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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.


1

isotopic ratio | EMSL  

NLE Websites -- All DOE Office Websites (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

ARM - Measurement - Isotope ratio  

NLE Websites -- All DOE Office Websites (Extended Search)

govMeasurementsIsotope ratio govMeasurementsIsotope ratio ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Isotope ratio Ratio of stable isotope concentrations. Categories Atmospheric Carbon, Atmospheric State Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments FLASK : Flask Samplers for Carbon Cycle Gases and Isotopes Field Campaign Instruments FLASK : Flask Samplers for Carbon Cycle Gases and Isotopes Datastreams FLASK : Flask Samplers for Carbon Cycle Gases and Isotopes

3

EMSL - isotopic ratio  

NLE Websites -- All DOE Office Websites (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

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

Open Energy Info (EERE)

Pathways Abstract Fluids from the western margin of the Basin and Range have helium isotope ratios as high as 6-7 Ra, indicating a strong mantle melt influence and consistent...

5

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

Open Energy Info (EERE)

Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and Steamboat Springs Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Helium isotopes in geothermal systems- Iceland, The Geysers, Raft River and Steamboat Springs Details Activities (3) Areas (3) Regions (0) Abstract: Helium isotope ratios have been measured in geothermal fluids from Iceland, The Geysers, Raft River, Steamboat Springs and Hawaii. These ratios have been interpreted in terms of the processes which supply He in distinct isotopic ratios (i.e. magmatic He, ~10 Ra; atmospheric He, R,sub>a; and crustal He, ~0.1 Ra) and in terms of the processes which can alter the isotopic ratio (hydrologic mixing, U-Th series alpha production and weathering release of crustal He, magma aging and

6

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

Open Energy Info (EERE)

And Local Trends In Helium Isotopes, Basin And Range Province, And Local Trends In Helium Isotopes, Basin And Range Province, Western North America- Evidence For Deep Permeable Pathways Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Regional And Local Trends In Helium Isotopes, Basin And Range Province, Western North America- Evidence For Deep Permeable Pathways Details Activities (1) Areas (1) Regions (0) Abstract: Fluids from the western margin of the Basin and Range have helium isotope ratios as high as ~6-7 Ra, indicating a strong mantle melt influence and consistent with recent and current volcanic activity. Moving away from these areas, helium isotope ratios decrease rapidly to 'background' values of around 0.6 Ra, and then gradually decrease toward the east to low values of ~0.1 Ra at the eastern margin of the Basin and

7

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

Open Energy Info (EERE)

Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal System Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Helium Isotope Perspective On The Dixie Valley, Nevada, Hydrothermal System Details Activities (3) Areas (1) Regions (0) Abstract: Fluids from springs, fumaroles, and wells throughout Dixie Valley, NV were analyzed for noble gas abundances and isotopic compositions. The helium isotopic compositions of fluids produced from the Dixie Valley geothermal field range from 0.70 to 0.76 Ra, are among the highest values in the valley, and indicate that similar to 7.5% of the total helium is derived from the mantle. A lack of recent volcanics or other potential sources requires flow of mantle-derived helium up along the

8

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

Open Energy Info (EERE)

gas abundances and isotopic compositions. The helium isotopic compositions of fluids produced from the Dixie Valley geothermal field range from 0.70 to 0.76 Ra, are among the...

9

Helium Isotopes In Geothermal And Volcanic Gases Of The Western United  

Open Energy Info (EERE)

Helium Isotopes In Geothermal And Volcanic Gases Of The Western United Helium Isotopes In Geothermal And Volcanic Gases Of The Western United States, I, Regional Variability And Magmatic Origin Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Helium Isotopes In Geothermal And Volcanic Gases Of The Western United States, I, Regional Variability And Magmatic Origin Details Activities (1) Areas (1) Regions (0) Abstract: Helium isotope ratios in gases of thirty hot springs and geothermal wells and of five natural gas wells in the western United States show no relationship to regional conductive heat flow, but do show a correlation with magma-based thermal activity and reservoir fluid temperature (or total convective heat discharge). Gases from high-T (> 200°C) reservoirs have 3He/4He > 2 _ the atmospheric value, with high He

10

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...

11

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs,  

Open Energy Info (EERE)

Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon- Evidence For Renewed Volcanic Activity Or A Long Term Steady State System(Question) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon- Evidence For Renewed Volcanic Activity Or A Long Term Steady State System(Question) Details Activities (1) Areas (1) Regions (0) Abstract: Here 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 central Oregon. The Separation Creek area which is several miles due west of the volcano is the locus of

12

Helium generation rates in isotopically tailored Fe-Cr-Ni alloys irradiated in FFTF/MOTA  

SciTech Connect

Three Fe-Cr-Ni alloys have been doped with 0.4% {sup 59}Ni for side-by-side irradiations of doped and undoped materials in order to determine the effects of fusion-relevant levels of helium production on microstructural development and mechanical properties. The alloys were irradiated in three successive cycles of the Materials Open Test Assembly (MOTA) located in the Fast Flux Test Facility (FFTF). Following irradiation, helium levels were measured by isotope dilution mass spectrometry. The highest level of helium achieved in doped alloys was 172 appm at 9.1 dpa for a helium(appm)-to-dpa ratio of 18.9. The overall pattern of predicted helium generation rates in doped and undoped alloys is in good agreement with the helium measurements.

Greenwood, L.R.; Garner, F.A. [Pacific Northwest Lab., Richland, WA (United States); Oliver, B.M. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.

1991-11-01T23:59:59.000Z

13

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

Open Energy Info (EERE)

Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope Trends Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Flow Of Mantle Fluids Through The Ductile Lower Crust- Helium Isotope Trends Details Activities (5) Areas (5) Regions (0) Abstract: Heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust. Minimum He-3/He-4 ratios in surface fluids from the northern Basin and Range Province, western North America, increase systematically from low crustal values in the east to high mantle values in the west, a regional trend that correlates with the rates of active crustal deformation. The highest ratios occur where the extension and shear strain rates are greatest. The

14

Development of High Expansion Ratio Helium Turbo Expander  

Science Journals Connector (OSTI)

The authors developed a high expansion ratio radial inflow turbine for a helium liquefier of 100 L/h capacity for use with a 70 MW superconductive generator. The following results were obtained from this devel...

N. Ino; A. Machida; K. Ttsugawa; Y. Arai; M. Matsuki…

1991-01-01T23:59:59.000Z

15

Isotope ratio determination in boron analysis  

Science Journals Connector (OSTI)

Traditionally, boron (B) isotope ratios have been determined using thermal ionization...+, Cs+, or O-...for analyte ionization. TIMS can be used in negative or positive ion modes with high sensitivity and precisi...

Ram N. Sah; Patrick H. Brown

1998-12-01T23:59:59.000Z

16

Development of a Micropyrolyzer for Enhanced Isotope Ratio Measurement...  

NLE Websites -- All DOE Office Websites (Extended Search)

Micropyrolyzer for Enhanced Isotope Ratio Measurement. Development of a Micropyrolyzer for Enhanced Isotope Ratio Measurement. Abstract: This paper presents design, fabrication and...

17

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

SciTech Connect

An extensive study of helium isotopes in fluids collectedfrom surface springs, fumaroles and wells across the northern Basin andRange Province reveals a systematic trend of decreasing 3He/4He ratiosfrom west to east. The western margin of the Basin and Range ischaracterized by mantle-like ratios (6-8 Ra) associated with active orrecently active crustal magma systems (e.g., Coso, Long Valley,Steamboat, and the Cascade volcanic complex). Moving towards the east,the ratios decline systematically to a background value of ~;0.1 Ra. Theregional trend is consistent with extensive mantle melting concentratedalong the western margin and is coincident with an east-to-west increasein the magnitude of northwest strain. The increase in shear strainenhances crustal permeability resulting in high vertical fluid flow ratesthat preserve the high helium isotope ratios at the surface. Superimposedon the regional trend are "helium spikes," local anomalies in the heliumisotope composition. These "spikes" reflect either local zones of mantlemelting or locally enhanced crustal permeability. In the case of theDixie Valley hydrothermal system, it appears to be a combination ofboth.

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

2006-05-01T23:59:59.000Z

18

Final Report on Isotope Ratio Techniques for Light Water Reactors  

SciTech Connect

The Isotope Ratio Method (IRM) is a technique for estimating the energy or plutonium production in a fission reactor by measuring isotope ratios in non-fuel reactor components. The isotope ratios in these components can then be directly related to the cumulative energy production with standard reactor modeling methods.

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

2009-07-01T23:59:59.000Z

19

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

SciTech Connect

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

20

GUM Analysis for TIMS and SIMS Isotopic Ratios in Graphite  

SciTech Connect

This report describes GUM calculations for TIMS and SIMS isotopic ratio measurements of reactor graphite samples. These isotopic ratios are used to estimate reactor burn-up, and currently consist of various ratios of U, Pu, and Boron impurities in the graphite samples. The GUM calculation is a propagation of error methodology that assigns uncertainties (in the form of standard error and confidence bound) to the final estimates.

Heasler, Patrick G.; Gerlach, David C.; Cliff, John B.; Petersen, Steven L.

2007-04-01T23:59:59.000Z

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.


21

Oxygen And Carbon Isotope Ratios Of Hydrothermal Minerals From Yellowstone  

Open Energy Info (EERE)

Oxygen And Carbon Isotope Ratios Of Hydrothermal Minerals From Yellowstone Oxygen And Carbon Isotope Ratios Of Hydrothermal Minerals From Yellowstone Drill Cores Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Oxygen And Carbon Isotope Ratios Of Hydrothermal Minerals From Yellowstone Drill Cores Details Activities (3) Areas (1) Regions (0) Abstract: Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199°C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The Δ18O values of the thirty-two analyzed silica samples (quartz, chalcedony, α-cristobalite, and β-cristobalite) range from -7.5 to +2.8‰. About one

22

Helium and oxygen isotope analyses of hydrothermal fluids from the East Pacific Rise between 17°S and 19°S  

Science Journals Connector (OSTI)

?Hydrothermal vent fields south of the Garret Fracture zone were sampled for the isotope composition of helium and oxygen ([18O]H2O/[16OH2O). The helium isotopes end-member (3He?/?4He=8.3×R ...

P. Jean-Baptiste; A. Dapoigny; M. Stievenard; J. L. Charlou…

1997-08-01T23:59:59.000Z

23

Upper-mantle dynamics revealed by helium isotope variations along the southeast Indian ridge  

Science Journals Connector (OSTI)

... present helium isotope data for MORB glasses recovered along ?5,800?km of the southeast Indian ridge, and develop an approach to quantitatively relate spatial variations in geochemical and geophysical ... quantitatively relate spatial variations in geochemical and geophysical parameters at the Earth's surface. A point-to- ...

D. W. Graham; J. E. Lupton; F. J. Spera; D. M. Christie

2001-02-08T23:59:59.000Z

24

LITERATURE SURVEY ON ISOTOPIC ABUNDANCE RATIO MEASUREMENTS - 2001-2005  

SciTech Connect

Along with my usual weekly review of the published literature for new nuclear data, I also search for new candidates for best measurements of isotopic abundances from a single source. Most of the published articles, that I previously had found in the Research Library at the Brookhaven Lab, have already been sent to the members of the Atomic Weights Commission, by either Michael Berglund or Thomas Walczyk. In the last few days, I checked the published literature for any other articles in the areas of natural variations in isotopic abundance ratios, measurements of isotopic abundance ratios on samples of extra-terrestrial material and isotopic abundance ratio measurements performed using ICPMS instruments. Hopefully this information will be of interest to members of the Commission, the sub-committee on isotopic abundance measurements (SIAM), members of the former sub-committee on natural isotopic fractionation (SNIF), the sub-committee on extra-terrestrial isotope ratios (SETIR), the RTCE Task Group and the Guidelines Task Group, who are dealing with ICPMS and TIMS comparisons. In the following report, I categorize the publications in one of four areas. Measurements performed using either positive or negative ions with Thermal Ionization Mass Spectrometer, TIMS, instruments; measurements performed on Inductively Coupled Plasma Mass Spectrometer, ICPMS, instruments; measurements of natural variations of the isotopic abundance ratios; and finally measurements on extra-terrestrial samples with instrumentation of either type. There is overlap in these areas. I selected out variations and ET results first and then categorized the rest of the papers by TIMS and ICPMS.

HOLDEN, N.E.

2005-08-13T23:59:59.000Z

25

Limits on the Boron Isotopic Ratio in HD 76932  

E-Print Network (OSTI)

Data in the 2090 A B region of HD 76932 have been obtained at high S/N using the HST GHRS echelle at a resolution of 90,000. This wavelength region has been previously identified as a likely candidate for observing the B11/B10 isotopic splitting. The observations do not match a calculated line profile extremely well at any abundance for any isotopic ratio. If the B abundance previously determined from observations at 2500 A is assumed, the calculated line profile is too weak, indicating a possible blending line. Assuming that the absorption at 2090 A is entirely due to boron, the best-fit total B abundance is higher than but consistent with that obtained at 2500 A, and the best-fit isotopic ratio (B11/B10) is in the range ~10:1 to ~4:1. If the absorption is not entirely due to B and there is an unknown blend, the best-fit isotopic ratio may be closer to 1:1. Future observations of a similar metal-poor star known to have unusually low B should allow us to distinguish between these two possibilities. The constraints that can be placed on the isotopic ratio based on comparisons with similar observations of HD 102870 and HD 61421 (Procyon) are also discussed.

L. M. Rebull; D. K. Duncan; S. Johansson; J. Thorburn; B. Fields

1998-07-13T23:59:59.000Z

26

Limits on the Boron Isotopic Ratio in HD 76932  

E-Print Network (OSTI)

Data in the 2090 A B region of HD 76932 have been obtained at high S/N using the HST GHRS echelle at a resolution of 90,000. This wavelength region has been previously identified as a likely candidate for observing the B11/B10 isotopic splitting. The observations do not match a calculated line profile extremely well at any abundance for any isotopic ratio. If the B abundance previously determined from observations at 2500 A is assumed, the calculated line profile is too weak, indicating a possible blending line. Assuming that the absorption at 2090 A is entirely due to boron, the best-fit total B abundance is higher than but consistent with that obtained at 2500 A, and the best-fit isotopic ratio (B11/B10) is in the range ~10:1 to ~4:1. If the absorption is not entirely due to B and there is an unknown blend, the best-fit isotopic ratio may be closer to 1:1. Future observations of a similar metal-poor star known to have unusually low B should allow us to distinguish between these two possibilities. The constr...

Rebull, L M; Johansson, S; Thorburn, J; Fields, B

1998-01-01T23:59:59.000Z

27

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

28

Long-term changes in solar wind elemental and isotopic ratios: A compairosn of two lunar ilmenites of different antiquities  

SciTech Connect

An ilmenite separate from lunar regolith breccia 79035, a sample presumed to have been exposed to solar wind more than 2 Ga ago, was analyzed for noble gas and nitrogen elemental and isotopic abundances by stepwise oxidation and pyrolysis. The gases appear to be distributed between two distinct reservoirs in the ilmenite, defined by release patterns and isotopic considerations. One of the reservoirs, near grain surfaces, yields elemental ratios that for the most part are solar while the other, sited at greater depths within grains, has severely fractionated elemental abundances and generally heavier isotopic ratios as well. Xenon provides an exception to the solar abundance pattern in the near-surface reservoir, being enhanced by about a factor of 2 relative to the expected value. A comparison of the 79035 separate with a previously analyzed ilmenite from soil 71501, which received its solar wind exposure much more recently, indicates that the two-fold xenon enhancement occurs in the fractionated reservoir as well as the solar one, and that it may therefore be attributable to a change in the solar wind elemental abundances. Other differences between the two ilmenites occur in helium and neon isotopic ratios and in He/Ar elemental ratios. Since mineralogical influences on retentivities of the gases in the two samples should be the same, and possible contributions of non-solar wind components to one ilmenite in preference to the other can generally be eliminated or accounted for, all of these differences may reflect changes in the solar wind over time.

Becker, R.H.; Pepin, R.O. (Univ. of Minneapolis, MN (USA))

1989-05-01T23:59:59.000Z

29

Isotopic Analysis At Northern Basin & Range Region (Kennedy ...  

Open Energy Info (EERE)

useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced...

30

Isotopic Analysis At Nw Basin & Range Region (Kennedy & Van Soest...  

Open Energy Info (EERE)

useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced...

31

Isotopic Analysis At Walker-Lane Transitional Zone Region (Kennedy...  

Open Energy Info (EERE)

useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced...

32

Determination of boron isotope ratios in geological materials by inductively coupled plasma mass spectrometry  

Science Journals Connector (OSTI)

Determination of boron isotope ratios in geological materials by inductively coupled plasma mass spectrometry ... Isotope dilution analysis using flow injection inductively coupled plasma mass spectrometry was applied to determine low boron contents in iron and steel samples. ...

D. Conrad Gregoire

1987-10-01T23:59:59.000Z

33

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

34

Mixing Ratios of CO, CO2, CH4, and Isotope Ratios of Associated 13C, 18O,  

NLE Websites -- All DOE Office Websites (Extended Search)

Air Samples, Niwot Ridge, Colorado Air Samples, Niwot Ridge, Colorado Mixing Ratios of CO, CO2, CH4, and Isotope Ratios of Associated 13C, 18O, and 2H in Air Samples from Niwot Ridge, Colorado, and Montaña de Oro, California, USA (January 2004) image Abstract graphics Graphics data Data Investigator Stanley C. Tyler Department of Earth System Science University of California Irvine, CA DOI: 10.3334/CDIAC/atg.db1022 Description and Methods Air samples from Niwot Ridge, Colorado (41°N, 105°W) and Montaña de Oro, CA (35°N, 121°W) have been collected at approximately semi-monthly to monthly intervals since the mid 1990s. The beginning dates for each gas and isotope analyzed are as follows: GASLAB Flask Sampling Network Data Available (April 2003) Gas or isotope Niwot Ridge Montaña de Oro

35

Stable Carbon Isotope Ratios of Phenolic Compounds in Secondary Particulate Organic Matter Formed by Photooxidation of Toluene  

E-Print Network (OSTI)

Compound-specific stable carbon isotope ratios for phenolic compounds in secondary particulate organic matter (POM) formed by photooxidation of toluene were studied. Secondary POM generated by photooxidation of toluene using a continuous-flow reactor and an 8 cubic meter indoor smog chamber was collected, and then extracted with acetonitrile. Eight phenolic compounds were identified in the extracts by a gas chromatograph coupled with a mass spectrometer, and their compound-specific stable carbon isotope ratios were determined by a gas chromatograph coupled with a combustion furnace followed by an isotope ratio mass spectrometer. The majority of the products, including methylnitrophenols and methylnitrocatechols, were isotopically depleted by 5 to 6 permil compared to the initial isotope ratio for toluene, whereas the isotope ratio for 4_nitrophenol remained the same as the initial isotope ratio for toluene. Based on the reaction mechanisms postulated in literature, stable carbon isotope ratios of these produc...

Irei, Satoshi; Huang, Lin; Auld, Janeen; Collin, Fabrice; Hastie, Donald

2014-01-01T23:59:59.000Z

36

Determination of boron isotope ratios by Zeeman effect background correction-graphite furnace atomic absorption spectrometry  

Science Journals Connector (OSTI)

A new method for the determination of isotopic ratio of boron using Zeeman effect background correction-graphite furnace atomic absorption spectrometry with conventional atomizer and natural-boron hollow cathode source is described. The isotope-shift Zeeman effect at 208.9 nm is utilized for isotopic ratio determination. At a given concentration of total boron, the net absorbance decreases linearly with increasing 10B/11B ratio. The absorbances are recorded at the field strength of 1.0 T. The isotope ratios measured by the proposed method were in good agreement with the results obtained by inductively coupled plasma-quadruple mass spectrometry or thermal ionization mass spectrometry. The present method is fairly fast and less expensive compared to the above techniques and is quite suitable for plant environments.

S. Thangavel; S.V. Rao; K. Dash; J. Arunachalam

2006-01-01T23:59:59.000Z

37

Bayesian Integration of Isotope Ratios for Geographic Sourcing of Castor Beans  

SciTech Connect

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

38

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

Open Energy Info (EERE)

Kennedy at the University of California at Berkeley, CA. Isotopic ratios of helium and CO2 determined for gases sampled at LVEW were 3.66 Ra (3He4He ratio) and -6.4 %o (delta...

39

Improving boron isotope ratio measurement precision with quadrupole inductively coupled plasma-mass spectrometry  

Science Journals Connector (OSTI)

A method was developed to improve the precision of inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) for the determination of boron isotope ratios (11B/10B) in various environmental materials including seawater. This approach is based on the common analyte internal standardization (CAIS) chemometric algorithm. The sample solution obtained after digestion is spiked with lithium, and both 7Li/6Li and 11B/10B values are measured using long-counting periods (20 min). The CAIS algorithm corrects the measured 11B/10B values for (a) statistical fluctuations resulting from short-term noise; (b) drift in 11B-to-10B ratio as a result of long-term deviation in instrumental parameters likely to occur during long counting times; (c) change in 11B-to-10B ratio caused by variation in matrix elements concentrations; and (d) drift in mass bias correction factor. Comparing boron isotopic ratios in seawater measured by conventional and the new isotope ratio methods validates the procedure. A synthetic isotopic mixture of boron SRM 951 and enriched 10B SRM 952 also was examined. The CAIS method provided a measured boron isotopic ratio precision of 0.05% R.S.D. while eliminating 5.1% matrix concentration error and 0.25% instrumental drift error.

Assad Al-Ammar; Eva Reitznerová; Ramon M. Barnes

2000-01-01T23:59:59.000Z

40

Monthly Atmospheric 13C/12C Isotopic Ratios for 11 SIO Stations  

NLE Websites -- All DOE Office Websites (Extended Search)

Isotopes » 13C/12C Isotopic Ratios for Isotopes » 13C/12C Isotopic Ratios for 11 SIO Stations Monthly Atmospheric 13C/12C Isotopic Ratios for 11 SIO Stations graphics Graphics data Data Investigators R.F. Keeling, S.C. Piper, A.F. Bollenbacher, and S.J. Walker Scripps CO2 Program http://scrippsco2.ucsd.edu/ University of California, La Jolla, California 92093-0244, U.S.A. Period of Record 1977-2008 Methods Stable isotopic measurements for atmospheric 13C/12C and 18O/16O at global sampling sites were initiated by Dr. C.D. Keeling and co-workers at Scripps Institution of Oceanography (SIO) in 1977. These isotopic measurements complement the continuing global atmospheric and oceanic CO2 measurements initiated by Keeling in 1957. This work is currently being continued under the direction of R.F. Keeling, who also runs a parallel program at SIO to

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

Positive correlation between Li and Mg isotope ratios in the river waters of the Mackenzie Basin challenges the interpretation of apparent isotopic  

E-Print Network (OSTI)

geochemistry magnesium Mg isotopes lithium Li isotopes chemical weathering a b s t r a c t During chemical expressed as d26 Mg) show in excess of one per mil variability. Part of this variability is attributed covariation between lithium (7 Li/6 Li, expressed as d7 Li) and Mg isotope ratios in the river waters

Paytan, Adina

42

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

SciTech Connect

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

43

Isotopic Ratio Measurements of Atmospheric Carbon Dioxide Using a 4.3 ?m Pulsed Quantum Cascade Laser  

Science Journals Connector (OSTI)

We report CO2 isotopic ratios (13C, 18O) measured in air using a pulsed quantum cascade laser at 2310 cm-1. Performance is...

Nelson, David; McManus, John B; Zahniser, Mark S; Tuzson, Bela; Emmenegger, Lukas

44

Boron isotope ratios in commercial produce and boron-10 foliar and hydroponic enriched plants  

Science Journals Connector (OSTI)

Boron isotope ratios in commercial produce and boron-10 foliar and hydroponic enriched plants ... The Absorption and Tissue Distribution of Selenium from High-Selenium Broccoli Are Different from Selenium from Sodium Selenite, Sodium Selenate, and Selenomethionine As Determined in Selenium-Deficient Rats ...

Richard A. Vanderpool; Phyllis E. Johnson

1992-03-01T23:59:59.000Z

45

A rapid and precise method for sampling and determining the oxygen isotope ratio of atmospheric  

E-Print Network (OSTI)

2002; Accepted 1 March 2002 A quantitative method for cryogenically sampling atmospheric water vapor recovery of a vaporized, known, 18 O water standard to 0.2% precision. Copyright # 2002 John Wiley & Sons differentially affect both the concentration and isotope ratio of atmospheric water vapor.5,8,9 Measurements

Ehleringer, Jim

46

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.

47

Barium even-to-odd isotope abundance ratios in thick disk and thin disk stars  

E-Print Network (OSTI)

We present the Ba even-to-odd isotope abundance ratios in 25 cool dwarf stars with the metallicity [Fe/H] ranged between 0.25 and --1.35. Our method takes advantage of the hyperfine structure (HFS) affecting the \\ion{Ba}{ii} resonance line of the odd isotopes. The fractional abundance of the odd isotopes of Ba is derived from a requirement that Ba abundances from the resonance line $\\lambda 4554$ and subordinate lines $\\lambda 5853$ and $\\lambda 6496$ must be equal. The results are based on NLTE line formation and analysis of high resolution (R $\\sim60000$) high signal-to-noise (S/N $\\ge 200$) observed spectra. We find that the fraction of the odd isotopes of Ba grows toward the lower Ba abundance (or metallicity) and the mean value in the thick disk stars equals 33 $\\pm$ 4%. This indicates the higher contribution of the $r-$process to barium in the thick disk stars compared to the solar system matter. The obtained fraction increases with the [Eu/Ba] abundance ratio growth in agreement with expectations. A significant fraction of the \\emph{even} isotopes of Ba found in old Galactic stars (the thick disk stars), $\\sim67$%, is in contrast to the prediction of the "classical" model of the $s-$process and favors the value predicted by the "stellar" models of Arlandini et al. (1999) and Travaglio et al. (1999).

L. Mashonkina; G. Zhao

2006-04-10T23:59:59.000Z

48

Estimation of boron isotope ratios using high resolution continuum source atomic absorption spectrometry  

Science Journals Connector (OSTI)

In the production of 10B enriched steels, the production–recycling process needs to be closely monitored for inadvertent mix-up of materials with different B isotope levels. A quick and simple method for the estimation of boron isotope ratios in high alloyed steels using high resolution continuum source flame AAS (HR-CS-FAAS) was developed. On the 208.9 nm B line the wavelength of the peak absorption of 10B and 11B differs by 2.5 pm. The wavelength of the peak absorption of boron was determined by fitting a Gauss function through spectra simultaneously recorded by HR-CS-FAAS. It was shown that a linear correlation between the wavelength of the peak absorption and the isotope ratio exists and that this correlation is independent of the total boron concentration. Internal spectroscopic standards were used to compensate for monochromator drift and monochromator resolution changes. Accuracy and precision of the analyzed samples were thereby increased by a factor of up to 1.3. Three steel reference materials and one boric acid CRM, each certified for the boron isotope ratio were used to validate the procedure.

Helmar Wiltsche; Karl Prattes; Michael Zischka; Günter Knapp

2009-01-01T23:59:59.000Z

49

Mg isotope ratios in giant stars of the globular clusters M 13 and M 71  

E-Print Network (OSTI)

We present Mg isotope ratios in 4 red giants of the globular cluster M 13 and 1 red giant of the globular cluster M 71 based on spectra obtained with HDS on the Subaru Telescope. We confirm earlier results by Shetrone that for M 13, the ratio varies from (25+26)Mg/24Mg = 1 in stars with the highest Al abundance to (25+26)Mg/24Mg = 0.2 in stars with the lowest Al abundance. However, we separate the contributions of all three isotopes and find a spread in the ratio 24Mg:25Mg:26Mg with values ranging from 48:13:39 to 78:11:11. As in NGC 6752, we find a positive correlation between 26Mg and Al, an anticorrelation between 24Mg and Al, and no correlation between 25Mg and Al. In M 71, our one star has a ratio 70:13:17. For both clusters, the lowest ratios of 25Mg/24Mg and 26Mg/24Mg exceed those observed in field stars at the same metallicity, a result also found in NGC 6752. The contribution of 25Mg to the total Mg abundance is constant within a given cluster and between clusters with 25Mg/(24+25+26)Mg = 0.13. For M 13 and NGC 6752, the ranges of the Mg isotope ratios are similar and both clusters show the same correlations between Al and Mg isotopes suggesting that the same process is responsible for the abundance variations in these clusters. While existing models fail to reproduce all the observed abundances, we continue to favor the scenario in which two generations of AGB stars produce the observed abundances. A first generation of metal-poor AGB stars pollutes the entire cluster and is responsible for the large ratios of 25Mg/24Mg and 26Mg/24Mg observed in cluster stars with compositions identical to field stars at the same metallicity. Differing degrees of pollution by a second generation of AGB stars of the same metallicity as the cluster provides the star-to-star scatter in Mg isotope ratios.

David Yong; Wako Aoki; David L. Lambert

2005-10-19T23:59:59.000Z

50

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

SciTech Connect

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

51

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

DOE Data Explorer (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

52

Concentrations and activity ratios of uranium isotopes in groundwater from Donana National Park, South of Spain  

SciTech Connect

The levels and distribution of natural radionuclides in groundwaters from the unconfined Almonte-Marismas aquifer, upon which Donana National Park is located, have been analysed. Most sampled points were multiple piezometers trying to study the vertical distribution of the hydrogeochemical characteristics in the aquifer. Temperature, pH, electrical conductivity, dissolved oxygen and redox potential were determined in the field. A large number of parameters, physico-chemical properties, major and minor ions, trace elements and natural radionuclides (U-isotopes, Th-isotopes, Ra-isotopes and {sup 210}Po), were also analysed. In the southern zone, where aeolian sands crop out, water composition is of the sodium chloride type, and the lower U-isotopes concentrations have been obtained. As water circulates through the aquifer, bicarbonate and calcium concentrations increase slightly, and higher radionuclides concentrations were measured. Finally, we have demonstrated that {sup 234}U/{sup 238}U activity ratios can be used as markers of the type of groundwater and bedrock, as it has been the case for old waters with marine origin confined by a marsh in the south-east part of aquifer.

