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1

Status of the intense pulsed neutron source  

Science Conference Proceedings (OSTI)

IPNS is not unique in having concerns about the level of funding, and the future looks good despite these concerns. This report details the progress made at IPNS during the last two years. Other papers in these proceedings discuss in detail the status of the enriched uranium Booster target, the two instruments that are under construction, GLAD and POSY II, and a proposal for research on an Advanced Pulsed Neutron Source (ASPUN) that has been submitted to the Department of Energy (DOE). Further details on IPNS are available in the IPNS Progress Report 1987--1988, available by writing the IPNS Division Office. 9 refs., 3 tabs.

Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

1988-01-01T23:59:59.000Z

2

Performance of the intense pulsed neutron source accelerator system  

Science Conference Proceedings (OSTI)

The Intense Pulsed Neutron Source (IPNS) facility has now been operating in a routine way for outside users since November 1, 1981. From that date through December of 1982, the accelerator system was scheduled for neutron science for 4500 hours. During this time the accelerator achieved its short-term goals by delivering about 380,000,000 pulses of beam totaling over 6 x 10/sup 20/ protons. The changes in equipment and operating practices that evolved during this period of intense running are described. The intensity related instability threshold was increased by a factor of two and the accelerator beam current has been ion source limited. Plans to increase the accelerator intensity are also described. Initial operating results with a new H/sup -/ ion source are discussed.

Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.

1983-01-01T23:59:59.000Z

3

Feasibility studies of an accelerator for the intense pulsed neutron source (IPNS)  

SciTech Connect

A proton linac plus synchrotron system was studied for the proposed Intense Pulsed Neutron Source (IPNS) at Argonne. An Alvarez H$sup -$ linac of 70 MeV and a high intensity fast cycling proton synchrotron to accelerate protons to 800 MeV will be the best choice to give a flux of 10$sup 16$ thermal neutron/sec cm$sup 2$ at the surface of moderator with a spallation neutron target of W or $sup 238$U. (auth)

Khoe, T.K.; Kimura, M.

1974-11-01T23:59:59.000Z

4

Intense Pulsed Neutron Source progress report for 1991  

Science Conference Proceedings (OSTI)

The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne`s ZING-P and ZING-P` prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and ``in press`` articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.

Not Available

1991-12-31T23:59:59.000Z

5

Intense Pulsed Neutron Source progress report for 1991  

Science Conference Proceedings (OSTI)

The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne's ZING-P and ZING-P' prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and in press'' articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.

Not Available

1991-01-01T23:59:59.000Z

6

Pulsed-neutron monochromator  

DOE Patents (OSTI)

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, H.A. Jr.

1984-01-01T23:59:59.000Z

7

The development of solid methane neutron moderators at the Intense Pulsed Neutron Source facility of Argonne National Laboratory.  

DOE Green Energy (OSTI)

The Intense Pulsed Neutron Source (IPNS) started using solid methane moderators in 1985 because of their efficient conversion (about 3.5 times greater than was achieved with a liquid hydrogen moderator) of fast neutrons to long wavelength neutrons. However, the solid methane moderators experienced numerous failures due to pressure surges caused by a combination of (1) the release of stored energy, which occurred when methane radiolytic products recombined, and (2) the expansion of hydrogen, which built up in the solid methane during irradiation. During the ensuing years studies were made to determine how to operate the solid methane moderators without causing failure. The rate at which stored energy built up during irradiation and the temperature at which hydrogen was released during annealing were determined. Since 1993 IPNS has successfully operated the solid methane moderators (at about 30 K) by periodically annealing to the liquid state around 90 K after every roughly three days of irradiation.

Carpenter, J. M.; Miller, M. E.; Scott, T. L.

1999-03-10T23:59:59.000Z

8

Pulsed neutron detector  

DOE Patents (OSTI)

A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

Robertson, deceased, J. Craig (late of Albuquerque, NM); Rowland, Mark S. (Livermore, CA)

1989-03-21T23:59:59.000Z

9

Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 2  

SciTech Connect

The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the author shave made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

NONE

1996-05-01T23:59:59.000Z

10

Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 1  

Science Conference Proceedings (OSTI)

The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the authors have made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

Marzec, B. [ed.

1996-05-01T23:59:59.000Z

11

NEUTRON FLUX INTENSITY DETECTION  

DOE Patents (OSTI)

A method of measuring the instantaneous intensity of neutron flux in the core of a nuclear reactor is described. A target gas capable of being transmuted by neutron bombardment to a product having a resonance absorption line nt a particular microwave frequency is passed through the core of the reactor. Frequency-modulated microwave energy is passed through the target gas and the attenuation of the energy due to the formation of the transmuted product is measured. (AEC)

Russell, J.T.

1964-04-21T23:59:59.000Z

12

How Argonne's Intense Pulsed Neutron Source came to life and gained its niche : the view from an ecosystem perspective.  

Science Conference Proceedings (OSTI)

At first glance the story of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory (ANL) appears to have followed a puzzling course. When researchers first proposed their ideas for an accelerator-driven neutron source for exploring the structure of materials through neutron scattering, the project seemed so promising that both Argonne managers and officials at the laboratory's funding agency, the Department of Energy (DOE), suggested that it be made larger and more expensive. But then, even though prototype building, testing, and initial construction went well a group of prominent DOE reviewers recommended in fall 1980 that it be killed, just months before it had been slated to begin operation, and DOE promptly accepted the recommendation. In response, Argonne's leadership declared the project was the laboratory's top priority and rallied to save it. In late 1982, thanks to another review panel led by the same scientist who had chaired the panel that had delivered the death sentence, the project was granted a reprieve. However, by the late 1980s, the IPNS was no longer top priority within the international materials science community, at Argonne, or within the DOE budget because prospects for another, larger materials science accelerator emerged. At just this point, the facility started to produce exciting scientific results. For the next two decades, the IPNS, its research, and its experts became valued resources at Argonne, within the U.S. national laboratory system, and within the international materials science community. Why did this Argonne project prosper and then almost suffer premature death, even though it promised (and later delivered) good science? How was it saved and how did it go on to have a long, prosperous life for more than a quarter of a century? In particular, what did an expert assessment of the quality of IPNS science have to do with its fate? Getting answers to such questions is important. The U.S. government spends a lot of money to produce science and technology at multipurpose laboratories like Argonne. For example, in the mid-1990s, about the time the IPNS's fortunes were secured, DOE spent more than $6 billion a year to fund nine such facilities, with Argonne's share totaling $500 million. And an important justification for funding these expensive laboratories is that they operate expensive but powerful scientific tools like the IPNS, generally considered too large to be built and managed by universities. Clearly, 'life and death' decision making has a lot to tell us about how the considerable U.S. federal investment in science and technology at national laboratories is actually transacted and, indeed, how a path is cleared or blocked for good science to be produced. Because forces within Argonne, DOE, and the materials science community obviously dictated the changing fortunes of the IPNS, it makes sense to probe the interactions binding these three environments for an understanding of how the IPNS was threatened and how it survived. In other words, sorting out what happened requires analyzing the system that includes all three environments. In an attempt to find a better way to understand its twists and turns, I will view the life-and-death IPNS story through the lens of an ecological metaphor. Employing the ideas and terms that ecologists use to describe what happens in a system of shared resources, that is, an ecosystem, I will describe the IPNS as an organism that vied with competitors for resources to find a niche in the interrelated environments of Argonne, DOE, and the materials science community. I will start with an explanation of the Argonne 'ecosystem' before the advent of the IPNS and then describe how the project struggled to emerge in the 1970s, how it scratched its way to a fragile niche in the early 1980s, and how it adapted and matured through the turn of the 21st century. The paper will conclude with a summary of what the ecosystem perspective shows about the life and death struggle of the IPNS and reflect on what that perspective reveals about how researc

Westfall, C.; Office of The Director

2008-02-25T23:59:59.000Z

13

Progress toward a microsecond duration, repetitively pulsed, intense- ion beam  

Science Conference Proceedings (OSTI)

A number of intense ion beams applications are emerging requiring repetitive high-average-power beams. These applications include ablative deposition of thin films, rapid melt and resolidification for surface property enhancement, advanced diagnostic neutral beams for the next generation of Tokamaks, and intense pulsed-neutron sources. We are developing a 200-250 keV, 15 kA, 1 {mu}s duration, 1-30 Hz intense ion beam accelerator to address these applications.

Davis, H.A.; Olson, J.C.; Reass, W.A. [Los Alamos National Lab., NM (United States); Coates, D.M.; Hunt, J.W.; Schleinitz, H.M. [Du Pont de Nemours (E.I.) and Co., Wilmington, DE (United States). Central Research and Development Dept.; Lovberg, R.H. [California Univ., San Diego, La Jolla, CA (United States); Greenly, J.B. [Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies

1996-07-01T23:59:59.000Z

14

Cold moderators for pulsed neutron sources  

SciTech Connect

This paper reviews cold moderators in pulsed neutron sources and provides details of the performance of different cold moderator materials and configurations. Analytical forms are presented which describe wavelength spectra and emission time distributions. Several types of cooling arrangements used in pulsed source moderators are described. Choices of materials are surveyed. The author examines some of the radiation damage effects in cold moderators, including the phenomenon of burping'' in irradiated cold solid methane. 9 refs., 15 figs., 4 tabs.

Carpenter, J.M.

1990-01-01T23:59:59.000Z

15

Ultracold Neutron Production in a Pulsed Neutron Beam Line  

E-Print Network (OSTI)

We present the results of an Ultracold neutron (UCN) production experiment in a pulsed neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal expected can be overwhelmed by the large background associated with the scattering of the primary cold neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-D$_2$ is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O$_2$. In addition to setting the overall detection efficiency in the...

Lavelle, C M; Manus, G; McChesney, P M; Salvat, D J; Shin, Y; Makela, M; Morris, C; Saunders, A; Couture, A; Young, A R; Liu, C -Y

2010-01-01T23:59:59.000Z

16

Ultracold Neutron Production in a Pulsed Neutron Beam Line  

E-Print Network (OSTI)

We present the results of an Ultracold neutron (UCN) production experiment in a pulsed neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal expected can be overwhelmed by the large background associated with the scattering of the primary cold neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-D$_2$ is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O$_2$. In addition to setting the overall detection efficiency in the apparatus, UCN production data using solid D$_2$ suggest that the UCN upscattering cross-section is smaller than previous estimates, indicating the deficiency of the incoherent approximation widely used to estimate inelastic cross-sections in the thermal and cold regimes.

C. M. Lavelle; W. Fox; G. Manus; P. M. McChesney; D. J. Salvat; Y. Shin; M. Makela; C. Morris; A. Saunders; A. Couture; A. R. Young; C. -Y. Liu

2010-04-15T23:59:59.000Z

17

Materials processing with intense pulsed ion beams  

SciTech Connect

We review research investigating the application of intense pulsed ion beams (IPIBs) for the surface treatment and coating of materials. The short range (0.1-10 {mu}m) and high-energy density (1-50 J/cm{sup 2}) of these short-pulsed ({le} 1 {mu}s) beams (with ion currents I = 5 - 50 kA, and energies E = 100 - 1000 keV) make them ideal to flash-heat a target surface, similar to the more familiar pulsed laser processes. IPIB surface treatment induces rapid melt and solidification at up to 10{sup 10} K/s to cause amorphous layer formation and the production of non-equilibrium microstructures. At higher energy density the target surface is vaporized, and the ablated vapor is condensed as coatings onto adjacent substrates or as nanophase powders. Progress towards the development of robust, high-repetition rate IPIB accelerators is presented along with economic estimates for the cost of ownership of this technology.

Rej, D.J.; Davis, H.A.; Olson, J.C. [and others

1996-12-31T23:59:59.000Z

18

Supercool Neutrons (Ultracold Neutrons)  

E-Print Network (OSTI)

in the USA. Why neutrons? Neutrons possess physical properties that make them valuable investigative tools Spallation Neutron Source (SNS) The world's most intense pulsed accelerator-based neutron source. High Flux Isotope Reactor (HFIR) The highest flux reactor-based neutron source for condensed matter research

Martin, Jeff

19

"Development and Neutronic Validation of pelletized Cold and Very Cold Moderators for Pulsed Neutron Sources" Phase II Final report  

Science Conference Proceedings (OSTI)

Intense beams of cold neutrons are produced at several DOE facilities and are used by researchers to study the microscopic structure of materials. Energetic neutrons are produced by a high energy proton beam impacting a target. The fast neutrons are converted to the desired cold neutrons passing through a cryogenic moderator vessel, presently filled with dense cold hydrogen gas. Moderators made from solid methane have demonstrated superior performance to the hydrogen moderators but cannot be implemented on high power sources such as the SNS due to the difficulty of removing heat from the solid blocks of methane. Cryogenic Applications F, Inc has developed the methane pellet formation and transport technologies needed to produce a hydrogen cooled solid methane pellet moderator, potentially capable of being used in a high power spallation neutron facility. Such a methane pellet moderator could double the brightness of the neutron beam. Prior to this work a methane pellet moderator had not been produced or studied. The Indiana University LENS facility is a small pulsed neutron source used in part to study and develop cold neutron moderators. In this project cold neutrons were produced in a solid methane pellet moderator and analyzed with the LENS facility diagnostics. The results indicated that the neutron beam formed by the pellet moderator was similar to that of a solid methane block moderator.

Foster, Christopher; Baxter, David V

2012-11-17T23:59:59.000Z

20

Neutron and Gamma Ray Pulse Shape Discrimination with Polyvinyltoluene  

SciTech Connect

The goal of this was research effort was to test the ability of two poly vinyltoluene research samples to produce recordable, distinguishable signals in response to gamma rays and neutrons. Pulse shape discrimination was performed to identify if the signal was generated by a gamma ray or a neutron. A standard figure of merit for pulse shape discrimination was used to quantify the gamma-neutron pulse separation. Measurements were made with gamma and neutron sources with and without shielding. The best figure of merit obtained was 1.77; this figure of merit was achieved with the first sample in response to an un-moderated 252Cf source shielded with 5.08 cm of lead.

Lintereur, Azaree T.; Ely, James H.; Stave, Jean A.; McDonald, Benjamin S.

2012-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Aspects of a high intensity neutron source  

E-Print Network (OSTI)

A unique methodology for creating a neutron source model was developed for deuterons and protons incident on solid phase beryllium and lithium targets. This model was then validated against experimental results already ...

Chapman, Peter H. (Peter Henry)

2010-01-01T23:59:59.000Z

22

Slow Electrons Generated by Intense High-Frequency Laser Pulses  

Science Conference Proceedings (OSTI)

A very slow electron is shown to emerge when an intense high-frequency laser pulse is applied to a hydrogen negative ion. This counterintuitive effect cannot be accounted for by multiphoton or tunneling ionization mechanisms. We explore the effect and show that in the high-frequency regime the atomic electron is promoted to the continuum via a nonadiabatic transition caused by slow deformation of the dressed potential that follows a variation of the envelope of the laser pulse. This is a general mechanism, and a slow electron peak should always appear in the photoelectron spectrum when an atom is irradiated by a high-frequency pulse of finite length.

Toyota, Koudai; Watanabe, Shinichi [Department of Applied Physics and Chemistry, University of Electro-Communications, 1-5-1, Chofu-ga-oka, Chofu-shi, Tokyo (Japan); Tolstikhin, Oleg I. [Russian Research Center 'Kurchatov Institute', Kurchatov Square 1, Moscow 123182 (Russian Federation); Morishita, Toru [Department of Applied Physics and Chemistry, University of Electro-Communications, 1-5-1, Chofu-ga-oka, Chofu-shi, Tokyo (Japan); PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

2009-10-09T23:59:59.000Z

23

LANL Efforts on Neutron Coincidence Modeling of INL Pulsed Neutron Data  

SciTech Connect

Overview of this presentation is: (1) pulsed histogram analysis, (2) creation of SPNS, (3) use of SPNS for modeling pulsed neutron data, (4) creation of MUDI, (5) calculated accidentals correction using GUAM + MUDI, (6) background subtraction analysis, and (7) current/figure work with MCNP.

Stewart, Scott [Los Alamos National Laboratory; Thron, Jonathan L. [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory; Geist, William H. [Los Alamos National Laboratory; Charlton, William S. [Los Alamos National Laboratory

2012-06-25T23:59:59.000Z

24

High-efficiency Resonant rf Spin Rotator with Broad Phase Space Acceptance for Pulsed Polarized Cold Neutron Beams  

SciTech Connect

High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPD Gamma experiment, a search for the small parity-violating {gamma}-ray asymmetry A{sub Y} in polarized cold neutron capture on parahydrogen, is one example. For the NPD Gamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5 cm x 9.5 cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized {sup 3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8 {+-} 0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPD Gamma experiment are considered.

Seo, P. -N. [Los Alamos National Laboratory (LANL); Barron-Palos, L. [Arizona State University; Bowman, J. D. [Los Alamos National Laboratory (LANL); Chupp, T. E. [University of Michigan; Crawford, C. [University of Tennessee, Knoxville (UTK); Dabaghyan, M. [University of New Hampshire; Dawkins, M. [Indiana University; Freedman, S. J. [University of California; Gentile, T. R. [National Institute of Standards and Technology (NIST); Gericke, M. T. [University of Manitoba, Canada; Gillis, R. C. [University of Manitoba, Canada; Greene, G. L. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Hersman, F. W. [University of New Hampshire; Jones, G. L. [Hamilton College, New York; Kandes, M. [University of Michigan; Lamoreaux, S. [Los Alamos National Laboratory (LANL); Lauss, B. [University of California, Berkeley; Leuschner, M. B. [Indiana University; Mahurin, R. [University of Tennessee, Knoxville (UTK); Mason, M. [University of New Hampshire; Mei, J. [Indiana University; Mitchell, G. S. [Los Alamos National Laboratory (LANL); Nann, H. [Indiana University; Page, S. A. [University of Manitoba, Canada; Penttila, S. I. [Los Alamos National Laboratory (LANL); Ramsay, W. D. [University of Manitoba & TRIUMF, Canada; Salas Bacci, A. [Los Alamos National Laboratory (LANL); Santra, S. [Indiana University; Sharma, M. [University of Michigan; Smith, T. B. [University of Dayton, Ohio; Snow, W. [Indiana University; Wilburn, W. S. [Los Alamos National Laboratory (LANL); Zhu, H. [University of New Hampshire

2008-01-01T23:59:59.000Z

25

Residual stress measurement using the pulsed neutron source at LANSCE  

Science Conference Proceedings (OSTI)

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can make spatially resolved non-destructive strain measurements in the interior of components. By recording the change in the crystalline interplanar spacing, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all the lattice reflections are recorded in each measurement which allows anisotropic effects to be studied. Measurements made at the Manuel Lujan Jr Neutron Scattering Centre (LANSCE) demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 15 refs., 7 figs.

Bourke, M.A.M.; Goldstone, J.A. (Los Alamos National Lab., NM (USA)); Holden, T.M. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada))

1991-01-01T23:59:59.000Z

26

Pulsed neutron generator using shunt between anode and cathode  

SciTech Connect

A pulsed neutron generator for well logging is provided having a resistor connected between the anode and cathode. The resistor provides a direct current path whereby corona current can flow between the cathode and a corona point without the necessity for the ion source to conduct. In an alternative embodiment, the secondary coil of a pulsing transformer is connected in series with a resistor between the anode and cathode. In an alternative embodiment, a corona regulator in series with the collector-emitter of a transistor is connected between the cathode and anode of the neutron source and the base drive to the transistor is provided by a light-responsive solar cell activatable by an external lamp. Circuitry is provided for utilizing the various neutron sources.

Culver, R.B.

1976-12-07T23:59:59.000Z

27

First measurement of low intensity fast neutron background from rock at the Boulby Underground Laboratory  

E-Print Network (OSTI)

A technique to measure low intensity fast neutron flux has been developed. The design, calibrations, procedure for data analysis and interpretation of the results are discussed in detail. The technique has been applied to measure the neutron background from rock at the Boulby Underground Laboratory, a site used for dark matter and other experiments, requiring shielding from cosmic ray muons. The experiment was performed using a liquid scintillation detector. A 6.1 litre volume stainless steel cell was filled with an in-house made liquid scintillator loaded with Gd to enhance neutron capture. A two-pulse signature (proton recoils followed by gammas from neutron capture) was used to identify the neutron events from much larger gamma background from PMTs. Suppression of gammas from the rock was achieved by surrounding the detector with high-purity lead and copper. Calibrations of the detector were performed with various gamma and neutron sources. Special care was taken to eliminate PMT afterpulses and correlated background events from the delayed coincidences of two pulses in the Bi-Po decay chain. A four month run revealed a neutron-induced event rate of 1.84 +- 0.65 (stat.) events/day. Monte Carlo simulations based on the GEANT4 toolkit were carried out to estimate the efficiency of the detector and the energy spectra of the expected proton recoils. From comparison of the measured rate with Monte Carlo simulations the flux of fast neutrons from rock was estimated as (1.72 +- 0.61 (stat.) +- 0.38 (syst.))*10^(-6) cm^(-2) s^(-1) above 0.5 MeV.

E. Tziaferi; M. J. Carson; V. A. Kudryavtsev; R. Lerner; P. K. Lightfoot; S. M. Paling; M. Robinson; N. J. C. Spooner

2006-12-08T23:59:59.000Z

28

YALINA-booster subcritical assembly pulsed-neutron experiments : data processing and spatial corrections.  

Science Conference Proceedings (OSTI)

The YALINA-Booster experiments and analyses are part of the collaboration between Argonne National Laboratory of USA and the Joint Institute for Power & Nuclear Research - SOSNY of Belarus for studying the physics of accelerator driven systems for nuclear energy applications using low enriched uranium. The YALINA-Booster subcritical assembly is utilized for studying the kinetics of accelerator driven systems with its highly intensive D-T or D-D pulsed neutron source. In particular, the pulsed neutron methods are used to determine the reactivity of the subcritical system. This report examines the pulsed-neutron experiments performed in the YALINA-Booster facility with different configurations for the subcritical assembly. The 1141 configuration with 90% U-235 fuel and the 1185 configuration with 36% or 21% U-235 fuel are examined. The Sjoestrand area-ratio method is utilized to determine the reactivities of the different configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from the experimental data are shown to be dependent on the detector locations inside the subcritical assembly and the types of detector used for the measurements. In this report, Bell's spatial correction factors are calculated based on a Monte Carlo model to remove the detector dependences. The large differences between the reactivity values given by the detectors in the fast neutron zone of the YALINA-Booster are reduced after applying the spatial corrections. In addition, the estimated reactivity values after the spatial corrections are much less spatially dependent.

Cao, Y.; Gohar, Y.; Nuclear Engineering Division

2010-10-11T23:59:59.000Z

29

Frequency conversion of high-intensity, femtosecond laser pulses  

SciTech Connect

Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated that conversion efficiencies of 30-40% are possible at intensities of 600-800 GW/cm2, which is the operating level of the Petawatt laser at LLNL. The main limiting factors are phase modulation and material damage.

Banks, P S

1997-06-01T23:59:59.000Z

30

Neutron pulse simulation in nuclear waste for waste characterization  

SciTech Connect

The numerical simulations discussed in this paper show how analysis with computer-generated illustrations can be used to explain the concepts and advantages of pulsed neutron systems for tank waste evaluations. Furthermore, the analysis-illustration approach lends itself to parametric studies evaluating design features of hardware before it is fabricated. Nuclear material characteristics of hazardous or toxic simulants can be evaluated before preparing them or finding nontoxic or nonhazardous substitutes that will exhibit similar nuclear properties. Pulsed neutron systems hold significant promise for partial characterization of tank waste. The device could operate in a high background gamma radiation field and provide important information on moisture concentrations, fissionable material contents, and material interfaces quickly and at considerably less cost than obtainable from sample analyses.

Toffer, H.; Watson, W.T.; Roetman, V.E.

1993-12-01T23:59:59.000Z

31

Making Relativistic Positrons Using Ultra-Intense Short Pulse Lasers  

Science Conference Proceedings (OSTI)

This paper describes a new positron source produced using ultra-intense short pulse lasers. Although it has been studied in theory since as early as the 1970s, the use of lasers as a valuable new positron source was not demonstrated experimentally until recent years, when the petawatt-class short pulse lasers were developed. In 2008 and 2009, in a series of experiments performed at Lawrence Livermore National Laboratory, a large number of positrons were observed after shooting a millimeter thick solid gold target. Up to 2 x 10{sup 10} positrons per steradian ejected out the back of {approx}mm thick gold targets were detected. The targets were illuminated with short ({approx}1 ps) ultra-intense ({approx}1 x 10{sup 20} W/cm{sup 2}) laser pulses. These positrons are produced predominantly by the Bethe-Heitler process, and have an effective temperature of 2-4 MeV, with the distribution peaking at 4-7 MeV. The angular distribution of the positrons is anisotropic. For a wide range of applications, this new laser based positron source with its unique characteristics may complements the existing sources using radioactive isotopes and accelerators.

Chen, H; Wilks, S; Bonlie, J; Chen, C; Chen, S; Cone, K; Elberson, L; Gregori, G; Liang, E; Price, D; Van Maren, R; Meyerhofer, D D; Mithen, J; Murphy, C V; Myatt, J; Schneider, M; Shepherd, R; Stafford, D; Tommasini, R; Beiersdorfer, P

2009-08-24T23:59:59.000Z

32

Ultracold-neutron production in a pulsed-neutron beam line  

Science Conference Proceedings (OSTI)

We present the results of an ultracold neutron (UCN) production experiment in a pulsed-neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal can be overwhelmed by the large background associated with the scattering of the primary cold-neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-{sup 2}H{sub 2} is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O{sub 2}. In addition to setting the overall detection efficiency in the apparatus, UCN production data using solid {sup 2}H{sub 2} suggest that the UCN upscattering cross section is smaller than previous estimates, indicating the deficiency of the incoherent approximation widely used to estimate inelastic cross sections in the thermal and cold regimes.

Lavelle, C. M.; Liu, C.-Y.; Fox, W.; Manus, G.; McChesney, P. M.; Salvat, D. J.; Shin, Y.; Makela, M.; Morris, C.; Saunders, A.; Couture, A.; Young, A. R. [Physics Department, Indiana University, Bloomington, Indiana 47408 (United States); Physics Division, P25, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); LANSCE Division, Nuclear Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Physics Department, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2010-07-15T23:59:59.000Z

33

5 MW pulsed spallation neutron source, Preconceptual design study  

Science Conference Proceedings (OSTI)

This report describes a self-consistent base line design for a 5 MW Pulsed Spallation Neutron Source (PSNS). It is intended to establish feasibility of design and as a basis for further expanded and detailed studies. It may also serve as a basis for establishing project cost (30% accuracy) in order to intercompare competing designs for a PSNS not only on the basis of technical feasibility and technical merit but also on the basis of projected total cost. The accelerator design considered here is based on the objective of a pulsed neutron source obtained by means of a pulsed proton beam with average beam power of 5 MW, in {approx} 1 {mu}sec pulses, operating at a repetition rate of 60 Hz. Two target stations are incorporated in the basic facility: one for operation at 10 Hz for long-wavelength instruments, and one operating at 50 Hz for instruments utilizing thermal neutrons. The design approach for the proton accelerator is to use a low energy linear accelerator (at 0.6 GeV), operating at 60 Hz, in tandem with two fast cycling booster synchrotrons (at 3.6 GeV), operating at 30 Hz. It is assumed here that considerations of cost and overall system reliability may favor the present design approach over the alternative approach pursued elsewhere, whereby use is made of a high energy linear accelerator in conjunction with a dc accumulation ring. With the knowledge that this alternative design is under active development, it was deliberately decided to favor here the low energy linac-fast cycling booster approach. Clearly, the present design, as developed here, must be carried to the full conceptual design stage in order to facilitate a meaningful technology and cost comparison with alternative designs.

Not Available

1994-06-01T23:59:59.000Z

34

Novel materials synthesis using an intense pulsed ion beam  

Science Conference Proceedings (OSTI)

Initial experiments on evaporation from metallic and ceramic targets using a pulsed light ion beam source is reported. The source is an intense ion beam produced by a 1.2 MV, 300 kJ Anaconda generator fitted with an extraction diode. Beam fluences of 10--20 J/cm{sup 2} gives a deposition rate of about 30--50 nm per shot, for both brass and YBa{sub 2}Cu{sub 3}O{sub 7-x} (1-2-3) targets. This is about 1000 times greater than comparable rates from pulsed laser deposition (PLD). Single-shot ablated 1-2-3 films, deposited on Si, were analyzed using RBS; the measured stoichiometry was close to 1-2-3 in favorable cases, but shot-to-shot reproducibility was poor. Approximately 1% of the available ion beam energy was utilized for these initial experiments. The potential for producing large area coatings from multi-cation targets and nanophase powders using pulsed ion beam deposition will be discussed.

Gautier, D.C.; Muenchausen, R.E.; Rej, D.J.; Roberts, B.F.; Waganarr, W.J. [Los Alamos National Lab., NM (United States); Johnston, G. [New Mexico Univ., Albuquerque, NM (United States)

1992-12-31T23:59:59.000Z

35

Novel materials synthesis using an intense pulsed ion beam  

Science Conference Proceedings (OSTI)

Initial experiments on evaporation from metallic and ceramic targets using a pulsed light ion beam source is reported. The source is an intense ion beam produced by a 1.2 MV, 300 kJ Anaconda generator fitted with an extraction diode. Beam fluences of 10--20 J/cm[sup 2] gives a deposition rate of about 30--50 nm per shot, for both brass and YBa[sub 2]Cu[sub 3]O[sub 7-x] (1-2-3) targets. This is about 1000 times greater than comparable rates from pulsed laser deposition (PLD). Single-shot ablated 1-2-3 films, deposited on Si, were analyzed using RBS; the measured stoichiometry was close to 1-2-3 in favorable cases, but shot-to-shot reproducibility was poor. Approximately 1% of the available ion beam energy was utilized for these initial experiments. The potential for producing large area coatings from multi-cation targets and nanophase powders using pulsed ion beam deposition will be discussed.

Gautier, D.C.; Muenchausen, R.E.; Rej, D.J.; Roberts, B.F.; Waganarr, W.J. (Los Alamos National Lab., NM (United States)); Johnston, G. (New Mexico Univ., Albuquerque, NM (United States))

1992-01-01T23:59:59.000Z

36

Design of a High Intensity Neutron Source for Neutron-Induced Fission Yield Studies  

E-Print Network (OSTI)

The upgraded IGISOL facility with JYFLTRAP, at the accelerator laboratory of the University of Jyv\\"askyl\\"a, has been supplied with a new cyclotron which will provide protons of the order of 100 {\\mu}A with up to 30 MeV energy, or deuterons with half the energy and intensity. This makes it an ideal place for measurements of neutron-induced fission products from various actinides, in view of proposed future nuclear fuel cycles. The groups at Uppsala University and University of Jyv\\"askyl\\"a are working on the design of a neutron converter that will be used as neutron source in fission yield studies. The design is based on simulations with Monte Carlo codes and a benchmark measurement that was recently performed at The Svedberg Laboratory in Uppsala. In order to obtain a competitive count rate the fission targets will be placed very close to the neutron converter. The goal is to have a flexible design that will enable the use of neutron fields with different energy distributions. In the present paper, some considerations for the design of the neutron converter will be discussed, together with different scenarios for which fission targets and neutron energies to focus on.

M. Lantz; D. Gorelov; A. Jokinen; V. S. Kolhinen; A. Mattera; H. Penttilš; S. Pomp; V. Rakopoulos; S. Rinta-Antila; A. Solders

2013-04-09T23:59:59.000Z

37

Intensity modulated neutron radiotherapy optimization by photon proxy  

SciTech Connect

Purpose: Introducing intensity modulation into neutron radiotherapy (IMNRT) planning has the potential to mitigate some normal tissue complications seen in past neutron trials. While the hardware to deliver IMNRT plans has been in use for several years, until recently the IMNRT planning process has been cumbersome and of lower fidelity than conventional photon plans. Our in-house planning system used to calculate neutron therapy plans allows beam weight optimization of forward planned segments, but does not provide inverse optimization capabilities. Commercial treatment planning systems provide inverse optimization capabilities, but currently cannot model our neutron beam. Methods: We have developed a methodology and software suite to make use of the robust optimization in our commercial planning system while still using our in-house planning system to calculate final neutron dose distributions. Optimized multileaf collimator (MLC) leaf positions for segments designed in the commercial system using a 4 MV photon proxy beam are translated into static neutron ports that can be represented within our in-house treatment planning system. The true neutron dose distribution is calculated in the in-house system and then exported back through the MATLAB software into the commercial treatment planning system for evaluation. Results: The planning process produces optimized IMNRT plans that reduce dose to normal tissue structures as compared to 3D conformal plans using static MLC apertures. The process involves standard planning techniques using a commercially available treatment planning system, and is not significantly more complex than conventional IMRT planning. Using a photon proxy in a commercial optimization algorithm produces IMNRT plans that are more conformal than those previously designed at our center and take much less time to create. Conclusions: The planning process presented here allows for the optimization of IMNRT plans by a commercial treatment planning optimization algorithm, potentially allowing IMNRT to achieve similar conformality in treatment as photon IMRT. The only remaining requirements for the delivery of very highly modulated neutron treatments are incremental improvements upon already implemented hardware systems that should be readily achievable.

Snyder, Michael; Hammoud, Ahmad; Bossenberger, Todd; Spink, Robyn; Burmeister, Jay [Karmanos Cancer Center, Wayne State University School of Medicine, Detroit, Michigan 48201 (United States)

2012-08-15T23:59:59.000Z

38

Neutron fluence and energy reproducibility of a 2-dollar TRIGA reactor Pulse  

Science Conference Proceedings (OSTI)

Washington State Universityís 1 MW TRIGA reactor has a long history of utilization for neutron activation analysis (NAA). TRIGA reactors have the ability to pulse, reach supercritical (k>1) for short bursts of time. At this high power and fast time the energy spectrum and neutron fluence are largely uncharacterized. The pulse neutron energy spectrum and fluence were determined by the activation of Cu, Au, Co, Fe, and Ti. These analyses were completed with and without Cd shielding to determine reproducibility between pulses. The applications and implications of the neutron energy and fluence reproducibility to the use of pulsed NAA will be discussed.

Payne, Rosara F.; Drader, Jessica A.; Friese, Judah I.; Greenwood, Lawrence R.; Hines, Corey C.; Metz, Lori A.; Kephart, Jeremy D.; King, Matthew D.; Pierson, Bruce D.; Smith, Jeremy D.; Wall, Donald E.

2009-10-01T23:59:59.000Z

39

Deposition and surface treatment with intense pulsed ion beams  

Science Conference Proceedings (OSTI)

Intense pulsed ion beams (500 keV, 30 kA, 0.5 {mu}s) are being investigated for materials processing. Demonstrated and potential applications include film deposition, glazing and joining, alloying and mixing, cleaning and polishing, corrosion improvement, polymer surface treatments, and nanophase powder synthesis. Initial experiments at Los Alamos have emphasized thin-film formation by depositing beam ablated target material on substrates. We have deposited films with complex stoichiometry such as YBa{sub 2}Cu{sub 3}O{sub 7-x}, and formed diamond-like-carbon films. Instantaneous deposition rates of 1 mm/sec have been achieved because of the short ion range (typically 1{mu}m), excellent target coupling, and the inherently high energy of these beams. Currently the beams are produced in single shot uncomplicated diodes with good electrical efficiency. High-voltage modulator technology and diodes capable of repetitive firing, needed for commercial application, are being developed.

Olson, J.C.; Davis, H.A.; Rej, D.J.; Waganaar, W.J. [Los Alamos National Lab., NM (United States); Stinnett, R.W.; McIntyre, D.C. [Sandia National Labs., Albuquerque, NM (United States)

1995-02-08T23:59:59.000Z

40

Production of high-density high-temperature plasma by collapsing small solid-density plasma shell with two ultra-intense laser pulses  

Science Conference Proceedings (OSTI)

Three-dimensional particle-in-cell simulations show that the anisotropic collapse of a plasma microshell by impact of two oppositely directed intense laser pulses can create at the center of the shell cavity a submicron-sized plasma of high density and temperature suitable for generating fusion neutrons.

Xu, H. [National Laboratory for Parallel and Distributed Processing, School of Computer Science, National University of Defense Technology, Changsha 410073 (China); Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang 621900 (China); Yu Wei [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Yu, M. Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, Bochum D-44780 (Germany); Wong, A. Y. [Department of Physics, University of California, Los Angeles, California 90095 (United States); Sheng, Z. M.; Zhang, J. [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Murakami, M. [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan)

2012-04-02T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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.
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to obtain the most current and comprehensive results.


41

Pulsed D-D Neutron Generator Measurements of HEU Oxide Fuel Pins  

SciTech Connect

Pulsed neutron interrogation measurements have been performed on highly enriched uranium (HEU) oxide fuel pins and depleted uranium (DU) metal using a D-D neutron generator (2 x 10{sup 6} neutrons-s{sup -1}) and moderated {sup 3}He tubes at the Idaho National Laboratory Power Burst Facility. These measurements demonstrate the ability to distinguish HEU from DU by coincidence counting using a pulsed source. The amount of HEU measured was 8 kg in a sealed 55-gallon drum compared to 31 kg of DU. Neutron events were counted during and after the pulse with the Nuclear Materials Identification System (NMIS) and used to calculate the neutron coincidence time distributions. Passive measurements were also performed for comparison with the pulsed measurements. This paper presents the neutron coincidence distribution and Feynman variance results from the measurements.

McConchie, Seth M [ORNL; Hausladen, Paul [ORNL; Mihalczo, John T [ORNL; Blackburn, Brandon [Idaho National Laboratory (INL); Chichester, David [Idaho National Laboratory (INL)

2009-01-01T23:59:59.000Z

42

Fabrication of nano-structural arrays by channeling pulsed atomic beams through an intensity-modulated  

E-Print Network (OSTI)

Fabrication of nano-structural arrays by channeling pulsed atomic beams through an intensity-dimensional nano-structure arrays by passing a pulsed atomic beam through an intensity-modulated continuous of ``cooling'' along the longitudinal direction. This enables fabrication of vertically heterogeneous nano

Zhu, Xiangdong

43

Generation of high intensity rf pulses in the ionosphere by means of in situ compression  

SciTech Connect

We demonstrate, using a simple model, that high intensity pulses can be generated from a frequency-chirped modifier of much lower intensity by making use of the dispersive properties of the ionosphere. We show that a frequency-chirped pulse can be constructed so that its various components overtake each other at a prescribed height, resulting in large (up to one hundred times) transient intensity enhancements as compared to those achievable from a steady modifier operating at the same power. We examine briefly one possible application: the enhancement of plasma wave amplitudes which occurs as a result of the interaction of such a compressed pulse with pre-generated turbulence.

Cowley, S.C.; Perkins, F.W.; Valeo, E.J.

1993-04-01T23:59:59.000Z

44

A High Intensity Neutron Scattering Techniques for Hydrogen ...  

