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1

Neutron sources and applications  

SciTech Connect

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)

1994-01-01

2

Italian neutron sources  

NASA Astrophysics Data System (ADS)

Many research activities, instrumental analysis, studies of radiation damage, etc., require neutron sources. The main neutron sources present in Italy are described in three different sections: nuclear research reactors, accelerator driven, and metrology stations. The nuclear research reactors of LENA (University of Pavia) and ENEA Casaccia are described in terms of irradiation facilities available, neutron flux for each of them and the main activities carried out by each research centre. In the second section, the Frascati Neutron Generator (FNG), the Frascati Beam-Test Facility (BTF) and their main features are reported. In the last section there is a detailed description of the institutional role and the main activities carried out in the field of neutron metrology by the National Institute for Metrology of Ionizing Radiation (INMRI) with a brief description of neutron sources of which the institute is endowed.

Prata, M.; Alloni, D.; De Felice, P.; Palomba, M.; Pietropaolo, A.; Pillon, M.; Quintieri, L.; Santagata, A.; Valente, P.

2014-11-01

3

COLD NEUTRON SOURCES  

Microsoft Academic Search

Experimental work on cold neutron source development is reviewed along ; with the theoretical explanations devised for the results obtained. Factors ; governing source design, the associated cryogenic and safety problems, large ; source design, and experiments by which source efficiency might be increased are ; also discussed. (D.C.W.);

F WEBB

1963-01-01

4

Pulsed spallation neutron sources  

SciTech Connect

This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology.

Carpenter, J.M. [Argonne National Lab., IL (United States). Intense Pulsed Neutron Source Div.

1996-05-01

5

Spallation-neutron sources  

SciTech Connect

Of particular interest for neutron-physics studies are spallation-neutron sources (SNSs) using intense proton beams with energies in the GeV range. Some SNSs already provide average fluxes of thermal and cold neutrons comparable with those of high-flux reactors. Most SNSs are pulsed with high peak fluxes that can be used with the powerful time-of-flight (TOF) method. Also, SNSs could be developed to much higher performance.

Michaudon, A.

1997-09-01

6

Fast neutron source reactor, YAYOI  

Microsoft Academic Search

The characteristics of the fast neutron source reactor, YAYOI of the University of Tokyo are described. The results of major researches are summarized. Those are the studies of fast neutron shielding and neutron transport, development of standard neutron field, advanced neutron detection, measurement of decay heat, development of epithermal neutron columns for boron neutron capture therapy, on-line tritium recovery from

Y. Oka; S. Koshizuka; I. Saito; K. Okamura; N. Aizawa; N. Sasuga; T. Sukegawa; T. Terakado; Y. Mabuchi; T. Nakagawa; S. An

1998-01-01

7

SNS: Spallation Neutron Source  

NSDL National Science Digital Library

The Spallation Neutron Source (SNS) is an accelerator-based neutron source currently being built by the United States Department of Energy. Users can find out about upcoming workshops, conferences, and other events dealing with the accelerator, which is scheduled to be completed in 2006. By downloading a series of materials, users can learn about SNS's benefits and mechanisms. Researchers can discover SNS's mission, instrumentation, moderators, and detectors. The website provides live video of the construction site. Visitors can also learn about employment opportunities.

8

ACCELERATOR BASED CONTINUOUS NEUTRON SOURCE  

Microsoft Academic Search

Until the last decade, most neutron experiments have been performed at steady-state, reactor-based sources. Recently, however, pulsed spallation sources have been shown to be very useful in a wide range of neutron studies. A major review of neutron sources in the US was conducted by a committee chaired by Nobel laureate Prof. W. Kohn: ''Neutron Sources for America's Future-BESAC Panel

S. M. SHAPIRO; A. G. RUGGIERO; H. LUDEWIG

2003-01-01

9

ACCELERATOR BASED CONTINUOUS NEUTRON SOURCE.  

SciTech Connect

Until the last decade, most neutron experiments have been performed at steady-state, reactor-based sources. Recently, however, pulsed spallation sources have been shown to be very useful in a wide range of neutron studies. A major review of neutron sources in the US was conducted by a committee chaired by Nobel laureate Prof. W. Kohn: ''Neutron Sources for America's Future-BESAC Panel on Neutron Sources 1/93''. This distinguished panel concluded that steady state and pulsed sources are complementary and that the nation has need for both to maintain a balanced neutron research program. The report recommended that both a new reactor and a spallation source be built. This complementarity is recognized worldwide. The conclusion of this report is that a new continuous neutron source is needed for the second decade of the 20 year plan to replace aging US research reactors and close the US neutron gap. it is based on spallation production of neutrons using a high power continuous superconducting linac to generate protons impinging on a heavy metal target. There do not appear to be any major technical challenges to the building of such a facility since a continuous spallation source has been operating in Switzerland for several years.

SHAPIRO,S.M.; RUGGIERO,A.G.; LUDEWIG,H.

2003-03-25

10

RIKEN Radio Isotope Beam Factory: Japanese Flagship for Nuclear Science  

NASA Astrophysics Data System (ADS)

Recent activities at the RIKEN Radio Isotope Beam Factory (RIBF) are reported together with its history and future prospects. RIBF is the Japanese flagship for nuclear science, and at this moment is the world flagship machine.

En'yo, Hideto

2015-11-01

11

Advanced Neutron Source (ANS) Project  

NASA Astrophysics Data System (ADS)

This report discusses the following about the Advanced Neutron Source: Project Management; Research and Development; Fuel Development; Corrosion Loop Tests and Analyses; Thermal-Hydraulic Loop Tests; Reactor Control and Shutdown Concepts; Critical and Subcritical Experiments; Material Data, Structural Tests, and Analysis; Cold-Source Development; Beam Tube, Guide, and Instrument Development; Hot-Source Development; Neutron Transport and Shielding; I & C Research and Development; Design; and Safety.

Campbell, J. H.

1992-01-01

12

Curium-248 standard neutron source  

PubMed

A new standard neutron source based on curium-248 has been developed, prepared, and certified. The curium-248 isotope is more long-lived than californium-252. The active core of this source is a pellet made of an alloy of platinum with curium. The measured full neutron yield for this source is 2.30 x 10(4) s(-1) with 4% error at 0.95 confidence. PMID:11003529

Radchenko; Ryabinin; Andreytchuk; Gavrilov; Karelin

2000-10-01

13

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)

2012-06-19

14

Research on fusion neutron sources  

NASA Astrophysics Data System (ADS)

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.

2012-06-01

15

International Spallation Ultracold Neutron Source  

E-print Network

and UCN Source Proton beam from TRIUMF cyclotron iSUN Implementation at TRIUMF Meson Hall concept UCN outInternational Spallation Ultracold Neutron Source We propose to construct the world's highest extraction, improved guide technology, etc. Item Cost Funding Source UCN cryostat system $4M Japanese

Martin, Jeff

16

Materials for spallation neutron sources  

SciTech Connect

The Workshop on Materials for Spallation Neutron Sources at the Los Alamos Neutron Science Center, February 6 to 10, 1995, gathered scientists from Department of Energy national laboratories, other federal institutions, universities, and industry to discuss areas in which work is needed, successful designs and use of materials, and opportunities for further studies. During the first day of the workshop, speakers presented overviews of current spallation neutron sources. During the next 3 days, seven panels allowed speakers to present information on a variety of topics ranging from experimental and theoretical considerations on radiation damage to materials safety issues. An attempt was made to identify specific problems that require attention within the context of spallation neutron sources. This proceedings is a collection of summaries from the overview sessions and the panel presentations.

Sommer, W.F.; Daemen, L.L. [comps.

1996-03-01

17

Neutron focusing system for the Texas Cold Neutron Source  

Microsoft Academic Search

A ``converging neutron guide'' focusing system located at the end of the Texas Cold Neutron Source (TCNS) ``curved neutron guide'' would increase the neutron flux for neutron capture experiments. Our design for a converging guide is based on using several rectangular truncated cone sections. Each rectangular truncated cone consists of four 20-cm long Si plates coated with NiC-Ti supermirrors. Dimensions

Bernard W. Wehring; Jong-Youl Kim; Kenan Ünlü

1994-01-01

18

Ukraine experimental neutron source facility  

Microsoft Academic Search

Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an experimental neutron source facility. The facility has been developed for producing medical isotopes, training young nuclear professionals, supporting the Ukraine nuclear industry, providing capability for performing reactor physics, material research, and basic science experiments. Argonne National Laboratory (ANL) of USA is collaborating with KIPT on

Y. Gohar; I. Bolshinsky; I. Nekludov; I. Karnaukhov

2008-01-01

19

CHINA SPALLATION NEUTRON SOURCE DESIGN.  

SciTech Connect

The China Spallation Neutron Source (CSNS) is an accelerator-based high-power project currently in preparation under the direction of the Chinese Academy of Sciences (CAS). The complex is based on an H- linear accelerator, a rapid cycling proton synchrotron accelerating the beam to 1.6 GeV, a solid tungsten target station, and five initial instruments for spallation neutron applications. The facility will operate at 25 Hz repetition rate with a phase-I beam power of about 120 kW. The major challenge is to build a robust and reliable user's facility with upgrade potential at a fractional of ''world standard'' cost.

WEI,J.

2007-01-29

20

Option for spallation neutron sources  

NASA Astrophysics Data System (ADS)

Spallation reactions are a very important option for efficient neutron sources appropriate for fusion materials testing. An “option of this option” is the EURAC concept, which makes use of short-term accelerator technology in the cheapest way and is proved to provide the needed neutron flux to verify fast experiments on fusion materials performance. Its flexible conception allows an optimum combination of very high fluxes of about 1016 n/cm2/s, with decreasing fluxes along the testing zones in enough volume to perform the correct irradiations. With this assumption, the rate effect can be perfectly analyzed together with the end-of-life conditions assumed in the structural material of the future fusion environments. The possible negative effects of the high-energy neutrons in the Spallation spectrum have been taken into account, concluding their non-significance in the desired damage parameters. The EURAC concept can also be considered in light of other purposes like incineration processes, ? production, and, with the appropriate booster, high-flux cold neutron source.

Perlado, J. M.; Piera, M.; Sanz, J.

1989-12-01

21

New neutron sources for radiotherapy  

Microsoft Academic Search

All existing neutron sources suffer from disadvantages which would not be tolerated in modern megavoltage X-ray equipment. Experimental work with 30-60 MeV protons on beryllium and other elements has shown how these difficulties can to a large extent be overcome. Angular distributions and kerma rates as a function of proton energy are presented for various targets. Thin targets are found

D. K. Bewley

1984-01-01

22

Californium-252 Neutron Sources for Medical Applications  

SciTech Connect

Californium-252 neutron sources are being prepared to investigate the value of this radionuclide in diagnosing and treating diseases. A source resembling a cell-loaded radium needle was developed for neutron therapy. Since therapy needles are normally implanted in the body, very conservative design criteria were established to prevent leakage of radioactive. Methods are being developed to prepare very intense californium sources that could be used eventually for neutron radiography and for diagnosis by neutron activation analysis. This paper discusses these methods.

Boulogne, A.R.

2001-08-29

23

The advanced neutron source reactor: An overview  

Microsoft Academic Search

The Advanced Neutron Source (ANS) will be a new user facility for all kinds of neutron research, including neutron scattering, materials testing, materials analysis, isotope production and nuclear physics experiments. The centerpiece of the facility is to be the world's highest flux beam reactor. There will be beams of hot, cold and thermal neutrons for more than 40 simultaneous scattering

1990-01-01

24

Fission neutron source in Rome  

NASA Astrophysics Data System (ADS)

A fission neutron source is operating in Rome at the ENEA Casaccia Research Center since 1971, consisting of a low power fast reactor named RSV-Tapiro. it is employed for a variety of experiments, including dosimetry, material testing, radiation protection and biology. In particular, application to experimental radiobiology includes studies of the biological action of neutrons in the whole-body irradiated animal, or in specialized systems in vivo or in vitro. For his purpose a vertical irradiation facility was originally constructed. Recently, a new horizontal irradiation facility has been designed to allow the exposure of larger samples or larger sample batches at one time. Dosimetry at the sample irradiation positions is routinely carried out by the conventional method of using two ion chambers. This physical dosimetry has recently been compared with the results of biological dosimetry based on the detection of chromosomal aberrations in peripheral blood human lymphocytes irradiated in vitro. A characterization of the radiation quality in the two configurations has been carried out by tissue equivalent proportional counter microdosimetry measurements. Information about the main characteristics of the reactor and the two irradiation facilities is provided and relevant results of the various measurements are summarized. Radiobiological results obtained using this neutron source are also briefly outlined.

Coppola, Mario; Di Majo, V.; Ingrao, G.; Rebessi, S.; Testa, A.

1997-02-01

25

A National Spallation Neutron Source for neutron scattering  

SciTech Connect

The National Spallation Neutron Source is a collaborative project or perform the conceptual design for a next generation neutron source for the Department of Energy. This paper reviews the need and justification for a new neutron source, the origins and structure of the collaboration formed to address this need, and the community input leading up to the current design approach. A reference design is presented for an accelerator based spallation neutron source that would begin operation at about 1 megawatt of power but designed so that it could be upgraded to significantly higher powers in the future. The technology approach, status, and progress on the conceptual design to date are presented.

Appleton, B.R.

1996-10-01

26

International workshop on cold neutron sources  

Microsoft Academic Search

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5 to 8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people

G. J. Russell; C. D. West

1991-01-01

27

International Workshop on Cold Neutron Sources  

Microsoft Academic Search

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory (New Mexico, USA) from March 5–8, 1990. The meeting (cosponsored by Los Alamos and Oak Ridge National Laboratories) was organized as an International Workshop on Cold Neutron Sources, and brought together experts in the fields of reactor and spallation cold-neutron-source design. Eighty-four people from

Gary Russell; Colin West

1990-01-01

28

Laser generated neutron source for neutron resonance spectroscopy  

SciTech Connect

A neutron source for neutron resonance spectroscopy has been developed using high-intensity, short-pulse lasers. This technique will allow robust measurement of interior ion temperature of laser-shocked materials and provide insight into material equation of state. The neutron generation technique uses laser-accelerated protons to create neutrons in LiF through (p,n) reactions. The incident proton beam has been diagnosed using radiochromic film. This distribution is used as the input for a (p,n) neutron prediction code which is validated with experimentally measured neutron yields. The calculation infers a total fluence of 1.8x10{sup 9} neutrons, which are expected to be sufficient for neutron resonance spectroscopy temperature measurements.

Higginson, D. P.; Bartal, T. [Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); McNaney, J. M.; Swift, D. C.; Hey, D. S.; Le Pape, S.; Mackinnon, A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Kodama, R.; Tanaka, K. A. [Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Mariscal, D.; Beg, F. N. [Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093 (United States); Nakamura, H. [Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871 (Japan); Nakanii, N. [Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093 (United States); Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan)

2010-10-15

29

Converging neutron guide for neutron focusing at the Texas Cold Neutron Source  

Microsoft Academic Search

We have thoroughly investigated the design and construction of a neutron focusing system for use with the Texas Cold Neutron Source (TCNS). The focusing system will be located at the end of the TCNS curved neutron guide to increase the neutron flux for neutron capture experiments that benefit from the low background expected at the end of the curved guide.

J. Y. Kim; B. W. Wehring; K. Uenlue

1993-01-01

30

Switchable radioactive neutron source device  

DOEpatents

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.

Boyar, Robert E. (La Grange, IL); DeVolpi, Alexander (Bolingbrook, IL); Stanford, George S. (Downers Grove, IL); Rhodes, Edgar A. (Woodridge, IL)

1989-01-01

31

Switchable radioactive neutron source device  

DOEpatents

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.

1987-11-06

32

Neutron sources: present practice and future potential  

SciTech Connect

The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500+ MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-production efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: (i) fundamental neutron-nuclear research, (ii) nuclear-data acquisition, (iii) materials-damage studies, (iv) engineering test, and (v) biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections.

Cierjacks, S.; Smith, A.B.

1988-01-01

33

Radio-isotope production using laser Wakefield accelerators  

SciTech Connect

A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu{sup 61} was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator.

Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Toth, C.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.; Reitsma, A.

2001-07-27

34

Spallation Neutron Source reaches megawatt power  

ScienceCinema

The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

Dr. William F. Brinkman

2010-01-08

35

Spallation Neutron Source reaches megawatt power  

SciTech Connect

The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

Dr. William F. Brinkman

2009-09-30

36

The University of Texas Cold Neutron Source  

Microsoft Academic Search

A cold neutron source has been designed, constructed, and tested by the Nuclear Engineering Teaching Laboratory (NETL) at The University of Texas at Austin. The Texas Cold Neutron Source (TCNS) is located in one of the beam ports of the NETL 1-MW TRIGA Mark II research reactor. The main components of the TCNS are a cooled moderator, a heat pipe,

Kenan Ünlü; Carlos Ríos-Martínez; Bernard W. Wehring

1994-01-01

37

Cyclotron-based neutron source for BNCT  

NASA Astrophysics Data System (ADS)

Kyoto University Research Reactor Institute (KURRI) and Sumitomo Heavy Industries, Ltd. (SHI) have developed a cyclotron-based neutron source for Boron Neutron Capture Therapy (BNCT). It was installed at KURRI in Osaka prefecture. The neutron source consists of a proton cyclotron named HM-30, a beam transport system and an irradiation & treatment system. In the cyclotron, H- ions are accelerated and extracted as 30 MeV proton beams of 1 mA. The proton beams is transported to the neutron production target made by a beryllium plate. Emitted neutrons are moderated by lead, iron, aluminum and calcium fluoride. The aperture diameter of neutron collimator is in the range from 100 mm to 250 mm. The peak neutron flux in the water phantom is 1.8×109 neutrons/cm2/sec at 20 mm from the surface at 1 mA proton beam. The neutron source have been stably operated for 3 years with 30 kW proton beam. Various pre-clinical tests including animal tests have been done by using the cyclotron-based neutron source with 10B-p-Borono-phenylalanine. Clinical trials of malignant brain tumors will be started in this year.

Mitsumoto, T.; Yajima, S.; Tsutsui, H.; Ogasawara, T.; Fujita, K.; Tanaka, H.; Sakurai, Y.; Maruhashi, A.

2013-04-01

38

Neutron dosimetry at SLAC: Neutron sources and instrumentation  

SciTech Connect

This report summarizes in detail the dosimetric characteristics of the five radioisotopic type neutron sources ({sup 238}PuBe, {sup 252}Cf, {sup 238}PuB, {sup 238}PuF{sub 4}, and {sup 238}PuLi) and the neutron instrumentation (moderated BF{sub 3} detector, Anderson-Braun (AB) detector, AB remmeter, Victoreen 488 Neutron Survey Meter, Beam Shut-Off Ionization Chamber, {sup 12}C plastic scintillator detector, moderated indium foil detector, and moderated and bare TLDs) that are commonly used for neutron dosimetry at the Stanford Linear Accelerator Center (SLAC). 36 refs,. 19 figs.

Liu, J.C.; Jenkins, T.M.; McCall, R.C.; Ipe, N.E.

1991-10-01

39

Unconventional neutron sources for oil well logging  

NASA Astrophysics Data System (ADS)

Americium-Beryllium (AmBe) radiological neutron sources have been widely used in the petroleum industry for well logging purposes. There is strong desire on the part of various governmental and regulatory bodies to find alternate sources due to the high activity and small size of AmBe sources. Other neutron sources are available, both radiological (252Cf) and electronic accelerator driven (D-D and D-T). All of these, however, have substantially different neutron energy spectra from AmBe and thus cause significantly different responses in well logging tools. We report on simulations performed using unconventional sources and techniques to attempt to better replicate the porosity and carbon/oxygen ratio responses a well logging tool would see from AmBe neutrons. The AmBe response of these two types of tools is compared to the response from 252Cf, D-D, D-T, filtered D-T, and T-T sources.

Frankle, C. M.; Dale, G. E.

2013-09-01

40

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Tritium neutron generator target sources. 39.55 Section...Equipment § 39.55 Tritium neutron generator target sources. (a) Use of a tritium neutron generator target source, containing...

2012-01-01

41

10 CFR 39.55 - Tritium neutron generator target sources.  

...2014-01-01 false Tritium neutron generator target sources. 39.55 Section...Equipment § 39.55 Tritium neutron generator target sources. (a) Use of a tritium neutron generator target source, containing...

2014-01-01

42

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Tritium neutron generator target sources. 39.55 Section...Equipment § 39.55 Tritium neutron generator target sources. (a) Use of a tritium neutron generator target source, containing...

2013-01-01

43

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Tritium neutron generator target sources. 39.55 ...LOGGING Equipment § 39.55 Tritium neutron generator target sources. (a) Use of a tritium neutron generator target source,...

2011-01-01

44

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Tritium neutron generator target sources. 39.55 ...LOGGING Equipment § 39.55 Tritium neutron generator target sources. (a) Use of a tritium neutron generator target source,...

2010-01-01

45

Advanced Neutron Source (ANS) Project progress report  

SciTech Connect

This report discusses the following topics on the advanced neutron source: quality assurance (QA) program; reactor core development; fuel element specification; corrosion loop tests and analyses; thermal-hydraulic loop tests; reactor control concepts; critical and subcritical experiments; material data, structural tests, and analysis; cold source development; beam tube, guide, and instrument development; hot source development; neutron transport and shielding; I C research and development; facility concepts; design; and safety.

McBee, M.R.; Chance, C.M. (eds.) (Oak Ridge National Lab., TN (USA)); Selby, D.L.; Harrington, R.M.; Peretz, F.J. (Oak Ridge National Lab., TN (USA))

1990-04-01

46

Observation of Neutron Skyshine from an Accelerator Based Neutron Source  

NASA Astrophysics Data System (ADS)

A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >1011 n?s-1. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

Franklyn, C. B.

2011-12-01

47

Observation of Neutron Skyshine from an Accelerator Based Neutron Source  

SciTech Connect

A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

2011-12-13

48

Modulating the Neutron Flux from a Mirror Neutron Source  

SciTech Connect

A 14-MeV neutron source based on a Gas-Dynamic Trap will provide a high flux of 14 MeV neutrons for fusion materials and sub-component testing. In addition to its main goal, the source has potential applications in condensed matter physics and biophysics. In this report, the author considers adding one more capability to the GDT-based neutron source, the modulation of the neutron flux with a desired frequency. The modulation may be an enabling tool for the assessment of the role of non-steady-state effects in fusion devices as well as for high-precision, low-signal basic science experiments favoring the use of the synchronous detection technique. A conclusion is drawn that modulation frequency of up to 1 kHz and modulation amplitude of a few percent is achievable. Limitations on the amplitude of modulations at higher frequencies are discussed.

Ryutov, D D

2011-09-01

49

Design calculations for the ANS (advanced neutron source) cold neutron source  

Microsoft Academic Search

The advanced neutron source (ANS) is a new experimental facility being planned at the Oak Ridge National Laboratory to meet the national need for an intense steady-state neutron source. A major purpose of the ANS is to provide a high flux of cold ({approx equal} 0.3-nm) neutrons for experiments. High fluxes of such cold neutrons can be obtained from a

R. A. Lillie; R. G. Jr. Alsmiller

1990-01-01

50

Inertial electrostatic confinement (IEC) neutron sources  

SciTech Connect

Inertial electrostatic confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron yields as high as 2 x 10(exp 10) neutrons/sec in steady state. These systems have considerable potential as small, inexpensive, portable neutron sources for assaying applications. Neutron tomography is also a potential application. This paper discusses the IEC concept and how it can be adapted to a steady-state assaying source and an intense pulsed neutron source. Theoretical modeling and experimental results are presented.

Barnes, D.C.; Caramana, E.J.; Janssen, R.D.; Nystrom, W.D.; Tiouririne, T.N.; Trent, B.C.; Miley, G.H.; Javedani, J.

1995-01-01

51

Inertial electrostatic confinement (IEC) neutron sources  

SciTech Connect

Inertial Electrostatic Confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron yields as high as 2 {times} 10{sup 10} neutrons/sec in steady state. These systems have considerable potential as small, inexpensive, portable neutron sources for assaying applications. Neutron tomography is also a potential application. This paper discusses the IEC concept and how it can be adapted to a steady-state assaying source and an intense pulsed neutron source. Theoretical modeling and experimental results are presented.

Nebel, R.A.; Barnes, D.C.; Caramana, E.J.; Janssen, R.D.; Nystrom, W.D.; Tiouririne, T.N.; Trent, B.C. [Los Alamos National Lab., NM (United States); Miley, G.H.; Javedani, J. [Univ. of Illinois, Urbana, IL (United States)

1995-12-31

52

Cryogenic detectors for advanced neutron sources  

NASA Astrophysics Data System (ADS)

Next-generation pulsed neutron sources using high-intensity proton accelerators have made a great deal of progress in Japan (J-PARC project), United States (SNS project), and United Kingdom (ISIS second target station project), where the peak intensity of the neutrons flux is expected to be an order of magnitude higher than the existing highest flux steady reactor in the Institut Laue-Langevin. The high-intensity pulsed neutron source would open up a possibility to use a micron-sized neutron beam, thus the neutron detectors with a high spatial resolution of a few micrometers and a temporal resolution of a few microseconds would be required. The cryogenic detectors using superconducting tunnel junctions or microcalorimeter would be key instruments to explore new sciences in such applications. Moreover, neutron detectors operating at a cryogenic temperature have an important role in physics research using fast neutrons or ultra-cold neutrons. In such applications, the microcalorimeters and the solid-state semiconductor detectors with neutron converters ( 6Li, 10B, 3He) have been developed. The cryogenic neutron detectors and their applications are reviewed in this report.

Katagiri, Masaki

2006-04-01

53

Improved neutron sources for neutron capture enhanced fast neutron therapy  

SciTech Connect

Fast neutron radiotherapy (FNT) can be combined with boron neutron capture therapy (BNCT). The selective incremental absorbed dose in the target volume that is thus obtained may be sufficient to produce a significant improvement in tumor control probability in some cases. Potential applications include certain non-small-cell lung tumors; head and neck tumors; prostate tumors; and possibly also glioblastoma multiform, an extremely refractory type of primary brain tumor. A class of modified neutron production targets has been developed to provide improved performance of the cyclotron-based clinical FNT facility at the University of Washington (UW) Medical Center for applications involving BNCT-enhanced FNT. The new targets produce neutron beams that feature essentially the same fast neutron physical depth-dose performance as the current UW system but with an increased fraction of BNCT enhancement.

Nigg, D.W.; Wemple, C.A.; Risler, R.; Hartwell, J.K.; Harker, Y.D.; Laramore, G.E.

2000-07-01

54

High Brightness Neutron Source for Radiography  

Microsoft Academic Search

This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is

J. T. Cremer; Piestrup; A. Melvin; K. Charles; Jack Harris; David L. Williams; Glenn Jones; J. Vainionpaa; Fuller; J. Michael; Rothbart; H. George; J. Kwan; B. Ludewigt; Gough; Jani Reijonen; Ka-Ngo Leung

2008-01-01

55

Performance of the Texas cold neutron source  

Microsoft Academic Search

The recently completed Texas Cold Neutron Source (TCNSN) system consists of a cooled moderator, a neon heat pipe, a cryogenic refrigerator, and a neutron guide tube. The TCNS fits into the piercing beam port of the 1-MW TRIGA Mark II reactor at the Nuclear Engineering Teaching Laboratory of the University of Texas. The moderator chosen for the TCNS is mesitylene,

K. Uenlue; C. Rios-Martinez; B. W. Wehring

1992-01-01

56

Cryogenic hydrogen circulation system of neutron source  

SciTech Connect

Cold neutron sources of reactors and spallation neutron sources are classic high flux neutron sources in operation all over the world. Cryogenic fluids such as supercritical or supercooled hydrogen are commonly selected as a moderator to absorb the nuclear heating from proton beams. By comparing supercritical hydrogen circulation systems and supercooled hydrogen circulation systems, the merits and drawbacks in both systems are summarized. When supercritical hydrogen circulates as the moderator, severe pressure fluctuations caused by temperature changes will occur. The pressure control system used to balance the system pressure, which consists of a heater as an active controller for thermal compensation and an accumulator as a passive volume controller, is preliminarily studied. The results may provide guidelines for design and operation of other cryogenic hydrogen system for neutron sources under construction.

Qiu, Y. N. [Institute of Physics and Chemistry, Chinese Academy of Sciences, BJ100190 China and University of Chinese Academy of Sciences, Chinese Academy of Sciences, BJ100049 (China); Hu, Z. J.; Wu, J. H.; Li, Q.; Zhang, Y. [Institute of Physics and Chemistry, Chinese Academy of Sciences, BJ100190 (China); Zhang, P. [School of Energy and Power Engineering, HuaZhong University of Science and Technology, WH430074 (China); Wang, G. P. [Institute of High Energy Physics, Chinese Academy of Sciences, BJ100049 (China)

2014-01-29

57

Cryogenic hydrogen circulation system of neutron source  

NASA Astrophysics Data System (ADS)

Cold neutron sources of reactors and spallation neutron sources are classic high flux neutron sources in operation all over the world. Cryogenic fluids such as supercritical or supercooled hydrogen are commonly selected as a moderator to absorb the nuclear heating from proton beams. By comparing supercritical hydrogen circulation systems and supercooled hydrogen circulation systems, the merits and drawbacks in both systems are summarized. When supercritical hydrogen circulates as the moderator, severe pressure fluctuations caused by temperature changes will occur. The pressure control system used to balance the system pressure, which consists of a heater as an active controller for thermal compensation and an accumulator as a passive volume controller, is preliminarily studied. The results may provide guidelines for design and operation of other cryogenic hydrogen system for neutron sources under construction.

Qiu, Y. N.; Hu, Z. J.; Wu, J. H.; Li, Q.; Zhang, Y.; Zhang, P.; Wang, G. P.

2014-01-01

58

Directional measurements for sources of fission neutrons  

Microsoft Academic Search

Although penetrating neutron and gamma-ray emissions arguably provide the most effective signals for locating sources of nuclear radiation, their relatively low fluxes make searching for radioactive materials a tedious process. Even assuming lightly shielded sources and detectors with large areas and high efficiencies, estimated counting times can exceed several minutes for source separations greater than ten meters. Because determining the

R. C. Byrd; G. F. Auchampaugh; W. C. Feldman

1993-01-01

59

Californium-252: A New Isotopic Source for Neutron Radiography  

SciTech Connect

This report discusses a new isotopic source for neutron radiography, Californium-252. Nuclear reactors are the usual source of neutrons for radiography, primarily because of their intense neutron beams. If neutron radiography is to have widespread use, intense transportable neutron sources are required that can be used in plants, in laboratories and in the field.

Reinig, W.C.

2001-08-29

60

RTNS-II Neutron Sources: Status Report  

Microsoft Academic Search

Experience with neutron sources consisting of air-insulated 400 kV deuteron accelerators and tritium targets which rotate at 5000 rpm is reported. These accelerators are part of the Rotating Target Neutron Source-II (RTNS-II) facility. A review of the accelerator design is given. Operation of the prototype accelerator using hydrogen beams is discussed in detail. The parameters are tabulated for the first

J. C. Davis; D. W. Heikkinen; J. L. Held; C. M. Logan; J. E. Osher

1979-01-01

61

An Accelerator Neutron Source for BNCT  

SciTech Connect

The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were 1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, 2) that the patient treatment time be reasonable, 3) that the proton current required to treat patients in reasonable times be technologially achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally 4) that the treatment be safe for the patients.

Blue, Thomas, E

2006-03-14

62

Phenomenological calculations of shielding spallation neutron sources  

NASA Astrophysics Data System (ADS)

The high level of radiation generated by a spallation source requires the design of an appropriate shielding to surround the source in order to fulfill radiation protection standards. A calculation of the spallation neutron attenuation is presented for various shielding materials, using a phenomenological model, based on the Moyer model. In the first step of the calculation, the interaction length of neutrons for each neutron energy and shielding material was estimated using inelastic cross-sections. In the second step the calculation deals with the attenuation of the neutron flux applying the Moyer model, for each material and neutron energy region. The transmission factors were calculated and compared with experimental data collected from the "Gamma-2" and the "E+T" projects running in JINR (Dubna, Russia). The results of the present work were also compared to the data obtained by different Monte Carlo codes such as MORSE, MCNPX, MARS14 and LAHET.

Fragopoulou, M.; Zamani, M.

2013-06-01

63

DIRECTIONAL DETECTION OF A NEUTRON SOURCE.  

SciTech Connect

Advantages afforded by the development of new directional neutron detectors and imagers are discussed. Thermal neutrons have mean free paths in air of about 20 meters, and can be effectively imaged using coded apertures. Fission spectrum neutrons have ranges greater than 100 meters, and carry enough energy to scatter at least twice in multilayer detectors which can yield both directional and spectral information. Such strategies allow better discrimination between a localized spontaneous fission source and the low, but fluctuating, level of background neutrons generated by cosmic rays. A coded aperture thermal neutron imager will be discussed as well as a proton-recoil double-scatter fast-neutron directional detector with time-of-flight energy discrimination.

VANIER, P.E.; FORMAN, L.

2006-10-23

64

Status of the advanced neutron source. [Advanced Neutron Source Reactor  

Microsoft Academic Search

Research reactors in the United States are becoming more and more outdated, at a time when neutron scattering is being recognized as an increasingly important technique in areas vital to the US scientific and technological future. The last US research reactor was constructed over 25 years ago, whereas new facilities have been built or are under construction in Japan, Russia

Hayter

1990-01-01

65

Science Opportunities at ORNL Neutron Sources  

SciTech Connect

The Neutron Sciences Directorate at Oak Ridge National Laboratory (ORNL) operates two of the most advanced neutron scattering research facilities in the world: the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). Our vision is to provide unprecedented capabilities for understanding structure and properties across the spectrum of biology, chemistry, physics, and engineering, and to stay at the leading edge of neutron science by developing new instruments, tools, and services. This talk will provide an update on the operations of the two research facilities and highlight the significant research that is emerging. For example, scientists from ORNL are at the forefront of research on a new class of iron-based superconductors based on experiments performed at the Triple-Axis Spectrometer at HFIR and ARCS at SNS. The complementary nature of neutron and x-ray techniques will be discussed to spark discussion among attendees.

Anderson, Ian (ORNL, SNS) [ORNL, SNS

2010-02-03

66

The FRM-II cold neutron source  

Microsoft Academic Search

The cold neutron source of new high flux research reactor FRM-II will be placed near the thermal flux maximum to obtain a cold neutron flux of 1×1014n\\/cm2\\/s and a thermal flux of 2.5×1014n\\/cm2\\/s in the moderator volume of 16l liquid deuterium at 25K. The total heat load in the cold part of the CNS generated by nuclear heating amounts to

Werner Gaubatz; Klaus Gobrecht

2000-01-01

67

Applications for the Texas cold neutron source  

Microsoft Academic Search

One of the viable instructional and research areas for a 1-MW university research reactor is the [open quotes]use of neutrons to probe the structure and dynamics of condensed matter.[close quotes] A cold neutron source has been designed, constructed, and tested as the first step in addressing this function at the University of Texas research reactor. Using the results of these

B. W. Wehring; K. Uenlue; J. Y. Kim; C. Rios-Martinez

1993-01-01

68

Neutron science opportunities at pulsed spallation neutron sources  

SciTech Connect

Using the IPNS Upgrade plan developed at Argonne National Laboratory as a worked example of the design of a pulsed spallation neutron source, this paper explores some of the scientific applications of an advanced facility for materials science studies and the instrumentation for those purposes.

Carpenter, J.M. [Argonne National Lab., IL (United States). Intense Pulsed Neutron Source

1996-12-31

69

Neutron production enhancements for the Intense Pulsed Neutron Source.  

SciTech Connect

The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments.

Iverson, E. B.

1999-01-04

70

Directional measurements for sources of fission neutrons  

SciTech Connect

Although penetrating neutron and gamma-ray emissions arguably provide the most effective signals for locating sources of nuclear radiation, their relatively low fluxes make searching for radioactive materials a tedious process. Even assuming lightly shielded sources and detectors with large areas and high efficiencies, estimated counting times can exceed several minutes for source separations greater than ten meters. Because determining the source position requires measurements at several locations, each with its own background, the search procedure can be lengthy and difficult to automate. Although directional measurements can be helpful, conventional collimation reduces count rates and increases the detector size and weight prohibitively, especially for neutron instruments. We describe an alternative approach for locating radiation sources that is based on the concept of a polarized radiation field. In this model, the presence of a source adds a directional component to the randomly oriented background radiation. The net direction of the local field indicates the source angle, and the magnitude provides an estimate of the distance to the source. The search detector is therefore seen as a device that responds to this polarized radiation field. Our proposed instrument simply substitutes segmented detectors for conventional single-element ones, so it requires little or no collimating material or additional weight. Attenuation across the detector creates differences in the count rates for opposite segments, whose ratios can be used to calculate the orthogonal components of the polarization vector. Although this approach is applicable to different types of radiation and detectors, in this report we demonstrate its use for sources of fission neutrons by using a prototype fast-neutron detector, which also provides background-corrected energy spectra for the incident neutrons.

Byrd, R.C.; Auchampaugh, G.F.; Feldman, W.C.

1993-11-01

71

THERMAL NEUTRON INTENSITIES IN SOILS IRRADIATED BY FAST NEUTRONS FROM POINT SOURCES. (R825549C054)  

EPA Science Inventory

Thermal-neutron fluences in soil are reported for selected fast-neutron sources, selected soil types, and selected irradiation geometries. Sources include 14 MeV neutrons from accelerators, neutrons from spontaneously fissioning 252Cf, and neutrons produced from alp...

72

Secondary electron ion source neutron generator  

DOEpatents

A neutron generator employing an electron emitter, an ion source bombarded by the electrons from the electron emitter, a plasma containment zone, and a target situated between the plasma containment zone and the electron emitter. The target contains occluded deuterium, tritium, or a mixture thereof

Brainard, John P. (Albuquerque, NM); McCollister, Daryl R. (Albuquerque, NM)

1998-01-01

73

Cold neutron source at the Budapest reactor  

Microsoft Academic Search

The installation of a liquid hydrogen cold neutron source assembly with a single closed circuit feed by two cryogenerators and utilizing the thermosyphon principle is in progress at the reconstructed Budapest reactor. The end of the in-pile part is a nearly tangential horiaontal channel with a moderator cell of 250 cm3 volume made of aluminium alloy located in a hole

T. Grosz; L. Cser; L. Rosta; M. Szalok; G. Zsigmond

1992-01-01

74

The Spallation Neutron Source RF Reference System  

Microsoft Academic Search

The Spallation Neutron Source (SNS) RF Reference System includes the master oscillator (MO), local oscillator(LO) distribution, and Reference RF distribution systems. Coherent low noise Reference RF signals provide the ability to control the phase relationships between the fields in the front-end and linear accelerator (linac) RF cavity structures. The SNS RF Reference System requirements, implementation details, and performance are discussed.

M. Piller; M. Champion; M. Crofford; H. Ma; L. Doolittle

2005-01-01

75

Spallation Neutron Sources and Accelerator-Driven Systems  

NASA Astrophysics Data System (ADS)

Spallation neutron sources are the primary accelerator-driven source of intense neutrons. They require high power proton accelerators in the GeV energy range coupled to heavy metal targets for efficient neutron production. They form the basis of large scale neutron scattering facilities, and are essential elements in accelerator-driven subcritical reactors. Demanding technology has been developed which is enabling the next generation of spallation neutron sources to reach even higher neutron fluxes. This technology sets the stage for future deployment in accelerator-driven systems and neutron sources for nuclear material irradiation.

Henderson, Stuart D.

2014-02-01

76

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

Microsoft Academic Search

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

Z. Zhong; Y. Gohar; R. Kellogg

2009-01-01

77

Enrico Fermi's Discovery of Neutron-Induced Artificial Radioactivity: Neutrons and Neutron Sources  

NASA Astrophysics Data System (ADS)

We reconstruct and analyze the path leading from James Chadwick’s discovery of the neutron in February 1932 through Frédéric Joliot and Irène Curie’s discovery of artificial radioactivity in January 1934 to Enrico Fermi’s discovery of neutron-induced artificial radioactivity in March 1934. We show, in particular, that Fermi’s innovative construction and use of radon-beryllium neutron sources permitted him to make his discovery.

Guerra, Francesco; Leone, Matteo; Robotti, Nadia

2006-09-01

78

Spallation neutron source and other high intensity froton sources  

SciTech Connect

This lecture is an introduction to the design of a spallation neutron source and other high intensity proton sources. It discusses two different approaches: linac-based and synchrotron-based. The requirements and design concepts of each approach are presented. The advantages and disadvantages are compared. A brief review of existing machines and those under construction and proposed is also given. An R&D program is included in an appendix.

Weiren Chou

2003-02-06

79

Portable, high intensity isotopic neutron source provides increased experimental accuracy  

NASA Technical Reports Server (NTRS)

Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy.

Mohr, W. C.; Stewart, D. C.; Wahlgren, M. A.

1968-01-01

80

HIGH FLUENCE NEUTRON SOURCE FOR NONDESTRUCTIVE CHARACTERIZATION OF NUCLEAR WASTE  

EPA Science Inventory

We propose to research the basic plasma physics necessary to develop a high fluence neutron source based on the inertial electrostatically confined (IEC) plasma. An intense neutron source directly addresses the capability to characterize nuclear materials under difficult measurem...

81

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

2009-02-17

82

Crystal Driven Neutron Source: A New Paradigm for Miniature Neutron Sources  

SciTech Connect

Neutron interrogation techniques have specific advantages for detection of hidden, shielded, or buried threats over other detection modalities in that neutrons readily penetrate most materials providing backscattered gammas indicative of the elemental composition of the potential threat. Such techniques have broad application to military and homeland security needs. Present neutron sources and interrogation systems are expensive and relatively bulky, thereby making widespread use of this technique impractical. Development of a compact, high intensity crystal driven neutron source is described. The crystal driven neutron source approach has been previously demonstrated using pyroelectric crystals that generate extremely high voltages when thermal cycled [1-4]. Placement of a sharpened needle on the positively polarized surface of the pyroelectric crystal results in sufficient field intensification to field ionize background deuterium molecules in a test chamber, and subsequently accelerate the ions to energies in excess of {approx}100 keV, sufficient for either D-D or D-T fusion reactions with appropriate target materials. Further increase in ion beam current can be achieved through optimization of crystal thermal ramping, ion source and crystal accelerator configuration. The advantage of such a system is the compact size along with elimination of large, high voltage power supplies. A novel implementation discussed incorporates an independently controlled ion source in order to provide pulsed neutron operation having microsecond pulse width.

