Note: This page contains sample records for the topic radio-isotopic neutron sources from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Neutron imaging of radioactive sources  

NASA Astrophysics Data System (ADS)

Isotopic neutron sources have been available for more than six decades. At the Atomic Institute in Vienna, operating a 250 kW TRIGA reactor, different neutron sources are in use for instrument calibration and fast neutron applications but we have only little information about their construction and densities. The knowledge of source design is essential for a complete MCNP5 modeling of the experiments. Neutron radiography (NR) and neutron tomography (NT) are the best choices for the non-destructive inspection of the source geometry and homogeneity. From the transmission analysis we gain information about the shielding components and the densities of the radio-isotopes in the cores. Three neutron sources, based on (alpha, n) reaction, have been investigated, two 239PuBe sources and one 241AmBe source. In the NR images the internal structure was clearly revealed using high-resolving scintillation and imaging plate detectors. In one source tablet a crack was detected which causes asymmetric neutron emission. The tomography inspection of strong absorbing materials is more challenging due to the low beam intensity of 1.3x105 n/cm2s at our NT instrument, and due to the beam hardening effect which requires an extension of reconstruction software. The tomographic inspection of a PuBe neutron source and appropriate measures for background and beam hardening correction are presented.

Hameed, F.; Karimzadeh, S.; Zawisky, M.

2008-08-01

2

In-vessel calibration of the JET neutron monitors using a sup 252 Cf neutron source: Difficulties experienced  

Microsoft Academic Search

The most direct method of obtaining an absolute calibration of the set of fission chambers used at JET for the measurement of the time-resolved neutron yield is by means of a standardized ²⁵²Cf radio-isotope neutron source which is moved around the vacuum vessel to map out the volume occupied by the plasma. The accuracy of this procedure can approach 10%.

O. N. Jarvis; G. Sadler; P. van Belle; T. Elevant

1990-01-01

3

In-vessel calibration of the JET neutron monitors using a 252Cf neutron source: Difficulties experienced  

Microsoft Academic Search

The most direct method of obtaining an absolute calibration of the set of fission chambers used at JET for the measurement of the time-resolved neutron yield is by means of a standardized 252Cf radio-isotope neutron source which is moved around the vacuum vessel to map out the volume occupied by the plasma. The accuracy of this procedure can approach 10%.

O. N. Jarvis; G. Sadler; P. van Belle; T. Elevant

1990-01-01

4

Focused Pulsed Neutron Source.  

National Technical Information Service (NTIS)

A non-reactor neutron source is disclosed that allows for a pulse intense current of ions to generate neutrons that are epithermal neutrons and provide low-energy neutron energy particularly suited for Boron Neutron Capture Therapy (BNCT) treatment. The p...

M. Friedman A. Drobot N. C. Wyeth

1995-01-01

5

Intense fusion neutron sources  

NASA Astrophysics Data System (ADS)

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

2010-04-01

6

Intense fusion neutron sources  

SciTech Connect

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 10{sup 15}-10{sup 21} neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 10{sup 20} neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

Kuteev, B. V. [Russian Research Centre Kurchatov Institute (Russian Federation); Goncharov, P. R.; Sergeev, V. Yu. [St. Petersburg State Polytechnic University (Russian Federation); Khripunov, V. I. [Russian Research Centre Kurchatov Institute (Russian Federation)

2010-04-15

7

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

8

In-vessel calibration of the JET neutron monitors using a sup 252 Cf neutron source: Difficulties experienced  

SciTech Connect

The most direct method of obtaining an absolute calibration of the set of fission chambers used at JET for the measurement of the time-resolved neutron yield is by means of a standardized {sup 252}Cf radio-isotope neutron source which is moved around the vacuum vessel to map out the volume occupied by the plasma. The accuracy of this procedure can approach 10%. However, its applicability depends on the geometry of the tokamak and the location of the fission chambers. At JET, most of the neutrons reach the detectors by passing through the main diagnostic ports. Now that these ports have become surrounded by massive items of hardware, it is found that this equipment moderates and absorbs the {sup 252}Cf neutrons more strongly than 2.5 MeV neutrons. This paper examines the magnitude of the errors on the absolute calibration of the fission chambers introduced by this effect.

Jarvis, O.N.; Sadler, G.; van Belle, P.; Elevant, T. (JET Joint Undertaking, Abingdon, Oxfordshire OX14 3EA (Great Britain))

1990-10-01

9

Intense fusion neutron sources  

Microsoft Academic Search

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons\\/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion

B. V. Kuteev; P. R. Goncharov; V. Yu. Sergeev; V. I. Khripunov

2010-01-01

10

Intense fusion neutron sources  

Microsoft Academic Search

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects\\u000a of creating fission and fusion neutron sources with intensities of 10151021 neutrons\\/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes\\u000a and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of\\u000a fusion

B. V. Kuteev; P. R. Goncharov; V. Yu. Sergeev; V. I. Khripunov

2010-01-01

11

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

12

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

13

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

14

High Yield Neutron Source.  

National Technical Information Service (NTIS)

A high yield neutron source comprising a plasma focus device in combination with a structured target is described. The plasma focus device generates a plasma sheath which focuses on a structured target in a predetermined focal region. The structured targe...

H. L. Sahlin J. H. Brownell B. L. Freeman

1978-01-01

15

Neutron source progress report  

Microsoft Academic Search

This document is a de-classified June 1948 progress report on neutron source development at Monsanto Chemical`s Mound facility. Specific sources reviewed are: (1) Postum-beryllium, (2) Postum-Boron and Postum-Fluoborate, and (3) Postum-Lithium and Postum-Sodium. Preparation of each source is discussed, and some of their physical properties are given.

L. Bentz; J. Birden; R. Hertz

1948-01-01

16

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.

17

Tokamak as a Neutron Source.  

National Technical Information Service (NTIS)

This paper describes the tokamak in its role as a neutron source, with emphasis on experimental results for D-D neutron production. The sections summarize tokamak operation, sources of fusion and non-fusion neutrons, principal neutron detection methods an...

H. W. Hendel D. L. Jassby

1989-01-01

18

Optimization of neutron source  

SciTech Connect

I consider here the optimization of the two component neutron source, allowing beam species and energy to vary. A simple model is developed, based on the earlier publications, that permits the optimum to be obtained simply. The two component plasma, with one species of hot ion (D{sup +} or T{sup +}) and the complementary species of cold ion, is easy to analyze in the case of a spatially uniform cold plasma, as to good approximation the total number of hot ions is important but not their spatial distribution. Consequently, the optimization can ignore spatial effects. The problem of a plasma with both types of hot ions and cold ions is rather more difficult, as the neutron production by hot-hot interactions is sensitive to their spatial distributions. Consequently, consideration of this problem will be delayed to a future memorandum. The basic model is that used in the published articles on the two-component, beam-plasma mirror source. I integrate the Fokker-Planck equation analytically, obtaining good agreement with previous numerical results. This simplifies the optimization, by providing a functional form for the neutron production. The primary result is expressed in terms of the power efficiency: watts of neutrons/watts of primary power. The latter includes the positive ion neutralization efficiency. At 150 keV, the present model obtains an efficiency of 0.66%, compared with 0.53% of the earlier calculation.

Hooper, E.B.

1993-11-09

19

Spherical tokamak volume neutron source  

Microsoft Academic Search

Details are discussed of a volume neutron source for testing assemblies such as blanket sections in a 14 MeV neutron environment. This neutron source is based on the spherical tokamak. The experimentally confirmed ability of the spherical tokamak to reach very high plasma pressures makes it ideally suited as the basis for a very compact neutron source (R?0.7 m, Ip?712

T. C. Hender; G. M. Voss; N. P. Taylor

1999-01-01

20

Accelerator-based Neutron Sources  

Microsoft Academic Search

Since the earliest experiments defining the properties of the neutron, accelerators have played an important role in providing neutrons for research and applications. For many years, neutrons produced at accelerator facilities have complemented capabilities available from reactor-based sources. Now, with the declining availability of reactor facilities, upgrades of existing accelerator facilities and proposed new, more powerful accelerator-based sources will be

James B. Ball

1997-01-01

21

Spallation Neutron Source Materials Studies  

Microsoft Academic Search

Operation of accelerator facilities such as Los Alamos Neutron Science Center (LANSCE), ISIS at Rutherford Appleton Laboratory, the Swiss Institute Neutron Source (SINQ) at Paul Scherrer Institute, and others has provided valuable information on materials performance in high energy particle beams and high energy neutron environments. The Accelerator Production of Tritium (APT) project is sponsoring an extensive series of tests

W. F. Sommer

1998-01-01

22

The tokamak as a neutron source  

Microsoft Academic Search

This paper describes the tokamak in its role as a neutron source, with emphasis on experimental results for D-D neutron production. The sections summarize tokamak operation, sources of fusion and non-fusion neutrons, principal neutron detection methods and their calibration, neutron energy spectra and fluxes outside the tokamak plasma chamber, history of neutron production in tokamaks, neutron emission and fusion power

H. W. Hendel; D. L. Jassby

1989-01-01

23

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

24

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

25

Spallation source neutron target systems  

SciTech Connect

This is the final report for a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project sought to design a next-generation spallation source neutron target system for the Manuel Lujan, Jr., Neutron Scattering Center (LANSCE) at Los Alamos. It has been recognized for some time that new advanced neutron sources are needed in the US if the country is to maintain a competitive position in several important scientific and technological areas. A recent DOE panel concluded that the proposed Advanced Neutron Source (a nuclear reactor at Oak Ridge National Laboratory) and a high-power pulsed spallation source are both needed in the near future. One of the most technically challenging designs for a spallation source is the target station itself and, more specifically, the target-moderator-reflector arrangement. Los Alamos has demonstrated capabilities in designing, building, and operating high-power spallation-neutron-source target stations. Most of the new design ideas proposed worldwide for target system design for the next generation pulsed spallation source have either been conceived and implemented at LANSCE or proposed by LANSCE target system designers. These concepts include split targets, flux-trap moderators, back scattering and composite moderators, and composite reflectors.

Russell, G.; Brown, R.; Collier, M.; Donahue, J. [and others

1996-07-01

26

The tokamak as a neutron source  

SciTech Connect

This paper describes the tokamak in its role as a neutron source, with emphasis on experimental results for D-D neutron production. The sections summarize tokamak operation, sources of fusion and non-fusion neutrons, principal neutron detection methods and their calibration, neutron energy spectra and fluxes outside the tokamak plasma chamber, history of neutron production in tokamaks, neutron emission and fusion power gain from JET and TFTR (the largest present-day tokamaks), and D-T neutron production from burnup of D-D tritons. This paper also discusses the prospects for future tokamak neutron production and potential applications of tokamak neutron sources. 100 refs., 16 figs., 4 tabs.

Hendel, H.W.; Jassby, D.L.

1989-11-01

27

Moderated Neutron Sources for Calibrating Neutron Dosimeters for Reactor Environments.  

National Technical Information Service (NTIS)

Neutron dosimeters used around reactor environments are often calibrated with ( alpha , n) sources or exp 252 Cf sources. Since these sources emit neutrons which are more energetic than those outside power reactors, the readings of dosimeters calibrated i...

H. Ing

1980-01-01

28

Neutron Fluence Map for the Rotating Target Neutron Source.  

National Technical Information Service (NTIS)

Nine nickel, niobium, and gold dosimetry foils incorporated in a neutron irradiation experiment at the Rotating Target Neutron Source (RTNS) facility were analyzed to construct a three-dimensional neutron fluence map. The purpose of the map was to determi...

D. W. Kneff H. Farrar R. A. Van Konynenburg R. R. Heinrich

1976-01-01

29

Advanced Neutron Source enrichment study  

Microsoft Academic Search

A study has been performed of the impact on performance of using low-enriched uranium (20% ²³⁵U) or medium-enriched uranium (35% ²³⁵U) as an alternative fuel for the Advanced Neutron Source, which was initially designed to use uranium enriched to 93% ²³⁵U. Higher fuel densities and larger volume cores were evaluated at the lower enrichments in terms of impact on neutron

R. A. Bari; H. Ludewig

1996-01-01

30

Fission-fusion neutron source  

NASA Astrophysics Data System (ADS)

In order to meet the requirements of fusion power reactors and nuclear waste treatment, a concept of fission-fusion neutron source is proposed, which consists of a LiD assembly located in the heavy water region of the China Advanced Research Reactor. This assembly of LiD fuel rods will be irradiated with slow neutrons and will produce fusion neutrons in the central hole via the reaction 6Li(n, ?). More precisely, tritium ions with a high energy of 2.739 MeV will be produced in LiD by the impinging slow neutrons. The tritium ions will in turn bombard the deuterium ions present in the LiD assembly, which will induce fusion reaction and then the production of 14 MeV neutrons. The fusion reaction rate will increase with the accumulation of tritium in LiD by the reaction between tritium and deuteron recoils produced by the 14 MeV neutrons. When the concentration of tritium reaches 0.5 10 22 and the fraction of fusion reactions between tritium and deuteron recoils approaches 1, the 14 MeV neutron flux is doubled and redoubled, an so forth, approaching saturation in which the tritium produced at a time t is exhausted by the fusion reactions to keep constant the tritium concentration in LiD.

Yu, Jinnan; Yu, Gang

2009-04-01

31

New neutron physics using spallation sources  

SciTech Connect

The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. The energy range of neutron research which is being explored with these sources extends from thermal energies to almost 800 MeV. The emphasis here is on prospective experiments below 100 keV neutron energy using the intense neutron bursts produced by the Proton Storage Ring (PSR) at Los Alamos. 30 refs., 10 figs.

Bowman, C.D.

1988-01-01

32

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

33

Neutron-emission measurements at a white neutron source  

SciTech Connect

Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

Haight, Robert C [Los Alamos National Laboratory

2010-01-01

34

Advanced Neutron Source enrichment study  

Microsoft Academic Search

A study has been performed of the impact on performance of using low enriched uranium (20% ²³⁵U) or medium enriched uranium (35% ²³⁵U) as an alternative fuel for the Advanced Neutron Source, which is currently designed to use uranium enriched to 93% ²³⁵U. Higher fuel densities and larger volume cores were evaluated at the lower enrichments in terms of impact

R. A. Bari; H. Ludewig

1994-01-01

35

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

36

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

37

Neutron Diagnostics for Pulsed Plasma Sources  

Microsoft Academic Search

Neutron detectors have been developed and applied to a variety of pulsed plasma sources with intensities ranging from 102 to 1012 neutrons\\/pulse. For yields as small as 102 neutrons, a 6Li-glass-scintillator detector is used. A rhodium-activation counter has been developed for yields greater than 106 neutrons. These detectors are used for total yield and angular distribution measurements. Neutron energies are

Frank C. Young

1975-01-01

38

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

39

Los Alamos intense neutron source  

SciTech Connect

The intense neutron source is an inertial electrostatic confinement (IEC) fusion device currently under construction at Los Alamos National Laboratory. It is designed to produce 10{sup 11} n/s steady state and will be used for nuclear assay applications. It is being built in a hot cell and will operate with a deuterium-tritium fuel mixture. This device is a three-grid IEC ion focus device. Expected performance has been predicted by scaling from a previous IEC device. In this paper we describe the physics principles of operation of this device, the engineering design parameters, and the empirical scaling used to determine the design parameters.

Nebel, R.A.; Pickrell, M.M.; Barnes, D.C. [Los Alamos National Lab., NM (United States)] [and others

1997-12-01

40

Neutron-scattering instrumentation for the National Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

The National Spallation Neutron Source (NSNS) is a 1 MW pulsed spallation neutron source proposed for construction at Oak Ridge National Laboratory. This facility is being designed as a five-laboratory collaboration project. This poster addresses the proposed facility layout, the process for selection and construction of neutron-scattering instruments at the NSNS, and the initial planning done on the basis of a reference set of 10 instruments.

NSNS Collaboration Team

1998-04-01

41

Neutron production enhancements for the Intense Pulsed Neutron Source.  

National Technical Information Service (NTIS)

The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the United States dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the developmen...

E. Iverson

1999-01-01

42

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

43

The continuous spallation neutron source SINQ  

Microsoft Academic Search

SINQ, at the Paul Scherrer Institut (PSI) in Villigen, Switzerland, is the first continuous spallation neutron source worldwide. The continuous flow of neutrons and the vertical target arrangement is responsible for an instrument suite characteristic of that installed at reactors. The neutrons are extracted by six double beam tubes which are all tangential with respect to the target: two of

Peter Allenspach

2000-01-01

44

Method for locating and characterizing neutron sources  

SciTech Connect

Counting neutron-induced tracks in plastics as a function of the orientation relative to the arrival direction of incident neutrons makes possible a rugged method of measuring the direction, fluence, and average energy of a directional flux of fast neutrons and the distance and strength of the source.

Fleischer, R.L.; Paretzke, H.G.

1982-06-01

45

New sources and instrumentation for neutron science  

NASA Astrophysics Data System (ADS)

Neutron-scattering research has a lot to do with our everyday lives. Things like medicine, food, electronics, cars and airplanes have all been improved by neutron-scattering research. Neutron research also helps scientists improve materials used in a multitude of different products, such as high-temperature superconductors, powerful lightweight magnets, stronger, lighter plastic products etc. Neutron scattering is one of the most effective ways to obtain information on both, the structure and the dynamics of condensed matter. Most of the world's neutron sources were built decades ago, and although the uses and demand for neutrons have increased throughout the years, few new sources have been built. The new construction, accelerator-based neutron source, the spallation source will provide the most intense pulsed neutron beams in the world for scientific research and industrial development. In this paper it will be described what neutrons are and what unique properties make them useful for science, how spallation source is designed to produce neutron beams and the experimental instruments that will use those beams. Finally, it will be described how past neutron research has affected our everyday lives and what we might expect from the most exciting future applications.

Gil, Alina

2011-04-01

46

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

47

(International Collaboration on Advanced Neutron Sources)  

SciTech Connect

The International Collaboration on Advanced Neutron Sources was started about a decade ago with the purpose of sharing information throughout the global neutron community. The collaboration has been extremely successful in optimizing the use of resources, and the discussions are open and detailed, with reasons for failure shared as well as reasons for success. Although the meetings have become increasingly oriented toward pulsed neutron sources, many of the neutron instrumentation techniques, such as the development of better monochromators, fast response detectors and various data analysis methods, are highly relevant to the Advanced Neutron Source (ANS). I presented one paper on the ANS, and another on the neutron optical polarizer design work which won a 1989 R D-100 Award. I also gained some valuable design ideas, in particular for the ANS hot source, in discussions with individual researchers from Canada, Western Europe, and Japan.

Hayter, J.B.

1990-11-08

48

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

49

Dose measurements around spallation neutron sources.  

PubMed

Neutron dose measurements and calculations around spallation sources appear to be of great importance in shielding research. Two spallation sources were irradiated by high-energy proton beams delivered by the Nuclotron accelerator (JINR), Dubna. Neutrons produced by the spallation sources were measured by using solid-state nuclear track detectors. In addition, neutron dose was calculated after polyethylene and concrete, using a phenomenological model based on empirical relations applied in high-energy physics. The study provides an analytical and experimental neutron benchmark analysis using the transmission factor and a comparison between the experimental results and calculations. PMID:18957519

Fragopoulou, M; Stoulos, S; Manolopoulou, M; Krivopustov, M; Zamani, M

2008-01-01

50

Transmutation missions for fusion neutron sources  

Microsoft Academic Search

There are a number of potential neutron transmutation missions (destruction of long-lived radioisotopes in spent nuclear fuel, disposal of surplus weapons-grade plutonium, breeding of fissile nuclear fuel) that perhaps best can be performed in sub-critical nuclear reactors driven by a neutron source. The requirements on a tokamak fusion neutron source for such transmutation missions are significantly less demanding than for

W. M. Stacey

2007-01-01

51

Pulsed thermal neutron source at the fast neutron generator  

Microsoft Academic Search

A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal neutron intensity and the short decay time of

Grzegorz Tracz; Krzysztof Drozdowicz; Barbara Gaba?ska; Ewa Krynicka

2009-01-01

52

Source Calibration for Neutron Flux Measurement  

NASA Astrophysics Data System (ADS)

The NPDGamma experiment is currently running at the Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The goal of the experiment is to measure the parity-violating asymmetry between the incident neutron spin and emitted photon direction for the capture of neutrons on protons. The gamma-rays are detected in a CsI array. We need to know the neutron flux accurately to verify that we are running at counting statistics. We measure the neutron flux from the gamma signal produced by capturing all neutrons on a black boron target. The detectors were calibrated with a known gamma-ray source (Cesium-137) to high precision using a High Purity Germanium (HPGe) detector. I will present the methodology and results of this calibration, and how it affects our measurement of the statistical precision of NPDGamma.

Craycraft, Kayla

2012-10-01

53

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 1.8109 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

54

International workshop on cold neutron sources  

SciTech Connect

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--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 from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources.

Russell, G.J.; West, C.D. (comps.) (Los Alamos National Lab., NM (United States)) [comps.; Los Alamos National Lab., NM (United States)

1991-08-01

55

Neutron sources for a neutron capture therapy facility  

SciTech Connect

Recent advances in the development of boron pharmaceuticals have reopened the possibility of using epithermal neutrons to treat brain tumors containing boron-10. This paper summarizes the approaches being used to generate the neutron sources and identifies specific areas where more research and development are needed.

Lennox, A.J.

1993-04-01

56

Spallation Neutron Sources: New Capabilities for Research  

NASA Astrophysics Data System (ADS)

Neutron sources based on the release of neutrons from matter by bombardment with medium energy particles excel by several features, which are impossible or difficult to realize on reactors: they can deliver an extremely wide range of neutron energies from the GeV range all the way down to micro-eV, or even lower; neutrons can be generated with virtually any time structure from nanosecond pulses to practically continuously; and the flux levels obtainable during the pulses can exceed those of controlled fission-based sources by several orders of magnitude. Furthermore, the beams driving the sources can be simultaneously taken advantage of to generate pions and muons or to study radiation effects in materials. Last but not least the neutrinos released with a time structure following that of the neutron generation are of interest for fundamental studies. The paper will mainly deal with the aspects of neutron generation, spectral and temporal tailoring of the neutron flux and the main motivation for the current proposals of spallation neutron sources: improved research opportunities for condensed matter science. In this context different concepts of spallation neutron sources will be dealt with and their respective merits and limitations will be discussed, as well as their positioning relative to research reactors. Finally, an outlook will be given on what can be expected in terms of future development and what the limiting factors are, according to present knowledge.

Bagenal, F.; Crary, F. J.; Stewart, A. I. F.; Schneider, N. M.; Gurnett, D. A.; Kurth, W. S.; Frank, L. A.; Paterson, W. R.

1998-10-01

57

Hand-held radio-isotope detection and identification instrument  

SciTech Connect

An instrument combining an array of Cadmium-Zinc-Telluride (CZT) detectors, a NaI scintillator, and two {sup 3}He neutron detectors has been constructed. The instrument uses the CZT array to identify radioactive materials. As an example of this application, the 3 {sigma} Minimum Detectable Activity for the 375 keV peak of {sup 238}Pu is less than 1 gram at a distance of 20 cm for a 100-second counting time. The 2 x 2 NaI scintillator has a dual purpose. First, it is used to supplement the CZT array for identification of high-energy gammas, such as those from {sup 60}Co. Second, the principle use of the NaI scintillator is to help search for radioactive material and to find a suitable measurement location on a suspect package for the CZT-based isotope-identification measurement. This detector also produces energy-corrected exposure-rate data. The {sup 3}He neutron detectors provide an additional confirmation of the presence of some plutonium isotopes. The neutron sensitivity is 90 counts per second at 20 cm from a moderated {sup 252}Cf neutron source.

W. M. Quam

2000-04-30

58

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

59

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

60

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

61

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

62

Modeling a neutron-rich nuclei source  

Microsoft Academic Search

: The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron-rich nuclei\\u000a based on the neutron-induced fission can be realised using these beams. A theoretical optimization of such a facility as a\\u000a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account\\u000a the

M. Mirea; O. Bajeat; F. Clapier; F. Ibrahim; A. C. Mueller; N. Pauwels; J. Proust

2001-01-01

63

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

64

Modulating the neutron flux from a mirror neutron source  

NASA Astrophysics Data System (ADS)

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.

2012-06-01

65

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

66

The University of Texas Cold Neutron Source  

NASA Astrophysics Data System (ADS)

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, a cryogenic refrigerator, and a neutron guide. 80 ml of mesitylene moderator are maintained at about 30 K in a chamber within the reactor graphite reflector by the heat pipe and cryogenic refrigerator. The heat pipe is a 3-m long aluminum tube that contains neon as the working fluid. The cold neutrons obtained from the moderator are transported by a curved 6-m long neutron guide. This neutron guide has a radius of curvature of 300 m, a 50 15 mm cross-section, 58Ni coating, and is separated into three channels. The TCNS will provide a low-background subthermal neutron beam for neutron capture and scattering research. After the installation of the external portion of the neutron guide, a neutron focusing system and a Prompt Gamma Activation Analysis facility will be set up at the TCNS.

nl, Kenan; Ros-Martnez, Carlos; Wehring, Bernard W.

1994-12-01

67

Advanced Neutron Source: The designer's perspective.  

National Technical Information Service (NTIS)

The Advanced Neutron Source (ANS) is a research facility based on a 350 MW beam reactor, to be brought into service at the Oak Ridge National Laboratory at the end of the century. The primary objective is to provide high-flux neutron beams and guides, wit...

F. J. Peretz

1990-01-01

68

Spallation neutron source target station issues  

Microsoft Academic Search

In many areas of physics, materials and nuclear engineering, it is extremely valuable to have a very intense source of neutrons so that the structure and function of materials can be studied. One facility proposed for this purpose is the National Spallation Neutron Source (NSNS). This facility will consist of two parts: (1) a high-energy (1 GeV) and high powered

Tony A. Gabriel; John N. Barnes; Lowell A. Charlton

1996-01-01

69

High Brightness Neutron Source for Radiography  

SciTech Connect

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 possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases of yield of two orders of magnitude. The first fast neutron radiographic images were obtained using neutron cameras and a new fast neutron generator. These early images demonstrated the feasibility of using fast neutrons for imaging and penetrating thick objects of high density and imaging. Fast neutrons can be used to image low atomic number materials (e.g. plastics, explosives, lubricants and ceramics) that are shielded by high density materials (e.g. lead, tungsten and uranium). Fast neutron radiography could be used as a means to screen weapons for flaws and chemical stability. X-ray radiography can not easily do this. Fast neutron imaging is technically difficult and, consequently, a completely undeveloped market. Two of the generators were designed to have small source size and high brightness, ideal for fast-neutron imaging. With these generators we successfully used two fast neutron cameras: one developed by us, and another developed by a collaborator, Commonwealth Scientific and Industrial Research Organization, CSIRO. We have successfully used these cameras to obtain low resolution images of various objects such as pipe fittings filled with water and other mechanical objects. Higher resolution and contrast images are expected by decreasing the source size and increasing generator yield.

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

2008-12-08

70

Pulsed thermal neutron source at the fast neutron generator.  

PubMed

A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14 MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal neutron intensity and the short decay time of the thermal neutron flux. The source has been built and the test experiments have been performed. To ensure the response is not due to the choice of target for the experiments, calculations have been done to demonstrate the response is valid regardless of the thermalization properties of the target. PMID:19223189

Tracz, Grzegorz; Drozdowicz, Krzysztof; Gaba?ska, Barbara; Krynicka, Ewa

2009-06-01

71

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

72

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

73

Small commercial neutron sources and applications  

SciTech Connect

In the past, the primary application for small, accelerator-based neutron sources has been laboratory neutron activation analysis (NAA). Continued development of conventional NAA has been inhibited by the lack of availability of high-yield, low-cost neutron generators. New applications of small accelerator-based neutron sources have shifted to a broad range of applications involving in situ analysis. These applications were pioneered in the oil field service industry but are now spreading to diverse fields ranging from detection of buried land mines to in vivo analysis of body composition. This paper reviews some of these applications and discusses the characteristics of the small neutron generators that are suitable for use in in situ analysis.