Science Conference Proceedings (OSTI)

Nucleation and Growth Observed by Ultrafast SAXS and WAXS ∑ O10: Effect of Nickel on the Neutron Irradiation Sensitivity of Nuclear Reactor Pressure Vessel†...

45

Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II : pulsed neutron source.  

SciTech Connect

One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a {sup 3}He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment.

Talamo, A.; Gohar, M. Y. A.; Rabiti, C.; Nuclear Engineering Division

2008-10-22T23:59:59.000Z

46

Film deposition and surface modification using intense pulsed ion beams  

SciTech Connect

High-power pulsed ion beams have been used to ablate material for ultrahigh-rate film deposition and to treat the surfaces of alloys. Pulsed ion beams were provided by the high-power-density Gamble II facility at the Naval Research Laboratory [high voltage ({similar_to}900 keV), short pulse (60 ns)] and the lower-power-density Anaconda facility at Los Alamos National Laboratory [lower voltage ({similar_to}300 keV), longer pulse (400 ns)]. Peak film deposition rates after target ablation reached 1 mm/s. Films of pure Al, pure Ta, YBCO, and Ni--Zn ferrite were deposited on glass and single-crystal substrates, in some cases heated. The film deposition process was studied with framing photography, a bolometer, and other diagnostics to gain an understanding of the ablation, transport, and deposition steps. Stoichiometric deposition of multicomponent targets has been demonstrated. Film morphology remains poor, but has steadily improved, and our present understanding points the way to further improvement. Lower fluences ({similar_to}5 J/cm{sup 2}) were used to investigate rapid thermal processing of metal surfaces for the enhancement of corrosion resistance. The results in this area have been negative, but here again the knowledge gained through these experiments allows us to propose directions for improvement. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Meli, C.A.; Grabowski, K.S.; Hinshelwood, D.D.; Stephanakis, S.J. [Naval Research Laboratory, Washington, DC 20375 (United States)] [Naval Research Laboratory, Washington, DC 20375 (United States); Rej, D.J.; Waganaar, W.J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1995-05-01T23:59:59.000Z

47

Commissioning of the new high-intensity ultracold neutron source at the Paul Scherrer Institut  

E-Print Network (OSTI)

Commissioning of the new high-intensity ultracold neutron (UCN) source at the Paul Scherrer Institut (PSI) has started in 2009. The design goal of this new generation high intensity UCN source is to surpass by a factor of ~100 the current ultracold neutron densities available for fundamental physics research, with the greatest thrust coming from the search for a neutron electric dipole moment. The PSI UCN source is based on neutron production via proton induced lead spallation, followed by neutron thermalization in heavy water and neutron cooling in a solid deuterium crystal to cold and ultracold energies. A successful beam test with up to 2 mA proton beam on the spallation target was conducted recently. Most source components are installed, others being finally mounted. The installation is on the track for the first cool-down and UCN production in 2010.

Bernhard Lauss

2010-11-17T23:59:59.000Z

48

New Concept for a Neutron Electric Dipole Moment Search using a Pulsed Beam  

E-Print Network (OSTI)

A concept to search for a neutron electric dipole moment (nEDM) is presented, which employs a pulsed neutron beam instead of the nowadays established use of storable ultracold neutrons (UCN). The technique takes advantage of the high peak flux and the time structure of a next-generation pulsed spallation source like the planned European Spallation Source. It is demonstrated that the sensitivity for a nEDM can be improved by several orders of magnitude compared to the best beam experiments performed in the 1970's and can compete with the sensitivity of UCN experiments.

F. M. Piegsa

2013-09-08T23:59:59.000Z

49

Note: A portable pulsed neutron source based on the smallest sealed-type plasma focus device  

Science Conference Proceedings (OSTI)

Development and operation of a portable and compact pulsed neutron source based on sealed-type plasma focus (PF) device are reported. The unit is the smallest sealed-type neutron producing PF device. The effective volume of the PF unit is 33 cm{sup 3} only. A compact size single capacitor (4 {mu}F) is used as the energy driver. A battery based power supply unit is used for charging the capacitor and triggering the spark gap. The PF unit is operated at 10 kV (200 J) and at a deuterium gas filling pressure of 8 mb. The device is operated over a time span of 200 days and the neutron emissions have been observed for 200 shots without changing the gas in between the shots. The maximum yield of this device is 7.8 x 10{sup 4} neutrons/pulse. Beyond 200 shots the yield is below the threshold (1050 neutrons/pulse) of our {sup 3}He detector. The neutron energy is evaluated using time of flight technique and the value is (2.49 {+-} 0.27) MeV. The measured neutron pulse width is (24 {+-} 5) ns. Multishot and long duration operations envisage the potentiality of such portable device for repetitive mode of operation.

Niranjan, Ram; Rout, R. K.; Srivastava, Rohit; Rawool, A. M.; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Mishra, Prabhat [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2011-02-15T23:59:59.000Z

50

Comoving acceleration of overdense electron-positron plasma by colliding ultra-intense laser pulses  

Science Conference Proceedings (OSTI)

Particle-in-cell (PIC) simulation results of sustained acceleration of electron-positron (e+e-) plasmas by comoving electromagnetic (EM) pulses are presented. When a thin slab of overdense e+e- plasma is irradiated with linear-polarized ultra-intense short laser pulses from both sides, the pulses are transmitted when the plasma is compressed to thinner than {approx}2 relativistic skin depths. A fraction of the plasma is then captured and efficiently accelerated by self-induced JxB forces. For 1 {mu}m laser and 10{sup 21} W cm{sup -2} intensity, the maximum energy exceeds GeV in a picosecond.

Liang, Edison [Rice University, P.O. Box 1892, Houston, Texas 77251 (United States)

2006-06-15T23:59:59.000Z

51

Analytical Calculation of the Neutrons Spectrum for Direct Measurement of N-N Scattering at Pulsed Reactor Yaguar  

E-Print Network (OSTI)

Analytical calculation of a single neutron detector counts per YAGUAR reactor pulse is presented and comparison with coincidence scheme is given.

V. K. Ignatovich

2008-06-23T23:59:59.000Z

52

Pulse Shape Discrimination for a Fast Neutron Detector  

Science Conference Proceedings (OSTI)

... as well as security applications such as detection of contraband fissile materials. Fast neutrons deposit energy in the scintillator by nuclear recoil ...

2010-09-08T23:59:59.000Z

53

Intensity-resolved Above Threshold Ionization Yields of Atoms with Ultrashort Laser Pulses  

E-Print Network (OSTI)

The above threshold ionization (ATI) spectra provide a diversity of information about a laser-atom ionization process such as laser intensity, pulse duration, carrier envelope phase, and atomic energy level spacing. However, the spatial distribution of intensities inherent in all laser beams reduces the resolution of this information. This research focuses on recovering the intensity-resolved ATI spectra from experimental data using a deconvolution algorithm. Electron ionization yields of xenon were measured for a set of laser pulse intensities using a time of flight (TOF) setup. Horizontally polarized, unchirped, 50fs pulses were used in the ionization process. All laser parameters other than the radiation intensity were held constant over the set of intensity measurements. A deconvolution algorithm was developed based on the experimental parameters. Then the deconvolution algorithm was applied to the experimental data to obtain the intensity-resolved total yield probability and ATI spectra. Finally, an error analysis was performed to determine the stability and accuracy of the algorithm as well as the quality of the data. It was found that the algorithm produced greater contrast for peaks in the ATI spectra where atom specific resonant behavior is observed. Additionally, the total yield probability showed that double ionization may be observed in the ionization yield. The error analysis revealed that the algorithm was stable under the experimental conditions for a range of intensities.

Hart, Nathan Andrew

2011-08-01T23:59:59.000Z

54

Nonlinear reflection of high intensity picosecond laser pulse from overdense plasma  

Science Conference Proceedings (OSTI)

The interaction of 1.5 ps FWHM laser pulses with solid targets at intensity 10{sup 15}-10{sup 17} W/cm{sup 2} and contrast ratio 10{sup 6} is studied. Red shift of a 'mirror' reflected fundamental wave and its second harmonic depending on the incident laser pulse energy and angle of incidence are observed. They are associated with Doppler shift corresponding to inward movement of the critical density surface from laser pondermotive pressure. Back scattered light has nonlinear dependence from laser intensity connected with SBS and changing of plasma surface.

Andreev, A. A.; Bayanov, V. I.; Vankov, A. B.; Kozlov, A. A.; Kurnin, I. V.; Platonov, K. Y.; Solovyev, N. A.; Chizhov, S. A.; Yashin, V. E. [Research Institute for Laser Physics, SC 'Vavilov State Optical Institute', 12, Birzhevaya line, St. Petersburg, 199034 (Russian Federation)

1998-02-20T23:59:59.000Z

55

Nonlinear reflection of high intensity picosecond laser pulse from overdense plasma  

Science Conference Proceedings (OSTI)

The interaction of 1.5 ps FWHM laser pulses with solid targets at intensity 10 15 Ė10 17 ? W/cm 2 and contrast ratio 10 6 is studied. Red shift of a ďmirrorĒ reflected fundamental wave and its second harmonic depending on the incident laser pulse energy and angle of incidence are observed. They are associated with Doppler shift corresponding to inward movement of the critical density surface from laser pondermotive pressure. Back scattered light has nonlinear dependence from laser intensity connected with SBS and changing of plasma surface.

A. A. Andreev; V. I. Bayanov; A. B. Vankov; A. A. Kozlov; I. V. Kurnin; K. Y. Platonov; N. A. Solovyev; S. A. Chizhov; V. E. Yashin

1998-01-01T23:59:59.000Z

56

Guiding of high intensity ultrashort laser pulses in plasma channels produced with the dual laser pulse ignitor-heater technique  

DOE Green Energy (OSTI)

The authors present results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme is proposed and experimentally tested in hydrogen and nitrogen. It makes use of two laser pulses. The Ignitor, an ultrashort (< 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used subsequently to heat the existing spark via inverse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. The channel density was diagnosed with time resolved longitudinal interferometry. From these measurements the plasma temperature was inferred. The guiding properties of the channels were tested by injecting a > 5 {times} 10{sup 17} W/cm{sup 2}, 75 fs laser pulse.

Volfbeyn, P.; Leemans, W.P.

1998-07-01T23:59:59.000Z

57

Hidden explosives detector employing pulsed neutron and x-ray interrogation  

DOE Green Energy (OSTI)

Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

Schultz, Frederick J. (Oak Ridge, TN); Caldwell, John T. (Los Alamos, NM)

1993-01-01T23:59:59.000Z

58

Hidden explosives detector employing pulsed neutron and x-ray interrogation  

DOE Patents (OSTI)

Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

Schultz, F.J.; Caldwell, J.T.

1993-04-06T23:59:59.000Z

59

The effects of intense magnetic fields on Landau levels in a neutron star  

E-Print Network (OSTI)

In this paper, an approximate method of calculating the Fermi energy of electrons ($E_{F}(e)$) in a high-intensity magnetic field, based on the analysis of the distribution of a neutron star magnetic field, has been proposed. In the interior of a Neutron star, different forms of intense magnetic field could exist simultaneously and a high electron Fermi energy could be generated by the release of magnetic field energy. The calculation results show that: $E_{F}(e)$ is related to density $\\rho$, the mean electron number per baryon $Y_{e}$ and magnetic field strength $B$.

Gao, Z F; Song, D L; Yuan, J P; Chou, C K

2013-01-01T23:59:59.000Z

60

Effect of pulse intensity distributions on fragment internal energy in the infrared multiphoton dissociation of vinyl  

E-Print Network (OSTI)

Effect of pulse intensity distributions on fragment internal energy in the infrared multiphoton the rovibra- tional energy distributions of fragmentsl formed in the infrared multiphoton dissociation (IRMPD energies of the frag- ment can be well characterized in terms of a Boltzmann distribution with a single

Zare, Richard N.

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Energetic electron propagation in solid targets driven by the intense electric fields of femtosecond laser pulses  

Science Conference Proceedings (OSTI)

An analytical model is used to interpret experimental data on the propagation of energetic electrons perpendicular to and parallel to the propagation direction of intense femtosecond laser pulses that are incident on solid targets. The pulses with {approx_equal}10{sup 20} W/cm{sup 2} intensity are incident normal onto a gadolinium or tungsten wire embedded in an aluminum substrate, and MeV electrons generated in the focal spot propagate along the laser direction into the irradiated wire. Electrons also propagate laterally from the focal spot through the aluminum substrate and into a dysprosium or hafnium spectator wire at a distance up to 1 mm from the irradiated wire. The ratio of the K shell emission from the spectator and irradiated wires is a measure of the numbers and energies of the MeV electrons propagating parallel to and perpendicular to the intense oscillating electric field of the laser pulse. It is found that the angular distribution of electrons from the focal spot is highly non-isotropic, and approximately twice as many electrons are driven by the electric field toward the spectator wire as into the irradiated wire. This quantitative result is consistent with the qualitative experimental observation that the oscillating electric field of an intense femtosecond laser pulse, when interacting with a heavy metal target, preferentially drives energetic electrons in the electric field direction as compared to perpendicular to the field.

Seely, J. F. [Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Szabo, C. I. [Artep, Inc., 2922 Excelsior Spring Circle, Ellicott City, Maryland 21042 (United States); Audebert, P.; Brambrink, E. [Laboratoire pour L'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, 91128 Palaiseau Cedex (France)

2011-06-15T23:59:59.000Z

62

Intense Electromagnetic Outbursts from Collapsing Hypermassive Neutron Stars  

E-Print Network (OSTI)

We study the gravitational collapse of a magnetized neutron star using a novel numerical approach able to capture both the dynamics of the star and the behavior of the surrounding plasma. In this approach, a fully general relativistic magnetohydrodynamics implementation models the collapse of the star and provides appropriate boundary conditions to a force-free model which describes the stellar exterior. We validate this strategy by comparing with known results for the rotating monopole and aligned rotator solutions and then apply it to study both rotating and non-rotating stellar collapse scenarios, and contrast the behavior with what is obtained when employing the electrovacuum approximation outside the star. The non-rotating electrovacuum collapse is shown to agree qualitatively with a Newtonian model of the electromagnetic field outside a collapsing star. We illustrate and discuss a fundamental difference between the force-free and electrovacuum solutions, involving the appearance of large zones of electric-dominated field in the vacuum case. This provides a clear demonstration of how dissipative singularities appear generically in the non-linear time-evolution of force-free fluids. In both the rotating and non-rotating cases, our simulations indicate that the collapse induces a strong electromagnetic transient. In the case of sub-millisecond rotation, the magnetic field experiences strong winding and the transient carries much more energy. This result has important implications for models of gamma-ray bursts.

Luis Lehner; Carlos Palenzuela; Steven L. Liebling; Christopher Thompson; Chad Hanna

2011-12-12T23:59:59.000Z

63

Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses  

SciTech Connect

Terahertz (THz) radiation from atomic clusters illuminated by intense femtosecond laser pulses is investigated. By studying the angular distribution, polarization properties and energy dependence of THz waves, we aim to obtain a proper understanding of the mechanism of THz generation. The properties of THz waves measured in this study differ from those predicted by previously proposed mechanisms. To interpret these properties qualitatively, we propose that the radiation is generated by time-varying quadrupoles, which are produced by the ponderomotive force of the laser pulse.

Jahangiri, Fazel [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan) [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan); Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan) [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan); Department of Physics, GSS, Kyoto University, Kyoto (Japan); Nagashima, Takeshi; Hangyo, Masanori [Department of Physics, GSS, Kyoto University, Kyoto (Japan) [Department of Physics, GSS, Kyoto University, Kyoto (Japan); Institute of Laser Engineering, Osaka University, Osaka (Japan)

2013-05-13T23:59:59.000Z

64

Momentum distributions of sequential ionization generated by an intense laser pulse  

E-Print Network (OSTI)

The relative yield and momentum distributions of all multiply charged atomic ions generated by a short (30 fs) intense (10(14)-5 x 10(18) W/cm(2)) laser pulse are investigated using a Monte Carlo simulation. We predict a substantial shift in the maximum (centroid) of the ion-momentum distribution along the laser polarization as a function of the absolute phase. This effect should be experimentally detectable with currently available laser systems even for relatively long pulses, such as 25-30 fs. In addition to the numerical results, we present semianalytical scaling for the position of the maximum.

Shvetsov-Shilovski, N. I.; Sayler, A. M.; Rathje, T.; Paulus, Gerhard G.

2011-01-01T23:59:59.000Z

65

Apparatus and process for active pulse intensity control of laser beam  

DOE Patents (OSTI)

An optically controlled laser pulse energy control apparatus and process is disclosed wherein variations in the energy of a portion of the laser beam are used to vary the resistance of a photodetector such as a photoresistor through which a control voltage is fed to a light intensity controlling device through which a second portion of the laser beam passes. Light attenuation means are provided to vary the intensity of the laser light used to control the resistance of the photodetector. An optical delay path is provided through which the second portion of the beam travels before reaching the light intensity controlling device. The control voltage is supplied by a variable power supply. The apparatus may be tuned to properly attenuate the laser beam passing through the intensity controlling device by adjusting the power supply, the optical delay path, or the light attenuating means. 3 figs.

Wilcox, R.B.

1990-01-01T23:59:59.000Z

66

Apparatus and process for active pulse intensity control of laser beam  

SciTech Connect

An optically controlled laser pulse energy control apparatus and process is disclosed wherein variations in the energy of a portion of the laser beam are used to vary the resistance of a photodetector such as a photoresistor through which a control voltage is fed to a light intensity controlling device through which a second portion of the laser beam passes. Light attenuation means are provided to vary the intensity of the laser light used to control the resistance of the photodetector. An optical delay path is provided through which the second portion of the beam travels before reaching the light intensity controlling device. The control voltage is supplied by a variable power supply. The apparatus may be tuned to properly attenuate the laser beam passing through the intensity controlling device by adjusting the power supply, the optical delay path, or the light attenuating means.

Wilcox, Russell B. (Oakland, CA)

1992-01-01T23:59:59.000Z

67

Apparatus and process for active pulse intensity control of laser beam  

DOE Patents (OSTI)

An optically controlled laser pulse energy control apparatus and process is disclosed wherein variations in the energy of a portion of the laser beam are used to vary the resistance of a photodetector such as a photoresistor through which a control voltage is fed to a light intensity controlling device through which a second portion of the laser beam passes. Light attenuation means are provided to vary the intensity of the laser light used to control the resistance of the photodetector. An optical delay path is provided through which the second portion of the beam travels before reaching the light intensity controlling device. The control voltage is supplied by a variable power supply. The apparatus may be tuned to properly attenuate the laser beam passing through the intensity controlling device by adjusting the power supply, the optical delay path, or the light attenuating means. 3 figs.

Wilcox, R.B.

1990-12-31T23:59:59.000Z

68

Tailoring the filamentation of intense femtosecond laser pulses with periodic lattices  

Science Conference Proceedings (OSTI)

We show numerically that by using periodic lattices the filamentation of intense femtosecond laser pulses, otherwise a result of competing nonlinear effects, can be well controlled with respect to its properties. The diffraction induced by the lattice provides a regularizing mechanism to the nonlinear self-action effects involved in filamentation. We demonstrate a new propagation regime of intense lattice solitons bridging the field of spatial solitons with that of femtosecond laser filamentation. The effective filamentation control is expected to have an important impact on numerous applications.

Panagiotopoulos, P.; Tzortzakis, S. [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, P.O. Box 1527, GR-71110 Heraklion (Greece); Efremidis, N. K. [Department of Applied Mathematics, University of Crete, P.O. Box 2208, GR-71003 Heraklion (Greece); Papazoglou, D. G. [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, P.O. Box 1527, GR-71110 Heraklion (Greece); Department of Materials Science and Technology, University of Crete, P.O. Box 2208, GR-71003 Heraklion (Greece); Couairon, A. [Centre de Physique Theorique, Centre National de la Recherche Scientifique, Ecole Polytechnique, F-91128 Palaiseau (France)

2010-12-15T23:59:59.000Z

69

Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation  

SciTech Connect

Recent advancement in digital signal processing (DSP) using fast processors and computer makes it possible to be used in pulse shape discrimination applications. In this study, we have investigated the feasibility of using a DSP to distinguish between the neutrons and gamma rays by the shape of their pulses in a liquid scintillator detector (BC501), and have investigated pulse shape-based techniques to improve the resolution performance of room-temperature cadmium zinc telluride (CZT) detectors. For the neutron/gamma discrimination, the advantage of using a DSP over the analog method is that in analog system two separate charge-sensitive ADC's are required. One ADC is used to integrate the beginning of the pulse risetime while the second ADC is for integrating the tail part. Using a DSP eliminates the need for separate ADCs as one can easily get the integration of two parts of the pulse from the digital waveforms. This work describes the performance of these DSP techniques and compares the results with the analog method.

R. Aryaeinejad; John K. Hartwell

2005-11-01T23:59:59.000Z

70

A Search for Pulsed and Bursty Radio Emission from X-ray Dim Isolated Neutron Stars  

E-Print Network (OSTI)

We have carried out a search for radio emission from six X-ray dim isolated neutron stars (XDINSs) observed with the Robert C. Byrd Green Bank Radio Telescope (GBT) at 820 MHz. No bursty or pulsed radio emission was found down to a 4sigma significance level. The corresponding flux limit is 0.01-0.04 mJy depending on the integration time for the particular source and pulse duty cycle of 2%. These are the most sensitive limits yet on radio emission from these objects.

V. I. Kondratiev; M. Burgay; A. Possenti; M. A. McLaughlin; D. R. Lorimer; R. Turolla; S. Popov; S. Zane

2007-10-08T23:59:59.000Z

71

Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz  

E-Print Network (OSTI)

The performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz with a maximum peak energy of 10 MJ is described. The solid deuterium converter with a volume of V=160 cm3 (8 mol), which is exposed to a thermal neutron fluence of 4.5x10^13 n/cm2, delivers up to 550 000 UCN per pulse outside of the biological shield at the experimental area. UCN densities of ~ 10/cm3 are obtained in stainless steel bottles of V ~ 10 L resulting in a storage efficiency of ~20%. The measured UCN yields compare well with the predictions from a Monte Carlo simulation developed to model the source and to optimize its performance for the upcoming upgrade of the TRIGA Mainz into a user facility for UCN physics.

J. Karch; Yu. Sobolev; M. Beck; K. Eberhardt; G. Hampel; W. Heil; R. Kieser; T. Reich; N. Trautmann; M. Ziegner

2013-08-21T23:59:59.000Z

72

Pulsed Neutron Measurments With A DT Neutron Generator for an Annular HEU Uranium Metal Casting  

SciTech Connect

Measurements were performed with a single annular, stainless-steel-canned casting of uranium (93.17 wt% 235U) metal ( ~18 kg) to provide data to verify calculational methods for criticality safety. The measurements used a small portable DT generator with an embedded alpha detector to time and directionally tag the neutrons from the generator. The center of the time and directional tagged neutron beam was perpendicular to the axis of the casting. The radiation detectors were 1x1x6 in plastic scintillators encased in 0.635-cm-thick lead shields that were sensitive to neutrons above 1 MeV in energy. The detector lead shields were adjacent to the casting and the target spot of the generator was about 3.8 cm from the casting at the vertical center. The time distribution of the fission induced radiation was measured with respect to the source event by a fast (1GHz) processor. The measurements described in this paper also include time correlation measurements with a time tagged spontaneously fissioning 252Cf neutron source, both on the axis and on the surface of the casting. Measurements with both types of sources are compared. Measurements with the DT generator closely coupled with the HEU provide no more additional information than those with the Cf source closely coupled with the HEU and are complicated by the time and directionally tagged neutrons from the generator scattering between the walls and floor of the measurements room and the casting while still above detection thresholds.

Mihalczo, John T [ORNL; Archer, Daniel E [ORNL; Wright, Michael C [ORNL; Mullens, James Allen [ORNL

2007-09-01T23:59:59.000Z

73

Investigating Correlated Neutrons from Pulsed Photonuclear Interrogation for Treaty Verification Applications  

E-Print Network (OSTI)

The treaty verification field is of renewed importance as continued nuclear weapons disarmament is prioritized nationally in partnership with other nuclear weapons states. This interest has led to research and development on technologies that could support future U.S. verification missions. A technology employing pulses of high-energy photons from an electron linear accelerator is one technique under consideration. High-energy photons are advantageous as an interrogation source because they penetrate thick shielding and can generate neutrons inside a measurement object. The neutrons would then multiply when presented with an object containing fissile material and allow for detection in a time domain immediately after the pulse. The purpose of this work was to develop an understanding of neutron behavior following a high-energy photon pulse and then develop a tool set to analyze data from this region to determine if a measurement object contains multiplying material, the mass of that material if present, and the moderation in the measurement object. Results indicate the tool sets developed were able to determine multiplication was present accurately in 3 out of 4 realistic verification objects. Additionally the state of the moderation in each object was able to be determined, and the mass could potentially be determined by calibrating to representative samples.

Stewart, Scott

2013-08-01T23:59:59.000Z

74

Liquid lithium target as a high intensity, high energy neutron source  

DOE Patents (OSTI)

This invention provides a target jet for charged particles. In one embodiment the charged particles are high energy deuterons that bombard the target jet to produce high intensity, high energy neutrons. To this end, deuterons in a vacuum container bombard an endlessly circulating, free-falling, sheet-shaped, copiously flowing, liquid lithium jet that gushes by gravity from a rectangular cross-section vent on the inside of the container means to form a moving web in contact with the inside wall of the vacuum container. The neutrons are produced via break-up of the beam in the target by stripping, spallation and compound nuclear reactions in which the projectiles (deuterons) interact with the target (Li) to produce excited nuclei, which then "boil off" or evaporate a neutron.

Parkin, Don M. (Los Alamos, NM); Dudey, Norman D. (Glen Ellyn, IL)

1976-01-01T23:59:59.000Z

75

Optimization of the target of an accelerator-driven neutron source through Monte Carlo numerical simulation of neutron and gamma transport by the  

E-Print Network (OSTI)

intense neutron beams for research on the structure and dynamics of materials in fields such as physics07-G00050D/gim SpallationNeutronSource SNS is an accelerator-based neutron source. This one-of-a-kind facility pro- vides the most intense pulsed neutron beams in the world. When ramped up to its full beam

Taskaev, Sergey Yur'evich

76

CIM - compact intensity modulation.  

SciTech Connect

Compact intensity modulation (CIM), a new method to modulate the intensity of a neutron beam is demonstrated. CIM allows the production of arbitrary signals where the focus point can be chosen and changed without any constraints. A novel feature in this technique compared to spin echo techniques is that the neutron polarization is kept parallel or anti-parallel to the static fields during the passage through the magnetic fields and the beating pattern at the detector is produced by an amplitude modulation (AM) of the adiabatic RF-spin flippers rather than Larmor precession like in neutron spin echo (NSE) instruments; thus, the achievable contrast is very high and the instrument resolution can be changed very quickly. This gives the fascinating possibility at pulsed neutron sources to sweep the modulation frequency of the flippers in order to increase dynamic resolution range during the same neutron pulse.

Bleuel, M.; Lang, E.; Gahler, G.; Lal, J.; Intense Pulsed Neutron Source; Inst. Lau Langevin

2008-07-21T23:59:59.000Z

77

Applicability of a Bonner Shere technique for pulsed neutron in 120 GeV proton facility  

Science Conference Proceedings (OSTI)

The data on neutron spectra and intensity behind shielding are important for radiation safety design of high-energy accelerators since neutrons are capable of penetrating thick shielding and activating materials. Corresponding particle transport codes--that involve physics models of neutron and other particle production, transportation, and interaction--have been developed and used world-wide [1-8]. The results of these codes have been ensured through plenty of comparisons with experimental results taken in simple geometries. For neutron generation and transport, several related experiments have been performed to measure neutron spectra, attenuation length and reaction rates behind shielding walls of various thicknesses and materials in energy range up to several hundred of MeV [9-11]. The data have been used to benchmark--and modify if needed--the simulation modes and parameters in the codes, as well as the reference data for radiation safety design. To obtain such kind of data above several hundred of MeV, Japan-Fermi National Accelerator Laboratory (FNAL) collaboration for shielding experiments has been started in 2007, based on suggestion from the specialist meeting of shielding, Shielding Aspects of Target, Irradiation Facilities (SATIF), because of very limited data available in high-energy region (see, for example, [12]). As a part of this shielding experiment, a set of Bonner sphere (BS) was tested at the antiproton production target facility (pbar target station) at FNAL to obtain neutron spectra induced by a 120-GeV proton beam in concrete and iron shielding. Generally, utilization of an active detector around high-energy accelerators requires an improvement on its readout to overcome burst of secondary radiation since the accelerator delivers an intense beam to a target in a short period after relatively long acceleration period. In this paper, we employ BS for a spectrum measurement of neutrons that penetrate the shielding wall of the pbar target station in FNAL.

Sanami, T.; Hagiwara, M.; Iwase, H.; /KEK, Tsukuba; Iwamoto, Y.; Sakamoto, Y.; Nakashima, H.; /JAEA, Ibaraki; Arakawa, H.; Shigyo, N.; /Kyushu U.; Leveling, A.F.; Boehnlein, D.J.; Vaziri, K.; /Fermilab

2008-02-01T23:59:59.000Z

78

Ionisation of hydrogen molecule in intense ultrashort laser pulses: parallel versus perpendicular orientation  

E-Print Network (OSTI)

A theoretical comparison of the electronic excitation and ionisation behaviour of molecular hydrogen oriented either parallel or perpendicular to a linear polarised laser pulse is performed. The investigation is based on a non-perturbative treatment that solves the full time-dependent Schr\\"odinger equation of both correlated electrons within the fixed-nuclei approximation and the dipole. Results are shown for two different laser pulse lengths and intensities as well as for a large variety of photon frequencies starting in the 1- and reaching into the 6-photon regime. In order to investigate the influence of the intrinsic diatomic two-center problem even further, two values of the internuclear separation and a newly developed atomic model are considered.

Yulian V. Vanne; Alejandro Saenz

2008-04-03T23:59:59.000Z

79

A graphite-moderated pulsed spallation ultra-cold neutron source  

E-Print Network (OSTI)

Proposals exist and efforts are under way to construct pulsed spallation ultra-cold neutron (UCN) sources at accelerator laboratories around the world. At the Paul Scherrer Institut (PSI), Switzerland, and at the Los Alamos National Laboratory (LANL), U.S.A., it is planned to use solid deuterium (SD_2) for the UCN production from cold neutrons. The philosophies about how the cold neutrons are obtained are quite different, though. The present proposal describes a third approach which applies a temperature optimized graphite moderator in combination with the SD_2 and qualitatively combines advantages of the different schemes. The scheme described here allows to build a powerful UCN source. Assuming a pulsed 2 mA, 590 MeV proton beam with an average current of 10 microA, one obtains UCN densities in excess of 2000 cm^{-3}, UCN fluxes of about 10^6 cm^{-2} s^{-1}, and total numbers of UCN in excess of 2*10^9 every 800 s.

Klaus Kirch

2001-09-05T23:59:59.000Z

80

Controlling double ionization of atoms in an intense bichromatic laser pulse  

SciTech Connect

We consider the classical dynamics of a two-electron system subjected to an intense bichromatic linearly polarized laser pulse. By varying the parameters of the field, such as the phase lag and the relative amplitude between the two colors of the field, we observe several trends from the statistical analysis of a large ensemble of trajectories initially in the ground-state energy of the helium atom: high sensitivity of the sequential double-ionization component, low sensitivity of the intensities where nonsequential double ionization occurs, while the corresponding yields can vary drastically. All these trends hold irrespective of which parameter is varied: the phase lag or the relative amplitude. We rationalize these observations by an analysis of the phase-space structures that drive the dynamics of this system and determine the extent of double ionization. These trends turn out to be mainly regulated by the dynamics of the inner electron.

Kamor, A.; Uzer, T. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430 (United States); Mauger, F.; Chandre, C. [Centre de Physique Theorique, CNRS, Aix-Marseille Universite, Campus de Luminy, case 907, 13288 Marseille cedex 09 (France)

2011-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux  

DOE Patents (OSTI)

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

Bowman, Charles D. (Los Alamos, NM)

1992-01-01T23:59:59.000Z

82

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux  

DOE Patents (OSTI)

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

Bowman, C.D.

1992-11-03T23:59:59.000Z

83

Design and optimization of 6li neutron-capture pulse mode ion chamber  

E-Print Network (OSTI)

The purpose of this research is to design and optimize the performance of a unique, inexpensive 6Li neutron-capture pulse-mode ion chamber (LiPMIC) for neutron detection that overcomes the fill-gas contamination stemming from outgas of detector components. This research also provides a demonstration of performance of LiPMICs. Simulations performed with GARFIELD, a drift-chamber simulation package for ion transport in an electrostatic field, have shown that argon-methane mixtures of fill-gas allow maintenance of electron drift velocity through a surprisingly wide range of fill-gas content. During the design stage of LiPMIC development, the thicknesses of lithium metallization layer, the neutron energy conversion site of the detector, and the thickness of neutron moderator, the high-density polyethylene body, are optimized through analytical and MCNPX calculations. Also, a methodology of obtaining the suitable combination of electric field strength, electron drift velocity, and fill-gas mixtures has been tested and simulated using argon-methane gas mixtures. The LiPMIC is shown to have comparable efficiency to 3He proportional counters at a fraction of cost. Six-month long baseline measurements of overall detector performance shows there is a 3% reduction in total counts for 252Cf sources, which provides a good indicator for the longevity of the detector.

Chung, Kiwhan

2008-08-01T23:59:59.000Z

84

Collective Focusing of Intense Ion Beam Pulses for High-energy Density Physics Applications  

SciTech Connect

The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson Phys. Rev. Lett. 48, 149 (1982) is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates (1) the effects of non-neutral collective focusing in a moderately strong magnetic field; (2) the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and (3) the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I (NDCX-I) , and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations. 2011 American Institute of Physics

Mikhail A. Dorf, Igor D. Kaganovich, Edward A. Startsev and Ronald C. Davidson

2011-04-27T23:59:59.000Z

85

Spallation Neutron Source  

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

D/gim D/gim Spallation Neutron Source SNS is an accelerator-based neutron source. This one-of-a-kind facility pro- vides the most intense pulsed neutron beams in the world. When ramped up to its full beam power of 1.4 MW, SNS will be eight times more powerful than today's best facility. It will give researchers more detailed snapshots of the smallest samples of physical and biological materials than ever before

86

Investigation of non-stationary self-focusing of intense laser pulse in cold quantum plasma using ramp density profile  

SciTech Connect

The authors have investigated the non-stationary self-focusing of Gaussian laser pulse in cold quantum plasma. In case of high dense plasma, the nonlinearity in the dielectric constant is mainly due to relativistic high intense interactions and quantum effects. In this paper, we have introduced a ramp density profile for plasma and presented graphically the behavior of spot size oscillations of pulse at rear and front portions of the pulse. It is observed that the ramp density profile and quantum effects play a vital role in stronger and better focusing at the rear of the pulse than at the front in cold quantum plasmas.

Habibi, M. [Department of Physics, Shirvan Branch, Islamic Azad University, Shirvan (Iran, Islamic Republic of); Ghamari, F. [Department of Physics, Khorramabad Branch, Islamic Azad University, Khorramabad (Iran, Islamic Republic of)

2012-11-15T23:59:59.000Z

87

Palm top plasma focus device as a portable pulsed neutron source  

SciTech Connect

Development of a palm top plasma focus device generating (5.2 {+-} 0.8) Multiplication-Sign 10{sup 4} neutrons/pulse into 4{pi} steradians with a pulse width of 15 {+-} 3 ns is reported for the first time. The weight of the system is less than 1.5 kg. The system comprises a compact capacitor bank, a triggered open air spark gap switch, and a sealed type miniature plasma focus tube. The setup is around 14 cm in diameter and 12.5 cm in length. The energy driver for the unit is a capacitor bank of four cylindrical commercially available electrolytic capacitors. Each capacitor is of 2 {mu}F capacity, 4.5 cm in diameter, and 9.8 cm in length. The cost of each capacitor is less than US$ 10. The internal diameter and the effective length of the plasma focus unit are 2.9 cm and 5 cm, respectively. A DC to DC converter power supply powered by two rechargeable batteries charges the capacitor bank to the desired voltage and also provides a trigger pulse of -15 kV to the spark gap. The maximum energy of operation of the device is 100 J (8 {mu}F, 5 kV, 59 kA) with deuterium gas filling pressure of 3 mbar. The neutrons have also been produced at energy as low as 36 J (3 kV) of operation. The neutron diagnostics are carried out with a bank of {sup 3}He detectors and with a plastic scintillator detector. The device is portable, reusable, and can be operated for multiple shots with a single gas filling.

Rout, R. K.; Niranjan, Ram; Srivastava, R.; Rawool, A. M.; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Mishra, P. [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2013-06-15T23:59:59.000Z

88

Acceleration of electrons by a circularly polarized laser pulse in the presence of an intense axial magnetic field in vacuum  

Science Conference Proceedings (OSTI)

Acceleration of electrons by a circularly polarized laser pulse in the presence of a short duration intense axial magnetic field has been studied. Resonance occurs between the electrons and the laser field for an optimum magnetic field leading to effective energy transfer from laser to electrons. The value of optimum magnetic field is independent of the laser intensity and decreases with initial electron energy. The electrons rotate around the axis of the laser pulse with small angle of emittance and small energy spread. Acceleration gradient increases with laser intensity and decreases with initial electron energy.

Singh, K. P. [Computational Plasma Dynamics Laboratory, Kettering University, Flint, Michigan 48504 (United States)

2006-08-15T23:59:59.000Z

89

Pulsed, Photonuclear-induced, Neutron Measurements of Nuclear Materials with Composite Shielding  

SciTech Connect

Active measurements were performed using a 10-MeV electron accelerator with inspection objects containing various nuclear and nonnuclear materials available at the Idaho National Laboratoryís Zero Power Physics Reactor (ZPPR) facility. The inspection objects were assembled from ZPPR reactor plate materials to evaluate the measurement technologies for the characterization of plutonium, depleted uranium or highly enriched uranium shielded by both nuclear and non-nuclear materials. A series of pulsed photonuclear, time-correlated measurements were performed with unshielded calibration materials and then compared with the more complex composite shield configurations. The measurements used multiple 3He detectors that are designed to detect fission neutrons between pulses of an electron linear accelerator. The accelerator produced 10-MeV bremsstrahlung X-rays at a repetition rate of 125 Hz (8 ms between pulses) with a 4-us pulse width. All inspected objects were positioned on beam centerline and 100 cm from the X-ray source. The time-correlated data was collected in parallel using both a Los Alamos National Laboratory-designed list-mode acquisition system and a commercial multichannel scaler analyzer. A combination of different measurement configurations and data analysis methods enabled the identification of each object. This paper describes the experimental configuration, the ZPPR inspection objects used, and the various measurement and analysis results for each inspected object.