Tang, V; Morse, J; Meyer, G; Falabella, S; Guethlein, G; Kerr, P; Park, H G; Rusnak, B; Sampayan, S; Schmid, G; Spadaccini, C; Wang, L

2008-08-08

83

Synchrotron based spallation neutron source concepts  

SciTech Connect

During the past 20 years, rapid-cycling synchrotrons (RCS) have been used very productively to generate short-pulse thermal neutron beams for neutron scattering research by materials science communities in Japan (KENS), the UK (ISIS) and the US (IPNS). The most powerful source in existence, ISIS in the UK, delivers a 160-kW proton beam to a neutron-generating target. Several recently proposed facilities require proton beams in the MW range to produce intense short-pulse neutron beams. In some proposals, a linear accelerator provides the beam power and an accumulator ring compresses the pulse length to the required {approx} 1 {micro}s. In others, RCS technology provides the bulk of the beam power and compresses the pulse length. Some synchrotron-based proposals achieve the desired beam power by combining two or more synchrotrons of the same energy, and others propose a combination of lower and higher energy synchrotrons. This paper presents the rationale for using RCS technology, and a discussion of the advantages and disadvantages of synchrotron-based spallation sources.

Cho, Y.

1998-07-01

84

DPA calculation for Japanese spallation neutron source  

NASA Astrophysics Data System (ADS)

A neutron generating target and surrounding components, such as moderators and proton-beam windows, of intense pulsed spallation sources suffer serious radiation damage. In order to construct a maintenance scenario of the Japanese Spallation Neutron Source, the life estimation of those components due to the radiation damage becomes indispensable. For this purpose, we calculated DPA values of the important components, based on the calculation of displacement cross-sections using PHITS and NJOY codes with the LA150 library. Maximum DPA values at the end of 5000 MW h are 3.9 for the target vessel, 2.8 for the reflector and moderator vessels, and 0.4 for the proton-beam window. We also discuss the effect of the proton-beam profile and proton-energy dependence on the DPA values. Briefly, we showed the calculation result on the helium and hydrogen production.

Harada, M.; Watanabe, N.; Konno, C.; Meigo, S.; Ikeda, Y.; Niita, K.

2005-08-01

85

INJECTION CHOICE FOR SPALLATION NEUTRON SOURCE RING.  

SciTech Connect

Injection is key in the low-loss design of high-intensity proton facilities like the Spallation Neutron Source (SNS). During the design of both the accumulator and the rapid-cycling-synchrotron version of the SNS, extensive comparison has been made to select injection scenarios that satisfy SNS's low-loss design criteria. This paper presents issues and considerations pertaining to the final choice of the SNS injection systems.

WEI,J.; BEEBE-WANG,J.; BLASKIEWICZ,M.; BRODOWSKI,J.; FEDOTOV,A.; GARDNER,C.; LEE,Y.Y.; RAPARIA,D.; DANILOV,V.; HOLMES,J.; PRIOR,C.; REES,G.; MACHIDA,S.

2001-06-18

86

ARPS: an Advanced Radio Isotope Power Subsystem for ExoMars Geophysical Package (GEP)  

NASA Astrophysics Data System (ADS)

Within the framework of the ESA Aurora initiative , IPGP, DLR and an international consortium of laboratories launched an initiative aiming at adding on board the ExoMars mission a long life geophysical observatory, called "GEP" (Geophysical package) or "Mars Long Lived Surface Package". The feasibility study of this "geophysical package", carried out with the CNES support, showed the need for studying an alternative source of power to solar panels. Developments related to RTG technologies have been restricted for a long time to the United States and Russian industries. However, the exploration of the remote solar system (in the frame of the ESA Cosmic Vision) as well as long duration planetary missions (such as ExoMars Geophysical Package GEP ) exclude de facto the use of solar panels. A possible solution would be to associate to a radioisotope heat source of Russian origin (of Angel type) a thermo-electrical conversion system of European design. A European consortium of laboratories, including LPM, IPG and DLR (WF and RS) was thus constituted, in order to validate by a study the assumptions on the electric subsystem for the preliminary sizing of the geophysical package. The power of this Advanced radio-isotopic power system (ARPS) should be between 3 and 4 W, and the proposed mass limited to about 3 to 4 kg. This study will be undertaken in collaboration between the LPM, IPGP, DLR-WF and DLR-RS. A preliminary iteration of the GEP power subsystem will be presented, and main trade-off will be considered.

Mimoun, D.; Biele, J.; Lenoir, B.; Dauscher, A.; Müller, E.

2005-12-01

87

Production, distribution and applications of californium-252 neutron sources  

Microsoft Academic Search

The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person’s little finger can emit up to 1011 neutrons s?1. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and

R. C. Martin; J. B. Knauer; P. A. Balo

2000-01-01

88

Spallation-Driven Cold Neutron Sources Dr. Bradley J. Micklich  

E-print Network

Spallation-Driven Cold Neutron Sources Dr. Bradley J. Micklich Senior Physicist, Physics Division) to 60 Hz (SNS) ­ pulse length ­ subs (short pulse), 12 ms (long pulse), CW (SINQ) Neutron economy Cold Neutrons? Cold neutron production at the IPNS Ep = 450 MeV Ep = 50 MeV En = 5 meV (~25 collisions

McDonald, Kirk

89

Design and safety aspects of the Cornell cold neutron source  

Microsoft Academic Search

The cold neutron beam facility at the Cornell University TRIGA Mark II reactor will begin operational testing in early 1993. It is designed to provide a low background subthermal neutron beam that is as free as possible of fast neutrons and gamma rays for applied research and graduate-level instruction. The Cornell cold neutron source differs from the more conventional types

Carol G. Ouellet; David D. Clark

1992-01-01

90

Initial characterization of the Cornell Cold Neutron Source  

Microsoft Academic Search

A device to moderate reactor spectrum neutrons to subthermal energies and filter out photons and higher energy neutrons has been designed, constructed and tested at Ward Laboratory, Cornell University. The Cornell Cold Neutron Source, which houses a chamber containing an organic moderator (mesitylene), the cryogenic cooling apparatus, and the first three one-meter long neutron guide elements, is physically inserted into

Stuart Alan Spern

1998-01-01

91

Advanced Neutron Source: Plant Design Requirements  

SciTech Connect

The Advanced Neutron Source will be a new world-class facility for research using hot, thermal, cold, and ultra-cold neutrons. The heart of the facility will be a 330-MW (fission), heavy-water cooled and heavy-water moderated reactor. The reactor will be housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides will fan out into a large guide hall, housing about 30 neutron research stations. Appropriate office, laboratory, and shop facilities will be included to provide a complete facility for users. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory early in the next decade. This PDR document defines the plant-level requirements for the design, construction, and operation of ANS. It also defines and provides input to the individual System Design Description (SDD) documents. Together, this PDR document and the set of SDD documents will define and control the baseline configuration of ANS.

Not Available

1990-07-01

92

Accelerator neutron sources for neutron capture therapy using near-threshold charged particle reactions  

Microsoft Academic Search

Compact neutron sources for neutron capture therapy hold the promise of permitting wide availability for this therapeutic modality for cancer treatment. Most accelerator based neutron source concepts for this purpose are centered on (p,n) reactions using bombarding energies several hundred keV to 1-2 MeV above the reaction threshold producing high neutron yield. The neutron energies in the range of hundreds

Yale D. Harker; Frank Harmon; James Seamans; Scott Serrano; William Trammell; Luther Yost; Xiao-Lin Zhou; Robert W. Hamm

1997-01-01

93

Study of neutron focusing at the Texas Cold Neutron Source. Final report  

Microsoft Academic Search

Funds were received for the first year of a three year DOE Nuclear Engineering Research Grant, ``Study of Neutron Focusing at the Texas Cold Neutron Source`` (FGO2-92ER75711). The purpose of this three year study was to develop a neutron focusing system to be used with the Texas Cold Neutron Source (TCNS) to produce an intense beam of neutrons. A prompt

B. W. Wehring; K. Uenlue

1995-01-01

94

Thermal-hydraulic studies of the Advanced Neutron Source cold source  

Microsoft Academic Search

The Advanced Neutron Source (ANS), in its conceptual design phase at Oak Ridge National Laboratory, was to be a user-oriented neutron research facility producing the most intense steady-state flux of thermal and cold neutrons in the world. Among its many scientific applications, the production of cold neutrons was a significant research mission for the ANS. The cold neutrons come from

P. T. Williams; A. T. Lucas

1995-01-01

95

Inertial electro-magnetostatic plasma neutron sources  

SciTech Connect

Two types of systems are being studied experimentally as D-T plasma neutron sources. In both concepts, spherical convergence of either electrons or ions or both is used to produce a dense central focus within which D-T fusion reactions produce 14 MeV neutrons. One concept uses nonneutral plasma confinement principles in a Penning type trap. In this approach, combined electrostatic and magnetic fields provide a vacuum potential well within which electrons are confined and focused. A small (6 mm radius) spherical machine has demonstrated a focus of 30 {micro}m radius, with a central density of up to 35 times the Brillouin density limit of a static trap. The resulting electron plasma of up to several 10{sup 13} cm{sup {minus}3} provides a multi-kV electrostatic well for confining thermonuclear ions as a neutron source. The second concept (Inertial Electrostatic Confinement, or IEC) uses a high-transparence grid to form a global well for acceleration and confinement of ions. Such a system has demonstrated steady neutron output of 2 {times} 10{sup 10} s{sup {minus}1}. The present experiment will scale this to >10{sup 11} s{sup {minus}1}. Advanced designs based on each concept have been developed recently. In these proposed approaches, a uniform-density electron sphere forms an electrostatic well for ions. Ions so trapped may be focused by spherical convergence to produce a dense core. An alternative approach produces large amplitude spherical oscillations of a confined ion cloud by a small, resonant modulation of the background electrons. In both the advanced Penning trap approach and the advanced IEC approach, the electrons are magnetically insulated from a large (up to 100 kV) applied electrostatic field. The physics of these devices is discussed, experimental design details are given, present observations are analyzed theoretically, and the performance of future advanced systems are predicted.

Barnes, D.C.; Nebel, R.A.; Schauer, M.M.; Pickrel, M.M. [Los Alamos National Lab., NM (United States)

1997-12-31

96

Superfluid-helium Ultracold Neutron Sources: Concepts for the European Spallation Source?  

NASA Astrophysics Data System (ADS)

Production of ultracold neutrons by conversion of cold neutrons in superfluid helium can be implemented in several ways, with the converter located either “in-pile” close to the core of a nuclear reactor or closely coupled to a neutron spallation source, or at the end of a neutron guide. This paper shall contribute to a discussion about source concepts for the ESS.

Zimmer, Oliver

97

The status of the spallation neutron source ion source  

SciTech Connect

The ion source for the spallation neutron source (SNS) is a radio-frequency, multicusp source designed to deliver 45 mA of H2 to the SNS accelerator with a pulse length of 1 ms and repetition rate of 60 Hz. A total of three ion sources have been fabricated and commissioned at Lawrence Berkeley National Laboratory and subsequently delivered to the SNS at the Oak Ridge National Laboratory. The ion sources are currently being rotated between operation on the SNS accelerator, where they are involved in ongoing efforts to commission the SNS LINAC, and the hot spare stand (HSS), where high-current tests are in progress. Commissioning work involves operating the source in a low duty-factor mode (pulse width {approx}200 ms and repetition rate {approx}5 Hz) for extended periods of time while the high-current tests involve source operation at full duty-factor of 6 percent (1 ms/60 Hz). This report discusses routine performance of the source employed in the commissioning role as well as the initial results o f high-current tests performed on the HSS.

Welton, R.F.; Stockli, M.P.; Murray, S.N.; Keller, R.

2003-09-11

98

New sources and instrumentation for neutrons in biology  

PubMed Central

Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed. PMID:19132140

Teixeira, S.C.M.; Ankner, J.; Bellissent-Funel, M.C.; Bewley, R.; Blakeley, M.P.; Coates, L.; Dahint, R.; Dalgliesh, R.; Dencher, N.; Dhont, J.; Fischer, P.; Forsyth, V.T.; Fragneto, G.; Frick, B.; Geue, T.; Gilles, R.; Gutberlet, T.; Haertlein, M.; Hauß, T.; Häußler, W.; Heller, W.T.; Herwig, K.; Holderer, O.; Juranyi, F.; Kampmann, R.; Knott, R.; Kohlbrecher, J.; Kreuger, S.; Langan, P.; Lechner, R.; Lynn, G.; Majkrzak, C.; May, R.; Meilleur, F.; Mo, Y.; Mortensen, K.; Myles, D.A.A.; Natali, F.; Neylon, C.; Niimura, N.; Ollivier, J.; Ostermann, A.; Peters, J.; Pieper, J.; Rühm, A.; Schwahn, D.; Shibata, K.; Soper, A.K.; Straessle, T.; Suzuki, U.-i.; Tanaka, I.; Tehei, M.; Timmins, P.; Torikai, N.; Unruh, T.; Urban, V.; Vavrin, R.; Weiss, K.; Zaccai, G.

2008-01-01

99

Converging neutron guide for neutron focusing at the Texas Cold Neutron Source  

SciTech Connect

We have thoroughly investigated the design and construction of a neutron focusing system for use with the Texas Cold Neutron Source (TCNS). The focusing system will be located at the end of the TCNS curved neutron guide to increase the neutron flux for neutron capture experiments that benefit from the low background expected at the end of the curved guide. An example of such an experiment, and one we plan to set up, is prompt gamma activation analysis, a nondestructive nuclear analytical technique based on spectroscopy of neutron capture gamma rays. After examining several methods for neutron focusing, we decided to design a converging neutron guide for use as a focusing system. Different multielement converging guides were designed and analyzed. Each consisted of a number of truncated rectangular cone sections. From the results of our study, we will select one of these guides for construction. Since the cost is expected to be quite high, the decision will be based on a cost-benefit argument.

Kim, J.Y.; Wehring, B.W.; Uenlue, K. (Univ. of Texas, Austin, TX (United States))

1993-01-01

100

Neutron dosimetry for a general 252Cf brachytherapy source.  

PubMed

This paper extends previous work to characterize neutron dosimetry in the vicinity of 252Cf brachytherapy sources. A general source is examined with an arbitrary length, diameter, and encapsulation using Monte Carlo methods. Fast neutron dosimetry and thermal neutron fluence rates were determined in a variety of clinically relevant media of varying dimensions. Applicator Tube, point source, high dose rate VariSource, and high dose rate muSelectron source geometries were analyzed. Fast neutron dosimetry was relatively independent of encapsulation thickness for an assortment of encapsulation materials less than 2 mm thick. Large variations in phantom size made minimal differences in the fast neutron dose close to the source. Specific source geometries were compared with dosimetry obtained from a simplified point model. The consequence of these results is a convenient means of accurately predicting clinical fast neutron dosimetry characteristics around a general 252Cf brachytherapy source in a variety of media without requiring neutron transport. Thermal neutron fluence rates were determined for a variety of source encapsulation materials, encapsulation thicknesses, and phantom sizes. At a distance of 3 cm from the source center, the thermal neutron fluence rate for a 30 cm diameter phantom was a 2.65 times greater than for a 10 cm diameter water phantom. These results demonstrate 252Cf thermal neutron fluence rate is relatively independent of encapsulation thickness and composition, yet highly dependent on hydrogen mass density and phantom size for phanta with diameters <30 cm. PMID:11190964

Rivard, M J

2000-12-01

101

Neutronic conceptual design of the ETRR-2 cold-neutron source using the MCNP code  

Microsoft Academic Search

A conceptual neutronic design of the cold-neutron source (CNS) for the Egyptian second research reactor (ETRR-2) was done using the MCNP code. Parametric analysis to chose the type and geometry of the moderator, and the required CNS dimensions to maximize the cold neutron production was performed. The moderator cell has a spherical annulus structure containing liquid hydrogen. The cold neutron

M. Y. Khalil; M. K. Shaat; A. Y. Abdelfattah

2005-01-01

102

Study of neutron focusing at the Texas Cold Neutron Source. Final report  

Microsoft Academic Search

The goals of this three-year study were: (1) design a neutron focusing system for use with the Texas Cold Neutron Source (TCNS) to produce an intense beam of cold neutrons appropriate for prompt gamma activation analysis (PGAA); (2) orchestrate the construction of the focusing system, integrate it into the TCNS neutron guide complex, and measure its performance; and (3) design,

B. W. Wehring; K. Uenlue

1996-01-01

103

SANS at Pulsed Neutron Sources: Present and Future Prospects  

Microsoft Academic Search

Small-angle diffraction with a pulsed neutron source, using time-of-flight analysis to separate neutrons of different wavelengths, offers a very wide simultaneous Q range coupled to good Q resolution. Data reduction to allow for wavelength-dependent effects may be achieved as a matter of routine. The cold neutron flux available from accelerator-based neutron sources does not yet fully match that of the

R. K. Heenan; J. Penfold; S. M. King

1997-01-01

104

Absolute determination of the neutron source yield using melamine as a neutron detector  

NASA Astrophysics Data System (ADS)

A new approach to absolute determination of the neutron source yield is presented. It bases on the application of melamine (C3H6N6) to neutron detection combined with Monte Carlo simulations of neutron transport. Melamine has the ability to detect neutrons via 14N(n, p)14C reaction and subsequent determination of 14C content. A cross section for this reaction is relatively high for thermal neutrons (1.827 b) and much lower for fast neutrons. A concentration of 14C nuclei created in the irradiated sample of melamine can be reliably measured with the aid of the accelerator mass spectrometry (AMS). The mass of melamine sufficient for this analysis is only 10 mg. Neutron detection is supported by Monte Carlo simulations of neutron transport carried out with the use of MCNP-4C code. These simulations are aimed at computing the probability of 14C creation in the melamine sample per the source neutron. The result of AMS measurements together with results of MCNP calculations enable us to determine the number of neutrons emitted from the source during the irradiation of melamine. The proposed method was applied for determining the neutron emission from a commercial 252Cf neutron source which was independently calibrated. The measured neutron emission agreed with the certified one within uncertainty limits. The relative expanded uncertainty (k=2) of the absolute neutron source yield determination was estimated at 2.6%. Apart from calibration of radionuclide neutron sources the proposed procedure could facilitate absolute yield measurements for more complex sources. Potential applications of this methodology as it is further developed include diagnostics of inertial confinement fusion and plasma-focus experiments, calibration of neutron measurement systems at tokamaks and accelerator-based neutron sources as well as characterization of neutron fields generated in large particle detectors during collisions of hadron beams.

Ciechanowski, M.; Bolewski, A., Jr.; Kreft, A.

2015-01-01

105

The National Spallation Neutron Source Collaboration: Towards a new pulsed neutron source in the United States  

Microsoft Academic Search

The US Department of Energy has commissioned Oak Ridge National Laboratory to initiate the conceptual design for a next-generation pulsed spallation neutron source. Current expectation is for a construction start in FY 1998, with commencement of operations in 2004. For this project, ORNL has entered into a collaborative arrangement with LBNL, BNL, LANL (and most recently ANL). The conceptual design

B. R. Appleton; J. B. Ball; J. R. Alonso; R. A. Gough; W. T. Weng; A. Jason

1996-01-01

106

The advanced neutron source: A new reactor-based facility for neutron research  

Microsoft Academic Search

The advanced neutron source (ANS) is a new reactor-based research facility planned to meet the need for an intense steady-state source of neutrons, associated instruments, and experimental space. As a user facility, the ANS will be open for use by scientists from universities, industry, and federal laboratories. The scientific case for the new facility and the major requirements (the neutron

1990-01-01

107

Development of an ultra cold neutron source at MLNSC  

Microsoft Academic Search

Ultra Cold Neutrons (UCN) can be produced at spallation sources using a variety of techniques. To date the technique used has been to Bragg scatter and Doppler shift cold neutrons into UCN from a moving crystal. This is particularly applicable to short-pulse spallation sources. We are presently constructing a UCN source at LANSCE using this method. In addition, large gains

S. J. Seestrom; T. J. Bowles; R. Hill; G. L. Greene; C. L. Morris

1996-01-01

108

Development of an ultra-cold neutron source at MLNSC  

Microsoft Academic Search

Ultra Cold Neutrons (UCN) can be produced at spallation sources using a variety of techniques. To date the technique used has ben to Bragg scatter and Doppler shift cold neutrons into UCN from a moving crystal. This is particularly applicable to short-pulse spallation sources. We are presently constructing a UCN source at LANSCE using this method.In addition, large gains in

Susan J. Seestrom; T. J. Bowles; R. Hill; G. L. Greene; Chris L. Morris

1997-01-01

109

Plans for an Ultra Cold Neutron source at Los Alamos  

Microsoft Academic Search

Ultra Cold Neutrons (UCN) can be produced at spallation sources using a variety of techniques. To date the technique used has been to Bragg scatter and Doppler shift cold neutrons into UCN from a moving crystal. This is particularly applicable to short-pulse spallation sources. We are presently constructing a UCN source at LANSCE using this method. In addition, large gains

S. J. Seestrom; T. J. Bowles; R. Hill; G. L. Greene

1996-01-01

110

rf improvements for Spallation Neutron Source H-ion source  

SciTech Connect

The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering 38 mA H beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride AlN plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier. 2010 American Institute of Physics.

Kang, Yoon W [ORNL; Fuja, Raymond E [ORNL; Goulding, Richard Howell [ORNL; Hardek, Thomas W [ORNL; Lee, Sung-Woo [ORNL; McCarthy, Mike [ORNL; Piller, Chip [ORNL; Shin, Ki [ORNL; Stockli, Martin P [ORNL; Welton, Robert F [ORNL

2010-01-01

111

An Experimental Study on Subcritical Assembly with Neutron Source  

Microsoft Academic Search

A new definition of Subcritical constants is introduced in this paper on the basis of the neutron balance equation. These Subcritical constants are obtained by integrating the intensity of the neutron flux over the whole volume of the Subcritical assembly with neutron source. Some other constants commonly used in conventional reactor physics can be predicted by analyzing the above mentioned

Yoshio MIYAWAKI

1968-01-01

112

HFIR cold neutron source moderator vessel design analysis  

SciTech Connect

A cold neutron source capsule made of aluminum alloy is to be installed and located at the tip of one of the neutron beam tubes of the High Flux Isotope Reactor. Cold hydrogen liquid of temperature approximately 20 degree Kelvin and 15 bars pressure is designed to flow through the aluminum capsule that serves to chill and to moderate the incoming neutrons produced from the reactor core. The cold and low energy neutrons thus produced will be used as cold neutron sources for the diffraction experiments. The structural design calculation for the aluminum capsule is reported in this paper.

Chang, S.J.

1998-04-01

113

H- radio frequency source development at the Spallation Neutron Source.  

PubMed

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent ?38 mA peak current in the linac and an availability of ?90%. H(-) beam pulses (?1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, ?60 kW) of a copper antenna that has been encased with a thickness of ?0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of ?99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of ?75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance?installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to ?100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence. PMID:22380234

Welton, R F; Dudnikov, V G; Gawne, K R; Han, B X; Murray, S N; Pennisi, T R; Roseberry, R T; Santana, M; Stockli, M P; Turvey, M W

2012-02-01

114

H- radio frequency source development at the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of {approx}75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to {approx}100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

Welton, Robert F [ORNL; Pennisi, Terry R [ORNL; Roseberry, Ron T [ORNL; Stockli, Martin P [ORNL

2012-01-01

115

The Spallation Neutron Source accelerator system design  

NASA Astrophysics Data System (ADS)

The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.

Henderson, S.; Abraham, W.; Aleksandrov, A.; Allen, C.; Alonso, J.; Anderson, D.; Arenius, D.; Arthur, T.; Assadi, S.; Ayers, J.; Bach, P.; Badea, V.; Battle, R.; Beebe-Wang, J.; Bergmann, B.; Bernardin, J.; Bhatia, T.; Billen, J.; Birke, T.; Bjorklund, E.; Blaskiewicz, M.; Blind, B.; Blokland, W.; Bookwalter, V.; Borovina, D.; Bowling, S.; Bradley, J.; Brantley, C.; Brennan, J.; Brodowski, J.; Brown, S.; Brown, R.; Bruce, D.; Bultman, N.; Cameron, P.; Campisi, I.; Casagrande, F.; Catalan-Lasheras, N.; Champion, M.; Champion, M.; Chen, Z.; Cheng, D.; Cho, Y.; Christensen, K.; Chu, C.; Cleaves, J.; Connolly, R.; Cote, T.; Cousineau, S.; Crandall, K.; Creel, J.; Crofford, M.; Cull, P.; Cutler, R.; Dabney, R.; Dalesio, L.; Daly, E.; Damm, R.; Danilov, V.; Davino, D.; Davis, K.; Dawson, C.; Day, L.; Deibele, C.; Delayen, J.; DeLong, J.; Demello, A.; DeVan, W.; Digennaro, R.; Dixon, K.; Dodson, G.; Doleans, M.; Doolittle, L.; Doss, J.; Drury, M.; Elliot, T.; Ellis, S.; Error, J.; Fazekas, J.; Fedotov, A.; Feng, P.; Fischer, J.; Fox, W.; Fuja, R.; Funk, W.; Galambos, J.; Ganni, V.; Garnett, R.; Geng, X.; Gentzlinger, R.; Giannella, M.; Gibson, P.; Gillis, R.; Gioia, J.; Gordon, J.; Gough, R.; Greer, J.; Gregory, W.; Gribble, R.; Grice, W.; Gurd, D.; Gurd, P.; Guthrie, A.; Hahn, H.; Hardek, T.; Hardekopf, R.; Harrison, J.; Hatfield, D.; He, P.; Hechler, M.; Heistermann, F.; Helus, S.; Hiatt, T.; Hicks, S.; Hill, J.; Hill, J.; Hoff, L.; Hoff, M.; Hogan, J.; Holding, M.; Holik, P.; Holmes, J.; Holtkamp, N.; Hovater, C.; Howell, M.; Hseuh, H.; Huhn, A.; Hunter, T.; Ilg, T.; Jackson, J.; Jain, A.; Jason, A.; Jeon, D.; Johnson, G.; Jones, A.; Joseph, S.; Justice, A.; Kang, Y.; Kasemir, K.; Keller, R.; Kersevan, R.; Kerstiens, D.; Kesselman, M.; Kim, S.; Kneisel, P.; Kravchuk, L.; Kuneli, T.; Kurennoy, S.; Kustom, R.; Kwon, S.; Ladd, P.; Lambiase, R.; Lee, Y. Y.; Leitner, M.; Leung, K.-N.; Lewis, S.; Liaw, C.; Lionberger, C.; Lo, C. C.; Long, C.; Ludewig, H.; Ludvig, J.; Luft, P.; Lynch, M.; Ma, H.; MacGill, R.; Macha, K.; Madre, B.; Mahler, G.; Mahoney, K.; Maines, J.; Mammosser, J.; Mann, T.; Marneris, I.; Marroquin, P.; Martineau, R.; Matsumoto, K.; McCarthy, M.; McChesney, C.; McGahern, W.; McGehee, P.; Meng, W.; Merz, B.; Meyer, R.; Meyer, R.; Miller, B.; Mitchell, R.; Mize, J.; Monroy, M.; Munro, J.; Murdoch, G.; Musson, J.; Nath, S.; Nelson, R.; Nelson, R.; O'Hara, J.; Olsen, D.; Oren, W.; Oshatz, D.; Owens, T.; Pai, C.; Papaphilippou, I.; Patterson, N.; Patterson, J.; Pearson, C.; Pelaia, T.; Pieck, M.; Piller, C.; Plawski, T.; Plum, M.; Pogge, J.; Power, J.; Powers, T.; Preble, J.; Prokop, M.; Pruyn, J.; Purcell, D.; Rank, J.; Raparia, D.; Ratti, A.; Reass, W.; Reece, K.; Rees, D.; Regan, A.; Regis, M.; Reijonen, J.; Rej, D.; Richards, D.; Richied, D.; Rode, C.; Rodriguez, W.; Rodriguez, M.; Rohlev, A.; Rose, C.; Roseberry, T.; Rowton, L.; Roybal, W.; Rust, K.; Salazer, G.; Sandberg, J.; Saunders, J.; Schenkel, T.; Schneider, W.; Schrage, D.; Schubert, J.; Severino, F.; Shafer, R.; Shea, T.; Shishlo, A.; Shoaee, H.; Sibley, C.; Sims, J.; Smee, S.; Smith, J.; Smith, K.; Spitz, R.; Staples, J.; Stein, P.; Stettler, M.; Stirbet, M.; Stockli, M.; Stone, W.; Stout, D.; Stovall, J.; Strelo, W.; Strong, H.; Sundelin, R.; Syversrud, D.; Szajbler, M.; Takeda, H.; Tallerico, P.; Tang, J.; Tanke, E.; Tepikian, S.; Thomae, R.; Thompson, D.; Thomson, D.; Thuot, M.; Treml, C.; Tsoupas, N.; Tuozzolo, J.; Tuzel, W.; Vassioutchenko, A.; Virostek, S.; Wallig, J.; Wanderer, P.; Wang, Y.; Wang, J. G.; Wangler, T.; Warren, D.; Wei, J.; Weiss, D.; Welton, R.; Weng, J.; Weng, W.-T.; Wezensky, M.; White, M.; Whitlatch, T.; Williams, D.; Williams, E.; Wilson, K.; Wiseman, M.; Wood, R.; Wright, P.; Wu, A.; Ybarrolaza, N.; Young, K.; Young, L.; Yourd, R.; Zachoszcz, A.; Zaltsman, A.; Zhang, S.; Zhang, W.; Zhang, Y.; Zhukov, A.

2014-11-01

116

SPALLATION NEUTRON SOURCE BEAM CURRENT MONITOR ELECTRONICS.  

SciTech Connect

The Spallation Neutron Source (SNS) to be constructed at ORNL is a collaboration of six laboratories. Beam current monitors for SNS will be used to monitor H-minus and H-plus beams ranging from the 15 mA (tune-up in the Front End and Linac) to over 60 A fully accumulated in the Ring. The time structure of the beams to be measured range from 645 nsec ''mini'' bunches, at the 1.05 MHz ring revolution rate, to an overall 1 mS long macro pulse. Beam current monitors (BCMs) for SNS have requirements depending upon their location within the system. The development of a general approach to satisfy requirements of various locations with common components is a major design objective. This paper will describe the development of the beam current monitors and electronics.

KESSELMAN, M.

2001-06-18

117

Shielding Ddsign and analyses of 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. An electron accelerator drives a sub-critical facility (ADS) is used for generating the neutron source. The facility will be utilized for performing basic and applied nuclear researches, producing medical isotopes, and training young nuclear specialists. Monte Carlo code MCNPX has been utilized as the major design tool for the design, due to its capability to transport electrons, photons, and neutrons at high energies. However the ADS shielding calculations with MCNPX need enormous computational resources and the small neutron yield per electron makes sampling difficulty for the Monte Carlo calculations. The high energy electrons (E > 100 MeV) generate very high energy neutrons and these neutrons dominant the total radiation dose outside the shield. The radiation dose caused by high energy neutrons is {approx}3-4 orders of magnitude higher than that of the photons. However, the high energy neutron fraction within the total generated neutrons is very small, which increases the sampling difficulty and the required computational time. To solve these difficulties, the user subroutines of MCNPX are utilized to generate a neutron source file, which record the generated neutrons from the photonuclear reactions caused by electrons. This neutron source file is utilized many times in the following MCNPX calculations for weight windows (importance function) generation and radiation dose calculations. In addition, the neutron source file can be sampled multiple times to improve the statistics of the calculated results. In this way the expensive electron transport calculations can be performed once with good statistics for the different ADS shielding problems. This paper presents the method of generating and utilizing the neutron source file by MCNPX for the ADS shielding calculation and similar accelerator facilities, and the accurate radiation dose analyses outside the shield using modest computational resources.

Zhong, Z.; Gohar, Y. (Nuclear Engineering Division)

2011-01-01

118

Electronic neutron sources for compensated porosity well logging  

NASA Astrophysics Data System (ADS)

The viability of replacing Americium-Beryllium (Am-Be) radiological neutron sources in compensated porosity nuclear well logging tools with D-T or D-D accelerator-driven neutron sources is explored. The analysis consisted of developing a model for a typical well-logging borehole configuration and computing the helium-3 detector response to varying formation porosities using three different neutron sources (Am-Be, D-D, and D-T). The results indicate that, when normalized to the same source intensity, the use of a D-D neutron source has greater sensitivity for measuring the formation porosity than either an Am-Be or D-T source. The results of the study provide operational requirements that enable compensated porosity well logging with a compact, low power D-D neutron generator, which the current state-of-the-art indicates is technically achievable.

Chen, A. X.; Antolak, A. J.; Leung, K.-N.

2012-08-01

119

Production, distribution and applications of californium-252 neutron sources.  

PubMed

The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 10(11) neutrons s(-1). Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordinance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations. PMID:11003521

Martin, R C; Knauer, J B; Balo, P A

2000-01-01

120

Materials Selection for the HFIR Cold Neutron Source  

Microsoft Academic Search

In year 2002 the High Flux Isotope Reactor (HFIR) will be fitted with a source of cold neutrons to upgrade and expand its existing neutron scattering facilities. The in-reactor components of the new source consist of a moderator vessel containing supercritical hydrogen gas moderator at a temperature of 20K and pressure of 15 bar, and a surrounding vacuum vessel. They

2001-01-01

121

The virtue of cold neutrons on pulsed sources  

Microsoft Academic Search

The widely-held view that pulsed sources and reactors are complementary, the former producing epithermal neutrons and the latter cold neutrons, has been shown in recent years to be an oversimplification. The concept of complementarity, if in fact it exists, is one of methods rather than of sources, frequently allowing similar scientific topics to be examined in refreshingly different ways. As

C. J. Carlile; J. Penfold

1995-01-01

122

Diffusion theory model for optimization calculations of cold neutron sources  

Microsoft Academic Search

Cold neutron sources are becoming increasingly important and common experimental facilities made available at many research reactors around the world due to the high utility of cold neutrons in scattering experiments. The authors describe a simple two-group diffusion model of an infinite slab LDâ cold source. The simplicity of the model permits to obtain an analytical solution from which one

Azmy

1987-01-01

123

Upgraded ultracold neutron facility with a supermirror turbine coupled to a very cold neutron source  

Microsoft Academic Search

An ultracold neutron (UCN) facility with the combination of a very cold neutron (VCN) source and a supermirror neutron turbine has been constructed in the Kyoto University Reactor. The present supermirror turbine was upgraded by changing the reflecting blades from the three-mirror sets to the five-mirror sets. The upgraded version enhances the UCN flux by a factor of about 3

Y. Kawabata; M. Utsuro; K. Okumura

1995-01-01

124

Study of neutron focusing at the Texas Cold Neutron Source: Progress report  

Microsoft Academic Search

The purpose of this three year study is to develop a neutron focusing system to be used with the Texas Cold Neutron Source (TCNS) to produce an intense beam of neutrons. A prompt gamma activation analysis (PGAA) facility will also be designed, setup, and tested under this DOE grant. During the first year of the DOE grant, a new procedure

B. W. Wehring; K. Uenlue

1993-01-01

125

Production, Distribution, and Applications of Californium-252 Neutron Sources  

SciTech Connect

The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-year half-life. A source the size of a person's little finger can emit up to 10{sup 11} neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6- year half-life. A source the size of a person's little finger can emit up to 10 neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory(ORNL). DOE sells {sup 252}Cf to commercial reencapsulators domestically and internationally. Sealed {sup 252}Cf sources are also available for loan to agencies and subcontractors of the U.S. government and to universities for educational, research, and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of {sup 252}Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments, and irradiation of rice to induce genetic mutations.

Balo, P.A.; Knauer, J.B.; Martin, R.C.

1999-10-03

126

Neutronic study of spherical cold-neutron sources composed of liquid hydrogen and liquid deuterium  

NASA Astrophysics Data System (ADS)

Using the cross-section model for neutron scattering in liquid H 2 and D 2, a neutron transport analysis is performed for spherical cold-neutron sources composed of either para H 2, normal H 2 or normal D 2. A special effort is made to generate a set of energy-averaged cross-sections (80 group constants between 0.1 ?eV and 10 eV) for liquid H 2 and D 2 at melting and boiling points. A number of conclusions on the spherical cold-neutron source configurations are drawn. It is especially shown that the highest cold-neutron flux is obtainable from the normal D 2 source with a radius of about 50 cm, while the normal- and para-H 2 sources with radii around 3- 4 cm produce maximum cold-neutron fluxes at the center.

Matsuo, Y.; Morishima, N.; Nagaya, Y.

2003-01-01

127

Superthermal Source of Ultracold Neutrons for Fundamental Physics Experiments  

SciTech Connect

Ultracold neutrons (UCNs) play an important role for precise measurements of the properties of the neutron and its interactions. During the past 25 years, a neutron turbine coupled to a liquid deuterium cold neutron source at a high-flux reactor has defined the state of the art for UCN production, despite a long history of efforts towards a new generation of UCN sources. This Letter reports a world-best UCN density available for users, achieved with a new source based on conversion of cold neutrons in superfluid helium. A conversion volume of 5 liters provides at least 274 000 UCN in a single accumulation run. Cyclically repeated operation of the source has been demonstrated, as well.

Zimmer, Oliver; Piegsa, Florian M.; Ivanov, Sergey N. [Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France)

2011-09-23

128

76 FR 76327 - Installation of Radiation Alarms for Rooms Housing Neutron Sources  

Federal Register 2010, 2011, 2012, 2013

...of Radiation Alarms for Rooms Housing Neutron Sources AGENCY: Nuclear Regulatory Commission...installation of radiation alarms in rooms housing neutron sources. DATES: Submit comments by February...Hamawy is concerned about the security of neutron sources. III. Petition The...

2011-12-07

129

78 FR 21567 - Installation of Radiation Alarms for Rooms Housing Neutron Sources  

Federal Register 2010, 2011, 2012, 2013

...of Radiation Alarms for Rooms Housing Neutron Sources AGENCY: Nuclear Regulatory Commission...of radiation alarms for rooms housing neutron sources. DATES: The docket for the petition...of radiation alarms for rooms housing neutron sources. The petitioner stated that...

2013-04-11

130

Advanced Neutron Source (ANS) Project Progress report, FY 1991  

SciTech Connect

This report discusses the following about the Advanced Neutron Source: Project Management; Research and Development; Fuel Development; Corrosion Loop Tests and Analyses; Thermal-Hydraulic Loop Tests; Reactor Control and Shutdown Concepts; Critical and Subcritical Experiments; Material Data, Structural Tests, and Analysis; Cold-Source Development; Beam Tube, Guide, and Instrument Development; Hot-Source Development; Neutron Transport and Shielding; I C Research and Development; Design; and Safety.

Campbell, J.H. (ed.) (Oak Ridge National Lab., TN (United States)); Selby, D.L.; Harrington, R.M. (Oak Ridge National Lab., TN (United States)); Thompson, P.B. (Martin Marietta Energy Systems, Inc., (United States). Engineering Division)

1992-01-01

131

Advanced Neutron Source (ANS) Project Progress report, FY 1991  

SciTech Connect

This report discusses the following about the Advanced Neutron Source: Project Management; Research and Development; Fuel Development; Corrosion Loop Tests and Analyses; Thermal-Hydraulic Loop Tests; Reactor Control and Shutdown Concepts; Critical and Subcritical Experiments; Material Data, Structural Tests, and Analysis; Cold-Source Development; Beam Tube, Guide, and Instrument Development; Hot-Source Development; Neutron Transport and Shielding; I & C Research and Development; Design; and Safety.

Campbell, J.H. [ed.] [Oak Ridge National Lab., TN (United States); Selby, D.L.; Harrington, R.M. [Oak Ridge National Lab., TN (United States); Thompson, P.B. [Martin Marietta Energy Systems, Inc., (United States). Engineering Division

1992-01-01

132

A Dipole Assisted IEC Neutron Source  

SciTech Connect

A potential opportunity to enhance Inertial Electrostatic Confinement (IEC) fusion exists by augmenting it with a magnetic dipole configuration. The theory is that the dipole fields will enhance the plasma density in the center region of the IEC and the combined IEC and dipole confinement properties will reduce plasma losses. To demonstrate that a hybrid Dipole-IEC configuration can provide an improved neutron source vs. a stand alone IEC, a first model Dipole-IEC experiment was benchmarked against a reference IEC. A triple Langmuir probe was used to find the electron temperature and density. It was found that the magnetic field increases the electron density by a factor of 16, the electron temperature decreases in the presence of a magnetic field, the discharge voltage decreases in the presence of a magnetic field, the potential of the dipole strongly influences the densities obtained in the center. The experimental set-up and plasma diagnostics are discussed in detail, as well as the results, and the developmental issues.

Prajakti Joshi Shrestha

2005-11-28

133

Microtron MT 25 as a source of neutrons  

NASA Astrophysics Data System (ADS)

The objective was to describe Microtron MT25 as a source of neutrons generated by bremsstrahlung induced photonuclear reactions in U and Pb targets. Bremsstrahlung photons were produced by electrons accelerated at energy 21.6 MeV. Spectral fluence of the generated neutrons was calculated with MCNPX code and then experimentally determined at two positions by means of a Bonner spheres spectrometer in which the detector of thermal neutrons was replaced by activation Mn tablets or track detectors CR-39 with a 10B radiator. The measured neutron spectral fluence and the calculated anisotropy served for the estimation of neutron yield from the targets and for the determination of ambient dose equivalent rate at the place of measurement. Microtron MT25 is intended as one of the sources for testing neutron sensitive devices which will be sent into the space.

Králík, M.; Šolc, J.; Chvátil, D.; Krist, P.; Turek, K.; Granja, C.

