Science.gov

Sample records for neutron induced radiography

  1. Regulatory aspects of neutron radiography

    NASA Astrophysics Data System (ADS)

    Hammer, J.

    1999-11-01

    While full legislation for industrial radiography with gamma and X-rays already exists in many countries, the situation is different for neutron radiography. Therefore, the licensing for equipment and procedures in this field has to be based on basic principles of national and international rules. This contribution will explain how the regulatory body in Switzerland deals with neutron radiography installations in order to maintain national standards of health and safety.

  2. Progress in thermal neutron radiography at LENS

    NASA Astrophysics Data System (ADS)

    Jenkins, Jack; Low Energy Neutron Source (LENS) at Indiana University Collaboration

    2014-09-01

    An end station for thermal neutron radiography and tomography is in operation at the Indiana University LENS facility. Neutrons from proton-induced nuclear reactions in Beryllium are moderated and collimated into a beam which is attenuated by a scanned object on a remotely-controlled rotating table. Neutron signal is then converted to a light signal with a ZnS scintillating screen and recorded in a cooled CCD. The author has performed diagnostics on the radiography hardware and software and has tested the system's capabilities by imaging a stack of high density polyethylene cubes with diverse inlet holes and grooves on an 80/20 aluminum base. The resolution of the radiographs are seen to be less than 1mm and 3D rending software is capable of reconstructing the internal structure of the aluminum. An end station for thermal neutron radiography and tomography is in operation at the Indiana University LENS facility. Neutrons from proton-induced nuclear reactions in Beryllium are moderated and collimated into a beam which is attenuated by a scanned object on a remotely-controlled rotating table. Neutron signal is then converted to a light signal with a ZnS scintillating screen and recorded in a cooled CCD. The author has performed diagnostics on the radiography hardware and software and has tested the system's capabilities by imaging a stack of high density polyethylene cubes with diverse inlet holes and grooves on an 80/20 aluminum base. The resolution of the radiographs are seen to be less than 1mm and 3D rending software is capable of reconstructing the internal structure of the aluminum. NSF.

  3. Survey of neutron radiography facilities

    SciTech Connect

    Imel, G.R.; McClellan, G.G.

    1996-08-01

    A directory of neutron radiography facilities around the world was informally compiled about ten years ago under the auspices of the American Society for Testing and Materials (ASTM), Subcommittee E7.05 (Radiology, Neutron). The work lay dormant for a number of years, but was revived in earnest in the fall of 1995. At that time, letters were mailed to all the facilities with available addresses in the original directory, requesting updated information. Additionally, information was gathered at the Second Topical meeting on neutron Radiography Facility System Design and Beam Characterization (November, 1995, Shonan Village, Japan). A second mailing was sent for final confirmation and updates in January, 1996. About 75% of the information in the directory has now been confirmed by the facility management. This paper presents a summary of the information contained in the facility directory. An electronic version of the directory in Wordperfect 6.1, uuencode, or rtf format is available by sending e-mail to the authors at imel{at}anl.gov or imel{at}baobab.cad.cea.fr. A WWW site for the directory is presently under construction.

  4. ARG portable neutron radiography. Final report

    SciTech Connect

    Barton, J.P.

    1995-04-01

    In this report all available neutron radiographic data, including results of tests run at LANL, McClellan AFB, and University of Virginia, will be combined to outline specific transportable neutron radiography systems that could achieve the desired results as a complement to x-radiography capabilities for the Accident Response Group (ARG).

  5. Multi-purpose neutron radiography system

    SciTech Connect

    Barton, J.P.; Bryant, L.E.; Berry, P.

    1996-07-01

    A conceptual design is given for a low cost, multipurpose radiography system suited for the needs of the Los Alamos National Laboratory (LANL). The proposed neutron source is californium-252. One purpose is to provide an in-house capability for occasional, reactor quality, neutron radiography thus replacing the recently closed Omega-West Reactor. A second purpose is to provide a highly reliable standby transportable neutron radiography system. A third purpose is to provide for transportable neutron probe gamma spectroscopy techniques. The cost is minimized by shared use of an existing x-ray facility, and by use of an existing transport cask. The achievable neutron radiography and radioscopy performance characteristics have been verified. The demonstrated image qualities range from high resolution gadolinium - SR film, with L:D = 100:1, to radioscopy using a LIXI image with L:D = 30:1 and neutron fluence 3.4 x 10{sup 5} n/cm{sup 2}.

  6. Californium-252: A New Isotopic Source for Neutron Radiography

    SciTech Connect

    Reinig, W.C.

    2001-08-29

    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.

  7. Lithium batteries: Application of neutron radiography

    NASA Astrophysics Data System (ADS)

    Kamata, Masahiro; Esaka, Takao; Fujine, Shigenori; Yoneda, Kenji; Kanda, Keiji

    Several kinds of primary and secondary commercial lithium batteries, such as CR1/3 · 1H (Fujitsu), CR1220 and BR435 (Panasonic), ML1220 (Sanyo Excel) were investigated using neutron radiography; the variation of the lithium distribution inside these batteries upon discharging (and charging) were clarified by analyzing their visualized images. It was demonstrated that neutron radiography is a potential and useful method, especially in evaluating the reversibility of rechargeable batteries, which have been used under different discharging/charging conditions.

  8. High Brightness Neutron Source for Radiography

    SciTech Connect

    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

    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

  9. NEUTRON IMAGING, RADIOGRAPHY AND TOMOGRAPHY.

    SciTech Connect

    SMITH,G.C.

    2002-03-01

    Neutrons are an invaluable probe in a wide range of scientific, medical and commercial endeavors. Many of these applications require the recording of an image of the neutron signal, either in one-dimension or in two-dimensions. We summarize the reactions of neutrons with the most important elements that are used for their detection. A description is then given of the major techniques used in neutron imaging, with emphasis on the detection media and position readout principle. Important characteristics such as position resolution, linearity, counting rate capability and sensitivity to gamma-background are discussed. Finally, the application of a subset of these instruments in radiology and tomography is described.

  10. Application of imaging plate neutron detector to neutron radiography

    NASA Astrophysics Data System (ADS)

    Fujine, Shigenori; Yoneda, Kenji; Kamata, Masahiro; Etoh, Masahiro

    1999-11-01

    As an imaging plate neutron detector (IP-ND) has been available for thermal neutron radiography (TNR) which has high resolution, high sensitivity and wide range, some basic characteristics of the IP-ND system were measured at the E-2 facility of the KUR. After basic performances of the IP were studied, images with high quality were obtained at a neutron fluence of 2 to 7×10 8 n cm -2. It was found that the IP-ND system with Gd 2O 3 as a neutron converter material has a higher sensitivity to γ-ray than that of a conventional film method. As a successful example, clear radiographs of the flat view for the fuel side plates with boron burnable poison were obtained. An application of the IP-ND system to neutron radiography (NR) is presented in this paper.

  11. NBS work on neutron resonance radiography

    SciTech Connect

    Schrack, R.A.

    1987-01-01

    NBS has been engaged in a wide-ranging program in Neutron Resonance Radiography utilizing both one- and two-dimensional position-sensitive neutron detectors. The ability to perform a position-sensitive assay of up to 16 isotopes in a complex matrix has been demonstrated for a wide variety of sample types, including those with high gamma activity. A major part of the program has been the development and application of the microchannel-plate-based position-sensitive neutron detector. This detector system has high resolution and sensitivity, together with adequate speed of response to be used with neutron time-of-flight techniques. This system has demonstrated the ability to simultaneously image three isotopes in a sample with no interference.

  12. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    SciTech Connect

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities, the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.

  13. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    DOE PAGESBeta

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities,more » the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.« less

  14. Beam Characterization at the Neutron Radiography Facility

    SciTech Connect

    Sarah Morgan; Jeffrey King

    2013-01-01

    The quality of a neutron imaging beam directly impacts the quality of radiographic images produced using that beam. Fully characterizing a neutron beam, including determination of the beam’s effective length-to-diameter ratio, neutron flux profile, energy spectrum, image quality, and beam divergence, is vital for producing quality radiographic images. This project characterized the east neutron imaging beamline at the Idaho National Laboratory Neutron Radiography Reactor (NRAD). The experiments which measured the beam’s effective length-to-diameter ratio and image quality are based on American Society for Testing and Materials (ASTM) standards. An analysis of the image produced by a calibrated phantom measured the beam divergence. The energy spectrum measurements consist of a series of foil irradiations using a selection of activation foils, compared to the results produced by a Monte Carlo n-Particle (MCNP) model of the beamline. Improvement of the existing NRAD MCNP beamline model includes validation of the model’s energy spectrum and the development of enhanced image simulation methods. The image simulation methods predict the radiographic image of an object based on the foil reaction rate data obtained by placing a model of the object in front of the image plane in an MCNP beamline model.

  15. Recent advances in fast neutron radiography for cargo inspection

    NASA Astrophysics Data System (ADS)

    Sowerby, B. D.; Tickner, J. R.

    2007-09-01

    Fast neutron radiography techniques are attractive for screening cargo for contraband such as narcotics and explosives. Neutrons have the required penetration, they interact with matter in a manner complementary to X-rays and they can be used to determine elemental composition. Compared to neutron interrogation techniques that measure secondary radiation (neutron or gamma-rays), neutron radiography systems are much more efficient and rapid and they are much more amenable to imaging. However, for neutron techniques to be successfully applied to cargo screening, they must demonstrate significant advantages over well-established X-ray techniques. This paper reviews recent developments and applications of fast neutron radiography for cargo inspection. These developments include a fast neutron and gamma-ray radiography system that utilizes a 14 MeV neutron generator as well as fast neutron resonance radiography systems that use variable energy quasi-monoenergetic neutrons and pulsed broad energy neutron beams. These systems will be discussed and compared with particular emphasis on user requirements, sources, detector systems, imaging ability and performance.

  16. Neutron Radiography Reactor Reactivity -- Focused Lessons Learned

    SciTech Connect

    Eric Woolstenhulme; Randal Damiana; Kenneth Schreck; Ann Marie Phillips; Dana Hewit

    2010-11-01

    As part of the Global Threat Reduction Initiative, the Neutron Radiography Reactor (NRAD) at the Idaho National Laboratory (INL) was converted from using highly enriched uranium (HEU) to low enriched uranium (LEU) fuel. After the conversion, NRAD resumed operations and is meeting operational requirements. Radiography image quality and the number of images that can be produced in a given time frame match pre-conversion capabilities. However, following the conversion, NRAD’s excess reactivity with the LEU fuel was less than it had been with the HEU fuel. Although some differences between model predictions and actual performance are to be expected, the lack of flexibility in NRAD’s safety documentation prevented adjusting the reactivity by adding more fuel, until the safety documentation could be modified. To aid future reactor conversions, a reactivity-focused Lessons Learned meeting was held. This report summarizes the findings of the lessons learned meeting and addresses specific questions posed by DOE regarding NRAD’s conversion and reactivity.

  17. Neutron Computed Tomography Using Real-Time Neutron Radiography.

    NASA Astrophysics Data System (ADS)

    Sulcoski, Mark Francis

    Conventional neutron radiography of an object records a two-dimensional distribution of the neutron beam intensity after it has passed through an object. The neutron radiograph, whether static film or real-time, may be considered a "shadow graph" of the object. In a shadow graph, internal structures in an object may mask one another making it difficult or impossible to precisely define the internals of the object. This problem can be solved by tomographic imaging. A real-time neutron radiography facility was constructed including the capability of neutron tomography. The neutron beam was measured for total neutron flux ((1.0 (+OR-) 0.2) x 10('11) n/(m('2)-sec)), gold cadmium ratio (52 (+OR-) 3) and effective neutron temperature (83(DEGREES)C (+OR -) 8(DEGREES)C). The angular divergence or nonparallelism of the neutron beam was measured to be \\2.3(DEGREES) (+OR -) 0.1(DEGREES) thereby providing a means of quantifying the collimator effectiveness. The resolution capabilities of both static film and real-time neutron radiographs were quantified using a Fourier transform algorithm to calculate the modulation transfer function of both types of radiographs. The contrast sensitivity of both types of radiographs was measured as 3.1% for film and 4.0% for real-time radiographs. Two tomography algorithms, the simultaneous iterative reconstruction technique (SIRT) and the convolution method, were programmed on an Intellect 100 Image Processing System. The SIRT algorithm was found to be too large and slow on the Intellect 100 to produce useful tomographs. The convolution method produced results near the theoretical resolution limits for a given number of projections. A tomographic resolution of at least 1.3 mm was demonstrated using 200 projections. Computer running time for the convolution method was found to be (TURN)30 seconds for each projection used. A series of experiments were conducted using the convolution method investigating the effect of high and low pass

  18. Diagnostics of coated fuel particles by neutron and synchrotron radiography

    SciTech Connect

    Momot, G. V.; Podurets, K. M.; Pogorelyi, D. K.; Somenkov, V. A.; Yakovenko, E. V.

    2011-12-15

    The nondestructive monitoring of coated fuel particles has been performed using contact neutron radiography and refraction radiography based on synchrotron radiation. It is shown that these methods supplement each other and have a high potential for determining the sizes, densities, and isotopic composition of the particle components.

  19. Deterministic simulation of thermal neutron radiography and tomography

    NASA Astrophysics Data System (ADS)

    Pal Chowdhury, Rajarshi; Liu, Xin

    2016-05-01

    In recent years, thermal neutron radiography and tomography have gained much attention as one of the nondestructive testing methods. However, the application of thermal neutron radiography and tomography is hindered by their technical complexity, radiation shielding, and time-consuming data collection processes. Monte Carlo simulations have been developed in the past to improve the neutron imaging facility's ability. In this paper, a new deterministic simulation approach has been proposed and demonstrated to simulate neutron radiographs numerically using a ray tracing algorithm. This approach has made the simulation of neutron radiographs much faster than by previously used stochastic methods (i.e., Monte Carlo methods). The major problem with neutron radiography and tomography simulation is finding a suitable scatter model. In this paper, an analytic scatter model has been proposed that is validated by a Monte Carlo simulation.

  20. Point Scattered Function (PScF) for fast neutron radiography

    NASA Astrophysics Data System (ADS)

    Hassan, Mohamed H.

    2009-08-01

    Fast neutron radiography opened up a new range of possibilities to image extremely dense objects. The removal of the scattering effect is one of the most challenging problems in neutron imaging. Neutron scattering in fast neutron radiography did not receive much attention compared with X-ray and thermal neutron radiography. The purpose of this work is to investigate the behavior of the Point Scattered Function (PScF) as applied in fast neutron radiography. The PScF was calculated using MCNP as a spatial distribution of scattered neutrons over the detector surface for one emitting source element. Armament and explosives materials, namely, Rifle steel, brass, aluminum and trinitrotoluene (TNT) were simulated. Effect of various sample thickness and sample-to-detector distance were considered. Simulated sample geometries included a slab with varying thickness, a sphere with varying radii, and a cylinder with varying base radii. Different neutron sources, namely, Cf-252, DT as well as DD neutron sources were considered. Neutron beams with zero degree divergence angle; and beams with varying angles related to the normal to the source plane were simulated. Curve fitting of the obtained PScF, in the form of Gaussian function, were given to be used in future work using image restoration codes. Analytical representation of the height as well as the Full Width at Half Maximum (FWHM) of the obtained Gaussian functions eliminates the need to calculate the PScF for sample parameters that were not investigated in this study.

  1. Imaging and Radiography with Nuclear Resonance Fluorescence and Effective-Z (EZ-3D™) Determination; SNM Detection Using Prompt Neutrons from Photon Induced Fission

    NASA Astrophysics Data System (ADS)

    Bertozzi, William; Hasty, Richard; Klimenko, Alexei; Korbly, Stephen E.; Ledoux, Robert J.; Park, William

    2009-03-01

    Four new technologies have been developed for use in non-intrusive inspection systems to detect nuclear materials, explosives and contraband. Nuclear Resonance Fluorescence (NRF) provides a three dimensional image of the isotopic content of a container. NRF determines the isotopic composition of a region and specifies the isotopic structure of the neighboring regions, thus providing the detailed isotopic composition of any threat. In transmission mode, NRF provides a two dimensional projection of the isotopic content of a container, much as standard X-ray radiography provides for density. The effective-Z method (EZ-3D™) uses electromagnetic scattering processes to yield a three-dimensional map of the effective-Z and the density in a container. The EZ-3D™ method allows for a rapid discrimination based on effective Z and mass of materials such as those with high Z, as well as specifying regions of interest for other contraband. The energy spectrum of prompt neutrons from photon induced fission (PNPF) provides a unique identification of the presence of actinides and SNM. These four new technologies can be used independently or together to automatically determine the presence of hazardous materials or contraband. They can also be combined with other technologies to provide added specificity.

  2. Neutron radiography and tomography facility at IBR-2 reactor

    NASA Astrophysics Data System (ADS)

    Kozlenko, D. P.; Kichanov, S. E.; Lukin, E. V.; Rutkauskas, A. V.; Belushkin, A. V.; Bokuchava, G. D.; Savenko, B. N.

    2016-05-01

    An experimental station for investigations using neutron radiography and tomography was developed at the upgraded high-flux pulsed IBR-2 reactor. The 20 × 20 cm neutron beam is formed by the system of collimators with the characteristic parameter L/D varying from 200 to 2000. The detector system is based on a 6LiF/ZnS scintillation screen; images are recorded using a high-sensitivity video camera based on the high-resolution CCD matrix. The results of the first neutron radiography and tomography experiments at the developed facility are presented.

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

    SciTech Connect

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

    2011-01-01

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

  4. Application of Neutron Radiography to Flow Visualization in Supercritical Water

    NASA Astrophysics Data System (ADS)

    Takenaka, N.; Sugimoto, K.; Takami, S.; Sugioka, K.; Tsukada, T.; Adschiri, T.; Saito, Y.

    Supercritical water is used in various chemical reaction processes including hydrothermal synthesis of metal oxide nano-particles, oxidation, chemical conversion of biomass and plastics. Density of the super critical water is much less than that of the sub-critical water. By using neutron radiography, Peterson et al. have studied salt precipitation processes in supercritical water and the flow pattern in a reverse-flow vessel for salt precipitation, and Balasko et al. have revealed the behaviour of supercritical water in a container. The nano-particles were made by mixing the super critical flow and the sub critical water solution. In the present study, neutron radiography was applied to the flow visualization of the super and sub critical water mixture in a T-junction made of stainless steel pipes for high pressure and temperature conditions to investigate their mixing process. Still images by a CCD camera were obtained by using the neutron radiography system at B4 port in KUR.

  5. Neutron radiography of thick hydrogenous materials with use of an imaging plate neutron detector

    NASA Astrophysics Data System (ADS)

    Kato, Kazuo; Matsumoto, Gen'ichi; Karasawa, Yuuko; Niimura, Nobuo; Matsubayashi, Masahito; Tsuruno, Akira

    1996-02-01

    The value of the neutron mass attenuation coefficient of hydrogen being very high, it is extremely difficult to image normal size, living animals with neutron radiography. However, the authors suggest the possibility of applying neutron radiography for biomedical specimens. The organs in the breast, bones and cartilages in the extremities, and the tail of mice and rats were clearly imaged by neutron radiography with Gd foils as neutron converters and X-ray films. However, no contours of the organs in the mouse abdomen were visible with neutron radiography with an exposure time of 200 s. By adding Gd or Li compounds as neutron converters to imaging X-ray plates, imaging plates have been developed for neutron detectors. A trial using these imaging plates for neutron radiography of water-filled containers and the abdomen of mice was completed. The roundness of a 100 ml-beaker was imaged with a neutron exposure of 180 s. Obscure contours of the liver and kidneys of the mouse were imaged with a neutron exposure of 100 s.

  6. Neutron radiography determination of water diffusivity in fired clay brick.

    PubMed

    El Abd, A; Czachor, A; Milczarek, J

    2009-04-01

    The real time neutron and gamma radiography station at Maria reactor, Institute of Atomic Energy, Swierk, Poland, was used to investigate the isothermal water absorption into fired clay brick samples. The investigated brick is different from the bricks reported in El Abd and Milczarek [2004. Neutron radiology study of water absorption in porous building materials: anomalous diffusing analysis. J. Phys. D: Appl. Phys. 37, 2305-2313] in density and chemical composition. Neutron radiography images were acquired regularly as the absorption time elapses. The water content, theta, along the flow direction, x, namely the water profiles theta(x,t) and the water front position as a function of the absorption time, t, were extracted from neutron radiography images. The results were discussed in terms of the macroscopic theory of water infiltration in unsaturated porous media. It was shown that the water front position followed the square root t-scaling (x(m)=phi(m) square root t) and the profiles (theta-phi) converged to a universal one master curve. The water diffusivity was analytically determined from the experimental results. It has the so-called hypo-diffusive character, namely its gradient with respect to the water content is positive. Neutron radiography is a powerful method to distinguish among the unsaturated flow in different porous construction materials.

  7. Study of pipe thickness loss using a neutron radiography method

    SciTech Connect

    Mohamed, Abdul Aziz; Wahab, Aliff Amiru Bin; Yazid, Hafizal B.; Ahmad, Megat Harun Al Rashid B. Megat; Jamro, Rafhayudi B.; Azman, Azraf B.; Zin, Muhamad Rawi Md; Idris, Faridah Mohamad

    2014-02-12

    The purpose of this preliminary work is to study for thickness changes in objects using neutron radiography. In doing the project, the technique for the radiography was studied. The experiment was done at NUR-2 facility at TRIGA research reactor in Malaysian Nuclear Agency, Malaysia. Test samples of varying materials were used in this project. The samples were radiographed using direct technique. Radiographic images were recorded using Nitrocellulose film. The films obtained were digitized to processed and analyzed. Digital processing is done on the images using software Isee!. The images were processed to produce better image for analysis. The thickness changes in the image were measured to be compared with real thickness of the objects. From the data collected, percentages difference between measured and real thickness are below than 2%. This is considerably very low variation from original values. Therefore, verifying the neutron radiography technique used in this project.

  8. Study of pipe thickness loss using a neutron radiography method

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdul Aziz; Wahab, Aliff Amiru Bin; Yazid, Hafizal B.; Ahmad, Megat Harun Al Rashid B. Megat; Jamro, Rafhayudi B.; Azman, Azraf B.; Zin, Muhamad Rawi Md; Idris, Faridah Mohamad

    2014-02-01

    The purpose of this preliminary work is to study for thickness changes in objects using neutron radiography. In doing the project, the technique for the radiography was studied. The experiment was done at NUR-2 facility at TRIGA research reactor in Malaysian Nuclear Agency, Malaysia. Test samples of varying materials were used in this project. The samples were radiographed using direct technique. Radiographic images were recorded using Nitrocellulose film. The films obtained were digitized to processed and analyzed. Digital processing is done on the images using software Isee!. The images were processed to produce better image for analysis. The thickness changes in the image were measured to be compared with real thickness of the objects. From the data collected, percentages difference between measured and real thickness are below than 2%. This is considerably very low variation from original values. Therefore, verifying the neutron radiography technique used in this project.

  9. NEUTRON RADIOGRAPHY (NRAD) REACTOR 64-ELEMENT CORE UPGRADE

    SciTech Connect

    John D. Bess

    2014-03-01

    The neutron radiography (NRAD) reactor is a 250 kW TRIGA (registered) (Training, Research, Isotopes, General Atomics) Mark II , tank-type research reactor currently located in the basement, below the main hot cell, of the Hot Fuel Examination Facility (HFEF) at the Idaho National Laboratory (INL). It is equipped with two beam tubes with separate radiography stations for the performance of neutron radiography irradiation on small test components. The interim critical configuration developed during the core upgrade, which contains only 62 fuel elements, has been evaluated as an acceptable benchmark experiment. The final 64-fuel-element operational core configuration of the NRAD LEU TRIGA reactor has also been evaluated as an acceptable benchmark experiment. Calculated eigenvalues differ significantly (approximately +/-1%) from the benchmark eigenvalue and have demonstrated sensitivity to the thermal scattering treatment of hydrogen in the U-Er-Zr-H fuel.

  10. A New Neutron Radiography / Tomography / Imaging Station DINGO at OPAL

    NASA Astrophysics Data System (ADS)

    Garbe, U.; Randall, T.; Hughes, C.; Davidson, G.; Pangelis, S.; Kennedy, S. J.

    A new neutron radiography / tomography / imaging instrument DINGO was built to support the area of neutron imaging research (neutron radiography/tomography) at ANSTO. The instrument is designed for an international user community and for routine quality control for defense, industrial, cultural heritage and archaeology applications. In the industrial field it provides a useful tool for studying cracking and defects in steel or other metals. The instrument construction was completed at the end of June 2013 and it is currently in the hot commissioning stage. The usable neutron flux is mainly determined by the neutron source, but it depends on the instrument position and the resolution. The instrument position for DINGO is the thermal neutron beam port HB-2 in the reactor hall. The measured flux (using gold foil) for an L/D of approximately 500 at HB-2 is 5.3*107 [n/cm2s], which is in a similar range to other facilities. A special feature of DINGO is the in-pile collimator position in front of the main shutter at HB-2. The collimator offers two pinholes with a possible L/D of 500 and 1000. A secondary collimator separates the two beams by blocking one and positions another aperture for the other beam. The whole instrument operates in two different positions, one for high resolution and one for high speed. In the current configuration DINGO measured first radiography and tomography data sets on friendly user test samples.

  11. Neutron transport study of a beam port based dynamic neutron radiography facility

    NASA Astrophysics Data System (ADS)

    Khaial, Anas M.

    Neutron radiography has the ability to differentiate between gas and liquid in two-phase flow due both to the density difference and the high neutron scattering probability of hydrogen. Previous studies have used dynamic neutron radiography -- in both real-time and high-speed -- for air-water, steam-water and gas-liquid metal two-phase flow measurements. Radiography with thermal neutrons is straightforward and efficient as thermal neutrons are easier to detect with relatively higher efficiency and can be easily extracted from nuclear reactor beam ports. The quality of images obtained using neutron radiography and the imaging speed depend on the neutron beam intensity at the imaging plane. A high quality neutron beam, with thermal neutron intensity greater than 3.0x 10 6 n/cm2-s and a collimation ratio greater than 100 at the imaging plane, is required for effective dynamic neutron radiography up to 2000 frames per second. The primary objectives of this work are: (1) to optimize a neutron radiography facility for dynamic neutron radiography applications and (2) to investigate a new technique for three-dimensional neutron radiography using information obtained from neutron scattering. In this work, neutron transport analysis and experimental validation of a dynamic neutron radiography facility is studied with consideration of real-time and high-speed neutron radiography requirements. A beam port based dynamic neutron radiography facility, for a target thermal neutron flux of 1.0x107 n/cm2-s, has been analyzed, constructed and experimentally verified at the McMaster Nuclear Reactor. The neutron source strength at the beam tube entrance is evaluated experimentally by measuring the thermal and fast neutron fluxes using copper activation flux-mapping technique. The development of different facility components, such as beam tube liner, gamma ray filter, beam shutter and biological shield, is achieved analytically using neutron attenuation and divergence theories. Monte

  12. New Structured Scintillators for Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Nagarkar, V. V.; Ovechkina, E. E.; Bhandari, H. B.; Soundara-Pandian, L.; More, M. J.; Riedel, R. A.; Miller, S. R.

    We report on the development of novel neutron scintillators fabricated in microcolumnar formats using the physical vapour deposition (PVD) method. Such structures mitigate the conventional trade-off between spatial resolution and detection efficiency by channelling the scintillation light towards the detector while minimizing lateral spread in the film. Consequently, high resolution and high contrast neutron images can be acquired in a time efficient manner. In this paper, we discuss methods and characterization for scintillator films made from three distinct compositions, Thallium (Tl) or Europium (Eu) doped Lithium CesiumIodide (Li3Cs2I5:Tl,Eu, referred to as LCI), Tl or Eudoped Lithium Sodium Iodide (LixNa1-xI:Tl,Eu, referred to as LNI), and Cerium (Ce)-doped Gadolinium Iodide (GdI3:Ce, referred to as GDI). LCI and LNI scintillators are derived from the well-known CsI and NaI scintillators by the incorporation of 6Li into their lattice. Based on our measurements reported here, LCI/LNI scintillators have shown to exhibit bright emissions, fast, sub-microsecond decay, and an ability to effectively discriminate between neutron and gamma interactions using pulse shape (PSD) and/or pulse height (PHD) discrimination. LCI has a density of 4.5 g/cm3, a measured peak emission wavelength of 460 nm (doped with Eu), and a light yield of ∼50,000 photons/thermal neutron. LNI has a density of 3.6 g/cm3, an emission peak measured at 420 nm, and a light yield of ∼100,000 photons/thermal neutron. The recently discovered GDI exhibits excellent scintillation properties including a bright emission of up to 5,000 photons/thermal neutron interaction, 550 nm green emission, a rise time of ∼0.5 ns and a primary decay time of ∼38 ns (Glodo et al., 2006). Its high thermal neutron cross-section of ∼255 kb makes it an attractive candidate for neutron detection and imaging. Although it has high density of 5.2 gm/cm3 and effective atomic number of 57, its gamma sensitivity can be

  13. Average Soil Water Retention Curves Measured by Neutron Radiography

    SciTech Connect

    Cheng, Chu-Lin; Perfect, Edmund; Kang, Misun; Voisin, Sophie; Bilheux, Hassina Z; Horita, Juske; Hussey, Dan

    2011-01-01

    Water retention curves are essential for understanding the hydrologic behavior of partially-saturated porous media and modeling flow transport processes within the vadose zone. In this paper we report direct measurements of the main drying and wetting branches of the average water retention function obtained using 2-dimensional neutron radiography. Flint sand columns were saturated with water and then drained under quasi-equilibrium conditions using a hanging water column setup. Digital images (2048 x 2048 pixels) of the transmitted flux of neutrons were acquired at each imposed matric potential (~10-15 matric potential values per experiment) at the NCNR BT-2 neutron imaging beam line. Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert s law after taking into account beam hardening and geometric corrections. To remove scattering effects at high water contents the volumetric water contents were normalized (to give relative saturations) by dividing the drying and wetting sequences of images by the images obtained at saturation and satiation, respectively. The resulting pixel values were then averaged and combined with information on the imposed basal matric potentials to give average water retention curves. The average relative saturations obtained by neutron radiography showed an approximate one-to-one relationship with the average values measured volumetrically using the hanging water column setup. There were no significant differences (at p < 0.05) between the parameters of the van Genuchten equation fitted to the average neutron radiography data and those estimated from replicated hanging water column data. Our results indicate that neutron imaging is a very effective tool for quantifying the average water retention curve.

  14. Analyzing the effect of geometric factors on designing neutron radiography system.

    PubMed

    Amini, Moharam; Fadaei, Amir Hosein; Gharib, Morteza

    2015-11-01

    Neutron radiography is one of the main applications of research reactors. It is a powerful tool to conduct nondestructive testing of materials. The parameters that affect the quality of a radiographic image must be considered during the design of a neutron radiography system. Hence, this study aims to investigate the effect of geometric factors on the quality of the neutron radiography system. The results show that the performance of the mentioned system can be increased by regulating the geometric factors. PMID:26343340

  15. Spectroscopic neutron radiography for a cargo scanning system

    NASA Astrophysics Data System (ADS)

    Rahon, Jill; Danagoulian, Areg; MacDonald, Thomas D.; Hartwig, Zachary S.; Lanza, Richard C.

    2016-06-01

    Detection of cross-border smuggling of illicit materials and contraband is a challenge that requires rapid, low-dose, and efficient radiographic technology. The work we describe here is derived from a technique which uses monoenergetic gamma rays from low energy nuclear reactions, such as 11B(d,nγ)12C, to perform radiographic analysis of shipping containers. Transmission ratios of multiple monoenergetic gamma lines resulting from several gamma producing nuclear reactions can be employed to detect materials of high atomic number (Z), the details of which will be described in a separate paper. Inherent in this particular nuclear reaction is the production of fast neutrons which could enable neutron radiography and further characterization of the effective-Z of the cargo, especially within the range of lower Z. Previous research efforts focused on the use of total neutron counts in combination with X-ray radiography to characterize the hydrogenous content of the cargo. We present a technique of performing transmitted neutron spectral analysis to reconstruct the effective Z and potentially the density of the cargo. This is made possible by the large differences in the energy dependence of neutron scattering cross-sections between hydrogenous materials and those of higher Z. These dependencies result in harder transmission spectra for hydrogenous cargoes than those of non-hydrogenous cargoes. Such observed differences can then be used to classify the cargo based on its hydrogenous content. The studies presented in this paper demonstrate that such techniques are feasible and can provide a contribution to cargo security, especially when used in concert with gamma radiography.

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

    SciTech Connect

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

    2013-02-05

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

  17. Characterization of non-tuberculosis mycobacteria by neutron radiography.

    PubMed

    da Silva, Jaqueline M; Crispim, Verginia Reis; da Silva, Marlei Gomes; Furtado, Vanessa Rodrigues; Duarte, Rafael Da Silva

    2013-07-01

    The genus Mycobacterium shares many characteristics with Corynebacterium and Actinomyces genera, among which the genomic guanine plus cytosine content and the production of long branched-chain fatty acids, known as mycolic acids are enhanced. Growth rate and optimal temperature of mycobacteria are variable. The genus comprises more than 140 known species; however Mycobacterium fortuitum, a fast growing nontuberculous mycobacterium, is clinically significant, because it has been associated to several lesions following surgery procedures such as liposuction, silicone breast and pacemaker implants, exposure to prosthetic materials besides sporadic lesions in the skin, soft tissues and rarely lungs. The objective of the present study is to reduce the time necessary for M. fortuitum characterization based on its morphology and the use of the neutron radiography technique substituting the classical biochemical assays. We also aim to confirm the utility of dendrimers as boron carriers. The samples were sterilized through conventional protocols using 10% formaldehyde. In the incubation process, two solutions with different molar ratios (10:1 and 20:1) of sodium borate and PAMAM G4 dendrimer and also pure sodium borate were used. After doping and sterilization procedures, the samples were deposited on CR-39 sheets, irradiated with a 4.6×10(5) n/cm(2)s thermal neutron flux for 30 min, from the J-9 irradiation channel of the Argonauta IEN/CNEN reactor. The images registered in the CR-39 were visualized in a Nikon E400 optical transmission microscope and captured by a Nikon Coolpix 995 digital camera. Developing the nuclear tracks registered in the CR-39 allowed a 1000× enlargement of mycobacterium images, facilitating their characterization, the use of more sophisticated equipment not being necessary. The use of neutron radiography technique reduced the time necessary for characterization. Doping with PAMAM dendrimer improved the visualization of NTM in neutron radiography

  18. Neutron Resonance Radiography for Explosives Detection: Technical Challenges

    SciTech Connect

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

    2005-11-09

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

  19. Development of a system for neutron radiography and tomography

    NASA Astrophysics Data System (ADS)

    Mühlbauer, Martin J.; Calzada, Elbio; Schillinger, Burkhard

    2005-04-01

    Neutron radiography and tomography are getting more and more popular. Since they use the white thermal neutron spectrum, they are especially feasible even at small neutron sources, where the flux is too low for efficient scattering experiments requiring monochromatization of the beam. High-end tomography systems require the investment of several ten thousand Euros, with the costs often hindering the initiative for a new tomography setup. Based on the experiences gathered at Technische Universitaet Muenchen, we developed a cheaper system based on standard components that cannot compete with the sensitivity of a high-grade system, but is perfectly capable of doing neutron radiography and tomography. The system is meant as a startup construction kit for initiating tomography programs even at small neutron sources. The system is built from scratch, enabling the user to gain an understanding for the influence of each component on the image results. With the experience thus gained, he should be able to design his next and more advanced system by himself. To keep the whole system simple and cheap (the price should reach only a few percent of a high-end system), standard parts are used whenever possible, and all components are designed in such a way that they can be built without special equipment. Public domain and freeware software is used for data processing. Such a system is being built at FRM2 in Garching within the scope of a master thesis. After completion, a website will be installed with descriptions, diagrams and software for building and operating the system. Both hardware and software are discussed.

  20. New detector for use in fast neutron radiography

    SciTech Connect

    Popov, V.; Degtiarenko, P.; Musatov, I.

    2011-01-01

    We have developed and tested a new type detector for use in the fast neutron (FN) imaging radiography applications. FN radiography is generally used for nondestructive material testing, medical and biology applications, border patrol, transportation and cargo screening tasks. It is complementary to other types of radiography, providing additional information on light element content of the material samples. Distinct from other FN imagers presently known, our device implements a neutron-sensitive scintillator attached to a position-sensitive photomultiplier tube (PSPMT), and operates in an event-by-event readout mode, acquiring energy, timing, and pulse shape information for all detected radiation events. The information is used to help separate events of FN interactions in the scintillator from the background events caused by the electronics noise and by the other types of background radiation. Selection of pure fast neutron events in the final image allows us to achieve ultimate image contrast and resolution, as compared with other types of FN imaging devices operating most commonly in an integration mode, in which the detector's dark noise and radiation background dilute the images. The detector performance for FN imaging application was tested using D-D neutron generator, designed and manufactured by Adelphi Technology, Inc. This essentially point-like neutron source operates in continuous mode producing up to 109 of 2.5 MeV neutrons per second. Samples made of metals plastic and other material were used to measure the detector resolution, efficiency and uniformity. Results of these tests are presented and discussed. Fig. 1 shows one of the test FN radiographic images obtained using the sample made of 11 styrene plastic strips. All strips are squares 4.8 x 4.8 mm2 with six different lengths 10 to 60 mm with 10 mm increment. [A] [B] [C] Fig. 1. [A]-layout of the test sample; [B]-raw FN shadow image of the sample; [C]-map of the plastic strips as they appear on

  1. Digital fast neutron radiography of steel reinforcing bar in concrete

    NASA Astrophysics Data System (ADS)

    Mitton, K.; Jones, A.; Joyce, M. J.

    2014-12-01

    Neutron imaging has previously been used in order to test for cracks, degradation and water content in concrete. However, these techniques often fall short of alternative non-destructive testing methods, such as γ-ray and X-ray imaging, particularly in terms of resolution. Further, thermal neutron techniques can be compromised by the significant expense associated with thermal neutron sources of sufficient intensity to yield satisfactory results that can often precipitate the need for a reactor. Such embodiments are clearly not portable in the context of the needs of field applications. This paper summarises the results of a study to investigate the potential for transmission radiography based on fast neutrons. The objective of this study was to determine whether the presence of heterogeneities in concrete, such as reinforcement structures, could be identified on the basis of variation in transmitted fast-neutron flux. Monte-Carlo simulations have been performed and the results from these are compared to those arising from practical tests using a 252Cf source. The experimental data have been acquired using a digital pulse-shape discrimination system that enables fast neutron transmission to be studied across an array of liquid scintillators placed in close proximity to samples under test, and read out in real time. Whilst this study does not yield sufficient spatial resolution, a comparison of overall flux ratios does provide a basis for the discrimination between samples with contrasting rebar content. This approach offers the potential for non-destructive testing that gives less dose, better transportability and better accessibility than competing approaches. It is also suitable for thick samples where γ-ray and X-ray methods can be limited.

  2. Visualization of embolism formation in the xylem of liana stems using neutron radiography

    PubMed Central

    Tötzke, Christian; Miranda, Tatiana; Konrad, Wilfried; Gout, Julien; Kardjilov, Nikolay; Dawson, Martin; Manke, Ingo; Roth-Nebelsick, Anita

    2013-01-01

    Background and Aims Cold neutron radiography was applied to directly observe embolism in conduits of liana stems with the aim to evaluate the suitability of this method for studying embolism formation and repair. Potential advantages of this method are a principally non-invasive imaging approach with low energy dose compared with synchrotron X-ray radiation, a good spatial and temporal resolution, and the possibility to observe the entire volume of stem portions with a length of several centimetres at one time. Methods Complete and cut stems of Adenia lobata, Aristolochia macrophylla and Parthenocissus tricuspidata were radiographed at the neutron imaging facility CONRAD at the Helmholtz-Zentrum Berlin für Materialien und Energie, with each measurement cycle lasting several hours. Low attenuation gas spaces were separated from the high attenuation (water-containing) plant tissue using image processing. Key results Severe cuts into the stem were necessary to induce embolism. The formation and temporal course of an embolism event could then be successfully observed in individual conduits. It was found that complete emptying of a vessel with a diameter of 100 µm required a time interval of 4 min. Furthermore, dehydration of the whole stem section could be monitored via decreasing attenuation of the neutrons. Conclusions The results suggest that cold neutron radiography represents a useful tool for studying water relations in plant stems that has the potential to complement other non-invasive methods. PMID:23393096

  3. Technical Specifications for the Neutron Radiography Facility (TRIGA Mark 1 Reactor). Revision 6

    SciTech Connect

    Tomlinson, R.L.; Perfect, J.F.

    1988-04-01

    These Technical Specifications state the limits under which the Neutron Radiography Facility, with its associated TRIGA Mark I Reactor, is operated by the Westinghouse Hanford Company for the US Department of Energy. These specifications cover operation of the Facility for the purpose of examination of specimens (including contained fissile material) by neutron radiography, for the irradiation of specimens in the pneumatic transfer system and approved in-core or in-pool irradiation facilities and operator training. The Final Safety Analysis Report (TC-344) and its supplements, and these Technical Specifications are the basic safety documents of the Neutron Radiography Facility.

  4. Inspection of an artificial heart by the neutron radiography technique

    NASA Astrophysics Data System (ADS)

    Pugliesi, R.; Geraldo, L. P.; Andrade, M. L. G.; Menezes, M. O.,; Pereira, M. A. S.; Maizato, M. J. S.

    1999-11-01

    The neutron radiography technique was employed to inspect an artificial heart prototype which is being developed to provide blood circulation for patients expecting heart transplant surgery. The radiographs have been obtained by the direct method with a gadolinium converter screen along with the double coated Kodak-AA emulsion film. The artificial heart consists of a flexible plastic membrane located inside a welded metallic cavity, which is employed for blood pumping purposes. The main objective of the present inspection was to identify possible damages in this plastic membrane, produced during the welding process of the metallic cavity. The obtained radiographs were digitized as well as analysed in a PC and the improved images clearly identify several damages in the plastic membrane, suggesting changes in the welding process.

  5. Dy-IP characterization and its application for experimental neutron radiography tests under realistic conditions

    NASA Astrophysics Data System (ADS)

    Tamaki, Masayoshi; Iida, Kazuhiro; Mori, Noriaki; Lehmann, Eberhard H.; Vontobel, Peter; Estermann, Mirko

    2005-04-01

    Imaging plates containing Dy for neutron radiography have been designed, fabricated and tested experimentally. Using the imaging plates combined with the developed NR system and the honeycomb collimator, quantitative neutron radiograph, which is free from scattered neutron and γ-ray, has been obtained. Application has been conducted for the post-irradiation examination for the nuclear fuel pin.

  6. Dynamic and static error analyses of neutron radiography testing

    SciTech Connect

    Joo, H.; Glickstein, S.S.

    1999-03-01

    Neutron radiography systems are being used for real-time visualization of the dynamic behavior as well as time-averaged measurements of spatial vapor fraction distributions for two phase fluids. The data in the form of video images are typically recorded on videotape at 30 frames per second. Image analysis of he video pictures is used to extract time-dependent or time-averaged data. The determination of the average vapor fraction requires averaging of the logarithm of time-dependent intensity measurements of the neutron beam (gray scale distribution of the image) that passes through the fluid. This could be significantly different than averaging the intensity of the transmitted beam and then taking the logarithm of that term. This difference is termed the dynamic error (error in the time-averaged vapor fractions due to the inherent time-dependence of the measured data) and is separate from the static error (statistical sampling uncertainty). Detailed analyses of both sources of errors are discussed.

  7. The relationship between contrast, resolution and detectability in accelerator-based fast neutron radiography

    SciTech Connect

    Ambrosi, R. M.; Watterson, J. I. W.

    1999-06-10

    Fast neutron radiography as a method for non destructive testing is a fast growing field of research. At the Schonland Research Center for Nuclear Sciences we have been engaged in the formulation of a model for the physics of image formation in fast neutron radiography (FNR). This involves examining all the various factors that affect image formation in FNR by experimental and Monte Carlo methods. One of the major problems in the development of a model for fast neutron radiography is the determination of the factors that affect image contrast and resolution. Monte Carlo methods offer an ideal tool for the determination of the origin of many of these factors. In previous work the focus of these methods has been the determination of the scattered neutron field in both a scintillator and a fast neutron radiography facility. As an extension of this work MCNP has been used to evaluate the role neutron scattering in a specimen plays in image detectability. Image processing of fast neutron radiographs is a necessary method of enhancing the detectability of features in an image. MCNP has been used to determine the part it can play in indirectly improving image resolution and aiding in image processing. The role noise plays in fast neutron radiography and its impact on image reconstruction has been evaluated. All these factors aid in the development of a model describing the relationship between contrast, resolution and detectability.

  8. High-speed neutron radiography for monitoring the water absorption by capillarity in porous materials

    NASA Astrophysics Data System (ADS)

    Cnudde, Veerle; Dierick, Manuel; Vlassenbroeck, Jelle; Masschaele, Bert; Lehmann, Eberhard; Jacobs, Patric; Van Hoorebeke, Luc

    2008-01-01

    Fluid flow through porous natural building stones is of great importance when studying their weathering processes. Many traditional experiments based on mass changes are available for studying liquid transport in porous stones, such as the determination of the water absorption coefficient by capillarity. Because thermal neutrons experience a strong attenuation by hydrogen, neutron radiography is a suitable technique for the study of water absorption by capillarity in porous stones. However, image contrast can be impaired because hydrogen mainly scatters neutrons rather than absorbing them, resulting in a blurred image. Capillarity results obtained by neutron radiography and by the European Standard 1925 for the determination of the water absorption coefficient by capillarity for natural building stones with a variable porosity were compared. It is illustrated that high-speed neutron radiography can be a useful research tool for the visualization of internal fluid flow inside inorganic building materials such as limestones and sandstones.

  9. Bright Flash Neutron Radiography at the McClellan Nuclear Research Reactor

    NASA Astrophysics Data System (ADS)

    Lerche, M.; Tremsin, A. S.; Schillinger, B.