James Jones; Kevin Haskell; Rich Waston; William Geist; Jonathan Thron; Corey Freeman; Martyn Swinhoe; Seth McConchie; Eric Sword; Lee Montierth; John Zabriskie

2011-07-01T23:59:59.000Z

90

Cratering behavior in single- and poly-crystalline copper irradiated by an intense pulsed ion beam  

Science Conference Proceedings (OSTI)

When treated with intense pulsed ion beams (IPIB), many materials exhibit increased wear resistance, fatigue life, and hardness. However, this treatment often results in cratering and roughening of the surface. In this work, high purity single crystal and polycrystalline copper samples were irradiated with pulses from an IPIB to gain insight into the causes of this cratering behavior. Samples were treated with 1,2,5, and 10 shots at 2 J/cm{sup 2} and 5 J/cm{sup 2} average energy fluence per shot. Shots were about 400 ns in duration and consisted of a mixture of carbon, hydrogen, and oxygen ions at 300 keV. It was found that the single crystal copper cratered far less than the polycrystalline copper at the lower energy fluence. At the higher energy fluence, cratering was replaced by other forms of surface damage, and the single crystal copper sustained less damage at all but the largest number of shots. Molten debris from the Lucite anode (the ion source) was removed and redeposited on the samples with each shot.

Wood, B.P.; Bitteker, L.J.; Waganaar, W.J. [Los Alamos National Lab., NM (United States). Plasma Physics Group; Perry, A.J. [A.I.M.S. Marketing, San Diego, CA (United States)

1998-12-31T23:59:59.000Z

91

Benchmark validation comparisons of measured and calculated delayed neutron detector responses for a pulsed photonuclear assessment technique  

SciTech Connect

An MCNPX-based calculational methodology has been developed to numerically simulate the complex electronĖphotonĖneutron transport problem for the active interrogation system known as the pulsed photonuclear assessment (PPA) technique. The PPA technique uses a pulsed electron accelerator to generate bremsstrahlung photons in order to fission nuclear materials. Delayed neutron radiation is then detected with helium-3 neutron detectors as evidence of the nuclear material presence. Two experimental tests were designed, setup and run to generate experimental data for benchmarking purposes. The first test irradiated depleted uranium in air, and the second test, depleted uranium in a simulated cargo container (plywood pallet), using 10 MeV electron pulses. Time-integrated, post-flash, delayed neutron counts were measured and compared to calculated count predictions in order to benchmark the calculational methodology and computer models. Comparisons between the experimental measurements and numerical predictions of the delayed neutron detector responses resulted in reasonable experiment/calculated ratios of 1.42 and 1.06 for the two tests. High-enriched uranium (HEU) predictions were also made with the benchmarked models.

J. W. Sterbentz; J. L. Jones; W. Y. Yoon; D. R. Norman; K. J. Haskell

2007-08-01T23:59:59.000Z

92

Use of pulsed-neutron capture logs to identify steam breakthrough  

Science Conference Proceedings (OSTI)

This paper reports on identification of steam-breakthrough zones in a stacked sand/shale sequence with variable lateral continuity which is difficult. Such identification, however, would allow the modification of field operations to enhance recovery through improved vertical sweep and heat injection. Twenty pulsed-neutron capture (PNC) logs were run to identify the steam-breakthrough zone(s) in a seven-pattern area of Mobil's Middle expansion (MIDX) Steamflood Project in the South Belridge field. These PNC data were combined with data from recent replacement wells and a detailed geologic analysis. Evaluation of this combined information allowed identification of potential steam-breakthrough zone(s), and operations were modified to reduce and eliminate steam breakthrough.

Masse, P.J.; Gosney, T.C. (Mobil E and P U.S. Inc. (US)); Long, D.L. (Halliburton Logging Services Inc. (US))

1991-09-01T23:59:59.000Z

93

Conceptual design of a high-intensity positron source for the Advanced Neutron Source  

SciTech Connect

The Advanced Neutron Source (ANS) is a planned new basic and applied research facility based on a powerful steady-state research reactor that provides neutrons for measurements and experiments in the fields of materials science and engineering, biology, chemistry, materials analysis, and nuclear science. The useful neutron flux will be at least five times more than is available in the world`s best existing reactor facility. Construction of the ANS provides a unique opportunity to build a positron spectroscopy facility (PSF) with very-high-intensity beams based on the radioactive decay of a positron-generating isotope. The estimated maximum beam current is 1000 to 5000 times higher than that available at the world`s best existing positron research facility. Such an improvement in beam capability, coupled with complementary detectors, will reduce experiment durations from months to less than one hour while simultaneously improving output resolution. This facility will remove the existing barriers to the routine use of positron-based analytical techniques and will be a giant step toward realization of the full potential of the application of positron spectroscopy to materials science. The ANS PSF is based on a batch cycle process using {sup 64}Cu isotope as the positron emitter and represents the status of the design at the end of last year. Recent work not included in this report, has led to a proposal for placing the laboratory space for the positron experiments outside the ANS containment; however, the design of the positron source is not changed by that relocation. Hydraulic and pneumatic flight tubes transport the source material between the reactor and the positron source where the beam is generated and conditioned. The beam is then transported through a beam pipe to one of several available detectors. The design presented here includes all systems necessary to support the positron source, but the beam pipe and detectors have not been addressed yet.

Hulett, L.D.; Eberle, C.C.

1994-12-01T23:59:59.000Z

94

Moderator materials and neutronic performance  

SciTech Connect

The great variety of instruments proposed for LANSCE-II entails an equally varied set of requirements for the target stations moderators. Besides the obvious features such as intensity and pulse width of the neutron pulse, a number of more pragmatic questions have to be addressed such as fast neutron background and energy deposition in the moderators, especially at large proton beam powers such as the 1 MW proton beam power proposed for LANSCE-II.

Daemen, L.L.; Russell, G.J.; Pitcher, E.J.; Lujan, M. Jr.

1993-12-31T23:59:59.000Z

95

Surface Modification of AISI-4620 Steel With Intense Pulsed Ion Beams  

SciTech Connect

A 300-keV, 30-kA, 1-{micro}s intense beam of carbon, oxygen, and hydrogen ions is used for the surface treatment of AISI-4620 steel coupons, a common material used in automotive gear applications. The beam is extracted from a magnetically-insulated vacuum diode and deposited into the top 1 {micro}m of the target surface. The beam-solid interaction causes a rapid melt and resolidification with heating and cooling rates of up to 10{sup 10} K/sec. Treated surfaces are smoothed over 1-{micro}m scale-lengths, but are accompanied by 1-{micro}m diameter craters and larger-scale roughening over >=10 {micro}m, depending on beam fluence and number of pulses. Treated surfaces are up to 1.8 x harder with no discernible change in modulus over depths of 1 {micro}m or more Qualitative improvements in the wear morphology of treated surfaces are reported.

Rej, D.J.; Davis, H.A.; Nastasi, M.; Olson, J.C.; Peterson, E.J.; Reiswig, R.D.; Walter, K.C.; Stinnett, R.W.; Remnev, G.E.; Struts, V.K.

1996-09-01T23:59:59.000Z

96

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma  

E-Print Network (OSTI)

Albuquerque, NM 87185 ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex

Kaganovich, I.D.

2010-01-01T23:59:59.000Z

97

Spallation Neutron Source, SNS  

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

Spallation Neutron Source Spallation Neutron Source Providing the most intense pulsed neutron beams in the world... Accumulator Ring Commissioning Latest Step for Spallation Neutron Source The Spallation Neutron Source, located at Oak Ridge National Laboratory, has passed another milestone on the way to completion this year--the commissioning of the proton accumulator ring. Brookhaven led the design and construction of the accumulator ring, which will allow an order of magnitude more beam power than any other facility in the world. The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. The figure on the right shows a schematic of the accumulator ring and transport beam lines that are being designed and built by Brookhaven

98

Quantitative interpretation of pulsed neutron capture logs: Part 1 --Fast numerical simulation  

E-Print Network (OSTI)

NEUTRON CAPTURE LOGS IN THINLY-BEDDED FORMATIONS Jordan G. Mimoun and Carlos Torres-Verdín, The University to capture neutrons. The lower the neutron energy, the more likely capture phenomena will take place; hence neutrons at thermal energies are the most likely to be absorbed. Consequently, monitoring the population

Torres-Verdín, Carlos

99

Relativistic effects in the interaction of high intensity ultra-short laser pulse with collisional underdense plasma  

SciTech Connect

In this paper, the effect of weakly relativistic ponderomotive force in the interaction of intense laser pulse with nonisothermal, underdense, collisional plasma is studied. Ponderomotive force modifies the electron density and temperature distribution. By considering the weakly relativistic effect and ohmic heating of plasma electrons, the nonlinear dielectric permittivity of plasma medium is obtained and the equation of electromagnetic wave propagation in plasma is solved. It is shown that with considering the ohmic heating of electrons and collisions, the effect of ponderomotive force in weakly relativistic regime leads to steepening the electron density profile and increases the temperature of plasma electrons noticeably. Bunches of electrons in plasma become narrower. By increasing the laser pulse strength, the wavelength of density oscillations decreases. In this regime of laser-plasma interaction, electron temperature increases sharply by increasing the intensity of laser pulse. The amplitude of electric and magnetic fields increases by increasing the laser pulse energy while their wavelength decreases and they lost their sinusoidal form.

Abedi, Samira [Physics Department, North Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Dorranian, Davoud [Laser Lab., Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Abari, Mehdi Etehadi [Physics Department, Science Faculty, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Shokri, Babak [Physics Department, Science Faculty, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Laser-Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of)

2011-09-15T23:59:59.000Z

100

Neutrons  

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

School on Neutron and X-ray Scattering Oak Ridge 10-24 August 2013 John M. Carpenter ANL, ORNLSNS 18 August 2013 2 Neutron Detection How does one detect a neutron? - It is...

Note: This page contains sample records for the topic "intense pulsed neutron" 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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101

Rationale for a spallation neutron source target system test facility at the 1-MW Long-Pulse Spallation Source  

Science Conference Proceedings (OSTI)

The conceptual design study for a 1-MW Long-Pulse Spallation Source at the Los Alamos Neutron Science Center has shown the feasibility of including a spallation neutron test facility at a relatively low cost. This document presents a rationale for developing such a test bed. Currently, neutron scattering facilities operate at a maximum power of 0.2 MW. Proposed new designs call for power levels as high as 10 MW, and future transmutation activities may require as much as 200 MW. A test bed will allow assessment of target neutronics; thermal hydraulics; remote handling; mechanical structure; corrosion in aqueous, non-aqueous, liquid metal, and molten salt systems; thermal shock on systems and system components; and materials for target systems. Reliable data in these areas are crucial to the safe and reliable operation of new high-power facilities. These tests will provide data useful not only to spallation neutron sources proposed or under development, but also to other projects in accelerator-driven transmutation technologies such as the production of tritium.

Sommer, W.F.

1995-12-01T23:59:59.000Z

102

Gamma/neutron analysis for SNM signatures at high-data rates(greater than 107 cps) for single-pulse active interrogation  

SciTech Connect

We are developing a high data gamma/neutron spectrometer suitable for active interrogation of special nuclear materials (SNM) activated by a single burst from an intense source. We have tested the system at Naval Research Laboratory's (NRL) Mercury pulsed-power facility at distances approaching 10 meters from a depleted uranium (DU) target. We have found that the gamma-ray field in the target room 'disappears' 10 milliseconds after the x-ray flash, and that gamma ray spectroscopy will then be dominated by isomeric states/beta decay of fission products. When a polyethylene moderator is added to the DU target, a time-dependent signature of the DU is produced by thermalized neutrons. We observe this signature in gamma-spectra measured consecutively in the 0.1-1.0 ms time range. These spectra contain the Compton edge line (2.2 MeV) from capture in hydrogen, and a continuous high energy gamma-spectrum from capture or fission in minority constituents of the DU.

Forman L.; Dioszegi, I.; Salwen, C.

2011-04-26T23:59:59.000Z

103

INGRID: an intense neutron generator for radiation-induced damage studies in the CTR materials program  

SciTech Connect

The proposal is broken into the following chapters: (1) the need for a neutron irradiation facility, (2) characteristics of the neutron source, (3) the accelerator, (4) the lithium target source, (5) buildings, utilities, and experimental facilities, and (6) project management, schedule, and costs. (MOW)

Saltmarsh, M.J.; Worsham, R.E. (eds.)

1976-01-01T23:59:59.000Z

104

Method and apparatus for measuring the intensity and phase of one or more ultrashort light pulses and for measuring optical properties of materials  

DOE Patents (OSTI)

The intensity and phase of one or more ultrashort light pulses are obtained using a non-linear optical medium. Information derived from the light pulses is also used to measure optical properties of materials. Various retrieval techniques are employed. Both "instantaneously" and "non-instantaneously" responding optical mediums may be used.

Trebino, Rick P. (Livermore, CA); DeLong, Kenneth W. (Livermore, CA)

1996-01-01T23:59:59.000Z

105

~PULSE  

~PULSE March6,2009 25MAQ''oq ""''''7", "- 'I""i'H!"i:II OfficeoftheAssistantGeneralCounsel 'E. forTechnologyTransferandIntellectualProperty U.S.DepartmentofEnergy

106

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma  

E-Print Network (OSTI)

2002). J.D. Lawson, ďPhysics of Charged Particles BeamsĒ, (B. Kusse, J. Moschella, Physics of Fluids 30 , 245 (1987).Davidson and H. Qin, ď Physics of Intense Charged Particle

Kaganovich, I.D.

2010-01-01T23:59:59.000Z

107

High-order harmonic generation with Rydberg atoms by using an intense few-cycle pulse  

Science Conference Proceedings (OSTI)

We demonstrate that high-order harmonic generation (HHG) with both high cutoff frequency and high conversion efficiency can be realized by using a Rydberg atom in a few-cycle laser pulse. This is because a Rydberg state has a large electron orbital radius and small binding energy; therefore an electron in the Rydberg state can be ionized easily and accelerated directly toward the core under the interaction of a few-cycle laser pulse, leading to emission of harmonic photons. In this case, the tunneling process of the electron is not involved and, hence, the conversion efficiency and the cutoff frequency of harmonic generation can be higher than that predicted by the conventional three-step model.

Zhai Zhen; Fu Panming; Wang Bingbing [Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Zhu Qiren [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); Chen Jing [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Yan Zongchao [Department of Physics, University of New Brunswick, P.O. Box 4400, Fredericton, New Brunswick E3B 5A3 (Canada)

2011-04-15T23:59:59.000Z

108

SNS | Spallation Neutron Source | ORNL  

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

SNS SNS Instruments Working with SNS Contact Us User Program Manager Laura Morris Edwards 865.574.2966 Spallation Neutron Source Home | User Facilities | SNS SNS | Spallation Neutron Source SHARE SNS is an accelerator-based neutron source in Oak Ridge, Tennessee, USA. This one-of-a-kind facility provides the most intense pulsed neutron beams in the world for scientific research and industrial development. The 80-acre SNS site is located on Chestnut Ridge and is part of Oak Ridge National Laboratory. Although most people don't know it, neutron scattering research has a lot to do with our everyday lives. For example, things like medicine, food, electronics, and cars and airplanes have all been improved by neutron scattering research. Neutron research also helps scientists improve materials used in a

109

Ion beam surface treatment: A new technique for thermally modifying surfaces using intense, pulsed ion beams  

Science Conference Proceedings (OSTI)

The emerging capability to produce high average power (10--300 kW) pulsed ion beams at 0.2{minus}2 MeV energies is enabling us to develop a new, commercial-scale thermal surface treatment technology called Ion Beam Surface Treatment (IBEST). This new technique uses high energy, pulsed ({le}500 ns) ion beams to directly deposit energy in the top 1--20 micrometers of the surface of any material. The depth of treatment is controllable by varying the ion energy and species. Deposition of the energy in a thin surface layer allows melft of the layer with relatively small energies (1--10J/cm2) and allows rapid cooling of the melted layer by thermal conduction into the underlying substrate. Typical cooling rates of this process (109 K/sec) are sufficient to cause amorphous layer formation and the production of non-equilibrium microstructures (nanocrystalline and metastable phases). Results from initial experiments confirm surface hardening, amorphous layer and nanocrystalline grain size formation, corrosion resistance in stainless steel and aluminum, metal surface polishing, controlled melt of ceramic surfaces, and surface cleaning and oxide layer removal as well as surface ablation and redeposition. These results follow other encouraging results obtained previously in Russia using single pulse ion beam systems. Potential commercialization of this surface treatment capability is made possible by the combination of two new technologies, a new repetitive high energy pulsed power capability (0.2{minus}2MV, 25--50 kA, 60 ns, 120 Hz) developed at SNL, and a new repetitive ion beam system developed at Cornell University.

Stinnett, R.W.; Buchheit, R.G.; Neau, E.L. [and others

1995-08-01T23:59:59.000Z

110

Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses  

Science Conference Proceedings (OSTI)

We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction of the molecular electric dipole moment. These findings are explained by a tunneling model invoking the laser-induced Stark shifts associated with the dipoles and polarizabilities of the molecule and its unrelaxed cation. The focus of the present article is to understand the strong-field ionization of one-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron emission in nodal planes of molecular orbitals.

Dimitrovski, Darko; Abu-samha, Mahmoud; Madsen, Lars Bojer; Filsinger, Frank; Meijer, Gerard; Kuepper, Jochen [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Holmegaard, Lotte; Kalhoej, Line [Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Nielsen, Jens H. [Department of Physics, Aarhus University, DK-8000 Aarhus C (Denmark); Stapelfeldt, Henrik [Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark)

2011-02-15T23:59:59.000Z

111

Preparation of diamond-like carbon and boron nitirde films by high-intensity pulsed ion beam deposition  

SciTech Connect

Intense ion beams (300-keV C{sup +}, O{sup +}, and H{sup +}, 20--30 kA, 50 to 400-ns pulsewidth, up to 0.3-Hz repetition rate) were used to prepare diamond-like carbon (DLC) and boron nitride (BN) films. Deposition rates of up to 25{plus_minus}5 nm/pulse were obtained with instantaneous rates exceeding 1 mm/s. Most films were uniform, light brown, translucent, and nonporous with some micron-size particulates. Raman and parallel electron energy loss spectroscopy indicated the presence of DLC. The films possessed favorable electron field-emission characteristics desirable for cold-cathode displays. Transmission electron microscopy (TEM) and transmission electron diffraction (TED) revealed that the C films contained diamond crystals with 25 to 125-nm grain size. BN films were composed of hexagonal, cubic and wurtzite phases.

Rej, D.J.; Davis, H.A. [Los Alamos National Lab., NM (United States); Remnev, G.E. [Tomsk Polytechnic Univ., Tomsk (Russian Federation). Nuclear Physics Institute.] [and others

1995-05-01T23:59:59.000Z

112

An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility  

E-Print Network (OSTI)

Predicting the consequences of highly energetic particle beams impacting protection devices as collimators or high power target stations is a fundamental issue in the design of state-of-the-art facilities for high-energy particle physics. These complex dynamic phenomena can be successfully simulated resorting to highly non-linear numerical tools (Hydrocodes). In order to produce accurate results, however, these codes require reliable material constitutive models that, at the extreme conditions induced by a destructive beam impact, are scarce and often inaccurate. In order to derive or validate such models a comprehensive, first-of-its-kind experiment has been recently carried out at CERN HiRadMat facility: performed tests entailed the controlled impact of intense and energetic proton pulses on a number of specimens made of six different materials. Experimental data were acquired relying on embedded instrumentation (strain gauges, temperature probes and vacuum sensors) and on remote-acquisition devices (laser ...

Bertarelli, A; Boccone, V; Carra, F; Cerutti, F; Charitonidis, N; Charrondiere, C; Dallocchio, A; Fernandez Carmona, P; Francon, P; Gentini, L; Guinchard, M; Mariani, N; Masi, A; Marques dos Santos, S D; Moyret, P; Peroni, L; Redaelli, S; Scapin, M

2013-01-01T23:59:59.000Z

113

Theory and Analysis of the Feynman-Alpha Method for Deterministically and Randomly Pulsed Neutron Sources  

E-Print Network (OSTI)

contract FIKW-CT-2000-00063. REFERENCES 1. R. UHRIG, Random Noise Techniques in Nuclear Reactor Systems. Conf. New Frontiers of Nuclear Technology: Reactor Phys- ics (PHYSOR 2002), Seoul, Korea, October 7 Determination in Accelerator Driven Nuclear Reactors by Statistics from Neutron Detectors ~Feynman-Alpha Method

P√°zsit, Imre

114

EIS-0247: Construction and Operation of the Spallation Neutron Source |  

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

247: Construction and Operation of the Spallation Neutron 247: Construction and Operation of the Spallation Neutron Source EIS-0247: Construction and Operation of the Spallation Neutron Source SUMMARY The United States needs a high-flux, short- pulsed neutron source to provide its scientific and industrial research communities with a much more intense source of pulsed neutrons for neutron scattering research than is currently available. This source would assure the availability of a state-of-the-art neutron research facility in the United States in the decades ahead. This facility would be used to conduct research in areas such as materials science, condensed matter physics, the molecular structure of biological materials, properties of polymers and complex fluids, and magnetism. In addition to creating new scientific and

115

SINGLE CRYSTAL NEUTRON DIFFRACTION.  

SciTech Connect

Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

KOETZLE,T.F.

2001-03-13T23:59:59.000Z

116

Facilities and Capabilities | Neutron Science | ORNL  

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

Isotope Reactor and the Spallation Neutron Source. The continuous neutron source at HFIR and the pulsed neutron source at SNS complement each other well and, along with their...

117

Spallation Neutron Source The Spallation Neutron Source (SNS)  

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

F/gim F/gim Spallation Neutron Source The Spallation Neutron Source (SNS) gives researchers more detailed informa- tion on the structure and dynamics of physical and biological materials than ever before possible. This accelerator- based facility provides the most intense pulsed neutron beams in the world. Scien- tists are able to count scattered neutrons, measure their energies and the angles at which they scatter, and map their final positions. SNS enables measurements of greater sensitivity, higher speed, higher resolution, and in more complex sample environments than have been possible at existing neutron facilities. Future Growth SNS was designed from the outset to accommodate a second target station, effectively doubling the capacity of the

118

Non-invasive Field Measurements of Soil Water Content Using a Pulsed 14 MeV Neutron Generator  

DOE Green Energy (OSTI)

Current techniques of soil water content measurement are invasive and labor-intensive. Here, we demonstrate that an in situ soil carbon (C) analyzer with a multi-elemental analysis capability, developed for studies of terrestrial C sequestration, can be used concurrently to non-invasively measure the water content of large-volume ({approx}0.3 m{sup 3}) soil samples. Our objectives were to investigate the correlations of the hydrogen (H) and oxygen (O) signals with water to the changes in the soil water content in laboratory experiments, and in an agricultural field. Implementing prompt gamma neutron activation analyses we showed that in the field, the signal from the H nucleus better indicates the soil water content than does that from the O nucleus. Using a field calibration, we were able to use the H signal to estimate a minimum detectable change of {approx}2% volumetric water in a 0-30 cm depth of soil.

Mitra S.; Wielopolski L.; Omonode, R.; Novak, J.; Frederick, J.; Chan, A.

2012-01-26T23:59:59.000Z

119

Guiding of Intense Laser Pulses in Efficient End-pumped Plasma Channels Generated by Self-guiding in Ar and H2 Clusters  

Science Conference Proceedings (OSTI)

We demonstrate that self-guiding of intense short pulses in clustered gases can be utilized to generate long plasma channels, which upon expansion form waveguides suitable for propagation of laser pulses at high intensity. This scheme has several advantages over waveguide-generation in non-clustered gases. The absorption of energy by the target depends on the size of the clusters and not on the average density of the gas, which allows greater control of the density encountered by the guided pulse. In particular, electron densities less than 1018 cm-3 are feasible. Moreover, since clusters absorb sub-picosecond pulses very efficiently, channel generation by an auxiliary long-pulse laser is no longer necessary and a considerably simpler setup suffices. The problem of taper at the channel entrance, an old bugbear of side-pumped waveguides in gases, is shown to be significantly reduced. Evidence will be presented of waveguide generation in gases of argon and hydrogen clusters, using different cryogenic sources. A slit source is used for argon, and waveguides 1017 Wcm-2 were guided. The results of a propagation code suggest that even longer channels are well within experimental reach. Argon, however, has the disadvantage that a super-intense pulse would likely produce further ionization, and hence suffer ionization induced defocusing. Hydrogen clusters, which can easily be fully ionized, were formed using a more efficient conical nozzle cooled to 90 K, limiting maximum waveguide lengths to < 3 mm. Though these channels are short, there is no obvious reason why a longer target would not allow longer waveguides to be generated, and the experiments demonstrate the utility of this novel scheme.

Kumarappan, V.; Kim, K.-Y.; Milchberg, H.M. [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States); Antonsen, T.M. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742 (United States)

2004-12-07T23:59:59.000Z

120

Spectral broadening and compression of high-intensity laser pulses in quasi-periodic systems with Kerr nonlinearity  

SciTech Connect

We report the results of theoretical studies and numerical simulations of optical high-power pulse compression systems based on the spectral broadening in a Kerr nonlinear medium with subsequent pulse compression in a dispersive delay line. It is shown that the effective spectral broadening requires suppressing a smallscale instability arising due to self-focusing, which is possible in quasi-periodic systems consisting of a nonlinear medium and optical relay telescopes transmitting images of the laser beam through the system. The numerical calculations have shown the possibility of broadening the spectrum, followed by 15-fold pulse compression until the instability is excited. (control of laser radiation parameters)

Vlasov, Sergei N; Koposova, E V; Yashin, V E

2012-11-30T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Photoionization of hydrogen atom by coherent intense high-frequency short laser pulses: Direct propagation of electron wave packets on enormous spatial grids  

E-Print Network (OSTI)

The time-dependent Schr\\"{o}dinger equation for the hydrogen atom and its interaction with coherent intense high-frequency short laser pulses is solved numerically exactly by employing the code implemented for the multi-configurational time-dependent Hartree-Fock (MCTDHF) method. Thereby, the wavefunction is followed in space and time for times longer than the pulse duration. Results are explicitly shown for 3 and 10 fs pulses. Particular attention is paid to identifying the effect of dynamic interference of photoelectrons emitted with the same kinetic energy at different times during the rising and falling sides of the pulse predicted in [\\emph{Ph.V. Demekhin and L.S. Cederbaum}, Phys. Rev. Lett. \\textbf{108}, 253001 (2012)]. In order to be able to see the dynamic interference pattern in the computed electron spectra, the photoelectron wave packet has to be propagated over long distances. Clearly, complex absorption potentials often employed to compute spectra of emitted particles cannot be used to detect dy...

Demekhin, Philipp V; Cederbaum, Lorenz S

2013-01-01T23:59:59.000Z

122

Analysis of the burping behavior of the cold solid methane moderator at IPNS (Intense Pulsed Neutron Source)  

SciTech Connect

Examination of the cold solid methane moderator at IPNS (Model II) revealed that a circumferential weld failed due to high internal pressure, such as would be caused by thermal expansion of solid methane or the release of Hydrogen gas upon spontaneous heating. This weld is the main object of current attention for a design of a replacement. The present paper deals with the processes which lead to the burping behavior and outlines the analysis of some of the consequences. The purpose is to determine conditions under which the system can operate at the lowest possible temperature, avoiding the problems experienced to data.

Carpenter, J.M.; Walter, U.

1986-01-01T23:59:59.000Z

123

(International Panel on 14 MeV Intense Neutron Source Based on Accelerators for Fusion Materials Study)  

SciTech Connect

Both travelers were members of a nine-person US delegation that participated in an international workshop on accelerator-based 14 MeV neutron sources for fusion materials research hosted by the University of Tokyo. Presentations made at the workshop reviewed the technology developed by the FMIT Project, advances in accelerator technology, and proposed concepts for neutron sources. One traveler then participated in the initial meeting of the IEA Working Group on High Energy, High Flux Neutron Sources in which efforts were begun to evaluate and compare proposed neutron sources; the Fourth FFTF/MOTA Experimenters' Workshop which covered planning and coordination of the US-Japan collaboration using the FFTF reactor to irradiate fusion reactor materials; and held discussions with several JAERI personnel on the US-Japan collaboration on fusion reactor materials.

Thoms, K.R.; Wiffen, F.W.

1991-02-14T23:59:59.000Z

124

Generation of Femtosecond Electron And Photon Pulses  

SciTech Connect

Femtosecond (fs) electron and photon pulses become a tool of increasing importance to study dynamics in ultrafast processes. Such short electron pulses can be generated from a system consisting of a thermionic-cathode RF-gun and a magnetic bunch compressor. The fs electron pulses can be used directly or used as a source to produce equally short electromagnetic radiation pulses via certain kind of radiation production processes. At the Fast Neutron Research Facility (FNRF), Thailand, we are especially interested in production of radiation in Farinfrared and X-ray regime. In the far-infrared wavelengths, the radiation emitted from fs electron pulses is emitted coherently resulting high intensity radiation. In the X-ray regime, development of fs X-ray sources is crucial for application in ultrafast sciene.

Thongbai, C.; Jinamoon, V.; Kangrang, M.; Kusoljariyakul, K.; Rimjaem, S.; Saisut, J.; Vilaithong, T.; Rhodes, M.W.; Wichaisirimongkol, P.; /Chiang Mai U.; Wiedemann, H.; /SLAC

2006-03-17T23:59:59.000Z

125

Facilities | ORNL Neutron Sciences  

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

Isotope Reactor. The pulsed neutron source at SNS and the continuous neutron source at HFIR complement each other well and, along with their state-of-the-art instruments, provide...

126

Inverse Bremsstrahlung Stabilization of Noise in the Generation of Ultra-short Intense Pulses by Backward Raman Amplification  

DOE Green Energy (OSTI)

Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the sub-critical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation.

Richard L. Berger; Daniel S. Clark Andrei Solodov; Ernest J. Valeo; Nathaniel J. Fisch

2003-11-06T23:59:59.000Z

127

Neutron Scattering Facilities 1982  

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

NEUTRON SOURCES NEUTRON SOURCES ÔĀ¨Types of Sources ÔĀ¨U.S. Sources Available for Users ÔĀ¨Plans for the Future ÔĀ¨The Neutron Scattering Society of America (NSSA) SNS/ANL School on Neutron and x-Ray Scattering, June 2011 Jim Rhyne Lujan Neutron Scattering Center Los Alamos National Lab. What do we need to do neutron scattering? * Neutron Source - produces neutrons * Diffractometer or Spectrometer - Allows neutrons to interact with sample - Sorts out discrete wavelengths by monochromator (reactor) or by time of flight (pulse source) - Detectors pick up neutrons scattered from sample * Analysis methods to determine material properties * Brain power to interpret results Sources of neutrons for scattering * Nuclear Reactor - Neutrons produced from fission of 235 U - Fission spectrum neutrons

128

Ionization of one- and three-dimensionally-oriented asymmetric-top molecules by intense circularly polarized femtosecond laser pulses  

SciTech Connect

We present a combined experimental and theoretical study on strong-field ionization of a three-dimensionally-oriented asymmetric top molecule, benzonitrile (C{sub 7}H{sub 5}N), by circularly polarized, nonresonant femtosecond laser pulses. Prior to the interaction with the strong field, the molecules are quantum-state selected using a deflector and three-dimensionally (3D) aligned and oriented adiabatically using an elliptically polarized laser pulse in combination with a static electric field. A characteristic splitting in the molecular frame photoelectron momentum distribution reveals the position of the nodal planes of the molecular orbitals from which ionization occurs. The experimental results are supported by a theoretical tunneling model that includes and quantifies the splitting in the momentum distribution. The focus of the present article is to understand strong-field ionization from 3D-oriented asymmetric top molecules, in particular the suppression of electron emission in nodal planes of molecular orbitals. In the preceding article [Dimitrovski et al., Phys. Rev. A 83, 023405 (2011)] the focus is to understand the strong-field ionization of one-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons.

Hansen, Jonas L. [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); Holmegaard, Lotte; Kalhoej, Line; Kragh, Sofie Louise [Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Stapelfeldt, Henrik [Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); Filsinger, Frank; Meijer, Gerard; Kuepper, Jochen; Dimitrovski, Darko; Abu-samha, Mahmoud; Martiny, Christian Per Juul; Madsen, Lars Bojer [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)

2011-02-15T23:59:59.000Z

129

High intensity performance of the Brookhaven AGS  

SciTech Connect

Experience and results from recent high intensity proton running periods of the Brookhaven AGS, during which a record intensity for a proton synchrotron of 6.3 x 10{sup 13} protons/pulse was reached, is presented. This high beam intensity allowed for the simultaneous operation of three high precision rare kaon decay experiments. The record beam intensities were achieved after the 1.5 GeV Booster was commissioned and a transition jump system, a powerful transverse damper, and an rf upgrade in the AGS were completed. Recently even higher intensity proton synchrotrons are studied for neutron spallation sources or proton driver for a muon collider. Implications of the experiences from the AGS to these proposals and also possible future upgrades for the AGS are discussed.

Brennan, J.M.; Roser, T.

1996-07-01T23:59:59.000Z

130

LANSCE | Lujan Neutron Scattering Center  

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

Department of Energy, National Office of Science Department of Energy, National Office of Science science.energy.gov Department of Energy, National Nuclear Security Administration nnsa.energy.gov Lujan Neutron Scattering Center Logo Lujan Center Mission The Lujan Center delivers science by exploiting the unique characteristics of intense beams of pulsed neutrons for academia, national security, and industry. Lujan Center Vision The Lujan Center will operate a world class user program in the service of the nation. Lujan Center scientists will be recognized for their leadership and innovation in neutron scattering. Lujan Center at LANSCE The Lujan Center is one of five user facilities supported by the LANSCE accelerator which is stewarded. Funding to operate 10 instruments in a national user program is provided by the Department of Energy's Office of

131

Effect of the change in the load resistance on the high voltage pulse transformer of the intense electron-beam accelerators  

Science Conference Proceedings (OSTI)

A high voltage pulse transformer (HVPT) is usually used as a charging device for the pulse forming line (PFL) of intense electron-beam accelerators (IEBAs). Insulation of the HVPT is one of the important factors that restrict the development of the HVPT. Until now, considerable effort has been focused on minimizing high field regions to avoid insulation breakdown between windings. Characteristics of the HVPT have been widely discussed to achieve these goals, but the effects of the PFL and load resistance on HVPT are usually neglected. In this paper, a HVPT is used as a charging device for the PFL of an IEBA and the effect of the change in the load resistance on the HVPT of the IEBA is presented. When the load resistance does not match the wave impedance of the PFL, a high-frequency bipolar oscillating voltage will occur, and the amplitude of the oscillating voltage will increase with the decrease in the load resistance. The load resistance approximates to zero and the amplitude of the oscillating voltage is much higher. This makes it easier for surface flashover along the insulation materials to form and decrease the lifetime of the HVPT.

Cheng Xinbing; Liu Jinliang; Qian Baoliang; Zhang Yu; Zhang Hongbo [College of Photoelectrical Science and Engineering, National University of Defense Technology, Hunan 410073 (China)

2009-11-15T23:59:59.000Z

132

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields  

Science Conference Proceedings (OSTI)

The design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ion driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B {approx} 100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasma electrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electron dynamics strongly affected by a weak applied magnetic field.

Dorf, Mikhail A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Davidson, Ronald C.; Kaganovich, Igor D.; Startsev, Edward A. [Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2012-05-15T23:59:59.000Z

133

Characterization of deuterium beam operation on RHEPP-1 for future neutron generation applications.  

Science Conference Proceedings (OSTI)

We investigate the potential for neutron generation using the 1 MeV RHEPP-1 intense pulsed ion beam facility at Sandia National Laboratories for a number of emerging applications. Among these are interrogation of cargo for detection of special nuclear materials (SNM). Ions from single-stage sources driven by pulsed power represent a potential source of significant neutron bursts. While a number of applications require higher ion energies (e.g. tens of MeV) than that provided by RHEPP-1, its ability to generate deuterium beams allow for neutron generation at and below 1 MeV. This report details the successful generation and characterization of deuterium ion beams, and their use in generating up to 3 x 10{sup 10} neutrons into 4{pi} per 5kA ion pulse.

Schall, Michael (University of New Mexico, Albuquerque, NM); Cooper, Gary Wayne (University of New Mexico, Albuquerque, NM); Renk, Timothy Jerome

2009-12-01T23:59:59.000Z

134

Laser fusion pulse shape controller  

DOE Patents (OSTI)

An apparatus for controlling the pulse shape, i.e., the pulse duration and intensity pattern, of a pulsed laser system, and which is particularly well adapted for controlling the pellet ignition pulse in a laser-driven fusion reaction system. The apparatus comprises a laser generator for providing an optical control pulse of the shape desired, a pulsed laser triggered by the control pulse, and a plurality of optical Kerr-effect gates serially disposed at the output of the pulsed laser and selectively triggered by the control pulse to pass only a portion of the pulsed laser output generally corresponding in shape to the control pulse.

Siebert, Larry D. (Ann Arbor, MI)

1977-01-01T23:59:59.000Z

135

Core Vessel Insert Handling Robot for the Spallation Neutron Source  

Science Conference Proceedings (OSTI)

The Spallation Neutron Source provides the world's most intense pulsed neutron beams for scientific research and industrial development. Its eighteen neutron beam lines will eventually support up to twenty-four simultaneous experiments. Each beam line consists of various optical components which guide the neutrons to a particular instrument. The optical components nearest the neutron moderators are the core vessel inserts. Located approximately 9 m below the high bay floor, these inserts are bolted to the core vessel chamber and are part of the vacuum boundary. They are in a highly radioactive environment and must periodically be replaced. During initial SNS construction, four of the beam lines received Core Vessel Insert plugs rather than functional inserts. Remote replacement of the first Core Vessel Insert plug was recently completed using several pieces of custom-designed tooling, including a highly complicated Core Vessel Insert Robot. The design of this tool are discussed.

Graves, Van B [ORNL; Dayton, Michael J [ORNL

2011-01-01T23:59:59.000Z

136

Neutron Spin Filters  

Science Conference Proceedings (OSTI)

... many nice scientific results from the use of high intensity polarized neutrons ... Electromagnetic radiation of exactly the right energy can exert a sort of ...

2013-03-12T23:59:59.000Z

137

Neutron Scattering Template  

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

Acknowledgements The graphics used on the Neutron Scattering Web Pages were designed by Tami Sharley (Information and Publishing Services Division) and Jack Carpenter (Intense...

138

Personnel electronic neutron dosimeter  

DOE Patents (OSTI)

A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

Falk, R.B.; Tyree, W.H.

1982-03-03T23:59:59.000Z

139

Femtosecond Electron and Photon Pulses Facility in Thailand  

SciTech Connect

Femtosecond electron and photon pulses facility has been established as SURIYA project at the Fast Neutron Research Facility (FNRF). Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet as an magnetic bunch compressor, and a linear accelerator as a post acceleration section. Femtosecond electron pulses can be used directly or used as a source to produce equally short electromagnetic (EM) radiation pulses via certain kind of radiation production processes. At SURIYA project, we are interested especially in production of radiation in Far-infrared (FIR) regime. At these wavelengths, the radiation from femtosecond electron pulses is emitted coherently resulting in high intensity radiation. Overview of the facility, the generation of femtosecond electron bunches, the theoretical background of coherent transition radiation and the recent experimental results will be presented and discussed in this paper.

