counting in an attempt to confirm the half life and gamma abundance ratios for this isotope. Recent changes in the published nuclear decay data indicate that historical literature values may be biased. The 153Sm was made by the neutron activation of ultrapure isotopically enriched 152Sm to create 153Sm. The decay measurements were made over a three week period and no other isotopes were detected during this time. The gamma abundance ratio for the 103 keV gamma was measured to be (27.9%) which is 4% lower than the published data. In addition, the half life was 1.9308 days, which is 0.34% lower than the published data.

Friese, Judah I.; Payne, Rosara F.; Greenwood, Lawrence R.; Soderquist, Chuck Z.; Garofoli, Stephanie J.

2009-11-02T23:59:59.000Z

231

RADIOCHEMICAL STUDIES OF NEUTRON DEFICIENT ACTINIDE ISOTOPES  

E-Print Network [OSTI]

Isotope Targets and Foils, AERE-R 5097, Paper 10 (1965). V.Isotope Targets and Foils, AERE-R 5097 Paper 12 (1965). K.M.Isotope Targets and Foils, AERE-R-5097 Paper 11 (1965). M.

Williams, Kimberly Eve

2011-01-01T23:59:59.000Z

232

DESIGN OPTIMIZATION OF HIGH-PERFORMANCE HELIUM-COOLED DIVERTOR PLATE CONCEPT  

E-Print Network [OSTI]

DESIGN OPTIMIZATION OF HIGH-PERFORMANCE HELIUM-COOLED DIVERTOR PLATE CONCEPT X.R. Wanga , S Consulting, Fliederweg 3, 76351 Linkenheim, Germany A helium-cooled plate-type divertor design concept has of the concept in the high heat flux zone. This paper describes the design optimization of the helium

Raffray, A. René

233

Chromatographic hydrogen isotope separation  

DOE Patents [OSTI]

Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

Aldridge, Frederick T. (Livermore, CA)

1981-01-01T23:59:59.000Z

234

Development of high through-put Sr isotope analysis for monitoring reservoir integrity for CO{sub 2} storage.  

SciTech Connect (OSTI)

Recent innovations in multi-collector ICP-mass spectrometry (MC-ICP-MS) have allowed for rapid and precise measurements of isotope ratios in geological samples. Naturally occurring Sr isotopes has the potential for use in Monitoring, Verification, and Accounting (MVA) associated with geologic CO2 storage. Sr isotopes can be useful for: Sensitive tracking of brine migration; Determining seal rock leakage; Studying fluid/rock reactions. We have optimized separation chemistry procedures that will allow operators to prepare samples for Sr isotope analysis off site using rapid, low cost methods.

Wall, Andy; Jain, Jinesh; Stewart, Brian; Capo, Rosemary; Hakala, Alexandra J.; Hammack, Richard; Guthrie, George

2012-01-01T23:59:59.000Z

235

Isotopic Trends in Production of Superheavies  

SciTech Connect (OSTI)

The isotopic trends are discussed for cold and hot fusion reactions leading to superheavies. The possibilities of production of new isotopes in incomplete fusion reactions are treated.

Antonenko, N.V. [Institut fuer Theoretische Physik der Justus-Liebig-Universitaet, D-35392 Giessen (Germany); Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Adamian, G.G.; Zubov, A.S. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Scheid, W. [Institut fuer Theoretische Physik der Justus-Liebig-Universitaet, D-35392 Giessen (Germany)

2005-11-21T23:59:59.000Z

236

The marine biogeochemistry of zinc isotopes  

E-Print Network [OSTI]

Zinc (Zn) stable isotopes can record information about important oceanographic processes. This thesis presents data on Zn isotopes in anthropogenic materials, hydrothermal fluids and minerals, cultured marine phytoplankton, ...

John, Seth G

2007-01-01T23:59:59.000Z

237

The Electrical Conductivity Of Partly Ionized Helium Plasma  

SciTech Connect (OSTI)

In this paper we analyzed atoms influence on electro conductivity, partially ionized helium plasma, in temperature region 5 000 K - 40 000 K and pressure 0.1 - 10 atm. Electro conductivity was calculated using 'Frost like' formula and Random Phase Approximation method and Semi-Classical (SC) approximation.

Sreckovic, Vladimir A.; Ignjatovic, Ljubinko; Mihajlov, A. A. [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro)

2007-04-23T23:59:59.000Z

238

TRANSMISSION ELECTRON MICROSCOPY STUDY OF HELIUM BEARING FUSION WELDS  

SciTech Connect (OSTI)

A transmission electron microscopy (TEM) study was conducted to characterize the helium bubble distributions in tritium-charged-and-aged 304L and 21Cr-6Ni-9Mn stainless steel fusion welds containing approximately 150 appm helium-3. TEM foils were prepared from C-shaped fracture toughness test specimens containing {delta} ferrite levels ranging from 4 to 33 volume percent. The weld microstructures in the low ferrite welds consisted mostly of austenite and discontinuous, skeletal {delta} ferrite. In welds with higher levels of {delta} ferrite, the ferrite was more continuous and, in some areas of the 33 volume percent sample, was the matrix/majority phase. The helium bubble microstructures observed were similar in all samples. Bubbles were found in the austenite but not in the {delta} ferrite. In the austenite, bubbles had nucleated homogeneously in the grain interiors and heterogeneously on dislocations. Bubbles were not found on any austenite/austenite grain boundaries or at the austenite/{delta} ferrite interphase interfaces. Bubbles were not observed in the {delta} ferrite because of the combined effects of the low solubility and rapid diffusion of tritium through the {delta} ferrite which limited the amount of helium present to form visible bubbles.

Tosten, M; Michael Morgan, M

2008-12-12T23:59:59.000Z

239

Communication: Barium ions and helium nanodroplets: Solvation and desolvation  

SciTech Connect (OSTI)

The solvation of Ba{sup +} ions created by the photoionization of barium atoms located on the surface of helium nanodroplets has been investigated. The excitation spectra corresponding to the 6p {sup 2}P{sub 1/2} Leftwards-Arrow 6s {sup 2}S{sub 1/2} and 6p {sup 2}P{sub 3/2} Leftwards-Arrow 6s {sup 2}S{sub 1/2} transitions of Ba{sup +} are found to be identical to those recorded in bulk He II [H. J. Reyher, H. Bauer, C. Huber, R. Mayer, A. Schafer, and A. Winnacker, Phys. Lett. A 115, 238 (1986)], indicating that the ions formed at the surface of the helium droplets become fully solvated by the helium. Time-of-flight mass spectra suggest that following the excitation of the solvated Ba{sup +} ions, these are being ejected from the helium droplets either as bare Ba{sup +} ions or as small Ba{sup +}He{sub n} (n < 20) complexes.

Zhang Xiaohang; Drabbels, Marcel [Laboratoire de Chimie Physique Moleculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2012-08-07T23:59:59.000Z

240

Quantum mechanicallycomplete measurements in electron impact excitation of helium  

E-Print Network [OSTI]

Centre for Atomic, Molecular and Surface Physics, Physics Department, The University of Western Australia, Nedlands, Perth. 6907, Australia. Abstract. A complete quantum description of the 3! D state of helium cascading photons (667.8 nm 3] D ->2'P and 58.4 nm 21 P-»11 S transitions) and the scattered n = 3 energy

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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241

Turbulent Mixing on Helium-Accreting White Dwarfs  

E-Print Network [OSTI]

An attractive scenario for producing Type Ia supernovae (SNe Ia) is a double detonation, where detonation of an accreted helium layer triggers ignition of a C/O core. Whether or not such a mechanism can explain some or most SNe Ia depends on the properties of the helium burning, which in turn is set by the composition of the surface material. Using a combination of semi-analytic and simple numerical models, I explore when turbulent mixing due to hydrodynamic instabilities during the accretion process can mix C/O core material up into the accreted helium. Mixing is strongest at high accretion rates, large white dwarf (WD) masses, and slow spin rates. The mixing would result in subsequent helium burning that better matches the observed properties of SNe Ia. In some cases, there is considerable mixing that can lead to more than 50% C/O in the accreted layer at the time of ignition. These results will hopefully motivate future theoretical studies of such strongly mixed conditions. Mixing also has implications for...

Piro, Anthony L

2015-01-01T23:59:59.000Z

242

Helium-cooled solid breeder blanket for ITER  

SciTech Connect (OSTI)

This paper summarizes the latest results of a design study of a helium-cooled solid breeder blanket for ITER. Attractive features of this design include the following: (1) There is a significant design margin since only part of the allowable solid breeder temperature window needs to be used. (2) There is an expanding data base available from solid breeder experiments carried out internationally. (3) The solid breeder can be designed to operate at high reactor-relevant temperature, while the helium is kept at moderate temperature and pressure for safety and reliability. In addition, since helium is a gas, it can be run so as to optimize the structure temperature and accommodate long term power variation without incurring any substantial pressure penalty. (4) The use of helium, an inert gas minimizing any chemical reaction and corrosion, in combination with a low activation solid breeder, is a safety advantage. An extensive list of the blanket operating parameters is provided and key factors are discussed.

Raffray, A.R.; Abdou, M.A.; Chou, P.; Gorbis, Z.; Tillack, M.; Watanabe, Y.; Ying, A.

1989-03-01T23:59:59.000Z

243

High ratio recirculating gas compressor  

DOE Patents [OSTI]

A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.

Weinbrecht, J.F.

1989-08-22T23:59:59.000Z

244

NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES  

SciTech Connect (OSTI)

We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61}, or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the {sup 58}Ni/{sup 61}Ni internally normalized {sup 60}Ni/{sup 61}Ni, {sup 62}Ni/{sup 61}Ni, and {sup 64}Ni/{sup 61}Ni ratios. The chondrites show a range of 0.15, 0.29, and 0.84 in {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61} relative to a typical sample precision of 0.03, 0.05, and 0.08 (2 s.e.), respectively. The carbonaceous chondrites show the largest positive anomalies, enstatite chondrites have approximately terrestrial ratios, though only EH match Earth's composition within uncertainty, and ordinary chondrites show negative anomalies. The meteorite data show a strong positive correlation between {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}, an extrapolation of which is within the error of the average of previous measurements of calcium-, aluminium-rich inclusions. Moreover, the slope of this bulk meteorite array is 3.003 {+-} 0.166 which is within the error of that expected for an anomaly solely on {sup 58}Ni. We also determined to high precision ({approx}10 ppm per AMU) the mass-dependent fractionation of two meteorite samples which span the range of {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}. These analyses show that 'absolute' ratios of {sup 58}Ni/{sup 61}Ni vary between these two samples whereas those of {sup 62}Ni/{sup 61}Ni and {sup 64}Ni/{sup 61}Ni do not. Thus, Ni isotopic differences seem most likely explained by variability in the neutron-poor {sup 58}Ni, and not correlated anomalies in the neutron-rich isotopes, {sup 62}Ni and {sup 64}Ni. This contrasts with previous inferences from mass-independent measurements of Ni and other transition elements which invoked variable contributions of a neutron-rich component. We have examined different nucleosynthetic environments to determine the possible source of the anomalous material responsible for the isotopic variations observed in Ni and other transition elements within bulk samples. We find that the Ni isotopic variability of the solar system cannot be explained by mixing with a component of bulk stellar ejecta from either SN II, Wolf-Rayet or, an asymptotic giant branch source and is unlikely to result from bulk mixing of material from an SN Ia. However, variable admixture of material from the Si/S zone of an SN II can create all the characteristics of Ni isotope variations in solar system materials. Moreover, these characteristics can also be provided by an SN II with a range of masses from 15 to 40 M{sub Sun }, showing that input from SN II is a robust source for Ni isotope variations in the solar system. Correlations of Ni isotope anomalies with O, Cr, and Ti isotope ratios and Pb/Yb in bulk meteorites suggest that the heterogeneous distribution of isotopic anomalies in the early solar system likely resulted from nebular sorting of chemically or physically different materials bearing different amounts of isotopes synthesized proximally to the collapse of the protosolar nebula.

Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim [Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ (United Kingdom); Russell, Sara, E-mail: r.steele@uclmail.net [Meteoritics and Cosmic mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

2012-10-10T23:59:59.000Z

245

Isotope separation by laser means  

DOE Patents [OSTI]

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

1982-06-15T23:59:59.000Z

246

Instructions for filling liquid Helium for the 800 MHz magnet This is a twoperson job and will require 2 x 100 liter tanks of liquid helium if filling  

E-Print Network [OSTI]

and will require 2 x 100 liter tanks of liquid helium if filling from 207 mm (41%). · Move the ladder to the side and place the helium tank to the right of the leg facing the 500 system and as close to the magnet as possible. · Cut all ties from the helium tanks · Hand tighten the homemade fitting to the vent port

Oliver, Douglas L.

247

Chromium isotopes as indicators of hexavalent chromium reduction  

SciTech Connect (OSTI)

This is the final report for a university research project which advanced development of a new technology for identifying chemical reduction of hexavalent chromium contamination in groundwater systems. Reduction renders mobile and toxic hexavalent chromium immobile and less toxic. The new method uses stable isotope ratio measurements, which are made using multicollector ICP-mass spectrometry. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.

Johnson, Thomas M.

2012-03-20T23:59:59.000Z

248

Beta-decay branching ratios of 62Ga  

E-Print Network [OSTI]

Beta-decay branching ratios of 62Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyvaskyla. 62Ga is one of the heavier Tz = 0, 0+ -> 0+ beta-emitting nuclides used to determine the vector coupling constant of the weak interaction and the Vud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of 62Ga. The branching ratio obtained, BR= 99.893(24)%, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed beta decay of 62Ga.

A. Bey; B. Blank; G. Canchel; C. Dossat; J. Giovinazzo; I. Matea; V. Elomaa; T. Eronen; U. Hager; M. Hakala; A. Jokinen; A. Kankainen; I. Moore; H. Penttila; S. Rinta-Antila; A. Saastamoinen; T. Sonoda; J. Aysto; N. Adimi; G. De France; J. C. Thomas; G. Voltolini; T. Chaventré

2008-04-17T23:59:59.000Z

249

Cold Vacuum Drying (CVD) Facility General Service Helium System Design Description  

SciTech Connect (OSTI)

The purpose of this System Design Description (SDD) is to describe the characteristics of the Cold Vacuum Drying (CVD) Facility general service helium system. The general service helium system is a general service facility process support system, but does include safety-class structures, systems and components (SSCs) providing protection to the offsite public. The general service helium system also performs safety-significant functions that provide protection to onsite workers. The general helium system essential function is to provide helium (He) to support process functions during all phases of facility operations. General service helium is used to purge the cask and the MCO in order to maintain their internal atmospheres below hydrogen flammability concentrations. The general service helium system also supplies helium to purge the process water conditioning (PWC) lines and components and the vacuum purge system (VPS) vacuum pump. The general service helium system, if available following an Safety Class Instrument and Control System (SCIC) Isolation and Purge (IS0 and PURGE) Trip, can provide an alternate general service helium system source to supply the Safety-Class Helium (SCHe) System.

SHAPLEY, B.J.

2000-04-20T23:59:59.000Z

250

Optical Readout Time Projection Chamber (O-TPC) for a Study of Oxygen Formation In Stellar Helium Burning  

E-Print Network [OSTI]

We are developing an Optical Readout Time Projection Chamber (O-TPC) detector for the study of the 12C(a,g)16O reaction that determines the ratio of carbon to oxygen in helium burning. This ratio is crucial for understanding the final fate of a progenitor star and the nucleosynthesis of elements prior to a Type II supernova; an oxygen rich star is predicted to collapse to a black hole, and a carbon rich star to a neutron star. Type Ia supernovae (SNeIa) are used as standard candles for measuring cosmological distances with the use of an empirical light curve-luminosity stretching factor. It is essential to understand helium burning that yields the carbon/oxygen white dwarf and thus the initial stage of SNeIa. The O-TPC is intended for use with high intensity photon beams extracted from the HIgS/TUNL facility at Duke University to study the 16O(g,a)12C reaction, and thus the direct reaction at energies as low as 0.7 MeV. We are conducting a systematical study of the best oxygen containing gas with light emitting admixture(s) for use in such an O-TPC. Preliminary results with CO_2 + TEA mixture were obtained

Moshe Gai; Amos Breskin; Rachel Chechik; Volker Dangendorf; Henry R. Weller

2005-04-01T23:59:59.000Z

251

Effects of Temperature on the Interactions of Helium-Vacancy Clusters with Gliding Edge Dislocations in ?-Fe  

SciTech Connect (OSTI)

The interaction of helium-vacancy (He-V) clusters with a gliding a/2<111>{110} edge dislocation in a-Fe is investigated by molecular dynamics methods under a constant strain rate at temperatures of 100 to 600 K. A number of small HenVm (n/m = 0~4) clusters initially placed at different positions relative to the slip plane are comparatively studied. The results show that the interaction of He-V clusters with gliding edge dislocations depends on the helium-to-vacancy (He/V) ratio, the position of the clusters relative to the slip plane, the cluster size, and also temperature. The obstacle strength of the He-V clusters relevant to the dislocation motion generally increases with increasing He/V ratio at the same temperature, but decreases slightly with increasing temperature for the same He-V cluster. One of the interesting results is that He-V clusters do not move along with the dislocation, even at 600 K.

Yang, Li; Zhu, Zi Qiang; Peng, SM; Long, XG; Zhou, X. S.; Zu, Xiaotao; Heinisch, Howard L.; Kurtz, Richard J.; Gao, Fei

2013-10-15T23:59:59.000Z

252

Isotopic consequences of consumer food choice: Hydrogen and oxygen stable isotope ratios in foods from fast food restaurants versus supermarkets  

E-Print Network [OSTI]

. Erkkila a,b , Thure E. Cerling a,b,c , James R. Ehleringer a,b a Department of Biology, University of Utah) regions of the USA (Leff, Ramankutty, & Foley, 2004; Monfreda, Ramankutty, & Foley, 2008). The result can

Ehleringer, Jim

253

Stable isotopic investigations of in situ bioremediation of chlorinated organic solvents. 1997 annual progress report  

SciTech Connect (OSTI)

'The author has made significant progress in developing innovative methods for investigating the mechanism and extent of in situ bioremediation of chlorinated organic solvents. These methods use precise isotopic ratio measurements of chlorine and carbon in reactant and product species in laboratory experiments and in materials from field demonstration sites. Specific tasks completed during FY 1997 include: (1) refinement and publication of a new analytical method for precise determination of chlorine and carbon isotope ratios in chlorinated volatile organic compounds; (2) laboratory experiments involving biological degradation of chlorinated solvents in liquid cultures and soil columns; and (3) use of chlorine and carbon isotope ratios to investigate natural attenuation of trichloroethene at the Paducah Gaseous Diffusion Plant. This work can have immediate impact because it will provide the fundamental basis for a new and cost-effective means of evaluating and monitoring the effectiveness of in situ bioremediation schemes for chlorinated organic solvents in soils, vadose horizons, and groundwater plumes.'

Sturchio, N.C.

1997-01-01T23:59:59.000Z

254

AN EXPERIMENTAL STUDY OF THE EFFECTS OF SOLID-TO-COOLANT THERMAL CONDUCTIVITY RATIO IN HELIUM-COOLED DIVERTOR MODULES  

E-Print Network [OSTI]

-7), and the He-cooled modular divertor with integrated pin array (HEMP) (Ref. 8-9). These designs rely on jet

255

Method for laser induced isotope enrichment  

DOE Patents [OSTI]

Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

2004-09-07T23:59:59.000Z

256

Apparatus and process for separating hydrogen isotopes  

DOE Patents [OSTI]

The apparatus and process for separating hydrogen isotopes is provided using dual columns, each column having an opposite hydrogen isotopic effect such that when a hydrogen isotope mixture feedstock is cycled between the two respective columns, two different hydrogen isotopes are separated from the feedstock.

Heung, Leung K; Sessions, Henry T; Xiao, Xin

2013-06-25T23:59:59.000Z

257

Electrochemical Isotope Effect and Lithium Isotope Separation Jay R. Black,  

E-Print Network [OSTI]

results showing a large lithium isotope separation due to electrodeposition. The fractionation is tunable lithium were plated from solutions of 1 M LiClO4 in propylene carbonate (PC) on planar nickel electrodes

Mcdonough, William F.

258

Compelling Research Opportunities using Isotopes  

SciTech Connect (OSTI)

Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1) medicine, pharmaceuticals, and biology, (2) physical sciences and engineering, and (3) national security and other applications. In each area, compelling research opportunities were considered and the subcommittee as a whole determined the final priorities for research opportunities as the foundations for the recommendations. While it was challenging to prioritize across disciplines, our order of recommendations reflect the compelling research prioritization along with consideration of time urgency for action as well as various geopolitical market issues. Common observations to all areas of research include the needs for domestic availability of crucial stable and radioactive isotopes and the education of the skilled workforce that will develop new advances using isotopes in the future. The six recommendations of NSACI reflect these concerns and the compelling research opportunities for potential new discoveries. The science case for each of the recommendations is elaborated in the respective chapters.

None

2009-04-23T23:59:59.000Z

259

Pulsed extraction of ionization from helium buffer gas  

E-Print Network [OSTI]

The migration of intense ionization created in helium buffer gas under the influence of applied electric fields is considered. First the chemical evolution of the ionization created by fast heavy-ion beams is described. Straight forward estimates of the lifetimes for charge exchange indicate a clear suppression of charge exchange during ion migration in low pressure helium. Then self-consistent calculations of the migration of the ions in the electric field of a gas-filled cell at the National Superconducting Cyclotron Laboratory (NSCL) using a Particle-In-Cell computer code are presented. The results of the calculations are compared to measurements of the extracted ion current caused by beam pulses injected into the NSCL gas cell.

D. J. Morrissey; G. Bollen; M. Facina; S. Schwarz

2008-08-13T23:59:59.000Z

260

Source localization of brain activity using helium-free interferometer  

SciTech Connect (OSTI)

To detect extremely small magnetic fields generated by the human brain, currently all commercial magnetoencephalography (MEG) systems are equipped with low-temperature (low-T{sub c}) superconducting quantum interference device (SQUID) sensors that use liquid helium for cooling. The limited and increasingly expensive supply of helium, which has seen dramatic price increases recently, has become a real problem for such systems and the situation shows no signs of abating. MEG research in the long run is now endangered. In this study, we report a MEG source localization utilizing a single, highly sensitive SQUID cooled with liquid nitrogen only. Our findings confirm that localization of neuromagnetic activity is indeed possible using high-T{sub c} SQUIDs. We believe that our findings secure the future of this exquisitely sensitive technique and have major implications for brain research and the developments of cost-effective multi-channel, high-T{sub c} SQUID-based MEG systems.