Reichardt, J.; Frey, M. [MF Physics Corp., Colorado Springs, CO (United States)

1997-12-01

74

Spallation neutron source target station issues  

SciTech Connect

In many areas of physics, materials and nuclear engineering, it is extremely valuable to have a very intense source of neutrons so that the structure and function of materials can be studied. One facility proposed for this purpose is the National Spallation Neutron Source (NSNS). This facility will consist of two parts: (1) a high-energy ({approximately}1 GeV) and high powered ({approximately} 1 MW) proton accelerator, and (2) a target station which converts the protons to low-energy ({le} 2 eV) neutrons and delivers them to the neutron scattering instruments. This paper deals with the second part, i.e., the design and development of the NSNS target station and the scientifically challenging issues. Many scientific and technical disciplines are required to produce a successful target station. These include engineering, remote handling, neutronics, materials, thermal hydraulics, and instrumentation. Some of these areas will be discussed.

Gabriel, T.A.; Barnes, J.N.; Charlton, L.A. [and others

1996-10-01

75

Fusion for neutrons: A realisable fusion neutron source  

Microsoft Academic Search

For 60 years fusion research has been focused on Fusion for Energy (F4E) as the ultimate carbon-free solution to the world's energy problems. It is proving a worthy but difficult task. However it is relatively easy to produce high-energy fusion neutrons. The many potential applications of a 14MeV neutron source are outlined, and a range of existing designs for such

A Sykes; M. P. Gryaznevich; G Voss; D. Kingham; B. Kuteev

2011-01-01

76

Fusion for Neutrons: A Realizable Fusion Neutron Source  

Microsoft Academic Search

For 60 years, fusion research has been focused on fusion for energy as the ultimate carbon-free solution to the world's energy problems. It is proving a worthy but difficult task. However, it is relatively easy to produce high-energy fusion neutrons. The many potential applications of a 14-MeV neutron source are outlined, and a range of existing designs for such a

A. Sykes; M. P. Gryaznevich; G. Voss; D. Kingham; B. Kuteev

2012-01-01

77

Neutronics analysis of a spherical torus based volume neutron source  

SciTech Connect

A spherical torus based volumetric neutron source (ST-VNS) concept has been developed as a possible intermediate step to develop the necessary technology for reactor components of future fusion power plants. Such a VNS would complement ITER in testing, developing and qualifying nuclear technology components. Two recently designconcepts for a spherical torus based VNS have been investigated. The initial design operated at 39 MW fusion power with a 0.8 m major radius yielding an average neutron wall loading of 1 MW/ m '. A higher fusion power (326 MW) ST-VNS design was conceived by increasing the major radius to 1.07 m yielding an average neutron wall loading of 5 MW/ m '. In this paper, we report the results of the neutronics analyses of this high power design along with several design modifications including the effects of using ITER materials in the key components. The results of a feasibility study of using the ST-VNS with suitably designed blankets to provide an intense neutron source for neutron science applications is also reported.

Cerbone, R. J. [TSI Research Inc.; Peng, Yueng Kay Martin [ORNL

1998-01-01

78

Radioactive source recovery program responses to neutron source emergencies  

SciTech Connect

Recovery of neutron sources containing Pu{sup 239} and Be is currently taking place at Los Alamos National Laboratory. The program was initiated in 1979 by the Department of Energy (DOE) to dismantle and recover sources owned primarily by universities and the Department of Defense. Since the inception of this program, Los Alamos has dismantled and recovered more than 1000 sources. The dismantlement and recovery process involves the removal of source cladding and the chemical separation of the source materials to eliminate neutron emissions. While this program continues for the disposal of {sup 239}Pu/Be sources, there is currently no avenue for the disposition of any sources other than those containing Pu{sup 239}. Increasingly, there have been demands from agencies both inside and outside the Federal Government and from the public to dispose of unwanted sources containing {sup 238}Pu/Be and {sup 241}Am/Be. DOE is attempting to establish a formal program to recover these sources and is working closely with the Nuclear Regulatory Commission (NRC) on a proposed Memorandum of Understanding to formalize an Acceptance Program. In the absence of a formal program to handle {sup 238}Pu/Be and {sup 241}Am/Be neutron sources, Los Alamos has responded to several emergency requests to receive and recover sources that have been determined to be a threat to public health and safety. This presentation will: (1) review the established {sup 239}Pu neutron source recovery program at Los Alamos, (2) detail plans for a more extensive neutron source disposal program, and (3) focus on recent emergency responses.

Dinehart, S.M.; Hatler, V.A.; Gray, D.W.; Guillen, A.D. [and others

1997-04-01

79

Studies of D-Li neutron source: An overview  

Microsoft Academic Search

The construction of a neutron source facility able to reproduce the radiation environment predicted for a fusion reactor can be considered a very important milestone for the fusion program. Such a neutron source should allow materials testing over a wide range of neutron flux and neutron fluence. To date, none of the existing facilities reproduce the neutron flux with the

I. Gomes; D. L. Smith

1994-01-01

80

Z-pinch plasma neutron sources  

NASA Astrophysics Data System (ADS)

A deuterium gas-puff load imploded by a multi-MA current driver from a large initial diameter could be a powerful source of fusion neutrons, a plasma neutron source (PNS). Unlike the beam-target neutrons produced in Z-pinch plasmas in the 1950s and deuterium-fiber experiments in the 1980s, the neutrons generated in deuterium gas-puffs with current levels achieved in recent experiments on the Z facility at Sandia National Laboratories could contain a substantial fraction of thermonuclear origin. For recent deuterium gas-puff shots on Z, our analytic estimates and one- and two-dimensional simulations predict thermal neutron yields ~31013, in fair agreement with the yields recently measured on Z [C. A. Coverdale et al., Phys. Plasmas (to be published)]. It is demonstrated that the hypothesis of a beam-target origin of the observed fusion neutrons implies a very high Z-pinch-driver-to-fast-ions energy transfer efficiency, 5 to 10%, which would make a multi-MA deuterium Z-pinch the most efficient light-ion accelerator. No matter what mechanism is eventually determined to be responsible for generating fusion neutrons in deuterium gas-puff shots on Z, the deuterium neutron yield is shown to scale as Yn~Im4, where Im is the peak current of the pinch. Theoretical estimates and numerical modeling of deuterium gas-puff implosions demonstrate that the yields of thermonuclear fusion neutrons that can be produced on ZR and the next-generation machines are sufficiently high to make PNS the most powerful, cost- and energy-efficient laboratory sources of 2.5-14 MeV fusion neutrons, just like plasma radiation sources are the most powerful sources of soft and keV x rays. In particular, the predicted deuterium-tritium thermal neutron-producing capability of PNS driven by the next-generation ZR and ZX accelerators is ~51016 and ~1018, respectively.

Velikovich, A. L.; Clark, R. W.; Davis, J.; Chong, Y. K.; Deeney, C.; Coverdale, C. A.; Ruiz, C. L.; Cooper, G. W.; Nelson, A. J.; Franklin, J.; Rudakov, L. I.

2007-02-01

81

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

82

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

83

Neutron source strength monitors for ITER  

SciTech Connect

There are several goals for the neutron source strength monitor system for the International Thermonuclear Experimental Reactor (ITER). Desired is a stable, reliable, time-dependent neutron detection system which exhibits a wide dynamic range and broad energy response to incident neutrons while being insensitive to gamma rays and having low noise characteristics in a harsh reactor environment. This system should be able to absolutely calibrated in-situ using various neutron sources. An array of proportional counters of varying sensitivities is proposed along with the most promising possible locations. One proposed location is in the pre-shields of the neutron camera collimators which would allow an integrated design of neutron systems with good detector access. As part of an ongoing conceptual design for this system, the detector-specific issues of dynamic range, performance monitoring, and sensitivity will be presented. The location options of the array will be discussed and most importantly, the calibration issues associated with a heavily shielded vessel will be presented.

Barnes, C.W. [Sandia National Labs., Albuquerque, NM (United States); Roquemore, A.L. [Princeton Univ., NJ (United States). Plasma Physics Lab.

1996-05-07

84

The Los Alamos Intense Neutron Source  

SciTech Connect

The Intense Neutron Source (INS) is an Inertial Electrostatic Confinement (IEC) fusion device presently under construction at Los Alamos National Laboratory. It is designed to produce 10{sup 11} neutrons per second steady-state using D-T fuel. Phase 1 operation of this device will be as a standard three grid IEC ion focus device. Expected performance has been predicted by scaling from a previous IEC device. Phase 2 operation of this device will utilize a new operating scheme, the Periodically Oscillating Plasma Sphere (POPS). This scheme is related to both the Spherical Reflect Diode and the Oscillating Penning Trap. With this type of operation the authors hope to improve plasma neutron production to about 10{sup 13} neutrons/second.

Nebel, R.A.; Barnes, D.C.; Bollman, R.; Eden, G.; Morrison, L.; Pickrell, M.M.; Reass, W.

1997-10-01

85

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...

86

NEUTRON SOURCES FOR USE IN REACTOR STARTUP  

Microsoft Academic Search

The particular properties of the Westinghouse Testing Reactor are used ; in the design of the neutron sources to be used both in its startup and in the ; critical experiments. Specifically the WTR is a high flux irradiation facility ; using highly enriched U²³⁵ as fuel and light water as moderator and coolant. ; The amount of reactivity control

de Saint Maurice

1956-01-01

87

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

88

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 is disclosed. The target contains occluded deuterium, tritium, or a mixture thereof. 4 figs.

Brainard, J.P.; McCollister, D.R.

1998-04-28

89

Isotope production in the advanced neutron source  

Microsoft Academic Search

The advanced neutron source (ANS) is a state-of-the-art research reactor currently being designed at Oak Ridge National Laboratory. It is scheduled to go into operation at the turn of the century. The ANS is a multifunctional research reactor having a number of missions. One of the major missions, and the subject of this paper, is to provide isotope production facilities

C. W. Alexander; J. P. Renier; T. J. McManamy; S. Mirzadeh

1993-01-01

90

Cold moderators for pulsed neutron sources  

SciTech Connect

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

Carpenter, J.M.

1990-01-01

91

Status Report on the Spallation Neutron Source  

SciTech Connect

The purpose of the Spallation Neutron Source Project (SNS) is to generate low-energy neutrons (ambient [{approximately}200 meV] and cold [{approximately}50 meV]) which can be used by up to 18 neutron beam lines to study the structure and functionality of materials. The neutrons are generated by the spallation process initiated by the interactions of 1-GeV protons with a Hg target. These neutrons are reflected by a Pb reflector and are moderated by 2 water (ambient) and 2 super critical hydrogen (cryogenic) moderators. The pulse structure for the 1 MW proton beam is 60 Hertz and < 0.7 {micro}s/pulse. The facility must be upgradable to higher power levels (2- and 4- MW) with minimal operational interruptions. Although not included in the current funding or baseline, a second target station and associated support structure which will be designed to utilize cold neutrons is also considered to be an upgrade that must be incorporated with minimal impact on operations.

Gabriel, T.A.

1998-10-12

92

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

93

Neutron source, neutron density and the origin of barium stars  

Microsoft Academic Search

The authors present new high resolution spectra of the MgH profiles in nine barium stars, and determine, by spectral synthesis techniques, the magnesium isotopic ratios in each star. When compared with recent AGB nucleosynthesis calculations, they can emphatically rule out the operation of the 22Ne(alpha, n)25Mg reaction as the neutron source responsible for the s-process enhancements observed in these barium

Robert A. Malaney; David L. Lambert

1988-01-01

94

Characterization of the source neutrons produced by the Frascati Neutron Generator  

Microsoft Academic Search

Integral experiments with a neutron source based on the T(d,n)? reaction require a good knowledge of the source neutron distribution. The source neutrons are energy-angle distributed with an energy spread of a few mega-electronvolts and anisotropy emission of a few percent.The characterization of the 14-MeV neutron source of the Frascati Neutron Generator (FNG) has been carried out using an absolutely

M Pillon; M Angelone; M Martone; V Rado

1995-01-01

95

Applied Nuclear Physics at Spallation Neutron Sources  

NASA Astrophysics Data System (ADS)

Research opportunities offered by spallation neutron sources for applied nuclear physics are reviewed, in particular having in mind the SNS machine under construction at Oak Ridge. Discussion is focused on nuclear data needs for 4 groups of applications. These include nuclear power (energy production, transmutation), defense (criticality safety, radiochemical diagnostics), and other applications (material analysis, medical, standards and resonance parameters), as well as needs for nuclear reaction model calculations (level densities, photon and neutron strength functions). It is concluded that the new SNS machine represents an important tool to meet future nuclear data needs in the U.S.

Oblozinsky, Pavel

2002-12-01

96

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

97

Compact, inexpensive, epithermal neutron source for BNCT  

SciTech Connect

A new rf-focused linac structure, designed specifically to increase the acceleration efficiency and reduce the cost of linac structures in the few-MeV range, may win the role as the optimum accelerator-based epithermal neutron source for the BNCT application. This new linac structure resembles a drift tube linac (DTL) with radio frequency quadrupole (RFQ) focusing incorporated into each 'drift tube,' hence the name R lowbar f F lowbar ocused D lowbar TL, or RFD. It promises superior acceleration properties, focusing properties, and CW capabilities. We have a proposal under consideration for the development of an epithermal neutron source, based on the 2.5-MeV RFD linac system with an average current of 10 mA, having the following components: an ion source, a short low-energy transport system, a short RFQ linac section, an RFD linac section, an rf power system, a high-energy beam transport system, a proton beam target, and a neutron beam moderator system. We propose to develop a solid lithium target for this application in the form of a thin lithium layer on the inner surface of a truncated aluminum cone, cooled by the heavy water moderator, where the proton beam is expanded to a diameter of 3 cm and scanned along a circular path, striking the lithium layer at the cone's half-angle of 30 degrees. We propose to develop a moderator assembly designed to transmit a large fraction of the source neutrons from the target to the patient treatment port, while shifting the neutron energies to an appropriate epithermal energy spectrum and minimizing the gamma-ray dose. The status of this proposal and these plans are presented.

Swenson, D. A. [Linac Systems, 2167 N. Highway 77, Waxahachie, Texas 75165 (United States)

1999-06-10

98

Neutron beam characterization at the Intense Pulsed Neutron Source.  

SciTech Connect

The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source dedicated to materials research. Its three cryogenic methane moderators provide twelve neutron beams to fourteen neutron scattering instruments and test facilities. The moderators at IPNS are of cryogenic methane (CH{sub 4}); one of liquid methane at 100 K, and two of solid methane at 30 K. These moderators produce intense beams of both cold and thermal neutrons. The moderators are each of a different physical configuration in order to tailor their performance for the instruments and facilities that operate on the neutron beams. As part of the ongoing operation of IPNS, as well as new enhancements to the target, moderator, and reflector systems, we have performed experiments characterizing the energy and time distribution of neutrons in the various beams. These measurements provide absolutely normalized energy spectra using foil activation techniques joined with time-of-flight measurements, and energy-dependent time distributions using a time-focused crystal analyzer. The IPNS accelerator system delivers 14 {micro}A of 450 MeV protons, in 100 ns pulses at 30 Hz, to a target composed of water-cooled depleted uranium disks. The solid methane ''H'' moderator is 100 by 100 by 45 mm in size, centerline poisoned with 0.25 mg/mm{sup 2} gadolinium, and decoupled from the graphite reflector with 0.5 mm of cadmium. The liquid methane ''F'' moderator, which is viewed from both faces, is also 100 by 100 by 45 mm in size, gadolinium poisoned 16 mm below each of the two viewed surfaces, and decoupled from the graphite reflector with cadmium. The solid methane ''C'' moderator has a re-entrant ''grooved'' geometry. The moderator is 100 by 100 by 80 mm overall, with 40 mm deep 12 mm wide horizontal grooves in the viewed surface. These grooves cover 50% of the viewed surface area. The ''C'' moderator is unpoisoned, but is decoupled from the graphite reflector with 0.5 mm of cadmium.

Iverson, E. B.

1998-05-18

99

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

National Technical Information Service (NTIS)

At the Intense Pulsed Neutron Source (IPNS) 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 ...

R. K. Crawford J. R. Haumann A. J. Schultz G. P. Felcher J. E. Epperson

1990-01-01

100

Depth-graded Multilayers as Neutron Doppler Converts At Pulsed Neutron Source.  

National Technical Information Service (NTIS)

A moving diffractor changes the energy of elastically diffracted neutrons by the Doppler effect. Depth-graded multilayers can diffract neutrons over a large band of energy. Using a pulsed neutron source, such a depth-graded multilayer, decelerating synchr...

A. D. Stoica

2001-01-01

101

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...

102

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

103

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

104

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

105

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

106

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

Microsoft Academic Search

At the Intense Pulsed Neutron Source (IPNS) 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

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

1990-01-01

107

Economic efficiency of radionuclide neutron sources  

SciTech Connect

Neutron sources based on various radionuclides are widely used in technological monitoring in many branches of industry, geological prospecting and also in medicine. Factors affecting the efficiency of radionuclide neutron sources (RNS) are discussed. The method considered here enables the formulation of comparative economic estimates at the stages of development and application of RNS in the solution of several problems such as: determining the limits of competitiveness of RNS based on different radionuclides; and also of RNS and other types of NS; determining the efficiency of utilization of specific RNS in comparison with conventional methods of performing the work; justifying the nomenclature of RNS manufacture with specific radionuclides as well as other areas described here.

Kirillov, E.V.; Karelin, E.A.; Klinov, A.V.; Konyashova, G.V.; Kudryashov, L.N.; Toporov, Y.G.

1985-11-01

108

Compact, inexpensive, epithermal neutron source for BNCT  

Microsoft Academic Search

A new rf-focused linac structure, designed specifically to increase the acceleration efficiency and reduce the cost of linac structures in the few-MeV range, may win the role as the optimum accelerator-based epithermal neutron source for the BNCT application. This new linac structure resembles a drift tube linac (DTL) with radio frequency quadrupole (RFQ) focusing incorporated into each drift tube, hence

D. A. Swenson

1999-01-01

109

Compact, inexpensive, epithermal neutron source for BNCT  

Microsoft Academic Search

A new rf-focused linac structure, designed specifically to increase the acceleration efficiency and reduce the cost of linac structures in the few-MeV range, may win the role as the optimum accelerator-based epithermal neutron source for the BNCT application. This new linac structure resembles a drift tube linac (DTL) with radio frequency quadrupole (RFQ) focusing incorporated into each ``drift tube,'' hence

D. A. Swenson

1999-01-01

110

Spallation Neutron Source Beam Current Monitor Electronics  

Microsoft Academic Search

This paper will discuss the present electronics design for the beam current monitor system to be used throughout the Spallation Neutron Source (SNS) under construction at Oak Ridge National Laboratory. The beam is composed of a micro-pulse structure due to the 402.5MHz RF, and is chopped into mini-pulses of 645ns duration with a 300ns gap, providing a macro-pulse of 1060

M. Kesselman; W. C. Dawson

2002-01-01

111

Spallation Neutron Source Radiation Shielding Issues  

SciTech Connect

This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and {sup 7}Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and after shutdown were also assessed.

Azmy, Y.Y.; Barnes, J.M.; Drischler, J.D.; Johnston, J.O.; Lillie, R.A.; McNeilly, G.S.; Santoro, R.T.

1999-11-14

112

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

113

Spallation neutron source\\/proposed rf system  

Microsoft Academic Search

The rf system for the synchrotrons of the spallation neutron source is designed to accelerate 1.4 10¹⁴ protons\\/pulse to an energy of 3.6 GeV. Injection energy is 600 MeV. The synchrotron repetition frequency is 30 Hz, with a 50% duty factor. The choice of operating frequency is somewhat arbitrary. The authors propose a low frequency of 1.3 to 1.6

M. Meth; J. M. Brennan

1993-01-01

114

Miniature neutron sources: Thermal neutron sources and their users in the academic field  

SciTech Connect

The three levels of thermal neutron sources are introduced - University laboratory sources infrastructure sources and world-class sources - and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for University sources based on {alpha}-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small reactors. Some possibilities for accelerator sources that could meet this need are considered.

Egelstaff, P.A. (Guelph Univ., ON (Canada). Dept. of Physics); Carpenter, J.M. (Argonne National Lab., IL (United States))

1992-01-01

115

Miniature neutron sources: Thermal neutron sources and their users in the academic field  

SciTech Connect

The three levels of thermal neutron sources are introduced - University laboratory sources infrastructure sources and world-class sources - and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for University sources based on {alpha}-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small reactors. Some possibilities for accelerator sources that could meet this need are considered.

Egelstaff, P.A. [Guelph Univ., ON (Canada). Dept. of Physics; Carpenter, J.M. [Argonne National Lab., IL (United States)

1992-09-01

116

Magnified neutron radiography with coded sources  

NASA Astrophysics Data System (ADS)

A coded source imaging system has been developed to improve resolution for neutron radiography through magnification and demonstrated at the High Flux Isotope Reactor (HFIR) CG-1D instrument. Without magnification, the current resolution at CG-1D is 80?m using a charge-coupled device (CCD) equipped with a lens. As for all neutron imaging instruments, magnification is limited by a large source size. At CG-1D the size is currently limited to 12mm with a circular aperture. Coded source imaging converts this large aperture into a coded array of smaller apertures to achieve high resolution without the loss of flux for a single pinhole aperture, but requires a decoding step. The developed system has demonstrated first magnified radiographic imaging at magnifications as high as 25x using coded apertures with holes as small as 10?m. Such a development requires a team with a broad base of expertise including imaging systems design, neutron physics, microelectronics manufacturing methods, reconstruction algorithms, and high performance computing. The paper presents the system design, discusses implementation challenges, and presents imaging results.

Bingham, Philip R.; Santos-Villalobos, Hector; Lavrik, Nickolay; Bilheux, Hassina; Gregor, Jens

2013-03-01

117

Standard Neutron Sources. Bibliography No. 11; SOURCES ETALONS DE NEUTRONS. Bibliographie No. 11  

Microsoft Academic Search

Seventy-nine abstracts are presented on the methods and processes of ; neutron source calibration and the preparation and properties of standard sources. ; The abstracts are arranged chronologically and cover a period from l936 to 196l. ; (D.L.C.)

Desdevises

1961-01-01

118

Advanced Neutron Sources: Plant Design Requirements  

SciTech Connect

The Advanced Neutron Source (ANS) is a new, world class facility for research using hot, thermal, cold, and ultra-cold neutrons. At the heart of the facility is a 350-MW{sub th}, heavy water cooled and moderated reactor. The reactor is housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides fans out into a large guide hall, housing about 30 neutron research stations. Office, laboratory, and shop facilities are included to provide a complete users facility. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory at the end of the decade. This Plant Design Requirements document defines the plant-level requirements for the design, construction, and operation of the ANS. This document also defines and provides input to the individual System Design Description (SDD) documents. Together, this Plant Design Requirements document and the set of SDD documents will define and control the baseline configuration of the ANS.

Not Available

1990-07-01

119

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

120

The advanced neutron source reactor: An overview  

SciTech Connect

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 and nuclear physics experiments. In addition, there will be irradiation positions and rabbit tubes for in-pile experiments, testing and isotopes production (including transuranium isotopes). To reduce technical risks and to minimize safety issues, the reactor design is based on technology already employed in existing research reactors. The fuel elements are annular assemblies of aluminum clad involute fuel plates, similar to the design of the High Flux Isotope Reactor (HFIR) at Oak Ridge and the Institut Laue-Langevin (ILL) Reactor in Grenoble. As is common with many other research reactors, the core is cooled, moderated and reflected by heavy water. The preferred fuel is U{sub 3}Si{sub 2} - a high-density fuel form developed by Argonne National Laboratory and Babcock and Wilcox that has been extensively tested in reactors in the United States, Europe and Japan. 7 figs., 2 tabs.

West, C.D.

1990-01-01

121

New RadioIsotope technique of measuring the thickness of fine sheet materials  

Microsoft Academic Search

and V. Yanushkovskii A new continuous method of measuring the thickness of very thin materials'during their p roduction has been worked out at the Riga Scientific Research Institute for Radio-Isotope Instruments. The operation of the instrument is based on the scattering of fl-radiation from a gaseous medium. In such a case, the energy spectrum of the scattered fl-radiation becomes much

A. Muzis; B. Ol'shvanger; I. Taksar; . Tesnavs; A. Tumul'kan; I. Fedotov; V. Shabalin; V. Yanushkovskii

1968-01-01

122

The status of the spallation neutron source ion source  

NASA Astrophysics Data System (ADS)

The ion source for the spallation neutron source (SNS) is a radio-frequency, multicusp source designed to deliver 45 mA of H- 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 ~200 ?s and repetition rate ~5 Hz) for extended periods of time while the high-current tests involve source operation at full duty-factor of 6% (1 ms/60 Hz). This report discusses routine performance of the source employed in the commissioning role as well as the initial results of high-current tests performed on the HSS.

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

2004-05-01

123

THE SPALLATION NEUTRON SOURCE PROJECT - PHYSICAL AND TECHNICAL CHALLENGES.  

SciTech Connect

The Spallation Neutron Source (SNS) is designed to reach an average proton beam power of 1.4 MW for pulsed neutron production. This paper summarizes design aspects and physical challenges to the project.

WEI,J.

2002-04-08

124

Dual-mode operation of a neutron source, a concept  

NASA Technical Reports Server (NTRS)

Pulsed neutron source operates in conjunction with a photomultiplier tube coupled to a gamma ray scintillation crystal. This allows measurements of gamma radiation from both inelastic scattering and thermal neutron capture in a single experiment.

Givens, W. W.; Mills, W. R., Jr.

1969-01-01

125

Status of the intense pulsed neutron source  

SciTech Connect

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

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

1988-01-01

126

Spectrometry and dosimetry of a neutron source  

NASA Astrophysics Data System (ADS)

Using the Monte Carlo methods, the spectrum, dose equivalent and ambient dose equivalent of a 239PuBe have been determined at several distances. The spectrum and both doses were determined to 100 cm with a Bonner sphere spectrometer. These quantities were obtained by unfolding the spectrometer count rates using artificial neural networks. The dose equivalent was measured with the area neutron dosemeter Eberline model NRD, to 100, 200 and 300 cm. All the measurements were carried out in an open space to avoid the room-return. With these results, it was found that this source has a yield of 8.41E(6) n/s.

Vega-Carrillo, H. R.; Manzanares-Acua, E.; Hernndez-Dvila, V. M.; Gonzlez, J. Ramrez; Villasana, R. Hernndez; Ruiz, A. Chacn

127

Fusion neutron detector calibration using a table-top laser generated plasma neutron source  

NASA Astrophysics Data System (ADS)

Using a high intensity, femtosecond laser driven neutron source, a high-sensitivity neutron detector was calibrated. This detector is designed for observing fusion neutrons at the Z accelerator in Sandia National Laboratories. Nuclear fusion from laser driven deuterium cluster explosions was used to generate a clean source of nearly monoenergetic 2.45 MeV neutrons at a well-defined time. This source can run at 10 Hz and was used to build up a clean pulse-height spectrum on scintillating neutron detectors giving a very accurate calibration for neutron yields at 2.45 MeV.

Hartke, R.; Symes, D. R.; Buersgens, F.; Ruggles, L. E.; Porter, J. L.; Ditmire, T.

2005-03-01

128

Directional Detection of a Neutron Source.  

National Technical Information Service (NTIS)

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 ran...

L. Forman P. E. Vanier

2006-01-01

129

Using spallation neutron sources for defense research  

SciTech Connect

Advanced characterization techniques and accelerated simulation are the cornerstones of the Energy Department`s science-based program to maintain confidence in the safety, reliability, and performance of the US nuclear deterrent in an era of no nuclear testing. Neutrons and protons provided by an accelerator-based facility have an important role to play in this program, impacting several of the key stockpile stewardship and management issues identified by the Department of Defense. Many of the techniques used for defense research at a spallation source have been used for many years for the basic research community, and to a lesser extent by industrial scientists. By providing access to a broad spectrum of researchers with different backgrounds, a spallation source such as the Los Alamos Neutron Science Center is able to promote synergistic interaction between defense, basic and industrial researchers. This broadens the scientific basis of the stockpile stewardship program in the short term and will provide spin-off to industrial and basic research in the longer term.

Pynn, R.; Sterbenz, S.M.; Weinacht, D.J.