Bolivar, J. P.; Olias, M.; Gonzalez-Garcia, F. [Department of Applied Physics, University of Huelva, Campus de El Carmen, 21071-Huelva (Spain); Garcia-Tenorio, R. [Department of Applied Physics II, University of Sevilla, ETSA Arquitectura, 41012-Sevilla (Spain)

2008-08-07T23:59:59.000Z

53

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

54

Uranium isotopic ratio determination in urine using flow-injection ICP-MS: a tool for emergency monitoring  

Science Journals Connector (OSTI)

......Biological monitoring of uranium exposure in south central...determination of low uranium isotopes ratios in small...Carpenter D. O. Depleted uranium contamination by inhalation...implication for human health assessment. Sci. Total......

Maria Luiza D. P. Godoy; Ligia M. Q. C. Julião; José Marcus Godoy

2009-02-01T23:59:59.000Z

55

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

SciTech Connect

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

56

Isotopic Analysis At U.S. West Region (Welhan, Et Al., 1988) | Open Energy  

Open Energy Info (EERE)

U.S. West Region (Welhan, Et Al., 1988) U.S. West Region (Welhan, Et Al., 1988) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At U.S. West Region (Welhan, Et Al., 1988) Exploration Activity Details Location U.S. West Region Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful DOE-funding Unknown Notes Helium isotope ratios are not correlated with regional heat flow in the western United States. High helium isotope ratios (R/RA > 2) occur only in magma-based geothermal systems. A direct correlation exists between geothermal reservoir temperature and helium isotope ratio of the fluids, suggesting that both heat and helium in a geothermal reservoir are derived from a shallow magmatic source. The rapid lateral decrease in 3He away from

57

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

SciTech Connect

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

58

Abundances and Isotope Ratios in the Magellanic Clouds: The Star Forming Environment of N113  

E-Print Network (OSTI)

With the goal of deriving the physical and chemical conditions of star forming regions in the Large Magellanic Cloud (LMC), a spectral line survey of the prominent star forming region N113 is presented. The observations cover parts of the frequency range from 85 GHz to 357 GHz and include 63 molecular transitions from a total of 16 species, among them spectra of rare isotopologues. Maps of selected molecular lines as well as the 1.2 mm continuum distribution are also presented. Molecular abundances in the core of the complex are found to be consistent with a photon dominated region (PDR) that is nitrogen deficient, with the potential exception of N2H+. Densities range from 5x10^3 cm-3 for CO to almost 10^6 for CS and HCN, indicating that only the densest regions provide sufficient shielding even for some of the most common species. An ortho- to para-H_2CO ratio of ~3 hints at H_2CO formation in a warm (>=40 K) environment. Isotope ratios are 12C/13C ~ 49+-5, 16O/18O ~ 2000+-250, 18O/17O ~ 1.7+-0.2 and 32S/34S ~ 15. Agreement with data from other star forming clouds shows that the gas is well mixed in the LMC . The isotope ratios do not only differ from those seen in the Galaxy. They also do not form a continuation of the trends observed with decreasing metallicity from the inner to the outer Galaxy. This implies that the outer Galaxy, is not providing a transition zone between the inner Galaxy and the metal poor environment of the Magellanic Clouds. A part of this discrepancy is likely caused by differences in the age of the stellar populations in the outer Galaxy and the LMC.

M. Wang; Y. -N. Chin; C. Henkel; J. B. Whiteoak; M. Cunningham

2008-09-10T23:59:59.000Z

59

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

60

Accurate and Precise Determination of Boron Isotopic Ratios at Low Concentration by Positive Thermal Ionization Mass Spectrometry Using Static Multicollection of Cs2BO2+ Ions  

Science Journals Connector (OSTI)

Accurate and Precise Determination of Boron Isotopic Ratios at Low Concentration by Positive Thermal Ionization Mass Spectrometry Using Static Multicollection of Cs2BO2+ Ions ... (1) A relatively large mass difference (10%) between the two isotopes and high volatility results in significant boron isotopic variation from ?70‰(2) to +75‰(3) in natural materials; thus, boron isotopes have numerous applications in geochemistry, isotope hydrology, oceanography, environmental sciences, cosmology, and nuclear technology. ... (2) Our method provided better long-term stability of NIST 951 standard compared to “Zoom Quad” mode when more than two isotopes were determined in addition to boron isotope. ...

Mao-yong He; Ying-kai Xiao; Zhang-dong Jin; Yun-qi Ma; Jun Xiao; Yan-ling Zhang; Chong-guang Luo; Fei Zhang

2013-05-29T23:59:59.000Z

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.


61

Oxygen isotope ratio measurements in CO2 by means of a continuous-wave quantum cascade laser at 4.3 ?m  

Science Journals Connector (OSTI)

A mid-infrared laser spectrometer was developed for simultaneous high-precision 18O/16O and 17O/16O isotope ratio measurements in carbon...

Castrillo, Antonio; Casa, Giovanni; Gianfrani, Livio

2007-01-01T23:59:59.000Z

62

Isotope 18O/16O ratio measurements of water vapor by use of the 950-nm wavelength region with cavity ring-down and photoacoustic spectroscopic techniques  

Science Journals Connector (OSTI)

Two optical methods, cavity ring-down spectroscopy and photoacoustic spectroscopy, are applied to the measurement of the isotope ratio 18O/16O in water-vapor...

Samura, Ken; Hashimoto, Satoshi; Kawasaki, Masahiro; Hayashida, Akira; Kagi, Eriko; Ishiwata, Takashi; Matsumi, Yutaka

2002-01-01T23:59:59.000Z

63

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

SciTech Connect

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

64

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

SciTech Connect

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

65

Geographic determination of coffee beans using multi-element analysis and isotope ratios of boron and strontium  

Science Journals Connector (OSTI)

Abstract This study aims to evaluate the feasibility of using chemical and isotopic compositions of coffee beans to identify their geographic origins. Twenty-one Coffea arabica beans collected from 14 countries in 3 major coffee-producing regions, Africa, America and Asia, were analysed for multi-element of B, Rb, Sr, Ba, Fe, Mn and Zn, as well as isotopic compositions of B and Sr. Our results demonstrate that the geographic origin of coffee beans could be classified based on concentrations of Rb, Sr and Ba. However, the isotope ratios of B and Sr provide more sensitive information for the growth localities. Combined with literature data, this study indicates that B and Sr isotopes are excellent indicators of the origin of coffee beans.

Hou-Chun Liu; Chen-Feng You; Chiou-Yun Chen; Yu-Ching Liu; Ming-Tsung Chung

2014-01-01T23:59:59.000Z

66

Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation  

E-Print Network (OSTI)

DEGLACIAL NEODYMIUM ISOTOPIC RATIOS IN THE FLORIDA STRAITS AND THE RESPONSE OF INTERMEDIATE WATERS TO REDUCED MERIDIONAL OVERTURNING CIRCULATION Major: Geology April 2010 Submitted to the Office of Undergraduate... AND THE RESPONSE OF INTERMEDIATE WATERS TO REDUCED MERIDIONAL OVERTURNING CIRCULATION Approved by: Research Advisor: Franco Marcantonio Associate Dean for Undergraduate Research: Robert C. Webb Major: Geology April 2010 Submitted...

Franklin, Alyssa L.

2010-07-14T23:59:59.000Z

67

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

68

Probing isotopic ratios at z = 0.89: molecular line absorption in front of the quasar PKS 1830-211  

E-Print Network (OSTI)

With the Plateau de Bure interferometer, we have measured the C, N, O and S isotopic abundance ratios in the arm of a spiral galaxy with a redshift of 0.89. The galaxy is seen face-on according to HST images. Its bulge intercepts the line of sight to the radio-loud quasar PKS 1830-211, giving rise at mm wavelengths to two Einstein images located each behind a spiral arm. The arms appear in absorption in the lines of several molecules, giving the opportunity to study the chemical composition of a galaxy only a few Gyr old. The isotopic ratios in this spiral galaxy differ markedly from those observed in the Milky Way. The $^{17}$O/$^{18}$O and $^{14}$N/$^{15}$N ratios are low, as one would expect from an object too young to let low mass stars play a major role in the regeneration of the gas.

Sebastien Muller; Michel Guelin; Michael Dumke; Robert Lucas; Francoise Combes

2006-08-04T23:59:59.000Z

69

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

70

The 16OH/18OH and OD/OH isotope ratios in comet C/2002 T7 (LINEAR)  

E-Print Network (OSTI)

The 16OH/18OH and OD/OH isotope ratios are measured in the Oort-Cloud comet C/2002 T7 (LINEAR) through ground-based observations of the OH ultraviolet bands at 3063 A (0,0) and 3121 A (1,1) secured with the Very Large Telescope (VLT) feeding the Ultraviolet-Visual Echelle Spectrograph (UVES). From the 16OH/18OH ratio, we find 16O/18O = 425 +/- 55, equal within the uncertainties to the terrestrial value and to the ratio measured in other comets, although marginally smaller. We also estimate OD/OH from which we derive D/H = 2.5 +/- 0.7 10-4 in water. This value is compatible with the water D/H ratios evaluated in other comets and marginally higher than the terrestrial value.

D. Hutsemekers; J. Manfroid; E. Jehin; J. -M. Zucconi; C. Arpigny

2008-09-25T23:59:59.000Z

71

Theoretical investigation of projectile angular dependence of the ratio of double to single ionization of helium by fast proton impact  

E-Print Network (OSTI)

) Chair of Advisory Committee: Dr. John F. Reading DifFerential cross sections for single and double ionization, and ratios of double to single ionization, of He by proton projectile at 0. 3, I, 3 and 6 MeV/amu are inves- tigated. For the single... Differential cross sections for singly ionizing electrons whose energies I'&iilge from ?, ki to ?, ' k;, from He by proton projectile at 300 KeV& amu. . 15 2 2 Differeutial &ross sections I' or singly ionizin electrons whose energies range froin ?, ki...

Fang, Xushan

2012-06-07T23:59:59.000Z

72

Oxygen- and Hydrogen-Isotopic Ratios of Water in Precipitation: Beyond Paleothermometry  

Science Journals Connector (OSTI)

...of water can be used to test Earth-system models focused on the hydrologic cycle...of the hydrologic cycles of Earth-system models that include appropriate isotopic...testing hydrologic cycles in Earth system models; this direction will be most...

Richard B. Alley; Kurt M. Cuffey

73

A one-group parametric sensitivity analysis for the graphite isotope ratio method and other related techniques using ORIGEN 2.2  

E-Print Network (OSTI)

Several methods have been developed previously for estimating cumulative energy production and plutonium production from graphite-moderated reactors. The Graphite Isotope Ratio Method (GIRM) is one well-known technique. This method is based...

Chesson, Kristin Elaine

2009-06-02T23:59:59.000Z

74

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

SciTech Connect

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

75

A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples  

SciTech Connect

A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios of small biological isolates with spatial resolutions {approx}50 {mu}m.

Kelly, James F.; Sams, Robert L.; Blake, Thomas A.; Newburn, Matthew K.; Moran, James J.; Alexander, M. L.; Kreuzer, Helen W.

2012-02-06T23:59:59.000Z

76

Isotopic Analysis-Fluid At Steamboat Springs Geothermal Area (1982) | Open  

Open Energy Info (EERE)

Isotopic Analysis-Fluid At Steamboat Springs Geothermal Area (1982) Isotopic Analysis-Fluid At Steamboat Springs Geothermal Area (1982) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis-Fluid At Steamboat Springs Geothermal Area (1982) Exploration Activity Details Location Steamboat Springs Geothermal Area Exploration Technique Isotopic Analysis-Fluid Activity Date 1982 Usefulness not indicated DOE-funding Unknown Notes Helium isotope ratios have been measured in geothermal fluids. These ratios have been interpreted in terms of the processes which supply He in distinct isotopic ratios (i.e. magmatic He, ~10 Ra; atmospheric He, Ra; and crustal He, ~0.1 Ra) and in terms of the processes which can alter the isotopic ratio (hydrologic mixing, U-Th series alpha production and weathering

77

Nitrogen isotope ratios in sedimentary organic matter track changes in nutrient utilization and inventories  

SciTech Connect

The isotopic composition of sedimentary nitrogen is a direct proxy for the extent of nutrient draw-down in surface waters and for changes in nutrient inventories in past oceans. In the eastern Pacific, surface sediment [delta][sup 15]N is lowest along the equator where surface ocean nitrate concentration ([NO[sub 3]-]) is highest; [delta][sup 15]N progressively increases and [NO[sub 3]-] decreases to the north and south. This pattern is produced by the formation and sedimentation of [sup 14]N-enriched organic material (OM) where phytoplankton growth is not limited by NO[sub 3]-, and the formation of isotopically heavy OM where NO[sub 3]- is progressively drawn down. Downcore records from the Panama Basin and Northwest Africa show a 1 to 2% decrease in [delta][sup 15]N from the Holocene (0 to 12 ky BP) to the last glacial maximum (LGM, 12 to 24 ky BP) due to a decrease in relative NO[sub 3]-utilization (biological uptake relative to supply) and an increase in OM burial rate due to an increase in productivity. Off northwestern Mexico and in the Arabian Sea, extensive denitrification in intermediate waters causes [delta][sup 15]N-enrichment of the source NO[sub 3]-, so that modern sediment [delta][sup 15]N is high. During the LGM, however, [delta][sup 15]N decreased because productivity and the extent of denitrification both fell. Hence, the global ocean NO[sub 3]- inventory increased, possibly leading to higher global productivity which could have been responsible for the lower glacial atmospheric pCO[sub 2].

Calvert, S.E.; Pedersen, T.F. (Univ. of British Columbia, Vancouver (Canada))

1996-01-01T23:59:59.000Z

78

Nitrogen isotope ratios in sedimentary organic matter track changes in nutrient utilization and inventories  

SciTech Connect

The isotopic composition of sedimentary nitrogen is a direct proxy for the extent of nutrient draw-down in surface waters and for changes in nutrient inventories in past oceans. In the eastern Pacific, surface sediment {delta}{sup 15}N is lowest along the equator where surface ocean nitrate concentration ([NO{sub 3}-]) is highest; {delta}{sup 15}N progressively increases and [NO{sub 3}-] decreases to the north and south. This pattern is produced by the formation and sedimentation of {sup 14}N-enriched organic material (OM) where phytoplankton growth is not limited by NO{sub 3}-, and the formation of isotopically heavy OM where NO{sub 3}- is progressively drawn down. Downcore records from the Panama Basin and Northwest Africa show a 1 to 2% decrease in {delta}{sup 15}N from the Holocene (0 to 12 ky BP) to the last glacial maximum (LGM, 12 to 24 ky BP) due to a decrease in relative NO{sub 3}-utilization (biological uptake relative to supply) and an increase in OM burial rate due to an increase in productivity. Off northwestern Mexico and in the Arabian Sea, extensive denitrification in intermediate waters causes {delta}{sup 15}N-enrichment of the source NO{sub 3}-, so that modern sediment {delta}{sup 15}N is high. During the LGM, however, {delta}{sup 15}N decreased because productivity and the extent of denitrification both fell. Hence, the global ocean NO{sub 3}- inventory increased, possibly leading to higher global productivity which could have been responsible for the lower glacial atmospheric pCO{sub 2}.

Calvert, S.E.; Pedersen, T.F. [Univ. of British Columbia, Vancouver (Canada)

1996-12-31T23:59:59.000Z

79

The use of post detonation analysis of stable isotope ratios to determine the type and production process of the explosive involved  

SciTech Connect

The detonation of a series of explosives was performed in a controlled manner to collect the resulting, solid residue or {open_quotes}soot.{close_quotes} This residue was examined to determine the ratios of the stable carbon, hydrogen, and nitrogen isotopes. The goal of the experiment was to determine if these ratios could be used to indicate, from the post detonation residues, the type and origin of the detonated explosive. The ratios of the stated stable isotopes in the undetonated explosive were also determined. Despite some reservations in the quality of the data resulting from contamination by nonexplosive components, certain trends can be discerned. (1) Carbon isotopes allow aromatic explosives to be distinguished from nonaromatic explosives. This trend seems to carry through the detonation so that the distinction might be made after the fact. (2) The amination process for TATB can be detected through the hydrogen and, to some extent, the nitrogen isotope ratios. Unfortunately, the data are not sufficiently good to determine if this differential carries through the detonation. (3) The relative magnitude and sign of the nitrogen isotope ratio seems to carry through the detonation: some exchange with atmospheric nitrogen is probable. Even though this set of experiments must also be viewed as preliminary, there is a definite indication that certain qualitative characteristics of explosives can be detected after the detonation. This {open_quotes}signature{close_quotes} could have application to both intelligence and counter terrorism.

McGuire, R.R.; Velsko, C.A.; Lee, C.G.; Raber, E.

1993-03-05T23:59:59.000Z

80

Generalized gamma-ray isotopic analysis software and re-evaluation of the two important 242Pu branching ratios  

SciTech Connect

The goal of the generalized gamma-ray analysis software is to provide precise and accurate isotopic analyses of samples that do not have a standard experimental geometry. This analysis tool will analyze gamma-ray data from all types of measurement scenarios with little or no interaction from the user. This tool also provides complete transparency regarding the gamma-ray peaks and branching intensities used in the analysis with the capability for the user to modify this information. They are currently at the data collected phase of building a validated spectral library. One of the by-products in this data collection phase is enabling them to reevaluate the two important branching ratios in {sup 242}Pu. These branching ratios are required for very high burn-up plutonium fuels. The preliminary analysis shows that the energy of the states are 103.5 keV and 158.82 keV, the branching ratio are 1.36E-5 (9%) and 3.37E-6(7%), respectively. More accurate measurements and analysis are currently being carried out.

Wang, T; Raschke, K; Roberts, K; Dougan, A

2009-07-06T23:59:59.000Z

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.


81

Isotopic Analysis At Central Nevada Seismic Zone Region (Kennedy & Van  

Open Energy Info (EERE)

Isotopic Analysis At Central Nevada Seismic Zone Region (Kennedy & Van Isotopic Analysis At Central Nevada Seismic Zone Region (Kennedy & Van Soest, 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Central Nevada Seismic Zone Region (Kennedy & Van Soest, 2007) Exploration Activity Details Location Central Nevada Seismic Zone Geothermal Region Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced permeability and that mantle fluids can penetrate the ductile lithosphere, even in regions where there is no substantial magmatism. Superimposed on the regional trend are local,

82

Application of multivariate curve resolution-alternating least squares for the determination of boron isotope ratios by inductively coupled plasma-optical emission spectrometry  

Science Journals Connector (OSTI)

Abstract Multivariate curve resolution-alternating least squares (MCR-ALS) was applied to atomic emission data obtained from inductively coupled plasma-optical emission spectrometry analysis of boron for the quantification of 10B/11B ratios. The determination of isotopic composition of boron is based on the isotopic shift of 10B and 11B in the emission line of 208.957 nm. After recording of the emission spectra in the range of 208.940–208.970 nm, evaluation of isotopic composition of boron containing samples was performed with MCR-ALS algorithm. MCR-ALS was able to resolve the emission spectra of 10B and 11B mixtures. The performance of the proposed methods was tested by determination of 10B/11B ratios in synthetic mixtures and also water samples.

Ehsan Zolfonoun; Seyed Javad Ahmadi

2013-01-01T23:59:59.000Z

83

Isotopic Analysis- Gas At Chena Geothermal Area (Kolker, Et Al...  

Open Energy Info (EERE)

Laboratory sampling and analysis of He isotopes from Chena Hot Springs. Notes Helium isotope measurements indicate there is no magmatic or mantle input at the Chena Geothermal...

84

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

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

85

Isotopic Analysis-Fluid At Geysers Geothermal Area (1982) | Open Energy  

Open Energy Info (EERE)

82) 82) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis-Fluid At Geysers Geothermal Area (1982) Exploration Activity Details Location Geysers Geothermal Area Exploration Technique Isotopic Analysis-Fluid Activity Date 1982 Usefulness not indicated DOE-funding Unknown Notes Helium isotope ratios have been measured in geothermal fluids. These ratios have been interpreted in terms of the processes which supply He in distinct isotopic ratios (i.e. magmatic He, ~10 Ra; atmospheric He, Ra; and crustal He, ~0.1 Ra) and in terms of the processes which can alter the isotopic ratio (hydrologic mixing, U-Th series alpha production and weathering release of crustal He, magma aging and tritiugenic addition of 3He). Raft

86

HELIOS: A helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR  

SciTech Connect

Radial profiles of electron temperature and density are measured at high spatial ({approx}1 mm) and temporal ( Greater-Than-Or-Slanted-Equal-To 10 {mu}s) resolution using a thermal supersonic helium jet. A highly accurate detection system is applied to well-developed collisional-radiative model codes to produce the profiles. Agreement between this measurement and an edge Thomson scattering measurement is found to be within the error bars ( Less-Than-Or-Equivalent-To 20%). The diagnostic is being used to give profiles near the ion cyclotron resonant heating antenna on TEXTOR to better understand RF coupling to the core.

Unterberg, E. A.; Fehling, D. H.; Klepper, C. C.; Hillis, D. L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169 (United States); Schmitz, O. [Insitut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, D-52428 Juelich (Germany); Stoschus, H. [Insitut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, D-52428 Juelich (Germany); Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831-0117 (United States); Munoz-Burgos, J. M. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831-0117 (United States); Van Wassenhove, G. [LPP-ERM/KMS, Association EURATOM-Belgian State, B-1000 Brussels (Belgium)

2012-10-15T23:59:59.000Z

87

Precise and accurate determination of boron isotope ratios by multiple collector ICP-MS: origin of boron in the Ngawha geothermal system, New Zealand  

Science Journals Connector (OSTI)

A new technique has been developed for the measurement of boron isotope ratios in fluids using a double focusing multiple collector inductively coupled plasma (ICP) mass spectrometer. Sample introduction using a direct injection nebuliser was found to eliminate memory problems that are common where spray chambers are involved. The 4–9% mass bias can be corrected for by bracketing sample measurements with standards. As matrices were found to affect the mass bias all samples must be purified and that sample and standard solutions must be similar. A new purification technique was developed that yields adequately purified samples. Using this technique, it is possible to make rapid measurements (4 min) from samples containing 250 ng B to a precision of ±0.2‰. This analytical technique has been applied to the Ngawha geothermal system in New Zealand in an attempt to determine the source of B in geothermal fluids where the B concentrations can exceed 100 mmol/l. The ?11B values range between ?3.1‰ and ?3.9‰ indicating that no seawater sources are involved and that the elevated B concentrations can only be accounted for by low water/rock ratios with the B being derived from basement greywacke/argillite. The similarity of B isotope ratios for hydrothermal fluids that have been diluted and cooled with groundwaters indicates that isotope fractionation due to adsorption is unlikely to occur in cool geothermal fluids (<40 °C).

J.K. Aggarwal; D. Sheppard; K. Mezger; E. Pernicka

2003-01-01T23:59:59.000Z

88

Stable Isotope Discrimination by Consumers in a Tropical Mangrove Food Web: How Important Are Variations in C/N Ratio?  

Science Journals Connector (OSTI)

Stable isotopes are widely used as tracers in food webs and as indicators of the trophic levels (TL) of consumers. The objectives of this study were to verify a possible ecosystem-wide increase in the relative...

Ralf Schwamborn; Tommaso Giarrizzo

2014-08-01T23:59:59.000Z

89

Isotopic Analysis-Fluid At Raft River Geothermal Area (1982) | Open Energy  

Open Energy Info (EERE)

Analysis-Fluid At Raft River Geothermal Area Analysis-Fluid At Raft River Geothermal Area (1982) Exploration Activity Details Location Raft River Geothermal Area Exploration Technique Isotopic Analysis- Fluid Activity Date 1982 Usefulness not useful DOE-funding Unknown Exploration Basis Determine which reservoir model best matches the isotope data. Notes 1) Chemical and light-stable isotope data are presented for water samples from the Raft River geothermal area and nearby. On the basis of chemical character, as defined by a trilinear plot of per cent milliequivalents, and light-stable isotope data, the waters in the geothermal area can be divided into waters that have and have not mixed with cold water. 2) Helium isotope ratios have been measured in geothermal fluids. These ratios have been interpreted in terms of the processes which supply He in distinct isotopic

90

High-precision optical measurements of 13C/12C isotope ratios in organic compounds at natural abundance  

Science Journals Connector (OSTI)

High-precision...compounds at natural abundance...catalytic combustor, and an isotopic...challenge to the high-cost and...carbon dioxide gas, using...temperature and pressure from which...of carbon gases . Spectrochim...2008 ) High precision...compounds at natural abundance...catalytic combustor, and...

Richard N. Zare; Douglas S. Kuramoto; Christa Haase; Sze M. Tan; Eric R. Crosson; Nabil M. R. Saad

2009-01-01T23:59:59.000Z

91

Phosphate oxygen isotope ratios as a tracer for sources and cycling of phosphate in North San Francisco Bay, California  

E-Print Network (OSTI)

and restoration of these ecosystems. [3] Phosphorus (P) is a required element for life and consequently, its is low relative to input and phosphate is not heavily cycled in the ecosystem, the oxygen isotopic.1029/2005JG000079. 1. Introduction [2] Urban and agricultural runoff are major sources of phosphate to aquatic

Paytan, Adina

92

Isotopic Analysis At Walker-Lane Transitional Zone Region (Kennedy & Van  

Open Energy Info (EERE)

Kennedy & Van Kennedy & Van Soest, 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Walker-Lane Transitional Zone Region (Kennedy & Van Soest, 2007) Exploration Activity Details Location Walker-Lane Transition Zone Geothermal Region Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced permeability and that mantle fluids can penetrate the ductile lithosphere, even in regions where there is no substantial magmatism. Superimposed on the regional trend are local, high 3He/4He anomalies indicating hidden magmatic activity and/or deep

93

unstable isotope  

Science Journals Connector (OSTI)

unstable isotope, radioisotope ? unstabiles Isotop n, nichtstabiles Isotop, radioaktives Isotop, Radioisotop

2014-08-01T23:59:59.000Z

94

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.

95

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

96

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

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

97

Using 3He/4He isotope ratios to identify the source of deep reservoir contributions to shallow fluids and soil gas  

Science Journals Connector (OSTI)

One strategy to counteract rising atmospheric CO2 levels is the capture and subsequent geological storage of anthropogenic CO2. Legislation will require the monitoring and early identification of any leakage to the near surface from the storage site. Owing to their low concentrations and unreactive nature, noble gases are well established as key tracers of crustal fluid systems (Ballentine et al., 2002). The 3He/4He and noble gas content of soil gases and groundwater may provide the opportunity to detect, identify and quantify a weak, deep-sourced signal that contributes to a larger, near-surface biological signal. We present 3He/4He, Ne, Ar, Kr, and Xe data from near-surface soil gases, two of which exhibit hydrocarbon microseepage from deeper oil reservoirs from the Teapot Dome oil field, Wyoming, USA. We also present a noble gas characterisation of the oil reservoirs beneath the seepages. A helium excess (4Heexcess up to 37.7 ppm) relative to air concentrations (4Heair = 5.24 ppm) is found in soil gases at both microseepage sites. Error propagation demonstrates that it is possible to unambiguously resolve the 3He/4He of the deep helium source and allows us to explore the limits of this technique. At one seep the resolved deep 3He/4He = 0.055 ± 0.009Ra (where Ra = 1.40 × 10? 6) is indistinguishable from the range observed in the subsurface hydrocarbon system of 0.046 to 0.109Ra. Notably the soil gas 4He/CH4 = 1.8 × 10? 3 at this microseepage site compares similarly with the lower subsurface source 4He/CH4 = 1.4 to 3.4 × 10? 4 and demonstrates the conservative nature of helium as a tracer. We show that the sensitivity of helium as a deep fluid tracer should be increased by up to two orders of magnitude in groundwater compared to soil gases studied here due to the low solubility of helium in water. Groundwater rather than soil gas should be the priority in any monitoring strategy that plans to use helium as an early indicator of deep fluid microseepage.

Sarah J. Mackintosh; Chris J. Ballentine

2012-01-01T23:59:59.000Z

98

Helium Ion Microscope | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

other characterization capabilities. User Portal Name: Helium Ion Microscope Instrument ID: 34104 Availability: 10 hours a day, 5 days a week Facility: Quiet Wing Quick Specs...

99

Double photoionization of helium with synchrotron x-rays: Proceedings  

SciTech Connect

This report contains papers on the following topics: Overview and comparison of photoionization with charged particle impact; The ratio of double to single ionization of helium: the relationship of photon and bare charged particle impact ionization; Double photoionization of helium at high energies; Compton scattering of photons from electrons bound in light elements; Electron ionization and the Compton effect in double ionization of helium; Elimination of two atomic electrons by a single energy photon; Double photoionization of helium at intermediate energies; Double Photoionization: Gauge Dependence, Coulomb Explosion; Single and Double Ionization by high energy photon impact; The effect of Compton Scattering on the double to single ionization ratio in helium; and Double ionization of He by photoionization and Compton scattering. These papers have been cataloged separately for the database.

Not Available

1994-01-01T23:59:59.000Z

100

Kinetic Isotope Effects in Cycloreversion of Rhenium (V) Diolates  

Science Journals Connector (OSTI)

The isotope effects were all calculated from these ratios according to the equation25 (F = extent of reaction; R = isotopic ratio vs reference at extent of reaction F; R0 = initial isotopic ratio vs reference). ... The magnitudes of small kinetic isotope effects (KIEs) are amplified in the isotopic compn. of starting materials recovered from reactions taken to high conversions. ... The magnitudes of small kinetic isotope effects (KIEs) are amplified in the isotopic compn. of starting materials recovered from reactions taken to high conversions. ...