Dammers, Jürgen, E-mail: J.Dammers@fz-juelich.de; Chocholacs, Harald; Eich, Eberhard; Boers, Frank [Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich (Germany); Faley, Michael; Dunin-Borkowski, Rafal E. [Peter Grünberg Institute (PGI-5), Forschungszentrum Jülich, Jülich (Germany); Jon Shah, N. [Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich (Germany); Department of Neurology, RWTH Aachen University, Aachen (Germany); Jülich Aachen Research Alliance (JARA)—Translational Brain Medicine, Jülich (Germany)

2014-05-26T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor  

E-Print Network [OSTI]

A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

1998-01-01T23:59:59.000Z

262

Acoustical Properties of Superfluid Helium in Confined Geometry  

E-Print Network [OSTI]

The problem studied in this paper is to obtain the equations describing sound propagation in a consolidated porous medium filled with superfluid, determine the elastic coefficients, appearing in the equations, in terms of physically measurable quantities, and calculate the propagation velocities of transverse and longitudinal waves at high and low oscillating frequencies. In general, the obtained equations describe all volume modes that can propagate in a porous medium saturated with superfluid for any values of the porosity and frequencies. The derived equations are applied to the most important particular case when the normal component of superfluid helium is locked inside a highly porous media (aerogel, Im-helium sample) by viscous forces. For this case the velocities of two longitudinal sound modes and transverse mode are calculated from the derived equations. There are established the coupling between temperature and pressure oscillations in these fast and slow modes.

Sh. E. Kekutia; N. D. Chkhaidze

2006-04-07T23:59:59.000Z

263

Electron bubbles in liquid helium: infrared-absorption spectrum  

E-Print Network [OSTI]

Within Density Functional Theory, we have calculated the energy of the transitions from the ground state to the first two excited states in the electron bubbles in liquid helium at pressures from zero to about the solidification pressure. For $^4$He at low temperatures, our results are in very good agreement with infrared absorption experiments. Above a temperature of $\\sim 2$ K, we overestimate the energy of the $1s-1p$ transition. We attribute this to the break down of the Franck-Condon principle due to the presence of helium vapor inside the bubble. Our results indicate that the $1s-2p$ transition energies are sensitive not only to the size of the electron bubble, but also to its surface thickness. We also present results for the infrared transitions in the case of liquid $^3$He, for which we lack of experimental data.

Víctor Grau; Manuel Barranco; Ricardo Mayol; Martí Pi

2006-01-20T23:59:59.000Z

264

Novel hybrid isotope separation scheme and apparatus  

DOE Patents [OSTI]

A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which the specific isotope is to be isolated, radiating the gas with frequencies characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photoionization reaction of the desired isotope, and collecting the specific isotope ion by suitable ion collection means. 3 figures.

Maya, J.

1991-06-18T23:59:59.000Z

265

Novel hybrid isotope separation scheme and apparatus  

DOE Patents [OSTI]

A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which the specific isotope is to be isolated, radiating the gas with frequencies characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photoionization reaction of the desired isotope, and collecting the specific isotope ion by suitable ion collection means.

Maya, Jakob (Brookline, MA)

1991-01-01T23:59:59.000Z

266

Physics with isotopically controlled semiconductors  

SciTech Connect (OSTI)

This paper is based on a tutorial presentation at the International Conference on Defects in Semiconductors (ICDS-25) held in Saint Petersburg, Russia in July 2009. The tutorial focused on a review of recent research involving isotopically controlled semiconductors. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, is the most prominent effect for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples.

Haller, E. E., E-mail: eehaller@lbl.gov [University of California at Berkeley, Department of Materials Science and Engineering (United States)

2010-07-15T23:59:59.000Z

267

Shock compression of liquid helium to 56 GPa (560 kbar)  

SciTech Connect (OSTI)

The first shock-compression experiments on liquid helium are reported. With a two-stage light-gas gun, liquid He at 4.3 K and 1 atm was shocked to 16 GPa and 12 000 K and double shocked to 56 GPa and 21 000 K. Liquid perturbation theory has been used to determine an effective interatomic potential from which the equation of state of He can be obtained over a wide range of densities and temperatures.

Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Trainor, R.J.; Governo, G.K.; Ross, M.; Young, D.A.

1984-09-24T23:59:59.000Z

268

DETERMINING THE INITIAL HELIUM ABUNDANCE OF THE SUN  

SciTech Connect (OSTI)

We determine the dependence of the initial helium abundance and the present-day helium abundance in the convective envelope of solar models (Y {sub ini} and Y {sub surf}, respectively) on the parameters that are used to construct the models. We do so by using reference standard solar models (SSMs) to compute the power-law coefficients of the dependence of Y {sub ini} and Y {sub surf} on the input parameters. We use these dependencies to determine the correlation between Y {sub ini} and Y {sub surf} and use this correlation to eliminate uncertainties in Y {sub ini} from all solar model input parameters except the microscopic diffusion rate. We find an expression for Y {sub ini} that depends only on Y {sub surf} and the diffusion rate. By adopting the helioseismic determination of solar surface helium abundance, Y {sup surf} {sub sun} = 0.2485 {+-} 0.0035, and an uncertainty of 20% for the diffusion rate, we find that the initial solar helium abundance, Y {sup ini} {sub sun}, is 0.278 {+-} 0.006 independently of the reference SSMs (and particularly on the adopted solar abundances) used in the derivation of the correlation between Y {sub ini} and Y {sub surf}. When non-SSMs with extra mixing are used, then we derive Y {sup ini} {sub sun} = 0.273 {+-} 0.006. In both cases, the derived Y {sup ini} {sub sun} value is higher than that directly derived from solar model calibrations when the low-metallicity solar abundances (e.g., by Asplund et al.) are adopted in the models.

Serenelli, Aldo M. [Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, Garching D-85471 (Germany); Basu, Sarbani, E-mail: aldos@mpa-garching.mpg.d [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)

2010-08-10T23:59:59.000Z

269

Mathematical modeling of a Fermilab helium liquefier coldbox  

SciTech Connect (OSTI)

Fermilab Central Helium Liquefier (CHL) facility is operated 24 hours-a-day to supply 4.6{degrees}K for the Fermilab Tevatron superconducting proton-antiproton collider Ring and to recover warm return gases. The centerpieces of the CHL are two independent cold boxes rated at 4000 and 5400 liters/hour with LN{sub 2} precool. These coldboxes are Claude cycle and have identical heat exchangers trains, but different turbo-expanders. The Tevatron cryogenics demand for higher helium supply from CHL was the driving force to investigate an installation of an expansion engine in place of the Joule-Thompson valve. A mathematical model was developed to describe the thermo- and gas-dynamic processes for the equipment included in the helium coldbox. The model is based on a finite element approach, opposite to a global variables approach, thus providing for higher accuracy and conversion stability. Though the coefficients used in thermo- and gas-dynamic equations are unique for a given coldbox, the general approach, the equations, the methods of computations, and most of the subroutines written in FORTRAN can be readily applied to different coldboxes. The simulation results are compared against actual operating data to demonstrate applicability of the model.

Geynisman, M.G.; Walker, R.J.

1995-12-01T23:59:59.000Z

270

Kinematics of the helium accretor GP Com  

E-Print Network [OSTI]

We present time-resolved spectra of the double-degenerate binary star, GP Com. The spectra confirm the presence and period (46.5 min) of the `S'-wave feature found by Nather, Robinson and Stover. GP Com is erratically variable at X-ray and UV wavelengths. We have found the equivalent variability in our data, which, as also seen in UV data, is mostly confined to the emission lines. The HeII 4686 changes by the largest amount, consistent with X-ray driven photo-ionisation. The flaring part of the line profiles is broader than the average, as expected if they are dominated by the inner disc. The HeII 4686 profile is especially remarkable in that its blue-shifted peak is 1400 km/s from line centre compared to 700 km/s for the HeI lines (the red-shifted peak is blended with HeI 4713). We deduce that HeII 4686 emission is confined to the inner 1/4 of the disc. We suggest that the activity of the inner disc indicates that accretion is significant (and unstable) there, in contrast to quiescent dwarf novae, in support of models in which GP Com is in a (quasi-)steady-state of low mass transfer rate. GP Com shows triple-peaked lines profiles which consist of the usual double-peaked profiles from a disc plus a narrow component at line centre. We find evidence for both radial velocity and flux variability in this component, inconsistent with a nebula origin. The radial velocity amplitude and its phase relative to the `S'-wave are consistent with an origin on the accreting white dwarf, if the mass ratio, q = M2/M1, is of order 0.02, as expected on evolutionary grounds. However this explanation is still not satisfactory as the systemic velocity of the narrow component shows significant variation from line to line, and we have no explanation for this.

T. R. Marsh

1998-12-23T23:59:59.000Z

271

Effects of diagenesis on the Nd-isotopic composition of black shales from the 420 Ma Utica Shale Magnafacies  

E-Print Network [OSTI]

-isotopic ratios were measured in whole rock black shales with different grades of thermal maturity from the Utica/Sm that cannot be explained solely by diagenesis, implying source heterogeneity. Whole rock black shales maturation), which alters the Sm/Nd ratio of the rock, it can be argued that the different components

Basu, Asish R.

272

Helium-Based Soundwave Chiller: Trillium: A Helium-Based Sonic Chiller- Tons of Freezing with 0 GWP Refrigerants  

SciTech Connect (OSTI)

BEETIT Project: Penn State is designing a freezer that substitutes the use of sound waves and environmentally benign refrigerant for synthetic refrigerants found in conventional freezers. Called a thermoacoustic chiller, the technology is based on the fact that the pressure oscillations in a sound wave result in temperature changes. Areas of higher pressure raise temperatures and areas of low pressure decrease temperatures. By carefully arranging a series of heat exchangers in a sound field, the chiller is able to isolate the hot and cold regions of the sound waves. Penn State’s chiller uses helium gas to replace synthetic refrigerants. Because helium does not burn, explode or combine with other chemicals, it is an environmentally-friendly alternative to other polluting refrigerants. Penn State is working to apply this technology on a large scale.

None

2010-09-01T23:59:59.000Z

273

Isotope production facility produces cancer-fighting actinium  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Cancer therapy gets a boost from new isotope Isotope production facility produces cancer-fighting actinium A new medical isotope project shows promise for rapidly producing major...

274

Production of carbon monoxide-free hydrogen and helium from a high-purity source  

DOE Patents [OSTI]

The invention provides vacuum swing adsorption processes that produce an essentially carbon monoxide-free hydrogen or helium gas stream from, respectively, a high-purity (e.g., pipeline grade) hydrogen or helium gas stream using one or two adsorber beds. By using physical adsorbents with high heats of nitrogen adsorption, intermediate heats of carbon monoxide adsorption, and low heats of hydrogen and helium adsorption, and by using vacuum purging and high feed stream pressures (e.g., pressures of as high as around 1,000 bar), pipeline grade hydrogen or helium can purified to produce essentially carbon monoxide -free hydrogen and helium, or carbon monoxide, nitrogen, and methane-free hydrogen and helium.

Golden, Timothy Christopher (Allentown, PA); Farris, Thomas Stephen (Bethlehem, PA)

2008-11-18T23:59:59.000Z

275

Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten  

SciTech Connect (OSTI)

To simulate neutron and helium damage in a fusion reactor first wall sequential self-ion implantation up to 13 dpa followed by helium-ion implantation up to 3000 appm was performed to produce damaged layers of {approx}2 {mu}m depth in pure tungsten. The hardness of these layers was measured using nanoindentation and was studied using transmission electron microscopy. Substantial hardness increases were seen in helium implanted regions, with smaller hardness increases in regions which had already been self-ion implanted, thus, containing pre-existing dislocation loops. This suggests that, for the same helium content, helium trapped in distributed vacancies gives stronger hardening than helium trapped in vacancies condensed into dislocation loops.

Armstrong, D. E. J.; Edmondson, P. D.; Roberts, S. G. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)] [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

2013-06-24T23:59:59.000Z

276

Quantum fluctuations and isotope effects in ab initio descriptions of water  

SciTech Connect (OSTI)

Isotope substitution is extensively used to investigate the microscopic behavior of hydrogen bonded systems such as liquid water. The changes in structure and stability of these systems upon isotope substitution arise entirely from the quantum mechanical nature of the nuclei. Here, we provide a fully ab initio determination of the isotope exchange free energy and fractionation ratio of hydrogen and deuterium in water treating exactly nuclear quantum effects and explicitly modeling the quantum nature of the electrons. This allows us to assess how quantum effects in water manifest as isotope effects, and unravel how the interplay between electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water.

Wang, Lu; Markland, Thomas E., E-mail: tmarkland@stanford.edu [Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, California 94305 (United States); Ceriotti, Michele, E-mail: michele.ceriotti@epfl.ch [Laboratory of Computational Science and Modeling, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland)

2014-09-14T23:59:59.000Z

277

Microsoft Word - 911138_0_SSC-6 Helium Circulator Test Plan_rel...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

8 Revision 0 ENGINEERING SERVICES FOR THE NEXT GENERATION NUCLEAR PLANT (NGNP) WITH HYDROGEN PRODUCTION Test Plan for Helium Circulators (PHTS, SCS, SHTS) Prepared by General...

278

Bubble microstructure evolution and helium behavior in He{sup +} implanted Ni-base alloys  

SciTech Connect (OSTI)

Behavior of ion-implanted helium in Ni as a function of alloying element concentration (Al or Ti) and irradiation conditions (at 20 or 750 C) have been investigated by means of thermal desorption spectrometry (TDS) and transmission electron microscopy (TEM). Substitution elements in solid solution were demonstrated to have substantial influence on the evolution of implanted helium, shifting the TDS spectrum peaks to higher temperature region and increasing the quantity of helium remaining in the samples after long-time postirradiation annealing. TEM investigations showed that in the case of postirradiation annealing, helium bubbles are formed earlier in quenched alloys than in those annealed.

Kalin, B.A.; Chernov, I.I.; Kalashnikov, A.N.; Solovyev, B.G. [Moscow State Engineering Physics Inst., Moscow (Russian Federation). Dept. of Physical Problems of Materials Science

1996-12-31T23:59:59.000Z

279

Interim Report on the Optimization and Feasibility Studies for the Neutron Detection without Helium-3 Project  

SciTech Connect (OSTI)

This report provides the status and results of the first year's effort in modeling and simulation to investigate alternatives to helium-3 for neutron detection in safeguards applications.

Ely, James H.

2012-03-19T23:59:59.000Z

280

Cold Vacuum Drying (CVD) Facility General Service Helium System Design Description  

SciTech Connect (OSTI)

This document describes the Cold Vacuum Drying Facility general service helium system (GSHe). The GSHe is a general service facility process support system, but does include safety-class systems, structures and components providing protection to the offsite public. The GSHe also performs safety-significant functions that provide protection to onsite workers. The GSHe essential function is to provide helium to support process functions during all phases of facility operations. GSHe helium is used to purge the cask and the MCO in order to maintain their internal atmospheres below hydrogen flammability concentrations. The GSHe also supplies helium to purge the PWC lines and components and the VPS vacuum pump.

FARWICK, C.C.

1999-07-06T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Low temperature carrier transport properties in isotopically controlled germanium  

SciTech Connect (OSTI)

Investigations of electronic and optical properties of semiconductors often require specimens with extremely homogeneous dopant distributions and precisely controlled net-carrier concentrations and compensation ratios. The previous difficulties in fabricating such samples are overcome as reported in this thesis by growing high-purity Ge single crystals of controlled {sup 75}Ge and {sup 70}Ge isotopic compositions, and doping these crystals by the neutron transmutation doping (NTD) technique. The resulting net-impurity concentrations and the compensation ratios are precisely determined by the thermal neutron fluence and the [{sup 74}Ge]/[{sup 70}Ge] ratios of the starting Ge materials, respectively. This method also guarantees unprecedented doping uniformity. Using such samples the authors have conducted four types of electron (hole) transport studies probing the nature of (1) free carrier scattering by neutral impurities, (2) free carrier scattering by ionized impurities, (3) low temperature hopping conduction, and (4) free carrier transport in samples close to the metal-insulator transition.

Itoh, K.

1994-12-01T23:59:59.000Z

282

Hyperfiltration-induced fractionation of lithium isotopes in geologic systems. Progress report, April 1, 1991--December 1, 1991  

SciTech Connect (OSTI)

Effective modeling of hyperfiltration-induced fractionation of lithium isotopes is hindered by a lack of data on aqueous diffusion coefficients of {sup 6}Li{sup +} and {sup 7}Li{sup +}. Several experiments were conducted this past year on yielded a value for the ratio of diffusion coefficients between {sup D6}Li+Cl{minus}/{sup D7}Li+Cl{minus}. A 0.9450 M LiCl solution was placed within sealed dialysis tubing and osmoted against a kilogram of deionized water at 22C. Osmotic equilibrium occurred at 143 minutes, and the ratio of {omega}{sup 6}Li{sup +}Cl{minus}/{omega}{sup 7}Li+Cl{minus} was measured to be 1.011. Because this experimental value is close to the square root of the mass ratio between {sup 7}LiCl and {sup 6}LiCl (1.012), Graham`s Law may be a convenient way to calculate such ratios for aqueous diffusion coefficients of individual isotopic components. In evolution of this closed-system osmotic cell as a function of time, Li isotopic ratios of beaker and bag solutions exhibit a minimum and a maximum before the {sup 6}Li/{sup 7}Li ratios of both solutions assume the inevitable asymptotic approach toward isotopic equilibrium. Max difference in {sup 6}Li/{sup 7}Li ratio between beaker and bag solution was 0.00156 {plus_minus} 0.00015.

Fritz, S.J.

1992-01-01T23:59:59.000Z

283

Energy spectra of finite temperature superfluid helium-4 turbulence  

SciTech Connect (OSTI)

A mesoscopic model of finite temperature superfluid helium-4 based on coupled Langevin-Navier-Stokes dynamics is proposed. Drawing upon scaling arguments and available numerical results, a numerical method for designing well resolved, mesoscopic calculations of finite temperature superfluid turbulence is developed. The application of model and numerical method to the problem of fully developed turbulence decay in helium II, indicates that the spectral structure of normal-fluid and superfluid turbulence is significantly more complex than that of turbulence in simple-fluids. Analysis based on a forced flow of helium-4 at 1.3 K, where viscous dissipation in the normal-fluid is compensated by the Lundgren force, indicate three scaling regimes in the normal-fluid, that include the inertial, low wavenumber, Kolmogorov k{sup ?5/3} regime, a sub-turbulence, low Reynolds number, fluctuating k{sup ?2.2} regime, and an intermediate, viscous k{sup ?6} range that connects the two. The k{sup ?2.2} regime is due to normal-fluid forcing by superfluid vortices at high wavenumbers. There are also three scaling regimes in the superfluid, that include a k{sup ?3} range that corresponds to the growth of superfluid vortex instabilities due to mutual-friction action, and an adjacent, low wavenumber, k{sup ?5/3} regime that emerges during the termination of this growth, as superfluid vortices agglomerate between intense normal-fluid vorticity regions, and weakly polarized bundles are formed. There is also evidence of a high wavenumber k{sup ?1} range that corresponds to the probing of individual-vortex velocity fields. The Kelvin waves cascade (the main dynamical effect in zero temperature superfluids) appears to be damped at the intervortex space scale.

Kivotides, Demosthenes [Department of Aeronautics, Imperial College London, London SW7 2AZ (United Kingdom)

2014-10-15T23:59:59.000Z

284

A pencil beam algorithm for helium ion beam therapy  

SciTech Connect (OSTI)

Purpose: To develop a flexible pencil beam algorithm for helium ion beam therapy. Dose distributions were calculated using the newly developed pencil beam algorithm and validated using Monte Carlo (MC) methods. Methods: The algorithm was based on the established theory of fluence weighted elemental pencil beam (PB) kernels. Using a new real-time splitting approach, a minimization routine selects the optimal shape for each sub-beam. Dose depositions along the beam path were determined using a look-up table (LUT). Data for LUT generation were derived from MC simulations in water using GATE 6.1. For materials other than water, dose depositions were calculated by the algorithm using water-equivalent depth scaling. Lateral beam spreading caused by multiple scattering has been accounted for by implementing a non-local scattering formula developed by Gottschalk. A new nuclear correction was modelled using a Voigt function and implemented by a LUT approach. Validation simulations have been performed using a phantom filled with homogeneous materials or heterogeneous slabs of up to 3 cm. The beams were incident perpendicular to the phantoms surface with initial particle energies ranging from 50 to 250 MeV/A with a total number of 10{sup 7} ions per beam. For comparison a special evaluation software was developed calculating the gamma indices for dose distributions. Results: In homogeneous phantoms, maximum range deviations between PB and MC of less than 1.1% and differences in the width of the distal energy falloff of the Bragg-Peak from 80% to 20% of less than 0.1 mm were found. Heterogeneous phantoms using layered slabs satisfied a {gamma}-index criterion of 2%/2mm of the local value except for some single voxels. For more complex phantoms using laterally arranged bone-air slabs, the {gamma}-index criterion was exceeded in some areas giving a maximum {gamma}-index of 1.75 and 4.9% of the voxels showed {gamma}-index values larger than one. The calculation precision of the presented algorithm was considered to be sufficient for clinical practice. Although only data for helium beams was presented, the performance of the pencil beam algorithm for proton beams was comparable. Conclusions: The pencil beam algorithm developed for helium ions presents a suitable tool for dose calculations. Its calculation speed was evaluated to be similar to other published pencil beam algorithms. The flexible design allows easy customization of measured depth-dose distributions and use of varying beam profiles, thus making it a promising candidate for integration into future treatment planning systems. Current work in progress deals with RBE effects of helium ions to complete the model.

Fuchs, Hermann; Stroebele, Julia; Schreiner, Thomas; Hirtl, Albert; Georg, Dietmar [Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); PEG MedAustron, 2700 Wiener Neustadt (Austria); Department of Nuclear Medicine, Medical University of Vienna, 1090 Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria)

2012-11-15T23:59:59.000Z

285

Quartz Tuning Fork: Thermometer, Pressure- and Viscometer for Helium Liquids  

E-Print Network [OSTI]

Commercial quartz oscillators of the tuning-fork type with a resonant frequency of ~32 kHz have been investigated in helium liquids. The oscillators are found to have at best Q values in the range 10^5-10^6, when measured in vacuum below 1.5 K. However, the variability is large and for very low temperature operation the sensor has to be preselected. We explore their properties in the regime of linear viscous hydrodynamic response in normal and superfluid 3He and 4He, by comparing measurements to the hydrodynamic model of the sensor.

R. Blaauwgeers; M. Blazkova; M. Clovecko; V. B. Eltsov; R. de Graaf; J. Hosio; M. Krusius; D. Schmoranzer; W. Schoepe; L. Skrbek; P. Skyba; R. E. Solntsev; D. E. Zmeev

2006-08-17T23:59:59.000Z

286

GUM Analysis for TIMS Isotopic Ratios in BEP0 Graphite Qualification Samples, Round 2  

SciTech Connect (OSTI)

In May 2007, one set of three samples from NBL were addressed to Steve Petersen for TIMS analysis, and included BEP0 samples numbered 27008, 30986, and 50846. All cores were trimmed by tooling, and lightly cleaned by CO2 pellet blasting. Small discs were cut from the second set of samples for SIMS analysis, with the remainder of each used for TIMS preparation.

Gerlach, David C.; Heasler, Patrick G.; Reid, Bruce D.