1996-12-31

130

Status of the intense pulsed neutron source  

SciTech Connect

Fortunately in spite of some premature reports of its impending demise, IPNS has passed the fourth anniversary of the first delivery of protons to the targets (May 5, 1981) and is approaching the fourth anniversary of its operation as a scattering facility (August 4, 1981). On June 10, 1984, the RCS delivered its one billionth pulse to the IPNS target - the total number of protons delivered to the targets amounted then to 75 stp cm/sup 3/ of H/sub 2/ gas. Since startup IPNS has improved steadily in terms of the performance of the Rapid Cycling Synchrotron, the source and its moderators and the scattering instruments, and a substantial and productive user program has evolved. This report summarizes the current status of the Intense Pulsed Neutron Source at Argonne National Laboratory. We include reference to recent accelerator operating experience, neutron facility operating experience, improvements to these systems, design work on the ASPUN high-current facility, booster target design, the new solid methane moderator, characterization of the room temperature moderators, and provide some examples of recent results from several of the spectrometers.

Carpenter, J.M.; Brown, B.S.; Kustom, R.L.; Lander, G.H.; Potts, C.W.; Schulke, A.W.; Wuestefeld, G.

1985-01-01

131

Field ion source development for neutron generators  

NASA Astrophysics Data System (ADS)

An ion source based on the principles of electrostatic field desorption is being developed to improve the performance of existing compact neutron generators. The ion source is an array of gated metal tips derived from field electron emitter array microfabrication technology. A comprehensive summary of development and experimental activities is presented. Many structural modifications to the arrays have been incorporated to achieve higher tip operating fields, while lowering fields at the gate electrode to prevent gate field electron emission which initiates electrical breakdown in the array. The latest focus of fabrication activities has been on rounding the gate electrode edge and surrounding the gate electrode with dielectric material. Array testing results have indicated a steady progression of increased array tip operating fields with each new design tested. The latest arrays have consistently achieved fields beyond those required for the onset of deuterium desorption (20 V/nm), and have demonstrated the desorption of deuterium at fields up to 36 V/nm. The number of ions desorbed from an array has been quantified, and field desorption of metal tip substrate material from array tips has been observed for the first time. Gas-phase field ionization studies with 10,000 tip arrays have achieved deuterium ion currents of 50 nA. Neutron production by field ionization has yielded 10 2 n/s from 1 mm 2 of array area using the deuterium-deuterium fusion reaction at 90 kV.

Bargsten Johnson, B.; Schwoebel, P. R.; Holland, C. E.; Resnick, P. J.; Hertz, K. L.; Chichester, D. L.

2012-01-01

132

14MeV Neutron Generator Used as a Thermal Neutron Source  

Microsoft Academic Search

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

Dioszegi

2008-01-01

133

Spallation neutron source/proposed rf system  

SciTech Connect

The rf system for the synchrotrons of the spallation neutron source is designed to accelerate 1.4 {times} 10{sup 14} protons/pulse to an energy of 3.6 GeV. Injection energy is 600 MeV. The synchrotron repetition frequency is 30 Hz, with a 50% duty factor. The choice of operating frequency is somewhat arbitrary. The authors propose a low frequency of 1.3 to 1.6 MHz, which is the second harmonic of the revolution frequency. The advantages of such a low frequency system are: (1) There will be two bunches in the machines and the time between bunches will be sufficiently long to allow for the rise time of the extraction kicker. No missing bunches will be necessary, which simplifies injection, and transient beam loading problems are avoided. (2) With only two bunches there are no unstable coupled-bunch modes of longitudinal instability. (3) In multi-gap low frequency cavities the transient time factor is essentially unity because the rf wavelength is much longer than the cavity dimensions. (4) Cavities in this low frequency range are basically lumped-element type structures, where the sources of the inductance and capacitance are clearly identified. This allows effective control of higher order mode impedances in such cavities. (5) Ferrite-loaded low-frequency cavities are necessarily low impedance structures; ferrites are lossy. This low impedance makes it possible to achieve system stability without large amounts of feedback in a heavily beam loaded system. (6) BNL has a good deal of experience in building rf systems in this range of frequency, voltage, and power level. This report outlines the essential parameters of a practical rf system for the synchrotrons of the Spallation Neutron Source. The design uses materials, ferrites and vacuum tubes, that are commercially available and with which the laboratory has recent experience.

Meth, M.; Brennan, J.M.

1993-09-30

134

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

135

Cryogenic System for the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) is a neutron-scattering facility being built at Oak Ridge, TN for the US Department of Energy. The SNS accelerator linac consists of superconducting radio-frequency (SRF) cavities in cryostats (cryomodules). The linac cryomodules are cooled to 2.1 K by a 2300 watt cryogenic refrigeration system. As an SNS partner laboratory, Jefferson Lab is responsible for the installed integrated cryogenic system design for the SNS linac accelerator consisting of major subsystem equipment engineered and procured from industry. Jefferson Lab's work included developing the major vendor subsystem equipment procurement specifications, equipment procurement, and the integrated system engineering support of the field installation and commissioning. The major cryogenic system components include liquid nitrogen storage, gaseous helium storage, cryogen distribution transfer line system, 2.1-K cold box consisting of four stages of cold compressors, 4.5-K cold box, warm helium compressors with its associated oil removal, gas management, helium purification, gas impurity monitoring systems, and the supportive utilities of electrical power, cooling water and instrument air. The system overview, project organization, the important aspects, and the capabilities of the cryogenic system are described.

Arenius, D.; Chronis, W.; Creel, J.; Dixon, K.; Ganni, V.; Knudsen, P. [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)

2004-06-23

136

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

137

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

138

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

139

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

140

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

141

Neutron Sources for the Medical Use.  

National Technical Information Service (NTIS)

Recently encouraging results of the neutron radiation therapy have been obtained in clinical trials. In addition to the therapy, the neutrons are applied to diagnosis in addition to the production of radioisotopes, that is, in-vivo activation analysis and...

K. Tsukada

1980-01-01

142

Performance of a Clad Tungsten Rod Spallation Neutron Source Target  

Microsoft Academic Search

Tungsten rods, slip-clad with Type 304L stainless steel, performed successfully as a spallation neutron source target operating to a peak fluence of 4 x 10²¹ p\\/cm². The target was used as a neutron source during the Accelerator Production of Tritium (APT) materials irradiation program at the Los Alamos Neutron Science Center. Tungsten rods of 2.642-mm diameter were slip-fit in Type

Walter F. Sommer; Stuart A. Maloy; McIntyre R. Louthan; Gordon J. Willcutt; Phillip D. Ferguson; Michael R. James

2005-01-01

143

A Solid Deuterium Source for Ultra-Cold Neutrons  

NASA Astrophysics Data System (ADS)

A new superthermal solid deuterium based source for ultra-cold neutrons (UCN) is under development at Los Alamos. This source will be used to provide the UCN for an improved measurement of the beta-asymmetry in neutron decay. In this super-thermal source, UCN are produced by down-scattering of cold neutrons. These cold neutrons are produced by the LANSCE proton beam incident on a tungsten spallation target which is closely coupled to the UCN source. Predictions suggest that this source should provide much greater UCN rates than existing sources. Production tests conducted over the last year have yielded UCN rates sufficient (scaled to greater proton beam flux) for the beta-asymmetry measurment. A detailed description of the source, results of the production tests, and planned future improvements to the source will be presented. Comparisons of the production rates with calculations will be presented in the following talk.

Saunders, A.; Bowles, T.; Hill, R.; Hogan, G.; Lamoreaux, S.; Morris, C.; Sattelberger, J.; Seestrom, S.; Teasdale, W.; Hoedl, S.; Liu, C.-Y.; Smith, D. A.; Young, A. R.; Filippone, B.; Ito, T.; Yuan, J.; Geltenbort, P.

1999-10-01

144

International workshop on plasma-based neutron sources.  

National Technical Information Service (NTIS)

The workshop was devoted to discussion of the status and future directions of work on plasma-based neutron sources. The workshop presentations demonstrated significant progress in development of the concepts of these sources and in broadening the required...

1996-01-01

145

Shielding design and analyses of 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. 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

Zhaopeng Zhong; Yousry Gohar

2011-01-01

146

High-Power Linac for the Spallation Neutron Source  

Microsoft Academic Search

The Spallation Neutron Source (SNS) will be the world's most intense source of neutrons for fundamental science and industrial applications. Design and construction of this facility, located at Oak Ridge, is a joint venture between six DOE laboratories. Construction began in 1999 and is currently ahead of the scheduled 2006 completion date. Injecting a high-power, pulsed proton beam into a

D. J. Rej

2002-01-01

147

Plutonium Beryllium Neutron Source as a Secondary Calibration Standard.  

National Technical Information Service (NTIS)

Plutonium-Beryllium (Pu-Be) neutron sources are calibrated with respect to total output, using a manganese-sulfate bath. When such sources are used as a point isotropic, secondary standard, inaccuracies occur due to the following reasons: (1) The neutron ...

J. A. Devanney

1968-01-01

148

The national spallation neutron source target station: A general overview  

SciTech Connect

The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.

Gabriel, T.A.; Barnes, J.N.; Charlton, L.A. [and others

1997-06-01

149

PREFACE: Neutrino physics at spallation neutron sources  

NASA Astrophysics Data System (ADS)

Unique because of their super-light masses and tiny interaction cross sections, neutrinos combine fundamental physics on the scale of the miniscule with macroscopic physics on the scale of the cosmos. Starting from the ignition of the primal p-p chain of stellar and solar fusion reactions that signal star-birth, these elementary leptons (neutrinos) are also critical players in the life-cycles and explosive deaths of massive stars and the production and disbursement of heavy elements. Stepping beyond their importance in solar, stellar and supernova astrophysics, neutrino interactions and properties influence the evolution, dynamics and symmetries of the cosmos as a whole. Further, they serve as valuable probes of its material content at various levels of structure from atoms and nuclei to valence and sea quarks. In the light of the multitude of physics phenomena that neutrinos influence, it is imperative to enhance our understanding of neutrino interactions and properties to the maximum. This is accentuated by the recent evidence of finite neutrino mass and flavour mixing between generations that reverberates on the plethora of physics that neutrinos influence. Laboratory experiments using intense neutrino fluxes would allow precision measurements and determination of important neutrino reaction rates. These can then complement atmospheric, solar and reactor experiments that have enriched so valuably our understanding of the neutrino and its repertoire of physics applications. In particular, intermediate energy neutrino experiments can provide critical information on stellar and solar astrophysical processes, along with advancing our knowledge of nuclear structure, sub-nuclear physics and fundamental symmetries. So where should we look for such intense neutrino sources? Spallation neutron facilities by their design are sources of intense neutrino pulses that are produced as a by-product of neutron spallation. These neutrino sources could serve as unique laboratories to enrich our knowledge of neutrino physics and the multifaceted science it interfaces. In fact, the neutrino energy spectra expected at spallation neutron facilities overlap remarkably with those emanating from distant supernovae and these sources seem `made to order' for terrestrial studies of supernova reactions. They are also in a suitable energy regime to pursue neutrino-mediated studies of nuclear structure, fundamental symmetries and solar reactions. Recent research indicates neutrino-nuclear reactions may be even more influential in supernova dynamics and detection than hitherto believed. The need for in-depth understanding of the individual neutrino-nuclear reactions that collectively have dramatic effects on the large-scale dynamics of evolving stars points to laboratory measurements of neutrino reactions on various nuclei as a premier requirement of neutrino-nuclear astrophysics. Such experimental data can improve our input to the extensive modelling projects that investigate the evolutionary stages of exploding supernovae and further our understanding of their internal physics. State-of-the-art simulations exploring the neutrino-reheating phases fail to produce explosions---yet clearly nature explodes her supernovae. Matters pertaining to the galactic abundance of very p-rich nuclei and the various isotope ratios are by no means well defined and demand further research, as do the intricacies of the nucleo-synthesis channels. Neutrino-nuclear experiments are also essential for proper development and calibration of appropriate supernova detectors. Solar neutrino research and detection have contributed vastly to our current understanding of neutrino science and have helped to validate the standard solar model. The chapter is by no means closed and experiments with intense neutrino fluxes could enrich valuably our understanding of both neutrino and solar physics. Neutrino nuclear reactions are not only important for their role in nuclear astrophysics, but also for the insight they provide on nuclear structure and the theoretical models used to calculat

Avignone, F. T.; Chatterjee, L.; Efremenko, Y. V.; Strayer, M.

2003-11-01

150

New opportunities in neutron capture research using advanced pulsed neutron sources  

SciTech Connect

The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. Prospective experiments are reviewed with particular attention to those with a strong connection to capture gamma-ray spectroscopy.

Bowman, C.D.

1987-08-01

151

Moving converter as the possible tool for producing ultra-cold neutrons on pulsed neutron sources  

NASA Astrophysics Data System (ADS)

A method is proposed for producing ultra-cold neutrons (UCN) at aperiodic pulse neutron sources. It is based on the use of the fast moving cooled converter of UCN which synchronises with the neutron pulse and it includes trapping of the generated UCN in a moving trap.

Pokotilovskij, Yu. N.

1992-05-01

152

A capture-gated neutron spectrometer for characterization of neutron sources and their shields  

NASA Astrophysics Data System (ADS)

A portable capture-gated neutron spectrometer was designed and built. The spectrometer consists of a boron-loaded scintillator. Data acquisition is performed in list-mode. 252Cf and AmBe sources and various neutron and gamma shields were used to characterize the response of the device. It is shown that both the unfolded capture-gated neutron spectrum and the singles spectrum up to 5 MeV should be utilized. Source identification is then possible and important information is revealed regarding the surroundings of the source. The detector?s discrimination of neutrons from photons is relatively good; specifically, one out of 105 photons is misclassified as a neutron and, more importantly, this misclassification rate can be calculated precisely for different measurement environments and can be taken into account in setting alarm limits for neutron detection. The source and source shield identification capabilities of the detector make it an interesting asset for security applications.

Holm, Philip; Perjrvi, Kari; Ristkari, Samu; Siiskonen, Teemu; Toivonen, Harri

2014-07-01

153

Low Energy Accelerator-Based Neutron Sources for Neutron Capture Therapy  

Microsoft Academic Search

An epithermal neutron beam design for an accelerator -based neutron source for neutron capture therapy (NCT) has been studied. Calculation shows that, of many possible neutron-producing reactions, the Li-7(p,n)Be-7 and H-3(p,n)He -3 reactions are the more promising reactions for producing high neutron yields for NCT. The total neutron yield from the Li-7(p,n)Be-7 and H-3(p,n)He-3 reactions are 1.5 times 10^{-4} and

1992-01-01

154

Neutron sources in a 24-MV medical linear accelerator  

SciTech Connect

During the assembly of the prototype Clinac 2500, a unique opportunity arose to measure the cumulative total neutron yield of the machine as the major subassemblies were added, section by section. Differentiation of the results led to an inventory of the relative strength of the several neutron sources identified. The method utilized the fact that the scattered neutron fluence in a cavity in concrete is nearly uniform throughout the space and proportional to the fast neutron source strength. When normalized to the neutron output of the guide with bend magnet vacuum chamber, the relative neutron source strengths found were target, 1.9; primary collimator, 2.4; steel filter, 0.6; tungsten filter, 1.5; and jaw system, 0.8 open and approximately 2.0 closed. There is reasonable agreement between these measurements and published estimates of the yields from the major components of the treatment head.

LaRiviere, P.D.

1985-11-01

155

Lithium neutron producing target for BINP accelerator-based neutron source  

Microsoft Academic Search

Pilot innovative accelerator-based neutron source for neutron capture therapy is under construction now at the Budker Institute of Nuclear Physics, Novosibirsk, Russia. One of the main elements of the facility is lithium target, that produces neutrons via threshold 7Li(p,n)7Be reaction at 25kW proton beam with energies 1.915 or 2.5MeV.In the present report, the results of experiments on neutron producing target

B. Bayanov; V. Belov; V. Kindyuk; E. Oparin; S. Taskaev

2004-01-01

156

Status of the low energy neutron source at Indiana University  

NASA Astrophysics Data System (ADS)

The National Science Foundation has recently approved funding for LENS (the low energy neutron source) at Indiana University and construction of this facility has begun. LENS represents a new paradigm for economically introducing neutron scattering into a university or industrial setting. In this design, neutrons are produced in a long-pulse (1 ms) mode through (p,n) reactions on a water-cooled Be target and the target is tightly coupled to a cryogenic moderator with a water reflector. This design gives a facility suitable for materials research, the development of new neutron instrumentation, and the education of new neutron scientists.

Baxter, D. V.; Cameron, J. M.; Derenchuk, V. P.; Lavelle, C. M.; Leuschner, M. B.; Lone, M. A.; Meyer, H. O.; Rinckel, T.; Snow, W. M.

2005-12-01

157

An overview of the planned advanced neutron source facility  

SciTech Connect

The Advanced Neutron Source (ANS), now in the conceptual design stage, will be a new user facility for neutron research, including neutron beam experiments, materials irradiation testing and materials analysis capabilities, and production facilities for transuranic and lighter isotopes. The neutron source is to be the world's highest flux beam reactor and is based on existing reactor technology to minimize safety issues. The preferred fuel, U{sub 3}Si{sub 2}, has been tested in operating reactors in the United States, Japan, and Europe. The core is cooled, moderated, and reflected by heavy water, common practice for research reactors. 3 refs., 9 figs., 3 tabs.

West, C.D.

1990-01-01

158

Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture  

SciTech Connect

The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

Scott Wilde, Raymond Keegan

2008-07-01

159

Basic physics with spallation-neutron sources  

Microsoft Academic Search

The neutron has unique intrinsic properties widely used in basic and applied sciences. The neutron plays a well-known role in applied sciences and technology and is a unique probe well suited for the exploration of condensed-matter properties. But the neutron is also used for many other basic-physics studies, including nuclear physics, particle physics, fundamental physics, astrophysics, and cosmology. These last

Michaudon

1994-01-01

160

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

161

Radio-isotopic calibration of the Late Eocene - Early Oligocene geomagnetic polarity time scale  

NASA Astrophysics Data System (ADS)

The Geomagnetic Polarity Time Scale (GPTS) has been the subject of several revisions over the last few decades, with a trend toward increasing reliance on astronomically tuned age models over traditional radio-isotopic calibration. In the 2012 Geological Time Scale (GTS12) a comparison between radio-isotopic and astronomical age models for the GPTS yielded partially divergent results, with discrepancies of up to 0.4 Myr in the age of magnetic reversals around the Eocene - Oligocene transition (Vandenberghe et al., 2012). Radio-isotopic constraints on the age of Late Eocene - Early Oligocene magnetic reversals are available from two key sedimentary successions which host datable volcanic tuffs: the marine record of the Umbria-Marche basin in Italy, and the terrestrial White River Group of North America, however concerns have been raised regarding both the accuracy of dates obtained from these successions, and the reliability of their magnetic polarity records (Hilgen and Kuiper, 2009). Here we present a fully integrated radio-isotopic and magnetostratigraphic dataset from the Late Eocene - Early Oligocene North American terrestrial succession with the aim of assessing the accuracy and precision of numerical ages derived from the GPTS. We developed a magnetic polarity record for two partially overlapping sections: Flagstaff Rim in Wyoming and Toadstool Geologic Park in Nebraska, which together provide coverage for the time interval between 36-31 Myr (C16n.2n - C12n) and calibrated this record using an age model based on 14 Pb/U weighted mean ID-TIMS dates obtained on zircons from primary air fall tuffs. The uncertainty of our age model includes random and systematic components for all radio-isotopic tie-points, as well as estimated uncertainties in the stratigraphic position of both the magnetic reversals and the dated tuffs. Our Pb/U dates are 0.4 - 0.8 Myr younger than previously published Ar/Ar data (Swisher and Prothero,1990, recalculated to 28.201 Myr for Fish Canyon sanidine). This, together with the detection of a previously unreported normal polarity zone in the Flagstaff Rim section, correlative to C15n, greatly reduces previously reported discrepancies in the correlation of marine and terrestrial records of the Eocene - Oligocene transition. Our interpolated magnetic reversal dates have uncertainties of 0.05 - 0.10 Myr, are consistent with relatively constant spreading rates for the South Atlantic magnetic anomaly profile of Cande and Kent (1992), and are in good agreement with the astronomically tuned time scale of Paelike et al (2006). A comparison with the astronomically tuned GTS12 record reveals a systematic discrepancy of ca. + 0.3 Myr for Late Eocene reversals. Cande, S.K., Kent, D.V. (1992), Journal of Geophysical Research - Solid Earth, 97, 13917-13951 Hilgen F.J., Kuiper, K.F. (2009) , Geological Society of America Special Papers, 452, 139-148 Paelike H., Norris, R.D., Herrle, J.O., Wilson, P.A., Coxall, H.K., Lear, C.H., Shackleton, N.J., Tripati, A.K., Wade, B.S. (2006), Science, 314, 1894-1898 Swisher, C.C., Prothero, D.R. (1990), Science, 249, 760-762 Vandenberghe N., Hilgen, F.J., Speijer, R.P. (2012), in Gradstein, F.M., Ogg, J.G., Schmitz, M.D., Ogg, G.M. (eds.) The Geologic Time Scale 2012, vol.2, 855-921

Sahy, Diana; Fischer, Anne U.; Condon, Daniel J.; Terry, Dennis O.; Hiess, Joe; Abels, Hemmo; Huesing, Silja K.; Kuiper, Klaudia F.

2013-04-01

162

On the optimum design of a white neutron source  

Microsoft Academic Search

The conceptual design of a neutron source for time-of-flight (TOF) measurements with good energy resolution was presented in a previous paper, aiming at its implementation on a high energy electron Linac. There is a growing interest in nuclear data worldwide and the existing neutron sources are clearly insufficient.The distinguished feature of this source is the very small size of the

S. Bartalucci; V. Angelov

2011-01-01

163

PLUTONIUM-BERYLLIUM NEUTRON SOURCES THEIR FABRICATION AND THEIR YIELD  

Microsoft Academic Search

An investigntion of the plutonium-beryllium phase diagram demonstrates ;\\u000a the suitability of these alloys and most particularly the intermetallic compound ;\\u000a PuBe for stable neutron sources. These sources are superior to polonium-;\\u000a beryllium sources in respect to sthbility of neutron yield as a iunction of time ;\\u000a and the prediotability of neutroc yield as a function of mass. The gamma-ray

R. E. Tate; A. S. Coffinberry

1958-01-01

164

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

165

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

166

Accelerator-based neutron source for the neutron-capture and fast neutron therapy at hospital  

NASA Astrophysics Data System (ADS)

The proton accelerator complex for neutron production in lithium target discussed, which can operate in two modes. The first provides a neutron beam kinematically collimated with good forward direction in 25 and average energy of 30 keV, directly applicable for neutron-capture therapy with high efficiency of proton beam use. The proton energy in this mode is 1.883-1.890 MeV that is near the threshold of the 7Li( p, n) 7Be reaction. In the second mode, at proton energy of 2.5 MeV, the complex-produced neutron beam with maximum energy board of 790 keV which can be used directly for fast neutron therapy and for neutron-capture therapy after moderation. The project of such a neutron source is based on the 2.5 MeV original electrostatic accelerator tandem with vacuum insulation developed at BINP which is supplied with a high-voltage rectifier. The rectifier is produced in BINP as a part of ELV-type industrial accelerator. Design features of the tandem determining its high reliability in operation with a high-current (up to 40 mA) H - ion beam are discussed. They are: the absence of ceramic accelerator columns around the beam passage region, good conditions for pumping out of charge-exchange gaseous target region, strong focusing optics and high acceleration rate minimizing the space charge effects. The possibility of stabilization of protons energy with an accuracy level of 0.1% necessary for operation in the near threshold region is considered. The design description of H - continuous ion source with a current of 40 mA is also performed. To operate with a 100 kW proton beam it is proposed to use liquid-lithium targets. A thin lithium layer on the surface of a tungsten disk cooled intensively by a liquid metal heat carrier is proposed for use in case of the vertical beam, and a flat liquid lithium jet flowing through the narrow nozzle - for the horizontal beam.

Bayanov, B. F.; Belov, V. P.; Bender, E. D.; Bokhovko, M. V.; Dimov, G. I.; Kononov, V. N.; Kononov, O. E.; Kuksanov, N. K.; Palchikov, V. E.; Pivovarov, V. A.; Salimov, R. A.; Silvestrov, G. I.; Skrinsky, A. N.; Soloviov, N. A.; Taskaev, S. Yu.

167

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.

Krlk, M.; olc, J.; Chvtil, D.; Krist, P.; Turek, K.; Granja, C.

2012-08-01

168

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

169

LABORATORY EXPERIMENTS USING A PULSED NEUTRON SOURCE  

Microsoft Academic Search

Laboratory experiments using pulsed neutron techniques are valuable for ; giving physical interpretation of reactor theory. Three experiments illustrate ; different pulsed neutron measurements. In one case diffusion properties of a ; sample are measured by varying the geometry of the sample. In another the ; absorption cross section of a solute is measured by varying the sample without ;

R. B. Mesler; H. G. OBrien; D. Freed

1962-01-01

170

Basic physics with spallation-neutron sources.  

National Technical Information Service (NTIS)

The neutron has unique intrinsic properties widely used in basic and applied sciences. The neutron plays a well-known role in applied sciences and technology and is a unique probe well suited for the exploration of condensed-matter properties. But the neu...

A. F. Michaudon

1994-01-01

171

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 completion and all key components have been tested. Here we report the current status of the project.

Pierce, Josh; Zhao, J. K. [Neutron Scattering Sciences Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Crabb, Don [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States)

2009-08-04

172

Measurements of the neutron source strength at DIII-D  

Microsoft Academic Search

A set of neutron counters and a pair of scintillators measure the 2.5 MeV neutron emission produced by the DIII-D tokamak. The neutron counter set provides a large dynamic range (?7 orders of magnitude) while the scintillators provide the very fast resolution needed for studying transient events. The counters are absolutely calibrated in situ with a 252Cf source and the

W. W. Heidbrink; P. L. Taylor; J. A. Phillips

1997-01-01

173

Measurements of the neutron source strength at DIII-D  

Microsoft Academic Search

A set of neutron counters and a pair of scintillators measure the 2.5 MeV neutron emission produced by the DIII-D tokamak. The neutron counter set provides a large dynamic range (7 orders of magnitude) while the scintillators provide the very fast resolution needed for studying transient events. The counters are absolutely calibrated {ital in situ} with a ²⁵²Cf source and

W. W. Heidbrink; P. L. Taylor; J. A. Phillips

1997-01-01

174

Physical design of target station and neutron instruments for China Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

The China Spallation Neutron Source (CSNS) is the first accelerator-based multidiscipline user facility to produce pulsed neutrons by tungsten target under collision of a pulsed proton beam with a beam power of 100 kW at a repetition rate of 25 Hz. In this paper, we focus on the physical design of CSNS target station and neutron instruments. Under optimized design, the flat tungsten target and the compact target-moderator-reflector coupling enhance effective cold and thermal neutron output from moderators. Three wing-type moderators supply four different characteristics of neutrons to 19 beamlines primarily for neutron scattering applications. Layout of neutron instruments are conceptually planned for total 20 beamlines, the configuration and specification have been determined for three day-one neutron instruments. All designs are optimized for the Phase I of 100 kW with a upgradable capacity to 500 kW.

Wang, FangWei; Liang, TianJiao; Yin, Wen; Yu, QuanZhi; He, LunHua; Tao, JuZhou; Zhu, Tao; Jia, XueJun; Zhang, ShaoYing

2013-12-01

175

Accelerator-driven neutron sources for materials research  

SciTech Connect

Particle accelerators are important tools for materials research and production. Advances in high-intensity linear accelerator technology make it possible to consider enhanced neutron sources for fusion material studies or as a source of spallation neutrons. Energy variability, uniformity of target dose distribution, target bombardment from multiple directions, time-scheduled dose patterns, and other features can be provided, opening new experimental opportunities. New designs have also been used to ensure hands-on maintenance on the accelerator in these factory-type facilities. Designs suitable for proposals such as the Japanese Energy-Selective Intense Neutron Source, and the international Fusion Materials Irradiation Facility are discussed.

Jameson, R.A.

1990-01-01

176

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

177

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 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 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

178

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

179

Summary of alpha-neutron sources in GADRAS.  