Kevin P. Gable; Fedor A. Zhuravlev

2002-03-21T23:59:59.000Z

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

Isotopic Analysis At Cascades Region (Kennedy & Van Soest, 2007) | Open  

Open Energy Info (EERE)

Analysis At Cascades Region (Kennedy & Van Soest, 2007) Analysis At Cascades Region (Kennedy & Van Soest, 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis-Fluid At Cascades Region (Kennedy & Van Soest, 2007) Exploration Activity Details Location Cascades Geothermal Region Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced permeability and that mantle fluids can penetrate the ductile lithosphere, even in regions where there is no substantial magmatism. Superimposed on the regional trend are local, high 3He/4He anomalies indicating hidden magmatic activity and/or deep

102

Isotopic Analysis At Nw Basin & Range Region (Kennedy & Van Soest, 2007) |  

Open Energy Info (EERE)

Nw Basin & Range Region (Kennedy & Van Soest, 2007) Nw Basin & Range Region (Kennedy & Van Soest, 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Nw Basin & Range Region (Kennedy & Van Soest, 2007) Exploration Activity Details Location Northwest Basin and Range Geothermal Region Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced permeability and that mantle fluids can penetrate the ductile lithosphere, even in regions where there is no substantial magmatism. Superimposed on the regional trend are local, high 3He/4He anomalies indicating hidden magmatic activity and/or deep

103

Isotopic Analysis At Northern Basin & Range Region (Kennedy & Van Soest,  

Open Energy Info (EERE)

Northern Basin & Range Region (Kennedy & Van Soest, Northern Basin & Range Region (Kennedy & Van Soest, 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Northern Basin & Range Region (Kennedy & Van Soest, 2007) Exploration Activity Details Location Northern Basin and Range Geothermal Region Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful regional reconnaissance DOE-funding Unknown Notes The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced permeability and that mantle fluids can penetrate the ductile lithosphere, even in regions where there is no substantial magmatism. Superimposed on the regional trend are local, high 3He/4He anomalies indicating hidden magmatic activity and/or deep

104

Electrochemical Isotope Effect and Lithium Isotope Separation  

Science Journals Connector (OSTI)

In a series of papers Kavner et al. (2005, 2008)(2, 3) derive an equation predicting isotopic fractionation due to an electrochemical isotope effect (?EIE), defined by the ratio of electron transfer rates (k?/k) for isotopically substituted species (prime for heavy isotopologues): where v, ?G, kB, T, m, ?eq, QP/QR, z, e, and ? denote collision frequency, activation free energy, Boltzmann’s constant, temperature, mass in motion, equilibrium fractionation factor, partition function ratio of abundant isotopologues of product (P) and reactant (R), number of electrons, charge of electron, and Marcus reorganization energy, respectively. ... fractional isotope evolution of Zn isotopes during an electroplating process which stepwise removes most of the Zn from the aq. ...

Jay R. Black; Grant Umeda; Bruce Dunn; William F. McDonough; Abby Kavner

2009-07-06T23:59:59.000Z

105

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

106

lead-isotope age  

Science Journals Connector (OSTI)

lead-isotope age, lead-lead age [An age in years calculated from the ratio of lead-207 to lead-206, a by-product of the uranium-thorium-lead age method] ? Blei-Isotopen-Alter n

2014-08-01T23:59:59.000Z

107

The Helium Question  

Science Journals Connector (OSTI)

...1976 1977 1978 (%) Kansas 55.34 51.58 48...U.S. naturai gas production, except from Alaska...Cryogenic transmis-sion of electricity, already technically...are so inefficient or site-dependent. Superconductivity...to supplement its own production with heli-um purchased...

Earl Cook

1979-12-07T23:59:59.000Z

108

Isotopic Analysis- Fluid | Open Energy Information  

Open Energy Info (EERE)

Isotopic Analysis- Fluid Isotopic Analysis- Fluid Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Isotopic Analysis- Fluid Details Activities (61) Areas (32) Regions (6) NEPA(0) Exploration Technique Information Exploration Group: Lab Analysis Techniques Exploration Sub Group: Fluid Lab Analysis Parent Exploration Technique: Fluid Lab Analysis Information Provided by Technique Lithology: Water rock interaction Stratigraphic/Structural: Hydrological: Origin of hydrothermal fluids; Mixing of hydrothermal fluids Thermal: Isotopic ratios can be used to characterize and locate subsurface thermal anomalies. Dictionary.png Isotopic Analysis- Fluid: Isotopes are atoms of the same element that have different numbers of neutrons. An isotopic analysis looks at a particular isotopic element(s) in

109

Isotopic Analysis At Dixie Valley Geothermal Field Area (Laney, 2005) |  

Open Energy Info (EERE)

Isotopic Analysis At Dixie Valley Geothermal Field Area (Laney, 2005) Isotopic Analysis At Dixie Valley Geothermal Field Area (Laney, 2005) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Dixie Valley Geothermal Field Area (Laney, 2005) Exploration Activity Details Location Dixie Valley Geothermal Field Area Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness not indicated DOE-funding Unknown Notes Gas and Isotopes Geochemistry, Kennedy, van Soest and Shevenell. During FY04, we concentrated on two primary projects. The first was a detailed study of helium isotope systematics throughout Dixie Valley and the inter-relationship between the Dixie Valley geothermal reservoir and local hydrology. The second is the construction of a helium isotope "map" of the

110

Creep properties of Hastelloy-X in impure helium environments  

SciTech Connect

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

111

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

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

112

Time-resolved distributions of bulk parameters, diacids, ketoacids and ?-dicarbonyls and stable carbon and nitrogen isotope ratios of TC and TN in tropical Indian aerosols: Influence of land/sea breeze and secondary processes  

Science Journals Connector (OSTI)

Abstract To better understand the photochemical production and diurnal distributions of organic and inorganic aerosols in the tropical coastal Indian atmosphere, the aerosol (TSP) samples were collected every 3 h during 30–31 January, 14–15 February and 28–29 May 2007 from Chennai and studied for total carbon (TC) and nitrogen (TN) and their stable isotope ratios (?13CTC and ?15NTN), carbonaceous components, inorganic ions, diacids, ketoacids and ?-dicarbonyls. Time-resolved distributions of bulk parameters, inorganic ions, and diacids and related compounds, except for few species, did not show any clear diurnal trend but showed peaks at 6–9 h during all the study periods, except for the peak at 15–18 h on 28 May. SO42?, C2 ? C6 diacids, ketoacids and ?-dicarbonyls in February and on 29 May showed a diurnal trend. ?13CTC and ?15NTN stayed relatively constant during the study periods but showed 13C depletion (in January) and 15 N enrichment when TC and TN peaked. Based on these results together with air mass trajectories, we found that the diurnal distributions of Chennai aerosols are mainly influenced by land/sea breeze and the aged (photochemically processed) air masses, although in situ photochemical production and nighttime chemistry of secondary aerosol species, particularly C2–C4 diacids and SO42?, are significant. The characteristics of seasonal variations of carbonaceous components, and diacids and related compounds and comparisons of ?13CTC and ?15NTN of Chennai aerosols with the isotopic signatures of the point sources inferred that biofuel/biomass burning in South and Southeast Asia are the major sources of aerosols (TSP).

Chandra Mouli Pavuluri; Kimitaka Kawamura; T. Swaminathan

2015-01-01T23:59:59.000Z

113

Effective Helium Burning Rates and the Production of the Neutrino Nuclei  

E-Print Network (OSTI)

Effective values for the key helium burning reaction rates, triple-alpha and 12C(alpha,gamma)16O, are obtained by adjusting their strengths so as to obtain the best match with the solar abundance pattern of isotopes uniquely or predominately made in core collapse supernovae. These effective rates are then used to determine the production of the neutrino isotopes. The use of effective rates considerably reduces the uncertainties in the production factors arising from uncertainties in the helium burning rates, and improves our ability to use the production of 11B to constrain the neutrino emission from supernovae.

Sam M. Austin; Christopher West; Alexander Heger

2014-02-26T23:59:59.000Z

114

Effective Helium Burning Rates and the Production of the Neutrino Nuclei  

E-Print Network (OSTI)

Effective values for the key helium burning reaction rates, triple-alpha and 12C(alpha,gamma)16O, are obtained by adjusting their strengths so as to obtain the best match with the solar abundance pattern of isotopes uniquely or predominately made in core collapse supernovae. These effective rates are then used to determine the production of the neutrino isotopes. The use of effective rates considerably reduces the uncertainties in the production factors arising from uncertainties in the helium burning rates, and improves our ability to use the production of 11B to constrain the neutrino emission from supernovae.

Austin, Sam M; Heger, Alexander

2014-01-01T23:59:59.000Z

115

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

116

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

117

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

118

Radioactive Kr Isotopes  

Science Journals Connector (OSTI)

A radioactive isotope of 1.1-hour half-life has been produced in krypton by alpha-particle bombardment of Se74, enriched electromagnetically from 0.9 percent to 14.1 percent. Assignment of the isotope is made to Kr77. Aluminum absorption measurements indicate a positron end point of 1.7 Mev. In addition to annihilation radiation, gamma-rays and K-capture have been observed. The ratio of K-capture to positron emission from the Se74(?,n) reaction is computed as 2.6. The krypton 1.42-day isotope has been produced by an ?,n reaction on electromagnetically enriched Se76. The isotope is located as Kr79 and its half-life confirmed. A positron end point of 1.0 Mev is determined by aluminum absorption measurements. In addition to annihilation radiation, gamma-rays and K-capture have been observed. The ratio of K-capture to positron emission from the Se76(?,n) reaction is computed to be 50. The cross-section ratio for formation of Kr77 compared to Kr79 by alpha-particle bombardment of selenium is computed as 1.4. The 4.6-hour Kr85 isotope has been produced by a Se(?,n) reaction.

L. L. Woodward; D. A. Mccown; M. L. Pool

1948-10-01T23:59:59.000Z

119

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

NLE Websites -- All DOE Office Websites (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...

120

The Viscosity of Liquid Helium  

Science Journals Connector (OSTI)

2 September 1935 research-article The Viscosity of Liquid Helium J. O. Wilhelm A. D. Misener A. R. Clark The Royal Society is collaborating with JSTOR to digitize, preserve...

1935-01-01T23:59:59.000Z

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.


121

Roughening transition and helium crystals  

Science Journals Connector (OSTI)

Crystal shapes or crystal growth mechanisms depend drastically on whether the crystal surface is smooth or rough, i.e. whether the temperature is lower or higher than its roughening temperature. Helium appeared r...

S. Balibar; F. Gallet; E. Rolley; P. E. Wolf

1985-01-01T23:59:59.000Z

122

Liquid helium cryo TEM | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

cryo TEM Liquid helium cryo TEM The JEOL JEM-3000SFF was designed for high-resolution cryogenic transmission electron microscopy (cryo-EM) of biological samples and expands EMSL...

123

Isotope Analysis  

Science Journals Connector (OSTI)

Naturally occurring oxygen includes three stable isotopes,16O,17O, and18O, with the relative abundances of 99.763%, 0.0375%, and 0.1995%, respectively. Isotopic analysis does not consider the absolute abundances ...

Tandong Yao; Wusheng Yu; Huabiao Zhao…

2014-08-01T23:59:59.000Z

124

Definition: Isotopic Analysis- Fluid | Open Energy Information  

Open Energy Info (EERE)

Definition Definition Edit with form History Facebook icon Twitter icon » Definition: Isotopic Analysis- Fluid Jump to: navigation, search Dictionary.png Isotopic Analysis- Fluid Isotopes are atoms of the same element that have different numbers of neutrons. An isotopic analysis looks at a particular isotopic element(s) in a given system, while the conditions which increase/decrease the number of neutrons are well understood and measurable. Fluid isotopes are used to characterize a fluids origin, age, and/or interaction with rocks or other fluids based on unique isotopic ratios or concentrations.[1] View on Wikipedia Wikipedia Definition Isotope geochemistry is an aspect of geology based upon study of the relative and absolute concentrations of the elements and their isotopes in

125

Definition: Isotopic Analysis | Open Energy Information  

Open Energy Info (EERE)

Analysis Analysis Jump to: navigation, search Dictionary.png Isotopic Analysis Isotopes are atoms of the same element that have different numbers of neutrons. An isotopic analysis looks at a particular isotopic element(s) in a given system, while the conditions which increase/decrease the number of neutrons are well understood and measurable.[1] View on Wikipedia Wikipedia Definition Isotope analysis is the identification of isotopic signature, the distribution of certain stable isotopes and chemical elements within chemical compounds. This can be applied to a food web to make it possible to draw direct inferences regarding diet, trophic level, and subsistence. Isotope ratios are measured using mass spectrometry, which separates the different isotopes of an element on the basis of their mass-to-charge

126

Isotopic Analysis At Dixie Valley Geothermal Field Area (Kennedy & Van  

Open Energy Info (EERE)

Dixie Valley Geothermal Field Area (Kennedy & Van Dixie Valley Geothermal Field Area (Kennedy & Van Soest, 2005) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Dixie Valley Geothermal Field Area (Kennedy & Van Soest, 2005) Exploration Activity Details Location Dixie Valley Geothermal Field Area Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful DOE-funding Unknown Notes Dixie Valley study suggests that helium isotopes may provide a new tool for mapping zones of deep permeability and therefore the potential for high fluid temperatures. The permeable zones are identified by local enrichments in 3He relative to a regional helium isotope trend. More work needs to be done, but it appears that helium isotopes may provide the best and perhaps

127

Carbon Isotopes  

NLE Websites -- All DOE Office Websites (Extended Search)

Atmospheric Trace Gases » Carbon Isotopes Atmospheric Trace Gases » Carbon Isotopes Carbon Isotopes Gateway Pages to Isotopes Data Modern Records of Carbon and Oxygen Isotopes in Atmospheric Carbon Dioxide and Carbon-13 in Methane 800,000 Deuterium Record and Shorter Records of Various Isotopic Species from Ice Cores Carbon-13 13C in CO Measurements from Niwot Ridge, Colorado and Montana de Oro, California (Tyler) 13C in CO2 NOAA/CMDL Flask Network (White and Vaughn) CSIRO GASLAB Flask Network (Allison, Francey, and Krummel) CSIRO in situ measurements at Cape Grim, Tasmania (Francey and Allison) Scripps Institution of Oceanography (Keeling et al.) 13C in CH4 NOAA/CMDL Flask Network (Miller and White) Northern & Southern Hemisphere Sites (Quay and Stutsman) Northern & Southern Hemisphere Sites (Stevens)

128

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

129

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...

130

Isotope Effects on the Enzymatic and Nonenzymatic Reactions of Chorismate  

Science Journals Connector (OSTI)

The isotopic composition of the latter was determined by isotope ratio mass spectrometry, enabling determination of isotope effects at the mechanistically interesting key positions O7, C1, and C9. ... Heavy atom isotope effects on the nonenzymatic Claisen rearrangement to give prephenate, 18k1 and 13k1, were determined at 60 °C as described for the enzymatic reactions and calculated from the following relationship: where xk1 is the apparent isotope effect, expressed as a ratio of the rate constants for the light and heavy (x) isotopes. ...

S. Kirk Wright; Michael S. DeClue; Ajay Mandal; Lac Lee; Olaf Wiest; W. Wallace Cleland; Donald Hilvert

2005-08-27T23:59:59.000Z

131

Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere  

Science Journals Connector (OSTI)

...isotopic ratios of primary sulfate produced from combustion processes . Tellus B Chem Phys Meterol 54 ( 3...isotopic ratios of primary sulfate produced from combustion processes. Tellus Series B-246 Chemical and Physical Meteorology...

Robina Shaheen; Mariana M. Abaunza; Teresa L. Jackson; Justin McCabe; Joël Savarino; Mark H. Thiemens

2014-01-01T23:59:59.000Z

132

Isotopic Analysis At Dixie Valley Geothermal Field Area (Kennedy & Van  

Open Energy Info (EERE)

Isotopic Analysis At Dixie Valley Geothermal Field Area (Kennedy & Van Isotopic Analysis At Dixie Valley Geothermal Field Area (Kennedy & Van Soest, 2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Dixie Valley Geothermal Field Area (Kennedy & Van Soest, 2006) Exploration Activity Details Location Dixie Valley Geothermal Field Area Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful DOE-funding Unknown Notes Fluids from springs, fumaroles, and wells throughout Dixie Valley, NV were analyzed for noble gas abundances and isotopic compositions. The helium isotopic compositions of fluids produced from the Dixie Valley geothermal field range from 0.70 to 0.76 Ra, are among the highest values in the valley, and indicate that _7.5% of the total helium is derived from the

133

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

134

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

135

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

136

from Isotope Production Facility  

NLE Websites -- All DOE Office Websites (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...

137

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

138

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

139

Fission Product Ratios as Treaty Monitoring Discriminants  

SciTech Connect

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

140

Isotope studies in photosynthesis  

Science Journals Connector (OSTI)

Isotope studies in photosynthesis ... Examines the use of isotopic oxygen, hydrogen, carbon, and phosphorus in the study of photosynthesis. ...

J. A. Bassham; A. A. Benson; Melvin Calvin

1953-01-01T23:59:59.000Z

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.


141

On the Triplets of Helium  

Science Journals Connector (OSTI)

It is well known that the inversion of the helium triplets and their deviation from interval rule are due to the spin-other-orbit and to the magnetic spin-spin interactions (respectively), which may be neglected in comparison with the spin-orbit interaction in treating the spectra of heavy elements. The preliminary calculation of Heisenberg is compared with the correct calculation of Breit for the lowest triplet. The extension to higher triplets, by Araki, is simplified and generalized, and the comparison with experiment is discussed.

D. R. Inglis

1942-03-01T23:59:59.000Z

142

Closed cycle liquid helium refrigerators  

Science Journals Connector (OSTI)

We have developed closed cycle liquid helium refrigerators using a Joule Thomson circuit precooled by commercially available two staged Gifford Mac Mahon cryocoolers. The Joule Thomson counterflow heat exchangers are modular and have been thermo-hydraulically characterized. Fully automatic cool down and operation are achieved by two pneumatically driven by pass and expansion valves. Several apparatus have been built or are under assembly with cooling power ranging from 100 mW up to 5 Watt, for temperature ranging from 2.8 K up to 4.5 K. A trouble free operation with several warm up and cool down cycles has been proven over 7000 hours.

G. Claudet; R. Lagnier; A. Ravex

1992-01-01T23:59:59.000Z

143

Neutron Scattering from Liquid Helium at Large Momentum Transfer  

Science Journals Connector (OSTI)

......letter Letters to the Editor Neutron Scattering from Liquid Helium at Large...Vol. 46 (1971), No. 1 Neutron Scattering from Liquid Helium at Large...Feynman diagram for the elastic scattering of a neutron from liquid helium, where......

Sigenobu Sunakawa; Kazuo Okajima; Kiyohisa Matsuda

1971-07-01T23:59:59.000Z

144

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

145

Control of radio-frequency atmospheric pressure argon plasma characteristics by helium gas mixing  

SciTech Connect

The control of plasma characteristics is one of the important issues in many atmospheric pressure plasma applications. In order to accomplish this control, a feasibility study was performed by investigating the role of helium gas in an argon glow plasma that were produced in ambient air by 13.56 MHz radio-frequency power. Optical emission spectroscopy was used to measure rotational temperature and emission spectra acquired between 300 and 840 nm. Based on electrical and optical measurements, parameters such as gas temperature, breakdown voltage, power coupling efficiency, spatial uniformity of rotational temperature, and the sum of the emission intensity were controlled by varying the argon and helium gas mixing ratio. The addition of helium gas (from 0 to 10 lpm) to the argon flow (of 10 lpm) lowered the breakdown voltage (from 430 to 300 V{sub pk}) and the rotational temperature (from 465 to 360 K). However, an excessive addition of helium resulted in a reduction of the spatial uniformity and efficiency of power coupling. When the ratio of helium to argon flow was between 0.3 and 0.5, a high spatial uniformity with a relatively low gas temperature and breakdown voltage was achieved. This suggests that mixing of the supply gas is a useful way of controlling the plasma characteristics that may be utilized for applications with specific required discharge conditions.

Moon, Se Youn; Han, Jewoo; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2006-01-15T23:59:59.000Z

146

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

147

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

148

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 cospectral similarity for temperature and water vapor isotope fluxes. mixing ratio generator Routine field use in water vapor isotope research. The unit generates a stable water vapor mixing ratio by measuring

Minnesota, University of

149

Helium refrigeration considerations for cryomodule design  

SciTech Connect

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

150

The helium-rich cataclysmic variable SBSS 1108+574  

E-Print Network (OSTI)

We present time-resolved spectroscopy and photometry of the dwarf nova SBSS 1108+574, obtained during the 2012 outburst. Its quiescent spectrum is unusually rich in helium, showing broad, double-peaked emission lines from the accretion disc. We measure a line flux ratio HeI 5875/Halpha = 0.81 +/- 0.04, a much higher ratio than typically observed in cataclysmic variables (CVs). The outburst spectrum shows hydrogen and helium in absorption, with weak emission of Halpha and HeI 6678, as well as strong HeII emission. From our photometry, we find the superhump period to be 56.34 +/- 0.18 minutes, in agreement with the previously published result. The spectroscopic period, derived from the radial velocities of the emission lines, is found to be 55.3 +/- 0.8 minutes, consistent with a previously identified photometric orbital period, and significantly below the normal CV period minimum. This indicates that the donor in SBSS 1108+574 is highly evolved. The superhump excess derived from our photometry implies a mass r...

Carter, P J; de Miguel, E; Goff, W; Koff, R A; Krajci, T; Marsh, T R; Gänsicke, B T; Breedt, E; Groot, P J; Nelemans, G; Roelofs, G H A; Rau, A; Koester, D; Kupfer, T

2013-01-01T23:59:59.000Z

151

Evolution of the geothermal fluids at Los Azufres, Mexico, as traced by noble gas isotopes, ?18O, ?D, ?13C and 87Sr/86Sr  

Science Journals Connector (OSTI)

Isotopes of noble gases, CO2, H2O and Sr were measured in 10 geothermal wells and 8 hot springs, fumaroles and mud volcanoes at Los Azufres, the second most important geothermal field in Mexico. The aim of this study is to provide additional information on fluid circulation in the field and surrounding areas (Araró hot springs), as well as on physical processes such as boiling, steam separation and invasion of re-injected brines following over 25 years of geothermal fluid exploitation. Mantle helium dominates in fluids from the northern production zone of Marítaro, with measured 3He/4He ratios up to 7 Ra (where Ra is the atmospheric ratio of 1.386 × 10? 6). 3He/4He ratios are positively correlated with 87Sr/86Sr ratios and with ?D and ?18O. These relationships suggest that Los Azufres fluids represent a mixing between primary magmatic 3He-rich fluids and groundwater currently discharging at Araró hot springs and enriched in radiogenic 4He acquired from Miocene andesites. Unusually high He ratios together with radiogenic Sr isotopic ratios suggest that thermal waters acquired mantle He from deep-seated parent magmas and radiogenic Sr possibly during their uprising through the metamorphic basement. 40Ar/36Ar ratios of 366 to 429 measured in two wells indicate either mantle-derived argon or a radiogenic 40Ar in situ component, suggesting the local presence of an older crustal fluid component in the northern part of the field. Ne, Kr and Xe are entirely of atmospheric origin, but processes of boiling, steam separation and re-injection of used brines have led to fractionation of their elemental abundances. Comparison with previous studies suggests that the boiling zone in the northern production zone is currently extending further north (Marítaro hot springs). In the southwestern productive zone, re-injected brines might account for more than 90% of the exploited fluids.

D.L. Pinti; M.C. Castro; O. Shouakar-Stash; A. Tremblay; V.H. Garduño; C.M. Hall; J.-F. Hélie; B. Ghaleb

2013-01-01T23:59:59.000Z

152

In situ boron isotope measurements of natural geological materials by LA-MC-ICP-MS  

Science Journals Connector (OSTI)

There are two main methods to determine boron isotopic composition. One is the solution method, in which boron is purified after the samples are dissolved in solution and the boron isotope ratios are determined b...

KeJun Hou; YanHe Li; YingKai Xiao; Feng Liu; YouRong Tian

2010-10-01T23:59:59.000Z

153

Pb isotope data of Roman and medieval objects from Wiesloch near Heidelberg, Germany  

Science Journals Connector (OSTI)

Lead isotope abundance ratios have become a reliable and common tool for obtaining information on the provenance of archaeological material containing lead. This paper presents Pb-isotope data of lead-silver s...

Florian Ströbele; Ludwig H. Hildebrandt…

2014-08-01T23:59:59.000Z

154

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.

155

Phase transitions of helium in aerogel  

Science Journals Connector (OSTI)

The effect of dilute quenched impurities on the liquid-vapor critical point, superfluid and He3?He4 phase separation transitions were studied by introducing liquid helium into aerogel. Aerogel is a highly porous ...

M. H. W. Chan

1996-01-01T23:59:59.000Z

156

NIDC: Online Catalog of Isotope Products | Product List  

NLE Websites -- All DOE Office Websites (Extended Search)

List List Please select an available isotope product from the lists below. If you would like an isotope product that is not listed, you can make a request by clicking here. Stable Isotope Products Radio-Isotope Products Antimony Argon (Alt) Barium Bromine Bromine (Alt) Cadmium Calcium Carbon (Alt) Cerium Chlorine Chlorine (Alt) Chromium Copper Dysprosium Erbium Europium Gadolinium Gallium Germanium Hafnium Helium (Alt) Indium Iridium Iron Krypton (Alt) Lanthanum Lead Lithium Lutetium Magnesium Mercury Molybdenum Neodymium Neon (Alt) Nickel Nitrogen (Alt) Osmium Oxygen (Alt) Palladium Platinum Potassium Rhenium Rubidium Ruthenium Samarium Selenium Silicon Silver Strontium Sulfur Sulfur (Alt) Tantalum Tellurium Thallium Tin Titanium Tungsten Vanadium Xenon (Alt) Ytterbium Zinc Zirconium Actinium-225 Aluminum-26 Americium-241

157

Equation of state of metallic helium  

SciTech Connect

The effective ion-ion interaction, free energy, pressure, and electric resistance of metallic liquid helium have been calculated in wide density and temperature ranges using perturbation theory in the electron-ion interaction potential. In the case of conduction electrons, the exchange interaction has been taken into account in the random-phase approximation and correlations have been taken into account in the local-field approximation. The solid-sphere model has been used for the nuclear subsystem. The diameter of these spheres is the only parameter of this theory. The diameter and density of the system at which the transition of helium from the singly ionized to doubly ionized state occurs have been estimated by analyzing the pair effective interaction between helium atoms. The case of doubly ionized helium atoms has been considered. Terms up to the third order of perturbation theory have been taken into account in the numerical calculations. The contribution of the third-order term is significant in all cases. The electric resistance and its temperature dependence for metallic helium are characteristic of simple divalent metals in the liquid state. The thermodynamic parameters-temperature and pressure densities-are within the ranges characteristic of the central regions of giant planets. This makes it possible to assume the existence of helium in the metallic state within the solar system.

Shvets, V. T., E-mail: tarval@breezein.net [Odessa State Academy of Refrigeration (Ukraine)

2013-01-15T23:59:59.000Z

158

lead-isotope dating  

Science Journals Connector (OSTI)

lead-isotope dating, lead-lead dating, lead-isotope age measurement, lead-lead age measurement ? Blei-Isotopen(-Alters)bestimmung, f, Blei-Isotopen-Datierung

2014-08-01T23:59:59.000Z

159

Selected Isotopes for Optimized Fuel Assembly Tags  

SciTech Connect

In support of our ongoing signatures project we present information on 3 isotopes selected for possible application in optimized tags that could be applied to fuel assemblies to provide an objective measure of burnup. 1. Important factors for an optimized tag are compatibility with the reactor environment (corrosion resistance), low radioactive activation, at least 2 stable isotopes, moderate neutron absorption cross-section, which gives significant changes in isotope ratios over typical fuel assembly irradiation levels, and ease of measurement in the SIMS machine 2. From the candidate isotopes presented in the 3rd FY 08 Quarterly Report, the most promising appear to be Titanium, Hafnium, and Platinum. The other candidate isotopes (Iron, Tungsten, exhibited inadequate corrosion resistance and/or had neutron capture cross-sections either too high or too low for the burnup range of interest.

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

2008-10-01T23:59:59.000Z

160

In situ Carbon 13 and Oxygen 18 Ratios of Atmospheric CO2 from Cape Grim,  

NLE Websites -- All DOE Office Websites (Extended Search)

Oxygen Isotopes and Ratios » 13C and 18O Oxygen Isotopes and Ratios » 13C and 18O Ratios, Atmospheric CO2, Cape Grim In situ Carbon 13 and Oxygen 18 Ratios of Atmospheric CO2 from Cape Grim, Tasmania, Australia: 1982-1993 DOI: 10.3334/CDIAC/atg.db1014 data Data Investigators Francey R. J. and C. E. Allison Description Since 1982, a continuous program of sampling atmospheric CO2 to determine stable isotope ratios has been maintained at the Australian Baseline Air Pollution Station, Cape Grim, Tasmania (40°, 40'56"S, 144°, 41'18"E). The process of in situ extraction of CO2 from air, the preponderance of samples collected in conditions of strong wind from the marine boundary layer of the Southern Ocean, and the determination of all isotope ratios relative to a common high purity CO2 reference gas with isotopic δ13C close to

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

Isotope/element fractionation during surface adsorption  

Science Journals Connector (OSTI)

The adsorption of ions onto mineral surfaces accompanies isotope/element fractionation in planets and asteroids. A model based on simple classical physics is presented to predict these fractionations. The agreement between the experimentally observed isotope/element ratios and their predicted values is found to be excellent. This fractionation can be demonstrated experimentally in advanced physics laboratories using macroscopic particles. The success of the model shows students that even a very complex naturally occurring process can be explained quantitatively with simple physics.

Gamini Seneviratne; Asiri Nanayakkara

2004-01-01T23:59:59.000Z

162

Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak  

DOE R&D Accomplishments (OSTI)

Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

1993-03-00T23:59:59.000Z

163

ISAC SC-LINAC PHASE-II HELIUM REFRIGERATOR COMMISSIONING AND FIRST OPERATIONAL EXPERIENCE AT TRIUMF  

SciTech Connect

ISAC Phase-II is an upgrade of the radioactive isotope superconducting linear accelerator, SC-linac, at TRIUMF. The Phase-I section of the accelerator, medium-beta, is operational and is cooled with a 600 W helium refrigerator, commissioned in March 2005. An identical refrigerator is being used with the Phase-II segment of the accelerator; which is now under construction. The second refrigerator has been commissioned and tested with the Phase-I section of the linac and is used for Phase-II linac development, including new SC-cavity performance tests. The commissioning of the Phase-II refrigeration system and recent operational experience is presented.