2009-01-01T23:59:59.000Z

287

A new concept for isotope ratio monitoring LC/MS A Wide Range of Applications  

E-Print Network [OSTI]

promotes rock thermal expansion and contraction, as do pressure changes due to fluid injection and gas of the complex time-variant thermal interplay between aqueous fluid flow and crustal deformation. We carry out injection, circulation, and gas formation can generate complex, temporally and spatially varying patterns

288

Summary We tested the hypothesis that forest age influ-ences the carbon isotope ratio (13  

E-Print Network [OSTI]

(13 CR), soil respiration (13 CR-soil), bulk needle tissue (13 CP) and soil organic carbon (13 CSOC Washington, USA. Values of 13 CR, 13 CR-soil, 13 CP and 13 CSOC showed consistent enrich- ment similar canopy levels), 13 CSOC (throughout the soil column), 13 CR-soil (during the wet season) and 13 CR

Ehleringer, Jim

289

Benthic foraminifera as paleoceanographic proxies : core-top element/calcium ratios and stable isotope data  

E-Print Network [OSTI]

in redox chemistry when compared with uranium. The dissolveduranium in foraminiferal coatings: A proxy for ocean redox chemistry.

Harper, Dustin T.; Harper, Dustin T.

2012-01-01T23:59:59.000Z

290

Carbon isotope ratios of organic compound fractions in oceanic suspended particles  

E-Print Network [OSTI]

in the northeast Pacific Ocean, J. Geophys. Res. , 101,slope to the abyssal NE Pacific Ocean, Deep Sea Res. , Partwaters of the equatorial Pacific Ocean, Deep Sea Res. , Part

Hwang, Jeomshik; Druffel, Ellen R. M

2006-01-01T23:59:59.000Z

291

Identification of isotopically primitive interplanetary dust particles: A NanoSIMS isotopic imaging study  

E-Print Network [OSTI]

Identification of isotopically primitive interplanetary dust particles: A NanoSIMS isotopic imaging contain larger regions with more modest enrichments in 15 N, leading to average bulk N isotopic of those IDPs that have anomalous bulk N isotopic compositions. These particles typically also contain

292

Spinelolivine magnesium isotope thermometry in the mantle and implications for the Mg isotopic composition of Earth  

E-Print Network [OSTI]

Spinel­olivine magnesium isotope thermometry in the mantle and implications for the Mg isotopic: magnesium isotopes mantle geochemistry meteorites MC-ICPMS The magnesium isotopic composition of Earth., 2004; Poitrasson et al., 2005; Georg et al., 2007; Poitrasson, 2007; Weyer et al., 2007). Magnesium

Manning, Craig

293

Online Catalog of Isotope Products from DOE's National Isotope Development Center  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

The National Isotope Development Center (NIDC) interfaces with the User Community and manages the coordination of isotope production across the facilities and business operations involved in the production, sale, and distribution of isotopes. A virtual center, the NIDC is funded by the Isotope Development and Production for Research and Applications (IDPRA) subprogram of the Office of Nuclear Physics in the U.S. Department of Energy Office of Science. The Isotope subprogram supports the production, and the development of production techniques of radioactive and stable isotopes that are in short supply for research and applications. Isotopes are high-priority commodities of strategic importance for the Nation and are essential for energy, medical, and national security applications and for basic research; a goal of the program is to make critical isotopes more readily available to meet domestic U.S. needs. This subprogram is steward of the Isotope Production Facility (IPF) at Los Alamos National Laboratory (LANL), the Brookhaven Linear Isotope Producer (BLIP) facility at BNL, and hot cell facilities for processing isotopes at ORNL, BNL and LANL. The subprogram also coordinates and supports isotope production at a suite of university, national laboratory, and commercial accelerator and reactor facilities throughout the Nation to promote a reliable supply of domestic isotopes. The National Isotope Development Center (NIDC) at ORNL coordinates isotope production across the many facilities and manages the business operations of the sale and distribution of isotopes.

294

Successful application of lead isotopes in source apportionment, legal proceedings, remediation and monitoring  

SciTech Connect (OSTI)

In late 2006, the seaside community in Esperance Western Australia was alerted to thousands of native bird species dying. The source of the lead (Pb) was determined by Pb isotopes to derive from the handling of Pb carbonate concentrate through the Port, which began in July 2005. Concern was expressed for the impact of this on the community. Our objectives were to employ Pb isotope ratios to evaluate the source of Pb in environmental samples for use in legal proceedings, and for use in remediation and monitoring. Isotope measurements were undertaken of bird livers, plants, drinking water, soil, harbour sediments, air, bulk ceiling dust, gutter sludge, surface swabs and blood. The unique lead isotopic signature of the contaminating Pb carbonate enabled diagnostic apportionment of lead in samples. Apart from some soil and water samples, the proportion of contaminating Pb was >95% in the environmental samples. Lead isotopes were critical in resolving legal proceedings, are being used in the remediation of premises, were used in monitoring of workers involved in the decontamination of the storage facility, and monitoring transport of the concentrate through another port facility. Air samples show the continued presence of contaminant Pb, more than one year after shipping of concentrate ceased, probably arising from dust resuspension. Brief details of the comprehensive testing and cleanup of the Esperance community are provided along with the role of the Community. Lead isotopic analyses can provide significant benefits to regulatory agencies, interested parties, and the community where the signature is able to be characterised with a high degree of certainty. - Highlights: Black-Right-Pointing-Triangle Lead carbonate concentrate. Black-Right-Pointing-Triangle Successful use of Pb isotopes in identifying sources of Pb arising from transport and shipping. Black-Right-Pointing-Triangle Use of Pb isotopes in legal proceedings and their use in cleanup of residences. Black-Right-Pointing-Triangle Use of Pb isotopes in cleanup of a residual 9000 tonnes of Pb carbonate and in ongoing monitoring.

Gulson, Brian, E-mail: brian.gulson@mq.edu.au [Graduate School of the Environment, Faculty of Science, Macquarie University, Sydney, NSW 2109 (Australia) [Graduate School of the Environment, Faculty of Science, Macquarie University, Sydney, NSW 2109 (Australia); CSIRO Earth Science and Resource Engineering North Ryde, NSW 1670 (Australia); Korsch, Michael [CSIRO Earth Science and Resource Engineering North Ryde, NSW 1670 (Australia)] [CSIRO Earth Science and Resource Engineering North Ryde, NSW 1670 (Australia); Winchester, Wayne; Devenish, Matthew; Hobbs, Thad [Esperance Cleanup and Recovery Project, Western Australia (WA) Department of Transport, Esperance 6450 (Australia)] [Esperance Cleanup and Recovery Project, Western Australia (WA) Department of Transport, Esperance 6450 (Australia); Main, Cleve; Smith, Gerard [Animal Health Laboratory, Department of Agriculture and Food, Perth 6151, WA (Australia)] [Animal Health Laboratory, Department of Agriculture and Food, Perth 6151, WA (Australia); Rosman, Kevin; Howearth, Lynette; Burn-Nunes, Laurie [Curtin University, Department of Imaging and Applied Physics, Bentley 6102, WA (Australia)] [Curtin University, Department of Imaging and Applied Physics, Bentley 6102, WA (Australia); Seow, Jimmy; Oxford, Cameron [Department of Environment and Conservation, Booragoon 6154, WA (Australia)] [Department of Environment and Conservation, Booragoon 6154, WA (Australia); Yun, Gracie; Gillam, Lindsay [Department of Health, East Perth 6004, WA (Australia)] [Department of Health, East Perth 6004, WA (Australia); Crisp, Michelle [LED (Locals for Esperance Development), Esperance 6450, WA (Australia)] [LED (Locals for Esperance Development), Esperance 6450, WA (Australia)

2012-01-15T23:59:59.000Z

295

Isotope Cancer Treatment Research at LANL  

ScienceCinema (OSTI)

Los Alamos National Laboratory has produced medical isotopes for diagnostic and imaging purposes for more than 30 years. Now LANL researchers have branched out into isotope cancer treatment studies. New results show that an accelerator-based approach can produce clinical trial quantities of actinium-225, an isotope that has promise as a way to kill tumors without damaging surrounding healthy cells.

Weidner, John; Nortier, Meiring

2014-06-02T23:59:59.000Z

296

Cold collisions of PH ({sup 3}{Sigma}{sup -}) with helium in magnetic fields  

SciTech Connect (OSTI)

A theoretical investigation of the He-PH ({sup 3}{Sigma}{sup -}) complex is presented. We perform ab initio calculations of the interaction potential energy surface and discuss its error bounds with relevance to cold collisions, and we carry out accurate calculations of bound energy levels of the complex including the molecular fine structure and magnetic-field effect. We find the potential has two shallow minima and supports ten and 13 bound levels in complex with {sup 3}He and {sup 4}He, respectively. Based on the potential the quantum scattering calculations are then implemented for elastic and inelastic cross sections of the magnetically trappable low-field-seeking state of PH ({sup 3}{Sigma}{sup -}) in collision with {sup 3}He atom. The cold-collision properties and the influence of the external magnetic field as well as the effect of the uncertainty of interaction potential on the collisionally induced Zeeman relaxation are explored and discussed in detail. The ratio of elastic to inelastic cross sections is large over a wide range of collision energy, magnetic field, and scaling factor of the potential, so that helium buffer-gas loading and evaporative cooling of PH is a good prospect.

Feng, Eryin; Yu, Chunhua; Sun, Chunyan; Shao, Xi; Huang, Wuying [Department of Physics, Anhui Normal University, Wuhu 241000 (China)

2011-12-15T23:59:59.000Z

297

Delayed-neutron branching ratios of precursors in the fission product region  

SciTech Connect (OSTI)

Delayed-neutron branching ratios in the fission product region have been tabulated, and average values have been determined. In order to provide data complementary to published values an experiment covering the mass range 79-150 has been carried out at the OSIRIS isotope-separator on-line facility at Studsvik. This experiment has resulted in branching ratios for some precursors ([sup 84]Ge, [sup 133]Sn, and [sup 150]La) for which such data have not been reported before. In several other cases the new results are accurate than older determinations. 19 refs., 2 figs., 1 tab.

Rudstam, G.; Aleklett, K.; Sihver, L. (Studsvik Neutron Research Lab., Nykoeping (Sweden))

1993-01-01T23:59:59.000Z

298

Variable ratio regenerative braking device  

DOE Patents [OSTI]

Disclosed is a regenerative braking device (10) for an automotive vehicle. The device includes an energy storage assembly (12) having a plurality of rubber rollers (26, 28) mounted for rotation between an input shaft (36) and an output shaft (42), clutches (38, 46) and brakes (40, 48) associated with each shaft, and a continuously variable transmission (22) connectable to a vehicle drivetrain and to the input and output shafts by the respective clutches. The rubber rollers are torsionally stressed to accumulate energy from the vehicle when the input shaft is clutched to the transmission while the brake on the output shaft is applied, and are torsionally relaxed to deliver energy to the vehicle when the output shaft is clutched to the transmission while the brake on the input shaft is applied. The transmission ratio is varied to control the rate of energy accumulation and delivery for a given rotational speed of the vehicle drivetrain.

Hoppie, Lyle O. (Birmingham, MI)

1981-12-15T23:59:59.000Z

299

Weather-Corrected Performance Ratio  

SciTech Connect (OSTI)

Photovoltaic (PV) system performance depends on both the quality of the system and the weather. One simple way to communicate the system performance is to use the performance ratio (PR): the ratio of the electricity generated to the electricity that would have been generated if the plant consistently converted sunlight to electricity at the level expected from the DC nameplate rating. The annual system yield for flat-plate PV systems is estimated by the product of the annual insolation in the plane of the array, the nameplate rating of the system, and the PR, which provides an attractive way to estimate expected annual system yield. Unfortunately, the PR is, again, a function of both the PV system efficiency and the weather. If the PR is measured during the winter or during the summer, substantially different values may be obtained, making this metric insufficient to use as the basis for a performance guarantee when precise confidence intervals are required. This technical report defines a way to modify the PR calculation to neutralize biases that may be introduced by variations in the weather, while still reporting a PR that reflects the annual PR at that site given the project design and the project weather file. This resulting weather-corrected PR gives more consistent results throughout the year, enabling its use as a metric for performance guarantees while still retaining the familiarity this metric brings to the industry and the value of its use in predicting actual annual system yield. A testing protocol is also presented to illustrate the use of this new metric with the intent of providing a reference starting point for contractual content.

Dierauf, T.; Growitz, A.; Kurtz, S.; Cruz, J. L. B.; Riley, E.; Hansen, C.

2013-04-01T23:59:59.000Z

300

The Source of the Helium Visible Lines in Eta Carinae  

E-Print Network [OSTI]

We assume that the helium-I lines emitted by the massive binary system Eta Carinae are formed in the acceleration zone of the less-massive secondary star. We calculate the Doppler shift of the lines as a function of orbital phase and of several parameters of the binary system. We find that a good fit is obtained if the helium lines are formed in the region where the secondary wind speed is 430 km/sec. The acceptable binary eccentricity is in the range 0.9-0.95, and the inclination angle (the angle between a line perpendicular to the orbital plane and the line of sight) is in the range 40-55 degrees. Lower values of e require higher values of i, and vice versa. The binary system is oriented such that the secondary star is in our direction (closer to us) during periastron passage. The orbital motion can account in part to the Doppler shift of the peak in X-ray emission.

Kashi, A; Kashi, Amit; Soker, Noam

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

The Source of the Helium Visible Lines in Eta Carinae  

E-Print Network [OSTI]

We assume that the helium-I lines emitted by the massive binary system Eta Carinae are formed in the acceleration zone of the less-massive secondary star. We calculate the Doppler shift of the lines as a function of orbital phase and of several parameters of the binary system. We find that a good fit is obtained if the helium lines are formed in the region where the secondary wind speed is 430 km/sec. The acceptable binary eccentricity is in the range 0.9-0.95, and the inclination angle (the angle between a line perpendicular to the orbital plane and the line of sight) is in the range 40-55 degrees. Lower values of e require higher values of i, and vice versa. The binary system is oriented such that the secondary star is in our direction (closer to us) during periastron passage. The orbital motion can account in part to the Doppler shift of the peak in X-ray emission.

Amit Kashi; Noam Soker

2007-04-13T23:59:59.000Z

302

Development of monitoring system of helium leakage from canister  

SciTech Connect (OSTI)

This paper presents a computational method for the helium leakage from a canister. The governing equations for compressible fluids consist of mass conservation equation in Eulerian description, momentum equations and energy equation. The numerical procedures are divided into three phases, advection, diffusion and acoustic phases, and the equations of compressible fluids are discretized with a finite volume method. Thus, the mass conservation law is sufficiently satisfied in the calculation region. In particular, our computational method enables us to predict the change of the temperature distributions around the canister boundaries by calculating the governing equations for the compressible gas flows, which are leaked out from a slight crack on the canister boundary. In order to confirm the validity of our method, it was applied to the basic problem, 2-dimensional natural convection flows in a rectangular cavity. As a result, it was shown that the naturally convected flows can be reasonably simulated by our method. Furthermore, numerical experiments were conducted for the helium leakage from canister and we derived a close relationship between the inner pressure and the boundary temperature distributions.

Toriu, D. [Kyoto University, CERE, Kyoto, 615-8540 (Japan); Ushijima, S. [Kyoto University, ACCMS, Kyoto, 606-8501 (Japan); Takeda, H. [Central Research Institute of Electric Power Industry - CRIEPI, Abiko 1646, 270-1194 (Japan)

2013-07-01T23:59:59.000Z

303

Ignition and extinction phenomena in helium micro hollow cathode discharges  

SciTech Connect (OSTI)

Micro hollow cathode discharges (MHCD) were produced using 250??m thick dielectric layer of alumina sandwiched between two nickel electrodes of 8??m thickness. A through cavity at the center of the chip was formed by laser drilling technique. MHCD with a diameter of few hundreds of micrometers allowed us to generate direct current discharges in helium at up to atmospheric pressure. A slowly varying ramped voltage generator was used to study the ignition and the extinction periods of the microdischarges. The analysis was performed by using electrical characterisation of the V-I behaviour and the measurement of He*({sup 3}S{sub 1}) metastable atoms density by tunable diode laser spectroscopy. At the ignition of the microdischarges, 2??s long current peak as high as 24?mA was observed, sometimes followed by low amplitude damped oscillations. At helium pressure above 400?Torr, an oscillatory behaviour of the discharge current was observed just before the extinction of the microdischarges. The same type of instability in the extinction period at high pressure also appeared on the density of He*({sup 3}S{sub 1}) metastable atoms, but delayed by a few ?s relative to the current oscillations. Metastable atoms thus cannot be at the origin of the generation of the observed instabilities.

Kulsreshath, M. K.; Schwaederle, L.; Dufour, T.; Lefaucheux, P.; Dussart, R. [GREMI, CNRS/Université d'Orléans (UMR7344), Orléans (France); Sadeghi, N. [LIPhy, CNRS and Universite Joseph Fourier (UMR5588), Grenoble (France); Overzet, L. J. [GREMI, CNRS/Université d'Orléans (UMR7344), Orléans (France); PSAL, UTDallas, Richardson, Texas 75080-3021 (United States)

2013-12-28T23:59:59.000Z

304

Neutron Irradiation Tests of Pressure Transducers in Liquid Helium  

E-Print Network [OSTI]

The superconducting magnets of the future Large Hadron Collider (LHC) at CERN will operate in pressurised superfluid helium (1 bar, 1.9 K). About 500 pressure transducers will be placed in the liquid helium bath for monitoring the filling and the pressure transients after resistive transitions. Their precision must remain better than 100 mbar at pressures below 2 bar and better than 5% for higher pressures (up to 20 bar), with temperatures ranging from 1.8 K to 300 K. All the tested transducers are based on the same principle: the fluid or gas is separated from a sealed reference vacuum by an elastic membrane; its deformation indicates the pressure. The transducers will be exposed to high neutron fluence (2 kGy, 1014 n/cm2 per year) during the 20 years of machine operation. This irradiation may induce changes both on the membranes characteristics (leakage, modification of elasticity) and on gauges which measure their deformations. To investigate these effects and select the transducer to be used in the LHC, a...

Amand, J F; Casas-Cubillos, J; Thermeau, J P

1999-01-01T23:59:59.000Z

305

Gettering of hydrogen and methane from a helium gas mixture  

SciTech Connect (OSTI)

In this study, the authors developed an approach for accurately quantifying the helium content in a gas mixture also containing hydrogen and methane using commercially available getters. The authors performed a systematic study to examine how both H{sub 2} and CH{sub 4} can be removed simultaneously from the mixture using two SAES St 172{sup ®} getters operating at different temperatures. The remaining He within the gas mixture can then be measured directly using a capacitance manometer. The optimum combination involved operating one getter at 650?°C to decompose the methane, and the second at 110?°C to remove the hydrogen. This approach eliminated the need to reactivate the getters between measurements, thereby enabling multiple measurements to be made within a short time interval, with accuracy better than 1%. The authors anticipate that such an approach will be particularly useful for quantifying the He-3 in mixtures that include tritium, tritiated methane, and helium-3. The presence of tritiated methane, generated by tritium activity, often complicates such measurements.

Cárdenas, Rosa Elia, E-mail: recarde1@uiwtx.edu [Department of Physics, The University of the Incarnate Word, 4301 Broadway, San Antonio, Texas 78209 (United States); Stewart, Kenneth D.; Cowgill, Donald F., E-mail: dfcowgi@sandia.gov [Sandia National Laboratories, Hydrogen and Metallurgical Sciences, 7011 East Avenue, Livermore, California 94550 (United States)

2014-11-01T23:59:59.000Z

306

The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle  

E-Print Network [OSTI]

The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle Matthias R. Aellig Alamos National Lab., Los Alamos, NM 87545 Abstract We investigate the helium abundance in the solar wind of 1994 and early 2000 are analyzed. In agreement with similar work for previous solar cycles, we find

Richardson, John

307

Difference in formation of hydrogen and helium clusters in tungsten K. O. E. Henriksson,a  

E-Print Network [OSTI]

Difference in formation of hydrogen and helium clusters in tungsten K. O. E. Henriksson,a K online 12 October 2005 The experimentally observed large difference in the depths of hydrogen and helium and He embrittlement of materials. Yet many of the basic properties of such systems are not well

Krasheninnikov, Arkady V.

308

RIS-M-2612 ON TRANSPORT OF HELIUM TO GRAIN BOUNDARIES DURING IRRADIATION  

E-Print Network [OSTI]

parameters determining the integrity and lifetime of the structural components of a fusion reactor. A diffusion calculation i s made of the flux of helium to a grain boundary. The flux i s found to depend interior. The calculated accumulation of helium i s in good agreement with the measured gas content

309

Faraday and Cotton-Mouton Effects of Helium at = 1064 nm A. Cad`ene1  

E-Print Network [OSTI]

Faraday and Cotton-Mouton Effects of Helium at = 1064 nm A. Cad`ene1 , D. Sordes1 , P. Berceau1 of the Faraday and the Cotton-Mouton effects of helium gas at = 1064 nm. Our apparatus is based on an up and Cotton-Mouton effect. Our measurements give for the first time the experimental value of the Faraday

Paris-Sud XI, Université de

310

Activation of the liquid helium contamination during its passage in the Collider ring  

SciTech Connect (OSTI)

Radioactivation of possible contamination of the liquid helium trapped in the arcs of the Collider ring of the Superconducting Super Collider and transported by the liquid helium is estimated. This estimation is used to calculate the dose rate on the filter of the refrigerator plant located at the top of the shaft.

Lopez, G.

1994-01-01T23:59:59.000Z

311

A systematic regional trend in helium isotopes across the northern basin and range province, Western North America  

E-Print Network [OSTI]

high potential for geothermal energy development. Over thespring; CF: Cove Fort geothermal energy plant. Additionalspring; CF: Cove Fort geothermal energy plant. Additional

Kennedy, B. Mack; van Soest, Matthijs C.

2006-01-01T23:59:59.000Z

312

Atomistic studies of formation and diffusion of helium clusters and bubbles in BCC iron  

SciTech Connect (OSTI)

In fusion applications, helium created by transmutation plays an important role in the response of reduced-activation ferritic/martensitic (RAFM) steels to neutron radiation damage. We have performed extensive atomistic simulations using the ORNL 3-body Fe He interatomic potential combined with three interatomic potentials for the iron matrix. Some of the results obtained are summarized in this review. Interstitial helium is very mobile and coalesces together to form interstitial clusters. We have investigated the mobility of these clusters. When an interstitial He cluster reaches sufficient size, it punches out an Fe interstitial, creating an immobile helium vacancy cluster. If more helium atoms join it, more Fe interstitials can be created; the He V defect is a nascent bubble. These mechanisms are investigated together in simulations that examine the nucleation of He defects. Mobile interstitial He clusters and helium bubbles 1 to 6 nm across are also simulated separately. Results are compared based on temperature and interatomic potentials used.