Rimjaem, S.; Thongbai, C.; Jinamoon, V.; Kangrang, N.; Kusoljariyakul, K.; Saisut, J.; Vilaithong, T. [Fast Neutron Research Facility (FNRF), Physics Department, Chiang Mai University, Chiang Mai 50200 (Thailand); Rhodes, M. W.; Wichaisirimongkol, P. [Institute for Science Technology Research and Development, Chiang Mai University, Chiang Mai 50200 (Thailand)

2007-01-19T23:59:59.000Z

140

Energy distribution of nonequilibrium electrons and optical phonons in GaAs under band-to-band pumping by intense short pulses of light  

SciTech Connect

Deviation from the Fermi distribution of nonequilibrium electrons and distribution of 'hot' optical phonons in GaAs under band-to-band pumping by picosecond pulses of light are calculated.

Altybaev, G. S.; Kumekov, S. E., E-mail: skumekov@mail.ru; Mahmudov, A. A. [Satpaev Kazakh National Technical University (Kazakhstan)

2009-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

World record neutron beam at Los Alamos National Laboratory  

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

World record neutron beam at LANL World record neutron beam at Los Alamos National Laboratory Scientists have created the largest neutron beam ever made by a short-pulse laser,...

142

The Intense Radiation Gas  

E-Print Network (OSTI)

We present a new dispersion relation for photons that are nonlinearly interacting with a radiation gas of arbitrary intensity due to photon-photon scattering. It is found that the photon phase velocity decreases with increasing radiation intensity, it and attains a minimum value in the limit of super-intense fields. By using Hamilton's ray equations, a self-consistent kinetic theory for interacting photons is formulated. The interaction between an electromagnetic pulse and the radiation gas is shown to produce pulse self-compression and nonlinear saturation. Implications of our new results are discussed.

M. Marklund; P. K. Shukla; B. Eliasson

2004-10-14T23:59:59.000Z

143

Neutronics studies for a long-wavelength target station at SNS.  

DOE Green Energy (OSTI)

The Spallation Neutron Source (SNS), under construction at Oak Ridge National Laboratory, will be the premier facility for neutron scattering studies in the United States. From the outset the SNS can achieve additional flexibility and accommodate a broader range of scientific investigation than would be possible with only the High Power Target Station by utilizing two target stations, each operating under a separate set of conditions and optimized for a certain class of instruments. A second target station, termed the Long-Wavelength Target Station (LWTS), would operate at a lower pulse rate (e.g., 10 vs. 60 Hz) and utilize very cold moderators to emphasize low-energy (long wavelength) neutrons. The LWTS concept discussed here obtains the highest low-energy fluxes possible for neutron scattering instruments by using a heavy-water-cooled solid tungsten target with two moderators in slab geometry and one in a front wing position. The primary focus has been on solid methane moderators, with liquid methane and hydrogen also considered. We used MCNPX to conduct a series of optimization and sensitivity studies to help determine the optimal neutronic parameters of the LWTS. We compared different options based on the thermal and epithermal fluxes as determined by fitting the spectral intensity of the moderators with a Maxwellian peak and a modified Westcott function. The primary parameters are the moderator positions and composition and the target size. We report results for spectral intensity, pulse shapes, high-energy neutron emission, heating profiles in the target, and target activation.

Micklich, B. J.; Iverson, E. B.; Carpenter, J. M.

2001-09-21T23:59:59.000Z

144

First time nuclear material detection by one short-pulse-laser...  

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

Technical Articles First time nuclear material detection by one short-pulse-laser-driven neutron source First time nuclear material detection by one short-pulse-laser-driven...

145

Moderators - Instrument Support | ORNL Neutron Sciences  

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

Moderators Moderators Detailed design of scattering instruments requires detailed knowledge of the neutron beam emitted from the moderator in question. We are currently providing moderator performance estimates based on the result of detailed Monte Carlo simulations of the entire target system. These simulations are being performed for both the High Power Target Station (HPTS) and the Long Wavelength Target Station (LWTS), and have been performed for the Intense Pulsed Neutron Source (IPNS) in the same manner. We make the IPNS source files available as a means to benchmark instrument simulation codes. These files follow a particular "source file format" which will adapt to the changing needs of instrument simulation as necessary. We also provide worked examples showing how to use the information in the source files

146

The Extended Q-Range Small Angle Neutron Scattering ...  

Science Conference Proceedings (OSTI)

Abstract Scope, The Extended Q-Range Small Angle Neutron Scattering Diffractometer (EQ-SANS) at the Spallation Neutron Source (SNS) is a high intensity†...

147

Detectors for Energy-Resolved Fast Neutron Imaging  

E-Print Network (OSTI)

Two detectors for energy-resolved fast-neutron imaging in pulsed broad-energy neutron beams are presented. The first one is a neutron-counting detector based on a solid neutron converter coupled to a gaseous electron multiplier (GEM). The second is an integrating imaging technique, based on a scintillator for neutron conversion and an optical imaging system with fast framing capability.

V. Dangendorf; A. Breskin; R. Chechik; G. Feldman; M. B. Goldberg; O. Jagutzki; C. Kersten; G. Laczko; I. Mor; U. Spillman; D. Vartsky

2004-03-25T23:59:59.000Z

148

Molecular pulses: Population inversion with positively chirped short pulses  

E-Print Network (OSTI)

Molecular pulses: Population inversion with positively chirped short pulses Jianshu Cao of molecular systems can be achieved with intense positively chirped broadband laser pulses. To provide and a four-level model is designed to demonstrate for molecular systems the correlation between the sign

Cao, Jianshu

149

Neutron Resonance Transmission Analysis (NRTA): Initial Studies of a Method for Assaying Plutonium in Spent Fuel  

SciTech Connect

Neutron Resonance Transmission Analysis (NRTA) is an analytical technique that uses neutrons to assay the isotopic content of bulk materials. The technique uses a pulsed accelerator to produce an intense, short pulse of neutrons in a time-of-flight configuration. These neutrons, traveling at different speeds according to their energy, can be used to interrogate a spent fuel (SF) assembly to determine its plutonium content. Neutron transmission through the assembly is monitored as a function of neutron energy (time after the pulse), similar to the way neutron cross-section data is often collected. The transmitted neutron intensity is recorded as a function of time, with faster (higher-energy) neutrons arriving first and slower (lower-energy) neutrons arriving later. The low-energy elastic scattering and absorption resonances of plutonium and other isotopes modulate the transmitted neutron spectrum. Plutonium content in SF can be determined by analyzing this attenuation. Work is currently underway at Idaho National Laboratory, as a part of United States Department of Energy's Next Generation Safeguards Initiative (NGSI), to investigate the NRTA technique and to assess its feasibility for quantifying the plutonium content in SF and for determining the diversion of SF pins from assemblies. Preliminary results indicate that NRTA has great potential for being able to assay intact SF assemblies. Operating in the 1-40 eV range, it can identify four plutonium isotopes (239, 240, 241, & 242Pu), three uranium isotopes (235, 236, & 238U), and six resonant fission products (99Tc, 103Rh, 131Xe, 133Cs, 145Nd, and 152Sm). It can determine the areal density or mass of these isotopes in single- or multiple-pin integral transmission scans. Further, multiple observables exist to allow the detection of material diversion (pin defects) including fast-neutron and x-ray radiography, gross-transmission neutron counting, plutonium resonance absorption analysis, and fission-product resonance absorption analysis. Initial benchmark modeling has shown excellent agreement with previously published experimental data for measurements of individual SF pins where plutonium assays were experimentally demonstrated to have a precision of better than 3%.

David L. Chichester; James W. Sterbentz

2011-05-01T23:59:59.000Z

150

Scientific opportunities with advanced facilities for neutron scattering  

SciTech Connect

The present report documents deliberations of a large group of experts in neutron scattering and fundamental physics on the need for new neutron sources of greater intensity and more sophisticated instrumentation than those currently available. An additional aspect of the Workshop was a comparison between steady-state (reactor) and pulsed (spallation) sources. The main conclusions were: (1) the case for a new higher flux neutron source is extremely strong and such a facility will lead to qualitatively new advances in condensed matter science and fundamental physics; (2) to a large extent the future needs of the scientific community could be met with either a 5 x 10/sup 15/ n cm/sup -2/s/sup -1/ steady state source or a 10/sup 17/ n cm/sup -2/s/sup -1/ peak flux spallation source; and (3) the findings of this Workshop are consistent with the recommendations of the Major Materials Facilities Committee.

Lander, G.H.; Emery, V.J. (eds.)

1984-01-01T23:59:59.000Z

151

The Spallation Neutron Source: A powerful tool for materials research  

SciTech Connect

When completed in 2006, the Spallation Neutron Source (SNS) will use an accelerator to produce the most intense beams of pulsed neutrons in the world. This unique facility is being built by a collaboration of six US Department of Energy laboratories and will serve a diverse community of users drawn from academia, industry, and government labs. The project continues on schedule and within budget, with commissioning and installation of all systems going well. Installation of 14 state-of-the-art instruments is under way, and design work is being completed for several others. These new instruments will enable inelastic and elastic-scattering measurements across a broad range of science such as condensed-matter physics, chemistry, engineering materials, biology, and beyond. Neutron Science at SNS will be complemented by research opportunities at several other facilities under way at Oak Ridge National Laboratory.

Mason, Thom [ORNL; Anderson, Ian S [ORNL; Ankner, John Francis [ORNL; Egami, Takeshi [ORNL; Ekkebus, Allen E [ORNL; Herwig, Kenneth W [ORNL; Hodges, Jason P [ORNL; Horak, Charlie M [ORNL; Horton, Linda L [ORNL; Klose, Frank Richard [ORNL; Mesecar, Andrew D. [University of Illinois, Chicago; Myles, Dean A A [ORNL; Ohl, M. [Forschungszentrum Julich, Julich, Germany; Zhao, Jinkui [ORNL

2006-01-01T23:59:59.000Z

152

Polarisation response of a gas medium in the field of a high-intensity ultrashort laser pulse: high order Kerr nonlinearities or plasma electron component?  

SciTech Connect

The polarisation response of quantum systems modelling silver and xenon atoms in the field of a high-intensity femtosecond Ti : sapphire laser (photon energy h{omega} Almost-Equal-To 1.5 eV), has been investigated by direct numerical integration of the Schroedinger equation. The applicability ranges of the perturbation theory and polarisation expansion in powers of field are determined. The contributions of excited atoms and electrons in the continuous-spectrum states to the polarisation response at the fundamental frequency, which arise as a result of excitation and photoionisation, are analysed. It is shown that specifically ionisation changes the sign of dielectric susceptibility with an increase in radiation intensity for the systems under consideration. (interaction of laser radiation with matter. laser plasmas)

Volkova, E A; Popov, Alexander M; Tikhonova, O V [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2012-08-31T23:59:59.000Z

153

Efficient optical pulse stacker system  

SciTech Connect

Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

Seppala, Lynn G. (Pleasanton, CA); Haas, Roger A. (Pleasanton, CA)

1982-01-01T23:59:59.000Z

154

Intense ion beam generator  

DOE Patents (OSTI)

Methods and apparatus for producing intense megavolt ion beams are disclosed. In one embodiment, a reflex triode-type pulsed ion accelerator is described which produces ion pulses of more than 5 kiloamperes current with a peak energy of 3 MeV. In other embodiments, the device is constructed so as to focus the beam of ions for high concentration and ease of extraction, and magnetic insulation is provided to increase the efficiency of operation.

Humphries, Jr., Stanley (Ithaca, NY); Sudan, Ravindra N. (Ithaca, NY)

1977-08-30T23:59:59.000Z

155

Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper  

E-Print Network (OSTI)

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).

D. Akimov; A. Bernstein; P. Barbeau; P. Barton; A. Bolozdynya; B. Cabrera-Palmer; F. Cavanna; V. Cianciolo; J. Collar; R. J. Cooper; D. Dean; Y. Efremenko; A. Etenko; N. Fields; M. Foxe; E. Figueroa-Feliciano; N. Fomin; F. Gallmeier; I. Garishvili; M. Gerling; M. Green; G. Greene; A. Hatzikoutelis; R. Henning; R. Hix; D. Hogan; D. Hornback; I. Jovanovic; T. Hossbach; E. Iverson; S. R. Klein; A. Khromov; J. Link; W. Louis; W. Lu; C. Mauger; P. Marleau; D. Markoff; R. D. Martin; P. Mueller; J. Newby; J. Orrell; C. O'Shaughnessy; S. Pentilla; K. Patton; A. W. Poon; D. Radford; D. Reyna; H. Ray; K. Scholberg; V. Sosnovtsev; R. Tayloe; K. Vetter; C. Virtue; J. Wilkerson; J. Yoo; C. H. Yu

2013-10-01T23:59:59.000Z

156

AGS intensity upgrades  

SciTech Connect

After the successful completion of the AGS Booster and several upgrades of the AGS, a new intensity record of 6.3 x 10{sup 13} protons per pulse accelerated to 24 GeV was achieved. The high intensity slow-extracted beam program at the AGS typically serves about five production targets and about eight experiments including three rare Kaon decay experiments. Further intensity upgrades are being discussed that could increase the average delivered beam intensity by up to a factor of four.

Roser, T.

1995-12-01T23:59:59.000Z

157

Spatial resolution of a ?PIC-based neutron imaging detector  

E-Print Network (OSTI)

We present a detailed study of the spatial resolution of our time-resolved neutron imaging detector utilizing a new neutron position reconstruction method that improves both spatial resolution and event reconstruction efficiency. Our prototype detector system, employing a micro-pattern gaseous detector known as the micro-pixel chamber ({\\mu}PIC) coupled with a field-programmable-gate-array-based data acquisition system, combines 100{\\mu}m-level spatial and sub-{\\mu}s time resolutions with excellent gamma rejection and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. From data taken at the Materials and Life Science Experimental Facility within the Japan Proton Accelerator Research Complex (J-PARC), the spatial resolution was found to be approximately Gaussian with a sigma of 103.48 +/- 0.77 {\\mu}m (after correcting for beam divergence). This is a significant improvement over that achievable with our previous reconstruction method (334 +/- 13 {\\mu}m), and compares well with conventional neutron imaging detectors and with other high-rate detectors currently under development. Further, a detector simulation indicates that a spatial resolution of less than 60 {\\mu}m may be possible with optimization of the gas characteristics and {\\mu}PIC structure. We also present an example of imaging combined with neutron resonance absorption spectroscopy.

Joseph D. Parker; Masahide Harada; Kaori Hattori; Satoru Iwaki; Shigeto Kabuki; Yuji Kishimoto; Hidetoshi Kubo; Shunsuke Kurosawa; Yoshihiro Matsuoka; Kentaro Miuchi; Tetsuya Mizumoto; Hironobu Nishimura; Takayuki Oku; Tatsuya Sawano; Takenao Shinohara; Jun-ichi Suzuki; Atsushi Takada; Toru Tanimori; Kazuki Ueno

2013-05-16T23:59:59.000Z

158

Proton Driver Linac for the Frankfurt Neutron Source  

SciTech Connect

The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will deliver high neutron fluxes in the energy range of 1 to 500 keV. The Activation Mode provides a high averaged neutron flux created by a cw proton beam of up to 5 mA, while in the Compressor Mode intense neutron pulses of 1 ns length are formed with a repetition rate of up to 250 kHz. The Compressor Mode is well-suited for energy-dependent neutron capture measurements using the Time-of-Flight method in combination with a 4{pi} BaF{sub 2} detector array. The design of the proton driver linac for both operation modes is presented. This includes the volume type ion source, the ExB chopper located in the low energy section, the RFQ-IH combination for beam acceleration and the bunch compressor. Finally, the neutron production at the lithium-7 target and the resulting energy spectrum is described.

Wiesner, C.; Chau, L. P.; Dinter, H.; Droba, M.; Heilmann, M.; Joshi, N.; Maeder, D.; Metz, A.; Meusel, O.; Noll, D.; Podlech, H.; Ratzinger, U.; Reichau, H.; Schempp, A.; Schmidt, S.; Schweizer, W.; Volk, K.; Wagner, C. [Institut fuer Angewandte Physik, Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt/Main (Germany); Reifarth, R. [Institut fuer Angewandte Physik, Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt/Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Mueller, I.

2010-08-04T23:59:59.000Z

159

THERMAL NEUTRON BACKSCATTER IMAGING.  

DOE Green Energy (OSTI)

Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

2004-10-16T23:59:59.000Z

160

New NIST Detector Can 'See' Single Neutrons Over Broad ...  

Science Conference Proceedings (OSTI)

... record them over a range of intensities at least ... jump between the two lowest-energy states of ... the spread in recordable neutron intensity from faint ...

2011-10-26T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Thirteenth National School on Neutron and X-ray Scattering  

E-Print Network (OSTI)

Spallation-Driven Cold Neutron Sources Dr. Bradley J. Micklich Senior Physicist, Physics Division physics research Want neutron wavelengths about the dimensions of interest, or neutron energies that can using an intense source of longerwavelength neutrons ­ fundamental nuclear physics (neutron halflife

162

Ultrafast neutron detector  

DOE Patents (OSTI)

The invention comprises a neutron detector (50) of very high temporal resolution that is particularly well suited for measuring the fusion reaction neutrons produced by laser-driven inertial confinement fusion targets. The detector comprises a biased two-conductor traveling-wave transmission line (54, 56, 58, 68) having a uranium cathode (60) and a phosphor anode (62) as respective parts of the two conductors. A charge line and Auston switch assembly (70, 72, 74) launch an electric field pulse along the transmission line. Neutrons striking the uranium cathode at a location where the field pulse is passing, are enabled to strike the phosphor anode and produce light that is recorded on photographic film (64). The transmission line may be variously configured to achieve specific experimental goals.

Wang, Ching L. (Livermore, CA)

1987-01-01T23:59:59.000Z

163

Portable neutron spectrometer and dosimeter  

DOE Patents (OSTI)

The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Waechter, David A. (Los Alamos, NM); Erkkila, Bruce H. (Los Alamos, NM); Vasilik, Dennis G. (Los Alamos, NM)

1985-01-01T23:59:59.000Z

164

Glossary Term - Neutron Emission  

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

Neutron Previous Term (Neutron) Glossary Main Index Next Term (Niobe) Niobe Neutron Emission After neutron emission, an atom contains one less neutron. Neutron emission is one...

165

Method and apparatus for pulse stacking  

DOE Patents (OSTI)

An active pulse stacking system including an etalon and an electro-optical modulator apparatus combined with a pulse-forming network capable of forming and summing a sequence of time-delayed optical waveforms arising from, for example, a single laser pulse. The Pockels cell pulse stacker may attain an efficiency of about 2.6% while providing a controllable faster-than-exponential time rise in transmitted pulse intensity.

Harney, Robert C. (Livermore, CA)

1977-01-01T23:59:59.000Z

166

Neutron beam imaging at neutron spectrometers at Dhruva  

SciTech Connect

A low efficiency, 2-Dimensional Position Sensitive Neutron Detector based on delay line position encoding is developed. It is designed to handle beam flux of 10{sup 6}-10{sup 7} n/cm{sup 2}/s and for monitoring intensity profiles of neutron beams. The present detector can be mounted in transmission mode, as the hardware allows maximum neutron transmission in sensitive region. Position resolution of 1.2 mm in X and Y directions, is obtained. Online monitoring of beam images and intensity profile of various neutron scattering spectrometers at Dhruva are presented. It shows better dynamic range of intensity over commercial neutron camera and is also time effective over the traditionally used photographic method.

Desai, Shraddha S.; Rao, Mala N. [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2012-06-05T23:59:59.000Z

167

Versatile neutron NDA  

SciTech Connect

Non-destructive analysis (NDA) of bulk samples is a major tool in international safeguards and domestic MC&A. Yet, enhancements are needed to reduce inspection time, financial cost, and radiation exposure-while improving reliability and accuracy-particularly for mixtures of fissile and fertile isotopes. Perhaps the greatest remaining direction for NDA improvement is the development of a single controllable neutron source that would add versatility and capability. One of the primary prospects is a switchable radioactive neutron source (SRNS) that has been under advanced-concept development at Argonne with DOE funding. The SRNS would be in a sealed capsule that can be remotely switched on and off, or pulsed at a controllable rate. Li({alpha}, n) or Be({alpha}, n) reactions could give a choice of sub-threshold or hard-spectrum neutrons at yields ranging from 10{sup 4}/s to more than 10{sup 8}s. The SRNS would provide improved capabilities for (1) simultaneous or alternating interrogation with fast and slow neutrons, (2) detection of the first few seconds of delayed neutrons, (3) measurements in the presence of high neutron and/or gamma background, and (4) inspection of heterogeneous materials. When the neutrons are switched off, the source would be portable with vastly reduced shielding. Proof-of-concept with a single switchable plate has been established under laboratory conditions.

DeVolpi, A.

1995-07-01T23:59:59.000Z

168

Neutron beam characterization measurements at the Manuel Lujan Jr. neutron scattering center  

DOE Green Energy (OSTI)

We have measured the neutron beam characteristics of neutron moderators at the Manuel Lujan Jr. Neutron Scattering Center at LANSCE. The absolute thermal neutron flux, energy spectra and time emission spectra were measured for the high resolution and high intensity decoupled water, partially coupled liquid hydrogen and partially coupled water moderators. The results of our experimental study will provide an insight into aging of different target-moderator-reflector-shield components as well as new experimental data for benchmarking of neutron transport codes.

Mocko, Michal [Los Alamos National Laboratory; Muhrer, Guenter [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Kelsey, Charles T [Los Alamos National Laboratory; Duran, Michael A [Los Alamos National Laboratory; Tovesson, Fredrik K [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

169

Use of metal organic fluors for spectral discrimination of neutrons and gammas.  

Science Conference Proceedings (OSTI)

A new method for spectral shape discrimination (SSD) of fast neutrons and gamma rays has been investigated. Gammas interfere with neutron detection, making efficient discrimination necessary for practical applications. Pulse shape discrimination (PSD) in liquid organic scintillators is currently the most effective means of gamma rejection. The hazardous liquids, restrictions on volume, and the need for fast timing are drawbacks to traditional PSD scintillators. In this project we investigated harvesting excited triplet states to increase scintillation yield and provide distinct spectral signatures for gammas and neutrons. Our novel approach relies on metal-organic phosphors to convert a portion of the energy normally lost to the scintillation process into useful luminescence with sub-microsecond lifetimes. The approach enables independent control over delayed luminescence wavelength, intensity, and timing for the first time. We demonstrated that organic scintillators, including plastics, nanoporous framework materials, and oil-based liquids can be engineered for both PSD and SSD.

Allendorf, Mark D.; Doty, F. Patrick; Feng, Patrick L.

2010-09-01T23:59:59.000Z

170

Intense Pulsed Light Sintering Technique for Nanomaterials  

Science Conference Proceedings (OSTI)

Advances in Current Activated Tip-Based Sintering (CATS) ∑ Advances in Synthesis and Densification of Heterogeneous Materials ∑ Application of Metal Injection†...

171

Neutron Radiography  

Science Conference Proceedings (OSTI)

Table 8   Characteristics of neutron radiography at various neutron-energy ranges...Good discrimination between materials and ready availability

172

Neutron Sources  

Science Conference Proceedings (OSTI)

Table 1   Characteristics of neutron radiography at various neutron-energy ranges...Good discrimination between materials, and ready

173

Optimization of an accelerator-based epithermal neutron source for neutron capture therapy  

E-Print Network (OSTI)

Nowadays at several nuclear reactors were created BNCTand intensity. Nuclear reactors as neutron source forsource based on a nuclear reactor [4]. The comparison shows

Kononov, O.E.; Kononov, V.N.; Bokhovko, M.V.; Korobeynikov, V.V.; Soloviev, A.N.; Chu, W.T.

2004-01-01T23:59:59.000Z

174

Injection locked oscillator system for pulsed metal vapor lasers  

SciTech Connect

An injection locked oscillator system for pulsed metal vapor lasers is disclosed. The invention includes the combination of a seeding oscillator with an injection locked oscillator (ILO) for improving the quality, particularly the intensity, of an output laser beam pulse. The present invention includes means for matching the first seeder laser pulses from the seeding oscillator to second laser pulses of a metal vapor laser to improve the quality, and particularly the intensity, of the output laser beam pulse.

Warner, Bruce E. (Livermore, CA); Ault, Earl R. (Dublin, CA)

1988-01-01T23:59:59.000Z

175

Glossary Term - Neutron  

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

Neutrino Previous Term (Neutrino) Glossary Main Index Next Term (Neutron Emission) Neutron Emission Neutron A Neutron Neutrons are uncharged particles found within atomic nuclei....

176

About Neutrons  

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

Neutron Basics Neutron Basics A neutron is one of the fundamental particles that make up matter. This uncharged particle exists in the nucleus of a typical atom, along with its positively charged counterpart, the proton. Protons and neutrons each have about the same mass, and both can exist as free particles away from the nucleus. In the universe, neutrons are abundant, making up more than half of all visible matter. Find Out What a Neutron Is Youtube icon Properties of Neutrons How Can Neutrons Be Used for Research? Image of glucose movement in plants Neutron imaging techniques have been able to determine the precise movement of glucose in plants. This knowledge can help scientists better understand how biomass can be efficiently converted into fuel. Neutrons have many properties that make them ideal for certain types of

177

The Digital discrimination of neutron and ? ray using organic scintillation detector based on wavelet transform modulus maximum  

E-Print Network (OSTI)

A novel algorithm for the discrimination of neutron and {\\gamma}-ray with wavelet transform modulus maximum (WTMM) in an organic scintillation has been investigated. Voltage pulses arising from a BC501A organic liquid scintillation detector in a mixed radiation field have been recorded with a fast digital sampling oscilloscope. The performances of most pulse shape discrimination methods in scintillation detection systems using time-domain features of the pulses are affected intensively by noise. However, the WTMM method using frequency-domain features exhibits a strong insensitivity to noise and can be used to discriminate neutron and {\\gamma}-ray events based on their different asymptotic decay trend between the positive modulus maximum curve and the negative modulus maximum curve in the scale-space plane. This technique has been verified by the corresponding mixed-field data assessed by the time-of-flight (TOF) method and the frequency gradient analysis (FGA) method. It is shown that the characterization of neutron and gamma achieved by the discrimination method based on WTMM is consistent with that afforded by TOF and better than FGA. Moreover, because the WTMM method is it self presented to eliminate the noise, there is no need to make any pretreatment for the pulses.

Yang yun; Liu guofu; Yang jun; Luo xiaoliang

2013-04-17T23:59:59.000Z

178

The Manuel Lujan Jr. Neutron Scattering Center (LANSCE) experiment reports 1993 run cycle. Progress report  

Science Conference Proceedings (OSTI)

This year the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) ran an informal user program because the US Department of Energy planned to close LANSCE in FY1994. As a result, an advisory committee recommended that LANSCE scientists and their collaborators complete work in progress. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and a associated Proton Storage Ring (PSR), which can Iter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory (LANL) may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. This year, a total of 127 proposals were submitted. The proposed experiments involved 229 scientists, 57 of whom visited LANSCE to participate in measurements. In addition, 3 (nuclear physics) participating research teams, comprising 44 scientists, carried out experiments at LANSCE. Instrument beam time was again oversubscribed, with 552 total days requested an 473 available for allocation.

Farrer, R.; Longshore, A. [comps.

1995-06-01T23:59:59.000Z

179

The Manuel Lujan, Jr. Neutron Scattering Center (LANSCE) experiment reports 1992 run cycle. Progress report  

Science Conference Proceedings (OSTI)

This year was the fifth in which LANSCE ran a formal user program. A call for proposals was issued before the scheduled run cycles, and experiment proposals were submitted by scientists from universities, industry, and other research facilities around the world. An external program advisory committee, which LANSCE shares with the Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory, examined the proposals and made recommendations. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and an associated Proton Storage Ring (PSR), which can alter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. One hundred sixty-seven proposals were submitted for unclassified research and twelve proposals for research of a programmatic interest to the Laboratory; six experiments in support of the LANSCE research program were accomplished during the discretionary periods. Oversubscription for instrument beam time by a factor of three was evident with 839 total days requested and only 371 available for allocation.

DiStravolo, M.A. [comp.

1993-09-01T23:59:59.000Z

180

PULSE AMPLIFIER  

DOE Patents (OSTI)

The improvement of pulse amplifiers used with scintillation detectors is described. The pulse amplifier circuit has the advantage of reducing the harmful effects of overloading cause by large signal inputs. In general the pulse amplifier circuit comprises two amplifier tubes with the input pulses applied to one amplifier grid and coupled to the second amplifier tube through a common cathode load. The output of the second amplifier is coupled from the plate circuit to a cathode follower tube grid and a diode tube in connected from grid to cathode of the cathode follower tube. Degenerative feedback is provided in the second amplifier by coupling a signal from the cathode follower cathode to the second amplifier grid. The circuit proqides moderate gain stability, and overload protection for subsequent pulse circuits.

Johnstone, C.W.

1958-06-17T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Opportunities for Neutrino Physics at the Spallation Neutron Source: A White Paper  

E-Print Network (OSTI)

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this document, the product of a workshop at the SNS in May 2012, we describe this free, high-quality stopped-pion neutrino source and outline various physics that could be done using it. We describe without prioritization some specific experimental configurations that could address these physics topics.

A. Bolozdynya; F. Cavanna; Y. Efremenko; G. T. Garvey; V. Gudkov; A. Hatzikoutelis; W. R. Hix; W. C. Louis; J. M. Link; D. M. Markoff; G. B. Mills; K. Patton; H. Ray; K. Scholberg; R. G. Van de Water; C. Virtue; D. H. White; S. Yen; J. Yoo

2012-11-22T23:59:59.000Z

182

Pulsed Neurton Elemental On-Line Material Analyzer  

DOE Patents (OSTI)

An on-line material analyzer which utilizes pulsed neutron generation in order to determine the composition of material flowing through the apparatus. The on-line elemental material analyzer is based on a pulsed neutron generator. The elements in the material interact with the fast and thermal neutrons produced from the pulsed generator. Spectra of gamma-rays produced from fast neutrons interacting with elements of the material are analyzed and stored separately from spectra produced from thermal neutron reactions. Measurements of neutron activation takes place separately from the above reactions and at a distance from the neutron generator. A primary passageway allows the material to flow through at a constant rate of speed and operators to provide data corresponding to fast and thermal neutron reactions. A secondary passageway meters the material to allow for neutron activation analysis. The apparatus also has the capability to determine the density of the flowed material. Finally, the apparatus continually utilizes a neutron detector in order to normalize the yield of the gamma ray detectors and thereby automatically calibrates and adjusts the spectra data for fluctuations in neutron generation.

Vourvopoulos, George (Bowling Green, KY)

2002-08-20T23:59:59.000Z

183

Photographic, magnetic, and interferometric measurements of current sheet canting in a pulsed electromagnetic accelerator  

E-Print Network (OSTI)

in a pulsed electromagnetic accelerator were measured using three different techniques: high- speed at higher pressures. 1 Introduction Pulsed electromagnetic accelerators are devices which use intense bursts Apparatus An experimental pulsed electromagnetic accelerator has been constructed. The accelerator

Choueiri, Edgar

184

HydroPulse Drilling  

Science Conference Proceedings (OSTI)

Tempress HydroPulse{trademark} tool increases overbalanced drilling rates by generating intense suction pulses at the drill bit. This report describes the operation of the tool; results of pressure drilling tests, wear tests and downhole drilling tests; and the business case for field applications. The HydroPulse{trademark} tool is designed to operate on weighted drilling mud at conventional flow rates and pressures. Pressure drilling tests confirm that the HydroPulse{trademark} tool provides 33% to 200% increased rate of penetration. Field tests demonstrated conventional rotary and mud motor drilling operations. The tool has been operated continuous for 50 hours on weighted mud in a wear test stand. This level of reliability is the threshold for commercial application. A seismic-while-drilling version of the tool was also developed and tested. This tool was used to demonstrate reverse vertical seismic profiling while drilling an inclined test well with a PDC bit. The primary applications for the HydroPulse{trademark} tool are deep onshore and offshore drilling where rate of penetration drives costs. The application of the seismic tool is vertical seismic profiling-while-drilling and look-ahead seismic imaging while drilling.

J.J. Kolle

2004-04-01T23:59:59.000Z

185

Neutron dosimetry  

DOE Patents (OSTI)

A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

Quinby, Thomas C. (Kingston, TN)

1976-07-27T23:59:59.000Z

186

Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source  

SciTech Connect

A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using {sup 3}He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MC NP K-Code calculations.

Hollas, C.L.; Goulding, C.A.; Myers, W.L.

1999-09-20T23:59:59.000Z

187

HIGH INTENSITY PERFORMANCE AND UPGRADES AT THE BROOKHAVEN AGS  

SciTech Connect

Fig. 1 shows the present layout of the AGS-RHIC accelerator complex. The high intensity proton beam of the AGS is used both for the slow-extracted-beam (SEB) area with many target station to produce secondary beams and the fast-extracted-beam (FEB) line used for the production of muons for the g-2 experiment and for high intensity target testing for the spallation neutron sources and muon production targets for the muon collider. The same FEB line will also be used for the transfer of beam to RHIC. The proton beam intensity in the AGS has increased steadily over the 35 year existence of the AGS, but the most dramatic increase occurred over the last couple of years with the addition of the new AGS Booster[1]. In Fig. 2 the history of the AGS intensity improvements is shown and the major upgrades are indicated. The AGS Booster has one quarter the circumference of the AGS and therefore allows four Booster beam pulses to be stacked in the AGS at an injection energy of 1.5--1.9 GeV. At this increased energy, space charge forces are much reduced and this in turn allows for the dramatic increase in the AGS beam intensity. The 200 MeV LINAC is being used both for the injection into the Booster as well as an isotope production facility. A recent upgrade of the LINAC rf system made it possible to operated at an average H{sup {minus}} current of 150 {micro}A and a maximum of 12 x 10{sup 13} H{sup {minus}} per 500 {micro}s LINAC pulse for the isotope production target. Typical beam currents during the 500 {micro}s pulse are about 80 mA at the source, 60 mA after the 750 keV RFQ, 38 mA after the first LINAC tank (10 MeV), and 37 mA at end of the LINAC at 200 MeV. The normalized beam emittance is about 2 {pi} mm mrad for 95% of the beam and the beam energy spread is about {+-}1.2 MeV. A magnetic fast chopper installed at 750 keV allows the shaping of the beam injected into the Booster to avoid excessive beam loss.

ROSER,T.

1998-05-04T23:59:59.000Z

188

Coherence as ultrashort pulse train generator  

E-Print Network (OSTI)

Intense, well-controlled regular light pulse trains start to play a crucial role in many fields of physics. We theoretically demonstrate a very simple and robust technique for generating such periodic ultrashort pulses from a continuous probe wave which propagates in a dispersive thermal gas media.

Gevorg Muradyan; Mariam Hovhannisyan

2010-07-08T23:59:59.000Z

189

Neutron Sources  

Science Conference Proceedings (OSTI)

... for Neutron Reaction Rate Measurements, JA Grundl, V. Spiegel, CM Eisenhauer, HT Heaton II, DM Gilliam (NBS), and J. Bigelow (ORNL), Nucl. ...

2013-07-27T23:59:59.000Z

190

MAGNETIC NEUTRON SCATTERING  

SciTech Connect

Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science, ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.

ZALIZNYAK,I.A.; LEE,S.H.

2004-07-30T23:59:59.000Z

191

Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method  

SciTech Connect

A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 {micro}m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

2011-04-01T23:59:59.000Z

192

First time nuclear material detection by one short-pulse-laser-driven  

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

Articles ¬Ľ Articles ¬Ľ First time nuclear material detection by one short-pulse-laser-driven neutron source First time nuclear material detection by one short-pulse-laser-driven neutron source The results obtained are the first experimental demonstration of active interrogation of nuclear material by a short pulse laser driven neutron source. April 3, 2013 TRIDENT pulse The results obtained are the first experimental demonstration of active interrogation of nuclear material by a short pulse laser driven neutron source. Contact James Rickman Communications Specialist (505) 665-9203 Email A single shot interrogation of the depleted uranium sample, showed a clear signal from the delayed neutrons in the detector with uranium, compared with the background, and with the typical time behavior of delayed

193

VULCAN: the Engineering Materials Diffractometer at SNS | ORNL Neutron  

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

Engineering Materials Diffractometer at SNS Engineering Materials Diffractometer at SNS VULCAN with the multiaxial loadframe on the sample stage. VULCAN with the multiaxial loadframe on the sample stage. VULCAN is designed for deformation, phase transformation, residual stress, texture, and microstructure studies. Load frames, furnaces, battery chargers, and other auxiliary equipment for in situ and time-resolved measurements are integrated in the instrument. As a time-of-flight diffractometer at the world's most intense pulsed, accelerator-based neutron source, VULCAN provides rapid volumetric mapping with a sampling volume of 1 mm3 and a measurement time of minutes for common engineering materials. In extreme cases, VULCAN has the ability to study kinetic behaviors in sub-second time frames. Applications

194

Neutronic reactor  

DOE Patents (OSTI)

A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

Wende, Charles W. J. (West Chester, PA)

1976-08-17T23:59:59.000Z

195

Neutron source  

DOE Patents (OSTI)

A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.

Cason, J.L. Jr.; Shaw, C.B.

1975-10-21T23:59:59.000Z

196

Production of Picosecond, Kilojoule, and Petawatt Laser Pulses via Raman Amplification of Nanosecond Pulses  

Science Conference Proceedings (OSTI)

Raman amplification in plasma has been promoted as a means of compressing picosecond optical laser pulses to femtosecond duration to explore the intensity frontier. Here we show for the first time that it can be used, with equal success, to compress laser pulses from nanosecond to picosecond duration. Simulations show up to 60% energy transfer from pump pulse to probe pulse, implying that multikilojoule ultraviolet petawatt laser pulses can be produced using this scheme. This has important consequences for the demonstration of fast-ignition inertial confinement fusion.

