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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

Neutron source  

DOEpatents

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

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

1975-10-21

3

NEUTRON SOURCES  

DOEpatents

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

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

1963-01-15

4

NEUTRON SOURCE  

DOEpatents

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

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

1959-01-13

5

NEUTRON SOURCE  

DOEpatents

An apparatus is described for producing neutrons through target bombardment with deuterons. Deuterium gas is ionized by electron bombardment and the deuteron ions are accelerated through a magnetic field to collimate them into a continuous high intensity beam. The ion beam is directed against a deuteron pervious metal target of substantially the same nnaterial throughout to embed the deuterous therein and react them to produce neutrons. A large quantity of neutrons is produced in this manner due to the increased energy and quantity of ions bombarding the target.

Bernander, N.K. et al.

1960-10-18

6

NEUTRON SOURCE  

DOEpatents

A compact electronic device capable of providing short time high density outputs of neutrons is described. The device of the invention includes an evacuated vacuum housing adapted to be supplied with a deuterium, tritium, or other atmosphere and means for establishing an electrical discharge along a path through the gas. An energized solenoid is arranged to constrain the ionized gas (plasma) along the path. An anode bearing adsorbed or adherent target material is arranged to enclose the constrained plasma. To produce neutrons a high voltage is applied from appropriate supply means between the plasma and anode to accelerate ions from the plasma to impinge upcn the target material, e.g., comprising deuterium.

Foster, J.S. Jr.

1960-04-19

7

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

8

The advanced neutron source  

Microsoft Academic Search

The Advanced Neutron Source (ANS), slated for construction start in 1994, will be a multipurpose neutron research laboratory serving academic and industrial users in chemistry, biology, condensed matter physics, nuclear and fundamental physics, materials science and engineering, and many other fields. It will be centered on the world`s highest flux neutron beam reactor, operating at 330 MW, with careful design

Hayter

1994-01-01

9

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

10

The advanced neutron source  

SciTech Connect

The Advanced Neutron Source (ANS) is a new user experimental facility planned to be operational at Oak Ridge in the late 1990's. The centerpiece of the ANS will be a steady-state research reactor of unprecedented thermal neutron flux ({phi}{sub th} {approx} 8 {times} 10{sup 19} m{sup {minus}2} {center dot}s{sup {minus}1}) accompanied by extensive and comprehensive equipment and facilities for neutron-based research.

Raman, S.; Hayter, J.B.

1990-01-01

11

FABRICATION OF NEUTRON SOURCES  

DOEpatents

A method is presented for preparing a neutron source from polonium-210 and substances, such as beryllium and boron, characterized by emission of neutrons upon exposure to alpha particles from the polonium. According to the invention, a source is prepared by placing powdered beryllium and a platinum foil electroplated with polonium-2;.0 in a beryllium container. The container is sealed and then heated by induction to a temperature of 450 to 1100 deg C to volatilize the polonium off the foil into the powder. The heating step is terminated upon detection of a maximum in the neutron flux level.

Birden, J.H.

1959-04-21

12

A femtosecond neutron source  

NASA Astrophysics Data System (ADS)

The possibility of using the ultrashort ion bunches produced by circularly polarized laser pulses to drive a source of fusion neutrons with sub-optical cycle duration is discussed. A two-sided irradiation of a deuterated thin foil target produces two counter-moving ion bunches, whose collision produces an ultrashort neutron burst. Using particle-in-cell simulations and analytical modeling, it is calculated that, for intensities of a few 1019 W cm-2, more than 103 neutrons per Joule may be producedwithin a time shorter than one femtosecond. Another scheme based on a layered deuterium-tritium target is outlined.

Macchi, A.

2006-03-01

13

Coded source neutron imaging  

SciTech Connect

Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100 m) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100um and 10um aperture hole diameters show resolutions matching the hole diameters.

Bingham, Philip R [ORNL; Santos-Villalobos, Hector J [ORNL

2011-01-01

14

Coded source neutron imaging  

NASA Astrophysics Data System (ADS)

Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100?m) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100?m and 10?m aperture hole diameters show resolutions matching the hole diameters.

Bingham, Philip; Santos-Villalobos, Hector; Tobin, Ken

2011-02-01

15

Intense neutron source  

SciTech Connect

A ScD/sub 2/ target film 5 x 10/sup -5/ m thick, tested in a UHV compatible 200 keV deuterium accelerator baked to 470/sup 0/C, maintained a D-D neutron output rate of 1.0-1.2x10'' /s for 80 out of 140 hours of operation. This result demonstrates that a D-T neutron generator capable of a neutron output rate of 1 x 10/sup 13//s and having a target lifetime suitable for cancer therapy is possible. Contrary to sputter rate data, ErD/sub 2/ target films appear to erode about twice as fast as ScD/sub 2/ films, making ErD/sub 2/ unsuitable as a target material. A low pressure ion source has been developed to replace the more complicated duopigatron. Experiments have verified that the single ring magnetic cusp ion source can deliver 200 mA of deuterium ions (approx. = 60% D/sup +/) at 10-15 A of arc current with a background deuterium pressure of 0.27-0.40 Pa. This source will improve the safety of a D-T machine by reducing the tritium inventory by a factor of 6, and by utilizing the Zr-Al getter as the gas reservoir.

Walko, R.J.; Brainard, J.P.; Riedel, A.A.; O'Hagan, J.B.; Bacon, F.M.

1982-01-01

16

Intense neutron source  

SciTech Connect

A ScD/sub 2/ target film 5x10/sup -5/ m thick, tested in a UHV compatible 200 keV deuterium accelerator baked to 470/sup 0/C, maintained a D-D neutron output rate of 1.0-1.2x10/sup 11//s for 80 out of 140 hours of operation. This result demonstrates that a D-T neutron generator capable of a neutron output rate of 1x10/sup 13//s and having a target lifetime suitable for cancer therapy is possible. Contrary to sputter rate data, ErD/sub 2/ target films appear to erode about twice as fast as ScD/sub 2/ films, making ErD/sub 2/ unsuitable as a target material. A low pressure ion source has been developed to replace the high pressure duopigatron. Experiments have verified that the single ring magnetic cusp ion source can deliver 200 mA of deuterium ions (approx. =60% D/sup +/) at 10-15 A of arc current with a background deuterium pressure of 0.27-0.40 Pa. This source will improve the safety of a D-T machine by reducing the tritium inventory by a factor of 6, and by utilizing the Zr-Al getter as the gas reservoir.

Walko, R.J.; Bacon, F.M.; Brainard, J.P.; O'Hagan, J.B.; Riedel, A.A.

1983-04-01

17

Spallation neutron source (SNS)  

NASA Astrophysics Data System (ADS)

The Spallation Neutron Source [1], located at Oak Ridge, TN, is a state-of-the-art neutron-scattering facility presently under construction as a collaborative effort of six national laboratories. The facility is comprised of a high-power particle-accelerator system, a liquid-mercury target-moderator system, and a suite of world-class scientific instruments. One-ms-long negative-hydrogen-ion (H-) pulses are produced by an ion source. The ion beam is accelerated to 185 MeV by normal conducting (NC) linear accelerator (linac) cavities, and further accelerated to 1 GeV by a superconducting linac [2]. The acceleration is accomplished by means of niobium superconducting radiofrequency (SRF) cavities that operate at 2.1K. The linac beam is stacked in a compressor ring, and 695-ns-long pulses are extracted onto the target at a 60-Hz rate. Neutrons are produced by spallation in the mercury, and their energy is moderated to useable levels, in part by supercritical hydrogen moderators. The simultaneous performance goals of more than one MW of initial proton beam power, 95% facility availability, and the desire for hands-on maintenance capability in the accelerator complex place significant demands on the performance and operational reliability of the technical and conventional systems. An overview of the SNS facility, including its purpose, major components, and a summary of the present status is presented, with particular emphasis on the superconducting linac and the cryogenic moderators. .

White, Marion M.; SNS Project

2002-05-01

18

Coaxial microwave neutron interrogation source  

NASA Astrophysics Data System (ADS)

A compact neutron generator is being developed based on a novel coaxial dipole permanent magnet electron cyclotron resonance (ECR) ion source. The ion source is capable of generating a high fraction of atomic ion species and can operate at low pressure. Multiple deuterium ion (D+) beamlets are extracted from the plasma ion source and accelerated to a beam-loaded titanium target creating 2.4 MeV neutrons as a result of the D-D fusion reaction at the target surface. This paper describes the design of the ECR-based neutron generator as well as reports on preliminary simulation and experimental results of the ion source performance.

Johnson, Will; Antolak, Arlyn; Leung, Ka-Ngo; Raber, Tom

2011-09-01

19

Fission neutron source in Rome  

Microsoft Academic Search

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,

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

1997-01-01

20

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

21

Next Generation Spallation Neutron Sources  

NASA Astrophysics Data System (ADS)

Neutron Scattering Experiments are traditionally done at nuclear reactors where high neutron fluxes are available from fission inside the reactor core. Naturally these are cw sources, which makes a whole class of time resolved experiments difficult to perform. Pulsed neutron sources, based on the spallation of neutrons by impinging an intense proton beam on a high atomic number target material, have therefore generated a large interest ever since they were put into operation. So far the typical integrated neutron flux is one or two orders of magnitude smaller than in a reactor. With the Spallation Neutron Source (SNS*) at Oak Ridge National Lab and the Japanese Hadron Project (J-PARC) at JAERI in Japan two second generation facilities are under construction that will provide average neutron fluxes exceeding those of reactors and peak fluxes that will allow new science to be done. The European Spallation Source, a project that still is in the planning stage, would even go beyond that. The talk will start out with the existing Spallation Sources and give an overview about the two construction projects focusing on the SNS presently foreseen to be finished in 2006. * SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge.

Holtkamp, Norbert

2004-05-01

22

Materials for spallation neutron sources  

SciTech Connect

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

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

1996-03-01

23

High Field Neutron Source Facility*  

NASA Astrophysics Data System (ADS)

Fusion creates more neutrons per energy released than fission or spallation, therefore DT fusion facilities have the potential to become the most intense sources of neutrons for material testing. An Ignitor-like device, that is a compact, high field, high density machine could be envisaged for this purpose making full use of the intense neutron flux that it can generate, without reaching ignition. The main features of this High Field Neutron Source Facility, which would have about 50% more volume than Ignitor, are illustrated and the R&D required in order to achieve relevant dpa quantities in the tested materials are discussed, in particular the adoption of superconducting magnet coils. Radiation damage evaluations have been performed by means of the ACAB code for some fusion-relevant materials, like pure iron, ASI316L, EUROFER, SiC/SiC, Mo, Graphite, V-15Cr-5Ti. Values ranging from 1.6 x10-26 to 2.4 x10-25 dpa per source neutron have been obtained. Some full-power months of operation are sufficient to obtain relevant radiation damage values in terms of dpa: the setup of a duty cycle for the device in order to obtain such operation times is the next required step to proceed with the evaluation. *Sponsored in part by ENEA of Italy and by the U.S. D.O.E.

Zucchetti, M.; Bombarda, F.; Ramogida, G.; Coppi, B.; Hartwig, Z.

2010-11-01

24

FIGARO : measuring neutron emission spectra with a white neutron source /.  

SciTech Connect

Neutron emission spectra from reactions induced by fast neutrons are of importance in basic physics and applications. Very few data are available in the literature over a wide range of incident neutron energies such as produced with a white neutron source. The FIGARO facility at the WNR/LANSCE neutron source has been established to measure such neutron emission over a range of incident neutron energies from 1 to over 100 MeV. Using the time-of-flight technique twice (once to determine the incident neutron energy and again to determine the outgoing neutron energy), we are measuring neutron emission spectra for several reactions such as (n,n') and (n,f). Neutron emission from inelastic scattering gives information on the level density of excited states of the target nucleus. Our first measurements are on structural materials such as iron.

Haight, Robert C.; O'Donnell, J. M.; Zanini, L.; Devlin, M.; Rochman, D. (Dimitri)

2002-01-01

25

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

26

The advanced neutron source reactor: An overview  

Microsoft Academic Search

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

1990-01-01

27

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

28

A National Spallation Neutron Source for neutron scattering  

SciTech Connect

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

Appleton, B.R.

1996-10-01

29

THE SPALLATION NEUTRON SOURCE PROJECT - PHYSICAL 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.

2002-06-03

30

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

31

Advanced Neutron Source operating philosophy  

SciTech Connect

An operating philosophy and operations cost estimate were prepared to support the Conceptual Design Report for the Advanced Neutron Source (ANS), a new research reactor planned for the Oak Ridge National Laboratory (ORNL). The operating philosophy was part of the initial effort of the ANS Human Factors Program, was integrated into the conceptual design, and addressed operational issues such as remote vs local operation; control room layout and responsibility issues; role of the operator; simulation and training; staffing levels; and plant computer systems. This paper will report on the overall plans and purpose for the operations work, the results of the work done for conceptual design, and plans for future effort.

Houser, M.M.

1993-03-01

32

Advanced Neutron Source operating philosophy  

SciTech Connect

An operating philosophy and operations cost estimate were prepared to support the Conceptual Design Report for the Advanced Neutron Source (ANS), a new research reactor planned for the Oak Ridge National Laboratory (ORNL). The operating philosophy was part of the initial effort of the ANS Human Factors Program, was integrated into the conceptual design, and addressed operational issues such as remote vs local operation; control room layout and responsibility issues; role of the operator; simulation and training; staffing levels; and plant computer systems. This paper will report on the overall plans and purpose for the operations work, the results of the work done for conceptual design, and plans for future effort.

Houser, M.M.

1993-01-01

33

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

34

Ion sources for sealed neutron tubes  

SciTech Connect

Fast and thermal neutron activation analysis with sealed neutron generators has been used to detect oil (oil logging), hazardous waste, fissile material, explosives, and contraband (drugs). Sealed neutron generators, used in the above applications, must be small and portable, have good electrical efficiency and long life. The ion sources used in the sealed neutron tubes require high gas utilization efficiencies or low pressure operation with high ionization efficiencies. In this paper, the authors compare a number of gas ion sources that can be used in sealed neutron tubes. The characteristics of the most popular ion source, the axial Penning discharge will be discussed as part of the zetatron neutron generator. Other sources to be discussed include the SAMIS source and RF ion source.

Burns, E.J.T. [Sandia National Labs., Albuquerque, NM (United States). Neutron Tube Dept.; Bischoff, G.C. [Lockheed Martin Specialty Components, Largo, FL (United States)

1996-11-01

35

Laser generated neutron source for neutron resonance spectroscopy  

SciTech Connect

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

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

2010-10-15

36

Laser generated neutron source for neutron resonance spectroscopy  

NASA Astrophysics Data System (ADS)

A neutron source for neutron resonance spectroscopy has been developed using high-intensity, short-pulse lasers. This technique will allow robust measurement of interior ion temperature of laser-shocked materials and provide insight into material equation of state. The neutron generation technique uses laser-accelerated protons to create neutrons in LiF through (p,n) reactions. The incident proton beam has been diagnosed using radiochromic film. This distribution is used as the input for a (p,n) neutron prediction code which is validated with experimentally measured neutron yields. The calculation infers a total fluence of 1.8×109 neutrons, which are expected to be sufficient for neutron resonance spectroscopy temperature measurements.

Higginson, D. P.; McNaney, J. M.; Swift, D. C.; Bartal, T.; Hey, D. S.; Kodama, R.; Le Pape, S.; MacKinnon, A.; Mariscal, D.; Nakamura, H.; Nakanii, N.; Tanaka, K. A.; Beg, F. N.

2010-10-01

37

SELF-REACTIVATING NEUTRON SOURCE FOR A NEUTRONIC REACTOR  

DOEpatents

Reactors of the type employing beryllium in a reflector region around the active portion and to a neutron source for use therewith are discussed. The neutron source is comprised or a quantity of antimony permanently incorporated in, and as an integral part of, the reactor in or near the beryllium reflector region. During operation of the reactor the natural occurring antimony isotope of atomic weight 123 absorbs neutrons and is thereby transformed to the antimony isotope of atomic weight 124, which is radioactive and emits gamma rays. The gamma rays react with the beryllium to produce neutrons. The beryllium and antimony thus cooperate to produce a built in neutron source which is automatically reactivated by the operation of the reactor itself and which is of sufficient strength to maintain the slow neutron flux at a sufficiently high level to be reliably measured during periods when the reactor is shut down.

Newson, H.W.

1959-02-01

38

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

39

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

40

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-producing efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: fundamental neutron-nuclear research, nuclear data acquisition, materials damage studies, engineering tests, and biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections. 90 refs., 4 figs.

Cierjacks, S.; Smith, A.B.

1988-01-01

41

(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

42

Spallation Neutron Source reaches megawatt power  

ScienceCinema

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

43

Neutron fan beam source for neutron radiography purpose  

SciTech Connect

The development of the DIANE neutron radiography system included a sealed-tube neutron generator for this purpose and the optimization of the system's neutron beam quality in terms of divergence and useful thermal neutron yield for each 14-MeV neutron produced. Following this development, the concept of a DIANE fan beam source is herewith introduced. The goal which drives this design is one of economy: by simply increasing the aperture dimension of a conventional DIANE beam in one plane of its collimator axis to a small-angle, fan-shaped output, the useful beam area for neutron radiography would be substantially increased. Thus with the same source, the throughput, or number of objects under examination at any given time, would be augmented significantly. Presented here are the design of this thermal neutron source and the initial Monte Carlo calculations. Taking into account the experience with the conventional DIANE neutron radiography system, these result are discussed and the potential of and interest in such a fan-beam source are explored.

Le Tourneur, P.; Bach, P.; Dance, W. E. [SODERN, 20, avenue Descartes, 94451 Limeil Brevannes (France); Consultant, Dallas, Texas (United States)

1999-06-10

44

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

45

Neutron dosimetry at SLAC: Neutron sources and instrumentation.  

National Technical Information Service (NTIS)

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...

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

1991-01-01

46

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

47

Observation of Neutron Skyshine from an Accelerator Based Neutron Source  

NASA Astrophysics Data System (ADS)

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

Franklyn, C. B.

2011-12-01

48

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

49

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

50

Neutron scattering instruments for the Spallation Neutron Source (SNS)  

SciTech Connect

The Spallation Neutron Source (SNS) is a 1 MW pulsed spallation source for neutron scattering planned for construction at Oak Ridge National Laboratory. This facility is being designed as a 5-laboratory collaboration project. This paper addresses the proposed facility layout, the process for selection and construction of neutron scattering instruments at the SNS, the initial planning done on the basis of a reference set of ten instruments, and the plans for research and development (R and D) to support construction of the first ten instruments and to establish the infrastructure to support later development and construction of additional instruments.

Crawford, R.K.; Fornek, T. [Argonne National Lab., IL (United States); Herwig, K.W. [Oak Ridge National Lab., TN (United States)

1998-07-01

51

Fission fragment driven neutron source  

DOEpatents

Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.

Miller, Lowell G. (Idaho Falls, ID); Young, Robert C. (Idaho Falls, ID); Brugger, Robert M. (Columbia, MO)

1976-01-01

52

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

53

Improved neutron sources for neutron capture enhanced fast neutron therapy  

SciTech Connect

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

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

2000-07-01

54

Status of the advanced neutron source facility  

Microsoft Academic Search

The Advanced Neutron Source (ANS) will be a new national user facility for all kinds of neutron research, based on a research reactor with an order of magnitude more flux than any now in service. A national steering committee representing universities, industry, and federal laboratories in a wide range of research fields provides guidance on the appropriate research facilities to

J. B. Hayter; P. B. Thompson; C. D. West

1992-01-01

55

Fast neutron capture with a white neutron source  

NASA Astrophysics Data System (ADS)

A system to measure gamma rays following fast neutron reactions was developed. The neutron beam is produced by bombarding a thick tantalum target with the 800 MeV proton beam from the LAMPF accelerator. Incident neutron energies, from 1 to over 200 MeV, are determined by their times of flight over a 7.6-m flight path. The gamma rays are detected in five 7.6 x 7.6 cm cylindrical bismuth germanate (BGO) detectors which span an angular range from 45(0) to 145(0) in the reaction plane. The system measures simultaneously the cross section and angular distribution of gamma rays as a function of neutron energy. The data for the (40)Ca(n,(GAMMA)0) reaction in the region of the giant dipole resonance demonstrate the unique capabilities of this system. Future developments to the neutron source which will enhance the capabilities of the system are presented.

Wender, S. A.; Auchampaugh, G. F.

56

Californium-252: A New Isotopic Source for Neutron Radiography  

SciTech Connect

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

Reinig, W.C.

2001-08-29

57

Simulation of pulsed neutron source reactivity measurements  

SciTech Connect

A model has been developed to simulate pulsed neutron source experiments which combines a Green`s function approach with the statistical samplings of the generation of neutrons by the source and the detection of them by the detector. The response pulse, measured by a multiscaler, is thus simulated allowing confirmation of experimental procedures and analysis of data for measuring the subcriticality of nuclear reactors. The results were applied to the preparation of experiments currently underway at the PROTEUS facility.

Difilippo, F.C. [Oak Ridge National Lab., TN (United States); Caro, M.; Williams, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1993-03-01

58

Simulation of pulsed neutron source reactivity measurements  

SciTech Connect

A model has been developed to simulate pulsed neutron source experiments which combines a Green's function approach with the statistical samplings of the generation of neutrons by the source and the detection of them by the detector. The response pulse, measured by a multiscaler, is thus simulated allowing confirmation of experimental procedures and analysis of data for measuring the subcriticality of nuclear reactors. The results were applied to the preparation of experiments currently underway at the PROTEUS facility.