Stewart, David M [ORNL; Stoller, Roger E [ORNL; Osetskiy, Yury N [ORNL

2011-01-01T23:59:59.000Z

313

The Initiation and Propagation of Helium Detonations in White Dwarf Envelopes  

E-Print Network [OSTI]

Detonations in helium-rich envelopes surrounding white dwarfs have garnered attention as triggers of faint thermonuclear ".Ia" supernovae and double detonation Type Ia supernovae. However, recent studies have found that the minimum size of a hotspot that can lead to a helium detonation is comparable to, or even larger than, the white dwarf's pressure scale height, casting doubt on the successful ignition of helium detonations in these systems. In this paper, we examine the previously neglected effects of C/O pollution and a full nuclear reaction network, and we consider hotspots with spatially constant pressure in addition to constant density hotspots. We find that the inclusion of these effects significantly decreases the minimum hotspot size for helium-rich detonation ignition, making detonations far more plausible during turbulent shell convection or during double white dwarf mergers. The increase in burning rate also decreases the minimum shell mass in which a helium detonation can successfully propagate ...

Shen, Ken J

2014-01-01T23:59:59.000Z

314

Laser spectroscopic studies of state-dependent collisional quenching of the lifetimes of metastable antiprotonic helium atoms  

E-Print Network [OSTI]

Laser spectroscopic studies of state-dependent collisional quenching of the lifetimes of metastable antiprotonic helium atoms

Hori, M; Torii, H A; Ishikawa, T; Maas, F E; Yamazaki, T; Eades, John; Widmann, E; Kumakara, M; Morita, N; Sugai, I; Horváth, D; Ketzer, B; Hartmann, F J; Maierl, C; Hasinoff, M D; Von Egidy, T; Tamura, H

1998-01-01T23:59:59.000Z

315

PLANETARY-SCALE STRONTIUM ISOTOPIC HETEROGENEITY AND THE AGE OF VOLATILE DEPLETION OF EARLY SOLAR SYSTEM MATERIALS  

SciTech Connect (OSTI)

Isotopic anomalies in planetary materials reflect both early solar nebular heterogeneity inherited from presolar stellar sources and processes that generated non-mass-dependent isotopic fractionations. The characterization of isotopic variations in heavy elements among early solar system materials yields important insight into the stellar environment and formation of the solar system, and about initial isotopic ratios relevant to long-term chronological applications. One such heavy element, strontium, is a central element in the geosciences due to wide application of the long-lived {sup 87}Rb-{sup 87}Sr radioactive as a chronometer. We show that the stable isotopes of Sr were heterogeneously distributed at both the mineral scale and the planetary scale in the early solar system, and also that the Sr isotopic heterogeneities correlate with mass-independent oxygen isotope variations, with only CI chondrites plotting outside of this correlation. The correlation implies that most solar system material formed by mixing of at least two isotopically distinct components: a CV-chondrite-like component and an O-chondrite-like component, and possibly a distinct CI-chondrite-like component. The heterogeneous distribution of Sr isotopes may indicate that variations in initial {sup 87}Sr/{sup 86}Sr of early solar system materials reflect isotopic heterogeneity instead of having chronological significance, as interpreted previously. For example, given the differences in {sup 84}Sr/{sup 86}Sr between calcium aluminum inclusions and eucrites ({epsilon}{sup 84}Sr > 2), the difference in age between these materials would be {approx}6 Ma shorter than previously interpreted, placing the Sr chronology in agreement with other long- and short-lived isotope systems, such as U-Pb and Mn-Cr.

Moynier, Frederic; Podosek, Frank A. [Department of Earth and Planetary Science and McDonnell Center for Space Sciences, Washington University, St. Louis, MO 63130 (United States); Day, James M. D. [Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244 (United States); Okui, Wataru; Yokoyama, Tetsuya [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Bouvier, Audrey [Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455-0231 (United States); Walker, Richard J., E-mail: moynier@levee.wustl.edu, E-mail: fap@levee.wustl.edu, E-mail: jmdday@ucsd.edu, E-mail: rjwalker@umd.edu, E-mail: okui.w.aa@m.titech.ac.jp, E-mail: tetsuya.yoko@geo.titech.ac.jp, E-mail: abouvier@umn.edu [Department of Geology, University of Maryland, College Park, MD 20742 (United States)

2012-10-10T23:59:59.000Z

316

Light stable isotope study of the Roosevelt Hot Springs thermal area, Southwestern Utah  

SciTech Connect (OSTI)

The isotopic composition of hydrogen, oxygen, and carbon has been determined for regional cold springs, thermal fluids, and rocks and minerals from the Roosevelt Hot Springs thermal area. The geothermal system has developed within plutonic granitic rocks and amphibolite facies gneiss, relying upon fracture-controlled permeability for the migration of the thermal fluids. Probably originating as meteoric waters in the upper elevations of the Mineral Mountains, the thermal waters sampled in the production wells display an oxygen isotopic shift of at least +1.2. Depletions of delta /sup 18/O in wole rock, K-feldspar, and biotite have a positive correlation with alteration intensity. W/R mass ratios, calculated from the isotopic shifts of rock and water, range up to 3.0 in a producing horizon of one well, although the K-feldspar has experienced only 30% exchange with the thermal waters. While veinlet quartz has equilibrated with the thermal waters, the /sup 18/O values of K-mica clay, an alteration product of plagioclase, mimic the isotopic composition of K-feldspar and whole rock. This suggests that locally small W/R ratios enable plagioclase to influence its alteration products by isotopic exchange.

Rohrs D.T.; Bowman, J.R.

1980-05-01T23:59:59.000Z

317

The helium-core mass at the helium flash in low-mass red giant stars observations and theory  

E-Print Network [OSTI]

The method developed by Raffelt (1990a,b,c) to estimate a possible increase in the standard values of the helium-core mass at the tip of the red giant branch, \\Mc, from properties of the color-magnitude diagrams of Galactic globular clusters is employed. In the present study, we revise and update Raffelt's database, including also constraints from RR Lyrae pulsation, and find that a small increase, by \\Delta\\Mc \\approx 0.01\\pm 0.015 \\Msun, cannot be ruled out with the present data and evolutionary models. Our new upper limits on \\Delta\\Mc are less restrictive than those previously obtained by Raffelt, as are the corresponding constraints on novel astroparticle phenomena which may affect the evolution of low-mass red giants. Within the estimated uncertainties, however, the standard values of \\Mc may also be acceptable. Raffelt's method does not rule out a low envelope helium abundance in globular cluster giants, though again the standard values are compatible with the available constraints. The influence of a ...

Catelan, M

1995-01-01T23:59:59.000Z

318

cpp header will be provided by the publisher Properties of Dense Fluid Hydrogen and Helium in Giant Gas  

E-Print Network [OSTI]

cpp header will be provided by the publisher Properties of Dense Fluid Hydrogen and Helium in Giant molecular dynamics, equation of state, giant gas planets, hydrogen-helium mix- tures PACS 61.20.Ja, 61.25.Em, 61.25.Mv, 61.20.-p Equilibrium properties of hydrogen-helium mixtures under thermodynamic conditions

Militzer, Burkhard

319

Hyperfine-induced effects on the linear polarization of the K$\\alpha_1$ emission from helium-like ions  

E-Print Network [OSTI]

The linear polarization of the characteristic photon emission from few-electron ions is studied for its sensitivity with regard to the nuclear spin and magnetic moment of the ions. Special attention is paid, in particular, to the K$\\alpha_1$ ($1s 2p_{3/2} ^{1,3}P_{1,2} \\to 1s^2 ^1S_0$) decay of selected helium-like ions following the radiative electron capture into initially hydrogen-like species. Based on the density matrix theory, a unified description is developed that includes both, the many-electron and hyperfine interactions as well as the multipole-mixing effects arising from the expansion of the radiation field. It is shown that the polarization of the K$\\alpha_1$ line can be significantly affected by the mutipole mixing between the leading $M2$ and hyperfine-induced $E1$ components of $1s2p ^3P_2, F_i \\to 1s^2 ^1S_0, F_f$ transitions. This $E1$-$M2$ mixing strongly depends on the nuclear properties of the considered isotopes and can be addressed experimentally at existing heavy-ion storage rings.

Surzhykov, Andrey; Stöhlker, Thomas; Fritzsche, Stephan

2013-01-01T23:59:59.000Z

320

Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems  

SciTech Connect (OSTI)

A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and also be treated as a mostly closed system for mass balance considerations. It is the near closure of the system that permits well- constrained chemical mass balance calculations to be made. These calculations generally focus of lithogenic solutes, and therefore in our discussions of lithogenic nuclides in the paper, the concept of chemical mass balance in a nearly dosed system will play an important role. Examination of the isotopic compositions of solutes provides a better understanding of the variety of processes controlling mass balance. It is with this approach that we examined the variety of processes occurring within the catchment system, such as weathering and soil production, generation of stormflow and streamflow (hydrograph separation), movement of soil pore water, groundwater flow, and the overall processes involved with basinal water balance. In this paper, the term `nuclide` will be used when referring to a nuclear species that contains a particular number of protons and neutrons. The term is not specific to any element. The term `isotope` will be used to distinguish nuclear species of a given element (atoms with the same number of protons). That is to say, there are many nuclides in nature - for example, {sup 36}Cl, {sup 87}Sr, {sup 238}U; the element has four naturally-occurring isotopes - {sup 87}Sr, and {sup 88}Sr. This paper will first discuss the general principles that underlie the study of lithogenic and cosmogenic nuclides in hydrology, and provide references to some of the more important studies applying these principles and nuclides. We then turn in the second section to a discussion of their specific applications in catchment- scale systems. The final section of this paper discusses new directions in the application of lithogenic and cosmogenic nuclides to catchment hydrology, with some thoughts concerning possible applications that still remain unexplored.

Nimz, G. J., LLNL

1998-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

System size effects in the N/Z dependence of balance energy for isotopic series  

E-Print Network [OSTI]

We study the system size effects in the N/Z dependence of balance energy for the isotopic series. We find drastic effect of symmetry energy on the N/Z dependence of E$_{bal}$ throughout the mass range. We also find that the N/Z dependence of E$_{bal}$ for isotopic series of lighter system is slightly more sensitive to symmetry energy as compared to that of heavier systems. We also study the mass dependence of E$_{bal}$ for the N/Z range from 1.0-2.0. We find that the mass dependence of E$_{bal}$ varies with the N/Z ratio.

Sakshi Gautam; Aman Deep Sood

2011-07-25T23:59:59.000Z

322

Options for Cryogenic Load Cooling with Forced Flow Helium Circulation  

SciTech Connect (OSTI)

Cryogenic pumps designed to circulate super-critical helium are commonly deemed necessary in many super-conducting magnet and other cooling applications. Acknowledging that these pumps are often located at the coldest temperature levels, their use introduces risks associated with the reliability of additional rotating machinery and an additional load on the refrigeration system. However, as it has been successfully demonstrated, this objective can be accomplished without using these pumps by the refrigeration system, resulting in lower system input power and improved reliability to the overall cryogenic system operations. In this paper we examine some trade-offs between using these pumps vs. using the refrigeration system directly with examples of processes that have used these concepts successfully and eliminated using such pumps

Peter Knudsen, Venkatarao Ganni, Roberto Than

2012-06-01T23:59:59.000Z

323

Nuclear fusion in muonic deuterium-helium complex  

E-Print Network [OSTI]

Experimental study of the nuclear fusion reaction in charge-asymmetrical d-mu-3He complex is presented. The 14.6 MeV protons were detected by three pairs of Si(dE-E) telescopes placed around the cryogenic target filled with the deuterium + helium-3 gas at 34 K. The 6.85 keV gamma rays emitted during the de-excitation of d-mu-3He complex were detected by a germanium detector. The measurements were performed at two target densities, 0.0585 and 0.169 (relative to liquid hydrogen density) with an atomic concentration of 3He c=0.0469. The values of the effective rate of nuclear fusion in d-mu-3He was obtained for the first time, and the J=0 nuclear fusion rate in d-mu-3He was derived.

V. M. Bystritsky; M. Filipowicz; V. V. Gerasimov; P. E. Knowles; F. Mulhauser; N. P. Popov; V. A. Stolupin; V. P. Volnykh; J. Wozniak

2005-06-22T23:59:59.000Z

324

Friction-Induced Fluid Heating in Nanoscale Helium Flows  

SciTech Connect (OSTI)

We investigate the mechanism of friction-induced fluid heating in nanoconfinements. Molecular dynamics simulations are used to study the temperature variations of liquid helium in nanoscale Poiseuille flows. It is found that the fluid heating is dominated by different sources of friction as the external driving force is changed. For small external force, the fluid heating is mainly caused by the internal viscous friction in the fluid. When the external force is large and causes fluid slip at the surfaces of channel walls, the friction at the fluid-solid interface dominates over the internal friction in the fluid and is the major contribution to fluid heating. An asymmetric temperature gradient in the fluid is developed in the case of nonidentical walls and the general temperature gradient may change sign as the dominant heating factor changes from internal to interfacial friction with increasing external force.

Li Zhigang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

2010-05-21T23:59:59.000Z

325

Measurements of neutral helium density in helicon plasmas  

SciTech Connect (OSTI)

Laser-induced-fluorescence (LIF) is used to measure the density of helium atoms in a helicon plasma source. For a pump wavelength of 587.725 nm (vacuum) and laser injection along the magnetic field, the LIF signal exhibits a signal decrease at the Doppler shifted central wavelength. The drop in signal results from the finite optical depth of the plasma and the magnitude of the decrease is proportional to the density of excited state neutral atoms. Using Langmuir probe measurements of plasma density and electron temperature and a collisional-radiative model, the absolute ground state neutral density is calculated from the optical depth measurements. Optimal plasma performance, i.e., the largest neutral depletion on the axis of the system, is observed for antenna frequencies of 13.0 and 13.5 MHz and magnetic field strengths of 550-600 G.

Houshmandyar, Saeid; Sears, Stephanie H.; Thakur, Saikat Chakraborty; Carr, Jerry Jr.; Galante, Matthew E.; Scime, Earl E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

2010-10-15T23:59:59.000Z

326

Zeeman deceleration of electron-impact-excited metastable helium atoms  

E-Print Network [OSTI]

We present experimental results that demonstrate - for the first time - the Zeeman deceleration of helium atoms in the metastable 2^3S_1state. A more than 40% decrease of the kinetic energy of the beam is achieved for deceleration from 490 m/s to a final velocity of 370 m/s. Metastable atom generation is achieved with an electron-impact-excitation source whose performance is enhanced through an additional discharge-type process which we characterize in detail. Comparison of deceleration data at different electron beam pulse durations confirms that a matching between the initial particle distribution and the phase-space acceptance of the decelerator is crucial for the production of a decelerated packet with a well-defined velocity distribution. The experimental findings are in good agreement with three-dimensional numerical particle trajectory simulations.

Dulitz, Katrin; Softley, Timothy P

2015-01-01T23:59:59.000Z

327

Evaluation of the Gas Turbine Modular Helium Reactor  

SciTech Connect (OSTI)

Recent advances in gas-turbine and heat exchanger technology have enhanced the potential for a Modular Helium Reactor (MHR) incorporating a direct gas turbine (Brayton) cycle for power conversion. The resulting Gas Turbine Modular Helium Reactor (GT-MHR) power plant combines the high temperature capabilities of the MHR with the efficiency and reliability of modern gas turbines. While the passive safety features of the steam cycle MHR (SC-MHR) are retained, generation efficiencies are projected to be in the range of 48% and steam power conversion systems, with their attendant complexities, are eliminated. Power costs are projected to be reduced by about 20%, relative to the SC-MHR or coal. This report documents the second, and final, phase of a two-part evaluation that concluded with a unanimous recommendation that the direct cycle (DC) variant of the GT-MHR be established as the commercial objective of the US Gas-Cooled Reactor Program. This recommendation has been endorsed by industrial and utility participants and accepted by the US Department of Energy (DOE). The Phase II effort, documented herein, concluded that the DC GT-MHR offers substantial technical and economic advantages over both the IDC and SC systems. Both the DC and IDC were found to offer safety advantages, relative to the SC, due to elimination of the potential for water ingress during power operations. This is the dominant consequence event for the SC. The IDC was judged to require somewhat less development than the direct cycle, while the SC, which has the greatest technology base, incurs the least development cost and risk. While the technical and licensing requirements for the DC were more demanding, they were judged to be incremental and feasible. Moreover, the DC offers significant performance and cost improvements over the other two concepts. Overall, the latter were found to justify the additional development needs.

Not Available

1994-02-01T23:59:59.000Z

328

Interactions of mobile helium clusters with surfaces and grain boundaries of plasma-exposed tungsten  

SciTech Connect (OSTI)

We report results of atomistic computations for the interactions of small mobile helium clusters (He{sub n}) with free surfaces and grain boundaries (GBs) in tungsten toward development of continuum drift-diffusion-reaction models for the dynamics of mobile helium clusters in plasma-exposed tungsten. Molecular-statics (MS) simulations based on reliable many-body interatomic potentials are carried out for He{sub n} (1???n???7) clusters near sinks to obtain the potential energy profiles of the He{sub n} clusters as a function of the clusters' center-of-mass distance from a sink. Sinks investigated include surfaces, GBs, and regions in the vicinity of junctions where GBs intersect free surfaces. Elastic interaction potentials based on elastic inclusion theory provide an excellent description of the MS results for the cluster-sink interactions. The key parameter in the elastic models is the sink segregation strength, which is found to increase with increasing cluster size. Such cluster-sink interactions are responsible for the migration of small helium clusters by drift and for helium segregation on surfaces and grain boundaries in tungsten. Such helium segregation on sinks is observed in large-scale molecular-dynamics simulations of helium aggregation in model polycrystalline tungsten at 933?K upon helium implantation.

Hu, Lin; Maroudas, Dimitrios, E-mail: maroudas@ecs.umass.edu [Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003-9303 (United States); Hammond, Karl D.; Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

2014-05-07T23:59:59.000Z

329

Analysis of hydrogen isotope mixtures  

DOE Patents [OSTI]

An apparatus and method for determining the concentrations of hydrogen isotopes in a sample. Hydrogen in the sample is separated from other elements using a filter selectively permeable to hydrogen. Then the hydrogen is condensed onto a cold finger or cryopump. The cold finger is rotated as pulsed laser energy vaporizes a portion of the condensed hydrogen, forming a packet of molecular hydrogen. The desorbed hydrogen is ionized and admitted into a mass spectrometer for analysis.

Villa-Aleman, Eliel (Aiken, SC)

1994-01-01T23:59:59.000Z

330

THE EFFECTS OF CURVATURE AND EXPANSION ON HELIUM DETONATIONS ON WHITE DWARF SURFACES  

SciTech Connect (OSTI)

Accreted helium layers on white dwarfs have been highlighted for many decades as a possible site for a detonation triggered by a thermonuclear runaway. In this paper, we find the minimum helium layer thickness that will sustain a steady laterally propagating detonation and show that it depends on the density and composition of the helium layer, specifically {sup 12}C and {sup 16}O. Detonations in these thin helium layers have speeds slower than the Chapman-Jouget (CJ) speed from complete helium burning, v{sub CJ} = 1.5 × 10{sup 9} cm s{sup –1}. Though gravitationally unbound, the ashes still have unburned helium (?80% in the thinnest cases) and only reach up to heavy elements such as {sup 40}Ca, {sup 44}Ti, {sup 48}Cr, and {sup 52}Fe. It is rare for these thin shells to generate large amounts of {sup 56}Ni. We also find a new set of solutions that can propagate in even thinner helium layers when {sup 16}O is present at a minimum mass fraction of ?0.07. Driven by energy release from ? captures on {sup 16}O and subsequent elements, these slow detonations only create ashes up to {sup 28}Si in the outer detonated He shell. We close by discussing how the unbound helium burning ashes may create faint and fast 'Ia' supernovae as well as events with virtually no radioactivity, and speculate on how the slower helium detonation velocities impact the off-center ignition of a carbon detonation that could cause a Type Ia supernova in the double detonation scenario.

Moore, Kevin; Bildsten, Lars [Department of Physics, University of California, Santa Barbara, CA (United States); Townsley, Dean M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL (United States)

2013-10-20T23:59:59.000Z

331

Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation  

SciTech Connect (OSTI)

This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

Maziasz, P.J.

1985-11-01T23:59:59.000Z

332

Helium effects on the mechanical properties of neutron-irradiated Cr-Mo ferritic steels  

SciTech Connect (OSTI)

In the first wall of a fusion rector, large amounts of transmutation helium will be produced simultaneously with the displacement damage caused by high-energy neutrons from the fusion reaction. One method used to simulate irradiation effects for ferritic steels is to add nickel to the steels and irradiate them in a mixed-spectrum reactor. Fast neutrons in the spectrum produce displacement damage, while transmutation helium is produced by a two-step reaction of {sup 58}Ni with thermal neutrons. This technique has been used to investigate the effect of helium on tensile properties and toughness. Results from these studies are summarized.

Klueh, R.L.

1990-01-01T23:59:59.000Z

333

Simulations of the effect of final state interactions on the scattering reponses of helium droplets  

E-Print Network [OSTI]

and Koonin. They show that FSI broadens the peak in Frx and produces results more in agreement with experimental data. For a Helium droplet, our computation indicates that F with FSI is also broader than FrA. From the similarity between bulk Helium... with and without considering FSI, namely, F and Fix, for bulk Helium. In their computation, they first used monte Carlo method (MC) to calculate FrA(rs pi) and F, pi's modified form corresponding to FSI. Then they transformed pi and F into Fix and E...

Yang, Jian

1996-01-01T23:59:59.000Z

334

Development of a Mass Flowmeter based on the Coriolis Acceleration for Liquid, Supercritical and Superfluid Helium  

E-Print Network [OSTI]

Beginning in the 1980's, Coriolis meters have gained generalised acceptance in liquid applications with a worldwide installed base of over 300,000 units. To meet the demands of cryogenic applications below 20 K, off-the-shelf Coriolis meters have been used, with minor design modifications and operational changes. The meters were originally calibrated on water and tested on liquid helium at 4.5 K, supercritical helium around 5 K and superfluid helium below 2 K. The meters maintain their intrinsic robustness and accuracy of better than 1% of measured value; accuracy is independent of density and temperature.

De Jonge, T; Rivetti, A; Serio, L

2002-01-01T23:59:59.000Z

335

EVIDENCE FOR MAGNESIUM ISOTOPE HETEROGENEITY IN THE SOLAR PROTOPLANETARY DISK  

SciTech Connect (OSTI)

With a half-life of 0.73 Myr, the {sup 26}Al-to-{sup 26}Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of {sup 26}Al-{sup 26}Mg ages of meteorites and their components relies on the critical assumption that the canonical {sup 26}Al/{sup 27}Al ratio of {approx}5 x 10{sup -5} recorded by the oldest dated solids, calcium-aluminium-rich inclusions (CAIs), represents the initial abundance of {sup 26}Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent {sup 26}Mg composition ({mu}{sup 26}Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of {sup 26}Al across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U-Pb and {sup 26}Al-{sup 26}Mg ages of pristine solar system materials, we infer that the bulk of the {mu}{sup 26}Mg* variability reflects heterogeneity in the initial abundance of {sup 26}Al across the solar protoplanetary disk. We conclude that the canonical value of {approx}5 x 10{sup -5} represents the average initial abundance of {sup 26}Al only in the CAI-forming region, and that large-scale heterogeneity-perhaps up to 80% of the canonical value-may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the {sup 26}Al-{sup 26}Mg system as an accurate early solar system chronometer.