Sekachev, I.; Kishi, D.; Laxdal, R. E. [TRIUMF, Vancouver, BC, V6T 2A3 (Canada)

2010-04-09T23:59:59.000Z

164

Isotopic Analysis At Separation Creek Area (Van Soest, Et Al., 2002) | Open  

Open Energy Info (EERE)

Isotopic Analysis At Separation Creek Area (Van Soest, Et Al., 2002) Isotopic Analysis At Separation Creek Area (Van Soest, Et Al., 2002) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Fluid At Separation Creek Area (Van Soest, Et Al., 2002) Exploration Activity Details Location Separation Creek Area Exploration Technique Isotopic Analysis- Fluid Activity Date Usefulness useful DOE-funding Unknown References M. C. van Soest, B. M. Kennedy, W. C. Evans, R. H. Mariner (2002) Mantle Helium And Carbon Isotopes In Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon- Evidence For Renewed Volcanic Activity Or A Long Term Steady State System(Question) Retrieved from "http://en.openei.org/w/index.php?title=Isotopic_Analysis_At_Separation_Creek_Area_(Van_Soest,_Et_Al.,_2002)&oldid=687475"

165

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

166

Stable isotope studies  

SciTech Connect

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

167

Helium-filled aluminum flight tubes  

NLE Websites -- All DOE Office Websites (Extended Search)

Helium-filled aluminum flight tubes. Helium-filled aluminum flight tubes. Detector housing for the CCD camera lens, mirror, and scintillator. For more information, contact Instrument Scientist: Hassina Bilheux, bilheuxhn@ornl.gov, 865.384.9630 neutrons.ornl.gov/instruments/HFIR/factsheets/Instrument-cg1d.pdf The CG-1D beam is used for neutron imaging measurements using a white beam. Apertures (with different diameters D (pinhole geometry) are used at the entrance of the helium-filled flight path to allow L/D variation from 400 to 800. L is the distance between the aperture and the detector (where the image is produced). Samples sit on a translation/ rotation stage for alignment and tomography purposes. Detectors for CG-1D include

168

Helium corona-assisted air discharge  

SciTech Connect

Operation of atmospheric discharge of electronegative gases including air at low voltages yet without consuming any inert gas will enormously promote the application of non-thermal plasmas. By taking advantage of the low onset voltage for helium corona, air discharge was successfully launched at much reduced voltages with a needle-plate system partly contained in a helium-filled glass bulb--for a needle-plate distance of 12 mm, 1.0 kV suffices. Ultraviolet emission from helium corona facilitates the discharging of air, and the discharge current manifests distinct features such as relatively broad Trichel pulses in both half periods. This design allows safe and economic implementation of atmospheric discharge of electronegative gases, which will find a broad palette of applications in surface modification, plasma medicine and gas treatment, etc.

Jiang Nan; Gao Lei; Ji Ailing; Cao Zexian [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2011-10-15T23:59:59.000Z

169

Laser Ablation Molecular Isotopic Spectrometry: Parameter influence on boron isotope measurements  

Science Journals Connector (OSTI)

Laser Ablation Molecular Isotopic Spectrometry (LAMIS) was recently reported for optical isotopic analysis of condensed samples in ambient air and at ambient pressure. LAMIS utilizes molecular emissions which exhibit larger isotopic spectral shits than in atomic transitions. For boron monoxide 10BO and 11BO, the isotopic shifts extend from 114 cm?1 (0.74 nm) to 145–238 cm?1 (5–8 nm) at the B 2?+ (v = 0) ? X 2?+ (v = 2) and A 2?i (v = 0) ? X 2?+ (v = 3) transitions, respectively. These molecular isotopic shifts are over two orders of magnitude larger than the maximum isotopic shift of approximately 0.6 cm?1 in atomic boron. This paper describes how boron isotope abundance can be quantitatively determined using LAMIS and how atomic, ionic, and molecular optical emission develops in a plasma emanating from laser ablation of solid samples with various boron isotopic composition. We demonstrate that requirements for spectral resolution of the measurement system can be significantly relaxed when the isotopic abundance ratio is determined using chemometric analysis of spectra. Sensitivity can be improved by using a second slightly delayed laser pulse arriving into an expanding plume created by the first ablation pulse.

Xianglei Mao; Alexander A. Bol'shakov; Dale L. Perry; Osman Sorkhabi; Richard E. Russo

2011-01-01T23:59:59.000Z

170

Underground helium travels to the Earth's surface via aquifers...  

NLE Websites -- All DOE Office Websites (Extended Search)

carried to the surface with the flow of water. The only place where helium is made on Earth is underground, where deep veins of uranium and thorium give off atoms of helium as...

171

Fluid helium at conditions of giant planetary interiors  

Science Journals Connector (OSTI)

...the nonmetal-to-metal transition in fluid helium . Phys Rev Lett 98 : 190602 . 41 Ternovoi VY Filimonov AS Pyalling AA Mintsev VB Fortov VE ( 2002 ) Thermophysical properties of helium under multiple shock compression in Shock Compression of Condensed...

Lars Stixrude; Raymond Jeanloz

2008-01-01T23:59:59.000Z

172

A Strontium Isotopic Study Of Newberry Volcano, Central Oregon- Structural  

Open Energy Info (EERE)

Strontium Isotopic Study Of Newberry Volcano, Central Oregon- Structural Strontium Isotopic Study Of Newberry Volcano, Central Oregon- Structural And Thermal Implications Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Strontium Isotopic Study Of Newberry Volcano, Central Oregon- Structural And Thermal Implications Details Activities (2) Areas (1) Regions (0) Abstract: Ratios of 87Sr/86Sr were determined in twenty-seven basaltic rocks from Newberry. These ratios range from 0.70330 to 0.70414; most fall between 0.7035 and 0.7038. Covariance of Al2O3/FeO* ratio, TiO2 content, and Th content with 87Sr/86Sr suggests that some isotopic ratios reflect shallow crustal contamination, but the data also suggest that two mantle sources, a prominent one at 0.7036 and a less-prominent one at 0.7033 or less, are represented. The hypothesis of crustal contamination is supported

173

Isotopically pumped isotopic CF4 laser  

Science Journals Connector (OSTI)

Single-mode optical pumping of CF4 to generate 16-µm frequencies has been extended to include the isotopic species 12CF4,...

Eckhardt, Roger; Telle, John; Haynes, Larry

1982-01-01T23:59:59.000Z

174

Impact of nuclear irradiation on helium bubble nucleation at interfaces in liquid metals coupled to permeation through stainless steels  

E-Print Network (OSTI)

The impact of nucleating gas bubbles in the form of a dispersed gas phase on hydrogen isotope permeation at interfaces between liquid metals, like LLE, and structural materials, like stainless steel, has been studied. Liquid metal to structural material interfaces involving surfaces, may lower the nucleation barrier promoting bubble nucleation at active sites. Hence, hydrogen isotope absorption into gas bubbles modelling and control at interfaces may have a capital importance regarding design, operation and safety. He bubbles as a permeation barrier principle is analysed showing a significant impact on hydrogen isotope permeation, which may have a significant effect on liquid metal systems, e.g., tritium extraction systems. Liquid metals like LLE under nuclear irradiation in, e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles...

Fradera, Jorge

2013-01-01T23:59:59.000Z

175

Potential applications of high temperature helium  

SciTech Connect

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

176

Potential applications of high temperature helium  

SciTech Connect

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

177

A Miniature Helium Turbo-Expander for Cryogenic Refrigeration Systems  

Science Journals Connector (OSTI)

Publisher Summary This chapter highlights the features of a miniature helium turbo expander for cryogenic refrigeration systems. The Cryogenic Engineering Laboratory of the National Bureau of Standards has investigated the use of small, high speed turbines, supported by gas lubricated journal bearings, in small capacity refrigeration system. Two systems have been studied, one that operates at 4.2 K and another at 30 K. As a result of optimization studies, a 20:1 pressure ratio was used for the 4.2 K system. It is found that although the final low temperature is obtained with an expansion valve, work extraction is necessary for system operation. Refrigeration at 30 K is accomplished by shutting the expansion valve, and leaving the low temperature loop of the system unused. Refrigeration is obtained downstream of the turbine. It is found that for this system, optimization studies indicated best performance at 4:1 pressure ratio. A program was initiated to investigate the performance of a 4:1 pressure ratio turbine for this application. A design goal of 70% was selected from the qualitative reasoning that in larger sizes 80 to 90% was common, but in small machines friction and leakage losses tend to be relatively high.

M.T. NORTON

1965-01-01T23:59:59.000Z

178

Hydrogen isotope fractionation in freshwater algae: I. Variations among lipids and species  

E-Print Network (OSTI)

Hydrogen isotope fractionation in freshwater algae: I. Variations among lipids and species Zhaohui in media containing different concentrations of deuterium. The hydrogen isotopic ratios of lipids that lipid dD values can be used to determine water dD values, hydrogen isotope fractionation was found

Sachs, Julian P.

179

Isotope Geothermometry | Open Energy Information  

Open Energy Info (EERE)

Isotope Geothermometry Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Isotope Geothermometry Details Activities (0) Areas (0) Regions (0)...

180

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

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

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

182

E-Print Network 3.0 - application des isotopes Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Page: << < 1 2 3 4 5 > >> 1 Guidelines and recommended terms for expression of stable-isotope-ratio and gas-ratio measurement results, Summary: Guidelines and recommended terms...

183

Perchlorate Isotope Forensics  

Science Journals Connector (OSTI)

In this study, comprehensive stable isotope analyses (37Cl/35Cl and 18O/17O/16O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. ... ?37Cl and ?18O are measures of mass-dependent fractionation of Cl and O isotopes by normal physical, chemical, or biological processes. ...

John Karl Böhlke; Neil C. Sturchio; Baohua Gu; Juske Horita; Gilbert M. Brown; W. Andrew Jackson; Jacimaria Batista; Paul B. Hatzinger

2005-11-04T23:59:59.000Z

184

Isotope Effect in Adhesion  

Science Journals Connector (OSTI)

Isotope Effect in Adhesion ... We report the first observation of an isotope effect in adhesion. ... The results are presented in Figure 3. Clearly, the isotope effect is very significant, substantiating the proposed H-bonding interactions between the PDMS and Si?OH(D) surfaces. ...

Gun Young Choi; Abraham Ulman; Yitzhak Shnidman; Walter Zurawsky; Cathy Fleischer

2000-05-25T23:59:59.000Z

185

An MCMC determination of the primordial helium abundance  

SciTech Connect

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

186

Cost-Effectiveness Ratio  

Science Journals Connector (OSTI)

The cost?effectiveness ratio (CER) is a calculation that summarizes the intervention's net cost and effectiveness. The three types of CER are: the average cost?effectiveness ratio (ACER), the marginal cost?...

2008-01-01T23:59:59.000Z

187

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

SciTech Connect

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

188

A major lithospheric boundary in eastern California defined by isotope  

Open Energy Info (EERE)

major lithospheric boundary in eastern California defined by isotope major lithospheric boundary in eastern California defined by isotope ratios in Cenozoic basalts from the Coso Range and surrounding areas Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: A major lithospheric boundary in eastern California defined by isotope ratios in Cenozoic basalts from the Coso Range and surrounding areas Details Activities (1) Areas (1) Regions (0) Abstract: Sr and Nd isotope ratios of Miocene-Recent basalts in eastern California, when screened for crustal contamination, vary dramatically and indicate the presence of a major lithospheric boundary that is not obvious from surface geology. Tectonic and geochemical interpretation of this boundary is difficult, however, because there are so many potential

189

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

190

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

191

Isotope Program Transportation | Department of Energy  

Office of Environmental Management (EM)

Isotope Program Transportation Isotope Program Transportation Isotope Program Transportation More Documents & Publications Nuclear Fuel Storage and Transportation Planning Project...

192

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

SciTech Connect

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

193

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

194

Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone  

Science Journals Connector (OSTI)

... 29), as would occur at depths >10?km in all but the lowest of geothermal gradients. However, without a path for advective fluid flow in the host rocks, ... chemistry was determined with a combination of gas chromatography, ion chromatograph and manometry in the geothermal laboratory in Menlo Park, California. Noble-gas isotopic ratios, including those for He, ...

J. B. Lowenstern; W. C. Evans; D. Bergfeld; A. G. Hunt

2014-02-19T23:59:59.000Z

195

Neutron-induced helium implantation in GCFR cladding  

SciTech Connect

The neutron-induced implantation of helium atoms on the exterior surfaces of the cladding of a prototypic gas-cooled fast reactor (GCFR) has been investigated analytically. A flux of recoil helium particles as high as 4.2 x 10/sup 10/ He/cm/sup 2/.s at the cladding surface has been calculated at the peak power location in the core of a 300-MWe GCFR. The calculated profile of the helium implantation rates indicates that although some helium is implanted as deep as 20 ..mu..m, more than 99% of helium particles are implanted in the first 2-..mu..m-deep layer below the cladding surface. Therefore, the implanted helium particles should mainly affect surface properties of the GCFR cladding.

Yamada, H.; Poeppel, R. B.; Sevy, R. H.

1980-10-01T23:59:59.000Z

196

Mass-Independent Isotope Effects  

Science Journals Connector (OSTI)

Scientific interests: ESR and NMR spectroscopies, molecular magnets, mechanisms of chemical and biochemical reactions, spin physics and chemistry, isotopes and isotope effects in chemistry and biochemistry. ... Another mass-independent isotope effect was detected in 1983 as a deviation of isotopic distribution in reaction products from that which would be expected from the mass-dependent isotope effect. ... Later, Nomura et al.(92) have found isotopic 233U anomaly in the U4+–U6+ exchange reaction; they noted that the isotope effect was correlated with isotope shifts in the atomic spectra of uranium isotopes. ...

Anatoly L. Buchachenko

2013-01-09T23:59:59.000Z

197

Raman spectroscopic and mass spectrometric investigations of the hydrogen isotopes and isotopically labelled methane  

SciTech Connect

Suitable analytical methods must be tested and developed for monitoring the individual process steps within the fuel cycle of a fusion reactor and for tritium accountability. The utility of laser-Raman spectroscopy accompanied by mass spectrometry with an Omegatron was investigated using the analysis of all hydrogen isotopes and isotopically labeled methanes as an example. The Omegatron is useful for analyzing all hydrogen isotopes mixed with the stable helium isotopes. The application of this mass spectrometer were demonstrated by analyzing mixtures of deuterated methanes. In addition, it was employed to study the radiochemical Witzbach exchange reaction between tritium and methanes. A laser-Raman spectrometer was designed for analysis of tritium-containing gases and was built from individual components. A tritium-compatible, metal-sealed Raman cuvette having windows with good optical properties and additional means for measuring the stray light was first used successfully in this work. The Raman spectra of the hydrogen isotopes were acquired in the pure rotation mode and in the rotation-vibration mode and were used for on. The deuterated methanes were measured by Raman spectroscopy, the wavenumbers determined were assigned to the corresponding vibrations, and the wavenumbers for the rotational fine-structure were summarized in tables. The fundamental Vibrations of the deuterated methanes produced Witzbach reactions were detected and assigned. The fundamental vibrations of the molecules were obtained with Raman spectroscopy for the first time in this work. The @-Raman spectrometer assembled is well suited for the analysis of tritium- containing gases and is practical in combination with mass spectrometry using an Omegatron, for studying gases used in fusion.

Jewett, J.R., Fluor Daniel Hanford

1997-02-24T23:59:59.000Z

198

Helium 4 Dimer in Two Coaxial Adjacent Nanotubes  

Science Journals Connector (OSTI)

The ground state properties of the helium 4 dimer, within the geometry defined by two adjacent nanotubes with different radii and hard core walls,...

J. Brana; S. Kili?; L. Vranješ

2002-01-01T23:59:59.000Z

199

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

200

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

Note: This page contains sample records for the topic "helium isotope ratios" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


201

Stable isotope enrichment  

SciTech Connect

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

202

Alternatives for Helium-3 in Multiplicity Counters  

SciTech Connect

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

203

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

204

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

205

Assessment of uranium exposure from total activity and 234U:238U activity ratios in urine  

Science Journals Connector (OSTI)

......Excretion Patterns of Naturally Occuring 234U, 238U and Calcium...ratios in urine. | Radiation workers at Atomic Weapons...Dose-Response Relationship, Radiation Humans Isotopes analysis...prevention & control Radiation Monitoring methods Radiation......

T. Nicholas; D. Bingham

2011-03-01T23:59:59.000Z

206

Isotopic Analysis- Rock At Coso Geothermal Area (1997) | Open Energy  

Open Energy Info (EERE)

Rock At Coso Geothermal Area (1997) Rock At Coso Geothermal Area (1997) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Isotopic Analysis- Rock At Coso Geothermal Area (1997) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Isotopic Analysis- Rock Activity Date 1997 Usefulness useful DOE-funding Unknown Exploration Basis Determine a major lithospheric boundary Notes Sr and Nd isotope ratios of Miocene-Recent basalts in eastern California, when screened for crustal contamination, vary dramatically and indicate the presence of a major lithospheric boundary that is not obvious from surface geology. Isotope ratios from the Coso field form a bull's-eye pattern with very low 87Sr/86Sr (0.7033) centered just south of the geothermal area. The

207

Celebrating The Isotope  

Science Journals Connector (OSTI)

Celebrating The Isotope ... The notion of isotopes and the rest of Soddy’s lifetime body of work on radioactivity, the group displacement laws, the social responsibility of scientists, and the environment have had a profound effect on science and society. ...

GEORGE B. KAUFFMAN

2013-12-02T23:59:59.000Z

208

Isotope - based Quantum Information  

E-Print Network (OSTI)

This paper is brief review of three aspects of the isotope - based quantum information: computation, teleportation and cryptography. Our results demonstrate not only that entanglement exists in elementary excitation of isotope - mixed solids but also it can be used for quantum information processing.

Vladimir G. Plekhanov

2009-09-04T23:59:59.000Z

209

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

210

DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI  

SciTech Connect

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

211

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

212

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

213

An Atomistic study of Helium Resolution in bcc Iron  

SciTech Connect

The evolution of gas-stabilized bubbles in irradiated materials can be a significant factor in the microstructural processes that lead to mechanical property and dimensional changes in structural materials exposed to high-energy neutrons. Helium generation and accumulation is particularly important under DT fusion irradiation conditions. Although the process of ballistic resolutioning of gas from bubbles has been long-discussed in the literature, there have been few computational studies of this mechanism. Resolutioning could limit bubble growth by ejecting gas atoms back into the metal matrix. A detailed atomistic study of ballistic He resolutioning from bubbles in bcc iron has been carried out using molecular dynamics. A newly-developed Fe-He interatomic potential was employed, with the iron matrix described by the potential of Ackland and co-workers from 1997. The primary variables examined were: irradiation temperature (100 and 600K), iron knock-on atom 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) in order to obtain an assessment of this dynamic resolutioning mechanism. The results presented here focus on the 5 keV cascades which indicate a modest, but potentially significant level of He removal by this process.

Stoller, Roger E [ORNL; Stewart, David M [ORNL

2011-01-01T23:59:59.000Z

214

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

215

Steam reformers heated by helium from high temperature reactors  

Science Journals Connector (OSTI)

The manifold possibilities of the application of helium-heated steam reformers combined with high temperature nuclear reactors are elucidated in this article. It is shown that the thermodynamic interpretation of the processes does not cause difficulties because of the good heat transfer in helium at high pressure and that helium peak temperatures of 950°C are sufficient for carrying out the process. The mechanical design of the reformer tube does not lead to problems because the helium and process pressures are so chosen as to be approximately equal. The problems of hydrogen and tritium permeation as well as the contamination of the reformer tube with solid fission products seem to be solvable using the knowledge available at present. Furthermore, the various possibilities for the design arrangements of helium-heated reformer tube furnaces are shown. The status of development attained to date is outlined and in conclusion there is a survey regarding the next steps to be taken in steam reformer technology.

K. Kugeler; M. Kugeler; H.F. Niessen; K.H. Hammelmann

1975-01-01T23:59:59.000Z

216

Lithium Isotope Analyses of Inorganic Constituents from the Murchison Meteorite  

Science Journals Connector (OSTI)

Aqueous processes were important modifiers of solid matter during the early stages of solar system history. Lithium isotopes are sensitive indicators of such solid-liquid interactions because 7Li passes preferentially into solution and 6Li remains behind in the solid phase. Lithium isotope ratios of inorganic phases in the Murchison meteorite reveal that the value for the whole rock is simply the average of individual components with widely different isotopic compositions. 7Li content increases from chondrules to phyllosilicate-rich matrices to carbonates, as would be expected from the relative duration each component has spent during aqueous alteration on the parent asteroid.

Mark A. Sephton; Rachael H. James; Philip A. Bland

2004-01-01T23:59:59.000Z

217

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

SciTech Connect

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

218

Oxygen isotope analysis of multiple, single ostracod valves as a proxy for combined variability in seasonal temperature and lake water oxygen isotopes  

Science Journals Connector (OSTI)

Paleoclimate studies in lakes typically use oxygen isotopic ratios in samples that consist of multiple ostracod specimens, to obtain an average ?18O value that reflects the mean temperature and ?18O of lake water...

Yama Dixit; David A. Hodell; Rajiv Sinha; Cameron A. Petrie

2014-10-01T23:59:59.000Z

219

Determination of boron isotopic variations in aquatic systems with negative thermal ionization mass spectrometry as a tracer for anthropogenic influences  

Science Journals Connector (OSTI)

A technique for precise boron isotope ratio measurements with a high detection power ... –0.3% have been obtained for the determination of the 11B/10B isotope ratio using nanogram amounts of boron. Ba(OH)2 has be...

S. Eisenhut; K. G. Heumann; A. Vengosh

1996-03-01T23:59:59.000Z

220

F Band in Isotopically Enriched LiF  

Science Journals Connector (OSTI)

The effect of isotopic composition on the optical obsorption spectrum of the F center in LiF has been investigated. The results of measurements on single crystals of x-ray irradiated Li6F (almost 96% lithium-6) and Li7F (almost 100% lithium-7) indicate that the average F-band width at half-maximum in the former is larger by about 3% at liquid-helium temperature, and by about 1% at room temperature. Theory shows that the half-widths in the two isotopic forms vary inversely as the fourth root of the mass of the alkali ions at low temperature, and as the temperature is increased the predicted half-width difference monotonically decreases to zero. The predicted half-width difference at low temperatures is about 4%, and at room temperature about 1%, both in reasonable agreement with experiment. At both room and liquid-helium temperatures the position of the F-band maximum in Li7F is slightly displaced to higher energy than in Li6F. The peak-position shift is in approximate agreement with the contributions arising from the difference in alkali mass and lattice constant of the two crystals as estimated at low temperature.

Herbert Rabin and Michael Reich

1964-07-06T23:59:59.000Z

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.


221

Scattering of Fast Neutrons by Helium  

Science Journals Connector (OSTI)

Measurements have been made of the angular distribution of helium recoils for incident neutrons of energies from 0.6 to 1.6 Mev. The distribution curves also permit estimates of the total cross section in this energy range. The results confirm the existence of a cross-section peak of about 6.8×10-24 cm2 around 1 Mev and indicate, under the assumption of s- and p-wave scattering only, that the peak is double. But preliminary attempts to fit the data to Bloch's detailed theory of s- and p-scattering with a split p-level have not been successful, and the sign of the postulated splitting is not established.

T. A. Hall and P. G. Koontz

1947-08-01T23:59:59.000Z

222

Continuous Photoelectric Absorption Cross Section of Helium  

Science Journals Connector (OSTI)

The continuous photoelectric absorption cross section of helium has been measured in the spectral region extending from 180 to 600 A with greater accuracy and the observations are found to agree with the calculations of Huang and Stewart and Wilkinson. A grazing incidence spectrometer with a photomultiplier was used for a single measurement at 180 A while the remaining measurements were carried out in a normal incidence spectrometer utilizing photographic techniques. Whereas in previous experiments the absorbing gas sample was allowed to fill the entire spectrometer chamber, in the current measurements the gas was confined to a small cell provided with sufficiently transparent windows. The use of an absorption cell reduces contamination and facilitates the measurement of gas pressures. The results indicate that the cross section varies from a value of 0.98±0.04 Mb at 180 A to a value of 7.7±0.3 Mb at the absorption edge located at 504 A.

D. J. Baker; Jr.; D. E. Bedo; D. H. Tomboulian

1961-12-01T23:59:59.000Z

223

Helium in the outer solar atmosphere  

Science Journals Connector (OSTI)

We construct models of the outer solar atmosphere comprising the region from the mid chromosphere and into the solar wind in order to study the force and energy balance in models with a significant helium abundance. The corona is created by dissipation of an energy flux from the Sun. The energy flux is lost as radiation from the top of the chromosphere and as gravitational and kinetic solar wind energy flux. We find that in models with significant ion heating of the extended corona most of the energy flux is lost in the solar wind. The ion temperatures are higher than the electron temperature in these models and the ?-particle temperature is much higher than the proton temperature. Roughly speaking we find that the relative ?-particle and proton fluxes are set by the degree of chromospheric mixing while the speeds are set by the details of the coronal heating process.

V. H. Hansteen; E. Leer; T. E. Holzer

1997-01-01T23:59:59.000Z

224

Isotope correlations for determining the isotopic composition of plutonium produced in research and power reactors using the experimental data obtained by alpha and mass spectrometry  

Science Journals Connector (OSTI)

Correlations have been developed for obtaining the isotopic composition of Pu produced in Indian research (CIRUS, DHRUVA) and power (PHWR) reactors. The experimental data obtained on 238Pu/(239Pu + 240Pu) alpha activity ratio using alpha spectrometry and on 240Pu/239Pu, 241Pu/239Pu, 242Pu/239Pu atom ratios by thermal ionisation mass spectrometry were used for developing isotope correlations.

S.K. Aggarwal; D. Alamelu

2005-01-01T23:59:59.000Z

225

Helium solubility in SON68 nuclear waste glass  

SciTech Connect

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

226

ISOTOPES IN WATER  

Science Journals Connector (OSTI)

The study of isotopic prosies ha two different though related basic aims: an understanding of the way in which the water cycle in linked to alterations in climate, and how the carbon cycle has responded to the...

W. GEORGE DARLING; ADRIAN H. BATH…

2006-01-01T23:59:59.000Z

227

Thermophysical Properties of Helium under Multiple Shock Compression  

Science Journals Connector (OSTI)

The results on measurements of thermodynamic properties and electrical conductivity of Helium compressed with shock wave reverberation technique up to pressure and density of 200 GPa and 1.4 g/cc are presented. The increase of the Helium conductivity up to the values of 1000 1/(Ohm?cm) was found at the densities more than 0.7 g/cc and temperature more than 15 kK. Comparison of the experimental results with different theoretical models of thermodynamic and transport properties of shocked Helium was done.

Vladimir Ya. Ternovoi; Alexander S. Filimonov; Alexei A. Pyalling; Viktor B. Mintsev; Vladimir E. Fortov

2002-01-01T23:59:59.000Z

228

Nuclear isotope thermometry  

Science Journals Connector (OSTI)

We discuss different aspects which might influence temperatures deduced from experimental isotopic yields in the multifragmentation process. It is shown that fluctuations due to the finite size of the system and distortions due to the decay of hot primary fragments conspire to blur the temperature determination in multifragmentation reactions. These facts suggest that caloric curves obtained through isotope thermometers, which were taken as evidence for a first-order phase transition in nuclear matter, should be investigated very carefully.

S. R. Souza, W. P. Tan, R. Donangelo, C. K. Gelbke, W. G. Lynch, and M. B. Tsang

2000-11-10T23:59:59.000Z

229

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

SciTech Connect

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

230

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

231

Spallation-Fission Competition in Heaviest Elements; Helium Ion Induced Reactions in Plutonium Isotopes  

E-Print Network (OSTI)

James W. Cobble, and Glenn T. Seaborg Radiation LaboratoryJames W. Cobble, and Glenn T. Seaborg Radiation Laboratory

Glass, Richard A.; Carr, Robert J.; Cobble, James W.; Seaborg, Glenn T.

1956-01-01T23:59:59.000Z

232

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

233

HELIUM ISOTOPE COMPOSITION OF FLUID INCLUSIONS HOSTED IN MASSIVE SULFIDES FROM MODERN SUBMARINE HYDROTHERMAL SYSTEMS  

Science Journals Connector (OSTI)

...resistance-heated furnace. Procedural blanks were...inclusions. The crushing efficiency depends on factors such...must be noted that the high-temperature (100...Oomori, T., 1990, Venting of carbon-dioxide-rich...2 orders of magnitude higher than expected for equilibrium...

Volker Lüders; Samuel Niedermann

234

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

235

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

SciTech Connect

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

236

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

237

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

238

Hydrogen isotope fractionation in freshwater and marine algae: II. Temperature and nitrogen limited growth rate effects  

E-Print Network (OSTI)

Hydrogen isotope fractionation in freshwater and marine algae: II. Temperature and nitrogen limited Accepted 7 November 2008 Available online 17 November 2008 a b s t r a c t Zhang and Sachs [Hydrogen. Introduction Hydrogen isotope ratios in plant and algal lipids from sediments are increasingly used

Sachs, Julian P.

239

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

SciTech Connect

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

240

Strontium isotopic variations of Neoproterozoic seawater: Implications for crustal evolution  

SciTech Connect

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

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.