Difilippo, F.C. (Oak Ridge National Lab., TN (United States)); Caro, M.; Williams, T. (Paul Scherrer Inst. (PSI), Villigen (Switzerland))

1993-01-01

59

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

2009-01-20

60

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

61

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

62

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

63

A telescope for monitoring fast neutron sources  

NASA Astrophysics Data System (ADS)

In the framework of nuclear waste management, highly radiotoxic long-lived fission products and minor actinides are planned to be transmuted in a sub-critical reactor coupled with an intense external neutron source. The latter source would be created by a high-energy proton beam hitting a high atomic number target. Such a new system, termed an accelerator-driven system (ADS), requires on-line and robust reactivity monitoring. The ratio between the beam current delivered by the accelerator and the reactor power level, or core neutron flux, is the basis of one method which could give access to a core reactivity change. In order to test reactivity measurement technique, some experimental programs use 14-MeV neutrons originating from the interaction of a deuteron beam with a tritium target as an external neutron source. In this case, the target tritium consumption over time precludes use of the beam current for reactivity monitoring and the external neutron source intensity must be monitored directly. A range telescope has been developed for this purpose, consisting of the assembly of a hydrogenous neutron converter and three silicon stages where the recoiling protons are detected. In this article, the performances of such a telescope are presented and compared to Monte-Carlo simulations.

Ban, G.; Fontbonne, J. M.; Lecolley, F. R.; Lecolley, J. F.; Lecouey, J. L.; Marie, N.; Steckmeyer, J. C.; Billebaud, A.; Brissot, R.; Le Brun, C.; Liatard, E.

2007-07-01

64

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

65

The PSI ultra-cold neutron source  

Microsoft Academic Search

A new type of ultra-cold neutron (UCN) source based on the spallation process is under construction at PSI. The essential elements are a pulsed proton beam with highest intensity (Ip?2mA) and a low duty cycle (1%), a lead spallation target, a large D2O moderator and a solid deuterium (sD2) converter system. Spallation neutrons are thermalized in the D2O, further cooled

A. Anghel; F. Atchison; B. Blau; B. van den Brandt; M. Daum; R. Doelling; M. Dubs; P.-A. Duperrex; A. Fuchs; D. George; L. Gültl; P. Hautle; G. Heidenreich; F. Heinrich; R. Henneck; S. Heule; Th. Hofmann; M. Kasprzak; K. Kirch; A. Knecht; J. A. Konter; T. Korhonen; M. Kuzniak; B. Lauss; A. Mezger; A. Mtchedlishvili; G. Petzoldt; A. Pichlmaier; D. Reggiani; R. Reiser; U. Rohrer; M. Seidel; H. Spitzer; K. Thomsen; W. Wagner; M. Wohlmuther; G. Zsigmond; J. Zuellig; K. Bodek; S. Kistryn; J. Zejma; P. Geltenbort; C. Plonka; S. Grigoriev

2009-01-01

66

Iterative Reconstruction of Coded Source Neutron Radiographs  

SciTech Connect

Use of a coded source facilitates high-resolution neutron imaging but requires that the radiographic data be deconvolved. In this paper, we compare direct deconvolution with two different iterative algorithms, namely, one based on direct deconvolution embedded in an MLE-like framework and one based on a geometric model of the neutron beam and a least squares formulation of the inverse imaging problem.

Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL; Gregor, Jens [University of Tennessee, Knoxville (UTK)

2012-01-01

67

Intense thermal neutron source based on MCF  

Microsoft Academic Search

The conceptual scheme of an ecologically clean thermal neutron source (TNS) based on muon-catalyzed fusion (MCF) is proposed. The preliminary design shows that an MCF-based TNS can produce the maximum value of unperturbed thermal neutron flux 1015 n\\/cm2 s using for muon production a beam power of about 14 MW supplied by an accelerator of the next generation.

V. V. Kuzminov; Yu. V. Petrov; E. G. Sakhnovsky

1996-01-01

68

Z-pinch plasma neutron sources  

SciTech Connect

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 {approx}3x10{sup 13}, 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 Y{sub n}{approx}I{sub m}{sup 4}, where I{sub m} 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 {approx}5x10{sup 16} and {approx}10{sup 18}, 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. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Chemical and Nuclear Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ktech Corporation, Albuquerque, New Mexico 87185 (United States); Icarus Research, Inc., Bethesda, Maryland 20824-0780 (United States)

2007-02-15

69

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

70

Iterative Reconstruction of Coded Source Neutron Radiographs  

SciTech Connect

Use of a coded source facilitates high-resolution neutron imaging through magnifications but requires that the radiographic data be deconvolved. A comparison of direct deconvolution with two different iterative algorithms has been performed. One iterative algorithm is based on a maximum likelihood estimation (MLE)-like framework and the second is based on a geometric model of the neutron beam within a least squares formulation of the inverse imaging problem. Simulated data for both uniform and Gaussian shaped source distributions was used for testing to understand the impact of non-uniformities present in neutron beam distributions on the reconstructed images. Results indicate that the model based reconstruction method will match resolution and improve on contrast over convolution methods in the presence of non-uniform sources. Additionally, the model based iterative algorithm provides direct calculation of quantitative transmission values while the convolution based methods must be normalized base on known values.

Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL; Gregor, Jens [University of Tennessee, Knoxville (UTK)

2013-01-01

71

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

EPA Science Inventory

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

72

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

73

``Fast neutron capture with a white neutron source''  

NASA Astrophysics Data System (ADS)

A system has been developed at the Los Alamos National Laboratory to measure gamma-rays following fast neutron reactions. The neutron beam is produced by bombarding a thick tantalum target with the 800 MeV proton beam from the LAMPF accelerator. Incident neutron energies, from 1 to over 200 MeV, are determined by their times of flight over a 7.6-m flight path. The gamma-rays are detected in five 7.6×7.6-cm cylindrical bismuth germanate (BGO) detectors which span an angular range from 45° to 145° in the reaction plane. With this system it is possible to simultaneously measure the cross section and angular distribution of gamma-rays as a function of neutron energy. The results for the cross section of the 12C(n,n'?=4.44 MeV) reaction at 90° and 125° show good agreement with previous measurements, while the complete angular distributions show the need for a large a4 coefficient which was not previously observed. Preliminary results for the 12C(n,n'?=15.1 MeV) reaction have also been obtained. The data obtained for the 40Ca(n,?0) reaction in the region of the giant dipole resonance demonstrate the unique capabilities of this system. Future developments to the neutron source which will enhance the capabilities of the system will be presented.

Wender, S. A.; Auchampaugh, G. F.

1985-01-01

74

SUPERCONDUCTING LINAC FOR THE SPALLATION NEUTRON SOURCE  

SciTech Connect

The Spallation Neutron Source (SNS) linac is comprised of both normal and superconducting rf (SRF) accelerating structures. The SRF linac accelerates the beam from 186 to 1250 MeV through 117 elliptical, multi-cell niobium cavities. This paper describes the SRF linac architecture, physics design considerations, cavity commissioning, and the expected beam dynamics performance.

J. STOVALL; S. NATH; ET AL

2000-10-01

75

New Steady State Medium Flux Neutron Source.  

National Technical Information Service (NTIS)

A new steady state neutron source is in operation on the Atomic Energy Commission Site of Saclay (France). It is a pool type nuclear reactor, using enriched uranium fuel elements together with a heavy water tank as moderator, and specially designed to pro...

B. Farnoux D. Cribier

1982-01-01

76

Neutron sources in Canada - Present and future  

Microsoft Academic Search

Canada's pre-eminent neutron source since 1957 has been the NRU reactor at Chalk River. It is unlikely to operate beyond the year 2005. In 1994, AECL prepared the case and concept for a new research reactor, the Irradiation Research Facility (IRF), to replace NRU. The IRF was developed with the dual purpose of meeting the needs of both R&D programs

G. Dolling; R. F. Lidstone

1998-01-01

77

Neutron sources in Canada — Present and future  

Microsoft Academic Search

Canada's pre-eminent neutron source since 1957 has been the NRU reactor at Chalk River. It is unlikely to operate beyond the year 2005. In 1994, AECL prepared the case and concept for a new research reactor, the Irradiation Research Facility (IRF), to replace NRU. The IRF was developed with the dual purpose of meeting the needs of both R&D programs

G Dolling; R. F Lidstone

1997-01-01

78

Spallation Neutron Source Radiation Shielding Issues  

Microsoft Academic Search

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 ⁷Be 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

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

1999-01-01

79

A telescope for monitoring fast neutron sources  

Microsoft Academic Search

In the framework of nuclear waste management, highly radiotoxic long-lived fission products and minor actinides are planned to be transmuted in a sub-critical reactor coupled with an intense external neutron source. The latter source would be created by a high-energy proton beam hitting a high atomic number target. Such a new system, termed an accelerator-driven system (ADS), requires on-line and

G. Ban; J. M. Fontbonne; F. R. Lecolley; J. F. Lecolley; J. L. Lecouey; N. Marie; J. C. Steckmeyer; A. Billebaud; R. Brissot; C. Le Brun; E. Liatard

2007-01-01

80

Neutron sources in nuclear astrophysics  

NASA Astrophysics Data System (ADS)

The excitations functions of the reactions 9Be((alpha) ,n)12C, 13C((alpha) ,n)16O, 17O((alpha) ,n)20Ne, 18O((alpha) ,n)21Ne, 21Ne((alpha) ,n)24Mg, 22Ne((alpha) ,n)25Mg, 25Mg((alpha) ,n)28Si and 26Mg((alpha) ,n)29Si have been measured at the 4 MV dynamitron accelerator in Stuttgart, Germany in the energy range of astrophysical interest, and from these S-factor- curves have been determined. Advanced techniques, especially with the windowless gastarget facility Rhinoceros have been applied. For neutron detection NE213 scintillation counters and a long counter like 4(pi) -detector have been used. A sensitivity limit in the range of 10-10b to 10-\\11b was reached with these experiments. Using our new experimental results astrophysical reaction rates have been calculated for all reactions except the Mg-reactions. Analytic expressions have been fitted to all reaction rates.

Kunz, Rino E.; Denker, A.; Drotleff, H. W.; Grosse, M.; Knee, H.; Kuechler, S.; Seidel, R.; Soine, M.; Hammer, J. W.

1995-03-01

81

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

82

High-Yield Neutron Source for Cargo Container Screening  

Microsoft Academic Search

A high-yield neutron source has been designed for the screening of sea-land cargo containers for shielded special nuclear materials (SNM). The accelerator-driven neutron source utilizes the D(d,n)3He reaction to produce a forward directed neutron beam. The key components of the neutron source are a high-current radio-frequency quadrupole (RFQ) accelerator and a high-power neutron production target. A thin entrance window has

Bernhard A. Ludewigt; Darren L. Bleuel; Joe W. Kwan; Derun Li; Alex Ratti; John W. Staples; Steven P. Virostek; Russell P. Wells

2006-01-01

83

An overview of the planned advanced neutron-source facility  

Microsoft Academic Search

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

Colin D. West

1991-01-01

84

Level1 PRA of the advanced neutron source reactor  

Microsoft Academic Search

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

J. C. Lin; D. C. Bley; C. T. Ramsey

1994-01-01

85

Ion source requirements for pulsed spallation neutron sources  

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 for a large class of experiments. 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{sup {minus}} source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The 1 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. A workshop held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H{sup {minus}} source technologies, and identified necessary R&D efforts to bridge the gap.

Alonso, J.R.

1995-10-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

87

A linac for the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source Project (SNS), to be constructed at Oak Ridge National Laboratory, accelerates H{sup {minus}} ions to an energy of 1.0 GeV with an average current of 1-mA for injection into an accumulator ring that produces the short intense burst of protons needed for the spallation-neutron source. The linac will be the most intense source of H{sup {minus}} ions and as such requires advanced design techniques to meet project technical goals. In particular, low beam loss is stressed for the chopped beam placing strong requirements on the beam dynamics and linac construction. Additionally, the linac is to be upgraded to the 2- and 4-MW beam-power levels with no increase in duty factor. The author gives an overview of the linac design parameters and design choices made.

Jason, A.J.

1998-12-31

88

Spallation neutron source saddle antenna H- ion source project  

NASA Astrophysics Data System (ADS)

In this project we are developing an H- 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.; Dudnikova, Galina; Stockli, Martin; Welton, Robert

2010-02-01

89

Spallation neutron source saddle antenna H- ion source project.  

PubMed

In this project we are developing an H(-) 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. PMID:20192379

Dudnikov, Vadim; Johnson, Rolland P; Dudnikova, Galina; Stockli, Martin; Welton, Robert

2010-02-01

90

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

91

Neutron Cross Section Measurements at the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

With the prospect of construction of the Spallation Neutron Source (SNS) at ORNL, and the fantastic high neutron flux, new, up to now impossible, experiments seem to be feasible in the fields of applied nuclear physics and astrophysics. These experiments will supply crucial neutron-induced cross section data for radionuclides, which are badly needed by many applied physics programs. The SNS will be uniquely suited for measuring the cross sections of interest to nuclear critically safety, accelerator transmutation of nuclear waste (ATW), and heavy element nucleosynthesis for astrophysics. Because the sample sizes required at current facilities are usually too large for practical measurements, scarce information of these cross sections is available. Using the high neutron flux at the SNS will allow these measurements to be made with samples about 40 times smaller than at the next best facility. The large reduction in sample size at the SNS will result in orders of magnitude reduction in background from the radioactive samples and make them much easier to produce; a much wider range of samples will be accessible for measurement at the SNS than at any other facility.

Guber, K. H.

2001-08-01

92

Neutron Cross Sections Measurements at the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

With the prospect of construction of the Spallation Neutron Source (SNS) at ORNL, and the fantastic high neutron flux, new, up to now impossible, experiments seem to be feasible in the fields of applied nuclear physics and astrophysics. These experiments will supply crucial neutron-induced cross section data for radioactive materials (fission products) and radionuclides, which are badly needed by many applied physics programs. The SNS will be uniquely suited for measuring the cross sections of interest to nuclear criticality safety, accelerator transmutation of nuclear waste, and heavy element nucleosynthesis for astrophysics. Using the high neutron flux at the SNS will allow these measurements to be made with samples about 40 times smaller than at the next best facility. The large reduction in sample size at the SNS will result in orders of magnitude reduction in background from the radioactive samples and make them much easier to produce; hence, a much wider range of samples will be accessible for measurement at the SNS than at any other facility. We will discuss some of the technical approaches.

Guber, K. H.; Koehler, P. E.; Valentine, T. E.; Leal, L. C.

2001-10-01

93

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...

94

10 CFR 39.55 - Tritium neutron generator target sources.  

Code of Federal Regulations, 2013 CFR

10 Energy 1 2013-01-01 2013-01-01...Tritium neutron generator target sources. 39.55 Section 39.55 Energy NUCLEAR REGULATORY COMMISSION...Tritium neutron generator target sources. (a) Use of a tritium...

2013-01-01

95

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. 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.; Meyer, G.; Falabella, S.; Guethlein, G.; Kerr, P.; Park, H. G.; Rusnak, B.; Sampayan, S.; Schmid, G.; Spadaccini, C.; Wang, L. [Lawrence Livermore National Laboratory, P.O. Box 808, L-229, Livermore, CA 94551 (United States); Morse, J. [National Nanomanufacturing Network, University of Massachusetts, Amherst, MA 01027 (United States)

2009-03-10

96

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

97

Condensed Matter Research Using the Spallation Neutron Source ISIS  

Microsoft Academic Search

The neutron scattering technique has been applied in earnest to condensed matter and materials research following the construction of reactor neutron sources in the mid-1940s. Today reactor sources are used to obtain results that pervade these subjects and applications in biology and physical chemistry are growing rapidly. The development of accelerator-based spallation sources, in which protons liberate neutrons from a

Paola Bisanti; Stephen W. Lovesey

1987-01-01

98

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

99

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

100

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

101

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

102

Experimental Neutron Source Facility Based on Accelerator Driven System  

NASA Astrophysics Data System (ADS)

An experimental neutron source facility has been developed for producing medical isotopes, training young nuclear professionals, providing capability for performing reactor physics, material research, and basic science experiments. It uses a driven subcritical assembly with an electron accelerator. The neutrons driving the subcritical assembly were generated from the electron interactions with a target assembly. Tungsten or uranium target material is used for the neutron production through photonuclear reactions. The neutron source intensity, spectrum, and spatial distribution have been studied to maximize the neutron yield and satisfy different engineering requirements. The subcritical assembly is designed to obtain the highest possible neutron flux intensity with a subcriticality of 0.98. Low enrichment uranium is used for the fuel material because it enhances the neutron source performance. Safety, reliability, and environmental considerations are included in the facility conceptual design. Horizontal neutron channels are incorporated for performing basic research including cold neutron source. This paper describes the conceptual design and summarizes some of the related analyses.

Gohar, Yousry

2010-06-01

103

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

104

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

105

The Advanced Neutron Source liquid deuterium cold source  

SciTech Connect

The Advanced Neutron Source will employ two cold sources to moderate neutrons to low energy (<10 meV). The cold neutrons produced are then passed through beam guides to various experiment stations. Each cold source moderator is a sphere of 410-mm internal diameter. The moderator material is liquid deuterium flowing at a rate of 1 kg/s and maintained at subcooled temperatures at all points of the circuit, to prevent boiling. Nuclear beat deposited within the liquid deuterium and its containment structure totals more than 30 kW. All of this heat is removed by the liquid deuterium, which raises its temperature by 5 K. The liquid prime mover is a cryogenic circulator that is situated in the return leg of the flow loop. This arrangement minimizes the heat added to the liquid between the heat exchanger and the moderator vessel, allowing the moderator to be operated at the minimum practical temperature. This report describes the latest thinking at the time of project termination. It also includes the status of various systems at that time and outlines anticipated directions in which the design would have progressed. In this regard, some detail differences between this report and official design documents reflect ideas that were not approved at the time of closure but are considered noteworthy.

Lucas, A.T.

1995-08-01

106

Intrinsic neutron source strengths in uranium solutions  

SciTech Connect

The presence of a source of neutrons to initiate persistent fission chains has long been recognized as an important element in the behavior of a critical assembly or reactor. The start-up source is a familiar part of most reactor loading or start-up operations. The problem of assembling fissionable material without the presence of an adequate source was reported in 1960 by Hansen, who analyzed the consequences of delayed initiation of a persistent fission chain during the assembly of a critical mass of material with a ramp reactivity addition. The stochastic nature of the first chain initiation was shown to provide the possibility of large reactivity availability even where modest ramp rates were assumed. At the Los Alamos Critical Experiments Facility, the authors have made experimental measurements of the intrinsic source strength for uranyl-nitrate and uranyl-fluoride solutions using a high-efficiency well counter system. These results are surprisingly similar, with the uranyl fluoride showing only a factor of 2 higher neutron production rate, and will be compared with the results of a recently developed theoretical model.

Seale, R.L. (Univ. of Arizona, Tucson (United States)); Anderson, R.E. (Los Alamos National Lab., NM (United States))

1991-01-01

107

The advanced neutron source safety approach and plans  

Microsoft Academic Search

The Advanced Neutron Source (ANS) is a user facility for all areas of neutron research proposed for construction at the Oak Ridge National Laboratory. The neutron source is planned to be a 350-MW research reactor. The reactor, currently in conceptual design, will belong to the United States Department of Energy (USDOE). The safety approach and planned elements of the safety

1989-01-01

108

Thermal-hydraulic studies of the Advanced Neutron Source cold source  

Microsoft Academic Search

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

P. T. Williams; A. T. Lucas

1995-01-01

109

High sensitivity neutron imaging system for neutron radiography with a small neutron source  

NASA Astrophysics Data System (ADS)

Although neutron radiography is a very useful NDT technique, its widespread use has been limited due to the lack of a mobile neutron radiography system. One of the major requirements in designing such a system is the development of a low fluence neutron imaging technique. In recent years several groups in France, Japan and the USA have been working on such an imaging system. We report in this paper the development of such a neutron imaging system based on a Li6F-ZnS scintillator screen using a pair of image intensifier tubes and a charge coupled device. This detector system has been employed to study the feasibility of neutron radiography using low neutron fluences. The main feature of this imaging system is its ability to detect individual neutron scintillation events with a high degree of spatial resolution. Details of this imaging system and the preliminary results obtained using a Pu-Be neutron source of strength ~2 × 107 n/s are reported in this paper.

Sinha, A.; Panchal, C. G.; Shyam, A.; Srinivasan, M.; Joshi, V. M.; Bhawe, B. D.

1996-03-01

110

Intense steady state neutron source. The CNR reactor  

SciTech Connect

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 materials irradiation research communities. The CNR is a major new experimental facility consisting of a reactor-based steady state neutron source of unprecedented flux, together with extensive facilities and instruments for neutron scattering, isotope production, materials irradiation, and other areas of research.

Difilippo, F.C.; Moon, R.M.; Gambill, W.R.; Moon, R.M.; Primm, R.T. III; West, C.D.

1986-01-01

111

New sources and instrumentation for neutrons in biology  

PubMed Central

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

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

2008-01-01

112

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

113

The Effect of Neutron Source Distribution on Subcriticality Measurement of Pressurized Water Reactors Using the Modified Neutron Source Multiplication Method  

Microsoft Academic Search

A modified neutron source multiplication method has been investigated for application to subcriticality measurement in commercial Pressurized Water Reactors (PWRs). This method is based on the extraction of the fundamental mode from measured neutron signals and corrections for spatial effects. In commercial reactors, mainly two types of neutron sources are expected, one from burnt fuels and the other from in-core

Win Naing; Masashi TSUJI; Yoichiro SHIMAZU

2003-01-01

114

The status of the spallation neutron source ion source  

SciTech Connect

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

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

2003-09-11

115

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

116

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

117

Unperturbed moderator brightness in pulsed neutron sources  

NASA Astrophysics Data System (ADS)

The unperturbed neutron brightness of a moderator can be defined from the number of neutrons leaving the surface of a moderator completely surrounded by a reflector. Without openings for beam extraction, it is the maximum brightness that can be theoretically achieved in a moderator. The unperturbed brightness of a cylindrical cold moderator filled with pure para-H2 was calculated using MCNPX; the moderator dimensions were optimised, for a fixed target and reflector geometry corresponding to the present concept for the ESS spallation source. This quantity does not depend on openings for beam extraction and therefore can be used for a first-round optimisation of a moderator, before effects due to beam openings are considered. We find that such an optimisation yields to a factor of 2 increase with respect to a conventional volume moderator, large enough to accommodate a viewed surface of 12×12 cm2: the unperturbed neutron brightness is maximum for a disc-shaped moderator of 15 cm diameter, 1.4 cm height.