Larsen, Kirsten K.; Trinquier, Anne; Paton, Chad; Schiller, Martin; Wielandt, Daniel; Connelly, James N.; Nordlund, Ake; Krot, Alexander N.; Bizzarro, Martin [Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Copenhagen DK-1350 (Denmark); Ivanova, Marina A. [Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow 119991 (Russian Federation)

2011-07-10T23:59:59.000Z

336

Validation of Electrochemically Modulated Separations Performed On-Line with MC-ICP-MS for Uranium and Plutonium Isotopic Analyses  

SciTech Connect (OSTI)

The most time consuming process in uranium or plutonium isotopic analyses is performing the requisite chromatographic separation of the actinides. Filament preparation for thermal ionization (TIMS) adds further delays, but is generally accepted due to the unmatched performance in trace isotopic analyses. Advances in Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) are beginning to rival the performance of TIMS. Methods, such as Electrochemically Modulated Separations (EMS) can efficiently pre-concentrate U or Pu quite selectively from small solution volumes in a matrix of 0.5 M nitric acid. When performed in-line with ICP-MS, the rapid analyte release from the electrode is fast, and large transient analyte signal enhancements of >100 fold can be achieved as compared to more conventional continuous nebulization of the original starting solution. This makes the approach ideal for very low level isotope ratio measurements. In this paper, some aspects of EMS performance are described. These include low level Pu isotope ratio behavior versus concentration by MC-ICP-MS and uranium rejection characteristics that are also important for reliable low level Pu isotope ratio determinations.

Liezers, Martin; Olsen, Khris B.; Mitroshkov, Alexandre V.; Duckworth, Douglas C.

2010-08-11T23:59:59.000Z

337

Feasibility study of plutonium isotopic analysis of resin beads by nondestructive gamma-ray spectroscopy  

SciTech Connect (OSTI)

We have initiated a feasibility study on the use of nondestructive low-energy gamma-ray spectroscopy for plutonium isotopic analysis on resin beads. Seven resin bead samples were measured, with each sample containing an average of 9 ..mu..g of plutonium; the isotopic compositions of the samples varied over a wide range. The gamma-ray spectroscopy results, obtained from 4-h counting-time measurements, were compared with mass spectrometry results. The average ratios of gamma-ray spectroscopy to mass spectrometry were 1.014 +- 0.025 for /sup 238/Pu//sup 239/Pu, 0.996 +- 0.018 for /sup 240/Pu//sup 239/Pu, and 0.980 +- 0.038 for /sup 241/Pu//sup 239/Pu. The rapid, automated, and accurate nondestructive isotopic analysis of resin beads may be very useful to process technicians and International Atomic Energy Agency inspectors. 3 refs., 1 fig., 3 tabs.

Li, T.K.

1985-01-01T23:59:59.000Z

338

Atom trap trace analysis of krypton isotopes  

SciTech Connect (OSTI)

A new method of ultrasensitive isotope trace analysis has been developed. This method, based on the technique of laser manipulation of neutral atoms, has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton gas sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. This method is free of contamination from other isotopes and elements and can be applied to several different isotope tracers for a wide range of applications. The demonstrated detection efficiency is 1 x 10{sup {minus}7}. System improvements could increase the efficiency by many orders of magnitude.

Bailey, K.; Chen, C. Y.; Du, X.; Li, Y. M.; Lu, Z.-T.; O'Connor, T. P.; Young, L.

1999-11-17T23:59:59.000Z

339

Integration of Nontraditional Isotopic Systems Into Reaction...  

Broader source: Energy.gov (indexed) [DOE]

minerals in geothermal systems (feldspars, epidote, and calcite) often control fracture permeability changes. Measurements of Ca and Sr isotopic fractionation at high...

340

Stable Isotope Protocols: Sampling and Sample Processing  

E-Print Network [OSTI]

plants, benthic microalgae [BMI], benthic macroalgae) andin a dessicator, prior to analysis. A.2 Benthic microalgaeBenthic microalgae (BMI) can be collected for isotope

Levin, Lisa A; Currin, Carolyn

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Integration of Nontraditional Isotopic Systems Into Reaction...  

Broader source: Energy.gov (indexed) [DOE]

of EGS For Exploration, Evaluation of Water-Rock Interaction, and Impacts of Water Chemistry on Reservoir Sustainability Integration of Nontraditional Isotopic Systems Into...

342

axial-flow helium gas: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

per atom (dpa) and helium production levels as a function of position within the high flux regions of a recent conceptual model for the "next-step" fusion device DEMO....

343

Products of High-Energy Deuteron and Helium Ion Bombardments of Copper  

E-Print Network [OSTI]

AND HELIUM ION BOHBARDMENTS OF COPPER D. R. Miller, R. C.observations made when natural copper (stable mass numbersof the Bombardment of Natural Copper with 190 Mev Deuterons

Miller, D.R.

2010-01-01T23:59:59.000Z

344

Helium release rates and ODH calculations from RHIC magnet cooling line failure  

SciTech Connect (OSTI)

A catastrophic failure of the magnet cooling lines, similar to the LHC superconducting bus failure incident, could discharge cold helium into the RHIC tunnel and cause an Oxygen Deficiency Hazard (ODH) problem. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the insulating vacuum volumes and discharging via the reliefs into the RHIC tunnel, had been developed. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces are included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Results, including helium discharge rates, helium inventory loss, and the resulting oxygen concentration in the RHIC tunnel area, are reported. Good agreement had been achieved when comparing the simulation results, a RHIC sector depressurization test measurement, and some simple analytical calculations.

Liaw, C.J.; Than, Y.; Tuozzolo, J.

2011-03-28T23:59:59.000Z

345

On the mechanism of electromagnetic microwave absorption in superfluid helium  

SciTech Connect (OSTI)

In experiments on electromagnetic (EM) wave absorption in the microwave range in superfluid (SF) helium [1-3], a narrow EM field absorption line with a width on the order of (20-200) kHz was observed against the background of a wide absorption band with a width of 30-40 GHz at frequencies f{sub 0} Almost-Equal-To 110-180 GHz corresponding to the roton gap energy {Delta}{sub r}(T) in the temperature range 1.4-2.2 K. Using the so-called flexoelectric mechanism of polarization of helium atoms ({sup 4}He) in the presence of density gradients in SF helium (HeII), we show that nonresonance microwave absorption in the frequency range 170-200 GHz can be due to the existence of time-varying local density gradients produced by roton excitations in the bulk HeII. The absorption bandwidth is determined by the roton-roton scattering time in an equilibrium Boltzmann gas of rotons, which is t{sub r-r} Almost-Equal-To 3.4 Multiplication-Sign 10{sup -11} s at T = 1.4 K and decreases upon heating. We propose that the anomalously narrow microwave resonance absorption line in HeII at the roton frequency f{sub 0}(T) = {Delta}r(T)/2{pi}h appears due to the following two factors: (i) the discrete structure of the spectrum of the surface EM resonator modes in the form of a periodic sequence of narrow peaks and (ii) the presence of a stationary dipole layer in HeII near the resonator surface, which forms due to polarization of {sup 4}He atoms under the action of the density gradient associated with the vanishing of the density of the SF component at the solid wall. For this reason, the relaxation of nonequilibrium rotons generated in such a surface dipole layer is strongly suppressed, and the shape and width of the microwave resonance absorption line are determined by the roton density of states, which has a sharp peak at the edge of the roton gap in the case of weak dissipation. The effective dipole moments of rotons in the dipole layer can be directed either along or across the normal to the resonator surface, which explains the experimentally observed symmetric doublet splitting of the resonance absorption line in an external dc electric field perpendicular to the resonator surface. We show that negative absorption (induced emission) of EM field quanta observed after triggering a Kapitza 'heat gun' occurs when the occupation numbers for roton states due to 'pumping' of rotons exceed the occupation numbers of EM field photons in the resonator.

Pashitskii, E. A., E-mail: pashitsk@iop.kiev.ua; Pentegov, V. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2012-08-15T23:59:59.000Z

346

Gamma Spectrum from Neutron Capture on Tungsten Isotopes  

E-Print Network [OSTI]

FROM NEUTRON CAPTURE ON TUNGSTEN ISOTOPES A. M. HURST ?1,2 ,capture on the stable tungsten isotopes is presented, withknown decay schemes of the tungsten isotopes from neutron

Hurst, Aaron

2011-01-01T23:59:59.000Z

347

CONDITIONS FOR SUCCESSFUL HELIUM DETONATIONS IN ASTROPHYSICAL ENVIRONMENTS  

SciTech Connect (OSTI)

Several models for Type Ia-like supernova events rely on the production of a self-sustained detonation powered by nuclear reactions. In the absence of hydrogen, the fuel that powers these detonations typically consists of either pure helium (He) or a mixture of carbon and oxygen (C/O). Studies that systematically determine the conditions required to initiate detonations in C/O material exist, but until now no analogous investigation of He matter has been conducted. We perform one-dimensional reactive hydrodynamical simulations at a variety of initial density and temperature combinations and find critical length scales for the initiation of He detonations that range between 1 and 10{sup 10} cm. A simple estimate of the length scales over which the total consumption of fuel will occur for steady-state detonations is provided by the Chapman-Jouguet (CJ) formalism. Our initiation lengths are consistently smaller than the corresponding CJ length scales by a factor of {approx}100, providing opportunities for thermonuclear explosions in a wider range of low-mass white dwarfs (WDs) than previously thought possible. We find that virialized WDs with as little mass as 0.24 M{sub Sun} can be detonated, and that even less massive WDs can be detonated if a sizable fraction of their mass is raised to a higher adiabat. That the initiation length is exceeded by the CJ length implies that certain systems may not reach nuclear statistical equilibrium within the time it takes a detonation to traverse the object. In support of this hypothesis, we demonstrate that incomplete burning will occur in the majority of He WD detonations and that {sup 40}Ca, {sup 44}Ti, or {sup 48}Cr, rather than {sup 56}Ni, is the predominant burning product for many of these events. We anticipate that a measure of the quantity of the intermediate-mass elements and {sup 56}Ni produced in a helium-rich thermonuclear explosion can potentially be used to constrain the nature of the progenitor system.

Holcomb, Cole; Guillochon, James; De Colle, Fabio; Ramirez-Ruiz, Enrico [TASC, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2013-07-01T23:59:59.000Z

348

Corrosion behavior of zirconia-coated Hastelloy X in a high-temperature helium environment  

SciTech Connect (OSTI)

The corrosion behavior of Hastelloy X coated with (NiCrAl)/(ZrO/sub 2/-CaC/sub 2/) was examined, after serving as the liner tube of helium engineering demonstration loop (HENDEL) hot gas duct. The Hastelloy X with the ceramic coating system was exposed to high-temperature helium gas for --6000 h. The compositions of oxide films formed on Hastelloy X were entirely different between the noncoated and ceramic-coated tubes.

Kondo, Y.; Fukaya, K.

1989-01-01T23:59:59.000Z

349

Spatial periphery of lithium isotopes  

SciTech Connect (OSTI)

The spatial structure of lithium isotopes is studied with the aid of the charge-exchange and (t, p) reactions on lithium nuclei. It is shown that an excited isobaric-analog state of {sup 6}Li (0{sup +}, 3.56MeV) has a halo structure formed by a proton and a neutron, that, in the {sup 9}Li nucleus, there is virtually no neutron halo, and that {sup 11}Li is a Borromean nucleus formed by a {sup 9}Li core and a two-neutron halo manifesting itself in cigar-like and dineutron configurations.

Galanina, L. I., E-mail: galan_lidiya@mail.ru; Zelenskaja, N. S. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2013-12-15T23:59:59.000Z

350

Eccentric crank variable compression ratio mechanism  

DOE Patents [OSTI]

A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

Lawrence, Keith Edward (Kobe, JP); Moser, William Elliott (Peoria, IL); Roozenboom, Stephan Donald (Washington, IL); Knox, Kevin Jay (Peoria, IL)

2008-05-13T23:59:59.000Z

351

Abundance Ratios in Early-Type Galaxies  

E-Print Network [OSTI]

Although evidence is accumulating that abundance ratios in galaxies are often non-solar, they are far from understood. I resume the current evidence for non-solar abundance ratios, supplementing the recent review by Worthey (1998) with some new results. It appears that the Mg/Fe abundance ratio only depends on the mass of the galaxy, not on the formation time-scale. For massive galaxies [Mg/Fe] > 0, while small galaxies show solar abundance ratios. Information about abundances of other element is scarce, but new evidence is given that [Ca/Fe] is solar, or slightly lower than solar, contrary to what is expected for an alpha-element.

Reynier Peletier

1999-04-21T23:59:59.000Z

352

RAPID FUSION METHOD FOR DETERMINATION OF PLUTONIUM ISOTOPES IN LARGE RICE SAMPLES  

SciTech Connect (OSTI)

A new rapid fusion method for the determination of plutonium in large rice samples has been developed at the Savannah River National Laboratory (Aiken, SC, USA) that can be used to determine very low levels of plutonium isotopes in rice. The recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid, reliable radiochemical analyses for radionuclides in environmental and food samples. Public concern regarding foods, particularly foods such as rice in Japan, highlights the need for analytical techniques that will allow very large sample aliquots of rice to be used for analysis so that very low levels of plutonium isotopes may be detected. The new method to determine plutonium isotopes in large rice samples utilizes a furnace ashing step, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with TEVA Resin? cartridges. The method can be applied to rice sample aliquots as large as 5 kg. Plutonium isotopes can be determined using alpha spectrometry or inductively-coupled plasma mass spectrometry (ICP-MS). The method showed high chemical recoveries and effective removal of interferences. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory plutonium particles are effectively digested. The MDA for a 5 kg rice sample using alpha spectrometry is 7E-5 mBq g{sup -1}. The method can easily be adapted for use by ICP-MS to allow detection of plutonium isotopic ratios.

Maxwell, S.

2013-03-01T23:59:59.000Z

353

Helium/solid powder O-ring leakage correlation experiments  

SciTech Connect (OSTI)

We have developed a method to test powder leakage that has passed O-ring seals. To validate this method we have spiked a test fixture with 98 ng of U and recovered 130 +- 25 ng of U. We did not detect U at a detection limit of 26 ng in a fixture which was treated as a blank. This method has been applied to the leakage of UO/sub 2/ powder passing the type of EPDM O-ring seals used in a SNM shipping cask belonging to PNC. Considering the three experimental tests in which no or very small quantities of U were detected as effective blank test, it appears that the level of external contamination is negligible. Therefore, we believe that the U quantities greater than 26 ng (6 tests) passed the primary O-ring seal. From this limited quantity of data, we observe no apparent correlation between the amount of U measured and either helium leak rate or equivalent tube diameter. The data for the 130/sup 0/C tests indicate the possibility of a U/time relationship; however, more data are needed for verification.

Leisher, W.B.; Weissman, S.H.; Tallant, D.R.; Kubo, M.

1983-01-01T23:59:59.000Z

354

EFFECT OF TRITIUM AND DECAY HELIUM ON WELDMENT FRACTURE TOUGHNESS  

SciTech Connect (OSTI)

The fracture toughness data collected in this study are needed to assess the long-term effects of tritium and its decay product on tritium reservoirs. The results show that tritium and decay helium have negative effects on the fracture toughness properties of stainless steel and its weldments. The data and report from this study has been included in a material property database for use in tritium reservoir modeling efforts like the Technology Investment Program ''Lifecycle Engineering for Tritium Reservoirs''. A number of conclusions can be drawn from the data: (1) For unexposed Type 304L stainless steel, the fracture toughness of weldments was two to three times higher than the base metal toughness. (2) Tritium exposure lowered the fracture toughness properties of both base metals and weldments. This was characterized by lower J{sub Q} values and lower J-da curves. (3) Tritium-exposed-and-aged base metals and weldments had lower fracture toughness values than unexposed ones but still retained good toughness properties.

Morgan, M; Scott West, S; Michael Tosten, M

2006-09-26T23:59:59.000Z

355

CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope...  

Broader source: Energy.gov (indexed) [DOE]

Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G...

356

CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope...  

Broader source: Energy.gov (indexed) [DOE]

Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of...

357

CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope...  

Broader source: Energy.gov (indexed) [DOE]

Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR...

358

CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope...  

Broader source: Energy.gov (indexed) [DOE]

Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR...

359

CRAD, Management- Oak Ridge National Laboratory High Flux Isotope...  

Broader source: Energy.gov (indexed) [DOE]

Management- Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C...

360

Enriched Stable Isotope Materials and Chemistry | ornl.gov  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Enriched Stable Isotope Materials and Chemistry SHARE Enriched Stable Isotope Materials and Chemistry Reductiondistillation of calcium-48 metal valued at over 900,000. An...

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Fractionation of Oxygen Isotopes in Phosphate during its Interactions...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Fractionation of Oxygen Isotopes in Phosphate during its Interactions with Iron Oxides. Fractionation of Oxygen Isotopes in Phosphate during its Interactions with Iron Oxides....

362

applied isotope techniques: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

M. 22 Applied Radiation and Isotopes 55 (2001) 707713 Bronchial dosimeter for radon progeny Biology and Medicine Websites Summary: Applied Radiation and Isotopes 55 (2001)...

363

The Quest for the Heaviest Uranium Isotope  

E-Print Network [OSTI]

We study Uranium isotopes and surrounding elements at very large neutron number excess. Relativistic mean field and Skyrme-type approaches with different parametrizations are used in the study. Most models show clear indications for isotopes that are stable with respect to neutron emission far beyond N=184 up to the range of around N=258.

S. Schramm; D. Gridnev; D. V. Tarasov; V. N. Tarasov; W. Greiner

2012-01-17T23:59:59.000Z

364

Positive and inverse isotope effect on superconductivity  

E-Print Network [OSTI]

This article improves the BCS theory to include the inverse isotope effect on superconductivity. An affective model can be deduced from the model including electron-phonon interactions, and the phonon-induced attraction is simply and clearly explained on the electron Green function. The focus of this work is on how the positive or inverse isotope effect occurs in superconductors.

Tian De Cao

2009-09-04T23:59:59.000Z

365

Isotope separation by selective photodissociation of glyoxal  

DOE Patents [OSTI]

Dissociation products, mainly formaldehyde and carbon monoxide, enriched in a desired isotope of carbon, oxygen, or hydrogen are obtained by the selective photodissociation of glyoxal wherein glyoxal is subjected to electromagnetic radiation of a predetermined wavelength such that photon absorption excites and induces dissociation of only those molecules of glyoxal containing the desired isotope.

Marling, John B. (Pleasanton, CA)

1976-01-01T23:59:59.000Z

366

Advanced Mass Spectrometers for Hydrogen Isotope Analyses  

SciTech Connect (OSTI)

This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.

Chastagner, P.

2001-08-01T23:59:59.000Z

367

Production ratio of meta-stable isomer in {sup 180}Ta by neutrino-induced reactions  

SciTech Connect (OSTI)

The nucleosynthesis of {sup 180}Ta has remained an unsolved problem and as its origin many nucleosynthesis mechanisms have been proposed. This isotope has the unique feature that the naturally occurring abundance of {sup 180}Ta is actually a meta-stable isomer (half-life of >=10{sup 15} yr), while the ground state is a 1{sup +} unstable state which beta-decays with a half-life of only 8.15 hr. We have made a new time-dependent calculation of {sup 180}Ta meta-stable isomer residual ratio after supernova neutrino-induced reactions. This isomer residual ratio is crucial for understanding the production and survival of this naturally occurring rare isotope. We have constructed a new model under temperature evolution after type II supernova explosion. We include the explicit linking between the isomer and all known excited states and found that the residual ratio is insensitive to astrophysical parameters such as neutrino energy spectrum, explosion energy, decay time constant. We find that the explicit time evolution of the synthesis of {sup 180}Ta avoids the overproduction relative to {sup 138}La for a neutrino process neutrino temperature of 4 MeV.

Hayakawa, Takehito [Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Kajino, Toshitaka [National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, Satoshi [Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-11 (Japan); Mathews, Grant [Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2010-05-12T23:59:59.000Z

368

Isotopes  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

are saving lives, advancing cutting-edge research and keeping the U.S. safe. Strontium-82 produced at Los Alamos is used in hospitals nation- and world-wide for critical...

369

ISOTOPES  

E-Print Network [OSTI]

1955). Production of Heavy water, 37. G.M. Keyser, D.B.Economy of Production of Heavy Water, Turin, Italy (1970),world production of heavy water to ~1ay, 1977. From data

Lederer, C. Michael

2013-01-01T23:59:59.000Z

370

ISOTOPES  

E-Print Network [OSTI]

constructed to enrich liquid UF6 slightly as feed for thej) b. Optimum a. s: .X. UF6 feed, (kg per year) XBL 7912 -

Lederer, C. Michael

2013-01-01T23:59:59.000Z

371

Isotopes  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFunInfrared LandResponsesIon/SurfacePump-Testing Sign

372

ISOTOPES  

E-Print Network [OSTI]

5-7. 1975, British Nuclear Engineering Society (1975). 87.London, March British Nuclear Engineering Society (1975).T.H. Pigford, Nuclear Chemical Engineering (1St edition),

Lederer, C. Michael

2013-01-01T23:59:59.000Z

373

High flux isotope reactor cold source preconceptual design study report  

SciTech Connect (OSTI)

In February 1995, the deputy director of Oak Ridge National Laboratory (ORNL) formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced Neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. The anticipated cold source will consist of a cryogenic LH{sub 2} moderator plug, a cryogenic pump system, a refrigerator that uses helium gas as a refrigerant, a heat exchanger to interface the refrigerant with the hydrogen loop, liquid hydrogen transfer lines, a gas handling system that includes vacuum lines, and an instrumentation and control system to provide constant system status monitoring and to maintain system stability. The scope of this project includes the development, design, safety analysis, procurement/fabrication, testing, and installation of all of the components necessary to produce a working cold source within an existing HFIR beam tube. This project will also include those activities necessary to transport the cold neutron beam to the front face of the present HFIR beam room. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and research and development (R and D), (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the preconceptual phase and establishes the concept feasibility. The information presented includes the project scope, the preliminary design requirements, the preliminary cost and schedule, the preliminary performance data, and an outline of the various plans for completing the project.

Selby, D.L.; Bucholz, J.A.; Burnette, S.E. [and others

1995-12-01T23:59:59.000Z

374

Chemical and Isotopic Composition and Gas Concentrations of Ground Water and Surface Water from Selected Sites At and Near the Idaho National Engineering and Environmental Laboratory, Idaho, 1994-97  

SciTech Connect (OSTI)

>From May 1994 through May 1997, the US Geological Survey, in cooperation with the US Department of Energy, collected water samples from 86 wells completed in the Snake River Plain aquifer at and near the Idaho National Engineering and Environmental Laboratory. The samples were analyzed for a variety of chemical constituents including all major elements and 22 trace elements. Concentrations of scandium, yttrium, and the lanthanide series were measured in samples from 11 wells and 1 hot spring. The data will be used to determine the fraction of young water in the ground water. The fraction of young water must be known to calculate the ages of ground water using chlorofluorocarbons. The concentrations of the isotopes deuterium, oxygen-18, carbon-13, carbon-14, and tritium were measured in many ground water, surface-water and spring samples. The isotopic composition will provide clues to the origin and sources of water in the Snake River Plain aquifer. Concentrations ! of helium-3 , helium-4, total helium, and neon were measured in most groundwater samples, and the results will be used to determine the recharge temperature, and to date the ground waters.