SciTech Connect

A common source of neutrons for calibration and testing is alpha-neutron material, named for the alpha-neutron nuclear reaction that occurs within. This material contains a long-lived alpha-emitter and a lighter target element. When the alpha particle from the emitter is absorbed by the target, neutrons and gamma rays are released. Gamma Detector Response and Analysis Software (GADRAS) includes built-in alpha-neutron source definitions for AcC, AmB, AmBe, AmF, AmLi, CmC, and PuC. In addition, GADRAS users may create their own alpha-neutron sources by placing valid alpha-emitters and target elements in materials within their one-dimensional models (1DModel). GADRAS has the ability to use pre-built alpha-neutron sources for plotting or as trace-sources in 1D models. In addition, if any material (existing or user-defined) specified in a 1D model contains both an alpha emitter in conjunction with a target nuclide, or there is an interface between such materials, then the appropriate neutron-emission rate from the alpha-neutron reaction will be computed. The gamma-emissions from these sources are also computed, but are limited to a subset of nine target nuclides. If a user has experimental data to contribute to the alpha-neutron gamma emission database, it may be added directly or submitted to the GADRAS developers for inclusion. The gadras.exe.config file will be replaced when GADRAS updates are installed, so sending the information to the GADRAS developers is the preferred method for updating the database. This is also preferable because it enables other users to benefit from your efforts.

Mitchell, Dean James; Thoreson, Gregory G.; Harding, Lee T.

2012-05-01

180

Residual stress measurement using the pulsed neutron source at LANSCE  

Microsoft Academic Search

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can make spatially resolved non-destructive strain measurements in the interior of components. By recording the change in the crystalline interplanar spacing, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all

M. A. M. Bourke; J. A. Goldstone; T. M. Holden

1991-01-01

181

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

182

Some experiments on ultrasonic cavitation using a pulsed neutron source  

Microsoft Academic Search

Experiments on the prompt neutron-induced cavitation effect in tetrachloroethylene are described. Cavitation bubbles were detected by the fast acoustic signals they emit, probably during the collapse phase. Using a pulsed fast-neutron source phase locked to the acoustic field, and a time analyser, information was obtained on the history of bubbles which were nucleated at a known phase of the sound

R. Howlett

1968-01-01

183

Materials compatibility studies for the Spallation Neutron Source.  

National Technical Information Service (NTIS)

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...

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

1998-01-01

184

Conceptual design studies of GDT-based neutron source  

Microsoft Academic Search

An analysis shows that the existing nuclear technology data bases are not sufficient to arrive at a DEMO with reasonable confidence in achieving target availability levels. In order to provide these data, a testing facility capable of simulating neutron environment in a fusion reactor is needed. A number of proposals for plasma-type neutron sources have been made recently to meet

A. A. Ivanov; E. P. Kruglyakov; Yu. A. Tsidulko; V. G. Krasnoperovt; V. V. Korshakovt

1995-01-01

185

Phase contrast neutron imaging at a medium intensity neutron source  

Microsoft Academic Search

Neutron Imaging is a technique for the nondestructive testing (NDT) of materials. It is characterized by its sensitivity to materials composed of low atomic number (Z) elements such as hydrogen. Enhancement of the spatial resolution and the contrast of the obtained images are primary objectives that are continuously being pursued in the development of this technique. An approach of improving

Kaushal K. Mishra; Ayman I. Hawari

2009-01-01

186

Coded source neutron imaging with a MURA mask  

NASA Astrophysics Data System (ADS)

In coded source neutron imaging the single aperture commonly used in neutron radiography is replaced with a coded mask. Using a coded source can improve the neutron flux at the sample plane when a very high L/ D ratio is needed. The coded source imaging is a possible way to reduce the exposure time to get a neutron image with very high L/ D ratio. A 1717 modified uniformly redundant array coded source was tested in this work. There are 144 holes of 0.8 mm diameter on the coded source. The neutron flux from the coded source is as high as from a single 9.6 mm aperture, while its effective L/ D is the same as in the case of a 0.8 mm aperture. The Richardson-Lucy maximum likelihood algorithm was used for image reconstruction. Compared to an in-line phase contrast neutron image taken with a 1 mm aperture, it takes much less time for the coded source to get an image of similar quality.

Zou, Y. B.; Schillinger, B.; Wang, S.; Zhang, X. S.; Guo, Z. Y.; Lu, Y. R.

2011-09-01

187

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

188

Fast-Neutron Source Based on Plasma-Focus Device  

SciTech Connect

This paper describes investigations of neutrons produced by small plasma focus device PF-6 operating in the Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland. Main parameters of neutron radiation have been measured by scintillation probe, and by activation technique. Current derivative probe has also been applied to measure dI/dt signal. Simultaneously neutron transport calculations have been carried out by Monte Carlo method. Finally, experimental measurements and numerical calculations have allowed concluding that plasma focus devices can be useful pulse neutron sources for different applications.

Scholz, M.; Bienkowska, B.; Chernyshova, M.; Gribkov, V. A.; Jednorog, S.; Kalinowska, Z.; Karpinski, L.; Paduch, M.; Prokopowicz, R. [Institute of Plasma Physics and Laser Microfusion (IPPLM), 23 Hery Str., 01-497 Warsaw (Poland); Szydlowski, A. [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland)

2008-03-19

189

Neutron sources for investigations on extracted beams in Russia  

SciTech Connect

An overview is presented of the current status and prospects for the development of neutron sources intended for investigations on extracted beams in Russia. The participation of Russia in international scientific organizations is demonstrated.

Aksenov, V. L. [Russian Research Centre 'Kurchatov Institute' (Russian Federation)], E-mail: Aksenov@kiae.ru

2007-05-15

190

Recovery of plutonium from plutonium-beryllium neutron sources.  

National Technical Information Service (NTIS)

At the Los Alamos National Laboratory, plutonium-beryllium neutron sources have traditionally been processed for plutonium recovery by precipitating the plutonium as plutonium oxalate, calcining to plutonium dioxide, redissolving the oxide and then precip...

M. J. Palmer

1990-01-01

191

Tokamak Fusion Neutron Source Requirements for Nuclear Applications  

Microsoft Academic Search

The potential near-term role for fusion in closing the nuclear fuel cycle was examined in a series of design studies for sub-critical fast transmutation reactors driven by tokamak fusion neutron sources.

W. M. Stacey

192

Gasdynamic Measurements for the LASL Intense Neutron Source.  

National Technical Information Service (NTIS)

Measurements made on a two-dimensional simulation of the Los Alamos Scientific Laboratory (LASL) Intense Neutron Source (INS) experiment are discussed. The purpose of this work was to characterize the supersonic INS channel flow under conditions of large ...

S. C. Johnston

1978-01-01

193

Parameter Optimization Studies for a Tandem Mirror Neutron Source  

NASA Astrophysics Data System (ADS)

A basic plasma physics tandem mirror experiment is proposed to develop the potential uses of magnetic mirror confined plasmas for a neutron source. We consider parameter variations from the currently operating symmetric mirror plasma trap GDT in an attempt to optimize the neutron source intensity while minimizing the expense and complications of the system. The combined radial and axial plasma loss rates are analyzed and shown to yield an optimal operational point that minimizes the required auxiliary heating power.

Horton, W.; Fu, X. R.; Ivanov, A.; Beklemishev, A.

2010-12-01

194

High-power LINAC for the spallation neutron source  

Microsoft Academic Search

The Spallation Neutron Source is a $1.4B project for the U.S. Dept. of Energy to develop the world's most intense source of neutrons for fundamental science and industrial applications. Design and construction of this facility, located at Oak Ridge, is a joint venture between six DOE laboratories. Construction began in 1999 and is currently ahead of the scheduled 2006 completion

D. J. Rej

2001-01-01

195

The IECA plasma-target-based neutron source  

Microsoft Academic Search

In the inertial electrostatic confinement (IEC) device, deuteron ions are accelerated, producing fusion reactions as they react with a deuterium plasma target. Present devices offer 106107 2.5 MeV D-D n s?1 during steady-state operation. Higher yield pulsed versions are under development. Consequently the IEC neutron source is currently competitive, in terms of neutron strength, with Cf-252 and accelerator solid-target sources

George H. Miley; John Sved

1997-01-01

196

Overview of target systems for the Spallation Neutron Source  

SciTech Connect

The purpose and requirements of target systems as well as the technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the Spallation Neutron Source (SNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis, and the planned hardware research and development program are also described.

Gabriel, T.A.; Barnes, J.M.; Charlton, L.A. [and others

1997-12-31

197

Secondary neutron source modelling using MCNPX and ALEPH codes  

NASA Astrophysics Data System (ADS)

Monitoring the subcritical state and divergence of reactors requires the presence of neutron sources. But mainly secondary neutrons from these sources feed the ex-core detectors (SRD, Source Range Detector) whose counting rate is correlated with the level of the subcriticality of reactor. In cycle 1, primary neutrons are provided by sources activated outside of the reactor (e.g. Cf252); part of this source can be used for the divergence of cycle 2 (not systematic). A second family of neutron sources is used for the second cycle: the spontaneous neutrons of actinides produced after irradiation of fuel in the first cycle. Both families of sources are not sufficient to efficiently monitor the divergence of the second cycles and following ones, in most reactors. Secondary sources cluster (SSC) fulfil this role. In the present case, the SSC [Sb, Be], after activation in the first cycle (production of Sb124, unstable), produces in subsequent cycles a photo-neutron source by gamma (from Sb124)-neutron (on Be9) reaction. This paper presents the model of the process between irradiation in cycle 1 and cycle 2 results for SRD counting rate at the beginning of cycle 2, using the MCNPX code and the depletion chain ALEPH-V1 (coupling of MCNPX and ORIGEN codes). The results of this simulation are compared with two experimental results of the PWR 1450 MWe-N4 reactors. A good agreement is observed between these results and the simulations. The subcriticality of the reactors is about at -15,000 pcm. Discrepancies on the SRD counting rate between calculations and measurements are in the order of 10%, lower than the combined uncertainty of measurements and code simulation. This comparison validates the AREVA methodology, which allows having an SRD counting rate best-estimate for cycles 2 and next ones and optimizing the position of the SSC, depending on the geographic location of sources, main parameter for optimal monitoring of subcritical states.

Trakas, Christos; Kerkar, Nordine

2014-06-01

198

LENSa 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

199

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

200

Design and demonstration of a quasi-monoenergetic neutron source  

NASA Astrophysics Data System (ADS)

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 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.

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

2014-08-01

201

Application of a triga research reactor as the neutron source for a production neutron radiography facility  

Microsoft Academic Search

GA Technologies Inc. (GA) has developed a Stationary Neutron Radiography System (SNRS) using a 250-1000 kW TRIGA reactor as the neutron source. The partially below ground reactor will be equipped with four vertical beam tubes originating in the reactor graphite reflector and installed tangential to the core to provide a strong current of thermal neutrons with minimum gamma-ray contamination. The

Chesworth

1988-01-01

202

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

203

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

204

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.; Hernndez-Dvila, V. M.; Rivera, T.; Snchez, A.

2014-02-01

205

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

SciTech Connect

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, setup, and test a cold-neutron PGAA system which utilizes the guided focused cold neutron beam. During the first year of the DOE grant, a new procedure was developed and used to design a focusing converging guide consisting of truncated rectangular cone sections. Detailed calculations were performed using a 3-D Monte Carlo code which the authors wrote to trace neutrons through the curved guide of the TCNS into the proposed converging guide. Using realistic reflectivities for Ni-Ti supermirrors, the authors obtained gains of 3 to 5 for 4 different converging guide geometries. During the second year of the DOE grant, the subject of this final report, Ovonic Synthetic Materials Company was contracted to build a converging neutron guide focusing system to the specifications. Considerable time and effort were spent working with Ovonics on selecting the materials for the converging neutron guide system. The major portion of the research on the design of a cold-neutron PGAA system was also completed during the second year. At the beginning of the third year of the grant, a converging neutron guide focusing system had been ordered, and a cold-neutron PGAA system had been designed. Since DOE did not fund the third year, there was no money to purchase the required equipment for the cold-neutron PGAA system and no money to perform tests of either the converging neutron guide or the cold-neutron PGAA system. The research already accomplished would have little value without testing the systems which had been designed. Thus the project was continued at a pace that could be sustained with internal funding.

Wehring, B.W.; Uenlue, K.

1996-12-19

206

Efficiency calibration of a large-area neutron detector by using Am\\/Be neutron source  

Microsoft Academic Search

Neutron detection efficiency for a long wedge-shaped plastic scintillation detector was measured by using the Am\\/Be neutron source. The overall efficiency attains 23% at around 2 MeV and decreases to 15% at about 5 MeV. The experimental results are in agreement with the Monte Carlo simulation calculations.

Q. Y. Hu; Y. L. Ye; Z. H. Li; X. Q. Li; D. X. Jiang; T. Zheng; Q. J. Wang; H. Hua; C. E. Wu; Z. Q. Chen; J. Ying; D. Y. Pang; G. L. Zhang; J. Wang

2005-01-01

207

Research on IEC - a plasma-target-based neutron source  

SciTech Connect

Inertial electrostatic confinement (IEC) offers a unique plasma target neutron source. Deuteron ions are accelerated, producing fusion reactions as they react with a deuterium plasma target. Current devices offer 10{sup 6} to 10{sup 7} 2.5-MeV deuterium-deuterium (D-D) n/s during steady-state operation. Conversion to higher energy (14-MeV) neutrons by substituting deuterium-tritium (D-T) fill gas gives 10{sup 8} to 10{sup 9} D-T n/s. Higher yield (> 10{sup 9} D-D n/s time averaged) pulsed versions are under development. Consequently, the IEC neutron source is currently competitive, in neutron strength, with {sup 252}Cf and with small accelerator solid-target sources. Further, it offers a number of advantages, including an on-off capability, long lifetime (avoiding target deterioration or radioactive decay), and minimum radioactivity involvement. These features simplify IEC usage and ease licensing restrictions. For these reasons, the IEC provides an excellent laboratory neutron source and an attractive, cost-efficient industrial source for neutron activation analysis and nondestructive testing.

Miley, G.H.; Gu, Y.; Stubbers, R. [Univ. of Illinois, Urbana-Champaign, IL (United States)] [and others

1997-12-01

208

Development of an ultra cold neutron source at MLNSC  

SciTech Connect

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 in UCN density should be possible using cryogenic UCN sources. Research is under way at Gatchina to demonstrate technical feasibility of a frozen deuterium source. If successful, a source of this type could be implemented at future spallation sources, such as the long pulse source being planned at Los Alamos, with a UCN density that may be two orders of magnitude higher than that presently available at reactors.

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

1996-09-01

209

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

210

Thermal neutron source imager using coded apertures.  

National Technical Information Service (NTIS)

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 neutron...

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

1995-01-01

211

GEM-based thermal neutron beam monitors for spallation sources  

NASA Astrophysics Data System (ADS)

The development of new large area and high flux thermal neutron detectors for future neutron spallation sources, like the European Spallation Source (ESS) is motivated by the problem of 3He shortage. In the framework of the development of ESS, GEM (Gas Electron Multiplier) is one of the detector technologies that are being explored as thermal neutron sensors. A first prototype of GEM-based thermal neutron beam monitor (bGEM) has been built during 2012. The bGEM is a triple GEM gaseous detector equipped with an aluminum cathode coated by 1?m thick B4C layer used to convert thermal neutrons to charged particles through the 10B(n,7Li)? nuclear reaction. This paper describes the results obtained by testing a bGEM detector at the ISIS spallation source on the VESUVIO beamline. Beam profiles (FWHMx=31 mm and FWHMy=36 mm), bGEM thermal neutron counting efficiency (?1%), detector stability (3.45%) and the time-of-flight spectrum of the beam were successfully measured. This prototype represents the first step towards the development of thermal neutrons detectors with efficiency larger than 50% as alternatives to 3He-based gaseous detectors.

Croci, G.; Claps, G.; Caniello, R.; Cazzaniga, C.; Grosso, G.; Murtas, F.; Tardocchi, M.; Vassallo, E.; Gorini, G.; Horstmann, C.; Kampmann, R.; Nowak, G.; Stoermer, M.

2013-12-01

212

A Detector for 2-D Neutron Imaging for the Spallation Neutron Source  

SciTech Connect

Abstract - We have designed, built, and tested a 2-D pixellated thermal neutron detector. The detector is modeled after the MicroMegas-type structure previously published for collider-type experiments. The detector consists of a 4X4 square array of 1 cm 2 pixels each of which is connected to an individual preamplifier-shaper-data acquisition system. The neutron converter is a 10B film on an aluminum substrate. We describe the construction of the detector and the test results utilizing 252Cf sources in Lucite to thermalize the neutrons.Drift electrode (Aluminum) Converter (10B) 3 mm Conversion gap neutron (-900 V)

Britton Jr, Charles L [ORNL; Bryan, W. L. [Oak Ridge National Laboratory (ORNL); Wintenberg, Alan Lee [ORNL; Clonts, Lloyd G [ORNL; Warmack, Robert J Bruce [ORNL; McKnight, Timothy E [ORNL; Frank, Steven Shane [ORNL; Cooper, Ronald G [ORNL; Dudney, Nancy J [ORNL; Veith, Gabriel M [ORNL

2006-01-01

213

Data acquisition system for the neutron scattering instruments at the intense pulsed neutron source  

SciTech Connect

The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a major new user-oriented facility which is now coming on line for basic research in neutron scattering and neutron radiation damage. This paper describes the data-acquisition system which will handle data acquisition and instrument control for the time-of-flight neutron-scattering instruments at IPNS. This discussion covers the scientific and operational requirements for this system, and the system architecture that was chosen to satisfy these requirements. It also provides an overview of the current system implementation including brief descriptions of the hardware and software which have been developed.

Crawford, R.K.; Daly, R.T.; Haumann, J.R.; Hitterman, R.L.; Morgan, C.B.; Ostrowski, G.E.; Worlton, T.G.

1981-01-01

214

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

215

Proposal for muon and white neutron sources at CSNS  

NASA Astrophysics Data System (ADS)

The China Spallation Neutron Source (CSNS) is a large scientific facility with the main purpose of serving multidisciplinary research on material characterization using neutron scattering techniques. The accelerator system is to provide a proton beam of 120 kW with a repetition rate of 25 Hz initially (CSNS-I), progressively upgradeable to 240 kW (CSNS-II) and 500 kW (CSNS-II'). In addition to serving as a driving source for the spallation target, the proton beam can be exploited for serving additional functions both in fundamental and applied research. The expanded scientific application based on pulsed muons and fast neutrons is especially attractive in the overall consideration of CSNS upgrade options. A second target station that houses a muon-generating target and a fast-neutron-generating target in tandem, intercepting and removing a small part of the proton beam for the spallation target, is proposed. The muon and white neutron sources are operated principally in parasitic mode, leaving the main part of the beam directed to the spallation target. However, it is also possible to deliver the proton beam to the second target station in a dedicated mode for some special applications. Within the dual target configuration, the thin muon target placed upstream of the fast-neutron target will consume only about 5% of the beam traversed; the majority of the beam is used for fast-neutron production. A proton beam with a beam power of about 60 kW, an energy of 1.6 GeV and a repetition rate of 12.5 Hz will make the muon source and the white neutron source very attractive to multidisciplinary researchers.

Tang, Jing-Yu; Fu, Shi-Nian; Jing, Han-Tao; Tang, Hong-Qing; Wei, Jie; Xia, Hai-Hong

2010-01-01

216

Neutron powder diffraction at a pulsed neutron source: a study of resolution effects  

Microsoft Academic Search

The General Purpose Powder Diffractometer (GPPD), a high resolution ( d\\/d = 0.002) time-of-flight instrument, exhibits a resolution function that is almost independent of d-spacing. Some of the special properties of time-of-flight scattering data obtained at a pulsed neutron source will be discussed. A method is described that transforms wavelength dependent data, obtained at a pulsed neutron source, so that

J. Jr. Faber; R. L. Hitterman

1985-01-01

217

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

218

Neutron field measurements at the Aladdin Synchrotron Light Source  

SciTech Connect

The neutron field near the inflector of the 800-MeV electron storage ring was studied. Photon-induced neutrons are produced by 100-MeV electrons bombarding the inflector during injection into the synchrotron ring. Neutrons were measured with moderating detectors made of 15 X 15 X 20 cm Lucite blocks and Au activation foils. Detector response was established with a Pu-Be neutron source and a 25.4-cm polyethylene sphere and Au foil detector. The neutron yield was 0.97 +/- 0.14 X 10(12) kJ-1. For 1.38 W of electron pulse power, the dose equivalent rate 1 m aside and 1 m above the inflector was 4.35 +/- 0.47 mu Sv s-1 and 3.13 +/- 0.23 mu Sv s-1, respectively. A measured dose equivalent transmission curve for polyethylene yielded an attenuation coefficient of 15.7 m-1.

Yang, Y.; Li, Y.X.; DeLuca, P.M. Jr.; Otte, R.; Rowe, E.M.

1986-01-01

219

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

220

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

221

High output neutron tube using an occluded gas ion source  

SciTech Connect

A neutron tube capable of generating 10/sup 10/ 14 MeV neutrons in a 1.2 ms pulse has been developed for the Nuclear Regulatory Commission for use in flow measurements using the Pulsed Neutron Activation technique. The tube consists of an occluded deuterium gas ion source, a single gap accelerator and a scandium tritide target. A unique feature of the tube design is its complete demountability, permitting easy replacement or modification of critical components. The ion source is a modified version of a stacked occluded washer source. However, in contrast to previous designs, this source utilizes only a single scandium deuteride washer and needs no independent trigger. Outputs of 1.2 x 10/sup 10/ neutrons per pulse from a 250 mA deuterium ion beam at 125 kV have been obtained for over 1500 consecutive operations with a standard deviation of only +- 5%. The ultimate operational lifetime is believed to be in excess of 3000 shots based on the present knowledge of ion source behavior. Recent experiments using nonmagnetic structural components in the ion source resulted in a 26% increase in output with a simultaneous 35% reduction in the source drive current. This implies that even higher outputs with greater source efficiencies may be achievable.

Walko, R.J.; Rochau, G.E.

1980-01-01

222

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

223

BNL Activities in Advanced Neutron Source Development: Past and Present  

SciTech Connect

Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In this report we discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

Hastings, J.B.; Ludewig, H.; Montanez, P.; Todosow, M.; Smith, G.C.; Larese, J.Z.

1998-06-14

224

BNL ACTIVITIES IN ADVANCED NEUTRON SOURCE DEVELOPMENT: PAST AND PRESENT  

SciTech Connect

Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In the sections below the authors discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

HASTINGS,J.B.; LUDEWIG,H.; MONTANEZ,P.; TODOSOW,M.; SMITH,G.C.; LARESE,J.Z.

1998-06-14

225

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

226

Beam dump window design for the Spallation Neutron Source  

Microsoft Academic Search

The Spallation Neutron Source accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. Beam tuning dumps are provided at the end of the linac (the Linac Dump) and in the Ring-to-Target transport line (the Extraction Dump). Thin windows are required to separate the accelerator vacuum from the poor vacuum upstream

G. Murdoch; A. Decarlo; S. Henderson; S. Kim; K. Potter; T. Roseberry; J. Rank; D. Raparia

2003-01-01

227

Plasma based 14 MeV neutron sources  

Microsoft Academic Search

The utmost urgency to develop powerful 14 MeV neutron sources is now well understood among fusion community of engineers and material scientists. The time of influence of 14 MeV neutrons upon the fusion reactor components is estimated at 1020 years and corresponds to a fluence of 1.54.5 1022 n\\/cm2. As yet, no reliable data are available on the behavior of

E. P. Kruglyakov

1995-01-01

228

The Spallation Neutron Source: A Powerful Tool for Materials Research  

SciTech Connect

The wavelengths and energies of thermal and cold neutrons are ideally matched to the length and energy scales in the materials that underpin technologies of the present and future: ranging from semiconductors to magnetic devices, composites to biomaterials and polymers. The Spallation Neutron Source will use an accelerator to produce the most intense beams of neutrons in the world when it is complete in 2006. The project is being built by a collaboration of six U.S. Department of Energy laboratories. It will serve a diverse community of users drawn from academia, industry, and government labs with interests in condensed matter physics, chemistry, engineering materials, biology, and beyond.

Mason, T.E.; Abernathy, D.; Ankner, J.; Ekkebus, A.; Granroth, G.; Hagen, M.; Herwig, K.; Hoffmann, C.; Horak, C.; Klose, F.; Miller, S.; Neuefeind, J.; Tulk, C.; Wang, X.-L. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge TN 37830 (United States)

2005-06-08

229

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

230

Design considerations for neutron activation and neutron source strength monitors for ITER  

SciTech Connect

The International Thermonuclear Experimental Reactor will require highly accurate measurements of fusion power production in time, space, and energy. Spectrometers in the neutron camera could do it all, but experience has taught us that multiple methods with redundancy and complementary uncertainties are needed. Previously, conceptual designs have been presented for time-integrated neutron activation and time-dependent neutron source strength monitors, both of which will be important parts of the integrated suite of neutron diagnostics for this purpose. The primary goals of the neutron activation system are: to maintain a robust relative measure of fusion energy production with stability and wide dynamic range; to enable an accurate absolute calibration of fusion power using neutronic techniques as successfully demonstrated on JET and TFTR; and to provide a flexible system for materials testing. The greatest difficulty is that the irradiation locations need to be close to plasma with a wide field of view. The routing of the pneumatic system is difficult because of minimum radius of curvature requirements and because of the careful need for containment of the tritium and activated air. The neutron source strength system needs to provide real-time source strength vs. time with {approximately}1 ms resolution and wide dynamic range in a robust and reliable manner with the capability to be absolutely calibrated by in-situ neutron sources as done on TFTR, JT-60U, and JET. In this paper a more detailed look at the expected neutron flux field around ITER is folded into a more complete design of the fission chamber system.

Barnes, C.W. [Los Alamos National Lab., NM (United States); Jassby, D.L.; LeMunyan, G.; Roquemore, A.L. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Walker, C. [ITER Joint Central Team, Garching (Germany)

1997-12-31

231

A high-fluence fusion neutron source  

SciTech Connect

A conceptual design of a D-T fusion facility for continuous production of 14-MeV neutron wall loading from 5 to 10 MW/m/sup 2/ at the plasma surface is presented. In this design, D-T neutrons are produced in a linear, two-component plasma formed by neutral beam irradiation of a fully ionized warm plasma target. The beam energy, which is deposited in the center, is transferred to the warm plasma mainly by electron drag and is conducted along the target plasma column to end regions where it is absorbed in neutral gas at high pressure. The target plasma is operated in a regime where electron thermal conduction along the column is the controlling energy-loss process. The loss rate is minimized by adjusting the diameter and length of the plasma column. A substantial gradient in T/sub e/ along the column results in recombination of the plasma to gas in the end-regions before impact on the end walls. The resultant hot gas is cooled by contact with large-area heat exchangers. In this way, the large steady-state heat load from the injected neutral beams is diffused and removed at tolerable heat flux levels. The reacting plasma is essentially an extrapolation of the 2XIIB high-..beta.. plasma to higher magnetic field, ion energy, and density. 12 refs., 4 figs.

Coensgen, F.H.; Casper, T.A.; Correll, D.L.; Damm, C.C.; Futch, A.H.; Logan, B.G.; Molvik, A.W.; Bulmer, R.H.

1988-02-17

232

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

233

Neutronic analysis of a liquid-4He source for ultra-cold neutron production and storage  

NASA Astrophysics Data System (ADS)

Ultra-cold neutron (UCN) production and storage in a liquid-4He source are evaluated by means of multi-group neutron-transport analysis. Using the cross-section model developed by the authors, a set of group constants for liquid 4He at many different temperatures down to 0.1K is generated. Major results thus obtained are as follows. As the temperature is decreased below about 0.5K, the UCN density shows a saturation behavior because of no significant up-scattering and UCN loss by neutron ?-decay only. Single down-scattering of a 1-meV neutron and also multiple scattering of a higher-energy neutron contribute largely to UCN production. A high UCN density of 1105 cm-3 is possible with a high reflectivity of a storage vessel, say over 0.9999.

Abe, Y.; Morishima, N.

234

Proton Driver Linac for the Frankfurt Neutron Source  

NASA Astrophysics Data System (ADS)

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? BaF2 detector array. The design of the proton driver linac for both operation modes is presented. This includes the volume type ion source, the EB 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.; Mder, D.; Metz, A.; Meusel, O.; Mller, I.; Noll, D.; Podlech, H.; Ratzinger, U.; Reichau, H.; Reifarth, R.; Schempp, A.; Schmidt, S.; Schweizer, W.; Volk, K.; Wagner, C.