Batkov, K.; Takibayev, A.; Zanini, L.; Mezei, F.

2013-11-01

118

Neutron Sources in Stellar Carbon Burning  

NASA Astrophysics Data System (ADS)

The possibility of a high temperature s-process during the carbon burning phase in late stellar evolution depends critically on possible neutron sources. In this context the following alpha capture reactions are being discussed, ^17O(?,n), ^18O(?,n), ^22Ne(?,n), ^25Mg(?,n), and ^26Mg(?,n). Their effective contribution to the neutron production depends on the abundance of the various seed nuclei, which in turn depend critically on the alpha or proton production in the ^12C+^12C fusion process; it also depends on the reaction cross sections or rates of these processes at carbon burning temperatures. We have studied the reaction cross sections at low energies at the Notre Dame KN accelerator using a new ^3He neutron detector array. The results will be shown and discussed in the context of late stellar evolution. In collaboration with Andreas Best, University of Notre Dame; Sascha Falahat, University of Mainz, Germany; Marco Pignatari, Keele University, UK; and Michael Wiescher, University of Notre Dame.

Goerres, Joachim

2009-10-01

119

Non-Reactor Neutron Sources for BNCT (Boron Neutron Capture Therapy).  

National Technical Information Service (NTIS)

The focus of this study is the identification of key feasibility issues for the use of non-reactor neutron sources for Boron Neutron Capture Therapy (BNCT). Of the non-reactor neutron sources surveyed, the (7)Li(p,n) reaction appears to be the most favora...

D. M. Woodall E. E. Wills E. H. Ottewitte T. J. Dolan W. A. Neuman

1989-01-01

120

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

121

Standard fields of old neutron sources--parameters and traceability.  

PubMed

Standard neutron fields of isotope neutron sources, established in the Institute of Atomic Energy, Poland, have been examined for nearly 20 y. The neutron dose equivalent and gamma dose rates were measured, applying various techniques. The neutron emission of standard neutron sources of 241Am-Be and 252Cf has been originally determined in primary standard laboratory, then checked, making use of transfer instrument calibrated in primary laboratory. The growth of neutron emission of 239Pu-Be source, used for routine calibrations, has been demonstrated. The total uncertainty of determined parameters has been discussed. The periodically repeated checks of neutron fields of standard sources with the use of transfer instrument, calibrated in primary laboratory, should provide the traceability to primary laboratory and the fields could be officially recognised. PMID:15353631

Józefowicz, Krystyna; Golnik, Natalia; Zielczy?ski, Mieczys?aw

2004-01-01

122

H- Ion Source Development for the National Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

The ion source for the 1 MW National Spallation Neutron Source (NSNS) is required to provide 35 mA of H- beam current (1 ms pulses at 60 Hz) at 65 keV with a normalized rms emittance of less than 0.2 #185# mm mrad. The same ion source should be able to produce 70 mA of H- at 6% duty factor when the NSNS is upgraded to 2 MW of power. For this application, a radio-frequency driven, magnetically filtered multicusp source is now being developed at LBNL. In preliminary experiments with an existing ion source developed for the Superconducting Super Collider, 16 mA of H- ions were extracted at an accelerated voltage of 10 kV and an RF output power of 20 kW without cesium. The design of a new source equipped with a cesium dispenser-collar, a fast ion beam pre-chopper (rise times < 100 ns) and a strong permanent-magnet insert for electron deflection will be presented. [This research is sponsored by the Division of Materials Sciences, DOE, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp.

Leitner, M.; Gough, R.; Leung, K. N.; Rickard, M.; Wengrow, A. B.; Williams, M. D.; Wutte, D.

1997-05-01

123

Outline of a proposal for a new neutron source: The pulsed neutron research facility.  

National Technical Information Service (NTIS)

Accelerator-based, pulsed spallation neutron sources have been performing neutron scattering research for about fifteen years. During this time beam intensities have increased by a factor of 100 and more than 50 spectrometers are now operating on four maj...

B. S. Brown J. M. Carpenter R. L. Kustom

1992-01-01

124

Spallation Neutron Source Effects in a SubCritical System  

Microsoft Academic Search

Numerical simulations of a sub-critical system coupled to a neutron spallation source (1000 MeV protons impinging on a lead target) have been performed with the Monte Carlo code MCNPX and the deterministic code system ERANOS. The investigations have focused on the determination of the source neutron efficiency, ?*, i.e. the ratio of the average importance of external source neutrons to

P. Seltborg; R. Jacqmin

125

Average cross sections for Pu-?-Be neutrons: Low-energy neutrons from ?-n sources  

Microsoft Academic Search

Average activation cross sections for a number of elements were determined using unmoderated neutrons from Pu-Be and Po-Be\\u000a sources. Applying threshold detectors it was found that 10% of Pu-Be neutrons are emitted in the energy interval 10–100 keV.\\u000a Neutron spectra from Pu-Be13 sources of different dimensions were the same within the interval 0.5–5 Ci; the majority of neutrons below 2

G. Pet?; J. Csikai; G. M. Shuriet; I. Józsa; V. Asztalos

1973-01-01

126

rf improvements for Spallation Neutron Source H- ion source.  

PubMed

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 approximately 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. PMID:20192394

Kang, Y W; Fuja, R; Goulding, R H; Hardek, T; Lee, S-W; McCarthy, M P; Piller, M C; Shin, K; Stockli, M P; Welton, R F

2010-02-01

127

rf improvements for Spallation Neutron Source H- ion source  

NASA Astrophysics Data System (ADS)

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.

Kang, Y. W.; Fuja, R.; Goulding, R. H.; Hardek, T.; Lee, S.-W.; McCarthy, M. P.; Piller, M. C.; Shin, K.; Stockli, M. P.; Welton, R. F.

2010-02-01

128

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

129

H- radio frequency source development at the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

130

BNL feasibility studies of spallation neutron sources  

SciTech Connect

This paper is the summary of conceptual design studies of a 5 MW Pulsed Spallation Neutron Source (PSNS) conducted by an interdepartmental study group at Brookhaven National Laboratory. The study was made of two periods. First, a scenario based on the use of a 600 MeV Linac followed by two fast-cycling 3.6 GeV Synchrotrons was investigated. Then, in a subsequent period, the attention of the study was directed toward an Accumulator scenario with two options: (1) a 1.25 GeV normal conducting Linac followed by two Accumulator Rings, and (2) a 2.4 GeV superconducting Linac followed by a single Accumulator Ring. The study did not make any reference to a specific site.

Lee, Y.Y.; Ruggiero, A.G.; Van Steenbergen, A.; Weng, W.T.

1995-12-01

131

SPALLATION NEUTRON SOURCE BEAM CURRENT MONITOR ELECTRONICS.  

SciTech Connect

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 mini-pulses repeating at a 60Hz rate. Ring beam current will vary from about 15ma peak during studies, to about 50Amps peak (design to 100 amps). A digital approach to droop compensation has been implemented and initial test results presented.

KESSELMAN,M.; DAWSON,W.C.

2002-05-06

132

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

133

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

134

Chemistry and Physics Challenges in Spallation Neutron Source Safety Analyses.  

National Technical Information Service (NTIS)

This paper describes several unique issues that have been addressed in the accident and source term analyses performed in support of the Preliminary Safety Analysis Report (PSAR) for the Spallation Neutron Source (SNS) Target Building. The inventory of ra...

R. R. Lowrie

2001-01-01

135

Materials for cold neutron sources: Cryogenic and irradiation effects.  

National Technical Information Service (NTIS)

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 w...

D. J. Alexander

1990-01-01

136

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

137

Overview of the Target Systems for the Spallation Neutron Source  

SciTech Connect

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

Gabriel, T.A.; Haines, J.R.; McManamy, T.J.

1998-10-15

138

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

National Technical Information Service (NTIS)

The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-year half-life. A source the size of a persons little finger can emit up to 1011 neutrons/s. Californ...

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

1999-01-01

139

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

140

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

141

A neutron source facility for neutron cross-section measurements on radioactive targets at RIA  

Microsoft Academic Search

The stockpile stewardship program is interested in neutron cross-section measurements on nuclei that are a few nucleons away from stability. Since neutron targets do not exist, radioactive targets are the only way to directly perform these measurements. This requires a facility that can provide high production rates for these short-lived nuclei as well as a source of neutrons. The Rare

L E Ahle; L. Bernstein; B. Rusnak; R. Berio

2003-01-01

142

Convenient method of relative calibration of the neutron source emission rate between different source types  

Microsoft Academic Search

Neutron source emission rates are determined by absolute or relative measurement. The relative measurement is performed by comparing between a sample source and a calibrated reference source of the same type. In this calibration, the energy spectra of the sample and reference sources should be identical, since normally there exists energy dependence in the response of neutron detectors. We propose

H. Harano; T. Matsumoto; T. Shimoyama; Y. Sato; A. Uritani; Y. Hino; K. Kudo; T. Michikawa

2006-01-01

143

Accelerator based epithermal neutron source for neutron capture therapy  

SciTech Connect

Several investigators have suggested that a charged particle accelerator with light element reactions might be able to produce enough epithermal neutrons to be useful in Neutron Capture Therapy. The reaction choice so far has been the Li(p,n) reaction with protons up to 2.5 MeV. A moderator around the target would reduce the faster neutrons down to the epithermal energy region. The goals of the present research are: identify better reactions; improve the moderators; and find better combinations of 1 and 2. The target is to achieve, at the patient location, an epithermal neutron current of greater than 10{sup 9}n/cm{sup 2}sec, with a dose to tissue from the neutrons alone of less than 10{sup {minus}10} rads/n and a dose from the gamma rays in the beam of less than 10{sup {minus}10} rads/n.

Brugger, R.; Kunze, J.

1991-05-01

144

Condensed Matter Research Using the Spallation Neutron Source ISIS  

NASA Astrophysics Data System (ADS)

The neutron scattering technique has been applied in earnest to condensed matter and materials research following the construction of reactor neutron sources in the mid-1940s. Today reactor sources are used to obtain results that pervade these subjects and applications in biology and physical chemistry are growing rapidly. The development of accelerator-based spallation sources, in which protons liberate neutrons from a heavy metal target, opens new frontiers through both the enhancement of available neutron flux and the inherent time structure of the beams. We survey the particular advantages of advanced pulsed sources with illustrations taken from recent work using the spallation source ISIS, sited at the Rutherford Appleton Laboratory. Topics of work include surface science, structure determination and molecular and neutron-electron spectroscopy. Finally we sketch the current development of new instrument technology and foreseeable applications.

Bisanti, Paola; Lovesey, Stephen W.

1987-01-01

145

Neutrino Physics at Pulsed Spallation Neutron Sources  

NASA Astrophysics Data System (ADS)

The 2MW, 1Gev Spallation Neutron Source, under construction at ORNL, is an excellent example of a facility that offers unique opportunities for experiments relevant to particle physics, neutrino astrophysics, nuclear physics, and cosmology. Numerical feasibility studies have been carried out for experimental measurements of neutrino oscillation parameters, ?-nucleus reactions, for example: d(?_e,e^-)pp, ^16O(?_e,e^-) ^16F, ^12C(?_e,e^-) ^12N_gs, ^12C(?,?^`) ^12C, ^56Fe(?_e,e^-) ^56Co, and other reactions using the same techniques. In addition, precision measurements of both charge-current and neutral-current cross sections for electron-neutrino elastic scattering can be done at such facilities when the pulse duration allows the separation of ?_? from ?e and \\overline?_?. The above and other feasible reactions would be very useful in analyzing the data from the SNO and other solar neutrino experiments, in tuning nuclear models used in supernovae computations, and in shedding light on weak interactions in nuclei. A broad selection of neutrino physics topics will be discussed. The physics that will be discussed applies to any intense, pulsed, stopped pion source.

Avignone, Frank T., III

2001-10-01

146

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

SciTech Connect

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

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

1999-10-03

147

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

148

Superthermal source of ultracold neutrons for fundamental physics experiments.  

PubMed

Ultracold neutrons (UCNs) play an important role for precise measurements of the properties of the neutron and its interactions. During the past 25 years, a neutron turbine coupled to a liquid deuterium cold neutron source at a high-flux reactor has defined the state of the art for UCN production, despite a long history of efforts towards a new generation of UCN sources. This Letter reports a world-best UCN density available for users, achieved with a new source based on conversion of cold neutrons in superfluid helium. A conversion volume of 5 liters provides at least 274,000 UCN in a single accumulation run. Cyclically repeated operation of the source has been demonstrated, as well. PMID:22026860

Zimmer, Oliver; Piegsa, Florian M; Ivanov, Sergey N

2011-09-19

149

Superthermal Source of Ultracold Neutrons for Fundamental Physics Experiments  

SciTech Connect

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

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

2011-09-23

150

Computational Benchmark Calculations Relevant to the Neutronic Design of the Spallation Neutron Source (SNS)  

Microsoft Academic Search

The Spallation Neutron Source (SNS) will provide an intense source of low-energy neutrons for experimental use. The low-energy neutrons are produced by the interaction of a high-energy (1.0 GeV) proton beam on a mercury (Hg) target and slowed down in liquid hydrogen or light water moderators. Computer codes and computational techniques are being benchmarked against relevant experimental data to validate

F. X. Gallmeier; D. C. Glasgow; E. A. Jerde; J. O. Johnson; J. J. Yugo

1999-01-01

151

Accelerator-based epithermal neutron sources for boron neutron capture therapy of brain tumors  

Microsoft Academic Search

Summary  This paper reviews the development of low-energy light ion accelerator-based neutron sources (ABNSs) for the treatment of\\u000a brain tumors through an intact scalp and skull using boron neutron capture therapy (BNCT). A major advantage of an ABNS for\\u000a BNCT over reactor-based neutron sources is the potential for siting within a hospital. Consequently, light-ion accelerators\\u000a that are injectors to larger machines

Thomas E. Blue; Jacquelyn C. Yanch

2003-01-01

152

Accelerator-based Epithermal Neutron Sources for Boron Neutron Capture Therapy of Brain Tumors  

Microsoft Academic Search

This paper reviews the development of low-energy light ion accelerator-based neutron sources (ABNSs) for the treatment of brain tumors through an intact scalp and skull using boron neutron capture therapy (BNCT). A major advantage of an ABNS for BNCT over reactor-based neutron sources is the potential for siting within a hospital. Consequently, light-ion accelerators that are injectors to larger machines

Thomas E. Blue; Jacquelyn C. Yanch

2003-01-01

153

The Advanced Neutron Source Facility: A new user facility for neutron research  

Microsoft Academic Search

The Advanced Neutron Source (ANS) is a new reactor-based research facility being planned by Oak Ridge National Laboratory (ORNL) to meet the need for an intense steady state source of neutrons and for associated research space and equipment. The ANS will be open for use by scientists from universities, industry, and other federal laboratories. The ANS will be built around

1988-01-01

154

Advanced Neutron Source Facility: A New User Facility for Neutron Research.  

National Technical Information Service (NTIS)

The Advanced Neutron Source (ANS) is a new reactor-based research facility being planned by Oak Ridge National Laboratory (ORNL) to meet the need for an intense steady state source of neutrons and for associated research space and equipment. The ANS will ...

C. D. West

1988-01-01

155

A solenoidal and monocusp ion source (SAMIS) neutron generator  

SciTech Connect

The authors have developed a new magnetic monocusp ion source for single aperture applications such as neutron generators. Coupling solenoidal magnetic fields on both sides of a monocusp magnetic field has generated over 70% atomic deuterium ions at pressures as low as 0.4 Pa (3 mTorr). This article describes the performance and characteristics of the SAMIS source. Initial tests with a SAMIS source in a ceramic neutron generator are also described.

Burns, E.J.T.; Brainard, J.P.; Draper, C.H.; Ney, R.J. [Sandia National Labs., Albuquerque, NM (United States). Neutron Tube Development Dept.; Leung, K.N.; Perkins, L.T.; Williams, M.D.; Wilde, S.B. [Lawrence Berkeley National Lab., CA (United States)

1996-06-01

156

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

157

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

158

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

159

Microtron MT 25 as a source of neutrons  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

160

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

161

Low Voltage D-T Neutron Source.  

National Technical Information Service (NTIS)

The report is concerned with an analysis of the problems involved in the design and slection of equipment for the production of intense beams of 14-MeV neutrons. Since the aim is to achieve total neutron yields in excess of 10 to the 13th power/sec, a fig...

J. B. Marion

1966-01-01

162

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

SciTech Connect

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

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

1996-07-01

163

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

164

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

165

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

166

FAST NEUTRON DOSIMETRY OF A PLUTONIUM-BERYLLIUM SOURCE (thesis)  

Microsoft Academic Search

S>Investigations showed that using a combination of two ehambers, one ; composed of polythylene-- ethylene and the other of teflon-- COâ, the doses ; delivered to a standard tissue'' by the fast neutrons and the gamma rays from ; a Pu--Be neutron source can be measured. The ionization currents were read on a ; vibrating reed electrometer. The probable errors

1958-01-01

167

A Bright Neutron Source Driven by a Short Pulse Laser  

NASA Astrophysics Data System (ADS)

Neutrons are a unique tool to alter and diagnose material properties, and to exciting nuclear reactions, for many applications. Accelerator based spallation sources provide high neutron fluxes for research, but there is a growing need for more compact sources with higher peak brightness, whether fast or moderated neutrons. Intense lasers promise such as source, readily linkable to other experimental facilities, or deployable outside a laboratory setting. We present experimental results on the first short-pulse laser-driven neutron source powerful enough for radiography. A novel laser-driven ion acceleration mechanism (Breakout Afterburner), operating in the relativistic transparency regime, is used. Based on the mechanism's advantages, a laser-driven deuteron beam is used to achieve a new record in laser-neutron production, in numbers, energy and directionality. This neutron beam is a highly directional pulse < 1 ns at ˜ 1 cm from the target, with a flux > 40/2?, and thus suitable for imaging applications with high temporal resolution. The beam contained, for the first time, neutrons with energies of up to 150 MeV. Thus using short pulse lasers, it is now possible to use the resulting hard x-rays and neutrons of different energies to radiograph an unknown object and to determine its material composition. Our data matches the simulated data for our test samples.

Roth, Markus

2012-10-01

168

An Intense Pulsed Neutron Source for Argonne National Laboratory  

Microsoft Academic Search

A pulsed neutron source has been designed for materials research in slow neutron scattering and radiation effects. The facility is based in its first phase on the ZGS 500 MeV Injector Booster Accelerator, which will produce 5 ?? 1012 protons per pulse and be modified for 60 Hz operation. In its second phase a high intensity synchrotron will provide 5

J. M. Carpenter; David L. Price

1975-01-01

169

Advanced Neutron Source radiological design criteria  

SciTech Connect

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

Westbrook, J.L.

1995-08-01

170

An ultra-cold neutron source at the MLNSC  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have carried out the research and development of an Ultra-Cold Neutron (UCN) source at the Manuel Lujan Neutron Scattering Center (MLNSC). A first generation source was constructed to test the feasibility of a rotor source. The source performed well with an UCN production rate reasonably consistent with that expected. This source can now provide the basis for further development work directed at using UCN in fundamental physics research as well as possible applications in materials science.

Bowles, T.J.; Brun, T.; Hill, R.; Morris, C.; Seestrom, S.J. [Los Alamos National Lab., NM (United States); Crow, L. [Univ. of Rhode Island, Kingston, RI (United States); Serebrov, A. [Petersburg Nuclear Physics Inst. (Russian Federation)

1998-11-01

171

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 17×17 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

172

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

173

Accelerator-driven neutron source for cargo screening  

NASA Astrophysics Data System (ADS)

Advanced neutron interrogation systems for screening sea-land cargo containers for shielded special nuclear materials (SNM) require a high-yield neutron source to achieve the desired detection probability, false alarm rate, and throughput. The design of an accelerator-driven neutron source is described that utilizes the D(d,n)3He reaction to produce a forward directed beam of up to 8.5 MeV neutrons. The key components of the neutron source are a high-current radio frequency quadrupole (RFQ) accelerator and a neutron production gas target. The 5.1 m long, 200 MHz RFQ accelerates a 40 mA deuteron beam from a microwave-driven ion source coupled to an electrostatic low energy beam transport (LEBT) system to 6 MeV. At a 5% duty factor, the time-average D+ beam current on target is 1.5 mA. A thin entrance window has been designed for the deuterium gas target that can withstand the high beam power and the gas pressure. The source will be capable of delivering a flux >1 × 107 n/(cm2 s) at a distance of 2.5 m from the target and will allow full testing and demonstration of a cargo screening system based on neutron stimulated SNM signatures.

Ludewigt, B. A.; Bleuel, D. L.; Hoff, M. D.; Kwan, J. W.; Li, D.; Ratti, A.; Staples, J. W.; Virostek, S. P.; Wells, R. P.

2007-08-01

174

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

175

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

176

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

177

Radionuclide neutron sources in calibration laboratory--neutron and gamma doses and their changes in time.  

PubMed

The calibration laboratory, having standard neutron fields of radionuclide sources, should perform regular measurements of fields' parameters in order to check their stability and to get knowledge of any changes. Usually, accompanying gamma radiation is not of serious concern, but some personal dosemeters, old neutron dose equivalent meters with scintillation detectors and the dose meters of mixed radiation require the determination of this component. In the Laboratory of Radiation Protection Measurements in the Institute of Atomic Energy, Poland, the fields of radionuclide neutron sources (252)Cf, (241)Am-Be and (239)Pu-Be were examined for nearly 20 y. A number of detectors and methods have been applied for the determination of neutron ambient dose equivalent rate and for the determination of neutron and gamma dose components. This paper presents the recent results of measurements of gamma and neutron dose and dose equivalent, compared with the results accumulated in nearly 20 y. PMID:17513855

Józefowicz, K; Golnik, N; Tulik, P; Zielczynski, M

2007-05-19

178

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

SciTech Connect

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

Mitra,S.

2008-11-17

179

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

180

Triple GEM gas detectors as real time fast neutron beam monitors for spallation neutron sources  

NASA Astrophysics Data System (ADS)

A fast neutron beam monitor based on a triple Gas Electron Multiplier (GEM) detector was developed and tested for the ISIS spallation neutron source in U.K. The test on beam was performed at the VESUVIO beam line operating at ISIS. The 2D fast neutron beam footprint was recorded in real time with a spatial resolution of a few millimeters thanks to the patterned detector readout.