E. Busenberg; L. N. Plummer; M. W. Doughten; P. K. Widman; R. C. Bartholomay (USGS)

2000-05-30T23:59:59.000Z

375

Symmetry Energy and the Isoscaling in Reactions on Enriched Tin Isotopes  

E-Print Network [OSTI]

The coefficients of symmetry energy term for fragments with Z=4,11,12 measured in multifragmentation reactions initiated by proton and deuteron with energy of 3.65A GeV on enriched tin isotopes 112,118,120,124Sn are determined. The dependence of isoscaling parameter on the excitation energy, the temperature of fragmenting systems and the density ratio for heavy mass products are analised.

A. S. Danagulyan; A. R. Balabekyan; G. H. Hovhannisyan

2009-02-17T23:59:59.000Z

376

Extreme helium stars: non-LTE matters Helium and hydrogen spectra of the unique objects V652 Her and HD144941  

E-Print Network [OSTI]

Quantitative analyses of low-mass hydrogen-deficient (super-)giant stars - so-called extreme helium stars - to date face two major difficulties. First, theory fails to reproduce the observed helium lines in their entirety, wings and line cores. Second, a general mismatch exists for effective temperatures derived from ionization equilibria and from spectral energy distributions. Here, we demonstrate how the issue can be resolved using state-of-the-art non-LTE line-formation for these chemically peculiar objects. Two unique high-gravity B-type objects are discussed in detail, the pulsating variable V652 Her and the metal-poor star HD144941. In the first case atmospheric parameters from published LTE analyses are largely recovered, in the other a systematic offset is found. Hydrogen abundances are systematically smaller than previously reported, by up to a factor ~2. Extreme helium stars turn out to be important testbeds for non-LTE model atoms for helium. Improved non-LTE computations show that analyses assuming LTE or based on older non-LTE model atoms can predict equivalent widths, for the HeI 10830A transition in particular, in error by up to a factor ~3.

N. Przybilla; K. Butler; U. Heber; C. S. Jeffery

2005-10-03T23:59:59.000Z

377

Atomic vapor laser isotope separation of lead-210 isotope  

DOE Patents [OSTI]

An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207.

Scheibner, Karl F. (Tracy, CA); Haynam, Christopher A. (Pleasanton, CA); Johnson, Michael A. (Pleasanton, CA); Worden, Earl F. (Diablo, CA)

1999-01-01T23:59:59.000Z

378

Atomic vapor laser isotope separation of lead-210 isotope  

DOE Patents [OSTI]

An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207. 5 figs.

Scheibner, K.F.; Haynam, C.A.; Johnson, M.A.; Worden, E.F.

1999-08-31T23:59:59.000Z

379

Crystal orientation effects on helium ion depth distributions and adatom formation processes in plasma-facing tungsten  

SciTech Connect (OSTI)

We present atomistic simulations that show the effect of surface orientation on helium depth distributions and surface feature formation as a result of low-energy helium plasma exposure. We find a pronounced effect of surface orientation on the initial depth of implanted helium ions, as well as a difference in reflection and helium retention across different surface orientations. Our results indicate that single helium interstitials are sufficient to induce the formation of adatom/substitutional helium pairs under certain highly corrugated tungsten surfaces, such as (1 1 1)-orientations, leading to the formation of a relatively concentrated layer of immobile helium immediately below the surface. The energies involved for helium-induced adatom formation on (1 1 1) and (2 1 1) surfaces are exoergic for even a single adatom very close to the surface, while (0 0 1) and (0 1 1) surfaces require two or even three helium atoms in a cluster before a substitutional helium cluster and adatom will form with reasonable probability. This phenomenon results in much higher initial helium retention during helium plasma exposure to (1 1 1) and (2 1 1) tungsten surfaces than is observed for (0 0 1) or (0 1 1) surfaces and is much higher than can be attributed to differences in the initial depth distributions alone. The layer thus formed may serve as nucleation sites for further bubble formation and growth or as a source of material embrittlement or fatigue, which may have implications for the formation of tungsten “fuzz” in plasma-facing divertors for magnetic-confinement nuclear fusion reactors and/or the lifetime of such divertors.

Hammond, Karl D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996–2300 (United States); Wirth, Brian D., E-mail: bdwirth@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996–2300 (United States); P.O. Box 2008, MS-6003, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831–6003 (United States)

2014-10-14T23:59:59.000Z

380

Hydrogen and helium traces in type Ib-c supernovae  

E-Print Network [OSTI]

The spectroscopic properties of a selected optical photospheric spectra of core collapse supernovae (CCSNe) are investigated.Special attention is devoted to traces of hydrogen at early phases. The generated spectra are found to match the observed ones reasonably well, including a list of only 23 candidate ions. Guided by SN Ib 1990I, the observed trough near 6300\\AA is attributed to H$\\alpha$ in almost all Type Ib events, although in some objects it becomes too weak to be discernible, especially at later phases. Alternative line identifications are discussed. Differences in the way hydrogen manifests its presence within CCSNe are highlighted. In Type Ib SNe, the H$\\alpha$ contrast velocity (i.e. line velocity minus the photospheric velocity) seems to increase with time at early epochs, reaching values as high as 8000 km s$^{-1}$ around 15-20 days after maximum and then remains almost constant. The derived photospheric velocities, indicate a lower velocity for Type II SNe 1987A and 1999em as compared to SN Ic 1994I and SN IIb 1993J, while Type Ib events display a somewhat larger variation. The scatter, around day 20, is measured to be $\\sim$5000 km s$^{-1}$. Following two simple approaches, rough estimates of ejecta and hydrogen masses are given. A mass of hydrogen of approximately 0.02 $M_\\odot$ is obtained for SN 1990I, while SNe 1983N and 2000H ejected $\\sim$0.008 $M_\\odot$ and $\\sim$0.08 $M_\\odot$ of hydrogen, respectively. SN 1993J has a higher hydrogen mass, $\\sim 0.7$ $M_\\odot$ with a large uncertainty. A low mass and thin hydrogen layer with very high ejection velocities above the helium shell, is thus the most likely scenario for Type Ib SNe. Some interesting and curious issues relating to oxygen lines suggest future investigations.

A. Elmhamdi; I. J. Danziger; D. Branch; B. Leibundgut; E. Baron; R. P. Kirshner

2006-04-04T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Strontium isotopic study of subsurface brines from Illinois basin  

SciTech Connect (OSTI)

The abundance of the radiogenic isotope /sup 87/Sr in a subsurface brine can be used as a tracer of brine origin, evolution, and diagenetic effects. The authors have determined the /sup 87/Sr//sup 86/Sr ratios of over 60 oil-field waters from the Illinois basin, where brine origin is perplexing because of the absence of any significant evaporite strata. Initially, they analyzed brines from 15 petroleum-producing sandstone and carbonate units; waters from Ordovician, Silurian, Devonian, and Mississippian strata have /sup 87/Sr//sup 86/Sr ratios in the range 0.7079-0.7108. All but those from the Ste. Genevieve Limestone (middle Mississippian) are more radiogenic in /sup 87/Sr//sup 86/Sr than seawater values for this interval of geologic time. The detrital source of the more radiogenic /sup 87/Sr may be the New Albany Shale group, considered to be a major petroleum source rock in the basin. The /sup 87/Sr//sup 86/Sr ratios of Ste. Genevieve brines apparently evolved without a contribution from fluid-shale interaction.

hetherington, E.A.; Stueber, A.M.; Pushkar, P.

1986-05-01T23:59:59.000Z

382

Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments  

SciTech Connect (OSTI)

The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the helium coolant. • Evaluate grain boundary engineering as a method to mitigate stress-assisted grain boundary oxidation and creep crack growth of candidate alloys in impure helium. The maximum primary helium coolant temperature in the high-temperature reactor is expected to be 850-1,000°C.Corrosion may involve oxidation, carburization, or decarburization mechanisms depending on the temperature, oxygen partial pressure, carbon activity, and alloy composition. These corrosion reactions can substantially affect long-term mechanical properties such as crack- growth rate and fracture toughness, creep rupture, and fatigue. Although there are some studies on the effects of impurities in helium coolant on creep rupture and fatigue strength, very little is known about their effects on creep crack initiation and crack growth rate at elevated temperatures.

Crone, Wendy; Cao, Guoping; Sridhara, Kumar

2013-05-31T23:59:59.000Z

383

Natural thorium isotopes in marine sediment core off Labuan port  

SciTech Connect (OSTI)

Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R. [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600, Bangi, Selangor (Malaysia)

2014-02-12T23:59:59.000Z

384

Helium release and microstructural changes in Er(D,T)2-x3Hex films).  

SciTech Connect (OSTI)

Er(D,T){sub 2-x} {sup 3}He{sub x}, erbium di-tritide, films of thicknesses 500 nm, 400 nm, 300 nm, 200 nm, and 100 nm were grown and analyzed by Transmission Electron Microscopy, X-Ray Diffraction, and Ion Beam Analysis to determine variations in film microstructure as a function of film thickness and age, due to the time-dependent build-up of {sup 3}He in the film from the radioactive decay of tritium. Several interesting features were observed: One, the amount of helium released as a function of film thickness is relatively constant. This suggests that the helium is being released only from the near surface region and that the helium is not diffusing to the surface from the bulk of the film. Two, lenticular helium bubbles are observed as a result of the radioactive decay of tritium into {sup 3}He. These bubbles grow along the [111] crystallographic direction. Three, a helium bubble free zone, or 'denuded zone' is observed near the surface. The size of this region is independent of film thickness. Four, an analysis of secondary diffraction spots in the Transmission Electron Microscopy study indicate that small erbium oxide precipitates, 5-10 nm in size, exist throughout the film. Further, all of the films had large erbium oxide inclusions, in many cases these inclusions span the depth of the film.

Gelles, D. S. (Pacific Northwest National Laboratory, Richland, WA); Browning, James Frederick; Snow, Clark Sheldon; Banks, James Clifford; Mangan, Michael A.; Rodriguez, Mark Andrew; Brewer, Luke N.; Kotula, Paul Gabriel

2007-12-01T23:59:59.000Z

385

Effects of Helium Phase Separation on the Evolution of Giant Planets  

E-Print Network [OSTI]

We present the first models of Saturn and Jupiter to couple their evolution to both a radiative-atmosphere grid and to high-pressure phase diagrams of hydrogen with helium. The purpose of these models is to quantify the evolutionary effects of helium phase separation in Saturn's deep interior. We find that prior calculated phase diagrams in which Saturn's interior reaches a region of predicted helium immiscibility do not allow enough energy release to prolong Saturn's cooling to its known age and effective temperature. We explore modifications to published phase diagrams that would lead to greater energy release, and find a modified H-He phase diagram that is physically reasonable, leads to the correct extension of Saturn's cooling, and predicts an atmospheric helium mass fraction Y_atmos in agreement with recent estimates. We then expand our inhomogeneous evolutionary models to show that hypothetical extrasolar giant planets in the 0.15 to 3.0 Jupiter mass range may have T_effs 10-15 K greater than one would predict with models that do not incorporate helium phase separation.

Jonathan J. Fortney; W. B. Hubbard

2003-12-15T23:59:59.000Z

386

A theoretical and experimental study of pressure broadening of the oxygen A-band by helium  

SciTech Connect (OSTI)

The rotationally resolved magnetic dipole absorption spectrum of the oxygen A-band b{sup 1}?{sub g}{sup +}(v=0)?X{sup 3}?{sub g}{sup ?}(v=0) perturbed by collisions with helium was studied theoretically using the impact approximation. To calculate the relaxation matrix, scattering calculations were performed on a newly computed helium-oxygen (b{sup 1}?{sub g}{sup +}) interaction potential as well as on a helium-oxygen (X{sup 3}?{sub g}{sup ?}) interaction potential from the literature. The calculated integrated line cross sections and broadening coefficients are in good agreement with experimental results from the literature. Additionally, cavity ring-down experiments were performed in the wings of the spectral lines for a quantitative study of line-mixing, i.e., the redistribution of rotational line intensities by helium-oxygen collisions. It is shown that inclusion of line-mixing in the theory is required to reproduce the experimentally determined absolute absorption strengths as a function of the density of the helium gas.

Grimminck, Dennis L. A. G.; Spiering, Frans R.; Janssen, Liesbeth M. C.; Avoird, Ad van der; Zande, Wim J. van der; Groenenboom, Gerrit C., E-mail: Gerritg@theochem.ru.nl [Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)

2014-05-28T23:59:59.000Z

387

Determination of the 242Pu Branching Ratio via Alpha-Gamma Coincidence  

SciTech Connect (OSTI)

When the burn-up is high, the {sup 242}Pu isotopic content becomes more important. The traditional correlation method will fail. The {sup 242}Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) {sup 242}Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin {sup 242}Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.

Wang, T F

2012-05-24T23:59:59.000Z

388

Effect of Compression Ratio and Piston Geometry on RCCI load...  

Broader source: Energy.gov (indexed) [DOE]

Compression Ratio and Piston Geometry on RCCI load limit Effect of Compression Ratio and Piston Geometry on RCCI load limit Explores the effect of compression ratio and piston...

389

8, 41994219, 2008 Study of the ratios  

E-Print Network [OSTI]

(UV) spectra of atmospheric global irradiance with the miniature fiber optic spectrometer AvaSpec-256ACPD 8, 4199­4219, 2008 Study of the ratios UV-A/UV-B from UV irradiance spectra I. Ansko et al@aai.ee) 4199 #12;ACPD 8, 4199­4219, 2008 Study of the ratios UV-A/UV-B from UV irradiance spectra I. Ansko et

Boyer, Edmond

390

- and -delayed neutron- decay of neutron-rich copper isotopes  

SciTech Connect (OSTI)

The {beta}-decay properties of neutron-rich Cu isotopes produced in proton-induced fission of {sup 238}U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The data were collected using high-resolution online mass separation, reacceleration, and digital {beta}-{gamma} spectroscopy methods. An improved decay scheme of N = 49 {sup 78}Cu and the first observation of N = 50 {sup 79}Cu {beta}-delayed neutron decay followed by a gamma transition are reported. Spin and parity (5{sup -}) are deduced for {sup 78gs}Cu. The {beta}-delayed neutron branching ratios (P{sub {beta}n}) for the {sup 77}Cu and {sup 79}Cu precursors are analyzed with the help of nuclear structure models.

Korgul, A. [University of Warsaw; Rykaczewski, Krzysztof Piotr [ORNL; Winger, J. A. [Oak Ridge Associated Universities (ORAU); Ilyushkin, S. [Mississippi State University (MSU); Gross, Carl J [ORNL; Batchelder, J. C. [Oak Ridge Associated Universities (ORAU); Bingham, C. R. [University of Tennessee, Knoxville (UTK); Borzov, Ivan N [ORNL; Goodin, C. [Vanderbilt University; Grzywacz, Robert Kazimierz [ORNL; Hamilton, Joseph H [ORNL; Krolas, W. [Joint Institute for Heavy Ion Research, Oak Ridge; Liddick, S. N. [Oak Ridge Associated Universities (ORAU); Mazzocchi, C. [University of Warsaw; Nelson, C. [Vanderbilt University; Nowacki, F. [Institut Pluridisciplinaire Hubert Curien, Strasbourg, France; Padgett, Stephen [University of Tennessee, Knoxville (UTK); Piechaczek, A. [Louisiana State University; Rajabali, M. M. [University of Tennessee, Knoxville (UTK); Shapira, Dan [ORNL; Sieja, K. [Technische Universitat Darmstadt, Germany; Zganjar, E. F. [Louisiana State University

2012-01-01T23:59:59.000Z

391

HELIUM SHELL DETONATIONS ON LOW-MASS WHITE DWARFS AS A POSSIBLE EXPLANATION FOR SN 2005E  

SciTech Connect (OSTI)

Recently, several Type Ib supernovae (SNe; with the prototypical SN 2005E) have been shown to have atypical properties. These SNe are faint (absolute peak magnitude of {approx} - 15) and fast SNe that show unique composition. They are inferred to have low ejecta mass (a few tenths of a solar mass) and to be highly enriched in calcium, but poor in silicon elements and nickel. These SNe were therefore suggested to belong to a new class of calcium-rich faint SNe explosions. Their properties were proposed to be the result of helium detonations that may occur on helium accreting white dwarfs. In this paper, we theoretically study the scenario of helium detonations and focus on the results of detonations in accreted helium layers on low-mass carbon-oxygen (CO) cores. We present new results from one-dimensional simulations of such explosions, including their light curves and spectra. We find that when the density of the helium layer is low enough the helium detonation produces large amounts of intermediate elements, such as calcium and titanium, together with a large amount of unburnt helium. Alternatively, enough carbon enrichment of the accreted helium as a result of convective undershoot at the early stages of the runaway can avoid the production of iron group elements as the alpha particles are consumed avoiding iron production. Our results suggest that the properties of calcium-rich faint SNe could indeed be consistent with the helium-detonation scenario on small CO cores. Above a certain density (larger CO cores) the detonation leaves mainly {sup 56}Ni and unburnt helium, and the predicted spectrum will unlikely fit the unique features of this class of SNe. Finally, none of our studied models reproduces the bright, fast-evolving light curves of another type of peculiar SNe suggested to originate in helium detonations (SNe 1885A, 1939B, and 2002bj).

Waldman, Roni; Livne, Eli; Glasner, Ami [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Sauer, Daniel [Stockholm University, Department for Astronomy, AlbaNova University Center, 106 91 Stockholm (Sweden); Perets, Hagai [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mazzali, Paolo [Max-Planck Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching (Germany); Truran, James W. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Gal-Yam, Avishay [Benoziyo Center for Astrophysics, Faculty of Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

2011-09-01T23:59:59.000Z

392

Commissioning of helium compression system for the 12 GeV refrigerator  

SciTech Connect (OSTI)

The compressor system used for the Jefferson Lab (JLab) 12 GeV upgrade, also known as the CHL-2 compressor system, incorporates many design changes to the typical compressor skid design to improve the efficiency, reliability and maintainability from previous systems. These include a considerably smaller bulk oil separator design that does not use coalescing elements/media, automated control of cooling oil injection based on the helium discharge temperature, a helium after-cooler design that is designed for and promotes coalescing of residual oil and a variable speed bearing oil pump to reduce oil bypass. The CHL-2 helium compression system has five compressors configured with four pressure levels that supports the three pressure levels in the cold box. This paper will briefly review several of these improvements and discuss some of the recent commissioning results.

Knudsen, Peter N. [JLAB; Ganni, Venkatarao [JLAB; Dixon, Kelly D. [JLAB; Norton, Robert O. [JLAB; Creel, Jonathan D. [JLAB; Arenius, Dana M. [JLAb

2014-01-01T23:59:59.000Z

393

The role of HeH+ in cool helium rich white dwarfs  

E-Print Network [OSTI]

HeH$^+$ is found to be the dominant positive ion over a wide range of temperatures and densities relevant to helium rich white dwarfs. The inclusion of HeH$^+$ in ionization equilibrium computations increases the abundance of free electrons by a significant factor. For temperatures below 8000 K, He$^-$ free-free absorption is increased by up to a factor of 5, by the inclusion of HeH$^+$. Illustrative model atmospheres and spectral energy distributions are computed, which show that HeH$^+$ has a strong effect upon the density and pressure structure of helium rich white dwarfs with teff < 8000 K. The inclusion of HeH$^+$ significantly reddens spectral energy distributions and broad band color indices for models with Teff < 5500 K. This has serious implications for existing model atmospheres, synthetic spectra and cooling curves for helium rich white dwarfs.

G. J. Harris; A. E. Lynas-Gray; S. Miller; J. Tennyson

2004-11-12T23:59:59.000Z

394

Nonequilibrium clumped isotope signals in microbial methane  

E-Print Network [OSTI]

Methane is a key component in the global carbon cycle with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its ...

Wang, David T.

395

A SUPERCONDUCTING-SOLENOID ISOTOPE SPECTROMETER  

E-Print Network [OSTI]

A SUPERCONDUCTING-SOLENOID ISOTOPE SPECTROMETER FOR PRODUCTION OF NEUTRON-RICH NUCLEI ( 136 Xe Superconducting Cyclotron Laboratory's weekly \\Green Sheet," 30 July 1999 #12; c Thomas W. O'Donnell 2000 All

O'Donnell, Tom

396

The Oxygen core inside the Magnesium isotopes  

E-Print Network [OSTI]

We have studied the ground state bulk properties of magnesium isotopes using axially symmetric relativistic mean field formalism. The BCS pairing approach is employed to take care of the pairing correlation for the open shell nuclei. The contour plot of the nucleons distribution are analyzed at various parts of the nucleus, where clusters are located. The presence of an $^{16}$O core along bubble like $\\alpha$-particle(s) and few {\\it nucleons} are found in the Mg isotopes.

Bhuyan, M

2013-01-01T23:59:59.000Z

397

Mechanistic studies using kinetic isotope effects  

E-Print Network [OSTI]

MECHANISTIC STUDIES USING KINETIC ISOTOPE EFFECTS A Thesis by BRIAN E. SCHULMFIER Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requtrements for the degree of MASTER OF SCIENCE December... 1999 Major Subject: Chemistry MECHANISTIC STUDIES USING KINETIC ISOTOPE EFFECTS A Thesis by BRIAN E. SCHULMEIER Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved...

Schulmeier, Brian E.

2012-06-07T23:59:59.000Z

398

The Evolution of Low Mass Helium Stars towards Supernova Type I Explosion  

E-Print Network [OSTI]

We explore the hypothesis, that helium stars in a certain mass range can evolve to a carbon core explosion similar to what is widely accepted as an explanation for the SN I phenomenon. This should happen when their carbon-oxygen core grows thanks to the helium shell burning above the core. We found that in the mass range of about 1.7-2.2 Msun, indeed this can happen. The main new insight we believe we gained is the crucial importance of an "early" off-center ignition of carbon, which at a later stage prevents the carbon which forms below the helium burning shell and ignites, from burning the carbon all the way to the center. When helium is almost depleted in the convective envelope by the helium burning shell at its bottom, the now super-Chandrasekhar mass carbon-oxygen core contracts, and the residual degenerate carbon at the center is ignited, resulting in a runaway similar to the classical SN I scenario. Since the structure and behavior of the carbon-oxygen core of the helium stars of our interest is very similar to that of a mass accreting carbon-oxygen star, we also thoroughly examined the behavior of carbon-oxygen stars. We discovered that the models which ignite carbon off-center (in the mass range of about 1.05-1.18 Msun, depending on the carbon mass fraction) present an interesting SN I progenitor scenario of their own, since whereas in the standard scenario runaway always takes place at the same density of about 2E9 gr/cm3, in our case, due to the small amount of carbon ignited, we get a whole range of densities from 1E9 up to 6E9 gr/cm3.