241

SRS upgrades helium recovery system | National Nuclear Security  

NLE Websites -- All DOE Office Websites (Extended Search)

upgrades helium recovery system | National Nuclear Security upgrades helium recovery system | National Nuclear Security Administration Our Mission Managing the Stockpile Preventing Proliferation Powering the Nuclear Navy Emergency Response Recapitalizing Our Infrastructure Continuing Management Reform Countering Nuclear Terrorism About Us Our Programs Our History Who We Are Our Leadership Our Locations Budget Our Operations Media Room Congressional Testimony Fact Sheets Newsletters Press Releases Speeches Events Social Media Video Gallery Photo Gallery NNSA Archive Federal Employment Apply for Our Jobs Our Jobs Working at NNSA Blog Home > NNSA Blog > SRS upgrades helium recovery system SRS upgrades helium recovery system Posted By Office of Public Affairs Savannah River Site (SRS) Tritium Programs recently completed a project to design, build and relocate a new system for separating and capturing

242

Heat Transfer in Liquid Helium below 1 degrees K  

Science Journals Connector (OSTI)

...September 1955 research-article Heat Transfer in Liquid Helium below 1 degrees...is proportional to the specific heat and the diameter of the specimen. Thus the sole mechanism of heat transfer appears to be by phonons which...

1955-01-01T23:59:59.000Z

243

Helium Pumping Wall for a Liquid Lithium Tokamak Richard Majeski...  

NLE Websites -- All DOE Office Websites (Extended Search)

Helium Pumping Wall for a Liquid Lithium Tokamak Richard Majeski This invention is designed to be a subsystem of a device, a tokamak with walls or plasma facing components of...

244

Performance Assessment of a Recuperative Helium Gas Turbine System  

Science Journals Connector (OSTI)

Helium is considered an ideal working fluid for closed cycle gas turbines powered by the heat of nuclear reactors or solar concentrators. Energetic and exergetic based thermodynamic analyses ... applied to an act...

Rami Salah El-Emam; Ibrahim Dincer

2014-01-01T23:59:59.000Z

245

A New Wide Range Equation of State for Helium-4  

E-Print Network (OSTI)

A NEW WIDE RANGE EQUATION OF STATE FOR HELIUM-4 A Dissertation by DIEGO ORLANDO ORTIZ VEGA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR... Copyright 2013Diego Orlando Ortiz Vega ii ABSTRACT A multiparametric and fundamental equation of state is presented for the fluid thermodynamic properties of helium. The equation is valid for temperatures from the ?- line (~2.17 K) to 1500 K...

Ortiz Vega, Diego O

2013-08-01T23:59:59.000Z

246

Process Options for Nominal 2-K Helium Refrigeration System Designs  

SciTech Connect

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

247

A Sr-Isotopic Comparison Between Thermal Waters, Rocks, And Hydrotherm...  

Open Energy Info (EERE)

pre-intrusive metavolcanic and metasedimentary rocks can have considerably higher Sr-isotope ratios (0.7061-0.7246 and 0.7090-0.7250, respectively). Hydrothermally altered...

248

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

E-Print Network (OSTI)

The biologically mediated removal of nitrogen from estuarine and shallow coastal waters was investigated using a new method for the determination of N? isotope ratios. This method employs the use of a chromatographic separation technique to purify...

Downer, Roswell Curtis

2012-06-07T23:59:59.000Z

249

Development of a compact quantum cascade laser spectrometer for field measurements of CO2 isotopes  

Science Journals Connector (OSTI)

We report the development of a field-deployable, pulsed quantum cascade laser spectrometer. The instrument is designed to measure...13C/12C isotopic ratio in the CO2 released from volcanic vents. Specific 12CO2 a...

D. Weidmann; G. Wysocki; C. Oppenheimer; F.K. Tittel

2005-02-01T23:59:59.000Z

250

Isotope effect on the superfluid density in conventional and high-temperature superconductors  

E-Print Network (OSTI)

We investigate the isotope effect on the London penetration depth of a superconductor which measures nS/m* [n subscript s / m superscript asterisk], the ratio of superfluid density to effective mass. We use a simplified ...

Serbyn, Maksym

251

Characterization of uranium isotopic abundances in depleted uranium metal assay standard 115  

Science Journals Connector (OSTI)

Certified reference material (CRM) 115, Uranium (Depleted) Metal (Uranium Assay Standard), was analyzed using a ... TRITON Thermal Ionization Mass Spectrometer to characterize the uranium isotope-amount ratios. T...

K. J. Mathew; G. L. Singleton; R. M. Essex…

2013-04-01T23:59:59.000Z

252

Atomic Spectroscopy and Separated Isotopes  

Science Journals Connector (OSTI)

The advantages in the use of separated isotopes in atomic spectroscopy for the determination of nuclear momentsI ? Q and for studies of the isotope-shift phenomena are discussed. Illustrations of spectra are given for mercury uranium and samarium. In addition a summary is given of twenty-two so-called problem nuclei i.e. those naturally occurring isotopes for which the nuclear moments are completely uncertain. Concluding remarks are made on such problems as the evaluation of the absolute magnitude of isotope shifts the role of “forbidden transitions” in isotope spectra and the potential future value of spectro-isotopic assay techniques.

J. R. McNally Jr.

1952-01-01T23:59:59.000Z

253

High-Precision Measurements of [superscript 33]S and [superscript 34]S Fractionation during SO[subscript 2] Oxidation Reveal Causes of Seasonality in SO[subscript 2] and Sulfate Isotopic Composition  

E-Print Network (OSTI)

This study presents high-precision isotope ratio-mass spectrometric measurements of isotopic fractionation during oxidation of SO[subscript 2] by OH radicals in the gas phase and H[subscript 2]O[subscript 2] and transition ...

Harris, Eliza

254

doi:10.1016/j.gca.2004.12.011 Stable boron isotope fractionation between dissolved B(OH)3 and B(OH)4  

E-Print Network (OSTI)

doi:10.1016/j.gca.2004.12.011 Stable boron isotope fractionation between dissolved B(OH)3 and B; accepted in revised form December 23, 2004) Abstract--The stable boron isotope ratio (11 B/10 B) in marine not provide a constraint on stable boron isotope fractionation. I conclude that in order to anchor

Zeebe, Richard E.

255

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

256

Anomalous isotopic composition of cosmic rays  

SciTech Connect

Recent measurements of nonsolar isotopic patterns for the elements neon and (perhaps) magnesium in cosmic rays are interpreted within current models of stellar nucleosynthesis. One possible explanation is that the stars currently responsible for cosmic-ray synthesis in the Galaxy are typically super-metal-rich by a factor of two to three. Other possibilities include the selective acceleration of certain zones or masses of supernovas or the enhancement of /sup 22/Ne in the interstellar medium by mass loss from red giant stars and planetary nebulas. Measurements of critical isotopic ratios are suggested to aid in distinguishing among the various possibilities. Some of these explanations place significant constraints on the fraction of cosmic ray nuclei that must be fresh supernova debris and the masses of the supernovas involved. 1 figure, 3 tables.

Woosley, S.E.; Weaver, T.A.

1980-06-20T23:59:59.000Z

257

Isotope separation apparatus  

DOE Patents (OSTI)

Isotope separation apparatus consisting of a plurality of cells disposed adjacent to each other in an evacuated container. A common magnetic field is established extending through all of the cells. A source of energetic electrons at one end of the container generates electrons which pass through the cells along the magnetic field lines. Each cell includes an array of collector plates arranged in parallel or in tandem within a common magnetic field. Sets of collector plates are disposed adjacent to each other in each cell. Means are provided for differentially energizing ions of a desired isotope by applying energy at the cyclotron resonant frequency of the desired isotope. As a result, the energized desired ions are preferentially collected by the collector plates.

Arnush, Donald (Rancho Palos Verdes, CA); MacKenzie, Kenneth R. (Pacific Palisades, CA); Wuerker, Ralph F. (Palos Verdes Estates, CA)

1980-01-01T23:59:59.000Z

258

GENERATION OF RADIOXENON ISOTOPES  

SciTech Connect

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

259

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

SciTech Connect

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

260

Isotope Effect of Mercury Diffusion in Air  

Science Journals Connector (OSTI)

Isotope fractionation describes the separation of a reservoir with one isotope composition into “fractions” with different isotope compositions due to small isotopic differences in equilibrium partitioning, rates of mass transfer, or rates of transformation. ... (29) ?202Hg is the value most frequently used to examine mass dependent fractionation of mercury isotopes as 202Hg is the heaviest mercury isotope without significant isobaric interferences. ...

Paul G. Koster van Groos; Bradley K. Esser; Ross W. Williams; James R. Hunt

2013-12-23T23:59:59.000Z

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.


261

THE HELIUM CONTENT OF GLOBULAR CLUSTERS: NGC 6121 (M4)  

SciTech Connect

In the context of the multiple stellar population scenario in globular clusters, helium (He) has been proposed as a key element to interpret the observed multiple main sequences, subgiant branches, and red giant branches, as well as the complex horizontal branch (HB) morphology. In particular, second-generation stars belonging to the bluer part of the HB are thought to be more He-rich ({Delta}Y = 0.03 or more) but also more Na-rich/O-poor than those located in the redder part that should have Y equal to the cosmological value. Up to now this hypothesis was only partially confirmed in NGC 6752, where stars of the redder zero-age HB showed an He content of Y = 0.25 {+-} 0.01, fully compatible with the primordial He content of the universe, and were all Na-poor/O-rich. Here we study hot blue horizontal branch (BHB) stars in the GC NGC 6121 (M4) to measure their He plus O/Na content. Our goal is to complete the partial results obtained for NGC 6752, focusing our attention on targets located on the bluer part of the HB of M4. We observed six BHB stars using the VLT2/UVES spectroscopic facility. Spectra of signal-to-noise ratio {approx} 150 were obtained and the very weak He line at 5875 A measured for all our targets. We compared this feature with synthetic spectra to obtain He abundances. In addition O, Na, and Fe abundances were estimated. Stars turned out to be all Na-rich and O-poor and to have a homogeneous He content with a mean value of Y = 0.29 {+-} 0.01(random) {+-} 0.01(systematic), which is enhanced by {Delta}Y {approx} 0.04 with respect to the most recent measurements of the primordial He content of the universe (Y {approx} 0.24/0.25). The high He content of blue HB stars in M4 is also confirmed by the fact that they are brighter than red HB stars (RHB). Theoretical models suggest the BHB stars are He-enhanced by {Delta}(Y) = 0.02/0.03 with respect to the RHB stars. The whole sample of stars has a metallicity of [Fe/H] = -1.06 {+-} 0.02 (internal error), in agreement with other studies available in the literature. This is a rare direct measurement of the (primordial) He abundance for stars belonging to the Na-rich/O-poor population of GC stars in a temperature regime where the He content is not altered by sedimentation or extreme mixing as suggested for the hottest, late helium flash HB stars. Our results support theoretical predictions that the Na-rich/O-poor population is also more He-rich than the Na-poor/O-rich generation and that a leading contender for the second parameter is the He abundance.

Villanova, S.; Geisler, D. [Departamento de Astronomia, Casilla 160, Universidad de Concepcion (Chile); Piotto, G. [Dipartimento di Astronomia, Universita di Padova, Vicolo dell'Osservatorio 3, I-35122 Padua (Italy); Gratton, R. G., E-mail: svillanova@astro-udec.cl, E-mail: dgeisler@astro-udec.cl, E-mail: giampaolo.piotto@unipd.it, E-mail: raffaele.gratton@oapd.inaf.it [Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova (Italy)

2012-03-20T23:59:59.000Z

262

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

263

David Lee, Douglas Osheroff, Superfluidity, and Helium 3  

NLE Websites -- All DOE Office Websites (Extended Search)

David Lee, Douglas Osheroff, Superfluidity, and Helium 3 David Lee, Douglas Osheroff, Superfluidity, and Helium 3 Resources with Additional Information David M. Lee and Douglas D. Osheroff received the 1996 Nobel Prize in Physics for 'their discovery of superfluidity in helium-3'. "In 1976, Lee shared with Richardson and Osheroff their earliest recognition for studies of superfluidity, the Simon Memorial Prize of the British Physical Society. The Buckley Prize of the American Physical Society followed for the trio in 1981. ... Douglas D. Osheroff Douglas D. Osheroff Courtesy AIP Emilio Segrè Visual Archives, AIP Meggers Gallery of Nobel Laureates David Lee David M. Lee Photo by Janerik Henriksson, Courtesy AIP Emilio Segrè Visual Archievs, W.F. Meggers Gallery of Nobel Laureate From 1966-67, Lee was a visiting scientist at Brookhaven National Laboratory ... ."1 His research at Cornell University includes " Low Temperature Physics: Normal and superfluid 3He, studies of the orientation of solid helium by optical birefringence, solid 3He and 4He, lambda phase diagram of 3He - 4He mixtures, quasiparticle tunneling in superconductors, magnetic resonance and ultrasound techniques, cooling by adiabatic demagnetization and the Pomeranchuk technique, spin waves in spin polarized hydrogen gas, high concentrations of hydrogen and nitrogen atons via matrix isolation by impurity-helium solids, magnetism, electron spin resonance."2

264

Coexistence of superfluid and solid helium in aerogel  

SciTech Connect

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

265

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

266

Strong nuclear force in cold antihydrogen-helium collisions  

SciTech Connect

We calculate cross sections for elastic scattering and annihilation in antihydrogen-helium collisions at low energies. The calculations are based on the Born-Oppenheimer approximation, and incorporate the effects of the strong interaction through a scattering length approach. We find that the strong nuclear force not only causes significant annihilation, but also cannot be neglected in the elastic channel. In the zero energy limit we obtain the scattering length a=-7.69-3.80i a.u. for ground state antihydrogen-helium collisions. Annihilation is found to dominate over elastic scattering up to a temperature about 3 K. Loosely bound metastable antihydrogen-helium states are also investigated, and it is found that a number of relatively long-lived states with up to three units of angular momentum exist.

Jonsell, S. [Department of Physics, Umeaa University, SE-90187 Umeaa (Sweden); Froelich, P.; Eriksson, S. [Department of Quantum Chemistry, Box 518, Uppsala University, SE-75120 Uppsala (Sweden); Strasburger, K. [Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

2004-12-01T23:59:59.000Z

267

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

268

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

269

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

270

Energy Profit Ratio Compared  

SciTech Connect

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

271

Radial characterisation of the helium plasma produced by the axial injection torch (TIA) at atmospheric pressure  

Science Journals Connector (OSTI)

This work presents the radial characterisation of a helium plasma produced by the “Torch à Injection Axiale ... using a collisional-radiative model for helium at atmospheric pressure, the electronic density and e...

R. Álvarez; A. Rodero; M. C. Quintero

2000-03-01T23:59:59.000Z

272

Date: Thursday May 23, 2013 Program: UHV Helium Ion Microscopy HR  

E-Print Network (OSTI)

Date: Thursday May 23, 2013 Program: UHV Helium Ion Microscopy HR Speakers: Gregor Hlawacek Helium selected investigations performed with the UTwente UHV-HIM in the last few years. The actual challenge, why

Twente, Universiteit

273

Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition  

SciTech Connect

An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O{sub 2} plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O{sub 2} plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O{sub 2} (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

Chen Wei; Huang Jun; Wang Xingquan; Lv Guohua; Zhang Guoping [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Du Ning; Liu Xiaodi; Guo Lihong [Department of Oral Biology, Peking University School and Hospital of Stomatology, 100080 Beijing (China); Yang Size [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Aeronautics, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005 (China)

2012-07-01T23:59:59.000Z

274

Effect of helium addition on discharge characteristics in a flat fluorescent lamp  

SciTech Connect

The discharge characteristics of a multielectrode dual coplanar in a mercury-free flat fluorescent lamp were investigated using brightness-efficiency measurement and the infrared (IR) spectrum and intensified charge coupled device (ICCD) characteristics. The level of brightness was above 14 900 cd/m{sup 2} under the conditions of neon--50% xenon-8% He gas composition, 150 Torr pressure, and 20 kHz alternating current pulse. The ICCD results revealed a faster and wider discharge with a Ne-50% Xe-8% He gas composition. The effect of adding helium (He) to Ne-50% Xe revealed a faster peak emission, as confirmed by ICCD images. From the gated IR emission spectrum, the intensity ratio of I{sub 823nm}/I{sub 828nm} was {approx}8% higher with Ne-50% Xe-8% He than with Ne-50% Xe under the same pressure and applied voltage conditions.

Lee, Seong-Eui; Lee, Ho-Nyeon; Park, Hyoung-Bin; Lee, Kyo Sung; Choi, Kyung Cheol [Materials and Devices Research Center, Samsung Advanced Institute of Technology, Suwon 440-600 (Korea, Republic of); Department of Electronics Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Department of Electrical Engineering and Computer Science, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)

2005-11-01T23:59:59.000Z

275

Carbon isotope fractionation in protoplanetary disks  

E-Print Network (OSTI)

We investigate the gas-phase and grain-surface chemistry in the inner 30 AU of a typical protoplanetary disk using a new model which calculates the gas temperature by solving the gas heating and cooling balance and which has an improved treatment of the UV radiation field. We discuss inner-disk chemistry in general, obtaining excellent agreement with recent observations which have probed the material in the inner regions of protoplanetary disks. We also apply our model to study the isotopic fractionation of carbon. Results show that the fractionation ratio, 12C/13C, of the system varies with radius and height in the disk. Different behaviour is seen in the fractionation of different species. We compare our results with 12C/13C ratios in the Solar System comets, and find a stark contrast, indicative of reprocessing.

Paul M. Woods; Karen Willacy

2008-12-01T23:59:59.000Z

276

Composition of saturn's atmosphere at northern temperate latitudes from Voyager iris spectra: NH/sub 3/, PH/sub 3/, C/sub 2/H/sub 2/, C/sub 2/H/sub 6/, CH/sub 3/D, CH/sub 4/, and the saturnian D/H isotopic ratio  

SciTech Connect

The abundances of minor atmospheric constituents at northern Saturnian latitudes have been inferred from infrared emission spectra recorded by Voyager. The NH/sub 3/, PH/sub 3/, C/sub 2/H/sub 2/, and C/sub 2/H/sub 6/ vertical distributions have been determined from spectra selected in a cloud-free region centered approximately at the latitude of the Voyager 2 radio-occultation point (36.5 N). The NH/sub 3/ mixing ratio in the upper troposphere is found to be compatible with the saturated partial pressure. The inferred PH/sub 3//H/sub 2/ ratio of 1.4 +- 0.8 x 10/sup -6/ is higher than the value derived from the solar P/H ratio, and the PH/sub 3/ vertical profile may extend somewhat into the stratosphere, up to a few millibars. The stratospheric C/sub 2/H/sub 2//H/sub 2/ and C/sub 2/H/sub 6//H/sub 2/ ratios are, respectively, 2.1 +- 1.4 x 10/sup -7/ and 3.0 x 1.1 x 10/sup -6/; the latter decreases sharply below the 20-50 mbar level. A larger selection of spectra yields CH/sub 3/D/H/sub 2/ = 3.9 +- 2.5 x 10/sup -7/ and CH/sub 4//H/sub 2/ = 4.5/sup +2.4//sub -1.9/ x 10/sup -3/. This result implies an enrichment of Saturn's upper atmosphere is carbon by at least a factor of 3 over the solar abundance. The D/H value resulting from our CH/sub 3/D/CH/sub 4/ ratio is 1.6/sup +1.3//sub -1.2/ x 10/sup -5/, significantly lower than previous determinations obtained from HD lines; it is also less than half of the IRIS-inferred Jovian value. Finally, the interpretation of two NH/sub 3/ lines in the 5 ..mu..m window suggests a NH/sub 3/H/sub 2/ ratio at the 2 bar level below the solar value.

Courtin, R.; Gautier, D.; Marten, A.; Bezard, B.; Hanel, R.

1984-12-15T23:59:59.000Z

277

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

278

Isotopes in Environmental and Health Studies Vol. 41, No. 4, December 2005, 293302  

E-Print Network (OSTI)

deployable quantum cascade laser-based sensor is described, along with line selection strategy for 13/12CO2 sensors; IR spectrometry; Natural isotope ratios; Volcanoes 1. Introduction Tunable laser absorption for the detection of low gas concentra- tion levels by improving the signal-to-noise ratio of the spectrometer

279

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

280

Heat Transfer Between Solids and Liquid Helium II  

Science Journals Connector (OSTI)

...February 1961 research-article Heat Transfer Between Solids and Liquid Helium...According to this author, the transfer of heat from the solid surface to the...least, some other mechanism of heat transfer may be involved. The Royal Society...

1961-01-01T23:59:59.000Z

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.


281

Thermonuclear .Ia Supernovae from Helium Shell Detonations: Explosion Models and Observables  

Science Journals Connector (OSTI)

During the early evolution of an AM Canum Venaticorum system, helium is accreted onto the surface of a white dwarf under conditions suitable for unstable thermonuclear ignition. The turbulent motions induced by the convective burning phase in the He envelope become strong enough to influence the propagation of burning fronts and may result in the onset of a detonation. Such an outcome would yield radioactive isotopes and a faint rapidly rising thermonuclear ".Ia" supernova. In this paper, we present hydrodynamic explosion models and observable outcomes of these He shell detonations for a range of initial core and envelope masses. The peak UVOIR bolometric luminosities range by a factor of 10 (from 5 ? 1041 to 5 ? 1042 erg s–1), and the R-band peak varies from M R,peak = –15 to –18. The rise times in all bands are very rapid (40Ca through 56Ni) and unburnt He. Thus, the spectra around peak light lack signs of intermediate-mass elements and are dominated by Ca II and Ti II features, with the caveat that our radiative transfer code does not include the nonthermal effects necessary to produce He features.

Ken J. Shen; Dan Kasen; Nevin N. Weinberg; Lars Bildsten; Evan Scannapieco

2010-01-01T23:59:59.000Z

282

Comparisons between stable isotope tr  

Science Journals Connector (OSTI)

Nitrogen spiraling in streams: Comparisons between stable isotope tracer and nutrient addition experiments. Abstract—A common method to quantify stream.

2007-05-31T23:59:59.000Z

283

Depletion of heavy isotopes of oxygen and hydrogen in tissue water of intertidal plants: implications for water economy  

Science Journals Connector (OSTI)

Stable oxygen and hydrogen isotope ratios of leaf and thallus water of the intertidal seagrasses Phyllospadix scouleri and P. torreyi and the marine algae Egregia menziesii, Gelidium coulteri, and Corallina vanco...

L. W. Cooper; M. J. DeNiro

1989-05-01T23:59:59.000Z

284

High-Resolution Triple Resonance Autoionization of Uranium Isotopes  

SciTech Connect

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

285

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.

286

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

287

Advanced isotope separation  

SciTech Connect

The Study Group briefly reviewed the technical status of the three Advanced Isotope Separation (AIS) processes. It also reviewed the evaluation work that has been carried out by DOE's Process Evaluation Board (PEB) and the Union Carbide Corporation-Nuclear Division (UCCND). The Study Group briefly reviewed a recent draft assessment made for DOE staff of the nonproliferation implications of the AIS technologies. The staff also very briefly summarized the status of GCEP and Advanced Centrifuge development. The Study Group concluded that: (1) there has not been sufficient progress to provide a firm scientific, technical or economic basis on which to select one of the three competing AIS processes for full-scale engineering development at this time; and (2) however, should budgetary restraints or other factors force such a selection, we believe that the evaluation process that is being carried out by the PEB provides the best basis available for making a decision. The Study Group recommended that: (1) any decisions on AIS processes should include a comparison with gas centrifuge processes, and should not be made independently from the plutonium isotope program; (2) in evaluating the various enrichment processes, all applicable costs (including R and D and sales overhead) and an appropriate discounting approach should be included in order to make comparisons on a private industry basis; (3) if the three AIS programs continue with limited resources, the work should be reoriented to focus only on the most pressing technical problems; and (4) if a decision is made to develop the Atomic Vapor Laser Isotope Separation process, the solid collector option should be pursued in parallel to alleviate the potential program impact of liquid collector thermal control problems.

Not Available

1982-05-04T23:59:59.000Z

288

" Column: Energy-Consumption Ratios;"  

U.S. Energy Information Administration (EIA) Indexed Site

" Level: National Data; " " Row: Values of Shipments within NAICS Codes;" " Column: Energy-Consumption Ratios;" " Unit: Varies." ,,,,"Consumption" ,,,"Consumption","per...

289

Iron Isotope Biosignatures  

Science Journals Connector (OSTI)

...Michigan and an Archean sample from the Sudan Mine in...ratios of transition metals (5). Thermal...Michigan and an Archean sample from the Sudan Mine in Minnesota. 56Fe values of...

Brian L. Beard; Clark M. Johnson; Lea Cox; Henry Sun; Kenneth H. Nealson; Carmen Aguilar

1999-09-17T23:59:59.000Z

290

Isotope Development & Production | Nuclear Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

of the "Calutrons" (electromagnetic enrichment devices) were converted by ORNL to the separation and enrichment of stable isotopes and some actinide isotopes. Until 1998 when...

291

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

SciTech Connect

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

292

On the Origin of the Lightest Molybdenum Isotopes  

SciTech Connect

We discuss implications of recent precision measurements for the {sup 93}Rh proton separation energy for the production of the lightest molybdenum isotopes in proton-rich type II supernova ejecta. It has recently been shown that a novel neutrino-induced process makes these ejecta a promising site for the production of the light molybdenum isotopes and other 'p-nuclei' with atomic mass near 100. The origin of these isotopes has long been uncertain. A distinguishing feature of nucleosynthesis in neutrino-irradiated outflows is that the relative production of {sup 92}Mo and {sup 94}Mo is set by a competition governed by the proton separation energy of {sup 93}Rh. We use detailed nuclear network calculations and the recent experimental results for this proton separation energy to place constraints on the outflow characteristics that produce the lightest molybdenum isotopes in their solar proportions. It is found that for the conditions calculated in recent two-dimensional supernova simulations, and also for a large range of outflow characteristics around these conditions, the solar ratio of {sup 92}Mo to {sup 94}Mo cannot be achieved. This suggests that either proton-rich winds from type II supernova do not exclusively produce both isotopes, or that these winds are qualitatively different than calculated in today's supernova models.

Fisker, J L; Hoffman, R D; Pruet, J

2007-10-24T23:59:59.000Z

293

Implications of Fast Reactor Transuranic Conversion Ratio  

SciTech Connect

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

294

First decay study of the very neutron-rich isotope 93Br  

Science Journals Connector (OSTI)

The decay of the mass-separated, very neutron-rich isotope 93Br has been studied by ? spectroscopy. A level scheme of its daughter 93Kr has been constructed. Level energies, ?-ray branching ratios, and multipolarities suggest spins and parities which are in accord with a smooth systematics of the N=57 isotones for Z<~40, suggesting the N=56 subshell closure still to be effective in Kr isotopes. So far, there is no indication of a progressive onset of deformation in neutron-rich Kr isotopes.

G. Lhersonneau; A. Wöhr; B. Pfeiffer; K.-L. Kratz; the ISOLDE Collaboration

2001-02-20T23:59:59.000Z

295

ISOTOPE FRACTIONATION Isotopes are atoms whose nuclei contain the same number of protons but a different number of neutrons. The  

E-Print Network (OSTI)

the most abundant isotope appears in the denominator: b R = b E / a E (stable boron isotopes = , [ ] [ ] [ ] [ ]OOCOOC2 OOCOOC2 O 16181616 16181818 CO 18 2 + + = . The isotopic composition, , of a sample, determined____________________________ ISOTOPE FRACTIONATION ____________________________ Isotopes are atoms

Zeebe, Richard E.

296

Theoretical investigation of thermophysical properties in two-temperature argon-helium thermal plasma  

Science Journals Connector (OSTI)

The thermophysical properties of argon-helium thermal plasma have been studied in the temperature range from 5000 to 40 000 K at atmospheric pressure in local thermodynamic equilibrium and non-local thermodynamic equilibrium conditions. Two cases of thermal plasma considered are (i) ground state plasma in which all the atoms and ions are assumed to be in the ground state and (ii) excited stateplasma in which atoms and ions are distributed over various possible excited states. The influence of electronic excitation and non-equilibrium parameter ??=?Te/Th on thermodynamic properties (composition degree of ionization Debye length enthalpy and total specific heat) and transport properties(electrical conductivity electron thermal conductivity and thermal diffusion ratio) have been studied. Within the framework of Chapman-Enskog method the higher-order contributions to transport coefficient and their convergence are studied. The influence of different molar compositions of argon-helium plasma mixture on convergence of higher-orders is investigated. Furthermore the effect of different definitions of Debye length has also been examined for electrical conductivity and it is observed that electrical conductivity with the definition of Debye length (in which only electrons participate in screening) is less than that of the another definition (in which both the electrons and ions participate in screening) and this deviation increases with electron temperature. Finally the effect of lowering of ionization energy is examined on electron number density Debye length and higher-order contribution to electrical conductivity. It is observed that the lowering of the ionization energy affects the electron transport-properties and consequently their higher-order contributions depending upon the value of the non-equilibrium parameter ?.

Rohit Sharma; Gurpreet Singh; Kuldip Singh

2011-01-01T23:59:59.000Z

297

Theoretical investigation of thermophysical properties in two-temperature argon-helium thermal plasma  

SciTech Connect

The thermophysical properties of argon-helium thermal plasma have been studied in the temperature range from 5000 to 40 000 K at atmospheric pressure in local thermodynamic equilibrium and non-local thermodynamic equilibrium conditions. Two cases of thermal plasma considered are (i) ground state plasma in which all the atoms and ions are assumed to be in the ground state and (ii) excited state plasma in which atoms and ions are distributed over various possible excited states. The influence of electronic excitation and non-equilibrium parameter {theta} = T{sub e}/T{sub h} on thermodynamic properties (composition, degree of ionization, Debye length, enthalpy, and total specific heat) and transport properties (electrical conductivity, electron thermal conductivity, and thermal diffusion ratio) have been studied. Within the framework of Chapman-Enskog method, the higher-order contributions to transport coefficient and their convergence are studied. The influence of different molar compositions of argon-helium plasma mixture on convergence of higher-orders is investigated. Furthermore, the effect of different definitions of Debye length has also been examined for electrical conductivity and it is observed that electrical conductivity with the definition of Debye length (in which only electrons participate in screening) is less than that of the another definition (in which both the electrons and ions participate in screening) and this deviation increases with electron temperature. Finally, the effect of lowering of ionization energy is examined on electron number density, Debye length, and higher-order contribution to electrical conductivity. It is observed that the lowering of the ionization energy affects the electron transport-properties and consequently their higher-order contributions depending upon the value of the non-equilibrium parameter {theta}.