    The University of California, Davis McClellan Nuclear Research Center (MNRC) operates a 2 MW TRIGATM reactor, which is currently the highest power TRIGATM reactor in the United States. The Center was originally build by the US Air Force to detect hidden defects in aircraft structures using neutron radiography; the Center can accommodate samples as large as 10.00 m long, 3.65 m high, and weighing up to 2,270 kg. The MNRC reactor can be pulsed to 350 MW for about 30 ms (FWHM). The combination of a short neutron pulse with a fast microchannel plate based neutron detector enables high-resolution flash neutron radiography to complement conventional neutron radiography

  10. Characterization of the Annular Core Research Reactor (ACRR) Neutron Radiography System Imaging Plane

    NASA Astrophysics Data System (ADS)

    Kaiser, Krista; Chantel Nowlen, K.; DePriest, K. Russell

    2016-02-01

    The Annular Core Research Reactor (ACRR) at Sandia National Laboratories (SNL) is an epithermal pool-type research reactor licensed up to a thermal power of 2.4 MW. The ACRR facility has a neutron radiography facility that is used for imaging a wide range of items including reactor fuel and neutron generators. The ACRR neutron radiography system has four apertures (65:1, 125:1, 250:1, and 500:1) available to experimenters. The neutron flux and spectrum as well as the gamma dose rate were characterized at the imaging plane for the ACRR's neutron radiography system for the 65:1, 125:1 and 250:1 apertures.

  11. Quantifying moisture transport in cementitious materials using neutron radiography

    NASA Astrophysics Data System (ADS)

    Lucero, Catherine L.

    . It has been found through this study that small pores, namely voids created by chemical shrinkage, gel pores, and capillary pores, ranging from 0.5 nm to 50 microm, fill quickly through capillary action. However, large entrapped and entrained air voids ranging from 0.05 to 1.25 mm remain empty during the initial filling process. In mortar exposed to calcium chloride solution, a decrease in sorptivity was observed due to an increase in viscosity and surface tension of the solution as proposed by Spragg et al 2011. This work however also noted a decrease in the rate of absorption due to a reaction between the salt and matrix which results in the filling of the pores in the concrete. The results from neutron imaging can help in the interpretation of standard absorption tests. ASTM C1585 test results can be further analyzed in several ways that could give an accurate indication of the durability of the concrete. Results can be reported in depth of penetration versus the square root of time rather than mm3 of fluid per mm2 of exposed surface area. Since a known fraction of pores are initially filling before reaching the edge of the sample, the actual depth of penetration can be calculated. This work is compared with an 'intrinsic sorptivity' that can be used to interpret mass measurements. Furthermore, the influence of shrinkage reducing admixtures (SRAs) on drying was studied. Neutron radiographs showed that systems saturated in water remain "wetter" than systems saturated in 5% SRA solution. The SRA in the system reduces the moisture diffusion coefficient due an increase in viscosity and decrease in surface tension. Neutron radiography provided spatial information of the drying front that cannot be achieved using other methods.

  12. Neutron radiography activity in the european program cost 524: Neutron imaging techniques

    NASA Astrophysics Data System (ADS)

    Chirco, P.; Bach, P.; Lehmann, E.; Balasko, M.

    2001-07-01

    COST is a framework for scientific and technical cooperation, allowing the coordination of national research on a European level, including 32 member countries. Participation of institutes from non-COST countries is possible. From an initial 7 Actions in 1971, COST has grown to 200 Actions at the beginning of 2000. COST Action 524 is under materials domain, the title of which being "Neutron Imaging Techniques for the Detection of Defects in Materials", under the Chairmanship of Dr. P. Chirco (I.N.F.N.). The following countries are represented in the Management Committee of Action 524: Italy, France, Austria, Germany, United Kingdom, Hungary, Switzerland, Spain, Czech Republic, Slovenia, and Russia. The six working groups of this Action are working respectively on standardization of neutron radiography techniques, on aerospace application, on civil engineering applications, on comparison and integration of neutron imaging techniques with other NDT, on neutron tomography, and on non radiographic techniques such as neutron scattering techniques. A specific effort is devoted to standardization issues, with respect to other non European standards. Results of work performed in the COST frame are published or will be published in the review INSIGHT, edited by the British Institute of Non Destructive Testing.

  13. Bright flash neutron radiography capability of the research reactor at the McClellan Nuclear Research Center

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Lerche, M.; Schillinger, B.; Feller, W. B.

    2014-06-01

    The capability to produce a bright, short neutron pulse at the McClellan Nuclear Research Center (MNRC) can be very attractive for some neutron imaging applications. Complementary to conventional thermal neutron radiography conducted at the reactor, operating at the average power of 1 MW, a short pulse of ~25 ms FWHM duration can be produced at MNRC with the peak power exceeding 350 MW. Combination of a fast thermal neutron counting detector with a short neutron pulse at MNRC, enables high-resolution stroboscopic imaging to complement conventional neutron radiography. The results presented in this paper demonstrate the MNRC capabilities for conducting conventional thermal neutron radiography, demonstrating imaging spatial resolution below 100 μm, as well as bright flash neutron radiography with multiple nearly simultaneous events detected with microsecond timing resolution.

  14. Neutron radiography with sub-15 μm resolution through event centroiding

    NASA Astrophysics Data System (ADS)

    Tremsin, Anton S.; McPhate, Jason B.; Vallerga, John V.; Siegmund, Oswald H. W.; Bruce Feller, W.; Lehmann, Eberhard; Kaestner, Anders; Boillat, Pierre; Panzner, Tobias; Filges, Uwe

    2012-10-01

    Conversion of thermal and cold neutrons into a strong ˜1 ns electron pulse with an absolute neutron detection efficiency as high as 50-70% makes detectors with 10B-doped Microchannel Plates (MCPs) very attractive for neutron radiography and microtomography applications. The subsequent signal amplification preserves the location of the event within the MCP pore (typically 6-10 μm in diameter), providing the possibility to perform neutron counting with high spatial resolution. Different event centroiding techniques of the charge landing on a patterned anode enable accurate reconstruction of the neutron position, provided the charge footprints do not overlap within the time required for event processing. The new fast 2×2 Timepix readout with >1.2 kHz frame rates provides the unique possibility to detect neutrons with sub-15 μm resolution at several MHz/cm2 counting rates. The results of high resolution neutron radiography experiments presented in this paper, demonstrate the sub-15 μm resolution capability of our detection system. The high degree of collimation and cold spectrum of ICON and BOA beamlines combined with the high spatial resolution and detection efficiency of MCP-Timepix detectors are crucial for high contrast neutron radiography and microtomography with high spatial resolution. The next generation of Timepix electronics with sparsified readout should enable counting rates in excess of 107 n/cm2/s taking full advantage of high beam intensity of present brightest neutron imaging facilities.

  15. Swelling behavior detection of irradiated U-10Zr alloy fuel using indirect neutron radiography

    NASA Astrophysics Data System (ADS)

    Sun, Yong; Huo, He-yong; Wu, Yang; Li, Jiangbo; Zhou, Wei; Guo, Hai-bing; Li, Hang; Cao, Chao; Yin, Wei; Wang, Sheng; Liu, Bin; Feng, Qi-jie; Tang, Bin

    2016-11-01

    It is hopeful that fusion-fission hybrid energy system will become an effective approach to achieve long-term sustainable development of fission energy. U-10Zr alloy (which means the mass ratio of Zr is 10%) fuel is the key material of subcritical blanket for fusion-fission hybrid energy system which the irradiation performance need to be considered. Indirect neutron radiography is used to detect the irradiated U-10Zr alloy because of the high residual dose in this paper. Different burnup samples (0.1%, 0.3%, 0.5% and 0.7%) have been tested with a special indirect neutron radiography device at CMRR (China Mianyang Research Reactor). The resolution of the device is better than 50 μm and the quantitative analysis of swelling behaviors was carried out. The results show that the swelling behaviors relate well to burnup character which can be detected accurately by indirect neutron radiography.

  16. Image enhancement using MCNP5 code and MATLAB in neutron radiography.

    PubMed

    Tharwat, Montaser; Mohamed, Nader; Mongy, T

    2014-07-01

    This work presents a method that can be used to enhance the neutron radiography (NR) image for objects with high scattering materials like hydrogen, carbon and other light materials. This method used Monte Carlo code, MCNP5, to simulate the NR process and get the flux distribution for each pixel of the image and determines the scattered neutron distribution that caused image blur, and then uses MATLAB to subtract this scattered neutron distribution from the initial image to improve its quality. This work was performed before the commissioning of digital NR system in Jan. 2013. The MATLAB enhancement method is quite a good technique in the case of static based film neutron radiography, while in neutron imaging (NI) technique, image enhancement and quantitative measurement were efficient by using ImageJ software. The enhanced image quality and quantitative measurements were presented in this work.

  17. Corrections on energy spectrum and scatterings for fast neutron radiography at NECTAR facility

    NASA Astrophysics Data System (ADS)

    Liu, Shu-Quan; Bücherl, Thomas; Li, Hang; Zou, Yu-Bin; Lu, Yuan-Rong; Guo, Zhi-Yu

    2013-11-01

    Distortions caused by the neutron spectrum and scattered neutrons are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM- II in Technische Universität München (TUM), Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by the neutron spectrum, and the Point Scattered Function (PScF) simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve image quality. Good analysis results prove the sound effects of the above two corrections.

  18. Proposed power upgrade of the Hot Fuel Examination Facility's neutron radiography reactor. [NRAD reactor

    SciTech Connect

    Pruett, D.P.; Richards, W.J.; Heidel, C.C.

    1984-01-01

    The Hot Fuel Examination Facility, HFEF, is one of several facilities located at the Argonne Site. HFEF comprises a large hot cell where both non-destructive and destructive examination of highly-irradiated reactor fuels are conducted in support of the LMFBR program. One of the non-destructive examination techniques utilized at HFEF is neutron radiography. Neutron radiography is provided by the NRAD reactor facility, which is located beneath the HFEF hot cell. The NRAD reactor is a TRIGA reactor and is operated at a steady state power level of 250 kW solely for neutron radiography and the development of radiography techniques. When the NRAD facility was designed and constructed, an operating power level of 250 kW was considered to be adequate for obtaining radiographs of the type of specimens envisaged at that time. A typical radiograph required approximately a twenty-minute exposure time. Specimens were typically single fuel rods placed in an aluminum tray. Since that time, however, several things have occurred that have tended to increase radiography exposure times to as much as 90 minutes each. In order to decrease exposure times, the reactor power level is to be increased from 250 kw to 1 MW. This increase in power will necessitate several engineering and design changes. These changes are described.

  19. Neutron radiography as a non-destructive method for diagnosing neutron converters for advanced thermal neutron detectors

    NASA Astrophysics Data System (ADS)

    Muraro, A.; Albani, G.; Perelli Cippo, E.; Croci, G.; Angella, G.; Birch, J.; Cazzaniga, C.; Caniello, R.; Dell'Era, F.; Ghezzi, F.; Grosso, G.; Hall-Wilton, R.; Höglund, C.; Hultman, L.; Schimdt, S.; Robinson, L.; Rebai, M.; Salvato, G.; Tresoldi, D.; Vasi, C.; Tardocchi, M.

    2016-03-01

    Due to the well-known problem of 3He shortage, a series of different thermal neutron detectors alternative to helium tubes are being developed, with the goal to find valid candidates for detection systems for the future spallation neutron sources such as the European Spallation Source (ESS). A possible 3He-free detector candidate is a charged particle detector equipped with a three dimensional neutron converter cathode (3D-C). The 3D-C currently under development is composed by a series of alumina (Al2O3) lamellas coated by 1 μ m of 10B enriched boron carbide (B4C). In order to obtain a good characterization in terms of detector efficiency and uniformity it is crucial to know the thickness, the uniformity and the atomic composition of the B4C neutron converter coating. In this work a non-destructive technique for the characterization of the lamellas that will compose the 3D-C was performed using neutron radiography. The results of these measurements show that the lamellas that will be used have coating uniformity suitable for detector applications. This technique (compared with SEM, EDX, ERDA, XPS) has the advantage of being global (i.e. non point-like) and non-destructive, thus it is suitable as a check method for mass production of the 3D-C elements.

  20. High Resolution Neutron Radiography and Tomography of Hydrided Zircaloy-4 Cladding Materials

    SciTech Connect

    Smith, Tyler S; Bilheux, Hassina Z; Ray, Holly B; Bilheux, Jean-Christophe; Yan, Yong

    2015-01-01

    Neutron radiography for hydrogen analysis was performed with several Zircaloy-4 cladding samples with controlled hydrogen concentrations up to 1100 ppm. Hydrogen charging was performed in a process tube that was heated to facilitate hydrogen absorption by the metal. A correlation between the hydrogen concentration in the hydrided tubes and the neutron intensity was established, by which hydrogen content can be determined precisely in a small area (55 m x 55 m). Radiography analysis was also performed to evaluate the heating rate and its correlation with the hydrogen distribution through hydrided materials. In addition to radiography analysis, tomography experiments were performed on Zircaloy-4 tube samples to study the local hydrogen distribution. Through tomography analysis a 3D reconstruction of the tube was evaluated in which an uneven hydrogen distribution in the circumferential direction can be observed.

  1. Design, construction and characterization of a new neutron beam for neutron radiography at the Tehran Research Reactor

    NASA Astrophysics Data System (ADS)

    Choopan Dastjerdi, M. H.; Khalafi, H.; Kasesaz, Y.; Mirvakili, S. M.; Emami, J.; Ghods, H.; Ezzati, A.

    2016-05-01

    To obtain a thermal neutron beam for neutron radiography applications, a neutron collimator has been designed and implemented at the Tehran Research Reactor (TRR). TRR is a 5 MW open pool light water moderated reactor with seven beam tubes. The neutron collimator is implemented in the E beam tube of the TRR. The design of the neutron collimator was performed using MCNPX Monte Carlo code. In this work, polycrystalline bismuth and graphite have been used as a gamma filter and an illuminator, respectively. The L/D parameter of the facility was chosen in the range of 150-250. The thermal neutron flux at the image plane can be varied from 2.26×106 to 6.5×106 n cm-2 s-1. Characterization of the beam was performed by ASTM standard IQI and foil activation technique to determine the quality of neutron beam. The results show that the obtained neutron beam has a good quality for neutron radiography applications.

  2. A simple model for neutron radiography of uranium-plutonium mixed oxide fuel pins

    NASA Astrophysics Data System (ADS)

    Panakkal, J. P.; Ghosh, J. K.

    1988-04-01

    Neutron radiography has been used for monitoring plutonium enrichment in uranium-plutonium mixed oxide fuel pellets inside welded nuclear fuel pins by correlating the optical density of radiographs at the centre of the pellets and plutonium enrichment. Optical density data corresponding to different thickness of the pellets starting from the centre towards the periphery was generated by microdensitometer scanning of neutron radiographs of the experimental fuel pins. An attempt has been made to correlate the optical density at points corresponding to different thickness segments of the pellets and thermal neutron interaction probability (product of the total macroscopic neutron cross section and the distance traversed by the neutrons). Based on the experimental data generated, a simple model for transmission of neutrons through nuclear fuel pins has been evolved. Using this model, it is possible to predict the optical density of plutonium bearing fuel pins containing pellets of different composition or diameter in neutron radiographic investigations.

  3. Digital processing to improve image quality in real-time neutron radiography

    NASA Astrophysics Data System (ADS)

    Fujine, Shigenori; Yoneda, Kenji; Kanda, Keiji

    1985-01-01

    Real-time neutron radiography (NTV) has been used for practical applications at the Kyoto University Reactor (KUR). At present, however, the direct image from the TV system is still poor in resolution and low in contrast. In this paper several image improvements are demonstrated, such as a frame summing technique, which are effective in increasing image quality in neutron radiography. Image integration before the A/D converter has a beneficial effect on image quality and the high quality image reveals details invisible in direct images, such as: small holes by a reversed image, defects in a neutron converter screen through a high quality image, a moving object in a contoured image, a slight difference between two low-contrast images by a subtraction technique, and so on. For the real-time application a contouring operation and an averaging approach can also be utilized effectively.

  4. Design and initial 1D radiography tests of the FANTOM mobile fast-neutron radiography and tomography system

    NASA Astrophysics Data System (ADS)

    Andersson, P.; Valldor-Blücher, J.; Andersson Sundén, E.; Sjöstrand, H.; Jacobsson-Svärd, S.

    2014-08-01

    The FANTOM system is a tabletop sized fast-neutron radiography and tomography system newly developed at the Applied Nuclear Physics Division of Uppsala University. The main purpose of the system is to provide time-averaged steam-and-water distribution measurement capability inside the metallic structures of two-phase test loops for light water reactor thermal-hydraulic studies using a portable fusion neutron generator. The FANTOM system provides a set of 1D neutron transmission data, which may be inserted into tomographic reconstruction algorithms to achieve a 2D mapping of the steam-and-water distribution. In this paper, the selected design of FANTOM is described and motivated. The detector concept is based on plastic scintillator elements, separated for spatial resolution. Analysis of pulse heights on an event-to-event basis is used for energy discrimination. Although the concept allows for close stacking of a large number of detector elements, this demonstrator is equipped with only three elements in the detector and one additional element for monitoring the yield from the neutron generator. The first measured projections on test objects of known configurations are presented. These were collected using a Sodern Genie 16 neutron generator with an isotropic yield of about 1E8 neutrons per second, and allowed for characterization of the instrument's capabilities. At an energy threshold of 10 MeV, the detector offered a count rate of about 500 cps per detector element. The performance in terms of spatial resolution was validated by fitting a Gaussian Line Spread Function to the experimental data, a procedure that revealed a spatial unsharpness in good agreement with the predicted FWHM of 0.5 mm.

  5. New Developments in Proton Radiography at the Los Alamos Neutron Science Center (LANSCE)

    SciTech Connect

    Morris, C. L.; Brown, E. N.; Agee, C.; Bernert, T.; Bourke, M. A. M.; Burkett, M. W.; Buttler, W. T.; Byler, D. D.; Chen, C. F.; Clarke, A. J.; Cooley, J. C.; Gibbs, P. J.; Imhoff, S. D.; Jones, R.; Kwiatkowski, K.; Mariam, F. G.; Merrill, F. E.; Murray, M. M.; Olinger, C. T.; Oro, D. M.; Nedrow, P.; Saunders, A.; Terrones, G.; Trouw, F.; Tupa, D.; Vogan, W.; Winkler, B.; Wang, Z.; Zellner, M. B.

    2015-12-30

    An application of nuclear physics, a facility for using protons for flash radiography, was developed at the Los Alamos Neutron Science Center (LANSCE). Protons have proven far superior to high energy x-rays for flash radiography because of their long mean free path, good position resolution, and low scatter background. Although this facility is primarily used for studying very fast phenomena such as high explosive driven experiments, it is finding increasing application to other fields, such as tomography of static objects, phase changes in materials and the dynamics of chemical reactions. The advantages of protons are discussed, data from some recent experiments will be reviewed and concepts for new techniques are introduced.

  6. Discriminated neutron and X-ray radiography using multi-color scintillation detector

    NASA Astrophysics Data System (ADS)

    Nittoh, Koichi; Takahara, Takeshi; Yoshida, Tadashi; Tamura, Toshiyuki

    1999-06-01

    A new conversion screen Gd 2O 2S:Eu is developed, which emits red light on irradiation by thermal neutrons. By applying this in combination with the currently used Gd 2O 2S:Tb, a green-light scintillator, in the radiography under a neutron + X-ray coexisting field, we can easily separate the neutron image and the X-ray image by simple color-image processing. This technique enables a non-destructive and detailed inspection of industrial products composed both of light elements (water, plastics, etc.) and heavy elements (metals), widening the horizon of new applications.

  7. Improvements in the Image Quality of Neutron Radiograms of NUR Neutron Radiography Facility by Using Several Exposure Techniques

    SciTech Connect

    Zergoug, T.; Nedjar, A.; Mokeddem, M. Y.; Mammou, L.

    2008-03-17

    Since the construction of NUR reactor neutron radiography facility in 1991, only transfer exposure method was used as a non destructive technique. The reason is the excess of gamma rays in the neutron beam. To improve radiation performances of the NR system, a stainless steal hollow conical cylinder is introduced at the bottom of the facility beam port, this filter reduce gamma infiltration through the edges of the NR structure without disturbing neutron beam arriving from the in pool divergent collimator. First results confirm our prediction; a gamma rays diminution and a relatively stable neutron flux at the point object are confirmed, consequently the n/{gamma} ratio reaches a value of 2.104 n/cm{sup 2} mR. Radiograms obtained by using the direct exposure method reveal the feasibility of the technique in the new NR configuration facility, but a weak resolution and contrast of the image is observed. In this paper, we describe a procedure to improve the image quality obtained by direct exposure technique. The process consists of using digitized images obtained by several exposure techniques (NR, gamma radiography or X radiography) for a comparison study and then better image definition can be attained.

  8. Neutron radiography for the characterization of porous structure in degraded building stones

    NASA Astrophysics Data System (ADS)

    Barone, G.; Crupi, V.; Longo, F.; Majolino, D.; Mazzoleni, P.; Raneri, S.; Teixeira, J.; Venuti, V.

    2014-05-01

    As it is well known, the porous structure of stones can change due to different degradation processes that modify the characteristics of freshly quarried blocks. Their knowledge is fundamental for predicting the behavior of stones and the efficacy of conservative treatments. In this context, neutron radiography is a useful tool not only to visualize the structure of porous materials, but also to evaluate the degree of degradation and surface modifications resulting from weathering processes. Furthermore, since thermal neutrons suffer a strong attenuation by hydrogen, this technique is effective in order to investigate the amount of absorbed water in building materials. In the present work, we report a neutron radiography investigation of limestones cropping out in the South-Eastern Sicily and widely used as building stones in Baroque monuments of the Noto Valley. The analyzed samples have been submitted to cyclic salt crystallization that simulate degradation processes acting in exposed stones of buildings. The obtained results demonstrate the interest of neutron radiography to better understand deterioration processes in limestones and to acquire information useful for restoration projects.

  9. High Speed Motion Neutron Radiography Of Dynamic Events

    NASA Astrophysics Data System (ADS)

    Robinson, A. H.; Bossi, R. H.; Barton, J. P.

    1983-03-01

    This paper describes the development of a technique that enables the neutron radiographic analysis of dynamic processes over a period lasting from one to ten milliseconds. The key to the technique is the use of a neutron pulse that is broad enough to span the duration of the brief event of interest and intense enough to permit recording of the results on a high-speed movie film at frame rates up to 10,000 frames/second. A system has been developed which utilizes the pulsing capability of the OSU TRIGA reactor. The system consists of the Oregon State University TRIGA reactor (pulsing to 3000 MW peak power), a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16 mm high speed movie camera. The peak neutron flux incident at the object position is approximately 4 x 1011 n/cm2s with a pulse, full width at half maximum, of 9 ms. The system has been operated in the range of 2000 to 10,000 frames/second and has provided high-speed-motion neutron radiographs for evaluation of the firing cycle of 7.62 mm munition rounds within a steel rifle barrel. The system has also been used to demonstrate the ability to produce neutron radiographic movies of two-phase flow.

  10. Water Calibration Measurements for Neutron Radiography: Application to Water Content Quantification in Porous Media

    SciTech Connect

    Kang, Misun; Bilheux, Hassina Z; Voisin, Sophie; Cheng, Chu-lin; Perfect, Edmund; Horita, Juske; Warren, Jeffrey

    2013-04-01

    Using neutron radiography, the measurement of water thickness was performed using aluminum (Al) water calibration cells at the High Flux Isotope Reactor (HFIR) Cold-Guide (CG) 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA. Calibration of water thickness is an important step to accurately measure water contents in samples of interest. Neutron attenuation by water does not vary linearly with thickness mainly due to beam hardening and scattering effects. Transmission measurements for known water thicknesses in water calibration cells allow proper correction of the underestimation of water content due to these effects. As anticipated, strong scattering effects were observed for water thicknesses greater than 2 mm when the water calibration cells were positioned close to the face of the detector / scintillator (0 and 2.4 cm away, respectively). The water calibration cells were also positioned 24 cm away from the detector face. These measurements resulted in less scattering and this position (designated as the sample position) was used for the subsequent experimental determination of the neutron attenuation coefficient for water. Neutron radiographic images of moist Flint sand in rectangular and cylindrical containers acquired at the sample position were used to demonstrate the applicability of the water calibration. Cumulative changes in the water volumes within the sand columns during monotonic drainage determined by neutron radiography were compared with those recorded by direct reading from a burette connected to a hanging water column. In general, the neutron radiography data showed very good agreement with those obtained volumetrically using the hanging water-column method. These results allow extension of the calibration equation to the quantification of unknown water contents within other samples of porous media.

  11. Water calibration measurements for neutron radiography: Application to water content quantification in porous media

    NASA Astrophysics Data System (ADS)

    Kang, M.; Bilheux, H. Z.; Voisin, S.; Cheng, C. L.; Perfect, E.; Horita, J.; Warren, J. M.

    2013-04-01

    Using neutron radiography, the measurement of water thickness was performed using aluminum (Al) water calibration cells at the High Flux Isotope Reactor (HFIR) Cold-Guide (CG) 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA. Calibration of water thickness is an important step to accurately measure water contents in samples of interest. Neutron attenuation by water does not vary linearly with thickness mainly due to beam hardening and scattering effects. Transmission measurements for known water thicknesses in water calibration cells allow proper correction of the underestimation of water content due to these effects. As anticipated, strong scattering effects were observed for water thicknesses greater than 0.2 cm when the water calibration cells were positioned close to the face of the detector/scintillator (0 and 2.4 cm away, respectively). The water calibration cells were also positioned 24 cm away from the detector face. These measurements resulted in less scattering and this position (designated as the sample position) was used for the subsequent experimental determination of the neutron attenuation coefficient for water. Neutron radiographic images of moist Flint sand in rectangular and cylindrical containers acquired at the sample position were used to demonstrate the applicability of the water calibration. Cumulative changes in the water volumes within the sand columns during monotonic drainage determined by neutron radiography were compared with those recorded by direct reading from a burette connected to a hanging water column. In general, the neutron radiography data showed very good agreement with those obtained volumetrically using the hanging water-column method. These results allow extension of the calibration equation to the quantification of unknown water contents within other samples of porous media.

  12. Measurement of Coolant in a Flat Heat Pipe Using Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Mizuta, Kei; Saito, Yasushi; Goshima, Takashi; Tsutsui, Toshio

    A newly developed flat heat pipe FGHPTM (Morex Kiire Co.) was experimentally investigated by using neutron radiography. The test sample of the FGHP heat spreader was 65 × 65 × 2 mm3 composed of several etched copper plates and pure water was used as the coolant. Neutron radiography was performed at the E-2 port of the Kyoto University Research Reactor (KUR). The coolant distributions in the wick area of the FGHP and its heat transfer characteristics were measured at heating conditions. Experimental results show that the coolant distributions depend slightly on its installation posture and that the liquid thickness in the wick region remains constant with increasing heat input to the FGHP. In addition, it is found that the wick surface does not dry out even in the vertical posture at present experimental conditions.

  13. Neutron capture radiography: a technique for isotopic labelling and analytical imaging with a few stable isotopes.

    PubMed

    Thellier, Michel; Ripoll, Camille

    2006-06-19

    NCR (neutron capture radiography) may be used successfully for the imaging of one of the stable isotopes of a few chemical elements (especially 6Li and 10B, possibly also 14N, 17O, and others) and for labelling experiments using these stable isotopes. Other physical techniques compete with NCR. However, NCR can remain extremely useful in a certain number of cases, because it is usually more easily done and is less expensive than the other techniques.

  14. Optimising visibility for the neutron radiography of titanium and nickel gas turbine components

    NASA Astrophysics Data System (ADS)

    Thornton, John; Arhatari, Benedicta D.; Peele, Andrew G.; Nugent, Keith A.

    2006-11-01

    An analytical expression for the visibility of radiographic images with phase and absorption contrast has been derived. It was used to theoretically optimise the visibility of cracks in titanium and nickel for the case of neutron radiography. The image-to-object distance, object-to-detector distance and the crack depths were varied in the optimisation. The different neutron refractive indices of the titanium and nickel produced qualitative differences in the predicted visibility as a function of the spatial frequencies of the object. Significant visibility from phase contrast was predicted for 50 μm deep cracks in nickel and 200 μm deep cracks in titanium.

  15. Visualization of cavitation phenomena in a Diesel engine fuel injection nozzle by neutron radiography

    NASA Astrophysics Data System (ADS)

    Takenaka, N.; Kadowaki, T.; Kawabata, Y.; Lim, I. C.; Sim, C. M.

    2005-04-01

    Visualization of cavitation phenomena in a Diesel engine fuel injection nozzle was carried out by using neutron radiography system at KUR in Research Reactor Institute in Kyoto University and at HANARO in Korea Atomic Energy Research Institute. A neutron chopper was synchronized to the engine rotation for high shutter speed exposures. A multi-exposure method was applied to obtain a clear image as an ensemble average of the synchronized images. Some images were successfully obtained and suggested new understanding of the cavitation phenomena in a Diesel engine fuel injection nozzle.

  16. A novel approach to determine post mortem interval using neutron radiography

    DOE PAGESBeta

    Bilheux, Hassina Z.; Cekanova, Maria; Vass, Arpad Alexander; Nichols, Trent L.; Bilheux, Jean -Christophe; Donnell, Robert; Finocchiaro, Vincenzo

    2015-03-06

    In this study, neutron radiography (NR) is used non-destructively to measure changes in hydrogen (H) content in decaying tissues as a mean to estimate post-mortem invertal (PMI). After death, tissue undergoes sequential changes consisting of organic and inorganic phase variations, as well as a gradual reduction of tissue water content. H is the primary contributor to NR contrast in biological specimens because (1) it is the most abundant element in biological tissues and (2) its nucleus scatter thermal and cold neutrons more strongly than any other atomic nucleus. These contrast differences can be advantageous in a forensic context to determinemore » small changes in hydrogen concentrations. Dog cadavers were used as a model for human cadavers. Canine tissues and cadavers were exposed to controlled (laboratory settings) and uncontrolled (University of Tennessee Anthropology Research Facility) environmental conditions during putefraction, respectively. Neutron radiographs were supplemented with photographs and histology data to assess the decomposition stage of cadavers. Results demonstrated that the increase in neutron transmission likely corresponded to a decrease in hydrogen content in the tissue, which was correlated with the time of decay of the tissue. Tissues depleted in hydrogen are brighter in the neutron transmission radiographs of skeletal muscles, lung, and bone, under controlled conditions. Over a period of 10 days, changes in neutron transmission through lung and muscle were found to be higher than bone by 8.3%, 7.0 %, and 2.0 %, respectively. Estimation of the PMI was calculated from a natural logarithmic fitting of the NR data. Under controlled conditions, estimation of the PMI was 70% and 63.9 % accurate for bone and lung tissues, while being 1.4% accurate for muscle tissue. All results underestimated the true PMI. In conclusion, neutron radiography can be used for detection of hydrogen changes in decaying tissues to estimate PMI.« less

  17. A novel approach to determine post mortem interval using neutron radiography

    SciTech Connect

    Bilheux, Hassina Z.; Cekanova, Maria; Vass, Arpad Alexander; Nichols, Trent L.; Bilheux, Jean -Christophe; Donnell, Robert; Finocchiaro, Vincenzo

    2015-03-06

    In this study, neutron radiography (NR) is used non-destructively to measure changes in hydrogen (H) content in decaying tissues as a mean to estimate post-mortem invertal (PMI). After death, tissue undergoes sequential changes consisting of organic and inorganic phase variations, as well as a gradual reduction of tissue water content. H is the primary contributor to NR contrast in biological specimens because (1) it is the most abundant element in biological tissues and (2) its nucleus scatter thermal and cold neutrons more strongly than any other atomic nucleus. These contrast differences can be advantageous in a forensic context to determine small changes in hydrogen concentrations. Dog cadavers were used as a model for human cadavers. Canine tissues and cadavers were exposed to controlled (laboratory settings) and uncontrolled (University of Tennessee Anthropology Research Facility) environmental conditions during putefraction, respectively. Neutron radiographs were supplemented with photographs and histology data to assess the decomposition stage of cadavers. Results demonstrated that the increase in neutron transmission likely corresponded to a decrease in hydrogen content in the tissue, which was correlated with the time of decay of the tissue. Tissues depleted in hydrogen are brighter in the neutron transmission radiographs of skeletal muscles, lung, and bone, under controlled conditions. Over a period of 10 days, changes in neutron transmission through lung and muscle were found to be higher than bone by 8.3%, 7.0 %, and 2.0 %, respectively. Estimation of the PMI was calculated from a natural logarithmic fitting of the NR data. Under controlled conditions, estimation of the PMI was 70% and 63.9 % accurate for bone and lung tissues, while being 1.4% accurate for muscle tissue. All results underestimated the true PMI. In conclusion, neutron radiography can be used for detection of hydrogen changes in decaying tissues to estimate PMI.

  18. Archaeometric studies by neutron, x-ray radiography and microCT

    NASA Astrophysics Data System (ADS)

    Latini, R. M.; Bellido, A. V. B.; Vinagre Filho, U. M.; Souza, M. I. S.; Lima, I.; Oliveira, D. F.; Lopes, R. T.

    2013-05-01

    The aim of this study is to investigate manufacturing techniques used in prehistoric Brazilian pottery from Acre state and Araruama, Rio de Janeiro state, Brazil, using Neutron and X-Ray Radiography. For the neutrongraphy different fragments of pottery were submitted to a neutron flux of the order of 105n.cm-2.s-1 for 3 minutes at the Argonauta research reactor of the Instituto de Engenharia Nuclear (IEN)/CNEN. Digital processing techniques using imaging plate were applied to process the image of the selected sample. For the radiography the sample were exposed to an X-Rays in the Feinfocus Model FX100 and the image was obtained by Flat Panel GE IT Model DXR 250V at the Laboratório de Instrumentação Nuclear (LIN) - COPPE/UFRJ. The Neutrongraphy and radiography shows two different manufacturing details: palette and rollers and the microtomography shows cavities in the clay body and different temper applied in the pottery production. The preliminary results shows promising techniques applied for the pottery manufacturing information and as complement for better understanding the ceramics classification and precedence.

  19. A novel approach to determine post mortem interval using neutron radiography.

    PubMed

    Bilheux, Hassina Z; Cekanova, Maria; Vass, Arpad A; Nichols, Trent L; Bilheux, Jean C; Donnell, Robert L; Finochiarro, Vincenzo

    2015-06-01

    One of the most difficult challenges in forensic research is to objectively determine the post-mortem interval (PMI). The accuracy of PMI is critical for determining the timeline of events surrounding a death. Most PMI techniques rely on gross morphological changes of cadavers that are highly sensitive to taphonomic factors. Recent studies have demonstrated that even exhumed individuals exposed to the same environmental conditions with similar PMIs can present different stages of decomposition. After death, tissue undergoes sequential changes consisting of organic and inorganic phase variations, as well as a gradual reduction of tissue water content. Hydrogen (H) is the primary contributor to neutron radiography (NR) contrast in biological specimens because (1) it is the most abundant element in biological tissues and (2) its nucleus scatters thermal and cold neutrons more strongly than any other atomic nucleus. These contrast differences can be advantageous in a forensic context to determine small changes in hydrogen concentrations. Neutron radiography of decaying canine tissues was performed to evaluate the PMI by measuring the changes in H content. In this study, dog cadavers were used as a model for human cadavers. Canine tissues and cadavers were exposed to controlled (laboratory settings, at the University of Tennessee, College of Veterinary Medicine) and uncontrolled (University of Tennessee Anthropology Research Facility) environmental conditions, respectively. Neutron radiographs were supplemented with photographs and histology data to assess the decompositional stages of cadavers. Results demonstrated that the increase in neutron transmission likely corresponded to a decrease in hydrogen content in the tissue, which was correlated with the decay time of the tissue. Tissues depleted in hydrogen were brighter in the neutron transmission radiographs of skeletal muscles, lung, and bone, under controlled conditions. Over a period of 10 days, changes in neutron

  20. New Developments in Proton Radiography at the Los Alamos Neutron Science Center (LANSCE)

    DOE PAGESBeta

    Morris, C. L.; Brown, E. N.; Agee, C.; Bernert, T.; Bourke, M. A. M.; Burkett, M. W.; Buttler, W. T.; Byler, D. D.; Chen, C. F.; Clarke, A. J.; et al

    2015-12-30

    An application of nuclear physics, a facility for using protons for flash radiography, was developed at the Los Alamos Neutron Science Center (LANSCE). Protons have proven far superior to high energy x-rays for flash radiography because of their long mean free path, good position resolution, and low scatter background. Although this facility is primarily used for studying very fast phenomena such as high explosive driven experiments, it is finding increasing application to other fields, such as tomography of static objects, phase changes in materials and the dynamics of chemical reactions. The advantages of protons are discussed, data from some recentmore » experiments will be reviewed and concepts for new techniques are introduced.« less

  1. Dual spectrum neutron radiography: identification of phase transitions between frozen and liquid water.

    PubMed

    Biesdorf, J; Oberholzer, P; Bernauer, F; Kaestner, A; Vontobel, P; Lehmann, E H; Schmidt, T J; Boillat, P

    2014-06-20

    In this Letter, a new approach to distinguish liquid water and ice based on dual spectrum neutron radiography is presented. The distinction is based on arising differences between the cross section of water and ice in the cold energy range. As a significant portion of the energy spectrum of the ICON beam line at Paul Scherrer Institut is in the thermal energy range, no differences can be observed with the entire beam. Introducing a polycrystalline neutron filter (beryllium) inside the beam, neutrons above its cutoff energy are filtered out and the cold energy region is emphasized. Finally, a contrast of about 1.6% is obtained with our imaging setup between liquid water and ice. Based on this measurement concept, the temporal evolution of the aggregate state of water can be investigated without any prior knowledge of its thickness. Using this technique, we could unambiguously prove the production of supercooled water inside fuel cells with a direct measurement method.

  2. Design of neutron beams at the Argonne Continuous Wave Linac (ACWL) for boron neutron capture therapy and neutron radiography

    SciTech Connect

    Zhou, X.L.; McMichael, G.E.

    1994-10-01

    Neutron beams are designed for capture therapy based on p-Li and p-Sc reactions using the Argonne Continuous Wave Linac (ACWL). The p-Li beam will provide a 2.5 {times} 10{sup 9} n/cm{sup 2}s epithermal flux with 7 {times} 10{sup 5} {gamma}/cm{sup 2}s contamination. On a human brain phantom, this beam allows an advantage depth (AD) of 10 cm, an advantage depth dose rate (ADDR) of 78 cGy/min and an advantage ratio (AR) of 3.2. The p-Sc beam offers 5.9 {times} 10{sup 7} n/cm{sup 2}s and a dose performance of AD = 8 cm and AR = 3.5, suggesting the potential of near-threshold (p,n) reactions such as the p-Li reaction at E{sub p} = 1.92 MeV. A thermal radiography beam could also be obtained from ACWL.

  3. Visualization of Bubble Behavior in a Packed Bed of Spheres Using Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Ito, Daisuke; Saito, Yasushi

    The present paper describes gas-liquid two-phase flow measurements in a packed bed of spheres using neutron radiography. Porous debris formed during a severe accident of a nuclear reactor should be cooled by a coolant and the cooling characteristics are dominated by two-phase flow behavior in the debris bed at the initial stage of the accident. Therefore, experimental database of the two-phase flow in the porous media has been required for safety analysis of the reactor. However, it is difficult to observe the flow structure, for example, void fraction distribution in such complex flow channel. In this study, the local void fraction in a packed bed which simulates the debris bed was measured by high frame-rate neutron radiography. Experiments were performed in air-water two-phase flow in a vertical pipe. Alumina spheres with 5 mm in diameter were packed randomly in the pipe. The bubble behavior between the spheres was investigated by using the void fraction distributions estimated from the neutron radiographs. Although it was difficult to track the small bubbles in the packed bed, the move of the large bubble could be found roughly from the distribution. In addition, the fluctuation of the void fraction was compared with that of the pressure drop in the test section. From these results, the possibility of the gas velocity estimation was shown.

  4. Unsaturated flow patterns observed in mine soils with embedded porous fragments using neutron radiography

    NASA Astrophysics Data System (ADS)

    Badorreck, A.; Gerke, H. H.; Vontobel, P.

    2009-04-01

    Mine soils represent a typical dual-porosity medium characterized by porous fragments (e.g., lignitic or clayey clods) that are embedded in a coarser-textured sand-dust matrix. Effects of heterogeneously-distributed embedded fragments of various sizes and shapes on flow are largely unknown. The objective of this study is to identify water flow paths using neutron radiography and imaging techniques. Experiments were carried out at the Swiss Spallation Neutron Source SINQ (PSI, Villigen). Neutron radiography (at the NEUTRA instrument) was used to observe unsaturated water movement under different flow conditions. For 2D-steady-state flow experiments, we used a double-membrane setup to infiltrate water (H2O) in slap-type undisturbed soil samples. Before the experiments, most of the water that was initially present in the samples has been exchanged by deuterium oxide (D2O). The 2D radiography series' show the dynamics of the spatial changes in water contents during the unsaturated flow process at defined matric potentials. In addition, we conducted multistep in- and outflow experiments to observe the 3D spatial distribution of the water content during the stationary phases at different steps of imposed pressure heads. Two minature tensiometers, one in the sandy matrix and the other in lignitic fragments, monitored the equilibration of soil water matric potentials in the dual-porosity medium. Our observations basically confirm that flow patterns are strongly related to the local-scale structures and that a more continuous pore region exists in the vicinity of fragments for the imposed moisture conditions. This continuous pore domain allows for preferential flow within a relatively small fraction of the otherwise coarse-textured porous medium. The geometries and hydraulic properties of the porous fragments are additionally modifying the flow patterns.

  5. Development of neutron radiography facility for boiling two-phase flow experiment in Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Sekimoto, S.; Hino, M.; Kawabata, Y.

    2011-09-01

    To visualize boiling two-phase flow at high heat flux by using neutron radiography, a new neutron radiography facility was developed in the B-4 beam hole of KUR. The B-4 beam hole is equipped with a supermirror neutron guide tube with a characteristic wavelength of 1.2 Å, whose geometrical parameters of the guide tube are: 11.7 m total length and 10 mm wide ×74 mm high beam cross-section. The total neutron flux obtained from the KUR supermirror guide tube is about 5×10 7 n/cm 2 s with a nominal thermal output of 5 MW of KUR, which is about 100 times what is obtainable with the conventional KUR neutron radiography facility (E-2 beam hole). In this study a new imaging device, an electric power supply (1200 A, 20 V), and a thermal hydraulic loop were installed. The neutron source, the beam tube, and the radiography rooms are described in detail and the preliminary images obtained at the developed facility are shown.

  6. Neutron collimator for neutron radiography applications at tangential port of the TRIGA RC-1 reactor

    NASA Astrophysics Data System (ADS)

    Rosa, R.; Andreoli, F.; Mattoni, M.; Palomba, M.

    2009-06-01

    At the ENEA TRIGA research reactor (Casaccia Research Center, Rome) a new neutron collimator has been designed and installed at the neutron tangential channel. This collimator, that is part of a neutron/X-ray facility for NDT analysis, was experimentally characterized and optimized in terms of thermal neutron fluence rate, spatial/energetic distribution, photon air KERMA and effective beam diameter. This paper shows the methodologies and the results of the experimental analysis that were carried out.

  7. Identification of microorganisms for the analysis of images obtained by neutron radiography

    NASA Astrophysics Data System (ADS)

    Lopes, J. D. R.; Crispim, V. R.; Lage, C.

    2001-06-01

    The main difficulty in identifying infectious microorganisms is the time required to obtain a reliable result, a minimum of 72 h. We propose a reduction to about 5 h through the technique of neutron radiography. Samples containing the bacillus Escherichia coli and the cocci Staphylococcus epidermidis were incubated with B 10, layered on SSNTD (CR-39) surface and irradiated in the J-9 channel from the Argonauta Reactor (IEN/CNEN) with a flux of thermal neutrons at a rate of 2.2×10 5 n/cm 2 s. Images were observed in an optical microscope after exposure of the plates to chemical development of the latent alpha-tracks. Analysis of the images revealed morphological differences between the species, conferring the technique the perspective to use in microbial diagnosis.

  8. Fast-neutron/gamma-ray radiography scanner for the detection of contraband in air cargo containers

    NASA Astrophysics Data System (ADS)

    Eberhardt, J.; Liu, Y.; Rainey, S.; Roach, G.; Sowerby, B.; Stevens, R.; Tickner, J.

    2006-05-01

    There is a worldwide need for efficient inspection of cargo containers at airports, seaports and road border crossings. The main objectives are the detection of contraband such as illicit drugs, explosives and weapons. Due to the large volume of cargo passing through Australia's airports every day, it is critical that any scanning system should be capable of working on unpacked or consolidated cargo, taking at most 1-2 minutes per container. CSIRO has developed a fast-neutron/gamma-ray radiography (FNGR) method for the rapid screening of air freight. By combining radiographs obtained using 14 MeV neutrons and 60Co gamma-rays, high resolution images showing both density and material composition are obtained. A near full-scale prototype scanner has been successfully tested in the laboratory. With the support of the Australian Customs Service, a full-scale scanner has recently been installed and commissioned at Brisbane International Airport.

  9. Neutron radiography of a static density gradient of 3He gas at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Wichmann, G.; Antognini, A.; Eggenberger, A.; Kirch, K.; Piegsa, F. M.; Soler, U.; Stahn, J.; Taqqu, D.

    2016-04-01

    We demonstrate a stationary helium gas density gradient which is needed for a proposed novel low-energy μ+ beam line. In a closed system with constant pressure the corresponding density gradient is only a function of the temperature. In a neutron radiography experiment two gas cells with different geometries were filled with 3He gas at constant pressures of about 10 mbar. Temperatures in the range from 6 K to 40 K were applied and density distributions with a maximum to minimum density ratio of larger than 3 were realized. The distribution was investigated employing the strongly neutron absorbing isotope 3He. A simple one-dimensional approach derived from Fourier's law describes the obtained gas density with a deviation < 2 %.