Roni Waldman; Zalman Barkat

2006-11-21T23:59:59.000Z

399

Influence of liquid structure on diffusive isotope separation in molten silicates and aqueous solutions  

SciTech Connect (OSTI)

Molecular diffusion in natural volcanic liquids discriminates between isotopes of major ions (e.g., Fe, Mg, Ca, and Li). Although isotope separation by diffusion is expected on theoretical grounds, the dependence on mass is highly variable for different elements and in different media. Silicate liquid diffusion experiments using simple liquid compositions were carried out to further probe the compositional dependence of diffusive isotopic discrimination and its relationship to liquid structure. Two diffusion couples consisting of the mineral constituents anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}; denoted AN), albite (NaAlSi{sub 3}O{sub 8}; denoted AB), and diopside (CaMgSi{sub 2}O{sub 6}; denoted DI) were held at 1450°C for 2 h and then quenched to ambient pressure and temperature. Major-element as well as Ca and Mg isotope profiles were measured on the recovered quenched glasses. In both experiments, Ca diffuses rapidly with respect to Si. In the AB–AN experiment, D{sub Ca}/D{sub Si} ~ 20 and the efficiency of isotope separation for Ca is much greater than in natural liquid experiments where D{sub Ca}/D{sub Si} ~ 1. In the AB–DI experiment, D{sub Ca}/D{sub Si} ~ 6 and the efficiency of isotope separation is between that of the natural liquid experiments and the AB–AN experiment. In the AB–DI experiment, D{sub Mg}/D{sub Si} ~ 1 and the efficiency of isotope separation for Mg is smaller than it is for Ca yet similar to that observed for Mg in natural liquids. The results from the experiments reported here, in combination with results from natural volcanic liquids, show clearly that the efficiency of diffusive separation of Ca isotopes is systematically related to the solvent-normalized diffusivity—the ratio of the diffusivity of the cation (D{sub Ca}) to the diffusivity of silicon (D{sub Si}). The results on Ca isotopes are consistent with available data on Fe, Li, and Mg isotopes in silicate liquids, when considered in terms of the parameter D{sub cation}/D{sub Si}. Cations diffusing in aqueous solutions display a similar relationship between isotopic separation efficiency and D{sub cation} =D{sub H 2 O} , although the efficiencies are smaller than in silicate liquids. Our empirical relationship provides a tool for predicting the magnitude of diffusive isotopic effects in many geologic environments and a basis for a more comprehensive theory of isotope separation in liquid solutions. We present a conceptual model for the relationship between diffusivity and liquid structure that is consistent with available data.

Watkins, J.M.; DePaolo, D.J.; Ryerson, F.J.; Peterson, B.

2011-03-01T23:59:59.000Z

400

The Chemical Evolution of Helium in Globular Clusters: Implications for the Self-Pollution Scenario  

E-Print Network [OSTI]

We investigate the suggestion that there are stellar populations in some globular clusters with enhanced helium (Y from 0.28 to 0.40) compared to the primordial value. We assume that a previous generation of massive Asymptotic Giant Branch (AGB) stars have polluted the cluster. Two independent sets of AGB yields are used to follow the evolution of helium and CNO using a Salpeter initial mass function (IMF) and two top-heavy IMFs. In no case are we able to produce the postulated large Y ~ 0.35 without violating the observational constraint that the CNO content is nearly constant.

Amanda Karakas; Yeshe Fenner; Alison Sills; Simon Campbell; John Lattanzio

2006-08-17T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Excitation of autoionizing states of helium-like ions by scattering of high-energy particles  

SciTech Connect (OSTI)

The cross sections for two-electron excitations of helium-like atomic systems into the autoionizing 2s{sup 2} ({sup 1}S)- and 2p{sup 2} ({sup 1}S)-states by collisions with high-energy electrons and photons are deduced. The evaluations are performed to the leading order of non-relativistic perturbation theory. The analytical formulas for cross sections are obtained in the form of universal scalings. A comparison of our theoretical predictions with available theoretical and experimental results for the helium atom is made.

Mikhailov, A. I.; Mikhailov, I. A.; Nefiodov, A. V., E-mail: anef@thd.pnpi.spb.ru [B. P. Konstantinov Petersburg Nuclear Physics Institute (Russian Federation); Plunien, G. [Technische Universitaet Dresden, Institut fuer Theoretische Physik (Germany)] [Technische Universitaet Dresden, Institut fuer Theoretische Physik (Germany)

2013-03-15T23:59:59.000Z

402

Application of JLab 12GeV helium refrigeration system for the FRIB accelerator at MSU  

SciTech Connect (OSTI)

The planned approach to have a turnkey helium refrigeration system for the MSU-FRIB accelerator system, encompassing the design, fabrication, installation and commissioning of the 4.5-K refrigerator cold box(es), cold compression system, warm compression system, gas management, oil removal and utility/ancillary systems, was found to be cost prohibitive. Following JLab’s suggestion, MSU-FRIB accelerator management made a formal request to evaluate the applicability of the recently designed 12GeV JLab cryogenic system for this application. The following paper will outline the findings and the planned approach for the FRIB helium refrigeration system.

Ganni, V.; Knudsen, P.; Arenius, D. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Casagrande, F. [MSU-FRIB, East Lansing, MI 48824 (United States)

2014-01-29T23:59:59.000Z

403

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas  

SciTech Connect (OSTI)

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29T23:59:59.000Z

404

Particle Detection in Superfluid Helium: R&D for Low Energy Solar Neutrinos  

SciTech Connect (OSTI)

This report presents a summary of the results from R&D conducted as a feasibility study in the Department of Physics of Brown University for detection of low energy solar neutrinos utilizing a superfluid helium target. The report outlines the results in several areas: 1) development of experimental facilities, 2) energy deposition by electrons and alphas in superfluid helium, 3) development of wafer and metallic magnetic calorimeters, 4) background studies, 5) coded apertures and conceptual design, 6) Detection of single electrons and 7) a simulation of expected performance of a full scale device. Recommendations for possible future work are also presented. A bibliography of published papers and unpublished doctoral theses is included.

Lanou, Robert E., Jr.

2006-03-31T23:59:59.000Z

405

High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium  

SciTech Connect (OSTI)

Work on the HTGR Helium Compatibility Task accomplished during the period March 31, 1977 through September 30, 1979, is documented in this report. Emphasis is on the results and analyses of creep data to 10,000 h and the detailed metallurgical evaluations performed on candidate alloy specimens tested for up to 10,000 h. Long-term creep and unstressed aging data in controlled-impurity helium and in air at 800, 900, and 1000/sup 0/C are reported for alloys included in the program in FY-76, including the wrought solid-solution-strengthened alloys, Hastelloy X, Hastelloy S, RA 333, and HD 556, and the centrifugally cast austenitic alloys, HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900.

Lechtenberg, T.A.; Stevenson, R.D.; Johnson, W.R.

1980-05-01T23:59:59.000Z

406

Strontium and carbon isotope stratigraphy of the Llandovery (Early Silurian): Implications for tectonics and weathering  

E-Print Network [OSTI]

Strontium and carbon isotope stratigraphy of the Llandovery (Early Silurian): Implications online 2 June 2010 Keywords: Silurian Strontium isotopes Carbon isotopes Weathering K-bentonites A high

Saltzman, Matthew R.

407

Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: Wavelength, pressure and temperature dependency.  

E-Print Network [OSTI]

Oxygen isotope fractionation in the vacuum ultravioletmeasurement of the associated oxygen isotopic composition ofwavelength dependency of the oxygen isotopic composition in

Chakraborty, Subrata

2013-01-01T23:59:59.000Z

408

THE GENESIS SOLAR WIND CONCENTRATOR TARGET: MASS FRACTIONATION CHARACTERISED BY NE ISOTOPES  

SciTech Connect (OSTI)

The concentrator on Genesis provides samples of increased fluences of solar wind ions for precise determination of the oxygen isotopic composition of the solar wind. The concentration process caused mass fractionation as function of the radial target position. They measured the fractionation using Ne released by UV laser ablation along two arms of the gold cross from the concentrator target to compare measured Ne with modeled Ne. The latter is based on simulations using actual conditions of the solar wind during Genesis operation. Measured Ne abundances and isotopic composition of both arms agree within uncertainties indicating a radial symmetric concentration process. Ne data reveal a maximum concentration factor of {approx} 30% at the target center and a target-wide fractionation of Ne isotopes of 3.8%/amu with monotonously decreasing {sup 20}Ne/{sup 22}Ne ratios towards the center. The experimentally determined data, in particular the isotopic fractionation, differ from the modeled data. They discuss potential reasons and propose future attempts to overcome these disagreements.

WIENS, ROGER C. [Los Alamos National Laboratory; OLINGER, C. [Los Alamos National Laboratory; HEBER, V.S. [Los Alamos National Laboratory; REISENFELD, D.B. [Los Alamos National Laboratory; BURNETT, D.S. [Los Alamos National Laboratory; ALLTON, J.H. [Los Alamos National Laboratory; BAUR, H. [Los Alamos National Laboratory; WIECHERT, U. [Los Alamos National Laboratory; WIELER, R. [Los Alamos National Laboratory

2007-01-02T23:59:59.000Z

409

UW Cosmogenic Isotopes Al-Be 1 EXTRACTION OF Al & Be FROM QUARTZ FOR ISOTOPIC ANALYSIS  

E-Print Network [OSTI]

UW Cosmogenic Isotopes Al-Be 1 EXTRACTION OF Al & Be FROM QUARTZ FOR ISOTOPIC ANALYSIS Summary This method is used to separate Al and Be for AMS analysis from pure quartz samples. After adding Be carrier, quartz is dissolved in HF. The solution is sub-sampled for determination of total Al content, then dried

Stone, John

410

Physics of Aquatic Systems II, 7. Tritium and Helium-3 Universitt HeidelbergInstitut fr Umweltphysik Physics of Aquatic Systems II  

E-Print Network [OSTI]

Physics of Aquatic Systems II, 7. Tritium and Helium-3 Universität HeidelbergInstitut für Umweltphysik 1 Physics of Aquatic Systems II ­ 7. Tritium and Helium-3 Werner Aeschbach-Hertig Institute of Environmental Physics University of Heidelberg Physics of Aquatic Systems II, 7. Tritium and Helium-3

Aeschbach-Hertig, Werner

411

Deep-Burn Modular Helium Reactor Fuel Development Plan  

SciTech Connect (OSTI)

This document contains the workscope, schedule and cost for the technology development tasks needed to satisfy the fuel and fission product transport Design Data Needs (DDNs) for the Gas Turbine-Modular Helium Reactor (GT-MHR), operating in its role of transmuting transuranic (TRU) nuclides in spent fuel discharged from commercial light-water reactors (LWRs). In its application for transmutation, the GT-MHR is referred to as the Deep-Burn MHR (DB-MHR). This Fuel Development Plan (FDP) describes part of the overall program being undertaken by the U.S. Department of Energy (DOE), utilities, and industry to evaluate the use of the GT-MHR to transmute transuranic nuclides from spent nuclear fuel. The Fuel Development Plan (FDP) includes the work on fuel necessary to support the design and licensing of the DB-MHR. The FDP is organized into ten sections. Section 1 provides a summary of the most important features of the plan, including cost and schedule information. Section 2 describes the DB-MHR concept, the features of its fuel and the plan to develop coated particle fuel for transmutation. Section 3 describes the knowledge base for fabrication of coated particles, the experience with irradiation performance of coated particle fuels, the database for fission product transport in HTGR cores, and describes test data and calculations for the performance of coated particle fuel while in a repository. Section 4 presents the fuel performance requirements in terms of as-manufactured quality and performance of the fuel coatings under irradiation and accident conditions. These requirements are provisional because the design of the DB-MHR is in an early stage. However, the requirements are presented in this preliminary form to guide the initial work on the fuel development. Section 4 also presents limits on the irradiation conditions to which the coated particle fuel can be subjected for the core design. These limits are based on past irradiation experience. Section 5 describes the Design Data Needs to: (1) fabricate the coated particle fuel, (2) predict its performance in the reactor core, (3) predict the radionuclide release rates from the reactor core, and (4) predict the performance of spent fuel in a geological repository. The heart of this fuel development plan is Section 6, which describes the development activities proposed to satisfy the DDNs presented in Section 5. The development scope is divided into Fuel Process Development, Fuel Materials Development, Fission Product Transport, and Spent Fuel Disposal. Section 7 describes the facilities to be used. Generally, this program will utilize existing facilities. While some facilities will need to be modified, there is no requirement for major new facilities. Section 8 states the Quality Assurance requirements that will be applied to the development activities. Section 9 presents detailed costs organized by WBS and spread over time. Section 10 presents a list of the types of deliverables that will be prepared in each of the WBS elements. Four Appendices contain supplementary information on: (a) design data needs, (b) the interface with the separations plant, (c) the detailed development schedule, and (d) the detailed cost estimate.

McEachern, D

2002-12-02T23:59:59.000Z

412

Nucleosynthetic osmium isotope anomalies in acid leachates of the Murchison meteorite  

E-Print Network [OSTI]

We present osmium isotopic results obtained by sequential leaching of the Murchison meteorite, which reveal the existence of very large internal anomalies of nucleosynthetic origin. The Os isotopic anomalies are correlated, and can be explained by the variable contributions of components derived from the s, r and p-processes of nucleosynthesis. Much of the s-process rich osmium is released by relatively mild leaching, suggesting the existence of an easily leachable s-process rich presolar phase, or alternatively, of a chemically resistant r-process rich phase. The s-process composition of Os released by mild leaching diverges slightly from that released by aggressive digestion techniques, perhaps suggesting that the presolar phases attacked by these differing procedures condensed in different stellar environments. The correlation between 190Os and 188Os can be used to constrain the s-process 190Os/188Os ratio to be 1.275 pm 0.043. Such a ratio can be reproduced in a nuclear reaction network for a MACS value for 190Os of ~200 pm 22 mbarn at 30 keV. We also present evidence for extensive internal variation of 184Os abundances in the Murchison meteorite. This suggests that p process rich presolar grains (e.g., supernova condensates) may be present in meteorites in sufficient quantities to influence the Os isotopic compositions of the leachates.

L. Reisberg; N. Dauphas; A. Luguet; D. G. Pearson; R. Gallino; C. Zimmermann

2008-12-15T23:59:59.000Z

413

Blowing Ratio Effects on Film Cooling Effectiveness  

E-Print Network [OSTI]

The research focuses on testing the film cooling effectiveness on a gas turbine blade suction side surface. The test is performed on a five bladed cascade with a blow down facility. Four different blowing ratios are used in this study, which are 0...

Liu, Kuo-Chun

2010-01-14T23:59:59.000Z

414

Helium enhancements in globular cluster stars from Asymptotic Giant Branch star pollution  

E-Print Network [OSTI]

Using a chemical evolution model we investigate the intriguing suggestion that there are populations of stars in some globular clusters (e.g. NGC 2808, omega Centauri) with enhanced levels of helium (Y from about 0.28 to 0.40) compared to the majority of the population that presumably have a primordial helium abundance. We assume that a previous generation of massive low-metallicity Asymptotic Giant Branch (AGB) stars has polluted the cluster gas via a slow stellar wind. We use two independent sets of AGB yields computed from detailed models to follow the evolution of helium, carbon, nitrogen and oxygen in the cluster gas using a Salpeter initial mass function (IMF) and a number of top-heavy IMFs. In no case were we able to fit the observational constraints, Y > 0.30 and C+N+O approximately constant. Depending on the shape of the IMF and the yields, we either obtained Y approximately greater than 0.30 and large increases in C+N+O or Y < 0.30 and C+N+O approximately constant. These results suggest that either AGB stars alone are not responsible for the large helium enrichment or that any dredge-up from this generation of stars was less than predicted by standard models.

Amanda Karakas; Yeshe Fenner; Alison Sills; Simon Campbell; John Lattanzio

2006-05-21T23:59:59.000Z

415

Transient Thermal and Stress Response of A Helium-Cooled Tungsten Plate-Type Divertor  

E-Print Network [OSTI]

.R. Raffray Center for Energy Research University of California, San Diego La Jolla, USA xrwang, which tend to have a negative impact on reliability. The helium-cooled plate- type divertor design maintenance or after the scheduled maintenance because of the different thermal time constants in the front

Raffray, A. René

416

D0 Silicon Upgrade: Gas Helium Storage Tank Pressure Vessel Engineering Note  

SciTech Connect (OSTI)

This is to certify that Beaird Industries, Inc. has done a white metal blast per SSPC-SP5 as required per specifications on the vessel internal. Following the blast, a black light inspection was performed by Beaird Quality Control personnel to assure that all debris, grease, etc. was removed and interior was clean prior to closing vessel for helium test.

Rucinski, Russ; /Fermilab

1996-11-11T23:59:59.000Z

417

Non-local thermodynamic equilibrium effects on isentropic coefficient in argon and helium thermal plasmas  

SciTech Connect (OSTI)

In the present work, two cases of thermal plasma have been considered; the ground state plasma in which all the atoms and ions are assumed to be in the ground state and the excited state plasma in which atoms and ions are distributed over various possible excited states. The variation of Z?, frozen isentropic coefficient and the isentropic coefficient with degree of ionization and non-equilibrium parameter ?(= T{sub e}/T{sub h}) has been investigated for the ground and excited state helium and argon plasmas at pressures 1?atm, 10?atm, and 100?atm in the temperature range from 6000?K to 60?000?K. For a given value of non-equilibrium parameter, the relationship of Z? with degree of ionization does not show any dependence on electronically excited states in helium plasma whereas in case of argon plasma this dependence is not appreciable till degree of ionization approaches 2. The minima of frozen isentropic coefficient shifts toward lower temperature with increase of non-equilibrium parameter for both the helium and argon plasmas. The lowering of non-equilibrium parameter decreases the frozen isentropic coefficient more emphatically in helium plasma at high pressures in comparison to argon plasma. The increase of pressure slightly reduces the ionization range over which isentropic coefficient almost remains constant and it does not affect appreciably the dependence of isentropic coefficient on non-equilibrium parameter.

Sharma, Rohit [Satyam Institute of Engineering and Technology, Amritsar 143107 (India)] [Satyam Institute of Engineering and Technology, Amritsar 143107 (India); Singh, Kuldip [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)] [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

2014-03-15T23:59:59.000Z

418

First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium  

SciTech Connect (OSTI)

While metallic fuels have a long history of reactor use, their fundamental physical and thermodynamic properties are not well understood. Many metallic nuclear fuels are body-centered cubic alloys of uranium that swell under fission conditions, creating fission product gases such as helium, xenon and krypton. In this paper, helium, xenon, and krypton point defects are investigated in the a and ? phases of metallic uranium using first principles calculations. A density functional theory (DFT) framework is utilized with projector augmented-wave (PAW) pseudopotentials. Formation and incorporation energies of He, Xe, and Kr are calculated at various defect positions for the prediction of fission gas behavior in uranium. In most cases, defect energies follow a size effect, with helium incorporation and formation energies being the smallest. The most likely position for the larger Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed. This is the first detailed study of the stability and incorporation of fission gases in uranium.

B. Beeler; B. Good; S. Rashkeev; M. Baskes; M. Okuniewski

2012-06-01T23:59:59.000Z

419

A liquid-helium cooled large-area silicon PIN photodiode x-ray detector  

E-Print Network [OSTI]

An x-ray detector using a liquid-helium cooled large-area silicon PIN photodiode has been developed along with a tailor-made charge sensitive preamplifier whose first-stage JFET has been cooled. The operating temperature of the JFET has been varied separately and optimized. The x- and $\\gamma$-ray energy spectra for an \

Yoshizumi Inoue; Shigetaka Moriyama; Hideyuki Hara; Makoto Minowa; Fumio Shimokoshi

1995-04-27T23:59:59.000Z

420

LBNL-42730 1 Collisional Perturbation of States in Atomic Ytterbium by Helium and Neon  

E-Print Network [OSTI]

LBNL-42730 1 Collisional Perturbation of States in Atomic Ytterbium by Helium and Neon D-photon radiative decays from the 3 P0 state to the ground state #12;LBNL-42730 2 are strictly forbidden by the J=0 transitions for the proposed PNC experiment in a vapor cell. #12;LBNL-42730 3 In a vapor cell experiment

Pines, Alexander

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Feasibility of measuring surface electron spin dynamics by inelastic scattering of metastable helium atoms  

E-Print Network [OSTI]

helium atoms M. El-Batanouny, G. Murthy, and C. R. Willis Department of Physics, Boston University atoms (He*) from surfaces of magnetic insulators to study the dynamical properties of surface electron a metastable He atom and the surface electron spins are determined by a configuration interaction calculation

Kais, Sabre

422

Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense Helium  

E-Print Network [OSTI]

Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense integral Monte Carlo (PIMC) and density func- tional molecular dynamics (DFT-MD), are applied to study hot excitation mecha- nisms that determine their behavior at high temperature. The helium atom has two ionization

Militzer, Burkhard

423

Critical Casimir Effect and Wetting by Helium Mixtures T. Ueno,* S. Balibar, T. Mizusaki,  

E-Print Network [OSTI]

He-4He mixtures against a sapphire window. We have found that this angle is finite and does not tend [1­4]. We found an exception to it by studying helium mixtures in contact with a sapphire window [5 of the fluctuations of superfluidity, i.e., a critical Casimir effect [7­11] in the 4 He-rich film between

Caupin, Frédéric

424

Fusion Engineering and Design 4950 (2000) 709717 Helium-cooled refractory alloys first wall and blanket  

E-Print Network [OSTI]

- tory alloy helium-cooled breeder FW/blanket con- cept developed under the APEX program is presented and blanket evaluation C.P.C. Wong a, *, R.E. Nygren b , C.B. Baxi a , P. Fogarty c , N. Ghoniem e , H. Khater first wall and blanket designs and to recommend and initiate tests to address critical issues. We

Ghoniem, Nasr M.

2000-01-01T23:59:59.000Z

425

Helium adsorption in silica aerogel near the liquid-vapor critical point  

E-Print Network [OSTI]

We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95% and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel's very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales.

Tobias Herman; James Day; John Beamish

2005-05-18T23:59:59.000Z

426

Condensation of helium in aerogels and athermal dynamics of the Random Field Ising Model  

E-Print Network [OSTI]

Condensation of helium in aerogels and athermal dynamics of the Random Field Ising Model Geoffroy J isotherms of 4He in a silica aerogel be- come discontinuous below a critical temperature. We show by the aerogel structure, but to the disorder-driven critical point predicted for the athermal out

Boyer, Edmond

427

Helium Adsorption in Silica Aerogel near the Liquid-Vapor Critical Point  

E-Print Network [OSTI]

We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95 % and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel’s very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales. I.