2012-08-01

134

Microtron MT 25 as a source of neutrons  

SciTech Connect

The objective was to describe Microtron MT25 as a source of neutrons generated by bremsstrahlung induced photonuclear reactions in U and Pb targets. Bremsstrahlung photons were produced by electrons accelerated at energy 21.6 MeV. Spectral fluence of the generated neutrons was calculated with MCNPX code and then experimentally determined at two positions by means of a Bonner spheres spectrometer in which the detector of thermal neutrons was replaced by activation Mn tablets or track detectors CR-39 with a {sup 10}B radiator. The measured neutron spectral fluence and the calculated anisotropy served for the estimation of neutron yield from the targets and for the determination of ambient dose equivalent rate at the place of measurement. Microtron MT25 is intended as one of the sources for testing neutron sensitive devices which will be sent into the space.

Kralik, M.; Solc, J. [Czech Metrology Institute, CZ-102 00 Prague 10 (Czech Republic); Chvatil, D.; Krist, P.; Turek, K. [Nuclear Physics Institute, p.r.i., AS CR, CZ-250 68 Rez (Czech Republic); Granja, C. [Institute of Experimental and Applied Physics, Horska 3a/22, CZ-128 00 Prague 2 (Czech Republic)

2012-08-15

135

Dynamically Polarized Sample for Neutron Scattering At the Spallation Neutron Source  

SciTech Connect

The recently constructed Spallation Neutron Source at the Oak Ridge National Laboratory is quickly becoming the world s leader in neutron scattering sciences. In addition to the world s most intense pulsed neutron source, we are continuously constructing state of the art neutron scattering instruments as well as sample environments to address today and tomorrow s challenges in materials research. The Dynamically Polarized Sample project at the SNS is aimed at taking maximum advantage of polarized neutron scattering from polarized samples, especially biological samples that are abundant in hydrogen. Polarized neutron scattering will allow us drastically increase the signal to noise ratio in experiments such as neutron protein crystallography. The DPS project is near its completion and all key components have been tested. Here we report the current status of the project.

Pierce, Josh [ORNL] [ORNL; Crabb, Don [University of Virginia] [University of Virginia; Zhao, Jinkui [ORNL] [ORNL

2009-01-01

136

Satellite pulsed tiny neutron source at Kyoto University, Sakyo  

Microsoft Academic Search

A pulsed neutron source facility will be constructed at Kyoto University, where the accelerated 3.5MeV proton beam will bombard a Li or Be target to generate neutrons. The average current, the pulse width and the typical repetition rate are 100?A, 100?s and 70Hz, respectively. The purposes of the system are neutron imaging, material science, fundamental physics, etc. This kind of

Y. Iwashita; T. Nagae; T. Tanimori; H. Fujioka; H. M. Shimizu

2011-01-01

137

The National Spallation Neutron Source Collaboration: Towards a new pulsed neutron source in the United States  

SciTech Connect

The US Department of Energy has commissioned Oak Ridge National Laboratory to initiate the conceptual design for a next-generation pulsed spallation neutron source. Current expectation is for a construction start in FY 1998, with commencement of operations in 2004. For this project, ORNL has entered into a collaborative arrangement with LBNL, BNL, LANL (and most recently ANL). The conceptual design study is now well underway, building on the strong base of the extensive work already performed by various Laboratories, as well as input from the user community (from special BESAC subpanels). Study progress, including accelerator configuration and plans for resolution of critical issues, is reported in this paper.

Appleton, B.R.; Ball, J.B.; Alonso, J.R. [Oak Ridge National Lab., TN (United States); Gough, R.A. [Lawrence Berkeley National Lab., CA (United States); Weng, W.T. [Brookhaven National Lab., Upton, NY (United States); Jason, A. [Los Alamos National Lab., NM (United States); The National Spallation Neutron Source Collaboration

1996-07-01

138

Inertial electrostatic confinement I(IEC) neutron sources  

SciTech Connect

Inertial Electrostatic Confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron yields as high as 2*10 [10]. neutrons/sec in steady state. These systems have considerable potential as small, inexpensive, portable neutron sources for assaying applications. Neutron tomography is also a potential application. This paper discusses the IEC concept and how it can be adapted to a steady-state assaying source and an intense pulsed neutron source. Theoretical modeling and experimental results are presented.

Nebel, R.A.; Barnes, D.C.; Caramana, E.J.; Janssen, R.D.; Nystrom, W.D.; Tiouririne, T.N.; Trent, B.C. [Los Alamos National Lab., NM (United States); Miley, G.H.; Javedani, J. [Illinois Univ., Urbana, IL (United States)

1995-12-01

139

Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source  

SciTech Connect

The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 10{sup 7}. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays.

Andreani, C.; Pietropaolo, A.; Salsano, A. [Centro NAST, Universita degli Studi di Roma Tor Vergata (Italy); Gorini, G.; Tardocchi, M. [Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano-Bicocca (Italy); Paccagnella, A.; Gerardin, S. [Dipartimento di Ingegneria dell'Informazione, Universita di Padova (Italy); Frost, C. D.; Ansell, S. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Platt, S. P. [School of Computing, Engineering and Physical Sciences, University of Central Lancashire, Preston, Lancs. PR1 2HE (United Kingdom)

2008-03-17

140

Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source  

NASA Astrophysics Data System (ADS)

The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 107. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays.

Andreani, C.; Pietropaolo, A.; Salsano, A.; Gorini, G.; Tardocchi, M.; Paccagnella, A.; Gerardin, S.; Frost, C. D.; Ansell, S.; Platt, S. P.

2008-03-01

141

Materials compatibility studies for the Spallation Neutron Source  

Microsoft Academic Search

The Spallation Neutron Source (SNS) is a high power facility for producing neutrons that utilizes flowing liquid mercury inside an austenitic stainless steel container as the target for a 1.0 GeV proton beam. Type 316 SS has been selected as the container material for the mercury and consequences of exposure of 316 SS to radiation, thermal shock, thermal stress, cavitation

J. R. DiStefano; S. J. Pawel; E. T. Manneschmidt

1998-01-01

142

Experimental Neutron Source Facility Based on Accelerator Driven System  

Microsoft Academic Search

An experimental neutron source facility has been developed for producing medical isotopes, training young nuclear professionals, providing capability for performing reactor physics, material research, and basic science experiments. It uses a driven subcritical assembly with an electron accelerator. The neutrons driving the subcritical assembly were generated from the electron interactions with a target assembly. Tungsten or uranium target material is

Yousry Gohar

2010-01-01

143

HFIR cold neutron source moderator vessel design analysis  

Microsoft Academic Search

A cold neutron source capsule made of aluminum alloy is to be installed and located at the tip of one of the neutron beam tubes of the High Flux Isotope Reactor. Cold hydrogen liquid of temperature approximately 20 degree Kelvin and 15 bars pressure is designed to flow through the aluminum capsule that serves to chill and to moderate the

1998-01-01

144

High Flux Isotope Reactor cold neutron source reference design concept  

Microsoft Academic Search

In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron

D. L. Selby; A. T. Lucas; C. R. Hyman

1998-01-01

145

Performance of the Texas cold neutron source at reactor power  

Microsoft Academic Search

The Texas Cold Neutron Source (TCNS) was recently installed into the piercing beam port of the 1-MW TRIGA Mark II research reactor at the Nuclear Engineering Teaching Laboratory of the University of Texas at Austin. The TCNS system consists of a cooled moderator, a neon heat pipe, a cryogenic refrigerator, and a neutron guide. Design features of the TCNS, safety

K. Uenlue; C. Rios-Martinez; T. L. Bauer; B. W. Wehring

1993-01-01

146

Advanced Neutron Source radiological design criteria  

SciTech Connect

The operation of the proposed Advanced Neutron Source (ANS) facility will present a variety of radiological protection problems. Because it is desired to design and operate the ANS according to the applicable licensing standards of the Nuclear Regulatory Commission (NRC), it must be demonstrated that the ANS radiological design basis is consistent not only with state and Department of Energy (DOE) and other usual federal regulations, but also, so far as is practicable, with NRC regulations and with recommendations of such organizations as the Institute of Nuclear Power Operations (INPO) and the Electric Power Research Institute (EPRI). Also, the ANS radiological design basis is in general to be consistent with the recommendations of authoritative professional and scientific organizations, specifically the National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP). As regards radiological protection, the principal goals of DOE regulations and guidance are to keep occupational doses ALARA [as low as (is) reasonably achievable], given the current state of technology, costs, and operations requirements; to control and monitor contained and released radioactivity during normal operation to keep public doses and releases to the environment ALARA; and to limit doses to workers and the public during accident conditions. Meeting these general design objectives requires that principles of dose reduction and of radioactivity control by employed in the design, operation, modification, and decommissioning of the ANS. The purpose of this document is to provide basic radiological criteria for incorporating these principles into the design of the ANS. Operations, modification, and decommissioning will be covered only as they are affected by design.

Westbrook, J.L.

1995-08-01

147

Neutron producing target for accelerator based neutron source for  

E-print Network

therapy [1, 2]. Lithium targets for two modes of neutron beam production are developed. The first one disk 50 mm in diameter, 3 mm thick, is a proton beam absorber. It is cooled by liquid metal flowing on the disk, a proton beam is directed on it. Fig. 1. Stationary target before assembling. A system

Taskaev, Sergey Yur'evich

148

Cold neutron source at KAERI, Korea  

Microsoft Academic Search

The HANARO (High-flux Advance Neutron Application ReactOr), an open tank in a pool type multi-purpose research reactor, generating a high neutron flux (fast: 2.1×1014n\\/cm2\\/s, thermal flux: 5×1014n\\/cm2\\/s) has been operating at 30MWth since its first criticality in February 1995. The HANARO provides neutrons to various utilization and research groups for global competition. Based on the world-wide trend for an availability

Young Ki Kim; Kye Hong Lee; Hark Rho Kim

2008-01-01

149

Compact, energy EFFICIENT neutron source: enabling technology for various applications  

SciTech Connect

A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste.

Hershcovitch, A.; Roser, T.

2009-12-01

150

Spallation neutron source target station design, development, and commissioning  

NASA Astrophysics Data System (ADS)

The spallation neutron source target station is designed to safely, reliably, and efficiently convert a 1 GeV beam of protons to a high flux of about 1 meV neutrons that are available at 24 neutron scattering instrument beam lines. Research and development findings, design requirements, design description, initial checkout testing, and results from early operation with beam are discussed for each of the primary target subsystems, including the mercury target, neutron moderators and reflector, surrounding vessels and shielding, utilities, remote handling equipment, and instrumentation and controls. Future plans for the mercury target development program are also briefly discussed.

Haines, J. R.; McManamy, T. J.; Gabriel, T. A.; Battle, R. E.; Chipley, K. K.; Crabtree, J. A.; Jacobs, L. L.; Lousteau, D. C.; Rennich, M. J.; Riemer, B. W.

2014-11-01

151

Satellite pulsed tiny neutron source at Kyoto University, Sakyo  

NASA Astrophysics Data System (ADS)

A pulsed neutron source facility will be constructed at Kyoto University, where the accelerated 3.5 MeV proton beam will bombard a Li or Be target to generate neutrons. The average current, the pulse width and the typical repetition rate are 100 ?A, 100 ?s and 70 Hz, respectively. The purposes of the system are neutron imaging, material science, fundamental physics, etc. This kind of compact facility, which can be distributed at modest cost, will help to incubate new ideas and promote growth of neutron science worldwide.

Iwashita, Y.; Nagae, T.; Tanimori, T.; Fujioka, H.; Shimizu, H. M.

2011-04-01

152

Fission diamond detector tests at the ISIS spallation neutron source  

NASA Astrophysics Data System (ADS)

A compact device for monitoring of fast neutron fluxes is presented. The device is based on single crystal diamond obtained by the Chemical Vapor Deposition technique coupled to a uranium converter foil where neutron interaction results in emission of charged particles detected inside the diamond. Thermal and fast neutrons are detected using natural uranium containing both 235U and 238U. Biparametric (pulse height and time of flight) data collection was used at the ISIS pulsed neutron source to distinguish events from 235U, 238U and from carbon break-up reactions inside the diamond.

Rebai, M.; Andreani, C.; Fazzi, A.; Frost, C. D.; Giacomelli, L.; Gorini, G.; Milani, E.; Perelli Cippo, E.; Pietropaolo, A.; Prestopino, G.; Schooneveld, E.; Tardocchi, M.; Verona, C.; Verona Rinati, G.

2011-06-01

153

Calculated neutron dose rates for implantable californium-252 sources  

Microsoft Academic Search

Fast neutron absorbed dose rates near 252Cf finite line sources in several infinite tissue compositions have been calculated. The neutron flux produced by a point source was calculated using the one-dimensional energy-dependent discrete ordinates computer code, DTF-IV. The calculations utilized an S-16 angular quadrature approximation, 21 energy groups and anisotropic scattering up to the third order in the cosine of

J P Windham; A Shapiro; J G Kereiakes

1972-01-01

154

Initial thermal characterization of the Cornell cold neutron source  

Microsoft Academic Search

The completed full-scale Cornell cold neutron source, an integral component of the Cornell cold neutron beam facility, has undergone testing prior to its insertion (and consequent activation) in the Cornell 500-kW TRIGA reactor. The source consists of an organic moderator (mesitylene) contained within an aluminum chamber, which is cooled by conduction through a 99.999+ pure 1.90-cm-diam copper rod 267 cm

S. A. Spern; A. G. Atwood; D. D. Clark; T. Z. Hossain

1995-01-01

155

A liquid-hydrogen cold neutron source for the NBSR  

Microsoft Academic Search

The National Bureau of Standards Reactor (NBSR) is a 20-MW research reactor operated by the National Institute of Standards and Technology. It was designed with a 55-cm-diam beamport for the purpose of installing a D[sub 2]O-ice cold neutron source, completed in 1987. The success of the cold source led to the construction of the Cold Neutron Research Facility, an experimental

R. E. Williams; J. M. Roew; P. Kopetka

1992-01-01

156

An overview of an accelerator-based neutron spallation source  

SciTech Connect

An overview of the feasibility study of a 1-MW pulsed spallation source is presented. The machine delivers 1 MW of proton beam power to spallation targets where slow neutrons are produced. The slow neutrons can be used for isotope production, materials irradiation, and neutron scattering research. The neutron source facility is based on a rapid cycling synchrotron (RCS) and consists of a 400-MeV linac, a 30-Hz RCS that accelerates the 400-MeV beam to 2 GeV, and two neutron-generating target stations. The RCS accelerates an average proton beam current of 0.5 mA, corresponding to 1.04 x 10{sup 14} protons per pulse. This intensity is about two times higher than that of existing machines. A key feature of this accelerator system design is that beam losses are minimized from injection to extraction, reducing activation to levels consistent with hands-on maintenance.

Lessner, E.S.

1996-06-01

157

LENS—a pulsed neutron source for education and research  

NASA Astrophysics Data System (ADS)

At the Indiana University Cyclotron Facility construction of a new source of cold neutrons has begun. Neutrons are generated by stopping 13 MeV protons in a beryllium target, located at the center of a moderator structure. Cold neutrons are emitted from a slab of frozen methane. Three beam lines deliver neutrons for scattering experiments, radiography and moderator studies. The purpose of the project is to develop a low-cost, small-scale facility, suitable for a university or an industrial setting, to provide a testing ground of instrumentation destined for use at a larger facility, to improve awareness of the use of neutron probes in a wide range of applications, and to offer a training opportunity for future neutron physicists.

Baxter, David V.; Cameron, J. M.; Leuschner, M. B.; Meyer, H. O.; Nann, H.; Snow, W. M.

2005-04-01

158

Design and Demonstration of a Quasi-monoenergetic Neutron Source  

SciTech Connect

The design of a neutron source capable of producing 24 and 70 keV neutron beams with narrow energy spread is presented. The source exploits near-threshold kinematics of the 7Li(p,n)7Be reaction while taking advantage of the interference `notches' found in the scattering cross-sections of iron. The design was implemented and characterized at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory. Alternative lters such as vanadium and manganese are also explored and the possibility of studying the response of di*erent materials to low-energy nuclear recoils using the resultant neutron beams is discussed.

Joshi, T.; Sangiorgio, Samuele; Mozin, Vladimir V.; Norman, E. B.; Sorensen, Peter F.; Foxe, Michael P.; Bench, G.; Bernstein, A.

2014-03-05

159

Design and demonstration of a quasi-monoenergetic neutron source  

E-print Network

The design of a neutron source capable of producing 24 and 70 keV neutron beams with narrow energy spread is presented. The source exploits near-threshold kinematics of the $^{7}$Li(p,n)$^{7}$Be reaction while taking advantage of the interference `notches' found in the scattering cross-sections of iron. The design was implemented and characterized at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory. Alternative filters such as vanadium and manganese are also explored and the possibility of studying the response of different materials to low-energy nuclear recoils using the resultant neutron beams is discussed.

T. H. Joshi; S. Sangiorgio; V. Mozin; E. B. Norman; P. Sorensen; M. Foxe; G. Bench; A. Bernstein

2014-05-13

160

Brazilian gamma-neutron dosemeter: response to 241AmBe and 252Cf neutron sources.  

PubMed

With the aim of improving the monitoring of workers potentially exposed to neutron radiation in Brazil, the IPEN/CNEN-SP in association with PRO-RAD designed and developed a passive individual gamma-neutron mixed-field dosemeter calibrated to be used to (241)AmBe sources. To verify the dosimetry system response to different neutron spectra, prototypes were irradiated with a (252)Cf source and evaluated using the dose-calculation algorithm developed for (241)AmBe sources. PMID:21186217

Souto, E B; Campos, L L

2011-03-01

161

Fundamental neutron physics beamline at the spallation neutron source at ORNL  

NASA Astrophysics Data System (ADS)

We describe the Fundamental Neutron Physics Beamline (FnPB) facility located at the Spallation Neutron Source at Oak Ridge National Laboratory. The FnPB was designed for the conduct of experiments that investigate scientific issues in nuclear physics, particle physics, astrophysics and cosmology using a pulsed slow neutron beam. We present a detailed description of the design philosophy, beamline components, and measured fluxes of the polychromatic and monochromatic beams.

Fomin, N.; Greene, G. L.; Allen, R. R.; Cianciolo, V.; Crawford, C.; Tito, T. M.; Huffman, P. R.; Iverson, E. B.; Mahurin, R.; Snow, W. M.

2015-02-01

162

Fundamental Neutron Physics Beamline at the Spallation Neutron Source at ORNL  

E-print Network

We describe the Fundamental Neutron Physics Beamline (FnPB) facility located at the Spallation Neutron Source at Oak Ridge National Laboratory. The FnPB was designed for the conduct of experiments that investigate scientific issues in nuclear physics, particle physics, astrophysics and cosmology using a pulsed slow neutron beam. We present a detailed description of the design philosophy, beamline components, and measured fluxes of the polychromatic and monochromatic beams.

N. Fomin; G. L. Greene; R. Allen; V. Cianciolo; C. Crawford; T. Ito; P. R. Huffman; E. B. Iverson; R. Mahurin; W. M. Snow

2014-08-04

163

Progress on Development of an Ultra-Cold Neutron Source at the Los Alamos Neutron Science Center  

Microsoft Academic Search

Cold neutrons (400 m\\/s) derived from the short pulse spallation source at the Los Alamos Neutron Science Center are being used to create Ultra-Cold Neutrons (UCN) by Bragg scattering from a moving (rotating) package of mica crystals. Our objective is to develop a source with sufficient UCN densities to begin a research program to measure angular correlations in polarized neutron

Roger E. Hill; Thomas J. Bowles; Torben O. Brun; Christopher L. Morris; Susan J. Seestrom; Lowell Crow

1997-01-01

164

A compact ion source for intense neutron generation  

NASA Astrophysics Data System (ADS)

Today, numerous applications for neutrons, beyond those of the nuclear power industry, are beginning to emerge and become viable. From neutron radiography which, not unlike conventional X-rays, can provide an in-depth image through various materials, to neutron radiotherapy, for the treatment of certain forms of cancer, all these applications promise to improve our quality of life. To meet the growing need for neutrons, greater demands are being made on the neutron 'generator' technology, demands for improved neutron output and reliability at reduced physical sizes and costs. One such example in the field of borehole neutron generators, where, through neutron activation analysis, the elemental composition, concentration and location in the surrounding borehole media can be ascertained. These generators, which commonly rely on the fusion of deuterium (D) and tritium (T) at energies of the order of one hundred thousand Volts, seem to defy their physical limitations to provide neutron outputs approaching a billion per second in packages no greater than two inches in diameter. In an attempt to answer this demand, we, at Lawrence Berkeley National Laboratory (LBNL), have begun developing a new generation of neutron generators making use of recent developments in ion source technology. The specific application which motivates this development is in the environmental monitoring field, where pollutants and their concentrations in the subsurface must be assessed. To achieve the desired direction of low-level concentrations and obtain a better directional sensitivity, a neutron output of 109 to 1010 D-T neutrons per second was targeted for generator package which can fit inside a ~5 cm diameter borehole. To accomplish this performance, a radio-frequency (RF)- driven ion source developed at LBNL was adapted to the requirements of this application. The advantages of this type of ion source are its intrinsic ability to tailor the delivery of RF power to the ion source and therefore control the neutron output (pulse width, repetition rate and magnitude) while operating at low pressures (~5 mTorr). In the experimental testing presented herein, a prototype, 5 cm-diameter, inductively driven ion source has produced unsaturated hydrogen beam current densities in excess of 1 A/cm2 and monatomic species fractions in excess of 90%. This satisfactory performance, with respect to the targeted neutron output, was achieved with a 2 MHz, 60 kW pulse of RF to produce a ~20?s plasma pulse at <100 Hz.

Perkins, Luke Torrilhon

165

Evaluation of the Impact of Radial Gradient of Neutron Source in Vver Neutron Fluence Calculation  

NASA Astrophysics Data System (ADS)

Taking account of the radial source negative gradient in the periphery of reactor core leads to diminishing the evaluation of the neutron fluence onto the reactor vessel in comparison with the calculated one with an assembly-wise source. In the case of VVER-440 in the direction of maximum exposure this diminishing is about 10%. In the case of VVER-1000 the neutron fluence evaluation diminishes by about 20%. The results obtained give a base for reduction of the neutron fluence evaluation without diminishing the conservatism. In the case of surveillance specimens of VVER-1000/320 taking account of the radial gradient of the neutron source does not make a significant impact on the neutron fluence evaluation.

Ilieva, K.; Belousov, S.; Apostolov, T.; Kirilova, D.; Petrov, B.

2003-06-01

166

Intrinsic neutron source strengths in uranium solutions  

NASA Astrophysics Data System (ADS)

Neutron production rates for 5 pct. enriched uranyl fluoride and 93 pct. uranyl nitrate solutions have been measured using a high efficiency neutron well counter. Measurements were made for both solution types as a function of sample volume. These results were extrapolated to zero sample volume to eliminate sample size effects, such as multiplication and absorption. For the 5 pct. enriched uranyl fluoride solution, a neutron production rate of 0.0414 (+ or -) 0.0041 n/s/ml was measured; for the 93 pct. enriched uranyl nitrate solution, a neutron production rate of 0.0232 (+ or -) 0.0023 n/s/ml was measured. The biggest uncertainty is in measuring the detector efficiency, and further work on this aspect of the experiment is planned. Calculations for the neutron production rates based on measured thick-target (alpha, n) production rates and the known alpha stopping powers are in reasonable agreement with the data for the uranyl nitrate solution, but are in poor agreement with the data for the uranyl fluoride solution.

Anderson, R. E.; Robba, A. A.; Seale, R. L.; Rutherford, D. A.; Butterfield, K. B.; Brunson, G. S.

167

Nuclear and dosimetric features of an isotopic neutron source  

NASA Astrophysics Data System (ADS)

A multisphere neutron spectrometer was used to determine the features of a 239PuBe neutron source that is used to operate the ESFM-IPN Subcritical Reactor. To determine the source main features it was located a 100 cm from the spectrometer which was a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter polyethylene spheres. Count rates obtained with the spectrometer were unfolded using the NSDUAZ code and neutron spectrum, total fluence, and ambient dose equivalent were determined. A Monte Carlo calculation was carried out to estimate the spectrum and integral features being less than values obtained experimentally due to the presence of 241Pu in the Pu used to fabricate the source. Actual neutron yield and the mass fraction of 241Pu was estimated.

Vega-Carrillo, H. R.; Hernández-Dávila, V. M.; Rivera, T.; Sánchez, A.

2014-02-01

168

Towards detectors for next generation spallation neutron sources  

NASA Astrophysics Data System (ADS)

Neutron scattering and diffraction methods are of utmost importance for probing the structure and dynamics of condensed matter at an atomic, molecular and mesoscopic level. However, today's experiments, using either wavelength-selected cw beams from steady-state reactor or spallation sources or, on the other hand, comparatively weak pulsed spallation source beams (with the exception of the pulsed IBR-2 reactor in Dubna), suffer from relatively low source strengths, e.g. compared to synchrotron-radiation investigations. Therefore, neutron scattering methods can greatly benefit from next generation pulsed spallation neutron sources with 1-10 MW average proton beam power, which will allow analyzing wavelengths by time-of-flight (TOF) and thus utilizing in an experiment simultaneously a large fraction of the full wavelength band. However, the improved instantaneous flux will pose great challenges on the detection systems, since for instance for ESS, the strongest of the projected sources, the peak thermal neutron flux will be higher by nearly two orders of magnitude than at the presently strongest sources. Owing to current improvements in neutron optics and spectrometer design, the fluxes impinging on the samples will be further enhanced by another factor 5-10; however, this will be compensated for by the tendency to investigate smaller samples becoming accessible due to smaller foci and higher beam fluxes. Hence, thermal neutron detectors with up to two orders of magnitude higher peak count rate capacity in conjunction with microsecond TOF and for some applications sub-millimeter position resolutions are required, in addition to other characteristics like e.g. high long-term stability and low sensitivity to photon background. In this review article an overview will be given on the current state-of-the-art and on currently investigated novel solutions for thermal neutron detectors for very high rate and resolution time-resolved experiments, comprising silicon microstrip, hybrid low-pressure microstrip gas chamber and gas electron multiplier (GEM) detectors with solid neutron converters.

Gebauer, B.

2004-12-01

169

Body composition to climate change studies - the many facets of neutron induced prompt gamma-ray analysis  

SciTech Connect

In-vivo body composition analysis of humans and animals and in-situ analysis of soil using fast neutron inelastic scattering and thermal neutron capture induced prompt-gamma rays have been described. By measuring carbon (C), nitrogen (N) and oxygen (O), protein, fat and water are determined. C determination in soil has become important for understanding below ground carbon sequestration process in the light of climate change studies. Various neutron sources ranging from radio isotopic to compact 14 MeV neutron generators employing the associated particle neutron time-of-flight technique or micro-second pulsing were implemented. Gamma spectroscopy using recently developed digital multi-channel analyzers has also been described.

Mitra,S.

2008-11-17

170

Optimal Neutron Source & Beam Shaping Assembly for Boron Neutron Capture Therapy  

SciTech Connect

There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly.

J. Vujic; E. Greenspan; W.E. Kastenber; Y. Karni; D. Regev; J.M. Verbeke, K.N. Leung; D. Chivers; S. Guess; L. Kim; W. Waldron; Y. Zhu

2003-04-30

171

Inertial electrostatic confinement (IEC) neutron sources  

Microsoft Academic Search

Inertial electrostatic confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron

R. A. Nebel; D. C. Barnes; E. J. Caramana; R. D. Janssen; W. D. Nystrom; T. N. Tiouririne; B. C. Trent; G. H. Miley; J. Javedani

1995-01-01

172

Instrumental neutron activation determination of gold in mineral raw materials using a californium neutron source  

Microsoft Academic Search

A facility using a californium neutron source and a method for the neutron activation analysis of gold were developed. The\\u000a sensitivity of the determination is 0.1 g\\/t. The sources of random and systematic errors have been studied. It has been concluded\\u000a that in prospection and evaluation of gold ore deposits, the traditional test tube analysis for gold may be replaced

N. A. Shilo; E. G. Ippolitov; V. V. Ivanenko; B. N. Kustov; V. V. Zheleznov; G. N. Aristov; A. S. Shtan; I. N. Ivanov; V. V. Kovalenko; N. B. Kondrat’ev

1983-01-01

173

High Intensity Accelerator and Neutron Source in China  

SciTech Connect

High intensity Accelerator is being studied all over world for numerous applications, which includes the waste transmutation, spallation neutron source and material irradiation facilities. The R/D activities of the technology of High intensity accelerator are also developed in China for some year, and have some good facilities around China. This paper will reports the status of some high intensity accelerators and neutron source in China, which including ADS/RFQ; CARR; CSNS; PKUNIFTY and CPHS. This paper will emphatically report the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China.

Guan Xialing; Wei, J.; Loong Chun [Tsinghua University, 100084 Beijing (China)

2011-06-28

174

Spent-fuel photon and neutron source spectra  

SciTech Connect

Computational activities at Oak Ridge National Laboratory have been performed to develop appropriate data and techniques for computing the photon and neutron source spectra of spent fuel. The methods reviewed here include both the determination of spent-fuel composition and the radiation source spectra associated with these isotopic inventories.

Hermann, O.W.; Alexander, C.W.

1983-01-01

175

Materials for cold neutron sources: Cryogenic and irradiation effects  

Microsoft Academic Search

Materials for the construction of cold neutron sources must satisfy a range of demands. The cryogenic temperature and irradiation create a severe environment. Candidate materials are identified and existing cold sources are briefly surveyed to determine which materials may be used. Aluminum- and magnesium-based alloys are the preferred materials. Existing data for the effects of cryogenic temperature and near-ambient irradiation

1990-01-01

176

Epithermal Neutron Source for Neutron Resonance Spectroscopy (NRS) using High Intensity, Short Pulse Lasers  

SciTech Connect

A neutron source for neutron resonance spectroscopy (NRS) has been developed using high intensity, short pulse lasers. This measurement technique will allow for robust measurements of interior ion temperature of laser-shocked materials and provide insight into equation of state (EOS) measurements. The neutron generation technique uses protons accelerated by lasers off of Cu foils to create neutrons in LiF, through (p,n) reactions with {sup 7}Li and {sup 19}F. The distribution of the incident proton beam has been diagnosed using radiochromic film (RCF). This distribution is used as the input for a (p,n) neturon prediction code which is compared to experimentally measured neutron yields. From this calculation, a total fluence of 1.8 x 10{sup 9} neutrons is infered, which is shown to be a reasonable amount for NRS temperature measurement.

Higginson, D P; McNaney, J M; Swift, D C; Bartal, T; Hey, D S; Pape, S L; Mackinnon, A; Mariscal, D; Nakamura, H; Nakanii, N; Beg, F N

2010-04-22

177

Core Vessel Insert Handling Robot for the Spallation Neutron Source  

SciTech Connect

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

2011-01-01

178

Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator  

NASA Astrophysics Data System (ADS)

Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

2014-12-01

179

A thermal neutron source imager using coded apertures  

SciTech Connect

To facilitate the process of re-entry vehicle on-site inspections, it would be useful to have an imaging technique which would allow the counting of deployed multiple nuclear warheads without significant disassembly of a missile`s structure. Since neutrons cannot easily be shielded without massive amounts of materials, they offer a means of imaging the separate sources inside a sealed vehicle. Thermal neutrons carry no detailed spectral information, so their detection should not be as intrusive as gamma ray imaging. A prototype device for imaging at close range with thermal neutrons has been constructed using an array of {sup 3}He position-sensitive gas proportional counters combined with a uniformly redundant coded aperture array. A sealed {sup 252}Cf source surrounded by a polyethylene moderator is used as a test source. By means of slit and pinhole experiments, count rates of image-forming neutrons (those which cast a shadow of a Cd aperture on the detector) are compared with the count rates for background neutrons. The resulting ratio, which limits the available image contrast, is measured as a function of distance from the source. The envelope of performance of the instrument is defined by the contrast ratio, the angular resolution, and the total count rate as a function of distance from the source. These factors will determine whether such an instrument could be practical as a tool for treaty verification.

Vanier, P.E.; Forman, L.; Selcow, E.C.

1995-08-01

180

China Spallation Neutron Source: Design, R&D, and outlook  

Microsoft Academic Search

The China Spallation Neutron Source (CSNS) is an accelerator based multidiscipline user facility planned to be constructed in Dongguan, Guangdong, China. The CSNS complex consists of an negative hydrogen linear accelerator, a rapid cycling proton synchrotron accelerating the beam to 1.6GeV energy, a solid tungsten target station, and instruments for spallation neutron applications. The facility operates at 25Hz repetition rate

Jie Wei; Hesheng Chen; Yanwei Chen; Yuanbo Chen; Yunlong Chi; Changdong Deng; Haiyi Dong; Lan Dong; Shouxian Fang; Ji Feng; Shinian Fu; Lunhua He; Wei He; Yuekun Heng; Kaixi Huang; Xuejun Jia; Wen Kang; Xiangcheng Kong; Jian Li; Tianjiao Liang; Guoping Lin; Zhenan Liu; Huafu Ouyang; Qing Qin; Huamin Qu; Caitu Shi; Hong Sun; Jingyu Tang; Juzhou Tao; Chunhong Wang; Fangwei Wang; Dingsheng Wang; Qingbin Wang; Sheng Wang; Tao Wei; Jiwei Xi; Taoguang Xu; Zhongxiong Xu; Wen Yin; Xuejun Yin; Jing Zhang; Zong Zhang; Zonghua Zhang; Min Zhou; Tao Zhu

2009-01-01

181

Level-1 PRA of the advanced neutron source reactor  

SciTech Connect

The advanced neutron source (ANS) reactor is being designed to provide thermal and subthermal neutrons for neutron scattering, physics experiments, materials irradiation, analytical chemistry, and transuranium as well as other isotopic production. The ANS is currently in the preliminary design phase and will be built at Oak Ridge National Laboratory. To be the world`s most intense neutron source available for continuous beams of low-energy neutrons, very high neutron flux and power density are required. This results in low thermal inertia and fast transient and accident responses. The current design of the ANS is a heavy-water-cooled, moderated, and reflected reactor housed in a large, double-walled containment dome and surrounded by thermal neutron beam experiments. It is designed with many safety features, including large heat sinks and a layout that maximizes natural circulation capabilities sufficient for decay heat removal; passive inventory control by accumulators, light water pools, and floodable cells; and fast, redundant, diverse shutdown systems. In parallel with the design efforts, a plant-specific level-1 probabilistic risk assessment (PRA) has been completed for the ANS conceptual design as part of the overall safety program.

Lin, J.C.; Bley, D.C.; Ramsey, C.T. [Oak Ridge National Lab., TN (United States)

1994-12-31

182

Materials for cold neutron sources: Cryogenic and irradiation effects  

SciTech Connect

Materials for the construction of cold neutron sources must satisfy a range of demands. The cryogenic temperature and irradiation create a severe environment. Candidate materials are identified and existing cold sources are briefly surveyed to determine which materials may be used. Aluminum- and magnesium-based alloys are the preferred materials. Existing data for the effects of cryogenic temperature and near-ambient irradiation on the mechanical properties of these alloys are briefly reviewed, and the very limited information on the effects of cryogenic irradiation are outlined. Generating mechanical property data under cold source operating conditions is a daunting prospect. It is clear that the cold source material will be degraded by neutron irradiation, and so the cold source must be designed as a brittle vessel. The continued effective operation of many different cold sources at a number of reactors makes it clear that this can be accomplished. 46 refs., 8 figs., 2 tab.

Alexander, D.J.

1990-01-01

183

Neutron source reconstruction from pinhole imaging at National Ignition Facility  

SciTech Connect

The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the ignition stage of inertial confinement fusion (ICF) implosions at NIF. Since the neutron source is small (?100 ?m) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-?m resolution are 20-cm long, single-sided tapers in gold. These apertures, which have triangular cross sections, produce distortions in the image, and the extended nature of the pinhole results in a non-stationary or spatially varying point spread function across the pinhole field of view. In this work, we have used iterative Maximum Likelihood techniques to remove the non-stationary distortions introduced by the aperture to reconstruct the underlying neutron source distributions. We present the detailed algorithms used for these reconstructions, the stopping criteria used and reconstructed sources from data collected at NIF with a discussion of the neutron imaging performance in light of other diagnostics.

Volegov, P.; Danly, C. R.; Grim, G. P.; Guler, N.; Merrill, F. E.; Wilde, C. H.; Wilson, D. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Fittinghoff, D. N.; Izumi, N.; Ma, T.; Warrick, A. L. [Livermore National Laboratory, Livermore, California 94550 (United States)] [Livermore National Laboratory, Livermore, California 94550 (United States)

2014-02-15

184

Neutron source reconstruction from pinhole imaging at National Ignition Facility.  

PubMed

The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the ignition stage of inertial confinement fusion (ICF) implosions at NIF. Since the neutron source is small (?100 ?m) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-?m resolution are 20-cm long, single-sided tapers in gold. These apertures, which have triangular cross sections, produce distortions in the image, and the extended nature of the pinhole results in a non-stationary or spatially varying point spread function across the pinhole field of view. In this work, we have used iterative Maximum Likelihood techniques to remove the non-stationary distortions introduced by the aperture to reconstruct the underlying neutron source distributions. We present the detailed algorithms used for these reconstructions, the stopping criteria used and reconstructed sources from data collected at NIF with a discussion of the neutron imaging performance in light of other diagnostics. PMID:24593362

Volegov, P; Danly, C R; Fittinghoff, D N; Grim, G P; Guler, N; Izumi, N; Ma, T; Merrill, F E; Warrick, A L; Wilde, C H; Wilson, D C

2014-02-01

185

Four energy group neutron flux distributions in the Syrian Miniature Neutron Source Reactor using the WIMSD4 and CITATION codes  

Microsoft Academic Search

A 3-D (R, ?, Z) neutronic model for the Miniature Neutron Source Reactor (MNSR) was developed earlier to conduct the reactor neutronic analysis. The group constants for all the reactor components were generated using the WIMSD4 code. The reactor excess reactivity and the four group neutron flux distributions were calculated using the CITATION code. This model is used in this

K. Khattab; H. Omar; N. Ghazi

2009-01-01

186

14-MeV Neutron Generator Used as a Thermal Neutron Source  

SciTech Connect

One of the most important applications of the general purpose Monte Carlo N-Particle (MCNPS and MCNPX) codes is neutron shielding design. We employed this method to simulate the shield of a 14-MeV neutron generator used as a thermal neutron source providing an external thermal neutron beam for testing large area neutron detectors developed for diffraction studies in biology and also useful for national security applications. Nuclear reactors have been the main sources of neutrons used for scientific applications. In the past decade, however, a large number of reactors have been shut down, and the importance of other, smaller devices capable of providing neutrons for research has increased. At Brookhaven National Laboratory a moderated Am-Be neutron source with shielding is used for neutron detector testing. This source is relatively weak, but provides a constant flux of neutrons, even when not in use. The use of a 14 MeV energized neutron generator, with an order of magnitude higher neutron flux has been considered to replace the Am-Be source, but the higher fast neutron yield requires a more careful design of moderator and shielding. In the present paper we describe a proposed shielding configuration based on Monte Carlo calculations, and provide calculated neutron flux and dose distributions. We simulated the neutron flux distribution of our existing Am-Be source surrounded by a paraffin thermalizer cylinder (radius of 17.8 cm), 0.8 mm cadmium, and borated polyethylene as biological shield. The thermal neutrons are available through a large opening through the polyethylene and cadmium. The geometrical model for the MCNPS and MCNPX2 simulations is shown in Fig. 1. We simulated the Am-Be source neutron energy distribution as a point source having an energy distribution of four discrete lines at 3.0 (37%), 5.0 (35%), 8.0 (20%) and 11.0 (8%) MeV energies. The estimated source strength based on the original specifications is 6.6 {center_dot} 10{sup 6} neutrons/sec. The simulation accurately predicts the measured thermal neutron flux at the collimator (Figure 2), thus providing validation for this method. Using MCNPX we simulated the neutron and photon dose distribution and also obtained a good agreement with the measured values. Having established a validated framework for the shield calculation we then scaled up the Am-Be arrangement to simulate the shielding required for the higher neutron energy and flux of the neutron generator (-10{sup 8} neutrodsec at 14 MeV). Given the physical dimensions of the generator we have chosen a cylindrical geometry, where the generator tube is placed vertically into a cylindrical thermalizer (25 cm paraffin) from above. The thermalizer is surrounded by 0.8 mm cadmium, and a cylindrical borated polyethylene shield. A cylindrical opening (radius of 7.6 cm) serves to direct the neutrons out towards the experimental area (on the right side). The initial model is shown in figure 3. The first goal of the calculations was to establish the minimal required radius of the biological shield. For this purpose we performed MCNPX neutron and photon dose distribution calculations by tallying the absorbed dose on a 200 x 200 cm mesh in the vertical center plane superimposed over the geometry. Figure 4. displays the neutron dose distribution along the central horizontal (X) axis. As observed from the figure, a shielding radius of -80 cm is sufficient to obtain a dose level of < -4 mrem/hour outside the shield (except from the open neutron channel on the right). In the next step we studied the optimization of the thickness of the paraffin thermalizer by increasing the depth of the neutron exit channel into the paraffin cylinder. It was found, that the thermal flux greatly increases if we have thinner paraffin layer, an optimal value being about 5 cm thickness. But as a drawback the flux of fast neutrons also increased. A thicker thermalizer layer, in fact, acts as shielding. A slightly off centered, tangential placement of the neutron channel provides a solution which maximizes the thermal flux to fast n

Dioszegi,I.

2008-08-10

187

The new Cold Neutron Chopper Spectrometer at the Spallation Neutron Source -- Design and Performance  

SciTech Connect

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

Ehlers, Georg [ORNL; Podlesnyak, Andrey A [ORNL; Niedziela, Jennifer L [ORNL; Iverson, Erik B [ORNL; Sokol, Paul E [ORNL

2011-01-01

188

The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance  

SciTech Connect

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

Ehlers, G.; Podlesnyak, A. A.; Niedziela, J. L.; Iverson, E. B. [Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Sokol, P. E. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

2011-08-15

189

The new cold neutron chopper spectrometer at the Spallation Neutron Source: design and performance.  

PubMed

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments. PMID:21895276

Ehlers, G; Podlesnyak, A A; Niedziela, J L; Iverson, E B; Sokol, P E

2011-08-01

190

The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance  

NASA Astrophysics Data System (ADS)

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

Ehlers, G.; Podlesnyak, A. A.; Niedziela, J. L.; Iverson, E. B.; Sokol, P. E.