  10. Design of Real-time Neutron Radiography at China Advanced Research Reactor

    NASA Astrophysics Data System (ADS)

    He, Linfeng; Han, Songbai; Wang, Hongli; Hao, Lijie; Wu, Meimei; Wei, Guohai; Wang, Yu; Liu, Yuntao; Sun, Kai; Chen, Dongfeng

    A real-time detector system for neutron radiography based on CMOS camera has been designed for the thermal neutron imaging facility under construction at China Advanced Research Reactor (CARR). This system is equipped with a new scientific CMOS camera with 5.5 million pixels and speed up to 100 fps at full frame. The readout noise is below 2.4 e/pixel. It is capable of providing images with much higher resolution and sensitivity at high frame rate. With optimized optical design and custom-built lens, the capture of quantitative information may be greatly enhanced. The maximum photon received by detector is calculated to be 2.1 × 103/pixel, while the camera resolution is 0.2 mm at 30 fps according to the expected flux (5 × 107 n/cm2/s) at the sample position.

  11. An on-line video image processing system for real-time neutron radiography

    NASA Astrophysics Data System (ADS)

    Fujine, Shigenori; Yoneda, Kenji; Kanda, Keiji

    1983-09-01

    The neutron radiography system installed at the E-2 experimental hole of the KUR (Kyoto University Reactor) has been used for some NDT applications in the nuclear field. The on-line video image processing system of this facility is introduced in this paper. A 0.5 mm resolution in images was obtained by using a super high quality TV camera developed for X-radiography viewing a NE-426 neutron-sensitive scintillator. The image of the Ne-426 on a CRT can be observed directly and visually, thus many test samples can be sequentially observed when necessary for industrial purposes. The video image signals from the TV camera are digitized, with a 33 ms delay, through a video A/D converter (ADC) and can be stored in the image bufer (32KB DRAM) of a microcomputer (Z-80) system. The digitized pictures are taken with 16 levels of gray scale and resolved to 240×256 picture elements (pixels) on a monochrome CRT, with the capability also to display 16 distinct colors on a RGB video display. The direct image of this system could be satisfactory for penetrating the side plates to test MTR type reactor fuels and for the investigation of moving objects.

  12. Non-destructive investigation of a time capsule using neutron radiography and X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    MacDonald, B. L.; Vanderstelt, J.; O'Meara, J.; McNeill, F. E.

    2016-01-01

    Non-destructive analytical techniques are becoming increasingly important for the study of objects of cultural heritage interest. This study applied two techniques: X-ray fluorescence and neutron radiography, for the investigation of a capped, tubular metal object recovered from an urban construction site in Gore Park, Hamilton, Canada. The site is an urban park containing a World War I commemorative monument that underwent renovation and relocation. Historical documentation suggested that the object buried underneath the monument was a time capsule containing a paper document listing the names of 1800 Canadians who died during WWI. The purpose of this study was to assess the condition of the object, and to verify if it was what the historical records purported. XRF analysis was used to characterize the elemental composition of the metal artifact, while neutron radiography revealed that its contents were congruent with historical records and remained intact after being interred for 91 years. Results of this study demonstrate the value of non-destructive techniques for the analysis and preservation of cultural heritage.

  13. Distribution of root exudates and mucilage in the rhizosphere: combining 14C imaging with neutron radiography

    NASA Astrophysics Data System (ADS)

    Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov

    2015-04-01

    Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and 14C imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later 14C distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, 14C activity on the image was related to the absolute 14C activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (14C imaging), we were able to differentiate between mucilage and root

  14. The Development of Neutron Radiography and Tomography on a SLOWPOKE-2 Reactor

    NASA Astrophysics Data System (ADS)

    Bennett, L. G. I.; Lewis, W. J.; Hungler, P. C.

    Development of neutron radiography at the Royal Military College of Canada (RMC) started by trying to interest the Royal Canadian Air Force (RCAF) in this new non-destructive testing (NDT) technique. A Californium-252 based device was ordered and then installed at RMC for development of applicable techniques for aircraft by the first author. A second and transportable device was then designed, modified and used in trials at RCAF Bases and other locations for one year. This activity was the only foreign loan of the U.S. Californium Loan Program. Around this time, SLOWPOKE-2 reactors were being installed at four Canadian universities, while a new science and engineering building was being built at RMC. A reactor pool was incorporated and efforts to procure a reactor succeeded a decade later with a SLOWPOKE-2 reactor being installed at RMC. The only modification by the vendor for RMC was a thermal column replacing an irradiation site inside the reactor container for a later installation of a neutron beam tube (NBT). Development of a working NBT took several years, starting with the second author. A demonstration of the actual worth of neutron radiography took place with a CF-18 Hornet aircraft being neutron and X-radiographed at McClellan Air Force Base, Sacramento, CA. This inspection was followed by one of the rudders that had indications of water ingress being radiographed successfully at RMC just after the NBT became functional. The next step was to develop a neutron radioscopy system (NRS), initially employing film and then digital imaging, and is in use today for all flight control surfaces (FCS). With the third author, a technique capable of removing water from affected FCS was developed at RMC. Heating equipment and a vacuum system were utilized to carefully remove the water. This technique was proven using a sequence of near real time neutron images obtained during the drying process. The results of the drying process were correlated with a relative humidity

  15. Multiple pixel-scale soil water retention curves quantified by neutron radiography

    NASA Astrophysics Data System (ADS)

    Kang, M.; Perfect, E.; Cheng, C. L.; Bilheux, H. Z.; Lee, J.; Horita, J.; Warren, J. M.

    2014-03-01

    The soil water retention function is needed for modeling multiphase flow in porous media. Traditional techniques for measuring the soil water retention function, such as the hanging water column or pressure cell methods, yield average water retention data which have to be modeled using inverse procedures to extract relevant point parameters. In this study, we have developed a technique for directly measuring multiple point (pixel-scale) water retention curves for a repacked sand material using 2-D neutron radiography. Neutron radiographic images were obtained under quasi-equilibrium conditions at nine imposed basal matric potentials during monotonic drying of Flint sand at the High Flux Isotope Reactor (HFIR) Cold Guide (CG) 1D beamline at Oak Ridge National Laboratory. All of the images were normalized with respect to an image of the oven dry sand column. Volumetric water contents were computed on a pixel by pixel basis using an empirical calibration equation after taking into account beam hardening and geometric corrections. Corresponding matric potentials were calculated from the imposed basal matric potential and pixel elevations. Volumetric water content and matric potential data pairs corresponding to 120 selected pixels were used to construct 120 point water retention curves. Each curve was fitted to the Brooks and Corey equation using segmented non-linear regression in SAS. A 98.5% convergence rate was achieved resulting in 115 estimates of the four Brooks and Corey parameters. A single Brooks and Corey point water retention function was constructed for Flint sand using the median values of these parameter estimates. This curve corresponded closely with the point Brooks and Corey function inversely extracted from the average water retention data using TrueCell. Forward numerical simulations performed using HYDRUS 1-D showed that the cumulative outflows predicted using the point Brooks and Corey functions from both the direct (neutron radiography) and

  16. Design of the Testing Set-up for a Nuclear Fuel Rod by Neutron Radiography at CARR

    NASA Astrophysics Data System (ADS)

    Wei, Guohai; Han, Songbai; Wang, Hongli; Hao, Lijie; Wu, Meimei; He, Linfeng; Wang, Yu; Liu, Yuntao; Sun, Kai; Chen, Dongfeng

    In this paper, an experimental set-up dedicated to non-destructively test a 15cm-long Pressurized Water Reactor (PWR) nuclear fuel rod by neutron radiography (NR) is described. It consists of three parts: transport container, imaging block and steel support. The design of the transport container was optimized with Monte-Carlo Simulation by the MCNP code. The material for the shell of the transport container was chosen to be lead with the thickness of 13 cm. Also, the mechanical devices were designed to control fuel rod movement inside the container. The imaging block was designed as the exposure platform, with three openings for the neutron beam, neutron converter foil, and specimen. Development and application of this experimental set-up will help gain much experience for investigating the actual irradiated fuel rod by neutron radiography at CARR in the future.

  17. Fresh-Core Reload of the Neutron Radiography (NRAD) Reactor with Uranium(20)-Erbium-Zirconium-Hydride Fuel

    SciTech Connect

    John D. Bess; Thomas L. Maddock; Margaret A. Marshall; Leland M. Montierth

    2014-03-01

    The neutron radiography (NRAD) reactor is a 250 kW TRIGA® (Training, Research, Isotopes, General Atomics) Mark II , tank-type research reactor currently located in the basement, below the main hot cell, of the Hot Fuel Examination Facility (HFEF) at the Idaho National Laboratory (INL). It is equipped with two beam tubes with separate radiography stations for the performance of neutron radiography irradiation on small test components. The 60-fuel-element operational core configuration of the NRAD LEU TRIGA reactor has been evaluated as an acceptable benchmark experiment. The initial critical configuration developed during the fuel loading process, which contains only 56 fuel elements, has not been evaluated as it is very similar to the evaluated core configuration. The benchmark eigenvalue is 1.0012 ± 0.0029. Calculated eigenvalues differ significantly (~±1%) from the benchmark eigenvalue and have demonstrated sensitivity to the thermal scattering treatment of hydrogen in the U-Er-Zr-H fuel.

  18. Fresh-Core Reload of the Neutron Radiography (NRAD) Reactor with Uranium(20)-Erbium-Zirconium-Hydride Fuel

    SciTech Connect

    John D. Bess; Thomas L. Maddock; Margaret A. Marshall; Leland M. Montierth

    2011-03-01

    The neutron radiography (NRAD) reactor is a 250 kW TRIGA® (Training, Research, Isotopes, General Atomics) Mark II , tank-type research reactor currently located in the basement, below the main hot cell, of the Hot Fuel Examination Facility (HFEF) at the Idaho National Laboratory (INL). It is equipped with two beam tubes with separate radiography stations for the performance of neutron radiography irradiation on small test components. The 60-fuel-element operational core configuration of the NRAD LEU TRIGA reactor has been evaluated as an acceptable benchmark experiment. The initial critical configuration developed during the fuel loading process, which contains only 56 fuel elements, has not been evaluated as it is very similar to the evaluated core configuration. The benchmark eigenvalue is 1.0012 ± 0.0029. Calculated eigenvalues differ significantly (~±1%) from the benchmark eigenvalue and have demonstrated sensitivity to the thermal scattering treatment of hydrogen in the U-Er-Zr-H fuel.

  19. Fresh-Core Reload of the Neutron Radiography (NRAD) Reactor with Uranium(20)-Erbium-Zirconium-Hydride Fuel

    SciTech Connect

    John D. Bess; Thomas L. Maddock; Margaret A. Marshall; Leland M. Montierth

    2013-03-01

    The neutron radiography (NRAD) reactor is a 250 kW TRIGA® (Training, Research, Isotopes, General Atomics) Mark II , tank-type research reactor currently located in the basement, below the main hot cell, of the Hot Fuel Examination Facility (HFEF) at the Idaho National Laboratory (INL). It is equipped with two beam tubes with separate radiography stations for the performance of neutron radiography irradiation on small test components. The initial critical configuration developed during the fuel loading process, which contains only 56 fuel elements, has been evaluated as an acceptable benchmark experiment. The 60-fuel-element operational core configuration of the NRAD LEU TRIGA reactor has also been evaluated as an acceptable benchmark experiment. Calculated eigenvalues differ significantly (~±1%) from the benchmark eigenvalue and have demonstrated sensitivity to the thermal scattering treatment of hydrogen in the U-Er-Zr-H fuel.

  20. The new neutron radiography/tomography/imaging station DINGO at OPAL

    NASA Astrophysics Data System (ADS)

    Garbe, U.; Randall, T.; Hughes, C.

    2011-09-01

    A new neutron imaging instrument will be built to support the area of neutron imaging research (neutron radiography/tomography) at ANSTO. The instrument will be designed for an international user community and for routine quality control for defence, industrial, mining, space and aircraft applications. It will also be a useful tool for assessing oil and water flow in sedimentary rock reservoirs (like the North West Shelf), assessing water damage in aircraft components, and the study of hydrogen distribution and cracking in steel. The instrument is planned to be completed by the end of June 2013 and is currently in the design stage. The usable neutron flux is mainly determined by the neutron source, but it also depends on the instrument position and the resolution. The designated instrument position for DINGO is the beam port HB-2 in the reactor hall. The estimated flux for an L/ D of approximately 250 at HB-2 is calculated by Mcstas simulation in a range of 4.75×10 7 n/cm 2 s, which is in the same range of other facilities like ANSTARES (FRM II; Schillinger et al., 2004 [1]) or BT2 (NIST; Hussey et al., 2005 [2]). A special feature of DINGO is the in-pile collimator place in front of the main shutter at HB-2. The collimator offers two pinholes with a possible L/ D of 250 and 1000. A secondary collimator will separate the two beams and block one. The whole instrument will operate in two different positions, one for high resolution and the other for high speed.

  1. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    DOEpatents

    Smith, D.L.; Ikeda, Yujiro; Uno, Yoshitomo

    1996-11-05

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the {sup 16}O(n,p){sup 16}N reaction using {sup 14}N-MeV neutrons produced at the neutron source via the {sup 3}H(d,n){sup 4}He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second {sup 16}N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1--2 minutes. 15 figs.

  2. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    DOEpatents

    Smith, Donald L.; Ikeda, Yujiro; Uno, Yoshitomo

    1996-01-01

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the .sup.16 O(n,p).sup.16 N reaction using .sup.14 -MeV neutrons produced at the neutron source via the .sup.3 H(d,n).sup.4 He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second .sup.16 N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1-2 minutes.

  3. Visualization of water penetration in cementitious materials with superabsorbent polymers by means of neutron radiography

    SciTech Connect

    Snoeck, D.; Steuperaert, S.; Van Tittelboom, K.; Dubruel, P.; De Belie, N.

    2012-08-15

    Concrete cracks due to its low tensile strength. As both harmful gases and fluids may enter the concrete by migrating into cracks, the durability is endangered. The service life decreases, repair costs rise and buildings could structurally decline. In the current research, crack sealing is enhanced by the use of superabsorbent polymers (SAP). When cracking occurs, SAP particles are exposed to the humid environment and swell, sealing the crack. By means of neutron radiography, the moisture distribution is studied during capillary absorption and water permeability tests. Capillary absorption in a crack and water permeability through a crack are reduced in specimens containing SAP particles. SAP particles are able to seal the crack, thus allowing a recovery of the water-tightness of the structure. The total uptake of potentially harmful substances hereby lowers, leading to an enhanced long-term durability and lower maintenance costs.

  4. In situ visualization of the electrolyte solvent filling process by neutron radiography

    NASA Astrophysics Data System (ADS)

    Knoche, Thomas; Zinth, Veronika; Schulz, Michael; Schnell, Joscha; Gilles, Ralph; Reinhart, Gunther

    2016-11-01

    In the manufacturing of Li-ion battery cells, filling with electrolyte liquid is a crucial step in terms of product quality and cost. To gain insight into the process phenomena, a non-destructive imaging method is presented. It is shown that the spreading of electrolyte liquid within the cell during filling and wetting can be visualized by neutron radiography. The experiment allows for the first time to visualize the soaking behaviour of electrolyte liquid in battery cells. The influence of the process parameters on the wetting behaviour is studied and flow paths of the liquid are identified. The electrolyte intake into the cell stack is discussed with two different analytical approaches. Based on the experimental data, the production process can be optimized, leading to stable cell performance and cost reduction due to faster processes and lower scrap rates.

  5. In-situ investigation water distribution in polymer electrolyte fuel cell using neutron radiography

    SciTech Connect

    Mishler, Jeffrey H; Mukundan, Rangachary; Borup, Rodney L; Wang, Eunkyoung Y; Jacobson, David L

    2010-01-01

    This paper investigates the water content within operating polymer electrolyte membrane (PEM) fuel cells using neutron radiography. We consider fuel cells with various PTFE loadings in their gas diffusion layers (GDL) and microporous layers (MPL), and examine the impacts of MPL/GDL properties on the liquid water behavior and fuel cell performance. Fuel cells are tested at both dry and fully hydrated conditions with different serpentine flow fields. Water contents in the projected areas of channel and land regions are probed. The fuel cell may be subject to more flooding at low current-density operation. Both MPL and GDL wetting properties have substantial impacts on the water content in fuel cell. Cell performance also varies on different scenarios of the MPL/GDL wetting properties. A quad-serpentine channel flow field exhibits higher water content without remarkable change in performance at low current densities. Liquid water profile along the channel is presented and on-set clearly indicated.

  6. Evaluation of liquid behavior in a Variable Conductance Heat Pipe by neutron radiography

    NASA Astrophysics Data System (ADS)

    Sugimoto, K.; Asano, H.; Murakawa, H.; Takenaka, N.; Nagayasu, T.; Ipposhi, S.

    2011-09-01

    A Variable Conductance Heat Pipe (VCHP) is used as a cooling device for electrical equipments. The condensation area is passively controlled by the non-condensable gas volume in the VCHP depending on the heat load. The VCHP has often a bent pipe between the evaporation and condensation area. The heat pipe performance depends much on the bent pipe shape and configuration because a liquid plug is formed in the bent pipe and disturbs the refrigerant circulation. However, the mechanism has not been clarified well. The neutron radiography system at the JRR-3 in Japan Atomic Energy Agency (JAEA) was used to visualize the refrigerant behavior in the VCHP. Effects of the thin plate inserted in the pipe, refrigerant filling ratios and heat pipe configuration were examined on the heat pipe performance. The liquid plug was formed at the bend and caused to decrease the performance. It was confirmed that the thin plate insert was effective to disturb the liquid plug formation.

  7. Documented Safety Analysis Addendum for the Neutron Radiography Reactor Facility Core Conversion

    SciTech Connect

    Boyd D. Christensen

    2009-05-01

    The Neutron Radiography Reactor Facility (NRAD) is a Training, Research, Isotope Production, General Atomics (TRIGA) reactor which was installed in the Idaho National Laboratory (INL) Hot Fuels Examination Facility (HFEF) at the Materials and Fuels Complex (MFC) in the mid 1970s. The facility provides researchers the capability to examine both irradiated and non-irradiated materials in support of reactor fuel and components programs through non-destructive neutron radiography examination. The facility has been used in the past as one facet of a suite of reactor fuels and component examination facilities available to researchers at the INL and throughout the DOE complex. The facility has also served various commercial research activities in addition to the DOE research and development support. The reactor was initially constructed using Fuel Lifetime Improvement Program (FLIP)- type highly enriched uranium (HEU) fuel obtained from the dismantled Puerto Rico Nuclear Center (PRNC) reactor. In accordance with international non-proliferation agreements, the NRAD core will be converted to a low enriched uranium (LEU) fuel and will continue to utilize the PRNC control rods, control rod drives, startup source, and instrument console as was previously used with the HEU core. The existing NRAD Safety Analysis Report (SAR) was created and maintained in the preferred format of the day, combining sections of both DOE-STD-3009 and Nuclear Regulatory Commission Regulatory Guide 1.70. An addendum was developed to cover the refueling and reactor operation with the LEU core. This addendum follows the existing SAR format combining required formats from both the DOE and NRC. This paper discusses the project to successfully write a compliant and approved addendum to the existing safety basis documents.

  8. Hysteresis of Soil Point Water Retention Functions Determined by Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Perfect, E.; Kang, M.; Bilheux, H.; Willis, K. J.; Horita, J.; Warren, J.; Cheng, C.

    2010-12-01

    Soil point water retention functions are needed for modeling flow and transport in partially-saturated porous media. Such functions are usually determined by inverse modeling of average water retention data measured experimentally on columns of finite length. However, the resulting functions are subject to the appropriateness of the chosen model, as well as the initial and boundary condition assumptions employed. Soil point water retention functions are rarely measured directly and when they are the focus is invariably on the main drying branch. Previous direct measurement methods include time domain reflectometry and gamma beam attenuation. Here we report direct measurements of the main wetting and drying branches of the point water retention function using neutron radiography. The measurements were performed on a coarse sand (Flint #13) packed into 2.6 cm diameter x 4 cm long aluminum cylinders at the NIST BT-2 (50 μm resolution) and ORNL-HFIR CG1D (70 μm resolution) imaging beamlines. The sand columns were saturated with water and then drained and rewetted under quasi-equilibrium conditions using a hanging water column setup. 2048 x 2048 pixel images of the transmitted flux of neutrons through the column were acquired at each imposed suction (~10-15 suction values per experiment). Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert’s law in conjunction with beam hardening and geometric corrections. The pixel rows were averaged and combined with information on the known distribution of suctions within the column to give 2048 point drying and wetting functions for each experiment. The point functions exhibited pronounced hysteresis and varied with column height, possibly due to differences in porosity caused by the packing procedure employed. Predicted point functions, extracted from the hanging water column volumetric data using the TrueCell inverse modeling procedure, showed very good agreement with the range of point

  9. Manufacturing techniques studies of ceramics by neutron and γ-ray radiography

    SciTech Connect

    Latini, R. M.; Bellido, A. V. B.; Souza, M. I. S.; Almeida, G. L.

    2014-11-11

    In this study, the aim was to evaluate capabilities and constraints of radiographic imagery using thermal neutrons and gamma-rays as tools to identify the type of technique employed in ceramics manufacturing especially that used in prehistoric Brazilian pottery from Acre state. For this purpose, radiographic images of test objects made with clay of this region using both techniques - palette and rollers - have been acquired with a system comprised of a source of gamma-rays or thermal neutrons and a corresponding X-ray or neutron-sensitive Imaging Plate as detector. For the neutrongraphy samples were exposed to a thermal neutron flux of order of 10{sup 5}n.cm{sup −2}.s{sup −1} for 3 minutes at main port of Argonauta research reactor of the Instituto de Engenharia Nuclear - IEN/CNEN. The radiographic images using γ-rays from {sup 165}Dy (95 keV) and {sup 198}Au (412 keV) both produced at this reactor, have been acquired under an exposure time of a couple of hours. After acquisition, images have undergone a treatment to improve their quality through enhancement of their contrast, a procedure involving corrections of the beam divergence, sample shape and averaging of the attenuation map profile. Preliminary results show that difference between manufacturing techniques is better identified by radiography using low energy γ-rays from {sup 165}Dy rather than neutrongraphy or γ-rays from {sup 198}Au. Nevertheless, disregarding the kind of employed radiation, it should be stressed that feasibility to apply the technique is tightly tied to homogeneity of the clay itself and tempers due to their different attenuation.

  10. Manufacturing techniques studies of ceramics by neutron and γ-ray radiography

    NASA Astrophysics Data System (ADS)

    Latini, R. M.; Souza, M. I. S.; Almeida, G. L.; Bellido, A. V. B.

    2014-11-01

    In this study, the aim was to evaluate capabilities and constraints of radiographic imagery using thermal neutrons and gamma-rays as tools to identify the type of technique employed in ceramics manufacturing especially that used in prehistoric Brazilian pottery from Acre state. For this purpose, radiographic images of test objects made with clay of this region using both techniques - palette and rollers - have been acquired with a system comprised of a source of gamma-rays or thermal neutrons and a corresponding X-ray or neutron-sensitive Imaging Plate as detector. For the neutrongraphy samples were exposed to a thermal neutron flux of order of 105n.cm-2.s-1 for 3 minutes at main port of Argonauta research reactor of the Instituto de Engenharia Nuclear - IEN/CNEN. The radiographic images using γ-rays from 165Dy (95 keV) and 198Au (412 keV) both produced at this reactor, have been acquired under an exposure time of a couple of hours. After acquisition, images have undergone a treatment to improve their quality through enhancement of their contrast, a procedure involving corrections of the beam divergence, sample shape and averaging of the attenuation map profile. Preliminary results show that difference between manufacturing techniques is better identified by radiography using low energy γ-rays from 165Dy rather than neutrongraphy or γ-rays from 198Au . Nevertheless, disregarding the kind of employed radiation, it should be stressed that feasibility to apply the technique is tightly tied to homogeneity of the clay itself and tempers due to their different attenuation.

  11. Feasibility of using neutron radiography to inspect the Space Shuttle solid rocket booster aft skirt, forward skirt and frustum. Part 1: Summary report

    NASA Technical Reports Server (NTRS)

    Barton, J. P.; Bader, J. W.; Brenizer, J. S.; Hosticka, B.

    1992-01-01

    The space shuttle's solid rocket boosters (SRB) include components made primarily of aluminum that are parachuted back for retrieval from the ocean and refurbished for repeated usage. Nondestructive inspection methods used on these aging parts to reduce the risk of unforeseen problems include x-ray, ultrasonics, and eddy current. Neutron radiography tests on segments of an SRB component show that entrapped moisture and naturally occurring aluminum corrosion can be revealed by neutron radiography even if present in only small amounts. Voids in sealant can also be evaluated. Three alternatives are suggested to follow-up this study: (1) take an SRB component to an existing neutron radiography system; (2) take an existing mobile neutron radiography system to the NASA site; or (3) plan a dedicated system custom designed for NASA applications.

  12. Neutron radiography for the study of water uptake in painting canvases and preparation layers

    NASA Astrophysics Data System (ADS)

    Boon, J. J.; Hendrickx, R.; Eijkel, G.; Cerjak, I.; Kaestner, A.; Ferreira, E. S. B.

    2015-11-01

    Easel paintings on canvas are subjected to alteration mechanisms triggered or accelerated by moisture. For the study of the spatial distribution and kinetics of such interactions, a moisture exposure chamber was designed and built to perform neutron radiography experiments. Multilayered sized and primed canvas samples were prepared for time-resolved experiments in the ICON cold neutron beamline. The first results show that the set-up gives a good contrast and sufficient resolution to visualise the water uptake in the layers of canvas, size and priming. The results allow, for the first time, real-time visualisation of the interaction of water vapour with such layered systems. This offers important new opportunities for relevant, spatially and time-resolved material behaviour studies and opens the way towards numerical modelling of the process. These first results show that cellulose fibres and glue sizing have a much stronger water uptake than the chalk-glue ground. Additionally, it shows that the uptake rate is not uniform throughout the thickness of the sized canvas. With prolonged moisture exposure, a higher amount of water is accumulating at the lower edge of the canvas weave suggesting a decrease in permeability in the sized canvas with increased water content.

  13. Evaluation of Neutron Radiography Reactor LEU-Core Start-Up Measurements

    SciTech Connect

    Bess, John D.; Maddock, Thomas L.; Smolinski, Andrew T.; Marshall, Margaret A.

    2014-11-04

    Benchmark models were developed to evaluate the cold-critical start-up measurements performed during the fresh core reload of the Neutron Radiography (NRAD) reactor with Low Enriched Uranium (LEU) fuel. Experiments include criticality, control-rod worth measurements, shutdown margin, and excess reactivity for four core loadings with 56, 60, 62, and 64 fuel elements. The worth of four graphite reflector block assemblies and an empty dry tube used for experiment irradiations were also measured and evaluated for the 60-fuel-element core configuration. Dominant uncertainties in the experimental keff come from uncertainties in the manganese content and impurities in the stainless steel fuel cladding as well as the 236U and erbium poison content in the fuel matrix. Calculations with MCNP5 and ENDF/B-VII.0 neutron nuclear data are approximately 1.4% (9σ) greater than the benchmark model eigenvalues, which is commonly seen in Monte Carlo simulations of other TRIGA reactors. Simulations of the worth measurements are within the 2σ uncertainty for most of the benchmark experiment worth values. The complete benchmark evaluation details are available in the 2014 edition of the International Handbook of Evaluated Reactor Physics Benchmark Experiments.

  14. Evaluation of Neutron Radiography Reactor LEU-Core Start-Up Measurements

    DOE PAGESBeta

    Bess, John D.; Maddock, Thomas L.; Smolinski, Andrew T.; Marshall, Margaret A.

    2014-11-04

    Benchmark models were developed to evaluate the cold-critical start-up measurements performed during the fresh core reload of the Neutron Radiography (NRAD) reactor with Low Enriched Uranium (LEU) fuel. Experiments include criticality, control-rod worth measurements, shutdown margin, and excess reactivity for four core loadings with 56, 60, 62, and 64 fuel elements. The worth of four graphite reflector block assemblies and an empty dry tube used for experiment irradiations were also measured and evaluated for the 60-fuel-element core configuration. Dominant uncertainties in the experimental keff come from uncertainties in the manganese content and impurities in the stainless steel fuel cladding asmore » well as the 236U and erbium poison content in the fuel matrix. Calculations with MCNP5 and ENDF/B-VII.0 neutron nuclear data are approximately 1.4% (9σ) greater than the benchmark model eigenvalues, which is commonly seen in Monte Carlo simulations of other TRIGA reactors. Simulations of the worth measurements are within the 2σ uncertainty for most of the benchmark experiment worth values. The complete benchmark evaluation details are available in the 2014 edition of the International Handbook of Evaluated Reactor Physics Benchmark Experiments.« less

  15. Detailed analyses of dynamic and static errors in neutron radiography testing

    SciTech Connect

    Joo, H.; Glickstein, S.S.

    1999-01-01

    Neutron radiography systems are being used for real-time visualization of the dynamic behavior as well as time-averaged measurements of spatial vapor fraction distributions for two phase fluids. The extraction of quantitative data on vapor-liquid flow fields is a significant advance in the methodology of fundamental two-phase flow experimentation. The data in the form of video images are typically recorded on videotape at 30 frames per second. Image analysis of the video pictures is used to extract time-dependent or time-averaged data. The determination of the average vapor fraction requires averaging of the logarithm of time-dependent intensity measurements of the neutron beam (gray scale distribution of the image) that passes through the fluid. This could be significantly different than averaging the intensity of the transmitted beam and then taking the logarithm of that term. This is termed the dynamic error (error in the time-averaged vapor fractions due t the inherent time-dependence of the measured data) and is separate from the static error (statistical sampling uncertainty). The results provide insight into the characteristics of these errors and help to quantify achievable bounds on the limits of these errors. The static error was determined by the uncertainties of measured beam intensities. It was found that the maximum static error increases as liquid thickness increases and can be reduced by increasing the neutron source strength. The dynamic error increased with large fluctuations in the local vapor fractions and with increasing liquid thickness. Detailed analyses of both sources of errors are discussed.

  16. Characterization of mono-ethylene-glycol based industrial polyurethanes samples by fast-neutron radiography and neutron tomography

    NASA Astrophysics Data System (ADS)

    Rogante, Massimo; Söllradl, Stefan

    2016-09-01

    A complicated structural organization of polyurethanes may have a strong influence on the materials functional properties. Under particular conditions such as mechanical and thermal loading and aging, it leads to the material degradation, even in fresh-prepared bulk polymers and especially if defects are present in the material. Unwanted bubbles can be observed, which form during the expansion of the mixture during its chemical reaction and remain present in the final product. These macro-, micro- and nano-bubbles influence the material's performance. In this work, neutron radiography and tomography have been adopted to characterize at a macro-scale level the bulk of commercially available polyurethane samples, obtained from dissimilar- mixture ratios with different densities and branching levels as well as from different zones of the production mould. The characterisation allowed an estimation of the different dense materials - as they are used, e.g., in soles of shoes - as well as the invisible defects like pores and cracks, responsible for the materials fracture by mechanical loading. The obtained information are expected to be useful for various industrial sectors such as automotive and footwear industry. It will be completed by applying SANS, which has already proved to characterize the microstructure of the bulk-polymer with respect to nano-pores, micro-cracks and their arrangement in the polymer matrix.

  17. Evaluation of water transfer from saturated lightweight aggregate to cement paste matrix by neutron radiography

    NASA Astrophysics Data System (ADS)

    Maruyama, I.; Kanematsu, M.; Noguchi, T.; Iikura, H.; Teramoto, A.; Hayano, H.

    2009-06-01

    In high-strength concrete with low water-cement ratio, self-desiccation occurs due to cement hydration and causes shrinkage and an increased risk of cracking. While high-strength concrete has a denser matrix than normal-strength concrete, resulting in lower permeability, early-age cracks would cancel out this advantage. For the mitigation of this self-desiccation and resultant shrinkage, water-saturated porous aggregate, such as artificial lightweight aggregate, may be used in high-strength concrete. In this contribution, for the purpose of clarification of the volume change of high-strength concrete containing water-saturated lightweight aggregate, water transfer from the lightweight aggregate to cement paste matrix is visualized by neutron radiography. As a result, it is clear that water was supplied to the cement paste matrix in the range 3-8 mm from the surface of the aggregate, and the osmotic forces may yield water transfer around lightweight aggregate in a few hours after mixing.

  18. In-situ investigation of water distribution in polymer electrolyte fuel cell using neutron radiography

    SciTech Connect

    Mishler, Jeffrey H; Mukundan, Rangachary; Borup, Rodney L; Wang, Yun; Hussey, Daniel S; Jacobson, David L

    2010-01-01

    This paper investigates the water content within operating polymer electrolyte membrane (PEM) fuel cells using neutron radiography. We consider fuel cells with various PTFE loadings in their gas diffusion layers (GDL) and microporous layers (MPL), and examine the impacts of MPL/GDL properties on the liquid water behavior and fuel cell performance. Fuel cells are tested at both dry and fully hydrated conditions with different serpentine flow fields. Water contents in the projected areas of channel and land regions are probed. We find that the fuel cell may be subject to more flooding at low current-density operation. In addition, both MPL and GDL wetting properties have substantial impacts on the water content in fuel cell. The cell performance also varies on different scenarios of the MPL/GDL wetting properties. The quad-channel flow field exhibits higher water content without remarkable change in performance at low current densities. Liquid water profile along the channel is presented and liquid water on-set clearly indicated.

  19. Combining fluorescence imaging and neutron radiography to simultaneously record dynamics of oxygen and water content in the root zone

    NASA Astrophysics Data System (ADS)

    Rudolph, N.; Oswald, S. E.; Nagl, S.; Kardjilov, N.

    2010-12-01

    There is a growing need in non-destructive techniques able to measure life-controlling parameters such as oxygen and water dynamics in ecosystems. We use neutron radiography coupled with fluorescence imaging to map the dynamics of these two essential biogeochemical parameters in the root-zone of plants. Measuring the real-time distribution of water and oxygen concentration can enable us to better understand where the active parts of the roots are located in respect to uptake and respiration. Roots performance itself is a function of age and local conditions such as water and oxygen availability in soil. It is technically challenging to monitor these dynamics in small distances from the roots without disturbing them. Non-destructive imaging methods such as fluorescence and neutron imaging provide a unique opportunity to unravel some of these complex processes. Boron-free glass containers (inner size 10cm x 10cm x 1cm) were filled with fine sand of different grain sizes. A sensor foil for O2 (Borisov et al. 2006) was installed on one inner-side of the containers. We grew lupine plants in the container for two weeks under controlled conditions. We took neutron radiographs and fluorescence images of the samples for a range of water contents, and therefore a range of root activities and oxygen changes. We observed the consumption of oxygen induced by roots of lupine plants during 36 hours. Neutron radiography gives us the information about root development and water content. Due to the high water content, aeration from atmosphere is limited. By focusing on the initial conditions we observe that the fluorescence intensity increases in the lower and upper part, where roots are located. The respiration activity creates oxygen deficits close to the roots, and we observed a higher activity by the lateral roots than the tap root. Moreover, the oxygen consumption increases with increasing root growth or root age. After 24 hours the images indicates better aeration in the upper

  20. Study of material changes of SINQ target rods after long-term exposure by neutron radiography methods.

    PubMed

    Lehmann, E E; Vontobel, P; Estermann, M

    2004-10-01

    This paper describes the results of non-destructive investigations by indirect neutron radiography methods obtained at the facility NEUTRA [Nondestruct. Testing Eval. 16 (2000b) 203], spallation neutron source SINQ [Operating experience and development projects at SINQ, PSI Report 98-04, ISSN 1019-0643]. Target rods from the second SINQ metal target were removed after 6 Ah of proton beam exposure and studied under well-shielded conditions. No real damage was found at one of the 11 observed rods and one tube. However, hydrogen accumulation could be identified inside the zircaloy rods and the steel rods as well. Whereas the hydrogen has a homogenous distribution in Zr (with the peak value near the centre of the applied beam), the steel samples show clusters of hydrogen near the edge of the Zr cladding. Lead (in steel cladding) was found modified by accumulations of spallation products, mainly mercury. In the radiography images, a depression of the neutron field was observed due to the absorption by mercury. The applied method with Dy and In as neutron converters and imaging plates [Nucl. Instrum. Methods 377 (1996) 119] as secondary detectors seems to be optimal for such kind of investigations, especially when quantitative considerations have to be made. PMID:15246406

  1. Dual Use Corrosion Inhibitor and Penetrant for Anomaly Detection in Neutron/X Radiography

    NASA Technical Reports Server (NTRS)

    Hall, Phillip B. (Inventor); Novak, Howard L. (Inventor)

    2004-01-01

    A dual purpose corrosion inhibitor and penetrant composition sensitive to radiography interrogation is provided. The corrosion inhibitor mitigates or eliminates corrosion on the surface of a substrate upon which the corrosion inhibitor is applied. In addition, the corrosion inhibitor provides for the attenuation of a signal used during radiography interrogation thereby providing for detection of anomalies on the surface of the substrate.

  2. Optimization and comprehensive characterization of metal hydride based hydrogen storage systems using in-situ Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Börries, S.; Metz, O.; Pranzas, P. K.; Bellosta von Colbe, J. M.; Bücherl, T.; Dornheim, M.; Klassen, T.; Schreyer, A.

    2016-10-01

    For the storage of hydrogen, complex metal hydrides are considered as highly promising with respect to capacity, reversibility and safety. The optimization of corresponding storage tanks demands a precise and time-resolved investigation of the hydrogen distribution in scaled-up metal hydride beds. In this study it is shown that in situ fission Neutron Radiography provides unique insights into the spatial distribution of hydrogen even for scaled-up compacts and therewith enables a direct study of hydrogen storage tanks. A technique is introduced for the precise quantification of both time-resolved data and a priori material distribution, allowing inter alia for an optimization of compacts manufacturing process. For the first time, several macroscopic fields are combined which elucidates the great potential of Neutron Imaging for investigations of metal hydrides by going further than solely 'imaging' the system: A combination of in-situ Neutron Radiography, IR-Thermography and thermodynamic quantities can reveal the interdependency of different driving forces for a scaled-up sodium alanate pellet by means of a multi-correlation analysis. A decisive and time-resolved, complex influence of material packing density is derived. The results of this study enable a variety of new investigation possibilities that provide essential information on the optimization of future hydrogen storage tanks.

  3. Micromachining of commodity plastics by proton beam writing and fabrication of spatial resolution test-chart for neutron radiography

    NASA Astrophysics Data System (ADS)

    Sakai, T.; Yasuda, R.; Iikura, H.; Nojima, T.; Matsubayashi, M.; Kada, W.; Kohka, M.; Satoh, T.; Ohkubo, T.; Ishii, Y.; Takano, K.

    2013-07-01

    Proton beam writing is a direct-write technique and a promising method for the micromachining of commodity plastics such as acrylic resins. Herein, we describe the fabrication of microscopic devices made from a relatively thick (∼75 μm) acrylic sheet using proton beam writing. In addition, a software package that converts image pixels into coordinates data was developed, and the successful fabrication of a very fine jigsaw puzzle was achieved. The size of the jigsaw puzzle pieces was 50 × 50 μm. For practical use, a prototype of a line and space test-chart was also successfully fabricated for the determination of spatial resolution in neutron radiography.

  4. Parameterising root system growth models using 2D neutron radiography images

    NASA Astrophysics Data System (ADS)

    Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel

    2013-04-01

    Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary

  5. Use and imaging performance of CMOS flat panel imager with LiF/ZnS(Ag) and Gadox scintillation screens for neutron radiography

    NASA Astrophysics Data System (ADS)

    Cha, B. K.; kim, J. Y.; Kim, T. J.; Sim, C.; Cho, G.; Lee, D. H.; Seo, C.-W.; Jeon, S.; Huh, Y.

    2011-01-01

    In digital neutron radiography system, a thermal neutron imaging detector based on neutron-sensitive scintillating screens with CMOS(complementary metal oxide semiconductor) flat panel imager is introduced for non-destructive testing (NDT) application. Recently, large area CMOS APS (active-pixel sensor) in conjunction with scintillation films has been widely used in many digital X-ray imaging applications. Instead of typical imaging detectors such as image plates, cooled-CCD cameras and amorphous silicon flat panel detectors in combination with scintillation screens, we tried to apply a scintillator-based CMOS APS to neutron imaging detection systems for high resolution neutron radiography. In this work, two major Gd2O2S:Tb and 6LiF/ZnS:Ag scintillation screens with various thickness were fabricated by a screen printing method. These neutron converter screens consist of a dispersion of Gd2O2S:Tb and 6LiF/ZnS:Ag scintillating particles in acrylic binder. These scintillating screens coupled-CMOS flat panel imager with 25x50mm2 active area and 48μm pixel pitch was used for neutron radiography. Thermal neutron flux with 6x106n/cm2/s was utilized at the NRF facility of HANARO in KAERI. The neutron imaging characterization of the used detector was investigated in terms of relative light output, linearity and spatial resolution in detail. The experimental results of scintillating screen-based CMOS flat panel detectors demonstrate possibility of high sensitive and high spatial resolution imaging in neutron radiography system.

  6. Scattering influences in quantitative fission neutron radiography for the in situ analysis of hydrogen distribution in metal hydrides

    NASA Astrophysics Data System (ADS)

    Börries, S.; Metz, O.; Pranzas, P. K.; Bücherl, T.; Söllradl, S.; Dornheim, M.; Klassen, T.; Schreyer, A.

    2015-10-01

    In situ neutron radiography allows for the time-resolved study of hydrogen distribution in metal hydrides. However, for a precise quantitative investigation of a time-dependent hydrogen content within a host material, an exact knowledge of the corresponding attenuation coefficient is necessary. Additionally, the effect of scattering has to be considered as it is known to violate Beer's law, which is used to determine the amount of hydrogen from a measured intensity distribution. Within this study, we used a metal hydride inside two different hydrogen storage tanks as host systems, consisting of steel and aluminum. The neutron beam attenuation by hydrogen was investigated in these two different setups during the hydrogen absorption process. A linear correlation to the amount of absorbed hydrogen was found, allowing for a readily quantitative investigation. Further, an analysis of scattering contributions on the measured intensity distributions was performed and is described in detail.

  7. Using Neutron Radiography to Quantify Water Transport and the Degree of Saturation in Entrained Air Cement Based Mortar

    NASA Astrophysics Data System (ADS)

    Lucero, Catherine L.; Bentz, Dale P.; Hussey, Daniel S.; Jacobson, David L.; Weiss, W. Jason

    Air entrainment is commonly added to concrete to help in reducing the potential for freeze thaw damage. It is hypothesized that the entrained air voids remain unsaturated or partially saturated long after the smaller pores fill with water. Small gel and capillary pores in the cement matrix fill quickly on exposure to water, but larger pores (entrapped and entrained air voids) require longer times or other methods to achieve saturation. As such, it is important to quantitatively determine the water content and degree of saturation in air entrained cementitious materials. In order to further investigate properties of cement-based mortar, a model based on Beer's Law has been developed to interpret neutron radiographs. This model is a powerful tool for analyzing images acquired from neutron radiography. A mortar with a known volume of aggregate, water to cement ratio and degree of hydration can be imaged and the degree of saturation can be estimated.

  8. Experience of the Indirect Neutron Radiography Method Based on the X-ray Imaging Plate at CARR

    NASA Astrophysics Data System (ADS)

    Wei, Guohai; Han, Songbai; Wang, Hongli; He, Linfeng; Wang, Yu; Wu, Meimei; Liu, Yuntao; Chen, Dongfeng

    Indirect neutron radiography (INR) experiments by X-ray imaging plate were carried out at the China Advanced Research Reactor (CARR). The key experiment parameters were optimized, especially the exposure time of the neutron converter andimaging plate. The optimized total exposure time is 37.25 min, it is two-fifths of the timebased on the film method under the same experimental conditions. The qualitative and quantitativeinspections were tested with dummy nuclear fuel rods and a water temperaturesensor ofa motor vehicle. The spring in the sensor and the defects of the dummy fuel rod's pellets can be qualitatively detected. The thickness of the tape at one position on the cladding of the dummy nuclear fuel rodwas quantitatively calculated to be 9.57 layers with the relative error of ±4.3%.

  9. Where do roots take up water? Neutron radiography of water flow into the roots of transpiring plants growing in soil.

    PubMed

    Zarebanadkouki, Mohsen; Kim, Yangmin X; Carminati, Andrea

    2013-09-01

    Where and how fast does water flow from soil into roots? The answer to this question requires direct and in situ measurement of local flow of water into roots of transpiring plants growing in soil. We used neutron radiography to trace the transport of deuterated water (D₂O) in lupin (Lupinus albus) roots. Lupins were grown in aluminum containers (30 × 25 × 1 cm) filled with sandy soil. D₂O was injected in different soil regions and its transport in soil and roots was monitored by neutron radiography. The transport of water into roots was then quantified using a convection-diffusion model of D₂O transport into roots. The results showed that water uptake was not uniform along roots. Water uptake was higher in the upper soil layers than in the lower ones. Along an individual root, the radial flux was higher in the proximal segments than in the distal segments. In lupins, most of the water uptake occurred in lateral roots. The function of the taproot was to collect water from laterals and transport it to the shoot. This function is ensured by a low radial conductivity and a high axial conductivity. Lupin root architecture seems well designed to take up water from deep soil layers.

  10. Neutron induced bystander effect among zebrafish embryos

    NASA Astrophysics Data System (ADS)

    Ng, C. Y. P.; Kong, E. Y.; Kobayashi, A.; Suya, N.; Uchihori, Y.; Cheng, S. H.; Konishi, T.; Yu, K. N.