Trines, R. M. G. M.; Bingham, R.; Norreys, P. A. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxon, OX11 0QX (United Kingdom); Fiuza, F.; Fonseca, R. A.; Silva, L. O. [GoLP/Instituto de Plasmas e Fusao Nuclear--Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Cairns, R. A. [University of St. Andrews, St. Andrews, Fife KY16 9AJ (United Kingdom)

2011-09-02T23:59:59.000Z

197

POWDER: The Neutron Powder Diffractometer at HFIR | ORNL Neutron Sciences  

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

Neutron Powder Diffractometer Neutron Powder Diffractometer Neutron Powder Diffractometer. Neutron Powder Diffractometer. The HB-2A diffractometer is a workhorse instrument used to conduct crystal structural and magnetic structural studies of powdered and ceramic samples, particularly as a function of intensive conditions (T, P, H, etc.). Powder diffraction data collected on this instrument are ideally suited for the Rietveld method. A full range of ancillary sample environments can be used, including cryofurnaces (4-800 K), furnaces (to 1800 K), cryostats (to 0.3 K), and cryomagnets (to 7 T). The Powder Diffractometer has a Debye-Scherrer geometry. The detector bank has 44 3He tubes, each with 6' Soller collimators. A germanium wafer-stack monochromator is vertically focusing and provides one of three principal

198

Physics and Dynamics of Current Sheets in Pulsed Plasma Thrusters  

E-Print Network (OSTI)

canting in pulsed electromagnetic accelerators is the departure of the plasma sheet that carries Pulsed electromagnetic accelerators are devices which use intense bursts of elec- trical current (O(104 to improve the performance of pulsed electromagnetic accelerators in the context of plasma propulsion

Choueiri, Edgar

199

Design of a repetitively pulsed megajoule dense-plasma focus  

SciTech Connect

This report describes a 1 pulse per second, dense-plasma-focus (DPF) materials-testing device capable of delivering a minimum of 10$sup 15$ neutrons per pulse. Moderate scaling up from existing designs is shown to be sufficient to provide 2 x 10$sup 13$ neutrons/ cm$sup 2$. s to a suitable target. The average power consumption, which has become a major issue due to the energy crisis, is analyzed with respect to other plasma devices and is shown to be highly favorable. Also discussed is a novel approach to capacitor-bank and switch design with respect to repetitive-pulse operation. (auth)

Zucker, O.; Bostick, W.; Gullickson, R.; Long, J.; Luce, J.; Sahlin, H.

1975-08-01T23:59:59.000Z

200

Neutron flux profile monitor for use in a fission reactor  

DOE Patents (OSTI)

A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occured. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Kopp, Manfred K. (Oak Ridge, TN); Valentine, Kenneth H. (Lenoir City, TN)

1983-01-01T23:59:59.000Z

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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

Research on fusion neutron sources  

SciTech Connect

The use of fusion devices as powerful neutron sources has been discussed for decades. Whereas the successful route to a commercial fusion power reactor demands steady state stable operation combined with the high efficiency required to make electricity production economic, the alternative approach to advancing the use of fusion is free of many of complications connected with the requirements for economic power generation and uses the already achieved knowledge of Fusion physics and developed Fusion technologies. 'Fusion for Neutrons' (F4N), has now been re-visited, inspired by recent progress achieved on comparably compact fusion devices, based on the Spherical Tokamak (ST) concept. Freed from the requirement to produce much more electricity than used to drive it, a fusion neutron source could be efficiently used for many commercial applications, and also to support the goal of producing energy by nuclear power. The possibility to use a small or medium size ST as a powerful or intense steady-state fusion neutron source (FNS) is discussed in this paper in comparison with the use of traditional high aspect ratio tokamaks. An overview of various conceptual designs of compact fusion neutron sources based on the ST concept is given and they are compared with a recently proposed Super Compact Fusion Neutron Source (SCFNS), with major radius as low as 0.5 metres but still able to produce several MW of neutrons in a steady-state regime.

Gryaznevich, M. P. [Tokamak Solutions UK, Culham Science Centre, Abingdon, OXON, OX133DB (United Kingdom)

2012-06-19T23:59:59.000Z

202

Thermal neutron detection system  

DOE Patents (OSTI)

According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

2000-01-01T23:59:59.000Z

203

Pulsed hydrojet  

DOE Patents (OSTI)

An underwater pulsed hydrojet propulsion system is provided for accelerating and propelling a projectile or other vessel. A reactant, such as lithium, is fluidized and injected into a water volume. The resulting reaction produces an energy density in a time effective to form a steam pocket. Thrust flaps or baffles direct the pressure from the steam pocket toward an exit nozzle for accelerating a water volume to create thrust. A control system regulates the dispersion of reactant to control thrust characteristics.

Bohachevsky, I.O.; Torrey, M.D.

1986-06-10T23:59:59.000Z

204

A Very Intense Neutrino Super Beam Experiment for Leptonic CP Violation Discovery based on the European Spallation Source Linac: A Snowmass 2013 White Paper  

E-Print Network (OSTI)

Very intense neutrino beams and large neutrino detectors will be needed in order to enable the discovery of CP violation in the leptonic sector. We propose to use the proton linac of the European Spallation Source currently under construction in Lund, Sweden to deliver, in parallel with the spallation neutron production, a very intense, cost effective and high performance neutrino beam. The baseline program for the European Spallation Source linac is that it will be fully operational at 5 MW average power by 2022, producing 2 GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron production and 14 pulses/s for neutrino production. Furthermore, because of the high current required in the pulsed neutrino horn, the length of the pulses used for neutrino production needs to be compressed to a few $\\mu$s with the aid of an accumulator ring. A long baseline experiment using this Super Beam and a megaton underground Water Cherenkov detector located in existing mines 300-600 km from Lund will make it possible to discover leptonic CP violation at 5 $\\sigma$ significance level in up to 50% of the leptonic Dirac CP-violating phase range. This experiment could also determine the neutrino mass hierarchy at a significance level of more than 3 $\\sigma$ if this issue will not already have been settled by other experiments by then. The mass hierarchy performance could be increased by combining the neutrino beam results with those obtained from atmospheric neutrinos detected by the same large volume detector. This detector will also be used to measure the proton lifetime, detect cosmological neutrinos and neutrinos from supernova explosions. Results on the sensitivity to leptonic CP violation and the neutrino mass hierarchy are presented.

E. Baussan; M. Blennow; M. Bogomilov; E. Bouquerel; J. Cederkall; P. Christiansen; P. Coloma; P. Cupial; H. Danared; C. Densham; M. Dracos; T. Ekelof; M. Eshraqi; E. Fernandez Martinez; G. Gaudiot; R. Hall-Wilton; J. -P. Koutchouk; M. Lindroos; R. Matev; D. McGinnis; M. Mezzetto; R. Miyamoto; L. Mosca; T. Ohlsson; H. Ohman; F. Osswald; S. Peggs; P. Poussot; R. Ruber; J. Y. Tang; R. Tsenov; G. Vankova-Kirilova; N. Vassilopoulos; E. Wildner; J. Wurtz

2013-09-26T23:59:59.000Z

205

NEUTRONIC REACTORS  

DOE Patents (OSTI)

A nuclear reactor is described wherein horizontal rods of thermal- neutron-fissionable material are disposed in a body of heavy water and extend through and are supported by spaced parallel walls of graphite.

Wigner, E.P.

1960-11-22T23:59:59.000Z

206

Neutron range spectrometer  

DOE Patents (OSTI)

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

Manglos, S.H.

1988-03-10T23:59:59.000Z

207

ORNL Neutron Sciences  

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

ORNL's Neutron Science Future: Integrating Neutron Scattering Across the Laboratory Greg Smith, HFIR Center for Neutron Scattering Upgrade Status and Scientific Opportunities...

208

Use of a high repetition rate neutron generator for in vivo body composition measurements via neutron inelastic scattering  

DOE Green Energy (OSTI)

A small D-T neutron generator with a high pulse rate is used for the in vivo measurement of body carbon, oxygen and hydrogen. The core of the neutron generator is a 13 cm-long Zetatron tube pulsed at a rate of 10 kHz delivering 10/sup 3/ to 10/sup 4/ neutrons per pulse. A target-current feedback system regulates the source of the accelerator to assure constant neutron output. Carbon is measured by detecting the 4.44 MeV ..gamma..-rays from inelastic scattering. The short half-life of the 4.44 MeV state of carbon requires detection of the ..gamma..-rays during the 10 ..mu..s neutron pulse. Generators with low pulsing rate were found inappropriate for carbon measurements because of their low duty-cycle (high neutron output during the pulse). In vivo measurements were performed with normal volunteers using a scanning bed facility for a dose less than 25 mrem. This technique offers medical as well as general bulk analysis applications. 8 refs., 5 figs.

Kehayias, J.J.; Ellis, K.J.; Cohn, S.H.; Weinlein, J.H.

1986-01-01T23:59:59.000Z

209

NEUTRONIC REACTOR  

DOE Patents (OSTI)

A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

Fraas, A.P.; Mills, C.B.

1961-11-21T23:59:59.000Z

210

NEUTRON SOURCES  

DOE Patents (OSTI)

A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)

Richmond, J.L.; Wells, C.E.

1963-01-15T23:59:59.000Z

211

NEUTRONIC REACTOR  

DOE Patents (OSTI)

A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

Wigner, E.P.

1958-04-22T23:59:59.000Z

212

Time resolved neutron spectrum measurements at the Mirror Fusion Test Facility  

SciTech Connect

An advanced neutron diagnostic system has been developed for spectrum measurements on MFTF. Its collimated field of view allows spatially resolved neutron spectrum measurements. The 10 Mhz pulse height analysis and particle identification capability allow spectrum measurements in intervals as short as 10 ms. These capabilities will be used for space and time resolved determinations of ion energy from measurements of neutron Doppler width.

Slaughter, D.

1985-10-01T23:59:59.000Z

213

Lithium batteries for pulse power  

DOE Green Energy (OSTI)

New designs of lithium batteries having bipolar construction and thin cell components possess the very low impedance that is necessary to deliver high-intensity current pulses. The R D and understanding of the fundamental properties of these pulse batteries have reached an advanced level. Ranges of 50--300 kW/kg specific power and 80--130 Wh/kg specific energy have been demonstrated with experimental high-temperature lithium alloy/transition-metal disulfide rechargeable bipolar batteries in repeated 1- to 100-ms long pulses. Other versions are designed for repetitive power bursts that may last up to 20 or 30 s and yet may attain high specific power (1--10 kW/kg). Primary high-temperature Li-alloy/FeS{sub 2} pulse batteries (thermal batteries) are already commercially available. Other high-temperature lithium systems may use chlorine or metal-oxide positive electrodes. Also under development are low-temperature pulse batteries: a 50-kW Li/SOCl{sub 2} primary batter and an all solid-state, polymer-electrolyte secondary battery. Such pulse batteries could find use in commercial and military applications in the near future. 21 refs., 8 figs.

Redey, L.

1990-01-01T23:59:59.000Z

214

Isolated sub-100-attosecond pulse generation via controlling electron dynamics  

E-Print Network (OSTI)

A new method to coherently control the electron dynamics is proposed using a few-cycle laser pulse in combination with a controlling field. It is shown that this method not only broadens the attosecond pulse bandwidth, but also reduces the chirp, then an isolated 80-as pulse is straightforwardly obtained and even shorter pulse is achievable by increasing the intensity of the controlling field. Such ultrashort pulses allow one to investigate ultrafast electronic processes which have never be achieved before. In addition, the few-cycle synthesized pulse is expected to manipulate a wide range of laser-atom interactions.

Lan, Pengfei; Cao, Wei; Li, Yuhua; Wang, Xinlin

2007-01-01T23:59:59.000Z

215

A feasibility study for a one-megawatt pulsed spallation source at Los Alamos National Laboratory  

SciTech Connect

Over the past two decades, high-intensity proton accelerators have been designed and developed to support nuclear physics research and defense applications. This technology has now matured to the point where it can support simultaneous and cost-effective exploitation of a number of important areas of both basic and applied science. Examples include neutron scattering, the production of radioisotopes, tests of technologies to transmute nuclear waste, radiation damage studies, nuclear physics, and muon spin research. As part of a larger program involving these and other areas, a team at Los Alamos National Laboratory has undertaken a feasibility study for a 1-MW pulsed spallation neutron source (PSS) based on the use of an 800-MeV proton linac and an accumulator ring. In January 1994, the feasibility study was reviewed by a large, international group of experts in the design of accelerators and neutron spallation targets. This group confirmed the viability of the proposed neutron source. In this paper, I describe the approach Los Alamos has taken to the feasibility study, which has involved a synergistic application of the Laboratory`s expertise in nuclear science and technology, computation, and particle-beam technologies. Several examples of problems resolved by the study are described, including chopping of low-energy proton beam, interactions between H{sup {minus}} particles and the stripper foil used to produce protons for injection into an accumulator ring, and the inclusion of engineering realities into the design of a neutron production target. These examples are chosen to illustrate the breadth of the expertise that has been brought to bear on the feasibility study and to demonstrate that there are real R&D issues that need to be resolved before a next-generation spoliation source can be built.

Pynn, R.

1994-07-01T23:59:59.000Z

216

Determination of the gamma-ray asymmetry in the capture of polarized neutrons on hydrogen and deuterium.  

DOE Green Energy (OSTI)

The n+p{yields}d+{gamma} experiment measures the parity-violating directional gamma-ray asymmetry, A{gamma}, with uncertainties of 0.5x10{sup -8} when cold polarized neutrons are captured by para-hydrogen. This precision measurement will determine the long-range pion-nucleon weak coupling constant, H{sub {pi}}{sup 1}, with a precision of 10% of its predicted value, and thus will help to clarify our understanding of the weak interaction between nucleons. The n+p{yields}d+{gamma} experiment on the SNS beamline 14B is designed to take advantage of the high intensity of the source and its pulsed nature. The experiment requires a 30-Hz pulsed beam for optimal performance. In three months of run time the experiment will achieve a statistical uncertainty of 0.5x10{sup -8}.

Bowman, J. D. (J. David); Greene, G. L. (Geoff L.); Knudson, J. N. (James N.); Lamoreaux, Steve Keith; Mitchell, G. S. (Gregory S.); Morgan, G. L. (George Lake); Wilburn, W. S. (Wesley S.); Yuan, V. W. (Vincent W.); Penttila, S. I. (Seppo I.)

2001-01-01T23:59:59.000Z

217

Californium Neutron Irradiation Facility  

Science Conference Proceedings (OSTI)

Californium Neutron Irradiation Facility. Summary: ... Cf irradiation facility (Photograph by: Neutron Physics Group). Lead Organizational Unit: pml. Staff: ...

2013-07-23T23:59:59.000Z

218

Neutron Physics Group  

Science Conference Proceedings (OSTI)

... spectrum and fluencies is essential for several ... Neutron Interferometer and Optics Facility performed a ... other neutron scattering facilities depends on ...

2011-10-24T23:59:59.000Z

219

Neutron Generators for Spent Fuel Assay  

SciTech Connect

The Next Generation Safeguards Initiative (NGSI) of the U.S. DOE has initiated a multi-lab/university collaboration to quantify the plutonium (Pu) mass in, and detect the diversion of pins from, spent nuclear fuel (SNF) assemblies with non-destructive assay (NDA). The 14 NDA techniques being studied include several that require an external neutron source: Delayed Neutrons (DN), Differential Die-Away (DDA), Delayed Gammas (DG), and Lead Slowing-Down Spectroscopy (LSDS). This report provides a survey of currently available neutron sources and their underlying technology that may be suitable for NDA of SNF assemblies. The neutron sources considered here fall into two broad categories. The term 'neutron generator' is commonly used for sealed devices that operate at relatively low acceleration voltages of less than 150 kV. Systems that employ an acceleration structure to produce ion beam energies from hundreds of keV to several MeV, and that are pumped down to vacuum during operation, rather than being sealed units, are usually referred to as 'accelerator-driven neutron sources.' Currently available neutron sources and future options are evaluated within the parameter space of the neutron generator/source requirements as currently understood and summarized in section 2. Applicable neutron source technologies are described in section 3. Commercially available neutron generators and other source options that could be made available in the near future with some further development and customization are discussed in sections 4 and 5, respectively. The pros and cons of the various options and possible ways forward are discussed in section 6. Selection of the best approach must take a number of parameters into account including cost, size, lifetime, and power consumption, as well as neutron flux, neutron energy spectrum, and pulse structure that satisfy the requirements of the NDA instrument to be built.

Ludewigt, Bernhard A

2010-12-30T23:59:59.000Z

220

Neutron Repulsion  

E-Print Network (OSTI)

Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding how: a.) The Sun generates and releases neutrinos, energy and solar-wind hydrogen and helium; b.) An inhabitable planet formed and life evolved around an ordinary-looking star; c.) Continuous climate change - induced by cyclic changes in gravitational interactions of the Sun's energetic core with planets - has favored survival by adaptation.

Oliver K. Manuel

2011-02-08T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Awareness, Preference, Utilization, and Messaging Research for the Spallation Neutron Source and High Flux Isotope Reactor  

Science Conference Proceedings (OSTI)

Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world, and the SNS is one of the world's most intense pulsed neutron beams. Management of these two resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD commissioned this survey research to develop baseline information regarding awareness of and perceptions about neutron science. Specific areas of investigative interest include the following: (1) awareness levels among those in the scientific community about the two neutron sources that ORNL offers; (2) the level of understanding members of various scientific communities have regarding benefits that neutron scattering techniques offer; and (3) any perceptions that negatively impact utilization of the facilities. NScD leadership identified users of two light sources in North America - the Advanced Photon Source (APS) at Argonne National Laboratory and the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory - as key publics. Given the type of research in which these scientists engage, they would quite likely benefit from including the neutron techniques available at SNS and HFIR among their scientific investigation tools. The objective of the survey of users of APS, NSLS, SNS, and HFIR was to explore awareness of and perceptions regarding SNS and HFIR among those in selected scientific communities. Perceptions of SNS and FHIR will provide a foundation for strategic communication plan development and for developing key educational messages. The survey was conducted in two phases. The first phase included qualitative methods of (1) key stakeholder meetings; (2) online interviews with user administrators of APS and NSLS; and (3) one-on-one interviews and traditional and online focus groups with scientists. The latter include SNS, HFIR, and APS users as well as scientists at ORNL, some of whom had not yet used HFIR and/or SNS. These approaches informed development of the second phase, a quantitative online survey. The survey consisted of 16 questions and 7 demographic categorizations, 9 open-ended queries, and 153 pre-coded variables and took an average time of 18 minutes to complete. The survey was sent to 589 SNS/HFIR users, 1,819 NSLS users, and 2,587 APS users. A total of 899 individuals provided responses for this study: 240 from NSLS; 136 from SNS/HFIR; and 523 from APS. The overall response rate was 18%.

Bryant, Rebecca [Bryant Research, LLC; Kszos, Lynn A [ORNL

2011-03-01T23:59:59.000Z

222

Cold Neutron and Ultracold Neutron Sources  

Science Conference Proceedings (OSTI)

... Moderators ē Solid Methane Ė CH 4 Ė CD 4 ... In a cold neutron flux with a continuous spectrum, more neutrons could ... Magneto-vibrational Scatt. + ...

2009-07-13T23:59:59.000Z

223

Chapter 13 - NEUTRON AREA DETECTORS 1. NEUTRON ...  

Science Conference Proceedings (OSTI)

... The neutron peak corresponds to both reaction products being entirely absorbed in the ... 6. A fission chamber is a very low efficiency neutron detector ...

2009-11-29T23:59:59.000Z

224

Neutronic design of a fission converter-based epithermal neutron beam for neutron capture therapy  

SciTech Connect

To meet the needs for neutron capture theory (NCT) irradiations, a high-intensity, high-quality fusion converter-based epithermal neutron beam has been designed for the MITR-II research reactor. This epithermal neutron beam, capable of delivering treatments in a few minutes with negligible background contamination from fast neutrons and photons, will be installed in the present thermal column and hohlraum of the 5-MW MITR-II research reactor. Spent or fresh MITR-II fuel elements will be used to fuel the converter. With a fission converter power of {approximately}80 kW using spent fuel, epithermal fluxes (1 eV < E < 10 keV) in excess of 10{sup 10} n/cm{sup 2} {center_dot} s are achievable at the target position with negligible photon and fast neutron contamination, i.e., <2 {times} 10{sup {minus}11}cGy-cm{sup 2}/n. With the currently available {sup 10}B delivery compound boronophenylalanine-fructose, average therapeutic ratios of {approximately}5 can be achieved using this beam for brain irradiations with deep effective penetration ({approximately}9.5 cm) and high dose rates of up to 400 to 600 RBE cGy/min. If NCT becomes an accepted therapy, fission converter-based beams constructed at existing reactors could meet a large fraction of the projected requirements for intense, low-background epithermal neutron beams at a relatively low cost. The results of an extensive set of neutronic design studies investigating all components of the beam are presented. These detailed studies can be useful as guidance for others who may wish to use the fission converter approach to develop epithermal beams for NCT.

Kiger, W.S. III; Sakamoto, S.; Harling, O.K. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1999-01-01T23:59:59.000Z

225

NEUTRONIC REACTOR  

DOE Patents (OSTI)

A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

Wigner, E.P.; Weinberg, A.W.; Young, G.J.

1958-04-15T23:59:59.000Z

226

Fast Neutron Detector for Fusion Reactor KSTAR Using Stilbene Scintillator  

E-Print Network (OSTI)

Various neutron diagnostic tools are used in fusion reactors to evaluate different aspects of plasma performance, such as fusion power, power density, ion temperature, fast ion energy, and their spatial distributions. The stilbene scintillator has been proposed for use as a neutron diagnostic system to measure the characteristics of neutrons from the Korea Superconducting Tokamak Advanced Research (KSTAR) fusion reactor. Specially designed electronics are necessary to measure fast neutron spectra with high radiation from a gamma-ray background. The signals from neutrons and gamma-rays are discriminated by the digital charge pulse shape discrimination (PSD) method, which uses total to partial charge ratio analysis. The signals are digitized by a flash analog-to-digital convertor (FADC). To evaluate the performance of the fabricated stilbene neutron diagnostic system, the efficiency of 10 mm soft-iron magnetic shielding and the detection efficiency of fast neutrons were tested experimentally using a 252Cf neutr...

Lee, Seung Kyu; Kim, Gi-Dong; Kim, Yong-Kyun

2011-01-01T23:59:59.000Z

227

Fast pulsed excitation wiggler or undulator  

DOE Patents (OSTI)

A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

Van Steenbergen, A.

1989-06-20T23:59:59.000Z

228

Fast pulsed excitation wiggler or undulator  

DOE Patents (OSTI)

A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

van Steenbergen, Arie (Shoreham, NY)

1990-01-01T23:59:59.000Z

229

Laser guiding at relativistic intensities and wakefield particle accleration in plasma channels  

E-Print Network (OSTI)

Laser Guiding at Relativistic Intensities and Wakefieldfirst time in a high gradient laser wakefield accelerator byguiding the drive laser pulse. Channels formed by

2004-01-01T23:59:59.000Z

230

Neutron Compound Refractive Prisms - DOE SBIR Phase II Final Report  

SciTech Connect

The results of the research led to a pulsed electromagnetic periodic magnetic field array (PMF), which coupled with a pair of collimation slits, and a mechanical chopper slit, were able to deflect spin-up neutrons to a band of line-fused neutrons a focal plane heights that correspond to the time-varying magnetic field amplitude. The electromagnetic field PMF produced 5.4 pulses per minute in which each pulse was 50 msec in duration with a full width half maximum (FWHM) of 7.5 msec. The calculated 7.7 mm vertical height of the band of focused spin-up neutrons corresponded closely to the measured 7.5 mm height of the center line of the imaged band of neutrons. The band of deflected spin-up neutrons was 5 mm in vertical width and the bottom of the band was 5 mm above the surface of the PMF pole. The limited exposure time of 3 hours and the smaller 0.78 T magnetic field allowed focused and near focused neutrons of 1.8 √?¬?√?¬? to 2.6 √?¬?√?¬? neutrons, which were in the tails of the McClellan Nuclear Radiation Center Bay 4 Maxwell Boltzmann distribution of neutrons with peak flux at 1.1-1.2 √?¬?√?¬?. The electromagnetic PMF was expected to produces a 2.0 T peak magnetic field amplitude, which would be operational at a higher duty factor, rather than the as built 7.5 msec FWHM with pulse repetition frequency of 5.4 pulses per minute. The fabricated pulsed electromagnetic PMF with chopper is expected to perform well on a cold, very cold or ultra cold beam line as a spectrometer or monochromator source of spin-up polarized neutron. In fact there may be a possible use of the PMF to do ultra-cold neutron trapping, see paper by A. I. Frank1, V. G. Nosov, Quantum Effects in a One-Dimensional Magnetic Gravitational Trap for Ultracold Neutrons, JETP Letters, Vol. 79, No. 7, 2004, pp. 313√?¬Ę√?¬?√?¬?315. The next step is to find a cold or very cold neutron facility, where further testing or use of the pulsed magnetic field PMF can be pursued.

Dr. Jay Theodore Cremer, Jr

2011-06-25T23:59:59.000Z

231

NEUTRONIC REACTORS  

DOE Patents (OSTI)

The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

Anderson, H.L.

1958-10-01T23:59:59.000Z

232

Neutron Imaging Explored as Complementary Technique for Improving Cancer  

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

Neutron Imaging Explored as Complementary Technique for Improving Cancer Neutron Imaging Explored as Complementary Technique for Improving Cancer Detection August 05, 2013 Researcher Maria Cekanova analyzes the neutron radiographs of a canine breast tumor (black color in top image of monitor screen) using the software to visualize in color the various intensities of neutron transmissions through the breast tissue. ORNL and University of Tennessee collaboration now analyzing first results from neutron radiographs of cancerous tissue samples Today's range of techniques for detection of breast and other cancers include mammography, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET), and optical imaging. Each technology has advantages and disadvantages, with limitations either

233

Methods for absorbing neutrons  

DOE Patents (OSTI)

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

Guillen, Donna P. (Idaho Falls, ID); Longhurst, Glen R. (Idaho Falls, ID); Porter, Douglas L. (Idaho Falls, ID); Parry, James R. (Idaho Falls, ID)

2012-07-24T23:59:59.000Z

234

Neutronic Characterization of the Megapie Target  

E-Print Network (OSTI)

The MEGAPIE project is one of the key experiments towards the feasibility of Accelerator Driven Systems. On-line operation and post-irradiation analysis will provide the scientific community with unique data on the behavior of a liquid spallation target under realistic irradiation conditions. A good neutronics performance of such a target is of primary importance towards an intense neutron source, where an extended liquid metal loop requires some dedicated verifications related to the delayed neutron activity of the irradiated PbBi. In this paper we report on the experimental characterization of the MEGAPIE neutronics in terms of the prompt neutron (PN) flux inside the target and the delayed neutron (DN) flux on the top of it. For the PN measurements, a complex detector, made of 8 microscopic fission chambers, has been built and installed in the central part of the target to measure the absolute neutron flux and its spatial distribution. Moreover, integral information on the neutron energy distribution as a function of the position along the beam axis could be extracted, providing integral constraints on the neutron production models implemented in transport codes such as MCNPX. For the DN measurement, we used a standard 3He counter and we acquired data during the start-up phase of the target irradiation in order to take sufficient statistics at variable beam power. Experimental results obtained on the PN flux characteristics and their comparison with MCNPX simulations are presented, together with a preliminary analysis of the DN decay time spectrum.

Stefano Panebianco; Olivier Bringer; Pavel Bokov; Sebastien Chabod; Frederic Chartier; Emmeric Dupont; Diane Dore; Xavier Ledoux; Alain Letourneau; Ludovic Oriol; Aurelien Prevost; Danas Ridikas; Jean-Christian Toussaint

2007-10-31T23:59:59.000Z

235

Neutronic Design Calculations on Moderators for the Spallation Neutron Source (SNS)  

DOE Green Energy (OSTI)

The Spallation Neutron Source (SNS) to be built at the Oak Ridge National Laboratory will provide an intense source of neutrons for a large variety of experiments. It consists of a high-energy (1-GeV) and high-power ({approximately}1-MW) proton accelerator, an accumulator ring, together with a target station and an experimental area. In the target itself, the proton beam will produce neutrons via the spallation process and these will be converted to low-energy (<2-eV) neutrons in moderators located close to the target. Current plans are to have two liquid-hydrogen (20-K) moderators and two room-temperature H{sub 2}O moderators. Extensive engineering design work has been conducted on the moderator vessels. For our studies we have produced realistic neutronic representations of these moderators. We report on neutronic studies conducted on these representations of the moderators using Monte Carlo simulation techniques.

Murphy, D.B.

1999-11-14T23:59:59.000Z

236

Photon and neutron active interrogation of highly enriched uranium.  

SciTech Connect

The physics of photon and neutron active interrogation of highly enriched uranium (HEU) using the delayed neutron reinterrogation method is described in this paper. Two sets of active interrogation experiments were performed using a set of subcritical configurations of cocentric HEU metal hemishells. One set of measurements utilized a pulsed 14-MeV neutron generator as the active source. The second set of measurements utilized a linear accelerator-based bremsstrahlung photon source as an active interrogation source. The neutron responses were measured for both sets of experiments. The operational details and results for both measurement sets are described.

Myers, W. L. (William L.); Goulding, C. A. (Charles A.); Hollas, C. L. (Charles L.); Moss, C. E. (Calvin E.)

2004-01-01T23:59:59.000Z

237

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

238

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

Wood, J.L.

1992-12-01T23:59:59.000Z

239

The neutron long counter NERO for studies of beta-delayed neutron emission in the r-process  

E-Print Network (OSTI)

The neutron long counter NERO was built at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, for measuring beta-delayed neutron-emission probabilities. The detector was designed to work in conjunction with a beta-decay implantation station, so that beta decays and beta-delayed neutrons emitted from implanted nuclei can be measured simultaneously. The high efficiency of about 40%, for the range of energies of interest, along with the small background, are crucial for measuring beta-delayed neutron emission branchings for neutron-rich r-process nuclei produced as low intensity fragmentation beams in in-flight separator facilities.

J. Pereira; P. Hosmer; G. Lorusso; P. Santi; A. Couture; J. Daly; M. Del Santo; T. Elliot; J. Goerres; C. Herlitzius; K. -L. Kratz; L. O. Lamm; H. Y. Lee; F. Montes; M. Ouellette; E. Pellegrini; P. Reeder; H. Schatz; F. Schertz; L. Schnorrenberger; K. Smith; E. Stech; E. Strandberg; C. Ugalde; M. Wiescher; A. Woehr

2010-07-28T23:59:59.000Z

240

Isolated trigger pulse generator  

DOE Patents (OSTI)

A trigger pulse generation system capable of delivering a multiplicity of isolated 100 kV trigger pulses with picosecond simultaneity. 2 figs.

Aaland, K.

1980-02-19T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Harmonic generation at high intensities  

Science Conference Proceedings (OSTI)

Atomic electrons subject to intense laser fields can absorb many photons, leading either to multiphoton ionization or the emission of a single, energetic photon which can be a high multiple of the laser frequency. The latter process, high-order harmonic generation, has been observed experimentally using a range of laser wavelengths and intensities over the past several years. Harmonic generation spectra have a generic form: a steep decline for the low order harmonics, followed by a plateau extending to high harmonic order, and finally an abrupt cutoff beyond which no harmonics are discernible. During the plateau the harmonic production is a very weak function of the process order. Harmonic generation is a promising source of coherent, tunable radiation in the XUV to soft X-ray range which could have a variety of scientific and possibly technological applications. Its conversion from an interesting multiphoton phenomenon to a useful laboratory radiation source requires a complete understanding of both its microscopic and macroscopic aspects. We present some recent results on the response of single atoms at intensities relevant to the short pulse experiments. The calculations employ time-dependent methods, which we briefly review in the next section. Following that we discuss the behavior of the harmonics as a function of laser intensity. Two features are notable: the slow scaling of the harmonic intensities with laser intensity, and the rapid variation in the phase of the individual harmonics with respect to harmonic order. We then give a simple empirical formula that predicts the extent of the plateau for a given ionization potential, wavelength and intensity.

Schafer, K.J.; Krause, J.L.; Kulander, K.C.

1993-06-01T23:59:59.000Z

242

Search for neutrons from deuterated palladium subject to high electrical currents  

Science Conference Proceedings (OSTI)

Tritium has been detected evolving from samples of deuteriated palladium wires and powders subject to pulsed high voltage at Los Alamos. They wanted to measure whether these samples were emitting neutrons. The idea of pulsing current through the wires and powders was to drive the deuterium in and out by rapid electrical heating. With promising tritium results in hand, the experiments were prepared at Los Alamos, and then taken to BYU and run in the neutron detector located in a tunnel in Provo canyon under 35 m of rock and dirt overburden. The neutrons detector and sample setup are described. Results including total neutron counts, time distributions, and an indication of the energy distributions are discussed. The results do not provide compelling evidence of neutron production, but are not inconsistent with earlier measurements of neutrons and tritium. Difficulties in explaining the difference in tritium and neutron measurements are also discussed. Plans for further work are presented.

Taylor, S.F. [Los Alamos National Lab., NM (United States)]|[Brigham Young Univ., Provo, UT (United States); Claytor, T.N.; Tuggle, D.G. [Los Alamos National Lab., NM (United States); Jones, S.E. [Brigham Young Univ., Provo, UT (United States). Dept. of Physics and Astronomy

1994-04-01T23:59:59.000Z

243

Fast Neutron Detector for Fusion Reactor KSTAR Using Stilbene Scintillator  

E-Print Network (OSTI)

Various neutron diagnostic tools are used in fusion reactors to evaluate different aspects of plasma performance, such as fusion power, power density, ion temperature, fast ion energy, and their spatial distributions. The stilbene scintillator has been proposed for use as a neutron diagnostic system to measure the characteristics of neutrons from the Korea Superconducting Tokamak Advanced Research (KSTAR) fusion reactor. Specially designed electronics are necessary to measure fast neutron spectra with high radiation from a gamma-ray background. The signals from neutrons and gamma-rays are discriminated by the digital charge pulse shape discrimination (PSD) method, which uses total to partial charge ratio analysis. The signals are digitized by a flash analog-to-digital convertor (FADC). To evaluate the performance of the fabricated stilbene neutron diagnostic system, the efficiency of 10 mm soft-iron magnetic shielding and the detection efficiency of fast neutrons were tested experimentally using a 252Cf neutron source. In the results, the designed and fabricated stilbene neutron diagnostic system performed well in discriminating neutrons from gamma-rays under the high magnetic field conditions during KSTAR operation. Fast neutrons of 2.45 MeV were effectively measured and evaluated during the 2011 KSTAR campaign.

Seung Kyu Lee; Byoung-Hwi Kang; Gi-Dong Kim; Yong-Kyun Kim

2011-12-27T23:59:59.000Z

244

Microsoft Word - WFnote-240_Pulse Heating study of structures...  

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

breakdown related parameter estimated as a continuation work of ref 1. Intensive rf breakdown studies in the recent years indicate that RF pulse heating might be one of main...

245

Pulse superimposition calculational methodology for estimating the subcritcality level of nuclear fuel assemblies.  

Science Conference Proceedings (OSTI)

One of the most reliable experimental methods for measuring the subcriticality level of a nuclear fuel assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology simulating the Sjoestrand method, which allows comparing the experimental and analytical reaction rates and the obtained subcriticality levels. In this methodology, the reaction rate is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the delayed fission neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction rate is vanished. The obtained reaction rate is then superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The analytical results of this new calculation methodology have shown an excellent agreement with the experimental data available from the YALINA-Booster facility of Belarus. This methodology can be used to calculate Bell and Glasstone spatial correction factor.

Talamo, A.; Gohar, Y.; Rabiti, C.; Aliberti, G.; Kondev, F.; Smith, D.; Zhong, Z.; Kiyavitskaya, H.; Bournos, V; Fokov, Y.; Routkovskaya, C.; Serafimovich, I. (Nuclear Engineering Division); (INL); (Joint Institute for Power and Nuclear Research-Sosny)

2009-05-01T23:59:59.000Z

246

Topology of forward scattering of neutrons from imperfect multilayers  

SciTech Connect

Neutrons sent at grazing incidence on imperfect multilayers of polymers are scattered both out of and within the plane of reflection. In the latter geometry the scattered intensity is highly structured in two series of ridges, whose loci can be labeled in terms of the neutron momenta. Intersecting ridges show evidence of mode coupling. Similar topology is expected for x-ray scattering.

Felcher, G.P.; Goyette, R.J. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Anastasiadis, S.; Russell, T.P. (IBM Almaden Research Center, San Jose, California 95120 (United States)); Foster, M.; Bates, F. (Department of Chemical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States))

1994-10-01T23:59:59.000Z

247

High-voltage supply for neutron tubes in well-logging applications  

DOE Patents (OSTI)

A high voltage supply is provided for a neutron tube used in well logging. The biased pulse supply of the invention combines DC and full pulse techniques and produces a target voltage comprising a substantial negative DC bias component on which is superimposed a pulse whose negative peak provides the desired negative voltage level for the neutron tube. The target voltage is preferably generated using voltage doubling techniques and employing a voltage source which generates bipolar pulse pairs having an amplitude corresponding to the DC bias level.

Humphreys, D.R.

1982-09-15T23:59:59.000Z

248

Contact ORNL Neutron Sciences  

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

Sciences Organization Charts Neutron Sciences Directorate Associate Laboratory Director for Neutron Sciences, Kelly Beierschmitt Biology and Soft Matter Division Director, Paul...

249

NEUTRON SOURCE  

DOE Patents (OSTI)

A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.

Reardon, W.A.; Lennox, D.H.; Nobles, R.G.

1959-01-13T23:59:59.000Z

250

Spallation Neutron Source | ORNL Neutron Sciences  

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

Spallation Neutron Source SNS site, Spring 2012 The 80-acre SNS site is located on the east end of the ORNL campus and is about a three-minute drive from her sister neutron...

251

DIFFERENTIAL PULSE HEIGHT DISCRIMINATOR  

DOE Patents (OSTI)

Pulse-height discriminators are described, specifically a differential pulse-height discriminator which is adapted to respond to pulses of a band of amplitudes, but to reject pulses of amplitudes greater or less than tbe preselected band. In general, the discriminator includes a vacuum tube having a plurality of grids adapted to cut off plate current in the tube upon the application of sufficient negative voltage. One grid is held below cutoff, while a positive pulse proportional to the amplltude of each pulse is applled to this grid. Another grid has a negative pulse proportional to the amplitude of each pulse simultaneously applied to it. With this arrangement the tube will only pass pulses which are of sufficlent amplitude to counter the cutoff bias but not of sufficlent amplitude to cutoff the tube.

Test, L.D.

1958-11-11T23:59:59.000Z

252

Science | ORNL Neutron Sciences  

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

Neutron Science Neutron Science Neutron Scattering Science Neutrons are one of the fundamental particles that make up matter and have properties that make them ideal for certain types of research. In the universe, neutrons are abundant, making up more than half of all visible matter. Neutron scattering provides information about the positions, motions, and magnetic properties of solids. When a beam of neutrons is aimed at a sample, many neutrons will pass through the material. But some will interact directly with atomic nuclei and "bounce" away at an angle, like colliding balls in a game of pool. This behavior is called neutron diffraction, or neutron scattering. Using detectors, scientists can count scattered neutrons, measure their energies and the angles at which they scatter, and map their final position

253

Laser pulse stacking method  

DOE Patents (OSTI)

A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

Moses, E.I.

1992-12-01T23:59:59.000Z

254

Laser pulse stacking method  

DOE Patents (OSTI)

A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter.