2011-08-01

191

Some preliminary design considerations for the ANS (Advanced Neutron Source) reactor cold source  

Microsoft Academic Search

Two areas concerned with the design of the Advanced Neutron Source (ANS) cold source have been investigated by simple one-dimensional calculations. The gain factors computed for a possible liquid nitrogen-15 cold source moderator are considerably below those computed for the much colder liquid deuterium moderator, as is reasonable considering the difference in moderator temperature. Nevertheless, nitrogen-15 does represent a viable

1988-01-01

192

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.

2010-08-04

193

High Flux Isotope Reactor cold neutron source reference design concept  

SciTech Connect

In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.

Selby, D.L.; Lucas, A.T.; Hyman, C.R. [and others

1998-05-01

194

Feasibility of single-view coded source neutron transmission tomography  

NASA Astrophysics Data System (ADS)

In a simulation experiment, we study the feasibility of single-view coded source neutron transmission tomography for imaging water density in fuel cells at the NIST neutron imaging facility. In standard two-dimensional transmission tomography, one reconstructs a spatially varying attenuation image based on many projections or views of an object. Here, we consider the limiting case where only one view is available. Rather than parallel beam sources, the projection data are produced by multiple pinhole sources. For a high-count case where the object is near the sources and the object magnification is approximately 200, and attenuation varies very smoothly in the object, we demonstrate that a penalized maximum likelihood method yields a reconstruction of attenuation that has a fractional root-mean-square prediction error of 5.8%. We determine the regularization parameter in the penalized likelihood method using a statistical learning method called two-fold cross-validation. As the object-to-source distance increases and object magnification in the detector plane decreases, the quality of the reconstruction deteriorates. At the NIST neutron imaging facility, the object magnification in a single-view coded source neutron imaging experiment would be only about 4. Due to this low magnification, even for the favorable case considered where attenuation varies very smoothly and we observe high-count projection data, we conclude that single-view coded source neutron transmission tomography is not a promising method for quantifying the spatial distribution of water in a fuel cell. (Contributions by staff of NIST, an agency of the US Government, are not subject to copyright.)

Coakley, K. J.; Hussey, D. S.

2007-11-01

195

China Spallation Neutron Source: Design, R&D, and outlook  

NASA Astrophysics Data System (ADS)

The China Spallation Neutron Source (CSNS) is an accelerator based multidiscipline user facility planned to be constructed in Dongguan, Guangdong, China. The CSNS complex consists of an negative hydrogen linear accelerator, a rapid cycling proton synchrotron accelerating the beam to 1.6 GeV energy, a solid tungsten target station, and instruments for spallation neutron applications. The facility operates at 25 Hz repetition rate with an initial design beam power of 120 kW and is upgradeable to 500 kW. The primary challenge is to build a robust and reliable user's facility with upgrade potential at a fraction of "world standard" cost. We report the status, design, R&D, and upgrade outlook including applications using spallation neutron, muon, fast neutron, and proton, as well as related programs including medical therapy and accelerator-driven sub-critical reactor (ADS) programs for nuclear waste transmutation.

Wei, Jie; Chen, Hesheng; Chen, Yanwei; Chen, Yuanbo; Chi, Yunlong; Deng, Changdong; Dong, Haiyi; Dong, Lan; Fang, Shouxian; Feng, Ji; Fu, Shinian; He, Lunhua; He, Wei; Heng, Yuekun; Huang, Kaixi; Jia, Xuejun; Kang, Wen; Kong, Xiangcheng; Li, Jian; Liang, Tianjiao; Lin, Guoping; Liu, Zhenan; Ouyang, Huafu; Qin, Qing; Qu, Huamin; Shi, Caitu; Sun, Hong; Tang, Jingyu; Tao, Juzhou; Wang, Chunhong; Wang, Fangwei; Wang, Dingsheng; Wang, Qingbin; Wang, Sheng; Wei, Tao; Xi, Jiwei; Xu, Taoguang; Xu, Zhongxiong; Yin, Wen; Yin, Xuejun; Zhang, Jing; Zhang, Zong; Zhang, Zonghua; Zhou, Min; Zhu, Tao

2009-02-01

196

Inertial-Electrostatic Confinement Neutron/Proton Source  

NASA Astrophysics Data System (ADS)

There is considerable demand in the scientific community for a neutron generator with an output of 106-108 neutrons/second (n/s) that can be switched on or off, emit fusion neutrons, be self-calibrating, and offer portable operation. An Inertial Electrostatic Confinement (IEC)-based neutron generator is proposed to meet these needs. In an IEC device, ion beams are injected into a spherical vacuum vessel containing one or more sets of spherical wire grids. A high fusion rate is generated in a dense plasma region created in the center of the innermost grid by intersecting ion beams and the associated potential well structure. Here, we describe a unique configuration, termed the IECGD, where a gaseous discharge in a single-gridded device serves as the ion source. Operation in the newly discovered "Star" discharge mode maximizes the effective grid transmission factor for ions. This configuration, then, provides a simple, rugged, low-cost fusion neutron source, operating in the 106 D-D n/s or 108 D-T n/s range. The extension to an intense MeV proton source is also possible. Experimental results for the IECGD are presented, with a discussion of corresponding theoretical studies using a Vlasov-Poisson solver (IXL) and an electrostatic particle-in-cell code (PDS1).

Miley, G. H.; Javedani, J.; Yamamoto, Y.; Nebel, R.; Nadler, J.; Gu, Y.; Satsangi, A.; Heck, P.

1994-03-01

197

Status report on the cold neutron source of the Garching neutron research facility FRM-II  

Microsoft Academic Search

The new high flux research reactor of the Technical University of Munich (Technische Universität München, TUM) will be equipped with a cold neutron source (CNS). The centre of the CNS will be located in the D2O-reflector tank at 400mm from the reactor core axis close to the thermal neutron flux maximum. The power of 4500W developed by the nuclear heating

K. Gobrecht; E. Gutsmiedl; A. Scheuer

2002-01-01

198

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

SciTech Connect

A modeling investigation was performed to choose moderator material and size for creating optimal epithermal neutron beams for BNCT based on a proton accelerator and the 7Li(p,n)7Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine. Results of calculation were experimentally tested and are in good agreement with measurements.

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

2004-02-20

199

Water-extended polyester neutron shield for a 252Cf neutron source.  

PubMed

A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester was carried out. During calculations, (252)Cf and shielding were modelled and the neutron spectra as well as the H(10) were calculated in four sites. The calculation was extended to include a water shielding, the source in vacuum and in air. Besides neutron shielding characteristics, the Kerma in air due to gammas emitted by (252)Cf and due to capture gamma rays in the shielding were included. PMID:17496334

Vega-Carrillo, H R; Manzanares-Acuña, E; Hernández-Dávila, V M; Gallego, E; Lorente, A; Donaire, I

2007-01-01

200

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

DOEpatents

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. 3 figs.

Yoon, W.Y.; Jones, J.L.; Nigg, D.W.; Harker, Y.D.

1999-05-11

201

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

DOEpatents

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)

1999-01-01

202

Development of an IEC neutron source for NDE  

SciTech Connect

This paper concerns the development of a neutron so based on the inertial electrostatic confinement (IEC) of a low density fusion plasma in a gridded, spherically-focusing device. With the motivation of using such sources for nondestructive evaluation (NDE) applications, the focus of the development is on : Small size devices, sealed operation with D{sub 2} or D{sub 2}/T{sub 2} mixtures, Power-utilization and neutron-output optimization, and integration into an assay system. In this paper, we describe an experimental system that has been established for the development and testing of IEC neutron sources, and we present preliminary results of tests conducted for 25-cm and 15-cm diameter IEC devices.

Anderl, R.A,; Hartwell, J.K. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States); Nadler, J.H. [Illinois Univ., Urbana, IL (United States). Fusion Studies Lab.

1995-12-01

203

RTNS-II (Rotating Target Neutron Source II) operational summary  

SciTech Connect

The Rotating Target Neutron Source II facility (RTNS-II) operated for over nine years. Its purpose was to provide high intensities of 14 MeV neutrons for materials studies in the fusion energy program. For the period from 1982-1987, the facility was supported by both the US (Department of Energy) and Japan (Ministry of Education, Culture, and Science). RTNS-II contains two accelerator-based neutron sources which use the T(d,n)/sup 4/He reaction. In this paper, we will summarize the operational history of RTNS-II. Typical operating parameters are given. In addition, a brief description of the experimental program is presented. The current status and future options for the facility are discussed. 7 refs., 5 tabs.

Heikkinen, D.W.

1988-09-01

204

SubCritical Transmutation Reactors with Tokamak Fusion Neutron Sources  

Microsoft Academic Search

The principal results of a series of design scoping studies of sub-critical fast transmutation reactors (based on the nuclear and processing technology being developed in the USDoE Generation IV, Advanced Fuel Cycle and Next Generation Nuclear Plant programs) coupled with a tokamak fusion neutron source (based on the ITER design basis physics and technology) are presented.

W. M. Stacey; J. Mandrekas; E. A. Hoffman

2005-01-01

205

Safety aspects of the Texas cold neutron source  

Microsoft Academic Search

This paper concerns the safety aspects and design features of the Texas Cold Neutron Source (TCNS), which was designed and recently constructed by the Nuclear Engineering Teaching Laboratory (NETL) at the University of Texas at Austin. The TCNS fits into the piercing beam port of the NETL 1-MW Triga Mark II reactor. The major safety considerations for the TCNS are

K. Uenlue; T. L. Bauer; B. W. Wehring

1992-01-01

206

Impedance measurements of the Spallation Neutron Source extraction kicker system  

Microsoft Academic Search

Transverse coupling impedance measurements of the Spallation Neutron Source (SNS) beam extraction system were performed and the results are here reported. The SNS beam extraction system is composed from 14 subsystems, each of which consists of a vertical kicker magnet plus a pulse forming network (PFN). Impedance bench measurements were performed on one large and one small aperture magnet, stand-alone

H. Hahn

2004-01-01

207

Materials for spallation neutron sources, with emphasis on SNS facility  

Microsoft Academic Search

The materials requirements in a high-power spallation neutron source like the SNS are particularly demanding. Materials at the target station are of special concern; these include the containment vessel and protective shroud for the mercury target material, beam windows, support structures, moderator housings, and beam tubes. The material chosen for the mercury containment vessel is Type 316 stainless steel (316SS).

Mansur

1999-01-01

208

Research on fusion neutron sources M. P. Gryaznevich  

E-print Network

energy by nuclear power. The possibility to use a small or medium size ST as a powerful or intense steady Source (SCFNS), with major radius as low as 0.5 metres but still able to produce several MW of neutrons reactions required for economic power generation (i.e. much more power out than power in), the conventional

209

The Spallation Neutron Source (SNS) conceptual design shielding analysis  

Microsoft Academic Search

The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional

J. O. Johnson; N. Odano; R. A. Lillie

1998-01-01

210

A Californium-252 Neutron Source for Student Use  

ERIC Educational Resources Information Center

Describes an undergraduate chemistry experiment which utilizes small samples of Californium 252 as a neutron source for the activation of 12 other elements. The students prepare decay curves of the radioactive isotopes and perform nondestructive activation analyses for gram amounts of some elements. (MLH)

Bowen, H. J.

1975-01-01

211

Thermal hydraulic tests of a liquid hydrogen cold neutron source  

Microsoft Academic Search

The authors have built and tested a simplified full scale model of the planned liquid hydrogen moderator for the cold neutron source of the NIST reactor. The heat load to the liquid hydrogen will be removed to an external refrigerator by means of a thermosyphon. The authors' experiments showed that this system could be filled, would operate stably, and the

J. D. Siegwarth; D. A. Olson; M. A. Lewis; J. M. Rowe; R. E. Williams

1994-01-01

212

MCNP simulation of TRR-II cold neutron source design  

Microsoft Academic Search

A cold neutron source (CNS) for the modified Taiwan Research Reactor (TRR-II) was designed using the MCNP code. Liquid hydrogen at 20K is selected as a moderator. The moderator cell has a structure of a cylindrical annulus in which the outer shell contains liquid hydrogen and the inner shell has only hydrogen vapor. The moderator cell is made of a

Tai-Cheng Guung; Wen-Fa Tsai; Weng-Sheng Kuo; Jong-Sheng Chen

2002-01-01

213

Advanced Neutron Source reactor control and plant protection systems design  

Microsoft Academic Search

This paper describes the reactor control and plant protection systems' conceptual design of the Advanced Neutron Source (ANS). The Plant Instrumentation, Control, and Data Systems and the Reactor Instrumentation and Control System of the ANS are planned as an integrated digital system with a hierarchical, distributed control structure of qualified redundant subsystems and a hybrid digital\\/analog protection system to achieve

J. L. Anderson; R. E. Battle; J. March-Leuba; M. I. Khayat

1992-01-01

214

Intense pulsed neutron source status report  

SciTech Connect

The status and future plans of IPNS will be reviewed. At the celebration of our 10th anniversary in 7 months, IPNS will have performed over 2000 experiments and has over 230 scientists visiting IPNS annually. Plans for a new spallation source concept using a fixed field alternating gradient synchrotron will be presented.

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

1990-01-01

215

Thermal-hydraulic studies of the Advanced Neutron Source cold source  

SciTech Connect

The Advanced Neutron Source (ANS), in its conceptual design phase at Oak Ridge National Laboratory, was to be a user-oriented neutron research facility producing the most intense steady-state flux of thermal and cold neutrons in the world. Among its many scientific applications, the production of cold neutrons was a significant research mission for the ANS. The cold neutrons come from two independent cold sources positioned near the reactor core. Contained by an aluminum alloy vessel, each cold source is a 410-mm-diam sphere of liquid deuterium that functions both as a neutron moderator and a cryogenic coolant. With nuclear heating of the containment vessel and internal baffling, steady-state operation requires close control of the liquid deuterium flow near the vessel`s inner surface. Preliminary thermal-hydraulic analyses supporting the cold source design were performed with heat conduction simulations of the vessel walls and multidimensional computational fluid dynamics simulations of the liquid deuterium flow and heat transfer. This report presents the starting phase of a challenging program and describes the cold source conceptual design, the thermal-hydraulic feasibility studies of the containment vessel, and the future computational and experimental studies that were planned to verify the final design.

Williams, P.T.; Lucas, A.T.

1995-08-01

216

Neutron activation analysis of essential elements in Multani mitti clay using miniature neutron source reactor.  

PubMed

Multani mitti clay was studied for 19 essential and other elements. Four different radio-assay schemes were adopted for instrumental neutron activation analysis (INAA) using miniature neutron source reactor. The estimated weekly intakes of Cr and Fe are high for men, women, pregnant and lactating women and children while intake of Co is higher in adult categories and Mn by pregnant women. Comparison of MM clay with other type of clays shows that it is a good source of essential elements. PMID:22871439

Waheed, S; Rahman, S; Faiz, Y; Siddique, N

2012-10-01

217

Evaluation of thermal neutron irradiation field using a cyclotron-based neutron source for alpha autoradiography.  

PubMed

It is important to measure the microdistribution of (10)B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of (10)B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×10(9) (cm(-2)s(-1)) and an area of 40mm in diameter. In this paper, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500mg/kg of boronophenyl-alanine. PMID:24560850

Tanaka, H; Sakurai, Y; Suzuki, M; Masunaga, S; Mitsumoto, T; Kinashi, Y; Kondo, N; Narabayashi, M; Nakagawa, Y; Watanabe, T; Fujimoto, N; Maruhashi, A; Ono, K

2014-06-01

218

Optimizing moderator dimensions for neutron scattering at the spallation neutron source  

SciTech Connect

In this work, we investigate the effect of neutron moderator dimensions on the performance of neutron scattering instruments at the Spallation Neutron Source (SNS). In a recent study of the planned second target station at the SNS facility, we have found that the dimensions of a moderator play a significant role in determining its surface brightness. A smaller moderator may be significantly brighter over a smaller viewing area. One of the immediate implications of this finding is that for modern neutron scattering instrument designs, moderator dimensions and brightness have to be incorporated as an integrated optimization parameter. Here, we establish a strategy of matching neutron scattering instruments with moderators using analytical and Monte Carlo techniques. In order to simplify our treatment, we group the instruments into two broad categories: those with natural collimation and those that use neutron guide systems. For instruments using natural collimation, the optimal moderator selection depends on the size of the moderator, the sample, and the moderator brightness. The desired beam divergence only plays a role in determining the distance between sample and moderator. For instruments using neutron optical systems, the smallest moderator available that is larger than the entrance dimension of the closest optical element will perform the best (assuming, as is the case here that smaller moderators are brighter)

Zhao, J. K.; Robertson, J. L.; Herwig, Kenneth W.; Gallmeier, Franz X.; Riemer, Bernard W. [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2013-12-15

219

Linac design study for an intense neutron-source driver  

SciTech Connect

The 1-MW spallation-neutron source under design study at Los Alamos is driven by a linac-compressor-ring scheme that utilizes a large portion of the existing Los Alamos Meson Physics Facility (LAMPF) linac, as well as the facility infrastructure. The project is referred to as the National Center for Neutron Research (NCNR). A second phase of the proposal will upgrade the driver power to 5 MW. A description of the 1-MW scheme is given in this paper. In addition, the upgrade path to the substantial increase of beam power required for the 5 MW scenario is discussed.

Lynch, M.T.; Browman, A.; DeHaven, R.; Jameson, R.; Jason, A.; Neuschaefer, G.; Tallerico, P.; Regan, A.

1993-06-01

220

Linac design study for an intense neutron-source driver  

SciTech Connect

The 1-MW spallation-neutron source under design study at Los Alamos is driven by a linac-compressor-ring scheme that utilizes a large portion of the existing Los Alamos Meson Physics Facility (LAMPF) linac, as well as the facility infrastructure. The project is referred to as the National Center for Neutron Research (NCNR). A second phase of the proposal will upgrade the driver power to 5 MW. A description of the 1-MW scheme is given in this paper. In addition, the upgrade path to the substantial increase of beam power required for the 5 MW scenario is discussed.

Lynch, M.T.; Browman, A.; DeHaven, R.; Jameson, R.; Jason, A.; Neuschaefer, G.; Tallerico, P.; Regan, A.

1993-01-01

221

Small plasma focus as neutron pulsed source for nuclides identification.  

PubMed

In this paper, we present preliminary results on the feasibility of employing a low energy (2 kJ, 31 kV) plasma focus device as a portable source of pulsed neutron beams (2.45 MeV) generated by nuclear fusion reactions D-D, for the "in situ" analysis of substances by nuclear activation. This source has the relevant advantage of being pulsed at requirement, transportable, not permanently radioactive, without radioactive waste, cheap, among others. We prove the feasibility of using this source showing several spectra of the characteristic emission line for manganese, gold, lead, and silver. PMID:24182104

Milanese, M; Niedbalski, J; Moroso, R; Barbaglia, M; Mayer, R; Castillo, F; Guichón, S

2013-10-01

222

Ion source antenna development for the Spallation Neutron Source  

Microsoft Academic Search

The operational lifetime of a radio-frequency (rf) ion source is generally governed by the length of time the insulating structure protecting the antenna survives during exposure to the plasma. Coating the antenna with a thin layer of insulating material is a common means of extending the life of such antennas. When low-power\\/low-duty factor rf excitation is employed, antenna lifetimes of

R. F. Welton; M. P. Stockli; Y. Kang; M. Janney; R. Keller; R. W. Thomae; T. Schenkel; S. Shukla

2002-01-01

223

Experience with position-sensitive neutron detectors at the Intense Pulsed Neutron Source  

NASA Astrophysics Data System (ADS)

At the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory, pulses of protons accelerated in a synchrotron produce pulses of fast neutrons via the spallation process in an enriched uranium target. After moderation, the resulting pulses of slow neutrons are directed into beams which serve a variety of neutron-scattering instruments. Currently there are thirteen neutron-scattering instruments in operation or under development at IPNS, and six of these use position-sensitive neutron detectors (PSDs). These PSDs are: a 30 cm × 30 cm, ˜3 mm resolution, neutron Anger camera area PSD with 6Li-glass scintillator; a 2.5 cm diameter, ˜0.7 mm resolution, microchannel-plate area PSD with 6Li-glass scintillator; a 20 cm × 20 cm, ˜5 mm resolution, 3He proportional-counter area PSD; a 40 cm × 40 cm, ˜4 mm resolution, 3He proportional-counter area PSD; a flat 20 cm long, ˜1.6 mm resolution, 3He proportional-counter linear PSD; and 160 cylindrical 3He proportional-counter linear PSDs, each of which is 1.27 cm in diameter and 60 cm long and has ˜14 mm resolution. These detectors, in addition to being position-sensitive, resolve the time of the neutron capture with ˜1 ?s precision for neutron time-of-flight measurements. This paper will discuss these various PSDs with emphasis on the instrumental specifications and the reasons for the selection of the different types of PSDs, and will also discuss the observed performances of these PSDs.

Crawford, R. K.; Haumann, J. R.; Epperson, J. E.; Thiyagarajan, P.; Schultz, A. J.; Felcher, G. P.; Montague, D. G.; Dejus, R. J.

1990-12-01

224

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

2006-01-01

225

An Ultracold Neutron Source for 1. Introduction to Ultracold Neutrons (UCN)  

E-print Network

astrophysics ­ BBN ­ r-process surface physics development towards JPARC 2nd target station UCN source #12 interacts with free neutron (UCN) target. 132Sn current 5e17 /s UCN density 2e4 /cc meter-long target sigma. Gutsmiedl, Munich FRM-II R. Golub, NCSU B. Filippone, Caltech P. Huffman, NCSU T. Ito, LANL E. Korobkina

Martin, Jeff

226

Capabilities of a DT tokamak fusion neutron source for driving a spent nuclear fuel transmutation reactor  

Microsoft Academic Search

The capabilities of a DT fusion neutron source for driving a spent nuclear fuel transmutation reactor are characterized by identifying limits on transmutation rates that would be imposed by tokamak physics and engineering limitations on fusion neutron source performance. The need for spent nuclear fuel transmutation and the need for a neutron source to drive subcritical fission transmutation reactors are

W. M. Stacey

2001-01-01

227

Post irradiation examination of the Spallation Neutron Source target vessels  

SciTech Connect

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is an accelerator-based pulsed neutron source that produces high-energy spallation neutrons by bombarding liquid mercury flowing through a stainless steel target vessel. During operation the proton beam and spallation neutrons produce radiation damage in the AISI 316L austenitic stainless steel target vessel and water-cooled shroud. The beam pulses also cause rapid heating of the liquid mercury, which may produce cavitation erosion damage on the inner surface of the target vessel. The cavitation erosion rate is thought to be highly sensitive to beam power and predicted to be the primary life-limiting factor of target vessel. Though mitigation of cavitation erosion and radiation damage to the target vessel will be a critical for successful high-power operation of the SNS facility, the effects of radiation damage and cavitation erosion to target vessels in liquid metal spallation systems are not well known. Therefore preparations are being undertaken to perform post irradiation examination (PIE) of the liquid mercury target vessel and water-cooled shroud after end-of-life occurs. An overview of the planned PIE for the SNS target vessel is presented here, including proposed techniques for specimen acquisition and subsequent material properties characterization.

McClintock, David A [ORNL; Ferguson, Phillip D [ORNL; Mansur, Louis K [ORNL

2010-01-01

228

Optimization of the beam geometry for the cold neutron tomography facility at the new neutron source in Munich  

Microsoft Academic Search

One of the very interesting applications at Munich's New Neutron Source will be neutron tomography. It will be used both for research and industry. The D2O moderated high flux reactor will provide thermal neutrons for the structural analysis of specimen up to the size of 1m. A central problem is the design of the beam geometry, especially the layout of

F Grünauer; B Schillinger; E Steichele

2004-01-01

229

Production of ultra-cold neutrons using Doppler-shifted Bragg scattering and an intense pulsed neutron spallation source  

Microsoft Academic Search

An analytic and a computer generated simulation of the production of Ultra-Cold Neutrons (UCN) is presented using Bragg scattering from a moving crystal to Doppler shift higher velocity neutrons into the UCN region. The calculation was carried out with a view toward its application at the Intense Pulsed Neutron Source (IPNS) now under construction at Argonne National Laboratory. This method

T. W. Dombeck; J. W. Lynn; S. Werner; T. Brun; J. Carpenter; V. Krohn; R. Ringo

1979-01-01

230

Target Operational Experience at the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) has operated at unprecedented power levels for a short-pulse spallation source. Target operations have been successful but not without difficulties. Three targets out of the eight used to date have ended life unexpectedly causing interruptions to the neutron science users. The first of a kind mercury target design experiences beam-pulse induced cavitation damage that is suspected in one of the target leaks. The two other targets suffered early failures due to defective welds. Diagnosing the causes of target leaks and understanding of the progression of cavitation erosion and radiation damage effects has made use of post-irradiation examination (PIE) capabilities. As a result of PIE, review of quality assurance practices and related investigations, design changes are being implemented and manufacturing oversight improved. This paper describes SNS target operating experience, including the more important observations and lessons learned.

Riemer, Bernie [ORNL] [ORNL; Janney, Jim G [ORNL] [ORNL; Kaminskas, Saulius [ORNL] [ORNL; McClintock, David A [ORNL] [ORNL; Rosenblad, Peter M [ORNL] [ORNL

2013-01-01

231

Dynamics of a self-gravitating neutron source  

SciTech Connect

We examine the dynamics of a self-gravitating magnetized neutron gas as a source of a Bianchi I spacetime described by the Kasner metric. The set of Einstein-Maxwell field equations can be expressed as a dynamical system in a 4-dimensional phase space. Numerical solutions of this system reveal the emergence of a point-like singularity as the final evolution state for a large class of physically motivated initial conditions. Besides the theoretical interest of studying this source in a fully general relativistic context, the resulting idealized model could be helpful in understanding the collapse of local volume elements of a neutron gas in the critical conditions that would prevail in the center of a compact object.

Paret, D. Manreza [Departamento de Física General, Facultad de Física, Universidad de la Habana, San Lázaro y L, CP-10400, La Habana (Cuba); Martínez, A. Pérez; Rey, A. Ulacia [Departamento de Física Teórica, Instituto de Cibernética, Matemática y Física, ICIMAF, Calle E No-309 Vedado, CP-10400, La Habana (Cuba); Sussman, Roberto A., E-mail: dmanreza@fisica.uh.cu, E-mail: aurora@icmf.inf.cu, E-mail: alain@icmf.inf.cu, E-mail: sussman@nucleares.unam.mx [Departamento de Gravitación y Teorías de Campo, Instituto de Ciencias Nucleares, ICN, Universidad Autónoma de México UNAM, DF. 04510 (Mexico)

2010-03-01

232

Inertial electrostatic confinement fusion neutron source R & D and issues  

Microsoft Academic Search

An inertial electrostatic confinement (IEC) fusion is the scheme of injecting the ions and electrons toward the spherical center, trapping both species in the electrostatic self-field and giving rise to fusion reactions in the dense core. An IEC is expected to have wide application from a small neutron source to a D-³He fusion reactor. Hirsch reported 10⁹ n\\/s deuterium-tritium (D-T)

Masami Ohnishi; Yasushi Yamamoto; Mitsunori Hasegawa

1997-01-01

233

Obsidian sources characterized by neutron-activation analysis.  

PubMed

Concentrations of elements such as manganese, scandium, lanthanum, rubidium, samarium, barium, and zirconium in obsidian samples from different flows show ranges of 1000 percent or more, whereas the variation in element content in obsidian samples from a single flow appears to be less than 40 percent. Neutron-activation analysis of these elements, as well as of sodium and iron, provides a means of identifying the geologic source of an archeological artifact of obsidian. PMID:17776740

Gordus, A A; Wright, G A; Griffin, J B

1968-07-26

234

Shielding Design of the Spallation Neutron Source (SNS)  

Microsoft Academic Search

The shielding design is important for the construction of an intense high-energy accelerator facility like the;\\u000aproposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance;\\u000aoperations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A;\\u000acalculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional

Johnson

1998-01-01

235

The Advanced Neutron Source research and development plan  

SciTech Connect

The Advanced Neutron Source (ANS) is being designed as a user-oriented neutron research laboratory centered around the most intense continuous beams of thermal and subthermal neutrons in the world. The ANS will be built around a new research reactor of {approximately} 330 MW fission power, producing an unprecedented peak thermal flux of > 7 {times} 10{sup 19} M{sup {minus}2} {center_dot} S{sup {minus}1}. Primarily a research facility, the ANS will accommodate more than 1000 academic, industrial, and government researchers each year. They will conduct basic research in all branches of science-as well as applied research-leading to better understanding of new materials, including high temperature super conductors, plastics, and thin films. Some 48 neutron beam stations will be set up in the ANS beam rooms and the neutron guide hall for neutron scattering and for fundamental and nuclear physics research. There also will be extensive facilities for materials irradiation, isotope production, and analytical chemistry. The R&D program will focus on the four objectives: Address feasibility issues; provide analysis support; evaluate options for improvement in performance beyond minimum requirements; and provide prototype demonstrations for unique facilities. The remainder of this report presents (1) the process by which the R&D activities are controlled and (2) a discussion of the individual tasks that have been identified for the R&D program, including their justification, schedule and costs. The activities discussed in this report will be performed by Martin Marietta Energy Systems, Inc. (MMES) through the Oak Ridge National Laboratory (ORNL) and through subcontracts with industry, universities, and other national laboratories. It should be noted that in general a success path has been assumed for all tasks.

Selby, D.L.

1992-11-30

236

The Advanced Neutron Source research and development plan  

SciTech Connect

The Advanced Neutron Source (ANS) is being designed as a user-oriented neutron research laboratory centered around the most intense continuous beams of thermal and subthermal neutrons in the world. The ANS will be built around a new research reactor of [approximately] 330 MW fission power, producing an unprecedented peak thermal flux of > 7 [times] 10[sup 19] M[sup [minus]2] [center dot] S[sup [minus]1]. Primarily a research facility, the ANS will accommodate more than 1000 academic, industrial, and government researchers each year. They will conduct basic research in all branches of science-as well as applied research-leading to better understanding of new materials, including high temperature super conductors, plastics, and thin films. Some 48 neutron beam stations will be set up in the ANS beam rooms and the neutron guide hall for neutron scattering and for fundamental and nuclear physics research. There also will be extensive facilities for materials irradiation, isotope production, and analytical chemistry. The R D program will focus on the four objectives: Address feasibility issues; provide analysis support; evaluate options for improvement in performance beyond minimum requirements; and provide prototype demonstrations for unique facilities. The remainder of this report presents (1) the process by which the R D activities are controlled and (2) a discussion of the individual tasks that have been identified for the R D program, including their justification, schedule and costs. The activities discussed in this report will be performed by Martin Marietta Energy Systems, Inc. (MMES) through the Oak Ridge National Laboratory (ORNL) and through subcontracts with industry, universities, and other national laboratories. It should be noted that in general a success path has been assumed for all tasks.

Selby, D.L.

1992-11-30

237

Elemental composition in sealed plutonium-beryllium neutron sources.  

PubMed

Five sealed plutonium-beryllium (PuBe) neutron sources from various manufacturers were disassembled. Destructive chemical analyses for recovered PuBe materials were conducted for disposition purposes. A dissolution method for PuBe alloys was developed for quantitative plutonium (Pu) and beryllium (Be) assay. Quantitation of Be and trace elements was performed using plasma based spectroscopic instruments, namely inductively coupled plasma mass spectrometry (ICP-MS) and atomic emission spectrometry (ICP-AES). Pu assay was accomplished by an electrochemical method. Variations in trace elemental contents among the five PuBe sources are discussed. PMID:25464182

Xu, N; Kuhn, K; Gallimore, D; Martinez, A; Schappert, M; Montoya, D; Lujan, E; Garduno, K; Tandon, L

2014-10-22

238

A shielding design for an accelerator-based neutron source for boron neutron capture therapy.  

PubMed

Research in boron neutron capture therapy (BNCT) at The Ohio State University Nuclear Engineering Department has been primarily focused on delivering a high quality neutron field for use in BNCT using an accelerator-based neutron source (ABNS). An ABNS for BNCT is composed of a proton accelerator, a high-energy beam transport system, a (7)Li target, a target heat removal system (HRS), a moderator assembly, and a treatment room. The intent of this paper is to demonstrate the advantages of a shielded moderator assembly design, in terms of material requirements necessary to adequately protect radiation personnel located outside a treatment room for BNCT, over an unshielded moderator assembly design. PMID:15308187

Hawk, A E; Blue, T E; Woollard, J E

2004-11-01

239

Measurement of uranium and plutonium in solid waste by passive photon or neutron counting and isotopic neutron source interrogation  

SciTech Connect

A summary of the status and applicability of nondestructive assay (NDA) techniques for the measurement of uranium and plutonium in 55-gal barrels of solid waste is reported. The NDA techniques reviewed include passive gamma-ray and x-ray counting with scintillator, solid state, and proportional gas photon detectors, passive neutron counting, and active neutron interrogation with neutron and gamma-ray counting. The active neutron interrogation methods are limited to those employing isotopic neutron sources. Three generic neutron sources (alpha-n, photoneutron, and /sup 252/Cf) are considered. The neutron detectors reviewed for both prompt and delayed fission neutron detection with the above sources include thermal (/sup 3/He, /sup 10/BF/sub 3/) and recoil (/sup 4/He, CH/sub 4/) proportional gas detectors and liquid and plastic scintillator detectors. The instrument found to be best suited for low-level measurements (< 10 nCi/g) is the /sup 252/Cf Shuffler. The measurement technique consists of passive neutron counting followed by cyclic activation using a /sup 252/Cf source and delayed neutron counting with the source withdrawn. It is recommended that a waste assay station composed of a /sup 252/Cf Shuffler, a gamma-ray scanner, and a screening station be tested and evaluated at a nuclear waste site. 34 figures, 15 tables.

Crane, T.W.

1980-03-01

240

Advanced Neutron Source: Plant Design Requirements. Revision 4  

SciTech Connect

The Advanced Neutron Source will be a new world-class facility for research using hot, thermal, cold, and ultra-cold neutrons. The heart of the facility will be a 330-MW (fission), heavy-water cooled and heavy-water moderated reactor. The reactor will be housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides will fan out into a large guide hall, housing about 30 neutron research stations. Appropriate office, laboratory, and shop facilities will be included to provide a complete facility for users. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory early in the next decade. This PDR document defines the plant-level requirements for the design, construction, and operation of ANS. It also defines and provides input to the individual System Design Description (SDD) documents. Together, this PDR document and the set of SDD documents will define and control the baseline configuration of ANS.

Not Available

1990-07-01

241

Methods for lipid nanostructure investigation at neutron and synchrotron sources  

NASA Astrophysics Data System (ADS)

A lipid membrane is a main component of biological membranes. Contemporary bionanotechnologies use phospholipids and ceramides as basic components of drugs and cosmetic preparations. Phospholipids-based nanoparticles are used as drug carriers. Effective development of bionanotechnologies in Russia calls for creation of physical methods to diagnose the particle nanostructure which would be promising for application in pharmacology. Radiation with wavelengths of 1-10 Å is an adequate instrument for detecting the nanostructure of lipid bi- and monolayers. The review deals with methods that apply neutron scattering and synchrotron radiation for studying nanostructures of lipid membranes, phospholipid nanoparticles, and phospholipid monolayers on a water surface by techniques of diffraction, small-angle scattering, and reflectometry. The importance of the mutually complementary application of neutron and synchrotron radiation for solving urgent problems of membrane biophysics, microbiology, dermapharmacology, and bionanotechnologies is demonstrated by particular examples of studies of phospholipid membranes and ceramide-based membranes. The efficiency of development and application of new methods for solving urgent problems of biophysics is shown. The review is written on the basis of results obtained over the period of 1999-2010 at the Joint Institute for Nuclear Research (JINR) Laboratory of Neutron Physics in collaboration with the Pharmaceutical Departments of universities of France (Paris-Sud, Chatenay Malabry) and Germany (Martin Luther University, Halle). The experiments were performed at various European and Russian neutron and synchrotron sources.

Kiselev, M. A.

2011-03-01

242

Thermal neutron transport near a moderator discontinuity using the method of weighted residuals - II. Cold neutron sources  

Microsoft Academic Search

Using the method of weighted residuals, a detailed numerical study is made of the neutronics of spherical cold neutron sources composed of liquid hydrogen and liquid deuterium in reactor moderators of light water, heavy water and graphite. Particular attention is paid to the physical effects at the cold source boundary. The computations allow a number of conclusions to be made

J. R. Moon; T. D. Beynon

1973-01-01

243

The continued development of the Spallation Neutron Source external antenna H{sup -} ion source  

SciTech Connect

The U.S. Spallation Neutron Source (SNS) is an accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to ensure that the SNS will meet its operational commitments as well as provide for future facility upgrades with high reliability, we are developing a rf-driven, H{sup -} ion source based on a water-cooled, ceramic aluminum nitride (AlN) plasma chamber. To date, early versions of this source have delivered up to 42 mA to the SNS front end and unanalyzed beam currents up to {approx}100 mA (60 Hz, 1 ms) to the ion source test stand. This source was operated on the SNS accelerator from February to April 2009 and produced {approx}35 mA (beam current required by the ramp up plan) with availability of {approx}97%. During this run several ion source failures identified reliability issues, which must be addressed before the source re-enters production: plasma ignition, antenna lifetime, magnet cooling, and cooling jacket integrity. This report discusses these issues, details proposed engineering solutions, and notes progress to date.

Welton, R. F.; Carmichael, J.; Fuga, R.; Goulding, R. H.; Han, B.; Kang, Y.; Lee, S. W.; Murray, S. N.; Pennisi, T.; Potter, K. G.; Santana, M.; Stockli, M. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States); Desai, N. J. [Worcester Polytechnic Institute, Worcester, Massachusetts 01609 (United States)

2010-02-15

244

A multilayer ultracold neutron turbine source for a long-pulse spallation source  

NASA Astrophysics Data System (ADS)

We have developed a concept for an ultracold neutron (UCN) turbine source based on a long-pulse spallation source. Using a single reflection from a receding blade, the turbine converts cold neutrons from the primary moderator to UCN. The UCN pulse length is spread out in time and is comparable to the primary pulse interval, producing a quasi-continuous UCN source. The principal parameters for such a design are the primary source pulse length, the flight path distance, and the velocity acceptance interval of the reflector. Taking advantage of recent advances in multilayer reflector preparation, we propose W? 11B 4C multilayer reflectors with a high-reflectivity plateau in the velocity range of 80±5 m/s. We have simulated a multilayer turbine which converts 160±5 m/s neutrons from a 1 ms primary source with a 2.5 m incident flight path to UCN with an efficiency, in terms of phase space density, of about 4.4%. For a ˜1 MW long-pulse spallation source with 1 ms pulse length and 60 Hz frequency, and a time average flux in a liquid hydrogen moderator of 1 × 10 14 n/cm 2 s, this corresponds to a UCN source flux of 1.9 × 10 5 n/cm 2 s, a total UCN current of 3.3 × 10 7 n/s, and a UCN density (for velocity ?6.2 m/s) of 500 n/cm 3.

Crow, M. L.; Esibov, L.; Steyerl, A.

1997-02-01

245

Test facility for a neutron induced positron source  

NASA Astrophysics Data System (ADS)

At the research reactor FRM of the Technical University of Munich, an in-pile intensive slow positron source was developed. Neutron capture gamma rays created by 113Cd(n, ?) 114Cd convert into e +-e - pairs by gamma absorption in tungsten foils. Moderated positrons are emitted from the foil surface and accelerated by electric lenses to a few keV. The positron beam is guided to a remoderation stage outside the reactor pool by a magnetic solenoid. In order to test various improvements of the experimental set-up the positron source was positioned at the accessible end of an external neutron guide outside the reactor building. To minimize background, a curved beam tube was installed at the end of the beamline. A germanium detector was used to measure the annihilation signal of the incoming positrons. This facility allows to optimize acceleration potentials and guide fields, as well as settings of earth magnetic compensation. With a continuous flux of 4×10 7 neutrons/cm 2s, the intensity of the primary positron beam was about 10 2 slow positrons per second. Recently, the profile of the positron beam, as well as photo electrons emitted from the tungsten foils, were studied by a space-resolving micro channel plate detector combined with a fluorescent screen and a CCD-camera.

Straßer, B.; Springer, M.; Hugenschmidt, C.; Schreckenbach, K.

1999-08-01

246

Conceptual design for one megawatt spallation neutron source at Argonne  

SciTech Connect

A feasibility study of a spallation neutron source based on a rapid-cycling synchrotron which delivers a proton beam of 2 GeV in energy and 0.5 mA time-averaged current at a 30 Hz repetition rate is presented. The lattice consists of 90-degree phase advance FODO cells with dispersion-free straight sections, and has a three-fold symmetry. The ring magnet system will be energized by 20 Hz and 60 Hz resonant circuits to decrease the dB/dt during the acceleration cycle. This lowers the peak acceleration voltage requirement to 130 kV. The single turn extraction system will be used to extract the beam alternatively to two target stations. The first station will operate at 10 Hz for research using long wavelength neutrons, and the second station will use the remaining pulses, collectively, providing 36 neutron beams. The 400 MeV negative-hydrogen-ion injector linac consists of an ion source, rf quadrupole, matching section, 100 MeV drift-tube linac, and a 300 MeV coupled-cavity linac.

Cho, Y.; Bailey, J.; Brown, B. [and others

1993-12-31

247

Small-angle neutron scattering at pulsed spallation sources  

SciTech Connect

The importance of small-angle neutron scattering (SANS) in biological, chemical, physical, and engineering research mandates that all intense neutron sources be equipped with SANS instruments. Four existing instruments are described, and the general differences between pulsed-source and reactor-based instrument designs are discussed. The basic geometries are identical, but dynamic range is achieved by using a broad band of wavelengths (with time-of-flight analysis) rather than by moving the detector. This allows a more optimized collimation system. Data acquisition requirements at a pulsed source are more severe, requiring large, fast histogramming memories. Data reduction is also more complex, as all wave length-dependent and angle-dependent backgrounds and non-linearities must be accounted for before data can be transformed to intensity vs Q. A comparison is shown between the Los Alamos pulsed instrument and D-11 (Institute Laue-Langevin), and examples from the four major topics of the conference are shown. The general conclusion is that reactor-based instruments remain superior at very low Q or if only a narrow range of Q is required, but that the current generation of pulsed-source instruments is competitive at moderate Q and may be faster when a wide range of Q is required. In principle, a user should choose which facility to use on the basis of optimizing the experiment; in practice the tradeoffs are not severe and the choice is usually made on the basis of availability.