Murtas, F.; Croci, G.; Pietropaolo, A.; Claps, G.; Frost, C. D.; Perelli Cippo, E.; Raspino, D.; Rebai, M.; Rhodes, N. J.; Schooneveld, E. M.; Tardocchi, M.; Gorini, G.

2012-07-01

181

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

NASA Astrophysics Data System (ADS)

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 inside the guide. These charged neutron-decay products are magnetically guided to the end of the neutron guide, where they are separated from the cold-neutron beam. In this way, a general-purpose source of neutron decay products is obtained which can be operated as a user facility for a variety of different experiments in neutron decay correlation spectroscopy that may be installed at this beam station. The angular distribution of the emitted charged particles depends on the magnetic field configuration and can be chosen freely, according to the need of the experiment being carried out. A gain in phase space density of several orders of magnitude can be achieved with PERC, as compared to existing neutron decay spectrometers. Detailed calculations show that the spectra and angular distributions of the emerging electrons and protons will be distortion- and background-free on the level of 10-4, more than 10 times better than that achieved today.

Dubbers, D.; Abele, H.; Baeßler, S.; Märkisch, B.; Schumann, M.; Soldner, T.; Zimmer, O.

2008-11-01

182

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

2010-12-24

183

Exploratory studies on neutron radiography with a small neutron source using a nuclear scintillation imaging technique  

NASA Astrophysics Data System (ADS)

Neutron radiography based on mobile neutron sources need optimum utilization of available neutron fluxes which are usually lower compared to those available from reactors. For optimum utilization of such low flux devices, a sensitive neutron imaging technique is required. Such a neutron imaging system based on a Li6F-ZnS scintillator screen has been developed using a pair of image intensifier tubes and a charge coupled device. This detector system has been employed to study the feasibility of neutron radiography using low neutron fluences. The main feature of this imaging system is its ability to detect individual neutron scintillation events with a higher degree of spatial resolution. In order to test the efficiency of this imaging system, a small scale moderator-collimator assembly was designed using a Pu-Be neutron source of strength ~ 2 × 107 n/s. Details of this imaging system and results of some exploratory experiments for low fluence neutron imaging are presented in this paper.

Sinha, Amar; Bhawe, B. D.; Panchal, C. G.; Shyam, A.; Srinivasan, M.; Joshi, V. M.

1996-02-01

184

Augmenting real data with synthetic data: an application in assessing radio-isotope identification algorithms  

SciTech Connect

The performance of Radio-Isotope Identification (RIID) algorithms using gamma spectroscopy is increasingly important. For example, sensors at locations that screen for illicit nuclear material rely on isotope identification to resolve innocent nuisance alarms arising from naturally occurring radioactive material. Recent data collections for RIID testing consist of repeat measurements for each of several scenarios to test RIID algorithms. Efficient allocation of measurement resources requires an appropriate number of repeats for each scenario. To help allocate measurement resources in such data collections for RIID algorithm testing, we consider using only a few real repeats per scenario. In order to reduce uncertainty in the estimated RIID algorithm performance for each scenario, the potential merit of augmenting these real repeats with realistic synthetic repeats is also considered. Our results suggest that for the scenarios and algorithms considered, approximately 10 real repeats augmented with simulated repeats will result in an estimate having comparable uncertainty to the estimate based on using 60 real repeats.

Burr, Tom L [Los Alamos National Laboratory; Hamada, Michael [Los Alamos National Laboratory; Graves, Todd [Los Alamos National Laboratory; Myers, Steve [Los Alamos National Laboratory

2008-01-01

185

Intrinsic neutron source strengths in uranium solutions  

SciTech Connect

Neutron production rates for 5% enriched uranyl fluoride and 93% uranyl nitrate solutions have been measured using a high-efficiency neutron well counter. Measurements were made for both solution types as a function of sample volume. These results were extrapolated to zero sample volume to eliminate sample size effects, such as multiplication and absorption. For the 5% enriched uranyl fluoride solution, a neutron production rate of 0.0414 {plus minus} 0.0041 n/s/ml was measured; for the 93% enriched uranyl nitrate solution, a neutron production rate of 0.0232 {plus minus} 0.0023 n/s/ml was measured. The biggest uncertainty is in measuring the detector efficiency, and further work on this aspect of the experiment is planned. Calculations for the neutron production rates based on measured thick-target (alpha, n) production rates and shown alpha stopping powers are in reasonable agreement with the data for the uranyl nitrate solution, but are in poor agreement with the data for the uranyl fluoride solution. 8 refs., 7 figs., 5 tabs.

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

1991-01-01

186

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

187

Plans for an Ultra Cold Neutron source at Los Alamos  

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 source, 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.

1996-10-01

188

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

189

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

190

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

191

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

192

The 4.438 MeV gamma to neutron ratio for the Am–Be neutron source  

Microsoft Academic Search

An accurate measurement of the 4.438MeV ?-ray to total neutron ratio, namely R=S?\\/Sn, for a Chinese-made Am–Be neutron source is described. The neutron strength of the source relative to a previously standardized source was determined by the manganese bath technique. The ?-rays spectra of the source were measured using a ?75×75mm NaI(Tl) detector. The background induced by neutrons and the

Zhenzhou Liu; Jinxiang Chen; Pei Zhu; Yongming Li; Guohui Zhang

2007-01-01

193

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

194

Conceptual design of an RFQ accelerator-based neutron source for boron neutron-capture therapy  

SciTech Connect

We present a conceptual design of a low-energy neutron generator for treatment of brain tumors by boron neutron capture theory (BNCT). The concept is based on a 2.5-MeV proton beam from a radio-frequency quadrupole (RFQ) linac, and the neutrons are produced by the /sup 7/Li(p,n)/sup 7/Be reaction. A liquid lithium target and modulator assembly are designed to provide a high flux of epithermal neutrons. The patient is administered a tumor-specific /sup 10/Be-enriched compound and is irradiated by the neutrons to create a highly localized dose from the reaction /sup 10/B(n,..cap alpha..)/sup 7/Li. An RFQ accelerator-based neutron source for BNCT is compact, which makes it practical to site the facility within a hospital. 11 refs., 5 figs., 1 tab.

Wangler, T.P.; Stovall, J.E.; Bhatia, T.S.; Wang, C.K.; Blue, T.E.; Gahbauer, R.A.

1989-01-01

195

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

196

Source-Specific Neutron Detection Efficiencies of the TAMU Neutron Ball  

NASA Astrophysics Data System (ADS)

In this paper, we report neutron detection efficiencies for the TAMU Neutron Ball located at the Cyclotron Institute at Texas A&M University. The results discussed are for symmetric reactions of 70Zn, 64Zn and 64Ni at a beam energy of 35 MeV/nucleon. The overall neutron detection efficiency was found to be approximately 70%. We also briefly discuss the process of quasi-projectile (QP) reconstruction. The HIPSE-SIMON reaction simulation and de-excitation code is used in conjunction with a software filter which simulates the geometric and energetic acceptances of the Neutron Ball to provide QT (quasi-target) and QP-specific neutron detection efficiencies. These source-specific efficiencies can be used to estimate the number of free neutrons to associate with the QP during reconstruction of experimental data. With this information it is possible to study the decay processes of well-defined, exotic forms of nuclear matter.

Zarrella, Andrew; Marini, Paola; McIntosh, Alan B.; Cammarata, Paul; Heilborn, Lauren; Mabiala, Justin; May, Larry W.; Raphelt, Andrew; Yennello, Sherry

2013-03-01

197

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

198

High Intensity Accelerator and Neutron Source in China  

NASA Astrophysics Data System (ADS)

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

Guan, Xialing; Wei, J.; Loong, Chun

2011-06-01

199

High Intensity Accelerator and Neutron Source in China  

SciTech Connect

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

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

2011-06-28

200

NEUTRON SPECTRUM OF A Pu-Be SOURCE  

Microsoft Academic Search

The spectrum of a Pu-Be source with 80 g Pu was determined using the ; time-of-flight method. The spectrum obtained is shown and is in good agreement ; with the BroekAnderson measurement in the range 2 to 9 Mev. Two rnaxima at 3 and ; 5 Mev were resolved. Pu fission and inelastic scattering of neutrons on the ; source

P. Huber; Z. Lewandowski; R. Plattner; C. Poppelbaum; R. Wagner

1962-01-01

201

Energy variable deuteron linac for materials research neutron source  

Microsoft Academic Search

Basic research in new materials and materials technology is a key national resource, and several countries are making plans for advanced capabilities, including intense neutron sources. Advances in high-intensity linear accelerator technology can provide efficient drivers for such sources. Aspects such as energy variability, uniformity of target dose distribution, target bombardment from multiple directions, time-scheduled dose patterns, and other features

1990-01-01

202

Spent-fuel photon and neutron source spectra  

SciTech Connect

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

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

1983-01-01

203

An overview of the planned advanced neutron-source facility  

NASA Astrophysics Data System (ADS)

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, U3Si2, 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. Based on work performed at Oak Ridge National Laboratory, managed by Martin Marietta Energy Systems Inc., under contract number DE-AC05-84OR21400 with the US Department of Energy.

West, Colin D.

1991-10-01

204

LOW VOLTAGE 14 Mev NEUTRON SOURCE  

DOEpatents

An apparatus yielding high-energy neutrons at the rate of 10/sup 8/ or more per second by the D,T or D,D reactions is described. The deuterium gas filling is ionized by electrons emitted from a filament, and the resulting ions are focused into a beam and accelerated against a fixed target. The apparatus is built in accordance with the relationship V/sub s/ = A--B log pd, where V/sub s/ is the sparking voltage, p the gas pressure, and d the gap length between the high voltage electrodes. Typical parameters to obtain the high neutron yields are 55 to 80 kv, 0.5 to 7.0 ma beam current, 5 to 12 microns D/sub 2/, and a gap length of 1 centimeter.

Little, R.N. Jr.; Graves, E.R.

1959-09-29

205

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

206

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

207

(252)Cf-source-driven neutron noise analysis method  

Microsoft Academic Search

The Cf-252-source-driven neutron noise analysis method has been tested in a wide variety of experiments that have indicated the broad range of applicability of the method. The neutron multiplication factor k(sub eff) has been satisfactorily determined for a variety of materials including uranium metal, light water reactor fuel pins, fissile solutions, fuel plates in water, and interacting cylinders. For a

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

1985-01-01

208

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

SciTech Connect

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

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

1999-09-20

209

Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources  

NASA Astrophysics Data System (ADS)

Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source strength of at least 1mg was necessary for fabrication of a 252Cf HDR source.

Rivard, Mark Joseph

210

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

211

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

SciTech Connect

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

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

2011-08-15

212

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

PubMed

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

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

2011-08-01

213

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

SciTech Connect

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

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

2011-01-01

214

A neutron producing target for BINP accelerator-based neutron source.  

PubMed

An innovative accelerator-based neutron source for BNCT has just started operation at the Budker Institute of Nuclear Physics, Novosibirsk. One of the main elements of the facility is a lithium target producing neutrons via the threshold (7)Li(p,n)(7)Be reaction at 25 kW proton beam with energies of 1.915 MeV or 2.5 MeV. The design of an optimal target and results of the investigation of radiation blistering of the lithium layer were presented at previous NCT Congresses. During the last two years the neutron target has been manufactured, assembled and placed in the facility. Optimization of the target is carried out with the Monte Carlo simulation code MCNP. In this article, the design of the target is discussed, results of all previous investigations are summarized, results of target testing and neutron generation are described, and results of simulation of neutron spectra are presented. PMID:19376729

Bayanov, B; Kashaeva, E; Makarov, A; Malyshkin, G; Samarin, S; Taskaev, S

2009-03-27

215

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

216

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

217

Proposal of a wide-band mirror polarizer of slow neutrons at a pulsed neutron source  

Microsoft Academic Search

The new type of wide-band mirror-based neutron polarizer, which is to be operated at a pulsed neutron source, is suggested. The idea is to use a movable polarizing mirror system, which, with the incoming beam monochromatized by the time-of-flight, would allow one to tune glancing angles in time so that the total reflection condition is always fulfilled only for one

Yu. V. Nikitenko; Yu. M. Ostanevich

1993-01-01

218

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

PubMed

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 (7)Li(p,n)(7)Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine to be placed on high current IPPE proton accelerator KG-2.5. Results of calculation were experimentally tested and are in good agreement with measurements. PMID:15308184

Kononov, O E; Kononov, V N; Bokhovko, M V; Korobeynikov, V V; Soloviev, A N; Sysoev, A S; Gulidov, I A; Chu, W T; Nigg, D W

2004-11-01

219

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

220

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

221

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

222

Fission reactor neutron sources for neutron capture therapy--a critical review.  

PubMed

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, at least one is suitable for use in high through-put routine therapy. It is concluded that reactor-based epithermal neutron beams with near optimum characteristics are currently available and more can be constructed at existing reactors. Suitable reactors include relatively low power reactors using the core directly as a source of neutrons or a fission converter if core neutrons are difficult to access. Thermal neutron beams for NCT studies with small animals or for shallow tumor treatments, with near optimum properties have been available at reactors for many years. Additional high quality thermal beams can also be constructed at existing reactors or at new, small reactors. Furthermore, it should be possible to design and construct new low power reactors specifically for NCT, which meet all requirements for routine therapy and which are based on proven and highly safe reactor technology. PMID:12749699

Harling, Otto K; Riley, Kent J

223

Neutron Radiographic Inspection of Industrial Components using Kamini Neutron Source Facility  

NASA Astrophysics Data System (ADS)

Kamini (Kalpakkam Mini) reactor is a U233 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 1012 n/cm2 s-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 mm×70 mm. Flux at the outer end of the beam tube is ~106-107 n/cm2 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.

2008-03-01

224

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

225

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

226

Residual stress measurement using the pulsed neutron source at LANSCE  

SciTech Connect

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

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

1991-01-01

227

Neutrino Physics at the Pulsed Spallation Neutron Source SNS.  

National Technical Information Service (NTIS)

An experimental facility for neutrino physics at the Spallation Neutron Source SNS at the Rutherford Appleton Laboratories in Chilton, England, is described. Neutrinos nu sub( mu ), nu sub(e) and anti nu sub( mu ) will be produced by the SNS with energies...

R. Maschuw B. Zeitnitz

1982-01-01

228

Advanced neutron source reactor probabilistic flow blockage assessment.  

National Technical Information Service (NTIS)

The Phase I Level I Probabilistic Risk Assessment (PRA) of the conceptual design of the Advanced Neutron Source (ANS) Reactor identified core flow blockage as the most likely internal event leading to fuel damage. The flow blockage event frequency used in...

C. T. Ramsey

1995-01-01

229

Advanced neutron source three-element-core fuel grading.  

National Technical Information Service (NTIS)

The proposed Advanced Neutron Source (ANS) pre-conceptual design consists of a two-element 330 MW(sub f) nuclear reactor fueled with highly-enriched uranium and is cooled, moderated, and reflected with heavy water. Recently, the ANS design has been change...

J. C. Gehin

1995-01-01

230

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

231

Advanced neutron source reactor probabilistic flow blockage assessment  

Microsoft Academic Search

The Phase I Level I Probabilistic Risk Assessment (PRA) of the conceptual design of the Advanced Neutron Source (ANS) Reactor identified core flow blockage as the most likely internal event leading to fuel damage. The flow blockage event frequency used in the original ANS PRA was based primarily on the flow blockage work done for the High Flux Isotope Reactor

1995-01-01

232

Neutrino Cross-Section Measurements at the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

In this paper we discuss the proposal to build a neutrino facility at the recently-completed Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL). This facility can host an extensive, long-term program to study neutrino-nucleus cross-sections in the range of interest for nuclear astrophysics and nuclear theory.

Stancu, Ion

2008-02-01

233

Emittance characterization of the spallation neutron source H- injector  

NASA Astrophysics Data System (ADS)

The H- injector for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory consists of a RF H- ion source and a compact electrostatic low-energy beam transport (LEBT) section. Up to 5 ion sources and up to 4 LEBT assemblies are alternated for the SNS beam operations. The beam current and emittance of the H- beam exiting the LEBT were characterized on the test-stand for different sources and LEBT assemblies in order to understand and minimize their performance variations.

Han, B. X.; Stockli, M. P.; Welton, R. F.; Murray, S. N., Jr.; Pennisi, T. R.; Santana, M.

2013-02-01

234

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

235

Intense pulsed neutron source status report  

SciTech Connect

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

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

1990-01-01

236

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

237

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

238

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

PubMed

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

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

2012-07-04

239

Localization of the source of terrestrial neutron bursts detected in thunderstorm atmosphere  

Microsoft Academic Search

To localize an altitude of the neutron source responsible for the neutron flux enhancements observed on the ground, numerical simulations of photonuclear production and transport to on-ground detector locations were carried out. The neutron fluence calculated for the volumetric source located at the altitudes 8–12 km is consistent with that estimated from neutron numbers measured on the ground. This altitude

Leonid P. Babich; Evgenii I. Bochkov; Igor M. Kutsyk; Robert A. Roussel-Dupré

2010-01-01

240

YAP scintillators for resonant detection of epithermal neutrons at pulsed neutron sources  

SciTech Connect

Recent studies indicate the resonance detector (RD) technique as an interesting approach for neutron spectroscopy in the electron volt energy region. This work summarizes the results of a series of experiments where RD consisting of YAlO{sub 3} (YAP) scintillators were used to detect scattered neutrons with energy in the range 1-200 eV. The response of YAP scintillators to radiative capture {gamma} emission from a {sup 238}U analyzer foil was characterized in a series of experiments performed on the VESUVIO spectrometer at the ISIS pulsed neutron source. In these experiments a biparametric data acquisition allowed the simultaneous measurements of both neutron time-of-flight and {gamma} pulse height (energy) spectra. The analysis of the {gamma} pulse height and neutron time of flight spectra permitted to identify and distinguish the signal and background components. These measurements showed that a significant improvement in the signal-to-background ratio can be achieved by setting a lower level discrimination on the pulse height at about 600 keV equivalent photon energy. Present results strongly indicate YAP scintillators as the ideal candidate for neutron scattering studies with epithermal neutrons at both very low (<5 deg.) and intermediate scattering angles.

Tardocchi, M.; Gorini, G.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Rhodes, N.; Schooneveld, E. M. [INFM, UdR Milano-Bicocca, Milan (Italy); Universita degli Studi di Milano-Bicocca, Dipartimento di Fisica 'G. Occhialini', Milan (Italy); INFM, UdR Tor Vergata, Rome (Italy); Universita degli Studi di Roma 'Tor Vergata', Dipartimento di Fisica, Rome (Italy); Rutherford Appleton Laboratory, ISIS Facility, Didcot (United Kingdom)

2004-11-01

241

AMERICIUM-BERYLLIUM AND PLUTONIUM-BERYLLIUM NEUTRON SOURCE RELATIVE EFFECTIVENESS IN PROMPT-GAMMA ACTIVATION ANALYSIS  

Microsoft Academic Search

S>The relative effectiveness in prompt-gamma neutron activation analysis ; of two Pu-Be isotopic neutron sources and an Am - Be neutron source is compared. ; Thermal neutron levels and the associated gamma radiation produced by these ; sources in a standard moderating system are normalized to the nominal neutron ; emission rate. The methods of measurement include a BFâ neutron

E. D. Jordan; H. E. Schierling

1962-01-01

242

Possible Use of a Spallation Neutron Source for Neutron Capture Therapy with Epithermal Neutrons.  

National Technical Information Service (NTIS)

Spallation is induced in a heavy material by 72 MeV protons. The hereby produced neutrons with essentially an evaporation spectrum with a peak energy of less than 2 MeV are moderated in two steps, first in iron, and then in carbon. Results from neutron fl...

E. Grusell H. Conde B. Larsson T. Roennqvist O. Sornsuntisook

1989-01-01

243

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

244

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

245

The neutron source calibration program at the National Institute of Standards and Technology  

SciTech Connect

The National Institute of Standards and Technology (NIST) has continually provided calibration services for radioisotopic neutron sources since the early 1960s, and NIST maintains one of the world's premier calibration facilities, whereby neutron source emission rates are determined via the Manganous sulfate bath technique. NIST provides this calibration service for neutron sources with emission rates (source strength) ranging from 5 x 10{sup 5} to 1 x 10{sup 10} s{sup {minus}1}. The Neutron Source Calibration Facility also provides important contributions to NIST's research programs in nuclear reactor pressure vessel dosimetry, neutron metrology, and fundamental neutron physics.

Adams, J.M.

2000-07-01

246

Accelerator-Driven Neutron Source for Cargo Screening  

SciTech Connect

Advanced neutron interrogation systems for the screening ofsea-land cargo containers for shielded special nuclear materials (SNM)require a high-yield neutron source to achieve the desired detectionprobability, false alarm rate, and throughput. An accelerator-drivenneutron source is described that produces a forward directed beam ofhigh-energy (up to 8.5 MeV) neutrons utilizing the D(d,n)3He reaction atdeuteron beam energies of up to 6 MeV. The key components of the neutronsource are a high-current RFQ accelerator and an innovative neutronproduction target. A microwave-driven deuteron source is coupled to anelectrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1meter-long, 200 MHz RFQ. The RFQ is based on an unusual beam dynamicsdesign and is capable of operating at a duty factor that produces morethan 1.2 mA timeaverage beam current. The beam is transported to a2-atmosphere deuterium gas target with a specially-designed, thinentrance window. A high-frequency dipole magnet is used to spread thebeam over the long dimension of the 4 by 35 cm target window. The sourcewill be capable of delivering a neutron flux of ~;2 x 107 n/(cm2 x s) tothe center of a sea-land cargo container and is expected t o satisfy therequirements for full testing and demonstration of advanced neutroninterrogation techniques based on stimulated SNM signatures.

Ludewigt, B.A.; Bleuel, D.L.; Hoff, M.D.; Kwan, J.W.; Li, D.; Ratti, A.; Staples, J.W.; Virostek, S.P.; Wells, R.P.