Sharma, Rohit; Singh, Kuldip [Department of Physics, Guru Nanak Dev University, Amritsar (India); Singh, Gurpreet [Department of Physics, DAV College, Bathinda (India)

2011-08-15T23:59:59.000Z

298

IMPROVEMENTS OF HELIUM LIQUEFACTION/REFRIGERATION PLANTS AND APPLICATIONS  

Science Journals Connector (OSTI)

Design features for a new range of helium liquefiers and refrigerators with capacities ranging from 30 to 280 l/h of liquid helium (LHe) and 100 to 900 Watt respectively. The latest He cold box development shows an increased efficiency due to improved turbine and heat exchanger design. Other benefits of the new design include short cool-down times and a very compact design which offers better flexibility and process control. The modularity of the system was designed in order to cover a wide range of applications like sophisticated shield cooling at different temperature levels or simultaneous operation modes for He liquefaction and refrigeration purposes. The presentation will highlight the individual improvements in the design.

K.-H. Berdais; H. Wilhelm; Th. Ungricht

2008-01-01T23:59:59.000Z

299

Elastic Electron Scattering from Tritium and Helium-3  

DOE R&D Accomplishments (OSTI)

The mirror nuclei of tritium and helium-3 have been studied by the method of elastic electron scattering. Absolute cross sections have been measured for incident electron energies in the range 110 - 690 MeV at scattering angles lying between 40 degrees and 135 degrees in this energy range. The data have been interpreted in a straightforward manner and form factors are given for the distributions of charge and magnetic moment in the two nuclei over a range of four-momentum transfer squared 1.0 - 8.0 F{sup -2}. Model-independent radii of the charge and magnetic moment distributions are given and an attempt is made to deduce form factors describing the spatial distribution of the protons in tritium and helium-3.

Collard, H.; Hofstadter, R.; Hughes, E. B.; Johansson, A.; Yearian, M. R.; Day, R. B.; Wagner, R. T.

1964-10-00T23:59:59.000Z

300

Coefficients of the second viscosity in bulk liquid helium  

Science Journals Connector (OSTI)

The coefficients of the second viscosity in bulk liquid helium are evaluated explicitly as a function of temperature via interactions between the anomalous excitation spectrums. The four coefficients of the second viscosity exhibit a T-1 dependence at low temperatures (well below 0.6 K), which is due to three-phonon processes originating from the anomalous dispersion at very low momenta and temperatures.

Chung-In Um; Chul-Won Jun; Thomas F. George

1992-09-01T23:59:59.000Z

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,
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We encourage you to perform a real-time search of NLEBeta
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301

An Experimental Study of the Effects of Solid-to-Coolant Thermal Conductivity Ratio in Helium-Cooled Divertor Modules  

Science Journals Connector (OSTI)

Test Blanket, Fuel Cycle, and Breeding / Proceedings of the Twentieth Topical Meeting on the Technology of Fusion Energy (TOFE-2012) (Part 2) Nashville, Tennessee, August 27-31, 2012

B. H. Mills; J. D. Rader; D. L. Sadowski; M. Yoda; S. I. Abdel-Khalik

302

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

303

Multiple reheat helium Brayton cycles for sodium fast reactors  

SciTech Connect

Sodium fast reactors (SFR) traditionally adopt the steam Rankine cycle for power conversion. The resulting potential for water-sodium reaction remains a continuing concern which at least partly delays the SFR technology commercialization and is a contributor to higher capital cost. Supercritical CO2 provides an alternative, but is also capable of sustaining energetic chemical reactions with sodium. Recent development on advanced inert-gas Brayton cycles could potentially solve this compatibility issue, increase thermal efficiency, and bring down the capital cost close to light water reactors. In this paper, helium Brayton cycles with multiple reheat and intercooling states are presented for SFRs with reactor outlet temperatures in the range of 510°C to 650°C. The resulting thermal efficiencies range from 39% and 47%, which is comparable with supercritical recompression CO2 cycles (SCO2 cycle). A systematic comparison between multiple reheat helium Brayton cycle and the SCO2 cycle is given, considering compatibility issues, plant site cooling temperature effect on plant efficiency, full plant cost optimization, and other important factors. The study indicates that the multiple reheat helium cycle is the preferred choice over SCO2 cycle for sodium fast reactors.

Haihua Zhao; Per F. Peterson

2008-07-01T23:59:59.000Z

304

Mathematical modeling of a Fermilab helium liquefier coldbox  

SciTech Connect

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

305

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

306

Activities of Pu and Am Isotopes and Isotopic Ratios in a Soil Contaminated by Weapons-Grade Plutonium  

Science Journals Connector (OSTI)

The Radiation Division of the Surveillance Directorate for the U.S. Air Force Institute for Environment, Safety and Occupational Health Risk Analysis collected soil samples at the BOMARC site in June, 2000. ... with a mean value of 0.19, which is close to the value reported from the BOMARC WGP contaminated soil (6) and the Rocky Flats WGP contaminated soil (27). ...

M. H. Lee; S. B. Clark

2005-06-28T23:59:59.000Z

307

ARM - Measurement - Backscatter depolarization ratio  

NLE Websites -- All DOE Office Websites (Extended Search)

govMeasurementsBackscatter depolarization ratio govMeasurementsBackscatter depolarization ratio ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Backscatter depolarization ratio The ratio of cross polarized to co-polarized elastic backscatter. Categories Aerosols Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments HSRL : High Spectral Resolution Lidar RL : Raman Lidar Field Campaign Instruments HSRL : High Spectral Resolution Lidar MIRAI : JAMSTEC Research Vessel Mirai MPL-AIR : Micropulse Lidar- Airborne

308

Isotopic Analysis- Rock | Open Energy Information  

Open Energy Info (EERE)

Isotopic Analysis- Rock Isotopic Analysis- Rock Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Isotopic Analysis- Rock Details Activities (13) Areas (11) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Lab Analysis Techniques Exploration Sub Group: Rock Lab Analysis Parent Exploration Technique: Rock Lab Analysis Information Provided by Technique Lithology: Water rock interaction Stratigraphic/Structural: Hydrological: Thermal: Dictionary.png Isotopic Analysis- Rock: Isotopes are atoms of the same element that have different numbers of neutrons. An isotopic analysis looks at a particular isotopic element(s) in a given system, while the conditions which increase/decrease the number of neutrons are well understood and measurable.

309

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

310

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

SciTech Connect

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

311

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

312

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

313

The Mg isotope composition of presolar silicate grains from red giant stars  

Science Journals Connector (OSTI)

Abstract We report O and Mg isotope compositions of presolar silicate grains which likely formed around asymptotic giant branch stars. Our grains represent the most abundant Mg-rich presolar grain group and their Mg isotope composition provides thus far missing information about the contribution of isotopically anomalous presolar dust to the Mg isotope inventory of the early Solar System. Presolar silicate grains were identified in situ, using the NanoSIMS, in the matrix of the ungrouped carbonaceous chondrite Acfer 094. O isotope compositions suggest that the presolar grains of the present study formed in the stellar winds of low mass (M ? ?2.2 × Msolar) red giant or asymptotic giant branch stars of close-to-solar metallicity and thus belong to the most abundant presolar silicate grain group. In order to minimise matrix contributions during spatially poorly resolved Mg isotope analyses (spatial resolution comparable to average grain size), meteorite matrix in the presolar grains’ vicinity was removed using a focussed Ga ion beam. To monitor accuracy, we prepared and analysed O-isotopically regular (Solar System) matrix grains the same way as the presolar grains. The 25Mg/24Mg ratios of all seven successfully analysed presolar silicate grains are identical to that of the Solar System at the precision of our measurements. The 26Mg/24Mg ratios of five grains are also solar but two grains have significant positive anomalies in 26Mg/24Mg. On average, however, 25Mg/24Mg and 26Mg/24Mg ratios are higher than solar by a few %. All grain compositions are consistent with Galactic chemical evolution and, possibly, isotope fractionation caused by interstellar or Solar System processing (sputtering and/or recondensation). The grain with the strongest enrichment in 26Mg relative to 25Mg (?25Mg = 34 ± 25‰, ?26Mg = 127 ± 25‰; where ?xMg = 1000 × [(xMg/24Mg)grain/(xMg/24Mg)meteorite matrix) ? 1] with x = 25 or 26; the reported uncertainty corresponds to 1 ?), probably incorporated 26Al during grain condensation. Our and previously reported Mg isotope data on presolar oxide and silicate grains indicate that the isotopically anomalous O-rich dust component of the Solar System’s parent molecular cloud was heterogeneous with respect to Mg isotope compositions and probably had a higher 26Mg/24Mg ratio on average than that of the present-day Solar System.

János Kodolányi; Peter Hoppe; Elmar Gröner; Christoph Pauly; Frank Mücklich

2014-01-01T23:59:59.000Z

314

Strontium Isotope Study of Coal Untilization By-products Interacting with Environmental Waters  

SciTech Connect

Sequential leaching experiments on coal utilization by-products (CUB) were coupled with chemical and strontium (Sr) isotopic analyses to better understand the influence of coal type and combustion processes on CUB properties and the release of elements during interaction with environmental waters during disposal. Class C fly ash tended to release the highest quantity of minor and trace elements—including alkaline earth elements, sodium, chromium, copper, manganese, lead, titanium, and zinc—during sequential extraction, with bottom ash yielding the lowest. Strontium isotope ratios ({sup 87}Sr/{sup 86}Sr) in bulk-CUB samples (total dissolution of CUB) are generally higher in class F ash than in class C ash. Bulk-CUB ratios appear to be controlled by the geologic source of the mineral matter in the feed coal, and by Sr added during desulfurization treatments. Leachates of the CUB generally have Sr isotope ratios that are different than the bulk value, demonstrating that Sr was not isotopically homogenized during combustion. Variations in the Sr isotopic composition of CUB leachates were correlated with mobility of several major and trace elements; the data suggest that arsenic and lead are held in phases that contain the more radiogenic (high-{sup 87}Sr/{sup 86}Sr) component. A changing Sr isotope ratio of CUB-interacting waters in a disposal environment could forecast the release of certain strongly bound elements of environmental concern. This study lays the groundwork for the application of Sr isotopes as an environmental tracer for CUB–water interaction.

Spivak-Birndorf, Lev J; Stewart, Brian W; Capo, Rosemary C; Chapman, Elizabeth C; Schroeder, Karl T; Brubaker, Tonya M

2011-09-01T23:59:59.000Z

315

Gas-chromatographische Bestimmung von Wasserstoff bei Verwendung von Helium als Trägergas  

Science Journals Connector (OSTI)

Die bei dem Trägergas Helium zuweilen auftretenden M-förmigen Wasserstoffpeaks lassen sich durch Vergrößern oder Verkleinern des Probenvolumens in eine auswertbare Form bringen.

Holm Pauschmann

1964-01-01T23:59:59.000Z

316

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

SciTech Connect

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

317

Atmospheric Pressure Helium Plasma Jet with Different Types of Discharge Setup  

Science Journals Connector (OSTI)

New techniques are demonstrated to generate cold plasma inside the glass capillary and hollow optical fiber. The plasma jet is generated using helium gas and experiments are carried...

Hosseinzadeh Kassani, Sahar; Lee, Changyoung; Yoon, Changsik; Choi, Honggu; Oh, Kyunghwan

318

Atmospheric-Pressure Helium Inductively Coupled Plasmas for Elemental Mass Spectrometry  

Science Journals Connector (OSTI)

Analytical and fundamental characteristics of helium inductively coupled plasma mass spectrometry (He ICPMS) were explored for atmospheric-pressure plasmas generated in a 13-mm He...

Zhang, Hao; Nam, Sang-Ho; Cai, Mingxiang; Montaser, Akbar

1996-01-01T23:59:59.000Z

319

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

NLE Websites -- All DOE Office Websites (Extended Search)

SERVICES FOR THE NEXT GENERATION NUCLEAR PLANT (NGNP) WITH HYDROGEN PRODUCTION Test Plan for Helium Circulators (PHTS, SCS, SHTS) Prepared by General Atomics For the...

320

Onboard Hydrogen/Helium Sensors in Support of the Global Technical...  

NLE Websites -- All DOE Office Websites (Extended Search)

Onboard HydrogenHelium Sensors in Support of the Global Technical Regulation: An Assessment of Performance in Fuel Cell Electric Vehicle Crash Tests Matthew B. Post, Robert...

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

Handheld isotope identification system  

DOE Patents (OSTI)

A portable radiation detector using a high-purity germanium crystal as the sensing device. The crystal is fabricated such that it exhibits a length to width ratio greater than 1:1 and is oriented within the detector to receive radiation along the width of said crystal. The crystal is located within a container pressurized with ultra-pure nitrogen, and the container is located within a cryostat under vacuum.

Frankle, Christen M. (Los Alamos, NM); Becker, John A. (Alameda, CA); Cork,; Christopher P. (Pleasant Hill, CA); Madden, Norman W. (Livermore, CA)

2007-01-09T23:59:59.000Z

322

E-Print Network 3.0 - abundance ratio measurements Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

1997. Figure 2 shows the helium to proton abundance ra- tio as a function... the largest solar cycle helium to proton abundance ... Source: Richardson, John - Kavli Institute for...

323

6:1 aspect ratio silicon pillar based thermal neutron detector filled with B 10  

Science Journals Connector (OSTI)

Current helium-3 tube based thermal neutrondetectors have shortcomings in achieving simultaneously high efficiency and low voltage while maintaining adequate fieldability performance. By using a three-dimensional silicon p - i - n diode pillar array filled with boron-10 these constraints can be overcome. The fabricated pillar structured detector reported here is composed of 2 ? m diameter silicon pillars with a 4 ? m pitch and height of 12 ? m . A thermal neutrondetection efficiency of 7.3 + ? ? 0.6 % and a neutron-to-gamma discrimination of 10 5 at 2 V reverse bias were measured for this detector. When scaled to larger aspect ratio a high efficiency device is possible.

R. J. Nikoli?; A. M. Conway; C. E. Reinhardt; R. T. Graff; T. F. Wang; N. Deo; C. L. Cheung

2008-01-01T23:59:59.000Z

324

Automated data extraction from in situ protein stable isotope...  

NLE Websites -- All DOE Office Websites (Extended Search)

data extraction from in situ protein stable isotope probing studies. Automated data extraction from in situ protein stable isotope probing studies. Abstract: Protein stable isotope...

325

Copper isotope fractionation in acid mine drainage. | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

Copper isotope fractionation in acid mine drainage. Copper isotope fractionation in acid mine drainage. Abstract: We surveyed the Cu isotopic composition of primary minerals and...

326

Isotope production facility produces cancer-fighting actinium  

NLE Websites -- All DOE Office Websites (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...

327

Development of Particle Induced Gamma-Ray Emission Methods for Nondestructive Determination of Isotopic Composition of Boron and Its Total Concentration in Natural and Enriched Samples  

Science Journals Connector (OSTI)

Development of Particle Induced Gamma-Ray Emission Methods for Nondestructive Determination of Isotopic Composition of Boron and Its Total Concentration in Natural and Enriched Samples ... The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to 10B and 11B of samples to natural boric acid standard. ...

Sumit Chhillar; Raghunath Acharya; Suparna Sodaye; Pradeep K. Pujari

2014-10-14T23:59:59.000Z

328

Helium Refrigerator Design for Pulsed Heat Load in Tokamaks  

SciTech Connect

Nuclear fusion reactors of the Tokamak type will be operated in a pulsed mode requiring the helium refrigerator to remove periodically large heat loads in time steps of approximately one hour. What are the necessary steps for a refrigerator to cope with such load variations?A series of numerical simulations has been performed indicating the possibility of an active refrigerator control with low exergetic losses. A basic comparison is made between the largest existing refrigerator sizes and the size required to service for example the ITER requirements.

Kuendig, A.; Schoenfeld, H. [Linde Kryotechnik AG, Dattlikonerstrasse 5, CH-8422 Pfungen (Switzerland)

2006-04-27T23:59:59.000Z

329

Cathode fall measurement in a dielectric barrier discharge in helium  

SciTech Connect

A method based on the “zero-length voltage” extrapolation is proposed to measure cathode fall in a dielectric barrier discharge. Starting, stable, and discharge-maintaining voltages were measured to obtain the extrapolation zero-length voltage. Under our experimental conditions, the “zero-length voltage” gave a cathode fall of about 185 V. Based on the known thickness of the cathode fall region, the spatial distribution of the electric field strength in dielectric barrier discharge in atmospheric helium is determined. The strong cathode fall with a maximum field value of approximately 9.25 kV/cm was typical for the glow mode of the discharge.

Hao, Yanpeng; Zheng, Bin; Liu, Yaoge [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)] [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

2013-11-15T23:59:59.000Z

330

Radiative Lifetimes of Some Electronic States of Helium  

Science Journals Connector (OSTI)

In this paper we describe our measurements of the radiative lifetimes of the 3 3 P 3 3 D 4 1 D and 4 3 D electronic states of helium using a low-energy positive ion accelerator. The lifetimes in nanoseconds are 3 3 P?(111±5) 3 3 D?(14±3) 4 1 D?(34±4) and 4 3 D?(32±1) . In addition we discuss the desirability and feasibility of introducing undergraduates to this type of research.

Stanley A. Chin-Bing; Charles E. Head; Albert E. Green Jr.

1970-01-01T23:59:59.000Z

331

A pencil beam algorithm for helium ion beam therapy  

SciTech Connect

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

332

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

333

Isotopic Analysis of Uranium in NIST SRM Glass by Femtosecond Laser Ablation  

SciTech Connect

We employed femtosecond Laser Ablation Multicollector Inductively Coupled Mass Spectrometry for the 11 determination of uranium isotope ratios in a series of standard reference material glasses (NIST 610, 612, 614, and 12 616). This uranium concentration in this series of SRM glasses is a combination of isotopically natural uranium in 13 the materials used to make the glass matrix and isotopically depleted uranium added to increase the uranium 14 elemental concentration across the series. Results for NIST 610 are in excellent agreement with literature values. 15 However, other than atom percent 235U, little information is available for the remaining glasses. We present atom 16 percent and isotope ratios for 234U, 235U, 236U, and 238U for all four glasses. Our results show deviations from the 17 certificate values for the atom percent 235U, indicating the need for further examination of the uranium isotopes in 18 NIST 610-616. Our results are fully consistent with a two isotopic component mixing between the depleted 19 uranium spike and natural uranium in the bulk glass.

Duffin, Andrew M.; Hart, Garret L.; Hanlen, Richard C.; Eiden, Gregory C.

2013-05-19T23:59:59.000Z

334

The effect of helium nano-bubbles on the structures stability and electronic properties of palladium tritides: a density functional theory study  

Science Journals Connector (OSTI)

...effect of helium nano-bubbles on the structures stability and electronic properties...found to contain helium gas bubbles. The stability of metal tritides decreases...The effects of helium bubbles on metal tritides are clearly...

2014-01-01T23:59:59.000Z

335

Further experiments with liquid helium. C. On the change of electric resistance of pure metals at very low temperatures etc. IV. The resistance of pure mercury at helium temperatures  

Science Journals Connector (OSTI)

Since the appearance of the last Communication dealing with liquid helium temperatures (December 1910) liquid helium has been succesfully transferred from the apparatus in which it was liquefied to another ves...

H. Kamerlingh Onnes

1991-01-01T23:59:59.000Z

336

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

337

Ignition and extinction phenomena in helium micro hollow cathode discharges  

SciTech Connect

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

338

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

2007-02-25T23:59:59.000Z

339

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

340

Technical Report No.7, Investigation of radon and helium as possible fluid-phase precursors to earthquakes. Technical Report No. 2, Additional task: Radon, helium and geochemical monitoring on the Palmdale uplift.  

E-Print Network (OSTI)

Imperial Valley) HELIUM AND All with RADON IN WELL SAMPLES of the wells in the Southern Network are geothermal

Craig, H; Lupton, J E; Chung, Y; Horowitz, R M

1977-01-01T23:59:59.000Z

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

Low temperature carrier transport properties in isotopically controlled germanium  

SciTech Connect

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

342

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

343

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.

344

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

345

Cryogenic (<20 K) helium cooling mitigates radiation damage to protein crystals  

Science Journals Connector (OSTI)

Comparison of diffraction data collected from matched protein crystals bathed in helium at a set temperature of 8 K and nitrogen at 100 K indicate that the use of cryogenic helium can increase the diffractive lifetime of crystals and measurably mitigate radiation damage.

Chinte, U.

2007-03-16T23:59:59.000Z

346

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

SciTech Connect

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

347

Kinematics of the ultra-compact helium accretor AM Canum Venaticorum  

E-Print Network (OSTI)

We report on the results from a five-night campaign of high-speed spectroscopy of the 17-minute binary AM Canum Venaticorum, obtained with the 4.2-m William Herschel Telescope on La Palma. We derive a mass ratio q=0.18+/-0.01 for AM CVn, which is significantly higher than the value found in previous, less direct measurements. We discuss the implications for AM CVn's evolutionary history and show that a helium star progenitor scenario is strongly favoured. We further discuss the implications for the interpretation of AM CVn's superhump behaviour, and for the detectability of its gravitational-wave signal with LISA. Finally, we test the predictions of an eccentric, precessing disc that are based on AM CVn's observed superhump behaviour. We limit the effective eccentricity in the outermost part of the disc, where the resonances that drive the eccentricity are thought to occur, to e=0.04+/-0.01, which is smaller than previous models indicated.

G. H. A. Roelofs; P. J. Groot; G. Nelemans; T. R. Marsh; D. Steeghs

2006-06-13T23:59:59.000Z

348

Comparison Between Air and Helium for Use as Working Fluids in the Energy-Conversion Cycle of the MPBR  

E-Print Network (OSTI)

A comparison between air and helium for use as working fluids in the energy-conversion cycle of the MPBR is presented. To date, helium has been selected in the MPBR indirect-cycle working reference design. Air open- and ...

Galen, T. A.

349

Helium Refrigerator Liquid Nitrogen Pre-Cooler Component Parameter Sensitivity Analysis  

SciTech Connect

For helium refrigerators using liquid nitrogen (LN) pre-cooling it is not uncommon for the ambient helium refrigeration return stream(s) exiting the cold box to be significantly colder and for the cycle to use more nitrogen than estimated by the process studies. Often there is an emphasis on the length of 300 to 80-K helium-nitrogen heat exchangers to ensure the exiting nitrogen is as close to ambient as possible. However, it is really the size and flow distribution of the 300 to 80-K helium-helium heat exchangers which are the dominate influence of the nitrogen consumption. As such, an analysis was done to identify and quantify the sensitivity the key parameters in the refrigerator LN pre-cooler section affecting the LN consumption.

Peter Knudsen, Venkatarao Ganni

2010-04-01T23:59:59.000Z

350

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

351

AVLIS enrichment of medical isotopes  

SciTech Connect

Under the Sponsorship of the United states Enrichment Corporation (USEC), we are currently investigating the large scale separation of several isotopes of medical interest using atomic vapor isotope separation (AVLIS). This work includes analysis and experiments in the enrichment of thallium 203 as a precursor to the production of thallium 201 used in cardiac imaging following heart attacks, on the stripping of strontium 84 from natural strontium as precursor to the production of strontium 89, and on the stripping of lead 210 from lead used in integrated circuits to reduce the number of alpha particle induced logic errors.

Haynam, C.A.; Scheibner, K.F.; Stern, R.C.; Worden, E.F. [Lawrence Livermore National Laboratory, CA (United States)

1996-12-31T23:59:59.000Z

352

The Transformation of the Nitrogen Isotope of Mass 15 into Carbon and Helium by Bombardment with Protons  

Science Journals Connector (OSTI)

...proton width of the maximum is 250 eV. Extrapolation of the one-level dispersion formula, together with the theory of thermonuclear reactions, gives a lifetime of 3 10 years for N in the sun. A photographic method of determining the angular distribution...

1949-01-01T23:59:59.000Z

353

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

354

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

355

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

356

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

DOE Data Explorer (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.

357

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

358

30TH INTERNATIONAL COSMIC RAY CONFERENCE Isotopic composition of cosmic-ray sources  

E-Print Network (OSTI)

solar composition. Introduction CR source abundances are normally derived using the leaky the energy- dependence of the secondary/primary ratios, and this will also affect the derivation of source Autónoma de México, Mexico City, Mexico, 2008 Vol. 2 (OG part 1), pages 129­132 ID 738 129 #12;ISOTOPIC

Moskalenko, Igor V.

359

Stable isotope patterns found in early Eocene equid tooth rows of North America: Implications for reproductive behavior and paleoclimate  

Science Journals Connector (OSTI)

Abstract Reproductive behaviors of early Eocene equids were likely different from their modern-day counterparts as a result of their small body size and warmer global temperatures. To better understand the paleoenvironment and ecology of these early horses, teeth of Protorohippus montanum jaws from a single stratigraphic locality in early Eocene sedimentary deposits of Wyoming were sampled for oxygen and carbon isotope analysis. These enamel data along with an inferred body mass of ~ 7.5 kg suggests that adult teeth formed over a matter of months, with the final tooth erupting at ~ 1.3 years of age. Thus, average isotopic values from each tooth likely represent environmental conditions from a single season. Results indicate two isotopic patterns. In the case of isotopic “pattern A,” the second forming molars (m/2s) have significantly lower isotopic ratios compared to other teeth within the jaw. This suggests the first forming molars (m/1s) formed during a cooling fall season, followed by formation of the m/2s during the cooler winter. In the case of isotopic “pattern B,” results suggest that m/1s formed during a warming spring season, while the m/2s formed during the following warmer summer season. Isotopic ratios of m/1s may represent an individual's birth season (or in utero season, depending on timing of initial formation), implying that early equids experienced at least two birth seasons per year. These results suggest that temperatures and reduced seasonality of the early Eocene played a strong role in early equid birth cycles. Lastly, the mean and variance in carbon and oxygen isotope ratios was not significantly different across tooth positions of all jaws when all individuals were grouped together, regardless of their pattern assignment. Such results indicate that isotopic data from fourth premolars, first molars, second molars, and third molars can be combined for purposes of temporal reconstructions of paleoclimate, thus increasing the potential sample sizes for these types of studies.

Abigail R. D’Ambrosia; William C. Clyde; Henry C. Fricke; Amy E. Chew

2014-01-01T23:59:59.000Z

360

Respiration, photosynthesis, and oxygen isotope fractionation in ...  

Science Journals Connector (OSTI)

Jan 25, 1971 ... Respiration, photosynthesis, and oxygen isotope fractionation in oceanic surface water1. Peter M. Kroopnick. Department of Oceanography,.

2000-01-04T23:59:59.000Z

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.


361

Magnesium Isotope Effects in Enzymatic Phosphorylation  

Science Journals Connector (OSTI)

So far as magnesium isotope effect in phosphorylation is an unexpected and unusual phenomenon, it is worthy to shortly describe materials and technologies used in isotopic biochemical experiments. ... Isotope-containing MgCl2 samples were obtained using treatment of magnesium oxides 24MgO, 25MgO, 26MgO, and *MgO with analytically pure HCl (*Mg means magnesium with natural abundance of the three isotopes; see Table 1). ...

Anatoly L. Buchachenko; Dmitry A. Kouznetsov; Natalia N. Breslavskaya; Marina A. Orlova

2008-02-05T23:59:59.000Z

362

Magnetic Isotope Effect in the Photolysis of Organotin Compounds  

Science Journals Connector (OSTI)

Fractionation of isotopes in chemical and biochemical reactions is induced by two isotope effects; their origin and physical nature are shown in Figure 1. ... The classical isotope effect (CIE) sorts isotopic nuclei on their masses; the magnetic isotope effect (MIE) demonstrates nuclear spin selectivity of reactions and separates isotopic nuclei according to their magnetic moments.1 ...

Anatoly L. Buchachenko; Vladimir L. Ivanov; Vitaly A. Roznyatovsky; Yuri A. Ustynyuk

2006-03-02T23:59:59.000Z

363

Photo-oxidation of Water by Molecular Oxygen: Isotope Exchange and Isotope Effects  

Science Journals Connector (OSTI)

In order to detect the reaction, we used water highly enriched with isotopes 17O and 18O, controlling the isotope composition of molecular oxygen before and after reaction. ... stability of heavy-isotope clumps'; slower kinetics of reactions requiring the breakage of bonds between heavy isotopes; the mass dependence of diffusive and thermo-gravitational fractionations; mixing between components that differ from one another in bulk isotopic compn.; biochem. ... Study of oxygen three-isotope behavior during thermal decompn. of naturally occurring carbonates of calcium and magnesium in vacuo revealed that, surprisingly, anomalous isotopic compns. ...

Anatoly L. Buchachenko; Elena O. Dubinina

2011-03-30T23:59:59.000Z

364

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

SciTech Connect

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

365

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

366

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice  

Science Journals Connector (OSTI)

...turn, shift the global delta13CH4 and deltaD-CH4...for natural gas (coal, thermogenic or...Ledru2001Correlations of char coal records of fires...Ward1993Methane production from global biomass burning...Wuebbles2000Radiative forcings and global warming potentials of 39...

2007-01-01T23:59:59.000Z

367

Laser Ablation Inductively Coupled Plasma Mass Spectrometry Measurement of Isotope Ratios in Depleted Uranium Contaminated Soils  

Science Journals Connector (OSTI)

Laser ablation of pressed soil pellets was examined as a means of direct sample introduction to enable inductively coupled plasma mass spectrometry (ICP-MS) screening of soils for...

Seltzer, Michael D

2003-01-01T23:59:59.000Z

368

Stable Carbon Isotope Ratios of Rock Varnish Organic Matter: A New Paleoenvironmental Indicator  

Science Journals Connector (OSTI)

...gross envir( regimes (desert, semiarid, or humid...Timna Valley, Negev Desert (Israel) *Searles...Peninsula) east margin Salt Springs, Mojave Desert, California Piedmont...changes, with desert scrub ich feasibeing replaced...