Seeger, P.A.; Hjelm, R.P. Jr.

1990-01-01

248

Spallation neutron source saddle antenna H{sup -} ion source project  

SciTech Connect

In this project we are developing an H{sup -} source which will synthesize the most important developments in the field of negative ion sources to provide high current, high brightness, good lifetime, high reliability, and high power efficiency. We describe two planned modifications to the present spallation neutron source external antenna source in order to increase the plasma density near the output aperture: (1) replacing the present 2 MHz plasma-forming solenoid antenna with a 13 MHz saddle-type antenna and (2) replacing the permanent multicusp magnetic system with a weaker electromagnet.

Dudnikov, Vadim; Johnson, Rolland P. [Muons, Inc., Batavia, Illinois 60510 (United States); Dudnikova, Galina [University of Maryland, College Park, Maryland 20742 (United States); Stockli, Martin; Welton, Robert [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2010-02-15

249

Tomsk Polytechnic University cyclotron as a source for neutron based cancer treatmenta)  

NASA Astrophysics Data System (ADS)

In this paper we present our cyclotron based neutron source with average energy 6.3 MeV generated during the 13.6 MeV deuterons interactions with beryllium target, neutron field dosimetry, and dosimetry of attendant gamma fields. We also present application of our neutron source for cancer treatment.

Lisin, V. A.; Bogdanov, A. V.; Golovkov, V. M.; Musabaeva, L. I.; Sukhikh, L. G.; Verigin, D. A.

2014-02-01

250

Tomsk Polytechnic University cyclotron as a source for neutron based cancer treatment  

SciTech Connect

In this paper we present our cyclotron based neutron source with average energy 6.3 MeV generated during the 13.6 MeV deuterons interactions with beryllium target, neutron field dosimetry, and dosimetry of attendant gamma fields. We also present application of our neutron source for cancer treatment.

Lisin, V. A. [Cancer Research Institute, 5 Kooperativny St., Tomsk 634050 (Russian Federation) [Cancer Research Institute, 5 Kooperativny St., Tomsk 634050 (Russian Federation); Tomsk Polytechnic University, 30 Lenina av., Tomsk 634050 (Russian Federation); Bogdanov, A. V.; Golovkov, V. M.; Sukhikh, L. G.; Verigin, D. A., E-mail: verigin@tpu.ru [Tomsk Polytechnic University, 30 Lenina av., Tomsk 634050 (Russian Federation); Musabaeva, L. I. [Cancer Research Institute, 5 Kooperativny St., Tomsk 634050 (Russian Federation)] [Cancer Research Institute, 5 Kooperativny St., Tomsk 634050 (Russian Federation)

2014-02-15

251

Accumulator ring lattice for the national spallation neutron source  

SciTech Connect

The Accumulator Ring for the proposed National Spallation Neutron Source (NSNS) is to accept a 1.03 millisecond beam pulse from a 1 GeV Proton Linac at a repetition rate of 60 Hz. For each beam pulse, 10{sup 14} protons are to be accumulated via charge-exchange injection. A 295 nanosecond gap in the beam, maintained by an rf system, will allow for extraction to an external target for the production of neutrons by spallation. This paper describes the four-fold symmetric lattice that has been chosen for the ring. The lattice contains four long dispersion-free straight sections to accomodate injection, extraction, rf cavities, and beam scraping respectively. The four-fold symmetry allows for easy adjustment of the tunes and flexibility in the placement of correction elements, and ensures that potentially dangerous betatron structure resonances are avoided.

Gardner, C.J.; Lee, Y.Y.; Luccio, A.U.

1997-08-01

252

Advanced Neutron Source Reactor thermal analysis of fuel plate defects  

SciTech Connect

The Advanced Neutron Source Reactor (ANSR) is a research reactor designed to provide the highest continuous neutron beam intensity of any reactor in the world. The present technology for determining safe operations were developed for the High Flux Isotope Reactor (HFIR). These techniques are conservative and provide confidence in the safe operation of HFIR. However, the more intense requirements of ANSR necessitate the development of more accurate, but still conservative, techniques. This report details the development of a Local Analysis Technique (LAT) that provides an appropriate approach. Application of the LAT to two ANSR core designs are presented. New theories of the thermal and nuclear behavior of the U{sub 3}Si{sub 2} fuel are utilized. The implications of lower fuel enrichment and of modifying the inspection procedures are also discussed. Development of the computer codes that enable the automate execution of the LAT is included.

Giles, G.E.

1995-08-01

253

Review of the Advanced Neutron Source (ANS) materials irradiation facilities  

SciTech Connect

The purpose of the workshop was to document as accurately as possible the present and future needs for neutron irradiation capacity and facilities as related to the design of the Advanced Neutron Source (ANS) which will be the next generation steady-state research reactor. The report provides the findings and recommendations of the working group. After introductory and background information is presented, the discussion includes the status of the ANS design, in particular in-core materials irradiation facilities design and important experimental parameters. The summary of workshop discussions describes a survey of irradiation-effects research community and opportunities for ex-core irradiation facilities. 20 refs., 2 figs., 4 tabs. (MHB)

Goland, A.N. (Brookhaven National Lab., Upton, NY (USA))

1991-03-01

254

Inertial electrostatic confinement fusion neutron source R & D and issues  

SciTech Connect

An inertial electrostatic confinement (IEC) fusion is the scheme of injecting the ions and electrons toward the spherical center, trapping both species in the electrostatic self-field and giving rise to fusion reactions in the dense core. An IEC is expected to have wide application from a small neutron source to a D-{sup 3}He fusion reactor. Hirsch reported 10{sup 9} n/s deuterium-tritium (D-T) neutron production in the device equipped with ion guns. Recently, Gu et al. measured 10{sup 6} n/s using a D{sub 2} gas discharge between the spherical wire cathode and the anode vacuum vessel, where the applied voltage is 60 kV and the current is 15 mA. We have also obtained similar neutron production at a lower voltage, {approximately}45 kV in a single-grid IEC device. Fusion reaction rates obtained by IEC experiments so far cannot be explained by a model of a simple potential well structure because the electrical potential peaked at the center prevents making a dense core. Hirsch proposed a multiwell structure called {open_quotes}poissors{close_quotes} to explain the experiments. It is generally believed that there may be some correlation between the potential well structure and the neutron production rate. The scaling of neutron production on the injected ion current is a most important aspect of the problem for the prospect of utilizing IEC for fusion energy. The potential structure and its behavior are keys to the physics in understanding the principle of an IEC.

Ohnishi, Masami; Yamamoto, Yasushi; Hasegawa, Mitsunori [Kyoto Univ. (Japan)] [and others

1997-12-01

255

An Ultracold Neutron Source for 1. Introduction to Ultracold Neutrons (UCN)  

E-print Network

astrophysics ­ BBN ­ r-process surface physics development towards JPARC 2nd target station UCN source #12 interacts with free neutron (UCN) target. 132Sn current 5e17 /s UCN density 2e4 /cc meter-long target sigma-II R. Golub, NCSU B. Filippone, Caltech P. Huffman, NCSU T. Ito, LANL E. Korobkina, NCSU C.-Y. Liu, Ind

Martin, Jeff

256

Finite element analysis of advanced neutron source fuel plates  

SciTech Connect

The proposed design for the Advanced Neutron Source reactor core consists of closely spaced involute fuel plates. Coolant flows between the plates at high velocities. It is vital that adjacent plates do not come in contact and that the coolant channels between the plates remain open. Several scenarios that could result in problems with the fuel plates are studied. Finite element analyses are performed on fuel plates under pressure from the coolant flowing between the plates at a high velocity, under pressure because of a partial flow blockage in one of the channels, and with different temperature profiles.

Luttrell, C.R.

1995-08-01

257

Neutron source capability assessment for cumulative fission yields measurements  

SciTech Connect

A recent analysis of high-quality cumulative fission yields data for Pu-239 published in the peer-reviewed literature showed that the quoted experimental uncertainties do not allow a clear statement on how the fission yields vary as a function of energy. [Prussin2009] To make such a statement requires a set of experiments with well 'controlled' and understood sources of experimental errors to reduce uncertainties as low as possible, ideally in the 1 to 2% range. The Inter Laboratory Working Group (ILWOG) determined that Directed Stockpile Work (DSW) would benefit from an experimental program with the stated goal to reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Following recent discussions between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), there is a renewed interest in developing a concerted experimental program to measure fission yields in a neutron energy range from thermal energy (0.025 eV) to 14 MeV with an emphasis on discrete energies from 0.5 to 4 MeV. Ideally, fission yields would be measured at single energies, however, in practice there are only 'quasi-monoenergetic' neutrons sources of finite width. This report outlines a capability assessment as of June 2011 of available neutron sources that could be used as part of a concerted experimental program to measure cumulative fission yields. In a framework of international collaborations, capabilities available in the United States, at the Atomic Weapons Establishment (AWE) in the United Kingdom and at the Commissariat Energie Atomique (CEA) in France are listed. There is a need to develop an experimental program that will reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Fission and monoenergetic neutron sources are available that could support these fission yield experiments in the US, as well as at AWE and CEA. Considerations that will impact the final choice of experimental venues are: (1) Availability during the timeframe of interest; (2) Ability to accommodate special nuclear materials; (3) Cost; (4) Availability of counting facilities; and (5) Expected experimental uncertainties.

Descalle, M A; Dekin, W; Kenneally, J

2011-04-06

258

Advanced Neutron Source (ANS) Project. Progress report FY 1993  

SciTech Connect

This report covers the progress made in 1993 in the following sections: (1) project management; (2) research and development; (3) design and (4) safety. The section on research and development covers the following: (1) reactor core development; (2) fuel development; (3) corrosion loop tests and analysis; (4) thermal-hydraulic loop tests; (5) reactor control and shutdown concepts; (6) critical and subcritical experiments; (7) material data, structure tests, and analysis; (8) cold source development; (9) beam tube, guide, and instrument development; (10) neutron transport and shielding; (11) I and C research and development; and (12) facility concepts.

Campbell, J.H. [ed.; Selby, D.L.; Harrington, R.M. [Oak Ridge National Lab., TN (United States); Thompson, P.B. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States). Engineering Div.

1994-01-01

259

The flow mechanism in the Chalk based on radio-isotope analyses of groundwater in the London Basin  

USGS Publications Warehouse

14C analyses of groundwaters from the Chalk of the London Basin are re-interpreted and the age of the groundwater is revised. Radio-isotope analyses are used to examine the flow mechanism in the aquifer. The evidence supports the view that a network of micro-fissures and larger intergranular pores in the matrix provides a significant part of the water pumped from Chalk wells and the major fissures distribute the water to the wells. Most of the matrix is fine-grained and contains a very old water. This diffuses into the micro-fissures and larger pores and is carried to the wells by the major fissures. ?? 1979.

Downing, R.A.; Pearson, F.J.; Smith, D.B.

1979-01-01

260

Emittance studies of the Spallation Neutron Source external-antenna H{sup -} ion source  

SciTech Connect

A new Allison-type emittance scanner has been built to characterize the ion sources and low energy beam transport systems at Spallation Neutron Source. In this work, the emittance characteristics of the H{sup -} beam produced with the external-antenna rf-driven ion source and transported through the two-lens electrostatic low energy beam transport are studied. The beam emittance dependence on beam intensity, extraction parameters, and the evolution of the emittance and twiss parameters over beam pulse duration are presented.

Han, B. X.; Stockli, M. P.; Welton, R. F.; Pennisi, T. R.; Murray, S. N.; Santana, M.; Long, C. D. [Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2010-02-15

261

Generalization of the analytical solution of neutron point kinetics equations with time-dependent external source  

NASA Astrophysics Data System (ADS)

Point reactor kinetics equations with one group of delayed neutrons in the presence of the time-dependent external neutron source are solved analytically during the start-up of a nuclear reactor. Our model incorporates the random nature of the source and linear reactivity variation. We establish a general relationship between the expectation values of source intensity and the expectation values of neutron density of the sub-critical reactor by ignoring the term of the second derivative for neutron density in neutron point kinetics equations. The results of the analytical solution are in good agreement with the results obtained with numerical solution.

Seidi, M.; Behnia, S.; Khodabakhsh, R.

2014-09-01

262

Improvements to the internal and external antenna H- ion sources at the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30-40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ˜55 mA of H- beam current (˜1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H- yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented.

Welton, R. F.; Dudnikov, V. G.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Pillar, C.; Santana, M.; Stockli, M. P.; Turvey, M. W.

2014-02-01

263

Improvements to the internal and external antenna H(-) ion sources at the Spallation Neutron Source.  

PubMed

The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30-40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ?55 mA of H(-) beam current (?1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H(-) yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented. PMID:24593575

Welton, R F; Dudnikov, V G; Han, B X; Murray, S N; Pennisi, T R; Pillar, C; Santana, M; Stockli, M P; Turvey, M W

2014-02-01

264

Spallation Neutron Source Accident Terms for Environmental Impact Statement Input  

SciTech Connect

This report is about accidents with the potential to release radioactive materials into the environment surrounding the Spallation Neutron Source (SNS). As shown in Chap. 2, the inventories of radioactivity at the SNS are dominated by the target facility. Source terms for a wide range of target facility accidents, from anticipated events to worst-case beyond-design-basis events, are provided in Chaps. 3 and 4. The most important criterion applied to these accident source terms is that they should not underestimate potential release. Therefore, conservative methodology was employed for the release estimates. Although the source terms are very conservative, excessive conservatism has been avoided by basing the releases on physical principles. Since it is envisioned that the SNS facility may eventually (after about 10 years) be expanded and modified to support a 4-MW proton beam operational capability, the source terms estimated in this report are applicable to a 4-MW operating proton beam power unless otherwise specified. This is bounding with regard to the 1-MW facility that will be built and operated initially. See further discussion below in Sect. 1.2.

Devore, J.R.; Harrington, R.M.

1998-08-01

265

Demonstration of a solid deuterium source of ultra-cold neutrons  

E-print Network

Ultra-cold neutrons (UCN), neutrons with energies low enough to be confined by the Fermi potential in material bottles, are playing an increasing role in measurements of fundamental properties of the neutron. The ability to manipulate UCN with material guides and bottles, magnetic fields, and gravity can lead to experiments with lower systematic errors than have been obtained in experiments with cold neutron beams. The UCN densities provided by existing reactor sources limit these experiments. The promise of much higher densities from solid deuterium sources has led to proposed facilities coupled to both reactor and spallation neutron sources. In this paper we report on the performance of a prototype spallation neutron-driven solid deuterium source. This source produced bottled UCN densities of 145 +/-7 UCN/cm3, about three times greater than the largest bottled UCN densities previously reported. These results indicate that a production UCN source with substantially higher densities should be possible.

A. Saunders; J. M. Anaya; T. J. Bowles; B. W. Filippone; P. Geltenbort; R. E. Hill; M. Hino; S. Hoedl; G. E. Hogan; T. M. Ito; K. W. Jones; T. Kawai; K. Kirch; S. K. Lamoreaux; C. -Y. Liu; M. Makela; L. J. Marek; J. W. Martin; C. L. Morris; R. N. Mortensen; A. Pichlmaier; S. J. Seestrom; A. Serebrov; D. Smith; W. Teasdale; B. Tipton; R. B. Vogelaar; A. R. Young; J. Yuan

2003-12-18

266

H- radio frequency source development at the Spallation Neutron Sourcea)  

NASA Astrophysics Data System (ADS)

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent ˜38 mA peak current in the linac and an availability of ˜90%. H- beam pulses (˜1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, ˜60 kW) of a copper antenna that has been encased with a thickness of ˜0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of ˜99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of ˜75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to ˜100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

Welton, R. F.; Dudnikov, V. G.; Gawne, K. R.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Roseberry, R. T.; Santana, M.; Stockli, M. P.; Turvey, M. W.

2012-02-01

267

Quantifying time in sedimentary successions by radio-isotopic dating of ash beds  

NASA Astrophysics Data System (ADS)

Sedimentary rock sequences are an accurate record of geological, chemical and biological processes throughout the history of our planet. If we want to know more about the duration or the rates of some of these processes, we can apply methods of absolute age determination, i.e. of radio-isotopic dating. Data of highest precision and accuracy, and therefore of highest degree of confidence, are obtained by chemical abrasion, isotope-dilution, thermal ionization mass spectrometry (CA-ID-TIMS) 238U-206Pb dating techniques, applied to magmatic zircon from ash beds that are interbedded with the sediments. This techniques allows high-precision estimates of age at the 0.1% uncertainty for single analyses, and down to 0.03% uncertainty for groups of statistically equivalent 206Pb/238U dates. Such high precision is needed, since we would like the precision to be approximately equivalent or better than the (interpolated) duration of ammonoid zones in the Mesozoic (e.g., Ovtcharova et al. 2006), or to match short feedback rates of biological, climatic, or geochemical cycles after giant volcanic eruptions in large igneous provinces (LIP's), e.g., at the Permian/Triassic or the Triassic/Jurassic boundaries. We also wish to establish as precisely as possible temporal coincidence between the sedimentary record and short-lived volcanic events within the LIP's. Precision and accuracy of the U-Pb data has to be traceable and quantifiable in absolute terms, achieved by direct reference to the international kilogram, via an absolute calibration of the standard and isotopic tracer solutions. Only with a perfect control on precision and accuracy of radio-isotopic data, we can confidently determine whether two ages of geological events are really different, and avoid mistaking interlaboratory or interchronometer biases for age difference. The development of unprecedented precision of CA-ID-TIMS 238U-206Pb dates led to the recognition of protracted growth of zircon in a magmatic liquid (see, e.g., Schoene et al. 2012), which then becomes transferred into volcanic ashes as excess dispersion of 238U-206Pb dates (see, e.g., Guex et al. 2012). Zircon is crystallizing in the magmatic liquid shortly before the volcanic eruption; we therefore aim at finding the youngest zircon date or youngest statistically equivalent cluster of 238U-206Pb dates as an approximation of ash deposition (Wotzlaw et al. 2013). Time gaps between last zircon crystallization and eruption ("?t") may be as large as 100-200 ka, at the limits of analytical precision. Understanding the magmatic crystallization history of zircon is the fundamental background for interpreting ash bed dates in a sedimentary succession. Ash beds of different stratigraphic position and age my be generated within different magmatic systems, showing different crystallization histories. A sufficient number of samples (N) is therefore of paramount importance, not to lose the stratigraphic age control in a given section, and to be able to discard samples with large ?t - but, how large has to be "N"? In order to use the youngest zircon or zircons as an approximation of the age of eruption and ash deposition, we need to be sure that we have quantitatively solved the problem of post-crystallization lead loss - but, how can we be sure?! Ash bed zircons are prone to partial loss of radiogenic lead, because the ashes have been flushed by volcanic gases, as well as brines during sediment compaction. We therefore need to analyze a sufficient number of zircons (n) to be sure not to miss the youngest - but, how large has to be "n"? Analysis of trace elements or oxygen, hafnium isotopic compositions in dated zircon may sometimes help to distinguish zircon that is in equilibrium with the last magmatic liquid, from those that are recycled from earlier crystallization episodes, or to recognize zircon with partial lead loss (Schoene et al. 2010). Respecting these constraints, we may arrive at accurate correlation of periods of global environmental and biotic disturbance (from ash bed analysis

Schaltegger, Urs

2014-05-01

268

The investigation of renovascular hypertension in children: the accuracy of radio-isotopes in detecting renovascular disease.  

PubMed

Renovascular disease is an important cause of hypertension in children because it is potentially treatable by surgical or angioplasty techniques. The aim of this study was to assess the accuracy of radio-isotopes (DMSA, DTPA and MAG3) combined with the angiotensin converting enzyme inhibitor, captopril, in detecting children with renovascular hypertension. We retrospectively reviewed the ultrasound and pre- and post-captopril radionuclide studies (either DMSA and/or DPTA and/or MAG3) of children with sustained hypertension investigated at our institution. Renal angiography was used as the 'reference technique'. Thirty-nine children, over a period of 10 years, were evaluated: 17 (44%) children had renovascular disease that involved the proximal three divisions of the renal arteries, some of which were amenable to treatment. The overall sensitivity, specificity, positive predictive value and negative predictive value for detecting such renovascular disease, as assessed by changes between pre- and post-captopril radio-isotope studies, were disappointing at 59%, 68%, 59% and 68%, respectively. When considering only abnormalities in post-captopril studies, these indices were 82%, 41%, 52% and 75%, respectively. Three children with potentially treatable renovascular disease were not identified on the captopril studies. We conclude that renal angiography should remain the 'reference technique' in identifying children suspected of renovascular hypertension. PMID:9423201

Ng, C S; de Bruyn, R; Gordon, I

1997-11-01

269

Neutron generators with size scalability, ease of fabrication and multiple ion source functionalities  

SciTech Connect

A neutron generator is provided with a flat, rectilinear geometry and surface mounted metallizations. This construction provides scalability and ease of fabrication, and permits multiple ion source functionalities.

Elizondo-Decanini, Juan M

2014-11-18

270

NEUTRON ACTIVATION ANALYSIS APPLICATIONS AT THE SAVANNAH RIVER SITE USING AN ISOTOPIC NEUTRON SOURCE  

SciTech Connect

NAA using {sup 252}Cf is used to address important areas of applied interest at SRS. Sensitivity needs for many of the applications are not severe; analyses are accomplished using a 21 mg {sup 252}Cf NAA facility. Because NAA allows analysis of bulk samples, it offers strong advantages for samples in difficult-to-digest matrices when its sensitivity is sufficient. Following radiochemical separation with stable carrier addition, chemical yields for a number methods are determined by neutron activation of the stable carrier. In some of the cases where no suitable stable carriers exist, the source has been used to generate radioactive tracers to yield separations.

Diprete, D; C Diprete, C; Raymond Sigg, R

2006-08-14

271

Neutron resonance transmission spectroscopy with high spatial and energy resolution at the J-PARC pulsed neutron source  

NASA Astrophysics Data System (ADS)

The sharp variation of neutron attenuation at certain energies specific to particular nuclides (the lower range being from ~1 eV up to ~1 keV), can be exploited for the remote mapping of element and/or isotope distributions, as well as temperature probing, within relatively thick samples. Intense pulsed neutron beam-lines at spallation sources combined with a high spatial, high-timing resolution neutron counting detector, provide a unique opportunity to measure neutron transmission spectra through the time-of-flight technique. We present the results of experiments where spatially resolved neutron resonances were measured, at energies up to 50 keV. These experiments were performed with the intense flux low background NOBORU neutron beamline at the J-PARC neutron source and the high timing resolution (~20 ns at epithermal neutron energies) and spatial resolution (~55 ?m) neutron counting detector using microchannel plates coupled to a Timepix electronic readout. Simultaneous element-specific imaging was carried out for several materials, at a spatial resolution of ~150 ?m. The high timing resolution of our detector combined with the low background beamline, also enabled characterization of the neutron pulse itself - specifically its pulse width, which varies with neutron energy. The results of our measurements are in good agreement with the predicted results for the double pulse structure of the J-PARC facility, which provides two 100 ns-wide proton pulses separated by 600 ns, broadened by the neutron energy moderation process. Thermal neutron radiography can be conducted simultaneously with resonance transmission spectroscopy, and can reveal the internal structure of the samples. The transmission spectra measured in our experiments demonstrate the feasibility of mapping elemental distributions using this non-destructive technique, for those elements (and in certain cases, specific isotopes), which have resonance energies below a few keV, and with lower resolution for elements with relatively high resonance energies in the 1-30 keV range.

Tremsin, A. S.; Shinohara, T.; Kai, T.; Ooi, M.; Kamiyama, T.; Kiyanagi, Y.; Shiota, Y.; McPhate, J. B.; Vallerga, J. V.; Siegmund, O. H. W.; Feller, W. B.

2014-05-01

272

Study on an inertial electrostatic confinement fusion as a portable neutron source  

Microsoft Academic Search

The scaling of neutron generation versus ion current is important in evaluating the prospect of an inertial electrostatic confinement (IEC) as a neutron source. In this paper, the scaling of neutron generation versus ion current, I, based on the results of both the experiments and the numerical simulations is discussed. The experiments shows the scaling of I2, while the numerical

Masami Ohnishi; Yasushi Yamamoto; Mitsunori Hasegawa; Kiyoshi Yoshikawa; George H. Miley

1998-01-01

273

A new imaging method using pulsed neutron sources for visualizing structural and dynamical information  

Microsoft Academic Search

Neutron imaging using pulsed neutron sources coupled with a 2-dimensional position sensitive detector applicable to the time-of-flight method can give information on the crystal texture of coherently scattering materials, dynamical information of incoherently scattering materials such as hydrogen, and magnetic field information. Bragg edges appeared at cold neutron region reflect the preferred orientation, crystallite size, and lattice spacing. To deduce

Y Kiyanagi; H Sato; T Kamiyama; T Shinohara

2012-01-01

274

Proposal for a New Integrated Circuit and Electronics Neutron Experiment Source at Oak Ridge National Laboratory  

SciTech Connect

Government and customer specifications increasingly require assessments of the single event effects probability in electronics from atmospheric neutrons. The accelerator that best simulates this neutron spectrum is the WNR facility (Los Alamos), but it is underfunded and oversubscribed for present and future needs. A new beam-line is proposed at the Oak Ridge National Laboratory, as part of the Spallation Neutron Source (SNS).

Ferguson, Phillip D [ORNL

2009-01-01

275

A Kinematically Beamed, Low Energy Pulsed Neutron Source for Active Interrogation  

Microsoft Academic Search

We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of SNM (Special Nuclear Materials) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals, (1)

D Dietrich; C Hagmann; P Kerr; L Nakae; M Rowland; N Snyderman; W Stoeffl; R Hamm

2004-01-01

276

Power Burst Reactor Facility as an epithermal neutron source for brain cancer therapy  

Microsoft Academic Search

The Power Burst Facility (PBF) reactor is considered for modification to provide an intense, clean source of intermediate-energy (epithermal) neutrons desirable for clinical studies of neutron capture therapy (NCT) for malignant tumors. The modifications include partial replacement of the reflector, installation of a neutron-moderating, shifting region, additional shielding, and penetration of the present concrete shield with a collimating (and optionally)

Wheeler

1986-01-01

277

A kinematically beamed, low energy pulsed neutron source for active interrogation  

Microsoft Academic Search

We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of special nuclear materials (SNM) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals: (1)

Dan Dietrich; Chris Hagmann; Phil Kerr; Les Nakae; Mark Rowland; Neal Snyderman; Wolfgang Stoeffl; Robert Hamm

2005-01-01

278

On replacing Am-Be neutron sources in compensated porosity logging tools.  

PubMed

Authors explored the direct replacement of Am-Be neutron sources in neutron porosity logging tools through Monte Carlo simulations using MCNP5. (252)Cf and electronic accelerator neutron sources based on the Deuterium-Tritium fusion reaction were considered. Between the sources, a tradeoff was noted between sensitivity to the presence of hydrogen and uncertainty due to counting statistics. It was concluded that both replacement sources as well as accelerator sources based on the Deuterium-Deuterium fusion reaction warrant further consideration as porosity log sources. PMID:20047837

Peeples, Cody R; Mickael, Medhat; Gardner, Robin P

2010-01-01

279

A new time-of-flight neutron reflectometer and SANS instrument GORIZONT at IN-06 spallation neutron source  

NASA Astrophysics Data System (ADS)

A new time-of-flight neutron reflectometer GORIZONT with vertical scattering plane was constructed and tested at the IN-06 spallation pulsed neutron source at the Institute for Nuclear Research RAS. The instrument can be used also as a small angle neutron instrument. Due to the vertical scattering plane it is well-suited for the studies of free-liquid surfaces. A Monte-Carlo simulation and experimental testing of instrument have been performed. The neutron spectra at the guide exit and at the sample position and beam profiles were measured. Based on the experimental data the momentum transfer range and the instrument resolution were estimated.

Litvin, V. S.; Trounov, V. A.; Ulyanov, V. A.; Boulkine, A. P.; Kalinin, S. I.; Alekseev, A. A.; Sadykov, R. A.; Koptelov, E. A.

2012-02-01

280

Materials compatibility studies for the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) is a high power facility for producing neutrons that utilizes flowing liquid mercury inside an austenitic stainless steel container as the target for a 1.0 GeV proton beam. Type 316 SS has been selected as the container material for the mercury and consequences of exposure of 316 SS to radiation, thermal shock, thermal stress, cavitation and hot, flowing mercury are all being addressed by R and D programs. In addition, corrosion studies also include evaluation of Inconel 718 because it has been successfully used in previous spallation neutron systems as a window material. Two types of compatibility issues relative to 316 SS/mercury and Inconel 718/mercury are being examined: (1) liquid metal embrittlement (LME) and (2) temperature gradient mass transfer. Studies have shown that mercury does not easily wet type 316 SS below 275 C. In the LME experiments, attempts were made to promote wetting of the steel by mercury either by adding gallium to the mercury or coating the specimen with a tin-silver solder that the mercury easily wets. The latter proved more reliable in establishing wetting, but there was no evidence of LME in any of the constant extension rate tensile tests either at 23 or 100 C. Inconel 718 also showed no change in room temperature properties when tested in mercury or mercury-gallium. However, there was evidence that the fracture was less ductile. Preliminary evaluation of mass transfer of either type 316 SS or Inconel 718 in mercury or mercury-gallium at 350 C (maximum temperature) did not reveal significant effects. Two 5,000 h thermal convection loop tests of type 316 SS are in progress, with specimens in both hot and cold test regions, at 300 and 240 C, respectively.

DiStefano, J.R.; Pawel, S.J.; Manneschmidt, E.T.

1998-11-01

281

Calculations of radiation damage in target, container and window materials for spallation neutron sources  

SciTech Connect

Radiation damage in target, container, and window materials for spallation neutron sources is am important factor in the design of target stations for accelerator-driver transmutation technologies. Calculations are described that use the LAHET and SPECTER codes to obtain displacement and helium production rates in tungsten, 316 stainless steel, and Inconel 718, which are major target, container, and window materials, respectively. Results are compared for the three materials, based on neutron spectra for NSNS and ATW spallation neutron sources, where the neutron fluxes are normalized to give the same flux of neutrons of all energies.

Wechsler, M.S. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering; Ferguson, P.D.; Sommer, W.F. [Los Alamos National Lab., NM (United States); Mansur, L.K. [Oak Ridge National Lab., TN (United States)

1996-07-01

282

Optimizing Laser-accelerated Ion Beams for a Collimated Neutron Source  

SciTech Connect

High-flux neutrons for imaging and materials analysis applications have typically been provided by accelerator- and reactor-based neutron sources. A novel approach is to use ultraintense (>1018W/cm2) lasers to generate picosecond, collimated neutrons from a dual target configuration. In this article, the production capabilities of present and upcoming laser facilities are estimated while independently maximizing neutron yields and minimizing beam divergence. A Monte-Carlo code calculates angular and energy distributions of neutrons generated by D-D fusion events occurring within a deuterated target for a given incident beam of D+ ions. Tailoring of the incident distribution via laser parameters and microlens focusing modifies the emerging neutrons. Projected neutron yields and distributions are compared to conventional sources, yielding comparable on-target fluxes per discharge, shorter time resolution, larger neutron energies and greater collimation.

C.L. Ellison and J. Fuchs

2010-09-23

283

/sup 252/Cf-source-driven neutron noise analysis method  

SciTech Connect

The /sup 252/Cf-source-driven neutron noise analysis method has been tested in a wide variety of experiments that have indicated the broad range of applicability of the method. The neutron multiplication factor k/sub eff/ has been satisfactorily detemined for a variety of materials including uranium metal, light water reactor fuel pins, fissile solutions, fuel plates in water, and interacting cylinders. For a uranyl nitrate solution tank which is typical of a fuel processing or reprocessing plant, the k/sub eff/ values were satisfactorily determined for values between 0.92 and 0.5 using a simple point kinetics interpretation of the experimental data. The short measurement times, in several cases as low as 1 min, have shown that the development of this method can lead to a practical subcriticality monitor for many in-plant applications. The further development of the method will require experiments oriented toward particular applications including dynamic experiments and the development of theoretical methods to predict the experimental observables.

Mihalczo, J.T.; King, W.T.; Blakeman, E.D.

1985-01-01

284

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.

1994-12-01

285

SPALLATION NEUTRON SOURCE HIGH-POWER PROTECTION MODULE TEST STAND  

SciTech Connect

The Spallation Neutron Source (SNS) High-Power Protection Module (HPM) provides interlocks and fast shutdown for the radio frequency (RF) system to protect the accelerating structures and high power RF (HPRF) Distribution System. The HPM has required some functional upgrades since the start of beam operations and an upgrade to the HPM test stand was required to support these added features. The HPM test stand currently verifies functionality, RF channel calibration, and measurement of the speed of shutdown to ensure the specifications are met. The upgraded test stand was implemented in a Field Programmable Gate Array (FPGA) to allow for future growth and flexibility. Work is currently progressing on automation of the test stand to better perform the required module calibration schedule.

Lee, Sung-Woo [ORNL] [ORNL; Ball, Jeffrey Allen [ORNL] [ORNL; Crofford, Mark T [ORNL] [ORNL; Davidson Jr, Taylor L [ORNL] [ORNL; Jones, Stacey L [ORNL] [ORNL; Hardek, Thomas W [ORNL] [ORNL

2010-01-01

286

Spallation neutron source cryomodule heat loads and thermal design  

SciTech Connect

When complete, the Spallation Neutron Source (SNS) will provide a 1 GeV, 2 MW beam for experiments. One portion of the machine's linac consists of over 80 Superconducting Radio Frequency (SRF) 805 MHz cavities housed in a minimum of 23 cryomodules operating at a saturation temperature of 2.1 K. Minimization of the total heat load is critical to machine performance and for efficient operation of the system. The total heat load of the cryomodules consists of the fixed static load and the dynamic load, which is proportional to the cavity performance. The helium refrigerator supports mainly the cryomodule loads and to a lesser extent the distribution system loads. The estimated heat loads and calculated thermal performance are discussed along with two unique features of this design: the helium heat exchanger housed in the cryomodule return end can and the helium gas cooled fundamental power coupler.

E. F. Daly; V. Ganni; C. H. Rode; W. J. Schneider; K. M. Wilson; M. A. Wiseman

2002-05-10

287

BEAM TRANSFER LINES FOR THE SPALLATION NEUTRON SOURCE.  

SciTech Connect

Beam transfer lines for the Spallation Neutron Source (SNS) are designed to have low beam losses for hand on maintenance while satisfying the facility footprint requirements. There are two main beam transfer lines, High Energy Beam Transport (HEBT) line which connect super conducting linac to the accumulator ring and Ring to Target Beam transport (RTBT) which transfers beam from accumulator ring to the target. HEBT line not only transfer the beam from linac to ring but also prepare beam for ring injection, correct the energy jitter from the linac, provide required energy spread for the ring injection, clean the transverse and longitudinal halo particles from the beam, determine the linac beam quality, and provide the protection to the accumulator ring. RTBT line transport the beam from ring to target while fulfilling the target requirements of beam size, maximum current density, beam moment on the target in case of ring extraction kicker failure. and protect the target from the ring fault conditions.

RAPARIA,D.; LEE,Y.Y.; WENG,W.T.; WEI,J.

2002-04-08

288

Electron-cloud mitigation in the spallation neutron source ring  

SciTech Connect

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H- injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation.

Wei, J.; Blaskiewicz, M.; Brodowski, J.; Cameron, P.; Davino, D.; Fedotov, A.; He, P.; Hseuh, H.; Lee, Y.Y.; Meng, W.; Raparia, D.; Tuozzolo, J.; Zhang, S.Y.; Danilov, V.; Henderson, S.; Furman, M.; Pivi, M.; Macek, R.

2003-05-01

289

Electron Cloud Mitigation in the Spallation Neutron Source Ring  

SciTech Connect

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H{sup -} injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron-cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation.

Wei, J.; Blaskiewicz, Michael; Brodowski, J.; Cameron, P.; Davino, Daniele; Fedotov, A.; He, P.; Hseuh, H.; Lee, Y.Y.; Ludewig, H.; Meng, W.; Raparia, D.; Tuozzolo, J.; Zhang, S.Y.; Catalan-Lasheras, N.; Macek, R.J.; Furman, Miguel A.; Aleksandrov, A.; Cousineau, S.; Danilov, V.; Henderson, S.; /Brookhaven /CERN /LANL, Ctr. for Nonlinear Studies /LBL, Berkeley /Oak Ridge /SLAC

2008-03-17

290

CONSTRUCTION STATUS AND ISSUES OF THE SPALLATION NEUTRON SOURCE RING.  

SciTech Connect

The Spallation Neutron Source (SNS) ring is designed to accumulate beam pulses of 1.5 x 10{sup 14} protons of 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity and power, key design challenges include control of beam loss and radio-activation, construction of high-quality large-aperture magnets and power supplies, design of robust injection and extraction systems, minimization of beam-coupling impedances, and mitigation of electron-cloud effects. This paper discusses the status of the ring systems with emphasis on technical challenges and issues, and presents future perspectives towards a next-generation high-intensity facility.

WEI,J.

2004-07-05

291

Materials for spallation neutron sources, with emphasis on SNS facility  

SciTech Connect

The materials requirements in a high-power spallation neutron source like the SNS are particularly demanding. Materials at the target station are of special concern; these include the containment vessel and protective shroud for the mercury target material, beam windows, support structures, moderator housings, and beam tubes. The material chosen for the mercury containment vessel is Type 316 stainless steel (316SS). This choice is based on the extensive background of experience with 316SS and on its good fabricability and availability. While much has been learned about the effect of radiation on the properties of 316SS, the preponderance of this information stems from fission reactor irradiations, where the average neutron energy is only 1 to 2 MeV and relatively few neutrons are present with energies above {approximately}10 MeV. By contrast, the energies of the spallation neutrons at the SNS extend up to the 1000-MeV energy of the incident protons. However, because of the design of the target module, irradiation creep is not expected to be a significant problem. The major concern is for radiation embrittlement. Mercury is known to be an aggressive medium, and corrosion and compatibility studies for 316SS and INCONEL 718 are included in the research and development program on SNS materials. INCONEL 718 is under consideration as a beam window material. Two issues are receiving particular attention: liquid-metal embrittlement and temperature gradient mass transfer. Constant-strain-rate tensile tests were conducted in mercury and mercury-gallium at 23 C for 316SS and INCONEL 718 and at 100 C for 316SS; in all the tests there was no evidence of liquid metal embrittlement. In addition, preliminary mass transfer tests on 3165SS or INCONEL 718 at temperatures up to 350 C reveled no significant effects. Fatigue tests in mercury have recently been initiated. As a partial simulation of SNS conditions, they provide a more severe probe for possible ductility loss associated with a liquid-metal environment.

Mansur, L.K. [Oak Ridge National Lab., TN (United States)

1999-09-01

292

Initial tests of the Spallation Neutron Source H{sup -} ion source with an external antenna  

SciTech Connect

The ion source for the Spallation Neutron Source (SNS) is a radio-frequency (rf) multicusp source designed to deliver H{sup -} beam pulses of 40 mA to the SNS accelerator with a normalized root-mean-square emittance of less than 0.2{pi} mm mrad, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high-pulse rf power, {approx}50 kW, and high average rf power, {approx}3.5 kW, over a continuous operational period of 3 weeks. During operation at these power levels the plasma-immersed, porcelain-coated rf antenna is susceptible to damage, limiting source lifetime. We are therefore developing an ion source where the plasma is separated from the Cu antenna by an Al{sub 2}O{sub 3} discharge chamber. This article describes the ion source, presents initial beam extraction measurements, and details our ongoing effort to develop this concept into a suitable ion source for the SNS.

Welton, R.F.; Stockli, M.P.; Murray, S.N.; Kang, Y.; Peters, J. [Accelerator Systems Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830-6473 (United States); DESY, Hamburg (Germany)

2006-03-15

293

Advances in the performance and understanding of the Spallation Neutron Source ion source  

SciTech Connect

The ion source developed for the Spallation Neutron Source (SNS) is a radio-frequency, multicusp source designed to produce {approx}40 mA of H{sup -} with a normalized rms emittance of less than 0.2 {pi} mm mrad. To date, the source has been utilized in the commissioning of the SNS accelerator and has already demonstrated stable, satisfactory operation at beam currents of 10-40 mA with duty factors of {approx}0.1% for operational periods of several weeks. Ultimately the SNS facility will require beam duty factors of 6% (1 ms pulse length, 60 Hz repetition rate). To ascertain the capability of the source to deliver beams at this duty factor over sustained periods, ongoing experiments are being performed in which the ion source is continuously operated on a dedicated test stand. The results of these tests are reported as well as a theory of the Cs release and transport processes that was derived from these data. The theory was then employed to develop a more effective source-conditioning procedure and a direct-transfer Cs collar, which led to a considerable improvement in source performance.

Welton, R.F.; Stockli, M.P.; Murray, S.N. [Accelerator Systems Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830-6473 (United States)

2006-03-15

294

On accelerator-based neutron sources and neutron field characterization with low energy neutron spectrometer based on position sensitive 3He counter.  