Moses, Edward I. (Livermore, CA)

1992-01-01T23:59:59.000Z

255

Generation of Femtosecond Electron Pulses  

SciTech Connect

At the Fast Neutron Research Facility (FNRF), Chiang Mai University (Thailand), the SURIYA project has been established aiming to produce femtosecond electron pulses utilizing a combination of an S-band thermionic rf gun and a magnetic bunch compressor ({alpha}-magnet). A specially designed rf-gun has been constructed to obtain optimum beam characteristics for the best bunch compression. Simulation results show that bunch lengths as short as about 50 fs rms can be expected at the experimental station. The electron bunch lengths will be determined using autocorrelation of coherent transition radiation (TR) through a Michelson interferometer. The paper discusses beam dynamics studies, design, fabrication and cold tests of the rf-gun as well as presents the project current status and forth-coming experiments.

Jinamoon, V.; Kusoljariyakul, K.; Rimjaem, S.; Saisut, J.; Thongbai, C.; Vilaithong, T.; /Chiang Mai U.; Rhodes, M.W.; Wichaisirimongkol, P.; /Chiang Mai U.; Chumphongphan,; /Mae Fah Luang U.; Wiedemann, H.; /SLAC, SSRL

2005-05-09T23:59:59.000Z

256

ORNL neutron facilities deliver neutrons  

Science Conference Proceedings (OSTI)

The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) resumed full power operations on May 16, 2007. There were three experiment cycles of 23 to 25 days in FY2007 and another six are proposed for FY2008 beginning in November 2007. During FY 2007, the High Flux Isotope Reactor delivered 1178 operating hours to users. Commissioning of two SANS instruments is under way and these instruments will join the user program in 2008. The Neutron Scattering Science Advisory Committee endorsed language encouraging development of the science case for two instruments proposed for HFIR.

Ekkebus, Allen E [ORNL

2008-01-01T23:59:59.000Z

257

Intense pulsed light sintering of copper nanoink for printed electronics  

E-Print Network (OSTI)

Skyscan 1172). Electrical resistivity of the sinteredresponsible for the electrical resistivity (5 Ķ cm) of theb) 3D view Fig. 10 Electrical resistivity of copper nanoink

Kim, Hak-Sung; Dhage, Sanjay R.; Shim, Dong-Eun; Hahn, H. Thomas

2009-01-01T23:59:59.000Z

258

Neutron-flux profile monitor for use in a fission reactor  

DOE Patents (OSTI)

A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occurred. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Kopp, M.K.; Valentine, K.H.

1981-09-15T23:59:59.000Z

259

Biology and Soft Matter | Neutron Sciences | ORNL  

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

Biology and Soft Matter Biology and Soft Matter SHARE Biology and Soft Matter This is a time of unprecedented opportunity for using neutrons in biological and soft matter research. The US Department of Energy (DOE) has invested in two forefront neutron user facilities, the accelerator-based Spallation Neutron Source (SNS) and the reactor-based High Flux Isotope Reactor (HFIR), at Oak Ridge National Laboratory (ORNL). Researchers have access to new instrumentation on some of the world's most intense neutron beam lines for studying the structure, function, and dynamics of complex systems. We anticipate that soft matter and biological sciences of tomorrow will require understanding, predicting, and manipulating complex systems to produce the new materials and products required to meet our nation's

260

Neutron-driven gamma-ray laser  

DOE Patents (OSTI)

A lasing cylinder emits laser radiation at a gamma-ray wavelength of 0.87 {angstrom} when subjected to an intense neutron flux of about 400 eV neutrons. A 250 {angstrom} thick layer of Be is provided between two layers of 100 {angstrom} thick layer of {sup 57}Co and these layers are supported on a foil substrate. The coated foil is coiled to form the lasing cylinder. Under the neutron flux {sup 57}Co becomes {sup 58}Co by neutron absorption. The {sup 58}Co then decays to {sup 57}Fe by 1.6 MeV proton emission. {sup 57}Fe then transitions by mesne decay to a population inversion for lasing action at 14.4 keV. Recoil from the proton emission separates the {sup 57}Fe from the {sup 57}Co and into the Be, where Mossbauer emission occurs at a gamma-ray wavelength.

Bowman, C.D.

1989-03-28T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Neutron-driven gamma-ray laser  

DOE Patents (OSTI)

A lasing cylinder emits laser radiation at a gamma-ray wavelength of 0.87 .ANG. when subjected to an intense neutron flux of about 400 eV neutrons. A 250 .ANG. thick layer of Be is provided between two layers of 100 .ANG. thick layer of .sup.57 Co and these layers are supported on a foil substrate. The coated foil is coiled to form the lasing cylinder. Under the neutron flux .sup.57 Co becomes .sup.58 Co by neutron absorption. The .sup.58 Co then decays to .sup.57 Fe by 1.6 MeV proton emission. .sup.57 Fe then transitions by mesne decay to a population inversion for lasing action at 14.4 keV. Recoil from the proton emission separates the .sup.57 Fe from the .sup.57 Co and into the Be, where Mossbauer emission occurs at a gamma-ray wavelength.

Bowman, Charles D. (Los Alamos, NM)

1990-01-01T23:59:59.000Z

262

First Neutron Spectrometry Measurement at the HL-2A Tokamak  

E-Print Network (OSTI)

A compact neutron spectrometer based on the liquid scintillator is presented for neutron energy spectrum measurements at the HL-2A tokamak. The spectrometer was well characterized and a fast digital pulse shape discrimination software was developed using the charge comparison method. A digitizer data acquisition system with a maximum frequency of 1 MHz can work under an environment with a high count rate at HL-2A tokamak. Specific radiation and magnetic shielding for the spectrometer were designed for the neutron spectrum measurement at the HL-2A tokamak. For pulse height spectrum analysis, dedicated numerical simulation utilizing NUBEAM combined with GENESIS was performed to obtain the neutron energy spectrum. Subsequently, the transportation process from the plasma to the detector was evaluated with Monte Carlo calculations. The distorted neutron energy spectrum was folded with the response matrix of the liquid scintillation spectrometer, and good consistency was found between the simulated and measured pulse height spectra. This neutron spectrometer based on a digital acquisition system could be well adopted for the investigation of the auxiliary heating behavior and the fast-ion related phenomenon on different tokamak devices.

Yuan Xi; Zhang Xing; Xie Xufei; Chen Zhongjing; Peng Xingyu; Fan Tieshuan; Chen Jinxiang; Li Xiangqing; Yuan Guoliang; Yang Jinwei; Yang Qingwei

2013-04-10T23:59:59.000Z

263

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

264

Electrical pulse generator  

DOE Patents (OSTI)

A technique for generating high-voltage, wide dynamic range, shaped electrical pulses in the nanosecond range. Two transmission lines are coupled together by resistive elements distributed along the length of the lines. The conductance of each coupling resistive element as a function of its position along the line is selected to produce the desired pulse shape in the output line when an easily produced pulse, such as a step function pulse, is applied to the input line.

Norris, Neil J. (Santa Barbara, CA)

1979-01-01T23:59:59.000Z

265

Optically pulsed electron accelerator  

DOE Patents (OSTI)

An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

Fraser, J.S.; Sheffield, R.L.

1985-05-20T23:59:59.000Z

266

Optically pulsed electron accelerator  

DOE Patents (OSTI)

An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

Fraser, John S. (Los Alamos, NM); Sheffield, Richard L. (Los Alamos, NM)

1987-01-01T23:59:59.000Z

267

NEUTRONIC REACTORS  

DOE Patents (OSTI)

A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

Wigner, E.P.; Young, G.J.

1958-10-14T23:59:59.000Z

268

Deuterium-Tritium Pulse Propulsion with Hydrogen as Propellant and the Entire Spacecraft as a Gigavolt Capacitor for Ignition  

E-Print Network (OSTI)

A deuterium-tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator: 1. By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ~ 105 K. 2. By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

Winterberg, Friedwardt

2012-01-01T23:59:59.000Z

269

Deuterium-Tritium Pulse Propulsion with Hydrogen as Propellant and the Entire Spacecraft as a Gigavolt Capacitor for Ignition  

E-Print Network (OSTI)

A deuterium-tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator: 1. By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ~ 105 K. 2. By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

Friedwardt Winterberg

2012-07-31T23:59:59.000Z

270

The Versatile Neutron Imaging Instrument at SNS | ORNL Neutron...  

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

The Versatile Neutron Imaging Instrument at SNS VENUS: Neutron imaging to advance energy efficiency VENUS: Neutron imaging to advance energy efficiency. As its name indicates,...

271

Cosmogenic neutron-capture-produced nuclides in stony meteorites  

SciTech Connect

The distribution of neutrons with energies below 15 MeV in spherical stony meteoroids is calculated using the ANISN neutron-transport code. The source distributions and intensities of neutrons are calculated using cross sections for the production of tritium. The meteoroid's radius and chemical composition strongly influence the total neutron flux and the neutron energy spectrum, while the location within a meteoroid only affects the relative neutron intensities. Meteoroids need to have radii of more than 50 g/cm/sup 2/ before they have appreciable fluxes of neutrons near thermal energies. Meteoroids with high hydrogen or low iron contents can thermalize neutrons better than chondrites. Rates for the production of /sup 60/Co, /sup 59/Ni, and /sup 36/Cl are calculated with evaluated neutron-capture cross sections and neutron fluxes determined for carbonaceous chondrites with high hydrogen contents, L-chondrites, and aubrites. For most meteoroids with radii < 300 g/cm/sup 2/, the production rates of these neutron-capture nuclides increase monotonically with depth. The highest calculated /sup 60/Co production rate in an ordinary chondrite is 375 atoms/(min g-Co) at the center of a meteoroid with a 250 g/cm/sup 2/ radius. The production rates calculated for spallogenic /sup 60/Co and /sup 59/Ni are greater than the neutron-capture rates for radii less than approx.50-75 g/cm/sup 2/. Only for very large meteoroids and chlorine-rich samples is the neutron-capture production of /sup 36/Cl important. The results of these calculations are compared with those of previous calculations and with measured activities in many meteorites. 44 refs., 15 figs., 1 tab.

Spergel, M.S.; Reedy, R.C.; Lazareth, O.W.; Levy, P.W.

1985-01-01T23:59:59.000Z

272

Neutron Energy Spectrum Measurements with a Compact Liquid Scintillation Detector on EAST  

E-Print Network (OSTI)

A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and gamma-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI (Tl) gamma-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.

Xi Yuan; Xing Zhang; Xufei Xie; G. Gorini; Zhongjing Chen; Xingyu Peng; Jinxiang Chen; Guohui Zhang; Tieshuan Fan; Guoqiang Zhong; Liqun Hu; Baonian Wan

2013-04-27T23:59:59.000Z

273

Optimized laser pulse profile for efficient radiation pressure acceleration of ions  

SciTech Connect

The radiation pressure acceleration regime of laser ion acceleration requires high intensity laser pulses to function efficiently. Moreover the foil should be opaque for incident radiation during the interaction to ensure maximum momentum transfer from the pulse to the foil, which requires proper matching of the target to the laser pulse. However, in the ultrarela-tivistic regime, this leads to large acceleration distances, over which the high laser intensity for a Gaussian laser pulse must be maintained. It is shown that proper tailoring of the laser pulse profile can significantly reduce the acceleration distance, leading to a compact laser ion accelerator, requiring less energy to operate.

Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P. [University of California, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) and University of California, Berkeley, California 94720 (United States)

2012-12-21T23:59:59.000Z

274

Optimized laser pulse profile for efficient radiation pressure acceleration of ions  

Science Conference Proceedings (OSTI)

The radiation pressure acceleration regime of laser ion acceleration requires high intensity laser pulses to function efficiently. Moreover, the foil should be opaque for incident radiation during the interaction to ensure maximum momentum transfer from the pulse to the foil, which requires proper matching of the target to the laser pulse. However, in the ultrarelativistic regime, this leads to large acceleration distances, over which the high laser intensity for a Gaussian laser pulse must be maintained. It is shown that proper tailoring of the laser pulse profile can significantly reduce the acceleration distance, leading to a compact laser ion accelerator, requiring less energy to operate.

Bulanov, S. S. [University of California, Berkeley, California 94720 (United States); Schroeder, C. B.; Esarey, E. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Leemans, W. P. [University of California, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2012-09-15T23:59:59.000Z

275

Imaging with Scattered Neutrons  

E-Print Network (OSTI)

We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-resolution images by scattered neutron radiography and tomography are presented.

H. Ballhausen; H. Abele; R. Gaehler; M. Trapp; A. Van Overberghe

2006-10-30T23:59:59.000Z

276

Neutron cross section measurements at WNR  

DOE Green Energy (OSTI)

The Weapons Neutron Research Facility has been used to obtain moderate-resolution total neutron cross section data for H, C, /sup 208/Pb, /sup 232/Th, /sup 238/U, and /sup 242/Pu over the energy range 5 to 200 MeV. Neutrons were produced by bombarding a 2.5-cm diam by 15-cm long Ta target with an 800 MeV pulsed proton beam from LAMPF. A 10.2-cm diam by 15.2-cm thick NE110 proton recoil detector was used at a flight path of 32 meters, giving a time-of-flight resolution of 60 ps/m. The total cross section results are compared to ENDF/BV evaluations and to previous data where possible.

Lisowski, P.W.; Archampaugh, G.F.; Moore, M.S.; Morgan, G.L.; Shamu, R.E.

1980-01-01T23:59:59.000Z

277

Use of ultracold neutrons for condensed-matter studies  

SciTech Connect

Ultracold neutrons have such low velocities that they are reflected by most materials at all incident angles and can be stored in material bottles for long periods of time during which their intrinsic properties can be studied in great detail. These features have been mainly used for fundamental-physics studies including the detection of a possible neutron electric dipole moment and the precise determination of neutron-decay properties. Ultracold neutrons can also play a role in condensed-matter studies with the help of high-resolution spectrometers that use gravity as a strongly dispersive medium for low-velocity neutrons. Such studies have so far been limited by the low intensity of existing ultracold-neutron sources but could be reconsidered with more intense sources, which are now envisaged. This report provides a broad survey of the properties of ultracold neutrons (including their reflectivity by different types of samples), of ultracold-neutron spectrometers that are compared with other high-resolution instruments, of results obtained in the field of condensed matter with these instruments, and of neutron microscopes. All these subjects are illustrated by numerous examples.

Michaudon, A.

1997-05-01T23:59:59.000Z

278

Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method  

DOE Patents (OSTI)

A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0.times.10.sup.9 neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use.

Yoon, Woo Y. (Idaho Falls, ID); Jones, James L. (Idaho Falls, ID); Nigg, David W. (Idaho Falls, ID); Harker, Yale D. (Idaho Falls, ID)

1999-01-01T23:59:59.000Z

279

Directorate Organization | ORNL Neutron Sciences  

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

ORNL Neutron Sciences Directorate The Neutron Sciences Directorate (NScD) manages and operates the Spallation Neutron Source and the High Flux Isotope Reactor, two of the world's...

280

A Survey of Students from the National School on Neutron and X-ray Scattering: Communication Habits and Preferences  

Science Conference Proceedings (OSTI)

Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world. And the SNS is one of the world's most intense pulse neutron beams. Management of these resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD started conducting the National School on Neutron and X-ray Scattering (NXS) in conjunction with the Advanced Photon Source (APS) at Argonne National Laboratory in 2007. This survey was conducted to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites and social media, for communicating with students about neutron science The survey was conducted in two phases using a classic qualitative investigation to confirm language and content followed by a survey designed to quantify issues, assumptions, and working hypotheses. Phase I consisted of a focus group in late June 2010 with students attending NXS. The primary intent of the group was to inform development of an online survey. Phase two consisted of an online survey that was developed and pre-tested in July 2010 and launched on August 9, 2010 and remained in the field until September 9, 2010. The survey achieved an overall response rate of 48% for a total of 157 completions. The objective of this study is to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites, social media, for communicating with students about neutron science.

Bryant, Rebecca [Bryant Research, LLC

2010-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

High intensity performance and upgrades at the Brookhaven AGS  

SciTech Connect

For the last two years the Brookhaven AGS has operated the slow extracted beam program at record proton intensities. This high beam intensity allowed for the simultaneous operation of three high precision rare kaon decay experiments. The record beam intensities were achieved after the 1.5 GeV Booster was commissioned and a transition jump system, a powerful transverse damper, and an rf upgrade in the AGS were completed. Recently even higher intensity proton synchrotrons are studied for neutron spallation sources or proton driver for a muon collider. Implications of the experiences from the AGS to these proposals and also possible future upgrades for the AGS are discussed.

Roser, T.

1996-12-31T23:59:59.000Z

282

Stress pulse phenomena  

Science Conference Proceedings (OSTI)

This paper is an introductory discussion of stress pulse phenomena in simple solids and fluids. Stress pulse phenomena is a very rich and complex field that has been studied by many scientists and engineers. This paper describes the behavior of stress pulses in idealized materials. Inviscid fluids and simple solids are realistic enough to illustrate the basic behavior of stress pulses. Sections 2 through 8 deal with the behavior of pressure pulses. Pressure is best thought of as the average stress at a point. Section 9 deals with shear stresses which are most important in studying solids.

McGlaun, M.

1993-08-01T23:59:59.000Z

283

Use of the WNR spallation neutron source at LAMPF to determine the absolute efficiency of a neutron scintillation detector  

DOE Green Energy (OSTI)

Prompt fission neutron spectrum measurements at the University of Massachusetts Lowell 5.5 MV Van de Graaff accelerator laboratory require that the neutron detector efficiency be well known over a neutron energy range of 100 keV to 20 MeV. The efficiency of the detector, has been determined for energies greater than 5.0 MeV using the Weapons Neutron Research (WNR) white neutron source at the Los Alamos Meson Physics Facility (LAMPF) in a pulsed beam, time-of-flight (TOF) experiment. Carbon matched polyethylene and graphite scatterers were used to obtain a hydrogen spectrum. The detector efficiency was determined using the well known H(n,n) scattering cross section. Results are compared to the detector efficiency calculation program SCINFUL available from the Radiation Shielding Information Center at Oak Ridge National Laboratory.

Staples, P.A.; Egan, J.J.; Kegel, G.H.R.; Woodring, M.L.; DeSimone, D.J. [University of Massachusetts, Lowell, MA (United States). Dept. of Physics and Applied Physics; Lisowski, P.W. [Los Alamos National Lab., NM (United States)

1994-06-01T23:59:59.000Z

284

OECD energy intensity  

Science Conference Proceedings (OSTI)

to examine OECD countries' energy intensity levels (i.e., the ratio of energy ... steady-state or long-run distribution of energy intensity for the Organisation of†...

285

NEUTRONIC REACTOR  

DOE Patents (OSTI)

This patent relates to neutronic reactors of the heterogeneous water cooled type, and in particular to a fuel element charging and discharging means therefor. In the embodiment illustrated the reactor contains horizontal, parallel coolant tubes in which the fuel elements are disposed. A loading cart containing a magnzine for holding a plurality of fuel elements operates along the face of the reactor at the inlet ends of the coolant tubes. The loading cart is equipped with a ram device for feeding fuel elements from the magazine through the inlot ends of the coolant tubes. Operating along the face adjacent the discharge ends of the tubes there is provided another cart means adapted to receive irradiated fuel elements as they are forced out of the discharge ends of the coolant tubes by the incoming new fuel elements. This cart is equipped with a tank coataining a coolant, such as water, into which the fuel elements fall, and a hydraulically operated plunger to hold the end of the fuel element being discharged. This inveation provides an apparatus whereby the fuel elements may be loaded into the reactor, irradiated therein, and unloaded from the reactor without stopping the fiow of the coolant and without danger to the operating personnel.

Ohlinger, L.A.; Wigner, E.P.; Weinberg, A.M.; Young, G.J.

1958-09-01T23:59:59.000Z

286

Neutron streak camera  

DOE Patents (OSTI)

Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

Wang, C.L.

1981-05-14T23:59:59.000Z

287

Organic metal neutron detector  

DOE Patents (OSTI)

A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

Butler, M.A.; Ginley, D.S.

1984-11-21T23:59:59.000Z

288

Layered semiconductor neutron detectors  

SciTech Connect

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Mao, Samuel S; Perry, Dale L

2013-12-10T23:59:59.000Z

289

MATERIALS FOR SPALLATION NEUTRON SOURCES: IV: Neutronics  

Science Conference Proceedings (OSTI)

The Department of Energy has initiated a pre-conceptual design study for the National Spallation Neutron Source (NSNS) and given preliminary approval for the†...

290

PULSE RATE DIVIDER  

DOE Patents (OSTI)

A compact pulse-rate divider circuit affording low impedance output and high input pulse repetition rates is described. The circuit features a single secondary emission tube having a capacitor interposed between its dynode and its control grid. An output pulse is produced at the anode of the tube each time an incoming pulse at the control grid drives the tube above cutoff and the duration of each output pulse corresponds to the charging time of the capacitor. Pulses incoming during the time the grid bias established by the discharging capacitor is sufficiently negative that the pulses are unable to drive the tube above cutoff do not produce output pulses at the anode; these pulses are lost and a dividing action is thus produced by the circuit. The time constant of the discharge path may be vanied to vary in turn the division ratio of the circuit; the time constant of the charging circuit may be varied to vary the width of the output pulses. (AEC)

McDonald, H.C. Jr.

1962-12-18T23:59:59.000Z

291

PULSE AMPLITUDE ANALYZER  

DOE Patents (OSTI)

A pulse-height analyzer system of improved design for sorting and counting a series of pulses, such as provided by a scintillation detector in nuclear radiation measurements, is described. The analyzer comprises a main transmission line, a cathode-ray tube for each section of the line with its deflection plates acting as the line capacitance; means to bias the respective cathode ray tubes so that the beam strikes a target only when a prearranged pulse amplitude is applied, with each tube progressively biased to respond to smaller amplitudes; pulse generating and counting means associated with each tube to respond when the beam is deflected; a control transmission line having the same time constant as the first line per section with pulse generating means for each tube for initiating a pulse on the second transmission line when a pulse triggers the tube of corresponding amplitude response, the former pulse acting to prevent successive tubes from responding to the pulse under test. This arrangement permits greater deflection sensitivity in the cathode ray tube and overcomes many of the disadvantages of prior art pulse-height analyzer circuits.

Gray, G.W.; Jensen, A.S.

1957-10-22T23:59:59.000Z

292

Pulsed Power Technology at Sandia National Laboratories  

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

News and Reviews News and Reviews Pulsed Power in the News Nuclear fusion simulation shows high-gain energy output (March 2012) Rapid-fire pulse brings Sandia Z method closer to goal of high-yield fusion reactor (April 2007) Ice created in nanoseconds by Sandia's Z machine (March 2007) Z-Machine Shockwaves Melt Diamond (November 2006) Phase diagram of water revised by Sandia researchers (October 2006) Z fires objects faster than Earth moves through space (June 6, 2005) Sandia imagists view imploding wire arrays on Z (November 10, 2004) Z's $61.7 million refurbishment to advance capabilities (October 21, 2004) Z produces fusion neutrons (April 7, 2003) Former shock physics manager (Asay) elected to NAE (February 20, 2003) Z-Beamlet image shows Z evenly compresses pellet (August 30, 2001)

293

PULSE AMPLITUDE ANALYZER  

DOE Patents (OSTI)

This patent pertains to pulse amplitude analyzers for sorting and counting a serles of pulses, and specifically discloses an analyzer which ls simple in construction and presents the puise height distribution visually on an oscilloscope screen. According to the invention, the pulses are applied to the vertical deflection plates of an oscilloscope and trigger the horizontal sweep. Each pulse starts at the same point on the screen and has a maximum amplitude substantially along the same vertical line. A mask is placed over the screen except for a slot running along the line where the maximum amplitudes of the pulses appear. After the slot has been scanned by a photocell in combination with a slotted rotating disk, the photocell signal is displayed on an auxiliary oscilloscope as vertical deflection along a horizontal time base to portray the pulse amplitude distribution.

Greenblatt, M.H.

1958-03-25T23:59:59.000Z

294

Performances of BNL high-intensity synchrotrons  

SciTech Connect

The AGS proton synchrotron was completed in 1960 with initial intensity in the 10 to the 10th power proton per pulse (ppp) range. Over the years, through many upgrades and improvements, the AGS now reached an intensity record of 6.3 {times} 10{sup 13} ppp, the highest world intensity record for a proton synchrotron on a single pulse basis. At the same time, the Booster reached 2.2 {times} 10{sup 13} ppp surpassing the design goal of 1.5 {times} 10{sup 13} ppp due to the introduction of second harmonic cavity during injection. The intensity limitation caused by space charge tune spread and its relationship to injection energy at 50 MeV, 200 MeV, and 1,500 MeV will be presented as well as many critical accelerator manipulations. BNL currently participates in the design of an accumulator ring for the SNS project at Oak Ridge. The status on the issues of halo formation, beam losses and collimation are also presented.

Weng, W.T.

1998-03-01T23:59:59.000Z

295

Instruments | Neutron Science | ORNL  

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

NScD Careers NScD Careers Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | Instruments SHARE Instruments at SNS and HFIR SNS Instrument Name HFIR Instrument Name 1B NOMAD - Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS - Backscattering Spectrometer CG-1D IMAGING - Neutron Imaging Prototype Facility 3 SNAP - Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS - General-Purpose Small-Angle Neutron Scattering Diffractometer 4A MR - Magnetism Reflectometer CG-3 Bio-SANS - Biological Small-Angle Neutron Scattering Instrument 4B LR - Liquids Reflectometer CG-4C CTAX - Cold Neutron Triple-Axis Spectrometer 5 CNCS - Cold Neutron Chopper Spectrometer HB-1 PTAX - Polarized Triple-Axis Spectrometer

296

Ultrafast neutron detector  

DOE Patents (OSTI)

A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

Wang, C.L.

1985-06-19T23:59:59.000Z

297

Procurement - ORNL Neutron Sciences  

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

for the acquisition of goods and services for neutron scattering operations at SNS and HFIR. If you're interested in conducting business with the Neutron Sciences Directorate or...

298

Dependence of terahertz power from laser-produced plasma on laser intensity  

SciTech Connect

Power of terahertz radiation from plasma which is generated from air irradiated by coupled ({omega}, 2{omega}) femtosecond laser pulses is analyzed for high laser intensities, for which non-linear plasma effects on the pulse propagation become essential, with multidimensional particle-in-cell simulations including the self-consistent plasma kinetics. The growth rate of THz power becomes slower as the laser intensity increases. A reason of such a lowering of efficiency in THz emission is found to be ionization of air by the laser pulse, which results in poor focusing of laser pulses.

Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Photon Pioneers Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka (Japan)

2012-07-11T23:59:59.000Z

299

High voltage pulse conditioning  

DOE Patents (OSTI)

Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

Stringfield, R.M.; Wheat, R.M. Jr.

1989-02-21T23:59:59.000Z

300

PULSED INDICATOR CIRCUIT  

DOE Patents (OSTI)

A system is given for detecting incremental changes in a transducer impedance terminating a transmission line. Principal novelty resides in the transducer impedance terminating the line in a mismatch and a pulse generator being provided to apply discrete pulses to the input end of the line. The amplitudes of the pulses reflected to the input end of the line from the mismatched transducer impedance are then observed as a very accurate measure of the instantaneous value of the latter.

Linlor, W.I.; Kerns, Q.A.

1960-11-15T23:59:59.000Z

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


301

High voltage pulse conditioning  

DOE Patents (OSTI)

Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

1990-01-01T23:59:59.000Z

302

Double pulse laser induced breakdown spectroscopy; experimental study of  

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

Double pulse laser induced breakdown spectroscopy; experimental study of Double pulse laser induced breakdown spectroscopy; experimental study of lead emission intensity dependence on the wavelengths and sample matrix Title Double pulse laser induced breakdown spectroscopy; experimental study of lead emission intensity dependence on the wavelengths and sample matrix Publication Type Journal Article Year of Publication 2009 Authors Piscitelli, Vincent, Mauro A. Martinez, Alberto J. Fernandez, Jhanis J. Gonzalez, Xianglei Mao, and Richard E. Russo Journal Spectrochimica Acta Part B Volume 64 Issue 2 Pagination 147-154 Date Published 02/2009 Keywords Double pulse LIBS, laser induced breakdown spectroscopy, lead Abstract Lead (Pb) emission intensity (atomic line 405.78 nm) dependence on the sample matrix (metal alloy) was studied by means of collinear double pulse (DP)-laser induced breakdown spectroscopy (LIBS). The measurement of the emission intensity produced by three different wavelength combinations (i.e. I:532 nm-II:1064 nm, I:532 nm-II:532 nm, and I:532 nm-II:355 nm) from three series of standard reference materials showed that the lead atomic line 405.78 nm emission intensity was dependent on the sample matrix for all the combination of wavelengths, however reduced dependency was found for the wavelength combination I:532 nm-II:355 nm.

303

Neutron Scattering Experiment Automation with Python  

Science Conference Proceedings (OSTI)

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.

Zolnierczuk, Piotr A [ORNL; Riedel, Richard A [ORNL

2010-01-01T23:59:59.000Z

304

PULSE at Stanford University  

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

Photon Science @ SLAC - LCLS - LUSI - SSRL - PULSE - Stanford University Go Search Home Publications Atomic & Molecular Physics Condensed Matter Physics Single Molecule Imaging...

305

Demonstration of Emitted-Neutron Computed Tomography to Quantify Nuclear Materials  

Science Conference Proceedings (OSTI)

In this document, we report demonstration of emitted-neutron computed tomography using fast fission neutrons to infer the geometry of sources of special nuclear material (SNM). The imaging system employed in the demonstration is based on a newly constructed array of pixelated neutron detectors that are suitable for arrangement in a close-packed imaging array and whose active volume consists of liquid scintillator EJ-309 which allows neutron-gamma discrimination via pulse shape to enable essentially pure fast-neutron imaging. The system is capable of high quality fast-neutron imaging where tomographic reconstruction of slices through an object resolves neutron sources similar in dimension to a fuel pellet, or about 1 cm. During measurements of Pu MOX fuel rodlet arrays in soup cans at the INL ZPPR facility, the position of a partial defect of a single rodlet containing Pu replaced by one containing depleted uranium (DU) was detected.

Hausladen, Paul [ORNL; Blackston, Matthew A [ORNL; Newby, Robert Jason [ORNL

2011-09-01T23:59:59.000Z

306

Neutron Log At Alum Area (Moos & Ronne, 2010) | Open Energy Information  

Open Energy Info (EERE)

Neutron Log At Alum Area (Moos & Ronne, 2010) Neutron Log At Alum Area (Moos & Ronne, 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Neutron Log At Alum Geothermal Area (Moos & Ronne, 2010) Exploration Activity Details Location Alum Geothermal Area Exploration Technique Neutron Log Activity Date Usefulness useful DOE-funding Unknown Notes Density, photo-electric factor (PEF), neutron, and gamma ray (GR) logs provided sufficient information to clearly delineate basement lithologic variations, suggesting that pulsed neutron logs may not in many cases be needed, References Daniel Moos, Joel Ronne (2010) Selecting The Optimal Logging Suite For Geothermal Reservoir Evaluation- Results From The Alum 25-29 Well, Nevada Retrieved from "http://en.openei.org/w/index.php?title=Neutron_Log_At_Alum_Area_(Moos_%26_Ronne,_2010)&oldid=511025"

307

Advanced neutron absorber materials  

DOE Patents (OSTI)

A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

Branagan, Daniel J. (Idaho Falls, ID); Smolik, Galen R. (Idaho Falls, ID)

2000-01-01T23:59:59.000Z

308

Arsenic activation neutron detector  

DOE Patents (OSTI)

A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

Jacobs, E.L.

1980-01-28T23:59:59.000Z

309

Physics @ Oxford SCATTERING NEUTRONS  

E-Print Network (OSTI)

1 Neutron Scattering Society of America (NSSA) Purpose and New Initiatives www.neutronscattering.org SNS/ANL School on Neutron and X-Ray Scattering June 2011 Visit us now on Facebook #12;2 What is the NSSA? NSSA is an organization of scientists and engineers with a common interest in using neutron

Herz, Laura M.

310

Analysis of pulse-shape discrimination techniques for BC501A using GHz digital signal processing  

SciTech Connect

A comparison study of pulse-shape analysis techniques was conducted for a BC501A scintillator using digital signal processing (DSP). In this study, output signals from a preamplifier were input directly into a 1 GHz analog-to-digital converter. The digitized data obtained with this method was post-processed for both pulse-height and pulse-shape information. Several different analysis techniques were evaluated for neutron and gamma-ray pulse-shape discrimination. It was surprising that one of the simplest and fastest techniques resulted in some of the best pulse-shape discrimination results. This technique, referred to here as the Integral Ratio technique, was able to effectively process several thousand detector pulses per second. This paper presents the results and findings of this study for various pulse-shape analysis techniques with digitized detector signals.

Rooney, B. D. (Brian D.); Dinwiddie, D. R. (Derek R.); Nelson, M. A. (Mark A.); Rawool-Sullivan, Mohini W.

2001-01-01T23:59:59.000Z

311

Computational Simulations of High Intensity X-Ray Matter Interaction  

SciTech Connect

Free electron lasers have the promise of producing extremely high-intensity short pulses of coherent, monochromatic radiation in the 1-10 keV energy range. For example, the Linac Coherent Light Source at Stanford is being designed to produce an output intensity of 2 x 10{sup 14} W/cm{sup 2} in a 230 fs pulse. These sources will open the door to many novel research studies. However, the intense x-ray pulses may damage the optical components necessary for studying and controlling the output. At the full output intensity, the dose to optical components at normal incidence ranges from 1-10 eV/atom for low-Z materials (Z < 14) at photon energies of 1 keV. It is important to have an understanding of the effects of such high doses in order to specify the composition, placement, and orientation of optical components, such as mirrors and monochromators. Doses of 10 eV/atom are certainly unacceptable since they will lead to ablation of the surface of the optical components. However, it is not precisely known what the damage thresholds are for the materials being considered for optical components for x-ray free electron lasers. In this paper, we present analytic estimates and computational simulations of the effects of high-intensity x-ray pulses on materials. We outline guidelines for the maximum dose to various materials and discuss implications for the design of optical components.

London, R A; Rionta, R; Tatchyn, R; Roessler, S

2001-08-02T23:59:59.000Z

312

A laser-induced repetitive fast neutron source applied for gold activation analysis  

SciTech Connect

A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 Multiplication-Sign 10{sup 5} n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He{sup 4} nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T{sup 3}.

Lee, Sungman; Park, Sangsoon; Lee, Kitae; Cha, Hyungki [Quantum Optics Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of)

2012-12-15T23:59:59.000Z

313

-- Why Use Neutrons? -- Neutron Sources -- Continuous vs ...  

Science Conference Proceedings (OSTI)

... Pulsed Sources: -- WNR/PSR LANSCE (Los Alamos). http://lansce.lanl.gov -- SNS (Oak Ridge National Lab). http://www.sns.gov. Page 6. ...

2011-11-01T23:59:59.000Z

314

High energy neutron dosimeter  

DOE Patents (OSTI)

A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

Rai, K.S.F.

1994-01-11T23:59:59.000Z

315

High energy neutron dosimeter  

DOE Patents (OSTI)

A device for measuring dose equivalents in neutron radiation fields. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning.

Sun, Rai Ko S.F. (Albany, CA)

1994-01-01T23:59:59.000Z

316

Schwinger Vacuum Pair Production in Chirped Laser Pulses  

E-Print Network (OSTI)

The recent developments of high intensity ultra-short laser pulses have raised the hopes of observing Schwinger vacuum pair production which is one of the important non-perturbative phenomena in Quantum electrodynamics (QED). The quantitative analysis of realistic high intensity laser pulses is vital for understanding the effect of the field parameters on the momentum spectrum of the produced particles. In this study, we analyze chirped laser pulses with a sub-cycle structure, and investigate the effects of the chirp parameter on the momentum spectrum of the produced particles. The combined effect of the chirp and carrier phase of the laser pulse is also analyzed. These effects are qualitatively explained by investigating the turning point structure of the potential within the framework of the complex WKB scattering approach to pair production.

Cesim K. Dumlu

2010-06-19T23:59:59.000Z

317

Neutronic design studies for the MIT fission converter beam  

SciTech Connect

Currently available epithermal neutron beams at the Massachusetts Institute of Technology (MIT) are not sufficiently intense to meet the anticipated demand for boron neutron capture therapy (BNCT) treatments if initial, currently in progress clinical trials of BNCT prove successful. Indeed, they are not really adequate for extensive (phase-III) clinical trials. To fulfill this need, a high-intensity, high-quality fission converter-based epithermal neutron beam for BNCT has been designed for the MIT Research Reactor, (MITR-II). This epithermal neutron beam, capable of delivering treatments in a few minutes with negligible beam background contamination, would be installed in the present thermal column and hohlraum of the MITR-II.

Kiger, W.S. III; Harling, O.K. [Massachusetts Inst. of Technology, Cambridge, MA (United States)

1996-12-31T23:59:59.000Z

318

PULSE AMPLITUDE DISTRIBUTION RECORDER  

DOE Patents (OSTI)

A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

Cowper, G.

1958-08-12T23:59:59.000Z

319

Pulsed wave interconnect  

Science Conference Proceedings (OSTI)

Pulsed wave interconnect is proposed for global interconnect applications. Signals are represented by localized wavepackets that propagate along the interconnect lines at the local speed of light to trigger the receivers. Energy consumption is reduced ... Keywords: CMOS, VLSI, high-speed interconnect, nonlinear transmission line, pulse compression, soliton, wafer-scale-integration

Pingshan Wang; Gen Pei; Edwin Chih-Chuan Kan

2004-05-01T23:59:59.000Z

320

PULSE HEIGHT ANALYZER  

DOE Patents (OSTI)

An anticoincidence device is described for a pair of adjacent channels of a multi-channel pulse height analyzer for preventing the lower channel from generating a count pulse in response to an input pulse when the input pulse has sufficient magnitude to reach the upper level channel. The anticoincidence circuit comprises a window amplifier, upper and lower level discriminators, and a biased-off amplifier. The output of the window amplifier is coupled to the inputs of the discriminators, the output of the upper level discriminator is connected to the resistance end of a series R-C network, the output of the lower level discriminator is coupled to the capacitance end of the R-C network, and the grid of the biased-off amplifier is coupled to the junction of the R-C network. In operation each discriminator produces a negative pulse output when the input pulse traverses its voltage setting. As a result of the connections to the R-C network, a trigger pulse will be sent to the biased-off amplifier when the incoming pulse level is sufficient to trigger only the lower level discriminator.

Johnstone, C.W.