2010-08-01

235

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

236

Characterization and evaluation of a modified local lymph node assay using ATP content as a non-radio isotopic endpoint  

Microsoft Academic Search

Introduction: The murine local lymph node assay (LLNA) is an accepted and widely used method for assessing the skin-sensitizing potential of chemicals. Here, we describe a non-radio isotopic modified LLNA in which adenosine triphosphate (ATP) content is used as an endpoint instead of radioisotope (RI); the method is termed LLNA modified by Daicel based on ATP content (LLNA-DA). Methods: Groups

Kenji Idehara; Gaku Yamagishi; Kunihiko Yamashita; Michio Ito

2008-01-01

237

Development and study of a portable plasma focus neutron source  

NASA Astrophysics Data System (ADS)

The work is devoted to designing a compact pulsed neutron source on the basis of a plasma focus (PF) discharge. The main task was to study the physical processes accompanying a sub-kilojoule repetitive PF discharge. A device with a power supply energy of up to 600 J and pulse repetition rate of up to 10 Hz has been developed and put into operation. The dependence of the neutron yield as a function of the pulse repetition rate has been studied experimentally. A neutron flux of 108 neutrons/s has been obtained in the 3-s-long packet mode with a repetition rate of 10 Hz and discharge current of 80-90 kA.

Vinogradov, V. P.; Nashilevskii, A. V.; Krauz, V. I.; Remnev, G. E.; Vinogradova, Yu. V.; Kanaev, G. G.; Mitrofanov, K. N.; Myalton, V. V.

2014-02-01

238

Separation of beam and electrons in the spallation neutron source H(sup -) ion source.  

National Technical Information Service (NTIS)

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 a...

J. H. Whealton R. J. Raridon K. N. Leung

1997-01-01

239

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

240

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

241

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 Universitt Mnchen, 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

242

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

243

Neutron source investigations in support of the cross section program at the Argonne Fast-Neutron Generator  

Microsoft Academic Search

Experimental methods related to the production of neutrons for cross section studies at the Argonne Fast-Neutron Generator are reviewed. Target assemblies commonly employed in these measurements are described, and some of the relevant physical properties of the neutron source reactions are discussed. Various measurements have been performed to ascertain knowledge about these source reaction that is required for cross section

J. W. Meadows; D. L. Smith

1980-01-01

244

Effect of Fusion Neutron Source Numerical Models on Neutron Wall Loading in a D-D Tokamak Device  

Microsoft Academic Search

Effect of various spatial and energy distributions of fusion neutron source on the calculation of neutron wall loading of Tokamak D-D fusion device has been investigated by means of the 3-D Monte Carlo code MCNP. A realistic Monte Carlo source model was developed based on the accurate representation of the spatial distribution and energy spectrum of fusion neutrons to solve

Yi-xue Chen; Yi-can Wu

2003-01-01

245

Neutron Radiographic Inspection of Industrial Components using Kamini Neutron Source Facility  

SciTech Connect

Kamini (Kalpakkam Mini) reactor is a U{sup 233} fuelled, demineralised light water moderated and cooled, beryllium oxide reflected, low power (30 kW) nuclear research reactor. This reactor functions as a neutron source with a flux of 10{sup 12} n/cm{sup 2} s{sup -1} at core centre with facilitates for carrying out neutron radiography, neutron activation analysis and neutron shielding experiments. There are two beam tubes for neutron radiography. The length/diameter ratio of the collimators is about 160 and the aperture size is 220 mmx70 mm. Flux at the outer end of the beam tube is {approx}10{sup 6}-10{sup 7} n/cm{sup 2} s. The north end beam tube is for radiography of inactive object while the south side beam tube is for radiography of radioactive objects. The availability of high neutron flux coupled with good collimated beam provides high quality radiographs with short exposure time. The reactor being a unique national facility for neutron radiography has been utilized in the examination of irradiated components, aero engine turbine blades, riveted plates, automobile chain links and for various types of pyro devices used in the space programme. In this paper, an overview of the salient features of this reactor facility for neutron radiography and our experience in the inspection of a variety of industrial components will be given.

Raghu, N.; Anandaraj, V.; Kasiviswanathan, K. V.; Kalyanasundaram, P. [Indira Gandhi Center for Atomic Research, Kalpakkam-603 102 (India)

2008-03-17

246

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

247

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

248

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

249

Accelerator shield design of KIPT neutron source facility  

SciTech Connect

Argonne National Laboratory (ANL) of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of a neutron source facility at KIPT utilizing an electron-accelerator-driven subcritical assembly. Electron beam power is 100 kW, using 100 MeV electrons. The facility is designed to perform basic and applied nuclear research, produce medical isotopes, and train young nuclear specialists. The biological shield of the accelerator building is designed to reduce the biological dose to less than 0.5-mrem/hr during operation. The main source of the biological dose is the photons and the neutrons generated by interactions of leaked electrons from the electron gun and accelerator sections with the surrounding concrete and accelerator materials. The Monte Carlo code MCNPX serves as the calculation tool for the shield design, due to its capability to transport electrons, photons, and neutrons coupled problems. The direct photon dose can be tallied by MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is less than 0.01 neutron per electron. This causes difficulties for Monte Carlo analyses and consumes tremendous computation time for tallying with acceptable statistics the neutron dose outside the shield boundary. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were developed for the study. The generated neutrons are banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron and secondary photon doses. The weight windows variance reduction technique is utilized for both neutron and photon dose calculations. Two shielding materials, i.e., heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total dose outside the shield boundary at less than 0.5-mrem/hr. The shield configuration and parameters of the accelerator building have been determined and are presented in this paper. (authors)

Zhong, Z.; Gohar, Y. [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)] [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)

2013-07-01

250

Operation of the Superconducting Linac at the Spallation Neutron Source  

Microsoft Academic Search

At the Spallation Neutron Source, the first fully operational pulsed superconducting linac has been active for about two years. During this period, stable beam operation at 4.4 K has been achieved with beam for repetition rates up to 15 Hz and 30 Hz at 2.1 K. At the lower temperature 60 Hz RF pulses have been also used. Full beam

Isidoro E Campisi; Fabio Casagrande; Mark S Champion; M. Crofford; M. Howell; Y. Kang; S. H. Kim; Z. Kursun; P. Ladd; D. Stout; W. Strong

2008-01-01

251

OPERATION OF THE SUPERCONDUCTING LINAC AT THE SPALLATION NEUTRON SOURCE  

Microsoft Academic Search

At the Spallation Neutron Source, the first fully operational pulsed superconducting linac has been active for about two years. During this period, stable beam operation at 4.4 K has been achieved with beam for repetition rates up to 15 Hz and 30 Hz at 2.1 K. At the lower temperature 60 Hz RF pulses have been also used. Full beam

Isidoro E Campisi; Fabio Casagrande; Mark Champion; Mark T Crofford; Matthew P Howell; Yoon W Kang; Sang-Ho Kim; Zafer Kursun; Peter Ladd; Daniel S Stout; William Herb Strong

2007-01-01

252

R&D for the Spallation Neutron Source mercury target  

Microsoft Academic Search

An overview of the research and development program for the Spallation Neutron Source (SNS) is presented. The materials-related efforts in target development are emphasized in order to provide a perspective for a number of specialized papers that are included in these proceedings. We give a brief introduction and historical sketch of the SNS project. Part of the materials R&D consists

L. K Mansur; T. A Gabriel; J. R Haines; D. C Lousteau

2001-01-01

253

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

254

Application of Fusion Neutron Source for Denaturing of Plutonium  

Microsoft Academic Search

Potential of DT fusion neutron source to enhance proliferation resistance properties of plutonium by means of its isotopic denaturing is addressed. The approach is exemplified by denaturing of pure Pu and plutonium of typical LWR spent fuel through transmutation of neptunium. The essential feature of a fusion driven system proposed in the study is a zero mass balance of plutonium:

Alan TAKIBAYEV; Masaki SAITO; Hiroshi SAGARA

2007-01-01

255

Flow blockage analysis for the advanced neutron source reactor.  

National Technical Information Service (NTIS)

The Advanced Neutron Source (ANS) reactor was designed to provide a research tool with capabilities beyond those of any existing reactors. One portion of its state-of-the-art design required high-speed fluid flow through narrow channels between the fuel p...

T. K. Stovall J. A. Crabtree D. K. Felde J. E. Park

1996-01-01

256

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2010 CFR

(a) Use of a tritium neutron generator target source, containing quantities not exceeding 1,110 GBg [30 curies] and in a well with a surface casing to protect fresh water aquifers, is subject to the requirements of this part except §§ 39.15, 39.41, and...

2009-01-01

257

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2010 CFR

(a) Use of a tritium neutron generator target source, containing quantities not exceeding 1,110 GBg [30 curies] and in a well with a surface casing to protect fresh water aquifers, is subject to the requirements of this part except §§ 39.15, 39.41, and...

2010-01-01

258

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

259

?CF based 14 MeV intense neutron source  

NASA Astrophysics Data System (ADS)

Results of a design study for an advanced scheme of a ?CF based 14 MeV intense neutron source for test material irradiation including the liquid lithium primary target and a low temperature liquid deuterium-tritium (D-T) mixture as a secondary target are presented. According to this scheme negative pions are produced inside a 150-cm-long 0.75-cm-radius lithium target. Pions and muons resulting from the pion decay in flight are collected in the backward direction and stopped in the D-T mixture. The fusion chamber has the shape of a 10-cm-radius sphere surrounded by two 0.03-cm-thickness titanium shells. Assuming 100 fusions per muon in this scheme one can produce 14-MeV neutrons with a source strength up to 1017 n/s. A neutron flux of up to 1014 n/cm2/s can be achieved in a test volume of about 2.5 l and on the surface of about 350 cm2. The results of the thermophysical and thermomechanical analysis show that the technological limits are not exceeded. This source has the advantage of producing the original 14 MeV fusion spectrum without tails, isotropically into a 4? solid angle, contrary to the d-Li stripping neutron source.

Anisimov, V. V.; Cavalleri, E.; Karmanov, F. I.; Konobeyev, A. Yu.; Latysheva, L. N.; Ponomarev, L. I.; Pshenichnov, I. A.; Slobodtchouk, V. I.; Vecchi, M.

1999-06-01

260

Intense neutron source: high-voltage power supply specifications  

SciTech Connect

This report explains the need for and sets forth the electrical, mechanical and safety specifications for a high-voltage power supply to be used with the intense neutron source. It contains sufficient information for a supplier to bid on such a power supply.

Riedel, A.A.

1980-08-01

261

The RF system design for the Spallation Neutron Source  

Microsoft Academic Search

Spallation Neutron Source (SNS) accelerator includes a nominally 1000 MeV, 2 mA average current linac consisting of a radio frequency quadrupole (RFQ), drift tube linac (DTL), coupled cavity linac (CCL), a medium and high beta superconducting (SC) linac, and two buncher cavities for beam transport to the ring. Los Alamos is responsible for the RF systems for all sections of

D. Rees; P. Tallerico; W. Roybal; K. Cummings; T. Hardek; J. Bradley; A. Regan

2001-01-01

262

Study of a spherical tokamak based volumetric neutron source  

Microsoft Academic Search

With the worldwide development of fusion power focusing on the design of the International Thermonuclear Experimental Reactor (ITER), developmental strategies for the demonstration fusion power plant (DEMO) are being discussed. A relatively prudent strategy is to construct and operate a small deuteriumtritium fuelled volumetric neutron source (VNS) in parallel with ITER. The VNS is to provide, over a period less

E. T. Cheng; Y. K. Martin Peng; Ralph Cerbone; Paul Fogarty; John D. Galambos; E. A. Mogahed; Brad Nelson; Massoud Simnad; Igor Sviatoslavsky; Mark Tillack

1998-01-01

263

Sub-Critical Transmutation Reactors with Tokamak Fusion Neutron Sources  

SciTech Connect

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.

Stacey, W.M. [Georgia Institute of Technology (United States); Mandrekas, J. [Georgia Institute of Technology (United States); Hoffman, E.A. [Argonne National Laboratory (United States)

2005-05-15

264

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

265

Advanced neutron source final preconceptual reference core design  

Microsoft Academic Search

The preconceptual design phase of the Advanced Neutron Source (ANS) Project ended with the selection of a reference reactor core that will be used to begin conceptual design work. The new reference core consists of two involute fuel elements, of different diameters, aligned axially with a small axial gap between them. The use of different element diameters permits a separate

G. L. Copeland; W. R. Gambill; R. M. Harrington; J. A. Johnson; F. J. Peretz; H. Reutler; J. M. Ryskamp; D. L. Selby; C. D. West; G. L. Yoder

1989-01-01

266

Creep analysis of fuel plates for the Advanced Neutron Source  

Microsoft Academic Search

The reactor for the planned Advanced Neutron Source will use closely spaced arrays of fuel plates. The plates are thin and will have a core containing enriched uranium silicide fuel clad in aluminum. The heat load caused by the nuclear reactions within the fuel plates will be removed by flowing high-velocity heavy water through narrow channels between the plates. However,

W. F. Swinson; G. T. Yahr

1994-01-01

267

Commissioning of the Spallation Neutron Source front end systems  

Microsoft Academic Search

The Front-End (FE) for the Spallation Neutron Source (SNS) accelerator system is a 2.5-MeV linac injector consisting of the following major subsystems, the rf-driven H-ion source, the electrostatic Low Energy Beam Transport line, a 402.5 MHz RFQ, the Medium Energy Beam Transport line, a beam chopper system and a suite of diagnostic devices. After construction and initial commissioning at LBNL

A. Aleksandrov

2003-01-01

268

THE SPALLATION NEUTRON SOURCE CRYOMODULE TEST STAND RF SYSTEM  

Microsoft Academic Search

The Spallation Neutron Source (SNS) has recently commissioned a cryomodule test facility for the repair and testing of the superconducting radio-frequency (SRF) cavities. This facility utilizes the original 402.5\\/805 MHz Radio Frequency (RF) Klystron Test Stand as its power source along with dual Low Level RF (LLRF) control systems. One control system is based on the standard SNS Linac LLRF

M. Crofford; J. Ball; T. Davidson; T. Hardek; D. Heidenreich; Y. Kang; K. Kasemir; S. H. Kim

269

Performance of the Intense Pulsed Neutron Source Accelerator System  

SciTech Connect

The performance of the Intense Pulsed Neutron Source (IPNS) Accelerator System is reported, including an increase in average beam current to 13.4 microamperes and increased reliability to 93.2%. Brief discussions are given for the performance of the major accelerator subsystems, including the H/sup -/ ion source and preaccelerator, the 50 MeV linac, and the synchrotron and its subsystems. (LEW)

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

1986-09-22

270

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

271

International workshop on plasma-based neutron sources  

SciTech Connect

The workshop was devoted to discussion of the status and future directions of work on plasma-based neutron sources. The workshop presentations demonstrated significant progress in development of the concepts of these sources and in broadening the required data base. Two main groups of neutron source designs were presented at the workshop: tokamak-based and mirror-based. Designs of the tokamak- based devices use the extensive data base generated during decades of tokamak research. Their plasma physics performance can be predicted with a high degree of confidence. On the other hand, they are relatively large and expensive, and best suited for Volumetric Neutron Sources (VNSes) or other large scale test facilities. They also have the advantage of being on the direct path to a power- producing reactor as presently conceived, although alternatives to the tokamak are presently receiving serious consideration for a reactor. The data base for the mirror-based group of plasma sources is less developed, but they are generally more flexible and, with appropriate selection of parameters, have the potential to be developed as compact Accelerated Test Facilities (ATFs) as well as full-scale VNSes. Also discussed at the workshop were some newly proposed but potentially promising concepts, like those based on the flow-through pinch and electrostatic ion-beam sources.

NONE

1996-12-09

272

The Low Energy Neutron Source at Indiana University  

NASA Astrophysics Data System (ADS)

The National Science Foundation has recently approved funding for construction of LENS (the Low Energy Neutron Source) at Indiana University and construction of this facility has begun. LENS represents a new paradigm for economically introducing neutron scattering into a university or industrial setting. Neutrons are produced in a long-pulse (1ms) mode through (p,n) reactions on a water-cooled Be target and supplied to three instrument beam lines. In this talk we will describe how LENS will use neutrons to fulfill its three-fold mission in education, materials research, and developing novel instrumentation. Of particular interest are the facility's ability to study cryogenic moderators at significantly lower temperatures than is possible at other facilities and the development of instruments that make use of the neutron spin to perform high-precision measurements of momentum transfer without significant collimation of the beam. The potential for these developments to expand significantly the range of problems amenable to exploration with neutron techniques will be discussed.

Baxter, David

2004-03-01

273

Measurements of Neutron Beta-decay Using Ultra-Cold Neutrons Produced at a Spallation Source  

NASA Astrophysics Data System (ADS)

We present an overview of our program to provide improved measurements of the neutron beta-asymmetry and other beta-decay observables using ultra-cold neutrons (UCNs) produced at LANSCE. Central to this effort is the recent development of a superthermal solid deuterium source coupled to a tungsten spallation target. Our preliminary production results indicate that ample UCN fluxes should be available for our proposed experiments. We briefly review the properties of this source, issues concerning UCN polarization and measured limits on UCN depolarization in material bottles, and our approach to beta-detection.

Young, A. R.; Hoedl, S.; Liu, C.-Y.; Smith, D.; Filippone, B.; Ito, T.; Jones, C.; McKeown, R.; Yuan, J.; Soyama, K.; Bowles, T.; Brun, T.; Fowler, M.; Hill, R.; Hime, A.; Hogan, G.; Lamoreaux, S.; Morris, C.; Saunders, A.; Seestrom, S.; Walstrom, P.; Alduschenkov, A.; Kharitonov, A.; Lassakov, M.; Rudnev, Y.; Serebrov, A.; Vasilev, A.; Geltenbort, P.; Kitagaki, T.; Asahi, K.; Hino, M.; Kawai, T.; Utsuro, M.; Garcia, A.; Makela, M.; Vogelaar, R. B.

1999-10-01

274

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 1.710(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

275

Production of Source Neutrons by Low Voltage Accelerated Deuterons on Titanium - Tritium Targets  

Microsoft Academic Search

The detailed information on neutron source characteristics is important to meet the demand of research and applications on neutron activation and transport phenomena. Fast monoenergetic neutrons can be produced by two body reactions induced by accelerated particles. In a number of laboratories much progress has been made in producing intense neutron sources based on the Deuteron - Tritium reaction to

Alberto Milocco; Andrej Trkov

276

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

277

Beam plasma neutron sources based on beam-driven mirror  

Microsoft Academic Search

The design and performance of a relatively low-cost, plasma-based, 14-MeV D-T neutron source for accelerated end-of-life testing of fusion reactor materials are described in this article. An intense flux (up to 51018 n\\/m2s) of 14-MeV neutrons is produced in a fully-ionized high-density tritium target (ne 31021 m-3) by injecting a current of 150-keV deuterium atoms. The tritium plasma target

F. H. Coensgen; T. A. Casper; D. L. Correll; C. C. Datum; A. H. Futch; B. G. Logan; A. W. Molvik; C. E. Walter

1989-01-01

278

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

279

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

280

Neutron-pumped excimer flashlamp sources  

NASA Astrophysics Data System (ADS)

A Nuclear Pumped Flashlamp (NPF) is closely related to a Nuclear-Pumped Laser NPL in that both use nuclear radiation to excite the medium. The NPF does not require as high peak power as is needed for NPL inversion. Still, with a reactor source, a large volume NPF can be designed to deliver extremely large fluorescence in the UV up to the infrared range, depending on the media employed. The NPF can then be used for industrial applications or for pumping a laser requiring a high intensity light pump. The first experimental example of this approach was a 3He-XeBr2 NPF employed in 1993 to pump a small iodine laser. The present paper discusses issues involved in scaling such a NPF up to an ultra high energy output.

Miley, George H.; Prelas, Mark A.

2004-01-01

281

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

282

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

SciTech Connect

At the Intense Pulsed Neutron Source (IPNS) 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 {times} 30 cm, {approximately}3 mm resolution, neutron Anger camera area PSD with {sup 6}Li-glass scintillator; a 2.5 cm dia, {approximately}0.7 mm resolution, microchannel-plate area PSD with {sup 6}Li-glass scintillator; a 20 cm {times} 20 cm, {approximately}5 mm resolution, {sup 3}He proportional counter area PSD; a 40 cm {times} 40 cm, {approximately}4 mm resolution, {sup 3}He proportional counter area PSD; a flat 20 cm long, {approximately}1.6 mm resolution, {sup 3}He proportional counter linear PSD; and 160 cylindrical {sup 3}He proportional counter linear PSDs, each of which is 1.27 cm in dia 60 cm long and has {approximately}14 mm resolution. These detectors, in addition to being position-sensitive, resolve the time of the neutron capture with {approximately}1 {mu}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. 14 refs., 6 figs., 1 tab.

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

1990-05-07

283

Small plasma focus as neutron pulsed source for nuclides identification  

SciTech Connect

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.

Milanese, M.; Moroso, R.; Barbaglia, M. [Centro de Investigaciones en Fsica e Ingeniera del Centro de la Provincia de Buenos Aires (CONICET-UNCPBA), Pinto 399, Tandil 7000, Buenos Aires (Argentina) [Centro de Investigaciones en Fsica e Ingeniera del Centro de la Provincia de Buenos Aires (CONICET-UNCPBA), Pinto 399, Tandil 7000, Buenos Aires (Argentina); Universidad del Centro de la Provincia de Buenos Aires (CONICET-UNCPBA), Pinto 399, Tandil 7000, Buenos Aires (Argentina); Niedbalski, J. [CONICET(Consejo Nacional de Investigaciones Cientficas y Tcnicas), Rivadavia 1917, Buenos Aires (Argentina)] [CONICET(Consejo Nacional de Investigaciones Cientficas y Tcnicas), Rivadavia 1917, Buenos Aires (Argentina); Mayer, R. [CNEA (Comisin Nacional de Energa Atmica), Av. Bustillo 9500, San Carlos de Bariloche, Rio Negro (Argentina)] [CNEA (Comisin Nacional de Energa Atmica), Av. Bustillo 9500, San Carlos de Bariloche, Rio Negro (Argentina); Castillo, F. [UNAM (Universidad Nacional Autnoma de Mxico)Circuito Exterior s/n, Ciudad Universitaria, Delg. Coyoacn, P.O. Box 70-543, Mxico DF (Mexico)] [UNAM (Universidad Nacional Autnoma de Mxico)Circuito Exterior s/n, Ciudad Universitaria, Delg. Coyoacn, P.O. Box 70-543, Mxico DF (Mexico); Guichn, S. [Universidad del Centro de la Provincia de Buenos Aires (CONICET-UNCPBA), Pinto 399, Tandil 7000, Buenos Aires (Argentina)] [Universidad del Centro de la Provincia de Buenos Aires (CONICET-UNCPBA), Pinto 399, Tandil 7000, Buenos Aires (Argentina)

2013-10-15

284

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; Guichn, S

2013-10-01

285

Small plasma focus as neutron pulsed source for nuclides identification  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

286

White neutron source from 1 to 400 MeV  

SciTech Connect

A new high intensity white neutron source has recently been constructed at Los Alamos. Beams of nuetrons with a continuous energy distribution up to several hundred MeV are produced by the spallation reaction using the 800 MeV pulsed proton beam from the Los Alamos Meson Physics Facility (LAMPF) linear accelerator. The neutron facility has been designed to make very efficient use of the LAMPF beam with several experiments being able to operate simultaneously. Typical running conditions involve approximately 50,000 bursts/sec and proton beam currents of 2.5 microamperes. Experiments planned for this fall include gamma-ray production, neutron induced fission, and medium energy (n,p) and (p,n) studies. 1 ref., 7 figs., 1 tab.

Wender, S.A.; Lisowski, P.W.

1986-01-01

287

Target station shielding issues at the spallation neutron source.  

PubMed

Recent spallation neutron source shielding activities in support of the neutron beam shutters and the hot cell walls are presented. Existing neutron beam shutters can be replaced with concrete at low power or with concrete and steel at approximately 500 kW of beam power. Potential voids in the hot cell walls are analysed to determine the impact on dose rates as a function of void size. A change in the type of shielding work is noted as the project moved from the early design stages as a 'green field' site to the current stage as a construction project nearing completion, where issues to be addressed are approaching retrofit-type analyses. PMID:16381707

Ferguson, P D; Gallmeier, F X; Iverson, E B; Popova, I I

2005-01-01

288

A prospective pulsed source of ultracold neutrons for experiments in fundamental neutron physics  

NASA Astrophysics Data System (ADS)

Since their discovery, ultracold neutrons (UCNs) have been a unique tool for the investigation of fundamental properties of the free neutron and its interactions. The succesfull installation of a new pulsed superthermal source for ultracold neutrons based on solid deuterium at the TRIGA Mainz reactor is described. In a combination of solid hydrogen acting as pre-moderator and a solid deuterium converter of around 160 cm3, this new UCN source should provide at the experimental area ? 370000 UCN to the storage volume with the reactor operated in the pulse mode. In a storage experiment, a UCN density of 18 2 UCN/cm3 was measured applying 1.5 pulses with a nominal power of 7 MJ. Assuming a linear behaviour of the UCN output as a function of reactor power this corresponds to a UCN density of 25 3 UCN/cm3 for 2 (10 MJ) pulses.

Lauer, Th.; Zechlau, Th.

2013-08-01

289

Report on the international workshop on cold moderators for pulsed neutron sources.  

National Technical Information Service (NTIS)

The International Workshop on Cold Moderators for Pulsed Neutron Sources resulted from the coincidenc of two forces. Our sponsors in the Materials Science Branch of developers both realized that it was time. The Neutron Sources Working Group of the Megasc...

J. Carpenter

1999-01-01

290

Neutron spectroscopy of an accelerator based 7Li(p,n) neutron source with a 3He ionization chamber  

Microsoft Academic Search

Significant discrepancies had been identified by many research groups worldwide between calculated and measured neutron doses from the 7Li(p,n) accelerator based neutron source, and therefore precise characterization of the source was needed. In this work neutron spectra from the 7Li(p,n) source were measured with a 3He ion chamber in the incident proton energy range from 1.95 to 2.3 MeV. The

Witold Matysiak

2010-01-01

291

Shielding and neutronic optimization of the National Spallation Neutron Source (NSNS)  

SciTech Connect

Studies are now underway to establish initial design characteristics for the pulsed neutron source NSNS facility and to optimize the design. In this paper the methodology of calculation is presented together with the calculated facility characteristics. Optimization studies are discussed and initial results shown. This paper addresses the target station of the NSNS.

Charlton, L.A.; Barnes, J.M.; Johnson, J.O.; Gabriel, T.A.

1997-05-01

292

Fission-Fusion Neutron Source Progress Report Sept 30, 2009  

SciTech Connect

In this report the authors describe the progress made in FY09 in evaluating the feasibility of a new concept for using the DT fusion reaction to produce intense pulses of 14 MeV neutrons. In this new scheme the heating of the DT is accomplished using fission fragments rather than ion beams as in conventional magnet confinement fusion schemes or lasers in inertial confinement schemes. As a source of fission fragments they propose using a dust reactor concept introduced some time ago by one of us (RC). An attractive feature of this approach is that there is no need for a large auxiliary power source to heat the DT plasma to the point where self-sustaining fusion become possible. Their scheme does require pulsed magnetic fields, but generating these fields requires only a modest power source. The dust reactor that they propose using for their neutron source would use micron-sized UC pellets suspended in a vacuum as the reactor fuel. Surrounding the fuel with a moderator such as heavy water (D{sub 2}O) would allow the reactor to operate as a thermal reactor and require only modest amounts of HEU. The scheme for using fission fragments to generate intense pulses of 14 MeV neutrons is based on the fission fragment rocket idea. In the fission fragment rocket scheme it was contemplated that the fission fragments produced in a low density reactor core could be guided out of the reactor by large magnetic fields used to form a 'rocket exhaust'. Their adaptation of this idea for the purposes of making a neutron source involves using the fission fragments escaping from one side of a tandem magnet mirror to heat DT gas confined in the adjacent magnetic trap.

Chapline, G F; Daffin, F; Clark, R

2010-02-19

293

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

294

Heat generation and neutron beam characteristics in a high power pulsed spallation neutron source  

SciTech Connect

In the course of conceptual design of a high power pulsed spallation source, a Monte Carlo model was developed for heat generation and neutronics studies. In this paper, we present two sets of results. The first set of calculations was performed with a simple target model to investigate general characteristics of power distribution and neutron production with various proton energies ranging from 0.8 to 12 GeV. The second set was performed with a realistic target model including major components of the target system to provide basic parameters for engineering design of a high power pulsed spallation source. Calculated results generally confirm that higher proton energy provides and advantage in target cooling system requirements and yet somewhat lower neutron beam intensity as a counter effect. The heat generation in the systems surrounding the target was investigated in detail and found to have important variation with position and according to proton beam energy. Calculations of the neutron currents from the moderators showed that the neutron beam intensity from moderators in the front region of the target decreased fro higher proton energy while that from moderators in the back region of the target remained almost unchanged.