PubMed

The development of new neutron sources for BNCT applications, based on particle accelerators is currently underway all over the world. Though nuclear reactors were used for a long time as the only neutron source available having the requested flux levels, the accelerator-based ones have recently been investigated on the other hand due to its easy-to-use and acceptable performances. However, when using an accelerator, various secondary particles would be emitted which forms a troublesome background. Moreover, the neutrons produced have usually an energy spectrum somewhat different from the requested one and thus should be largely moderated. An additional issue to be taken into account is the patient positioning, which should be close to the neutron source, in order to take advantage of a neutron flux level high enough to limit the BNCT treatment time within 1h. This implies that, inside a relatively narrow space, neutrons should be moderated, while unnecessary secondary particles should be shielded. Considering that a background-free neutron field from an accelerator-driven neutron source dedicated to BNCT application is generally difficult to be provided, the characterization of such a neutron field will have to be clearly assessed. In the present study, a low energy neutron spectrometer has been thus designed and is now being developed to measure the accelerator-based neutron source performance. The presently proposed spectrometer is based on a (3)He proportional counter, which is 50 cm long and 5 cm in diameter, with a gas pressure of 0.5 MPa. It is quite unique that the spectrometer is set up in parallel with the incident neutron beam and a reaction depth distribution is measured by it as a position sensitive detector. Recently, a prototype detector has been developed and the signal test is now underway. In this paper, the feature of the accelerator-based neutron sources is outlined and importance of neutron field characterization is discussed. And the developed new low energy neutron spectrometer for the characterization is detailed. PMID:19376716

Murata, I; Miyamaru, H; Kato, I; Mori, Y

2009-07-01

295

?-Ray background sources in the VESUVIO spectrometer at ISIS spallation neutron source  

NASA Astrophysics Data System (ADS)

An investigation of the gamma background was carried out in the VESUVIO spectrometer at the ISIS spallation neutron source. This study, performed with a yttrium-aluminum-perovskite (YAP) scintillator, follows high resolution pulse height measurements of the gamma background carried out on the same instrument with the use of a high-purity germanium detector. In this experimental work, a mapping of the gamma background was attempted, trying to find the spatial distribution and degree of directionality of the different contributions identified in the previous study. It is found that the gamma background at low times is highly directional and mostly due to the gamma rays generated in the moderator-decoupler system. The other contributions, consistently to the findings of a previous experiment, are identified as a nearly isotropic one due to neutron absorption in the walls of the experimental hall, and a directional one coming from the beam dump.

Pietropaolo, A.; Perelli Cippo, E.; Gorini, G.; Tardocchi, M.; Schooneveld, E. M.; Andreani, C.; Senesi, R.

2009-09-01

296

Some neutron and gamma radiation characteristics of plutonium cermet fuel for isotopic power sources  

NASA Technical Reports Server (NTRS)

Gamma and neutron measurements on various types of plutonium sources are presented in order to show the effects of O-17, O-18 F-19, Pu-236, age of the fuel, and size of the source on the gamma and neutron spectra. Analysis of the radiation measurements shows that fluorine is the main contributor to the neutron yields from present plutonium-molybdenum cermet fuel, while both fluorine and Pu-236 daughters contribute significantly to the gamma ray intensities.

Neff, R. A.; Anderson, M. E.; Campbell, A. R.; Haas, F. X.

1972-01-01

297

Evaluation of Minimum Neutron Source Strength Required for Ignition of DT Fuel  

Microsoft Academic Search

Minimum thermal and cold neutron source strength necessary for the thermonuclear ignition of D-T fuel using the energy released in exothermic 3He(n, p)T reaction is determined for representative tokamak parameters, when the tokamak inner walls are lined with good thermal neutron reflectors. It is found, that D-T ignition is possible with the help of currently available neutron sources if the

Kanpathipillai Murukesapillai

1992-01-01

298

Final report on Seed Money Project 3210-0346: Feasibility study for californium cold neutron source  

Microsoft Academic Search

A study has been completed of the feasibility and cost of building a cold neutron source that is not dependent on a reactor or accelerator. The neutron source is provided by up to ten ²⁵²Cf capsules, each containing 50 mg of the isotope produced in the High-Flux Isotope Reactor. The neutrons are moderated by heavy water and liquid deuterium to

R. G. Alsmiller; D. L. Henderson; B. H. Montgomery

1988-01-01

299

A portable neutron\\/tunable X-ray source based on inertial electrostatic confinement  

Microsoft Academic Search

Portable neutron sources are of strong interest for uses such as industrial neutron activation analysis and various medical research applications. The inertial electrostatic confinement (IEC) device under development at the University of Illionis is intended for such uses and also provides a tunable X-ray source (required reverse bias and added electron emitters). The IEC operates as an accelerator plasma-target type

George H. Miley

1999-01-01

300

Development of an Ultra-Cold Neutron Source at Los Alamos  

Microsoft Academic Search

The production of ultra cold neutrons (UCN) at a spallation source is quite different than at a reactor. Although the average neutron fluxes are lower than at a reactor, one can take advantage of the short pulse width of the source to produce and store UCN at the peak intensities available, which are comparable to or can exceed that at

S. J. Seestrom; T. J. Bowles; R. Hill; C. L. Morris; G. L. Greene

1996-01-01

301

Computer simulations for rf design of a Spallation Neutron Source external antenna H ion source  

SciTech Connect

Electromagnetic modeling of the multicusp external antenna H ion source for the Spallation Neutron Source SNS has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as . Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

Lee, Sung-Woo [ORNL] [ORNL; Goulding, Richard Howell [ORNL] [ORNL; Kang, Yoon W [ORNL] [ORNL; Shin, Ki [ORNL] [ORNL; Welton, Robert F [ORNL] [ORNL

2010-01-01

302

Inertial-Electrostatic Confinement Neutron\\/Proton Source  

Microsoft Academic Search

There is considerable demand in the scientific community for a neutron generator with an output of 106-108 neutrons\\/second (n\\/s) that can be switched on or off, emit fusion neutrons, be self-calibrating, and offer portable operation. An Inertial Electrostatic Confinement (IEC)-based neutron generator is proposed to meet these needs. In an IEC device, ion beams are injected into a spherical vacuum

G. H. Miley; J. Javedani; Y. Yamamoto; R. Nebel; J. Nadler; Y. Gu; A. Satsangi; P. Heck

1994-01-01

303

Physics Analysis and Optimization Studies for a Fusion Neutron Source Based on a Gas Dynamic Trap  

NASA Astrophysics Data System (ADS)

To further investigate the fusion neutron source based on a gas dynamic trap (GDT), characteristics of the GDT were analyzed and physics analyses were made for a fusion neutron source based on the GDT concept. The prior design of a GDT-based fusion neutron source was optimized based on a refreshed understanding of GDT operation. A two-step progressive development route of a GDT-based fusion neutron source was suggested. Potential applications of GDT are discussed. Preliminary analyses show that a fusion neutron source based on the GDT concept is suitable for plasma-material interaction research, fusion material and subcomponent testing, and capable of driving a proof-of-principle fusion fission hybrid experimental facility.

Du, Hongfei; Chen, Dehong; Duan, Wenxue; Jiang, Jieqiong; Wu, Yican; FDS Team

2014-12-01

304

Characterization of an accelerator neutron source based on the Be(d,n) reaction  

SciTech Connect

Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.

Meadows, J.W.; Smith, D.L.

1992-01-01

305

Characterization of an accelerator neutron source based on the Be(d,n) reaction  

SciTech Connect

Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.

Meadows, J.W.; Smith, D.L.

1992-07-01

306

Neutron source strength measurements for Varian, Siemens, Elekta, and General Electric linear accelerators.  

PubMed

The shielding calculations for high energy (>10 MV) linear accelerators must include the photoneutron production within the head of the accelerator. Procedures have been described to calculate the treatment room door shielding based on the neutron source strength (Q value) for a specific accelerator and energy combination. Unfortunately, there is currently little data in the literature stating the neutron source strengths for the most widely used linear accelerators. In this study, the neutron fluence for 36 linear accelerators, including models from Varian, Siemens, Elekta/Philips, and General Electric, was measured using gold-foil activation. Several of the models and energy combinations had multiple measurements. The neutron fluence measured in the patient plane was independent of the surface area of the room, suggesting that neutron fluence is more dependent on the direct neutron fluence from the head of the accelerator than from room scatter. Neutron source strength, Q, was determined from the measured neutron fluences. As expected, Q increased with increasing photon energy. The Q values ranged from 0.02 for a 10 MV beam to 1.44(x10(12)) neutrons per photon Gy for a 25 MV beam. The most comprehensive set of neutron source strength values, Q, for the current accelerators in clinical use are presented for use in calculating room shielding. PMID:12841788

Followill, David S; Stovall, Marilyn S; Kry, Stephen F; Ibbott, Geoffrey S

2003-01-01

307

Materials Compatibility Studies for the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) is a high power facility for producing neutrons that utilizes flowing liquid mercury inside an austenitic stainless steel container as the target for a 1.0 GeV proton beam. The energy deposited in the target is transported by two separate mercury flow streams: one to transport heat in the interior target region and one to cool the stainless steel container. Three-dimensional computational fluid dynamics simulations have been performed to predict temperature, velocity, and pressure distributions in the target. Results have generally shown that the power deposited in the bulk mercury can be effectively transported with reasonable flow rates and the bulk mercury temperature should not exceed 160{deg}C. Assuming good thermal contact, the maximum stainless steel wall temperature should be 130 {deg}C. Type 316 SS has been selected as the container material for the mercury and consequences of exposure of 316 SS to radiation, thermal shock, thermal stress, cavitation and hot, flowing mercury are all being addressed by R&D programs. In addition, corrosion studies include evaluation of Inconel 718 because it has been successfully used in previous water cooled spallation neutron systems as a window material. With type 316 SS selected to contain the mercury target of the SNS, two types of compatibility issues have been examined: LME and temperature gradient mass transfer. Studies have shown that mercury does not easily wet type 316 SS below 275{deg}C. In the LME experiments, attempts were made to promote wetting of the steel by mercury either by adding gallium to the mercury or coating the specimen with a tin-silver solder that the mercury easily wets. The latter proved more reliable in establishing wetting, but there was no evidence of LME in any of the constant extension rate tensile tests either at 23 or 100 {deg}C. Inconel 718 also showed no change in room temperature properties when tested in mercwy or mercury-gallium. However, there was evidence that the fracture was less ductile. Preliminary evaluation of mass transfer of either type 304 SS, 316 SS, and Inconel 718 in mercury or mercury-gallium at 300-3500 C (maximum temperature) did not reveal significant effects. Two 5000 h thermal convection loop tests of type 316 SS are in progress, with specimens in both hot and cold test regions, at 300 and 240{deg}C, respectively.

DiStefano, J.R.; Manneschmidt, E.T.; Pawel, S.J.

1998-09-01

308

Modelling of an imaging beamline at the ISIS pulsed neutron source  

NASA Astrophysics Data System (ADS)

A combined neutron imaging and neutron diffraction facility, IMAT, is currently being built at the pulsed neutron spallation source ISIS in the U.K. A supermirror neutron guide is required to combine imaging and diffraction modes at the sample position in order to obtain suitable time of flight resolutions for energy selective imaging and diffraction experiments. IMAT will make use of a straight neutron guide and we consider here the optimization of the supermirror guide dimensions and characterisation of the resulting beam characteristics, including the homogeneity of the flux distribution in space and energy and the average and peak neutron fluxes. These investigations take into account some main design criteria: to maximise the neutron flux, to minimise geometrical artefacts in the open beam image at the sample position and to obtain a good energy resolution whilst retaining a large neutron bandwidth. All of these are desirable beam characteristics for the proposed imaging and diffraction analysis modes of IMAT.

Burca, G.; Kockelmann, W.; James, J. A.; Fitzpatrick, M. E.

2013-10-01

309

A neutron resonance capture analysis experimental station at the ISIS spallation source.  

PubMed

Neutron resonance capture analysis (NRCA) is a nuclear technique that is used to determine the elemental composition of materials and artifacts (e.g., bronze objects) of archaeological interest. NRCA experiments are mostly performed at the GELINA facility in Belgium, a pulsed neutron source operating with an electron linear accelerator. Very intense fluxes of epithermal neutrons are also provided by spallation neutron sources, such as the ISIS spallation neutron source in the United Kingdom. In the present study, the suitability of the Italian Neutron Experimental Station (INES) beam line for NRCA measurements is assessed using a compact (n, ?) resonance detector made of a Yttrium-Aluminum-Perovskite (YAP) scintillation crystal coupled with a silicon photomultiplier (SiPM) readout. The measurements provided a qualitative recognition of the composition of the standard sample, a lower limit for the sensitivity for NRCA for almost-in-traces elements, and an estimation of the relative isotopic concentration in the sample. PMID:20828445

Pietropaolo, Antonino; Gorini, Giuseppe; Festa, Giulia; Reali, Enzo; Grazzi, Francesco; Schooneveld, Erik M

2010-09-01

310

A kinematically beamed, low energy pulsed neutron source for active interrogation  

NASA Astrophysics Data System (ADS)

We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of special nuclear materials (SNM) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals: (1) energy discrimination allows us to measure the prompt fast fission neutrons produced while the interrogation beam is on; (2) neutrons with an energy of approximately 60-100 keV do not fission 238U and Thorium, but penetrate bulk material nearly as far as high energy neutrons do and (3) below about 100 keV neutrons lose their energy by kinematical collisions rather than via the nuclear (n, 2n) or (n, n') processes thus further simplifying the prompt neutron induced background. 60 keV neutrons create a low radiation dose and readily thermal capture in normal materials, thus providing a clean spectroscopic signature of the intervening materials. The kinematically beamed source also eliminates the need for heavy backward and sideway neutron shielding. We have designed and built a very compact pulsed neutron source, based on an RFQ proton accelerator and a lithium target. We are developing fast neutron detectors that are nearly insensitive to the ever-present thermal neutron and neutron capture induced gamma ray background. The detection of only a few high energy fission neutrons in time correlation with the linac pulse will be a clear indication of the presence of SNM.

Dietrich, Dan; Hagmann, Chris; Kerr, Phil; Nakae, Les; Rowland, Mark; Snyderman, Neal; Stoeffl, Wolfgang; Hamm, Robert

2005-12-01

311

Preliminary ANS (Advanced Neutron Source) reactor cold source gain factor calculations for liquid deuterium and liquid nitrogen-15  

Microsoft Academic Search

Individual energy group gain factors are computed for liquid nitrogen-15 and liquid deuterium cold source moderators using simple one-dimensional slab and spherical geometry calculational models. The energy spectrum of the neutron source is assumed to be that of a thermalized Maxwellian flux at 20\\/degree\\/C. The slab geometry calculations indicate that the optimum thickness for neutron transmission through a slab given

1988-01-01

312

Multiplicity correlation between neutrons and gamma-rays emitted from SNM and non-SNM sources  

NASA Astrophysics Data System (ADS)

The challenge in detection and identification of Special Nuclear Materials (SNM) is to discriminate between the time-correlated neutrons and gamma-rays emitted from SNM and those originating from non-correlated or differently-correlated environmental non-SNM sources. Time-correlated neutron and gamma-ray bursts can be generated by penetrating components of cosmic radiation. The characteristic features or attributes of correlated signatures can be revealed by analyzing the joint probability density functions (JPDFs) of various parameters of neutrons and gamma-rays. Monte Carlo simulations of SNM and cosmic-ray (non-SNM) sources of neutrons and gamma-rays are performed. For both SNM and non-SNM sources, energy-lifetime JPDF of neutrons, energy-lifetime JPDF of gamma-rays, and JPDFs of neutron-gamma-ray multiplicity are evaluated. Mean values, standard deviations, covariance and correlation are estimated. It is found that the number (multiplicity) of neutrons and gamma-rays emitted from an SNM source is moderately correlated (?0.48). The multiplicity of neutrons and gamma-rays generated by cosmic-ray showers at sea level is only weakly correlated (?-0.046). The exploitation of neutron-gamma-ray multiplicity correlation in detectors can provide a tool to discriminate non-SNM sources.

Miloshevsky, Gennady; Hassanein, Ahmed

2015-01-01

313

The Neutron Energy Spectrum Study from the Phase II Solid Methane Moderator at the LENS Neutron Source  

E-print Network

Neutron energy spectrum measurements from a solid methane moderator were performed at the Low Energy Neutron Source (LENS) at Indiana University Cyclotron Facility (IUCF) to verify our neutron scattering model of solid methane. The time-of-flight method was used to measure the energy spectrum of the moderator in the energy range of 0.1$meV\\sim$ 1$eV$. Neutrons were counted with a high efficiency $^{3}{He}$ detector. The solid methane moderator was operated in phase II temperature and the energy spectra were measured at the temperatures of 20K and 4K. We have also tested our newly-developed scattering kernels for phase II solid methane by calculating the neutron spectral intensity expected from the methane moderator at the LENS neutron source using MCNP (Monte Carlo N-particle Transport Code). Within the expected accuracy of our approximate approach, our model predicts both the neutron spectral intensity and the optimal thickness of the moderator at both temperatures. The predictions are compared to the measured energy spectra. The simulations agree with the measurement data at both temperatures.

Yunchang Shin; W. Mike Snow; Christopher M. Lavelle; David V. Baxter; Xin Tong; Haiyang Yan; Mark Leuschner

2007-11-19

314

Analysis of the propagation of neutrons and gamma-rays from the fast neutron source reactor YAYOI  

NASA Astrophysics Data System (ADS)

The skyshine effect is crucial for designing appropriate shielding. To investigate the skyshine effect, the propagation of neutrons was measured and analyzed at the fast neutron source reactor YAYOI. Pulse height spectra and dose distributions of neutron and secondary gamma-ray were measured outside YAYOI, and analyzed with MCNP-5 and JENDL-3.3. Comparison with the experimental results showed good agreement. Also, a semi-empirical formula was successfully derived to describe the dose distribution. The formulae can be used to predict the skyshine effect at YAYOI, and will be useful for estimating the skyshine effect and designing the shield structure for fusion facilities.

Yoshida, Shigeo; Murata, Isao; Nakagawa, Tsutomu; Saito, Isao

2011-10-01

315

Novel neutron sources at the Radiological Research Accelerator Facility  

NASA Astrophysics Data System (ADS)

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

Xu, Y.; Garty, G.; Marino, S. A.; Massey, T. N.; Randers-Pehrson, G.; Johnson, G. W.; Brenner, D. J.

2012-03-01

316

Novel neutron sources at the Radiological Research Accelerator Facility  

PubMed Central

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10–20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components. PMID:22545061

Xu, Yanping; Garty, Guy; Marino, Stephen A.; Massey, Thomas N.; Randers-Pehrson, Gerhard; Johnson, Gary W.; Brenner, David J.

2012-01-01

317

Novel neutron sources at the Radiological Research Accelerator Facility.  

PubMed

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons.We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target.A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the (7)Li(p,n)(7)Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components. PMID:22545061

Xu, Yanping; Garty, Guy; Marino, Stephen A; Massey, Thomas N; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

2012-03-16

318

Simulation of H- ion source extraction systems for the Spallation Neutron Source with Ion Beam Simulator.  

PubMed

A three-dimensional ion optical code IBSimu, which is being developed at the University of Jyva?skyla?, features positive and negative ion plasma extraction models and self-consistent space charge calculation. The code has been utilized for modeling the existing extraction system of the H(-) ion source of the Spallation Neutron Source. Simulation results are in good agreement with experimental data. A high-current extraction system with downstream electron dumping at intermediate energy has been designed. According to the simulations it provides lower emittance compared to the baseline system at H(-) currents exceeding 40 mA. A magnetic low energy beam transport section consisting of two solenoids has been designed to transport the beam from the alternative electrostatic extraction systems to the radio frequency quadrupole. PMID:22380214

Kalvas, T; Welton, R F; Tarvainen, O; Han, B X; Stockli, M P

2012-02-01

319

Three new nondestructive evaluation tools based on high flux neutron sources  

SciTech Connect

Nondestructive evaluation methods and systems based on specific attributes of neutron interactions with materials are being developed. The special attributes of neutrons are low attenuation in most engineering materials, strong interaction with low Z elements, and epithermal neutron absorption resonances. The three methods under development at ORNL include neutron based tomography and radiography; through thickness, nondestructive texture mapping; and internal, noninvasive temperature measurement. All three techniques require high flux sources such as the High Flux Isotope Reactor, a steady state source, or the Oak Ridge Electron Linear Accelerator, a pulsed neutron source. Neutrons are quite penetrating in most engineering materials and thus can be useful to detect internal flaws and features. Hydrogen atoms, such as in a hydrocarbon fuel, lubricant, or a metal hydride, are relatively opaque to neutron transmission and thus neutron based tomography/radiography is ideal to image their presence. Texture, the nonrandom orientation of crystalline grains within materials, can be mapped nondestructively using neutron diffraction methods. Epithermal neutron resonance absorption is being studied as a noncontacting temperature sensor. This paper highlights the underlying physics of the methods, progress in development, and the potential benefits for science and industry of the three facilities.

Hubbard, C.R.; Raine, D.; Peascoe, R.; Wright, M. [and others

1997-03-01

320

rf improvements for Spallation Neutron Source H{sup -} ion source  

SciTech Connect

The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering {approx}38 mA H{sup -} beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride (AlN) plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier.

Kang, Y. W.; Fuja, R.; Hardek, T.; Lee, S.-W.; McCarthy, M. P.; Piller, M. C.; Shin, K.; Stockli, M. P.; Welton, R. F. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Goulding, R. H. [Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2010-02-15

321

Microwave Ion Source and Beam Injection for an Accelerator-drivenNeutron Source  

SciTech Connect

An over-dense microwave driven ion source capable ofproducing deuterium (or hydrogen) beams at 100-200 mA/cm2 and with atomicfraction>90 percent was designed and tested with an electrostaticlow energy beam transport section (LEBT). This ion source wasincorporatedinto the design of an Accelerator Driven Neutron Source(ADNS). The other key components in the ADNS include a 6 MeV RFQaccelerator, a beam bending and scanning system, and a deuterium gastarget. In this design a 40 mA D+ beam is produced from a 6 mm diameteraperture using a 60 kV extraction voltage. The LEBT section consists of 5electrodes arranged to form 2 Einzel lenses that focus the beam into theRFQ entrance. To create the ECR condition, 2 induction coils are used tocreate ~; 875 Gauss on axis inside the source chamber. To prevent HVbreakdown in the LEBT a magnetic field clamp is necessary to minimize thefield in this region. Matching of the microwave power from the waveguideto the plasma is done by an autotuner. We observed significantimprovement of the beam quality after installing a boron nitride linerinside the ion source. The measured emittance data are compared withPBGUNS simulations.

Vainionpaa, J.H.; Gough, R.; Hoff, M.; Kwan, J.W.; Ludewigt,B.A.; Regis, M.J.; Wallig, J.G.; Wells, R.

2007-02-15

322

Control system for the Spallation Neutron Source H{sup -} source test facility Allison scanner  

SciTech Connect

Spallation Neutron Source is currently in progress of a multiyear plan to ramp ion beam power to the initial design power of 1.4 MW. Key to reaching this goal is understanding and improving the operation of the H{sup -} ion source. An Allison scanner was installed on the ion source in the test facility to support this improvement. This paper will discuss the hardware and the software control system of the installed Allison scanner. The hardware for the system consists of several parts. The heart of the system is the scanner head, complete with associated bias plates, slits, and signal detector. There are two analog controlled high voltage power supplies to bias the plates in the head, and a motor with associated controller to position the head in the beam. A multifunction data acquisition card reads the signals from the signal detector, as well as supplies the analog voltage control for the power supplies. To synchronize data acquisition with the source, the same timing signal that is used to trigger the source itself is used to trigger data acquisition. Finally, there is an industrial personal computer to control the rest of the hardware. Control software was developed using National Instruments LABVIEW, and consists of two parts: a data acquisition program to control the hardware and a stand alone application for offline user data analysis.

Long, C. D.; Stockli, M. P.; Gorlov, T. V.; Han, B.; Murray, S. N.; Pennisi, T. R. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)

2010-02-15

323

Advanced Neutron Source design: Burnout heat flux correlation development  

SciTech Connect

In the Advanced Neutron Source Reactor (ANSR) fuel element region, heat fluxes will be elevated. Early designs corresponded to average and estimated hot-spot fluxes of 11-12 and 21-22 MW/m/sup 2/, respectively. Design changes under consideration may lower these values to about 9 and 17 MW/m/sup 2/. In either event, the development of a satisfactory burnout heat flux correlation is an important element among the many thermal-hydraulic design issues, since the critical power ration will depend in part on its validity. Relatively little work in the area of subcooled-flow burnout has been published over the past 12 years. We have compared seven burnout correlations and modifications thereof with several sets of experimental data, of which the most relevant to the ANS core are presently those referenced. The best overall agreement between the correlations tested and these data is currently provided by a modification of Thorgerson's correlation. 7 refs., 1 tab.

Gambill, W.R.; Mochizuki, T.

1988-01-01

324

Fabrication development for the Advanced Neutron Source Reactor  

SciTech Connect

This report presents the fuel fabrication development for the Advanced Neutron Source (ANS) reactor. The fuel element is similar to that successfully fabricated and used in the High Flux Isotope Reactor (HFIR) for many years, but there are two significant differences that require some development. The fuel compound is U{sub 3}Si{sub 2} rather than U{sub 3}O{sub 8}, and the fuel is graded in the axial as well as the radial direction. Both of these changes can be accomplished with a straightforward extension of the HFIR technology. The ANS also requires some improvements in inspection technology and somewhat more stringent acceptance criteria. Early indications were that the fuel fabrication and inspection technology would produce a reactor core meeting the requirements of the ANS for the low volume fraction loadings needed for the highly enriched uranium design (up to 1.7 Mg U/m{sup 3}). Near the end of the development work, higher volume fractions were fabricated that would be required for a lower- enrichment uranium core. Again, results look encouraging for loadings up to {approx}3.5 Mg U/m{sup 3}; however, much less evaluation was done for the higher loadings.

Pace, B.W. [Babcock and Wilcox, Lynchburg, VA (United States); Copeland, G.L. [Oak Ridge National Lab., TN (United States)

1995-08-01

325

Fuel qualification plan for the Advanced Neutron Source Reactor  

SciTech Connect

This report describes the development and qualification plan for the fuel for the Advanced Neutron Source. The reference fuel is U{sub 3}Si{sub 2}, dispersed in aluminum and clad in 6061 aluminum. This report was prepared in May 1994, at which time the reference design was for a two-element core containing highly enriched uranium (93% {sup 235}U) . The reactor was in the process of being redesigned to accommodate lowered uranium enrichment and became a three-element core containing a higher volume fraction of uranium enriched to 50% {sup 235}U. Consequently, this report was not issued at that time and would have been revised to reflect the possibly different requirements of the lower-enrichment, higher-volume fraction fuel. Because the reactor is now being canceled, this unrevised report is being issued for archival purposes. The report describes the fabrication and inspection development plan, the irradiation tests and performance modeling to qualify performance, the transient testing that is part of the safety program, and the interactions and interfaces of the fuel development with other tasks.

Copeland, G.L.

1995-07-01

326

Assessment of the roles of the Advanced Neutron Source Operators  

SciTech Connect

The Advanced Neutron Source (ANS) is unique in the extent to which human factors engineering (HFE) principles are being applied at the conceptual design stage. initial HFE accomplishments include the development of an ANS HFE program plan, operating philosophy, and functional analysis. In FY 1994, HFE activities focused on the role of the ANS control room reactor operator (RO). An operator-centered control room model was used in conjunction with information gathered from existing ANS system design descriptions and other literature to define a list of RO responsibilities. From this list, a survey instrument was developed and administered to ANS design engineers, operations management personnel at Oak Ridge National Laboratory`s High Flux Isotope Reactor (HFIR), and HFIR ROs to detail the nature of the RO position. Initial results indicated that the RO will function as a high-level system supervisor with considerable monitoring, verification, and communication responsibilities. The relatively high level of control automation has resulted in a reshaping of the RO`s traditional safety and investment protection roles.

Hill, W.E.; Houser, M.M.; Knee, H.E.; Spelt, P.F.

1995-03-01

327

Mercury Cavitation Phenomenon in Pulsed Spallation Neutron Sources  

SciTech Connect

Innovative researches will be performed at Materials and Life Science Experimental Facility in J-PARC, in which a mercury target system will be installed as MW-class pulse spallation neutron sources. Proton beams will be injected into mercury target to induce the spallation reaction. At the moment the intense proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by micro-jets and/or shock waves which are caused by cavitation bubble collapse impose pitting damage on the vessel wall. The pitting damage which degrades the structural integrity of target vessels is a crucial issue for high power mercury targets. Micro-gas-bubbles injection into mercury may be useful to mitigate the pressure wave and the pitting damage. The visualization of cavitation-bubble and gas-bubble collapse behaviors was carried out by using a high-speed video camera. The differences between them are recognized.

Futakawa, Masatoshi; Naoe, Takashi [Japan Atomic Energy Agency Tokai-mura, Naka-gun, Ibaraki-ken, 319-1195 (Japan); Kawai, Masayoshi [KEK Tsukuba-shi, Ibaraki-ken, 305-0801 (Japan)

2008-06-24

328

H{sup -} radio frequency source development at the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of {approx}75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to {approx}100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

Welton, R. F.; Gawne, K. R.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Roseberry, R. T.; Santana, M.; Stockli, M. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States); Dudnikov, V. G. [Muons, Inc., 552 N. Batavia Avenue, Batavia, Illinois 60510 (United States); Turvey, M. W. [Villanova University, 800E. Lancaster Ave, Villanova, Pennsylvania 19085 (United States)

2012-02-15

329

Shielding design studies for a neutron irradiator system based on a 252Cf source.  

PubMed

This study aims to investigate a shielding design against neutrons and gamma rays from a source of 252Cf, using Monte Carlo simulation. The shielding materials studied were borated polyethylene, borated-lead polyethylene and stainless steel. The Monte Carlo code MCNP4B was used to design shielding for 252Cf based neutron irradiator systems. By normalising the dose equivalent rate values presented to the neutron production rate of the source, the resulting calculations are independent of the intensity of the actual 252Cf source. The results show that the total dose equivalent rates were reduced significantly by the shielding system optimisation. PMID:11707031

da Silva, A X; Crispim, V R

2001-01-01

330

OPTIONS FOR A STEADY-STATE COMPACT FUSION NEUTRON SOURCE M.P. Gryaznevich1  

E-print Network

, is the fusion ­ fission hybrid reactor. By using the excess neutrons from the fusion reaction to cause a highOPTIONS FOR A STEADY-STATE COMPACT FUSION NEUTRON SOURCE M.P. Gryaznevich1 , A. Sykes1 , D Kingham1@tokamaksolutions.co.uk The new approach in advancing the use of fusion, "Fusion for Neutrons" (F4N), is proposed. The application

331

The neutron detection efficiency of NE213 detectors measured by means of a 252Cf source  

Microsoft Academic Search

The neutron detection efficiency of a NE213 scintillator was determined by comparing the measured neutron time-of-flight spectrum of a 252Cf source with its reference neutron energy distribution. Below En = 8 MeV an accuracy of better than 3% could be achieved. The measured efficiency agreed reasonably well in shape with a Monte Carlo simulation in the entire energy range 0.8

J. Cub; E. Finckh; K. Gebhardt; K. Geissdörfer; R. Lin; J. Strate; H. Klein

1989-01-01

332

Initial in-reactor performance of the Cornell cold neutron source  

Microsoft Academic Search

The Cornell Cold Neutron Beam Facility consists of two major subsystems, a cold neutron source (CNS) and a 13-m-long curved neutron guide. This paper describes the initial in-reactor performance tests of the CNS. The results agree closely with predictions from out-of-reactor tests and meet the design criteria for safety and simplicity of operation. This phase of the project has therefore

S. A. Spern; D. D. Clark; A. G. Atwood

1996-01-01

333

Characterization of pulsed (plasma focus) neutron source with image plate and application to neutron radiography  

SciTech Connect

Plasma focus device of Mather type developed in house has been used first time for neutron radiography of different objects. The device gives (1.2{+-}0.3) Multiplication-Sign 10{sup 9} neutrons per pulse produced by D-D fusion reaction with a pulse width of 50{+-}5 ns. The method involves exposing sample to be radiographed to thermalized D-D neutrons and recording the image on Fuji-film BAS-ND image plates. The thermal neutron component of the moderated beam was estimated using two image plates: a conventional IP for X-rays and gamma rays, and an IP doped with Gd for detecting neutrons.

Andola, Sanjay; Niranjan, Ram; Rout, R. K.; Kaushik, T. C.; Gupta, S. C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Shaikh, A. M. [Raja Ramanna Fellow, Solid State Physics Division (India)

2013-02-05

334

Tagging fast neutrons from an 241Am/9Be source  

E-print Network

We report on an investigation of the fast-neutron spectrum emitted by 241Am/9Be. Well-understood shielding, coincidence, and time-of-flight measurement techniques are employed to produce a continuous, polychromatic, energy-tagged neutron beam.

J. Scherzinger; J. R. M. Annand; G. Davatz; K. G. Fissum; U. Gendotti; R. Hall-Wilton; A. Rosborg; E. Håkansson; R. Jebali; K. Kanaki; M. Lundin; B. Nilsson; H. Svensson

2015-01-03

335

INNOVATIVE ACCELERATOR BASED NEUTRON SOURCE B. F. Bayanov1  

E-print Network

to 10 mA. Epithermal neutrons for boron neutron capture therapy are proposed to be generated by protons by 1.75 MeV protons bombarding a arbon-13 target. The 2 mA 2 MeV proton beam had just been obtained. In the report, the pilot facility design is given, results of first experiments on proton beam transport

Taskaev, Sergey Yur'evich

336

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

PubMed

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 × 10(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(4) nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T(3). PMID:23277984

Lee, Sungman; Park, Sangsoon; Lee, Kitae; Cha, Hyungki

2012-12-01

337

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)

2012-12-15

338

Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings.  

PubMed

The fabrication of gratings including metal deposition processes for highly neutron absorbing lines is a critical issue to achieve a good visibility of the grating-based phase imaging system. The source grating for a neutron Talbot-Lau interferometer is an array of Gadolinium (Gd) structures that are generally made by sputtering, photo-lithography, and chemical wet etching. However, it is very challenging to fabricate a Gd structure with sufficient neutron attenuation of approximately more than 20 ?m using a conventional metal deposition method because of the slow Gd deposition rate, film stress, high material cost, and so on. In this article, we fabricated the source gratings for neutron Talbot-Lau interferometers by filling the silicon structure with Gadox particles. The new fabrication method allowed us a very stable and efficient way to achieve a much higher Gadox filled structure than a Gd film structure, and is even more suitable for thermal polychromatic neutrons, which are more difficult to stop than cold neutrons. The newly fabricated source gratings were tested at the polychromatic thermal neutron grating interferometer system of HANARO at the Korea Atomic Energy Research Institute, and the visibilities and images from the neutron phase imaging system with the new source gratings were compared with those fabricated by a Gd deposition method. PMID:23822350

Kim, Jongyul; Lee, Kye Hong; Lim, Chang Hwy; Kim, Taejoo; Ahn, Chi Won; Cho, Gyuseong; Lee, Seung Wook

2013-06-01

339

Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings  

NASA Astrophysics Data System (ADS)

The fabrication of gratings including metal deposition processes for highly neutron absorbing lines is a critical issue to achieve a good visibility of the grating-based phase imaging system. The source grating for a neutron Talbot-Lau interferometer is an array of Gadolinium (Gd) structures that are generally made by sputtering, photo-lithography, and chemical wet etching. However, it is very challenging to fabricate a Gd structure with sufficient neutron attenuation of approximately more than 20 ?m using a conventional metal deposition method because of the slow Gd deposition rate, film stress, high material cost, and so on. In this article, we fabricated the source gratings for neutron Talbot-Lau interferometers by filling the silicon structure with Gadox particles. The new fabrication method allowed us a very stable and efficient way to achieve a much higher Gadox filled structure than a Gd film structure, and is even more suitable for thermal polychromatic neutrons, which are more difficult to stop than cold neutrons. The newly fabricated source gratings were tested at the polychromatic thermal neutron grating interferometer system of HANARO at the Korea Atomic Energy Research Institute, and the visibilities and images from the neutron phase imaging system with the new source gratings were compared with those fabricated by a Gd deposition method.

Kim, Jongyul; Lee, Kye Hong; Lim, Chang Hwy; Kim, Taejoo; Ahn, Chi Won; Cho, Gyuseong; Lee, Seung Wook

2013-06-01

340

An accelerator-based epithermal photoneutron source for boron neutron capture therapy  

SciTech Connect

Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10{sup 7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF{sub 3} composite and a stacked Al/Teflon design) at various incident electron energies.

Mitchell, H.E.

1996-04-01

341

ALARA Review of the Spallation Neutron Source Accumulator Ring and Transfer Lines  

Microsoft Academic Search

The Spallation Neutron Source (SNS) is designed to meet the growing need for new tools that will deepen our understanding in materials science, life science, chemistry, fundamental and nuclear physics, earth and environmental sciences, and engineering sciences. The SNS is an accelerator-based neutron-scattering facility that when operational will produce an average beam power of 2 MW at a repetition rate

Haire

2003-01-01

342

Application of spallation neutron sources in support of radiation hardness studies  

Microsoft Academic Search

High-power spallation neutron sources offer a unique opportunity to gather critical measurements on the very early transient displacement damage in semiconductors. This paper discusses the important attributes of spallation neutron facilities used for investigating the transient radiation hardness of semiconductors. By comparing the attributes of some different types of radiation facilities currently used for semiconductor damage characterization, a new and

Patrick Griffin; Donald King; Norm Kolb

2006-01-01

343

Energyangle correlation of neutrons and gamma-rays emitted from an HEU source  

E-print Network

Energy­angle correlation of neutrons and gamma-rays emitted from an HEU source G. Miloshevsky n , A and gamma-rays Joint and marginal probability density functions Covariance and correlation a b s t r a c t Special Nuclear Materials (SNM) yield very unique fission signatures, namely correlated neutrons and gamma-rays

Harilal, S. S.

344

A source-based fast-neutron facility for precision irradiations  

E-print Network

We report on a source-based fast-neutron facility that has been developed for precision irradiations. Well-understood shielding, coincidence, and time-of-flight measurement techniques are employed to produce a polychromatic energy-tagged neutron beam.

Scherzinger, J; Davatz, G; Fissum, K G; Gendotti, U; Hall-Wilton, R; Hansson, A; Håkansson, E; Jebali, R; Kanaki, K; Lundin, M; Nilsson, B; Svensson, H

2014-01-01

345

Plasma focus based repetitive source of fusion neutrons and hard x-rays  

Microsoft Academic Search

A plasma focus device capable of operating at 0.2 pulses per second during several minutes is used as a source of hard x-rays and fast neutrons. An experimental demonstration of the use of the neutrons emissions for radiation probing of hydrogenated substances is presented, showing a particular application in detecting water concentrations differences in the proximity of the device by

V. Raspa; F Di Lorenzo; P. Knoblauch; A. Lazarte; A. Tartaglione; A. Clausse; C. Moreno

2008-01-01

346

Thermal-hydraulic analysis of the Advanced Neutron Source reactor refueling process  

Microsoft Academic Search

The Advanced Neutron Source Reactor (ANSR) is being designed to become the world's most advanced reactor for neutron scattering research. It is both moderated and cooled by heavy water (D[sub 2]O) and uses a core of highly enriched uranium silicide fuel in a plate geometry. During the refueling process of the ANSR, the spent fuel must be moved from within

Y. Elkassabgi; G. L. Yoder; W. R. Gambill

1994-01-01

347

Materials research and development for the spallation neutron source mercury target  

Microsoft Academic Search

In the Spallation Neutron Source target, the structural material will be exposed to intense pulsed fluxes of high-energy protons and neutrons, which produce radiation damage. These pulsed fluxes also lead to pressure pulses created by beam heating. In turn, the pressure pulses give rise to fluctuating stresses in the 316 LN austenitic stainless steel target vessel, and to cavitation in

L. K. Mansur

2003-01-01

348

Thermal design study of a liquid hydrogen-cooled cold-neutron source  

Microsoft Academic Search

The use of both liquid hydrogen as a moderator and polycrystalline beryllium as a filter to enhance cold neutron flux at the UC Davis McClellan Nuclear Radiation Center has been studied. Although, more work is needed before an actual cold neutron source can be designed and built, the purpose of this preliminary study is to investigate the effects of liquid

D. Quach; R. C. Aldredge; H. B. Liu; W. J. Richards

2007-01-01

349

Intense Pulsed Neutron Source progress report for 1991  

SciTech Connect

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

1991-01-01

350

Production of Fast Neutron With Plasma Focus Device  

Microsoft Academic Search

Before its demise DIANA Hi-TECH, LLC, demonstrated the use of two 50 kJoule Plasma Focus devices for the copius production of fast neutrons, x-rays and radio-isotopes. Such a device is suitable for fast neutron non invasive interogation of contra-band materials including hidden nuclear materials. It could be particularly useful for a fast and fail safe interogation of large cargo containers,

Moshe Gai

2006-01-01

351

A comparative neutronic feasibility study for a hydrogen, deuterium and helium cold neutron sources situated in the center of a nuclear reactor core  

Microsoft Academic Search

A tool was developed to calculate the average cold neutron flux that could be generated for a spherically shaped cold neutron source situated in the center of a nuclear reactor core. The tool also estimates the subsequent nuclear heating of the cold source. The results were compared for three different cold source mediums; hydrogen, deuterium and helium. The tool utilizes

Malek Chatila

2003-01-01

352

Design of a compact high-power neutron source—The EURISOL converter target  

NASA Astrophysics Data System (ADS)

The EURISOL project, a multi-lateral initiative supported by the EU, aims to develop a facility to achieve high yields of isotopes in radioactive beams and extend the variety of these isotopes towards more exotic types. The neutron source at the heart of the projected facility is designed to generate isotopes by fissioning uranium carbide (UC) targets arranged around a 4 MW neutron source. For reasons of efficiency, it is essential that the neutron source be as compact as possible, to avoid losing neutrons by absorption whilst maximising the escaping neutron flux, thus increasing the number of fissions in the UC targets. The resulting configuration presents a challenge in terms of absorbing heat deposition rates of up to 8 kW/cm3 in the neutron source; it has led to the selection of liquid metal for the target material. The current paper presents the design of a compact high-power liquid-metal neutron source comprising a specially optimised beam window concept. The design is based on two-dimensional (2D) and three-dimensional (3D) computational fluid dynamics (CFD) numerical simulations for thermal hydraulics and hydraulic aspects, as well as finite-element method (FEM) for assessing thermo-mechanical stability. The resulting optimised design was validated by a dedicated hydraulic test under realistic flow conditions. A full-scale mock-up was built at the Paul Scherrer Institute (PSI) and was tested at the Institute of Physics of the University of Latvia (IPUL).

Samec, K.; Milenkovi?, R. Ž.; Dementjevs, S.; Ashrafi-Nik, M.; Kalt, A.