    2015-12-01

    The present paper reported the first-ever observation of neutron induced bystander effect (NIBE) using zebrafish (Danio rerio) embryos as the in vivo model. The neutron exposure in the present work was provided by the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. Two different strategies were employed to induce NIBE, namely, through directly partnering and through medium transfer. Both results agreed with a neutron-dose window (20-50 mGy) which could induce NIBE. The lower dose limit corresponded to the threshold amount of neutron-induced damages to trigger significant bystander signals, while the upper limit corresponded to the onset of gamma-ray hormesis which could mitigate the neutron-induced damages and thereby suppress the bystander signals. Failures to observe NIBE in previous studies were due to using neutron doses outside the dose-window. Strategies to enhance the chance of observing NIBE included (1) use of a mono-energetic high-energy (e.g., between 100 keV and 2 MeV) neutron source, and (2) use of a neutron source with a small gamma-ray contamination. It appeared that the NASBEE facility used in the present study fulfilled both conditions, and was thus ideal for triggering NIBE.

  11. Vapor fraction measurements in a steam-water tube at up to 15 bar using neutron radiography techniques

    SciTech Connect

    Glickstein, S.S.; Murphy, J.H.; Joo, H.

    1998-02-01

    Real time neutron radiography has been used to study the dynamic behavior of two phase flow and measure the time averaged vapor fraction in a heated metal tube containing boiling steam water operating at up to 15 bar pressure. The neutron radiographic technique is non-intrusive and requires no special transparent window region. This is the first time this technique has been used in an electrically heated pressurized flow loop. This unique experimental method offers the opportunity to observe and record on videotape, flow patterns and transient behavior of two phase flow inside opaque containers without disturbing the environment. In this study the test sections consisted of stainless steel tubes with a 1.27 cm outer diameter and wall thicknesses of 0.084 cm and 0.124 cm. The experiments were carried out at the Pennsylvania State University 1 megawatt TRIGA reactor facility utilizing a Precise Optics neutron radiography camera. The inlet water temperature to the test section was varied between 120 to 170 C and the flow rate set to 2.3 l/min. T{sub sat} 200 C at these conditions. The tube was resistivity heated by passing high currents ({approximately}1,000 A) through the stainless steel wall. Scattering due to water in the 1 cm tube is significant and Monte Carlo calculations simulating the experiment were made to correct for this effect on the vapor fraction measurement. Details of the experimental technique, methods for analyzing the data and the results of the experiments are discussed.

  12. A study of flow boiling phenomena using real time neutron radiography

    NASA Astrophysics Data System (ADS)

    Novog, David Raymond

    The operation and safety of both fossil-fuel and nuclear power stations depend on adequate cooling of the thermal source involved. This is usually accomplished using liquid coolants that are forced through the high temperature regions by a pumping system; this fluid then transports the thermal energy to another section of the power station. However, fluids that undergo boiling during this process create vapor that can be detrimental, and influence safe operation of other system components. The behavior of this vapor, or void, as it is generated and transported through the system is critical in predicting the operational and safety performance. This study uses two advanced penetrating radiation techniques, Real Time Neutron Radiography (RTNR), and High Speed X-Ray Tomography (HS-XCT), to examine void generation and transport behavior in a flow boiling system. The geometries studied were tube side flow boiling in a cylindrical configuration, and a similar flow channel with an internal twisted tape swirl flow generator. The heat transfer performance and pressure drop characteristics were monitored in addition to void distribution measurements, so that the impact of void distribution could be determined. The RTNR and heat transfer pipe flow studies were conducted using boiling Refrigerant 134a at pressures from 500 to 700 kPa, inlet subcooling from 3 to 12°C and mass fluxes from 55 to 170kg/m 2-s with heat fluxes up to 40 kW/m2. RTNR and HS-XCT were used to measure the distribution and size of the vapor phases in the channel for cylindrical tube-side flow boiling and swirl-flow boiling geometries. The results clearly show that the averaged void is similar for both geometries, but that there is a significant difference in the void distribution, velocity and transport behavior from one configuration to the next. Specifically, the void distribution during flow boiling in a cylindrical-tube test section showed that the void fraction was largest near the tube center and

  13. Boron determination in liver tissue by combining quantitative neutron capture radiography (QNCR) and histological analysis for BNCT treatment planning at the TRIGA Mainz.

    PubMed

    Schütz, C; Brochhausen, C; Altieri, S; Bartholomew, K; Bortolussi, S; Enzmann, F; Gabel, D; Hampel, G; Kirkpatrick, C J; Kratz, J V; Minouchehr, S; Schmidberger, H; Otto, G

    2011-09-01

    The typical primary malignancies of the liver are hepatocellular carcinoma and cholangiocarcinoma, whereas colorectal liver metastases are the most frequently occurring secondary tumors. In many cases, only palliative treatment is possible. Boron neutron capture therapy (BNCT) represents a technique that potentially destroys tumor tissue selectively by use of externally induced, locally confined secondary particle irradiation. In 2001 and 2003, BNCT was applied to two patients with colorectal liver metastases in Pavia, Italy. To scrutinize the rationale of BNCT, a clinical pilot study on patients with colorectal liver metastases was carried out at the University of Mainz. The distribution of the (10)B carrier (p-borono-phenylalanine) in the liver and its uptake in cancerous and tumor-free tissue were determined, focusing on a potential correlation between the uptake of p-borono-phenylalanine and the biological characteristics of cancerous tissue. Samples were analyzed using quantitative neutron capture radiography of cryosections combined with histological analysis. Methodological aspects of the combination of these techniques and results from four patients enrolled in the study are presented that indicate that the uptake of p-borono-phenylalanine strongly depends on the metabolic activity of cells.

  14. Dyadic wavelet for image coding implementation on a Xilinx MicroBlaze processor: application to neutron radiography.

    PubMed

    Saadi, Slami; Touiza, Maamar; Kharfi, Fayçal; Guessoum, Abderrezak

    2013-12-01

    In this work, we present a mixed software/hardware implementation of 2-D signals encoder/decoder using dyadic discrete wavelet transform (DWT) based on quadrature mirror filters (QMF); using fast wavelet Mallat's algorithm. This work is designed and compiled on the embedded development kit EDK6.3i, and the synthesis software, ISE6.3i, which is available with Xilinx Virtex-IIV2MB1000 FPGA. Huffman coding scheme is used to encode the wavelet coefficients so that they can be transmitted progressively through an Ethernet TCP/IP based connection. The possible reconfiguration can be exploited to attain higher performance. The design will be integrated with the neutron radiography system that is used with the Es-Salem research reactor. PMID:24041807

  15. Dyadic wavelet for image coding implementation on a Xilinx MicroBlaze processor: application to neutron radiography.

    PubMed

    Saadi, Slami; Touiza, Maamar; Kharfi, Fayçal; Guessoum, Abderrezak

    2013-12-01

    In this work, we present a mixed software/hardware implementation of 2-D signals encoder/decoder using dyadic discrete wavelet transform (DWT) based on quadrature mirror filters (QMF); using fast wavelet Mallat's algorithm. This work is designed and compiled on the embedded development kit EDK6.3i, and the synthesis software, ISE6.3i, which is available with Xilinx Virtex-IIV2MB1000 FPGA. Huffman coding scheme is used to encode the wavelet coefficients so that they can be transmitted progressively through an Ethernet TCP/IP based connection. The possible reconfiguration can be exploited to attain higher performance. The design will be integrated with the neutron radiography system that is used with the Es-Salem research reactor.

  16. Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography

    NASA Astrophysics Data System (ADS)

    Simpson, R.; Cutler, T. E.; Danly, C. R.; Espy, M. A.; Goglio, J. H.; Hunter, J. F.; Madden, A. C.; Mayo, D. R.; Merrill, F. E.; Nelson, R. O.; Swift, A. L.; Wilde, C. H.; Zocco, T. G.

    2016-11-01

    The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

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

    NASA Astrophysics Data System (ADS)

    Guerra, Francesco; Leone, Matteo; Robotti, Nadia

    2006-09-01

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

  18. Effect of cross-flow on PEFC liquid-water distribution: An in-situ high-resolution neutron radiography study

    NASA Astrophysics Data System (ADS)

    Santamaria, Anthony D.; Becton, Maxwell K.; Cooper, Nathanial J.; Weber, Adam Z.; Park, Jae Wan

    2015-10-01

    Liquid-water management in polymer-electrolyte fuel cells (PEFCs) remains an area of ongoing research. To enhance water removal, certain flow-fields induce cross-flow, or flow through the gas-diffusion layer (GDL) via channel-to-channel pressure differences. While beneficial to water removal, cross-flow comes at the cost of higher pumping pressures and may lead to membrane dehydration and other deleterious issues. This paper examines the impact of cross-flow on component saturation levels as determined through in-plane high-resolution neutron radiography. Various humidities and operating conditions are examined, and the results demonstrate that cell saturation levels correlate strongly with the level of cross-flow rate, and lower GDL saturation levels are found to correlate with an increase in permeability at higher flow rates. Effective water removal is found to occur at channel-to-channel pressure gradients greater than the measured breakthrough pressure of the GDL, evidence that similar liquid-water transport mechanisms exist for under-land area transport as in transverse GDL flow.

  19. Spin distribution in neutron induced preequilibrium reactions

    SciTech Connect

    Dashdorj, D; Kawano, T; Chadwick, M; Devlin, M; Fotiades, N; Nelson, R O; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Macri, R; Younes, W

    2005-10-04

    The preequilibrium reaction mechanism makes an important contribution to neutron-induced reactions above E{sub n} {approx} 10 MeV. The preequilibrium process has been studied exclusively via the characteristic high energy neutrons produced at bombarding energies greater than 10 MeV. They are expanding the study of the preequilibrium reaction mechanism through {gamma}-ray spectroscopy. Cross-section measurements were made of prompt {gamma}-ray production as a function of incident neutron energy (E{sub n} = 1 to 250 MeV) on a {sup 48}Ti sample. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the Los Alamos Neutron Science Center facility. The prompt-reaction {gamma} rays were detected with the large-scale Compton-suppressed Germanium Array for Neutron Induced Excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The {gamma}-ray excitation functions were converted to partial {gamma}-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). Residual state population was predicted using the GNASH reaction code, enhanced for preequilibrium. The preequilibrium reaction spin distribution was calculated using the quantum mechanical theory of Feshback, Kerman, and Koonin (FKK). The multistep direct part of the FKK theory was calculated for a one-step process. The FKK preequilibrium spin distribution was incorporated into the GNASH calculations and the {gamma}-ray production cross sections were calculated and compared with experimental data. The difference in the partial {gamma}-ray cross sections using spin distributions with and without preequilibrium effects is significant.

  20. Visualization of root water uptake: quantification of deuterated water transport in roots using neutron radiography and numerical modeling.

    PubMed

    Zarebanadkouki, Mohsen; Kroener, Eva; Kaestner, Anders; Carminati, Andrea

    2014-10-01

    Our understanding of soil and plant water relations is limited by the lack of experimental methods to measure water fluxes in soil and plants. Here, we describe a new method to noninvasively quantify water fluxes in roots. To this end, neutron radiography was used to trace the transport of deuterated water (D2O) into roots. The results showed that (1) the radial transport of D2O from soil to the roots depended similarly on diffusive and convective transport and (2) the axial transport of D2O along the root xylem was largely dominated by convection. To quantify the convective fluxes from the radiographs, we introduced a convection-diffusion model to simulate the D2O transport in roots. The model takes into account different pathways of water across the root tissue, the endodermis as a layer with distinct transport properties, and the axial transport of D2O in the xylem. The diffusion coefficients of the root tissues were inversely estimated by simulating the experiments at night under the assumption that the convective fluxes were negligible. Inverse modeling of the experiment at day gave the profile of water fluxes into the roots. For a 24-d-old lupine (Lupinus albus) grown in a soil with uniform water content, root water uptake was higher in the proximal parts of lateral roots and decreased toward the distal parts. The method allows the quantification of the root properties and the regions of root water uptake along the root systems.

  1. Visualization of Root Water Uptake: Quantification of Deuterated Water Transport in Roots Using Neutron Radiography and Numerical Modeling[C

    PubMed Central

    Zarebanadkouki, Mohsen; Kroener, Eva; Kaestner, Anders; Carminati, Andrea

    2014-01-01

    Our understanding of soil and plant water relations is limited by the lack of experimental methods to measure water fluxes in soil and plants. Here, we describe a new method to noninvasively quantify water fluxes in roots. To this end, neutron radiography was used to trace the transport of deuterated water (D2O) into roots. The results showed that (1) the radial transport of D2O from soil to the roots depended similarly on diffusive and convective transport and (2) the axial transport of D2O along the root xylem was largely dominated by convection. To quantify the convective fluxes from the radiographs, we introduced a convection-diffusion model to simulate the D2O transport in roots. The model takes into account different pathways of water across the root tissue, the endodermis as a layer with distinct transport properties, and the axial transport of D2O in the xylem. The diffusion coefficients of the root tissues were inversely estimated by simulating the experiments at night under the assumption that the convective fluxes were negligible. Inverse modeling of the experiment at day gave the profile of water fluxes into the roots. For a 24-d-old lupine (Lupinus albus) grown in a soil with uniform water content, root water uptake was higher in the proximal parts of lateral roots and decreased toward the distal parts. The method allows the quantification of the root properties and the regions of root water uptake along the root systems. PMID:25189533

  2. Highly resolved imaging at the soil - plant root interface: A combination of fluorescence imaging and neutron radiography

    NASA Astrophysics Data System (ADS)

    Rudolph, N.; Oswald, S. E.; Lehmann, E.

    2012-12-01

    This study represents a novel experimental set up to non-invasivley map the gradients of biogeochemical parameters at the soil -root interface of plants in situ. The patterns of oxygen, pH and the soil water content distribution were mapped in high resolution with a combination of fluorescence imaging and neutron radiography. Measuring the real-time distribution of water, pH and oxygen concentration would enable us to locate the active parts of the roots in respect to water uptake, exudation and respiration. Roots performance itself is variable as a function of age and development stage and is interrelated with local soil conditions such as water and oxygen availability or nutrients and pH buffering capacity in soil. Non-destructive imaging methods such as fluorescence and neutron imaging have provided a unique opportunity to unravel some of these complex processes. Thin glass containers (inner size 10cm x 10cm x 1.5 cm) were filled with 2 different sandy soils. Sensor foil for O2 and pH were installed on the inner-sides of the containers. We grew lupine plants in the container under controlled conditions until the root system was developed. Growing plants at different stages prior to the imaging experiment, we took neutron radiographs and fluorescence images of 10-day old and 30-day old root systems of lupine plants over a range of soil water contents, and therefore a range of root activities and oxygen changes. We observed the oxygen consumption pattern, the pH changes, and the root water uptake of lupine plants over the course of several days. We observed a higher respiration activity around the lateral roots than for the tap root. The oxygen depletion zones around the roots extended to farther distances after each rewatering of the samples. Root systems of the plants were mapped from the neutron radiograps. Close association of the roots distribution and the the location of oxygen depletion patterns provided evidence that this effect was caused by roots. The

  3. Developments for neutron-induced fission at IGISOL-4

    NASA Astrophysics Data System (ADS)

    Gorelov, D.; Penttilä, H.; Al-Adili, A.; Eronen, T.; Hakala, J.; Jokinen, A.; Kankainen, A.; Kolhinen, V. S.; Koponen, J.; Lantz, M.; Mattera, A.; Moore, I. D.; Pohjalainen, I.; Pomp, S.; Rakopoulos, V.; Reinikainen, J.; Rinta-Antila, S.; Simutkin, V.; Solders, A.; Voss, A.; Äystö, J.

    2016-06-01

    At the IGISOL-4 facility, neutron-rich, medium mass nuclei have usually been produced via charged particle-induced fission of natural uranium and thorium. Neutron-induced fission is expected to have a higher production cross section of the most neutron-rich species. Development of a neutron source along with a new ion guide continues to be one of the major goals since the commissioning of IGISOL-4. Neutron intensities at different angles from a beryllium neutron source have been measured in an on-line experiment with a 30 MeV proton beam. Recently, the new ion guide coupled to the neutron source has been tested as well. Details of the neutron source and ion guide design together with preliminary results from the first neutron-induced fission experiment at IGISOL-4 are presented in this report.

  4. Monte-Carlo simulations of neutron-induced activation in a Fast-Neutron and Gamma-Based Cargo Inspection System

    NASA Astrophysics Data System (ADS)

    Bromberger, B.; Bar, D.; Brandis, M.; Dangendorf, V.; Goldberg, M. B.; Kaufmann, F.; Mor, I.; Nolte, R.; Schmiedel, M.; Tittelmeier, K.; Vartsky, D.; Wershofen, H.

    2012-03-01

    An air cargo inspection system combining two nuclear reaction based techniques, namely Fast-Neutron Resonance Radiography and Dual-Discrete-Energy Gamma Radiography is currently being developed. This system is expected to allow detection of standard and improvised explosives as well as special nuclear materials. An important aspect for the applicability of nuclear techniques in an airport inspection facility is the inventory and lifetimes of radioactive isotopes produced by the neutron radiation inside the cargo, as well as the dose delivered by these isotopes to people in contact with the cargo during and following the interrogation procedure. Using MCNPX and CINDER90 we have calculated the activation levels for several typical inspection scenarios. One example is the activation of various metal samples embedded in a cotton-filled container. To validate the simulation results, a benchmark experiment was performed, in which metal samples were activated by fast-neutrons in a water-filled glass jar. The induced activity was determined by analyzing the gamma spectra. Based on the calculated radioactive inventory in the container, the dose levels due to the induced gamma radiation were calculated at several distances from the container and in relevant time windows after the irradiation, in order to evaluate the radiation exposure of the cargo handling staff, air crew and passengers during flight. The possibility of remanent long-lived radioactive inventory after cargo is delivered to the client is also of concern and was evaluated.

  5. Neutron-induced defects in optical fibers

    SciTech Connect

    Rizzolo, S.; Morana, A.; Boukenter, A.; Ouerdane, Y.; Girard, S.; Cannas, M.; Boscaino, R.; Bauer, S.; Perisse, J.; Mace, J-R.; Nacir, B.

    2014-10-21

    We present a study on 0.8 MeV neutron-induced defects up to fluences of 10{sup 17} n/cm{sup 2} in fluorine doped optical fibers by using electron paramagnetic resonance, optical absorption and confocal micro-luminescence techniques. Our results allow to address the microscopic mechanisms leading to the generation of Silica-related point-defects such as E', H(I), POR and NBOH Centers.

  6. Neutron-induced defects in optical fibers

    NASA Astrophysics Data System (ADS)

    Rizzolo, S.; Morana, A.; Cannas, M.; Bauer, S.; Perisse, J.; Mace, J.-R.; Boscaino, R.; Boukenter, A.; Ouerdane, Y.; Nacir, B.; Girard, S.

    2014-10-01

    We present a study on 0.8 MeV neutron-induced defects up to fluences of 1017 n/cm2 in fluorine doped optical fibers by using electron paramagnetic resonance, optical absorption and confocal micro-luminescence techniques. Our results allow to address the microscopic mechanisms leading to the generation of Silica-related point-defects such as E', H(I), POR and NBOH Centers.

  7. Intercomparison of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples.

    PubMed

    Schütz, C L; Brochhausen, C; Hampel, G; Iffland, D; Kuczewski, B; Otto, G; Schmitz, T; Stieghorst, C; Kratz, J V

    2012-10-01

    Boron determination in blood and tissue samples is a crucial task especially for treatment planning, preclinical research, and clinical application of boron neutron capture therapy (BNCT). Comparison of clinical findings remains difficult due to a variety of analytical methods, protocols, and standard reference materials in use. This paper addresses the comparability of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples. It was possible to demonstrate that three different methods relying on three different principles of sample preparation and boron detection can be validated against each other and yield consistent results for both blood and tissue samples. The samples were obtained during a clinical study for the application of BNCT for liver malignancies and therefore represent a realistic situation for boron analysis.

  8. Quantitative imaging of water transport in soil and roots using neutron radiography, D2O and a new numerical model

    NASA Astrophysics Data System (ADS)

    Zarebanadkouki, M.; Kroener, E.; Ahmed, M. A.; Carminati, A.

    2014-12-01

    Our understanding of soil and plant water relations is currently limited by the lack of experimental methods to measure the water fluxes in soil and plants. Our study aimed to develop a new non-destructive method to measure the local fluxes of water into roots of plants growing in soils. We injected deuterated water (D2O) near the roots of lupines growing in sandy soils, and we used neutron radiography to image the transport of D2O through the root system. The experiments were performed during day, when plants were transpiring, and at night, when transpiration was reduced. The radiographs showed that: 1) the radial transport of D2O from soil and roots depended similarly to diffusion and convection; and 2) the axial transport of D2O along the root xylem was largely dominated by convection. To determine the convective fluxes from the radiographs, we simulated the D2O transport in soils and roots. A dual porosity model was used to describe the apoplastic and symplastic pathways of water across the root tissue. Other features such as the endodermis and the xylem were also included in the model. The D2O transport was modelled solving a convection-diffusion numerical model in soil and plants. The diffusion coefficients of the root tissues were inversely estimated by simulating the experiments at night under the assumption that at night the convective fluxes were negligible. Inverse modelling of the experiment at day gave the profile of water fluxes into the roots. For 24 day-old lupine grown in a sandy soil with uniform water content, our modelling results showed that root water uptake was higher at the proximal parts of the roots near soil surface and it decreased toward the distal parts. The method allows the quantification of the root properties and the regions of root water uptake along root systems growing in soils. Future applications of this method include the characterization of varying root systems, the radial and axial hydraulic conductivity of different root

  9. Neutron radiography and X-ray computed tomography for quantifying weathering and water uptake processes inside porous limestone used as building material

    SciTech Connect

    Dewanckele, J.; De Kock, T.; Fronteau, G.; Derluyn, H.; Vontobel, P.; Dierick, M.; Van Hoorebeke, L.; Jacobs, P.; Cnudde, V.

    2014-02-15

    Euville and Savonnières limestones were weathered by acid test and this resulted in the formation of a gypsum crust. In order to characterize the crystallization pattern and the evolution of the pore structure below the crust, a combination of high resolution X-ray computed tomography and SEM–EDS was used. A time lapse sequence of the changing pore structure in both stones was obtained and afterwards quantified by using image analysis. The difference in weathering of both stones by the same process could be explained by the underlying microstructure and texture. Because water and moisture play a crucial role in the weathering processes, water uptake in weathered and non-weathered samples was characterized based on neutron radiography. In this way the water uptake was both visualized and quantified in function of the height of the sample and in function of time. In general, the formation of a gypsum crust on limestone slows down the initial water uptake in the materials. - Highlights: • Time lapse sequence in 3D of changing pore structures inside limestone • A combination of X-ray CT, SEM and neutron radiography was used. • Quantification of water content in function of time, height and weathering • Characterization of weathering processes due to gypsum crystallization.

  10. Time-resolved fast-neutron radiography of air-water two-phase flows in a rectangular channel by an improved detection system

    SciTech Connect

    Zboray, Robert; Dangendorf, Volker; Bromberger, Benjamin; Tittelmeier, Kai; Mor, Ilan

    2015-07-15

    In a previous work, we have demonstrated the feasibility of high-frame-rate, fast-neutron radiography of generic air-water two-phase flows in a 1.5 cm thick, rectangular flow channel. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany, using an multi-frame, time-resolved detector developed for fast neutron resonance radiography. The results were however not fully optimal and therefore we have decided to modify the detector and optimize it for the given application, which is described in the present work. Furthermore, we managed to improve the image post-processing methodology and the noise suppression. Using the tailored detector and the improved post-processing, significant increase in the image quality and an order of magnitude lower exposure times, down to 3.33 ms, have been achieved with minimized motion artifacts. Similar to the previous study, different two-phase flow regimes such as bubbly slug and churn flows have been examined. The enhanced imaging quality enables an improved prediction of two-phase flow parameters like the instantaneous volumetric gas fraction, bubble size, and bubble velocities. Instantaneous velocity fields around the gas enclosures can also be more robustly predicted using optical flow methods as previously.

  11. Measurement of delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons

    SciTech Connect

    Gundorin, N. A.; Zhdanova, K. V.; Zhuchko, V. E.; Pikelner, L. B. Rebrova, N. V.; Salamatin, I. M.; Smirnov, V. I.; Furman, V. I.

    2007-06-15

    The delayed-neutron yield from thermal-neutron-induced fission of the {sup 237}Np nucleus was measured using a sample periodically exposed to a pulsed neutron beam with subsequent detection of neutrons during the time intervals between pulses. The experiment was realized on an Isomer-M setup mounted in the IBR-2 pulsed reactor channel equipped with a mirror neutron guide. The setup and the experimental procedure are described, the background sources are thoroughly analyzed, and the experimental data are presented. The total delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons is {nu}{sub d} = 0.0110 {+-} 0.0009. This study was performed at the Frank Laboratory of Neutron Physics (JINR, Dubna)

  12. Application of very low energy neutron radiography with energy selection system using 4Qc(4m) supermirror

    NASA Astrophysics Data System (ADS)

    Kawabata, Yuji; Hino, Masahiro; Nakano, Takafumi; Sunohara, Hiroaki; Matsushima, Uzuki; Geltenbort, Peter

    2005-04-01

    A high contrast neutron CT system is installed in the VCN/PF2 port of Institut Laue-Langevin and VCN port of Kyoto University Reactor (KUR). A converter+C-CCD system is used for the image detection. This system has an option of the energy selection system by neutron reflection on a 4Qc (4m) supermirror. The critical angle of the neutron reflection on this mirror is four times larger than that of natural nickel and the diameter is 20 cm. As the neutron reflection on a mirror removes faster neutrons, it can be used as a low pass filter of the neutron energy. The upper limit of the reflected neutron energy can be easily changed by the rotation of the mirror. As the application of this high contrast imaging system, the density nonuniformity of an aluminum welding sample can be shown by the refraction effect of very cold neutrons in VCN/PF2/ILL.

  13. Neutron-induced single event burnout in high voltage electronics

    SciTech Connect

    Normand, E.; Wert, J.L.; Oberg, D.L.; Majewski, P.P.; Voss, P.; Wender, S.A.

    1997-12-01

    Energetic neutrons with an atmospheric neutron spectrum, which were demonstrated to induce single event burnout in power MOSFETs, have been shown to induce burnout in high voltage (>3,000V) electronics when operated at voltages as low as 50% of rated voltage. The laboratory failure rates correlate well with field failure rates measured in Europe.

  14. Detection of special nuclear material from delayed neutron emission induced by a dual-particle monoenergetic source

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Nattress, J.; Jovanovic, I.

    2016-06-01

    Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the 11B(d,n γ)12C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass-polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time-dependent buildup and decay of delayed neutron emission from 238U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

  15. Real-time measurements of temperature, pressure and moisture profiles in High-Performance Concrete exposed to high temperatures during neutron radiography imaging

    SciTech Connect

    Toropovs, N.; Lo Monte, F.; Wyrzykowski, M.; Weber, B.; Sahmenko, G.; Vontobel, P.; Felicetti, R.; Lura, P.

    2015-02-15

    High-Performance Concrete (HPC) is particularly prone to explosive spalling when exposed to high temperature. Although the exact causes that lead to spalling are still being debated, moisture transport during heating plays an important role in all proposed mechanisms. In this study, slabs made of high-performance, low water-to-binder ratio mortars with addition of superabsorbent polymers (SAP) and polypropylene fibers (PP) were heated from one side on a temperature-controlled plate up to 550 °C. A combination of measurements was performed simultaneously on the same sample: moisture profiles via neutron radiography, temperature profiles with embedded thermocouples and pore pressure evolution with embedded pressure sensors. Spalling occurred in the sample with SAP, where sharp profiles of moisture and temperature were observed. No spalling occurred when PP-fibers were introduced in addition to SAP. The experimental procedure described here is essential for developing and verifying numerical models and studying measures against fire spalling risk in HPC.

  16. Magnetic field induced differential neutron phase contrast imaging

    SciTech Connect

    Strobl, M.; Treimer, W.; Walter, P.; Keil, S.; Manke, I.

    2007-12-17

    Besides the attenuation of a neutron beam penetrating an object, induced phase changes have been utilized to provide contrast in neutron and x-ray imaging. In analogy to differential phase contrast imaging of bulk samples, the refraction of neutrons by magnetic fields yields image contrast. Here, it will be reported how double crystal setups can provide quantitative tomographic images of magnetic fields. The use of magnetic air prisms adequate to split the neutron spin states enables a distinction of field induced phase shifts and these introduced by interaction with matter.

  17. Neutron induced capture and fission discrimination using calorimetric shape decomposition

    NASA Astrophysics Data System (ADS)

    Carrapiço, C.; Berthoumieux, E.; Dridi, W.; Gonçalves, I. F.; Gunsing, F.; Lampoudis, C.; Vaz, P.; n TOF Collaboration

    2013-03-01

    The neutron capture and fission cross-sections of 233U have been measured at the neutron time-of-flight facility n_TOF at CERN in the energy range from 1 eV to 1 keV using a high performance 4π BaF2 Total Absorption Calorimeter (TAC) as a detection device. In order to separate the contributions of neutron capture and neutron induced fission in the TAC, a methodology called Calorimetric Shape Decomposition (CSD) was developed. The CSD methodology is based on the study of the TAC's energy response for all competing reactions, allowing to discriminate between γ s originating from neutron induced fission and those from neutron capture reactions without the need for fission tagging or any additional detection system. In this article, the concept behind the CSD is explained in detail together with the necessary analysis to obtain the TAC's response to neutron capture and neutron induced fission. The discrimination between capture and fission contributions is shown for several neutron energies. A comparison between the 233U neutron capture and fission yield extraction with ENDF/B-VII v1. library data is also provided.

  18. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    NASA Astrophysics Data System (ADS)

    Gozani, Tsahi; King, Michael J.

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

  19. An approach of reducing the background induced by neutrons

    NASA Technical Reports Server (NTRS)

    Shen, C.; Gu, Y.; Sun, Y.; Ma, Y.; Dai, C.; Fan, Z.

    1985-01-01

    The background induced by interactions of neutrons with detector material (and shield material) is difficult to be rejected. It is one of the most important factors to affect the sensitivity of a balloon-borne gamma-ray astronomical telescope. The main component of neutron flux at the major detector of the telescope is incident neutrons, that consists of atmospheric neutrons and neutrons locally produced in the balloon platform. Therefore, shielding the detector from incident neutrons is a possible way to reduce the background. NaI (T1) crystal is very widely used in gamma-ray astronomical telescopes. Through balloon-borne experiment it is shown that up 6 LiF shield is effective to reduce the background in NaI crystal.

  20. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    NASA Astrophysics Data System (ADS)

    Jandel, M.; Bredeweg, T. A.; Stoyer, M. A.; Wu, C. Y.; Fowler, M. M.; Becker, J. A.; Bond, E. M.; Couture, A.; Haight, R. C.; Haslett, R. J.; Henderson, R. A.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.

    2009-01-01

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for 241Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for 243Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on 242mAm will be presented where the fission events were actively triggered during the experiments. In these experiments, a Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,γ) events from (n,f) events. The first direct observation of neutron capture on 242mAm in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  1. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    SciTech Connect

    Jandel, Marian

    2008-01-01

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) from (n,f) events. The first evidence of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  2. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    SciTech Connect

    Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Couture, A.; Haight, R. C.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Stoyer, M. A.; Wu, C. Y.; Becker, J. A.; Haslett, R. J.; Henderson, R. A.

    2009-01-28

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented where the fission events were actively triggered during the experiments. In these experiments, a Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) events from (n,f) events. The first direct observation of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  3. Prompt Emission in Fission Induced with Fast Neutrons

    NASA Astrophysics Data System (ADS)

    Wilson, J. N.; Lebois, M.; Halipré, P.; Oberstedt, S.; Oberstedt, A.

    Prompt gamma-ray and neutron emission data in fission integrates a large amount of information on the fission process and can shed light on the partition of energy. Measured emission spectra, average energies and multiplicities also provide important information for energy applications. While current reactors mostly use thermal neutron spectra, the future reactors of Generation IV will use fast neutron spectra for which little experimental prompt emission data exist. Initial investigations on prompt emission in fast neutron induced fission have recently been carried out at the LICORNE facility at the IPN Orsay, which exploits inverse reactions to produce naturally collimated, intense beams of neutrons. We report on first results with LICORNE to measure prompt fission gamma-ray spectra, average energies and multiplicities for 235U and 238U. Current improvements and upgrades being carried out on the LICORNE facility will also be described, including the development of a H2 gas target to reduce parasitic backgrounds and increase intensities, and the deployment of 11B beams to extend the effective LICORNE neutron energy range up to 12 MeV. Prospects for future experimental studies of prompt gamma-ray and neutron emission in fast neutron induced fission will be presented.

  4. Low doses of neutrons induce changes in gene expression

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, C.M. ); Panozzo, J.; Libertin, C.R. )

    1993-01-01

    Studies were designed to identify genes induced following low-dose neutron but not following [gamma]-ray exposure in fibroblasts. Our past work had shown differences in the expression of [beta]-protein kinase C and c-fos genes, both being induced following [gamma]-ray but not neutron exposure. We have identified two genes that are induced following neutron, but not [gamma]-ray, exposure: Rp-8 (a gene induced by apoptosis) and the long terminal repeat (LTR) of the human immunodeficiency (HIV). Rp-8 mRNA induction was demonstrated in Syrian hamster embryo fibroblasts and was found to be induced in cells exposed to neutrons administered at low (0.5 cGy/min) and at high dose rate (12 cGy/min). The induction of transcription from the LTR of HIV was demonstrated in HeLa cells bearing a transfected construct of the chloramphenicol acetyl transferase (CAT) gene driven by the HIV-LTR promoter. Measures of CAT activity and CAT transcripts following irradiation demonstrated an unresponsiveness to [gamma] rays over a broad range of doses. Twofold induction of the HIV-LTR was detected following neutron exposure (48 cGy) administered at low (0.5 cGy/min) but not high (12 cGy/min) dose rates. Ultraviolet-mediated HIV-LTR induction was inhibited by low-dose-rate neutron exposure.

  5. Low doses of neutrons induce changes in gene expression

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, C.M.; Panozzo, J.; Libertin, C.R.

    1993-06-01

    Studies were designed to identify genes induced following low-dose neutron but not following {gamma}-ray exposure in fibroblasts. Our past work had shown differences in the expression of {beta}-protein kinase C and c-fos genes, both being induced following {gamma}-ray but not neutron exposure. We have identified two genes that are induced following neutron, but not {gamma}-ray, exposure: Rp-8 (a gene induced by apoptosis) and the long terminal repeat (LTR) of the human immunodeficiency (HIV). Rp-8 mRNA induction was demonstrated in Syrian hamster embryo fibroblasts and was found to be induced in cells exposed to neutrons administered at low (0.5 cGy/min) and at high dose rate (12 cGy/min). The induction of transcription from the LTR of HIV was demonstrated in HeLa cells bearing a transfected construct of the chloramphenicol acetyl transferase (CAT) gene driven by the HIV-LTR promoter. Measures of CAT activity and CAT transcripts following irradiation demonstrated an unresponsiveness to {gamma} rays over a broad range of doses. Twofold induction of the HIV-LTR was detected following neutron exposure (48 cGy) administered at low (0.5 cGy/min) but not high (12 cGy/min) dose rates. Ultraviolet-mediated HIV-LTR induction was inhibited by low-dose-rate neutron exposure.

  6. A SURVEY OF HIGH EXPLOSIVE-INDUCED DAMAGE AND SPALL IN SELECTED METALS USING PROTON RADIOGRAPHY.

    SciTech Connect

    Holtkamp, D. B.; Clark, D. A.; Ferm, E. N.; Gallegos, R. A.; Hammon, D.; Hemsing, W. F.; Hogan, G. E.; Holmes, V. H.; King, N.. S.P; liljestrand, R.; Lopez, R. P.; Merrill, F. E.; Morris, C. L.; Morley, K. B.; Murray, M. M.; Pazuchanics, P. D.; Prestridge, K. P.; Quintana, J. P.; Saunders, A.; Schafer, T.; Shinas, M. A.

    2003-07-01

    Multiple spall and damage layers can be created in metal when the free surface reflects a Taylor wave generated by high explosives. These phenomena have been explored in different thicknesses of several metals (tantalum, copper, 6061 T6-aluminum, and tin) using high-energy proton radiography. Multiple images (up to 21) can be produced of the dynamic evolution of damaged material on the microsecond time scale with a <50 ns “shutter” time. Movies and multiframe still images of areal and (Abel inverted) volume densities are presented. An example of material that is likely melted on release (tin) is also presented..

  7. Sorption kinetics of superabsorbent polymers (SAPs) in fresh Portland cement-based pastes visualized and quantified by neutron radiography and correlated to the progress of cement hydration

    SciTech Connect

    Schroefl, Christof; Mechtcherine, Viktor; Vontobel, Peter; Hovind, Jan; Lehmann, Eberhard

    2015-09-15

    Water sorption of two superabsorbent polymers in cement-based pastes has been characterized by neutron radiography. Cement pastes with W/C of 0.25 and 0.50 and one additionally containing silica fume (W/C = 0.42) were investigated. The SAPs differed in their inherent sorption kinetics in extracted cement pore solution (SAP 1: self-releasing; SAP 2: retentive). Desorption from SAP 1 started very early after paste preparation. Hence, its individual non-retentiveness governs its behavior only. SAP 2 released water into all matrices, but its kinetics were different. In the paste with the highest W/C, some moderate water release was recorded from the beginning. In the other two pastes, SAP 2 retained its stored liquid during the dormant period, i.e., up to the percolation threshold. Intense desorption then set in and continued throughout the acceleration period. These findings explain the pronouncedly higher efficiency of SAP 2 as internal curing admixture as compared to SAP 1.

  8. Investigation of the role of the micro-porous layer in polymer electrolyte fuel cells with hydrogen deuterium contrast neutron radiography.

    PubMed

    Cho, Kyu Taek; Mench, Matthew M

    2012-03-28

    In this study, the high resolution hydrogen-deuterium contrast radiography method was applied to elucidate the impact of the micro-porous layer (MPL) on water distribution in the porous fuel cell media. At the steady state, deuterium replaced hydrogen in the anode stream, and the large difference in neutron attenuation of the D(2)O produced at the cathode was used to track the produced water. It was found that the water content peaked in the cathode-side diffusion media (DM) for the cell without MPL, but with an MPL on the anode and cathode DM, the peak water amount was pushed toward the anode, resulting in a relatively flattened water profile through components and demonstrating a liquid barrier effect. Additionally, the dynamic water behavior in diffusion media was analyzed to understand the effect of a MPL and operating conditions. The water content in the DM changed with applied current, although there is a significant amount of residual liquid content that does not appear to be part of capillary channels. The effect of the MPL on irreducible saturation in DM and cell performance was also investigated.

  9. Actinide neutron-induced fission cross section measurements at LANSCE

    SciTech Connect

    Tovesson, Fredrik K; Laptev, Alexander B; Hill, Tony S

    2010-01-01

    Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub-thermal energies up to 200 MeV. A parallel-plate ionization chamber are used to measure fission cross sections ratios relative to the {sup 235}U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, {sup 239-242}Pu and {sup 243}Am neutron-induced fission cross sections. Obtained data are presented in comparison with ex isting evaluations and previous data.

  10. Neutron-Induced Cross Sections Measurements of Calcium

    SciTech Connect

    Guber, Klaus H; Kopecky, S.; Schillebeeckx, P.; Kauwenberghs, K.; Siegler, P.

    2013-01-01

    To support the US Department of Energy Nuclear Criticality Safety Program neutron induced cross section experiments were performed at the Geel Electron Linear Accelerator of the Institute for Reference Material and Measurements of the Joint Research Centers, European Union. Neutron capture and transmission measurements were carried out using a metallic calcium sample. The obtained data will be used for a new calcium evaluation, which will be submitted with its covariances to the ENDBF/B nuclear data base.

  11. Neutron irradiation induced amorphization of silicon carbide

    SciTech Connect

    Snead, L.L.; Hay, J.C.

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  12. X-ray tests of a microchannel plate detector and amorphous silicon pixel array readout for neutron radiography

    NASA Astrophysics Data System (ADS)

    Ambrosi, R. M.; Street, R.; Feller, B.; Fraser, G. W.; Watterson, J. I. W.; Lanza, R. C.; Dowson, J.; Ross, D.; Martindale, A.; Abbey, A. F.; Vernon, D.

    2007-03-01

    High-performance large area imaging detectors for fast neutrons in the 5-14 MeV energy range do not exist at present. The aim of this project is to combine microchannel plates or MCPs (or similar electron multiplication structures) traditionally used in image intensifiers and X-ray detectors with amorphous silicon (a-Si) pixel arrays to produce a composite converter and intensifier position sensitive imaging system. This detector will provide an order of magnitude improvement in image resolution when compared with current millimetre resolution limits obtained using phosphor or scintillator-based hydrogen rich converters. In this study we present the results of the initial experimental evaluation of the prototype system. This study was carried out using a medical X-ray source for the proof of concept tests, the next phase will involve neutron imaging tests. The hybrid detector described in this study is a unique development and paves the way for large area position sensitive detectors consisting of MCP or microsphere plate detectors and a-Si or polysilicon pixel arrays. Applications include neutron and X-ray imaging for terrestrial applications. The technology could be extended to space instrumentation for X-ray astronomy.

  13. Flash Proton Radiography

    NASA Astrophysics Data System (ADS)

    Merrill, Frank E.

    Protons were first investigated as radiographic probes as high energy proton accelerators became accessible to the scientific community in the 1960s. Like the initial use of X-rays in the 1800s, protons were shown to be a useful tool for studying the contents of opaque materials, but the electromagnetic charge of the protons opened up a new set of interaction processes which complicated their use. These complications in combination with the high expense of generating protons with energies high enough to penetrate typical objects resulted in proton radiography becoming a novelty, demonstrated at accelerator facilities, but not utilized to their full potential until the 1990s at Los Alamos. During this time Los Alamos National Laboratory was investigating a wide range of options, including X-rays and neutrons, as the next generation of probes to be used for thick object flash radiography. During this process it was realized that the charge nature of the protons, which was the source of the initial difficulty with this idea, could be used to recover this technique. By introducing a magnetic imaging lens downstream of the object to be radiographed, the blur resulting from scattering within the object could be focused out of the measurements, dramatically improving the resolution of proton radiography of thick systems. Imaging systems were quickly developed and combined with the temporal structure of a proton beam generated by a linear accelerator, providing a unique flash radiography capability for measurements at Los Alamos National Laboratory. This technique has now been employed at LANSCE for two decades and has been adopted around the world as the premier flash radiography technique for the study of dynamic material properties.

  14. Neutron radiation induced degradation of diode characteristics

    NASA Astrophysics Data System (ADS)

    Khanna, S. M.; Pepper, G. T.; Stone, R. E.

    1992-12-01

    Neutron radiation effects on diode current-voltage characteristics have been studied for a variety of diode over 1(10)(exp 13) - 3(10)(exp 15) n/sq cm 1 MeV equivalent neutron fluence range. A classification scheme consisting of three types of neutron effects on diode forward characteristics is proposed here for the first time. For constant forward current I(sub F) higher than that in the generation-recombination regime, the diode voltage V(sub F) either increases with fluence phi (Type 1 diode), on V(sub F) first decreases with phi at lower fluence levels and then increases with phi at higher fluence levels (Type 2 diode), or V(sub F) decreases with phi at all fluence levels used in this work (Type 3 diode). Most of the previous results on p-n junction diodes correspond to Type 1 diode results. Type 2 diode results are rather rare in the literature. Several examples of Type 2 diode results are presented here. Type 3 diode results are reported here for other types of diodes not reported earlier. These results are explained qualitatively in terms of the theories for a p-n junction and for radiation effects on semiconductors. It is shown here that a type 3 diode could be developed as a high neutron fluence monitor with three orders of magnitude higher upper limit than the Harshaw p-i-n diode neutron fluence monitor under evaluation at the US Army Aberdeen Proving Grounds, Aberdeen, Md. The results also suggest a methodology for radiation hard diode development.

  15. Neutron-induced background in charge-coupled device detectors

    SciTech Connect

    Jaanimagi, P. A.; Boni, R.; Keck, R. L.

    2001-01-01

    The inertial confinement fusion (ICF) community must become more cognizant of the neutron-induced background levels in charge-coupled device (CCD) detectors that are replacing film as the recording medium in many ICF diagnostics. This background degrades the signal-to-noise ratio (SNR) of the recorded signals and for the highest-yield shots comprises a substantial fraction of the pixel's full well capacity. CCD detectors located anywhere in the OMEGA Target Bay are precluded from recording high precision signals (SNR>30) for deuterium--tritium neutron yields greater than 10{sup 13}. CCDs make excellent calibrated neutron detectors. The average CCD background level is proportional to the neutron yield, and we have measured a linear response over four decades. The spectrum of deposited energy per pixel is heavily weighted to low energies, <50 keV, with a few isolated saturated pixels. Most of the background recorded by the CCDs is due to secondary radiation produced by interactions of the primary neutrons with all the materials in the Target Bay as well as the shield walls and the floor. Since the noise source comes from all directions it is very difficult to shield. The fallback position of using film instead of CCD cameras for high-neutron-yield target shots is flawed, as we have observed substantially increased fog levels on our x-ray recording film as a function of the neutron yield.

  16. X-ray Induced Pinhole Closure in Point Projection X-ray Radiography

    SciTech Connect

    Bullock, A B; Landen, O L; Blue, B E; Edwards, J; Bradley, D K

    2006-01-13

    In pinhole-assisted point-projection x-ray radiography (or ''backlighting''), pinholes are placed between the sample of interest and an x-ray source (or ''backlighter'') to effectively limit the source size and hence improve the spatial resolution of the system. Pinholes are generally placed close to such x-ray backlighters to increase the field-of-view, leading to possible vaporization and pinhole closure due to x-ray driven ablation, thereby potentially limiting the usefulness of this method. An experimental study and modeling of time-dependent closure and resolution is presented. The pinhole closure timescale is studied for various pinhole sizes, pinhole to backlighter separations and filtering conditions. In addition the time-dependent resolution is extracted from one-dimensional wire imaging prior to pinhole closure. Cylindrical hydrodynamic modeling of the pinhole closure shows reasonable agreement with data, giving us a predictive capability for pinhole closure in future experiments.