Jerng, D.W. [Argonne National Lab., IL (United States); Carpenter, J.M. [Argonne National Lab., IL (United States)][Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of)

1996-11-01

295

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

296

Modeling the neutron yield of a therapeutic thermal neutron source driven with a repetitively pulsed electron linac  

Microsoft Academic Search

Summary form only given. Hampering the development of the medical application of thermal neutrons is the lack of a compact, low cost, high-flux thermal neutron generator. Presently, the only sources of high-flux thermal neutron beams are nuclear research reactors. These facilities are few in number and often lack the clinical environment necessary for medical research. For the therapeutic application of

G. E. Dale; J. M. Gahl

2001-01-01

297

High heat flux target for intense neutron source  

SciTech Connect

A 200-kV, 200-mA deuterium ion accelerator has been developed to simulate the operation of an intense neutron source for use in cancer therapy. The thin-film ScD/sub 2/ target for the neutron source is supported on a water-cooled copper substrate designed to dissipate 40MW/m/sup 2/ at a surface temperature of 450 /sup 0/C. This paper describes the theoretical and experimental analysis of the target and the postmortem analysis of a target after 140 h of operation at power densities exceeding 40 MW/m/sup 2/. Cooling channel erosion due to nucleate boiling of the cooling water was shown to be the life-limiting feature of the target design.

Bacon, F.M.; Cowgill, D.F.; Hickox, C.E.; Walko, R.J.; Subia, S.R. Jr.; Riedel, A.A.

1984-01-01

298

Flow blockage analysis for the advanced neutron source reactor  

Microsoft Academic Search

The Advanced Neutron Source (ANS) reactor was designed to provide a research tool with capabilities beyond those of any existing reactors. One portion of its state-of-the-art design required high-speed fluid flow through narrow channels between the fuel plates in the core. Experience with previous reactors has shown that fuel plate damage can occur when debris becomes lodged at the entrance

T. K. Stovall; J. A. Crabtree; D. K. Felde; J. E. Park

1996-01-01

299

Test facility for a neutron induced positron source  

Microsoft Academic Search

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

B. Straer; M Springer; C Hugenschmidt; K Schreckenbach

1999-01-01

300

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

301

Linac RF structures for the Spallation Neutron Source  

Microsoft Academic Search

The Spallation Neutron Source (SNS) project is a collaboration among Argonne, Brookhaven, Lawrence Berkeley, Los Alamos, and Oak Ridge National Laboratories. Los Alamos is responsible for the linac that accelerates the H- beam from 2.5 MeV to 1 GeV. For the baseline design, scheduled for completion in 2005, the linac will deliver to the accumulator ring a beam of 1.1-MW

J. H. Billen; H. Takeda; T. S. Bhatia

1999-01-01

302

Funnel cavities for 4MW upgrade of Spallation Neutron Source  

Microsoft Academic Search

The Spallation Neutron Source (SNS) project includes a future upgrade option to 4 MW of beam power. The upgrade scenario stipulates adding a second front end and drift-tube linac, and then merging two 402.5-MHz beams from the parallel legs by interlacing them into a single 805-MHz beam at the entrance to the main linac. The funnel energy is chosen to

F. L. Krawczyk; S. S. Kurennoy

1999-01-01

303

Beam dynamics simulation of the Spallation Neutron Source linear accelerator  

Microsoft Academic Search

The accelerating structure for Spallation Neutron Source (SNS) consists of a radio-frequency-quadrupole-linac (RFQ), a drift-tube-linac (DTL), a coupled-cavity-drift-tube-linac (CCDTL), and a coupled-cavity-linac (CCL). The linac is operated at room temperature. The authors discuss the detailed design of linac which accelerates an H⁻ pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from

H. Takeda; J. H. Billen; T. S. Bhatia

1998-01-01

304

Spallation Neutron Source High Power RF Installation and Commissioning Progress  

Microsoft Academic Search

The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In the normal conducting (NC) section of this linac, the Radio Frequency Quadupole (RFQ) and six drift tube linac (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons and the four coupled cavity linac (CCL) cavities are powered by

M. McCarthy; D. Anderson; R. Fuja; P. Gurd; T. Hardek; Y. Kang; K. Young; D. Rees; W. Roybal

2005-01-01

305

Room-temperature linac structures for the Spallation Neutron Source  

Microsoft Academic Search

Los Alamos National Laboratory is building room-temperature rf accelerating structures for the Spallation Neutron Source (SNS). These structures, for Hions, consist of six 402.5 MHz, 2 MW drift-tube linac (DTL) tanks from 2.5 to 87 MeV followed by four 805 MHz, 4 MW coupled-cavity linac (CCL) modules to 186 MeV. The DTL uses permanent magnet quadrupoles inside the drift tubes

J. H. Billen; L. M. Young; S. Kurennoy; K. R. Crandall

2001-01-01

306

CHINA SPALLATION NEUTRON SOURCE ACCELERATORS: DESIGN, RESEARCH, AND DEVELOPMENT.  

SciTech Connect

The China Spallation Neutron Source (CSNS) is a newly approved high-power accelerator project based on a H{sup -} linear accelerator and a rapid cycling synchrotron. During the past year, several major revisions were made on the design including the type of the front end, the linac frequency, the transport layout, the ring lattice, and the type of ring components. Here, we discuss the rationale of design revisions, status of the R&D efforts, and upgrade considerations.

WEI, J.; FU, S.; FANG, S.

2006-06-26

307

Design of a tritium breeding blanket for volumetric neutron source  

Microsoft Academic Search

A water-cooled and austenitic stainless-steel-structured breeding blanket system is designed for a volumetric neutron source (VNS), based on a steady-state tokamak device. The designed VNS with super-conducting coils has a 4.5 m main radius and a total of 300 MW in fusion power. It yields the tritium consumption of approximately 10 kg per year with 50% availability. It is unrealistic

Y. Asaoka; Y. Ogawa; K. Okano; N. Inoue; Y. Murakami; K. Tomabechi; T. Yamamoto; T. Yoshida

1998-01-01

308

ASPUN, Argonne Super Intense Pulsed Spallation Neutron source  

SciTech Connect

Argonne has been in the process of developing plans for pulsed spallation neutron source facilities that would extend the flux levels by at least an order or magnitude over fluxes provided by facilities that are either now in operation or in construction. The ANL facility is called ASPUN for Argonne Super Intense Pulsed Spallation Neutron Source. The heart of ASPUN is a Fixed-Field Alternating Gradient (FFAG) proton synchrotron which, in our opinion, has great potential as a driver for a spallation neutron source. The FFAG synchrotron was extensively studied in the 1950's and early 1960's at the Midwestern Universities Research Association (MURA) laboratories in Stoughton, Wisconsin. An FFAG accelerator has dc excited magnetic fields into which beam is injected on the inside radius and as the beam is accelerated, the average equilibrium orbit radius grows. Frequency modulated rf cavities are used to accelerate the beam with a voltage and frequency program that tracks the beam energy. The conceptual design of the FFAG synchrotron is given. (WHK)

Khoe, T.K.; Kustom, R.L.

1983-01-01

309

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

310

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

311

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 (an order of magnitude more intense than beams available from the most advanced existing reactors). The ANS will be built around a new research reactor of 330-MW fission power, producing an unprecedented peak thermal flux of >7 {center_dot} 10{sup 19} {center_dot} m{sup -2} {center_dot} s{sup -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 top level work breakdown structure (WBS) for the project. As noted in this figure, one component of the project is a research and development (R&D) program (WBS 1.1). This program interfaces with all of the other project level two WBS activities. Because one of the project guidelines is to meet minimum performance goals without relying on new inventions, this R&D activity is not intended to produce new concepts to allow the project to meet minimum performance goals. Instead, the R&D program will focus on the four objectives described.

Selby, D.L.

1995-08-01

312

Absolute experimental and numerical calibration of the 14 MeV neutron source at the Frascati neutron generator  

Microsoft Academic Search

The absolute neutron yield of the 14 MeV Frascati neutron generator (FNG) is routinely measured by means of the associated alpha-particle method with a silicon surface barrier detector (SSD). This paper describes the work carried out to characterize the neutron source in terms of absolute intensity and angle-energy distribution of the emitted neutrons. The development of the measuring setup and

M. Angelone; M. Pillon; P. Batistoni; M. Martini; M. Martone; V. Rado

1996-01-01

313

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

314

Application of a triga research reactor as the neutron source for a production neutron radiography facility  

SciTech Connect

GA Technologies Inc. (GA) has developed a Stationary Neutron Radiography System (SNRS) using a 250-1000 kW TRIGA reactor as the neutron source. The partially below ground reactor will be equipped with four vertical beam tubes originating in the reactor graphite reflector and installed tangential to the core to provide a strong current of thermal neutrons with minimum gamma-ray contamination. The vertical beam tubes interface with rugged component positioning systems designed to handle intact F-11 aircraft wings, partial A-10 aircraft wings, pyrotechnics, and other honeycomb aircraft structures. The SNRS will be equipped with real-time, near-real-time, and film-radiographic imaging systems to provide a broad spectrum of capability for detection of corrosion or entrained moisture in large aircraft panels.

Chesworth, R.H.

1988-01-01

315

Sample environments at the Intense Pulsed Neutron Source (IPNS).  

SciTech Connect

Neutron diffraction is a powerful tool for structural studies of samples in special sample environments because of the high penetrating power of neutrons compared to x-rays. The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory (ANL) offers its users a variety of sample environments for pulsed neutron scattering and diffraction experiments. At the present time over 80% of all experiments performed at the IPNS invoke some type of ancillary equipment to control the sample environment. These include closed-cycle refrigerators, cryostats, furnaces, magnets, and pressure cells. There are also devices for automatic sample changing, positioning, and orientating. Most instruments have at a minimum, a dedicated closed cycle refrigerator (10K to RT) configured for the instrument's typical sample dimensions and scattering angles. Standardization in instrument sample well dimensions, process control equipment, and control software has made multi-instrument use of many of the furnaces and cryostats possible. General use, multi-instrument equipment is maintained by the facility's technical staff. Instrument dedicated equipment is maintained by the respective instrument scientist with help from the ancillary equipment group. The design and upgrading of equipment is done by the ancillary equipment engineer with the oversight and input of instrument scientists, instrument engineer, and technical staff. Ancillary equipment conception and design is science driven, with the instrument scientists and even users providing the initial input for design criteria.

Bohringer, D. E.

1998-11-30

316

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

317

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

Microsoft Academic Search

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

J. W. Meadows; D. L. Smith

1992-01-01

318

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

Microsoft Academic Search

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

James W. Meadows; Donald L. Smith

1993-01-01

319

ORNL contributions to the Advanced Neutron Source (ANS) Project for October 1986March 1987  

Microsoft Academic Search

The Advanced Neutron Source (ANS) Facility - formerly called the Center for Neutron Research - will provide the world's best facilities for the study of neutron scattering. The ANS high power density reactor will be fueled with uranium silicide and cooled, moderated, and reflected by DO. Peak neutron fluxes in the reflector are expected to be 5 to 10 x

D. L. Selby; R. M. Harrington; F. J. Peretz

1987-01-01

320

High-current negative-ion sources for pulsed spallation neutron sources: LBNL workshop, October 1994  

SciTech Connect

The neutron scattering community has endorsed the need for a high-power (1 to 5 MW) accelerator-driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (sub-microsecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 kW source in the UK), and call for a high-current (approx. 100 mA peak) H- source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The I to 5 GeV proton beam is extracted in a single turn and brought to the target-moderator stations. The high current, high duty-factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. The Workshop reported on here, held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H- source technologies, and identified necessary R&D efforts to bridge the gap.

Alonso, J.R.

1995-09-01

321

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 410 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.

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

1999-08-01

322

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

323

Neutron source in the MCNPX shielding calculating for electron accelerator driven facility  

SciTech Connect

Argonne National Laboratory (ANL) of USA and Kharkov Inst. of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of an experimental neutron source facility. It is an accelerator driven system (ADS) utilizing a subcritical assembly driven by electron accelerator. 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 a design tool due to its capability to transport electrons, photons, and neutrons at high energies. However the facility shielding calculations with MCNPX need enormous computational resources and the small neutron yield per electron makes sampling difficulty for the Monte Carlo calculations. A method, based on generating and utilizing neutron source file, was proposed and tested. This method reduces significantly the required computer resources and improves the statistics of the calculated neutron dose outside the shield boundary. However the statistical errors introduced by generating the neutron source were not directly represented in the results, questioning the validity of this methodology, because an insufficiently sampled neutron source can cause error on the calculated neutron dose. This paper presents a procedure for the validation of the generated neutron source file. The impact of neutron source statistic on the neutron dose is examined by calculating the neutron dose as a function of the number of electron particles used for generating the neutron source files. When the value of the calculated neutron dose converges, it means the neutron source has scored sufficient records and statistic does not have apparent impact on the calculated neutron dose. In this way, the validity of neutron source and the shield analyses could be verified. (authors)

Zhong, Z.; Gohar, Y. [Nuclear Engineering Div., Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

2012-07-01

324

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

325

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

326

Coded source neutron imaging at the PULSTAR reactor  

SciTech Connect

A neutron imaging facility is located on beam-tube No.5 of the 1-MW PULSTAR reactor at North Carolina State University. An investigation of high resolution imaging using the coded source imaging technique has been initiated at the facility. Coded imaging uses a mosaic of pinholes to encode an aperture, thus generating an encoded image of the object at the detector. To reconstruct the image data received by the detector, the corresponding decoding patterns are used. The optimized design of coded mask is critical for the performance of this technique and will depend on the characteristics of the imaging beam. In this work, a 34 x 38 uniformly redundant array (URA) coded aperture system is studied for application at the PULSTAR reactor neutron imaging facility. The URA pattern was fabricated on a 500 ?m gadolinium sheet. Simulations and experiments with a pinhole object have been conducted using the Gd URA and the optimized beam line.

Xiao, Ziyu [North Carolina State University; Mishra, Kaushal [North Carolina State University; Hawari, Ayman [North Carolina State University; Bingham, Philip R [ORNL; Bilheux, Hassina Z [ORNL; Tobin Jr, Kenneth William [ORNL

2011-01-01

327

Recent performance of the Intense Pulsed Neutron Source accelerator system  

SciTech Connect

The Intense Pulsed Neutron Source (IPNS) accelerator system has now been in operation as part of a national user program for over five years. During that period steady progress has been made in both beam intensity and reliability. Almost 1.8 billion pulses totaling 4 x 10/sup 21/ protons have now been delivered to the spallation neutron target. Recent weekly average currents have reached 15 ..mu..A (3.2 x 10/sup 12/ protons per pulse, 30 pulses per second) and short-term peaks of almost 17 ..mu..A have been reached. In fact, the average current for the last two years is up 31% over the average for the first three years of operation.

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

1987-03-01

328

BEAM DUMP WINDOW DESIGN FOR THE SPALLATION NEUTRON SOURCE.  

SciTech Connect

The Spallation Neutron Source accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. Beam tuning dumps are provided at the end of the linac (the Linac Dump) and in the Ring-to-Target transport line (the Extraction Dump) [1]. Thin windows are required to separate the accelerator vacuum from the poor vacuum upstream of the beam dump. There are several challenging engineering issues that have been addressed in the window design. Namely, handling of the high local power density deposited by the stripped electrons from the H-beam accelerated in the linac, and the need for low-exposure removal and replacement of an activated window. The thermal design of the linac dump window is presented, as is the design of a vacuum clamp and mechanism that allows remote removal and replacement of the window.

RAPARIA,D.RANK,J.MURDOCH,G.ET AL.

2004-03-10

329

Study of spherical torus based volume neutron source  

SciTech Connect

With the worldwide development of fusion power focusing on the design of the International Thermonuclear Experimental Reactor (ITER), developmental strategies for the demonstration fusion power plant (DEMO) are being discussed. A relatively prudent strategy is to construct and operate a small deuterium tritium fuelled volumetric neutron source (VNS) in parallel with ITER. The VNS is to provide, over a period less than 20 years, a relatively high fusion neutron fluence of 6 MW year m2 and wall loading of 1 MW m2 or more, over an accessible blanket test area of more than 10 m2. Such a VNS would complement ITER in testing, developing, and qualifying nuclear technology components, materials, and their combinations for DEMO and future commercial power plants. The effort of this study has established the potential of the spherical tokamak as a credible VNS concept that satisfies the above requirements.

Cheng, E.T. [TSI Research Inc.; Peng, Yueng Kay Martin [ORNL

1998-01-01

330

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

331

The RF system for the National Spallation Neutron Source linac  

SciTech Connect

The National Spallation Neutron Source (NSNS) system has been proposed to dramatically improve the neutron capabilities for science applications in the US. The NSNS is a fast pulse neutron source that would consist of a 1000 MeV H-linac, an accumulator ring, a neutron target, and an experimental area. Although the NSNS is to be built at Oak Ridge, the design responsibility is delegated to five US national laboratories, and the Los Alamos National Laboratory is responsible for the linac portion of this machine, from the output of the radio frequency quadrupole (RFQ) accelerator, to the entrance to the accumulator ring. In the baseline design, a total of 59 klystrons are used to provide the RF power for a 1-MW average power beam in the accumulator ring, and a 1.04 ms pulse length, 6.24% duty factor beam in the linac. The frequencies chosen are 402.5 MHz for the RFQ and drift tube linac (DTL) portions of the machine, and 805 MHz for the coupled-cavity DTL (CCDTL) and coupled cavity (CCL) portions of the linac. The baseline 805 MHz klystron is capable of 2.5 MW peak power into a flat load, and it contains a modulating anode. The backup 805 MHz klystron is cathode pulsed, and has a 5 MW peak output power. The modulators for these two klystrons are vastly different. The challenges and compromises for the two klystrons and their associated modulators and RF systems are discussed. The baseline design RF system is presented in detail.

Tallerico, P.; Billen, J.; Jason, A. [and others

1997-06-01

332

Design Optimization and the path towards a 2 MW Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) is designed to ultimately reach an average proton beam power of 2 MW for pulsed neutron production. The SNS physics groups analyze the machine performance within the hardware constraints, optimize the accelerator design, and establish the best path towards a 2 MW and higher spallation neutron source.

M. Blaskiewicz; N. Catalan-Lasheras; D. Davino; A. Fedotov; Y. Lee; N. Malitsky; Y. Papaphilippou; D. Raparia; A. Shishlo; N. Tsoupas; J. Wei; W. Weng; S. Zhang; J. Billen; S. Kurennoy; S. Nath; J. Stovall; H. Takeda; L. Young; R. Keller; J. Staples; A. Aleksandrov; Y. Cho; P. Chu; S. Cousineau; V. Danilov; M. Doleans; J. Galambos; J. Holmes; N. Holtkamp; D. Jeon; S. Kim; R. Kustom; E. Tanke; W. Wan; R. Sundelin

2001-08-01

333

PULSE-SHAPE DISCRIMINATION FOR IDENTIFICATION OF NEUTRON SOURCES USING THE BC501A LIQUID SCINTILLATOR  

Microsoft Academic Search

Fast and accurate identification of neutron sources is very important in nuclear nonproliferation and international safeguards applications. Commonly, the identification of neutron spectra relies on unfolding procedures, which requires the solution of an ill-posed problem. In this paper, we present a new application of an existing technique, which can be used for neutron source identification without employing energy-spectrum unfolding techniques.

M. Flaska; S. A. Pozzi

2007-01-01

334

DESIGN OPTIMIZATION AND THE PATH TOWARDS A 2 MW SPALLATION NEUTRON SOURCE.  

SciTech Connect

The Spallation Neutron Source (SNS) is designed to ultimately reach an average proton beam power of 2 MW for pulsed neutron production. The SNS physics groups analyze the machine performance within the hardware constraints, optimize the accelerator design, and establish the best path towards a 2 MW and higher spallation neutron source.

WEI,J.; BLASKIEWICZ,M.; CATALAN-LASHERAS,N.; DAVINO,D.; FEDOTOV,A.; LEE,Y.Y.; MALITSKY,N.; ET AL

2001-06-18

335

Optimizing a three-element core design for the Advanced Neutron Source Reactor  

Microsoft Academic Search

Source of neutrons in the proposed Advanced Neutron Source facility is a multipurpose research reactor providing 5-10 times the flux, for neutron beams, of the best existing facilities. Baseline design for the reactor core, based on the ``no new inventions`` rule, was an assembly of two annular fuel elements similar to those used in the Oak Ridge and Grenoble high

1995-01-01

336

A single-crystal diamond-based thermal neutron beam monitor for instruments at pulsed neutron sources  

NASA Astrophysics Data System (ADS)

Single-crystal diamond detectors manufactured through a Chemical Vapour Deposition (CVD) technique are recent technology devices that have been employed in reactor and Tokamak environments in order to detect both thermal and almost monochromatic 14 MeV neutrons produced in deuterium-tritium ( d-t) nuclear fusion reactions. Their robustness and compactness are the key features that can be exploited for different applications as well. Aim of the present experimental investigation is the assessment of the performance of a diamond detector as a thermal neutron beam monitor at pulsed neutron sources. To this aim, a test measurement was carried out on the Italian Neutron Experimental Station (INES) beam line at the ISIS spallation neutron source (Great Britain). The experiment has shown the capability of these devices to work at a pulsed neutron source for beam monitoring purposes. Other interesting possible applications are also suggested.

Pietropaolo, A.; Verona Rinati, G.; Verona, C.; Schooneveld, E. M.; Angelone, M.; Pillon, M.

2009-11-01

337

General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

This research investigates the use of a PETtrace cyclotron produced by General Electric (GE) as a neutron source for boron neutron capture therapy (BNCT). The GE PETtrace was chosen for this investigation because this type of cyclotron is popular among nuclear pharmacies and clinics in many countries; it is compact and reliable; it produces protons with energies high enough to produce neutrons with appropriate energy and fluence rate for BNCT and it does not require significant changes in design to provide neutrons. In particular, the standard PETtrace 18O target is considered. The cyclotron efficiency may be significantly increased if unused neutrons produced during radioisotopes production could be utilized for other medical modalities such as BNCT at the same time. The resulting dose from the radiation emitted from the target is evaluated using the Monte Carlo radiation transport code MCNP at several depths in a brain phantom for different scattering geometries. Four different moderating materials of various thicknesses were considered: light water, carbon, heavy water, arid Fluental(TM). The fluence rate tally was used to calculate photon and neutron dose, by applying fluence rate-to-dose conversion factors. Fifteen different geometries were considered and a 30-cm thick heavy water moderator was chosen as the most suitable for BNCT with the GE PETtrace cyclotron. According to the Brookhaven Medical Research Reactor (BMRR) protocol, the maximum dose to the normal brain is set to 12.5 RBEGy, which for the conditions of using a heavy water moderator, assuming a 60 muA beam current, would be reached with a treatment time of 258 min. Results showed that using a PETtrace cyclotron in this configuration provides a therapeutic ratio of about 2.4 for depths up to 4 cm inside a brain phantom. Further increase of beam current proposed by GE should significantly improve the beam quality or the treatment time and allow treating tumors at greater depths.

Bosko, Andrey

338

Neutron sources for in-situ planetary science applications  

NASA Astrophysics Data System (ADS)

There are a number of future European Space Agency (ESA) and NASA planetary science missions that are in the planning or initial study phases, where the scientific objectives include determining the surface composition, measuring planetary surface heat flow and constraining planetary chronology. The University of Leicester is developing instrumentation for geophysical applications that include ?-ray spectroscopy, ?-ray densitometry and radiometric dating. This paper describes the modelling of a geophysical package, with the Monte Carlo code MCNPX, in order to determine the impact that a neutron source would have on in-situ composition measurements, radiometric dating and, in particular, trace element detection. The suitability of ? 2.542.54 cm LaBr3(Ce) detectors in the geophysical package for in-situ missions was examined. 252Cf, Am-Be and Pu-Be neutron sources were compared in a trade-off study to determine mission suitability, potential for thermal and electric power production, mass and shielding requirements. This study is linked to a parallel examination of the suitability of radioisotope thermal generators for in-situ planetary science applications. The aim of the modelling was to optimise the source type and detector geometry in order to measure the elemental peaks of interest with a precision of 10% or better based on the Poisson statistics of the detected counts above background.

Skidmore, M. S.; Ambrosi, R. M.; O'Brien, R. C.

2009-09-01

339

The New Munich Neutron Source FRM II: Overview and Uses for Biological Studies  

SciTech Connect

The application of neutron scattering to biological systems using the new neutron source in Munich is discussed. Structural as well as dynamical studies of biomolecules with a variety of spectrometers, diffractometers and reflectometers are explained.

Doster, Wolfgang [Technical University Munich, Physics Department E 13, D-85748 Garching (Germany)

2007-11-26

340

Chopper layout for spectrometers at long pulse neutron sources  

NASA Astrophysics Data System (ADS)

We discuss the implications of a long pulse neutron source for the chopper system of direct geometry time-of-flight spectrometers. While the same conditions apply for the layout of the resolution defining choppers as on reactor based instruments, we emphasize the multi-chromatic nature of the instruments. The chopper system must not only provide a unique assignment of the wavelength to each pulse, but also provide adopted time frames matching the respective energy of the pulse. We propose a chopper system consisting of disc choppers, heavy T0 choppers and a newly developed Fan chopper to account for the various challenges due to the long pulse nature.

Voigt, J.; Violini, N.; Brckel, T.

2014-03-01

341

A compact neutron generator using a field ionization source.  

PubMed

Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-fibers promise the high field-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of field emitters with a density up to 10(6)?tips?cm(2) and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties. PMID:22380291

Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas

2012-02-01

342

A compact neutron generator using a field ionization source  

NASA Astrophysics Data System (ADS)

Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-fibers promise the high field-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of field emitters with a density up to 106 tips/cm2 and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.

Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas

2012-02-01

343

Flat-spectrum radio sources - Cosmic conspiracy or relativistic neutrons?  

NASA Technical Reports Server (NTRS)

The intensity spectrum of the core of radio-loud AGN varies smoothly from 10 exp 8.5 to 10 to the 16th Hz, and is flat between 10 to the 9th and 10 to the 10th Hz, implying that a single emission mechanism is responsible. It is proposed here that energy is transported from the central source by relativistic neutrons which travel freely over a large volume and decay into relativistic protons. The protons produce secondary electrons which generate the observed radiation. The photon spectra thus produced are largely model-independent and flat.

Giovanoni, Peter M.; Kazanas, Demosthenes

1990-01-01

344

Beginnings of remote handling at the RAL Spallation Neutron Source  

SciTech Connect

Expenditure of funds and resources for remote maintenance systems traditionally are delayed until late in an accelerator's development. However, simple remote-surveillance equipment can be included early in facility planning to set the stage for future remote-handling needs and to identify appropriate personnel. Some basic equipment developed in the UK at the Spallation Neutron Source (SNS) that serves this function and that has been used to monitor beam loss during commissioning is described. A photograph of this equipment, positioned over the extractor septum magnet, is shown. This method can serve as a pattern approach to the problem of initiating remote-handling activities in other facilities.

Liska, D.J.; Hirst, J.

1985-01-01

345

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

346

Physics design of the National Spallation Neutron Source linac  

SciTech Connect

The National Spallation Neutron Source (NSNS) requires a linac that accelerates a H{sup {minus}} beam to 1.0 GeV. The linac starts with a radio-frequency quadrupole (RFQ) accelerator, which is followed by a drift-tube linac (DTL), a coupled-cavity drift-tube linac (CCDTL), and a conventional coupled-cavity linac (CCL). In this paper, the authors focus on the DTL, CCDTL, and CCL parts of the accelerator. They discuss the linac design parameters and beam dynamics issues. The design rationale of no separate matching sections between different accelerating sections maintains the current independence of beam behavior.

Takeda, H.; Billen, J.H.; Nath, S.

1997-10-01

347

STUDY OF A 10-MW CONTINUOUS SPALLATION NEUTRON SOURCE.  

SciTech Connect

This paper reports on the feasibility study of a proton Super-Conducting Linac as the driver for an Accelerator-based Continuous Neutron Source (ACNS) [1] to be located at Brookhaven National Laboratory (BNL). The Linac is to be operated in the Continuous Wave (CW) mode to produce an average 10 MW of beam power. The Linac beam energy is taken to be 1.25 GeV. The required average proton beam intensity in exit is then 8 mA.