2009-07-01

353

Separation of beam and electrons in the spallation neutron source H{sup -} ion source  

SciTech Connect

The Spallation Neutron Source (SNS) requires an ion source producing an H{sup {minus}} beam with a peak current of 35mA at a 6.2 percent duty factor. For the design of this ion source, extracted electrons must be transported and dumped without adversely affecting the H{sup {minus}} beam optics. Two issues are considered: (1) electron containment transport and controlled removal; and (2) first-order H{sup {minus}} beam steering. For electron containment, various magnetic, geometric and electrode biasing configurations are analyzed. A kinetic description for the negative ions and electrons is employed with self-consistent fields obtained from a steady-state solution to Poisson`s equation. Guiding center electron trajectories are used when the gyroradius is sufficiently small. The magnetic fields used to control the transport of the electrons and the asymmetric sheath produced by the gyrating electrons steer the ion beam. Scenarios for correcting this steering by split acceleration and focusing electrodes will be considered in some detail.

Whealton, J.H.; Raridon, R.J. [Oak Ridge National Lab., TN (United States); Leung, K.N. [Lawrence Berkeley National Lab., CA (United States)

1997-12-01

354

Monte Carlo calculation of skyshine'' neutron dose from ALS (Advanced Light Source)  

SciTech Connect

This report discusses the following topics on skyshine'' neutron dose from ALS: Sources of radiation; ALS modeling for skyshine calculations; MORSE Monte-Carlo; Implementation of MORSE; Results of skyshine calculations from storage ring; and Comparison of MORSE shielding calculations.

Moin-Vasiri, M.

1990-06-01

355

ELECTRON CLOUD AT COLLIMATOR AND INJECTION REGION OF THE SPALLATION NEUTRON SOURCE ACCUMULATOR RING.  

SciTech Connect

The beam loss along the Spallation Neutron Source's accumulator ring is mainly located at the collimator region and injection region. This paper studied the electron cloud build-up at these two regions with the three-dimension program CLOUDLAND.

WANG, L.; HSEUH, H.-C.; LEE, Y.Y.; RAPARIA, D.; WEI, J.; COUSINEAU, S.

2005-05-16

356

Proceedings of the 10th meeting of the international collaboration on advanced neutron sources  

SciTech Connect

This report contains papers from the 10th meeting of the International Collaboration on Advanced Neutron Sources. Two general types of workshops are discussed, instrument and target-station. Individual papers are indexed separately elsewhere. (LSP)

Hyer, D.K. (comp. and ed.)

1989-03-01

357

Borated Polymer Composite for Fast Neutron Shielding (Americium-Beryllium Source)  

Microsoft Academic Search

Neutrons from a americium-beryllium source with a source strength of 5 Ci have been examined for shielding using a borated polymer composite formulated of baryte and quartz as strengtheners. It is observed that there is a considerable dose reduction and spectral hardening leading to energy degradations. Various sources of americium have been tried with a target nucleus of beryllium in

K. L. Sundar; G. Radhakrishnan; B. R. Reddi

1996-01-01

358

Neutron kinetics in subcritical cores with application to the source modulation method  

E-print Network

Neutron kinetics in subcritical cores with application to the source modulation method J. Wright The subject of this paper is an investigation of the performance of the so-called source modulation technique detector, including the source modulation method, are based on the assumption of point kinetic behaviour

Pázsit, Imre

359

Initial Testing of an Ultra-Cold Neutron Source at Los Alamos  

Microsoft Academic Search

The production of ultra cold neutrons (UCN) at a spallation source is quite different than at a reactor. One can take advantage of the short pulse width of the source to produce and store UCN at the peak intensities available, which are comparable to or can exceed those at a reactor. We have built a source (UCN homepage ) at

T. J. Bowles; T. O. Brun; R. E. Hill; C. L. Morris; S. J. Seestrom; M. L. Crow

1997-01-01

360

A fast-neutron activation detector for 14MeV pulsed neutron sources  

Microsoft Academic Search

A fast-neutron activation detector is described in which the gamma rays ; resulting from the decay of Pb\\/sup 207m\\/- are observed in a plastic scintillator. ; The Pb\\/sup 207m\\/ is produced by fast-neutron activation of a lead shield ; which surrounds the scintillator and photomultiplier. Following a 20-msec delay ; from the neutron pulse, the Pb\\/sup 207m\\/ activity is observed

Lawrence Ruby; J. B. Rechen

1962-01-01

361

A FAST-NEUTRON ACTIVATION DETECTOR FOR 14Mev PULSED NEUTRON SOURCES  

Microsoft Academic Search

A fast-neutron activation detector is described in which the gamma rays ; resulting from the decay of Pb\\/sup 207m\\/ are observed in a plastic scintillator. ; The Pb\\/sup 207m\\/ produced by fast-neutron activation of a lead shield which ; surrounds the scintillator and photomultiplier. Following a 20-msec delay from ; the neutron pulse, the Pb\\/sup 207m\\/ activity is observed for

L. Ruby; J. B. Rechen

1961-01-01

362

Geometrical effects on thermal neutron reflection of hydrogenous moderators using 241Am-Be source  

Microsoft Academic Search

The variation of thermal reflection parameter with thicknesses of water and paraffin moderators was measured using an instrument consisting of 1 Ci 241Am–Be isotopic neutron source and 3He neutron detector. Based on experimental data obtained from two different source–detector–sample geometries, analytical expressions were derived for calculation of reflection parameters for various moderator thicknesses. The measured data for the two geometries

E. H. K. Akaho; S. A. Jonah; C. P. K Dagadu; B. T. Maakuu; P. S. Adu; S. Anim-Sampong; A. W. K. Kyere

2001-01-01

363

Materials irradiation subpanel report to BESAC neutron sources and research panel  

Microsoft Academic Search

The future success of the nuclear power option in the US (fission and fusion) depends critically on the continued existence of a healthy national materials-irradiation program. Consideration of the requirements for acceptable materials-irradiation systems in a new neutron source has led the subcommittee to identify an advanced steady-state reactor (ANS) as a better choice than a spallation neutron source. However,

R. C. Birtcher; A. N. Goland; R. Lott; G. R. Odette

1992-01-01

364

Nanoparticles as a possible moderator for an ultracold neutron source  

E-print Network

Ultracold and very cold neutrons (UCN and VCN) interact strongly with nanoparticles due to the similarity of their wavelengths and nanoparticles sizes. We analyze the hypothesis that this interaction can provide efficient cooling of neutrons by ultracold nanoparticles at certain experimental conditions, thus increasing the density of UCN by many orders of magnitude. The present analytical and numerical description of the problem is limited to the model of independent nanoparticles at zero temperature. Constraints of application of this model are discussed.

V. V. Nesvizhevsky; G. Pignol; K. V. Protasov

2005-10-06

365

New source for ultracold neutrons at the Institut Laue-Langevin  

NASA Astrophysics Data System (ADS)

A new intense superthermal source for ultracold neutrons (UCN) was installed at a dedicated beam line at the Institut Laue-Langevin. Incident neutrons with a wavelength of 0.89 nm are converted to UCN in a 5-liter volume filled with superfluid He4 at a temperature of about 0.7 K. The UCN can be extracted to room temperature experiments. We present the cryogenic setup of the source, a characterization of the cold neutron beam, and UCN production measurements, where a UCN density in the production volume of at least 55 per cm3 was determined.

Piegsa, F. M.; Fertl, M.; Ivanov, S. N.; Kreuz, M.; Leung, K. K. H.; Schmidt-Wellenburg, P.; Soldner, T.; Zimmer, O.

2014-07-01

366

Prompt-gamma neutron activation analysis system design: effects of D-T versus D-D neutron generator source selection  

Technology Transfer Automated Retrieval System (TEKTRAN)

Prompt-gamma neutron activation analysis (PGNAA) is used for the non-invasive measurement of human body composition. Advancements in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators are available: D-D with 2.5 MeV, and D-T wi...

367

THERMAL AND HYDRAULIC ANALYSIS OF THE CORNELL COLD NEUTRON BEAM FACILITY COOLING SYSTEM AND CONTINUATION OF DEVELOPMENT OF A NEW COOLING SYSTEM FOR PSU COLD NEUTRON SOURCE  

Microsoft Academic Search

The objectives of this research project is to investigate thermal and thermal-hydraulic characteristics of the cooling system of Cornell University, The Cold Neutron Beam Facility (CNBF) which includes a moderator, a cryo-refrigerator, copper cold fingers, a neutron guide system, vacuum jackets, shielding, and various connecting and control lines. In order to design a third generation mesitlylene based cold neutron source

Savas Yavuzkurt

368

Accelerator based neutron source for neutron capture therapy B. Bayanov, Yu. Belchenko, V. Belov, V. Davydenko, A. Donin, A. Dranichnikov, A. Ivanov,  

E-print Network

in the center of high-voltage electrode, the proton beam is formed at the outlet of the tandemAccelerator based neutron source for neutron capture therapy B. Bayanov, Yu. Belchenko, V. Belov, V capture and fast neutron therapy for hospital. Innovative approach is based upon vacuum insulation tandem

Taskaev, Sergey Yur'evich

369

FAST NEUTRON SOURCE DETECTION AT LONG DISTANCES USING DOUBLE SCATTER SPECTROMETRY.  

SciTech Connect

Fast neutrons can be detected with relatively high efficiency, >15%, using two planes of hydrogenous scintillator detectors where a scatter in the first plane creates a start pulse and scatter in the second plane is separated by time-of-flight. Indeed, the neutron spectrum of the source can be determined as the sum of energy deposited by pulse height in the first added to the energy of the second found by time-of-flight to the second detector. Gamma rays can also create a double scatter by Compton interaction in the first with detection in the second, but these events occur in a single time window because the scattered photons all travel at the speed of light. Thus, gamma ray events can be separated from neutrons by the time-of-flight differences. We have studied this detection system with a Cf-252 source using Bicron 501A organic scintillators and report on the ability to efficiently detect fast neutrons with high neutron/gamma detection ratios. We have further studied cosmic-ray neutron background detection response that is the dominant background in long range detection. We have found that most of the neutrons are excluded from the time-of-flight window because they are either too high in energy, >10 keV, or too low, < 10 keV. Moreover, if the detection planes are position-sensitive, the angular direction of the source can be determined by the ratio of the energy of scattered protons in the first detector relative to the position and energy of the scattered neutron detected in the second. This ability to locate the source in theta is useful, but more importantly increases the signal to noise relative to cosmic-ray produced neutrons that are relatively isotropic. This technique may be used in large arrays to detect neutrons at ranges up to 0.5 kilometer.

FORMAN,L.VANIER,P.WELSH,K.

2003-08-03

370

Materials irradiation subpanel report to BESAC neutron sources and research panel  

SciTech Connect

The future success of the nuclear power option in the US (fission and fusion) depends critically on the continued existence of a healthy national materials-irradiation program. Consideration of the requirements for acceptable materials-irradiation systems in a new neutron source has led the subcommittee to identify an advanced steady-state reactor (ANS) as a better choice than a spallation neutron source. However, the subcommittee also hastens to point out that the ANS cannot stand alone as the nation`s sole high-flux mixed-spectrum neutron irradiation source in the next century. It must be incorporated in a broader program that includes other currently existing neutron irradiation facilities. Upgrading and continuing support for these facilities must be planned. In particular, serious consideration should be given to converting the HFIR into a dedicated materials test reactor, and long-term support for several university reactors should be established.

Birtcher, R.C. [Argonne National Lab., IL (United States); Goland, A.N. [Brookhaven National Lab., Upton, NY (United States); Lott, R. [Westinghouse Electric Corp., Pittsburgh, PA (United States). Science and Technology Center; Odette, G.R. [California Univ., Santa Barbara, CA (United States)

1992-09-10

371

Comparison of LaBr 3:Ce and NAI(Tl) scintillators for radio-isotope identification devices  

NASA Astrophysics Data System (ADS)

Lanthanum bromide (LaBr 3:Ce) scintillators offer significantly better resolution (<3 percent at 662 keV) relative to sodium iodide (NaI(Tl)) but contain internal radioactivity that contributes to spectral counts. LaBr 3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5×1.5-in. LaBr 3:Ce detector with an Exploranium GR-135 RIID, which contains a 1.5×2.2-in. NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision™). In general, the LaBr 3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr 3:Ce detector was usually two to three times faster. The notable exception was for 40K-containing NORM where interfering internal activity due to 138La in the LaBr 3:Ce detector exists and NaI(Tl) consistently outperformed LaBr 3:Ce.

Milbrath, B. D.; Choate, B. J.; Fast, J. E.; Hensley, W. K.; Kouzes, R. T.; Schweppe, J. E.

2007-03-01

372

A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives  

NASA Astrophysics Data System (ADS)

AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at ˜10-50 Hz and emits ˜106n/pulse at a peak current of 100 kA. Both sources emit 2.45±0.1 MeV (DD) neutron pulses of ˜25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm3 in volume.

Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert; Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin; Lane, Stephen

2011-12-01

373

A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives  

SciTech Connect

AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at {approx}10-50 Hz and emits {approx}10{sup 6}n/pulse at a peak current of 100 kA. Both sources emit 2.45{+-}0.1 MeV(DD) neutron pulses of {approx}25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm{sup 3} in volume.

Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert [Alameda Applied Sciences Corporation, 3077 Teagarden Street, San Leandro, CA 94577 (United States); Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin [XIA LLC, 31057 Genstar Road, Hayward, CA 94544 (United States); Lane, Stephen [NSF Center for Biophotonics and School of Medicine, University of California Davis, Sacramento CA, 95817 (United States)

2011-12-13

374

Design of an accelerator-based neutron source for neutron capture therapy.  

PubMed

The boron neutron capture therapy is mainly suited in the treatment of some tumor kinds which revealed ineffective to the traditional radiotherapy. In order to take advantage of such a therapeutic modality in hospital environments, neutron beams of suitable energy and flux levels provided by compact size facilities are needed. The advantages and drawbacks of several neutron beams are here analysed in terms of therapeutic gains. In detail the GEANT-3/MICAP simulations show that high tumor control probability, with sub-lethal dose at healthy tissues, can be achieved by using neutron beams of few keV energy having a flux of about 10(9) neutrons/(cm(2)s). To produce such a neutron beam, the feasibility of a proton accelerator is investigated. In particular an appropriate choice of the radiofrequency parameters (modulation, efficiency of acceleration, phase shift, etc.) allows the development of relatively compact accelerators, having a proton beam current of 30 mA and an energy of 2 MeV, which could eventually lead to setting up of hospital-based neutron facilities. PMID:19406649

Terlizzi, R; Colonna, N; Colangelo, P; Maiorana, A; Marrone, S; Rainò, A; Tagliente, G; Variale, V

2009-07-01

375

Thermal hydraulic analysis of two-phase closed thermosyphon cooling system for new cold neutron source moderator of Breazeale research reactor at Penn State  

Microsoft Academic Search

A cold neutron source cooling system is required for the Penn State's next generation cold neutron source facility that can accommodate a variable heat load up to about ˜10W with operating temperature of about 28K. An existing cold neutron source cooling system operating at the University of Texas Cold Neutron Source (TCNS) facility failed to accommodate heat loads upwards of

Melaku Habte

2008-01-01

376

Design of a laboratory for experiments with a pulsed neutron source.  

PubMed

We present the results of a neutron shielding design and optimisation study performed to reduce the exposure to radiological doses arising from a 14 MeV pulsed neutron generator (PNG) having a maximum emission strength of 2.0 x 10(8) neutrons s(-1). The source was intended to be used in a new irradiation facility for the realisation of an experiment on acoustical cavitation in liquids. This paper describes in detail how the facility was designed to reduce both neutron and gamma-ray dose rates to acceptable levels, taking into account the ALARP principle in following the steps of optimisation. In particular, this work compares two different methods of optimisation to assess neutron dose rates: the use of analytical methods and the use of Monte Carlo simulations (MCNPX 2.4). The activation of the surrounding materials during operation was estimated using the neutron spectra as input to the FISPACT 3.0 code. The limitations of a first-order analytical model to determine the neutron activation levels are highlighted. The impact that activation has on the choice of the materials to be used inside the laboratory and on the waiting time before anyone can safely enter the room after the neutron source is switched off is also discussed. PMID:19454793

Memoli, G; Trusler, J P M; Ziver, A K

2009-06-01

377

Monte Carlo-based method to determine the strength of a neutron source  

NASA Astrophysics Data System (ADS)

The utilization of a gamma-ray spectrometer with a 7.62 ×7.62 cm NaI(Tl) detector, with a spherical moderator, has been studied with the aim to measure the neutron fluence rate and to determine the neutron source strength. Moderators with a large amount of hydrogen are able to slowdown and thermalize neutrons; once thermalized, there is a probability for thermal neutrons to be captured by hydrogen, producing 2.22 MeV gamma rays. The pulse-height spectrum collected in a multichannel analyzer shows a photopeak around 2.22 MeV whose net area is proportional to total neutron fluence rate and to the neutron source strength. The characteristics of this system were determined by a Monte Carlo study using the MCNP 4C code, where a detailed model of the NaI(Tl) was utilized. Spheres of diameters 3, 5, and 10 inch were used as moderators, and the response was calculated for monoenergetic and isotopic neutrons sources.

Vega-Carrillo, H. R.; Manzanares-Acu?a, E.; Hern&Ández-D&Ávila, V. M.; Chacón-Ruíz, A.; Mercado, G. A.; Gallego, E.; Lorente, A.

378

Production and characterization of a custom-made 228Th source with reduced neutron source strength for the Borexino experiment  

NASA Astrophysics Data System (ADS)

A custom-made 228Th source of several MBq activities was produced for the Borexino experiment to study the external background of the detector. The aim was to reduce the unwanted neutron emission produced via (?,n) reactions in ceramics typically used for commercial 228Th sources. For this purpose a ThCl4 solution was chemically converted into ThO2 and embedded in a gold foil. The paper describes the production of the custom-made source and its characterization by means of ?-activity, dose rate and neutron source strength measurements. From ?-spectroscopic measurements it was deduced that activity transfer from the initial solution to the final source was >91% (at 68% C.L.) and the final activity was (5.41±0.30) MBq. The dose rate was measured with two dosimeters yielding 12.1 mSv/h and 14.3 mSv/h in 1 cm distance. The neutron source strength of the 5.41 MBq 228Th source was determined to be (6.59±0.85) s-1.

Maneschg, W.; Baudis, L.; Dressler, R.; Eberhardt, K.; Eichler, R.; Keller, H.; Lackner, R.; Praast, B.; Santorelli, R.; Schreiner, J.; Tarka, M.; Wiegel, B.; Zimbal, A.

2012-07-01

379

Modified big bang nucleosynthesis with nonstandard neutron sources  

NASA Astrophysics Data System (ADS)

During big bang nucleosynthesis, any injection of extra neutrons around the time of the Be7 formation, i.e. at a temperature of order T ?50 keV, can reduce the predicted freeze-out amount of Be7+Li7 that otherwise remains in sharp contradiction with the Spite plateau value inferred from the observations of Pop II stars. However, the growing confidence in the primordial D /H determinations puts a strong constraint on any such scenario. We address this issue in detail, analyzing different temporal patterns of neutron injection, such as decay, annihilation, resonant annihilation, and oscillation between mirror and standard model world neutrons. For this latter case, we derive the realistic injection pattern taking into account thermal effects (damping and refraction) in the primordial plasma. If the extra-neutron supply is the sole nonstandard mechanism operating during the big bang nucleosynthesis, the suppression of lithium abundance below Li /H?1.9×10-10 always leads to the overproduction of deuterium, D /H?3.6×10-5, well outside the error bars suggested by recent observations.

Coc, Alain; Pospelov, Maxim; Uzan, Jean-Philippe; Vangioni, Elisabeth

2014-10-01

380

The investigation of high intensity laser driven micro neutron sources  

E-print Network

. These potentially offer sufficient energy density for efficient neutron production in DT targets with dimensions/pulse at 100 Hz (i.e. 10 kW average power) and laser irradiances in the range I2 1017 -1019 W µm2 /cm2 could relevant materials (e.g., ferritic steel, vana- dium alloy, carbon, silicon carbide) and the potential

Ghoniem, Nasr M.

381

A Targeted Search for Point Sources of EeV Neutrons  

NASA Astrophysics Data System (ADS)

A flux of neutrons from an astrophysical source in the Galaxy can be detected in the Pierre Auger Observatory as an excess of cosmic-ray air showers arriving from the direction of the source. To avoid the statistical penalty for making many trials, classes of objects are tested in combinations as nine "target sets," in addition to the search for a neutron flux from the Galactic center or from the Galactic plane. Within a target set, each candidate source is weighted in proportion to its electromagnetic flux, its exposure to the Auger Observatory, and its flux attenuation factor due to neutron decay. These searches do not find evidence for a neutron flux from any class of candidate sources. Tabulated results give the combined p-value for each class, with and without the weights, and also the flux upper limit for the most significant candidate source within each class. These limits on fluxes of neutrons significantly constrain models of EeV proton emission from non-transient discrete sources in the Galaxy.

Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Bohá?ová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filip?i?, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fuji, T.; Gaior, R.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q. D.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Islo, K.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mari?, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, A. J.; Matthews, J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mi?anovi?, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pe?ala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Peters, C.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.

2014-07-01

382

High energy particle background at neutron spallation sources and possible solutions  

NASA Astrophysics Data System (ADS)

Modern spallation neutron sources are driven by proton beams ~ GeV energies. Whereas low energy particle background shielding is well understood for reactors sources of neutrons (~20 MeV), for high energies (100s MeV to multiple GeV) there is potential to improve shielding solutions and reduce instrument backgrounds significantly. We present initial measured data on high energy particle backgrounds, which illustrate the results of particle showers caused by high energy particles from spallation neutron sources. We use detailed physics models of different materials to identify new shielding solutions for such neutron sources, including laminated layers of multiple materials. In addition to the steel and concrete, which are used traditionally, we introduce some other options that are new to the neutron scattering community, among which there are copper alloys as used in hadronic calorimeters in high energy physics laboratories. These concepts have very attractive energy absorption characteristics, and simulations predict that the background suppression could be improved by one or two orders of magnitude. These solutions are expected to be great benefit to the European Spallation Source, where the majority of instruments are potentially affected by high energy backgrounds, as well as to existing spallation sources.

Cherkashyna, N.; Kanaki, K.; Kittelmann, T.; Filges, U.; Deen, P.; Herwig, K.; Ehlers, G.; Greene, G.; Carpenter, J.; Connatser, R.; Hall-Wilton, R.; Bentley, P. M.

2014-07-01

383

A Targeted Search for Point Sources of EeV Neutrons  

E-print Network

A flux of neutrons from an astrophysical source in the Galaxy can be detected in the Pierre Auger Observatory as an excess of cosmic-ray air showers arriving from the direction of the source. To avoid the statistical penalty for making many trials, classes of objects are tested in combinations as nine "target sets", in addition to the search for a neutron flux from the Galactic Center or from the Galactic Plane. Within a target set, each candidate source is weighted in proportion to its electromagnetic flux, its exposure to the Auger Observatory, and its flux attenuation factor due to neutron decay. These searches do not find evidence for a neutron flux from any class of candidate sources. Tabulated results give the combined p-value for each class, with and without the weights, and also the flux upper limit for the most significant candidate source within each class. These limits on fluxes of neutrons significantly constrain models of EeV proton emission from non-transient discrete sources in the Galaxy.

Aab, A; Aglietta, M; Ahlers, M; Ahn, E J; Samarai, I Al; Albuquerque, I F M; Allekotte, I; Allen, J; Allison, P; Almela, A; Castillo, J Alvarez; Alvarez-Muñiz, J; Batista, R Alves; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Aramo, C; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Badescu, A M; Barber, K B; Bäuml, J; Baus, C; Beatty, J J; Becker, K H; Bellido, J A; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, F; Blanco, M; Bleve, C; Blümer, H; Bohá?ová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brancus, I; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Buscemi, M; Caballero-Mora, K S; Caccianiga, B; Caccianiga, L; Candusso, M; Caramete, L; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Chavez, A G; Cheng, S H; Chiavassa, A; Chinellato, J A; Chudoba, J; Cilmo, M; Clay, R W; Cocciolo, G; Colalillo, R; Collica, L; Coluccia, M R; Conceição, R; Contreras, F; Cooper, M J; Coutu, S; Covault, C E; Criss, A; Cronin, J; Curutiu, A; Dallier, R; Daniel, B; Dasso, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; de Jong, S J; Neto, J R T de Mello; De Mitri, I; de Oliveira, J; de Souza, V; del Peral, L; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Di Matteo, A; Diaz, J C; Castro, M L Díaz; Diep, P N; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dong, P N; Dorofeev, A; Dova, M T; Ebr, J; Engel, R; Erdmann, M; Erfani, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Luis, P Facal San; Falcke, H; Fang, K; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Fernandes, M; Fick, B; Figueira, J M; Filevich, A; Filip?i?, A; Fox, B D; Fratu, O; Fröhlich, U; Fuchs, B; Fuji, T; Gaior, R; García, B; Roca, S T Garcia; Garcia-Gamez, D; Garcia-Pinto, D; Garilli, G; Bravo, A Gascon; Gate, F; Gemmeke, H; Ghia, P L; Giaccari, U; Giammarchi, M; Giller, M; Glaser, C; Glass, H; Albarracin, F Gomez; Berisso, M Gómez; Vitale, P F Gómez; Gonçalves, P; Gonzalez, J G; Gookin, B; Gorgi, A; Gorham, P; Gouffon, P; Grebe, S; Griffith, N; Grillo, A F; Grubb, T D; Guardincerri, Y; Guarino, F; Guedes, G P; Hansen, P; Harari, D; Harrison, T A; Harton, J L; Hasankiadeh, Q D; Haungs, A; Hebbeker, T; Heck, D; Heimann, P; Herve, A E; Hill, G C; Hojvat, C; Hollon, N; Holt, E; Homola, P; Hörandel, J R; Horvath, P; Hrabovský, M; Huber, D; Huege, T; Insolia, A; Isar, P G; Islo, K; Jandt, I; Jansen, S; Jarne, C; Josebachuili, M; Kääpä, A; Kambeitz, O; Kampert, K H; Kasper, P; Katkov, I; Kégl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Krause, R; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; La Rosa, G; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Coz, S Le; Leão, M S A B; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lu, L; Lucero, A; Ludwig, M; Lyberis, H; Maccarone, M C; Malacari, M; Maldera, S; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Mari?, I C; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Martraire, D; Meza, J J Masías; Mathes, H J; Mathys, S; Matthews, A J; Matthews, J; Matthiae, G; Maurel, D; Maurizio, D; Mayotte, E; Mazur, P O; Medina, C; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Messina, S; Meyhandan, R; Mi?anovi?, S; Micheletti, M I; Middendorf, L; Minaya, I A; Miramonti, L; Mitrica, B; Molina-Bueno, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morello, C; Moreno, J C; Mostafá, M; Moura, C A; Muller, M A; Müller, G; Münchmeyer, M; Mussa, R; Navarra, G; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Niechciol, M; Niemietz, L; Niggemann, T; Nitz, D; Nosek, D; Novotny, V; Nožka, L; Ochilo, L; Olinto, A; Oliveira, M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Papenbreer, P; Parente, G; Parra, A; Pastor, S; Paul, T; Pech, M; P?kala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Peters, C; Petrera, S; Petrolini, A; Petrov, Y; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Plum, M; Porcelli, A; Porowski, C; Privitera, P; Prouza, M; Purrello, V; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rizi, V; Roberts, J; de Carvalho, W Rodrigues; Cabo, I Rodriguez; Fernandez, G Rodriguez; Rojo, J Rodriguez; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Roulet, E; Rovero, A C; Rühle, C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Greus, F Salesa; Salina, G; Sánchez, F; Sanchez-Lucas, P; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarmento, R; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, A

2014-01-01

384

Consideration of a ultracold neutron source in two-dimensional cylindrical geometry by taking simulated boundaries  

NASA Astrophysics Data System (ADS)

A new idea to calculate ultracold neutron (UCN) production by using Monte Carlo simulation method to calculate the cold neutron (CN) flux and an analytical approach to calculate the UCN production from the simulated CN flux was given. A super-thermal source (UCN source) was modeled based on an arrangement of D2O and solid D2 (sD2). The D2O was investigated as the neutron moderator, and sD2 as the converter. In order to determine the required parameters, a two-dimensional (2D) neutron balance equation written in Matlab was combined with the MCNPX simulation code. The 2D neutron-transport equation in cylindrical (? - z) geometry was considered for 330 neutron energy groups in the sD2. The 2D balance equation for UCN and CN was solved using simulated CN flux as boundary value. The UCN source dimensions were calculated for the development of the next UCN source. In the optimal condition, the UCN flux and the UCN production rate (averaged over the sD2 volume) equal to 6.79 × 106 cm-2s-1 and 2.20 ×105 cm-3s-1, respectively.

Gheisari, R.; Firoozabadi, M. M.; Mohammadi, H.

2014-01-01

385

Consideration of a ultracold neutron source in two-dimensional cylindrical geometry by taking simulated boundaries  

SciTech Connect

A new idea to calculate ultracold neutron (UCN) production by using Monte Carlo simulation method to calculate the cold neutron (CN) flux and an analytical approach to calculate the UCN production from the simulated CN flux was given. A super-thermal source (UCN source) was modeled based on an arrangement of D{sub 2}O and solid D{sub 2} (sD{sub 2}). The D{sub 2}O was investigated as the neutron moderator, and sD{sub 2} as the converter. In order to determine the required parameters, a two-dimensional (2D) neutron balance equation written in Matlab was combined with the MCNPX simulation code. The 2D neutron-transport equation in cylindrical (? ? z) geometry was considered for 330 neutron energy groups in the sD{sub 2}. The 2D balance equation for UCN and CN was solved using simulated CN flux as boundary value. The UCN source dimensions were calculated for the development of the next UCN source. In the optimal condition, the UCN flux and the UCN production rate (averaged over the sD{sub 2} volume) equal to 6.79?×?10{sup 6} cm{sup ?2}s{sup ?1} and 2.20 ×10{sup 5} cm{sup ?3}s{sup ?1}, respectively.

Gheisari, R., E-mail: gheisari@pgu.ac.ir [Physics Department, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Nuclear Energy Research Center, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Firoozabadi, M. M.; Mohammadi, H. [Department of Physics, University of Birjand, Birjand 97175 (Iran, Islamic Republic of)] [Department of Physics, University of Birjand, Birjand 97175 (Iran, Islamic Republic of)

2014-01-15

386

Performance characteristics of a polyethylene collimator with an EJ-426 detector in neutron source localisation  

NASA Astrophysics Data System (ADS)

In this paper, characteristics of neutron source localisation using an EJ-426 detector with a polyethylene collimator are presented. The detector is placed inside of the polyethylene collimator, where the collimator has a constant internal diameter and external diameter gradually increases towards the back end. The combined detector-collimator unit was mounted onto an equatorial mount and, data were collected from an ultra-fast mixed-field analyser. Neutron images have been produced to characterise the area investigated in real-time. Radiation images are fundamentally related to the detector efficiency and to the collimator geometry. In order to characterise the neutron source localisation capability of the polyethylene collimator, with an EJ-426 detector, experiments have been carried out using three different neutron sources. Results indicate that the existing design of the polyethylene collimator is suitable for localisation of low energy neutron sources. The measurements were performed in the low-scatter facility of the Neutron Metrology, National Physical Laboratory, Teddington, UK.

Gamage, K. A. A.; Crompton, A. J.; Joyce, M. J.

2014-08-01

387

Standardisation of water-moderated 241Am-Be neutron source using De Pangher neutron long counter: experimental and Monte Carlo modelling.  

PubMed

A convenient neutron source is made for calibration of neutron survey instruments and personal dosimeters that are used in various nuclear installations such as fuel reprocessing, waste management, fuel fabrication and oil and well logging facilities, etc. This source consists of a bare (241)Am-Be neutron source placed at the centre of a 15-cm radius stainless steel spherical shell filled with distilled water. This paper describes the standardisation of the source at Bhabha Atomic Research Centre, using De Pangher neutron long counter both experimentally and using the Monte Carlo simulation. The ratio of neutron yield of water moderated to the bare (241)Am-Be neutron source was found to be 0.573. From the simulation, the neutron-fluence-weighted average energy of water-moderated (241)Am-Be source (fluence-weighted average energy of 2.25 MeV, dose-weighted average energy of 3.55 MeV) was found to be nearly the same as that of a (252)Cf source (fluence-weighted average energy of 2.1 MeV, dose-weighted average energy of 2.3 MeV). This source can be used for calibration in addition to (252)Cf, to study the variation in response of neutron monitoring instruments. PMID:21498862

Ghodke, Shobha; Kumari, Sujatha; Singh, Yashoda; Sathian, V; Mahant, A K; Sharma, D N

2012-02-01

388

Physics Analyses in the Design of the HFIR Cold Neutron Source  

Microsoft Academic Search

Physics analyses have been performed to characterize the performance of the cold neutron source to be installed in the High Flux Isotope Reactor at the Oak Ridge National Laboratory in the near future. This paper provides a description of the physics models developed, and the resulting analyses that have been performed to support the design of the cold source. These

Bucholz

1999-01-01

389

Design calculations for the ANS cold neutron source Part II. Heating rates  

Microsoft Academic Search

Calculated results to aid in the design of a liquid deuterium cold source in the D2O reflector of a high-flux reactor are presented. The results presented include a comparison with experimental data, neutron leakage current as a function of wavelength, and heating rates in liquid deuterium and the other materials of the cold source.

R. G. Alsmiller; R. A. Lillie

1992-01-01

390

Secondary Startup Neutron Sources as a Source of Tritium in a Pressurized Water Reactor (PWR) Reactor Coolant System (RCS)  

SciTech Connect

The hypothesis of this paper is that the Zircaloy clad fuel source is minimal and that secondary startup neutron sources are the significant contributors of the tritium in the RCS that was previously assigned to release from fuel. Currently there are large uncertainties in the attribution of tritium in a Pressurized Water Reactor (PWR) Reactor Coolant System (RCS). The measured amount of tritium in the coolant cannot be separated out empirically into its individual sources. Therefore, to quantify individual contributors, all sources of tritium in the RCS of a PWR must be understood theoretically and verified by the sum of the individual components equaling the measured values.

Shaver, Mark W.; Lanning, Donald D.

2010-02-01

391

Progress on the Construction of the PULSTAR Solid Deuterium Ultracold Neutron Source  

NASA Astrophysics Data System (ADS)

An ultracold neutron (UCN) source utilizing solid deuterium is being constructed at the 1MW PULSTAR nuclear reactor on the campus of North Carolina State University. The final stages of assembly and commissioning are underway. The overall design, status of construction, and benchmarking measurements will be discussed. The UCN source design is based on detailed simulations including MCNP, UCN transport Monte Carlo, and CFD of the cryogenic systems. The source will be available for developing general UCN experiment technology, such as guides and detectors in support of current neutron EDM and UCNA projects. Other plans include fundamental physics measurements such as neutron beta decay and gravity measurements, as well as development of new techniques to use UCN in material and surface physics studies. The expected experimental density of UCN will be competitive with currently available sources, including those at significantly more powerful reactors. This work is supported in part by NSF grant #0314114 and funds from the DOE INIE program.

Palmquist, Grant; Cottrell, Chris; Golub, Robert; Huffman, Paul; Young, Albert; Hawari, Ayman; Korobkina, Ekaterina; Wehring, Bernard

2009-10-01

392

Neutron production using a pyroelectric driven target coupled with a gated field ionization source  

SciTech Connect

A palm sized, portable neutron source would be useful for widespread implementation of detection systems for shielded, special nuclear material. We present progress towards the development of the components for an ultracompact neutron generator using a pulsed, meso-scale field ionization source, a deuterated (or tritiated) titanium target driven by a negative high voltage lithium tantalate crystal. Neutron production from integrated tests using an ion source with a single, biased tungsten tip and a 3 Multiplication-Sign 1 cm, vacuum insulated crystal with a plastic deuterated target are presented. Component testing of the ion source with a single tip produces up to 3 nA of current. Dielectric insulation of the lithium tantalate crystals appears to reduce flashover, which should improve the robustness. The field emission losses from a 3 cm diameter crystal with a plastic target and 6 cm diameter crystal with a metal target are compared.

Ellsworth, J. L.; Tang, V.; Falabella, S. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Naranjo, B.; Putterman, S. [University of California Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90095 (United States)

2013-04-19

393

Status of Multi-Reflection Time-of-Flight Spectrometer for Radio-Isotopes at RIKEN  

NASA Astrophysics Data System (ADS)

The new Radioactive Ion Beam Factory at RIKEN will provide unprecedented access to exotic neutron-rich isotopes such as are important for r-process nucleosynthesis. To utilize these exotic RI beams, we continue to develop a Multi- Reflection Time-of-Flight (MRTOF) spectrograph. Our system will make use on an advanced gas cell to thermalize relativistic ions of exotic radioactive ions and transfer them to high-vacuum quickly and efficiently. An RF ion trap of novel geometry will cool and bunch ions extracted from the gas cell. A pair of electrostatic mirrors creates an extended flight path of 1 km or more for the ions. By combining high-quality ion pulses with the long flight path, simulations have indicated that the device should be capable to achieve mass resolving powers of R=m?m>500,000. The high-resolving power will allow the MRTOF spectrograph to be competitive with Penning trap mass spectrometers. We will present the current state of development of our MRTOF along with an overview of our anticipated impact on the nuclear landscape.

Schury, Peter; Wada, Michiharu; Sonoda, Tetsu; Takamine, Aiko; Yamazaki, Yasunori; Wollnik, Hermann

2009-10-01

394

A Strongly Heated Neutron Star in the Transient Z Source MAXI J0556-332  

NASA Astrophysics Data System (ADS)

We present Chandra, XMM-Newton, and Swift observations of the quiescent neutron star in the transient low-mass X-ray binary MAXI J0556-332. Observations of the source made during outburst (with the Rossi X-ray Timing Explorer) reveal tracks in its X-ray color-color and hardness-intensity diagrams that closely resemble those of the neutron-star Z sources, suggesting that MAXI J0556-332 had near- or super-Eddington luminosities for a large part of its ~16 month outburst. A comparison of these diagrams with those of other Z sources suggests a source distance of 46 ± 15 kpc. Fits to the quiescent spectra of MAXI J0556-332 with a neutron-star atmosphere model (with or without a power-law component) result in distance estimates of 45 ± 3 kpc, for a neutron-star radius of 10 km and a mass of 1.4 M ?. The spectra show the effective surface temperature of the neutron star decreasing monotonically over the first ~500 days of quiescence, except for two observations that were likely affected by enhanced low-level accretion. The temperatures we obtain for the fits that include a power law (kT_eff? = 184-308 eV) are much higher than those seen for any other neutron star heated by accretion, while the inferred cooling (e-folding) timescale (~200 days) is similar to other sources. Fits without a power law yield higher temperatures (kT_eff? = 190-336 eV) and a shorter e-folding time (~160 days). Our results suggest that the heating of the neutron-star crust in MAXI J0556-332 was considerably more efficient than for other systems, possibly indicating additional or more efficient shallow heat sources in its crust.

Homan, Jeroen; Fridriksson, Joel K.; Wijnands, Rudy; Cackett, Edward M.; Degenaar, Nathalie; Linares, Manuel; Lin, Dacheng; Remillard, Ronald A.

2014-11-01

395

A Photo-neutron Source for a Sub-Critical Nuclear Reactor Program  

NASA Astrophysics Data System (ADS)

Experiments to benchmark photo-neutron production calculations for an Accelerator Driven Sub-Critical System (ADS) are described. A photo-nuclear based neutron source with output > 1013 n/sec has been proposed as a driver for a program using the sub-critical assembly at Idaho State University. The program is intended to study ADS control issues arising from coupling an accelerator neutron source with a sub-critical assembly. The experiments were performed using the 20 MeV electron linear accelerator at the Idaho Accelerator Center (IAC). Results of calculations, that were made using ACCEPT, PINP, MCNP, and MCNPX codes to optimize photo-nuclear based neutron conversion targets, are compared to experimental data for a single energy measurement.

Reda, M. A.; Harmon, J. F.; Sadineni, S. B.

2003-08-01

396

Evaluation of the characteristics of the neutron reference field using D2O-moderated 252Cf source.  

PubMed

The ambient/personal dose equivalent per fluence for D(2)O moderated (252)Cf neutron source was determined by measurement. An appropriate subtraction of the scattered neutrons is required for the accurate measurement of direct neutrons. A cubic shadow object was used for the subtraction of the scattered neutrons from the surroundings. The scattered neutrons to be subtracted vary with the position of the shadow object due to the large volume of the source. Using the Monte Carlo code MCNP-4C, the optimum positions of the shadow object were surveyed for subtracting the scattered neutrons. The energy spectra of direct neutrons were measured in the optimum position. The dosimetric parameters for the D(2)O moderated (252)Cf neutron source were reasonable, taking into account the uncertainties of the parameters. PMID:17525058

Kowatari, M; Fujii, K; Takahashi, M; Yoshizawa, M; Shimizu, S; Kawasaki, K; Yamaguchi, Y

2007-01-01

397

Ultracold neutron source at the PULSTAR reactor: Engineering design and cryogenic testing  

NASA Astrophysics Data System (ADS)

Construction is completed and commissioning is in progress for an ultracold neutron (UCN) source at the PULSTAR reactor on the campus of North Carolina State University. The source utilizes two stages of neutron moderation, one in heavy water at room temperature and the other in solid methane at ~ 40 K, followed by a converter stage, solid deuterium at 5 K, that allows a single down scattering of cold neutrons to provide UCN. The UCN source rolls into the thermal column enclosure of the PULSTAR reactor, where neutrons will be delivered from a bare face of the reactor core by streaming through a graphite-lined assembly. The source infrastructure, i.e., graphite-lined assembly, heavy-water system, gas handling system, and helium liquefier cooling system, has been tested and all systems operate as predicted. The research program being considered for the PULSTAR UCN source includes the physics of UCN production, fundamental particle physics, and material surface studies of nanolayers containing hydrogen. In the present paper we report details of the engineering and cryogenic design of the facility as well as results of critical commissioning tests without neutrons.

Korobkina, E.; Medlin, G.; Wehring, B.; Hawari, A. I.; Huffman, P. R.; Young, A. R.; Beaumont, B.; Palmquist, G.