RONALD I. DORN; MICHAEL J. DENIRO

1985-03-22T23:59:59.000Z

369

Ratios of Carbon Isotopes in Microbial Lipids as an Indicator of Substrate Usage  

Science Journals Connector (OSTI)

...For this, a systematic investigation of the discrimination of...However, no systematic investigation was conducted on the degree...Pritchard P. H. Effect of remedial nitrogen applications on...For this, a systematic investigation of the discrimination of...

Wolf-Rainer Abraham; Christian Hesse; Oliver Pelz

1998-11-01T23:59:59.000Z

370

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

E-Print Network (OSTI)

18. Science, Vol. 203, Tachikawa, K. , and H. Elderfield, (B, respectively, from Tachikawa and Elderfield 2002 (Figuresat CD113A sites A and B (Tachikawa and Elderfield, 2002;

Harper, Dustin T.; Harper, Dustin T.

2012-01-01T23:59:59.000Z

371

Envera Variable Compression Ratio Engine  

SciTech Connect

Aggressive engine downsizing, variable compression ratio and use of the Atkinson cycle are being combined to improve fuel economy by up to 40 percent relative to port fuel injected gasoline engines, while maintaining full engine power. Approach Engine downsizing is viewed by US and foreign automobile manufacturers as one of the best options for improving fuel economy. While this strategy has already demonstrated a degree of success, downsizing and fuel economy gains are currently limited. With new variable compression ratio technology however, the degree of engine downsizing and fuel economy improvement can be greatly increased. A small variable compression ratio (VCR) engine has the potential to return significantly higher vehicle fuel economy while also providing high power. Affordability and potential for near term commercialization are key attributes of the Envera VCR engine. VCR Technology To meet torque and power requirements, a smaller engine needs to do more work per stroke. This is typically accomplished by boosting the incoming charge with either a turbo or supercharger so that more energy is present in the cylinder per stroke to do the work. With current production engines the degree of engine boosting (which correlates to downsizing) is limited by detonation (combustion knock) at high boost levels. Additionally, the turbo or supercharger needs to be responsive and efficient while providing the needed boost. VCR technology eliminates the limitation of engine knock at high load levels by reducing compression ratio to {approx}9:1 (or whatever level is appropriate) when high boost pressures are needed. By reducing the compression ratio during high load demand periods there is increased volume in the cylinder at top dead center (TDC) which allows more charge (or energy) to be present in the cylinder without increasing the peak pressure. Cylinder pressure is thus kept below the level at which the engine would begin to knock. When loads on the engine are low the compression ratio can be raised (to as much as 18:1) providing high engine efficiency. It is important to recognize that for a well designed VCR engine cylinder pressure does not need to be higher than found in current production turbocharged engines. As such, there is no need for a stronger crankcase, bearings and other load bearing parts within the VCR engine. The Envera VCR mechanism uses an eccentric carrier approach to adjust engine compression ratio. The crankshaft main bearings are mounted in this eccentric carrier or 'crankshaft cradle' and pivoting the eccentric carrier 30 degrees adjusts compression ratio from 9:1 to 18:1. The eccentric carrier is made up of a casting that provides rigid support for the main bearings, and removable upper bearing caps. Oil feed to the main bearings transits through the bearing cap fastener sockets. The eccentric carrier design was chosen for its low cost and rigid support of the main bearings. A control shaft and connecting links are used to pivot the eccentric carrier. The control shaft mechanism features compression ratio lock-up at minimum and maximum compression ratio settings. The control shaft method of pivoting the eccentric carrier was selected due to its lock-up capability. The control shaft can be rotated by a hydraulic actuator or an electric motor. The engine shown in Figures 3 and 4 has a hydraulic actuator that was developed under the current program. In-line 4-cylinder engines are significantly less expensive than V engines because an entire cylinder head can be eliminated. The cost savings from eliminating cylinders and an entire cylinder head will notably offset the added cost of the VCR and supercharging. Replacing V6 and V8 engines with in-line VCR 4-cylinder engines will provide high fuel economy at low cost. Numerous enabling technologies exist which have the potential to increase engine efficiency. The greatest efficiency gains are realized when the right combination of advanced and new technologies are packaged together to provide the greatest gains at the least cost. Aggressive engine downsiz

Charles Mendler

2011-03-15T23:59:59.000Z

372

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

373

Options for Cryogenic Load Cooling with Forced Flow Helium Circulation  

SciTech Connect

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

374

Friction-Induced Fluid Heating in Nanoscale Helium Flows  

SciTech Connect

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

375

Design of oilfree all turbo-type helium refrigerator  

Science Journals Connector (OSTI)

We have designed a high efficient, compact 300 W oilfree all turbo-type heliumrefrigerator capable of long maintenance free continuous operation. The main compressor at ambient temperature which is driven by a helium gas turbine attached to the same shaft, is supported by magnetic bearings, and, has an inlet and outlet pressure of 0.35 \\{MPa\\} and 0.7 MPa. Four turbo expanders are employed, including one at 80 K because LN2 is not used in this system. Each expander drives a cold compressor, accompanying a generator brake by use of an induction motor. This provides very easy control. Variable nozzles are adopted to the expanders, and the number of valves are diminished as much as possible to reduce line pressure loss. Concerning a heat exchanger, we have examined a micro tube laminar flow heat exchanger which is compact and enables high efficiency at low temperature. This heat exchanger can reduce pressure loss greatly.

N. Saji; S. Nagai; H. Asakura; Y. Kaneko

1994-01-01T23:59:59.000Z

376

Equation of state and optical properties of warm dense helium  

Science Journals Connector (OSTI)

We investigate the physical properties of warm dense helium under the conditions found in the atmospheres of cool white dwarfs using both a chemical model and ab initio simulations. A chemical model is developed for the low-ionization limit that includes the species He, He+, He2+, and electrons, and interactions between them. The ab initio calculations consist in quantum molecular dynamics (QMD) simulations. We use the generalized gradient approximation (GGA) to calculate the equation of state and the electrical and optical properties within the linear response theory. We further use an exact exchange hybrid (PBE0) density functional as well as the GW approximation to estimate the uncertainties on the electrical and optical properties resulting from the GGA approximation. While both the chemical model and the QMD simulations are in excellent agreement with the measured equation of state, a qualitative discrepancy exists with the measured conductivity.

P. M. Kowalski, S. Mazevet, D. Saumon, and M. Challacombe

2007-08-10T23:59:59.000Z

377

The Role of Helium in the Outer Solar Atmosphere  

Science Journals Connector (OSTI)

We construct models of the outer solar atmosphere comprising the region from the mid-chromosphere and into the solar wind in order to study the force and energy balance in models with a significant helium abundance. The corona is created by dissipation of an energy flux from the Sun. The energy flux is lost as radiation from the top of the chromosphere and as gravitational and kinetic solar wind energy flux. We find that in models with significant ion heating of the extended corona most of the energy flux is lost in the solar wind. The ion temperatures are higher than the electron temperature in these models, and the ?-particle temperature is much higher than the proton temperature, so there is energy transfer from the ?-particle fluid to the protons and electrons, but this energy exchange between the different species is relatively small. To a fairly good approximation we can say that the energy flux deposited in the protons and ?-particles is lost as kinetic and gravitational energy flux in the proton and ?-particle flow. How this energy flux is divided between gravitational and kinetic energy flux (i.e., how large the particle fluxes and flow speeds are) depends upon details of the heating process. We also find that mixing processes in the chromosphere play an important role in determining the coronal helium abundance and the relative solar wind proton and ?-particle fluxes. Roughly speaking, we find that the relative ?-particle and proton fluxes are set by the degree of chromospheric mixing, while the speeds are set by the details of the coronal heating process.

V. H. Hansteen; E. Leer; T.

1997-01-01T23:59:59.000Z

378

Isotope Evidence for Ozone Formation on Surfaces  

Science Journals Connector (OSTI)

Remarkably, the gas-phase recombination or association reaction of ozone has an unusually large (?10%) isotope effect and shows almost equal enrichments of the ozone molecules containing two different oxygen isotopes. ... For a better understanding of the pressure and temperature dependence of ozone isotopic composition in oxygen discharges, we developed a relatively simple isotope kinetic model that accounts for the processes of (i) heterogeneous ozone formation at the reactor walls, (ii) isotope exchange of oxygen atoms with O2 molecules, and (iii) ozone formation in the gas phase. ...

Christof Janssen; Béla Tuzson

2010-05-06T23:59:59.000Z

379

Magnesium-Isotope Fractionation During Plant Growth  

Science Journals Connector (OSTI)

With three stable isotopes naturally abundant (24Mg, 78.992%; 25Mg, 10.003%; 26Mg, 11.005%), magnesium stable isotope fractionation may provide insights into these cycles. ... Measurements of the magnesium isotopic composition of chlorophylls, seeds, shoots, roots, leaves, exudates, and the limiting nutrient solution over time show that the plant appears to establish an isotopic equilibrium with the nutrient available to it and that the plant (in particular, the seeds and exudates) becomes enriched in the heavy isotopes of magnesium in a mass-dependent relationship as the plant reaches maturity. ...

Jay R. Black; Emanuel Epstein; William D. Rains; Qing-zhu Yin; William H. Casey

2008-10-01T23:59:59.000Z

380

Slow Neutron Scattering by the Titanium Isotopes  

Science Journals Connector (OSTI)

Neutron diffraction studies are reported on isotopically enriched samples of TiO2 from which are evaluated the coherent scattering amplitudes of the titanium isotopes. Scattering amplitudes of +0.48, +0.33, -0.58, +0.08, and +0.55×10-12 cm were established for the titanium isotopes of mass 46, 47, 48, 49, and 50, respectively. The major isotope Ti48 is thus responsible for the anomalous scattering amplitude, -0.34×10-12 cm, characteristic of the normal element. Pronounced nuclear scattering resonance effects on the observed neutron scattering are suggested to occur for most of the isotopes.

C. G. Shull; M. K. Wilkinson; M. H. Mueller

1960-05-01T23:59:59.000Z

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.


381

Isotope Effects in Isotope-Exchange Reactions:? Evidence for a Large 12C/13C Kinetic Isotope Effect in the Gas Phase  

Science Journals Connector (OSTI)

Isotope effects are key to understanding reaction mechanisms because isotopic substitution affects reaction rates and equilibrium constants. ... These values are considered in relation to the vapor pressures of isotopic compds., the geologic abundance of C and O isotopes, the relative abundance of O isotopes in air and H2O, and variations in the at. ...

Giulia de Petris; Anna Troiani

2008-03-05T23:59:59.000Z

382

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

SciTech Connect

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

383

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

SciTech Connect

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

384

The effect of a micro bubble dispersed gas phase on hydrogen isotope transport in liquid metals under nuclear irradiation  

E-Print Network (OSTI)

The present work intend to be a first step towards the understanding and quantification of the hydrogen isotope complex phenomena in liquid metals for nuclear technology. Liquid metals under nuclear irradiation in,e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles. Other liquid metal systems of a nuclear reactor involve hydrogen isotope absorption processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption into gas bubbles modelling and control may have a capital importance regarding design, operation and safety. Here general models for hydrogen isotopes transport in liquid metal and absorption into gas phase, that do not depend on the mass transfer limiting regime, are exposed and implemented in OpenFOAMR CFD tool for 0D to 3D simulations. Results for a 0D case show the impact of a He dispersed phase of na...

Fradera, Jorge

2013-01-01T23:59:59.000Z

385

Definition: Isotopic Analysis- Rock | Open Energy Information  

Open Energy Info (EERE)

Isotopic Analysis- Rock Isotopic Analysis- Rock Jump to: navigation, search Dictionary.png Isotopic Analysis- Rock Isotopes are atoms of the same element that have different numbers of neutrons. An isotopic analysis looks at a particular isotopic element(s) in a given system, while the conditions which increase/decrease the number of neutrons are well understood and measurable.[1] View on Wikipedia Wikipedia Definition References ↑ http://wwwrcamnl.wr.usgs.gov/isoig/isopubs/itchch2.html Ret LikeLike UnlikeLike You like this.Sign Up to see what your friends like. rieved from "http://en.openei.org/w/index.php?title=Definition:Isotopic_Analysis-_Rock&oldid=687702" Category: Definitions What links here Related changes Special pages Printable version Permanent link Browse properties

386

50 years of helium liquefaction at the MIT Cryogenic Engineering Laboratory  

Science Journals Connector (OSTI)

The evolution of the helium liquefaction facility of the MIT Cryogenic Engineering Laboratory and the history of its operation over the last 50 years are described. Professor Samuel C. Collins created the liquid-helium facility based on his earlier developments. The chronology of the laboratory helium liquefiers is given with a brief description of each one. The current facility based on the Model 2000 liquefier is described and operating experience is given. The reasons for the very high availability of the liquefaction system are developed.

Joseph L. Smith Jr.

2002-01-01T23:59:59.000Z

387

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

SciTech Connect

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

388

Laser-driven nanoplasmas in doped helium droplets: Local ignition and anisotropic expansion  

E-Print Network (OSTI)

Doping a helium nanodroplet with a tiny xenon cluster of a few atoms only, sparks complete ionization of the droplet at laser intensities below the ionization threshold of helium atoms. As a result, the intrinsically inert and transparent droplet turns into a fast and strong absorber of infrared light. Microscopic calculations reveal a two-step mechanism to be responsible for the dramatic change: Avalanche-like ionization of the helium atoms on a femtosecond time scale, driven by field ionization due to the quickly charged xenon core is followed by resonant absorption enabled by an unusual cigar-shaped nanoplasma within the droplet.

Mikaberidze, Alexey; Rost, Jan M

2009-01-01T23:59:59.000Z

389

Laser-Driven Nanoplasmas in Doped Helium Droplets: Local Ignition and Anisotropic Growth  

Science Journals Connector (OSTI)

Doping a helium nanodroplet with only a tiny xenon cluster of a few atoms sparks complete ionization of the droplet at laser intensities below the ionization threshold of helium atoms. As a result, the intrinsically inert and transparent droplet turns into a fast and strong absorber of infrared light. Microscopic calculations reveal a two-step mechanism to be responsible for the dramatic change: Avalanchelike ionization of the helium atoms on a femtosecond time scale, driven by field ionization due to the quickly charged xenon core, is followed by resonant absorption enabled by an unusual cigar-shaped nanoplasma within the droplet.

Alexey Mikaberidze, Ulf Saalmann, and Jan M. Rost

2009-03-25T23:59:59.000Z

390

Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems  

SciTech Connect

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

391

Weather-Corrected Performance Ratio  

SciTech Connect

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

392

Observations of nitrogen isotope fractionation in deeply embedded protostars  

E-Print Network (OSTI)

(Abridged) The terrestrial planets, comets, and meteorites are significantly enriched in 15N compared to the Sun and Jupiter. While the solar and jovian nitrogen isotope ratio is believed to represent the composition of the protosolar nebula, a still unidentified process has caused 15N-enrichment in the solids. Several mechanisms have been proposed to explain the variations, including chemical fractionation. However, observational results that constrain the fractionation models are scarce. While there is evidence of 15N-enrichment in prestellar cores, it is unclear how the signature evolves into the protostellar phases. Our aim is to measure the 14N/15N ratio around three nearby, embedded low-to-intermediate-mass protostars. Isotopologues of HCN and HNC were used to probe the 14N/15N ratio. A selection of H13CN, HC15N, HN13C, and H15NC transitions was observed with the APEX telescope. The 14N/15N ratios were derived from the integrated intensities assuming a standard 12C/13C ratio. The assumption of optically...

Wampfler, S F; Bizzarro, M; Bisschop, S E

2014-01-01T23:59:59.000Z

393

Isotopic Composition of Light Nuclei in Cosmic Rays: Results from AMS-01  

Science Journals Connector (OSTI)

The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper, we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be), and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.

M. Aguilar; J. Alcaraz; J. Allaby; B. Alpat; G. Ambrosi; H. Anderhub; L. Ao; A. Arefiev; L. Arruda; P. Azzarello; M. Basile; F. Barao; G. Barreira; A. Bartoloni; R. Battiston; R. Becker; U. Becker; L. Bellagamba; J. Berdugo; P. Berges; B. Bertucci; A. Biland; V. Bindi; G. Boella; M. Boschini; M. Bourquin; G. Bruni; M. Buénerd; J. D. Burger; W. J. Burger; X. D. Cai; P. Cannarsa; M. Capell; D. Casadei; J. Casaus; G. Castellini; I. Cernuda; Y. H. Chang; H. F. Chen; H. S. Chen; Z. G. Chen; N. A. Chernoplekov; T. H. Chiueh; Y. Y. Choi; F. Cindolo; V. Commichau; A. Contin; E. Cortina-Gil; D. Crespo; M. Cristinziani; T. S. Dai; C. dela Guia; C. Delgado; S. Di Falco; L. Djambazov; I. D'Antone; Z. R. Dong; M. Duranti; J. Engelberg; F. J. Eppling; T. Eronen; P. Extermann; J. Favier; E. Fiandrini; P. H. Fisher; G. Flügge; N. Fouque; Y. Galaktionov; M. Gervasi; F. Giovacchini; P. Giusti; D. Grandi; O. Grimm; W. Q. Gu; S. Haino; K. Hangarter; A. Hasan; V. Hermel; H. Hofer; W. Hungerford; M. Ionica; M. Jongmanns; K. Karlamaa; W. Karpinski; G. Kenney; D. H. Kim; G. N. Kim; K. S. Kim; T. Kirn; A. Klimentov; R. Kossakowski; A. Kounine; V. Koutsenko; M. Kraeber; G. Laborie; T. Laitinen; G. Lamanna; G. Laurenti; A. Lebedev; C. Lechanoine-Leluc; M. W. Lee; S. C. Lee; G. Levi; C. H. Lin; H. T. Liu; G. Lu; Y. S. Lu; K. Lübelsmeyer; D. Luckey; W. Lustermann; C. Maña; A. Margotti; F. Mayet; R. R. McNeil; M. Menichelli; A. Mihul; A. Mujunen; S. Natale; A. Oliva; F. Palmonari; M. Paniccia; H. B. Park; W. H. Park; M. Pauluzzi; F. Pauss; R. Pereira; E. Perrin; A. Pevsner; F. Pilo; M. Pimenta; V. Plyaskin; V. Pojidaev; M. Pohl; N. Produit; L. Quadrani; P. G. Rancoita; D. Rapin; D. Ren; Z. Ren; M. Ribordy; E. Riihonen; J. Ritakari; S. Ro; U. Roeser; R. Sagdeev; D. Santos; G. Sartorelli; P. Saouter; C. Sbarra; S. Schael; A. Schultz von Dratzig; G. Schwering; E. S. Seo; J. W. Shin; E. Shoumilov; V. Shoutko; T. Siedenburg; R. Siedling; D. Son; T. Song; F. R. Spada; F. Spinella; M. Steuer; G. S. Sun; H. Suter; X. W. Tang; Samuel C. C. Ting; S. M. Ting; N. Tomassetti; M. Tornikoski; J. Torsti; J. Trümper; J. Ulbricht; S. Urpo; E. Valtonen; J. Vandenhirtz; E. Velikhov; B. Verlaat; I. Vetlitsky; F. Vezzu; J. P. Vialle; G. Viertel; D. Vité; H. Von Gunten; S. Waldmeier Wicki; W. Wallraff; J. Z. Wang; K. Wiik; C. Williams; S. X. Wu; P. C. Xia; S. Xu; Z. Z. Xu; J. L. Yan; L. G. Yan; C. G. Yang; J. Yang; M. Yang; S. W. Ye; H. Y. Zhang; Z. P. Zhang; D. X. Zhao; F. Zhou; Y. Zhou; G. Y. Zhu; W. Z. Zhu; H. L. Zhuang; A. Zichichi; B. Zimmermann; P. Zuccon

2011-01-01T23:59:59.000Z

394

Fusion reactions with germanium isotopes  

Science Journals Connector (OSTI)

Measurements of the fusion of 16O and 27Al with a series of germanium isotopes are analyzed within a coupled-channels approach. It is found that couplings based interactions that are linear in the deformation amplitudes are insufficient in reproducing the data. In order to obtain reasonable fits, it is necessary also to include couplings based on quadratic interactions. The analysis suggests that the nuclear radius of 72Ge is significantly smaller than predicted from a smooth interpolation between other germanium isotopes. The large prolate deformation of 74Ge, which has been proposed as the preferred solution to measurements of the quadrupole moment of the 2+ state, is not supported by the analysis; the near spherical solution is more likely.

H. Esbensen

2003-09-04T23:59:59.000Z

395

On the mechanism of electromagnetic microwave absorption in superfluid helium  

SciTech Connect

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

396

Direct Detection of Vacuum Ultraviolet Radiation for Nonmetal Determinations with a Helium Microwave-Induced Plasma  

Science Journals Connector (OSTI)

A study of the determination of metals, nonmetals, and metalloids (F, Cl, Br, I, S, P, Se, As, Sb, and Pb) in the vacuum-ultraviolet spectral region with a kilowatt-plus helium...

Alvarado, Jorge; Carnahan, Jon W

1993-01-01T23:59:59.000Z

397

High-frequency two-photon ionization of helium and cesium  

Science Journals Connector (OSTI)

Calculations of the two-photon ionization of metastable levels of helium and the first three s levels of cesium are presented. The calculations are carried out to second order in a...

Marinescu, M; Sadeghpour, H R; Dalgarno, A

1993-01-01T23:59:59.000Z

398

Modeling the point-spread function in helium-ion lithography  

E-Print Network (OSTI)

We present here a hybrid approach to modeling helium-ion lithography that combines the power and ease-of-use of the Stopping and Range of Ions in Matter (SRIM) software with the results of recent work simulating secondary ...

Winston, Donald

399

Development of Small Size Claude Cycle Helium Refrigerator with Micro Turbo-Expander  

Science Journals Connector (OSTI)

In the field of small size helium refrigerators, need for a maintenance free and vibration free system is rapidly increasing, especially for the application to cryoelectronic devices such as NMR-CT and Josephs...

H. Izumi; S. Harada; K. Matsubara; S. Saito

1986-01-01T23:59:59.000Z

400

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

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

Conception design of helium ion FFAG accelerator with induction accelerating cavity  

E-Print Network (OSTI)

In the recent decades of particle accelerator R&D area, fixed field alternating gradient (FFAG) accelerator has become a highlight for some advantages of its higher beam intensity and lower cost, although there are still some technical challenges. In this paper, FFAG accelerator is adopted to accelerate helium ion beam on the one hand for the study of helium embrittlement on fusion reactor envelope material and on the other hand for promoting the conception research and design of FFAG accelerator and exploring the possibility of developing high power FFAG accelerators. The conventional period focusing unit of helium ion FFAG accelerator and three-dimensional model of the large aperture combinatorial magnet by OPERA-TOSCA are given. For low energy and low revolution frequency, induction acceleration is proposed to replace conventional radio frequency(RF) acceleration for helium ion FFAG accelerator, which avoids the potential breakdown of acceleration field caused by wake field and improves the acceleratio...

Huan-li, Luo; Xiang-qi, Wang; Hong-Liang, Xu

2013-01-01T23:59:59.000Z

402

CONDITIONS FOR SUCCESSFUL HELIUM DETONATIONS IN ASTROPHYSICAL ENVIRONMENTS  

SciTech Connect

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

403

Nuclear Energy Protocol for Research Isotopes Owen Lowe  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Protocol for Protocol for Research Isotopes Owen Lowe Office of Isotopes for Medicine and Science Office of Nuclear Energy, Science and Technology April 16, 2002 Isotopes for Life Isotopes for Life Isotopes for Life Office of Nuclear Energy, Science and Technology Lowe/April16_02 NEPRI to NERAC.ppt (2) Nuclear Energy Protocol For Research Isotopes Nuclear Energy Protocol For Research Isotopes Why NEPRI? 6 NEPRI implements DOE funding priorities for fiscal year 2003 6 NEPRI will * Bring order to DOE's responses to requests for research isotopes * Introduce a high-quality peer review to the selection of research isotopes * Enable DOE to concentrate on operating its unique isotope production facilities Isotopes for Life Isotopes for Life Isotopes for Life Office of Nuclear Energy, Science and Technology

404

Diameters of Single-Wall Carbon Nanotubes Depending on Helium Gas Pressure in an Arc Discharge  

Science Journals Connector (OSTI)

Diameters of Single-Wall Carbon Nanotubes Depending on Helium Gas Pressure in an Arc Discharge ... So far, relatively large quantities of SWNTs have been produced by using Y?Ni and Fe?Ni catalysts for the electric arc discharge method28-30 and by using a Co?Ni catalyst for the pulsed laser ablation method. ... The electric current of the arc discharge also affected the yield of SWNTs though its effect was not as serious as the helium pressure. ...

Yahachi Saito; Yoshihiko Tani; Atsuo Kasuya

2000-02-26T23:59:59.000Z

405

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

SciTech Connect

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

406

Discrete Visible Luminescence of Helium Atoms and Molecules Desorbing from Helium Clusters: The Role of Electronic, Vibrational, and Rotational Energy Transfer  

SciTech Connect

Discrete visible and near-infrared luminescence of a beam of photoexcited helium clusters is reported. The emission lines are attributed to free helium atoms and molecules desorbing from clusters in electronically excited states. Depending on the excitation energy, various atomic and molecular singlet and triplet states are involved in the relaxation process. With increasing cluster size the intensity of molecular transitions becomes dominant. The temperature of ejected molecules could be estimated to T{sub vib}{approximately}2500 K and T{sub rot}{approximately}450 K and is much higher than that of the cluster itself. {copyright} {ital 1997} {ital The American Physical Society}

von Haeften, K.; von Pietrowski, R.; Moeller, T. [Hamburger Synchrotronstrahlungslabor HASYLAB Deutsches Elektronen Synchroton DESY, Hamburg, Notkestr. 85, 22603 Hamburg (Germany)] [Hamburger Synchrotronstrahlungslabor HASYLAB Deutsches Elektronen Synchroton DESY, Hamburg, Notkestr. 85, 22603 Hamburg (Germany); Joppien, M.; Moussavizadeh, L. [II. Institute fuer Experimentalphysik, Universitaet Hamburg (Germany)] [II. Institute fuer Experimentalphysik, Universitaet Hamburg (Germany); de Castro, A.R. [Laboratorio National de Luz Sincrotron, Campinas 13081-90 (Brazil)] [Laboratorio National de Luz Sincrotron, Campinas 13081-90 (Brazil)

1997-06-01T23:59:59.000Z

407

Strategic Isotope Production | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Strategic Isotope Strategic Isotope Production SHARE Strategic Isotope Production Typical capsules used in the transport of 252Cf source material inside heavily shielded shipping casks. ORNL's unique facilities at the High Flux Isotope Reactor (HFIR), Radiochemical Engineering Development Center (REDC), Irradiated Fuels Examination Laboratory (IFEL), and Irradiated Materials Examination Testing facility (IMET) are routinely used in the production, purification, packaging, and shipping of a number of isotopes of national importance, including: 75Se, 63Ni, 238Pu, 252Cf, and others. The intense neutron flux of the HFIR (2.0 x 1015 neutrons/cm²·s) permits the rapid formation of such isotopes. These highly irradiated materials are then processed and packaged for shipping using the facilities at the REDC, IFEL, and IMET.

408

Electromagnetic Isotope Separation Lab (EMIS) | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Electromagnetic Isotope Separation Lab Electromagnetic Isotope Separation Lab May 30, 2013 ORNL established the Stable Isotope Enrichment Laboratory (SIEL) as part of a project funded by the DOE Office of Science, Nuclear Physics Program to develop a modernized electromagnetic isotope separator (EMIS), optimized for separation of a wide range of stable isotopes. The SIEL is located in the Building 6010 Shield Test Station, space formerly allocated to the Oak Ridge Electron Linear Accelerator, on the main campus of ORNL. ORNL staff have designed and built a nominal 10 mA ion current EMIS (sum of all isotopes at the collector) in the SIEL. This EMIS is currently being tested to determine basic performance metrics such as throughput and enrichment factor per pass. This EMIS unit and space will be used to

409

Magnesium isotope fractionation between brucite [Mg(OH)2] and Mg aqueous species: Implications for silicate weathering and biogeochemical processes  

Science Journals Connector (OSTI)

Abstract Brucite, with its octahedral structure, has a lattice configuration that is similar to the Mg-bearing octahedral layers in phyllosilicates. Understanding stable Mg isotope fractionation between brucite and aqueous solution therefore bears on interpretation of Mg isotope data in natural weathering systems. In this study, we experimentally determined Mg isotope fractionation between brucite and two Mg aqueous species, the free Mg aquo ion ([Mg(OH2)6]2+) and EDTA-bonded Mg (Mg-EDTA2?). Results from recrystallization and brucite synthesis experiments suggest mild preferential partitioning of light Mg isotopes into brucite compared to Mg aquo ions at low temperatures, where measured ? Mg brucite - Mg 2 + 26 fractionation increased from ca. ? 0.3 ‰ at 7?°C, to ca. ? 0.2 ‰ at 22?°C, to ca. 0‰ at 40?°C. MgO hydrolysis experiments in EDTA-bearing solutions suggest that the ? Mg brucite - Mg - EDTA 26 fractionation is ? + 2.0 ‰ at 22?°C, indicating that light Mg isotopes strongly partition into Mg-EDTA complex relative to brucite, as well as relative to Mg aquo ions. Magnesium atoms in brucite, Mg aquo ions, and Mg-EDTA complexes are all octahedrally coordinated, and the measured Mg isotope fractionations correlate with average bond lengths for Mg. Aqueous Mg ions have the shortest bond length among the three phases, and enrich heavy Mg isotopes relative to brucite and Mg-EDTA. In contrast, Mg-EDTA has the longest average bond length for Mg, and enriches light Mg isotopes relative to Mg aquo ions and brucite; the relatively long Mg-EDTA bond suggests that organically bound Mg may commonly have low 26Mg/24Mg ratios, which may explain proposed “vital” effects for stable Mg isotopes. Such relations between bond length and Mg isotope fractionation could be extended to other phyllosilicates such as serpentine- and clay-group minerals where Mg is also octahedrally coordinated.