Tobias Herman; James Day; John Beamish

2008-01-01T23:59:59.000Z

428

Heat capacity of adsorbed Helium-3 at ultra-low temperatures  

E-Print Network [OSTI]

temperatures the surface 3He heat capacity dominates over the heat capacity of the bulk liquid 3HeHeat capacity of adsorbed Helium-3 at ultra-low temperatures J. Elbs, C. Winkelmann, Yu. M. Bunkov Martyrs, BP 166, 38042 Grenoble cedex 9, France We report on direct measurements of the heat capacity

Boyer, Edmond

429

SUPERCONDUCTING PROPERTIES OF ALUMINIUM THIN FILMS AFTER ION IMPLANTATION AT LIQUID HELIUM TEMPERATURES (*)  

E-Print Network [OSTI]

L-271 SUPERCONDUCTING PROPERTIES OF ALUMINIUM THIN FILMS AFTER ION IMPLANTATION AT LIQUID HELIUM concentration near AlH2. It is well-known [1] that the superconducting transition temperature Tc of metals as in the electronic density of states N(O) at the Fermi surface. In the case of weak-coupling superconductors

Boyer, Edmond

430

Creep and rupture behavior of a special grade Hastelloy-X in simulated HTGR helium  

SciTech Connect (OSTI)

Creep and rupture tests were conducted for Hastelloy-XR (a modified version of the conventional Hastelloy alloy X) at 800, 900, and 1000/sup 0/C in simulated high-temperature gas-cooled reactor helium. Creep testing machines with special control of helium chemistry were used. As a result, the scatter of creep-rupture data could be reduced, and the variability of creep-rupture behavior due to manufacturing history could be resolved. Results of metallography and carbon analysis of ruptured specimens showed that the material improved resistance to corrosion in the helium environment, and carbon intrusion during the steady-state creep stage was suppressed to a negligible level. Under refined test conditions combined with the quality controlled material, it was demonstrated that there was little significant difference between helium and air in the creep-rupture results obtained at 800 to 1000/sup 0/C up to about 10/sup 4/h. The importance of maintaining the protective function of the surface oxide film of alloys was stressed in securing reproducibility and predictability of long-time creep performance.

Kurata, Y.; Kondo, T.; Ogawa, Y.

1984-08-01T23:59:59.000Z

431

Gas-Surface Energy Exchange in Collisions of Helium Atoms with Aligned Single-Walled Carbon  

E-Print Network [OSTI]

1 Gas-Surface Energy Exchange in Collisions of Helium Atoms with Aligned Single-Walled Carbon #12;2 ABSTRACT Since gas flows in micro/nano devices are dominated by the interaction of gas molecules accommodation of gas molecules on surfaces. The scattering of gas molecules on quartz surfaces covered with VA

Maruyama, Shigeo

432

Fusion Engineering and Design 82 (2007) 22172225 Integrated thermo-fluid analysis towards helium flow  

E-Print Network [OSTI]

Fusion Engineering and Design 82 (2007) 2217­2225 Integrated thermo-fluid analysis towards helium. Andob, I. Komadab a Fusion Engineering Sciences, Mechanical and Aerospace Eng. Department, University the ITER test blanket module (TBM) warrants the need of extensive computer aided engineering (CAE

Abdou, Mohamed

433

Cavitation in normal liquid helium 3 F. Caupin, P. Roche, S. Marchand and S. Balibar  

E-Print Network [OSTI]

Cavitation in normal liquid helium 3 F. Caupin, P. Roche, S. Marchand and S. Balibar Laboratoire de 24 rue Lhomond 75231 Paris Cedex 05, France We have studied cavitation, i.e. bubble nucleation, cavitation is found to be stochastic, with a cavitation probability 0.5 at a given value of the sound

Caupin, Frédéric

434

A temperature-controlled device for volumetric measurements of Helium adsorption in porous  

E-Print Network [OSTI]

a set-up for studying adsorption of helium in silica aerogels, where the adsorbed amount is easily- dation experiments and a first application to aerogels. This device is well adapted to study hysteresis, such as grafoil, carbon nanotubes, or silica glasses. The case of silica aerogels has attracted attention

Boyer, Edmond

435

Laser Isotope Separation Employing Condensation Repression  

SciTech Connect (OSTI)

Molecular laser isotope separation (MLIS) techniques using condensation repression (CR) harvesting are reviewed and compared with atomic vapor laser isotope separation (AVLIS), gaseous diffusion (DIF), ultracentrifuges (UCF), and electromagnetic separations (EMS). Two different CR-MLIS or CRISLA (Condensation Repression Isotope Separation by Laser Activation) approaches have been under investigation at the University of Missouri (MU), one involving supersonic super-cooled free jets and dimer formation, and the other subsonic cold-wall condensation. Both employ mixtures of an isotopomer (e.g. {sup i}QF{sub 6}) and a carrier gas, operated at low temperatures and pressures. Present theories of VT relaxation, dimerization, and condensation are found to be unsatisfactory to explain/predict experimental CRISLA results. They were replaced by fundamentally new models that allow ab-initio calculation of isotope enrichments and predictions of condensation parameters for laser-excited and non-excited vapors which are in good agreement with experiment. Because of supersonic speeds, throughputs for free-jet CRISLA are a thousand times higher than cold-wall CRISLA schemes, and thus preferred for large-quantity Uranium enrichments. For small-quantity separations of (radioactive) medical isotopes, the simpler coldwall CRISLA method may be adequate.

Eerkens, Jeff W.; Miller, William H.

2004-09-15T23:59:59.000Z

436

ISO/GUM UNCERTAINTIES AND CIAAW (UNCERTAINTY TREATMENT FOR RECOMMENDED ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCES)  

SciTech Connect (OSTI)

The International Organization for Standardization (ISO) has published a Guide to the expression of Uncertainty in Measurement (GUM). The IUPAC Commission on Isotopic Abundance and Atomic Weight (CIAAW) began attaching uncertainty limits to their recommended values about forty years ago. CIAAW's method for determining and assigning uncertainties has evolved over time. We trace this evolution to their present method and their effort to incorporate the basic ISO/GUM procedures into evaluations of these uncertainties. We discuss some dilemma the CIAAW faces in their present method and whether it is consistent with the application of the ISO/GUM rules. We discuss the attempt to incorporate variations in measured isotope ratios, due to natural fractionation, into the ISO/GUM system. We make some observations about the inconsistent treatment in the incorporation of natural variations into recommended data and uncertainties. A recommendation for expressing atomic weight values using a tabulated range of values for various chemical elements is discussed.

HOLDEN,N.E.

2007-07-23T23:59:59.000Z

437

Recent activities for ?-decay half-lives and ?-delayed neutron emission of very neutron-rich isotopes  

SciTech Connect (OSTI)

Beta-delayed neutron (?n) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material ?-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure ?n-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 ?-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 ?-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of ?-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and theoretical models.

Dillmann, Iris [TRIUMF, Vancouver BC, V6T 2A3, Canada and GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Abriola, Daniel [Laboratorio Tandar, Comisión Nacional de Energía Atómica, B1650KINA, San Martín, Buenos Aires (Argentina); Singh, Balraj [Department of Physics and Astronomy, McMaster University, Hamilton ON, L8S 4M1 (Canada)

2014-05-02T23:59:59.000Z

438

Atomic line emission analyzer for hydrogen isotopes  

DOE Patents [OSTI]

Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using a metal hydride.

Kronberg, James W. (108 Independent Blvd., Aiken, SC 29801)

1993-01-01T23:59:59.000Z

439

Atomic line emission analyzer for hydrogen isotopes  

DOE Patents [OSTI]

Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using, a metal hydride.

Kronberg, J.W.

1991-05-08T23:59:59.000Z

440

Apparatus for separating and recovering hydrogen isotopes  

DOE Patents [OSTI]

An apparatus for recovering hydrogen and separating its isotopes. The apparatus includes a housing bearing at least a fluid inlet and a fluid outlet. A baffle is disposed within the housing, attached thereto by a bracket. A hollow conduit is coiled about the baffle, in spaced relation to the baffle and the housing. The coiled conduit is at least partially filled with a hydride. The hydride can be heated to a high temperature and cooled to a low temperature quickly by circulating a heat transfer fluid in the housing. The spacing between the baffle and the housing maximizes the heat exchange rate between the fluid in the housing and the hydride in the conduit. The apparatus can be used to recover hydrogen isotopes (protium, deuterium and tritium) from gaseous mixtures, or to separate hydrogen isotopes from each other.

Heung, Leung K. (Aiken, SC)

1994-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Atomic line emission analyzer for hydrogen isotopes  

DOE Patents [OSTI]

Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using a metal hydride.

Kronberg, J.W.

1993-03-30T23:59:59.000Z

442

J. Phys. I FFance 6 (1996) 771-781 JUNE 1996, PAGE 771 Measurement of the Carbon Isotopic Composition of Methane  

E-Print Network [OSTI]

Composition of Methane Using Helicoidal Laser Eigenstates D. Jacob (~), A. Le Floch (~), F. Bretenaker intracavity measurements of the carbon isotopic composition of methane. The method is based on a double the ~~CH4/~~CH4 composition ratio of methane with an uncertainty of the order of +0.07% for a sample

Paris-Sud XI, Université de

443

Method for production of an isotopically enriched compound  

DOE Patents [OSTI]

A method is presented for producing and isolating an isotopically enriched compound of a desired isotope from a parent radionuclide. The method includes forming, or placing, a precipitate containing a parent radionuclide of the desired daughter isotope in a first reaction zone and allowing sufficient time for the parent to decay into the desired gaseous daughter radioisotope. The method further contemplates collecting the desired daughter isotope as a solid in a second reaction zone through the application of temperatures below the freezing point of the desired isotope to a second reaction zone that is connected to the first reaction zone. Specifically, a method is presented for producing isotopically enriched compounds of xenon, including the radioactive isotope Xe-131m and the stable isotope Xe-131.

Watrous, Matthew G.

2012-12-11T23:59:59.000Z

444

Hydrogen isotope fractionation during lipid biosynthesis by Haloarcula marismortui  

E-Print Network [OSTI]

Hydrogen isotope fractionation during lipid biosynthesis by Haloarcula marismortui Sitindra S studied the controls on the fractionation of hydrogen isotopes during lipid biosynthesis by Haloarcula marismortui, a halophilic archaea, in pure culture experiments by varying organic substrate, the hydrogen

445

The Cosmic Ray Helium and Carbon Nuclei Spectra Measured by Voyager 1 at Low Energies and Earth Based Measurements of these Nuclei up to 200 GeV nuc Concordance at High Energies with a Leaky Box Propagation Model  

E-Print Network [OSTI]

A comparison of the Helium and Carbon interstellar spectra measured at Voyager in the local interstellar medium leads to a different interpretation than a comparison of the Hydrogen to Helium spectra. This is because the He/C ratio is observed to increase rapidly with energy below 40 MeV/nuc in contrast to an almost constant H/He ratio at these low energies. Both the He and C spectra that are observed at Voyager above 40 MeV/nuc and much higher energy spectra from the PAMELA measurements of these two components up to 100 GeV/nuc can be accurately fit to within 10% assuming galactic propagation in a leaky box type of diffusion model in the galaxy with identical source spectra P-2.28 for He and C using a diffusion coefficient P0.50 above 1 GV rigidity. These same exponents also fit the H spectrum from 40 MeV to over 100 GeV. At low energies an excess of He relative to C is observed that would amount to about 20% of the modeled galactic component at 10 MeV/nuc.

Webber, W R

2015-01-01T23:59:59.000Z

446

Laser isotope separation by multiple photon absorption  

DOE Patents [OSTI]

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

1987-04-07T23:59:59.000Z

447

Laser isotope separation by multiple photon absorption  

DOE Patents [OSTI]

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

Robinson, C. Paul (Los Alamos, NM); Rockwood, Stephen D. (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Lyman, John L. (Los Alamos, NM); Aldridge, III, Jack P. (Los Alamos, NM)

1987-01-01T23:59:59.000Z

448

Isotope Research Materials Laboratory | ornl.gov  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFunInfrared LandResponsesIon/SurfacePump-Testing Sign InIsotope ProgramIsotope

449

Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Geothermal...  

Open Energy Info (EERE)

navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Geothermal Area (Phillips, 2004)...

450

Isotopic Analysis At Lassen Volcanic National Park Area (Janik...  

Open Energy Info (EERE)

navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis At Lassen Volcanic National Park Area (Janik & Mclaren, 2010) Exploration Activity...

451

Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Geothermal...  

Open Energy Info (EERE)

navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Geothermal Area (Ito & Tanaka, 1995)...

452

Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Area...  

Open Energy Info (EERE)

navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Area (Ito & Tanaka, 1995) Exploration...

453

Isotopic Analysis At Valles Caldera - Redondo Geothermal Area...  

Open Energy Info (EERE)

navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis At Valles Caldera - Redondo Geothermal Area (Phillips, 2004) Exploration Activity...

454

Isotopic Analysis- Gas At Dixie Valley Geothermal Area (Kennedy...  

Open Energy Info (EERE)

search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Gas At Dixie Valley Geothermal Area (Kennedy & Soest, 2006) Exploration Activity Details...

455

aspect ratio tori: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

efficiency versus a function of mobility ratio and aspect ratio for staggered line-drive waterflood pattern Texas A&M University - TxSpace Summary: ratios on five-spot and...

456

aspect ratio su-8: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

efficiency versus a function of mobility ratio and aspect ratio for staggered line-drive waterflood pattern Texas A&M University - TxSpace Summary: ratios on five-spot and...

457

Discovery of dysprosium, holmium, erbium, thulium, and ytterbium isotopes  

SciTech Connect (OSTI)

Currently, thirty-one dysprosium, thirty-two holmium, thirty-two erbium, thirty-three thulium, and thirty-one ytterbium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Fry, C.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2013-09-15T23:59:59.000Z

458

Discovery of palladium, antimony, tellurium, iodine, and xenon isotopes  

SciTech Connect (OSTI)

Currently, thirty-eight palladium, thirty-eight antimony, thirty-nine tellurium, thirty-eight iodine, and forty xenon isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Kathawa, J.; Fry, C.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2013-01-15T23:59:59.000Z

459

Discovery of the astatine, radon, francium, and radium isotopes  

SciTech Connect (OSTI)

Thirty-nine astatine, thirty-nine radon, thirty-five francium, and thirty-four radium isotopes have so far been observed; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Fry, C.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2013-09-15T23:59:59.000Z

460

Discovery of samarium, europium, gadolinium, and terbium isotopes  

SciTech Connect (OSTI)

Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2013-01-15T23:59:59.000Z

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Discovery of Rubidium, Strontium, Molybdenum, and Rhodium Isotopes  

E-Print Network [OSTI]

Currently, thirty-one rubidium, thirty-five strontium, thirty-five molybdenum and thirty-eight rhodium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Parker, A M

2011-01-01T23:59:59.000Z

462

Discovery of rubidium, strontium, molybdenum, and rhodium isotopes  

SciTech Connect (OSTI)

Currently, 31 rubidium, 35 strontium, 35 molybdenum, and 38 rhodium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Parker, A.M.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2012-07-15T23:59:59.000Z

463

Discovery of Rubidium, Strontium, Molybdenum, and Rhodium Isotopes  

E-Print Network [OSTI]

Currently, thirty-one rubidium, thirty-five strontium, thirty-five molybdenum and thirty-eight rhodium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

A. M. Parker; M. Thoennessen

2011-02-11T23:59:59.000Z

464

Discovery of the actinium, thorium, protactinium, and uranium isotopes  

E-Print Network [OSTI]

Currently, 31 actinium, 31 thorium, 28 protactinium, and 23 uranium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

C. Fry; M. Thoennessen

2012-03-06T23:59:59.000Z

465

Discovery of Chromium, Manganese, Nickel, and Copper Isotopes  

E-Print Network [OSTI]

Twenty-seven chromium, twenty-five manganese, thirty-one nickel and twenty-six copper isotopes have so far been observed and the discovery of these isotopes is discussed. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

K. Garofali; R. Robinson; M. Thoennessen

2010-12-07T23:59:59.000Z

466

Discovery of Cesium, Lanthanum, Praseodymium and Promethium Isotopes  

E-Print Network [OSTI]

Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium, isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E

2011-01-01T23:59:59.000Z

467

Discovery of Cesium, Lanthanum, Praseodymium and Promethium Isotopes  

E-Print Network [OSTI]

Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium, isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

E. May; M. Thoennessen

2011-09-08T23:59:59.000Z

468

Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation  

E-Print Network [OSTI]

The relationship between intermediate watermass response to Atlantic Meridonial Overturning Circulation (AMOC) during two abrupt cooling events of the last deglacial, the Younger Dryas (YD) and Heinrich Event 1 (H1) is controversial and has been...

Franklin, Alyssa L.

2010-07-14T23:59:59.000Z

469

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability  

E-Print Network [OSTI]

Schumann, K. Wendt, B. Bushaw, High-resolution triple-resonancefrom Schumann, et al. is the lack of a sharp resonance atresonance marked with an asterisk is described in the text. (Reproduced from Schumann,

Isselhardt, Brett Hallen

2011-01-01T23:59:59.000Z

470

Investigation of Countercurrent Helium-Air Flows in Air-ingress Accidents for VHTRs  

SciTech Connect (OSTI)

The primary objective of this research is to develop an extensive experimental database for the air- ingress phenomenon for the validation of computational fluid dynamics (CFD) analyses. This research is intended to be a separate-effects experimental study. However, the project team will perform a careful scaling analysis prior to designing a scaled-down test facility in order to closely tie this research with the real application. As a reference design in this study, the team will use the 600 MWth gas turbine modular helium reactor (GT-MHR) developed by General Atomic. In the test matrix of the experiments, researchers will vary the temperature and pressure of the helium— along with break size, location, shape, and orientation—to simulate deferent scenarios and to identify potential mitigation strategies. Under support of the Department of Energy, a high-temperature helium test facility has been designed and is currently being constructed at Ohio State University, primarily for high- temperature compact heat exchanger testing for the VHTR program. Once the facility is in operation (expected April 2009), this study will utilize high-temperature helium up to 900°C and 3 MPa for loss-of-coolant accident (LOCA) depressurization and air-ingress experiments. The project team will first conduct a scaling study and then design an air-ingress test facility. The major parameter to be measured in the experiments is oxygen (or nitrogen) concentration history at various locations following a LOCA scenario. The team will use two measurement techniques: 1) oxygen (or similar type) sensors employed in the flow field, which will introduce some undesirable intrusiveness, disturbing the flow, and 2) a planar laser-induced fluorescence (PLIF) imaging technique, which has no physical intrusiveness to the flow but requires a transparent window or test section that the laser beam can penetrate. The team will construct two test facilities, one for high-temperature helium tests with local sensors and the other for low- temperature helium tests with the PLIF technique. The results from the two instruments will provide a means to cross-calibrate the measurement techniques.

Sun, Xiaodong; Christensen, Richard; Oh, Chang

2013-10-03T23:59:59.000Z

471

air-fuel ratio: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

was performed to investigate the effects of air-fuel ratio, inlet boost pressure, hydrogen rich fuel reformate, and compression ratio on engine knock behavior. For each...

472

Two-Stage Variable Compression Ratio (VCR) System to Increase...  

Broader source: Energy.gov (indexed) [DOE]

Two-Stage Variable Compression Ratio (VCR) System to Increase Efficiency in Gasoline Powertrains Two-Stage Variable Compression Ratio (VCR) System to Increase Efficiency in...

473

A review of stable water isotopeA review of stable water isotope modellingmodelling  

E-Print Network [OSTI]

fractionation · Kinetic fractionation 2. Modelling the stable water isotope cycle · Rayleigh distillation model Institution of Oceanography) Harald SODEMANN (Norwegian Institute for Air Research) Kristof 18Ovapour=-40 18Oocean=0 18Osnow=-3018Orain=-2 Equilibrium fractionationEquilibrium fractionation

Sturm, Christophe "Kristof"

474

Isotopically selective, Doppler-free, saturation spectroscopy of lutetium isotopes via resonance ionization mass spectrometry  

SciTech Connect (OSTI)

A new technique utilizing RIMS to obtain very high resolution atomic spectra with isotopic selectivity has been demonstrated. This technique allows the precise determination of HF splitting constants, limited only by the transition's natural linewidth. In addition, it is also feasible with this technique to accurately determine atomic isotope shifts. The exact determination of HF component line positions provides data for isotopically selective ionization which, in turn, will increase RIMS' dynamic range. Future work includes the incorporation of a /open quotes/vibrating/close quotes/ mirror and the study of rarer isotopes, i.e., /sup 174/Lu, /sup 173/Lu, /sup 172/Lu, /sup 171/Lu, and possibly, /sup 170/Lu. 13 refs., 3 figs.

Fearey, B.L.; Parent, D.C.; Keller, R.A.; Miller, C.M.

1988-01-01T23:59:59.000Z

475

Isotope-labeled immunoassays without radiation waste  

E-Print Network [OSTI]

of California, Davis, CA 95616; and Center for Accelerator Mass Spectrometry, Lawrence Livermore National, such as liquid scintillation counting (LSC) and autoradiography, use the radiation generated in the isotope in areas such as environmental monitoring and food analysis. Accelerator mass spectrometry (AMS) developed

Hammock, Bruce D.

476

Radiation Sources External Beam and Isotopes  

E-Print Network [OSTI]

Radiation Sources External Beam and Isotopes J. Daniel Bourland, PhD Professor Department of Radiation Oncology Departments of Physics and Biomedical Engineering Wake Forest School of Medicine Winston Radiation · Photons: electromagnetic radiation, no mass, E = h · X rays: origins are from atomic energy

477

Review of hydrogen isotope permeability through materials  

SciTech Connect (OSTI)

This report is the first part of a comprehensive summary of the literature on hydrogen isotope permeability through materials that do not readily form hydrides. While we mainly focus on pure metals with low permeabilities because of their importance to tritium containment, we also give data on higher-permeability materials such as iron, nickel, steels, and glasses.

Steward, S.A.

1983-08-15T23:59:59.000Z

478

Trace Element and Isotopic Fluxes/ Subducted Slab  

E-Print Network [OSTI]

3.20.7.2.1 Devolatilization 34 3.20.7.2.2 Boron and lithium isotopes 35 3.20.7.3 Carbon and Nitrogen forearcs. In addi- tion, subduction erosion from the forearc hanging walls can impact geochemical evolut

Bebout, Gray E.

479

5, 547577, 2008 Isotope hydrology of  

E-Print Network [OSTI]

HESSD 5, 547­577, 2008 Isotope hydrology of cave dripwaters L. Fuller et al. Title Page Abstract.hydrol-earth-syst-sci-discuss.net/5/547/2008/ © Author(s) 2008. This work is licensed under a Creative Commons License. Hydrology and Earth System Sciences Discussions Papers published in Hydrology and Earth System Sciences Discussions

Boyer, Edmond

480

Radioactive isotopes in Danish drinking water  

E-Print Network [OSTI]

Radioactive isotopes in Danish drinking water Sven P. Nielsen Risø National Laboratory Working OF INVESTIGATION 11 3 DESCRIPTION OF INVESTIGATION 12 4 RADIOACTIVITY IN DRINKING WATER 13 5 SAMPLING 15 6 27 #12;4 #12;5 Preface This project for investigation of radioactivity in drinking water shall