  17. Neutron-induced reaction studies using stored ions

    NASA Astrophysics Data System (ADS)

    Glorius, Jan; Litvinov, Yuri A.; Reifarth, René

    2015-11-01

    Storage rings provide unique possibilities for investigations of nuclear reactions. Radioactive ions can be stored if the ring is connected to an appropriate facility and reaction studies are feasible at low beam intensities because of the recycling of beam particles. Using gas jet or droplet targets, charged particle-induced reactions on short-lived isotopes can be studied in inverse kinematics. In such a system a high-flux reactor could serve as a neutron target extending the experimental spectrum to neutron-induced reactions. Those could be studied over a wide energy range covering the research fields of nuclear astrophysics and reactor safety, transmutation of nuclear waste and fusion.

  18. Facility for neutron induced few body reactions at Bochum University

    NASA Astrophysics Data System (ADS)

    Bannach, B.; Bodek, K.; Börker, G.; Kamke, D.; Krug, J.; Lekkas, P.; Lübcke, W.; Stephan, M.

    1987-02-01

    A facility is described which is designed for the measurement of neutron induced three-body breakup. It has been used for the breakup of deuterium and of the nucleus 9Be. Neutrons are produced by a pulsed beam of deuterons from the Bochum 4MV Dynamitron-Tandem accelerator by bombarding a thick tritium-titanium target or a deuterium gas target. The outgoing beam is collimated by a 4π shielding to a solid angle of about 1 msr. In most cases, a liquid scintillator (NE232 or a mixture of NE232/NE213) serves as a target for the neutron beam. Scattered neutrons are detected by NE213-detectors of different sizes. For testing purposes the differential elastic n-d cross section and simultaneously the response of NE232 have been measured at 22.4 and 7.9 MeV.

  19. Neutron Induced Capture and Fission Processes on 238U

    NASA Astrophysics Data System (ADS)

    Oprea, Cristiana; Oprea, Alexandru

    2016-03-01

    Nuclear data on Uranium isotopes are of crucial interest for new generation of nuclear reactors. Processes of interest are the nuclear reactions induced by neutrons and in this work mainly the capture and the fission process on 238U will be analyzed in a wide energy interval. For slow and resonant neutrons the many levels Breit - Wigner formalism is necessary. In the case of fast and very fast neutrons up to 200 MeV the nuclear reaction mechanism implemented in Talys will be used. The present evaluations are necessary in order to obtain the field of neutrons in the design of nuclear reactors and they are compared with experimental data from literature obtained from capture and (n,xn) processes.

  20. Basic Physics Data: Measurement of Neutron Multiplicity from Induced Fission

    SciTech Connect

    Pozzi, Sara; Haight, Robert

    2015-05-04

    From October 1 to October 17 a team of researchers from UM visited the LANSCE facility for an experiment during beam-time allotted from October 4 to October 17. A total of 24 detectors were used at LANSCE including liquid organic scintillation detectors (EJ-309), NaI scintillation detectors, and Li-6 enriched glass detectors. It is a double time-offlight (TOF) measurement using spallation neutrons generated by a target bombarded with pulsed high-energy protons. The neutrons travel to an LLNL-manufactured parallel plate avalanche chamber (PPAC) loaded with thin U-235 foils in which fission events are induced. The generated fission neutrons and photons are then detected in a detector array designed and built at UM and shipped to LANSCE. Preparations were made at UM, where setup and proposed detectors were tested. The UM equipment was then shipped to LANSCE for use at the 15L beam of the weapons neutron research (WNR) facility.

  1. Skull Radiography

    MedlinePlus

    What you need to know about… Skull Radiography X-ray images of the skull are taken when it is necessary to see the cranium, facial bones or jaw bones. ... Among other things, x-ray exams of the skull can show fractures. Patient Preparation Before the examination, ...

  2. High Energy Neutron Induced Gamma Production

    SciTech Connect

    Brown, D A; Johnson, M; Navratil, P

    2007-09-28

    N Division has an interest in improving the physics and accuracy of the gamma data it provides to its customers. It was asked to look into major gamma producing reactions for 14 MeV incident neutrons for several low-Z materials and determine whether LLNL's processed data files faithfully represent the current state of experimental and theoretical knowledge for these reactions. To address this, we surveyed the evaluations of the requested materials, made recommendations for the next ENDL release and noted isotopes that will require further experimental study. This process uncovered several major problems in our translation and processing of the ENDF formatted evaluations, most of which have been resolved.

  3. Noise-induced dephasing in neutron interferometry

    SciTech Connect

    Sulyok, G.; Hasegawa, Y.; Rauch, H.; Klepp, J.; Lemmel, H.

    2010-05-15

    Decoherence phenomenona in a neutron interferometer are analyzed by simulation of the effects of an environment with magnetic noise fields. Basic calculations and experiments show the validity and limitations of this model system. In particular, loss and recovery of the interference pattern with controllable noise sources in both interferometer arms are discussed in detail. In addition, the decoherence behavior at high interference order, where Schroedinger-cat-like states exist in the interferometer, is investigated. While at low interference order a smearing of the interference pattern is observed, at high interference order a smearing of the modulated momentum distribution occurs.

  4. Recovering root system traits using image analysis exemplified by two-dimensional neutron radiography images of lupine.

    PubMed

    Leitner, Daniel; Felderer, Bernd; Vontobel, Peter; Schnepf, Andrea

    2014-01-01

    Root system traits are important in view of current challenges such as sustainable crop production with reduced fertilizer input or in resource-limited environments. We present a novel approach for recovering root architectural parameters based on image-analysis techniques. It is based on a graph representation of the segmented and skeletonized image of the root system, where individual roots are tracked in a fully automated way. Using a dynamic root architecture model for deciding whether a specific path in the graph is likely to represent a root helps to distinguish root overlaps from branches and favors the analysis of root development over a sequence of images. After the root tracking step, global traits such as topological characteristics as well as root architectural parameters are computed. Analysis of neutron radiographic root system images of lupine (Lupinus albus) grown in mesocosms filled with sandy soil results in a set of root architectural parameters. They are used to simulate the dynamic development of the root system and to compute the corresponding root length densities in the mesocosm. The graph representation of the root system provides global information about connectivity inside the graph. The underlying root growth model helps to determine which path inside the graph is most likely for a given root. This facilitates the systematic investigation of root architectural traits, in particular with respect to the parameterization of dynamic root architecture models. PMID:24218493

  5. Recovering root system traits using image analysis exemplified by two-dimensional neutron radiography images of lupine.

    PubMed

    Leitner, Daniel; Felderer, Bernd; Vontobel, Peter; Schnepf, Andrea

    2014-01-01

    Root system traits are important in view of current challenges such as sustainable crop production with reduced fertilizer input or in resource-limited environments. We present a novel approach for recovering root architectural parameters based on image-analysis techniques. It is based on a graph representation of the segmented and skeletonized image of the root system, where individual roots are tracked in a fully automated way. Using a dynamic root architecture model for deciding whether a specific path in the graph is likely to represent a root helps to distinguish root overlaps from branches and favors the analysis of root development over a sequence of images. After the root tracking step, global traits such as topological characteristics as well as root architectural parameters are computed. Analysis of neutron radiographic root system images of lupine (Lupinus albus) grown in mesocosms filled with sandy soil results in a set of root architectural parameters. They are used to simulate the dynamic development of the root system and to compute the corresponding root length densities in the mesocosm. The graph representation of the root system provides global information about connectivity inside the graph. The underlying root growth model helps to determine which path inside the graph is most likely for a given root. This facilitates the systematic investigation of root architectural traits, in particular with respect to the parameterization of dynamic root architecture models.

  6. Fast neutron imaging device and method

    DOEpatents

    Popov, Vladimir; Degtiarenko, Pavel; Musatov, Igor V.

    2014-02-11

    A fast neutron imaging apparatus and method of constructing fast neutron radiography images, the apparatus including a neutron source and a detector that provides event-by-event acquisition of position and energy deposition, and optionally timing and pulse shape for each individual neutron event detected by the detector. The method for constructing fast neutron radiography images utilizes the apparatus of the invention.

  7. Particle Beam Radiography

    NASA Astrophysics Data System (ADS)

    Peach, Ken; Ekdahl, Carl

    2014-02-01

    Particle beam radiography, which uses a variety of particle probes (neutrons, protons, electrons, gammas and potentially other particles) to study the structure of materials and objects noninvasively, is reviewed, largely from an accelerator perspective, although the use of cosmic rays (mainly muons but potentially also high-energy neutrinos) is briefly reviewed. Tomography is a form of radiography which uses multiple views to reconstruct a three-dimensional density map of an object. There is a very wide range of applications of radiography and tomography, from medicine to engineering and security, and advances in instrumentation, specifically the development of electronic detectors, allow rapid analysis of the resultant radiographs. Flash radiography is a diagnostic technique for large high-explosive-driven hydrodynamic experiments that is used at many laboratories. The bremsstrahlung radiation pulse from an intense relativistic electron beam incident onto a high-Z target is the source of these radiographs. The challenge is to provide radiation sources intense enough to penetrate hundreds of g/cm2 of material, in pulses short enough to stop the motion of high-speed hydrodynamic shocks, and with source spots small enough to resolve fine details. The challenge has been met with a wide variety of accelerator technologies, including pulsed-power-driven diodes, air-core pulsed betatrons and high-current linear induction accelerators. Accelerator technology has also evolved to accommodate the experimenters' continuing quest for multiple images in time and space. Linear induction accelerators have had a major role in these advances, especially in providing multiple-time radiographs of the largest hydrodynamic experiments.

  8. Defect-induced magnetism in graphite through neutron irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Yutian; Pochet, Pascal; Jenkins, Catherine A.; Arenholz, Elke; Bukalis, Gregor; Gemming, Sibylle; Helm, Manfred; Zhou, Shengqiang

    2014-12-01

    We have investigated the variation in the magnetization of highly ordered pyrolytic graphite (HOPG) after neutron irradiation, which introduces defects in the bulk sample and consequently gives rise to a large magnetic signal. We observe strong paramagnetism in HOPG, increasing with the neutron fluence. The induced paramagnetism can be well correlated with structural defects by comparison with density-functional theory calculations. In addition to the in-plane vacancies, the transplanar defects also contribute to the magnetization. The lack of any magnetic order between the local moments is possibly due to the absence of hydrogen/nitrogen chemisorption, or the magnetic order cannot be established at all in the bulk form.

  9. Analysis of induced effects in matter during pulsed Nd:YAG laser welding by flash radiography

    NASA Astrophysics Data System (ADS)

    Pascal, G.; Noré, D.; Girard, K.; Perret, O.; Naudy, P.

    2000-05-01

    Tantalum and TA6V (titanium alloy) are respectively used in corrosive chemical product containers and in aircraft and aerospace industries. The objective of this study was to analyze the dynamic behavior of the matter during deep laser spot welding of these materials. The obtained images should allow a better understanding of laser-matter interaction and should validate a model developed for porosities formation. Because of the afterglow of detectors, classical video x-ray systems are not suitable for the analysis of short dynamic effects during and after the laser pulse. An experimental device, based on a flash x-ray generator EUROPULSE 600 kV and a QUANTEL pulsed Nd:YAG laser, has been used. The flash x-ray generator is triggered, after a programmed delay, by the laser shot. The x-ray pulse duration is 30 ns. Welding parameters (pulse duration and energy) yield molten zones of 2 mm depth. Both materials, tantalum and TA6V, have been tested. Radiological films BIOMAX coupled with radioluminescent screens and direct exposure film (DEF) were respectively used for tantalum and TA6V samples. A fine collimation was studied to avoid the scattering effect in the material and in the radioluminescent screen. Radiological test samples, made of tantalum and TA6V, were performed to estimate the images qualities obtained by flash radiography. About 270 laser/x-rays shots were performed. The radiographic images have been digitalized and processed. The results show a deep and narrow capillary hole called "keyhole" which appears a few milliseconds after the beginning of the interaction. The "keyhole" hollows until the end of the laser pulse. After the end of the laser pulse, the molten bath collapses in less than 1 ms, trapping cavities.

  10. Phase contrast radiography: Image modeling and optimization

    NASA Astrophysics Data System (ADS)

    Arhatari, Benedicta D.; Mancuso, Adrian P.; Peele, Andrew G.; Nugent, Keith A.

    2004-12-01

    We consider image formation for the phase-contrast radiography technique where the radiation source is extended and spatially incoherent. A model is developed for this imaging process which allows us to define an objective filtering criterion that can be applied to the recovery of quantitative phase images from data obtained at different propagation distances. We test our image model with experimental x-ray data. We then apply our filter to experimental neutron phase radiography data and demonstrate improved image quality.

  11. Neutron Induced Cross Sections for Radiochemistry for Isotopes of Nickel, Copper, and Zinc

    SciTech Connect

    Kelley, K; Hoffman, R D; Dietrich, F S; Mustafa, M

    2006-05-30

    We have developed a set of modeled neutron induced cross sections for use in radiochemical diagnostics. Local systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for target isotopes of nickel, copper, and zinc (28 {le} Z {le} 30) for neutron numbers 30 {le} N {le} 40.

  12. Estimation of neutron-induced spallation yields of krypton isotopes

    NASA Astrophysics Data System (ADS)

    Karol, Paul J.; Tobin, Michael J.; Shibata, Seiichi

    1983-10-01

    A procedure is outlined for estimating cross sections for neutron-induced spallation products relative to those for proton-induced reactions. When combined with known proton spallation systematics, it is demonstrated that cumulative yields for cosmogenically-important stable 84Kr and 86Kr isotopes are ~1.4 and ~2.8 times greater, respectively, for incident neutrons compared to protons at 0.2<=E<=3.0 GeV for nearby medium mass targets. Yields for lighter kryptons are relatively insensitive to the identity of the incident nucleon. NUCLEAR REACTIONS (n, spallation), 0.2<=En<=3.0 GeV, stable Kr product yield estimates from proton spallation systematics.

  13. Genotoxicity of neutrons in Drosophila melanogaster. Somatic mutation and recombination induced by reactor neutrons.

    PubMed

    Guzmán-Rincón, J; Delfín-Loya, A; Ureña-Núñez, F; Paredes, L C; Zambrano-Achirica, F; Graf, U

    2005-08-01

    This paper describes the observation of a direct relationship between the absorbed doses of neutrons and the frequencies of somatic mutation and recombination using the wing somatic mutation and recombination test (SMART) of Drosophila melanogaster. This test was used for evaluating the biological effects induced by neutrons from the Triga Mark III reactor of Mexico. Two different reactor power levels were used, 300 and 1000 kW, and two absorbed doses were tested for each power level: 1.6 and 3.2 Gy for 300 kW and 0.84 and 1.7 Gy for 1000 kW. A linear relationship was observed between the absorbed dose and the somatic mutation and recombination frequencies. Furthermore, these frequencies were dependent on larval age: In 96-h-old larvae, the frequencies were increased considerably but the sizes of the spots were smaller than in 72-h-old larvae. The analysis of the balancer-heterozygous progeny showed a linear absorbed dose- response relationship, although the responses were clearly lower than found in the marker-trans-heterozygous flies. Approximately 65% of the genotoxicity observed is due to recombinational events. The results of the study indicate that thermal and fast neutrons are both mutagenic and recombinagenic in the D. melanogaster wing SMART, and that the frequencies are dependent on neutron dose, reactor power, and the age of the treated larvae.

  14. Genotoxicity of neutrons in Drosophila melanogaster. Somatic mutation and recombination induced by reactor neutrons.

    PubMed

    Guzmán-Rincón, J; Delfín-Loya, A; Ureña-Núñez, F; Paredes, L C; Zambrano-Achirica, F; Graf, U

    2005-08-01

    This paper describes the observation of a direct relationship between the absorbed doses of neutrons and the frequencies of somatic mutation and recombination using the wing somatic mutation and recombination test (SMART) of Drosophila melanogaster. This test was used for evaluating the biological effects induced by neutrons from the Triga Mark III reactor of Mexico. Two different reactor power levels were used, 300 and 1000 kW, and two absorbed doses were tested for each power level: 1.6 and 3.2 Gy for 300 kW and 0.84 and 1.7 Gy for 1000 kW. A linear relationship was observed between the absorbed dose and the somatic mutation and recombination frequencies. Furthermore, these frequencies were dependent on larval age: In 96-h-old larvae, the frequencies were increased considerably but the sizes of the spots were smaller than in 72-h-old larvae. The analysis of the balancer-heterozygous progeny showed a linear absorbed dose- response relationship, although the responses were clearly lower than found in the marker-trans-heterozygous flies. Approximately 65% of the genotoxicity observed is due to recombinational events. The results of the study indicate that thermal and fast neutrons are both mutagenic and recombinagenic in the D. melanogaster wing SMART, and that the frequencies are dependent on neutron dose, reactor power, and the age of the treated larvae. PMID:16038586

  15. Digital Radiography

    NASA Technical Reports Server (NTRS)

    1986-01-01

    System One, a digital radiography system, incorporates a reusable image medium (RIM) which retains an image. No film is needed; the RIM is read with a laser scanner, and the information is used to produce a digital image on an image processor. The image is stored on an optical disc. System allows the radiologist to "dial away" unwanted images to compare views on three screens. It is compatible with existing equipment and cost efficient. It was commercialized by a Stanford researcher from energy selective technology developed under a NASA grant.

  16. Electron radiography

    DOEpatents

    Merrill, Frank E.; Morris, Christopher

    2005-05-17

    A system capable of performing radiography using a beam of electrons. Diffuser means receive a beam of electrons and diffuse the electrons before they enter first matching quadrupoles where the diffused electrons are focused prior to the diffused electrons entering an object. First imaging quadrupoles receive the focused diffused electrons after the focused diffused electrons have been scattered by the object for focusing the scattered electrons. Collimator means receive the scattered electrons and remove scattered electrons that have scattered to large angles. Second imaging quadrupoles receive the collimated scattered electrons and refocus the collimated scattered electrons and map the focused collimated scattered electrons to transverse locations on an image plane representative of the electrons' positions in the object.

  17. Muon-Induced Neutrons Do Not Explain the DAMA Data.

    PubMed

    Klinger, J; Kudryavtsev, V A

    2015-04-17

    We present an accurate model of the muon-induced background in the DAMA/LIBRA experiment. Our work challenges proposed mechanisms which seek to explain the observed DAMA signal modulation with muon-induced backgrounds. Muon generation and transport are performed using the MUSIC/MUSUN code, and subsequent interactions in the vicinity of the DAMA detector cavern are simulated with Geant4. We estimate the total muon-induced neutron flux in the detector cavern to be Φ(n)(ν)=1.0 × 10(-9)  cm(-2) s(-1). We predict 3.49 × 10(-5)  counts/day/kg/keV, which accounts for less than 0.3% of the DAMA signal modulation amplitude.

  18. Muon-Induced Neutrons Do Not Explain the DAMA Data

    NASA Astrophysics Data System (ADS)

    Klinger, J.; Kudryavtsev, V. A.

    2015-04-01

    We present an accurate model of the muon-induced background in the DAMA/LIBRA experiment. Our work challenges proposed mechanisms which seek to explain the observed DAMA signal modulation with muon-induced backgrounds. Muon generation and transport are performed using the MUSIC /MUSUN code, and subsequent interactions in the vicinity of the DAMA detector cavern are simulated with Geant4. We estimate the total muon-induced neutron flux in the detector cavern to be Φnν=1.0 ×10-9 cm-2 s-1 . We predict 3.49 ×10-5 counts /day /kg /keV , which accounts for less than 0.3% of the DAMA signal modulation amplitude.

  19. Electron-Induced Neutron Knockout from 4He

    NASA Astrophysics Data System (ADS)

    Misiejuk, A.; Papandreou, Z.; Voutier, E.; Bauer, Th. S.; Blok, H. P.; Boersma, D. J.; den Bok, H. W.; Bruins, E. E.; Farzanpay, F.; Grüner, K.; Hesselink, W. H.; Huber, G. M.; Jans, E.; Kalantar-Nayestanaki, N.; Kasdorp, W.-J.; Konijn, J.; Laget, J.-M.; Lapikás, L.; Lolos, G. J.; Onderwater, G. J.; Pellegrino, A.; Schroevers, R.; Spaltro, C. M.; Starink, R.; van der Steenhoven, G.; Steiger, J. J.; Visschers, J. L.; Willering, H. W.; Yeomans, D. M.

    2002-10-01

    The differential cross section for electron-induced neutron knockout in the reaction 4He(e,e'n)3He has been measured for the first time with a statistical accuracy of 11%. The experiment was performed in quasielastic kinematics at a momentum transfer of 300 MeV/c and in the missing-momentum range of 25-70 MeV/c. The comparison of the data with theoretical calculations shows an impressive increase of the cross section resulting from final state interaction effects. Specifically , the p-n charge-exchange process dominates the cross section in this kinematical regime.

  20. Neutron distribution and induced activity inside a Linac treatment room.

    PubMed

    Juste, B; Miró, R; Verdú, G; Díez, S; Campayo, J M

    2015-01-01

    Induced radioactivity and photoneutron contamination inside a radiation therapy bunker of a medical linear accelerator (Linac) is investigated in this work. The Linac studied is an Elekta Precise electron accelerator which maximum treatment photon energy is 15 MeV. This energy exceeds the photonuclear reaction threshold (around 7 MeV for high atomic number metals). The Monte Carlo code MCNP6 has been used for quantifying the neutron contamination inside the treatment room for different gantry rotation configuration. Walls activation processes have also been simulated. The approach described in this paper is useful to prevent the overexposure of patients and medical staff. PMID:26737878

  1. Neutron production in neutron-induced reactions at 96 MeV on 56Fe and 208Pb

    NASA Astrophysics Data System (ADS)

    Sagrado García, I. C.; Lecolley, J. F.; Lecolley, F. R.; Blideanu, V.; Ban, G.; Fontbonne, J. M.; Itis, G.; Lecouey, J. L.; Lefort, T.; Marie, N.; Steckmeyer, J. C.; Le Brun, C.; Blomgren, J.; Johansson, C.; Klug, J.; Orhn, A.; Mermod, P.; Olsson, N.; Pomp, S.; Osterlund, M.; Tippawan, U.; Prokofiev, A. V.; Nadel-Turonski, P.; Fallot, M.; Foucher, Y.; Guertin, A.; Haddad, F.; Vatre, M.

    2011-10-01

    Double-differential cross sections for neutron production were measured in 96-MeV neutron-induced reactions at The Svedberg Laboratory in Uppsala, Sweden. Measurements for Fe and Pb targets were performed using two independent setups: DECOI-DEMON, time-of-flight telescope dedicated to the detection of emitted neutrons with energies between a few and 50MeV and CLODIA-SCANDAL device devoted to measuring emitted neutrons with energies above 40MeV. Double-differential cross sections were measured for an angular range between 15 and 98 deg and with low-energy thresholds (≈2 MeV). Angular and energy distributions and total neutron emission cross sections have been obtained from those measurements. Results have been compared with predictions given by different models included in several transport codes (MCNPX, GEANT, TALYS, PHITS, and DYWAN) and with other experimental data (the EXFOR database).

  2. Cross-sectional void fraction distribution measurements in a vertical annulus two-phase flow by high speed X-ray computed tomography and real-time neutron radiography techniques

    SciTech Connect

    Harvel, G.D. |; Hori, K.; Kawanishi, K.

    1995-09-01

    A Real-Time Neutron Radiography (RTNR) system and a high speed X-ray Computed tomography (X-CT) system are compared for measurement of two-phase flow. Each system is used to determine the flow regime, and the void fraction distribution in a vertical annulus flow channel. A standard optical video system is also used to observe the flow regime. The annulus flow channel is operated as a bubble column and measurements obtained for gas flow rates from 0.0 to 30.01/min. The flow regimes observed by all three measurement systems through image analysis shows that the two-dimensional void fraction distribution can be obtained. The X-CT system is shown to have a superior temporal resolution capable of resolving the void fraction distribution in an (r,{theta}) plane in 33.0 ms. Void fraction distribution for bubbly flow and slug flow is determined.

  3. System for uncollimated digital radiography

    DOEpatents

    Wang, Han; Hall, James M.; McCarrick, James F.; Tang, Vincent

    2015-08-11

    The inversion algorithm based on the maximum entropy method (MEM) removes unwanted effects in high energy imaging resulting from an uncollimated source interacting with a finitely thick scintillator. The algorithm takes as input the image from the thick scintillator (TS) and the radiography setup geometry. The algorithm then outputs a restored image which appears as if taken with an infinitesimally thin scintillator (ITS). Inversion is accomplished by numerically generating a probabilistic model relating the ITS image to the TS image and then inverting this model on the TS image through MEM. This reconstruction technique can reduce the exposure time or the required source intensity without undesirable object blurring on the image by allowing the use of both thicker scintillators with higher efficiencies and closer source-to-detector distances to maximize incident radiation flux. The technique is applicable in radiographic applications including fast neutron, high-energy gamma and x-ray radiography using thick scintillators.

  4. Probing energy dissipation, γ-ray and neutron multiplicity in the thermal neutron-induced fission of 239Pu

    NASA Astrophysics Data System (ADS)

    Pahlavani, M. R.; Mirfathi, S. M.

    2016-04-01

    The incorporation of the four-dimensional Langevin equations led to an integrative description of fission cross-section, fragment mass distribution and the multiplicity and energy distribution of prompt neutrons and γ-rays in the thermal neutron-induced fission of 239Pu. The dynamical approach presented in this paper thoroughly reproduces several experimental observables of the fission process at low excitation energy.

  5. INDUSTRIAL RADIOGRAPHY INSTRUCTOR'S GUIDE.

    ERIC Educational Resources Information Center

    Bureau of Adult, Vocational, and Technical Education (DHEW/OE), Washington, DC. Div. of Vocational and Technical Education.

    THIS LABORATORY GUIDE WAS DEVELOPED FOR AN 80-HOUR COURSE IN INDUSTRIAL RADIOGRAPHY FOR HIGH SCHOOL GRADUATES TRAINING TO BECOME BEGINNING RADIOGRAPHERS. IT IS USED IN CONJUNCTION WITH TWO OTHER VOLUMES--(1) INDUSTRIAL RADIOGRAPHY INSTRUCTOR'S GUIDE, AND (2) INUDSTRIAL RADIOGRAPHY MANUAL. THE PROGRAM WAS DEVELOPED BY A COMMITTEE OF REPRESENTATIVES…

  6. Charged particle radiography.

    PubMed

    Morris, C L; King, N S P; Kwiatkowski, K; Mariam, F G; Merrill, F E; Saunders, A

    2013-04-01

    New applications of charged particle radiography have been developed over the past two decades that extend the range of radiographic techniques providing high-speed sequences of radiographs of thicker objects with higher effective dose than can be obtained with conventional radiographic techniques. In this paper, we review the motivation and the development of flash radiography and in particular, charged particle radiography. PMID:23481477

  7. Charged particle radiography

    NASA Astrophysics Data System (ADS)

    Morris, C. L.; King, N. S. P.; Kwiatkowski, K.; Mariam, F. G.; Merrill, F. E.; Saunders, A.

    2013-04-01

    New applications of charged particle radiography have been developed over the past two decades that extend the range of radiographic techniques providing high-speed sequences of radiographs of thicker objects with higher effective dose than can be obtained with conventional radiographic techniques. In this paper, we review the motivation and the development of flash radiography and in particular, charged particle radiography.

  8. Evaluating the 239Pu prompt fission neutron spectrum induced by thermal to 30 MeV neutrons

    DOE PAGESBeta

    Neudecker, Denise; Talou, Patrick; Kawano, Toshihiko; Kahler, Albert Comstock; Rising, Michael Evan; White, Morgan Curtis

    2016-03-15

    We present a new evaluation of the 239Pu prompt fission neutron spectrum (PFNS) induced by thermal to 30 MeV neutrons. Compared to the ENDF/B-VII.1 evaluation, this one includes recently published experimental data as well as an improved and extended model description to predict PFNS. For instance, the pre-equilibrium neutron emission component to the PFNS is considered and the incident energy dependence of model parameters is parametrized more realistically. Experimental and model parameter uncertainties and covariances are estimated in detail. Also, evaluated covariances are provided between all PFNS at different incident neutron energies. In conclusion, selected evaluation results and first benchmarkmore » calculations using this evaluation are briefly discussed.« less

  9. Evaluating the 239Pu Prompt Fission Neutron Spectrum Induced by Thermal to 30 MeV Neutrons

    NASA Astrophysics Data System (ADS)

    Neudecker, D.; Talou, P.; Kawano, T.; Kahler, A. C.; Rising, M. E.; White, M. C.

    2016-03-01

    We present a new evaluation of the 239Pu prompt fission neutron spectrum (PFNS) induced by thermal to 30 MeV neutrons. Compared to the ENDF/B-VII.1 evaluation, this one includes recently published experimental data as well as an improved and extended model description to predict PFNS. For instance, the pre-equilibrium neutron emission component to the PFNS is considered and the incident energy dependence of model parameters is parametrized more realistically. Experimental and model parameter uncertainties and covariances are estimated in detail. Also, evaluated covariances are provided between all PFNS at different incident neutron energies. Selected evaluation results and first benchmark calculations using this evaluation are briefly discussed.

  10. α and 2 p 2 n emission in fast neutron-induced reactions on 60Ni

    NASA Astrophysics Data System (ADS)

    Fotiades, N.; Devlin, M.; Haight, R. C.; Nelson, R. O.; Kunieda, S.; Kawano, T.

    2015-06-01

    Background: The cross sections for populating the residual nucleus in the reaction ZAX(n,x) Z -2 A -4Y exhibit peaks as a function of incident neutron energy corresponding to the (n ,n'α ) reaction and, at higher energy, to the (n ,2 p 3 n ) reaction. The relative magnitudes of these peaks vary with the Z of the target nucleus. Purpose: Study fast neutron-induced reactions on 60Ni. Locate experimentally the nuclear charge region along the line of stability where the cross sections for α emission and for 2 p 2 n emission in fast neutron-induced reactions are comparable as a further test of reaction models. Methods: Data were taken by using the Germanium Array for Neutron-Induced Excitations. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center's Weapons Neutron Research facility provided neutrons in the energy range from 1 to 250 MeV. The time-of-flight technique was used to determine the incident-neutron energies. Results: Absolute partial cross sections for production of seven discrete Fe γ rays populated in 60Ni (n ,α /2 p x n γ ) reactions with 2 ≤x ≤5 were measured for neutron energies 1 MeVneutron energies while discrepancies appear at higher neutron energies. The cross section for producing an isotope in fast neutron-induced reactions on stable targets via α emission at the peak of the (n ,α ) and (n ,n'α ) reactions is comparable to that for 2 p 2 n and 2 p 3 n emission at higher incident energies in the nuclear charge region around Fe.

  11. Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced fission reactions on Pu239

    NASA Astrophysics Data System (ADS)

    Talou, P.; Becker, B.; Kawano, T.; Chadwick, M. B.; Danon, Y.

    2011-06-01

    Prompt fission neutrons following the thermal and 0.5 MeV neutron-induced fission reaction of Pu239 are calculated using a Monte Carlo approach to the evaporation of the excited fission fragments. Exclusive data such as the multiplicity distribution P(ν), the average multiplicity as a function of fragment mass ν¯(A), and many others are inferred in addition to the most used average prompt fission neutron spectrum χ(Ein,Eout), as well as average neutron multiplicity ν¯. Experimental information on these more exclusive data help constrain the Monte Carlo model parameters. The calculated average total neutron multiplicity is ν¯c=2.871 in very close agreement with the evaluated value ν¯e=2.8725 present in the ENDF/B-VII.0 library. The neutron multiplicity distribution P(ν) is in very good agreement with the evaluation by Holden and Zucker. The calculated average spectrum differs in shape from the ENDF/B-VII.0 spectrum, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail of the spectrum (below about 300 keV) than the Madland-Nix calculations, casting some doubts on how much scission neutrons contribute to the shape of the low-energy tail of the spectrum. The spectrum high-energy tail is very sensitive to the total kinetic energy distribution of the fragments as well as to the total excitation energy sharing at scission. Present experimental uncertainties on measured spectra above 6 MeV are too large to distinguish between various theoretical hypotheses. Finally, comparisons of the Monte Carlo results with experimental data on ν¯(A) indicate that more neutrons are emitted from the light fragments than the heavy ones, in agreement with previous works.

  12. Cosmic-Ray-Induced Ship-Effect Neutron Measurements and Implications for Cargo Scanning at Borders

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Seifert, Allen; Siciliano, Edward R.; Weier, Dennis R.; Windsor, Lindsay K.; Woodring, Mitchell L.; Borgardt, James D.; Buckley, Elise D.; Flumerfelt, Eric L.; Oliveri, Anna F.; Salvitti, Matthew

    2008-03-11

    Neutron measurements are used as part of the interdiction process for illicit nuclear materials at border crossings. Even though the natural neutron background is small, its variation can impact the sensitivity of detection systems. The natural background of neutrons that is observed in monitoring instruments arises almost entirely from cosmic ray induced cascades in the atmosphere and the surrounding environment. One significant source of variation in the observed neutron background is produced by the “ship effect” in large quantities of cargo that transit past detection instruments. This paper reports on results from measurements with typical monitoring equipment of ship effect neutrons in various materials. One new result is the “neutron shadow shielding” effect seen with some low neutron density materials.

  13. Experimental Evaluation of Neutron Induced Noise on Gated X-ray Framing Cameras

    SciTech Connect

    Izumi, N; Stone, G; Hagmann, C; Sorce, C; Bradley, D K; Moran, M; Landen, O L; Stoeffl, W; Springer, P; Tommasini, R; Hermann, H W; Kyrala, G A; Glebov, V Y; Sangster, T C; Koch, J A

    2009-10-08

    A micro-channel plate based temporally-gated x-ray camera (framing camera) is one of the most versatile diagnostic tools of inertial confinement fusion experiments; particularly for observation of the shape of x-ray self emission from compressed core of imploded capsules. However, components used in an x-ray framing camera have sensitivity to neutrons induced secondary radiations. On early low-yield capsule implosions at the National Ignition Facility (NIF), the expected neutron production is about 5 x 10{sup 14}. Therefore, the expected neutron fluence at a framing camera located {approx} 150 cm from the object is 2 x 10{sup 9} neutrons/cm{sup 2}. To obtain gated x-ray images in such harsh neutron environments, quantitative understanding of neutron-induced backgrounds is crucial.

  14. Measurement of residual 60Co activity induced by atomic-bomb neutrons in Nagasaki and background contribution by environmental neutrons.

    PubMed

    Shizuma, Kiyoshi; Endo, Satoru; Hoshi, Masaharu; Takada, Jun; Iwatani, Kazuo; Hasai, Hiromi; Oka, Takamitsu; Shimazaki, Tatsuya; Okumura, Yutaka; Fujita, Shoichiro; Watanabe, Tadaaki; Imanaka, Tetsuji

    2002-12-01

    Residual 60Co activity in five steel samples induced by neutrons from the Nagasaki atomic bomb has been measured within about 1000 m from the hypocenter. The chemical separation of cobalt and nickel from steel samples was performed, and cobalt-enriched samples were prepared for all samples. Gamma-ray measurements were carried out with a low-background well-type germanium detector. The gamma-ray spectra for five samples were compared with the spectrum of a control sample to ensure that the observed 60Co was actually induced by A-bomb neutrons. The activation of cobalt by environmental neutrons was also investigated. It has been shown that the present 60Co data are consistent with earlier Hashizume's data. PMID:12674203

  15. New developments in proton radiography at LANSCE

    NASA Astrophysics Data System (ADS)

    Morris, Christopher; Proton Radiography Team

    2014-09-01

    In a new application of nuclear physics, a facility for using proton for flash radiography has been developed at the Los Alamos Neutron Science Center (LANSCE). Protons have proven far superior to high energy x-rays for flash radiography. Although this facility is primarily used for studying very fast phenomena such as high explosive driven experiments, it is finding increasing application to other fields, such as tomography of static objects, phase changes in materials, and the dynamics of chemical reactions. The advantages of protons will be discussed and data from some of the recent experiments will be presented.

  16. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano

    PubMed Central

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d’Ars, Jean; Komorowski, Jean-Christophe

    2016-01-01

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 106 m3 to 7 × 106 m3. However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [−0.8;−0.4] × 109 kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 109 kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir. PMID:27629497

  17. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano.

    PubMed

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d'Ars, Jean; Komorowski, Jean-Christophe

    2016-01-01

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 10(6) m(3) to 7 × 10(6) m(3). However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [-0.8;-0.4] × 10(9) kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 10(9) kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir. PMID:27629497

  18. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano.

    PubMed

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d'Ars, Jean; Komorowski, Jean-Christophe

    2016-09-15

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 10(6) m(3) to 7 × 10(6) m(3). However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [-0.8;-0.4] × 10(9) kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 10(9) kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir.

  19. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano

    NASA Astrophysics Data System (ADS)

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond D’Ars, Jean; Komorowski, Jean-Christophe

    2016-09-01

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 106 m3 to 7 × 106 m3. However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [‑0.8‑0.4] × 109 kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 109 kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir.

  20. Explosive Material Identification via Neutron-Induced Gamma Rays

    NASA Astrophysics Data System (ADS)

    Freiberg, David; Litz, Marc

    2014-09-01

    With the increase in the usage of improvised explosive devices, both vehicle-borne and buried, it has become increasingly important to quickly identify potentially explosive materials before they can be detonated. In a field test performed in January of 2014, 14 MeV neutrons generated in a deuterium-tritium reaction induced gamma emissions in explosive material targets. The resulting gamma rays were counted in LaBr3 detectors in both a time-binned associated particle imaging (API) mode and a repetitively pulsed mode. The details of the resulting data sets were analyzed, and gamma lines for carbon, oxygen, and nitrogen were identified in the spectra produced by both modes. Post-test noise reduction techniques included empty hole background subtraction, Compton background subtraction, peak area integration, and time-of-flight gating. The induced C, O, and N gamma line intensities and ratios were compared to the elemental weight ratios expected for each type of material. The composition results are indicative of the known elemental weights in the target materials. The statistics are limited because of the short, 20 second data collection periods, and would improve greatly with longer exposure times in the future.

  1. Displacement damage induce degradation of COTS array CCDs irradiated by neutron beams from a nuclear reactor

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Chen, Wei; Xiao, Zhigang; Liu, Minbo; Huang, Shaoyan; He, Baoping; Luo, Tongding

    2015-01-01

    The experiments of displacement damage effects on COTS array charge coupled devices (CCDs) induced by neutron irradiation from a nuclear reactor are presented. The charge transfer inefficiency (CTI), saturation output signal voltage (VS), dynamic range (DR), dark signal, and camera imaging quality versus neutron fluence are investigated. The degradation mechanisms of the CCDs irradiated by reactor neutron beams are also analyzed. The CTI increase due to neutron displacement damage appears to be proportional to displacement damage dose. The experiments show that VS degradation induced by neutron irradiation is much less than that induced by gamma irradiation. The dark images from the CCDs irradiated by neutrons are given to investigate dark signal degradation. The degradation forms and mechanisms of the camera imaging quality are very different between the reactor neutron displacement damage and the gamma total ionization dose damage. The three samples were exposed by 1 MeV neutron-equivalent fluences of 1×1011, 5×1011, and 1×1012 n/cm2, respectively. A sample was exposed by 1 MeV neutron-equivalent fluences up to 2×1013 n/cm2, and the CCD is a functional failure after irradiation.

  2. Study of muon-induced neutron production using accelerator muon beam at CERN

    SciTech Connect

    Nakajima, Y.; Lin, C. J.; Ochoa-Ricoux, J. P.; Draeger, E.; White, C. G.; Luk, K. B.; Steiner, H.

    2015-08-17

    Cosmogenic muon-induced neutrons are one of the most problematic backgrounds for various underground experiments for rare event searches. In order to accurately understand such backgrounds, experimental data with high-statistics and well-controlled systematics is essential. We performed a test experiment to measure muon-induced neutron production yield and energy spectrum using a high-energy accelerator muon beam at CERN. We successfully observed neutrons from 160 GeV/c muon interaction on lead, and measured kinetic energy distributions for various production angles. Works towards evaluation of absolute neutron production yield is underway. This work also demonstrates that the setup is feasible for a future large-scale experiment for more comprehensive study of muon-induced neutron production.

  3. Angular signal radiography.

    PubMed

    Li, Panyun; Zhang, Kai; Bao, Yuan; Ren, Yuqi; Ju, Zaiqiang; Wang, Yan; He, Qili; Zhu, Zhongzhu; Huang, Wanxia; Yuan, Qingxi; Zhu, Peiping

    2016-03-21

    Microscopy techniques using visible photons, x-rays, neutrons, and electrons have made remarkable impact in many scientific disciplines. The microscopic data can often be expressed as the convolution of the spatial distribution of certain properties of the specimens and the inherent response function of the imaging system. The x-ray grating interferometer (XGI), which is sensitive to the deviation angle of the incoming x-rays, has attracted significant attention in the past years due to its capability in achieving x-ray phase contrast imaging with low brilliance source. However, the comprehensive and analytical theoretical framework is yet to be presented. Herein, we propose a theoretical framework termed angular signal radiography (ASR) to describe the imaging process of the XGI system in a classical, comprehensive and analytical manner. We demonstrated, by means of theoretical deduction and synchrotron based experiments, that the spatial distribution of specimens' physical properties, including absorption, refraction and scattering, can be extracted by ASR in XGI. Implementation of ASR in XGI offers advantages such as simplified phase retrieval algorithm, reduced overall radiation dose, and improved image acquisition speed. These advantages, as well as the limitations of the proposed method, are systematically investigated in this paper. PMID:27136780

  4. Neutron-induced gamma dose from a reactor beam filter for boron neutron capture therapy.

    PubMed

    Harrington, B V

    1989-01-01

    For the boron neutron capture therapy (NCT) of deep-seated metastatic melanoma, an epithermal (up to a few keV energy) neutron beam from a reactor horizontal facility could be useful if the inherent contamination from fast neutrons and gamma rays could be minimised. Calculations for ANSTO's 10 MW research reactor HIFAR have shown that, even though a filter material such as AlF3 attenuates the fast neutron dose, the beam quality improvement is counteracted by a relative increase in the gamma dose because of the gammas arising from neutron captures in the filter material, particularly the aluminium. The aluminium gammas, most of which arise from thermal neutron capture, are hard and cannot be attenuated by lead or bismuth without comparable attenuation of the epithermal neutron flux. Addition of an absorber such as 6Li to the AlF3 filter was investigated as a means of reducing the hard gamma dose, but the improvement in beam quality was small and at considerable cost to dose intensity. Dose characteristics calculations confirmed the superiority of a tangential beam over a radial beam with better results from an unfiltered tangential beam than from an AlF3 filter in a radial beam. This study showed conclusively that assessments of filter assemblies based on the effect of individual components on either the neutron or gamma dose in isolation are inadequate. In assessing any epithermal neutron filter, thermal neutron shield, and gamma shield combination, the total effect of each on the neutron, gamma, and boron-10 dose must be considered.

  5. Radioactive targets for neutron-induced cross section measurements

    SciTech Connect

    Kronenberg, A.; Bond, E. M.; Glover, S. E.; Rundberg, R. S.; Vieira, D. J.; Esch, E. I.; Reifarth, R.; Ullmann, J. L.; Haight, Robert C.; Rochmann, D.

    2004-01-01

    Measurements using radioactive targets are important for the determination of key reaction path ways associated with the synthesis of the elements in nuclear astrophysics (sprocess), advanced fuel cycle initiative (transmutation of radioactive waste), and stockpile stewardship. High precision capture cross-section measurements are needed to interpret observations, predict elemental or isotopical ratios, and unobserved abundances. There are two new detector systems that are presently being commissioned at Los Alamos National Laboratory for very precise measurements of (n,{gamma}) and (n,f) cross-sections using small quantities of radioactive samples. DANCE (Detector for Advanced Neutron-Capture Experiments), a 4 {pi} gamma array made up of 160 BaF{sub 2} detectors, is designed to measure neutron capture cross-sections of unstable nuclei in the low-energy range (thermal to {approx}500 keV). The high granularity and high detection efficiency of DANCE, combined with the high TOF-neutron flux available at the Lujan Center provides a versatile tool for measuring many important cross section data using radioactive and isotopically enriched targets of about 1 milligram. Another powerful instrument is the Lead-slowing down spectrometer (LSDS), which will enable the measurement of neutron-induced fission cross-section of U-235m and other short-lived actinides in a energy range from 1-200 keV with sample sizes down to 10 nanograms. Due to the short half-life of the U-235m isomer (T{sub 1/2} = 26 minutes), the samples must be rapidly and repeatedly extracted from its {sup 239}Pu parent. Since {sup 239}Pu is itself highly fissile, the separation must not only be rapid, but must also be of very high purity (the Pu must be removed from the U with a decontamination factor >10{sup 12}). Once extracted and purified, the {sup 235m}U isomer would be electrodeposited on solar cells as a fission detector and placed within the LSDS for direct (n,f) cross section measurements. The

  6. Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Chandler, K. C.; Barish, J.

    1972-01-01

    Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra were calculated using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron-leakage spectrum at the particular latitude considered support the theory that the cosmic-ray-albedo-neutron-decay mechanism is the source of the protons and electrons trapped in the Van Allen belts.

  7. Advantages of passive detectors for the determination of the cosmic ray induced neutron environment.

    PubMed

    Hajek, M; Berger, T; Schöner, W; Vana, N

    2002-01-01

    Due to the pronounced energy dependence of the neutron quality factor, accurate assessment of the biologically relevant dose requires knowledge of the spectral neutron fluence rate. Bonner sphere spectrometers (BSSs) are the only instruments which provide a sufficient response over practically the whole energy range of the cosmic ray induced neutron component. Measurements in a 62 MeV proton beam at Paul Scherrer Institute, Switzerland, and in the CERN-EU high-energy reference field led to the assumption that conventional active devices for the detection of thermal neutrons inside the BSS, e.g. 6Lil(Eu) scintillators, also respond to charged particles when used in high-energy mixed radiation fields. The effects of these particles cannot be suppressed by amplitude discrimination and are subsequently misinterpreted as neutron radiation. In contrast, paired TLD-600 and TLD-700 thermoluminescence dosemeters allow the determination of a net thermal neutron signal.