2006-11-15

247

A high power accelerator driver system for spallation neutron sources  

SciTech Connect

This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). For several years, the Los Alamos Meson Physics Facility (LAMPF) and the Proton Storage Ring (PSR) have provided a successful driver for the nearly 100-kW Los Alamos Neutron Scattering Center (LANSCE) source. The authors have studied an upgrade to this system. The goal of this effort was to establish a credible design for the accelerator driver of a next-generation source providing 1-MW of beam power. They have explored a limited subset of the possible approaches to a driver and have considered only the low 1-MW beam power. The next-generation source must utilize the optimum technology and may require larger neutron intensities than they now envision.

Jason, A.; Blind, B.; Channell, P. [and others

1996-07-01

248

Thick beryllium target as an epithermal neutron source for neutron capture therapy.  

PubMed

Accelerator-based intense epithermal neutron sources for Neutron Capture Therapy (NCT) have been considered as an alternative to nuclear reactors. Lithium (Li) has generally received the widest attention for this application, since the threshold energy is low and neutron yield is high. Because of the poor thermal and chemical properties of Li and the need for heat removal in the target, the design of Li targets has been quite difficult. Beryllium (Be) has been thought of as an alternative target because of its good thermal and chemical properties and reasonable neutron yield. However, in order to have a neutron yield comparable to that of a thick Li target bombarded with 2.5 MeV protons, the proton energy required for a thick Be target must be approaching 4 MeV. Consequently, the neutrons emitted are more energetic. In addition, a significant amount of high-energy gamma rays, which is undesirable, will occur when Be is bombarded with low-energy protons. Regardless of the more energetic neutrons and additional gamma rays, in this paper it is shown that it is possible to develop a high-quality and high-intensity epithermal neutron beam based on a thick Be target for NCT treatment. For a fixed proton current, the optimal Be-target-based beam (with 4-MeV protons) can produce a neutron beam, with both quality and intensity slightly better than those produced by the optimal Li-target-based beam (with 2.5-MeV protons). The single-session NCT treatment time for the optimal Be-target-based beam is estimated to be 88 min for a proton current of 50 mA.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7869996

Wang, C K; Moore, B R

1994-10-01

249

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

250

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

251

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

252

A status report on the Advanced Neutron Source Project  

SciTech Connect

The Advanced Neutron Source (ANS) will be a new laboratory for neutron research, centered around a 330 MW(f) research reactor cooled and reflected by heavy water and including extensive experiment systems and support facilities. The major components of the baseline design, occupying about 16 heetares, are a guide hall/research support area, containing most of the neutron beam experiment systems, shops and supporting laboratories; a 60 m diameter containment building housing the reactor and its primary coolant system, and selected scientific research facilities; an operations support building with the majority of the remaining plant systems; an office/interface complex providing a carefully designed, user friendly entry point for access control; and several other major facilities including user housing, an electrical substation, a diesel generator building, a cryorefrigerator building, and heavy water cleanup and upgrade systems.

West, C.D.

1993-10-01

253

Review of spent-fuel photon and neutron source spectra  

SciTech Connect

The calculations of spent-fuel photon and neutron spectra have been significantly improved over the past several years. Methods for performing these computations at ORNL have been implemented in the ORIGEN2 and ORIGEN-S codes and the SAS2 control module of the SCALE system. The codes use photon data for delayed gamma rays, x-rays, spontaneous fission gamma rays, (..cap alpha..,n) reaction gamma rays, bremsstrahlung and decay constants, taken mainly from the Evaluated Nuclear Data Structure File. The data for neutron source strengths and spectral distributions of spontaneous fission and (..cap alpha..,n) reactions were compiled from several different research projects. Brief discussions of the codes, the spectral data and the range of applicability are presented. Also, several examples of spent-fuel photon and neutron spectra are included. 29 refs.

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

1986-01-01

254

Spallation Ultracold Neutron Source of Superfluid Helium below 1 K  

NASA Astrophysics Data System (ADS)

For the production of high-density ultracold neutrons (UCNs), we placed 0.8 K superfluid helium in a cold neutron moderator. We resolved previous heat-load problems in the spallation neutron source that were particularly serious below 1 K. With a proton-beam power of 400MeV×1?A, a UCN production rate of 4UCNcm-3s-1 at the maximum UCN energy of Ec=210neV and a storage lifetime of 81 s were obtained. A cryogenic test showed that the production rate can be increased by a factor of 10 with the same storage lifetime by increasing the proton-beam power as well as He3 pumping speed.

Masuda, Yasuhiro; Hatanaka, Kichiji; Jeong, Sun-Chan; Kawasaki, Shinsuke; Matsumiya, Ryohei; Matsuta, Kensaku; Mihara, Mototsugu; Watanabe, Yutaka

2012-03-01

255

Neutronic analysis of three-element core configurations for the Advanced Neutron Source Reactor  

SciTech Connect

Calculations of several important neutronic parameters have been performed for ten different three-element configurations considered for the Advanced Neutron Source (ANS) Reactor. Six of these configurations (labeled ST, SB, MT, MB, LT, and LB) are there result of the permutations of the same three elements. Two configurations (ST- MOD and SB-MOD) have the same element configuration as their base core design (ST and SB) but have slightly different element dimensions, and two configurations (ST-OL1 and ST-OL2) have two overlapping elements to increase the neutron fluxes in the reflector. For each configuration, in addition to the conceptual two-element design, fuel-cycle calculations were performed with calculations required to obtain unperturbed fluxes. The element power densities, peak thermal neutron flux as a function of position throughout the cycle, fast flux, fast-to-thermal flux ratios, irradiation and production region fluxes, and control rod worth curves were determined. The effective multiplication factor for each fuel element criticality. A comparison shows that the ST core configurations have the best overall performance, and the fully overlapping core configuration ST-OL2 has the best performance by a large margin. Therefore, on the basis of the neutronics results, the fully overlapping configuration is recommended for further consideration in using a three-element ANS reactor core. Other considerations such as thermal-hydraulics, safety, and engineering that are not directly related to the core neutronic performance must be weighed before a final design is chosen.

Gehin, J.C.

1995-08-01

256

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

257

The rf System for the National Spallation Neutron Source Linac*  

NASA Astrophysics Data System (ADS)

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, a storage ring, a neutron target, and an experimental area. Although the NSNS is to be built at Oak Ridge, the design responsibility has been 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 accelerator, to the entrance to the storage ring. In the baseline design, a total of 42 klystrons are used to provide the rf power for a 2-MW average power, 1 ms pulse length, 6klystron is capable of 5 MW peak power into a flat load, but two designs are being considered: klystrons with and without a modulating anode. 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.

Tallerico, Paul; Billen, James; Jason, Andrew; Lynch, Michael; Wangler, Thomas; Young, Lloyd

1997-05-01

258

Stellar neutron sources and s-Process in Massive Stars  

NASA Astrophysics Data System (ADS)

Potential stellar neutron sources for the s-process in massive stars are associated with ?-capture reactions on light nuclei. The capture-reaction rates provide the reaction flow for the buildup of the neutron sources ^22Ne, and ^26Mg during the helium-burning phase in stars. A critical influence on these reactions is expected to come from low-energy resonances at stellar energies between 300 keV and 1500 keV. It is possible that these resonances are characterized by a pronounced cluster structure near the ?-threshold. Direct measurements of capture reactions to study the cluster structure are handicapped by the Coulomb barrier and limited detector resolutions. Hence, inelastic ?-scattering on these nuclei has been used as an alternative tool to probe into the level structure. In reference to this, the experiment performed using the Grand Raiden Spectrometer at RCNP, Osaka will be discussed and preliminary results will be presented.

Talwar, R.; Berg, G. P. A.; Bin, L.; Couder, M.; Deboer, R.; Fang, X.; Fujita, H.; Fujita, Y.; Goerres, J.; Hatanaka, K.; Itoh, T.; Kadoya, T.; Long, A.; Masaru, Y.; Matsuda, Y.; Miki, K.; Tamii, A.; Wiescher, M.

2012-10-01

259

Mechanical design of the prototype H- ion source for the Spallation Neutron Source  

Microsoft Academic Search

The mechanical design of the prototype H- ion source for the Spallation Neutron Source (SNS) is presented. Experience obtained in the ongoing SNS R&D program is being utilized in the current design. The physics design parameters require a 2 MHz RF-driven multicusp ion source operated at 50kW, pulsed (6% duty factor) RF-power. The four major components (plasma-generator, cesium collar, outlet

S. K. Mukherjee; D. Cheng; M. A. Leitner; K. N. Leung; P. A. Luft; R. A. Gough; R. Keller; M. D. Williams

1999-01-01

260

SPALLATION NEUTRON SOURCE OPERATIONAL EXPERIENCE AT 1 MW  

SciTech Connect

The Spallation Neutron Source (SNS) has been operating at the MW level for about one year. Experience in beam loss control and machine activation at this power level is presented. Also experience with machine protection systems is reviewed, which is critical at this power level. One of the most challenging operational aspects of high power operation has been attaining high availability, which is also discussed

Galambos, John D [ORNL

2011-01-01

261

Analysis of new SHEBA for feedback and internal neutron source  

SciTech Connect

SHEBA (Solution High Energy Burst Assembly) was built at the Los Alamos National Laboratory, New Mexico, in the 1980s. Both SHEBA-I and -II used uranyl fluoride solution with 4.95% enriched {sup 235}U. The fluoride solution is being replaced by 20% enriched {sup 235}U in nitrate solution. Two concentrations have been considered: 150 and 180 g/{ell} uranium. Temperature feedback, volumetric feedback, and its internal neutron source are calculated using transport codes and other computer programs.

Lee, S. [Univ. of Arizona, Tucson, AZ (United States)

1996-12-31

262

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

263

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

264

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

PubMed

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

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

2004-11-01

265

GE PETtrace cyclotron as a neutron source for boron neutron capture therapy.  

PubMed

This paper discusses the use of a General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy. In particular, the standard PETtrace (18)O target is considered. The resulting dose from the neutrons emitted from the target is evaluated using the Monte Carlo radiation transport code MCNP at different depths in a brain phantom. MCNP-simulated results are presented at 1, 2, 3, 4, 5, 6, 7, and 8 cm depth inside this brain phantom. Results showed that using a PETtrace cyclotron in the current configuration allows treating tumors at a depth of up to 4 cm with reasonable treatment times. Further increase of a beam current should significantly improve the treatment time and allow treating tumors at greater depths. PMID:15308192

Bosko, A; Zhilchenkov, D; Reece, W D

2004-11-01

266

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

Microsoft Academic Search

Lanthanum bromide (LaBr3:Ce) scintillators offer significantly better resolution (<3 percent at 662keV) relative to sodium iodide (NaI(Tl)) but contain internal radioactivity that contributes to spectral counts. LaBr3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5×1.5-in. LaBr3:Ce

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

2007-01-01

267

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

268

The Advanced Neutron Source Facility: A new user facility for neutron research  

SciTech Connect

The Advanced Neutron Source (ANS) is a new reactor-based research facility being planned by Oak Ridge National Laboratory (ORNL) to meet the need for an intense steady state source of neutrons and for associated research space and equipment. The ANS will be open for use by scientists from universities, industry, and other federal laboratories. The ANS will be built around a new research reactor of unprecedented flux; that is, it will produce the most intense continuous beams of neutrons in the world. The goal is to reach a thermal neutron flux for beam experiments of 5 /times/ 10/sup 19/ to 10 /times/ 10/sup 19/ neutrons/(m/sup 2//center dot/s/sup /minus/1/). By combining the higher source flux with improved experimental facilities, the ANS will surpass current US high flux reactors---the High Flux Isotope Reactor (HFIR) at ORNL and the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory---by a factor of 10 to 20. The safety analysis of the ANS facility will include a complete probabilistic risk assessment (PRA), which will provide a systematic assessment of dependencies among systems at the malfunctions. For the current generation of nuclear power plants that have recently undergone the licensing review process, PRA has been used an an analysis tool after completion of the plant designs. For the ANS Project, the PRA effort has already begun, before the facility conceptual design. This allows safety insights from the PRA to be incorporated into the evolving plant design. 4 refs., 6 figs.

West, C.D.

1988-01-01

269

Design and Applications of a {sup 252}Cf Cold Neutron Source  

SciTech Connect

The goal was to design a source of cold neutrons from such sources as {sup 252}Cf, {sup 241}Am-Be, {sup 244}Cm-Be, or {sup 124}Sb-Be and to find the limitations when such a source is applied to neutron activation analysis. Here, cold neutrons are neutrons with a kinetic energy < 0.01 eV. The initial kinetic energy of most of the neutrons produced from the decay of the {sup 252}Cf nucleus lies in the range from 0.5 to 10 MeV, so moderation is necessary to produce a significant quantity of cold neutrons from these initial neutrons. The same is true for the other three neutron sources. The general design that was selected for the cold neutron source has two moderation regions, and the geometry was restricted to cylindrical symmetry with the sample region along the cylindrical axis. The moderation regions may have different temperatures and may contain different moderating materials. The design tasks are then to find the optimum geometry, moderating materials, and moderating temperatures. A cold neutron flux in the sample region of 2.7 x 10 {sup -3} cold neutrons per source neutron is obtainable in a {sup 252}Cf cold neutron source that has polyethylene as the cold and thermal moderator or with trimethylbenzene as the cold moderator and polyethylene as the thermal moderator. The neutron fluxes obtained are probably within 10{percent} of the fluxes that would be obtained in an actual cold neutron source that is based on the model used. This flux of cold neutrons is adequate for sensitive prompt and delayed neutron activation analysis measurements. The results show that a useful flux of cold neutrons can be obtained from small amounts of {sup 252}Cf, {sup 241}Am, {sup 244}Cm, or {sup 124}Sb.

Elijah Johnson; Larry Robinson; Li Zhao

2000-11-12

270

Computational Benchmark Calculations Relevant to the Neutronic Design of the Spallation Neutron Source (SNS)  

SciTech Connect

The Spallation Neutron Source (SNS) will provide an intense source of low-energy neutrons for experimental use. The low-energy neutrons are produced by the interaction of a high-energy (1.0 GeV) proton beam on a mercury (Hg) target and slowed down in liquid hydrogen or light water moderators. Computer codes and computational techniques are being benchmarked against relevant experimental data to validate and verify the tools being used to predict the performance of the SNS. The LAHET Code System (LCS), which includes LAHET, HTAPE ad HMCNP (a modified version of MCNP version 3b), have been applied to the analysis of experiments that were conducted in the Alternating Gradient Synchrotron (AGS) facility at Brookhaven National Laboratory (BNL). In the AGS experiments, foils of various materials were placed around a mercury-filled stainless steel cylinder, which was bombarded with protons at 1.6 GeV. Neutrons created in the mercury target, activated the foils. Activities of the relevant isotopes were accurately measured and compared with calculated predictions. Measurements at BNL were provided in part by collaborating scientists from JAERI as part of the AGS Spallation Target Experiment (ASTE) collaboration. To date, calculations have shown good agreement with measurements.

Gallmeier, F.X.; Glasgow, D.C.; Jerde, E.A.; Johnson, J.O.; Yugo, J.J.

1999-11-14

271

Surviving to tell the tale : Argonne's Intense Pulsed Neutron Source from an ecosystem perspective  

Microsoft Academic Search

At first glance the story of the Intense Pulsed Neutron Source (IPNS), an accelerator-driven neutron source for exploring the structure of materials through neutron scattering, seems to be one of puzzling ups and downs. For example, Argonne management, Department of Energy officials, and materials science reviewers continued to offer, then withdraw, votes of confidence even though the middling-sized IPNS produced

C. Westfall

2010-01-01

272

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

273

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

274

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

275

Advanced Neutron Source Reactor thermal analysis of fuel plate defects  

SciTech Connect

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

Giles, G.E.

1995-08-01

276

Accumulator ring lattice for the national spallation neutron source  

SciTech Connect

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

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

1997-08-01

277

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

278

A Search for Point Sources of EeV Neutrons  

NASA Astrophysics Data System (ADS)

A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from -90° to +15° in declination using four different energy ranges above 1 EeV (1018 eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.

Pierre Auger Collaboration; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Anti?i'c, T.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Bohá?ová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Buroker, L.; Burton, R. E.; Caballero-Mora, K. S.; Caccianiga, B.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chirinos Diaz, J.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; del Río, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filip?i?, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jansen, S.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; LaHurd, D.; Latronico, L.; Lauer, R.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Meyhandan, R.; Mi'canovi'c, S.; Micheletti, M. I.; Minaya, I. A.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pe?ala, J.; Pelayo, R.

2012-12-01

279

Coded source neutron imaging at the PULSTAR reactor  

NASA Astrophysics Data System (ADS)

A neutron imaging facility is located on beam-tube #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 34×38 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; Mishra, Kaushal K.; Hawari, Ayman I.; Bingham, Philip R.; Bilheux, Hassina Z.; Tobin, Kenneth W.

2011-10-01

280

Experimental tests with MISANS (Modulated Intensity Small Angle Neutron Scattering) at IPNS (Intense Pulsed Neutron Source).  

SciTech Connect

In this paper we describe the latest tests of the MISANS spectrometer at the IPNS in Argonne, USA. At this stage the time resolution and more importantly the contrast of the modulation at the detector is very low, nevertheless it was possible to perform a MISANS-measurement and test some features typical for a pulsed neutron source. The MISANS technique has a huge potential to improve its contrast and resolution towards a high resolution spin echo spectrometer.

Bleuel, M.; Gahler, R.; Lang, E.; Lal, J.; Inst. Laue Langevin

2009-01-01

281

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

282

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

283

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

284

Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source  

SciTech Connect

Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically, probably at a small fraction of the cost of He-3 detectors. In addition to neutron scattering science, the fully developed base technology can be used as a rugged, low-cost neutron detector in area monitoring and surveying. Radiation monitors are used in a number of other settings for occupational and environmental radiation safety. Such a detector can also be used in environmental monitoring and remote nuclear power plant monitoring. For example, the Department of Energy could use it to characterize nuclear waste dumps, coordinate clean-up efforts, and assess the radioactive contaminants in the air and water. Radiation monitors can be used to monitor the age and component breakdown of nuclear warheads and to distinguish between weapons and reactor grade plutonium. The UN's International Atomic Energy Agency (IAEA) uses radiation monitors for treaty verification, remote monitoring, and enforcing the non-proliferation of nuclear weapons. As part of treaty verification, monitors can be used to certify the contents of containers during inspections. They could be used for portal monitoring to secure border checkpoints, sea ports, air cargo centers, public parks, sporting venues, and key government buildings. Currently, only 2% of all sea cargo shipped is inspected for radiation sources. In addition, merely the presence of radiation is detected and nothing is known about the radioactive source until further testing. The utilization of radiation monitors with neutron sensitivity and capability of operation in hostile port environments would increase the capacity and effectiveness of the radioactive scanning processes.

Lacy, Jeffrey L

2009-05-22

285

Materials Selection for the HFIR Cold Neutron Source  

SciTech Connect

In year 2002 the High Flux Isotope Reactor (HFIR) will be fitted with a source of cold neutrons to upgrade and expand its existing neutron scattering facilities. The in-reactor components of the new source consist of a moderator vessel containing supercritical hydrogen gas moderator at a temperature of 20K and pressure of 15 bar, and a surrounding vacuum vessel. They will be installed in an enlarged beam tube located at the site of the present horizontal beam tube, HB-4; which terminates within the reactor's beryllium reflector. These components must withstand exceptional service conditions. This report describes the reasons and factors underlying the choice of 6061-T6 aluminum alloy for construction of the in-reactor components. The overwhelming considerations are the need to minimize generation of nuclear heat and to remove that heat through the flowing moderator, and to achieve a minimum service life of about 8 years coincident with the replacement schedule for the beryllium reflector. 6061-T6 aluminum alloy offers the best combination of low nuclear heating, high thermal conductivity, good fabricability, compatibility with hydrogen, superior cryogenic properties, and a well-established history of satisfactory performance in nuclear environments. These features are documented herein. An assessment is given of the expected performance of each component of the cold source.

Farrell, K.

2001-08-24

286

Neutron interrogation to identify chemical elements with an ion-tube neutron source (INS)  

SciTech Connect

A non-destructive analysis technique using a portable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The broad range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should lead to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers.

Alvarez, R.A.; Dougan, A.D.; Rowland, M.R.; Wang, T.F.

1994-04-07

287

Spallation Neutron Source Beam Dump Radiation Shielding Analysis  

SciTech Connect

Preliminary shielding calculations were performed to establish the dimensions of the radiation shielding surrounding the three Spallation Neutron Source (SNS) beam stops. Steel shielding thicknesses were sized to give dose levels of 1, 2, and 5 mrem/h at the top of the shield, and, to provide enough shielding along the sides and bottom of the beam dump so that soil activation is not a problem. It was concluded that 144 in. of steel shielding is needed above the beam stop. The thickness of the concrete floor in the service building above the dump was not a part of these calculations. This shielding design is current as of January 2000.

Johnson, J.O.

2000-02-21

288

Finite element analysis of advanced neutron source fuel plates  

SciTech Connect

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

Luttrell, C.R.

1995-08-01

289

A compact neutron generator using a field ionization source  

SciTech Connect

Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-#12;bers promise the high #12;eld-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of #12;field emitters with a density up to 10{sup 6} tips/cm{sup 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.

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

2011-10-31

290

A compact neutron generator using a field ionization source  

SciTech Connect

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{sup 6} tips/cm{sup 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.

Persaud, Arun; Waldmann, Ole; Schenkel, Thomas [E.O. Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kapadia, Rehan; Takei, Kuniharu; Javey, Ali [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States)

2012-02-15

291

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

292

POWER SUPPLY CONTROL FOR THE SPALLATION NEUTRON SOURCE.  

SciTech Connect

Brookhaven National Laboratory is currently constructing an accumulator ring as part of a six laboratory collaboration to build the Spallation Neutron Source (SNS) that will be located in Oak Ridge, Tennessee. Control of the power supplies will be implemented using a simple integrated system that provides all functions (setpoint, readback, control and status) with a single board at the power converter. Communication between the power supply interface and the VME control card is through a pair of fibers that also provides electrical isolation. This paper describes the power supply control system and it's impact on the SNS.