2014-12-01

398

Research and Development of Compact Neutron Sources based on Inertial Electrostatic Confinement Fusion  

Microsoft Academic Search

Recent progress is described in the research and development of an inertial-electrostatic confinement fusion (IECF) device. Use of a water-cooling jacket with non-uniform thickness shows promising success for landmine detection application, such as effective channeling of neutron flux toward the target and a very stable dc yield in excess of 107 D-D neutrons\\/sec. Addition of an ion source to the

Kai Masuda; Teruhisa Takamatsu; Kiyoshi Yoshikawa; Tsuyoshi Misawa; Seiji Shiroya; Yoshiyuki Takahashi; Takeshi Fujimoto; Tomoya Nakagawa; Taiju Kajiwara; Kazunobu Nagasaki

2009-01-01

399

Conceptual study of cold-neutron source in China Advanced Research Reactor  

Microsoft Academic Search

The fundamental design of the cold-neutron source (CNS) to be installed in the China Advanced Research Reactor (CARR) was prepared. The principal design criterion of the fundamental CNS design is the maximum increase of cold-neutron flux considering nuclear heating to be removed and safety problem. All nuclear calculations were performed with MCNP (version 4A) computer code using a complete 3D

Feng Shen; Luzheng Yuan

2002-01-01

400

Updated pipe break analysis for Advanced Neutron Source Reactor conceptual design  

Microsoft Academic Search

The Advanced Neutron Source Reactor (ANSR) is a research reactor to be built at the Oak Ridge National Laboratory that will supply the highest continuous neutron flux levels of any reactor in the world. It uses plate-type fuel with high-mass-flux and highly subcooled heavy water as the primary coolant. The Conceptual Safety Analysis for the ANSR was completed in June

M. W. Wendel; N. C. J. Chen; G. L. Yoder

1994-01-01

401

Performance of neon-thermosyphon in the Texas Cold Neutron Source  

Microsoft Academic Search

The Texas Cold Neutron Source (TCNS) is operated in one of the beam ports of the UT-TRIGA 1-MW research reactor. Beams of cold neutrons are produced by means of a cooled moderator contained in an aluminum chamber (7.5-cm diam x 2 cm thick) located in the graphite reflector close to the reactor core. The moderator, mesitylene, is maintained at cryogenic

C. Rios-Martinez; K. Uenlue; T. L. Bauer; B. W. Wehring

1994-01-01

402

The LICORNE Neutron Source and Measurements of Prompt ?-rays Emitted in Fission  

NASA Astrophysics Data System (ADS)

The emission of prompt gamma rays is one of the least measured and least well-understood parts of the fission process. Knowledge of prompt fission gamma spectra, mean energies and multiplicities are important for reactor gamma heating and hence linked to reactor safety. At the IPN Orsay we have developed a unique, directional, fast neutron source called LICORNE, intended initially to facilitate prompt fission gamma measurements. The ability of the IPN Orsay tandem accelerator to produce intense beams of 7Li is exploited to produce quasi mono-energetic neutrons between 0.5 - 4 MeV using the p(7Li, 7Be)n inverse reaction. The available fluxes of up to 7×107 neutrons/second/steradian are comparable to existing installations, but with two added advantages: (i) The kinematic focusing produces a natural neutron beam collimation which allows placement of gamma detectors adjacent to the irradiated sample unimpeded by source neutrons. (ii) The background of scattered neutrons in the experimental hall is drastically reduced. The dedicated neutron converter was commissioned in June 2013

Wilson, J. N.; Lebois, M.; Halipre, P.; Oberstedt, S.; Oberstedt, A.

403

Baseline design of a low energy neutron source at ESS-Bilbao  

NASA Astrophysics Data System (ADS)

This article briefly describes the basic design of the ESS-Bilbao neutron target station as well as its expected neutronic performance. The baseline engineering design, associated ancillary systems, and plant layout for the facility is now complete. A rotating target composed of twenty beryllium plates has been selected as the best choice in terms of both neutron yield and engineering complexity. It will provide neutron beams with a source term of 1015 n s?1 resulting from the direct 9Be(p, xn) reaction using a 75 mA proton beam at 50 MeV. The design envisages a target station equipped with two fully optimized moderators capable of withstanding a proton-beam power of 112 kW. This design is flexible enough to accommodate future upgrades in final proton energy. The envisaged neutron-beam brightness will enable several applications, including the use of cold and thermal neutrons for condensed matter research as well as fast-neutron irradiation studies. We close by discussing the role that this facility may play once the European Spallation Source becomes operational in Lund, Sweden.

Sordo, F.; Fernandez-Alonso, F.; Gonzalez, Miguel A.; Ghiglino, A.; Magán, M.; Terrón, S.; Martínez, F.; de Vicente, J. P.; Vivanco, R.; Bermejo, F. J.; Perlado, J. M.

2014-10-01

404

Study on low activation decoupler material for MW-class spallation neutron sources  

NASA Astrophysics Data System (ADS)

The Japan Spallation Neutron Source (JSNS) at the Japan Proton Accelerator Research Complex (J-PARC) has started its operation on May 30, 2008. The Ag-In-Cd (AIC) alloy was adopted as a decoupler material for two decoupled moderators. A high decoupling energy at 1 eV was for the first time achieved in MW-class spallation neutron sources due to the adoption of the AIC alloy. Although the AIC decoupler is superior in the neutronic performance, it has a demerit in high residual radioactivity due to production of Ag-110 m (half life: 250 days) and Ag-108 m (half life: 418 years). To overcome this demerit, we studied on possibilities of a low activation decoupler material with high decoupling energy as the AIC alloy, that is, Au-In-Cd (AuIC) alloy. Neutronic performance of this material was investigated by using neutronics calculations. As a result, it was found that the AuIC decoupler could provide neutron pulses with almost the same characteristics as those for the AIC decoupler even when the burn-up effects were considered. Excellent low activation property of the AuIC alloy to the AIC alloy was demonstrated by residual radioactivity calculations. On viewpoint of neutronics performance, it was concluded that the AuIC decoupler was available as the substitute of the AIC decoupler.

Harada, M.; Teshigawara, M.; Maekawa, F.; Futakawa, M.

2010-03-01

405

Development of target system for intense neutron source of p-Li reaction.  

PubMed

A target cooling system was developed for an intense neutron source of p-Li reaction. The system consists of target cooling devices and protection devices for lithium evaporation. A pin-structure cooling device was developed to enhance cooling power. Functional graded material was utilized for the evaporation of lithium. Test experiments were performed by using the neutron exposure accelerator system for biological effect experiments (NASBEE) at the National Institute of Radiological Sciences (NIRS) in Japan. The target system was confirmed to be applicable for accelerator-based boron neutron capture therapy. PMID:24786900

Kamada, So; Takada, Masashi; Suda, Mitsuru; Hamano, Tsuyoshi; Imaseki, Hitoshi; Hoshi, Masaharu; Fujii, Ryo; Nakamura, Masaru; Sato, Hitoshi; Higashimata, Atsushi; Arai, Seiji

2014-06-01

406

First Data Acquired on the EQ-SANS Diffractometer at the Spallation Neutron Source  

SciTech Connect

The measurement of the conformation of a Generation-8 Polyamidoamine dendrimer is reported as an initial experiment using the Extended Q-range Small Angle Neutron Scattering (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory (ORNL). The conformation parameters (radius of gyration, thickness of the soft shell etc.) are extracted by model fitting. The results are compared with data collected at the General-Purpose Small Angle Neutron Scattering at the High Flux Isotopic Reactor at ORNL. The comparison shows that the EQ-SANS diffractometer has comparable data statistics and Q resolution with shorter counting time over the measured Q-range.

Liu, Dazhi [ORNL; Hong, Kunlun [ORNL; Gao, Carrie Y [ORNL; Melnichenko, Yuri B [ORNL; Littrell, Ken [ORNL; Smith, Greg [ORNL; Zhao, Jinkui [ORNL

2011-01-01

407

Preliminary Modeling Results of a Thermal Neutron Source Driven with an Electron Linac  

NASA Astrophysics Data System (ADS)

An electron linac, fitted with a standard x-ray converter, can produce high neutron yields in materials with low photonuclear threshold energies, such as D and 9Be. This paper discusses the preliminary MCNP modeling of a thermal neutron source driven with a 10 MeV electron linac operated in the CW mode. Results indicate that a 10 MeV, 10 kW electron linac can produce on the order of 1012 n/sec in a heavy water photoneutron target. The thermal neutron flux in an unreflected heavy water target is nearly 1010 n/cm2/sec. Current modeling results are discussed.

Dale, Gregory E.; Gahl, John M.

2002-12-01

408

Collinear Cluster Tripartition as a Neutron Source--Evaluation of the Setup Parameters  

SciTech Connect

Forthcoming experiments aimed at studying the mechanism of collinear cluster tripartition are planning to be performed with the new facility. Charged products will be registered with the double arm time-of-flight spectrometer composed of mosaics of PIN -diodes and MCP (micro channel plates) based timing detectors. Several tens of {sup 3}He-filled counters will be gathered round the {sup 252}Cf source. In order to choose an optimal configuration of the neutron detector and other parameters of the experiment special modeling has performed using both 'neutron barrel' and known MCNP code. The first test run of the new facility is in progress also its 'neutron skin' in under construction.

Kamanin, D. V.; Kuznetsova, E. A.; Aleksandrov, A. A.; Aleksandrova, I. A.; Borzakov, S. B.; Chelnokov, M. L.; Pham Minh, D.; Kondratyev, N. A.; Kopach, Yu. N.; Panteleev, Ts.; Penionzhkevich, Yu. E.; Svirikhin, A. I.; Sokol, E. A.; Testov, D. A.; Zhuchko, V. E.; Yeremin, A. V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Pyatkov, Yu. V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Moscow Engineering Physics Institute, 115409 Moscow (Russian Federation); Jacobs, N. [Faculty of Military Science, Military Academy, Stellenbosch University, Saldanha 7395 (South Africa); Ryabov, Yu. V. [Institute for Nuclear Research RAN, 117312 Moscow (Russian Federation)

2010-04-30

409

Detailed flux calculations for the conceptual design of the Advanced Neutron Source Reactor  

SciTech Connect

A detailed MCNP model of the Advanced Neutron Source Reactor has been developed. All reactor components inside the reflector tank were included, and all components were highly segmented. Neutron and photon multigroup flux spectra have been calculated for each segment in the model, and thermal-to-fast neutron flux ratios were determined for each component segment. Axial profiles of the spectra are provided for all components of the reactor. Individual segment statistical uncertainties were limited wherever possible, and the group fluxes for all important reflector components have a standard deviation below 10%.

Wemple, C.A. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

1995-05-01

410

SOURCES 4A: A Code for Calculating (alpha,n), Spontaneous Fission, and Delayed Neutron Sources and Spectra  

SciTech Connect

SOURCES 4A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

Madland, D.G.; Arthur, E.D.; Estes, G.P.; Stewart, J.E.; Bozoian, M.; Perry, R.T.; Parish, T.A.; Brown, T.H.; England, T.R.; Wilson, W.B.; Charlton, W.S.

1999-09-01

411

HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE.  

SciTech Connect

This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual design for a focused-beam, hybrid time-of-flight instrument with a crystal monochromator for the SNS called HYSPEC (an acronym for hybrid spectrometer). The proposed instrument has a potential to collect data more than an order of magnitude faster than existing steady-source spectrometers over a wide range of energy transfer ({h_bar}{omega}) and momentum transfer (Q) space, and will transform the way that data in elastic and inelastic single-crystal spectroscopy are collected. HYSPEC is optimized to provide the highest neutron flux on sample in the thermal and epithermal neutron energy ranges at a good-to-moderate energy resolution. By providing a flux on sample several times higher than other inelastic instruments currently planned for the SNS, the proposed instrument will indeed allow unique ground-breaking measurements, and will ultimately make polarized beam studies at a pulsed spallation source a realistic possibility.

SHAPIRO,S.M.; ZALIZNYAK,I.A.

2002-12-30

412

Bright laser-driven neutron source based on the relativistic transparency of solids.  

PubMed

Neutrons are unique particles to probe samples in many fields of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to produce neutrons with energies in excess of 10 MeV. For more than a decade experiments have tried to obtain neutron numbers sufficient for applications. Our recent experiments demonstrated an ion acceleration mechanism based on the concept of relativistic transparency. Using this new mechanism, we produced an intense beam of high energy (up to 170 MeV) deuterons directed into a Be converter to produce a forward peaked neutron flux with a record yield, on the order of 10(10)? n/sr. We present results comparing the two acceleration mechanisms and the first short pulse laser generated neutron radiograph. PMID:25166169

Roth, M; Jung, D; Falk, K; Guler, N; Deppert, O; Devlin, M; Favalli, A; Fernandez, J; Gautier, D; Geissel, M; Haight, R; Hamilton, C E; Hegelich, B M; Johnson, R P; Merrill, F; Schaumann, G; Schoenberg, K; Schollmeier, M; Shimada, T; Taddeucci, T; Tybo, J L; Wagner, F; Wender, S A; Wilde, C H; Wurden, G A

2013-01-25

413

Neutron Capture gamma ENDF libraries for modeling and identification of neutron sources  

SciTech Connect

There are a number of inaccuracies and data omissions with respect to gammas from neutron capture in the ENDF libraries used as field reference information and by modeling codes used in JTOT. As the use of Active Neutron interrogation methods is expanded, these shortfalls become more acute. A new, more accurate and complete evaluated experimental database of gamma rays (over 35,000 lines for 262 isotopes up to U so far) from thermal neutron capture has recently become available from the IAEA. To my knowledge, none of this new data has been installed in ENDF libraries and disseminated. I propose to upgrade libraries of {sup 184,186}W, {sup 56}Fe, {sup 204,206,207}Pb, {sup 104}Pd, and {sup 19}F the 1st year. This will involve collaboration with Richard Firestone at LBL in evaluating the data and installing it in the libraries. I will test them with the transport code MCNP5.

Sleaford, B

2007-10-29

414

Nuclear heat load calculations for the NBSR cold neutron source using MCNP  

Microsoft Academic Search

A liquid-hydrogen (LH2) cold neutron source is being designed for installation in the 20-MW National Bureau of Standards reactor (NBSR) at National Institute of Standards and Technology to replace the D[sub 2]O-ice cold source currently in use. An accurate estimate of the heat deposited in the cold source is needed to ensure that it can be adequately cooled for successful

M. Blau; J. M. Rowe; R. E. Williams

1993-01-01

415

Compact D-D Neutron Source-Driven Subcritical Multiplier and Beam-Shaping Assembly for Boron Neutron Capture Therapy  

SciTech Connect

This work assesses the feasibility of using a small, safe, and inexpensive keff 0.98 subcritical fission assembly [subcritical neutron multiplier (SCM)] to amplify the treatment neutron beam intensity attainable from a compact deuterium-deuterium (D-D) fusion neutron source delivering [approximately]1012 n/s. The objective is to reduce the treatment time for deep-seated brain tumors to [approximately]1 h. The paper describes the optimal SCM design and two optimal beam-shaping assemblies (BSAs) - one designed to maximize the dose rate and the other designed to maximize the total dose that can be delivered to a deep-seated tumor. The neutron beam intensity amplification achieved with the optimized SCM and BSA results in an increase in the treatment dose rate by a factor of 18: from 0.56 Gy/h without the SCM to 10.1 Gy/h. The entire SCM is encased in an aluminum structure. The total amount of 20% enriched uranium required for the SCM is 8.5 kg, and the cost (not including fabrication) is estimated to be less than $60,000. The SCM power level is estimated at 400 W when driven by a 1012 n/s D-D neutron source. This translates into consumption of only [approximately]0.6% of the initially loaded 235U atoms during 50 years of continuous operation and implies that the SCM could operate continuously for the entire lifetime of the facility without refueling. Cooling the SCM does not pose a challenge; it may be accomplished by natural circulation as the maximum heat flux is only 0.034 W/cm2.

Francesco Ganda; Jasmina Vujic; Ehud Greenspan; Ka-Ngo Leung

2010-12-01

416

Discharge characteristics of a penning ion source for compact neutron generator  

NASA Astrophysics Data System (ADS)

We investigate the discharge characteristics of a penning ion source for a compact sealed neutron generator in DC mode. A measuring system consisting of console, vacuum gauges, and teslameter is established. By using the measuring system, the discharge current as a function of ion source voltage, gas pressure, and magnetic field is studied. The results show that the neutron generator can operate in a safe and steady state when the experimental parameters are as follows: ion source voltage of 1.2-2 kV, gas pressure of 4×10-2-8×10-2 Pa, and magnetic field of 0.3-0.5 T. Within these ranges, the neutron yield of the generator can reach 2×108 n/s.

Liu, Weibo; Li, Mingjuan; Gao, Kun; Gu, Deshan

2014-12-01

417

Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources  

SciTech Connect

The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which make Rietveld refinement possible for complex structures. In this paper we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods. 50 refs., 12 figs., 14 tabs.

David, W.I.F. (Rutherford Appleton Lab., Chilton (UK)); Jorgensen, J.D. (Argonne National Lab., IL (USA))

1990-10-01

418

Plans for a Collaboratively Developed Distributed Control System for the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) is an accelerator-based pulsed neutron source to be built in Oak Ridge, Tennessee. The facility has five major sections - a ''front end'' consisting of a 65 keV H{sup -} ion source followed by a 2.5 MeV RFQ; a 1 GeV linac; a storage ring; a 1MW spallation neutron target (upgradeable to 2 MW); the conventional facilities to support these machines and a suite of neutron scattering instruments to exploit them. These components will be designed and implemented by five collaborating institutions: Lawrence Berkeley National Laboratory (Front End), Los Alamos National Laboratory (Linac); Brookhaven National Laboratory (Storage Ring); Argonne National Laboratory (Instruments); and Oak Ridge National Laboratory (Neutron Source and Conventional Facilities). It is proposed to implement a fully integrated control system for all aspects of this complex. The system will be developed collaboratively, with some degree of local autonomy for distributed systems, but centralized accountability. Technical integration will be based upon the widely-used EPICS control system toolkit, and a complete set of hardware and software standards. The scope of the integrated control system includes site-wide timing and synchronization, networking and machine protection. This paper discusses the technical and organizational issues of planning a large control system to be developed collaboratively at five different institutions, the approaches being taken to address those issues, as well as some of the particular technical challenges for the SNS control system.

DeVan, W.R.; Gurd, D.P.; Hammonds, J.; Lewis, S.A.; Smith, J.D.

1999-03-29

419

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

2008-10-22

420

Neutron Spectrum Determination of the p(35 MeV)-Be Source Reaction by the Dosimetry Foils Method  

NASA Astrophysics Data System (ADS)

The thick target neutron field of source reaction p + Be was investigated for a proton energy of 35 MeV. The spectral neutron flux at 0? for two target-to-sample distances was determined by using the dosimetry foils activation method. The present p(35)-Be white neutron spectra provide the suitable basis for irradiation experiments and integral tests of nuclear data.

Štefánik, M.; Bém, P.; Götz, M.; Katovský, K.; Majerle, M.; Novák, J.; Šime?ková, E.

2014-05-01

421

Low-level measuring techniques for neutrons: High accuracy neutron source strength determination and fluence rate measurement at an underground laboratory  

NASA Astrophysics Data System (ADS)

We report on measuring techniques for neutrons that have been developed at the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. PTB has characterized radioactive sources used in the BOREXINO and XENON100 experiments. For the BOREXINO experiment, a 228Th gamma radiation source was required which would not emit more than 10 neutrons per second. The determination of the neutron emission rate of this specially designed 228Th source was challenging due to the low neutron emission rate and because the ratio of neutron to gamma radiation was expected to be extremely low, of the order of 10-6. For the XENON100 detector, PTB carried out a high accuracy measurement of the neutron emission rate of an AmBe source. PTB has also done measurements in underground laboratories. A two month measurement campaign with a set of 3He-filled proportional counters was carried out in PTB's former UDO underground laboratory at the Asse salt mine. The aim of the campaign was to determine the intrinsic background of detectors, which is needed for the analysis of data taken in lowintensity neutron fields. At a later time, PTB did a preliminary measurement of the neutron fluence rate at the underground laboratory Felsenkeller operated by VKTA. By taking into account data from UDO, Felsenkeller, and detector calibrations made at the PTB facility, it was possible to estimate the neutron fluence rate at the Felsenkeller underground laboratory.

Zimbal, Andreas; Degering, Detlev; Reginatto, Marcel; Schuhmacher, Helmut; Wiegel, Burkhard; Zuber, Kai

2013-08-01

422

Low-level measuring techniques for neutrons: High accuracy neutron source strength determination and fluence rate measurement at an underground laboratory  

SciTech Connect

We report on measuring techniques for neutrons that have been developed at the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. PTB has characterized radioactive sources used in the BOREXINO and XENON100 experiments. For the BOREXINO experiment, a {sup 228}Th gamma radiation source was required which would not emit more than 10 neutrons per second. The determination of the neutron emission rate of this specially designed {sup 228}Th source was challenging due to the low neutron emission rate and because the ratio of neutron to gamma radiation was expected to be extremely low, of the order of 10{sup ?6}. For the XENON100 detector, PTB carried out a high accuracy measurement of the neutron emission rate of an AmBe source. PTB has also done measurements in underground laboratories. A two month measurement campaign with a set of {sup 3}He-filled proportional counters was carried out in PTB's former UDO underground laboratory at the Asse salt mine. The aim of the campaign was to determine the intrinsic background of detectors, which is needed for the analysis of data taken in lowintensity neutron fields. At a later time, PTB did a preliminary measurement of the neutron fluence rate at the underground laboratory Felsenkeller operated by VKTA. By taking into account data from UDO, Felsenkeller, and detector calibrations made at the PTB facility, it was possible to estimate the neutron fluence rate at the Felsenkeller underground laboratory.

Zimbal, Andreas; Reginatto, Marcel; Schuhmacher, Helmut; Wiegel, Burkhard [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)] [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Degering, Detlev [Verein für Kernverfahrenstechnik und Analytik Rossendorf e. V. (VKTA), D-01314 Dresden (Germany)] [Verein für Kernverfahrenstechnik und Analytik Rossendorf e. V. (VKTA), D-01314 Dresden (Germany); Zuber, Kai [Technische Universität Dresden, D-01069 Dresden (Germany)] [Technische Universität Dresden, D-01069 Dresden (Germany)

2013-08-08

423

Measurement and calculation of the emission anisotropy of an X1 252Cf neutron source.  

PubMed

The authors have measured the emission anisotropy from a (252)Cf spontaneous fission neutron source in an X1 encapsulation. The measurements were made in a large low-scatter laboratory using a long counter, and data were taken at angles varying in 10 degrees steps from 0 degrees to 180 degrees relative to the cylindrical axis of the source. Corrections were made for room scatter, loss of neutrons due to air scatter and detector dead time. Calculations corresponding to these measurements were subsequently carried out using the two Monte Carlo codes MCNP and MCBEND, and the results are compared with the measurements and with each other. PMID:17496296

Hawkes, N P; Freedman, R; Tagziria, H; Thomas, D J

2007-01-01

424

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

SciTech Connect

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

2011-03-01

425

Improvements to the internal and external antenna H{sup ?} ion sources at the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30–40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ?55 mA of H{sup ?} beam current (?1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H{sup ?} yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented.

Welton, R. F., E-mail: welton@ornl.gov; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Pillar, C.; Santana, M.; Stockli, M. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States)] [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States); Dudnikov, V. G. [Muons, Inc., 552 N. Batavia Avenue, Batavia, Illinois 60510 (United States)] [Muons, Inc., 552 N. Batavia Avenue, Batavia, Illinois 60510 (United States); Turvey, M. W. [Villanova University, 800E. Lancaster Ave, Villanova, Pennsylvania 19085 (United States)] [Villanova University, 800E. Lancaster Ave, Villanova, Pennsylvania 19085 (United States)

2014-02-15

426

Pulsed neutrons: one year of experience with the new source at Argonne National Laboratory  

SciTech Connect

The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source based on a 500-MeV proton accelerator operating at 30 Hz and with an average proton current of approx. 10 ..mu..A. Neutron-scattering instruments for elastic scattering include two powder diffractometers, a single-crystal diffractometer based on the Laue method and employing a large (30 x 30 cm) position-sensitive scintillation detector, a small-angle diffractometer using a position-sensitive detector, and a polarized-neutron diffractometer which will utilize the spin-refrigerator device to obtain a beam of white polarized neutrons. For inelastic scattering, we presently have the crystal-analyzer spectrometer and two chopper spectrometers capable of providing monoenergetic incident neutron beams of between 100 and 600 MeV. From its inception IPNS has been operating in a user mode and the selection of experiments is made by a Program Committee twice a year on the basis of the scientific merit of submitted proposals.

Lander, G.H.

1982-01-01

427

Assessment of neutron dosemeters around standard sources and nuclear fissile objects.  

PubMed

In order to evaluate the neutron doses around nuclear fissile objects, a comparative study has been made on several neutron dosemeters: bubble dosemeters, etched-track detectors (CR-39) and 3He-filled proportional counters used as dose-rate meters. The measurements were made on the ambient and the personal dose equivalents H*(10) and Hp(10). Results showed that several bubble dosemeters should have been used due to a low reproducibility in the measurements. A strong correlation with the neutron energy was also found, with about a 30% underestimation of Hp(10) for neutrons from the PuBe source, and about a 9% overestimation for neutrons from the 252Cf source. Measurements of the nuclear fissile objects were made using the CR-39 and the dose-rate meters. The CR-39 led to an underestimation of 30% with respect to the neutron dose-rate meter measurements. In addition, the MCNP calculation code was used in the different configurations. PMID:12382734

Raimondi, N; Tournier, B; Groetz, J E; Piot, J; Riebler, E; Crovisier, P; Chambaudet, A; Cabanné, N

2002-01-01

428

Ramping up the Spallation Neutron Source beam power with the H{sup -} source using 0 mg Cs/day  

SciTech Connect

This paper describes the ramp up of the beam power for the Spallation Neutron Source by ramping up the pulse length, the repetition rate, and the beam current emerging from the H{sup -} source. Starting out with low repetition rates ({<=}10 Hz) and short pulse lengths ({<=}0.2 ms), the H{sup -} source and low-energy beam transport delivered from Lawrence Berkeley National Laboratory exceeded the requirements with almost perfect availability. This paper discusses the modifications that were required to exceed 0.2 ms pulse length and 0.2% duty factor with acceptable availability and performance. Currently, the source is supporting neutron production at 1 MW with 38 mA linac beam current at 60 Hz and 0.9 ms pulse length. The pulse length will be increased to {approx}1.1 ms to meet the requirements for neutron production with a power between 1 and 1.4 MW. A medium-energy beam transport (MEBT) beam current of 46 mA with a 5.4% duty factor has been demonstrated for 32 h. A 56 mA MEBT beam current with a 4.1% duty factor has been demonstrated for 20 min at the conclusion of a 12-day production run. This is close to the 59 mA needed for 3 MW neutron productions. Also notable is the Cs{sub 2}CrO{sub 4} cesium system, which dispenses {approx}10 mg of Cs during the startup of the ion source, sufficient for producing the required 38 mA for 4 weeks without significant degradation.

Stockli, M. P.; Han, B.; Murray, S. N.; Pennisi, T. R.; Santana, M.; Welton, R. F. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)

2010-02-15

429

A feasibility study of the Tehran research reactor as a neutron source for BNCT.  

PubMed

Investigation on the use of the Tehran Research Reactor (TRR) as a neutron source for Boron Neutron Capture Therapy (BNCT) has been performed by calculating and measuring energy spectrum and the spatial distribution of neutrons in all external irradiation facilities, including six beam tubes, thermal column, and the medical room. Activation methods with multiple foils and a copper wire have been used for the mentioned measurements. The results show that (1) the small diameter and long length beam tubes cannot provide sufficient neutron flux for BNCT; (2) in order to use the medical room, the TRR core should be placed in the open pool position, in this situation the distance between the core and patient position is about 400 cm, so neutron flux cannot be sufficient for BNCT; and (3) the best facility which can be adapted for BNCT application is the thermal column, if all graphite blocks can be removed. The epithermal and fast neutron flux at the beginning of this empty column are 4.12×10(9) and 1.21×10(9) n/cm(2)/s, respectively, which can provide an appropriate neutron beam for BNCT by designing and constructing a proper Beam Shaping Assembly (BSA) structure. PMID:24742535

Kasesaz, Yaser; Khalafi, Hossein; Rahmani, Faezeh; Ezati, Arsalan; Keyvani, Mehdi; Hossnirokh, Ashkan; Shamami, Mehrdad Azizi; Monshizadeh, Mahdi

2014-08-01

430

A new imaging method using pulsed neutron sources for visualizing structural and dynamical information  

NASA Astrophysics Data System (ADS)

Neutron imaging using pulsed neutron sources coupled with a 2-dimensional position sensitive detector applicable to the time-of-flight method can give information on the crystal texture of coherently scattering materials, dynamical information of incoherently scattering materials such as hydrogen, and magnetic field information. Bragg edges appeared at cold neutron region reflect the preferred orientation, crystallite size, and lattice spacing. To deduce such information from the neutron transmission data depending on the position we have developed a data analysis code, and applied this code to data of a welded iron sample. Furthermore, as examples of more realistic materials we have investigated quenched iron rods. The quenched region was clearly demonstrated by the lattice space distribution. Furthermore, difference in the bound state of water or hydrogen in wet and dry cement pastes have been observed by analyzing the gradient of the neutron transmission cross section at the cold neutron region. The magnetic field has been also measured by using the polarized neutrons, and the strength of the field was estimated easily by analyzing the wave length dependent data.

Kiyanagi, Y.; Sato, H.; Kamiyama, T.; Shinohara, T.

2012-02-01

431

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

NASA Astrophysics Data System (ADS)

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 cm3 only. A compact size single capacitor (4 ?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 × 104 neutrons/pulse. Beyond 200 shots the yield is below the threshold (1050 neutrons/pulse) of our 3He 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.; Mishra, Prabhat; Srivastava, Rohit; Rawool, A. M.; Kaushik, T. C.; Gupta, Satish C.

2011-02-01

432

A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.  

SciTech Connect

Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.

Doyle, Barney Lee (Sandia National Laboratories, Albuquerque, NM); King, Michael; Rossi, Paolo (Sandia National Laboratories, Albuquerque, NM); McDaniel, Floyd Del (Sandia National Laboratories, Albuquerque, NM); Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak (Sandia National Laboratories, Albuquerque, NM); Raber, Thomas N.

2008-12-01

433

Irradiation damage of ferritic/martensitic steels: Fusion program data applied to a spallation neutron source  

SciTech Connect

Ferritic/martensitic steels were chosen as candidates for future fusion power plants because of their superior swelling resistance and better thermal properties than austenitic stainless steels. For the same reasons, these steels are being considered for the target structure of a spallation neutron source, where the structural materials will experience even more extreme irradiation conditions than expected in a fusion power plant first wall (i.e., high-energy neutrons that produce large amounts of displacement damage and transmutation helium). Extensive studies on the effects of neutron irradiation on the mechanical properties of ferritic/martensitic steels indicate that the major problem involves the effect of irradiation on fracture, as determined by a Charpy impact test. There are indications that helium can affect the impact behavior. Even more helium will be produced in a spallation neutron target material than in the first wall of a fusion power plant, making helium effects a prime concern for both applications. 39 refs., 10 figs.

Klueh, R.L. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1997-06-01

434

Characteristics of the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators.  

PubMed

The authors established the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators at the Japan Nuclear Cycle Development Institute (JNC), Tokai Works. The moderators are annular cylinders made of polymethyl methacrylate and steel. The neutron energy spectrum at the reference calibration point was evaluated from the calculations by MCNP-4B and the measurements by the Bonner multisphere spectrometer and the hydrogen-filled proportional counters. The calculated neutron spectra were in good agreements with the measured ones. These fields can provide the realistic neutron spectra similar to those encountered around the glove-boxes of the fabrication process of MOX (PuO2-UO2 mixed oxide) fuel. PMID:15353633

Tsujimura, N; Yoshida, T

2004-01-01

435

Establishment of a simple neutron calibration field from a moderated 252Cf source . Part I. Design and calculation of the simple neutron calibration field  

NASA Astrophysics Data System (ADS)

This paper describes the development and standardization of simple neutron reference calibration fields. These fields have been arranged for calibration of neutron detectors particularly used for radiation control and environmental measurements, having four different neutron spectra formed by a 252Cf source with or without moderators of iron, carbon or polyethylene. These calibration fields are independent of room-scattered neutrons, since they use only direct neutron components which are obtained by subtracting the results with shadow blocks from the results without those. The absolute energy spectra and dose equivalents of direct neutrons and room-scattered neutrons, and the effect of a shadow shield have been calculated by the one-dimensional ANISN-W, two-dimensional DOT-3.5 discrete ordinates codes and the three-dimensional MORSE-CG Monte Carlo code, for these four fields.

Hara, A.; Iwai, S.; Nakamura, T.

1987-02-01

436

Principles for timing at spallation neutron sources based on developments at LANSCE  

SciTech Connect

Due to AC-power-grid frequency fluctuations, the designers for accelerator-based spallation-neutron facilities have worked to optimize the conflicting demands of accelerator and neutron chopper performance. For the first time, we are able to quantitatively access the tradeoffs between these two constraints and design or upgrade a facility to optimize total system performance using powerful new simulation techniques. We have modeled timing systems that integrate chopper controllers and chopper hardware and built new systems. Thus, at LANSCE, we now operate multiple chopper systems and the accelerator as simple slaves to a single master-timing-reference generator. Based on this experience we recommend that spallation neutron sources adhere to three principles. First, timing for pulsed sources should be planned starting with extraction at a fixed phase and working backwards toward the leading edge of the beam pulse. Second, accelerator triggers and storage ring extraction commands from neutron choppers offer only marginal benefits to accelerator-based spallation sources. Third, the storage-ring RF should be phase synchronized with neutron choppers to provide extraction without the one orbit timing uncertainty.

Nelson, R. O. (Ronald O.); Merl, R. B. (Robert B.); Rose, C. R. (Chris R.)

2001-01-01

437

Gas Dynamic Trap Neutron Source (DTNS) -- applications and development path  

NASA Astrophysics Data System (ADS)

The successes in the Gas Dynamic Trap at the Budker Institute of Nuclear Physics -- stable operation to ?˜60%, Te increasing with neutral beam power to >200 eV, and classical behavior of hot ions (Ivanov and Beklemishev, this conf.) -- motivate building a DTNS. The DTNS provides ˜2 MW/m^2neutron flux, and 20 l irradiated volume (in a 2.5 cm thick annulus) to enable aggressive programs in fusion materials development, tritium-breeding blankets (which do not have to breed initially because the DTNS burns less than 200 g/yr of T), and hybrid fission blankets. The major issue is steady-state operation of a configuration that has been demonstrated during 5 ms pulses. The known issues are all engineering: cooling components impinged by beams, pumping the gas and regenerating the pumps. Possible plasma physics issues, such as drift waves, are expected to have slow growth times enabling suppression or saturation at low levels.

Molvik, A. W.; Simonen, T. C.; Ryutov, D. D.

2009-11-01

438

RESULTS OF FIRST EXPERIMENTS ON NEUTRON GENERATION IN THE VITA NEUTRON SOURCE  

E-print Network

of flux and spectrum of both gamma-ray and neutrons at 50 µm lithium thickness and 1.915 MeV proton beam as a result of threshold reaction 7 Li(p, n)7 Be while dumping the 1.915 MeV 10 mA proton beam on lithium therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact

Taskaev, Sergey Yur'evich

439

Identification of shielded neutron sources with the liquid scintillator BC-501A using a digital pulse shape discrimination method  

NASA Astrophysics Data System (ADS)

Fast and unambiguous identification of shielded neutron sources is of paramount importance in nuclear nonproliferation and international safeguards applications. Usually, the identification of neutron spectra relies on unfolding procedures that are unstable and time consuming. In this paper, we present a new application of an existing technique, which can be used for neutron source identification by direct analysis of the pulse height spectrum, i.e., without resorting to energy spectrum unfolding. This technique is based on the acquisition of neutron and ?-ray pulses by using a liquid scintillation detector and a fast waveform digitizer. An optimized digital pulse shape discrimination method based on standard charge integration is used to discriminate neutrons from ?-rays. The neutron pulses are then analyzed to generate a pulse height distribution. The accuracy of the neutron source identification technique was tested on three neutron sources: Cf-252, Am-Be, and Am-Li. Several source-shielding configurations were tested to assess the influence of potential shielding of the source and the sensitivity of the technique. For this investigation, lead and polyethylene shielding blocks were used. The measured pulse height distributions were compared with the distributions simulated with the MCNP-PoliMi code, and very good agreement was obtained. The results show that for both shielded and unshielded configurations the identification of Cf-252, Am-Be, and Am-Li shielded sources is easily achievable by direct analysis of the measured pulse height distributions, without the need of subsequent neutron energy spectrum unfolding.

Flaska, M.; Pozzi, S. A.

2007-07-01

440

Research and Development of Landmine Detection System by a Compact Fusion Neutron Source  

SciTech Connect

Current results are described on the research and development of an advanced anti-personnel landmine detection system by using a compact discharge-type fusion neutron source called IECF (Inertial-Electrostatic Confinement Fusion). Landmines are to be identified through backscattering of neutrons, and specific-energy capture {gamma}-rays by hydrogen and nitrogen atoms in the landmine explosives.For this purpose, improvements in the IECF were made by various methods to achieve a drastic enhancement of neutron yields of more than 10{sup 8} n/s in pulsed operation. This required R and D on the power source, as well as analysis of envisaged detection systems with multi-sensors. The results suggest promising and practical features for humanitarian landmine detection, particularly, in Afghanistan.

Yoshikawa, Kiyoshi [Kyoto University (Japan); Masuda, Kai [Kyoto University (Japan); Toku, Hisayuki [Kyoto University (Japan); Nagasaki, Kazunobu [Kyoto University (Japan); Mizutani, Toshiyuki [Kyoto University (Japan); Takamatsu, Teruhisa [Kyoto University (Japan); Imoto, Masaki [Kyoto University (Japan); Yamamoto, Yasushi [Kyoto University (Japan); Ohnishi, Masami [Kansai University (Japan); Osawa, Hodaka [Kansai University (Japan); Hotta, Eiki [Tokyo Institute of Technology (Japan); Kohno, Toshiyuki [Tokyo Institute of Technology (Japan); Okino, Akitoshi [Tokyo Institute of Technology (Japan); Watanabe, Masato [Tokyo Institute of Technology (Japan); Yamauchi, Kunihito [Tokyo Institute of Technology (Japan); Yuura, Morimasa [Pulse Electronic Engineering Co., Ltd. (Japan); Shiroya, Seiji [Kyoto University (Japan); Misawa, Tsuyoshi [Kyoto University (Japan); Mori, Takamasa [Japan Atomic Energy Agency (Japan)

2005-05-15

441

Experiment Automation with a Robot Arm using the Liquids Reflectometer Instrument at the Spallation Neutron Source  

SciTech Connect

The Liquids Reflectometer instrument installed at the Spallation Neutron Source (SNS) enables observations of chemical kinetics, solid-state reactions and phase-transitions of thin film materials at both solid and liquid surfaces. Effective measurement of these behaviors requires each sample to be calibrated dynamically using the neutron beam and the data acquisition system in a feedback loop. Since the SNS is an intense neutron source, the time needed to perform the measurement can be the same as the alignment process, leading to a labor-intensive operation that is exhausting to users. An update to the instrument control system, completed in March 2013, implemented the key features of automated sample alignment and robot-driven sample management, allowing for unattended operation over extended periods, lasting as long as 20 hours. We present a case study of the effort, detailing the mechanical, electrical and software modifications that were made as well as the lessons learned during the integration, verification and testing process.

Zolnierczuk, Piotr A [ORNL; Vacaliuc, Bogdan [ORNL; Sundaram, Madhan [ORNL; Parizzi, Andre A [ORNL; Halbert, Candice E [ORNL; Hoffmann, Michael C [ORNL; Greene, Gayle C [ORNL; Browning, Jim [ORNL; Ankner, John Francis [ORNL

2013-01-01

442

Can Handheld Plastic Detectors Do Both Gamma and Neutron Isotopic Identification with Directional Source Location?  

SciTech Connect

This paper demonstrates, through MCNPX simulations, that a compact hexagonal array of detectors can be utilized to do both gamma isotopic identification (ID) along with neutron identification while simultaneously finding the direction of the source relative to the detector array. The detector array itself is composed of seven borated polyvinyl toluene (PVT) hexagonal light pipes approximately 4 inches long and with a 1.25 inch face-to-face thickness assembled in a tight configuration. The gamma ID capability is realized through judicious windowing algorithms as is the neutron spectral unfolding. By having multiple detectors in different relative positions, directional determination of the source can be realized. By further adding multiplicity counters to the neutron counts, fission events can be measured.

Robert Hayes

2008-04-18

443

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device  

NASA Astrophysics Data System (ADS)

The development of a novel and portable tabletop pulsed neutron source is presented. It is a battery powered neutron tube based on a miniature plasma focus (PF) device having all metal-sealed components. The tube, fuelled with deuterium gas, generates neutrons because of D-D fusion reactions. The inner diameter and the length of the tube are 3.4 cm and 8 cm, respectively. A single capacitor (200 J, 4.0 µF, 10 nH) of compact size (17 cm × 15 cm × 13 cm, 6.5 kg) is used as the energy driver. A power supply system charges the capacitor to 10 kV in 10 s and also provides a 30 kV trigger pulse to the spark gap. An input of 24 V dc (7.5 A) to the power supply system is provided by two rechargeable batteries (each 12 V, 7.5 A, 20 h). The device has produced neutrons for 150 shots within a period of 120 days in a very reliable manner without purging the deuterium gas between the shots. For the first 50 shots, the average yield is (1.6 ± 0.3) × 106 neutrons/shot in 4? sr with a pulse width of 23.4 ± 3.3 ns. The estimated neutron energy is 2.47 ± 0.22 MeV. The neutron production reduces slowly and reaches the detection threshold value of 3 × 105 neutrons/shot towards the last shots. The device produces neutrons in a similar manner on evacuation and refilling. The height of the mounted PF tube with the capacitor and the spark gap is 35 cm. The complete setup comprising the capacitor with spark gap, the PF tube, the power supply system with two batteries and the control panel weighs only 23 kg.

Rout, R. K.; Mishra, P.; Rawool, A. M.; Kulkarni, L. V.; Gupta, Satish C.

2008-10-01

444