  8. Radioactivity induced by neutrons: Enrico Fermi and a thermodynamic approach to radiative capture

    NASA Astrophysics Data System (ADS)

    De Gregorio, Alberto

    2006-07-01

    When Fermi learned that slow neutrons are much more effective than fast ones in inducing radioactivity, he explained this phenomenon by mentioning the well-known scattering cross section between neutrons and protons. At this early stage, he did not refer to the capture cross section by target nuclei. At the same time a thermodynamic approach to neutron-proton capture was being discussed by physicists: neutron capture was interpretated as the reverse of deuteron photodissociation and detailed balance among neutrons, protons, deuterons, and radiation was invoked. This thermodynamic approach might underlie Fermi's early explanation of the great efficiency of slow neutrons. Fermi repeatedly used a thermodynamic approach that had been used in describing some of the physical properties of conductors by Richardson and had been influential in Fermi's youth.

  9. Neutron-induced 2.2 MeV background in gamma ray telescopes

    NASA Technical Reports Server (NTRS)

    Zanrosso, E. M.; Long, J. L.; Zych, A. D.; White, R. S.

    1985-01-01

    Neutron-induced gamma ray production is an important source of background in Compton scatter gamma ray telescopes where organic scintillator material is used. Most important is deuteron formation when atmospheric albedo and locally produced neutrons are thermalized and subsequently absorbed in the hydrogenous material. The resulting 2.2 MeV gamma ray line radiation essentially represents a continuous isotropic source within the scintillator itself. Interestingly, using a scintillator material with a high hydrogen-to-carbon ratio to minimize the scintillator material with a high hydrogen-to-carbon ratio to minimize the neutron-induced 4.4 MeV carbon line favors the np reaction. The full problem of neutron-induced background in Compton scatter telescopes has been previously discussed. Results are presented of observations with the University of California balloon-borne Compton scatter telescope where the 2.2 MeV induced line emission is prominently seen.

  10. Neutron micro-beam design simulation by Monte Carlo

    NASA Astrophysics Data System (ADS)

    Pazirandeh, Ali; Taheri, Ali

    2007-09-01

    Over the last two decades neutron micro-beam has increasingly been developing in view of various applications in molecular activation analysis, micro-radiography in space and aviation and in radiation induced bystander effects in bio-cells. In this paper the structure and simulation of a neutron micro-beam is presented. The collimator for micro-beam is made of a polyethylene cylinder with a small hole along the centerline of the cylinder. The hole is filled with very thin needles in triangular or rectangular arrangement. The neutron source was reactor neutrons or a spontaneous Cf-252 neutron source falling on the top side of the collimator. The outgoing thermal and epithermal neutron fluxes were calculated.

  11. Neutron-induced hydrogen and helium production in iron

    SciTech Connect

    Haight, Robert C.

    2004-01-01

    In support of the Advanced Fuel Cycle Initiative, cross sections for hydrogen and helium production by neutrons are being investigated on structural materials from threshold to 100 MeV with the continuous-in-energy spallation neutron source at the Los Alamos Neutron Science Center (LANSCE). The present measurements are for elemental iron. The results are compared with values from the ENDF/B-VI library and its extension with LA150 evaluations. For designs in the Advanced Fuel Cycle Initiative, structural materials will be subjected to very large fluences of neutrons, and the selection of these materials will be guided by their resistance to radiation damage. The macroscopic effects of radiation damage result both from displacement of atoms in the materials as well as nuclear transmutation. We are studying the production of hydrogen and helium by neutrons, because these gases can lead to significant changes in materials properties such as embrittlement and swelling. Our experiments span the full range from threshold to 100 MeV. The lower neutron energies are those characteristic of fission neutrons, whereas the higher energies are relevant for accelerator-based irradiation test facilities. Results for the nickel isotopes, {sup 58,60}Ni, have been reported previously. The present studies are on natural iron.

  12. Neutron induced inelastic cross sections of 150Sm for En = 1 to 35 MeV

    SciTech Connect

    Dashdorj, D; Mitchell, G E; Kawano, T; Becker, J A; Agvaanluvsan, U; Chadwick, M B; Cooper, J R; Devlin, M; Fotiades, N; Garrett, P E; Nelson, R O; Wu, C Y; Younes, W

    2006-08-16

    Cross-section measurements were made of prompt gamma-ray production as a function of incident neutron energy (E{sub n} = 1 to 35 MeV) on an enriched (95.6%) {sup 150}Sm sample. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the Los Alamos Neutron Science Center (LANSCE) facility. The prompt-reaction gamma rays were detected with the large-scale Compton-suppressed Germanium Array for Neutron Induced Excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The {gamma}-ray excitation functions were converted to partial {gamma}-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). Partial {gamma}-ray cross sections were predicted using the Hauser-Feshbach statistical reaction code GNASH. Above E{sub n} {approx} 8 MeV the pre-equilibrium reaction process dominates the inelastic reaction. The spin distribution transferred in pre-equilibrium neutron-induced reactions was calculated using the quantum mechanical theory of Feshbach, Kerman, and Koonin (FKK). These pre-equilibrium spin distributions were incorporated into a new version of GNASH and the {gamma}-ray production cross sections were calculated and compared with experimental data. The difference in the partial {gamma}-ray cross sections using spin distributions with and without pre-equilibrium effects is discussed.

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

    SciTech Connect

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

    2012-12-15

    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}.

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

    PubMed

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

    2012-12-01

    A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 × 10(5) n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He(4) nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T(3). PMID:23277984

  15. Neutron-Induced Fission Measurements at the Dance and Lsds Facilities at Lanl

    NASA Astrophysics Data System (ADS)

    Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Couture, A.; O'Donnell, J. M.; Fowler, M. M.; Haight, R. C.; Hayes-Sterbenz, A. C.; Rundberg, R. S.; Rusev, G. Y.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wu, C. Y.; Becker, J. A.; Alexander, C. W.; Belier, G.

    2014-09-01

    New results from neutron-induced fission measurements performed at the Detector for Advanced Neutron Capture Experiments (DANCE) and Lead Slowing Down Spectrometer (LSDS) are presented. New correlated data on promptfission γ-ray (PFG) distributions were measured using the DANCE array for resonant neutron-induced fission of 233U, 235U and 239Pu. The deduced properties of PFG emission are presented using a simple parametrization. An accurate knowledge of fission γ-ray spectra enables us to analyze the isomeric states of 236U created after neutron capture on 235U. We briefly discuss these new results. Finally, we review details and preliminary results of the challenging 237U(n,f) cross section measurement at the LSDS facility.

  16. Measurement of Neutron Induced and Spontaneous Fission in Pu-242 at DANCE

    NASA Astrophysics Data System (ADS)

    Chyzh, Andrii; Wu, C. Y.; Henderson, R.; Couture, A.; Lee, H. Y.; Ullmann, J.; O'Donnell, J. M.; Jandel, M.; Haight, R. C.; Bredeweg, T. A.; Dance Collaboration

    2013-10-01

    Neutron capture and fission reactions are important in nuclear engineering and physics. DANCE (Detector for Advanced Neutron Capture Measurement, LANL) combined with PPAC (avalanche technique based fission tagging detector, LLNL) were used to study neutron induced and spontaneous fission in 242Pu. 2 measurements were performed in 2013. The first experiment was done without the incident neutron beam with the fission tagging ability to study γ-rays emitted in the spontaneous fission of 242Pu. The second one - with the neutron beam to measure both the neutron capture and fission reactions. This is the first direct measurement of prompt fission γ-rays in 242Pu. The γ-ray multiplicity, γ-ray energy, and total energy of γ-rays per fission in 242Pu will be presented. These distributions of the 242Pu spontaneous fission will be compared to those in the 241Pu neutron induced fission. This work was performed under the auspices of the US Department of Energy by Los Alamos National Laboratory under Contract DE-AC52-06NA25396 and Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Trauma and Mobile Radiography

    SciTech Connect

    Drafke, M.W.

    1989-01-01

    Trauma and Mobile Radiography focuses on the radiography of trauma patients and of patients confined to bed. This book offers students a foundation in the skills they need to produce quality radiograms without causing additional injury or pain to the patient. Features of this new book include: coverage of the basics of radiography and patient care, including monitoring of heavily sedated, immobile, and accident patients. Information on the injuries associated with certain types of accidents, and methods for dealing with these problems. Detailed explanation of the positioning of each anatomical area. A Quick Reference Card with information on evaluating, monitoring and radiographing trauma patients.

  18. Measurements of activation induced by environmental neutrons using ultra low-level gamma-ray spectrometry.

    PubMed

    Martínez Canet, M J; Hult, M; Köhler, M; Johnston, P N

    2000-03-01

    The flux of environmental neutrons is being studied by activation of metal discs of selected elements. Near the earth's surface the total neutron flux is in the order of 10(-2) cm(-2)s(-1), which gives induced activities of a few mBq in the discs. Initial results from this technique, involving activation at ground level for several materials (W, Au, Ta, In, Re, Sm, Dy and Mn) and ultra low-level gamma-ray spectrometry in an underground laboratory located at 500 m.w.e., are presented. Diffusion of environmental neutrons in water is also measured by activation of gold at different depths.

  19. Neutron-induced fission measurements at the time-of-flight facility nELBE

    DOE PAGESBeta

    Kögler, T.; Beyer, R.; Junghans, A. R.; Massarczyk, R.; Schwengner, R.; Wagner, A.

    2015-05-18

    Neutron-induced fission of ²⁴²Pu is studied at the photoneutron source nELBE. The relative fast neutron fission cross section was determined using actinide fission chambers in a time-of-flight experiment. A good agreement of present nuclear data with evalua- tions has been achieved in the range of 100 keV to 10 MeV.

  20. Neutron source

    DOEpatents

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

    1975-10-21

    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.

  1. Simulating Makrofol as a detector for neutron-induced recoils.

    PubMed

    Zhang, G; Becker, F; Urban, M; Xuan, Y

    2011-03-01

    The response of solid-state nuclear track detector is extremely dependent on incident angles of neutrons, which determine the angular distribution of secondary particles. In this paper, the authors present a method to investigate the angular response of Makrofol detectors. Using the C++-based Monte-Carlo tool-kit Geant4 in combination with SRIM and our MATLAB codes, we simulated the angular response of Makrofol. The simulations were based on the restricted energy loss model, and the concept of energy threshold and critical angle. Experiments were carried out with (252)Cf neutrons to verify the simulation results.

  2. Colossal Light-Induced Refractive-Index Modulation for Neutrons in Holographic Polymer-Dispersed Liquid Crystals

    SciTech Connect

    Fally, Martin; Ellabban, Mostafa A.; Drevensek-Olenik, Irena; Pranzas, Klaus P.; Vollbrandt, Juergen

    2006-10-20

    We report strong diffraction of cold neutrons from an only 30 {mu}m thick holographic polymer-dispersed liquid crystal (H-PDLC) transmission grating. The light-induced refractive-index modulation for neutrons is about 10{sup -6}, i.e., nearly 2 orders of magnitude larger than in the best photo-neutron-refractive materials probed up to now. This makes H-PDLCs a promising candidate for fabricating neutron-optical devices.

  3. Molecular structural analysis of HPRT mutations induced by thermal and epithermal neutrons in Chinese hamster ovary cells.

    PubMed

    Kinashi, Y; Sakurai, Y; Masunaga, S; Suzuki, M; Takagaki, M; Akaboshi, M; Ono, K

    2000-09-01

    Chinese hamster ovary (CHO) cells were exposed to thermal and epithermal neutrons, and the occurrence of mutations at the HPRT locus was investigated. The Kyoto University Research Reactor (KUR), which has been improved for use in neutron capture therapy, was the neutron source. Neutron energy spectra ranging from nearly pure thermal to epithermal can be chosen using the spectrum shifters and thermal neutron filters. To determine mutant frequency and cell survival, cells were irradiated with thermal and epithermal neutrons under three conditions: thermal neutron mode, mixed mode with thermal and epithermal neutrons, and epithermal neutron mode. The mutagenicity was different among the three irradiation modes, with the epithermal neutrons showing a mutation frequency about 5-fold that of the thermal neutrons and about 1.5-fold that of the mixed mode. In the thermal neutron and mixed mode, boron did not significantly increase the frequency of the mutants at the same dose. Therefore, the effect of boron as used in boron neutron capture therapy (BNCT) is quantitatively minimal in terms of mutation induction. Over 300 independent neutron-induced mutant clones were isolated from 12 experiments. The molecular structure of HPRT mutations was determined by analysis of all nine exons by multiplex polymerase chain reaction. In the thermal neutron and mixed modes, total and partial deletions were dominant and the fraction of total deletions was increased in the presence of boron. In the epithermal neutron mode, more than half of the mutations observed were total deletions. Our results suggest that there are clear differences between thermal and epithermal neutron beams in their mutagenicity and in the structural pattern of the mutants that they induce. Mapping of deletion breakpoints of 173 partial-deletion mutants showed that regions of introns 3-4, 7/8-9 and 9-0 are sensitive to the induction of mutants by neutron irradiation.

  4. Active-Interrogation Measurements of Induced-Fission Neutrons from Low-Enriched Uranium

    SciTech Connect

    J. L. Dolan; M. J. Marcath; M. Flaska; S. A. Pozzi; D. L. Chichester; A. Tomanin; P. Peerani; G. Nebbia

    2012-07-01

    Protection and control of nuclear fuels is paramount for nuclear security and safeguards; therefore, it is important to develop fast and robust controlling mechanisms to ensure the safety of nuclear fuels. Through both passive- and active-interrogation methods we can use fast-neutron detection to perform real-time measurements of fission neutrons for process monitoring. Active interrogation allows us to use different ranges of incident neutron energy to probe for different isotopes of uranium. With fast-neutron detectors, such as organic liquid scintillation detectors, we can detect the induced-fission neutrons and photons and work towards quantifying a sample’s mass and enrichment. Using MCNPX-PoliMi, a system was designed to measure induced-fission neutrons from U-235 and U-238. Measurements were then performed in the summer of 2010 at the Joint Research Centre in Ispra, Italy. Fissions were induced with an associated particle D-T generator and an isotopic Am-Li source. The fission neutrons, as well as neutrons from (n, 2n) and (n, 3n) reactions, were measured with five 5” by 5” EJ-309 organic liquid scintillators. The D-T neutron generator was available as part of a measurement campaign in place by Padova University. The measurement and data-acquisition systems were developed at the University of Michigan utilizing a CAEN V1720 digitizer and pulse-shape discrimination algorithms to differentiate neutron and photon detections. Low-enriched uranium samples of varying mass and enrichment were interrogated. Acquired time-of-flight curves and cross-correlation curves are currently analyzed to draw relationships between detected neutrons and sample mass and enrichment. In the full paper, the promise of active-interrogation measurements and fast-neutron detection will be assessed through the example of this proof-of-concept measurement campaign. Additionally, MCNPX-PoliMi simulation results will be compared to the measured data to validate the MCNPX-PoliMi code

  5. Recovering Root System Traits Using Image Analysis Exemplified by Two-Dimensional Neutron Radiography Images of Lupine1[C][W][OPEN

    PubMed Central

    Leitner, Daniel; Felderer, Bernd; Vontobel, Peter; Schnepf, Andrea

    2014-01-01

    Root system traits are important in view of current challenges such as sustainable crop production with reduced fertilizer input or in resource-limited environments. We present a novel approach for recovering root architectural parameters based on image-analysis techniques. It is based on a graph representation of the segmented and skeletonized image of the root system, where individual roots are tracked in a fully automated way. Using a dynamic root architecture model for deciding whether a specific path in the graph is likely to represent a root helps to distinguish root overlaps from branches and favors the analysis of root development over a sequence of images. After the root tracking step, global traits such as topological characteristics as well as root architectural parameters are computed. Analysis of neutron radiographic root system images of lupine (Lupinus albus) grown in mesocosms filled with sandy soil results in a set of root architectural parameters. They are used to simulate the dynamic development of the root system and to compute the corresponding root length densities in the mesocosm. The graph representation of the root system provides global information about connectivity inside the graph. The underlying root growth model helps to determine which path inside the graph is most likely for a given root. This facilitates the systematic investigation of root architectural traits, in particular with respect to the parameterization of dynamic root architecture models. PMID:24218493

  6. Neutron-induced reactions in the hohlraum to study reaction in flight neutrons

    NASA Astrophysics Data System (ADS)

    Boswell, M. S.; Elliott, S. R.; Guiseppe, V.; Kidd, M.; Rundberg, B.; Tybo, J.

    2013-04-01

    We are currently developing the physics necessary to measure the Reaction In Flight (RIF) neutron flux from a NIF capsule. A measurement of the RIF neutron flux from a NIF capsule could be used to deduce the stopping power in the cold fuel of the NIF capsule. A foil irradiated at the Omega laser at LLE was counted at the LANL low-background counting facility at WIPP. The estimated production rate of 195Au was just below our experimental sensitivity. We have made several improvements to our counting facility in recent months. These improvements are designed to increase our sensitivity, and include installing two new low-background detectors, and taking steps to reduce noise in the signals.

  7. Active-Interrogation Measurements of Fast Neutrons from Induced Fission in Low-Enriched Uranium

    SciTech Connect

    J. L. Dolan; M. J. Marcath; M. Flaska; S. A. Pozzi; D. L. Chichester; A. Tomanin; P. Peerani

    2014-02-01

    A detection system was designed with MCNPX-PoliMi to measure induced-fission neutrons from U-235 and U-238 using active interrogation. Measurements were then performed with this system at the Joint Research Centre (JRC) in Ispra, Italy on low-enriched uranium samples. Liquid scintillators measured induced fission neutron to characterize the samples in terms of their uranium mass and enrichment. Results are presented to investigate and support the use of organic liquid scintillators with active interrogation techniques to characterize uranium containing materials.

  8. Determination of the cosmic-ray-induced neutron flux and ambient dose equivalent at flight altitude

    NASA Astrophysics Data System (ADS)

    Pazianotto, M. T.; Cortés-Giraldo, M. A.; Federico, C. A.; Gonçalez, O. L.; Quesada, J. M.; Carlson, B. V.

    2015-07-01

    There is interest in modeling the atmosphere in the South Atlantic Magnetic Anomaly in order to obtain information about the cosmic-ray induced neutron spectrum and angular distribution as functions of altitude. In this work we use the Monte Carlo codes MCNPX and Geant4 to determine the cosmic-ray-induced neutron flux in the atmosphere produced by the cosmic ray protons incident on the top of the atmosphere and to estimate the ambient dose equivalent rate as function of altitude. The results present a reasonable conformity to other codes (QARM and EXPACS) based on other parameterizations.

  9. Isospin effects on fragmentation in the asymmetric reactions induced by neutron-rich targets

    NASA Astrophysics Data System (ADS)

    Sharma, Arun

    2016-05-01

    To understand the isospin effects in terms of fragment's yield in the asymmetric reactions induced by neutron-rich targets, we perform a theoretical study using isospin-dependent quantum molecular dynamics (IQMD) model. Simulations are carried out for reactions of 16O+Br80,84,92 and 16O+Ag108,113,122. We envision that fragments's yield in the asymmetric collisions induced by neutron-rich targets is better candidate to study isospin effects via symmetry energy and nucleon-nucleon (nn) cross-sections. Also, pronounced effects of symmetry energy and cross-sections can be found at lower and higher beam energies, respectively.

  10. Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays.

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Chandler, K. C.; Barish, J.

    1973-01-01

    Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra in the energy range from about 10 to the minus 8th to about 100,000 MeV at various depths in the atmosphere were calculated by using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron leakage spectrum at the particular latitude considered support the theory that the cosmic ray albedo neutron decay (Crand) mechanism is the source of the protons trapped in the inner radiation belt.

  11. Using Ultracold Neutrons to Characterize Fission Fragment Induced Sputtering

    NASA Astrophysics Data System (ADS)

    Broussard, Leah; Makela, Mark; Morris, Chris

    2015-10-01

    One of the modern challenges in nuclear science and technology is the understanding of the nature of fission fragment damage to material and the resulting ejection of matter as the fragments pass through the surface, with implications to stockpile stewardship and nuclear energy. We have demonstrated a new technique that can be used to characterize the sputtered material with knowledge of the location of the originating fission event. Due to their very high fission cross sections, ultracold neutrons (~100 neV energy) can be used to control the depth at which fission takes place using their energy or the material enrichment. This effort represents one of the first practical applications of ultracold neutrons, which to date have been primarily used to explore questions in fundamental particle physics. We will present results of demonstration measurements including first limits on the total and fission cross sections for 100 neV scale neutrons and the status of the development of this new capability. We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program, the G. T. Seaborg Institute, and LANL Science Campaign C1 for this work.

  12. Chromosomal abnormalities in neutron-induced acute myeloid leukemias in CBA/H mice

    SciTech Connect

    Bouffler, S.D.; Meijne, E.I.M.; Huiskamp, R.

    1996-09-01

    Acute myeloid leukemias (AMLs) induced in CBA/H mice by 1 MeV fission neutrons have been examined for chromosomal abnormalities by G-band analysis. In common with X-ray- and {alpha}-particle-induced AMLs in CBA/H mice, more than 90% (16/17) of the myeloid leukemias had chromosome 2 abnormalities, in this case, all interstitial deletions. Chromosome 2 breakpoints were not wholly consistent, but clustering in three specific G-band regions was observed. Very distal (H-region) breakpoints were more common in the neutron AMLs than in X-ray- or {alpha}-particle-induced leukemias. These data indicate that neutron-induced AMLs in CBA/H mice are not characterized by a specific chromosome deletion but that a variety of chromosome 2 deletion types are associated with the disease. Trisomy of chromosome 1 (12.5% AMLs) and aneusomy of chromosomes 6 (31% AMLs) and Y (37.5% AMLs) were noted. While chromatid breakage was observed occasionally in neutron-induced AML, no clear indications of persistent chromosomal instability or high levels of stable chromosomal change were apparent. 19 refs., 1 fig., 1 tab.

  13. 8. VIEW OF RADIOGRAPHY EQUIPMENT, TEST METHODS INCLUDED RADIOGRAPHY AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF RADIOGRAPHY EQUIPMENT, TEST METHODS INCLUDED RADIOGRAPHY AND BETA BACKSCATTERING. (7/13/56) - Rocky Flats Plant, Non-Nuclear Production Facility, South of Cottonwood Avenue, west of Seventh Avenue & east of Building 460, Golden, Jefferson County, CO

  14. Thorium-uranium fission radiography

    NASA Technical Reports Server (NTRS)

    Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

    1976-01-01

    Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

  15. Neutron-induced gamma ray spectroscopy: Simulations for chemical mapping of planetary surfaces

    NASA Astrophysics Data System (ADS)

    Brückner, J.; Wänke, H.; Reedy, R. C.

    Cosmic rays interact with the surface of a planetary body and produce a cascade of secondary particles, such as neutrons. Neutron-induced scattering and capture reactions play an important role in the production of discrete gamma ray lines that can be measured by a gamma ray spectrometer on board an orbiting spacecraft. These data can be used to determine the concentration of many elements in the surface of a planetary body, which enables us to recognize individual geological units and provides clues to the bulk composition and in turn the origin and evolution of the body. To investigate the gamma ray fluxes induced by accelerator neutrons, experiments were carried out by irradiating thin targets with neutrons of energies from 14 MeV to 0.025 eV. The neutron fluxes at target position were measured by foil activation techniques. The ratio of the epithermal to thermal neutron flux was determined to be 2.0, a value that is similar to that in the moon. Gamma rays in the energy range of 0.1 to 8 MeV emitted by the targets and the surrounding material were measured by a high-resolution germanium detector. Most of the gamma ray lines that are expected to be used for planetary gamma ray Spectroscopy were found in the recorded spectra. These spectra were unfolded, background was subtracted, and gamma ray attenuation corrections were made to obtain the corresponding gamma ray fluxes from the targets. The majority of gamma ray lines were narrow without noticeable Doppler broadening except for the very broad 4.4-MeV line of carbon and five asymmetric germanium lines produced by the detector itself. The agreement of measured gamma ray flux ratios with calculated flux ratios for neutron-capture reactions showed that thermal neutron data can be used for theoretical calculations of low-energy neutron-induced gamma ray fluxes. This study was a first step toward a more realistic simulation of cosmic-ray-induced gamma-ray production and it indicates the importance of accelerator

  16. Neutron-induced gamma ray spectroscopy: Simulations for chemical mapping of planetary surfaces

    NASA Astrophysics Data System (ADS)

    Brückner, J.; Wänke, H.; Reedy, R. C.

    1987-09-01

    Cosmic rays interact with the surface of a planetary body and produce a cascade of secondary particles, such as neutrons. Neutron-induced scattering and capture reactions play an important role in the production of discrete gamma ray lines that can be measured by a gamma ray spectrometer on board an orbiting spacecraft. These data can be used to determine the concentration of many elements in the surface of a planetary body, which enables us to recognize individual geological units and provides clues to the bulk composition and in turn the origin and evolution of the body. To investigate the gamma ray fluxes induced by accelerator neutrons, experiments were carried out by irradiating thin targets with neutrons of energies from 14 MeV to 0.025 eV. The neutron fluxes at target position were measured by foil activation techniques. The ratio of the epithermal to thermal neutron flux was determined to be 2.0, a value that is similar to that in the moon. Gamma rays in the energy range of 0.1 to 8 MeV emitted by the targets and the surrounding material were measured by a high-resolution germanium detector. Most of the gamma ray lines that are expected to be used for planetary gamma ray spectroscopy were found in the recorded spectra. These spectra were unfolded, background was subtracted, and gamma ray attenuation corrections were made to obtain the corresponding gamma ray fluxes from the targets. The majority of gamma ray lines were narrow without noticeable Doppler broadening except for the very broad 4.4-MeV line of carbon and five asymmetric germanium lines produced by the detector itself. The agreement of measured gamma ray flux ratios with calculated flux ratios for neutron-capture reactions showed that thermal neutron data can be used for theoretical calculations of low-energy neutron-induced gamma ray fluxes. This study was a first step toward a more realistic simulation of cosmic-ray-induced gamma-ray production and it indicates the importance of accelerator

  17. Displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor

    SciTech Connect

    Wang, Zujun Huang, Shaoyan; Liu, Minbo; Xiao, Zhigang; He, Baoping; Yao, Zhibin; Sheng, Jiangkun

    2014-07-15

    The experiments of displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor are presented. The CMOS APS image sensors are manufactured in the standard 0.35 μm CMOS technology. The flux of neutron beams was about 1.33 × 10{sup 8} n/cm{sup 2}s. The three samples were exposed by 1 MeV neutron equivalent-fluence of 1 × 10{sup 11}, 5 × 10{sup 11}, and 1 × 10{sup 12} n/cm{sup 2}, respectively. The mean dark signal (K{sub D}), dark signal spike, dark signal non-uniformity (DSNU), noise (V{sub N}), saturation output signal voltage (V{sub S}), and dynamic range (DR) versus neutron fluence are investigated. The degradation mechanisms of CMOS APS image sensors are analyzed. The mean dark signal increase due to neutron displacement damage appears to be proportional to displacement damage dose. The dark images from CMOS APS image sensors irradiated by neutrons are presented to investigate the generation of dark signal spike.

  18. Fast Neutron Induced Autophagy Leads To Necrosis In Glioblastoma Multiforme Cells

    NASA Astrophysics Data System (ADS)

    Yasui, Linda; Gladden, Samantha; Andorf, Christine; Kroc, Thomas

    2011-06-01

    Fast neutrons are highly effective at killing glioblastoma multiforme (GBM), U87 and U251 cells. The mode of cell death was investigated using transmission electron microscopy (TEM) to identify the fraction of irradiated U87 or U251 cells having morphological features of autophagy and/or necrosis. U87 or U251 cells were irradiated with 2 Gy fast neturons or 10 Gy γ rays. A majority of U87 and U251 cells exhibit features of cell death with autophagy after irradiation with either 10 Gy γ rays or 2 Gy fast neutrons. Very few γ irradiated cells had features of necrosis (U87 or U251 cell samples processed for TEM 1 day after 10 Gy γ irradiation). In contrast, a significant increase was observed in necrotic U87 and U251 cells irradiated with fast neutrons. These results show a greater percentage of cells exhibit morphological evidence of necrosis induced by a lower dose of fast neutron irradiation compared to γ irradiation. Also, the evidence of necrosis in fast neutron irradiated U87 and U251 cells occurs in a background of autophagy. Since autophagy is observed before necrosis, autophagy may play a role in signaling programmed necrosis in fast neutron irradiated U87 and U251 cells.

  19. Fast Neutron Induced Autophagy Leads To Necrosis In Glioblastoma Multiforme Cells

    SciTech Connect

    Yasui, Linda; Gladden, Samantha; Andorf, Christine; Kroc, Thomas

    2011-06-01

    Fast neutrons are highly effective at killing glioblastoma multiforme (GBM), U87 and U251 cells. The mode of cell death was investigated using transmission electron microscopy (TEM) to identify the fraction of irradiated U87 or U251 cells having morphological features of autophagy and/or necrosis. U87 or U251 cells were irradiated with 2 Gy fast neturons or 10 Gy {gamma} rays. A majority of U87 and U251 cells exhibit features of cell death with autophagy after irradiation with either 10 Gy {gamma} rays or 2 Gy fast neutrons. Very few {gamma} irradiated cells had features of necrosis (U87 or U251 cell samples processed for TEM 1 day after 10 Gy {gamma} irradiation). In contrast, a significant increase was observed in necrotic U87 and U251 cells irradiated with fast neutrons. These results show a greater percentage of cells exhibit morphological evidence of necrosis induced by a lower dose of fast neutron irradiation compared to {gamma} irradiation. Also, the evidence of necrosis in fast neutron irradiated U87 and U251 cells occurs in a background of autophagy. Since autophagy is observed before necrosis, autophagy may play a role in signaling programmed necrosis in fast neutron irradiated U87 and U251 cells.

  20. Are neutron stars crushed? Gravitomagnetic tidal forces as a mechanism for binary-induced collapse

    NASA Astrophysics Data System (ADS)

    Favata, Marc; Thorne, Kip S.

    2002-04-01

    Numerical simulations of coalescing binary neutron stars performed by Wilson, Mathews, and Marronetti indicated that a binary companion could cause a stable neutron star to undergo gravitational collapse prior to merger if the neutron star is close to its maximum allowed mass. Subsequent studies by several authors failed to explain this surprising effect. Although Flanagan’s correction accounted for most of the effect, a small residual compression remained. This has prompted us to ask: what physical mechanism, if any, could cause binary-induced compression of a neutron star? We have found that a compressive force can exist when gravitomagnetic tidal fields, generated by the companion's orbital motion, couple to certain velocity patterns (or modes of stellar oscillation) in the neutron star. Specifically, we find that if one decomposes the star's fluid velocity into a sum over vector spherical harmonics, a radial compression force exists for certain vector harmonic indices. However, this force can only affect stability if the star is already very close to its maximum mass. We derive expressions for the evolution of the star's fundamental radial mode (along which compression and expansion occur) and the change in the central density. We also estimate how close a neutron star needs to be to its maximum mass in order for this compression to initiate gravitational collapse. Our analysis demonstrates techniques that can be applied to the study of relativistic tidal fields on various modes of stellar oscillation.

  1. Continuous versus pulse neutron induced gamma spectroscopy for soil carbon analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neutron induced gamma spectra analysis (NGA) provides a means of measuring carbon in large soil volumes without destructive sampling. Calibration of the NGA system must account for system background and the interference of other nuclei on the carbon peak at 4.43 MeV. Accounting for these factors pro...

  2. Real-time radiography

    SciTech Connect

    Bossi, R.H.; Oien, C.T.

    1981-02-26

    Real-time radiography is used for imaging both dynamic events and static objects. Fluorescent screens play an important role in converting radiation to light, which is then observed directly or intensified and detected. The radiographic parameters for real-time radiography are similar to conventional film radiography with special emphasis on statistics and magnification. Direct-viewing fluoroscopy uses the human eye as a detector of fluorescent screen light or the light from an intensifier. Remote-viewing systems replace the human observer with a television camera. The remote-viewing systems have many advantages over the direct-viewing conditions such as safety, image enhancement, and the capability to produce permanent records. This report reviews real-time imaging system parameters and components.

  3. The measurement of gamma ray induced heating in a mixed neutron and gamma ray environment

    SciTech Connect

    Chiu, H.K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one- dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC{sup 2}-2 for the case of DT neutrons slowing down in a low-Z material. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The gamma energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations.

  4. Neutron Induced D Breakup in Inertial Confinement Fusion at the Omega Laser Facility

    NASA Astrophysics Data System (ADS)

    Forrest, C. J.; Glebov, V. Yu.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.; Schroder, W. U.; Frenje, J. A.; Gatu Johnson, M.

    2015-11-01

    High-resolution neutron spectroscopy is used to study the deuteron breakup reaction D(n,n ') np in the thermonuclear environment created in inertial confinement fusion experiments at the Omega Laser Facility. Neutrons with an energy of 14.1 MeV generated in the primary D-T fusion reactions scatter elastically and inelastically off the dense (cryogenic) D-T fuel assembly surrounding the central hot spot at peak fuel compression. These neutrons also induce a breakup of the fuel deuterons. The corresponding breakup cross section is measured relative to elastic n -D and n -T scattering, i.e., simultaneously in the same environment. Apart from astrophysical and technological interest, the neutron-induced deuteron breakup reaction is of interest to the physics of nucleon -nucleon forces. For example, theoretical calculations predict a noticeable influence of nucleonic three-body forces on the magnitude of the breakup cross section. Preliminary results from measurements of the neutron contribution in the 2- to 6-MeV range show reasonable agreement with the published ENDL 2008.2 semi-empirical cross-section. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  5. Study of the beam-induced neutron flux and required shielding for DIANA

    NASA Astrophysics Data System (ADS)

    Best, Andreas; Couder, Manoel; Famiano, Michael; Lemut, Alberto; Wiescher, Michael

    2013-11-01

    Low energy accelerators in underground locations have emerged as a powerful tool for the measurement of critical nuclear reactions for the study of energy production and element synthesis in astrophysics. While cosmic ray induced background is substantially reduced, beam induced background on target impurities and depositions on target and collimator materials remain a matter of serious concern. The Dual Ion Accelerator for Nuclear Astrophysics (DIANA) is proposed to operate as a low-level background facility in an underground location. One of the main goals of DIANA is the study of neutron sources in stellar helium burning. For these experiments DIANA is a neutron radiation source which may affect other nearby low background level experiments. We therefore investigated the required laboratory layout to attenuate the neutron flux generated in a worst-case scenario to a level below the natural background in the underground environment. Detailed Monte Carlo calculations of the neutron propagation in the laboratory show that a neutron flux many orders of magnitude above expected values gets attenuated below the natural background rate using a 1 m thick water-shielded door as well as an emergency access/egress maze.

  6. Evaluated Mean Values and Covariances for the Prompt Fission Neutron Spectrum of 239Pu induced by neutrons of 500 keV

    SciTech Connect

    Neudecker, Denise

    2014-07-10

    This document provides the numerical values of the evaluated prompt fission neutron spectrum for 239Pu induced by neutrons of 500 keV as well as relative uncertainties and correlations. This document also contains a short description how these data were obtained and shows plots comparing the evaluated results to experimental information as well as the corresponding ENDF/B-VII.1 evaluation.

  7. Closed-Loop Performance Measures for Flight Controllers Subject to Neutron-Induced Upsets

    NASA Technical Reports Server (NTRS)

    Gray, W. Steven; Zhang, Hong; Gonzalex, Oscar R.

    2003-01-01

    It has been observed that atmospheric neutrons can produce single event upsets in digital flight control hardware. The phenomenon has been studied extensively at the chip level, and now system level experiments are underway. In this paper analytical closed-loop performance measures for the tracking error are developed for a plant that is stabilized by a recoverable computer system subject to neutron induced upsets. The underlying model is a Markov jump-linear system with process noise. The steady-state tracking error is expressed in terms of a generalized observability Gramian.

  8. Characterization of the CRESST detectors by neutron induced nuclear recoils

    NASA Astrophysics Data System (ADS)

    Coppi, C.; Ciemniak, C.; von Feilitzsch, F.; Gütlein, A.; Hagn, H.; Isaila, C.; Jochum, J.; Kimmerle, M.; Lanfranchi, J.-C.; Pfister, S.; Potzel, W.; Rau, W.; Roth, S.; Rottler, K.; Sailer, C.; Scholl, S.; Usherov, I.; Westphal, W.

    CRESST is an experiment for the direct detection of dark matter particles via nuclear recoils. The CRESST detectors, based on CaWO4 scintillating crystals, are able to discriminate γ and β background by simultaneously measuring the light and phonon signals produced by particle interactions. The discrimination of the background is possible because of the different light output (Quenching Factor, QF) for nuclear and electron recoils. In this article a measurement is shown, aimed at the determination of the QFs of the different nuclei (O, Ca, W) of the detector crystal at 40-60 mK using an 11 MeV neutron beam produced at the Maier-Leibnitz-Laboratorium in Garching (MLL).

  9. A measurement of the muon-induced neutron yield in lead at a depth of 2850 m water equivalent

    SciTech Connect

    Reichhart, L.; Ghag, C.; Lindote, A.; Chepel, V.; DeViveiros, L.; Lopes, M. I.; Neves, F.; Pinto da Cunha, J.; Silva, C.; Solovov, V. N.; Akimov, D. Yu.; Belov, V. A.; Burenkov, A. A.; Kobyakin, A. S.; Kovalenko, A. G.; Stekhanov, V. N.; Araújo, H. M.; Bewick, A.; Currie, A.; Horn, M.; and others

    2013-08-08

    We present results from the measurement of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850 m water equivalent (mean muon energy of 260 GeV). A tonne-scale highly segmented plastic scintillator detector was utilised to detect both the energy depositions from the traversing muons as well as the delayed radiative capture signals of the induced neutrons. Complementary Monte Carlo simulations reproduce well the distributions of muons and detected muon-induced neutrons. Absolute agreement between simulation and data is of the order of 25%. By comparing the measured and simulated neutron capture rates a neutron yield in pure lead of (5.78{sub −0.28}{sup +0.21})×10{sup −3} neutrons/muon/(g/cm{sup 2}) has been obtained.

  10. Neutron emission effects on fragment mass and kinetic energy distribution from fission of 239{sup Pu} induced by thermal neutrons

    SciTech Connect

    Montoya, M.; Rojas, J.; Lobato, I.

    2010-08-04

    The average of fragment kinetic energy (E-bar sign*) and the multiplicity of prompt neutrons ({nu}(bar sign)) as a function of fragment mass (m*), as well as the fragment mass yield (Y(m*)) from thermal neutron-induced fission of {sup 239}Pu have been measured by Tsuchiya et al.. In that work the mass and kinetic energy are calculated from the measured kinetic energy of one fragment and the difference of time of flight of the two complementary fragments. However they do not present their results about the standard deviation {sigma}{sub E}*(m*). In this work we have made a numerical simulation of that experiment which reproduces its results, assuming an initial distribution of the primary fragment kinetic energy (E(A)) with a constant value of the standard deviation as function of fragment mass ({sigma}{sub E}(A)). As a result of the simulation we obtain the dependence {sigma}{sub E}*(m*) which presents an enhancement between m* = 92 and m* = 110, and a peak at m* = 121.

  11. Fast neutrons-induced apoptosis is Fas-independent in lymphoblastoid cells

    SciTech Connect

    Fischer, Barbara; Benzina, Sami; Jeannequin, Pierre; Dufour, Patrick; Bergerat, Jean-Pierre; Denis, Jean-Marc; Gueulette, John; Bischoff, Pierre L. . E-mail: Pierre.Bischoff@ircad.u-strasbg.fr

    2005-08-26

    We have previously shown that ionizing radiation-induced apoptosis in human lymphoblastoid cells differs according to their p53 status, and that caspase 8-mediated cleavage of BID is involved in the p53-dependent pathway. In the present study, we investigated the role of Fas signaling in caspase 8 activation induced by fast neutrons irradiation in these cells. Fas and FasL expression was assessed by flow cytometry and by immunoblot. We also measured Fas aggregation after irradiation by fluorescence microscopy. We found a decrease of Fas expression after irradiation, but no change in Fas ligand expression. We also showed that, in contrast to the stimulation of Fas by an agonistic antibody, Fas aggregation did not occur after irradiation. Altogether, our data strongly suggest that fast neutrons induced-apoptosis is Fas-independent, even in p53-dependent apoptosis.

  12. In-situ measurement of the rate of U-235 fission induced by lunar neutrons

    NASA Technical Reports Server (NTRS)

    Woolum, D. S.; Burnett, D. S.

    1974-01-01

    The depth profile of the neutron-induced fission rate of U-235 was directly measured to a depth of 350 g/sq cm by the Apollo 17 Lunar Neutron Probe Experiment. The fission rate rises sharply from the surface to a broad maximum from 110 to 160 g/sq cm and drops off at greater depths. The shape of the theoretical depth profile of Lingenfelter et al (1972) fits the measured capture rates well at all depths. The absolute magnitude of the experimental fission rates are (11 plus or minus 17)% lower than those calculated theoretically. The excellent agreement between theory and experiment implies that conclusions drawn previously by interpreting lunar sample data with the theoretical capture rates will not require revision. In particular, lunar surface processes, rather than uncertainties in the capture rates, are required to explain the relatively low neutron fluences observed for surface soil samples compared to the fluences expected for a uniformly mixed regolith.

  13. Neutron-induced reactions on AlF3 studied using the optical model

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Lv, Cui-Juan; Zhang, Guo-Qiang; Wang, Hong-Wei; Zuo, Jia-Xu

    2015-08-01

    Neutron-induced reactions on 27Al and 19F nuclei are investigated using the optical model implemented in the TALYS 1.4 toolkit. Incident neutron energies in a wide range from 0.1 keV to 30 MeV are calculated. The cross sections for the main channels (n, np), (n, p), (n, α), (n, 2n), and (n, γ) and the total reaction cross section (n, tot) of the reactions are obtained. When the default parameters in TALYS 1.4 are adopted, the calculated results agree with the measured results. Based on the calculated results for the n + 27Al and n + 19F reactions, the results of the n + 27Al19F reactions are predicted. These results are useful both for the design of thorium-based molten salt reactors and for neutron activation analysis techniques.

  14. Analysis of the Nuclear Structure of 186 Re Using Neutron-Induced Reactions

    NASA Astrophysics Data System (ADS)

    Matters, David; McClory, John; Carroll, James; Chiara, Chris; Fotiades, Nikolaos; Devlin, Matt; Nelson, Ron O.

    2015-04-01

    Evaluated nuclear structure data for 186 Re identifies the majority of spin-parity assignments as tentative, with approximate values associated with the energies of several levels and transitions. In particular, the absence of known transitions that feed the Jπ =8+ isomer motivates their discovery, which would have astrophysical implications and a potential application in the development of an isomer power source. Using the GErmanium Array for Neutron Induced Excitations (GEANIE) spectrometer at the Los Alamos Neutron Science Center (LANSCE) Weapons Neutron Research (WNR) facility, the (n,2n γ) and (n,n' γ) reactions in a 99.52% enriched 187 Re target were used to measure γ-ray excitation functions in 186 Re and 187 Re, respectively. A preliminary analysis of the data obtained from the experiment reveals several new transitions in 186 Re and 187 Re.

  15. Neutron-Induced Fission Cross Section Measurements for Full Suite of Uranium Isotopes

    NASA Astrophysics Data System (ADS)

    Laptev, Alexander; Tovesson, Fredrik; Hill, Tony

    2010-11-01

    A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R&D). The incident neutron energy range spans energies from sub-thermal energies up to 200 MeV by measuring both the Lujan Center and the Weapons Neutron Research center (WNR). Conventional parallel-plate fission ionization chambers with actinide deposited foils are used as a fission detector. The time-of-flight method is implemented to measure neutron energy. Counting rate ratio from investigated and standard U-235 foils is translated into fission cross section ratio. Different methods of normalization for measured ratio are employed, namely, using of actinide deposit thicknesses, normalization to evaluated data, etc. Finally, ratios are converted to cross sections based on the standard U-235 fission cross section data file. Preliminary data for newly investigated isotopes U-236 and U-234 will be reported. Those new data complete a full suite of Uranium isotopes, which were investigated with presented experimental approach. When analysis of the new measured data will is completed, data will be delivered to evaluators. Having data for full set of Uranium isotopes will increase theoretical modeling capabilities and make new data evaluations much more reliable.

  16. Neutron-induced gamma-ray spectroscopy: simulations for chemical mapping of planetary surfaces

    SciTech Connect

    Brueckner, J.; Waenke, H.; Reedy, R.C.

    1986-01-01

    Cosmic rays interact with the surface of a planetary body and produce a cascade of secondary particles, such as neutrons. Neutron-induced scattering and capture reactions play an important role in the production of discrete gamma-ray lines that can be measured by a gamma-ray spectrometer on board of an orbiting spacecraft. These data can be used to determine the concentration of many elements in the surface of a planetary body, which provides clues to its bulk composition and in turn to its origin and evolution. To investigate the gamma rays made by neutron interactions, thin targets were irradiated with neutrons having energies from 14 MeV to 0.025 eV. By means of foil activation technique the ratio of epithermal to thermal neutrons was determined to be similar to that in the Moon. Gamma rays emitted by the targets and the surrounding material were detected by a high-resolution germanium detector in the energy range of 0.1 to 8 MeV. Most of the gamma-ray lines that are expected to be used for planetary gamma-ray spectroscopy were found in the recorded spectra and the principal lines in these spectra are presented. 58 refs., 7 figs., 9 tabs.

  17. Neutron induced damage in reactor pressure vessel steel: An X-ray absorption fine structure study

    NASA Astrophysics Data System (ADS)

    Kuri, G.; Cammelli, S.; Degueldre, C.; Bertsch, J.; Gavillet, D.