1958-01-21T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Neutron Radiography and Fission Mapping Measurements of Nuclear Materials with Varying Composition and Shielding  

Science Conference Proceedings (OSTI)

Neutron radiography and fission mapping measurements were performed on four measurement objects with varying composition and shielding arrangements at the Idaho National Laboratory's Zero Power Physics Reactor (ZPPR) facility. The measurement objects were assembled with ZPPR reactor plate materials comprising plutonium, natural uranium, or highly enriched uranium and were presented as unknowns for characterization. As a part of the characterization, neutron radiography was performed using a deuterium-tritium (D-T) neutron generator as a source of time and directionally tagged 14 MeV neutrons. The neutrons were detected by plastic scintillators placed on the opposite side of the object, using the time-correlation-based data acquisition of the Nuclear Materials Identification System developed at Oak Ridge National Laboratory. Each object was measured at several rotations with respect to the neutron source to obtain a tomographic reconstruction of the object and a limited identification of materials via measurement of the neutron attenuation. Large area liquid scintillators with pulse shape discrimination were used to detect the induced fission neutrons. A fission site map reconstruction was produced by time correlating the induced fission neutrons with each tagged neutron from the D-T neutron generator. This paper describes the experimental configuration, the ZPPR measurement objects used, and the neutron imaging and fission mapping results.

Mullens, James Allen [ORNL; McConchie, Seth M [ORNL; Hausladen, Paul [ORNL; Mihalczo, John T [ORNL; Grogan, Brandon R [ORNL; Sword, Eric D [ORNL

2011-01-01T23:59:59.000Z

322

Calibration of the neutron detectors for the cluster fusion experiment on the Texas Petawatt Laser  

Science Conference Proceedings (OSTI)

Three types of neutron detectors (plastic scintillation detectors, indium activation detectors, and CR-39 track detectors) were calibrated for the measurement of 2.45 MeV DD fusion neutron yields from the deuterium cluster fusion experiment on the Texas Petawatt Laser. A Cf-252 neutron source and 2.45 MeV fusion neutrons generated from laser-cluster interaction were used as neutron sources. The scintillation detectors were calibrated such that they can detect up to 10{sup 8} DD fusion neutrons per shot in current mode under high electromagnetic pulse environments. Indium activation detectors successfully measured neutron yields as low as 10{sup 4} per shot and up to 10{sup 11} neutrons. The use of a Cf-252 neutron source allowed cross calibration of CR-39 and indium activation detectors at high neutron yields ({approx}10{sup 11}). The CR-39 detectors provided consistent measurements of the total neutron yield of Cf-252 when a modified detection efficiency of 4.6 Multiplication-Sign 10{sup -4} was used. The combined use of all three detectors allowed for a detection range of 10{sup 4} to 10{sup 11} neutrons per shot.

Bang, W.; Quevedo, H. J.; Dyer, G.; Rougk, J.; Kim, I.; McCormick, M.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

2012-06-15T23:59:59.000Z

323

Pulsed electron beam precharger  

Science Conference Proceedings (OSTI)

Florida State University is investigating the concept of pulsed electron beams for fly ash precipitation. This report describes the results and data on three of the subtasks of this project and preliminary work only on the remaining five subtasks. Described are the modification of precharger for pulsed and DC energization of anode; installation of the Q/A measurement system; and modification and installation of pulsed power supply to provide both pulsed and DC energization of the anode. The other tasks include: measurement of the removal efficiency for monodisperse simulated fly ash particles; measurement of particle charge; optimization of pulse energization schedule for maximum removal efficiency; practical assessment of results; and measurement of the removal efficiency for polydisperse test particles. 15 figs., 1 tab. (CK)

Finney, W.C. (ed.); Shelton, W.N.

1990-01-01T23:59:59.000Z

324

Determination of the Axial-Vector Weak Coupling Constant with Ultracold Neutrons  

Science Conference Proceedings (OSTI)

A precise measurement of the neutron decay {beta} asymmetry A{sub 0} has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A{sub 0}=-0.119 66{+-}0.000 89{sub -0.00140}{sup +0.00123}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon g{sub A}/g{sub V}=-1.275 90{sub -0.00445}{sup +0.00409}.

Liu, J. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Department of Physics, Shanghai Jiao Tong University, Shanghai, 200240 (China); Mendenhall, M. P.; Carr, R.; Filippone, B. W.; Hickerson, K. P.; Perez Galvan, A.; Russell, R. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Holley, A. T.; Hoagland, J.; VornDick, B. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Back, H. O.; Pattie, R. W. Jr.; Young, A. R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708 (United States); Bowles, T. J.; Clayton, S.; Currie, S.; Hogan, G. E.; Ito, T. M.; Makela, M.; Morris, C. L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2010-10-29T23:59:59.000Z

325

ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS.  

SciTech Connect

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures.

WEI,J.; MACEK,R.J.

2002-04-14T23:59:59.000Z

326

Imaging and Neutrons - IAN 2006 - Neutron Sciences  

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

SNS Home Saturday, January 11, 2014 SNS Home Saturday, January 11, 2014 Go IAN 2006 Imaging and Neutrons 2006 October 23-25, 2006 Iran Thomas Auditorium Central Laboratory and Office Building Spallation Neutron Source Oak Ridge National Laboratory, Oak Ridge, TN Who Should Attend Synopsis Goals and Expected Outcomes Application Areas Techniques International Advisory Committee Local Organizing Committee Agenda with Presentations NEW Confirmed Speakers Frequently Asked Questions - FAQ Satellite Workshop - Progress in Electron Volt Neutron Spectroscopy eV Worshop Agenda presentations NEW Lodging, Transportation, Bus Schedule Location Directions and Map Registration CLOSED Abstracts, Posters, Contributed Talks Scholarships Sponsors Vendors May Attend Relevant Reports Important Dates Weather Attractions

327

NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR  

DOE Patents (OSTI)

The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

Young, G.J.

1959-06-30T23:59:59.000Z

328

528 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 33, NO. 2, APRIL 2005 Visualization of Current Sheet Evolution in a Pulsed  

E-Print Network (OSTI)

, visualization. PULSED electromagnetic accelerators are devices which use intense bursts of electrical current. Y. Choueiri, "Characterization of current sheet evo- lution in a pulsed electromagnetic accelerator canting in a pulsed electromagnetic accelerator," Phys. Plasmas, vol. 11, no. 10, pp. 4847­4858, Oct. 2004

Choueiri, Edgar

329

Intensity Frontier Instrumentation  

E-Print Network (OSTI)

This report summarizes findings of the 2013 Snowmass Community Summer Study Instrumentation Frontier's subgroup on the Intensity Frontier. This report is directed at identifying instrumentation R&D needed to support particle physics research over the coming decades at the Intensity Frontier.

S. H. Kettell; R. A. Rameika; R. S. Tschirhart

2013-09-26T23:59:59.000Z

330

Light intensity compressor  

DOE Patents (OSTI)

In a system for recording images having vastly differing light intensities over the face of the image, a light intensity compressor is provided that utilizes the properties of twisted nematic liquid crystals to compress the image intensity. A photoconductor or photodiode material that is responsive to the wavelength of radiation being recorded is placed adjacent a layer of twisted nematic liquid crystal material. An electric potential applied to a pair of electrodes that are disposed outside of the liquid crystal/photoconductor arrangement to provide an electric field in the vicinity of the liquid crystal material. The electrodes are substantially transparent to the form of radiation being recorded. A pair of crossed polarizers are provided on opposite sides of the liquid crystal. The front polarizer linearly polarizes the light, while the back polarizer cooperates with the front polarizer and the liquid crystal material to compress the intensity of a viewed scene. Light incident upon the intensity compressor activates the photoconductor in proportion to the intensity of the light, thereby varying the field applied to the liquid crystal. The increased field causes the liquid crystal to have less of a twisting effect on the incident linearly polarized light, which will cause an increased percentage of the light to be absorbed by the back polarizer. The intensity of an image may be compressed by forming an image on the light intensity compressor.

Rushford, Michael C. (Livermore, CA)

1990-01-01T23:59:59.000Z

331

Special Nuclear Materials Detection Using IEC Fusion Pulsed Neutron Source  

Science Conference Proceedings (OSTI)

Experimental Facilities and Nonelectric Applications / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 1)

J. H. Sorebo; G. L. Kulcinski; R. F. Radel; J. F. Santarius

332

High-performance laser processing using manipulated ultrafast laser pulses  

Science Conference Proceedings (OSTI)

We employ manipulated ultrafast laser pulses to realize microprocessing with high-performance. Efficient microwelding of glass substrates by irradiation by a double-pulse train of ultrafast laser pulses is demonstrated. The bonding strength of two photostructurable glass substrates welded by double-pulse irradiation was evaluated to be 22.9 MPa, which is approximately 22% greater than that of a sample prepared by conventional irradiation by a single pulse train. Additionally, the fabrication of hollow microfluidic channels with a circular cross-sectional shape embedded in fused silica is realized by spatiotemporally focusing the ultrafast laser beam. We show both theoretically and experimentally that the spatiotemporal focusing of ultrafast laser beam allows for the creation of a three-dimensionally symmetric spherical peak intensity distribution at the focal spot.

Sugioka, Koji; Cheng Ya; Xu Zhizhan; Hanada, Yasutaka; Midorikawa, Katsumi [RIKEN - Advanced Science Institute, Wako, Saitama 351-0198 (Japan); State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (China); RIKEN - Advanced Science Institute, Wako, Saitama 351-0198 (Japan)

2012-07-30T23:59:59.000Z

333

Laser breakdown in air at ultrahigh laser pulse repetition rates  

SciTech Connect

Some specific features of interaction of intense femtosecond laser pulses with air at ultrahigh pulse repetition rates have been experimentally studied. Data on the dynamics of plasma cloud expansion and the plasma electron density on time intervals no longer than 10 ns are obtained by femtosecond interferometry. These data are interpreted in terms of the most likely mechanisms of ionised gas recombination. The effect of ultrahigh-frequency laser radiation on a medium was modelled by double-pulse irradiation with a short delay {Delta}t between the pulses: from 1 ps to 11 ns. A nonmonotonic dependence of the degree of air ionisation by the second pulse on the delay time {Delta}t is found; possible mechanisms of these dependences are discussed in terms of the processes of femtosecond radiation absorption in the residual plasma. (extreme light fields and their applications)

Kononenko, Vitalii V; Kononenko, Taras V; Pashinin, V P; Gololobov, V M; Konov, Vitalii I [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2013-04-30T23:59:59.000Z

334

Accelerator-based neutron generator (addendum)  

SciTech Connect

A proposal to design, construct, and operate a D--Li intense neutron source for CTR materials research is discussed. Information pertaining to the following areas is given: (1) radiation damage effectiveness, (2) Linac design and performance, (3) target design and performance, (4) experimental area design, (5) construction schedule, (6) construction costs, (7) preliminary design and development program, (8) facility operation and operating costs, and (9) financial appropriation plan. (MOW)

Grand, P. (ed.)

1976-01-01T23:59:59.000Z

335

Propagation of Nd-laser pulses through crystalline silicon wafers  

SciTech Connect

Propagation of pulses from an Nd:YAG laser (wavelength, 1.064 {mu}m; pulse duration, 270 ns; pulse energy, 225 {mu}J) through crystalline silicon wafers is studied experimentally. Mathematical modelling of the process is performed: the heat conduction equation is solved numerically, the temperature dependences of the absorption and refraction of a substance, as well as generation of nonequilibrium carriers by radiation are taken into account. The constructed model satisfactorily explains the experimentally observed intensity oscillations of transmitted radiation. (interaction of laser radiation with matter)

Kirichenko, N A; Kuzmin, P G; Shcherbina, M E [Wave Research Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2011-07-31T23:59:59.000Z

336

Uncertainty evaluation of delayed neutron decay parameters  

E-Print Network (OSTI)

In a nuclear reactor, delayed neutrons play a critical role in sustaining a controllable chain reaction. Delayed neutronís relative yields and decay constants are very important for modeling reactivity control and have been studied for decades. Researchers have tried different experimental and numerical methods to assess these delayed neutron parameters. The reported parameter values vary widely, much more than the small statistical errors reported with these parameters. Interestingly, the reported parameters fit their individual measurement data well in spite of these differences. This dissertation focuses on evaluation of the errors and methods of delayed neutron relative yields and decay constants for thermal fission of U-235. Various numerical methods used to extract the delayed neutron parameter from the measured data, including Matrix Inverse, Levenberg-Marquardt, and Quasi-Newton methods, were studied extensively using simulated delayed neutron data. This simulated data was Poisson distributed around Keepinís theoretical data. The extraction methods produced totally different results for the same data set, and some of the above numerical methods could not even find solutions for some data sets. Further investigation found that ill-conditioned matrices in the objective function were the reason for the inconsistent results. To find a reasonable solution with small variation, a regularization parameter was introduced using a numerical method called Ridge Regression. The results from the Ridge Regression method, in terms of goodness of fit to the data, were good and often better than the other methods. Due to the introduction of a regularization number in the algorithm, the fitted result contains a small additional bias, but this method can guarantee convergence no matter how large the coefficient matrix condition number. Both saturation and pulse modes were simulated to focus on different groups. Some of the factors that affect the solution stability were investigated including initial count rate, sample flight time, initial guess values. Finally, because comparing reported delayed neutron parameters among different experiments is useless to determine if their data actually differs, methods are proposed that can be used to compare the delayed neutron data sets.

Wang, Jinkai

2008-12-01T23:59:59.000Z

337

Development of Neutron Detectors for the Next Generation of Radioactive Ion-Beam Facilities  

E-Print Network (OSTI)

The next generation of radioactive ion beam facilities, which will give experimental access to many exotic nuclei, are presently being developed. These facilities will make it possible to study very short lived exotic nuclei with extreme values of isospin far from the line of beta stability. Such nuclei will be produced with very low cross sections and to study them, new detector arrays are being developed. At the SPIRAL facility in GANIL a neutron detector array, the Neutron Wall, is located. In this work the Neutron Wall has been characterized regarding neutron detection efficiency and discrimination between neutrons and gamma rays. The possibility to increase the efficiency by increasing the high voltage of the photomultiplier tubes has also been studied. For SPIRAL2 a neutron detector array, NEDA, is being developed. NEDA will operate in a high gamma-ray background environment which puts a high demand on the quality of discrimination between neutrons and gamma rays. To increase the quality of the discrimination methods pulse-shape discrimination techniques utilizing digital electronics have been developed and evaluated regarding bit resolution and sampling frequency of the ADC. The conclusion is that an ADC with a bit resolution of 12 bits and a sampling frequency of 100 MS/s is adequate for pulse-shape discrimination of neutrons and gamma rays for a neutron energy range of 0.3-12 MeV.

Pšr-Anders SŲderstrŲm

2009-05-13T23:59:59.000Z

338

A Neutron Star in F-sharp  

E-Print Network (OSTI)

In this short introductory commentary on the paper (Hessels et al 2006, Science, 311, 1901) reporting the discovery of the shortest spin period millisecond pulsar (MSP) Ter5-ad in the globular cluster Terzan 5, I also point out a new explanation for possible minimum spin periods, P, of MSPs without requiring gravitational radiation (or other) slow-down torques. If the accretion of matter required to spinup a MSP also reduces (buries) the neutron star (NS) magnetic field, B, as commonly believed, an inverse correlation between neutron star mass, M, and B is expected together with a positive correlation between P and B. Both are suggested for the 4 MSPs with NS mass measures reported (Latimer and Prakash 2004, Science, 304, 536) to have tested when a timing solution is found. If confirmed, the highest spin frequency NSs do not pulse simply because their B fields are too low.

Jonathan E. Grindlay

2006-05-04T23:59:59.000Z

339

Nonlinear Thomson scattering of an ultrashort laser pulse  

SciTech Connect

The nonlinear scattering of an ultrashort laser pulse by free electrons is considered. The pulse is described in the 'Mexican hat' wavelet basis. The equation of motion for a charged particle in the field of a plane electromagnetic wave has an exact solution allowing, together with the instant spectrum approximation, the calculation of the intensity of nonlinear Thomson scattering for a high-intensity laser pulse. The spectral distribution of scattered radiation for the entire pulse duration is found by integrating with respect to time. The maximum of the emission spectrum of a free electron calculated in 10{sup 19}-10{sup 21} W/cm{sup 2} fields lies in the UV spectral region between 3 and 12 eV. A part of the continuous spectrum achieves high photon energies. One percent of the scattered energy for the field intensity 10{sup 20} W/cm{sup 2} is concentrated in the range h{omega} > 2.7 Multiplication-Sign 10{sup 2} eV, for a field intensity of 10{sup 21} W/cm{sup 2} in the range h{Omega} > 7.9 Multiplication-Sign 10{sup 2} eV, and for an intensity of 10{sup 22} W/cm{sup 2} in the range h{Omega} > 2.45 Multiplication-Sign 10{sup 5} eV. These results allow us to estimate nonlinear scattering as a source of hard X-rays.

Golovinski, P. A., E-mail: golovinski@bk.ru; Mikhin, E. A. [Voronezh State Architectural-Building University (Russian Federation)

2011-10-15T23:59:59.000Z

340

The Neutron Residual Stress Mapping Facility at HFIR | ORNL Neutron...  

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

Neutron Residual Stress Mapping Facility at HFIR Neutron Residual Stress Mapping Facility (HB-2B) Neutron Residual Stress Mapping Facility (HB-2B). The HB-2B beam port is optimized...

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Performance of long-pulse source reference target-moderator-reflector configurations  

DOE Green Energy (OSTI)

We have calculated the performance of five similar target-moderator-reflector geometries that are reasonably well optimized for long-pulse source applications. For all cases, the moderators are fully coupled; that is, no poisons, decouplers, or liners are used. For each case, the energy- and time-dependent characteristics of the moderator source brightness have been parameteterized using empirical functions. These parameterizations have been made available to users of the Monte Carlo neutron scattering instrument design code MCLIB for use in evaluating the performance of neutron scattering instruments on a long-pulse source.

Pitcher, E.J.; Russell, G.J.; Seeger, P.A.; Ferguson, P.D.

1995-12-31T23:59:59.000Z

342

Neutron sources and applications  

Science Conference Proceedings (OSTI)

Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1994-01-01T23:59:59.000Z

343

Pulse measurement apparatus and method  

DOE Patents (OSTI)

An embodiment of the invention is directed to a pulse measuring system that measures a characteristic of an input pulse under test, particularly the pulse shape of a single-shot, nano-second duration, high shape-contrast optical or electrical pulse. An exemplary system includes a multi-stage, passive pulse replicator, wherein each successive stage introduces a fixed time delay to the input pulse under test, a repetitively-gated electronic sampling apparatus that acquires the pulse train including an entire waveform of each replica pulse, a processor that temporally aligns the replicated pulses, and an averager that temporally averages the replicated pulses to generate the pulse shape of the pulse under test. An embodiment of the invention is directed to a method for measuring an optical or an electrical pulse shape. The method includes the steps of passively replicating the pulse under test with a known time delay, temporally stacking the pulses, and temporally averaging the stacked pulses. An embodiment of the invention is directed to a method for increasing the dynamic range of a pulse measurement by a repetitively-gated electronic sampling device having a rated dynamic range capability, beyond the rated dynamic range of the sampling device; e.g., enhancing the dynamic range of an oscilloscope. The embodied technique can improve the SNR from about 300:1 to 1000:1. A dynamic range enhancement of four to seven bits may be achieved.

Marciante, John R. (Webster, NY); Donaldson, William R. (Pittsford, NY); Roides, Richard G. (Scottsville, NY)

2011-10-25T23:59:59.000Z

344

Highly stable pulse stretchers  

SciTech Connect

Highly stable pulse stretchers are described that are designed for fine control of pulse duration in digital pulse shapers of nuclear magnetic resonance spectrometers with a quantization step of 0.1 ..mu..sec. The fine-control range is 20-150 nsec. The stretchers employ a circuit to compensate for the logic-0 voltage and the time delays of the logic elements. The instability of the trailing-edge delay for a supply variation of +/- 0.5 V is less than 0.1%, and the temperature instability in the range of 20-80/sup 0/C is not over (60/t/sub d/)-0.3%, where t/sub d/ is the trailing-edge delay. The inputs and outputs of the pulse stretchers are matcher to TTL and Schottky TTL levels.

Svintenok, V.A.; Nikiforov, E.A.

1988-02-01T23:59:59.000Z

345

Pulse magnetic welder  

DOE Patents (OSTI)

A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

Christiansen, D.W.; Brown, W.F.

1984-01-01T23:59:59.000Z

346

PULSE COLUMN DESIGN  

SciTech Connect

A stagewise approach was used in a theoretical analysis of pulse columns. In the analysis the column was arbitrarily divided into discrete stages comprising that part of the column between two adjacent perforated plates. The operation of the pulse column was described mathematically using material balance equations, and a design method was derived which used two stage lines and two operating lines, one set for the pulse generator upstroke and one set for the downstroke. Assuming equilibrium contact, the effect of recycle in a pulse column was shown to cause a large decrease in the separation obtained as the pulse frequency was increased. Hold-up studies were made using isoamyl alcohol- water, and methyl isobutyl ketone water. The hold-up per cycle of the dispersed phase for both systems was found to be equal to the interstage flow per cycle of the dispersed phase. Hold-up behavior at high frequencies was different for the two systems. Extraction runs were also made using the system methyl isobutyl ketone - acetic acid-water. The effects of recycle were found to result in a drop in column separation efficiency with increased pulse frequency. It was found to be theoretically possible for a column to operate in a pinched-in region even though this is not apparert from an examination of the superficial flow ratio of the two streams being fed to the column Techniques for sampling interstage flow streams in a colurm operating in the mixer-settler region are described. (J.R.D.)

Burkhart, L.E.; Fahien, R.W.

1958-11-01T23:59:59.000Z

347

The Hurricane Intensity Issue  

Science Conference Proceedings (OSTI)

The intensity issue of hurricanes is addressed in this paper using the angular momentum budget of a hurricane in storm-relative cylindrical coordinates and a scale-interaction approach. In the angular momentum budget in storm-relative coordinates,...

T. N. Krishnamurti; S. Pattnaik; L. Stefanova; T. S. V. Vijaya Kumar; B. P. Mackey; A. J. OíShay; Richard J. Pasch

2005-07-01T23:59:59.000Z

348

Neutron-detection apparatus  

DOE Patents (OSTI)

An atomic fission counting apparatus used for neutron detection is provided with spirally curved electrode plates uniformly spaced apart in a circular array and coated with fissile material.

Kopp, M.K.; Valentine, K.H.

1981-04-24T23:59:59.000Z

349

Education | ORNL Neutron Sciences  

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

Matter Physics Neutron Scattering in Quantum Condensed Matter Physics flyer The first cyber enabled collaborative graduate course was launched in Fall semester 2012. It addresses...

350

Industry - ORNL Neutron Sciences  

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

Industry banner Industry banner Neutron scattering research has applications in practically every field, and neutron research at ORNL is leading to productive partnerships with the industrial and business communities. We welcome proposals for all types of research, including those involving proprietary work. Recent studies have led to discoveries with potential applications in fields such as medicine, energy, and various metals technologies. For more information, please see our recent research highlights. Research Collaborations Industry-Driven Research Benefits Plastics Manufacturing Corning uses VULCAN to test limits of ceramic material for car emission controls, filtration devices Neutrons Probe Inner Workings of Batteries Industry and Neutron Science: Working To Make a Match

351

Physics Out Loud - Neutron  

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

Matter Previous Video (Matter) Physics Out Loud Main Index Next Video (Niobium) Niobium Neutron Karl Slifer, a physicist based at the University of New Hampshire and who conducts...

352

Neutron Scattering Facilities  

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

Gaithersburg, Maryland, USA Peruvian Institute of Nuclear Energy (IPEN), Lima, Peru Spallation Neutron Source, Oak Ridge National Laboratory, Tennessee, USA University of...

353

Neutron Scattering Web  

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

at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site. We will leave the current content here for...

354

Magnetization of neutron matter  

SciTech Connect

In this paper, we compute magnetization of neutron matter at strong magnetic field using the lowest order constrained variational (LOCV) technique.

Bigdeli, M. [Department of Physics, Zanjan University, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of)

2011-09-21T23:59:59.000Z

355

NCNR Neutron Spin Filters  

Science Conference Proceedings (OSTI)

... be characterized either by the transmission asymmetry A ... defined to be the transmissions for neutrons ... P sub n, (solid thick line), transmission T sub n ...

356

Neutron detection apparatus  

DOE Patents (OSTI)

An atomic fission counting apparatus used for neutron detection is provided with spirally curved electrode plates uniformly spaced apart in a circular array and coated with fissile material.

Kopp, Manfred K. (Oak Ridge, TN); Valentine, Kenneth H. (Lenoir City, TN)

1983-01-01T23:59:59.000Z

357

Neutron Activation Calculator  

Science Conference Proceedings (OSTI)

... and incoherent scattering cross sections). Source neutrons (Ang, meV or m/s), Density (g/cm 3 or lattice), Thickness (cm). ...

358

Neutrons in Biology, ORNL  

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

Scattering Sciences Division Oak Ridge National Laboratory Phone: 865.241.2897 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...

359

Neutrons in Biology, ORNL  

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

Scattering Sciences Division Oak Ridge National Laboratory Phone: 865.576.2779 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...

360

Neutrons in Biology, ORNL  

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

Materials Division Oak Ridge National Laboratory Phone: 865.241.5176 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...

Note: This page contains sample records for the topic "intense pulsed neutron" 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

ORNL Neutron Sciences Publications  

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

at other facilties by Neutron Sciences Directorate staff. We strongly encourage SNS and HFIR users to submit citation information, including URLs, for all publications regarding...

362

Towards a Neutron Microscope  

Science Conference Proceedings (OSTI)

Towards a Neutron Microscope. Summary: ... The novel lens is a Wolter Optic similar in design to the telescope of the CHANDRA x-ray observatory. ...

2013-07-23T23:59:59.000Z

363

STATISTICAL CORRELATIONS AND INTENSITY SPIKING IN THE SASE FEL.  

SciTech Connect

In the linear regime before saturation, we describe the statistical correlations in the narrow band chaotic output of the SASE FEL. At a fixed position along the undulator axis, we derive joint probability distributions for the intensity in the output pulse to have values I{sub 1} and I{sub 2} at times t{sub 1} and t{sub 2}, and for the spectral intensity to have values {tilde I}{sub 1} and {tilde I}{sub 2} at frequencies {omega}{sub 1} and {omega}{sub 2}. Probability distributions for the peak values of intensity in the time and frequency domains are also determined.

KRINSKY,S.; GLUCKSTERN,R.L.

2001-09-19T23:59:59.000Z

364

Neutrons in Soft Matter Science | Education | ORNL Neutron Sciences  

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

Complex Materials on Mesoscopic Scales Neutron in Soft Matter Science flyer The new cyber-enabled collaborative graduate course "Neutrons in Soft Matter Science: Complex...

365

Neutron Science Facilities Operating Status | ORNL Neutron Sciences  

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

Neutron Science Facilities Operating Status High Flux Isotope Reactor The reactor is currently operating at 100% power for fuel cycle 449. Spallation Neutron Source SNS is shutdown...

366

For the first time, three-dimensional neutron images have been taken of rare  

E-Print Network (OSTI)

that substantiate their existence. The two-year experimental campaign began with a 250-day irradiation in HFIR filtering out the rest. The extreme intensity of HFIR's neutron beam enables this technique to achieve good

367

Physics design of a cold neutron source for KIPT neutron source facility.  

SciTech Connect

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the meV energy range through scattering reactions in the moderator and reflector materials. However, the fraction of neutrons with energies less than 5 meV in a normal moderator spectrum is very low because of up-scattering caused by the thermal motion of moderator or reflector molecules. In order to obtain neutrons with energy less than 5 meV, cryogenically cooled moderators 'cold neutron sources' should be used to slow down the neutrons. These cold moderators shift the neutron energy spectrum down because the thermal motion of moderator molecules as well as the up-scattering is very small, which provides large gains in intensity of low energy neutrons, E < 5 meV. The accelerator driven subcritical facility is designed with a provision to add a cryogenically cooled moderator system. This cold neutron source could provide the neutrons beams with lower energy, which could be utilized in scattering experiment and material structures analysis. This study describes the performed physics analyses to define and characterize the cold neutron source of the KIPT neutron source facility. The cold neutron source is designed to optimize the cold neutron brightness to the experimental instruments outside the radial heavy concrete shield of the facility. Liquid hydrogen or solid methane with 20 K temperature is used as a cold moderator. Monte Carlo computer code MCNPX [4], with ENDF/B-VI nuclear data libraries, is utilized to calculate the cold neutron source performance and estimate the nuclear heat load to the cold moderator. The surface source generation capability of MCNPX code has been used to provide the possibility of analyzing different design configurations and perform design optimization analyses with reasonable computer resources. Several design configurations were analyzed and their performance were characterized and optimized.

Zhong, Z.; Gohar, Y.; Kellogg, R.; Nuclear Engineering Division

2009-02-17T23:59:59.000Z

368

Physics design of a cold neutron source for KIPT neutron source facility.  

Science Conference Proceedings (OSTI)

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the meV energy range through scattering reactions in the moderator and reflector materials. However, the fraction of neutrons with energies less than 5 meV in a normal moderator spectrum is very low because of up-scattering caused by the thermal motion of moderator or reflector molecules. In order to obtain neutrons with energy less than 5 meV, cryogenically cooled moderators 'cold neutron sources' should be used to slow down the neutrons. These cold moderators shift the neutron energy spectrum down because the thermal motion of moderator molecules as well as the up-scattering is very small, which provides large gains in intensity of low energy neutrons, E neutron source could provide the neutrons beams with lower energy, which could be utilized in scattering experiment and material structures analysis. This study describes the performed physics analyses to define and characterize the cold neutron source of the KIPT neutron source facility. The cold neutron source is designed to optimize the cold neutron brightness to the experimental instruments outside the radial heavy concrete shield of the facility. Liquid hydrogen or solid methane with 20 K temperature is used as a cold moderator. Monte Carlo computer code MCNPX [4], with ENDF/B-VI nuclear data libraries, is utilized to calculate the cold neutron source performance and estimate the nuclear heat load to the cold moderator. The surface source generation capability of MCNPX code has been used to provide the possibility of analyzing different design configurations and perform design optimization analyses with reasonable computer resources. Several design configurations were analyzed and their performance were characterized and optimized.

Zhong, Z.; Gohar, Y.; Kellogg, R.; Nuclear Engineering Division

2009-02-17T23:59:59.000Z

369

ARACOR Eagle-matched Operations and Neutron Detector Performance Tests  

SciTech Connect

A test campaign was undertaken during April 16-19 in LaHonda, California to match the operational performance of the Idaho National Engineering and Environmental Laboratory (INEEL)Varitron accelerator to that of an ARACOR Eagle accelerator. This Eagle-matched condition, with the INEEL Varitron, will be used during a concept demonstration test at Los Alamos National Laboratory (LANL). This operational characterization involved the use of similar electron beam energies, similar production of photoneutrons from selected non-nuclear materials, and similar production of photofissionbased, delayed neutrons from an INEEL-provided, depleted uranium sample. Then using the matched operation, the Varitron was used to define detector performances for several INEEL and LANL detectors using the depleted uranium target and Eagle-like, bremsstrahlung collimation. This summary report provides neutron measurements using the INEEL detectors. All delayed neutron data are acquired in the time interval ranging from 4.95 to 19.9 ms after each accelerator pulse. All prompt neutron data are acquired during 0.156 to 4.91 ms after each accelerator pulse. Prompt and delayed neutron counting acquisition intervals can still be optimized.

Jones, James Litton; Haskell, Kevin James; Hoggan, Jerry Matkin; Norman, Daren Reeve

2002-06-01T23:59:59.000Z

370

Neutronic Aspects and Recent Experimental Results with ...  

Science Conference Proceedings (OSTI)

... Neutronic Aspects and Recent Experimental Results with Methane Moderators at IUCF Low Energy Neutron Source (LENS). ...

371

Pulse shaping with transmission lines  

DOE Patents (OSTI)

A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

Wilcox, R.B.

1985-08-15T23:59:59.000Z

372

Pulse shaping with transmission lines  

DOE Patents (OSTI)

A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

Wilcox, Russell B. (Oakland, CA)

1987-01-01T23:59:59.000Z

373

Neutron Diffraction @ TOPAZ  

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

Topaz Guide Bender Topaz Guide Bender Neutron Diffraction @ TOPAZ Workshop on Single Crystal Neutron Diffraction picture 2 September 29 - October 1, 2011 * Spallation Neutron Source * Oak Ridge National Laboratory * Oak Ridge TN, USA TOPAZ 2011 Home Contacts Agenda and Important Deadlines Registration and Payment filler Workshop summary and purpose A workshop on single crystal neutron diffraction will be held at the Spallation Neutron Source at the Oak Ridge National Laboratory (ORNL). It will present invited and contributed talks to showcase cutting edge science and examples where neutron diffraction can make significant contributions; and provide training in neutron structure analysis and sample screening for the preparation of instrument beam-time proposals. TOPAZ is a high resolution wavelength-resolved Laue diffractometer with a versatile sample environment. Commissioning user experiments have demonstrated successfully the instrument capability for structural study of a vitamin B12 derivative, ion distribution in Li-ion battery materials, order and disorder in shape memory intermetallics, magnetic phase transition in multiferroic single crystal and functional thin films. The workshop is directed towards experienced neutron diffraction users and new users alike and encourages members to highlight their research and interest in structure analysis and investigation. The workshop will give opportunity to bring your own single crystal and screen sample quality and scattering power on TOPAZ @ room temperature, to evaluate data collection time and quality for an anticipated experiment. Finally, an opportunity to compose a proposal for neutron beam time (http://neutrons.ornl.gov/users/proposals.shtml) with staff will be provided in the framework of the workshop. The workshop format is well suited for researchers to contribute by showcasing their research and bring their research group or graduate student, who would like to test a single crystal sample. User access training for the ORNL neutron scattering facility will be included. It will be valid for future experiments.

374

NIST: NIF - Neutron Imaging Facility  

Science Conference Proceedings (OSTI)

... 1 above) is located at Beam Tube 2 (BT-2 ... Figure 2. Plan view of the neutron imaging facility ... still a significant amount of high energy neutrons and ...

375

Neutron and Nano User Meeting  

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

Home Science @ Neutron and Nano Facilities User Workshops Integrated Agendas Venue Travel Information Contacts and Sponsors Registration Talks Neutron and Nano User Meeting August...

376

Neutron and Nano User Meeting  

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

Science @ Neutron and Nano Facilities Science @ Neutron and Nano Facilities: Complementary Techniques Oak Ridge National Laboratory, Building 5200 Tuesday-Wednesday, August 13-14,...

377

News & Awards | Neutron Science | ORNL  

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

Awards Events and Conferences Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | News and Awards SHARE News and Awards 1-6 of 6 Results...

378

CO{sub 2} laser pulse shortening by laser ablation of a metal target  

Science Conference Proceedings (OSTI)

A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO{sub 2} laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to {approx}2 ns and to remove the low power, long duration tails that are present in TEA CO{sub 2} pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is {approx}10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.

Donnelly, T.; Mazoyer, M.; Lynch, A.; O'Sullivan, G.; O'Reilly, F.; Dunne, P.; Cummins, T. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2012-03-15T23:59:59.000Z

379

The mechanism of thin film Si nanomachining using femtosecond laser pulses  

E-Print Network (OSTI)

Femtosecond (fs) laser ablation has been the subject of intense recent research. The pulse time ('width') is shorter than the electronic relaxation time, resulting in a decoupling of the period of laser illumination and ...

Jia, Jimmy Yi-Jie, 1980-

2004-01-01T23:59:59.000Z

380

NSE: the Neutron Spin Echo Spectrometer at SNS | ORNL Neutron Sciences  

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

Spin Echo Spectrometer at SNS Spin Echo Spectrometer at SNS NSE NSE is funded and operated by the J√ľlich Centre for Neutron Science. The SNS NSE instrument provides ultrahigh resolution spectroscopy with a Fourier time range that covers ŌĄ = 1 ps to a nominal 350 ns with a high effective neutron flux, aiming to be the best of its class in both resolution and dynamic range (please refer to the instrument fact sheet for a detailed current status). Researchers use this instrument to investigate soft condensed matter and complex fluids applications in a variety of fields. The planned optional ferromagnetic and intensity-modulated modes will allow for detailed investigation of magnetic samples and phenomena. The design of the NSE spectrometer takes full advantage of recent progress in neutron optics and polarizing supermirror microbenders,1,2 resulting in

Note: This page contains sample records for the topic "intense pulsed neutron" 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

FAST NEUTRON REACTOR  

DOE Patents (OSTI)

A reactor comprising fissionable material in concentration sufficiently high so that the average neutron enengy within the reactor is at least 25,000 ev is described. A natural uranium blanket surrounds the reactor, and a moderating reflector surrounds the blanket. The blanket is thick enough to substantially eliminate flow of neutrons from the reflector.

Soodak, H.; Wigner, E.P.

1961-07-25T23:59:59.000Z

382

Design of a High-energy, Two-stage Pulsed Plasma Thruster T.E. Markusic  

E-Print Network (OSTI)

Canting in Pulsed Electromagnetic Accelerators. PhD thesis, Prince- ton University, 2002. [14] Y.C.F. Thio electromagnetic accelerators are devices which use intense bursts of electrical current (8@9BADCFEHGIADCFPDQ A, July 7-10, 2002. Copyright by authors. Published by the AIAA with permission. 1 Introduction Pulsed

Choueiri, Edgar

383

Industry - ORNL Neutron Sciences  

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

Industry and Neutron Science Industry and Neutron Science Industry and Neutron Science: Working To Make a Match "In fundamental research, we want to know everything. Industry wants to know enough to answer a question." Research Contact: Mike Crawford September 2011, Written by Deborah Counce Mike Crawford and Souleymane Diallo Mike Crawford of Dupont (right) and Souleymane Diallo, instrument scientist for the Backscattering Spectrometer at SNS, prepare a material sample for an experiment on the instrument. Industrial users are starting to eye the potential of neutron science for solving problems that can't be solved in any other way. At the same time, the SNS and HFIR neutron science facilities at ORNL are exploring ways to woo such users and to make a match of it, to the benefit of both.

384

Neutron Scattering Software  

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

Software Software A new portal for neutron scattering has just been established at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site. We will leave the current content here for archival purposes but no new content will be added. We encourage everyone interested in neutron scattering to take full advantage of this exciting new resource for our community. Neutronsources.org Data Formats NeXus: Neutron and X-ray Data Format Crystallographic Binary Format (CBF/imgCIF) Hierarchical Data Format (HDF) Data Analysis and Visualization Data Analysis for Neutron Scattering Experiments (DANSE): distributed data analysis project Large Array Manipulation Program (LAMP): IDL-based data analysis and visualization

385

Pocked surface neutron detector  

DOE Patents (OSTI)

The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

2003-04-08T23:59:59.000Z

386

AGS RESONANT EXTRACTION WITH HIGH INTENSITY BEAMS.  