LAMBIASE, R.F.; OERTER, B.; SMITH, J.

2000-06-30

293

BEAM LOSS MITIGATION IN THE OAK RIDGE SPALLATION NEUTRON SOURCE  

SciTech Connect

The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and compare the design vs. the loss-minimized equipment parameters.

Plum, Michael A [ORNL

2012-01-01

294

Neutron source capability assessment for cumulative fission yields measurements  

SciTech Connect

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

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

2011-04-06

295

SPALLATION NEUTRON SOURCE RING-DESIGN AND CONSTRUCTION SUMMARY.  

SciTech Connect

After six years, the delivery of components for the Spallation Neutron Source (SNS) accumulator ring (AR) and the transport lines was completed in Spring 2005. Designed to deliver 1.5 MW beam power (1.5 x 10{sup 14} protons of 1 GeV kinetic energy at a repetition rate of 60 Hz), stringent measures were implemented in the fabrication, test, and assembly to ensure the quality of the accelerator systems. This paper summarizes the design, R&D, and construction of the ring and transport systems.

WEI,J.

2005-05-16

296

Creep analysis of fuel plates for the Advanced Neutron Source  

SciTech Connect

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, the plates will still be at elevated temperatures while in service, and the potential for excessive plate deformation because of creep must be considered. An analysis to include creep for deformation and stresses because of temperature over a given time span has been performed and is reported herein.

Swinson, W.F.; Yahr, G.T.

1994-11-01

297

The Los Alamos National Laboratory Neutron Source Reclamation Program  

SciTech Connect

Over the past fifty years, the Los Alamos National Laboratory has developed an extensive capability to handle significant quantities of nuclear materials as part of its role in support of DOE Defense Program activities. The goals and objectives of these activities are met through a base program in nuclear materials technology research, development, and demonstration as well as through additional programs (such as the Neutron Source Reclamation Program) aimed at specific, often near-term goals. This base program encompasses (1) plutonium process technology research, development and demonstration activities, (2) technology transfer and offsite technical support, (3) nuclear materials recycle and recovery, and (4) nuclear facility operations and maintenance.

Behrens, R.G.; Jones, S.W.

1994-05-01

298

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

299

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

300

Measurements on H{sup -} sources for spallation neutron source application  

SciTech Connect

Lawrence Berkeley National Laboratory is engaged in the development of H{sup -} ion sources for the upgrade of the Los Alamos Neutron Science Center (LANSCE) facility and the spallation neutron source (SNS) to be built in the U.S. For the upgrade of the LANSCE facility, the H{sup -} ion generator has to deliver an output current of 40 mA. The repetition rate must be 120 Hz at a pulse length of 1 ms (12% duty factor). Furthermore, the normalized emittance must be less than 0.1{pi} mm mrad. During the last years, the Ion Beam Technology Group of the LBNL improved the so-called surface conversion source for the generation of higher H{sup -} currents. In the first part of this article, we discuss the operation conditions of the source at the required 40 mA output current. The ion source for the 1 MW spallation neutron source is required to provide 35 mA of H{sup -} beam current at 6% duty factor (1 ms pulses at 60 Hz) with a normalized rms emittance of less than 0.2{pi} mm mrad. The H{sup -} beam will be accelerated to 65 keV and matched into a 2.5 MeV RFQ. The ion source is expected to ultimately produce 70 mA of H{sup -} at 6% duty factor when the SNS is upgraded to 2 MW of power. For this application, a radio-frequency driven, magnetically filtered multicusp source is being developed at LBNL. Experimental results (including emittance measurements) on the performance of the prototype ion source operated at the demanded beam parameters will be presented in this article. (c) 2000 American Institute of Physics.

Thomae, R. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Gough, R. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Keller, R. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Leitner, M. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Leung, K. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Meyer, D. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Williams, M. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

2000-02-01

301

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

SciTech Connect

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

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

2010-02-15

302

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

PubMed

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. PMID:20192461

Han, B X; Stockli, M P; Welton, R F; Pennisi, T R; Murray, S N; Santana, M; Long, C D

2010-02-01

303

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

304

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

305

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

306

Detection of buried explosives using portable neutron sources with nanosecond timing.  

PubMed

Significant reduction of time needed to identify hidden explosives and other hazardous materials by the "neutron in, gamma out" method has been achieved by introducing timed (nanosecond) neutron sources-the so-called nanosecond neutron analysis technique. Prototype mobile device for explosives' detection based on a timed (nanosecond) isotopic (252)Cf neutron source has been created. The prototype is capable of identifying 400 g of hidden explosives in 10 min. Tests have been also made with a prototype device using timed (nanosecond) neutron source based on a portable D-T neutron generator with built-in segmented detector of accompanying alpha-particles. The presently achieved intensity of the neutron generator is 5x10(7)n/s into 4pi, with over 10(6) of these neutrons being correlated with alpha-particles detected by the built-in alpha-particle detector. Results of measurements with an anti-personnel landmine imitator are presented. PMID:15145438

Kuznetsov, A V; Evsenin, A V; Gorshkov, I Yu; Osetrov, O I; Vakhtin, D N

2004-07-01

307

The 4.438 MeV gamma to neutron ratio for the Am-Be neutron source.  

PubMed

An accurate measurement of the 4.438 MeV gamma-ray to total neutron ratio, namely R=Sgamma/Sn, for a Chinese-made Am-Be neutron source is described. The neutron strength of the source relative to a previously standardized source was determined by the manganese bath technique. The gamma-rays spectra of the source were measured using a Ø 75 x 75 mm NaI(Tl) detector. The background induced by neutrons and the absolute full energy peak efficiency of the detector were calculated using the MCNP code. The experimental ratio so obtained agrees well with the calculated value. A synthetic evaluated and recommended value of R=0.575+/-4.8% was given. We conclude that the experimental R-value appears an important characteristic for an Am-Be source. PMID:17574426

Liu, Zhenzhou; Chen, Jinxiang; Zhu, Pei; Li, Yongming; Zhang, Guohui

2007-04-14

308

5 MW pulsed spallation neutron source, Preconceptual design study  

SciTech Connect

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

Not Available

1994-06-01

309

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

310

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

311

Energy variable deuteron linac for materials research neutron source  

SciTech Connect

Basic research in new materials and materials technology is a key national resource, and several countries are making plans for advanced capabilities, including intense neutron sources. Advances in high-intensity linear accelerator technology can provide efficient drivers for such sources. Aspects such as energy variability, uniformity of target dose distribution, target bombardment from multiple directions, time-scheduled dose patterns, and other features can be provided, opening new opportunities in the experimental program. These considerations are discussed in the context of 20--40 mA continuous-current, 35-MeV compact deuteron linac facility, as a subset of designs with much larger (250 mA) current capability. The possibility for a current-upgradeable facility is briefly described. 11 refs., 2 figs., 1 tab.

Jameson, R.A.

1990-01-01

312

Assessment of neutron requirements and potential sources for fusion development  

NASA Astrophysics Data System (ADS)

The particular aims of this project were to (1) identify the anticipated critical failure modes for fusion components exposed to high neutron flux, (2) determine the minimum acceptable number of simple material property tests which would be required for acceptance of a material for use in these components, (3) identify appropriate neutron sources for this testing, and (4) identify and define appropriate subscale tests which address the problem of interactive material effects in these components. The high-flux components examined in this study were limited to the first wall, breeder and breeder structure. Eleven critical failure modes for these components were identified and ranked. Materials properties relevant to each of these failure modes were identified and ranked, and material property test matrices were devised. The minimum number of irradiated materials tests identified for the first wall materials under consideration (PCA, HT-9 and V-15Cr-5Ti) was found to be 904, a significant decrease from earlier studies. The minimum number of irradiated tests identified for the various breeder materials (Li2O, LiAlO2, Liquid Li, and Liquid Li-Pb) was 280. EBR-II, HFIR and FFTF were identified as the most appropriate fission-based sources for fusion materials testing.

Davis, J. W.

1985-05-01

313

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

314

Assessment of the Pu content of Pu–Be neutron sources  

Microsoft Academic Search

A nondestructive method for assaying sealed Pu–Be sources has been developed, using a combination of the ?-spectrometric determination of Pu isotopic abundances and neutron counting. A passive neutron coincidence collar was designed with nine 3He counters embedded in a polyethylene moderator surrounding the sources to be measured. The measurement cavity is lined with Cd to shield the source against slow

János Bagi; Tam Cong Nguyen; László Lakosi

2004-01-01

315

Characteristics and Performance of an Integrated Portable High Efficiency Neutron Multiplicity Counter for Detection of Illicit Neutron Sources  

Microsoft Academic Search

In the interdiction of illicitly trafficked Special Nuclear Material (SNM) the neutron signal is a valuable adjunct to the gamma-ray signature. Neutrons are not attenuated by heavy metal shielding which might be used to shield the gamma rays emitted by the source. However, \\

Timothy R. Twomey; Ronald M. Keyser

316

Brighter H/sup -/ source for the intense pulsed neutron source accelerator system  

SciTech Connect

Further increases in the beam intensity of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory required the replacement of the H/sup -/ source with a higher current source. A magnetron ion source of Fermi National Accelerator Laboratory (FNAL) design was adapted with a grooved cathode to provide a stable 40 to 50 mA of beam operating at 30 Hz for up to a 90 ..mu..s pulse duration. Problems of space charge blowup due to the lack of neutralization of the H/sup -/ beam were solved by injecting additional gs into the 20 keV transport system. The source has recently been installed in the machine and the available input to the accelerator has more than doubled.

Stipp, V.; DeWitt, A.; Madsen, J.

1983-01-01

317

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

318

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. Baeßler; B. Märkisch; M. Schumann; T. Soldner; O. Zimmer

2008-01-01

319

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

320

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

NASA Astrophysics Data System (ADS)

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 fast neutrons, which are emitted from the reaction between a beryllium target and 30-MeV protons accelerated by a cyclotron accelerator, using an optimum moderator system composed of iron, lead, aluminum and calcium fluoride. At present, an epithermal-neutron source is under construction from June 2008. This system consists of a cyclotron accelerator, beam transport system, neutron-yielding target, filter, moderator and irradiation bed. In this article, an overview of this system and the properties of the treatment neutron beam optimized by the MCNPX Monte Carlo neutron transport code are presented. The distribution of biological effect weighted dose in a head phantom compared with that of Kyoto University Research Reactor (KUR) is shown. It is confirmed that for the accelerator, the biological effect weighted dose for a deeply situated tumor in the phantom is 18% larger than that for KUR, when the limit dose of the normal brain is 10 Gy-eq. The therapeutic time of the cyclotron-based neutron sources are nearly one-quarter of that of KUR. The cyclotron-based epithermal-neutron source is a promising alternative to reactor-based neutron sources for treatments by BNCT.

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

2009-06-01

321

Design of a neutron radiography facility at the spallation source SINQ  

Microsoft Academic Search

The continuous-current neutron source SINQ is presently under construction at the Paul Scherrer Institute (Switzerland). First operational tests are scheduled to begin during the last quarter of 1996. SINQ will provide both thermal and cold neutron beams for a wide variety of experimental facilities.A neutron radiography facility has been designed and is under construction. It consists of the first collimation

Eberhard Lehmann; Helena Pleinert; Luzius Wiezel

1996-01-01

322

Design of a laboratory for experiments with a pulsed neutron source  

Microsoft Academic Search

We present the results of a neutron shielding design and optimisation study performed to reduce the exposure to radiological doses arising from a 14 MeV pulsed neutron generator (PNG) having a maximum emission strength of 2.0 × 108 neutrons s-1. The source was intended to be used in a new irradiation facility for the realisation of an experiment on acoustical

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

2009-01-01

323

Design of a laboratory for experiments with a pulsed neutron source  

Microsoft Academic Search

We present the results of a neutron shielding design and optimisation study performed to reduce the exposure to radiological doses arising from a 14 MeV pulsed neutron generator (PNG) having a maximum emission strength of 2.0 × 108 neutrons s?1. The source was intended to be used in a new irradiation facility for the realisation of an experiment on acoustical

G Memoli; J P M Trusler; A K Ziver

2009-01-01

324

A compact neutron source driven by a thyratron switched, pulsed current transformer  

Microsoft Academic Search

Pulsed neutron accelerators have been considered for active interrogation of special nuclear materials and also for location and imaging of explosives using PFNA. Alameda Applied Sciences Corporation is developing a <40 ns pulsed neutron source for these applications, based on the dense plasma focus (DPF). The Dense Plasma Focus (DPF) produces a 10-40 ns (FWHM) neutron pulse, with output scaling

M. Krishnan; B. Bures; R. Madden; J. Thompson

2009-01-01

325

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

326

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

2007-06-16

327

Materials compatibility studies for the Spallation Neutron Source  

SciTech Connect

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

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

1998-11-01

328

New evidence of an intense scission neutron source in the 252Cf spontaneous fission  

NASA Astrophysics Data System (ADS)

The neutron energy-angular distributions relative to the fragment direction of 252Cf (SF) were analysed. The results of three independent experiments being in reasonable agreement allows the conclusion that a (/30+/-5)% neutron surplus exists at ~90? relative to the direction of the moving fragments, which can not be accounted for with the assumption that all neutrons are emitted from fully accelerated fragments. This experimental fact required the incorporation of neutron emission from an additional source of neutrons. Angular and energy distributions of these additional neutrons were evaluated using data from an experiment performed at IRMM several years ago and were compared with the results in literature.

Kornilov, N. V.; Kagalenko, A. B.; Poupko, S. V.; Androsenko, P. A.; Hambsch, F.-J.

2001-04-01

329

Stationary DIANE equipment Description and performance of the thermal neutron source  

NASA Astrophysics Data System (ADS)

A new neutron radiography facility using a GENIE 46 generator is now operating at SODERN (France). In contrast to the first mobile DIANE system working at IABG (Germany), this new version uses a stationary thermal neutron source. With this second equipment the performance has been significantly improved. Thanks to computer simulations and experimental thermal neutron cartography, progress has been made on neutron moderation/thermalization (combination of lead and HD polyethylene), extraction geometry, neutron and photon collimation. The results in terms of gamma ray and thermal neutron contents in the beam are reported.

Cluzeau, S.; Le Tourneur, P.

1994-05-01

330

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

PubMed

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

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

2009-12-11

331

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 (>10{sup 18} W/cm{sup 2}) lasers to generate picosecond, collimated neutrons from a dual target configuration. In this article, the production capabilities of the 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.

Ellison, C. L. [Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States); Fuchs, J. [Laboratoire pour l'Utilisation des Lasers Intenses, UMR 7605, CNRS-CEA-Ecole Polytechnique-Universite Paris VI, 91128 Palaiseau (France)

2010-11-15

332

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

SciTech Connect

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

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

1996-07-01

333

An Am/Be neutron source and its use in integral tests of differential neutron reaction cross-section data.  

PubMed

An Am/Be neutron source, installed recently at the Rajshahi University, is described. Neutron flux mapping was done using the nuclear reactions (197)Au(n,gamma)(198)Au, (113)In(n,gamma)(114m)In, (115)In(n,n'gamma)(115m)In and (58)Ni(n,p)(58)Co. An approximate validation of the neutron spectral shape was done using five neutron threshold detectors and the iterative unfolding code SULSA. Integral cross sections of the reactions (54)Fe(n,p)(54)Mn, (59)Co(n,p)(59)Fe and (92)Mo(n,p)(92m)Nb were measured with fast neutrons (E(n)>1.5MeV) and compared with data calculated using the neutron spectral distribution and the excitation function of each reaction given in data libraries: an agreement within +/-6% was found. PMID:20206536

Uddin, M S; Zaman, M R; Hossain, S M; Spahn, I; Sudár, S; Qaim, S M

2010-02-20

334

Measurement of the spectral fluence rate of reference neutron sources with a liquid scintillation detector.  

PubMed

Reference neutron sources such as (241)AmBe(alpha,n) and (252)Cf are commonly used to calibrate neutron detectors for radiation protection purposes. The calibration factors of these detectors depend on the spectral distribution of the neutron fluence from the source. Differences between the spectral fluence of the neutron source and the ISO-recommended reference spectra might be caused by the properties of the individual source. The spectral neutron fluence rates of different reference neutron sources used at PTB were measured with a liquid scintillation detector (NE213), using maximum entropy unfolding and a new, experimentally determined detector response matrix. The detector response matrix was determined by means of the time-of-flight technique at a pulsed neutron source with a broad energy distribution realised at the PTB accelerator facility. The results of the measurements of the reference sources are compared with the ISO-recommended reference spectra. For the PTB (241)AmBe(alpha,n) reference source, the spectral neutron fluence was determined by means of a high-resolution (3)He semiconductor sandwich spectrometer in 1982. These measurements were the basis for the ISO recommendations. The current measurements confirm the high-energy part (E(n) > 2 MeV) of this spectrum and demonstrate the suitability of this new method for high-resolution spectrometry of broad neutron spectra. PMID:17553863

Zimbal, A

2007-06-06

335

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

336

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

SciTech Connect

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

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

1985-01-01

337

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

Grünauer, F; Schillinger, B; Steichele, E

2004-10-01

338

Gadolinium-neutron-activation determination with a Pu-Be source  

Microsoft Academic Search

A nondestructive neutron activation method for determining gadolinium content for reactor construction materials was developed. The method uses a Pu-Be neutron source capable of giving 10⁸ neutrons per second and the neutron reaction with a ¹⁶°Gd target. To determine the flux attenuation, induced-activity distributions were measured along the radius with artificial compacts of AlâOâ + GdâOâ specimens with varying gadolinium

A. E. Konyaev; V. F. Kositsyn; A. B. Medvedev; V. S. Rudenko

1988-01-01

339

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

340

Materials for spallation neutron sources, with emphasis on SNS facility  

SciTech Connect

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

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

1999-09-01

341

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, I. E.; Casagrande, F.; Crofford, M.; Howell, M.; Kang, Y.; Kim, S. H.; Kursun, Z.; Ladd, P.; Stout, D.; Strong, W. [Oak Ridge National Laboratory Oak Ridge, TN, 37831 (United States); Champion, M. [Fermi National Accelerator Laboratory Batavia, IL, 60510 (United States)

2008-03-16

342

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

343

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

344

EVOLUTION OF THE SPALLATION NEUTRON SOURCE RING LATTICE.  

SciTech Connect

Requirements of minimum beam loss for hand-on maintenance and flexibility for future operations are essential for the lattice design of the Spallation Neutron Source (SNS) accumulator ring. During the past seven years, the lattice has evolved from an all-FODO to a FODO/doublet hybrid, the circumference has been increased to accommodate for a higher energy foreseen with a super-conducting RF linac, and the layout has evolved from an {alpha}- to an {Omega}-geometry. Extensive studies are performed to determine working points that accommodate injection painting and minimize beam losses due to space charge and resonances. In this paper, we review the evolution of the SNS ring lattice and discuss the rationales.

WEI,J.; CATALAN - LASHERAS,N.; FEDOTOV,A.; GARDNER,C.J.; LEE,Y.Y.; PAPAPHILIPPOU,Y.; RAPARIA,D.; TSOUPAS,N.; HOLMES,J.

2002-04-08

345

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

346

Magnets for the national spallation neutron source accumulator ring  

SciTech Connect

The National Spallation Neutron Source Accumulator Ring will require large aperture dipole magnets, strong focusing quadrupole magnets, and smaller low field dipole, quadrupole, and sextupole correcting magnets. All of the magnets will provide a fixed magnetic field throughout the accumulator`s fill/storage/extraction cycle. Similar fixed field magnets will also be provided for the beam transport systems. Because of the high intensity in the accumulator, the magnets must be designed with high tolerances for optimum field quality and for the high radiation environment which may be present at the injection/extraction areas, near the collimators, and near the target area. Field specifications and field plots are presented as well as planned fabrication methods and procedures, cooling system design, support, and installation.

Tuozzolo, J.; Brodowski, J.; Danby, G. [and others

1997-07-01

347

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

348

Neutron activation analysis detection limits using {sup 252}Cf sources  

SciTech Connect

The Savannah River Technology Center (SRTC) developed a neutron activation analysis (NAA) facility several decades ago using low-flux {sup 252}Cf neutron sources. Through this time, the facility has addressed areas of applied interest in managing the Savannah River Site (SRS). Some applications are unique because of the site's operating history and its chemical-processing facilities. Because sensitivity needs for many applications are not severe, they can be accomplished using an {approximately}6-mg {sup 252}Cf NAA facility. The SRTC {sup 252}Cf facility continues to support applied research programs at SRTC as well as other SRS programs for environmental and waste management customers. Samples analyzed by NAA include organic compounds, metal alloys, sediments, site process solutions, and many other materials. Numerous radiochemical analyses also rely on the facility for production of short-lived tracers, yielding by activation of carriers and small-scale isotope production for separation methods testing. These applications are more fully reviewed in Ref. 1. Although the flux [{approximately}2 x 10{sup 7} n/cm{sup 2}{center_dot}s] is low relative to reactor facilities, more than 40 elements can be detected at low and sub-part-per-million levels. Detection limits provided by the facility are adequate for many analytical projects. Other multielement analysis methods, particularly inductively coupled plasma atomic emission and inductively coupled plasma mass spectrometry, can now provide sensitivities on dissolved samples that are often better than those available by NAA using low-flux isotopic sources. Because NAA allows analysis of bulk samples, (a) it is a more cost-effective choice when its sensitivity is adequate than methods that require digestion and (b) it eliminates uncertainties that can be introduced by digestion processes.

DiPrete, D.P.; Sigg, R.A.

2000-07-01

349

Time-of-flight diffraction at pulsed neutron sources: An introduction to the symposium  

SciTech Connect

In the 25 years since the first low-power demonstration experiments, pulsed neutron sources have become as productive as reactor sources for many types of diffraction experiments. The pulsed neutron sources presently operating in the United States, England, and Japan offer state of the art instruments for powder and single crystal diffraction, small angle scattering, and such specialized techniques as grazing-incidence neutron reflection, as well as quasielastic and inelastic scattering. In this symposium, speakers review the latest advances in diffraction instrumentation for pulsed neutron sources and give examples of some of the important science presently being done. In this introduction to the symposium, I briefly define the basic principles of pulsed neutron sources, review their development, comment in general terms on the development of time-of-flight diffraction instrumentation for these sources, and project how this field will develop in the next ten years.