    2009-03-01

    The radiation damage produced in reactor pressure vessel (RPV) steels during neutron irradiation is a long-standing problem of considerable practical interest. In this study, an extended X-ray absorption fine structure (EXAFS) spectroscopy has been applied at Cu, Ni and Mn K-edges to systematically investigate neutron induced radiation damage to the metal-site bcc structure of RPV steels, irradiated with neutrons in the fluence range from 0.85 to 5.0 × 1019 cm-2. An overall similarity of Cu, Ni and Mn atomic environment in the iron matrix is observed. The radial distribution functions (RDFs), derived from EXAFS data have been found to evolve continuously as a function of neutron fluence describing the atomic-scale structural modifications in RPVs by neutron irradiations. From the pristine data, long range order beyond the first- and second-shell is apparent in the RDF spectra. In the irradiated specimens, all near-neighbour peaks are greatly reduced in magnitude, typical of damaged material. Prolonged annealing leads annihilation of point defects to give rise to an increase in the coordination numbers of near-neighbour atomic shells approaching values close to that of non-irradiated material, but does not suppress the formation of nano-sized Cu and/or Ni-rich-precipitates. Total amount of radiation damage under a given irradiation condition has been determined. The average structural parameters estimated from the EXAFS data are presented and discussed.

  18. Fast-neutron spectroscopy studies using induced-proton tracks in PADC track detectors

    NASA Astrophysics Data System (ADS)

    El-Sersy, A. R.; Eman, S. A.

    2010-06-01

    In this work, a simple and adequate method for fast-neutron spectroscopy is proposed. This method was performed by free-in-air fast-neutron irradiation of CR-39 Nuclear Track Detectors (NTD) using an Am-Be source. Detectors were then chemically etched to remove few layers up to a thickness of 6.25 μm. By using an automatic image analyzer system for studying the registration of the induced-proton tracks in the NTD, the obtained data were analyzed via two tracks shapes. In the first one, the elliptical tracks were eliminated from the calculation and only the circular ones were considered in developing the response function. In the second method all registered tracks were considered and the corresponding response function was obtained. The rate of energy loss of the protons as a function of V[(d E/d X) - V] was calculated using the Monte Carlo simulation. The induced-proton energy was extracted from the corresponding d E/d X in NTD using a computer program based on the Bethe-Bloch function. The energy of the incident particles was up to few hundred MeV/nucleon. The energy of the interacting neutrons was then estimated by means of the extracted induced-proton energies and the scattering angle. It was found that the present resulting energy distribution of the fast-neutron spectrum from the Am-Be source was similar to that given in the literature where an average neutron energy of 4.6MeV was obtained.

  19. Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

    PubMed

    Afach, S; Ayres, N J; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Daum, M; Fertl, M; Franke, B; Griffith, W C; Grujić, Z D; Harris, P G; Heil, W; Hélaine, V; Kasprzak, M; Kermaidic, Y; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Musgrave, M; Naviliat-Cuncic, O; Pendlebury, J M; Piegsa, F M; Pignol, G; Plonka-Spehr, C; Prashanth, P N; Quéméner, G; Rawlik, M; Rebreyend, D; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severijns, N; Thorne, J A; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zenner, J; Zsigmond, G

    2015-10-16

    We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1  μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1  pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime. PMID:26550870

  20. Neutron-induced nucleation inside bubble chambers using Freon 115 as the active medium

    NASA Astrophysics Data System (ADS)

    Ghilea, M. C.; Meyerhofer, D. D.; Sangster, T. C.

    2011-08-01

    Neutron imaging is used in inertial confinement fusion (ICF) experiments to measure the core symmetry of imploded targets. Liquid bubble chambers have the potential to obtain higher resolution images of the targets for a shorter source-target distance than typical scintillator arrays. Due to the fact that nucleation models used in gel detectors research cannot always give correct estimates for the neutron-induced bubble density inside a liquid bubble chamber, an improved theoretical model to describe the mechanism of bubble formation for Freon 115 as the active medium has been developed. It shows that the size of the critical radius for the nucleation process determines the mechanism of bubble formation and the sensitivity of the active medium to the 14.1-MeV incident neutrons resulting from ICF implosions. The bubble-growth mechanism is driven by the excitation of the medium electronic levels and not by electrons ejected from the medium's atoms as happens for the bubble chambers used to detect charged particles. The model accurately predicts the neutron-induced bubble density measured on OMEGA with both liquid bubble chambers and gel detectors.

  1. Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

    PubMed

    Afach, S; Ayres, N J; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Daum, M; Fertl, M; Franke, B; Griffith, W C; Grujić, Z D; Harris, P G; Heil, W; Hélaine, V; Kasprzak, M; Kermaidic, Y; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Musgrave, M; Naviliat-Cuncic, O; Pendlebury, J M; Piegsa, F M; Pignol, G; Plonka-Spehr, C; Prashanth, P N; Quéméner, G; Rawlik, M; Rebreyend, D; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severijns, N; Thorne, J A; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zenner, J; Zsigmond, G

    2015-10-16

    We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1  μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1  pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

  2. Reducing Uncertainties in Neutron-Induced Fission Cross Sections Using a Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Manning, Brett; Niffte Collaboration

    2015-10-01

    Neutron-induced fission cross sections for actinides have long been of great interest for nuclear energy and stockpile stewardship. Traditionally, measurements were performed using fission chambers which provided limited information about the detected fission events. For the case of 239Pu(n,f), sensitivity studies have shown a need for more precise measurements. Recently the Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) has developed the fission Time Projection Chamber (fissionTPC) to measure fission cross sections to better than 1% uncertainty by providing 3D tracking of fission fragments. The fissionTPC collected data to calculate the 239Pu(n,f) cross section at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center during the 2014 run cycle. Preliminary analysis has been focused on studying particle identification and target and beam non-uniformities to reduce the uncertainty on the cross section. Additionally, the collaboration is investigating other systematic errors that could not be well studied with a traditional fission chamber. LA-UR-15-24906.

  3. Proton Radiography: Cross Section Measurements and Detector Development

    SciTech Connect

    Michael J. Longo; H. R. Gustafson: Durga Rajaram; Turgun Nigmanov

    2010-04-16

    Proton radiography has become an important tool for predicting the performance of stockpiled nuclear weapons. Current proton radiography experiments at LANSCE are confined to relatively small targets on the order of centimeters in size because of the low beam energy. LANL scientists have made radiographs with 12 and 24 GeV protons produced by the accelerator at Brookhaven National Laboratory. These energies are in the range required for hydrotest radiography. The design of a facility for hydrotest radiography requires knowledge of the cross sections for producing high-energy particles in the forward direction, which are incorporated into the Monte Carlo simulation used in designing the beam and detectors. There are few existing measurements of neutron production cross sections for proton-nuclei interactions in the 50 GeV range, and almost no data exist for forward neutron production, especially for heavy target nuclei. Thus the data from the MIPP EMCAL and HCAL, for which our group was responsible, are critical to proton radiography. Since neutrons and photons cannot be focused by magnets, they cause a background “fog” on the images. This problem can be minimized by careful design of the focusing system and detectors. The purpose of our research was to measure forward production of neutrons produced by high-energy proton beams striking a variety of targets. The forward-going particles carry most of the energy from a high-energy proton interaction, so these are the most important to proton radiography. This work was carried out in conjunction with the Fermilab E-907 (MIPP) collaboration. Our group was responsible for designing and building the E907 forward neutron and photon calorimeters. With the support of our Stewardship Science Academic Alliances grants, we were able to design, build, and commission the calorimeters on budget and ahead of schedule. The MIPP experiment accumulated a large amount of data in the first run that ended in early 2006. Our group has

  4. Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced fission reactions on {sup 239}Pu

    SciTech Connect

    Talou, P.; Kawano, T.; Becker, B.; Danon, Y.; Chadwick, M. B.

    2011-06-15

    Prompt fission neutrons following the thermal and 0.5 MeV neutron-induced fission reaction of {sup 239}Pu are calculated using a Monte Carlo approach to the evaporation of the excited fission fragments. Exclusive data such as the multiplicity distribution P({nu}), the average multiplicity as a function of fragment mass {nu}-bar(A), and many others are inferred in addition to the most used average prompt fission neutron spectrum {chi}(E{sub in},E{sub out}), as well as average neutron multiplicity {nu}-bar. Experimental information on these more exclusive data help constrain the Monte Carlo model parameters. The calculated average total neutron multiplicity is {nu}-bar{sub c}=2.871 in very close agreement with the evaluated value {nu}-bar{sub e}=2.8725 present in the ENDF/B-VII.0 library. The neutron multiplicity distribution P({nu}) is in very good agreement with the evaluation by Holden and Zucker. The calculated average spectrum differs in shape from the ENDF/B-VII.0 spectrum, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail of the spectrum (below about 300 keV) than the Madland-Nix calculations, casting some doubts on how much scission neutrons contribute to the shape of the low-energy tail of the spectrum. The spectrum high-energy tail is very sensitive to the total kinetic energy distribution of the fragments as well as to the total excitation energy sharing at scission. Present experimental uncertainties on measured spectra above 6 MeV are too large to distinguish between various theoretical hypotheses. Finally, comparisons of the Monte Carlo results with experimental data on {nu}-bar(A) indicate that more neutrons are emitted from the light fragments than the heavy ones, in agreement with previous works.

  5. 231Pa and 233Pa Neutron-Induced Fission Data Analysis

    SciTech Connect

    Maslov, V.M.; Tetereva, N.A.; Baba, M.; Hasegawa, A.; Kornilov, N.V.; Kagalenko, A.B.

    2005-05-24

    The 231Pa and 233Pa neutron-induced fission cross-section database is analyzed within the Hauser-Feshbach approach. The consistency of neutron-induced fission cross-section data and data extracted from transfer reactions is investigated. The fission probabilities of Pa, fissioning in 231,233Pa(n,nf) reactions, are defined by fitting (3He,d) or (3He,t) transfer-reaction data. The present estimate of the 233Pa(n,f) fission cross section above the emissive fission threshold is supported by smooth level-density parameter systematics, validated in the case of the 231Pa(n,f) data description up to En =20 MeV.

  6. Neutron dosimetry

    DOEpatents

    Quinby, Thomas C.

    1976-07-27

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

  7. Modeled Neutron Induced Nuclear Reaction Cross Sections for Radiochemistry in the region of Iriduim and Gold

    SciTech Connect

    Hoffman, R D; Dietrich, F S; Kelley, K; Escher, J; Bauer, R; Mustafa, M

    2008-02-26

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for targets ranging from osmium (Z = 76) to gold (Z = 79). Of particular interest are the cross sections on Ir and Au including reactions on isomeric targets.

  8. Cosmic Ray Scattering Radiography

    NASA Astrophysics Data System (ADS)

    Morris, C. L.

    2015-12-01

    Cosmic ray muons are ubiquitous, are highly penetrating, and can be used to measure material densities by either measuring the stopping rate or by measuring the scattering of transmitted muons. The Los Alamos team has studied scattering radiography for a number of applications. Some results will be shown of scattering imaging for a range of practical applications, and estimates will be made of the utility of scattering radiography for nondestructive assessments of large structures and for geological surveying. Results of imaging the core of the Toshiba Nuclear Critical Assembly (NCA) Reactor in Kawasaki, Japan and simulations of imaging the damaged cores of the Fukushima nuclear reactors will be presented. Below is an image made using muons of a core configuration for the NCA reactor.

  9. Apparatus for proton radiography

    DOEpatents

    Martin, Ronald L.

    1976-01-01

    An apparatus for effecting diagnostic proton radiography of patients in hospitals comprises a source of negative hydrogen ions, a synchrotron for accelerating the negative hydrogen ions to a predetermined energy, a plurality of stations for stripping extraction of a radiography beam of protons, means for sweeping the extracted beam to cover a target, and means for measuring the residual range, residual energy, or percentage transmission of protons that pass through the target. The combination of information identifying the position of the beam with information about particles traversing the subject and the back absorber is performed with the aid of a computer to provide a proton radiograph of the subject. In an alternate embodiment of the invention, a back absorber comprises a plurality of scintillators which are coupled to detectors.

  10. Patient care in radiography

    SciTech Connect

    Ehrlich, R.A.; McCloskey, E.D.

    1989-01-01

    This book focuses on patient care procedures for radiographers. The authors focus on the role of the radiographer as a member of the health care team. The authors report on such topics as communication in patient care: safety, medico-legal considerations, transfer and positioning; physical needs; infection control; medication; CPR standards, acute situations; examination of the GI tract; contrast media; special imaging techniques and bedside radiography.

  11. Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory

    NASA Astrophysics Data System (ADS)

    Blyth, S. C.; Chan, Y. L.; Chen, X. C.; Chu, M. C.; Cui, K. X.; Hahn, R. L.; Ho, T. H.; Hsiung, Y. B.; Hu, B. Z.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Lau, Y. P.; Leung, J. K. C.; Leung, K. Y.; Lin, G. L.; Lin, Y. C.; Luk, K. B.; Luk, W. H.; Ngai, H. Y.; Ngan, S. Y.; Pun, C. S. J.; Shih, K.; Tam, Y. H.; Tsang, R. H. M.; Wang, C. H.; Wong, C. M.; Wong, H. L. H.; Wong, K. K.; Yeh, M.; Zhang, B. J.; Aberdeen Tunnel Experiment Collaboration

    2016-04-01

    We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of a gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be Iμ=(5.7 ±0.6 )×10-6 cm-2 s-1 sr-1 . The yield of muon-induced neutrons in the liquid scintillator was determined to be Yn=(1.19 ±0.08 (stat)±0.21 (syst))×10-4 neutrons /(μ .g .cm-2 ) . A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of ⟨Eμ⟩ 0.76 ±0.03 for liquid-scintillator targets.

  12. Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory

    DOE PAGESBeta

    Yeh, M.; Chan, Y. L.; Chen, X. C.; Chu, M. C.; Cui, K. X.; Hahn, R. L.; Ho, T. H.; Hsiung, Y. B.; Hu, B. Z.; Kwan, K. K.; et al

    2016-04-07

    In this study, we have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of a gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be Iμ = (5.7±0.6)×10–6 cm–2 s–1 sr–1. The yield of muon-induced neutrons in the liquid scintillator was determined to be Yn = (1.19 ± 0.08(stat) ± 0.21(syst)) × 10–4 neutrons/(μ•g•cm–2). A fit to the recently measured neutron yields at different depthsmore » gave a mean muon energy dependence of < Eμ >0.76±0.03 for liquid-scintillator targets.« less

  13. Welding-induced microstructure in austenitic stainless steels before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stoenescu, R.; Schäublin, R.; Gavillet, D.; Baluc, N.

    2007-02-01

    The effects of neutron irradiation on the microstructure of welded joints made of austenitic stainless steels have been investigated. The materials were welded AISI 304 and AISI 347, so-called test weld materials, and irradiated with neutrons at 300 °C to 0.3 and 1.0 dpa. In addition, an AISI 304 type from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 300 °C, was investigated. The microstructure of heat-affected zones and base materials was analysed before and after irradiation, using transmission electron microscopy. Neutron diffraction was performed for internal stress measurements. It was found that the heat-affected zone contains, relative to the base material, a higher dislocation density, which relates well to a higher residual stress level and, after irradiation, a higher irradiation-induced defect density. In both materials, the irradiation-induced defects are of the same type, consisting in black dots and Frank dislocation loops. Careful analysis of the irradiation-induced defect contrast was performed and it is explained why no stacking fault tetrahedra could be identified.

  14. Study of neutron irradiation-induced colors in Brazilian topaz

    NASA Astrophysics Data System (ADS)

    Leal, A. S.; Krambrock, K.; Ribeiro, L. G. M.; Menezes, M. Â. B. C.; Vermaercke, P.; Sneyers, L.

    2007-09-01

    In this work, preliminary results of the investigation of the coloring mechanisms in topaz from different regions of Brazil, irradiated by the TRIGA MARK I IPR-R1 and BR1 nuclear reactors of the CDTN/CNEN (Brazil) and SCK.CEN(Belgium), respectively, are presented . The samples were analyzed by the k0-NAA method for impurities and total activity. The color and color centers were investigated by optical absorption and electron paramagnetic resonance (EPR) spectroscopy. The total integrated flux dependence of the induced blue colors and color centers is discussed.

  15. Measurement and modeling of muon-induced neutrons in LSM in application for direct dark matter searches

    SciTech Connect

    Kozlov, Valentin; Collaboration: EDELWEISS Collaboration

    2013-08-08

    Due to a very low event rate expected in direct dark matter search experiments, a good understanding of every background component is crucial. Muon-induced neutrons constitute a prominent background, since neutrons lead to nuclear recoils and thus can mimic a potential dark matter signal. EDELWEISS is a Ge-bolometer experiment searching for WIMP dark matter. It is located in the Laboratoire Souterrain de Modane (LSM, France). We have measured muon-induced neutrons by means of a neutron counter based on Gd-loaded liquid scintillator. Studies of muon-induced neutrons are presented and include development of the appropriate MC model based on Geant4 and analysis of a 1000-days measurement campaign in LSM. We find a good agreement between measured rates of muon-induced neutrons and those predicted by the developed model with full event topology. The impact of the neutron background on current EDELWEISS data-taking as well as for next generation experiments such as EURECA is briefly discussed.

  16. Energy dependence of nuclear charge distribution in neutron induced fission of Z-even nuclei

    NASA Astrophysics Data System (ADS)

    Roshchenko, V. A.; Piksaikin, V. M.; Isaev, S. G.; Goverdovski, A. A.

    2006-07-01

    For the first time the distribution of nuclear charge of fission products with mass numbers 87, 88, 89, 91, 93, 94, 95, 137, 138, 139, and 140 and their complementary products have been studied for neutron induced fission of U235 and Pu239 in the energy range from thermal up to 1.2 MeV. The energy dependences of the cumulative yields of Br87, Br88, Br89, Br91, Kr93, Rb94, Rb95, I137, I138, I139, and I140 have been obtained by delayed neutron measurements. The most probable charge ZP(A)in the appropriate isobaric β-decay chains was estimated. The results were analyzed in terms of the deviation ΔZP(A') of the most probable charge of isobaric β-decay chains from the unchanged charge distribution before prompt neutron emission (nuclear charge polarization) and they are compared with experimental data of other authors and with predictions from Nethaway's ZP-formula and Wahl's ZP-model. We show that the nuclear charge polarization of primary fission fragments <ΔZP(A')> before prompt neutron evaporation decreases as the excitation energy of the compound nucleus increases. This decrease is more pronounced for fission of U235. The energy dependencies of ΔZP(A') and ΔZP(ZP) obtained in the present work show an attenuation of the odd-even effects in the charge distribution as the excitation energy of the compound nucleus increases.

  17. Neutron induced light-ion production from Iron and Bismuth at 175 MeV

    NASA Astrophysics Data System (ADS)

    Bevilacqua, R.; Pomp, S.; Simutkin, V.; Tippawan, U.; Andersson, P.; Blomgren, J.; Österlund, M.; Hayashi, M.; Hirayama, S.; Naito, Y.; Watanabe, Y.; Tesinsky, M.; Lecolley, F.-R.; Marie, N.; Hjalmarsson, A.; Prokofiev, A.; Kolozhvari, A.

    2010-03-01

    We have measured light-ion (p, d, t, 3He and α) production in the interaction of 175 MeV neutrons with iron and bismuth, using the MEDLEY setup. A large set of measurements at 96 MeV has been recently completed and published, and now higher energy region is under investigation. MEDLEY is a conventional spectrometer system that allows low-energy thresholds and offers measurements over a wide angular range. The system consists of eight telescopes, each of them composed of two silicon surface barrier detectors, to perform particle identification, and a CsI(Tl) scintillator to fully measure the kinetic energy of the produced light-ions. The telescopes are placed at angles from 20° to 160°, in steps of 20°. Measurements have been performed at The Svedberg Laboratory, Uppsala (Sweden), where a quasi mono-energetic neutron beam is available and well characterized. Time of flight techniques are used to select light-ion events induced by neutrons in the main peak of the source neutron spectrum. We report preliminary double differential cross sections for production of protons, deuterons and tritons in comparison with model calculations using TALYS-1.0 code.

  18. Defect-induced magnetism in neutron irradiated 6H-SiC single crystals.

    PubMed

    Liu, Yu; Wang, Gang; Wang, Shunchong; Yang, Jianhui; Chen, Liang; Qin, Xiubo; Song, Bo; Wang, Baoyi; Chen, Xiaolong

    2011-02-25

    Defect-induced magnetism is firstly observed in neutron irradiated SiC single crystals. We demonstrated that the intentionally created defects dominated by divacancies (V(Si)V(C)) are responsible for the observed magnetism. First-principles calculations revealed that defect states favor the formation of local moments and the extended tails of defect wave functions make long-range spin couplings possible. Our results confirm the existence of defect-induced magnetism, implying the possibility of tuning the magnetism of wide band-gap semiconductors by defect engineering.

  19. Neutron Radiographic Inspection of Industrial Components using Kamini Neutron Source Facility

    NASA Astrophysics Data System (ADS)

    Raghu, N.; Anandaraj, V.; Kasiviswanathan, K. V.; Kalyanasundaram, P.

    2008-03-01

    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.

  20. Irradiation Induced Defect Characterization in Reactor Pressure Vessel Steel by Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Han, Yougn-Soo; Shin, Eun-Joo; Lee, Chang-Hee; Park, Duck-Gun

    The degradation of the mechanical properties of the RPV (Reactor Pressure Vessel) steel during an irradiation in a nuclear power plant is closely related to the irradiation induced defects. The size of these defects is known to be a few nanometer, and the small angle neutron scattering technique is regarded as the best non destructive technique to characterize the nano sized inhomogeneities in bulk samples. The investigated the RPV steel has been used in YeongKwang nuclear power plant at Korea and the Cu content of the RPV steel is 0.06 wt%. The RPV steel was irradiated in the HANARO reactor at KAERI. The small angle neutron scattering experiments were performed by the SANS instrument in the HANARO reactor. The nano sized irradiation induced defects were quantitatively analyzed by SANS and the type of the irradiation induced defects was discussed in detail. The relation between irradiation induced defects and the yield strength was investigated. The characteristics of irradiation induced defects in low Cu containing RPV steel were discussed.

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

    PubMed

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

    2000-01-01

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

  2. Lower Gastrointestinal (GI) Tract X-Ray (Radiography)

    MedlinePlus

    ... Resources Professions Site Index A-Z X-ray (Radiography) - Lower GI Tract Lower gastrointestinal tract radiography or ... Radiography? What is Lower GI Tract X-ray Radiography (Barium Enema)? Lower gastrointestinal (GI) tract radiography, also ...

  3. Neutron interferometric measurement and calculations of a phase shift induced by Laue transmission.

    PubMed

    Potocar, T; Zawisky, M; Lemmel, H; Springer, J; Suda, M

    2015-09-01

    This study investigates the phase shift induced by Laue transmission in a perfect Si crystal blade in unprecedented detail. This `Laue phase' was measured at two wavelengths in the vicinity of the Bragg condition within a neutron interferometer. In particular, the sensitivity of the Laue phase to the alignment of the monochromator and interferometer (rocking angle) and beam divergence has been verified. However, the influence of fundamental quantities, such as the neutron-electron scattering length, on the Laue phase is rather small. The fascinating steep phase slope of 5.5° [(220) Bragg peak] and 11.5° [(440) Bragg peak] per 0.001 arcsec deviation from the Bragg angle has been achieved. The results are analysed using an upgraded simulation tool. PMID:26317196

  4. Angular distribution of products of ternary nuclear fission induced by cold polarized neutrons

    SciTech Connect

    Bunakov, V. E. Kadmensky, S. G. Kadmensky, S. S.

    2008-11-15

    Within quantum fission theory, angular distributions of products originating from the ternary fission of nuclei that is induced by polarized cold and thermal neutrons are investigated on the basis of a non-evaporative mechanism of third-particle emission and a consistent description of fission-channel coupling. It is shown that the inclusion of Coriolis interaction both in the region of the discrete and in the region of the continuous spectrum of states of the system undergoing fission leads to T-odd correlations in the aforementioned angular distributions. The properties of the TRI and ROT effects discovered recently, which are due to the interference between the fission amplitudes of neutron resonances, are explored. The results obtained here are compared with their counterparts from classic calculations based on the trajectory method.

  5. Semiclassical description of TRI asymmetry in ternary fission induced by cold polarized neutrons

    SciTech Connect

    Bunakov, V. E.; Kadmensky, S. G.

    2011-11-15

    The possibility of semiclassically describing T-even TRI-type asymmetry in ternary fission induced by polarized neutrons is considered on the basis of employing Coriolis interaction that takes into account the coupling of a light charged particle to the collective rotation of a polarized fissile nucleus. It is shown that allowance for this interaction makes it possible to explain qualitatively the magnitudes of two asymmetry effects observed in light-charge-particle emission both within the semiclassical and within the quantum-mechanical approach. The difference in the relative magnitudes and signs of the effects between different target nuclei is associated with the interference contributions to the cross section from neighboring neutron resonances and therefore cannot be explained within the semiclassical approach.

  6. Nuclear Reaction Models Responsible for Simulation of Neutron-induced Soft Errors in Microelectronics

    SciTech Connect

    Watanabe, Y. Abe, S.

    2014-06-15

    Terrestrial neutron-induced soft errors in MOSFETs from a 65 nm down to a 25 nm design rule are analyzed by means of multi-scale Monte Carlo simulation using the PHITS-HyENEXSS code system. Nuclear reaction models implemented in PHITS code are validated by comparisons with experimental data. From the analysis of calculated soft error rates, it is clarified that secondary He and H ions provide a major impact on soft errors with decreasing critical charge. It is also found that the high energy component from 10 MeV up to several hundreds of MeV in secondary cosmic-ray neutrons has the most significant source of soft errors regardless of design rule.

  7. Boron analysis for neutron capture therapy using particle-induced gamma-ray emission.

    PubMed

    Nakai, Kei; Yamamoto, Yohei; Okamoto, Emiko; Yamamoto, Tetsuya; Yoshida, Fumiyo; Matsumura, Akira; Yamada, Naoto; Kitamura, Akane; Koka, Masashi; Satoh, Takahiro

    2015-12-01

    The neutron source of BNCT is currently changing from reactor to accelerator, but peripheral facilities such as a dose-planning system and blood boron analysis have still not been established. To evaluate the potential application of particle-induced gamma-ray emission (PIGE) for boron measurement in clinical boron neutron capture therapy, boronophenylalanine dissolved within a cell culture medium was measured using PIGE. PIGE detected 18 μgB/mL f-BPA in the culture medium, and all measurements of any given sample were taken within 20 min. Two hours of f-BPA exposure was required to create a boron distribution image. However, even though boron remained in the cells, the boron on the cell membrane could not be distinguished from the boron in the cytoplasm.

  8. Chromosome aberrations induced in human lymphocytes by D-T neutrons

    SciTech Connect

    Lloyd, D.C.; Edwards, A.A.; Prosser, J.S.; Bolton, D.; Sherwin, A.G.

    1984-06-01

    Unstable chromosome aberrations induced by in vitro irradiation with D-T neutrons have been analyzed in human blood lymphocytes. With respect to 250 kVp X rays a maximum limiting RBE at low doses of 4.1 was obtained for dicentric aberrations. Using aberrations as markers in mixed cultures of irradiated and unirradiated cells permits an assessment of interphase death plus mitotic delay. The low-dose RBE for this effect is 2.5. Assuming all unstable aberrations observed at metaphase would lead to cell death by nondisjunction allows an assessment of mitotic death. The low-dose RBE for this effect is 4.5. The data are compared with similar work obtained earlier with /sup 242/Cm ..cap alpha.. particles. The application of the present work to cytogenetic assessment of dose after accidental exposure to D-T neutrons is discussed.

  9. Radioactive ion beams produced by neutron-induced fission at ISOLDE

    NASA Astrophysics Data System (ADS)

    Catherall, R.; Lettry, J.; Gilardoni, S.; Köster, U.; Isolde Collaboration

    2003-05-01

    The production rates of neutron-rich fission products for the next-generation radioactive beam facility EURISOL [EU-RTD Project EURISOL (HPRI-CT-1999-50001)] are mainly limited by the maximum amount of power deposited by protons in the target. An alternative approach is to use neutron beams to induce fission in actinide targets. This has the advantage of reducing: the energy deposited by the proton beam in the target; contamination from neutron-deficient isobars that would be produced by spallation; and mechanical stress on the target. At ISOLDE CERN [E. Kugler, Hyperfine Interact. 129 (2000) 23], tests have been made on standard ISOLDE actinide targets using fast-neutron bunches produced by bombarding thick, high- Z metal converters with 1 and 1.4 GeV proton pulses. This paper reviews the first applications of converters used at ISOLDE. It highlights the different geometries and the techniques used to compare fission yields produced by the proton beam directly on the target with neutron-induced fission. Results from the six targets already tested, namely UC 2/graphite and ThO 2 targets with tungsten and tantalum converters, are presented. To gain further knowledge for the design of a dedicated target as required by the TARGISOL project [EU-RTD Project TARGISOL (HPRI-CT-2001-50033)], the results are compared to simulations, using the MARS [N.V. Mokhov, S.I. Striganov, A. Van Ginneken, S.G. Mashnik, A.J. Sierk, J. Ranft, MARS code developments, in: 4th Workshop on Simulating Accelerator Radiation Environments, SARE-4, Knoxville, USA, 14-15.9.1998, FERMILAB-PUB-98-379, nucl-th/9812038; N.V. Mokhov, The Mars Code System User's Guide, Fermilab-FN-628, 1995; N.V. Mokhov, MARS Code Developments, Benchmarking and Applications, Fermilab-Conf-00-066, 2000; O.E. Krivosheev, N.V. Mokhov, A New MARS and its Applications, Fermilab-Conf-98/43, 1998] code interfaced with MCNP [J.S. Hendrics, MCNP4C LANL Memo X-5; JSH-2000-3; J.F. Briemesteir (Ed.), MCNP - A General Montecarlo N

  10. Radioactive ion beams produced by neutron-induced fission at ISOLDE

    NASA Astrophysics Data System (ADS)

    Isolde Collaboration; Catherall, R.; Lettry, J.; Gilardoni, S.; Köster, U.

    2003-05-01

    The production rates of neutron-rich fission products for the next-generation radioactive beam facility EURISOL [EU-RTD Project EURISOL (HPRI-CT-1999-50001)] are mainly limited by the maximum amount of power deposited by protons in the target. An alternative approach is to use neutron beams to induce fission in actinide targets. This has the advantage of reducing: the energy deposited by the proton beam in the target; contamination from neutron-deficient isobars that would be produced by spallation; and mechanical stress on the target. At ISOLDE CERN [E. Kugler, Hyperfine Interact. 129 (2000) 23], tests have been made on standard ISOLDE actinide targets using fast-neutron bunches produced by bombarding thick, high-/Z metal converters with 1 and 1.4 GeV proton pulses. This paper reviews the first applications of converters used at ISOLDE. It highlights the different geometries and the techniques used to compare fission yields produced by the proton beam directly on the target with neutron-induced fission. Results from the six targets already tested, namely UC2/graphite and ThO2 targets with tungsten and tantalum converters, are presented. To gain further knowledge for the design of a dedicated target as required by the TARGISOL project [EU-RTD Project TARGISOL (HPRI-CT-2001-50033)], the results are compared to simulations, using the MARS [N.V. Mokhov, S.I. Striganov, A. Van Ginneken, S.G. Mashnik, A.J. Sierk, J. Ranft, MARS code developments, in: 4th Workshop on Simulating Accelerator Radiation Environments, SARE-4, Knoxville, USA, 14-15.9.1998, FERMILAB-PUB-98-379, nucl-th/9812038; N.V. Mokhov, The Mars Code System User's Guide, Fermilab-FN-628, 1995; N.V. Mokhov, MARS Code Developments, Benchmarking and Applications, Fermilab-Conf-00-066, 2000; O.E. Krivosheev, N.V. Mokhov, A New MARS and its Applications, Fermilab-Conf-98/43, 1998] code interfaced with MCNP [J.S. Hendrics, MCNP4C LANL Memo X-5; JSH-2000-3; J.F. Briemesteir (Ed.), MCNP - A General Montecarlo N

  11. Neutron-induced fission: properties of prompt neutron and γ rays as a function of incident energy

    NASA Astrophysics Data System (ADS)

    Stetcu, I.; Talou, P.; Kawano, T.

    2016-06-01

    We have applied the Hauser-Feshbach statistical theory, in a Monte-Carlo implementation, to the de-excitation of fission fragments, obtaining a reasonable description of the characteristics of neutrons and gamma rays emitted before beta decays toward stability. Originally implemented for the spontaneous fission of 252Cf and the neutroninduced fission of 235U and 239Pu at thermal neutron energy, in this contribution we discuss the extension of the formalism to incident neutron energies up to 20 MeV. For the emission of pre-fission neutrons, at incident energies beyond second-chance fission, we take into account both the pre-equilibrium and statistical pre-fission components. Phenomenological parameterizations of mass, charge and TKE yields are used to obtain the initial conditions for the fission fragments that subsequently decay via neutron and emissions. We illustrate this approach for 239Pu(n,f).

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

    SciTech Connect

    Mitra,S.

    2008-11-17

    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.

  13. Measurement of residual 152Eu activity induced by atomic bomb neutrons in Nagasaki and the contribution of environmental neutrons to this activity.

    PubMed

    Shizuma, Kiyoshi; Endo, Satoru; Hoshi, Masaharu; Takada, Jun; Ishikawa, Masayori; Iwatani, Kazuo; Hasai, Hiromi; Oka, Takamitsu; Fujita, Shoichiro; Watanabe, Tadaaki; Yamashita, Tomoaki; Imanaka, Tetsuji

    2003-06-01

    Residual 152Eu activities induced by neutrons from the Nagasaki atomic bomb were measured for nine mineral samples located up to 1,061 m in the slant range and one control sample at 2,850 m from the hypocenter. A chemical separation to prepare europium-enriched samples was performed for all samples, and gamma ray measurements were carried out with a low background well-type germanium detector. In this paper, the measured specific activities of 152Eu are compared with activation calculations based on the DS86 neutron fluence and the 93Rev one. The calculated-to-measured ratios are also compared with those of 60Co and 36Cl. The present results indicate that the measurements agree to the calculation within a factor of three as observed in the nuclear tests at Nevada. The activation level of environmental neutrons and the detection limit for 152Eu are also discussed. PMID:13678342

  14. Effects of Neutron Emission on Fragment Mass and Kinetic Energy Distribution from Thermal Neutron-Induced Fission of {sup 235}U

    SciTech Connect

    Montoya, M.; Rojas, J.; Saetone, E.

    2007-10-26

    The mass and kinetic energy distribution of nuclear fragments from thermal neutron-induced fission of {sup 235}U(n{sub th},f) have been studied using a Monte-Carlo simulation. Besides reproducing the pronounced broadening in the standard deviation of the kinetic energy at the final fragment mass number around m = 109, our simulation also produces a second broadening around m = 125. These results are in good agreement with the experimental data obtained by Belhafaf et al. and other results on yield of mass. We conclude that the obtained results are a consequence of the characteristics of the neutron emission, the sharp variation in the primary fragment kinetic energy and mass yield curves. We show that because neutron emission is hazardous to make any conclusion on primary quantities distribution of fragments from experimental results on final quantities distributions.

  15. RECENT APPLICATIONS OF THE GREENSPAN AND TSCHIEGG DATA ON NEUTRON INDUCED CAVITATION THRESHOLDS

    SciTech Connect

    West, Colin D

    2007-03-01

    In 1967 Greenspan and Tschiegg published a paper on radiation induced acoustic cavitation. They researched the thresholds for cavitation induced in various liquids by fast neutrons, {alpha}-decay recoils and fission fragments. It turns out that these data can be used to verify predictions of a more recent theory of radiation induced cavitation nucleation. In 1979, in a report to their sponsor (The Office of Naval Research) they published new details of their results on neutron induced cavitation thresholds, including tables of the thresholds at different temperatures for various liquids. They were also some fission fragment results, but none of the {alpha}-decay recoil data. By that time Greenspan had evidently retired while I had left the field of cavitation research and did not know of the existence of their report [which also contains the only published record of some cavitation threshold measurements made by West and Howlett at Harwell, England]. Later still, in 1982, Greenspan and Tschiegg published the graphical data--but not the tables--in a more easily accessible form. In the late 1990s I revisited the problem of calculating radiation induced cavitation thresholds. There was interest in this because the Spallation Neutron Source (SNS) project, then just beginning, planned to use a liquid mercury target to produce intense bursts of neutrons when irradiated by a pulsed, high energy proton beam. It was known that the pressure waves produced by local heating when the proton pulse struck the target could, upon reflection at the walls of the mercury container, give rise to very high, although brief, negative pressure waves in the mercury. There was concern that cavitation might result and, if it did, might lead to undesirable effects. With the encouragement of the SNS target team this author managed further to develop an earlier method of calculating the threshold for such cavitation, and the SNS project kindly provided funding to publish the work in two ORNL

  16. Optimisation in general radiography

    PubMed Central

    Martin, CJ

    2007-01-01

    Radiography using film has been an established method for imaging the internal organs of the body for over 100 years. Surveys carried out during the 1980s identified a wide range in patient doses showing that there was scope for dosage reduction in many hospitals. This paper discusses factors that need to be considered in optimising the performance of radiographic equipment. The most important factor is choice of the screen/film combination, and the preparation of automatic exposure control devices to suit its characteristics. Tube potential determines the photon energies in the X-ray beam, with the selection involving a compromise between image contrast and the dose to the patient. Allied to this is the choice of anti-scatter grid, as a high grid ratio effectively removes the larger component of scatter when using higher tube potentials. However, a high grid ratio attenuates the X-ray beam more heavily. Decisions about grids and use of low attenuation components are particularly important for paediatric radiography, which uses lower energy X-ray beams. Another factor which can reduce patient dose is the use of copper filtration to remove more low-energy X-rays. Regular surveys of patient dose and comparisons with diagnostic reference levels that provide a guide representing good practice enable units for which doses are higher to be identified. Causes can then be investigated and changes implemented to address any shortfalls. Application of these methods has led to a gradual reduction in doses in many countries. PMID:21614270

  17. Study of Neutron-Induced Fission Cross Sections of U, Am, and Cm at n{sub T}OF

    SciTech Connect

    Milazzo, P. M.; Abbondanno, U.; Belloni, F.; Fujii, K.; Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.; Ferrant, L.; Gunsing, F.; Pancin, J.; Perrot, L.; Plukis, A.; Stephan, C.; Tassan-Got, L.; Alvarez-Velarde, F.; Cano-Ott, D.

    2010-08-04

    Neutron induced fission cross sections of several isotopes have been measured at the CERN n{sub T}OF spallation neutron facility. Between them some measurements involve isotopes ({sup 233}U, {sup 241}Am, {sup 243}Am, {sup 245}Cm) relevant for applications to nuclear technologies. The n{sub T}OF facility delivers neutrons with high instantaneous flux and in a wide energy range, from thermal up to 250 MeV. The experimental apparatus consists of an ionization chamber that discriminates fission fragments and {alpha} particles coming from natural radioactivity of the samples. All the measurements were performed referring to the standard cross section of {sup 235}U.

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

    SciTech Connect

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

    1999-10-03

    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

  19. Residual Stress Analysis in Deep Drawn Twinning Induced Plasticity (TWIP) Steels Using Neutron Diffraction Method

    NASA Astrophysics Data System (ADS)

    Hong, Seokmin; Lee, Junghoon; Lee, Sunghak; Woo, Wanchuck; Kim, Sung-Kyu; Kim, Hyoung Seop

    2014-04-01

    In Twinning Induced Plasticity (TWIP) steels, delayed fracture occurs due to residual stresses induced during deep drawing. In order to investigate the relation between residual stresses and delayed fracture, in the present study, residual stresses of deep drawn TWIP steels (22Mn-0.6C and 18Mn-2Al-0.6C steels) were investigated using the finite element method (FEM) and neutron diffraction measurements. In addition, the delayed fracture properties were examined by dipping tests of cup specimens in the boiled water. In the FEM analysis, the hoop direction residual stress was highly tensile at cup edge, and the delayed fracture was initiated by the separation of hoop direction and propagated in an axial direction. According to the neutron diffraction analysis, residual stresses in 18Mn-2Al-0.6C steel were about half the residual stresses in 22Mn-0.6C steel. From the residual strain measurement using electron back-scatter diffraction, formation of deformation twins caused a lot of grain rotation and local strain at the grain boundaries and twin boundaries. These local residual strains induce residual stress at boundaries. Al addition in TWIP steels restrained the formation of deformation twins and dynamic strain aging, resulting in more homogeneous stress and strain distributions in cup specimens. Thus, in Al-added TWIP steels, residual stress of cup specimen considerably decreased, and delayed fracture resistance was remarkably improved by the addition of Al in TWIP steels.

  20. Charge distribution in the reactor-neutron-induced fission of 232Th

    NASA Astrophysics Data System (ADS)

    Erten, H. N.; Grütter, A.; Rössler, E.; von Gunten, H. R.

    1982-05-01

    The independent yields of 82Br, 86Rb, 96Nb, 98Nbm, 128Sbg, and 136Cs were determined in the reactor-neutron-induced fission of 232Th using radiochemical techniques. Results: (2.3+/-2.3)×10-4% for 82Br, <3.8×10-4% for 86Rb, <4.2×10-5% for 96Nb, (2.48+/-0.53)×10-3% for 98Nbm, (2.34+/-0.37)×10-3% for 128Sbg, and (1.70+/-0.13) ×10-4% for 136Cs. Using the extended Zp model of Wahl with the yield data from this work and the literature the following parameters were obtained for the charge distribution in 232Th fission: width of Gaussian dispersion σ¯Z=0.52+/-0.01, ΔZP (=ZP-ZUCD)=0.45+/-0.02. The even-odd proton and neutron enhancement factors were found to be small. These parameters and systematics of even-odd proton and neutron effects in low energy fission are discussed. NUCLEAR REACTIONS, FISSION Radiochemical fission yields 232Th(n,f), calculated charge dispersion parameters, and odd-even effects.

  1. Reliability Design for Neutron Induced Single-Event Burnout of IGBT

    NASA Astrophysics Data System (ADS)

    Shoji, Tomoyuki; Nishida, Shuichi; Ohnishi, Toyokazu; Fujikawa, Touma; Nose, Noboru; Hamada, Kimimori; Ishiko, Masayasu

    Single-event burnout (SEB) caused by cosmic ray neutrons leads to catastrophic failures in insulated gate bipolar transistors (IGBTs). It was found experimentally that the incident neutron induced SEB failure rate increases as a function of the applied collector voltage. Moreover, the failure rate increased sharply with an increase in the applied collector voltage when the voltage exceeded a certain threshold value (SEB cutoff voltage). In this paper, transient device simulation results indicate that impact ionization at the n-drift/n+ buffer boundary is a crucially important factor in the turning-on of the parasitic pnp transistor, and eventually latch-up of the parasitic thyristor causes SEB. In addition, the device parameter dependency of the SEB cutoff voltage was analytically derived from the latch-up condition of the parasitic thyristor. As a result, it was confirmed that reducing the current gain of the parasitic transistor, such as by increasing the n-drift region thickness d was effective in increasing the SEB cutoff voltage. Furthermore, `white' neutron-irradiation experiments demonstrated that suppressing the inherent parasitic thyristor action leads to an improvement of the SEB cutoff voltage. It was confirmed that current gain optimization of the parasitic transistor is a crucial factor for establishing highly reliable design against chance failures.

  2. Analysis of prompt fission neutrons in 235U(nth,f) and fission fragment distributions for the thermal neutron induced fission of 234U

    NASA Astrophysics Data System (ADS)

    Al-Adili, A.; Tarrío, D.; Hambsch, F.-J.; Göök, A.; Jansson, K.; Solders, A.; Rakopoulos, V.; Gustafsson, C.; Lantz, M.; Mattera, A.; Oberstedt, S.; Prokofiev, A. V.; Vidali, M.; Österlund, M.; Pomp, S.

    2016-06-01

    This paper presents the ongoing analysis of two fission experiments. Both projects are part of the collaboration between the nuclear reactions group at Uppsala and the JRC-IRMM. The first experiment deals with the prompt fission neutron multiplicity in the thermal neutron induced fission of 235U(n,f). The second, on the fission fragment properties in the thermal fission of 234U(n,f). The prompt fission neutron multiplicity has been measured at the JRC-IRMM using two liquid scintillators in coincidence with an ionization chamber. The first experimental campaign focused on 235U(nth,f) whereas a second experimental campaign is foreseen later for the same reaction at 5.5 MeV. The goal is to investigate how the so-called sawtooth shape changes as a function of fragment mass and excitation energy. Some harsh experimental conditions were experienced due to the large radiation background. The solution to this will be discussed along with preliminary results. In addition, the analysis of thermal neutron induced fission of 234U(n,f) will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of 235U(nth,f). Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.

  3. Image Acquisition and Quality in Digital Radiography.

    PubMed

    Alexander, Shannon

    2016-09-01

    Medical imaging has undergone dramatic changes and technological breakthroughs since the introduction of digital radiography. This article presents information on the development of digital radiography and types of digital radiography systems. Aspects of image quality and radiation exposure control are highlighted as well. In addition, the article includes related workplace changes and medicolegal considerations in the digital radiography environment. PMID:27601691

  4. Optimization of microwave-induced chemical etching for rapid development of neutron-induced recoil tracks in CR-39 detectors

    NASA Astrophysics Data System (ADS)

    Sahoo, G. S.; Tripathy, S. P.; Bandyopadhyay, T.

    2014-03-01

    A systematic investigation is carried out to optimize the recently established microwave-induced chemical etching (MICE) parameters for rapid development of neutron-induced recoil tracks in CR-39 detectors. Several combinations of all available microwave powers with different etching durations were analysed to determine the most suitable etching condition. The etching duration was found to reduce with increasing microwave power and the tracks were observed at about 18, 15, 12, and 6 min for 300, 450, 600 and 900 W of microwave powers respectively compared to a few hours in chemical etching (CE) method. However, for complete development of tracks the etching duration of 30, 40, 50 and 60 min were found to be suitable for the microwave powers of 900, 600, 450 and 300 W, respectively. Temperature profiles of the etchant for all the available microwave powers at different etching durations were generated to regulate the etching process in a controlled manner. The bulk etch rates at different microwave powers were determined by 2 methods, viz., gravimetric and removed thickness methods. A logarithmic expression was used to fit the variation of bulk etch rate with microwave power. Neutron detection efficiencies were obtained for all the cases and the results on track parameters obtained with MICE technique were compared with those obtained from another detector processed with chemical etching.