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

2003-05-12

348

Carbon Nanotube Based Deuterium Ion Source for Improved Neutron Generators  

SciTech Connect

Field ionization uses high electric fields to cause the ionization and emission of ions from the surface of a sharp electrode. We are developing a novel field ionization neutron generator using carbon nanotubes (CNT) to produce the deuterium ion current. The generator consists of three major components: a deuterium ion source made of carbon nanotubes, a smooth negatively-biased target electrode, and a secondary electron suppression system. When a negative high voltage is applied on the target electrode, a high gradient electric field is formed at the tips of the carbon nanotubes. This field is sufficiently strong to create deuterium (D) ions at or near the nanotubes which are accelerated to the target causing D-D reactions to occur and the production of neutrons. A cross magnetic field is used to suppress secondary emission electrons generated on the target surface. We have demonstrated field ionization currents of 70 nA (1 {mu}A/cm{sup 2}) at hydrogen gas pressure of 10 mTorr. We have found that the current scales proportionally with CNT area and also with the gas pressure in the range of 1 mTorr to 10 mTorr. We have demonstrated pulse cut-off times as short as 2 {mu}sec. Finally, we have shown the feasibility of generating neutrons using deuterium gas.

Fink, R. L.; Jiang, N.; Thuesen, L. [Applied Nanotech, Inc., 3006 Longhorn Blvd., Ste 107, Austin, TX 78758 (United States); Leung, K. N. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antolak, A. J. [Sandia National Laboratories, Livermore, CA 94550 (United States)

2009-03-10

349

Materials considerations for the National Spallation Neutron Source target  

SciTech Connect

The National Spallation Neutron Source (NSNS), in which neutrons are generated by bombarding a liquid mercury target with 1 GeV protons, will place extraordinary demands on materials performance. The target structural material will operate in an aggressive environment, subject to intense fluxes of high energy protons, neutrons, and other particles, while exposed to liquid mercury and to water. Components that require special consideration include the Hg liquid target container and protective shroud, beam windows, support structures, moderator containers, and beam tubes. In response to these demands a materials R and D program has been developed for the NSNS that includes: selection of materials; calculations of radiation damage; irradiations, post irradiation testing, and characterization; compatibility testing and characterization; design and implementation of a plan for monitoring of materials performance in service; and materials engineering and technical support to the project. Irradiations are being carried out in actual and simulated spallation environments. Compatibility experiments in Hg are underway to ascertain whether the phenomena of liquid metal embrittlement and temperature gradient mass transfer will be significant. Results available to date are assessed in terms of the design and operational performance of the facility.

Mansur, L.K.; DiStefano, J.R.; Farrell, K.; Lee, E.H.; Pawel, S.J. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Wechsler, M.S. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering

1997-08-01

350

Post-irradiation examination of the Spallation Neutron Source target module  

Microsoft Academic Search

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

David A McClintock; Phillip D Ferguson; Louis K Mansur

2010-01-01

351

Preliminary study of coded-source-based neutron imaging at the CPHS  

Microsoft Academic Search

A cold neutron radiography\\/tomography instrument is under construction at the Compact Pulsed Hadron Source (CPHS) at Tsinghua University, China. The neutron flux is so low that an acceptable neutron radiographic image requires a long exposure time in the single-hole imaging mode. The coded-source-based imaging technique is helpful to increase the utilization of neutron flux to reduce the exposure time without

Yuanji Li; Zhifeng Huang; Zhiqiang Chen; Kejun Kang; Yongshun Xiao; Xuewu Wang; Jie Wei; C.-K. Loong

2011-01-01

352

Rapidly pulsed TRIGA reactor: an intense source for neutron scattering experiments  

Microsoft Academic Search

The need for ever increasing intensities of thermal neutron beams for neutron scattering experiments has stimulated the development of intense steady state research reactors such as the 53-MW ILL reactor at Grenoble. The source flux at the reactor end of the beam ports is typically 10n\\/cm.s for its thermal neutron beams. To achieve still higher source fluxes of neutrons, the

Whittemore; William L

1994-01-01

353

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

NASA Astrophysics Data System (ADS)

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- 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.

2010-02-01

354

Intense Steady State Neutron Source. The CNR Reactor.  

National Technical Information Service (NTIS)

The Center for Neutron Research (CNR) has been proposed in response to the needs - neutron flux, spectrum, and experimental facilities - that have been identified through workshops, studies, and discussions by the neutron-scattering, isotope, and material...

F. C. Difilippo R. M. Moon W. R. Gambill R. M. Moon R. T. Primm

1986-01-01

355

A hydrocarbon fluid-based deuteron ion source for neutron generators  

NASA Astrophysics Data System (ADS)

A deuteron ion source based on a spark discharge between electrodes coated with a deuterated hydrocarbon fluid is investigated. In the prototypic example studied here ion currents extracted from the source were on the order of 0.5 A with a pulse duration of approximately 10 ?s. Operation in a laboratory neutron generator provided a neutron yield of 105 neutrons/pulse with the deuterium-deuterium fusion reaction at a deuteron ion energy of 65 keV. This approach to ion sources for neutron generators has the potential to provide a compact, long-lived, high-output neutron generator for homeland security applications.

Schwoebel, P. R.

2012-10-01

356

The Spallation Neutron Source (SNS) conceptual design shielding analysis  

SciTech Connect

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 discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.

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

1998-03-01

357

Shielding Design of the Spallation Neutron Source (SNS)  

SciTech Connect

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 discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements, calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.

Johnson, J.O.

1998-09-17

358

THE SPALLATION NEUTRON SOURCE CRYOMODULE TEST STAND RF SYSTEM  

SciTech Connect

The Spallation Neutron Source (SNS) has recently commissioned a cryomodule test facility for the repair and testing of the super-conducting radio-frequency (SRF) cavities. This facility utilizes the original 402.5/805 MHz Radio Frequency (RF) Klystron Test Stand as its power source along with dual Low Level RF (LLRF) control systems. One control system is based on the standard SNS Linac LLRF controls with a second system for open-loop only control. The system is designed to allow simultaneous testing of devices in the test cave and other devices which can be tested outside of the enclosure. Initial tests have shown good results; some improvements are yet to be implemented.

Crofford, Mark T [ORNL] [ORNL; Ball, Jeffrey Allen [ORNL] [ORNL; Davidson Jr, Taylor L [ORNL] [ORNL; Hardek, Thomas W [ORNL] [ORNL; Heidenreich, Dale A [ORNL] [ORNL; Kasemir, Kay [ORNL] [ORNL; Kim, Sang-Ho [ORNL] [ORNL; Kang, Yoon [ORNL] [ORNL

2008-01-01

359

The Upgrade of the Neutron Induced Positron Source NEPOMUC  

NASA Astrophysics Data System (ADS)

In summer 2012, the new NEutron induced POsitron Source MUniCh (NEPOMUC) was installed and put into operation at the research reactor FRM II. At NEPOMUC upgrade 80% 113Cd enriched Cd is used as neutron-gamma converter in order to ensure an operation time of 25 years. A structure of Pt foils inside the beam tube generates positrons by pair production. Moderated positrons leaving the Pt front foil are electrically extracted and magnetically guided to the outside of the reactor pool. The whole design, including Pt-foils, the electric lenses and the magnetic fields, has been improved in order to enhance both the intensity and the brightness of the positron beam. After adjusting the potentials and the magnetic guide and compensation fields an intensity of about 3109 moderated positrons per second is expected. During the first start-up, the measured temperatures of about 90C ensure a reliable operation of the positron source. Within this contribution the features and the status of NEPOMUC upgrade are elucidated. In addition, an overview of recent positron beam experiments and current developments at the spectrometers is given.

Hugenschmidt, C.; Ceeh, H.; Gigl, T.; Lippert, F.; Piochacz, C.; Pikart, P.; Reiner, M.; Weber, J.; Zimnik, S.

2013-06-01

360

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

361

Absolute calibration of the JT-60U neutron monitor using a 252Cf neutron source (abstract)a)  

Microsoft Academic Search

Absolutely calibrated measurements of the neutron yield are important for the evaluation of the plasma performance such as the fusion gain Q in D-D operating tokamaks. The time-resolved neutron yield is measured with 235U and 238U fission chambers and 3He proportional counters in the JT-60U tokamak. The insitu calibration was performed by moving the 252Cf neutron source toroidally through the

T. Nishitani; H. Takeuchi; T. Kondoh; T. Itoh; M. Kuriyama; Y. Ikeda; T. Iguchi; Cris W. Barnes

1992-01-01

362

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

NASA Astrophysics Data System (ADS)

The new high flux research reactor of the Technical University of Munich (Technische Universitt Mnchen, TUM) will be equipped with a cold neutron source (CNS). The centre of the CNS will be located in the D 2O-reflector tank at 400 mm from the reactor core axis close to the thermal neutron flux maximum. The power of 4500 W developed by the nuclear heating in the 16 l of liquid deuterium at 25 K, and in the structures, is evacuated by a two-phase thermal siphon avoiding film boiling and flooding. The thermal siphon is a single tube with counter current flow. It is inclined by 10 from vertical, and optimised for a deuterium flow rate of 14 g/s. Optimisation of structure design and material, as well as safety aspects will be discussed. Those parts of the structure, which are exposed to high thermal neutron flux, are made from Zircaloy 4 and 6061T6 aluminium. Structure failure due to embrittlement of the structure material under high rapid neutron flux is very improbable during the lifetime of the CNS (30 years). Double, in pile even triple, containment with inert gas liner guarantees lack of explosion risk and of tritium contamination to the environment. Adding a few percent of hydrogen (H 2) to the deuterium (D 2) will improve the moderating properties of our relatively small moderator volume. Nearly all of the hydrogen is bound in the form of HD molecules. A long-term change of the hydrogen content in the deuterium is avoided by storing the mixture not in a gas buffer volume but as a metal hydride at low pressure. The metal hydride storage system contains two getter beds, one with 250 kg of LaCo 3Ni 2, the other one with 150 kg of ZrCo 0.8Ni 0.2. Each bed can take the total gas inventory, both beds together can absorb the total gas inventory in <6 min at a pressure <3 bar. The new reactor will have 13 beam tubes, 4 of which are looking at the CNS, including two for very cold (VCN) and ultra-cold neutron (UCN) production. The latter will take place in the horizontal beam tube SR4, which will house an additional cryogenic moderator (e.g. solid deuterium). More than 60% of the experiments foreseen in the new neutron research facility will use cold neutrons from the CNS. The mounting of the hardware components of the CNS into the reactor has started in the spring of 2000. The CNS went into trial operation in the end of year 2000.

Gobrecht, K.; Gutsmiedl, E.; Scheuer, A.

2002-01-01

363

Effect of Fusion Neutron Source Numerical Models on Neutron Wall Loading in a D-D Tokamak Device  

NASA Astrophysics Data System (ADS)

Effect of various spatial and energy distributions of fusion neutron source on the calculation of neutron wall loading of Tokamak D-D fusion device has been investigated by means of the 3-D Monte Carlo code MCNP. A realistic Monte Carlo source model was developed based on the accurate representation of the spatial distribution and energy spectrum of fusion neutrons to solve the complicated problem of tokamak fusion neutron source modelling. The results show that those simplified source models will introduce significant uncertainties. For accurate estimation of the key nuclear responses of the tokamak design and analyses, the use of the realistic source is recommended. In addition, the accumulation of tritium produced during D-D plasma operation should be carefully considered.

Chen, Yi-xue; Wu, Yi-can

2003-04-01

364

Neutron measurements  

SciTech Connect

Methods of neutron detection and measurement are discussed. Topics include sources of neutrons, neutrons in medicine, interactions of neutrons with matter, neutron shielding, neutron measurement units, measurement methods, and neutron spectroscopy. (ACR)

McCall, R.C.

1981-01-01

365

Demonstration of a solid deuterium source of ultra-cold neutrons  

NASA Astrophysics Data System (ADS)

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 Letter we report on the performance of a prototype spallation neutron-driven solid deuterium source. This source produced bottled UCN densities of 1457UCN/cm 3, 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.

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

2004-07-01

366

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

NASA Astrophysics Data System (ADS)

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 reviewed. The likely parameter ranges for tokamak neutron sources that could produce an interesting transmutation rate of 100s to 1000s of kg/FPY (where FPY stands for full power year) are identified (Pfus approx 10-100 MW, ?N approx 2-3, Qp approx 2-5, R approx 3-5 m, I approx 6-10 MA). The electrical and thermal power characteristics of transmutation reactors driven by fusion and accelerator spallation neutron sources are compared. The status of fusion development vis--vis a neutron source is reviewed.

Stacey, W. M.

2001-02-01

367

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

SciTech Connect

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

Foster, Christopher; Baxter, David V

2012-11-17

368

Neutron-irradiation facilities at the Intense Pulsed Neutron Source-I for fusion magnet materials studies  

SciTech Connect

The decommissioning of reactor-based neutron sources in the USA has led to the development of a new generation of neutron sources that employ high-energy accelerators. Among the accelerator-based neutron sources presently in operation, the highest-flux source is the Intense Pulsed Neutron Source (IPNS), a user facility at Argonne National Laboratory. Neutrons in this source are produced by the interaction of 400 to 500 MeV protons with either of two /sup 238/U target systems. In the Radiation Effects Facility (REF), the /sup 238/U target is surrounded by Pb for neutron generatjion and reflection. The REF has three separate irradiation thimbles. Two thimbles provide irradiation temperatures between that of liquid He and several hundred degrees centigrade. The third thimble operates at ambient temperature. The large irradiation volume, the neutron spectrum and flux, the ability to transfer samples without warm up, and the dedication of the facilities during the irradiation make this ideally suited for radiation damage studies on components for superconducting fusion magnets. Possible experiments for fusion magnet materials are discussed on cyclic irradiation and annealing of stabilizers in a high magnetic field, mechanical tests on organic insulation irradiated at 4 K, and superconductors measured in high fields after irradiation.

Brown, B.S.; Blewitt, T.H.

1982-01-01

369

High electric field deuterium ion sources for neutron generators  

NASA Astrophysics Data System (ADS)

Active interrogation systems for highly enriched uranium require improved fieldable neutron sources. The target technology for deuterium-tritium neutron generators is well understood and the most significant improvement can be achieved by improving the deuterium ion source through increased output and, in some cases, lifetime of the ion source. We are developing a new approach to a deuterium ion sources based upon the field desorption/evaporation of deuterium from the surfaces of metal tips. Electrostatic field desorption (EFD) desorbs previously adsorbed deuterium as ions under the influence of high electric fields (several V/A), without removing tip material. Single etched wire tip experiments have been performed and have shown that this is difficult but can be achieved with molybdenum and tungsten tips. Electrostatic field evaporation (EFE) evaporates ultra thin deuterated titanium films as ions. It has been shown that several 10s of atomic layers can be removed within a few nanoseconds from etched tungsten tips. In the course of these studies titanium deposition and deuteration methods were studied and new detection methods developed. Space charge effects resulting from the large ion currents were identified to be the most likely cause of some unusual ion emission characteristics. In addition, on W < 110 > oriented substrates a surprising body-centered cubic crystal structure of the titanium film was found and studied. The ion currents required for neutron generator applications can be achieved by microfabrication of metal tip arrays. Field desorption studies of microfabricated field emitter tip arrays have been conducted for the first time. Maximum fields of 3 V/A have been applied to the array tip surfaces to date, although fields of 2 V/A to 2.5 V/A are more typical. Desorption of atomic deuterium ions has been observed at fields of roughly 2 V/A at room temperature. The desorption of common surface adsorbates, such as hydrogen, carbon, water, and carbon monoxide is observed at fields exceeding 1 V/A. In vacuo heating of the arrays to temperatures of the order of 800C can be effective in removing many of the surface contaminants observed. For both the field desorption and the field evaporation approaches further improvements to array design and fabrication are required if arrays are to provide sufficient deuterium ion currents to produce 109 to 1010 n/cm2 of tip array area for the detection systems.

Reichenbach, Birk

370

Radio Isotope Method for Rapid Determination of Proppant Concentration in Working Mixtures Used in Hydraulic Fracturing of Oil and Gas Containing Strata  

Microsoft Academic Search

A radio isotope method for rapid determination of proppant concentration and a test measurement unit RIKP-01 constructed on the basis of it provides a relative error in determining proppant concentration of not more than 3.5% with a measurement time of 15 sec that is four times better than for the world leader, i.e., the firm Halliburton (USA).

O. T. Nurgaliev; V. K. Kuleshov; Yu. A. Volchenko; M. S. Sukhanov

2005-01-01

371

Double Chooz Neutron Detection Efficiency with Calibration System  

NASA Astrophysics Data System (ADS)

The Double Chooz experiment is designed to search for a non-vanishing mixing angle theta13 with unprecedented sensitivity. The first results obtained with the far detector only indicate a non-zero value of theta13. The Double Chooz detector system consists of a main detector, an outer veto system and a number of calibration systems. The main detector consists of a series of concentric cylinders. The target vessel, a liquid scintillator loaded with 0.1% Gd, is surrounded by the gamma-catcher, a non-loaded liquid scintillator. A buffer region of non-scintillating liquid surrounds the gamma-catcher and serves to decrease the level of accidental background. There is the Inner Veto region outside the buffer. The experiment is calibrated with light sources, radioactive point sources, cosmics and natural radioactivity. The radio-isotopes sealed in miniature capsules are deployed in the target and the gamma-catcher. Neutron detection efficiency is one of the major systematic components in the measurement of anti-neutrino disappearance. An untagged 252Cf source was used to determine fractions of neutron captures on Gd, neutron capture time systematic and neutron delayed energy systematic. The details will be explained in the talk.

Chang, Pi-Jung

2012-03-01

372

Characteristics comparison between a cyclotron-based neutron source and KUR-HWNIF for boron neutron capture therapy  

Microsoft Academic Search

At Kyoto University Research Reactor Institute (KURRI), 275 clinical trials of boron neutron capture therapy (BNCT) have been performed as of March 2006, and the effectiveness of BNCT has been revealed. In order to further develop BNCT, it is desirable to supply accelerator-based epithermal-neutron sources that can be installed near the hospital. We proposed the method of filtering and moderating

H. Tanaka; Y. Sakurai; M. Suzuki; S. Masunaga; Y. Kinashi; G. Kashino; Y. Liu; T. Mitsumoto; S. Yajima; H. Tsutsui; A. Maruhashi; K. Ono

2009-01-01

373

ABSORPTION OF NEUTRONS EMITTED FROM A FAST-NEUTRON SOURCE BY CADMIUM AND INDIUM PLATES PLACED IN AN AQUEOUS MEDIUM  

Microsoft Academic Search

Following up previous work on the In--Ga loop of the IRT reactor, ; involving the estimation of the activation of the in--Ga alloy, a supplementary ; problem was considered. It consisted of the calculation of the absorption ; probability of the neutrons emitted by- a flat, infinite, and uniform fast ; neutron source in a parallel layer which was black

V. A. Eltekov; Yu. S. Ryabukhin

1962-01-01

374

Assessment of restrictions imposed by neutron irradiation on the workability of a copper conductor in volumetric neutron source coils  

Microsoft Academic Search

The paper presents the results of the analysis of the irradiation conditions and the quantitative estimation of factors that control the lifetime of copper alloys as materials for a conductor in volumetric neutron source coils, as well the results of the analysis of the effect of neutron irradiation at Tirr?=?100C on the mechanical properties and electrical conductivity of copper alloys

S. A. Fabritsiev; E. A. Azizov; A. B. Mineev; V. A. Korotkov

2005-01-01

375

Plans for a collaboratively developed distributed control system for the Spallation Neutron Source  

Microsoft Academic Search

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 ion source followed by a 2.5 MeV RFQ; a 1 GeV linac; a storage ring; a 1 MW spallation neutron target (upgradeable to 2 MW); the conventional facilities

W. R. DeVan; D. P. Gurd; J. Hammonds; S. A. Lewis; J. D. Smith

1999-01-01

376

A clean, bright, and versatile source of neutron decay products  

Microsoft Academic Search

We present a case study on a new type of beam station for the measurement of angular correlations in the ?-decay of free neutrons. This beam station, called proton and electron radiation channel (PERC), is a cold-neutron guide that delivers at its open end, instead of neutrons, a beam of electrons and protons from neutron decays that take place far

D. Dubbers; H. Abele; S. Baeler; B. Mrkisch; M. Schumann; T. Soldner; O. Zimmer

2008-01-01

377

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

378

Optimisation of the neutron source based on gas dynamic trap for transmutation of radioactive wastes  

NASA Astrophysics Data System (ADS)

The Budker Institute of Nuclear Physics in collaboration with the Russian and foreign organizations develop the project of 14 MeV neutron source, which can be used for fusion material studies and for other application. The projected neutron source of plasma type is based on the plasma Gas Dynamic Trap (GDT), which is a special magnetic mirror system for plasma confinement. Presented work continues the subject of development the GDT-based neutron source (GDT-NS) for hybrid fusion-fission reactors. The paper presents the results of recent numerical optimization of such neutron source for transmutation of the long-lives radioactive wastes in spent nuclear fuel.

Anikeev, Andrey V.

2012-06-01

379

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 130 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

380

Pre-conceptual design and preliminary neutronic analysis of the proposed National Spallation Neutron Source (NSNS)  

SciTech Connect

The Department of Energy (DOE) has initiated a pre-conceptual design study for the National Spallation Neutron Source (NSNS) and given preliminary approval for the proposed facility to be built at Oak Ridge National Laboratory (ORNL). The pre-conceptual design of the NSNS initially consists of an accelerator system capable of delivering a 1 to 2 GeV proton beam with 1 MW of beam power in an approximate 0.5 {micro}s pulse at a 60 Hz frequency onto a single target station. The NSNS will be upgradable to a significantly higher power level with two target stations (a 60 Hz station and a 10 Hz station). There are many possible layouts and designs for the NSNS target stations. This paper gives a brief overview of the proposed NSNS with respect to the target station, as well as the general philosophy adopted for the neutronic design of the NSNS target stations. A reference design is presented, and some preliminary neutronic results for the NSNS are briefly discussed.

Johnson, J.O.; Barnes, J.M.; Charlton, L.A. [Oak Ridge National Lab., TN (United States). Computational Physics and Engineering Div.

1997-03-01

381

A Project of Boron Neutron Capture Therapy System based on a Proton Linac Neutron Source  

NASA Astrophysics Data System (ADS)

At present, the clinical trials of Boron Neutron Capture Therapy (BNCT) are being performed at research reactor facilities. However, an accelerator based BNCT has a merit that it can be built in a hospital. So, we just launched a development project for the BNCT based on an accelerator in order to establish and to spread the BNCT as an effective therapy in the near future. In the project, a compact proton linac installed in a hospital will be applied as a neutron source, and energy of the proton beam is planned to be less than about 10 MeV to reduce the radioactivity. The BNCT requires epithermal neutron beam with an intensity of around 1x109 (n/cm2/sec) to deliver the therapeutic dose to a deeper region in a body and to complete the irradiation within an hour. From this condition, the current of the proton beam required is estimated to be a few mA on average. Enormous heat deposition in the target is a big issue. We are aiming at total optimization of the accelerator based BNCT from the linac to the irradiation position. Here, the outline of the project is introduced and the moderator design is presented.

Kiyanagi, Yoshikai; Asano, Kenji; Arakawa, Akihiro; Fukuchi, Shin; Hiraga, Fujio; Kimura, Kenju; Kobayashi, Hitoshi; Kubota, Michio; Kumada, Hiroaki; Matsumoto, Hiroshi; Matsumoto, Akira; Sakae, Takeji; Saitoh, Kimiaki; Shibata, Tokushi; Yoshioka, Masakazu

382

Calculations of anisotropy factors for radionuclide neutron sources due to scattering from source encapsulation and support structures.  

PubMed

A model has been developed for calculating the angular neutron fluence distributions for radionuclide neutron sources that are heavily encapsulated or surrounded by source support structures as a source holder and a source movement system. These structures may cause an anisotropic neutron fluence distribution. This should be taken into account in the neutron-measuring instruments calibration procedure. The calculations were made for two types of widely used neutron sources, (241)Am-Be and (252)Cf, by combining an in-house code simulating the (9)Be(alpha,n) reactions and the Monte Carlo code MCNP-4C. As a result, anisotropy factors in the direction perpendicular to the source capsule axis for bare neutron sources were evaluated to be 1.012, 1.030 and 1.039 for (252)Cf in a standard Amersham X1 capsule, (241)Am-Be in a X3 capsule and (241)Am-Be in a X4 capsule, respectively. These values are in reasonable agreement with the published data. If the support structures are included in the MCNP simulation, the anisotropy factors for these neutron sources increase by approximately 10%. PMID:17575299

Tsujimura, N; Yoshida, T; Momose, T

2007-01-01

383

Prompt-gamma neutron activation analysis system design: Effects of DT versus D-D neutron generator source selection  

Microsoft Academic Search

Prompt-gamma neutron activation (PGNA) analysis is used for the non-invasive measurement of human body composition. Advancements\\u000a in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators\\u000a are available: D-D with 2.5 MeV and D-T with 14.2 MeV neutrons. To compare the performance of these two units in our present\\u000a PGNA system, we performed

R. J. Shypailo; K. J. Ellis

2008-01-01

384

Neutron and Gamma-Ray Environments for Point Neutron Sources in an Air-Over-Ground Geometry. Volume I.  

National Technical Information Service (NTIS)

A complete graphical presentation is given of an Oak Ridge transport calculation of the nuclear environment at the air-earth interface generated by point sources of monoenergetic neutrons. Monte Carlo methods were employed in the calculations (computer co...

R. L. Beck W. W. Brown

1971-01-01

385

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

386

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

387

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

388

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

389

Spallation Neutron Source Accelerator Facility Target Safety and Non-safety Control Systems  

Microsoft Academic Search

Abstract - The Spallation Neutron Source (SNS) is a proton accelerator facility that generates neutrons for scientific researchers by spallation of neutrons from a mercury target. The SNS became operational on April 28, 2006, with first beam on target at approximately 200 W. The SNS accelerator, target, and conventional facilities controls are integrated by standardized hardware and software throughout the

Battle; Ronald E

2006-01-01

390

Physics data base for the beam plasma neutron source (BPNS)  

SciTech Connect

A 14-MeV deuterium-tritium (D-T) neutron source for accelerated end-of-life testing of fusion reactor materials has been designed on the basis of a linear two-component collisional plasma system. An intense flux (up to 5 {times} 10{sup 18}/m{sup 2}{center dot}s) of 14-MeV neutrons is produced in a fully ionized high-density (n{sub e} {approx equal} 3 {times} 10{sup 21} m{sup {minus}3}) tritium target by transverse injection of 60 MW of neutral beam power. Power deposited in the target is removed by thermal electron conduction to large end chambers, where it is deposited in gaseous plasma collectors. We show in this paper that the major physics issues have now been experimentally demonstrated. These include magnetohydrodynamic (MHD) equilibrium and stability, microstability, startup, fueling, Spitzer electron thermal conductivity, and power deposition in a gaseous plasma collector. However, an integrated system has not been demonstrated. 28 refs., 8 figs., 2 tabs.

Coensgen, F.H.; Casper, T.A.; Correll, D.L.; Damm, C.C.; Futch, A.H.; Molvik, A.W.

1990-10-12

391

Advanced Neutron Source (ANS) Project progress report, FY 1994  

SciTech Connect

The President`s budget request for FY 1994 included a construction project for the Advanced Neutron Source (ANS). However, the budget that emerged from the Congress did not, and so activities during this reporting period were limited to continued research and development and to advanced conceptual design. A significant effort was devoted to a study, requested by the US Department of Energy (DOE) and led by Brookhaven National Laboratory, of the performance and cost impacts of reducing the uranium fuel enrichment below the baseline design value of 93%. The study also considered alternative core designs that might mitigate those impacts. The ANS Project proposed a modified core design, with three fuel elements instead of two, that would allow operation with only 50% enriched uranium and use existing fuel technology. The performance penalty would be 15--20% loss of thermal neutron flux; the flux would still just meet the minimum design requirement set by the user community. At the time of this writing, DOE has not established an enrichment level for ANS, but two advisory committees have recommended adopting the new core design, provided the minimum flux requirements are still met.