Jorgensen, J.D.

1994-05-01

350

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

PubMed

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

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

2009-03-27

351

Assessment of the Pu content of Pu-Be neutron sources  

NASA Astrophysics Data System (ADS)

A nondestructive method for assaying sealed Pu-Be sources has been developed, using a combination of the ?-spectrometric determination of Pu isotopic abundances and neutron counting. A passive neutron coincidence collar was designed with nine 3He counters embedded in a polyethylene moderator surrounding the sources to be measured. The measurement cavity is lined with Cd to shield the source against slow neutrons diffusing backward from the moderator. The electronics consist of a nine-channel chain of pulse amplifiers and discriminators as well as a shift register. The neutron yield of the sources was determined by gross neutron counting, and the Pu content was assessed by adopting specific (?,n) reaction yields of individual Pu (and Am) isotopes from the literature. Coincidence counts were also recorded. The coincidences are mostly due to neutron-induced fission of the Pu isotopes, i.e. self-multiplication, and the 9Be(n,2n)8Be reaction.

Bagi, János; Cong Nguyen, Tam; Lakosi, László

2004-07-01

352

Determining 252Cf source strength by absolute passive neutron correlation counting  

NASA Astrophysics Data System (ADS)

Physically small, lightly encapsulated, radionuclide sources containing 252Cf are widely used for a vast variety of industrial, medical, educational and research applications requiring a convenient source of neutrons. For many quantitative applications, such as detector efficiency calibrations, the absolute strength of the neutron emission is needed. In this work we show how, by using a neutron multiplicity counter the neutron emission rate can be obtained with high accuracy. This provides an independent and alternative way to create reference sources in-house for laboratories such as ours engaged in international safeguards metrology. The method makes use of the unique and well known properties of the 252Cf spontaneous fission system and applies advanced neutron correlation counting methods. We lay out the foundation of the method and demonstrate it experimentally. We show that accuracy comparable to the best methods currently used by national bodies to certify neutron source strengths is possible.

Croft, S.; Henzlova, D.

2013-06-01

353

High-Power Linac for the Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

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 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

354

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

355

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

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

356

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

SciTech Connect

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

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

2006-03-15

357

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

SciTech Connect

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

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

2006-03-15

358

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

NASA Astrophysics Data System (ADS)

The ion source for the Spallation Neutron Source (SNS) is a radio-frequency (rf) multicusp source designed to deliver H- beam pulses of 40 mA to the SNS accelerator with a normalized root-mean-square emittance of less than 0.2? mm mrad, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high-pulse rf power, ~50 kW, and high average rf power, ~3.5 kW, over a continuous operational period of 3 weeks. During operation at these power levels the plasma-immersed, porcelain-coated rf antenna is susceptible to damage, limiting source lifetime. We are therefore developing an ion source where the plasma is separated from the Cu antenna by an Al2O3 discharge chamber. This article describes the ion source, presents initial beam extraction measurements, and details our ongoing effort to develop this concept into a suitable ion source for the SNS.

Welton, R. F.; Stockli, M. P.; Murray, S. N.; Kang, Y.; Peters, J.

2006-03-01

359

Evaluation of neutron sources for ISAGE—in-situ-NAA for a future lunar mission  

Microsoft Academic Search

For a future Moon landing, a concept for an in-situ NAA involving age determination using the 40Ar–39Ar method is developed. A neutron source 252Cf is chosen for sample irradiation on the Moon. A special sample-in-source irradiation geometry is designed to provide a homogeneous distribution of neutron flux at the irradiation position. Using reflector, the neutron flux is likely to increase

X. Li; H. Breitkreutz; J. Burfeindt; H.-G. Bernhardt; M. Trieloff; J. Hopp; E. K. Jessberger; W. H. Schwarz; P. Hofmann; H. Hiesinger

2011-01-01

360

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 1.6×10?26 to 2.4×10?25dpa per source neutron have been obtained, which translates into 16–250dpa\\/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

361

Gas dynamics studies of an Intense Neutron Source for fusion reactor materials testing  

Microsoft Academic Search

Theoretical and experimental studies have been performed on the supersonic gas target for the Intense Neutron Source (INS) project. The INS is a high-flux source of high-energy neutrons for fusion reactor materials damage studies. A 300-keV, 1-A tritium ion beam collides with a supersonic deuterium jet to produce neutrons. The gas target must convect away the beam heat and minimize

J. C. Hyde; M. C. Cline; G. Hefer

1978-01-01

362

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

Microsoft Academic Search

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

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

2004-01-01

363

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

364

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

365

Constraints on neutron star models of gamma-burst sources from the Einstein Observatory  

Microsoft Academic Search

Six Einstein observations of five gamma-ray burst sources are presented and discussed. With one possible exception, no point source was detected in any of the observations. The data are interpreted in the framework of neutron star models for gamma bursters. Upper limits are derived for the surface temperatures of the neutron stars assumed to be responsible for the bursts. It

G. Pizzichini; M. Gottardi; J.-L. Atteia; C. Barat; K. Hurley; M. Niel; G. Vedrenne; J. G. Laros; W. D. Evans; E. E. Fenimore; R. W. Klebesadel; T. L. Cline; U. D. Desai; V. G. Kurt; A. V. Kuznetsov; V. M. Zenchenko

1986-01-01

366

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

367

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

368

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

369

Phantom studies of Cd, Hg and Cl by prompt gamma neutron activation analysis using a 238Pu Be neutron source  

NASA Astrophysics Data System (ADS)

Prompt gamma neutron activation analysis is a means of non-invasive monitoring for occupational exposure to toxic heavy metals such as Cd and Hg. Preliminary kidney detection limits from previous phantom studies at McMaster were 13.6 ± 0.2 ppm for Cd (125 mL phantom) and 315 ± 24 ppm for Hg (125 mL phantom) using the 238Pu Be neutron source and 0.88 ± 0.01 ppm for Cd (125 mL phantom) and 16.91 ± 0.05 ppm for Hg (30 mL phantom) using the thermal neutron beam port at the McMaster Nuclear Reactor. The detection limits vary greatly between the two methods due to differences in experimental set-up, neutron energy spectra and a difference in dose by more than a factor of 100. The Hg detection limit from preliminary data is much higher than expected for both neutron source types. In order to explain the apparent detection limit discrepancy, measurements of Hg and Cd phantoms were performed using the 238Pu Be neutron source. The results were compared to phantom measurements of Cl, a well-known neutron activation element.

Grinyer, J.; Atanackovic, J.; Byun, S. H.; Chettle, D. R.

2007-10-01

370

Pulse width regulator for a pulsed neutron source  

Microsoft Academic Search

A pulsed neutron system for neutron--neutron logging is described including an accelerator tube having a target, an ionization section, and a replenisher for supplying accelerator gas. The power supplied to the replenisher is controlled to maintain the ionization pulse time duration within the upper and lower limits of a time window. A comparator compares the ionization pulse time duration to

1976-01-01

371

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

PubMed

Electromagnetic modeling of the multicusp external antenna H(-) ion source for the Spallation Neutron Source (SNS) has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as sigma. Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion. PMID:20192395

Lee, S W; Goulding, R H; Kang, Y W; Shin, K; Welton, R F

2010-02-01

372

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

NASA Astrophysics Data System (ADS)

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

Lee, S. W.; Goulding, R. H.; Kang, Y. W.; Shin, K.; Welton, R. F.

2010-02-01

373

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

SciTech Connect

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

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

2010-01-01

374

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

375

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

376

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

SciTech Connect

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

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

1992-01-01

377

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

SciTech Connect

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

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

1992-07-01

378

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

379

Mechanical design considerations of a spherical torus volumetric neutron source  

SciTech Connect

The mechanical design of a spherical torus based volumetric neutron source (ST VNS) is being studied under the support of a DOE-SBIR funding. A device capable of staged operation from a neutron wall loading of 0.5-5.0 MW/m(2) has been scoped out, as the physics and engineering design assumptions are raised from modest to aggressive levels. Margins in the design are ensured since operation of the VNS will be adequate st a wall loading of 2 MW/m(2). The device has a naturally diverted plasma with major radius of 1.07 m, a minor radius of 0.77 m for an aspect ratio of 1.4, an elongation of 3 and triangularity of 0,6. In the neutral beam driven version, the plasma current is 11.1 MA and the toroidal field at the plasma major radius is 2.13 T, The baseline fusion power is 151 MW giving an average neutron wall loading of 2 MV/m(2) on the outboard side over an accessible area of over 15 m(2) for blanket testing. The device utilizes a normal Cu conducting bell jar as the return leg of the toroidal field current, a concept developed at the Oak Ridge National Laboratory. The current is carried by an unshielded single-turn center post (CP) made of dispersion strengthened Cu which is cooled by water in a single pass from top to bottom. A special sliding electrical interface between the CP and the bell jar is provided on the upper end to allow for differential expansion and to isolate the CP from tensile and torsional forces from the bell jar. The ohmic heating in the CP is 153 MW at the start of operation and increases to 178 MW after 3 full power years of operation. Over this period the maximum Cu temperature does not exceed 160 C. This report primarily deals with the design of the CP, one of the most challenging Issues of a low aspect ratio spherical torus. Maintenance approaches for the Or and the divertor assemblies have been determined and are addressed in the paper.

Sviatoslavky, I. N. [University of Wisconsin, Madison; Peng, Yueng Kay Martin [ORNL

1998-01-01

380

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

381

Parity Violation, Time Reversal, and the Neutron: Nuclear and Particle Physics at the Spallation Neutron Source (SNS)  

ScienceCinema

For more than half a century, low energy neutrons have been used to elucidate important issues related to the understanding of fundamental symmetries, the determination of fundamental constants, and the testing of basic theories in nuclear and particle physics. Currently investigations with 'Cold' and 'Ultra Cold' neutrons are addressing questions related to the origin of time reversal asymmetry, the unitarity of the CKM matrix, and the nature of the hadronic weak interaction. Current and proposed measurements of the neutron electric dipole moment, neutron beta decay and nucleon-nucleon parity violation will be reviewed. The opportunities for this work at the accelerator based Spallation Neutron Source, currently under construction at Oak Ridge National Laboratory, will be discussed.

382

A Long-Pulse Spallation Source at Los Alamos: Facility description and preliminary neutronic performance for cold neutrons  

SciTech Connect

The Los Alamos National Laboratory has discussed installing a new 1-MW spallation neutron target station in an existing building at the end of its 800-MeV proton linear accelerator. Because the accelerator provides pulses of protons each about 1 msec in duration, the new source would be a Long Pulse Spallation Source (LPSS). The facility would employ vertical extraction of moderators and reflectors, and horizontal extraction of the spallation target. An LPSS uses coupled moderators rather than decoupled ones. There are potential gains of about a factor of 6 to 7 in the time-averaged neutron brightness for cold-neutron production from a coupled liquid H{sub 2} moderator compared to a decoupled one. However, these gains come at the expense of putting ``tails`` on the neutron pulses. The particulars of the neutron pulses from a moderator (e.g., energy-dependent rise times, peak intensities, pulse widths, and decay constant(s) of the tails) are crucial parameters for designing instruments and estimating their performance at an LPSS. Tungsten is the reference target material. Inconel 718 is the reference target canister and proton beam window material, with Al-6061 being the choice for the liquid H{sub 2} moderator canister and vacuum container. A 1-MW LPSS would have world-class neutronic performance. The authors describe the proposed Los Alamos LPSS facility, and show that, for cold neutrons, the calculated time-averaged neutronic performance of a liquid H{sub 2} moderator at the 1-MW LPSS is equivalent to about 1/4th the calculated neutronic performance of the best liquid D{sub 2} moderator at the Institute Laue-Langevin reactor. They show that the time-averaged moderator neutronic brightness increases as the size of the moderator gets smaller.

Russell, G.J.; Weinacht, D.J.; Pitcher, E.J.; Ferguson, P.D.

1998-03-01

383

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

384

The Swiss spallation neutron source SINQ—developments and upgrades for optimized user service  

NASA Astrophysics Data System (ADS)

The Swiss spallation neutron source SINQ at the Paul Scherrer Institute (PSI) is a popular user facility for neutron scattering and neutron imaging serving user groups from a widespread international community, see also http://sinq.web.psi.ch/. Beyond reliable routine operation, PSI seeks to play a leading role in the development of facilities, instrumentation, sample environment, and user programs. On the side of neutron instrumentation, three instruments are currently being built up in the SINQ hall: a cold neutron radiography station (ICON), a thermal triple-axis spectrometer (EIGER) and a backscattering spectrometer (MARS).

Wagner, W.; Mesot, J.; Allenspach, P.; Kuehne, G.; Rønnow, H. M.

2006-11-01

385

Improvement in the practical implementation of neutron source strength calibration using prompt gamma rays.  

PubMed

In this study, the neutron emission rate from neutron sources using prompt gamma rays in hydrogen was determined, and several improvements were applied. Using Monte Carlo calculations, the best positions for the source, moderator and detector relative to each other were selected. For (241)Am-Be and (252)Cf sources, the sizes for polyethylene spheres with the highest efficiency were 12- and 10-inch, respectively. In addition, a new shielding cone was designed to account for scattered neutrons and gamma rays. The newly designed shielding cone, which is 45 cm in length, provided suitable attenuation for the source radiation. PMID:23672963

Khabaz, Rahim; Rene Vega-Carrillo, Hector

2013-03-31

386

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

Microsoft Academic Search

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

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

2011-01-01

387

Novel neutron sources at the Radiological Research Accelerator Facility  

PubMed Central

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

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

2012-01-01

388

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

389

Spin-Echo Resolved Grazing Incidence Scattering (SERGIS) at Pulsed and CW Neutron Sources  

NASA Astrophysics Data System (ADS)

We have used SERGIS to probe the surface structure of a silicon diffraction grating of period 140 nm. Experiments were performed at: the Los Alamos Neutron Science Center (LANSCE) pulsed neutron source and the National Institute of Standards and Technology (NIST) continuous wave (CW) reactor neutron source. Although both sets of data show peaks of the spin echo polarization at integer multiples of the grating period, as expected, the results differ in detail. We have developed a dynamical theory, based on a Bloch wave expansion, to describe neutron diffraction from a grating. The theory explains the differences between the two sets of data without any adjustable parameters.

Ashkar, Rana; Stonaha, P.; Washington, A.; Shah, V. R.; Fitzsimmons, M. R.; Maranville, B.; Majkrzak, C. F.; Lee, W. T.; Pynn, Roger

2010-11-01

390

Investigation of the neutron energy distribution of the IRSN 241Am-Be(alpha,n) source.  

PubMed

The neutron energy distribution of the IRSN standard 241Am-Be(alpha,n) source was measured using a proton recoil liquid scintillator, BC501A, >1.65 MeV. The experimental data were compared with the ISO recommended neutron energy distribution for an Am-Be source and some significant discrepancies were observed. Monte Carlo simulations were then performed to investigate on the neutron source term in order to consider the different parameters between the IRSN Am-Be source and the one used to establish the neutron emission spectrum recommended by the ISO standard. The variation of the parameters of the source did not explain the remaining discrepancies. A good agreement with the experimental results was observed when the theoretical neutron energy distribution from Geiger and Van der Zwan was introduced in the study as new source term. These investigations showed that the ISO recommended Am-Be distribution might not be well suited to represent the neutron energy distribution of all Am-Be sources, and that the manufacturing of the sources might play a major role in the neutron fluence energy distribution. PMID:17276999

Magalotti, N; Lacoste, V; Lebreton, L; Gressier, V

2007-02-02

391

A parameter study to determine the optimal source neutron energy in boron neutron capture therapy of brain tumours  

NASA Astrophysics Data System (ADS)

The values of the parameters used in boron neutron capture therapy (BNCT) to calculate a given dose to human tissue vary with patients due to different physical, biological and/or medical circumstances. Parameters include the tissue dimensions, the 10B concentration and the relative biological effectiveness (RBE) factors for the different dose components associated with BNCT. Because there is still no worldwide agreement on RBE values, more often than not, average values for these parameters are used. It turns out that the RBE-problem can be circumvented by taking into account all imaginable parameter values. Approaching this quest from another angle: the outcome will also provide the parameters (and values) which influence the optimal source neutron energy. For brain tumours it turns out that the 10B concentration, the RBE factors for 10B as well as fast neutrons, together with the dose limit set for healthy tissue, affect the optimal BNCT source neutron energy. By using source neutrons of a few keV together with neutrons of a few eV, it ensures that, under all imaginable circumstances, a maximum of alpha (and lithium) particles can be delivered in the tumour.

Nievaart, V. A.; Moss, R. L.; Kloosterman, J. L.; van der Hagen, T. H. J. J.; van Dam, H.

2004-09-01

392

Three new nondestructive evaluation tools based on high flux neutron sources  

SciTech Connect

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

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

1997-03-01

393

Effects of neutron source selection on land-mine detection efficiency  

NASA Astrophysics Data System (ADS)

One proposed method of land-mine detection is based on measurements of the 10.8MeV photons from the 14N(n,/?) reaction. In this study, simulations of the photon production efficiencies for nitrogenous explosive material (TNT), buried in soil having variable moisture content, were completed for different published neutron spectra. Monte Carlo simulations were performed with MCNP with a cylindrical geometry of TNT considered as target material and with neutron energies ranging from thermal to 20MeV. The numbers of 14N(n, /?) reactions in TNT were tallied to obtain response functions. To find the effectiveness of different neutron sources, response functions were folded with the neutron spectra. Response curves reveal that higher water content increases response for fast neutrons, and reduces response for slow neutrons. Lower energy neutron sources, i.e. D(d,n) or 252Cf, are more suitable than higher energy neutron sources such as 241Am-Be or T(d, n). Although its advantages disappear with increasing depth, the usage of moderating spheres of CH2 increases the signal significantly when compared with a bare source, while also reducing neutron dose to workers.

Hsu, H.-H.; Kearfott, K. J.

1999-02-01

394

ASPUN: design for an Argonne super-intense pulsed neutron source  

Microsoft Academic Search

Argonne pioneered the pulsed spallation neutron source with the ZING-P and IPNS-I concepts. IPNS-I is now a reliable and actively used source for pulsed spallation neutrons. The accelerator is a 500-MeV, 8 to 9 ..mu..a, 30-Hz rapid-cycling proton synchrotron. Other proton spallation sources are now in operation or in construction. These include KENS-I at the National Laboratory for High Energy

T. K. Khoe; R. L. Kustom

1983-01-01

395

Beam dynamics simulation of the Spallation Neutron Source linear accelerator  

SciTech Connect

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{sup {minus}} pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from 402.5 MHz DTL with a 4 {beta}{lambda} structure to a CCDTL operated at 805 MHz with a 12 {beta}{lambda} structure. After a discussion of overall feature of the linac, they present an end-to-end particle simulation using the new version of the PARMILA code for a beam starting from the RFQ entrance through the rest of the linac. At 1000 MeV, the beam is transported to a storage ring. The storage ring requires a large ({+-}500-keV) energy spread. This is accomplished by operating the rf-phase in the last section of the linac so the particles are at the unstable fixed point of the separatrix. They present zero-current phase advance, beam size, and beam emittance along the entire linac.

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

1998-12-31

396

Advanced neutron source reactor probabilistic flow blockage assessment  

SciTech Connect

The Phase I Level I Probabilistic Risk Assessment (PRA) of the conceptual design of the Advanced Neutron Source (ANS) Reactor identified core flow blockage as the most likely internal event leading to fuel damage. The flow blockage event frequency used in the original ANS PRA was based primarily on the flow blockage work done for the High Flux Isotope Reactor (HFIR) PRA. This report examines potential flow blockage scenarios and calculates an estimate of the likelihood of debris-induced fuel damage. The bulk of the report is based specifically on the conceptual design of ANS with a 93%-enriched, two-element core; insights to the impact of the proposed three-element core are examined in Sect. 5. In addition to providing a probability (uncertainty) distribution for the likelihood of core flow blockage, this ongoing effort will serve to indicate potential areas of concern to be focused on in the preliminary design for elimination or mitigation. It will also serve as a loose-parts management tool.

Ramsey, C.T.

1995-08-01

397

Advanced Neutron Source design: Burnout heat flux correlation development  

SciTech Connect

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

Gambill, W.R.; Mochizuki, T.

1988-01-01

398

Advanced Neutron Source Reactor zoning, shielding, and radiological optimization guide  

SciTech Connect

In the design of major nuclear facilities, it is important to protect both humans and equipment excessive radiation dose. Past experience has shown that it is very effective to apply dose reduction principles early in the design of a nuclear facility both to specific design features and to the manner of operation of the facility, where they can aid in making the facility more efficient and cost-effective. Since the appropriate choice of radiological controls and practices varies according to the case, each area of the facility must be analyzed for its radiological impact, both by itself and in interactions with other areas. For the Advanced Neutron Source (ANS) project, a large relational database will be used to collect facility information by system and relate it to areas. The database will also hold the facility dose and shielding information as it is produced during the design process. This report details how the ANS zoning scheme was established and how the calculation of doses and shielding are to be done.

Westbrook, J.L.; DeVore, J.R.

1995-08-01

399

Fuel qualification plan for the Advanced Neutron Source Reactor  

SciTech Connect

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

Copeland, G.L.

1995-07-01

400

A High Intensity Linac for the National Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

The National Spallation Neutron Source to be constructed at Oak Ridge National Laboratory, requires a linac capable of delivering up to 5 MW of beam power to an accumulator ring with a nominal 6.2% duty factor and an energy of 1 GeV. Los Alamos, responsible for the linac design, has developed an appropriate room-temperature linac that consists of a drift-tube section from 2.5 to 20 MeV, a coupled-cavity drift-tube section to 100 MeV, and a coupled-cavity section to 1 GeV. The initial scenario requires an average 1.1-mA beam current with a corresponding 28 mA peak current and a 1.2-Mhz chopped time structure corresponding to the ring period. Upgrade to a 4.4 mA average current requires funneling with a peak current of 112 mA in the high-energy sections. Further parameters are presented along with beam dynamics and structure choices and mechanical and rf engineering considerations.