SciTech Connect

The Brookhaven AGS third integer resonant extraction system allows the AGS to provide high quality, high intensity 25.5 GeV/c proton beams simultaneously to four target stations and as many as 8 experiments. With the increasing intensities (over 7 x 10{sup 13} protons/pulse) and associated longer spill periods (2.4 to 3 seconds long), we continue to run with low losses and high quality low modulation continuous current beams.[1] Learning to extract and transport these higher intensity beams has required a process of careful modeling and experimentation. We have had to learn how to correct for various instabilities and how to better match extraction and the transport lines to the higher emittance beams being accelerated in the AGS. Techniques employed include ''RF'' methods to smooth out momentum distributions and fine structure. We will present results of detailed multi-particle tracking modeling studies which enabled us to develop a clear understanding of beam loss mechanisms in the transport and extraction process. We will report on our status, experiences, and the present understanding of the intensity limitations imposed by resonant extraction and transport to fixed target stations.

AHRENS,L.; BROWN,K.; GLENN,J.W.; ROSER,T.; TSOUPAS,N.; VANASSELT,W.

1999-03-29T23:59:59.000Z

387

Neutron Resonance Radiography for Explosives Detection: Technical Challenges  

DOE Green Energy (OSTI)

Fast Neutron Resonance Radiography (NRR) has recently become a focus of investigation as a supplement to conventional x-ray systems as a non-invasive, non-destructive means of detecting explosive material concealed in checked luggage or cargo containers at airports. Using fast (1-6 MeV) neutrons produced by the D(d,n){sup 3}He reaction, NRR provides both an imaging capability and the ability to determine the chemical composition of materials in baggage or cargo. Elemental discrimination is achieved by exploiting the resonance features of the neutron cross-section for oxygen, nitrogen, carbon, and hydrogen. Simulations have shown the effectiveness of multiple-element NRR through Monte Carlo transport methods; this work is focused on the development of a prototype system that will incorporate an accelerator-based neutron source and a neutron detection and imaging system to demonstrate the realistic capabilities of NRR in distinguishing the elemental components of concealed objects. Preliminary experiments have exposed significant technical difficulties unapparent in simulations, including the presence of image contamination from gamma ray production, the detection of low-fluence fast neutrons in a gamma field, and the mechanical difficulties inherent in the use of thin foil windows for gas cell confinement. To mitigate these concerns, a new gas target has been developed to simultaneously reduce gamma ray production and increase structural integrity in high flux gas targets. Development of a neutron imaging system and neutron counting based on characteristic neutron pulse shapes have been investigated as a means of improving signal to noise ratios, reducing irradiation times, and increasing the accuracy of elemental determination.

Raas, W L; Blackburn, B; Boyd, E; Hall, J M; Kohse, G; Lanza, R; Rusnak, B; Watterson, J W

2005-11-09T23:59:59.000Z

388

Le Bail Intensity Extraction  

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

Le Bail Intensity Extraction Le Bail Intensity Extraction Presentation Goal Introduce the concepts behind LeBail fitting; why it is useful and how to perform a Le Bail fit with GSAS. Format: PDF slides or a RealPlayer video of the slides with accompanying audio and a demo video that shows how a Le Bail fit is performed. Presentation Outline What is the Le Bail method? Other approaches Why use the Le Bail method? Parameter fitting with Le Bail intensity extraction Le Bail refinement strategies Avoiding problems with background fitting: BKGEDIT Demo: an example Le Bail fit Links Le Bail lecture Slides (as PDF file) FlashMovie presentation with index (best viewed with 1024x768 or better screen resolution) FlashMovie file (800x600 pixels) Le Bail demo FlashMovie presentation with index (best viewed with 1024x768 or

389

Pulse power linac  

DOE Patents (OSTI)

A linear acceleration for charged particles is constructed of a plurality of transmission line sections that extend between a power injection region and an accelerating region. Each line section is constructed of spaced plate-like conductors and is coupled to an accelerating gap located at the accelerating region. Each gap is formed between a pair of apertured electrodes, with all of the electrode apertures being aligned along a particle accelerating path. The accelerating gaps are arranged in series, and at the injection region the line sections are connected in parallel. At the injection region a power pulse is applied simultaneously to all line sections. The line sections are graduated in length so that the pulse reaches the gaps in a coordinated sequence whereby pulse energy is applied to particles as they reach each of the gaps along the accelerating path.

Villa, Francesco (Alameda, CA)

1990-01-01T23:59:59.000Z

390

Pulse shaping system  

DOE Patents (OSTI)

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

Skeldon, M.D.; Letzring, S.A.

1999-03-23T23:59:59.000Z

391

Pulse shaping system  

DOE Patents (OSTI)

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Skeldon, Mark D. (Penfield, NY); Letzring, Samuel A. (Jemez Springs, NM)

1999-03-23T23:59:59.000Z

392

Physics of solar neutron production: Questionable detection of neutrons  

E-Print Network (OSTI)

) A short introduction is given to astrophysics of neutron stars and to physics of dense matter in neutron stars. Observed properties of astro- physical objects containing neutron stars are discussed. Current scenarios regarding formation and evolution of neutron stars in those objects are presented. Physical

Share, Gerald

393

High intensity hadron accelerators  

SciTech Connect

This rapporteur report consists mainly of two parts. Part I is an abridged review of the status of all High Intensity Hadron Accelerator projects in the world in semi-tabulated form for quick reference and comparison. Part II is a brief discussion of the salient features of the different technologies involved. The discussion is based mainly on my personal experiences and opinions, tempered, I hope, by the discussions I participated in in the various parallel sessions of the workshop. In addition, appended at the end is my evaluation and expression of the merits of high intensity hadron accelerators as research facilities for nuclear and particle physics.

Teng, L.C.

1989-05-01T23:59:59.000Z

394

Ultrahigh-intensity laser: physics of the extreme on a tabletop  

SciTech Connect

This paper reviews the development of ultrahigh-intensity laser technology from the early 1960`s to the present, explaining the obstacles to each increase in intensity and the technical means used to overcome them. These included the shortening of pulses, mode locking, and chirped pulse amplification (CPA). The particular technical advances that make CPA possible included the invention of matched pulse stretchers and compressors and the development of ultrabroadband gain media. The paper then discusses the generation of ultrashort pulses and their characteristics. It then moves on to the Petawatt laser, which incorporates the CPA technology. It then addresses the question of whether it is possible to forecast the ultimate peak power that can be achieved by a laser system of a given size. Applications of ultrahigh-intensity lasers in different physical regimes are discussed.

Mourou, G.A.; Barty, C.P.; Perry, M.D.

1997-10-10T23:59:59.000Z

395

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.  

SciTech Connect

An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

2007-12-01T23:59:59.000Z

396

Energy Intensity Strategy  

E-Print Network (OSTI)

Our presentation will cover how we began the journey of conserving energy at our facility. Weíll discuss a basic layout of our energy intensity plan and the impact our team has had on the process, what tools weíre using, what goals have been identified, how we structured the plan to include our team in the process and so on.

Rappolee, D.

2008-01-01T23:59:59.000Z

397

Neutron detectors for fusion reaction-rate measurements  

SciTech Connect

Fusion reactions in an inertial-confinement fusion (ICF) target filled with deuterium or a deuterium/tritium fuel release nearly monoenergetic neutrons. Because most the neutrons leave the compressed target without collision, they preserve reaction-rate information as they travel radially outward from their point of origin. Three fast, neutron detector techniques, each capable of measuring the fusion reaction-rate of ICF targets, have been demonstrated. The most advanced detector is based on the fast rise-time of a commercial plastic scintillator material (BC-422) which acts as a neutron-to-light converter. Signals, which are recorded with a fast optical streak camera, have a resolution of 25 ps. Good signals can be recorded for targets producing only 5 x 10{sup 7} DT neutrons. Two other detectors use knock-on collisions between neutrons and protons in a thin polyethylene (CH{sub 2}) converter. In one, the converter is placed in front of the photocathode of an x-ray streak camera. Recoil protons pass through the photocathode and knock out electrons which are accelerated and deflected to produce a signal. Resolutions < 25 ps are possible. In the other, the converter is placed in front of a microchannel plate (MCP) with a gated microstrip. Recoil protons eject electrons from the gold layer forming the microstrip. If a gate pulse is present, the signal is amplified. Present gate times are about 80 ps.

Lerche, R.A.; Phillion, D.W.; Landen, O.L.; Murphy, T.J. [Lawrence Livermore National Lab., CA (United States); Jaanimagi, P.A. [Univ. of Rochester, NY (United States). Laboratory for Laser Energetics

1994-02-10T23:59:59.000Z

398

A New Method of Prompt Fission Neutron Energy Spectrum Unfolding  

Science Conference Proceedings (OSTI)

The prompt neutron emission in spontaneous fission of {sup 252}Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the {sup 252}Cf(sf) reaction is one of the main references for nuclear data, on the other hand the understanding of PFN emission mechanism is very important for nuclear fission theory. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 10{sup 7} fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

Zeynalova, O. V. [Moscow State Institute of Radioengineering, Electronics and Automation, Moscow (Russian Federation); Joint Institute for Nuclear Research, Dubna (Russian Federation); Zeynalov, Sh. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Hambsch, F.-J.; Oberstedt, S. [EC-JRC-Institute for Reference Materials and Measurements, Geel (Belgium)

2010-11-25T23:59:59.000Z

399

Sandia National Laboratories: Z Pulsed Power Facility: About Z  

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

About Z About Z Picture of Z Machine Sandia's Z machine is Earth's most powerful pulsed-power facility and X-ray generator. Z compresses energy in time and space to achieve extreme powers and intensities, found nowhere else on Earth. In approximately 200 shots Z fires every year, the machine uses currents of about 26 million amps to reach peak X-ray emissions of 350 terawatts and an X-ray output of 2.7 megajoules. The Z machine is located in Albuquerque, N.M., and is part of Sandia's Pulsed Power Program, which began in the 1960s. Pulsed power is a technology that concentrates electrical energy and turns it into short pulses of enormous power, which are then used to generate X-rays and gamma rays. Produced in the laboratory, this controlled radiation creates conditions similar to those caused by the detonation of nuclear weapons,

400

Passive and active pulse stacking scheme for pulse shaping  

DOE Patents (OSTI)

Apparatus and method for producing a sequence of radiation pulses with a pulse envelope of time variation which is controllable by an external electromagnetic signal applied to an active medium or by a sectored reflector, through which the radiation passes.

Harney, Robert C. (Livermore, CA); Schipper, John F. (Palo Alto, CA)

1977-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "intense pulsed neutron" 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

Optical penetration sensor for pulsed laser welding  

SciTech Connect

An apparatus and method for determining the penetration of the weld pool created from pulsed laser welding and more particularly to an apparatus and method of utilizing an optical technique to monitor the weld vaporization plume velocity to determine the depth of penetration. A light source directs a beam through a vaporization plume above a weld pool, wherein the plume changes the intensity of the beam, allowing determination of the velocity of the plume. From the velocity of the plume, the depth of the weld is determined.

Essien, Marcelino (Albuquerque, NM); Keicher, David M. (Albuquerque, NM); Schlienger, M. Eric (Albuquerque, NM); Jellison, James L. (Albuquerque, NM)

2000-01-01T23:59:59.000Z

402

Hypernuclear Physics for Neutron Stars  

E-Print Network (OSTI)

The role of hypernuclear physics for the physics of neutron stars is delineated. Hypernuclear potentials in dense matter control the hyperon composition of dense neutron star matter. The three-body interactions of nucleons and hyperons determine the stiffness of the neutron star equation of state and thereby the maximum neutron star mass. Two-body hyperon-nucleon and hyperon-hyperon interactions give rise to hyperon pairing which exponentially suppresses cooling of neutron stars via the direct hyperon URCA processes. Non-mesonic weak reactions with hyperons in dense neutron star matter govern the gravitational wave emissions due to the r-mode instability of rotating neutron stars.

Jurgen Schaffner-Bielich

2008-01-24T23:59:59.000Z

403

FABRICATION OF NEUTRON SOURCES  

DOE Patents (OSTI)

A method is presented for preparing a neutron source from polonium-210 and substances, such as beryllium and boron, characterized by emission of neutrons upon exposure to alpha particles from the polonium. According to the invention, a source is prepared by placing powdered beryllium and a platinum foil electroplated with polonium-2;.0 in a beryllium container. The container is sealed and then heated by induction to a temperature of 450 to 1100 deg C to volatilize the polonium off the foil into the powder. The heating step is terminated upon detection of a maximum in the neutron flux level.

Birden, J.H.

1959-04-21T23:59:59.000Z

404

Switchable radioactive neutron source device  

DOE Patents (OSTI)

This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned with the neutron portion of the second plate to produce neutrons and brought out of alignment to cease production of neutrons. 3 figs.

Stanford, G.S.; Rhodes, E.A.; Devolpi, A.; Boyar, R.E.

1987-11-06T23:59:59.000Z

405

Delayed neutrons from the neutron irradiation of ≤≥?U  

E-Print Network (OSTI)

A series of experiments was performed with the Texas A&M University Nuclear Science Center Reactor (NSCR) to verify ≤≥?U delayed neutron emission rates. A custom device was created to accurately measure a sample's pneumatic flight time and the Nuclear Science Center's (NSC's) pneumatic transfer system (PTS) was redesigned to reduce a sample's pneumatic flight time from over 1,600 milliseconds to less than 450 milliseconds. Four saturation irradiations were performed at reactor powers of 100 and 200 kW for 300 seconds and one burst irradiation was performed using a $1.61 pulse producing 19.11 MW-s of energy. Experimental results agreed extremely well with those of Keepin. By comparing the first ten seconds of collected data, the first saturation irradiation deviated ~1.869% with a dead time of 2 microseconds, while the burst irradiation deviated ~0.303% with a dead time of 5 microseconds. Saturation irradiations one, three and four were normalized to the initial count rate of saturation irradiation two to determine the system reproducibility, and deviated ~0.449%, ~0.343% and ~0.389%, respectively.

Heinrich, Aaron David

2008-05-01T23:59:59.000Z

406

Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement  

Science Conference Proceedings (OSTI)

We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstration of particle beam profile diagnostics using fiber optic laser pulse transmission line.

Liu, Yun [ORNL; Huang, Chunning [ORNL; Aleksandrov, Alexander V [ORNL

2013-01-01T23:59:59.000Z

407

Unlocking energy intensive habits  

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

energy intensive habits energy intensive habits Presentation at LBL Oct 10, 2013 by Hal Wilhite Professor and Research Director University of Oslo Centre for Development and the Environment Source: WWF US EIA Outlook 2011 Conventional framing of the energy consumption and savings * Sovereign consumers * Economically rational and persistentely reflexive. * Uninfluenced by social and material conditions of everyday life * Focus on efficiency and not on size and volume which is for the most part treated as an indifferent variable Cognitive reductionism The change of frame * From individual to socio-material * From rational/reflexive experience-based (practical) knowledge * From efficiency to reduction A theory of habit * Acknowledges the role of lived experience (history, both cultural and personal) in forming

408

Industry - ORNL Neutron Sciences  

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

PartTec PartTec ORNL, PartTec Inc. Licensing Agreement ORNL and PartTec sign licensing agreement (Front) ORNL Deputy Director for Science & Technology Thomas Zacharia and PartTec CEO Herschel Workman. (Back) Bruce Hannan (SNS), PartTec production manager Craig Kline, Rick Riedel (SNS), Jason Hodges (SNS) and Ron Cooper (SNS). The SNS guys were on the development team. Representatives from Oak Ridge National Laboratory and PartTec, an Indiana-based firm, formally signed a licensing agreement Thursday, Aug. 12, to market an advanced neutron detector system developed for the Spallation Neutron Source. The Shifting Scintillator Neutron Detector can determine the time and position of captured neutrons, which enables researchers to obtain very accurate time-of-flight measurements.

409

Education | ORNL Neutron Sciences  

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

Education banner Education banner Sunil Sinha A Chat with Sunil Sinha, Distinguished Professor of Physics at the University of California-San Diego and speaker at the recent CNMS-SNS Research Forum more... The purpose of the Spallation Neutron Source and the High Flux Isotope Reactor is to facilitate neutron scattering as an integral tool for scientific research and technological development across many scientific and engineering domains within the scientific, academic,and industrial communities. Coupled with this role is a recognized need to inspire, educate, and facilitate the next generation of users and hence foster enhanced use of the unique neutron scattering facilities at ORNL. This is the central theme of the education activities within the Neutron Sciences Directorate (NScD).

410

ORNL Neutron Sciences Instruments  

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

Instruments banner Instruments banner ORNL Neutron Sciences Instruments SNS and HFIR provide researchers with two complementary world-class suites of neutron scattering instruments and beam lines. All the instruments are supported by a variety of sample environments and data analysis and visualization capabilities. Before submitting a proposal for a specific instrument, please contact the appropriate instrument scientist to make sure your research is feasible for that instrument. Instruments Currently Available to Users SNS Beam Line Instrument Name HFIR Beam Line Instrument Name 1B NOMAD Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS Backscattering Spectrometer CG-1D IMAGING Neutron Imaging Prototype Facility 3 SNAP Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS

411

Awards | Neutron Science | ORNL  

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

| Neutron Science | News and Awards | Awards SHARE Awards for Excellence 1-2 of 2 Results ORNL team wins R&D 100 award for wavelength-shifting scintillator detector January...

412

Personnel neutron dosimetry  

Science Conference Proceedings (OSTI)

This edited transcript of a presentation on personnel neutron discusses the accuracy of present dosimetry practices, requirements, calibration, dosemeter types, quality factors, operational problems, and dosimetry for a criticality accident. 32 figs. (ACR)

Hankins, D.

1982-04-01T23:59:59.000Z

413

Neutron personnel dosimetry  

Science Conference Proceedings (OSTI)

The current state-of-the-art in neutron personnel dosimetry is reviewed. Topics covered include dosimetry needs and alternatives, current dosimetry approaches, personnel monitoring devices, calibration strategies, and future developments. (ACR)

Griffith, R.V.

1981-06-16T23:59:59.000Z

414

Neutron Scattering Science User ...  

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

Proposals for beam time at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) and Spallation Neutron Source (SNS) will be accepted via the web-based proposal system...

415

ORNL Neutron Sciences Users  

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

SHUG banner SNS-HFIR User Group The SNS-HFIR User Group (SHUG) consists of all persons interested in using the neutron scattering facilities at Oak Ridge. It provides input to the...

416

Determination of the Axial-Vector Weak Coupling Constant with Polarized Ultracold Neutrons  

E-Print Network (OSTI)

A precise measurement of the neutron decay $\\beta$-asymmetry $A_0$ has been carried out using polarized ultracold neutrons (UCN) from the pulsed spallation UCN source at the Los Alamos Neutron Science Center (LANSCE). Combining data obtained in 2008 and 2009, we report $A_0 = -0.11966 \\pm 0.00089 _{-0.00140}^{+0.00123}$, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon $g_A/g_V = -1.27590 _{-0.00445}^{+0.00409}$.

Liu, J; Holley, A T; Back, H O; Bowles, T J; Broussard, L J; Carr, R; Clayton, S; Currie, S; Filippone, B W; Garcia, A; Geltenbort, P; Hickerson, K P; Hoagland, J; Hogan, G E; Hona, B; Ito, T M; Liu, C -Y; Makela, M; Mammei, R R; Martin, J W; Melconian, D; Morris, C L; Pattie, R W; Galvan, A Perez; Pitt, M L; Plaster, B; Ramsey, J C; Rios, R; Russell, R; Saunders, A; Seestrom, S; Sondheim, W E; Tatar, E; Vogelaar, R B; VornDick, B; Wrede, C; Yan, H; Young, A R

2010-01-01T23:59:59.000Z

417

Determination of the Axial-Vector Weak Coupling Constant with Ultracold Neutrons  

E-Print Network (OSTI)

A precise measurement of the neutron decay $\\beta$-asymmetry $A_0$ has been carried out using polarized ultracold neutrons (UCN) from the pulsed spallation UCN source at the Los Alamos Neutron Science Center (LANSCE). Combining data obtained in 2008 and 2009, we report $A_0 = -0.11966 \\pm 0.00089_{-0.00140}^{+0.00123}$, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon $g_A/g_V = -1.27590_{-0.00445}^{+0.00409}$.

UCNA Collaboration; J. Liu; M. P. Mendenhall; A. T. Holley; H. O. Back; T. J. Bowles; L. J. Broussard; R. Carr; S. Clayton; S. Currie; B. W. Filippone; A. Garcia; P. Geltenbort; K. P. Hickerson; J. Hoagland; G. E. Hogan; B. Hona; T. M. Ito; C. -Y. Liu; M. Makela; R. R. Mammei; J. W. Martin; D. Melconian; C. L. Morris; R. W. Pattie Jr.; A. Perez Galvan; M. L. Pitt; B. Plaster; J. C. Ramsey; R. Rios; R. Russell; A. Saunders; S. J. Seestrom; W. E. Sondheim; E. Tatar; R. B. Vogelaar; B. VornDick; C. Wrede; H. Yan; A. R. Young

2010-07-22T23:59:59.000Z

418

Science Education Programs | Neutron Science | ORNL  

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

What are Neutrons Why Research with Neutrons Graduate & Post-doctoral Programs Student & Teacher Programs Science Forum Neutron Scattering Tutorials Kids' Corner News and Awards...

419

ORNL Neutron Sciences Directorate Executive Office  

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

Neutron Sciences Directorate Executive Office Kelly Beierschmitt ORNL Associate Laboratory Director for Neutron Sciences Kelly Beierschmitt. The Neutron Sciences Directorate (NScD)...

420

Clifford G. Shull, Neutron Diffraction, Hydrogen Atoms, and Neutron  

Office of Scientific and Technical Information (OSTI)

Clifford Shull, Neutron Diffraction, and Neutron Scattering Clifford Shull, Neutron Diffraction, and Neutron Scattering Resources with Additional Information Clifford G. Shull was awarded the 1994 Nobel Prize in Physics "for the development of the neutron diffraction technique". 'Professor Shull's prize was awarded for his pioneering work in neutron scattering, a technique that reveals where atoms are within a material like ricocheting bullets reveal where obstacles are in the dark. Clifford Shull Photo Courtesy of Oak Ridge National Laboratory When a beam of neutrons is directed at a given material, the neutrons bounce off, or are scattered by, atoms in the sample being investigated. The neutrons' directions change, depending on the location of the atoms they hit, and a diffraction pattern of the atoms' positions can then be obtained.

Note: This page contains sample records for the topic "intense pulsed neutron" 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.
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to obtain the most current and comprehensive results.


421

FABRICATION OF NEUTRON SOURCES  

DOE Patents (OSTI)

A method is presented for preparing a more efficient neutron source comprising inserting in a container a quantity of Po-210, inserting B powder coated with either Ag, Pt, or Ni. The container is sealed and then slowly heated to about 450 C to volatilize the Po and effect combination of the coated powder with the Po. The neutron flux emitted by the unit is moritored and the heating step is terminated when the flux reaches a maximum or selected level.

Birden, J.H.

1959-01-20T23:59:59.000Z

422

Polarized neutrons in RHIC  

Science Conference Proceedings (OSTI)

There does not appear to be any obvious way to accelerate neutrons, polarized or otherwise, to high energies by themselves. To investigate the behavior of polarized neutrons the authors therefore have to obtain them by accelerating them as components of heavier nuclei, and then sorting out the contribution of the neutrons in the analysis of the reactions produced by the heavy ion beams. The best neutron carriers for this purpose are probably {sup 3}He nuclei and deuterons. A polarized deuteron is primarily a combination of a proton and a neutron with their spins pointing in the same direction; in the {sup 3}He nucleus the spins of the two protons are opposite and the net spin (and magnetic moment) is almost the same as that of a free neutron. Polarized ions other than protons may be accelerated, stored and collided in a ring such as RHIC provided the techniques proposed for polarized proton operation can be adapted (or replaced by other strategies) for these ions. This paper discusses techniques for accelerating polarized {sup 3}He nuclei and deuterons.

Courant, E.D.

1998-04-20T23:59:59.000Z

423

Nonlinear pulse propagation and phase velocity of laser-driven plasma waves  

Science Conference Proceedings (OSTI)

Laser evolution and plasma wave excitation by a relativistically-intense short-pulse laser in underdense plasma are investigated in the broad pulse limit, including the effects of pulse steepening, frequency red-shifting, and energy depletion. The nonlinear plasma wave phase velocity is shown to be significantly lower than the laser group velocity and further decreases as the pulse propagates owing to laser evolution. This lowers the thresholds for trapping and wavebreaking, and reduces the energy gain and efficiency of laser-plasma accelerators that use a uniform plasma profile.

Schroeder, Carl B.; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

2011-03-25T23:59:59.000Z

424

Pulsed gas laser  

DOE Patents (OSTI)

A pulsed gas laser is constituted by Blumlein circuits wherein space metal plates function both as capacitors and transmission lines coupling high frequency oscillations to a gas filled laser tube. The tube itself is formed by spaced metal side walls which function as connections to the electrodes to provide for a high frequency, high voltage discharge in the tube to cause the gas to lase. Also shown is a spark gap switch having structural features permitting a long life.

Anderson, Louis W. (Madison, WI); Fitzsimmons, William A. (Madison, WI)

1978-01-01T23:59:59.000Z

425

Downhole pulse radar  

DOE Patents (OSTI)

A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

Chang, Hsi-Tien

1987-09-28T23:59:59.000Z

426

Downhole pulse radar  

DOE Patents (OSTI)

A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

Chang, Hsi-Tien (Albuquerque, NM)

1989-01-01T23:59:59.000Z

427

MULTICHANNEL PULSE-HEIGHT ANALYZER  

DOE Patents (OSTI)

This patent deals with electronic computing circuits and more particularly to pulse-height analyzers used for classifying variable amplitude pulses into groups of different amplitudes. The device accomplishes this pulse allocation by by converting the pulses into frequencies corresponding to the amplitudes of the pulses, which frequencies are filtered in channels individually pretuned to a particular frequency and then detected and recorded in the responsive channel. This circuit substantially overcomes the disadvantages of prior annlyzers incorporating discriminators pre-set to respond to certain voltage levels, since small variation in component values is not as critical to satisfactory circuit operation.

Russell, J.T.; Lefevre, H.W.

1958-01-21T23:59:59.000Z

428

Laser stand for irradiation of targets by laser pulses from the Iskra-5 facility at a repetition rate of 100 MHz  

SciTech Connect

A train of a few tens of high-power subnanosecond laser pulses with a repetition period of 10 ns is generated in the Iskra-5 facility. The laser pulse train has an energy of up to 300 J and contains up to 40 pulses (by the 0.15 intensity level), the single pulse duration in the train being {approx}0.5 ns. The results of experiments on conversion of a train of laser pulses to a train of X-ray pulses are presented. Upon irradiation of a tungsten target, a train of X-ray pulses is generated with the shape of an envelope in the spectral band from 0.18 to 0.28 keV similar to that of the envelope of the laser pulse train. The duration of a single X-ray pulse in the train is equal to that of a single laser pulse. (lasers)

Annenkov, V I; Garanin, Sergey G; Eroshenko, V A; Zhidkov, N V; Zubkov, A V; Kalipanov, S V; Kalmykov, N A; Kovalenko, V P; Krotov, V A; Lapin, S G; Martynenko, S P; Pankratov, V I; Faizullin, V S; Khrustalev, V A; Khudikov, N M; Chebotar, V S [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod Region (Russian Federation)

2009-08-31T23:59:59.000Z

429

Scaling to Ultra-High Intensities by High-Energy Petawatt Beam Combining  

SciTech Connect

The output pulse energy from a single-aperture high-energy laser amplifier (e.g. fusion lasers such as NIF and LMJ) are critically limited by a number of factors including optical damage, which places an upper bound on the operating fluence; parasitic gain, which limits together with manufacturing costs the maximum aperture size to {approx} 40-cm; and non-linear phase effects which limits the peak intensity. For 20-ns narrow band pulses down to transform-limited sub-picosecond pulses, these limiters combine to yield 10-kJ to 1-kJ maximum pulse energies with up to petawatt peak power. For example, the Advanced Radiographic Capability (ARC) project at NIF is designed to provide kilo-Joule pulses from 0.75-ps to 50-ps, with peak focused intensity above 10{sup 19} W/cm{sup 2}. Using such a high-energy petawatt (HEPW) beamline as a modular unit, they discuss large-scale architectures for coherently combining multiple HEPW pulses from independent apertures, called CAPE (Coherent Addition of Pulses for Energy), to significantly increase the peak achievable focused intensity. Importantly, the maximum intensity achievable with CAPE increases non-linearly. Clearly, the total integrated energy grows linearly with the number of apertures N used. However, as CAPE combines beams in the focal plane by increasing the angular convergence to focus (i.e. the f-number decreases), the foal spot diameter scales inversely with N. Hence the peak intensity scales as N{sup 2}. Using design estimates for the focal spot size and output pulse energy (limited by damage fluence on the final compressor gratings) versus compressed pulse duration in the ARC system, Figure 2 shows the scaled focal spot intensity and total energy for various CAPE configurations from 1,2,4, ..., up to 192 total beams. They see from the fixture that the peak intensity for event modest 8 to 16 beam combinations reaches the 10{sup 21} to 10{sup 22} W/cm{sup 2} regime. With greater number of apertures, or with improvements to the focusability of the individual beams, the maximum peak intensity can be increased further to {approx} 10{sup 24} W/cm{sup 2}. Lastly, an important feature of the CAPE architecture is the ability to coherently combine beams to produce complex spatio-temporal intensity distributions for laser-based accelerators (e.g. all-optical electron injection and acceleration) and high energy density science applications such as fast ignition.

Siders, C W; Jovanovic, I; Crane, J; Rushford, M; Lucianetti, A; Barty, C J

2006-06-23T23:59:59.000Z

430

Thermal-neutron capture for A=36-44  

SciTech Connect

The prompt gamma-ray data of thermal- neutron captures fornuclear mass number A=26-35 had been evaluated and published in "ATOMICDATA AND NUCLEAR DATA TABLES, 26, 511 (1981)". Since that time the manyexperimental data of the thermal-neutron captures have been measured andpublished. The update of the evaluated prompt gamma-ray data is verynecessary for use in PGAA of high-resolution analytical prompt gamma-rayspectroscopy. Besides, the evaluation is also very needed in theEvaluated Nuclear Structure Data File, ENSDF, because there are no promptgamma-ray data in ENSDF. The levels, prompt gamma-rays and decay schemesof thermal-neutron captures fornuclides (26Mg, 27Al, 28Si, 29Si, 30Si,31P, 32S, 33S, 34S, and 35Cl) with nuclear mass number A=26-35 have beenevaluated on the basis of all experimental data. The normalizationfactors, from which absolute prompt gamma-ray intensity can be obtained,and necessary comments are given in the text. The ENSDF format has beenadopted in this evaluation. The physical check (intensity balance andenergy balance) of evaluated thermal-neutron capture data has been done.The evaluated data have been put into Evaluated Nuclear Structure DataFile, ENSDF. This evaluation may be considered as an update of the promptgamma-ray from thermal-neutron capture data tables as published in"ATOMIC DATA AND NUCLEAR DATA TABLES, 26, 511 (1981)".

Chunmei, Z.; Firestone, R.B.

2003-01-01T23:59:59.000Z

431

Petawatt pulsed-power accelerator  

DOE Patents (OSTI)

A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

Stygar, William A. (Albuquerque, NM); Cuneo, Michael E. (Albuquerque, NM); Headley, Daniel I. (Albuquerque, NM); Ives, Harry C. (Albuquerque, NM); Ives, legal representative; Berry Cottrell (Albuquerque, NM); Leeper, Ramon J. (Albuquerque, NM); Mazarakis, Michael G. (Albuquerque, NM); Olson, Craig L. (Albuquerque, NM); Porter, John L. (Sandia Park, NM); Wagoner; Tim C. (Albuquerque, NM)

2010-03-16T23:59:59.000Z

432

Plans for an Integrated Front-End Test Stand at the Spallation Neutron Source  

SciTech Connect

A spare Radio-Frequency Quadrupole (RFQ) is presently being fabricated by industry with delivery to Oak Ridge National Laboratory planned in late 2012. The establishment of a test stand at the Spallation Neutron Source site is underway so that complete acceptance testing can be performed during the winter of 2012-2013. This activity is the first step in the establishment of an integrated front-end test stand that will include an ion source, low-energy beam transport (LEBT), RFQ, medium-energy beam transport, diagnostics, and a beam dump. The test stand will be capable of delivering an H- ion beam of up to 50 mA with a pulse length of 1 ms and a repetition rate of 60 Hz or a proton beam of up to 50 mA, 100us, 1Hz. The test stand will enable the following activities: complete ion source characterization; development of a magnetic LEBT chopper; development of a two-source layout; development of beam diagnostics; and study of beam dynamics of high intensity beam.

Champion, Mark S [ORNL; Aleksandrov, Alexander V [ORNL; Crofford, Mark T [ORNL; Heidenreich, Dale A [ORNL; Kang, Yoon W [ORNL; Moss, John [ORNL; Roseberry, Jr., R Tom [ORNL; Schubert, James Phillip [ORNL

2012-01-01T23:59:59.000Z

433

Effect of pulse profile and chirp on a laser wakefield generation  

SciTech Connect

A laser wakefield driven by an asymmetric laser pulse with/without chirp is investigated analytically and through two-dimensional particle-in-cell simulations. For a laser pulse with an appropriate pulse length compared with the plasma wavelength, the wakefield amplitude can be enhanced by using an asymmetric un-chirped laser pulse with a fast rise time; however, the growth is small. On the other hand, the wakefield can be greatly enhanced for both positively chirped laser pulse having a fast rise time and negatively chirped laser pulse having a slow rise time. Simulations show that at the early laser-plasma interaction stage, due to the influence of the fast rise time the wakefield driven by the positively chirped laser pulse is more intense than that driven by the negatively chirped laser pulse, which is in good agreement with analytical results. At a later time, since the laser pulse with positive chirp exhibits opposite evolution to the one with negative chirp when propagating in plasma, the wakefield in the latter case grows more intensely. These effects should be useful in laser wakefield acceleration experiments operating at low plasma densities.

Zhang Xiaomei; Shen Baifei; Ji Liangliang; Wang Wenpeng; Xu Jiancai; Yu Yahong; Yi Longqing; Wang Xiaofeng [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Hafz, Nasr A. M. [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Kulagin, V. [Sternberg Astronomical Institute of Moscow State University, Moscow 119992 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region, 141700 (Russian Federation)

2012-05-15T23:59:59.000Z

434

Synchronization of sub-picosecond electron and laser pulses  

SciTech Connect

Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail. (AIP) {copyright} {ital 1999 American Institute of Physics.}

Rosenzweig, J.B. [UCLA Department of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, California 90095 (United States); Le Sage, G.P. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

1999-07-01T23:59:59.000Z

435

Synchronization of sub-picosecond electron and laser pulses  

SciTech Connect

Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail.

Rosenzweig, J. B.; Le Sage, G. P. [UCLA Department of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, California 90095 (United States); Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

1999-07-12T23:59:59.000Z

436

High-speed pulse-shape generator, pulse multiplexer  

DOE Patents (OSTI)

The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

Burkhart, Scott C. (Livermore, CA)

2002-01-01T23:59:59.000Z

437

Neutron lifetime measurements using gravitationally trapped ultracold neutrons  

E-Print Network (OSTI)

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.

A. P. Serebrov; V. E. Varlamov; A. G. Kharitonov; A. K. Fomin; Yu. N. Pokotilovski; P. Geltenbort; I. A. Krasnoschekova; M. S. Lasakov; R. R. Taldaev; A. V. Vassiljev; O. M. Zherebtsov

2007-02-06T23:59:59.000Z

438

GALLIUM ARSENIDE SEMICONDUCTOR-BASED NEUTRON DETECTOR  

NEUTRON DETECTOR BENEFITS Portable, ... High Flux Isotope Reactor and Spallation Neutron Source. Several Homeland Security. LINKS TO ONLINE ...

439

Portable Neutron Sensors for Emergency Response Operations  

Science Conference Proceedings (OSTI)

This slide-show presents neutron measurement work, including design, use and performance of different neutron detection systems.

Mukhopadhyay, S., Maurer, R., Detweiler, R.

2012-06-22T23:59:59.000Z

440

The System of Nanosecond 280-KeV He+ Pulsed Beam  

SciTech Connect

At Fast Neutron Research Facility, the 150 kV-pulses neutron generator is being upgraded to a 280-kV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45{sup o}-double focusing dipole magnet and quadrupole lens. The multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 {micro}A with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between chopper and buncher have been included in the optimization of the bunch length.

Junphong, P.; Ano, V.; Lekprasert, B.; Suwannakachorn, D.; Thongnopparat, N.; Vilaithong, T.; /Chiang Mai U.; Wiedemann, H.; /SLAC /SLAC, SSRL

2006-05-01T23:59:59.000Z

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441

Resonant Auger Effect at High X-Ray Intensity  

SciTech Connect

The resonant Auger effect of atomic neon exposed to high-intensity x-ray radiation in resonance with the 1s {yields} 3p transition is discussed. High intensity here means that the x-ray peak intensity is sufficient ({approx} 10{sup 18} W/cm{sup 2}) to induce Rabi oscillations between the neon ground state and the 1s{sup -1}3p ({sup 1}P) state within the relaxation lifetime of the inner-shell vacancy. For the numerical analysis presented, an effective two-level model, including a description of the resonant Auger decay process, is employed. Both coherent and chaotic x-ray pulses are treated. The latter are used to simulate radiation from x-ray free-electron lasers based on the principle of self-amplified spontaneous emission. Observing x-ray-driven atomic population dynamics in the time domain is challenging for chaotic pulse ensembles. A more practical option for experiments using x-ray free-electron lasers is to measure the line profiles in the kinetic energy distribution of the resonant Auger electron. This provides information on both atomic population dynamics and x-ray pulse properties.

Rohringer, N; Santra, R

2008-03-27T23:59:59.000Z

442

Atomic processes in plasmas under ultra-intense laser irradiation  

Science Conference Proceedings (OSTI)

Lasers delivering subpicosecond pulses with energies of a fraction of a Joule have made it possible to generate irradiance levels approaching 10{sup 20} W/cm{sup 2}. We presently operate two such systems, a KrF based excimer laser capable of producing a few 10{sup 17} W/cm{sup 2} at 248 nm with a repetition rate of 3--5 Hz and a XeCl based excimer laser capable of producing mid 10{sup 19} W/cm{sup 2} at 308 nm and 1 Hz. We will discuss some experimental results and the theory and modeling of the interaction of such intense laser pulses with aluminum. Because of a small ASE prepulse the high intensity interaction is not at the solid surface but rather at the n{sub e} = 2 {times} 10{sup 22} cm{sup {minus}3} critical density of the blowoff plasma generated by the ASE. The transient behavior of the plasma following the energy deposition by the intense subpicosecond pulse can be viewed as the energy-impulse response of the plasma. Experimental results and modeling of the x-ray emission from this plasma will be presented. 15 refs., 8 figs.

Schappert, G.T.; Casperson, D.E.; Cobble, J.A.; Comly, J.C.; Jones, L.A.; Kyrala, G.A.; LaGattuta, K.J.; Lee, P.H.Y.; Olson, G.L.; Taylor, A.J.

1989-11-01T23:59:59.000Z

443

A workshop on enhanced national capability for neutron scattering  

SciTech Connect

This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron sc