Campbell, J.H.; King-Jones, K.H. [eds.; 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). Central Engineering Services

1995-01-01

392

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

393

The project of ultracold neutron sources at the PIK reactor with superfluid helium as a moderator  

NASA Astrophysics Data System (ADS)

The project of ultracold neutron sources at the PIK reactor with superfluid helium as a moderator is presented. The rate of producing ultracold neutrons in superfluid helium is 100 cm-3 s-1 at neutron flux density ?(? = 9 ) = 109 cm-2 s-1 -1. At a moderator temperature of 1 K within the experimental volume of 351, the density of ultracold neutrons may be equal to 1.3 103 cm-3, which is two orders of magnitude exceeds that the currently existing ultracold neutron sources.

Serebrov, A. P.; Fomin, A. K.; Onegin, M. S.; Kharitonov, A. G.; Prudnikov, D. V.; Lyamkin, V. A.; Ivanov, S. A.

2014-01-01

394

The Solution of Cold Neutron Source using Solid Methane Moderator for the CPHS  

NASA Astrophysics Data System (ADS)

The Compact Pulsed Hadron Source (CPHS) at Tsinghua University will produce neutrons by bombarding a 13-MeV proton beam from a LINAC system on a beryllium target. One of the purposes of this neutron source is to provide the neutron facilities for characterization of advanced materials with an emphasis on soft matter and biological systems, for which high cold-neutron fluxes are essential. The design and optimization of the solid-methane moderator system aim at the enhancement of cold neutron production. This paper describes the moderator configuration, the associated gas-handling and cryogenic apparatus, and the operation procedure.

Feng, Q. X.; Feng, Q. K.; Kawai, T.; Zhong, B.; Wei, J.; Loong, C.-K.; Liang, T. J.

395

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

396

STATUS OF THE SPALLATION NEUTRON SOURCE SUPERCONDUCTING RF FACILITIES  

SciTech Connect

The Spallation Neutron Source (SNS) project was completed with only limited superconducting RF (SRF) facilities installed as part of the project. A concerted effort has been initiated to install the infrastructure and equipment necessary to maintain and repair the superconducting Linac, and to support power upgrade research and development (R&D). Installation of a Class10/100/10,000 cleanroom and outfitting of the test cave with RF, vacuum, controls, personnel protection and cryogenics systems is underway. A horizontal cryostat, which can house a helium vessel/cavity and fundamental power coupler for full power, pulsed testing, is being procured. Equipment for cryomodule assembly and disassembly is being procured. This effort, while derived from the experience of the SRF community, will provide a unique high power test capability as well as long term maintenance capabilities. This paper presents the current status and the future plans for the SNS SRF facilities.

Stout, Daniel S [ORNL] [ORNL; Assadi, Saeed [ORNL] [ORNL; Campisi, Isidoro E [ORNL] [ORNL; Casagrande, Fabio [ORNL] [ORNL; Crofford, Mark T [ORNL] [ORNL; DeVan, Bill [ORNL] [ORNL; Hardek, Thomas W [ORNL] [ORNL; Henderson, Stuart D [ORNL] [ORNL; Howell, Matthew P [ORNL] [ORNL; Kang, Yoon W [ORNL] [ORNL; Geng, Xiaosong [ORNL] [ORNL; Stone Jr, William C [ORNL] [ORNL; Strong, William Herb [ORNL] [ORNL; Williams, Derrick C [ORNL] [ORNL; Wright, Paul Alan [ORNL] [ORNL

2007-01-01

397

BEAM INSTRUMENTATION FOR THE SPALLATION NEUTRON SOURCE RING.  

SciTech Connect

The Spallation Neutron Source (SNS) will be constructed by a multi-laboratory collaboration with BNL responsible for the transfer lines and ring. [1] The 1 MW beam power necessitates careful monitoring to minimize un-controlled loss. This high beam power will influence the design of the monitors in the high energy beam transport line (HEBT) from linac to ring, in the ring, and in the ring-to-target transfer line (RTBT). The ring instrumentation must cover a 3-decade range of beam intensity during accumulation. Beam loss monitoring will be especially critical since un-controlled beam loss must be kept below 10{sup -4}. A Beam-In-Gap (BIG) monitor is being designed to assure out-of-bucket beam will not be lost in the ring.

WITKOVER,R.L.; CAMERON,P.R.; SHEA,T.J.; CONNOLLY,R.C.; KESSELMAN,M.

1999-03-29

398

Operation of the superconducting linac at the spallation neutron source  

SciTech Connect

At the Spallation Neutron Source, the first fully operational pulsed superconducting linac has been active for about two years. During this period, stable beam operation at 4.4 K has been achieved with beam for repetition rates up to 15 Hz and 30 Hz at 2.1 K. At the lower temperature 60 Hz RF pulses have been also used. Full beam energy has been achieved at 15 Hz and short beam pulses. Most of the time the superconducting cavities are operated at somewhat lower gradients to improve reliability. A large amount of data has been collected on the pulsed behavior of cavities and SRF modules at various repetition rates and at various temperatures. This experience will be of great value in determining future optimizations of SNS as well in guiding in the design and operation of future pulsed superconducting linacs. This paper describes the details of the cryogenic system and RF properties of the SNS superconducting linac.

Campisi, Isidoro E [ORNL; Casagrande, Fabio [ORNL; Champion, Mark S [ORNL; Howell, Matthew P [ORNL; Kang, Yoon [ORNL; Kim, Sang-Ho [ORNL; Kursun, Zafer [ORNL; Ladd, Peter [ORNL; Stout, Daniel S [ORNL; Strong, William Herb [ORNL

2008-01-01

399

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

400

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; Ball, Jeffrey Allen [ORNL; Crofford, Mark T [ORNL; Davidson Jr, Taylor L [ORNL; Jones, Stacey L [ORNL; Hardek, Thomas W [ORNL

2010-01-01

401

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

402

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

403

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

404

Room-temperature LINAC structures for the spallation neutron source  

SciTech Connect

Los Alamos National Laboratory is building room-temperature rf accelerating structures for the Spallation Neutron Source (SNS). These structures, for H{sup -} ions, consist of six 402.5-MHz, 2-MW drift-tube linac (DTL) tanks from 2.5 to 87 MeV followed by four 805-MHz, 4-MW coupled-cavity linac (CCL) modules to 186 MeV. The DTL uses permanent magnet quadrupoles inside the drift tubes arranged in a 6{beta}{lambda} FFODDO lattice with every third drift tube available for diagnostics and steering. The CCL uses a 13{beta}{lambda} FODO electromagnetic quadrupole lattice. Diagnostics and magnets occupy the 2.5{beta}{lambda} spaces between 8-cavity segments. This paper discusses design of the rf cavities and low-power modeling work.

Billen, J. H. (James H.); Young, L. M. (Lloyd M.); Kurennoy, S. (Sergey); Crandall, K. R. (Kenneth R.)

2001-04-01

405

ROOM-TEMPERATURE LINAC STRUCTURES FOR THE SPALLATION NEUTRON SOURCE  

SciTech Connect

Los Alamos National Laboratory is building room-temperature rf accelerating structures for the Spallation Neutron Source (SNS). These structures, for H{sup {minus}} ions, consist of six 402.5-MHz, 2-MW drift-tube linac (DTL) tanks from 2.5 to 87 MeV followed by four 805-MHz, 4-MW coupled-cavity linac (CCL) modules to 186 MeV. The DTL uses permanent magnet quadrupoles inside the drift tubes arranged in a 6{beta}{lambda} FFODDO lattice with every third drift tube available for diagnostics and steering. The CCL uses a 13{beta}{lambda} FODO electromagnetic quadrupole lattice. Diagnostics and magnets occupy the 2.5{beta}{lambda} spaces between 8-cavity segments. This paper discusses design of the rf cavities and low-power modeling work.

J. H. BILLEN; L. M. YOUNG; ET AL

2001-04-01

406

The front-end systems for the spallation neutron source  

NASA Astrophysics Data System (ADS)

The Front-End Systems (FES) of the Spallation Neutron Source (SNS) project are being built by Berkeley Lab and will deliver a 52-mA H- ion beam at 2.5 MeV energy to the subsequent Drift-Tube Linac, to be built by Los Alamos National Laboratory. The FES comprise a volume-production, cesium-enhanced Ion Source, an electrostatic Low-Energy Beam Transport (LEBT), and RFQ accelerator, and a Medium-Energy Beam Transport (MEBT) that includes rebuncher cavities, magnetic quadrupoles, and beam diagnostics. The macro-pulse duty factor is 6%, and the macro pulses have to be chopped into a minipulse structure with a time scale of hundreds of ns, to reduce beam losses and component activation during extraction from the SNS Accumulator Ring. Delivery of the entire FES to the main SNS facility in Oak Ridge is planned for April 2002. This paper discusses the design features and status of the major FES subsystems with special emphasis on Ion Source and LEBT for which first experimental results have been obtained. After successful completion, the FES could be viewed as a prototype of a high-current, high duty-factor injector for other accelerator projects or, without the elaborate MEBT, as an independent 2.5-MeV accelerator for various applications. .

Keller, Roderich

2001-07-01

407

Experimental and numerical characterization of the neutron field produced in the n@BTF Frascati photo-neutron source  

NASA Astrophysics Data System (ADS)

A photo-neutron irradiation facility is going to be established at the Frascati National Laboratories of INFN on the base of the successful results of the n@BTF experiment. The photo-neutron source is obtained by an electron or positron pulsed beam, tuneable in energy, current and in time structure, impinging on an optimized tungsten target located in a polyethylene-lead shielding assembly. The resulting neutron field, through selectable collimated apertures at different angles, is released into a 100 m 2 irradiation room. The neutron beam, characterized by an evaporation spectrum peaked at about 1 MeV, can be used in nuclear physics, material science, calibration of neutron detectors, studies of neutron hardness, ageing and study of single event effect. The intensity of the neutron beam obtainable with 510 MeV electrons and its fluence energy distribution at a point of reference in the irradiation room were predicted by Monte Carlo simulations and experimentally determined with a Bonner Sphere Spectrometer (BSS). Due to the large photon contribution and the pulsed time structure of the beam, passive photon-insensitive thermal neutron detectors were used as sensitive elements of the BSS. For this purpose, a set of Dy activation foils was used. This paper presents the numerical simulations and the measurements, and compares their results in terms of both neutron spectrum and total neutron fluence.

Bedogni, R.; Quintieri, L.; Buonomo, B.; Esposito, A.; Mazzitelli, G.; Foggetta, L.; Gmez-Ros, J. M.

2011-12-01

408

Calculations of helium production in materials irradiated at spallation neutron sources  

Microsoft Academic Search

Experience with materials irradiated in fission reactor neutron environments has shown that radiation-produced helium can exacerbate the degradation of properties caused by radiation-produced defects and defect clusters. Whereas fission-reactor neutron energies extend up to 10 MeV, the neutrons and protons at spallation neutron sources reach up to 1,000 to 2,000 MeV, and He production is much greater. For example, calculations

R. K. Corzine; D. J. Dudziak; M. S. Wechsler; M. H. Barnett; L. K. Mansur

1998-01-01

409

Neutron beam preparation with AmBe source for analysis of biological samples with PGNAA method  

Microsoft Academic Search

Material analysis with prompt gamma neutron activation analysis (PGNAA) requires a proper geometrical arrangement for equipments\\u000a in laboratory. Application of PGNAA in analysis of biological samples, due to small size of sample, needs attention to the\\u000a dimension of neutron beam. In our work, neutron source has been made of 241AmBe type. Activity of 241Am was 20Ci which lead to neutron

P. Ghorbani; D. Sardari; E. Bayat; V. Doostmohammadi

410

A proposed measurement of the asymmetry in neutron decay with the Los Alamos Ultra-Cold Neutron Source  

NASA Astrophysics Data System (ADS)

This article reviews the status of an experiment to study the neutron spin-electron angular correlation with the Los Alamos Ultra-Cold Neutron (UCN) source. The experiment will generate UCNs from a novel solid deuterium, spallation source, and polarize them in a solenoid magnetic field. The experiment spectrometer will consist of a neutron decay region in a solenoid magnetic field combined with several different detector possibilities. An electron beam and a magnetic spectrometer will provide a precise, absolute calibration for these detectors. An A-correlation measurement with a relative precision of 0.2% is expected by the end of 2002. .

Tipton, B.; Alduschenkov, A.; Asahi, K.; Bowles, T.; Filippone, B.; Fowler, M.; Geltenbort, P.; Hartmann, F.; Hill, R.; Hime, A.; Hino, M.; Hoedl, S.; Hogan, G.; Ito, T.; Jones, C.; Kawai, T.; Kharitonov, A.; Kirch, K.; Kitagaki, T.; Lamoreaux, S.; Lassakov, M.; Liu, C.-Y.; Makela, M.; Martin, J.; McKeown, R.; Morris, C.; Pichlmaier, A.; Pitt, M.; Rudnev, Yu.; Saunders, A.; Seestrom, S.; Serebrov, A.; Smith, D.; Soyama, K.; Utsuro, M.; Vasilev, A.; Vogelaar, B.; Walstrom, P.; Wilhelmy, J.; Young, A. R.; Yuan, J.

2000-10-01

411

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

PubMed

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 1 m. A central problem is the design of the beam geometry, especially the layout of the collimator and the aperture. Calculations were carried out in order to get an optimal beam geometry, taking into consideration an extended source, low beam divergency and high flux in the detector plane. PMID:15246387

Grnauer, F; Schillinger, B; Steichele, E

2004-10-01

412

High-Power Linac for the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

The Spallation Neutron Source (SNS) will be the worlds most intense source of neutrons for fundamental science and industrial applications. Design and construction of this facility, located at Oak Ridge, is a joint venture between six DOE laboratories. Construction began in 1999 and is currently ahead of the scheduled 2006 completion date. Injecting a high-power, pulsed proton beam into a mercury target produces neutrons. In this talk, we review the physics requirements, design, and status of the construction of the 1-GeV, 1.4-MW average power RF linac for SNS. The accelerator consists of a drift tube linac (DTL), a coupled-cavity linac (CCL), and a superconducting rf (SRF) linac. The phase and quadrupole settings are set to avoid structure and parametric resonances, with coherent resonances posing minimal risk for emittance growth. The DTL is 37 m long and accelerates the ions to 87 MeV. The CCL is 55 m long and accelerates the ions to 186 MeV. The rf structure design and stability for both the DTL and CCL have been validated with scale models. The SRF linac has a modular design to accelerate ions to 1000 MeV, with a straightforward upgrade to 1.3 GeV at a later date. 3D particle-in-cell simulations of beam dynamics are performed to validate performance. The accelerator utilizes 93 MW of pulsed power operating continuously at 60-Hz with an 8factor. Approximately one hundred 402.5 or 805-MHz klystrons, with outputs between 0.55 and 5 MW, are used. The klystrons are powered by a novel converter-modulator that takes advantage of recent advances in IGBT switch plate assemblies and low-loss material cores for boost transformer. Beam diagnostics include position, phase, profile, and current monitors. They are designed to enable accurate beam steering and matching, and to minimize beam loss that would lead to activation and prevent hands-on maintenance.

Rej, D. J.

2002-04-01

413

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

NASA Astrophysics Data System (ADS)

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

Lauss, B.; PSI UCN Project Team

2011-09-01

414

Neutron noise transmission characteristics of multiplying media and neutron noise source localization in liquid-metal fast breeder reactors by using the neutron wave propagation technique  

Microsoft Academic Search

The results of a theoretical study of noise transmission characteristics of multiplying media and neutron noise source localization in liquid-metal fast breeder reactors (LMFBRs) by using the neutron wave propagation technique is reported. The study was carried out using one-group as well as multigroup diffusion theory. Both theories show that the noise transmission characteristics are quite sensitive to the multiplication

T. M. John; O. P. Singh

1983-01-01

415

Spectrum shaping assessment of accelerator-based fusion neutron sources to be used in BNCT treatment  

NASA Astrophysics Data System (ADS)

Monte Carlo modelling of an irradiation facility, for boron neutron capture therapy (BNCT) application, using a set of advanced type, accelerator based, 3H(d,n) 4He (D-T) fusion neutron source device is presented. Some general issues concerning the design of a proper irradiation beam shaping assembly, based on very hard energy neutron source spectrum, are reviewed. The facility here proposed, which represents an interesting solution compared to the much more investigated Li or Be based accelerator driven neutron source could fulfil all the medical and safety requirements to be used by an hospital environment.

Cerullo, N.; Esposito, J.; Daquino, G. G.

2004-01-01

416

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

417

Powerful pulsed neutron sources for research with a pulsed magnetic field  

Microsoft Academic Search

The prospects for neutron investigations into the magnetic properties of condensed matter with the use of powerful pulsed\\u000a neutron sources [Japan Spallation Neutron Source (JSNS) (Tokai, Japan), TIRAN (Zababakhin All-Russia Research Institute of\\u000a Technical Physics, Russian Federal Nuclear Center, Snezhinsk, Russia), Large Hadron Collider (LHC) (CERN)] and pulsed magnetic\\u000a fields are considered. It is demonstrated that the diffraction measurements of

V. V. Nietz

2008-01-01

418

Thermophysical properties of saturated light and heavy water for Advanced Neutron Source applications  

Microsoft Academic Search

The Advanced Neutron Source is an experimental facility being developed by Oak Ridge National Laboratory. As a new nuclear fission research reactor of unprecedented flux, the Advanced Neutron Source Reactor will provide the most intense steady-state beams of neutrons in the world. The high heat fluxes generated in the reactor [303 MW(t) with an average power density of 4.5 MW\\/L

A. Crabtree; M. Siman-Tov

1993-01-01

419

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

420

Compact tokamaks as convenient neutron sources for fusion reactors materials testing  

Microsoft Academic Search

Radiation damage evaluations have been performed with the ACAB code for fusion-relevant materials in an Ignitor-like compact fusion device that could be used as a neutron source for materials testing. Values ranging from 1.610?26 to 2.410?25dpa per source neutron have been obtained, which translates into 16250dpa\\/y at full operating power and demonstrates the potential of this neutron-rich device for fusion

F. Bombarda; B. Coppi; Z. S. Hartwig; M. Sassi; M. Zucchetti

2011-01-01

421

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

422

Optimizing a three-element core design for the advanced neutron source reactor  

Microsoft Academic Search

The source of neutrons in the proposed Advanced Neutron Source facility is a multipurpose research reactor providing 5 to 10 times the flux, for neutron beams, of the best existing facilities. The project team constrained the design with the {open_quotes}no new inventions rule,{close_quotes} which states that the design should not rely on the development of new technology to meet the

1995-01-01

423

Fission Reactor Neutron Sources for Neutron Capture Therapy A Critical Review  

Microsoft Academic Search

The status of fission reactor-based neutron beams for neutron capture therapy (NCT) is reviewed critically. Epithermal neutron beams, which are favored for treatment of deep-seated tumors, have been constructed or are under construction at a number of reactors worldwide. Some of the most recently constructed epithermal neutron beams approach the theoretical optimum for beam purity. Of these higher quality beams,

Otto K. Harling; Kent J. Riley

2003-01-01

424

Concept and characteristics of a simulated line source for annular blanket experiments using an accelerator-based deuterium-tritium neutron source  

Microsoft Academic Search

A pseudoline source is realized by using an accelerator-based deuterium-tritium point-neutron source. The pseudoline source is obtained by time averaging of the continuously moving point source or by superposition of the finely distributed point sources. The line source is utilized for fusion blanket neutronics experiments with an annular geometry to simulate a part of a tokamak reactor. The source neutron

Y. Oyama; C. Konno; Y. Ikeda

1995-01-01

425

Fast-Neutron Source Based on Plasma-Focus Device  

Microsoft Academic Search

This paper describes investigations of neutrons produced by small plasma focus device PF-6 operating in the Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland. Main parameters of neutron radiation have been measured by scintillation probe, and by activation technique. Current derivative probe has also been applied to measure dI\\/dt signal. Simultaneously neutron transport calculations have been carried out by

M. Scholz; B. Bienkowska; M. Chernyshova; V. A. Gribkov; S. Jednorog; Z. Kalinowska; L. Karpinski; M. Paduch; R. Prokopowicz; A. Szydlowski

2008-01-01

426

Fission diamond detector tests at the ISIS spallation neutron source  

Microsoft Academic Search

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

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

2011-01-01

427

Shielding analysis and design of the KIPT experimental neutron source facility of Ukraine  

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 an experimental neutron source facility based on the use of an electron accelerator driven subcritical (ADS) facility [1]. The facility uses the existing electron accelerators of KIPT in Ukraine. The neutron source of the sub-critical

Z. Zhong; M. Y. A. Gohar; D. Naberezhnev; J. Duo

2008-01-01

428

Final Report on Seed Money Project 3210-0346: Feasibility Study for Californium Cold Neutron Source.  

National Technical Information Service (NTIS)

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 sup 252 Cf capsules, each containing 50 mg of the isotope produced in t...

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

1988-01-01

429

A first step in the development of a powerful 14 MeV neutron source  

NASA Astrophysics Data System (ADS)

This paper reviews the latest results of the numerical optimization of the powerful 14 MeV neutron source based on gas dynamic trap (GDT). Further experiments on the existing GDT device in Novosibirsk, which are planned to prove the key physical issues of the plasma confinement in the neutron source, are also discussed here.

Ivanov, A. A.; Kruglyakov, E. P.; Tsidulko, Yu. A.

2002-12-01

430

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

431

Risk minimization using PRA (probabilistic risk analysis) in preconceptual design for the advanced neutron source reactor  

Microsoft Academic Search

The advanced neutron source (ANS) reactor being designed at Oak Ridge National Laboratory (ORNL) for the 1990s will be the worlds best source of low-energy neutrons for materials studies, physics research, transplutonium production, and radiation effects. Probabilistic risk analysis (PRA) is one of the tools being used for safety and operational optimization. The ANS is currently in preconceptual design. This

R. Fullwood; W. Shier

1990-01-01

432

LOW LOSS DESIGN OF THE LINAC AND ACCUMULATOR RING FOR THE SPALLATION NEUTRON SOURCE  

Microsoft Academic Search

The Spallation Neutron Source (SNS) is a second generation pulsed neutron source and is presently in the fourth year of a seven-year construction cycle at Oak Ridge National Laboratory. A collaboration of six national laboratories (ANL, BNL, LANL, LBNL, ORNL, TJNAF) is responsible for the design and construction of the various subsystems. The operation of the facility will begin in

2003-01-01

433

Operational Experiences of Fast Neutron Source Reactor YAYOI as Pulsed Fast Reactor  

Microsoft Academic Search

University of Tokyo research reactor YAYOI is intended to be operated as a dynamic fast neutron source reactor as well as a stationary one. It is equipped with reactivity adding devices with both slow and quick action, and a LINAC PNS (Pulsed Neutron Source) to be operated with the devices mentioned above. The unique idea of fly-through type pulse reactivity

Hiroaki WAKABAYASHI; Isao SAITO; Takaaki TAMURA; Shigehiro AN

1981-01-01

434

Startup neutron source strength evaluation of Three Mile Island Unit 1 after extended shutdown  

Microsoft Academic Search

Three Mile Island Unit 1 (TMI-1) was shut down February 17, 1979, for refueling and went critical October 3, 1985 (2420 days later), without inserting any external neutron sources. The intrinsic neutron source strength was evaluated and confirmed in 1981 through analyses and supporting subcritical tests. Results showed TMI-1 could have performed a successful startup at least through 1990 without

J. D. Luoma; J. W. Folsom; W. W. Wilkerson

1986-01-01

435

Tokamak D T fusion neutron source requirements for closing the nuclear fuel cycle  

Microsoft Academic Search

This paper summarizes a series of conceptual design studies conducted with the purpose of determining if tokamak fusion neutron sources based on ITER physics and technology could meet the neutron source requirements for sub-critical fast-spectrum nuclear reactors that would help to close the nuclear fuel cycle by transmuting the transuranics in spent nuclear fuel. The studies were constrained to nuclear

W. M. Stacey

2007-01-01

436

SUBCRITICAL TRANSMUTATION REACTORS WITH TOKAMAK FUSION NEUTRON SOURCES BASED ON ITER PHYSICS AND TECHNOLOGY  

Microsoft Academic Search

A series of design scoping and fuel cycle studies for sub-critical fast transmutation reactors driven by tokamak fusion neutron sources has been carried out to determine if the requirements on the tokamak neutron sources are compatible with the fusion physics and technology design database that will exist after the operation of ITER and to determine if there is a significant

W. M. Stacey

437

Tokamak DT fusion neutron source requirements for closing the nuclear fuel cycle  

Microsoft Academic Search

This paper summarizes a series of conceptual design studies conducted with the purpose of determining if tokamak fusion neutron sources based on ITER physics and technology could meet the neutron source requirements for sub-critical fast-spectrum nuclear reactors that would help to close the nuclear fuel cycle by transmuting the transuranics in spent nuclear fuel. The studies were constrained to nuclear

W. M. Stacey

2007-01-01

438

Overview of the national spallation neutron source with emphasis on the target station  

SciTech Connect

The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.

Gabriel, T.A.; Barnes, J.N.; Charlton, L.A. [and others

1997-06-01

439

Mechanical Engineering of the Linac for the Spallation Neutron Source  

SciTech Connect

The linac for the Spallation Neutron Source (SNS) Project will accelerate an average current of 1 mA of H{sup {minus}} ions from 20 MeV to 1GeV for injection into an accumulator ring. The linac will be an intense source of H{sup {minus}} ions and as such requires advanced design techniques to meet project technical goals as well as to minimize costs. The DTL, CCDTL and CCL are 466m long and operate at 805 MHz with a maximum H{sup {minus}} input current of 28 mA and 7% rf duty factor. The Drift Tube Linac is a copper-plated steel structure using permanent magnetic quadrupoles. The Coupled-Cavity portions are brazed copper structures and use electromagnetic quads. RF losses in the copper are 80 MW, with total rf power supplied by 52 klystrons. Additionally, the linac is to be upgraded to the 2- and 4-MW beam power levels with no increase in duty factor. The authors give an overview of the linac mechanical engineering effort and discuss the special challenges and status of the effort.

Bultman, N.K.; Chen, Z.; Collier, M.; Erickson, J.L.; Guthrie, A.; Hunter, W.T.; Ilg, T.; Meyer, R.K.; Snodgrass, N.L.

1999-03-29

440

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

441

SINQ-the spallation neutron source, a new research facility at PSI  

NASA Astrophysics Data System (ADS)

SINQ is a steady state neutron source. Its concept is optimized for the highest possible neutron flux that can be generated from the available beam power. This source is fed by the PSI cyclotron accelerator system used for particle and nuclear physics, medical applications and an ever increasing portion of condensed matter -and material-science. With the beam power approaching 1 MWatt, SINQ is equivalent to a medium flux reactor for thermal neutrons. With our emphasis on cold neutrons, we have optimized the cold moderator and the neutron beam transport system (supermirrors) to the instruments. In this spectral region the source becomes competitive with high flux facilities. We present the set up and the expected performance of the source (if possible first results of actual beam measurements may be available at the time). Furthermore we give an outlook on the set of spectrometers at the source.

Fischer, W. E.

1997-02-01

442

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

Microsoft Academic Search

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

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

2009-01-01

443

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

444

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

445

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, 1020 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, Yanping; Garty, Guy; Marino, Stephen A.; Massey, Thomas N.; Randers-Pehrson, Gerhard; Johnson, Gary W.; Brenner, David J.

2012-01-01

446

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

447

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

448

Experimental progress on an ultra-cold neutron source at Los Alamos  

NASA Astrophysics Data System (ADS)

A program to develop a new ultra-cold neutron (UCN) source has been in progress at Los Alamos National Lab. In this source, neutrons are produced by the spallation process and are brought into the ultra-cold region by a superthermal process in solid deuterium. This source will be used for a proposed neutron beta decay asymmetry measurement. In this talk, the recent progress in our effort will be presented, including the experimental apparatus, the various methods utilized to characterize the performance of the source, and the most recent results, which will be followed by a detailed analysis presented in the succeeding talk.

Ito, T. M.; Filippone, B. W.; Martin, J.; Tipton, B.; Yuan, J.; Bowles, T.; Hill, R. E.; Hogan, G.; Kirch, K.; Lamoreaux, S.; Marek, L.; Morris, C. L.; Saunders, A.; Seestron, S. J.; Teasdale, W.; Hoedl, S.; Liu, C.-Y.; Smith, D. A.; Young, A. R.; Geltenbort, P.; Serebrov, A.

2000-04-01