Weiqiang Li; Brian L. Beard; Chengxiang Li; Clark M. Johnson

2014-01-01T23:59:59.000Z

410

A DEEPLY ECLIPSING DETACHED DOUBLE HELIUM WHITE DWARF BINARY  

SciTech Connect

Using Liverpool Telescope+RISE photometry we identify the 2.78 hr period binary star CSS 41177 as a detached eclipsing double white dwarf binary with a 21,100 K primary star and a 10,500 K secondary star. This makes CSS 41177 only the second known eclipsing double white dwarf binary after NLTT 11748. The 2 minute long primary eclipse is 40% deep and the secondary eclipse 10% deep. From Gemini+GMOS spectroscopy, we measure the radial velocities of both components of the binary from the H{alpha} absorption line cores. These measurements, combined with the light curve information, yield white dwarf masses of M{sub 1} = 0.283 {+-} 0.064 M{sub sun} and M{sub 2} = 0.274 {+-} 0.034 M{sub sun}, making them both helium core white dwarfs. As an eclipsing, double-lined spectroscopic binary, CSS 41177 is ideally suited to measuring precise, model-independent masses and radii. The two white dwarfs will merge in roughly 1.1 Gyr to form a single sdB star.

Parsons, S. G.; Marsh, T. R.; Gaensicke, B. T. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Drake, A. J. [California Institute of Technology, 1200 E. California Blvd, CA 91225 (United States); Koester, D. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Kiel (Germany)

2011-07-10T23:59:59.000Z

411

EFFECT OF TRITIUM AND DECAY HELIUM ON WELDMENT FRACTURE TOUGHNESS  

SciTech Connect

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

412

Enforcement Letter, International Isotopes Idaho Inc - August...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Isotopes Idaho, Inc. related to the Relocation of an Irradiated Pellet at the Test Reactor Area Hot Cell Facility at the Idaho National Engineering and Environmental...

413

EIS-0249: Medical Isotopes Production Project  

Energy.gov (U.S. Department of Energy (DOE))

This EIS evaluates the potential environmental impacts of a proposal to establish a production capability for molybdenum-99 (Mo-99) and related medical isotopes.

414

Category:Isotope Geothermometry | Open Energy Information  

Open Energy Info (EERE)

Login | Sign Up Search Category Edit History Facebook icon Twitter icon Category:Isotope Geothermometry Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home...

415

Integration of Nontraditional Isotopic Systems Into Reaction...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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

416

Science with Beams of Radioactive Isotopes  

NLE Websites -- All DOE Office Websites (Extended Search)

2015 The International Chemical Congress of Pacific Basin Societies Science with Beams of Radioactive Isotopes ( 340) Honolulu, Hawaii, USA December 15-20, 2015 Science...

417

Integration of Nontraditional Isotopic Systems Into Reaction...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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

418

Isotopic Analysis At Geysers Area (Lambert & Epstein, 1992) | Open Energy  

Open Energy Info (EERE)

Isotopic Analysis- Rock At Geysers Area (Lambert & Isotopic Analysis- Rock At Geysers Area (Lambert & Epstein, 1992) Exploration Activity Details Location Geysers Area Exploration Technique Isotopic Analysis- Rock Activity Date Usefulness useful DOE-funding Unknown Notes Measurements of 180/160, 13C/12C and D/H ratio variations were made by the usual methods (McCrea, 1950; Taylor and Epstein, 1962; Epstein and Taylor, 1970) using mass spectrometers of the type described by Nier (1947) with modifications by McKinney et al. (1950). Results are reported in 8-notation with respect to the SMOW (Craig, 1961 ) and PDB (Urey et al., 1951 ) standards. Analytical precisions for multiple analyses of any single sample were _+ 0.2%0 for oxygen and carbon and _ 1%o for hydrogen. Inhomogeneities of cuttings fractions gave rise to variations within single cuttings

419

Seasonal variations in the stable carbon isotopic signature of biogenic methane in a coastal sediment  

SciTech Connect

Systematic seasonal variations in the stable carbon isotopic signature of methane gas occur in the anoxic sediments of Cape Lookout Bight, a lagoonal basin on North Carolina's Outer Banks. Values for the carbon isotope ratio (delta /sup 13/C) of methane range from -57.3 per mil during summer to -68.5 per mil during winter in gas bubbles with an average methane content of 95%. The variations are hypothesized to result from changes in the pathways of microbial methane production and cycling of key substrates including acetate and hydrogen. The use of stable isotopic signatures to investigate the global methane cycle through mass balance calculations, involving various sediment and soil biogenic sources, appears to require seasonally averaged data from individual sites. 17 references, 2 figures, 2 tables.

Martens, C.S.; Blair, N.E.; Green, C.D.; Des Marais, D.J.

1986-09-19T23:59:59.000Z

420

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

SciTech Connect

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

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

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

SciTech Connect

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

422

Research with fast radioactive isotope beams at RIKEN  

Science Journals Connector (OSTI)

......moments of neutron-rich boron isotopes were measured by the...many neutron-rich isotopes. To exploit fully the...most straightforward determination of the charge distribution...called KISS (KEK isotope separation system......

Tohru Motobayashi; Hiroyoshi Sakurai

2012-01-01T23:59:59.000Z

423

Isotope-Selective Detection and Imaging of Organic Nanolayers  

Science Journals Connector (OSTI)

Isotope-Selective Detection and Imaging of Organic Nanolayers ... We show isotopic selectivity of MRFM for three nuclei, 1H, 31P, and 13C, in organic materials. ... data to further distinguish and characterize the 2 isotopes. ...

H. J. Mamin; T. H. Oosterkamp; M. Poggio; C. L. Degen; C. T. Rettner; D. Rugar

2009-07-09T23:59:59.000Z

424

Solvent Isotope-Induced Equilibrium Perturbation for Isocitrate Lyase  

Science Journals Connector (OSTI)

Solvent Isotope-Induced Equilibrium Perturbation for Isocitrate Lyase ... Solvent isotopic composition can influence both the rates of enzyme-catalyzed reactions (solvent kinetic isotope effects) and, in the case of solvent-derived deuterium incorporation into nonexchangeable C–H bonds in products, solvent equilibrium isotope effects. ... In this study, we report the solvent isotope-induced transient change in the concentration and isotopic composition of the reactants. ...

Christine E. Quartararo; Timin Hadi; Sean M. Cahill; John S. Blanchard

2013-11-21T23:59:59.000Z

425

Post-eruptive alteration of silicic ignimbrites and lavas, Gran Canaria, Canary Islands: Strontium, neodymium, lead, and oxygen isotopic evidence  

SciTech Connect

Isotopic analyses of Miocene comenditic, pantelleritic, and trachyphonolitic ignimbrites and lavas from Gran Canaria, Canary Islands, provide evidence for posteruptive mobility of Rb, Sr, and O. Calculated initial [sup 87]Sr/[sup 86]Sr ratios in whole-rock samples from basaltic lavas and feldspar mineral separates from ignimbrites define a magmatic trend in the stratigraphic section, from ratios of 0.70340 at the base of the Mogan Formation to 0.70305 in the lower Fataga Formation. However, calculated apparent initial [sup 87]Sr/[sup 86]Sr ratios in hydrated vitrophyre and devitrified matrix separates range from 0.7035 to 0.7090. [delta][sup 18]O ratios in basalts and feldspars vary little, from +5.7 to +6.1, yet range from +6.5 to +15.0 in the ignimbrite matrices. In contrast to the Sr and O isotope ratios, Pb and Nd isotope ratios are identical within analytical error in feldspars and their silicic ignimbrite matrices. Sequential leaching experiments and the oxygen data suggest that low-temperature, posteruptive interaction with meteoric water, perhaps containing a small seawater component, has modified Rb and Sr concentrations in the matrices, such that calculated apparent initial [sup 87]Sr/[sup 86]Sr ratios are not those of the magmas when they were erupted. Mobilization of Rb and Sr must occur significantly after eurption. Nd and Pb isotope systems appear to be unaffected by this process. Therefore, [sup 87]Sr/[sup 86]Sr ratios determined by whole rock analysis of silicic rocks from hotspot-type oceanic islands are suspect and should not be incorporated into mantle tracer studies, although analysis of phenocrysts may produce useful data. 40 refs., 5 figs., 3 tabs.

Cousens, B.L. (Universite de Montreal, Quebec (Canada)); Spera, F.J. (Univ. of California, Santa Barbara (United States)); Dobson, P.F. (Unocal Corp., Brea, CA (United States))

1993-02-01T23:59:59.000Z

426

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

427

36Cl/Cl ratios in geothermal systems- preliminary measurements from the  

Open Energy Info (EERE)

Cl/Cl ratios in geothermal systems- preliminary measurements from the Cl/Cl ratios in geothermal systems- preliminary measurements from the Coso Field Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: 36Cl/Cl ratios in geothermal systems- preliminary measurements from the Coso Field Details Activities (1) Areas (1) Regions (0) Abstract: The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results

428

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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...

429

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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

430

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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

431

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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

432

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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...

433

Stable Isotope, Site-Specific Mass Tagging For Protein Identification  

NLE Websites -- All DOE Office Websites (Extended Search)

Stable Isotope, Site-Specific Mass Tagging For Protein Identification Stable Isotope, Site-Specific Mass Tagging For Protein Identification Proteolytic peptide mass mapping as...

434

Enriched Stable Isotope Materials and Chemistry | ornl.gov  

NLE Websites -- All DOE Office Websites (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...

435

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

SciTech Connect

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

436

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

2011-07-06T23:59:59.000Z

437

Advanced Mass Spectrometers for Hydrogen Isotope Analyses  

SciTech Connect

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

438

History of Animals using Isotope Records (HAIR): A 6-year dietary history of one family of African elephants  

Science Journals Connector (OSTI)

...dominated by Acacia-Commiphora savanna and scrub bush and located along the Ewaso N?giro River (Fig...carbon isotope ratio and microhabitat in desert plants . Oecologia 76 : 562...Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA. thure.cerling...

Thure E. Cerling; George Wittemyer; James R. Ehleringer; Christopher H. Remien; Iain Douglas-Hamilton

2009-01-01T23:59:59.000Z

439

High flux isotope reactor cold source preconceptual design study report  

SciTech Connect

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

440

Isotopes  

NLE Websites -- All DOE Office Websites (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...

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

ISOTOPES  

E-Print Network (OSTI)

Research, Division of Nuclear Sciences of the Basic Energy Sciences ProgramResearch, Division of Nuclear Sciences of the Basic Energy Sciences Program

Lederer, C. Michael

2013-01-01T23:59:59.000Z

442

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

443

ISOTOPES  

E-Print Network (OSTI)

uranium, heavy-water-moderated CANDU reactor, as contrastedis important, and in the CANDU power reactor, which uses

Lederer, C. Michael

2013-01-01T23:59:59.000Z

444

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

>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

445

It's Elemental - Isotopes of the Element Francium  

NLE Websites -- All DOE Office Websites (Extended Search)

Radon Radon Previous Element (Radon) The Periodic Table of Elements Next Element (Radium) Radium Isotopes of the Element Francium [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Francium has no naturally occurring isotopes. Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 199 12 milliseconds Alpha Decay > 0.00% Electron Capture No Data Available 200 49 milliseconds Alpha Decay 100.00% 201 62 milliseconds Alpha Decay 100.00% 201m 19 milliseconds Alpha Decay 100.00% 202 0.30 seconds Alpha Decay 100.00% 202m 0.29 seconds Alpha Decay 100.00% 203 0.55 seconds Alpha Decay <= 100.00% 204 1.8 seconds Alpha Decay 92.00%

446

It's Elemental - Isotopes of the Element Radon  

NLE Websites -- All DOE Office Websites (Extended Search)

Astatine Astatine Previous Element (Astatine) The Periodic Table of Elements Next Element (Francium) Francium Isotopes of the Element Radon [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Radon has no naturally occurring isotopes. Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 193 1.15 milliseconds Alpha Decay 100.00% 194 0.78 milliseconds Alpha Decay 100.00% 195 6 milliseconds Alpha Decay 100.00% 195m 5 milliseconds Alpha Decay 100.00% 196 4.4 milliseconds Alpha Decay 99.90% Electron Capture ~ 0.10% 197 53 milliseconds Alpha Decay 100.00% 197m 25 milliseconds Alpha Decay 100.00% 198 65 milliseconds Alpha Decay No Data Available

447

Device and method for separating oxygen isotopes  

DOE Patents (OSTI)

A device and method for separating oxygen isotopes with an ArF laser which produces coherent radiation at approximately 193 nm. The output of the ArF laser is filtered in natural air and applied to an irradiation cell where it preferentially photodissociates molecules of oxygen gas containing .sup.17 O or .sup.18 O oxygen nuclides. A scavenger such as O.sub.2, CO or ethylene is used to collect the preferentially dissociated oxygen atoms and recycled to produce isotopically enriched molecular oxygen gas. Other embodiments utilize an ArF laser which is narrowly tuned with a prism or diffraction grating to preferentially photodissociate desired isotopes. Similarly, desired mixtures of isotopic gas can be used as a filter to photodissociate enriched preselected isotopes of oxygen.

Rockwood, Stephen D. (Los Alamos, NM); Sander, Robert K. (Los Alamos, NM)

1984-01-01T23:59:59.000Z

448

Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments  

SciTech Connect

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

449

DOUBLE-DETONATION SUB-CHANDRASEKHAR SUPERNOVAE: SYNTHETIC OBSERVABLES FOR MINIMUM HELIUM SHELL MASS MODELS  

SciTech Connect

In the double-detonation scenario for Type Ia supernovae, it is suggested that a detonation initiates in a shell of helium-rich material accreted from a companion star by a sub-Chandrasekhar-mass white dwarf. This shell detonation drives a shock front into the carbon-oxygen white dwarf that triggers a secondary detonation in the core. The core detonation results in a complete disruption of the white dwarf. Earlier studies concluded that this scenario has difficulties in accounting for the observed properties of Type Ia supernovae since the explosion ejecta are surrounded by the products of explosive helium burning in the shell. Recently, however, it was proposed that detonations might be possible for much less massive helium shells than previously assumed (Bildsten et al.). Moreover, it was shown that even detonations of these minimum helium shell masses robustly trigger detonations of the carbon-oxygen core (Fink et al.). Therefore, it is possible that the impact of the helium layer on observables is less than previously thought. Here, we present time-dependent multi-wavelength radiative transfer calculations for models with minimum helium shell mass and derive synthetic observables for both the optical and {gamma}-ray spectral regions. These differ strongly from those found in earlier simulations of sub-Chandrasekhar-mass explosions in which more massive helium shells were considered. Our models predict light curves that cover both the range of brightnesses and the rise and decline times of observed Type Ia supernovae. However, their colors and spectra do not match the observations. In particular, their B - V colors are generally too red. We show that this discrepancy is mainly due to the composition of the burning products of the helium shell of the Fink et al. models which contain significant amounts of titanium and chromium. Using a toy model, we also show that the burning products of the helium shell depend crucially on its initial composition. This leads us to conclude that good agreement between sub-Chandrasekhar-mass explosions and observed Type Ia supernovae may still be feasible but further study of the shell properties is required.

Kromer, M.; Sim, S. A.; Fink, M.; Roepke, F. K.; Seitenzahl, I. R.; Hillebrandt, W., E-mail: mkromer@mpa-garching.mpg.d [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Strasse 1, D-85748 Garching (Germany)

2010-08-20T23:59:59.000Z

450

Mantle helium in hydrothermal plumes in the Galapagos Rift  

Science Journals Connector (OSTI)

... the laboratory for analysis on a 3He/4He ratio mass spectrometer as described previously3'5. Radon activities were measured at sea on six of these samples, using our normal shipboard ... 3He observed in the deep oceans, by seawater penetration and circulation in the basalts.Radon concentrations (Table 1) are reported as 'excess ...

J. E. LUPTON; R. F. WEISS; H. CRAIG

1977-06-16T23:59:59.000Z

451

Estimation of tritium and helium inventory in the tritium handling system in Korea  

SciTech Connect

In Korea, the Wolsong Tritium Removal Facility (WTRF) is under construction to reduce the amount of tritium present in the moderator and coolant of the CANDU type Wolsong nuclear power plants. Recently, a study on the tritium handling system for recovery of the tritium collected from the WTRF was started. Some tritium would enter the steel of the container walls and subsequently decay to helium. This helium can deteriorate the mechanical properties of the material of the tritium handling system. To evaluate the tritium and helium inventory in the stainless steel wall of this system, the time-dependent diffusion equation was developed, solved and the results are presented in this paper. These results were compared to previous work that evaluated the tritium inventory in the stainless steel wall of 50-L tritium containers. Tritium and helium concentration profiles and the corresponding inventories were evaluated with respect to the various parameters such as exposure time, temperature, and partial pressure. After 24 years, the helium inventory in the wall of the tritium handling system exceeds the tritium inventory. (authors)

Yook, D.; Lee, S.; Lee, K. [Dept. of Nuclear Eng., KAIST, 373-1, Kusong-dong, Yusong-gu, Daejon 305-701 (Korea, Republic of); Song, K. M.; Shon, S. H. [KEPRI, 103-16 Munji-Dong, Yuseong-Gu, Daejeon, 305-380 (Korea, Republic of)

2008-07-15T23:59:59.000Z

452

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

453

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

454

Deuterium transport and isotope effects in type 316L stainless steel at high temperatures for nuclear fusion and nuclear hydrogen technology applications  

Science Journals Connector (OSTI)

Abstract We present the first complete data set for the permeability, diffusivity, and solubility of both deuterium and hydrogen in 316L stainless steel (316L SS) obtained over a wide temperature range of 350–850 °C that accommodates both nuclear fusion and nuclear hydrogen technology applications. The deuterium results were also compared with the hydrogen results to estimate the isotope effect. The isotope effect ratio for diffusivity was different from the classical prediction. Furthermore, some of our results were compared with the results previously reported for 316 SS. Results and discussion are presented with an emphasis on the deuterium permeation and isotope effects.

S.K. Lee; S.-H. Yun; Han Gyu Joo; S.J. Noh

2014-01-01T23:59:59.000Z

455

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

456

HELIUM SHELL DETONATIONS ON LOW-MASS WHITE DWARFS AS A POSSIBLE EXPLANATION FOR SN 2005E  

SciTech Connect

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

457

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

SciTech Connect

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

458

Heat transfer enhancement on thin wires in superfluid helium forced flows  

E-Print Network (OSTI)

In this paper, we report the first evidence of an enhancement of the heat transfer from a heated wire by an external turbulent flow of superfluid helium. We used a standard Pt-Rh hot-wire anemometer and overheat it up to 21 K in a pressurized liquid helium turbulent round jet at temperatures between 1.9 K and 2.12 K. The null-velocity response of the sensor can be satisfactorily modeled by the counter flow mechanism while the extra cooling produced by the forced convection is found to scale similarly as the corresponding extra cooling in classical fluids. We propose a preliminary analysis of the response of the sensor and show that -contrary to a common assumption- such sensor can be used to probe local velocity in turbulent superfluid helium.

Duri, Davide; Moro, Jean-Paul; Roche, Philippe-Emmanuel; Diribarne, Pantxo

2014-01-01T23:59:59.000Z

459

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

460

Neutron-induced dpa, transmutations, gas production, and helium embrittlement of fusion materials  

E-Print Network (OSTI)

In a fusion reactor materials will be subjected to significant fluxes of high-energy neutrons. As well as causing radiation damage, the neutrons also initiate nuclear reactions leading to changes in the chemical composition of materials (transmutation). Many of these reactions produce gases, particularly helium, which cause additional swelling and embrittlement of materials. This paper investigates, using a combination of neutron-transport and inventory calculations, the variation in displacements 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. Subsequently, the gas production rates are used to provide revised estimates, based on new density-functional-theory results, for the critical component lifetimes associated with the helium-induced grain-boundary embrittlement of materials. The revised estimates give more optimistic projections for the lifetimes of materials in a fusion power plant co...

Gilbert, M R; Nguyen-Manh, D; Zheng, S; Packer, L W; Sublet, J -Ch

2013-01-01T23:59:59.000Z

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.


461

Isotopic composition of Silurian seawater  

SciTech Connect

Direct isotopic analyses of 21 samples of the Silurian hydrosphere preserved as fluid inclusions in Silurian halite deposits in the Michigan Basin Salina Group yield delta/sup 18/O, deltaD ranging from 0.2 to +5.9 and -26 to -73, respectively. delta/sup 18/O has the same range as observed for modern halite facies evaporite waters and is a few per thousand higher than 100 analyses of fluid inclusions in Permian halite. deltaD is about 20 to 30 per thousand lower than modern and Permian examples. The trajectory of evaporating seawater on a deltaD-delta/sup 18/O diagram initially has a positive slope of 3-6, but hooks strongly downward to negative values, the shape of the hook depending upon humidity. Halite begins to precipitate at delta values similar to those observed for the most /sup 18/O rich fluid inclusions. Subsequent evaporation yields progressively more negative delta values as observed for the fluid inclusions. The fluid inclusion data can be readily explained in terms of evaporating seawater and are consistent with the degree of evaporation deduced from measured bromide profiles. These data are strongly inconsistent with arguments that Silurian seawater was 5.5 per thousand depleted in /sup 18/O. delta/sup 18/O for evaporite waters is systematically related to that of seawater, and does not show a -5.5 per thousand shift in the Silurian, even allowing for variables which affect the isotope evaporation trajectory. The lower deltaD may indicate a component of gypsum dehydration waters or may suggest a D-depleted Silurian hydrosphere.

Knauth, L.P.; Kealy, S.; Larimer, S.

1985-01-01T23:59:59.000Z

462

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

463

Application of JLab 12GeV helium refrigeration system for the FRIB accelerator at MSU  

SciTech Connect

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

464

Stopping Cross Sections of Some Hydrocarbon Gases for 40-200-keV Helium Ions  

Science Journals Connector (OSTI)

The stopping cross sections of air, CH4, C2H2, C2H4, C3H8, (CH2)3, and C3H6 have been measured for incident helium ions in the energy range 40 to 200 keV. The data are in good agreement with previous experiment work, and have standard deviations between 2 and 6%. They obey an energy dependence ?=?E12 in accord with the calculation of Lindhard and Scharff. It has been shown that while there is probably an effect due to chemical binding on the helium-ion stopping cross sections of hydrocarbons, this effect is small.

John T. Park

1965-05-31T23:59:59.000Z

465

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas  

SciTech Connect

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

466

Ultrasonic attenuation and volume viscosity in liquid argon, nitrogen and helium  

E-Print Network (OSTI)

. Ultrasonic attenuation in liquid nitrogen at 49. 45 Hc/sec ll. Dersity dependence of the volume viscosity in l. iquid nitrogen 12. Density dependence of Qv/&(S in liquid nitrogen 40 13. Ultrasonic attenuation in liquid helium at 4. 20 K 43 14. Ultrasonic... attenuation in liquid helium at 3. 69"K 44 15. Qv in liquid argon and nitrogen as a function of reduced density 51 LIST OF TABLES 1. Data and results for the calculation of volume viscosity in liquid argon 2. Data and results for the calculation of volume...

Singer, James Robert

2012-06-07T23:59:59.000Z

467

Nanometer-scale tunnel formation in metallic glass by helium ion irradiation  

SciTech Connect

We have shown that upon high fluence helium ion irradiation, metallic glass Cu{sub 50}Zr{sub 45}Ti{sub 5} becomes highly porous at the depth of the helium projected range. The resulting porous region is characterized by the formation of a tunnel like structure and self-linkage of nanometer size gas bubbles. Furthermore, the irradiation leads to the formation of nanometer size Cu{sub x}Zr{sub y} crystals that are randomly distributed. The results of this study indicate that the He-filled bubbles have attractive interactions and experience considerable mobility. Movement of the bubbles is believed to be assisted by ballistic collisions.

Shao Lin [Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843 (United States); Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Gorman, Brian P. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401 (United States); Aitkaliyeva, Assel [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); David Theodore, N. [CHD-Fab, Freescale Semiconductor, Inc., Chandler, Arizona 85224 (United States); Xie Guoqiang [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2012-07-23T23:59:59.000Z

468

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

469

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.

Karakas, A I; Sills, A; Campbell, S; Lattanzio, J C; Karakas, Amanda; Fenner, Yeshe; Sills, Alison; Campbell, Simon; Lattanzio, John

2006-01-01T23:59:59.000Z

470

Thermal photons to dileptons ratio at LHC  

E-Print Network (OSTI)

It is shown that the ratio of transverse momentum (p_T) distribution of thermal photons to dileptons produced in heavy ion collisions reaches a plateau above p_T=1 GeV. We argue that the value of the ratio in the plateau region can be used to estimate the initial temperature.

Jajati K. Nayak; Jan-e Alam; Sourav Sarkar; Bikash Sinha

2007-05-24T23:59:59.000Z

471

Strontium isotopic study of subsurface brines from Illinois basin  

SciTech Connect

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

472

Chemi-ionization reactions involving metastable helium atoms at high energy P. Pradel and J. J. Laucagne  

E-Print Network (OSTI)

1263 Chemi-ionization reactions involving metastable helium atoms at high energy P. Pradel and J. J dépend du défaut d'énergie de la réaction. Abstract - Total chemi-ionization cross-sections have been. Introduction. Over the last decade the chemi-ionization of atomic or molecular gases by metastable helium

Paris-Sud XI, Université de

473

Gas Exchange of Algae: II. Effects of Oxygen, Helium, and Argon on the Photosynthesis of Chlorella pyrenoidosa  

Science Journals Connector (OSTI)

...verify that nitrogen, helium...and exit gases was identical...that the solubility of the gases in the algal...dioxide in nitrogen, helium...error due to water vapor pressure...properties of the gas molecules...closely matches nitrogen (Handbook...

Elizabeth C. B. Ammann; Victoria H. Lynch

1966-07-01T23:59:59.000Z

474

High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium  

SciTech Connect

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

475

Natural thorium isotopes in marine sediment core off Labuan port  

SciTech Connect

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

476

It's Elemental - Isotopes of the Element Magnesium  

NLE Websites -- All DOE Office Websites (Extended Search)

Sodium Sodium Previous Element (Sodium) The Periodic Table of Elements Next Element (Aluminum) Aluminum Isotopes of the Element Magnesium [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 24 78.99% STABLE 25 10.00% STABLE 26 11.01% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 19 4.0 picoseconds Double Proton Emission 100.00% 20 90.8 milliseconds Electron Capture 100.00% Electron Capture with delayed Proton Emission ~ 27.00% 21 122 milliseconds Electron Capture 100.00% Electron Capture with delayed Proton Emission 32.60% Electron Capture with delayed Alpha Decay < 0.50%

477

It's Elemental - Isotopes of the Element Chlorine  

NLE Websites -- All DOE Office Websites (Extended Search)

Sulfur Sulfur Previous Element (Sulfur) The Periodic Table of Elements Next Element (Argon) Argon Isotopes of the Element Chlorine [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 35 75.76% STABLE 37 24.24% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 28 No Data Available Proton Emission (suspected) No Data Available 29 < 20 nanoseconds Proton Emission No Data Available 30 < 30 nanoseconds Proton Emission No Data Available 31 150 milliseconds Electron Capture 100.00% Electron Capture with delayed Proton Emission 0.70% 32 298 milliseconds Electron Capture 100.00%

478

It's Elemental - Isotopes of the Element Potassium  

NLE Websites -- All DOE Office Websites (Extended Search)

Argon Argon Previous Element (Argon) The Periodic Table of Elements Next Element (Calcium) Calcium Isotopes of the Element Potassium [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 39 93.2581% STABLE 40 0.0117% 1.248×10+9 years 41 6.7302% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 32 No Data Available Proton Emission (suspected) No Data Available 33 < 25 nanoseconds Proton Emission No Data Available 34 < 25 nanoseconds Proton Emission No Data Available 35 178 milliseconds Electron Capture 100.00% Electron Capture with delayed Proton Emission 0.37% 36 342 milliseconds Electron Capture 100.00%

479

It's Elemental - Isotopes of the Element Phosphorus  

NLE Websites -- All DOE Office Websites (Extended Search)

Silicon Silicon Previous Element (Silicon) The Periodic Table of Elements Next Element (Sulfur) Sulfur Isotopes of the Element Phosphorus [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 31 100% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 24 No Data Available Electron Capture (suspected) No Data Available Proton Emission (suspected) No Data Available 25 < 30 nanoseconds Proton Emission 100.00% 26 43.7 milliseconds Electron Capture 100.00% Electron Capture with delayed Proton Emission No Data Available 27 260 milliseconds Electron Capture 100.00% Electron Capture with

480

It's Elemental - Isotopes of the Element Oxygen  

NLE Websites -- All DOE Office Websites (Extended Search)

Nitrogen Nitrogen Previous Element (Nitrogen) The Periodic Table of Elements Next Element (Fluorine) Fluorine Isotopes of the Element Oxygen [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 16 99.757% STABLE 17 0.038% STABLE 18 0.205% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 12 1.139×10-21 seconds Proton Emission No Data Available 13 8.58 milliseconds Electron Capture 100.00% Electron Capture with delayed Proton Emission 100.00% 14 70.620 seconds Electron Capture 100.00% 15 122.24 seconds Electron Capture 100.00% 16 STABLE - - 17 STABLE - - 18 STABLE - - 19 26.88 seconds Beta-minus Decay 100.00%

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.


481

It's Elemental - Isotopes of the Element Gallium  

NLE Websites -- All DOE Office Websites (Extended Search)

Zinc Zinc Previous Element (Zinc) The Periodic Table of Elements Next Element (Germanium) Germanium Isotopes of the Element Gallium [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 69 60.108% STABLE 71 39.892% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 56 No Data Available Proton Emission (suspected) No Data Available 57 No Data Available Proton Emission (suspected) No Data Available 58 No Data Available Proton Emission (suspected) No Data Available 59 No Data Available Proton Emission (suspected) No Data Available 60 70 milliseconds Electron Capture 98.40%

482

It's Elemental - Isotopes of the Element Sodium  

NLE Websites -- All DOE Office Websites (Extended Search)

Neon Neon Previous Element (Neon) The Periodic Table of Elements Next Element (Magnesium) Magnesium Isotopes of the Element Sodium [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 23 100% STABLE Known Isotopes Mass Number Half-life Decay Mo