Jason, A.; Bhatia, T.; Billen, J.; Schrage, D.; Kurennoy, S.; Krawczyk, F.; Lynch, M.; Nath, S.; Shafer, R.; Takeda, H.; Tallerico, P.; Wangler, T.; Wood, R.; Young, L.; Grand, P.; McKenzie-Wilson, R.

1997-05-01

401

Neutron spectra from monoenergetic source neutrons after multiple reflection between plane-parallel concrete interfaces  

Microsoft Academic Search

Monte Carlo calculations have been performed for neutrons reflecting between two Type 04 concrete plane-parallel interfaces. A new 23-group albedo data base (SAIL) was used in conjunction with the MORSE code to calculate the neutron spectrum at each reflection. It was found that, after thermalization, for the same order of reflection, the number of neutrons in the cavity is dependent

W. K. Hagan; G. L. Simmons

1980-01-01

402

Uranium Assay Logging Using a Pulsed 14MEV Neutron Source and Detection of Delayed Fission Neutrons  

Microsoft Academic Search

An in-situ uranium assay logging system has been developed that measures directly and quantitatively the uranium concentration in the formation surrounding a drill hole. System operation is based on the DFN (delayed fission neutron) method which involves (1) bombarding a formation with short duration bursts of neutrons from a pulsed-neutron generator to induce fission in any uranium present; (2) separating

W. W. Givens; W. R. Mills; C. L. Dennis; R. L. Caldwell

1976-01-01

403

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

SciTech Connect

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

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

2010-02-15

404

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

SciTech Connect

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

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

2007-02-15

405

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

SciTech Connect

The International Workshop on Cold Moderators for Pulsed Neutron Sources resulted from the coincidence of two forces. Our sponsors in the Materials Sciences Branch of DOE's Office of Energy Research and the community of moderator and neutron facility developers both realized that it was time. The Neutron Sources Working Group of the Megascience Forum of the Organization for Economic Cooperation and Development offered to contribute its support by publishing the proceedings, which with DOE and Argonne sponsorship cemented the initiative. The purposes of the workshop were: to recall and improve the theoretical groundwork of time-dependent neutron thermalization; to pose and examine the needs for and benefits of cold moderators for neutron scattering and other applications of pulsed neutron sources; to summarize experience with pulsed source, cold moderators, their performance, effectiveness, successes, problems and solutions, and the needs for operational data; to compile and evaluate new ideas for cold moderator materials and geometries; to review methods of measuring and characterizing pulsed source cold moderator performance; to appraise methods of calculating needed source characteristics and to evaluate the needs and prospects for improvements; to assess the state of knowledge of data needed for calculating the neutronic and engineering performance of cold moderators; and to outline the needs for facilities for testing various aspects of pulsed source cold moderator performance.

Carpenter, J. M.

1999-01-06

406

Design of the Small Angle Neutron Scattering instrument at the Indiana University Low Energy Neutron Source: Applications to the study of nanostructured materials  

Microsoft Academic Search

The Low Energy Neutron Source (LENS) located at the Indiana University Cyclotron Facility (IUCF) is a prototypical long-pulse accelerator-based neutron source. The Small Angle Neutron Scattering (SANS) instrument is one of several planned instruments at the LENS facility. The SANS instrument is a time-of-flight instrument which utilizes a pinhole collimation system and neutron wavelengths up to 20A giving it a

Nicholas B. Remmes

2007-01-01

407

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

NASA Astrophysics Data System (ADS)

Plasma focus device of Mather type developed in house has been used first time for neutron radiography of different objects. The device gives (1.2+/-0.3) ×109 neutrons per pulse produced by D-D fusion reaction with a pulse width of 50+/-5 ns. The method involves exposing sample to be radiographed to thermalized D-D neutrons and recording the image on Fuji-film BAS-ND image plates. The thermal neutron component of the moderated beam was estimated using two image plates: a conventional IP for X-rays and gamma rays, and an IP doped with Gd for detecting neutrons.

Andola, Sanjay; Niranjan, Ram; Shaikh, A. M.; Rout, R. K.; Kaushik, T. C.; Gupta, S. C.

2013-02-01

408

Determining Pu isotopic composition and Pu content of PuBe sources by neutron coincidence technique  

Microsoft Academic Search

The paper describes a pure neutron method for determining both Pu content and Pu isotopic composition of PuBe neutron sources by neutron coincidence technique, without using gamma-spectrometry. The new procedure based on the R\\/T–T relationship is a developed version of the R\\/T-method based on R\\/T–MPu calibration curve described in [C.T. Nguyen, J. Bagi, L. Lakosi, A novel method of quantitative

Cong Tam Nguyen; Janos Bagi; Laszlo Lakosi

2007-01-01

409

MEASUREMENT OF THE NEUTRON SPECTRUM OF A Pu-Be SOURCE  

Microsoft Academic Search

The neutron spectrum of a Pu--Be source containing 9.99 g Pu was ; determined using the time-of-flight method. The experimental apparatus is shown. ; The neutrons were measured in a cylindrical scintillator. The time-of-flight ; spectrum of neutrons scattered at the first scintillator was measured with a time ; analyzer. The energy spectrum calculated from the results are given, and

Z. Lewandowski; P. Huber; R. Wagner

1961-01-01

410

Powder diffraction in materials science using the KENS cold-neutron source  

SciTech Connect

Since superconductivity fever spread around the world, neutron powder diffraction has become very popular and been widely used by crystallographers, physicists, chemists, mineralogists, and materials scientists. The purpose of present paper is to show, firstly, important characteristics of time-of-flight TOF powder diffraction using cold-neutron source in the study of materials science, and, secondly, recent studies on the structure and function of batteries at the Neutron Science Laboratory (KENS) in the High Energy Accelerator Research Organization (KEK).

Kamiyama, T.; Oikawa, K. [Univ. of Tsukuba (Japan). Inst. of Materials Science; Akiba, E. [National Inst. of Materials and Chemical Research, Tsukuba (Japan)] [and others

1997-12-01

411

A fast miniature plasma focus based compact and portable nanosecond pulsed neutron source  

Microsoft Academic Search

A low energy fast miniature plasma focus device 'FMPF-1' has recently been developed to be used as compact and portable nanosecond pulsed neutron source for field applications. The system operates in deuterium producing maximum neutron yield in the order of 10 6 neutrons\\/ pulse in 4? sr. at ~80kA peak discharge current. In the range of 4 to 7mbar distinct

Rishi Verma; R. S. Rawat; P. Lee; S. V. Springham; T. L. Tan; M. V. Roshan

2009-01-01

412

Thermosiphon mock-up test for the cold neutron source of HANARO  

Microsoft Academic Search

Due to the national demand for a cold neutron beam utilization, a cold neutron research facility project has been carried out since July 2003 to install a cold neutron source (CNS) in HANARO. The CNS adopts a two-phase thermo-siphon of liquid hydrogen as a working fluid to remove a heat load. The CNS consists of an in-pool assembly (IPA) and

Jungwoon Choi; Myong-seop Kim; Bong Soo Kim; Kye Hong Lee; Hark Rho Kim

2010-01-01

413

The Swiss spallation neutron source SINQ—developments and upgrades for optimized user service  

Microsoft Academic Search

The Swiss spallation neutron source SINQ at the Paul Scherrer Institute (PSI) is a popular user facility for neutron scattering and neutron imaging serving user groups from a widespread international community, see also http:\\/\\/sinq.web.psi.ch\\/. Beyond reliable routine operation, PSI seeks to play a leading role in the development of facilities, instrumentation, sample environment, and user programs. On the side of

W. Wagner; J. Mesot; P. Allenspach; G. Kuehne; H. M. Rønnow

2006-01-01

414

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device  

Microsoft Academic Search

The development of a novel and portable tabletop pulsed neutron source is presented. It is a battery powered neutron tube based on a miniature plasma focus (PF) device having all metal-sealed components. The tube, fuelled with deuterium gas, generates neutrons because of D–D fusion reactions. The inner diameter and the length of the tube are 3.4 cm and 8 cm,

R K Rout; P Mishra; A M Rawool; L V Kulkarni; Satish C Gupta

2008-01-01

415

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device  

Microsoft Academic Search

The development of a novel and portable tabletop pulsed neutron source is presented. It is a battery powered neutron tube based on a miniature plasma focus (PF) device having all metal-sealed components. The tube, fuelled with deuterium gas, generates neutrons because of D-D fusion reactions. The inner diameter and the length of the tube are 3.4 cm and 8 cm,

R. K. Rout; P. Mishra; A. M. Rawool; L. V. Kulkarni; Satish C. Gupta

2008-01-01

416

Californium-252: neutron source for industry and medicine  

SciTech Connect

From eleventh conference on radioisotopes; Tokyo, Japan (13 Nov 1973). The history, production, and availability of /sup 252/Cf and its many potential uses are discussed. Applications in life sciences, education chemical analysis, exploration for natural resources, industrial process control, neutron radiography, nondestructive inspection, and neutron flux enhancement are described. (TFD)

Reinig, W.C.; Permar, P.H.; Cornman, W.R.

1973-01-01

417

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

SciTech Connect

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

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

2012-02-15

418

Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices  

SciTech Connect

LaBr3:Ce scintillators offer significantly better resolution (< 3% at 662 keV) relative to NaI(Tl) and have recently become commercially available in sizes large enough for the handheld, Radio-Isotope Identification Device (RIID) market. Drawbacks to lanthanum halide detectors, however, include internal radioactivity contributing to spectral counts, and a low-energy response which can cause detector resolution to be worse than that of NaI(Tl) below 100 keV. To study the potential of this new material for RIIDs we performed a series of measurements comparing a 1.5² ´ 1.5² LaBr¬3:Ce detector with an Exploranium GR-135 RIID, which contains a 1.5² ´ 2.2² NaI(Tl) detector. Measurements were taken for short timeframes, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. Some measurements were non-contact, involving short distances or cargo shielding scenarios. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope-identification software (ORTEC ScintiVision).

Milbrath, Brian D.; Choate, Bethany J.; Fast, Jim E.; Kouzes, Richard T.; Schweppe, John E.

2005-10-23

419

Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices  

SciTech Connect

Lanthanum bromide (LaBr3:Ce) scintillators offer significantly better resolution [<3 percent at 662 kilo-electron volt (keV)] relative to sodium iodide [NaI(Tl)] but contain internal radioactivity that contributes to spectral counts. LaBr3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5 ´ 1.5 inch LaBr¬3:Ce detector with an Exploranium GR 135 RIID, which contains a 1.5 ´ 2.2 inch NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision?). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal activity due to 138La in the LaBr3:Ce detector exists and NaI(Tl) consistently outperformed LaBr3:Ce.

Milbrath, Brian D.; Choate, Bethany J.; Fast, Jim E.; Hensley, Walter K.; Kouzes, Richard T.; Schweppe, John E.

2007-03-11

420

Comparison of LaBr3:Ce and NAI(Tl) scintillators for radio-isotope identification devices  

NASA Astrophysics Data System (ADS)

Lanthanum bromide (LaBr3:Ce) scintillators offer significantly better resolution (<3 percent at 662 keV) relative to sodium iodide (NaI(Tl)) but contain internal radioactivity that contributes to spectral counts. LaBr3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5×1.5-in. LaBr3:Ce detector with an Exploranium GR-135 RIID, which contains a 1.5×2.2-in. NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision™). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K-containing NORM where interfering internal activity due to 138La in the LaBr3:Ce detector exists and NaI(Tl) consistently outperformed LaBr3:Ce.

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

2007-03-01

421

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

SciTech Connect

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

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

2012-12-15

422

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

NASA Astrophysics Data System (ADS)

A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 × 105 n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He4 nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T3.

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

2012-12-01

423

Design and simulation of neutron radiography system based on 241Am-Be source  

NASA Astrophysics Data System (ADS)

Neutron imaging is extended rapidly as a means of non-destructive testing (NDT) of materials. Various effective parameters on the image quality are needed to be studied for neutron radiography system with good resolution. In the present study a portable system of neutron radiography has been designed using 241Am-Be neutron source. The effective collimator parameters were calculated to obtain relatively pure, collimated and uniform neutron beam. All simulations were carried out in two stages using MCNPX Monte Carlo code. In the first stage, different collimator configurations were investigated and the appropriate design was selected based on maximum intensity and uniformity of neutron flux at the image plane in the outlet of collimator. Then, the overall system including source, collimator and sample was simulated for achieving radiographic images of standard samples. Normalized thermal neutron fluence of 2.61×10-5 cm-2 per source particle with n/? ratio of 1.92×105 cm-2 ?Sv-1 could be obtained at beam port of the designed collimator. Quality of images was assessed for two standard samples, using radiographic imaging capability in MCNPX. The collimated neutron beam in the designed system could be useful in a transportable exposure module for neutron radiography application.

Jafari, H.; Feghhi, S. A. H.

2012-05-01

424

An ultracold neutron source at the NC State University PULSTAR reactor  

NASA Astrophysics Data System (ADS)

Research and development is being completed for an ultracold neutron (UCN) source to be installed at the PULSTAR reactor on the campus of North Carolina State University (NCSU). The objective is to establish a university-based UCN facility with sufficient UCN intensity to allow world-class fundamental and applied research with UCN. To maximize the UCN yield, a solid ortho-D2 converter will be implemented coupled to two moderators, D2O at room temperature, to thermalize reactor neutrons, and solid CH4, to moderate the thermal neutrons to cold-neutron energies. The source assembly will be located in a tank of D2O in the space previously occupied by the thermal column of the PULSTAR reactor. Neutrons leaving a bare face of the reactor core enter the D2O tank through a 45×45 cm cross-sectional area void between the reactor core and the D2O tank. Liquid He will cool the disk-shaped UCN converter to below 5 K. Independently, He gas will cool the cup-shaped CH4 cold-neutron moderator to an optimum temperature between 20 and 40 K. The UCN will be transported from the converter to experiments by a guide with an inside diameter of 16 cm. Research areas being considered for the PULSTAR UCN source include time-reversal violation in neutron beta decay, neutron lifetime determination, support measurements for a neutron electric-dipole-moment search, and nanoscience applications.

Korobkina, E.; Wehring, B. W.; Hawari, A. I.; Young, A. R.; Huffman, P. R.; Golub, R.; Xu, Y.; Palmquist, G.

2007-08-01

425

High-Resolution Measurements of Neutron Energy Spectra from Americium-Beryllium and Americium-Boron Neutron Sources  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. A Helium-3 sandwich spectrometer incorporating two semiconductor detectors was designed and constructed to enable the measurement of high resolution neutron energy spectra in the energy range from 100 keV to 15 MeV. The instrument is novel in respect of the inclusion of an anode wire which enables the gas chamber to function as a gas proportional counter. Few similar instruments have been constructed and no similar instrument is known to be currently (1990) in use in the UK. The efficiency of the spectrometer was determined experimentally, using a Californium-252 spontaneous fission source, in the low-scatter facility of the National physical Laboratory. A Monte Carlo code has been written to determine the absolute efficiency over an energy range from 81 keV to 20 MeV. The calculated values were used to extrapolate the measured efficiency to higher energies. Furthermore the Monte Carlo code was used to determine certain operating parameters to optimise the efficiency of the spectrometer. The neutron energy spectra from two different size standard Am-Be neutron sources and a standard Am-B neutron source available at NPL were measured. Although these types of neutron sources have been subject to energy spectra measurements elsewhere, the present work improves considerably on the previous poorer energy resolution and energy range. The new data indicates for the three neutron sources studied that the ambient dose equivalent, H*(10) per unit fluence, for each, were identical, being within 2% of 3.70 E-10 Sv cm^2.

Marsh, James W.

426

Scalar Radiation Field of a Neutron-Source in Liquid Nitrogen.  

National Technical Information Service (NTIS)

A set of measured values was established for testing computational methods and computer programs for the calculation of the radiation transport from nuclear weapons. The scalar neutron and gamma radiation field from a 14 MeV neutron source in liquid nitro...

B. Broecker K. Clausen P. Johnsen P. Schneider-kuehnle M. Weinert

1974-01-01

427

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

Federal Register 2010, 2011, 2012, 2013

...licensees include Am-241/Be, Pu/Be, and californium-252 (Cf-252). A licensee's decision to use a specific type of...sources produce neutrons during spontaneous fission. The Cf-252 splits apart producing a number of neutrons in the...

2013-04-11

428

Force analysis of the Advanced Neutron Source control rod drive latch mechanism  

Microsoft Academic Search

The Advanced Neutron Source reactor (ANS), a proposed Department of Energy research reactor currently undergoing conceptual design, will generate a thermal neutron flux approximating 1020 m-2 -s-1. The compact core necessary to produce this flux provides little space for the shim\\/safety control rods, which are located in the central annulus of the core. Without proper control rod drive design, the

B. Damiano

1990-01-01

429

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

PubMed

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

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

2013-06-01

430

Argonne Intense Pulsed Neutron Source Used to Solve the Molecular Structure of a Novel Organometallic Complex  

Microsoft Academic Search

The single-crystal structure of Mn(CO)3(C7H11) is the first to be solved by direct methods based on time-of-flight neutron diffraction data obtained at the Argonne Intense Pulsed Neutron Source. The molecule contains an unusual three-center, two-electron manganese-hydrogen-carbon interaction.

Arthur J. Schultz; Raymond G. Teller; Mark A. Beno; Jack M. Williams; M. Brookhart; W. Lamanna; M. Beth Humphrey

1983-01-01

431

Oak Ridge Reservation site evaluation report for the Advanced Neutron Source  

Microsoft Academic Search

The Advanced Neutron Source (ANS) is a research reactor that is the US Department of Energy (DOE) plans to build for initial service late in this century. The primary purpose of the ANS is to provide a useable neutron flux for scattering experiments 5 to 10 times as a high as that generated by any existing research reactor, secondary purposes

B. Sigmon; A. C. Jr. Heitzman; J. Morrissey

1990-01-01

432

Intense Pulsed Neutron Source progress report for 1991  

SciTech Connect

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

Not Available

1991-12-31

433

Intense Pulsed Neutron Source progress report for 1991  

SciTech Connect

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

Not Available

1991-01-01

434

Non-Uniform Contrast and Noise Correction for Coded Source Neutron Imaging  

SciTech Connect

Since the first application of neutron radiography in the 1930s, the field of neutron radiography has matured enough to develop several applications. However, advances in the technology are far from concluded. In general, the resolution of scintillator-based detection systems is limited to the $10\\mu m$ range, and the relatively low neutron count rate of neutron sources compared to other illumination sources restricts time resolved measurement. One path toward improved resolution is the use of magnification; however, to date neutron optics are inefficient, expensive, and difficult to develop. There is a clear demand for cost-effective scintillator-based neutron imaging systems that achieve resolutions of $1 \\mu m$ or less. Such imaging system would dramatically extend the application of neutron imaging. For such purposes a coded source imaging system is under development. The current challenge is to reduce artifacts in the reconstructed coded source images. Artifacts are generated by non-uniform illumination of the source, gamma rays, dark current at the imaging sensor, and system noise from the reconstruction kernel. In this paper, we describe how to pre-process the coded signal to reduce noise and non-uniform illumination, and how to reconstruct the coded signal with three reconstruction methods correlation, maximum likelihood estimation, and algebraic reconstruction technique. We illustrates our results with experimental examples.

Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL

2012-01-01

435

Non-uniform contrast and noise correction for coded source neutron imaging  

NASA Astrophysics Data System (ADS)

Since the first application of neutron radiography in the 1930s, the field of neutron radiography has matured enough to develop several applications. However, advances in the technology are far from concluded. In general, the resolution of scintillator-based detection systems is limited to the 10?m range, and the relatively low neutron count rate of neutron sources compared to other illumination sources restricts time resolved measurement. One path toward improved resolution is the use of magnification; however, to date neutron optics are inefficient, expensive, and difficult to develop. There is a clear demand for cost-effective scintillator-based neutron imaging systems that achieve resolutions of 1?m or less. Such imaging system would dramatically extend the application of neutron imaging. For such purposes a coded source imaging system is under development. The current challenge is to reduce artifacts in the reconstructed coded source images. Artifacts are generated by non-uniform illumination of the source, gamma rays, dark current at the imaging sensor, and system noise from the reconstruction kernel. In this paper, we describe how to pre-process the coded signal to reduce noise and non-uniform illumination, and how to reconstruct the coded signal with three reconstruction methods correlation, maximum likelihood estimation, and algebraic reconstruction technique. We illustrates our results with experimental examples.

Santos-Villalobos, Hector J.; Bingham, Philip R.

2012-02-01

436

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

NASA Astrophysics Data System (ADS)

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 loss in spatial resolution and provides high signal-to-noise ratio (SNR) images. Here we report a preliminary study on the feasibility of coded-source-based technique applied to the cold neutron imaging with a low-brilliance neutron source at the CPHS. A proper coded aperture is designed to be used in the beamline instead of the single-hole aperture. Two image retrieval algorithms, the Wiener filter algorithm and the Richardson-Lucy algorithm, are evaluated by using analytical and Monte Carlo simulations. The simulation results reveal that the coded source imaging technique is suitable for the CPHS to partially solve the problem of low neutron flux.

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

2011-09-01

437

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

NASA Astrophysics Data System (ADS)

The EURISOL project, a multi-lateral initiative supported by the EU, aims to develop a facility to achieve high yields of isotopes in radioactive beams and extend the variety of these isotopes towards more exotic types. The neutron source at the heart of the projected facility is designed to generate isotopes by fissioning uranium carbide (UC) targets arranged around a 4 MW neutron source. For reasons of efficiency, it is essential that the neutron source be as compact as possible, to avoid losing neutrons by absorption whilst maximising the escaping neutron flux, thus increasing the number of fissions in the UC targets. The resulting configuration presents a challenge in terms of absorbing heat deposition rates of up to 8 kW/cm3 in the neutron source; it has led to the selection of liquid metal for the target material. The current paper presents the design of a compact high-power liquid-metal neutron