  5. The Neutron's Discovery - 80 Years on

    NASA Astrophysics Data System (ADS)

    Rogers, John D.

    A brief review is given of selected highlights in scientific developments from the birth of modern nuclear physics at the end of the 19th century to the discovery of the neutron in 1932. This is followed by some important milestones in neutron and reactor physics that have led to our current understanding and implementation of nuclear technologies. The beginnings can be traced back to the discovery of X-rays by Roentgen, the identification of natural radioactivity by Becquerel and the discovery of the electron by Thomson, towards the end of the 19th Century. Rutherford was a key figure in experimental physics who determined the structure of the atom and who inspired his students at McGill, Manchester and Cambridge Universities (many of whom would become Nobel laureates) in the pursuit of their physics research. One of Rutherford's students, James Chadwick, had studied the work carried out by Bothe and Becker on alpha particle-induced disintegration of light elements which had led to their observation of high energy penetrating radiation that neither they nor the Joliot-Curies could identify. Chadwick knew that the only possible explanation was the emission of a neutron in the nuclear reaction. He carried out tests in the Cavendish Laboratory and submitted his now classical paper identifying the neutron to the periodical Nature in 1932. The discovery of the neutron and of nuclear fission in 1939 opened up new areas for scientific investigation, in, for example, astrophysics, geology, neutron and nuclear physics. The prospects for nuclear power in particular appeared to be unlimited and both civil and military applications have been actively pursued. Many new experimental facilities have been designed and built to provide intense sources of neutrons for research purposes. Work carried out in such centres is included in the programme of the 7th International Topical Meeting on Neutron Radiography, an important forum for discussion of the latest research work of this

  6. Californium-252 Neutron Sources for Medical Applications

    SciTech Connect

    Boulogne, A.R.

    2001-08-29

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

  7. Radiometric Investigation of Water Vapour Movement in Wood-based Composites by Means of Cold and Thermal Neutrons

    NASA Astrophysics Data System (ADS)

    Solbrig, K.; Frühwald, K.; Ressel, J. B.; Mannes, D.; Schillinger, B.; Schulz, M.

    Wood-based composites are industrially produced panels made of resin-blended wood furnish material consolidated by hot pressing. Precise knowledge of the physical interrelations, such as heat and mass transfer induced densification and curing, are inevitable to control process performance and final product properties. Neutron radiography is able to distinguish between moisture and wood matter movement and thus to provide quantitative information considering the hot pressing process where only models exist. To this end, preliminary experiments were carried out utilising both cold and thermal neutrons to visualise and to quantify the water vapour movement within wood-based composites heated under sealing within a simplified mimicry of the hot pressing process conditions. Neutron radiography of this rather fast process was found to be feasible in general. The evaluation of the time-resolved image data maps the relative water content distribution within the sample during 9 min process time. A presumed wavefront-like vapour movement was confirmed. Hence, the results enhance the understanding of heat and mass transfer inside consolidated resin-blended wood furnish. These preliminary experiments prove neutron radiography as viable method for further comprehensive in-situ investigations of the hot pressing process of wood-based composites.

  8. Prompt γ-ray production in neutron-induced fission of 239Pu

    NASA Astrophysics Data System (ADS)

    Ullmann, J. L.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Kawano, T.; Lee, H. Y.; O'Donnell, J. M.; Hayes, A. C.; Stetcu, I.; Taddeucci, T. N.; Talou, P.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Chyzh, A.; Gostic, J.; Henderson, R.; Kwan, E.; Wu, C. Y.

    2013-04-01

    Background: The prompt gamma-ray spectrum from fission is important for understanding the physics of nuclear fission, and also in applications involving fission. Relatively few measurements of the prompt gamma spectrum from 239Pu(n,f) have been published.Purpose: This experiment measured the multiplicity, individual gamma energy spectrum, and total gamma energy spectrum of prompt fission gamma rays from 239Pu(n,f) in the neutron energy range from thermal to 30 keV, to test models of fission and to provide information for applications.Method: Gamma rays from neutron-induced fission of 239Pu were measured using the DANCE gamma-ray calorimeter. Fission events were tagged by detecting fission products in a parallel-plate avalanche counter in the center of DANCE. The measurements were corrected for detector response using a geant4 model of DANCE. A detailed analysis for the gamma rays from the 1+ resonance complex at 10.93 eV is presented.Results: A six-parameter analytical parametrization of the fission gamma-ray spectrum was obtained. A Monte Carlo Hauser-Feshbach calculation provided good general agreement with the data, but some differences remain to be resolved.Conclusions: An analytic parametrization can be made of the gamma-ray multiplicity, energy distribution, and total-energy distribution for the prompt gamma rays following neutron-induced fission of 239Pu. This parametrization may be useful for applications. Modern Monte Carlo Hauser-Feshbach calculations can do a good job of calculating the fission gamma-ray emission spectrum, although some details remain to be understood.

  9. Neutron irradiation induced microstructural changes in NBG-18 and IG-110 nuclear graphites

    SciTech Connect

    Karthik, Chinnathambi; Kane, Joshua; Butt, Darryl P.; Windes, William E.; Ubic, Rick

    2015-05-01

    This paper reports the neutron-irradiation-induced effects on the microstructure of NBG-18 and IG-110 nuclear graphites. The high-temperature neutron irradiation at two different irradiation conditions was carried out at the Advanced Test Reactor National User Facility at the Idaho National Laboratory. NBG-18 samples were irradiated to 1.54 dpa and 6.78 dpa at 430 °C and 678 °C respectively. IG-110 samples were irradiated to 1.91 dpa and 6.70 dpa at 451 °C and 674 °C respectively. Bright-field transmission electron microscopy imaging was used to study the changes in different microstructural components such as filler particles, microcracks, binder and quinoline-insoluble (QI) particles. Significant changes have been observed in samples irradiated to about 6.7 dpa. The closing of pre-existing microcracks was observed in both the filler and the binder phases. The binder phase exhibited substantial densification with near complete elimination of the microcracks. The QI particles embedded in the binder phase exhibited a complete microstructural transformation from rosettes to highly crystalline solid spheres. The lattice images indicate the formation of edge dislocations as well as extended line defects bridging the adjacent basal planes. The positive climb of these dislocations has been identified as the main contributor to the irradiation-induced swelling of the graphite lattice.

  10. Neutron-induced autoradiography used in the investigation of modern pigments in paintings of known composition

    SciTech Connect

    Aderhold, H.C.; Taft, W.S.

    1992-07-01

    Neutron-Induced Autoradiography is an effective analytical technique for mapping the location of a number of specified pigments in paintings. Most paintings which have been examined through neutron-induced autoradiography to date were painted prior to the introduction of the most common of modern pigments. By understanding die nuclear properties of these pigments, as revealed by this technique, a more informed analysis of modem paintings may result This investigation is part of an ongoing program to develop case studies for presentation to an undergraduate class at Cornell University, 'Art, Isotopes and Analysis'. We have found that this technique is a graphic and effective method of presenting nuclear reactions and radioactivity to non-specialists. Sample paintings are produced using pigments of known composition. A sequence of discreet layers, each a separate image, is documented in order to establish a reference for accurately interpreting the autoradiographs. The painting is then activated in the Cornell TRIGA reactor and a series of autoradiographs produced Gamma spectra taken before and after each film exposure gives us detailed information on which radioisotopes (and therefore, which pigments), are active. (author)

  11. Measurement of DT fusion and neutron-induced gamma-rays using gas Cherenkov Detector

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Herrmann, H. W.; Evans, S.; Sedillo, T.; Langenbrunner, J. R.; Young, C. S.; Mack, J. M.; McEvoy, A.; Horsfield, C. J.; Rubery, M.; Ali, Z.; Stoeffl, W.

    2010-08-01

    A secondary gamma experiment was carried out using a Gas Cherenkov Detector (GCD) at the OMEGA laser facility. The primary experimental objective was to simulate neutron-induced secondary gamma production (n-γ) from a NIF implosion capsule, hohlraum, and thermo-mechanical package. The high-band width of the GCD enabled us to detect time delayed and Doppler broadened n-γ signals from five different puck materials (Si, SiO2, Al, Al2O3, Cu) placed near target chamber center. These measurements were used for MCNP & ITS ACCEPT code validation purposes. By a simple change of the GCD CO2 gas pressure the system can effectively eliminate signals induced by n-γ reactions and thereby allow quality measurements of DT fusion γ-rays that are produced at NIF (National Ignition Facility).

  12. A multitask neutron beam line for spallation neutron sources

    NASA Astrophysics Data System (ADS)

    Pietropaolo, A.; Festa, G.; Grazzi, F.; Barzagli, E.; Scherillo, A.; Schooneveld, E. M.; Civita, F.

    2011-08-01

    Here we present a new concept for a time-of-flight neutron scattering instrument allowing for simultaneous application of three different techniques: time-of-flight neutron diffraction, neutron resonance capture analysis and Bragg edge transmission analysis. The instrument can provide average resolution neutron radiography too. The potential of the proposed concept was explored by implementing the necessary equipment on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (UK). The results obtained show the effectiveness of the proposed instrument to acquire relevant quantitative information in a non-invasive way on a historical metallurgical sample, namely a Japanese hand guard (tsuba). The aforementioned neutron techniques simultaneously exploited the extended neutron energy range available from 10 meV to 1 keV. This allowed a fully satisfactory characterization of the sample in terms of metal components and their combination in different phases, and forging and assembling methods.

  13. Initial observations of cavitation-induced erosion of liquid metal spallation target vessels at the Spallation Neutron Source

    SciTech Connect

    McClintock, David A; Riemer, Bernie; Ferguson, Phillip D; Carroll, Adam J; Dayton, Michael J

    2012-01-01

    During operation of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory the mechanical properties of the AISI 316L target module are altered by high-energy neutron and proton radiation. The interior surfaces of the target vessel are also damaged by cavitation-induced erosion, which results from repetitive rapid heating of the liquid mercury by high-energy proton beam pulses. Until recently no observations of cavitation-induced erosion were possible for conditions prototypical to the SNS. Post irradiation examination (PIE) of the first and second operational SNS targets was performed to gain insight into the radiation-induced changes in mechanical properties of the 316L target material and the extent of cavitation-induced erosion to the target vessel inner surfaces. Observations of cavitation-induced erosion of the first and second operational SNS target modules are presented here, including images of the target vessel interiors and specimens removed from the target beam-entrance regions.

  14. Neutron induced fission of U isotopes up to 100 MeV

    SciTech Connect

    Lestone, J.P.; Gavron, A.

    1993-10-01

    We have developed a statistical model description of the neutron induced fission of U isotopes using densities of intrinsic states and spin cut off parameters obtained directly from appropriate Nilsson model single particle levels. The first chance fission cross sections are well reproduced when the rotational contributions to the nuclear level densities are taken into account. In order to fit the U(n,f) cross sections above the threshold of second chance fission, we need to: (1) assume that the triaxial level density enhancement is washed out at an excitation energy of {approximately}7 MeV above the triaxial barriers with a width of {approximately}1 MeV, implying a {gamma} deformation for the first barriers of 10{degree} < {gamma} < 20{degree}; and (2) include pre-equilibrium particle emission in the calculations. Above an incoming neutron kinetic energy of {approximately}17 MeV our statistical model U(n,f) cross sections increasingly overestimate the experimental data when so called ``good`` optical model potentials are used to calculate the compound nucleus formation cross sections. This is not surprising since at these high energies little data exists on the scattering of neutrons to help guide the choice of optical model parameters. A satisfactory reproduction of all the available U(n,f) cross sections above 17 MeV is obtained by a simple scaling of our calculated compound nucleus formation cross sections. This scaling factor falls from 1.0 at 17 MeV to 0.82 at 100 MeV.

  15. Grazing-incidence neutron-induced fluorescence probes density profiles of labeled molecules at solid/liquid interfaces.

    PubMed

    Schneck, Emanuel; Jentschel, Michael; Gege, Christian; Tanaka, Motomu; Demé, Bruno

    2013-03-26

    We report on the use of characteristic prompt γ-fluorescence after neutron capture induced by an evanescent neutron wave to probe densities and depth profiles of labeled molecules at solid/liquid interfaces. In contrast to classical scattering techniques and X-ray fluorescence, this method of "grazing-incidence neutron-induced fluorescence" combines direct chemical specificity, provided by the label, with sensitivity to the interface, inherent to the evanescent wave. We demonstrate that the formation of a supported lipid membrane can be quantitatively monitored from the characteristic fluorescence of (157)Gd(3+) ions bound to the headgroup of chelator lipids. Moreover, we were able to localize the (157)Gd(3+) ions along the surface normal with nanometer precision. This first proof of principle with a well-defined model system suggests that the method has a great potential for biology and soft matter studies where spatial resolution and chemical sensitivity are required.

  16. Revised Production Rates for Na-22 and Mn-54 in Meteorites Using Cross Sections Measured for Neutron-induced Reactions

    NASA Technical Reports Server (NTRS)

    Sisterson, J. M.; Kim, K. J.; Reedy, R. C.

    2004-01-01

    The interactions of galactic cosmic rays (GCR) with extraterrestrial bodies produce small amounts of radionuclides and stable isotopes. The production rates of many relatively short-lived radionuclides, including 2.6-year Na-22 and 312-day Mn-54, have been measured in several meteorites collected very soon after they fell. Theoretical models used to calculate production rates for comparison with the measured values rely on input data containing good cross section measurements for all relevant reactions. Most GCR particles are protons, but secondary neutrons make most cosmogenic nuclides. Calculated production rates using only cross sections for proton-induced reactions do not agree well with measurements. One possible explanation is that the contribution to the production rate from reactions initiated by secondary neutrons produced in primary GCR interactions should be included explicitly. This, however, is difficult to do because so few of the relevant cross sections for neutron-induced reactions have been measured.

  17. Neutron stars and millisecond pulsars from accretion-induced collapse in globular clusters

    NASA Technical Reports Server (NTRS)

    Bailyn, Charles D.; Grindlay, Jonathan E.

    1990-01-01

    This paper examines the limits on the number of millisecond pulsars which could be formed in globular clusters by the generally accepted scenario (in which a neutron star is created by the supernova of an initially massive star and subsequently captures a companion to form a low-mass X-ray binary which eventually becomes a millisecond pulsar). It is found that, while the number of observed low-mass X-ray binaries can be adequately explained in this way, the reasonable assumption that the pulsar luminosity function in clusters extends below the current observational limits down to the luminosity of the faintest millisecond pulsars in the field suggests a cluster population of millisecond pulsars which is substantially larger than the standard model can produce. Alleviating this problem by postulating much shorter lifetimes for the X-ray binaries requires massive star populations sufficiently large that the mass loss resulting from their evolution would be likely to unbind the cluster. It is argued that neutron star formation in globular clusters by accretion-induced collapse of white dwarfs may resolve the discrepancy in birthrates.

  18. Neutron Induced Backgrounds In the MIXE X-Ray Detector at Balloon Altitudes

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.; Dietz, K. L.; Ramsey, B. D.

    1997-01-01

    The MIXE detector developed at NASA/MSFC is designed for x-ray astronomy and consists of a multiwire proportional counter sensitive to photons less than 150 keV. The detector has been flown on several balloon flights with higher than expected background levels observed. Previous predictions of the detector background due to atmospheric gamma-ray and cosmic diffuse sources were much less (factor of 3) than flight background measurements. The work reported here was undertaken to determine if the additional contribution from gamma-rays generated by albedo and cosmic-ray induced neutrons in the detector and payload assembly could account for the background levels observed. Monte Carlo nuclear interaction and radiation transport simulations were made for the ambient cosmic-ray environment corresponding to a previous MEE balloon flight at 3 g/cm(exp 2) residual atmosphere and 42 N geomagnetic latitude. The omnidirectional albedo neutron spectrum and the GCR proton spectrum which were used as input to the calculations are shown. For the albedo angular distribution, the predicted up/down flux ratio of 2.5 was used together with the angular dependence measured by Preszler, et al.

  19. Upper Gastrointestinal (GI) Tract X-Ray (Radiography)

    MedlinePlus

    ... Resources Professions Site Index A-Z X-ray (Radiography) - Upper GI Tract Upper gastrointestinal tract radiography or ... X-ray? What is Upper Gastrointestinal (GI) Tract Radiography? Upper gastrointestinal tract radiography, also called an upper ...

  20. RhG-CSF improves radiation-induced myelosuppression and survival in the canine exposed to fission neutron irradiation.

    PubMed

    Yu, Zu-Yin; Li, Ming; Han, A-Ru-Na; Xing, Shuang; Ou, Hong-Ling; Xiong, Guo-Lin; Xie, Ling; Zhao, Yan-Fang; Xiao, He; Shan, Ya-Jun; Zhao, Zhen-Hu; Liu, Xiao-Lan; Cong, Yu-Wen; Luo, Qing-Liang

    2011-01-01

    Fission-neutron radiation damage is hard to treat due to its critical injuries to hematopoietic and gastrointestinal systems, and so far few data are available on the therapeutic measures for neutron-radiation syndrome. This study was designed to test the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in dogs which had received 2.3 Gy mixed fission-neutron-γ irradiation with a high ratio of neutrons (~90%). Following irradiation, rhG-CSF treatment induced 100% survival versus 60% in controls. Only two of five rhG-CSF-treated dogs experienced leukopenia (white blood cells [WBC] count < 1.0 × 10(9)/L) and neutropenia (neutrophil [ANC] count < 0.5 × 10(9)/L), whereas all irradiated controls displayed a profound period of leukopenia and neutropenia. Furthermore, administration of rhG-CSF significantly delayed the onset of leukopenia and reduced the duration of leucopenia as compared with controls. In addition, individual dogs in the rhG-CSF-treated group exhibited evident differences in rhG-CSF responsiveness after neutron-irradiation. Finally, histopathological evaluation of the surviving dogs revealed that the incidence and severity of bone marrow, thymus and spleen damage decreased in rhG-CSF-treated dogs as compared with surviving controls. Thus, these results demonstrated that rhG-CSF administration enhanced recovery of myelopoiesis and survival after neutron-irradiation. PMID:21785235

  1. Revised Calculations of the Production Rates for Co Isotopes in Meteorites Using New Cross Sections for Neutron-induced Reactions

    NASA Technical Reports Server (NTRS)

    Sisterson, J. M.; Brooks, F. D.; Buffler, A.; Allie, M. S.; Herbert, M. S.; Nchodu, M. R.; Makupula, S.; Ullmann, J.; Reedy, R. C.; Jones, D. T. L.

    2002-01-01

    New cross section measurements for reactions induced by neutrons with energies greater than 70 MeV are used to calculate the production rates for cobalt isotopes in meteorites and these new calculations are compared to previous estimates. Additional information is contained in the original extended abstract.

  2. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

    PubMed

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed.

  3. Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Bromine and Krypton

    SciTech Connect

    Hoffman, R; Dietrich, F; Bauer, R; Kelley, K; Mustafa, M

    2004-07-23

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of bromine and krypton (34 {le} Z {le} 37, 40 {le} N {le} 47).

  4. Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Samarium, Europium, and Gadolinium

    SciTech Connect

    Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R; Mustafa, M

    2004-11-30

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of samarium, europium and gadolinium (62 {le} Z {le} 64, 82 {le} N {le} 96).

  5. Enrico Fermi's Discovery of Neutron-Induced Artificial Radioactivity:The Recovery of His First Laboratory Notebook

    NASA Astrophysics Data System (ADS)

    Acocella, Giovanni; Guerra, Francesco; Robotti, Nadia

    . We give a short description of the discovery of the first experimental notebook of Enrico Fermi (1901-1954) on his researches during March and April of 1934 on neutron-induced artificial radioactivity, and we point out its relevance for a proper historical and conceptual understanding of those researches.

  6. Shape of spectra and mean energies of prompt fission neutrons from {sup 237}Np fission induced by primary neutrons of energy in the range E{sub n} < 20 MeV

    SciTech Connect

    Svirin, M. I.

    2008-10-15

    An analysis of the spectrum of prompt neutrons originating from {sup 237}Np fission induced by primary neutrons of energy E{sub n} = 14.7 MeV confirms the results obtained previously for {sup 232}Th (E{sub n} = 14.7, 17.7 MeV), {sup 235}U (14.7 MeV), and {sup 238}U (13.2, 14.7, 16, and 17.7 MeV) nuclei. In the experimental spectrum measured in the emissive fission of {sup 237}Np, there is also an excess of soft neutrons in the energy range E < 2 MeV in relation to what follows from a traditional theoretical description that considers two sources of prompt fission neutrons: fully accelerated fission fragments and excited nuclei prior to their separation. In just the same way as in the cases of {sup 232}Th and {sup 235,238}U, the shape of the prompt-fission-neutron spectrum for {sup 237}Np is reproduced theoretically over the entire measured range of secondary-neutron energies upon including nonaccelerated fragments as a third source of neutrons in the computational scheme. A description of the spectra and mean energies of prompt fission neutrons versus the bombarding-neutron energy is obtained on the basis of experimental data and their analysis. The results on mean energies are compared with data on the proton-induced fission of {sup 236,238}U nuclei.

  7. Coded source neutron imaging

    SciTech Connect

    Bingham, Philip R; Santos-Villalobos, Hector J

    2011-01-01

    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.

  8. Neutron scattering study of the field-induced tricritical point in MnSi

    NASA Astrophysics Data System (ADS)

    Kindervater, J.; Bauer, A.; Garst, M.; Janoschek, M.; Martin, N.; Mühlbauer, S.; Häussler, W.; Böni, P.; Pfleiderer, C.

    The intermetallic compound MnSi attracts great scientific interest due to two unusual phase transitions, namely the transition from the conical phase to a skyrmion lattice in small fields and the transition from the helical to the paramagnetic phase without external magnetic field that was recently identified to be a fluctuation induced first-order transition, i.e. a so called Brazovskii-transition. Recent measurements of the specific heat provide striking evidence for a tricritical point (TCP), were the first order transition alters to second order. We report neutron spin echo measurements using the MIEZE technique. The recorded quasi elastic linewidth shows a change of the characteristic spin fluctuations at the TCP. The combination with additional SANS measurements and a generalized Brazovskii theory establishes a consistent picture of the statics and dynamics of the transition. Financial support by ERC-AdG (291079 TOPFIT) and through DFG TRR80 is greatfully acknowledged.

  9. Calculated cross sections for neutron induced reactions on sup 19 F and uncertainties of parameters

    SciTech Connect

    Zhao, Z.X. . Inst. of Atomic Energy); Fu, C.Y.; Larson, D.C. )

    1990-09-01

    Nuclear model codes were used to calculate cross sections for neutron-induced reactions on {sup 19}F for incident energies from 2 to 20 MeV. The model parameters in the codes were adjusted to best reproduce experimental data and are given in this report. The calculated results are compared to measured data and the evaluated values of ENDF/B-V. The covariance matrix for several of the most sensitive model parameters is given based on the scatter of measured data around the theoretical curves and the long-range correlation error of measured data. The results of these calculations form the basis for the new ENDF/B-VI fluorine evaluation. 44 refs., 64 figs., 14 tabs.

  10. Neutron- and proton-induced reactions for analysis of bioenvironmental samples

    SciTech Connect

    Spyrou, N.M.; Altaf, W.J.; Khrbish, Y.S. )

    1988-01-01

    The study of the elemental composition of bioenvironmental samples is of continuing interest in a wide variety of medical and environmental investigations, be it as environmental monitors or as indicators of the state of health and disease of an individual or a population. Nuclear activation methods play an important role in these studies as research tools and in certain cases are employed as rapid, routine analytical techniques. Although the authors have been using instrumental neutron activation analysis as the main technique for obtaining information about elemental composition and concentration, they have also developed techniques, for further or complementary analysis, in which proton-induced reactions have been exploited. Two recent studies, in which the composition of human lung tissue and the elemental concentration in plant samples were determined, have been selected as illustrations of the techniques employed.

  11. Prompt fission neutron spectra from fission induced by 1 to 8 MeV neutrons on {sup 235}U and {sup 239}Pu using the double time-of-flight technique

    SciTech Connect

    Noda, S.; Haight, R. C.; Nelson, R. O.; Devlin, M.; O'Donnell, J. M.; Chatillon, A.; Granier, T.; Belier, G.; Taieb, J.; Kawano, T.; Talou, P.

    2011-03-15

    Prompt fission neutron spectra from {sup 235}U and {sup 239}Pu were measured for incident neutron energies from 1 to 200 MeV at the Weapons Neutron Research facility (WNR) of the Los Alamos Neutron Science Center, and the experimental data were analyzed with the Los Alamos model for the incident neutron energies of 1-8 MeV. A CEA multiple-foil fission chamber containing deposits of 100 mg {sup 235}U and 90 mg {sup 239}Pu detected fission events. Outgoing neutrons were detected by the Fast Neutron-Induced {gamma}-Ray Observer array of 20 liquid organic scintillators. A double time-of-flight technique was used to deduce the neutron incident energies from the spallation target and the outgoing energies from the fission chamber. These data were used for testing the Los Alamos model, and the total kinetic energy parameters were optimized to obtain a best fit to the data. The prompt fission neutron spectra were also compared with the Evaluated Nuclear Data File (ENDF/B-VII.0). We calculate average energies from both experimental and calculated fission neutron spectra.

  12. TANGRA-Setup for the Investigation of Nuclear Fission Induced by 14.1 MeV Neutrons

    NASA Astrophysics Data System (ADS)

    Ruskov, I. N.; Kopatch, Yu. N.; Bystritsky, V. M.; Skoy, V. R.; Shvetsov, V. N.; Hambsch, F.-J.; Oberstedt, S.; Noy, R. Capote; Sedyshev, P. V.; Grozdanov, D. N.; Ivanov, I. Zh.; Aleksakhin, V. Yu.; Bogolubov, E. P.; Barmakov, Yu. N.; Khabarov, S. V.; Krasnoperov, A. V.; Krylov, A. R.; Obhođaš, J.; Pikelner, L. B.; Rapatskiy, V. L.; Rogachev, A. V.; Rogov, Yu. N.; Ryzhkov, V. I.; Sadovsky, A. B.; Salmin, R. A.; Sapozhnikov, M. G.; Slepnev, V. M.; Sudac, D.; Tarasov, O. G.; Valković, V.; Yurkov, D. I.; Zamyatin, N. I.; Zeynalov, Sh. S.; Zontikov, A. O.; Zubarev, E. V.

    The new experimental setup TANGRA (Tagged Neutrons & Gamma Rays), for the investigation of neutron induced nuclear reactions, e.g. (n,xn'), (n,xn'γ), (n,γ), (n,f), on a number of important isotopes for nuclear science and engineering (235,238U, 237Np, 239Pu, 244,245,248Cm) is under construction and being tested at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) in Dubna. The TANGRA setup consists of: a portable neutron generator ING-27, with a 64-pixel Si charge-particle detector incorporated into its vacuum chamber for registering of α-particles formed in the T(d, n)4He reaction, as a source of 14.1 MeV steady-state neutrons radiation with an intensity of ∼5x107n/s; a combined iron (Fe), borated polyethylene (BPE) and lead (Pb) compact shielding-collimator; a reconfigurable multi-detector (neutron plus gamma ray detecting system); a fast computer with 2 (x16 channels) PCI-E 100 MHz ADC cards for data acquisition and hard disk storage; Linux ROOT data acquisition, visualization and analysis software. The signals from the α-particle detector are used to 'tag' the neutrons with the coincident α-particles. Counting the coincidences between the α-particle and the reaction-product detectors in a 20ns time-interval improves the effect/background-ratio by a factor of ∼200 as well as the accuracy in the neutron flux determination, which decreases noticeably the overall experimental data uncertainty.

  13. Early stages of oxidative stress-induced membrane permeabilization: a neutron reflectometry study.

    PubMed

    Smith, Hillary L; Howland, Michael C; Szmodis, Alan W; Li, Qijuan; Daemen, Luke L; Parikh, Atul N; Majewski, Jaroslaw

    2009-03-18

    Neutron reflectometry was used to probe in situ the structure of supported lipid bilayers at the solid-liquid interface during the early stages of UV-induced oxidative degradation. Single-component supported lipid bilayers composed of gel phase, dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and fluid phase, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), phospholipids were exposed to low-dose oxidative stress generated by UV light and their structures were examined by neutron reflectometry. An interrupted illumination mode, involving exposures in 15 min increments with 2 h intervals between subsequent exposures, and a continuous mode involving a single 60 (or 90) min exposure period were employed. In both cases, pronounced differences in the structure of the lipid bilayer after exposure were observed. Interrupted exposure led to a substantial decrease in membrane coverage but preserved its total thickness at reduced scattering length densities. These results indicate that the initial phase during UV-induced membrane degradation involves the formation of hydrophilic channels within the membrane. This is consistent with the loss of some lipid molecules we observe and attendant reorganization of residual lipids forming hemimicellar edges of the hydrophilic channels. In contrast, continuous illumination produced a graded interface of continuously varied scattering length density (and hence hydrocarbon density) extending 100-150 A into the liquid phase. Exposure of a DPPC bilayer to UV light in the presence of a reservoir of unfused vesicles showed low net membrane disintegration during oxidative stress, presumably because of surface back-filling from the bulk reservoir. Chemical evidence for membrane degradation was obtained by mass spectrometry and Fourier transform infrared spectroscopy. Further evidence for the formation of hydrophilic channels was furnished by fluorescence microscopy and imaging ellipsometry data.

  14. Early Stages of Oxidative Stress-Induced Membrane Permeabilization: A Neutron Reflectometry Study

    PubMed Central

    Smith, Hillary L.; Howland, Michael C.; Szmodis, Alan W.; Li, Qijuan; Daemen, Luke L.; Parikh, Atul N.; Majewski, Jaroslaw

    2009-01-01

    Neutron reflectometry was used to probe in situ the structure of supported lipid bilayers at the solid–liquid interface during the early stages of UV-induced oxidative degradation. Single-component supported lipid bilayers composed of gel phase, dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and fluid phase, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), phospholipids were exposed to low-dose oxidative stress generated by UV light and their structures were examined by neutron reflectometry. An interrupted illumination mode, involving exposures in 15 min increments with 2 h intervals between subsequent exposures, and a continuous mode involving a single 60 (or 90) min exposure period were employed. In both cases, pronounced differences in the structure of the lipid bilayer after exposure were observed. Interrupted exposure led to a substantial decrease in membrane coverage but preserved its total thickness at reduced scattering length densities. These results indicate that the initial phase during UV-induced membrane degradation involves the formation of hydrophilic channels within the membrane. This is consistent with the loss of some lipid molecules we observe and attendant reorganization of residual lipids forming hemimicellar edges of the hydrophilic channels. In contrast, continuous illumination produced a graded interface of continuously varied scattering length density (and hence hydrocarbon density) extending 100–150 Å into the liquid phase. Exposure of a DPPC bilayer to UV light in the presence of a reservoir of unfused vesicles showed low net membrane disintegration during oxidative stress, presumably because of surface back-filling from the bulk reservoir. Chemical evidence for membrane degradation was obtained by mass spectrometry and Fourier transform infrared spectroscopy. Further evidence for the formation of hydrophilic channels was furnished by fluorescence microscopy and imaging ellipsometry data. PMID:19275260

  15. Scattered Neutron Tomography Based on A Neutron Transport Inverse Problem

    SciTech Connect

    William Charlton

    2007-07-01

    Neutron radiography and computed tomography are commonly used techniques to non-destructively examine materials. Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions.

  16. Prompt γ-rays from the Fast Neutron Induced Fission on 235,238U and 232Th

    NASA Astrophysics Data System (ADS)

    Lebois, M.; Wilson, J. N.; Halipré, P.; Leniau, B.; Matea, I.; Oberstedt, A.; Oberstedt, S.; Verney, D.

    Preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fast-neutron induced fission of 238U, 232Th and 235U were detected. Thick samples of around 50 g of 238U and 232Th are used for the first part of the experiment. An ionisation chamber containing ∼ 10 mg samples of 238U and 235U to provide a fission trigger is used for the second part of the experiment. Gamma rays have been detected using 17 high efficiency BaF2 detectors and 6 LaBr3 scintillator detectors.

  17. Energy dependence of mass, charge, isotopic, and energy distributions in neutron-induced fission of 235U and 239Pu

    NASA Astrophysics Data System (ADS)

    Pasca, H.; Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.; Kim, Y.

    2016-05-01

    The mass, charge, isotopic, and kinetic-energy distributions of fission fragments are studied within an improved scission-point statistical model in the reactions 235U+n and 239Pu+n at different energies of the incident neutron. The charge and mass distributions of the electromagnetic- and neutron-induced fission of 214,218Ra, 230,232,238U are also shown. The available experimental data are well reproduced and the energy-dependencies of the observable characteristics of fission are predicted for future experiments.

  18. Boron neutron capture therapy induces apoptosis of glioma cells through Bcl-2/Bax

    PubMed Central

    2010-01-01

    treated with BPA-BNCT were significantly higher than those in Group B and Group C irradiated by [60Co] γ-rays (P < 0.01). The clonogenicity of glioma cells was reduced by BPA-BNCT compared with cells treated in the reactor (Group F, G, H, I), and with the control cells (P < 0.01). Upon BPA-BNCT treatment, the Bax level increased in glioma cells, whereas Bcl-2 expression decreased. Conclusions Compared with γ-ray and reactor neutron irradiation, a higher RBE can be achieved upon treatment of glioma cells with BNCT. Glioma cell apoptosis induced by BNCT may be related to activation of Bax and downregulation of Bcl-2. PMID:21122152

  19. Proteomic analysis of cellular response induced by boron neutron capture reaction in human squamous cell carcinoma SAS cells.

    PubMed

    Sato, Akira; Itoh, Tasuku; Imamichi, Shoji; Kikuhara, Sota; Fujimori, Hiroaki; Hirai, Takahisa; Saito, Soichiro; Sakurai, Yoshinori; Tanaka, Hiroki; Nakamura, Hiroyuki; Suzuki, Minoru; Murakami, Yasufumi; Baiseitov, Diaz; Berikkhanova, Kulzhan; Zhumadilov, Zhaxybay; Imahori, Yoshio; Itami, Jun; Ono, Koji; Masunaga, Shinichiro; Masutani, Mitsuko

    2015-12-01

    To understand the mechanism of cell death induced by boron neutron capture reaction (BNCR), we performed proteome analyses of human squamous tumor SAS cells after BNCR. Cells were irradiated with thermal neutron beam at KUR after incubation under boronophenylalanine (BPA)(+) and BPA(-) conditions. BNCR mainly induced typical apoptosis in SAS cells 24h post-irradiation. Proteomic analysis in SAS cells suggested that proteins functioning in endoplasmic reticulum, DNA repair, and RNA processing showed dynamic changes at early phase after BNCR and could be involved in the regulation of cellular response to BNCR. We found that the BNCR induces fragments of endoplasmic reticulum-localized lymphoid-restricted protein (LRMP). The fragmentation of LRMP was also observed in the rat tumor graft model 20 hours after BNCT treatment carried out at the National Nuclear Center of the Republic of Kazakhstan. These data suggest that dynamic changes of LRMP could be involved during cellular response to BNCR.

  20. Excited states in neutron-rich 188W produced by an 18O-induced 2-neutron transfer reaction

    NASA Astrophysics Data System (ADS)

    Shizuma, T.; Ishii, T.; Makii, H.; Hayakawa, T.; Shigematsu, S.; Matsuda, M.; Ideguchi, E.; Zheng, Y.; Liu, M.; Morikawa, T.; Walker, P. M.; Oi, M.

    2006-11-01

    Excited states in neutron-rich 188W have been populated using a 186W(18O,16O) reaction. In-beam γ-rays were measured in coincidence with scattered particles detected by a high-resolution ΔE-E Si telescope. In this experiment, the ground-state band has been identified up to I π = 8+. The γ band, the K π = 2- octupole band, and a 2-quasiparticle state were also observed. The results are compared with predictions of self-consistent HFB cranking calculations and blocked-BCS multi-quasiparticle calculations.

  1. Neutron-Induced Partial Gamma-Ray Cross-Section Measurements on Actinides at TUNL using a segmented Clover detector

    NASA Astrophysics Data System (ADS)

    Wolter, C.; Crowell, A. S.; Fallin, B.; Howell, C. R.; Macri, R. A.; Tonchev, A. P.; Tornow, W.; Walter, R. L.; Pedroni, R. S.; Weisel, G. J.; Becker, J. A.; Nelson, R. O.

    2004-10-01

    An experimental program is being developed at TUNL to study (n,2n) excitation functions on actinide nuclei using monoenergetic and pulsed neutron beams in the 5 to 18 MeV energy range. Measurements have been performed on a 238U target with incident neutron energies of 6 and 10 MeV using a segmented Clover detector. A study of the detector involving the photopeak efficiency, energy and timing resolution has been performed with radioactive sources and in-beam experiments. Experimental techniques and results for neutron-induced partial gamma-ray cross-section measurements will be presented. Supported by the NNSA under the Stewardship Science Academic Alliances Program through DOE Research grant # DE-FG03-02NA00057 and NSF REU grant # NSF-0243776

  2. Early changes in flow cytometric DNA profiles induced by californium-252 neutron brachytherapy in squamocellular carcinomas of the uterine cervix.

    PubMed

    Tacev, T; Zaloudík, J; Janáková, L; Vagunda, V

    1998-01-01

    Ninety-five squamocellular carcinomas of the uterine cervix, clinical Stages II and III, were treated by either four schedules combining 252-californium neutron-gamma-radiotherapy with different proportions of a neutron component (9, 6 and 3 Gy) or gamma-irradiation alone. Flow cytometric DNA profiles were obtainable in 72 cases before treatment and 56 cases were monitored for DNA content by flow cytometry (FCM) in weekly intervals by analysis of sequential microbiopsies for one month during and after radiotherapy. DNA aneuploidy was reduced from 40% (25/63) to 19% (9/47) one week within therapy in neutron-treated groups, but not after initial gamma-radiotherapy alone. Extinction of DNA aneuploid subpopulations occurred after neutron therapy in all remaining aneuploid tumors (9/9) during further monitoring, but only in 40% (2/5) of tumors after sole gamma-irradiation. In contrast, proliferation index by more than 50% was more often achieved in groups with a higher gamma-radiation component than after neutrons only. When all therapy-induced DNA flow cytometric events are taken together for evaluation of the effects of various radiotherapy schedules, it appears that the regimen with the maximal neutron dose may not be optimal for all tumors. It is hypothesized that the differences in the early flow cytometric DNA profiles may select the DNA aneuploid squamous cell uterine cervical carcinomas as candidates for combined neutron-brachytherapy, while highly proliferating DNA near-diploid tumors may profit more from treatment with a higher gamma-radiotherapy component. However, these early DNA flow cytometric findings need to be correlated with clinical course of the disease to validate this hypothesis, a process which will be completed at the end of the expected five-year clinical outcome in 2000.

  3. GENERAL RELATIVISTIC SIMULATIONS OF ACCRETION INDUCED COLLAPSE OF NEUTRON STARS TO BLACK HOLES

    SciTech Connect

    Giacomazzo, Bruno; Perna, Rosalba

    2012-10-10

    Neutron stars (NSs) in the astrophysical universe are often surrounded by accretion disks. Accretion of matter onto an NS may increase its mass above the maximum value allowed by its equation of state, inducing its collapse to a black hole (BH). Here we study this process for the first time, in three-dimensions, and in full general relativity. By considering three initial NS configurations, each with and without a surrounding disk (of mass {approx}7% M{sub NS}), we investigate the effect of the accretion disk on the dynamics of the collapse and its imprint on both the gravitational wave (GW) and electromagnetic (EM) signals that can be emitted by these sources. We show in particular that, even if the GW signal is similar for the accretion induced collapse (AIC) and the collapse of an NS in vacuum (and detectable only for Galactic sources), the EM counterpart could allow us to discriminate between these two types of events. In fact, our simulations show that, while the collapse of an NS in vacuum leaves no appreciable baryonic matter outside the event horizon, an AIC is followed by a phase of rapid accretion of the surviving disk onto the newly formed BH. The post-collapse accretion rates, on the order of {approx}10{sup -2} M{sub Sun} s{sup -1}, make these events tantalizing candidates as engines of short gamma-ray bursts.

  4. Neutron-induced fission cross section measurements for uranium isotopes 236U and 234U at LANSCE

    NASA Astrophysics Data System (ADS)

    Laptev, A. B.; Tovesson, F.; Hill, T. S.

    2013-04-01

    A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R&D). The incident neutron energy range spans from sub-thermal up to 200 MeV by combining two LANSCE facilities, the Lujan Center and the Weapons Neutron Research facility (WNR). The time-of-flight method is implemented to measure the incident neutron energy. A parallel-plate fission ionization chamber was used as a fission fragment detector. The event rate ratio between the investigated foil and a standard 235U foil is converted into a fission cross section ratio. In addition to previously measured data new measurements include 236U data which is being analyzed, and 234U data acquired in the 2011-2012 LANSCE run cycle. The new data complete the full suite of Uranium isotopes which were investigated with this experimental approach. Obtained data are presented in comparison with existing evaluations and previous data.

  5. Characterization of neutron induced damage effect in several types of metallic multilayer nanocomposites based on Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Chen, Feida; Tang, Xiaobin; Yang, Yahui; Huang, Hai; Liu, Jian; Chen, Da

    2015-09-01

    Metallic multilayer nanocomposites are known to have excellent interface self-healing performance when it comes to repairing irradiation damages, thus showing promise as structural materials for advanced nuclear power systems. The present study investigated the neutron irradiation displacement damage rate, spectra of the primary knocked-on atoms (PKAs) produced in the cascade collision, and the H/He ratio in four kinds of metallic multilayer nanocomposites (Cu/Nb, Ag/V, Fe/W, and Ti/Ta) versus neutrons' energy. Results suggest that the three neutron induced damage effects in all multilayer systems increased with the increasing of incident neutrons' energy. For fission reactor environment (1 MeV), multilayer's displacement damage rate is 5-10 × 1022 dpa/(n/cm2) and the mean PKAs energy is about 16 keV, without any noteworthy H/He produced. Fe/W multilayer seems very suitable among these four systems. For fusion reactor environment (14 MeV), the dominant damage effect varies in different multilayer systems. Fe/W multilayer has the lowest displacement damage under the same neutron flux but its gaseous transmutation production is the highest. Considering the displacement damage and transmutation, the irradiation resistance of Ag/V and Ti/Ta systems seems much greater than those of the other two.

  6. Neutron tomography developments and applications.

    PubMed

    Richards, W J; Gibbons, M R; Shields, K C

    2004-10-01

    Neutron radiography has been in use as a nondestructive testing technique for the past 50 years. The neutrons' unique ability to image certain elements and isotopes that are either completely undetectable or poorly detected by other NDI methods makes neutron radiography an important tool for the NDI community. Neutron radiography like other imaging techniques takes a number of different forms (i.e., film, radioscopic, transfer methods, tomography, etc.) This paper will describe the neutron tomography system developed at the University of California, Davis McClellan Nuclear Radiation Center (UC Davis/MNRC), and the applications for both research and commercial uses. The neutron radiography system at the UC Davis/MNRC has been under development for 4 years. The initial system was developed to find very low concentrations of hydrogen (i.e., <200 ppm). In order to achieve these low detection levels, it was necessary to perform both pre- and post-processing of the tomographs. The pre-processing steps include corrections for spatial resolution and random noise effects. Images are corrected for systematic noise errors and beam hardening. From these data the attenuation coefficient is calculated. The post-processing steps include alignment of the collected images, determining the center of mass, and, finally, using the filtered back-projection routine from the Donner Algorithms Library to obtain the final images. Since its initial development, the tomography system has been used very successfully to find low levels of hydrogen in a metal matrix. Further uses of the system have been to verify the exact placement, in three dimensions, of "O-rings" in large metal valve bodies, and to map the location and extent of veins in porous and high-density rocks of various different kinds. These examples show that neutron tomography is becoming a needed inspection technique for the 21st century. PMID:15246398

  7. Radiation-induced stress relaxation in high temperature water of type 316L stainless steel evaluated by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Ishiyama, Y.; Rogge, R. B.; Obata, M.

    2011-01-01

    Weld beads on plate specimens made of type 316L stainless steel were neutron-irradiated up to about 2.5 × 10 25 n/m 2 ( E > 1 MeV) at 561 K in the Japan Material Testing Reactor (JMTR). Residual stresses of the specimens were measured by the neutron diffraction method, and the radiation-induced stress relaxation was evaluated. The values of σ x residual stress (transverse to the weld bead) and σ y residual stress (longitudinal to the weld bead) decreased with increasing neutron dose. The tendency of the stress relaxation was almost the same as previously published data, which were obtained for type 304 stainless steel. From this result, it was considered that there was no steel type dependence on radiation-induced stress relaxation. The neutron irradiation dose dependence of the stress relaxation was examined using an equation derived from the irradiation creep equation. The coefficient of the stress relaxation equation was obtained, and the value was 1.4 (×10 -6/MPa/dpa). This value was smaller than that of nickel alloy.

  8. Boron neutron capture therapy induces cell cycle arrest and cell apoptosis of glioma stem/progenitor cells in vitro

    PubMed Central

    2013-01-01

    Background Glioma stem cells in the quiescent state are resistant to clinical radiation therapy. An almost inevitable glioma recurrence is due to the persistence of these cells. The high linear energy transfer associated with boron neutron capture therapy (BNCT) could kill quiescent and proliferative cells. Methods The present study aimed to evaluate the effects of BNCT on glioma stem/progenitor cells in vitro. The damage induced by BNCT was assessed using cell cycle progression, apoptotic cell ratio and apoptosis-associated proteins expression. Results The surviving fraction and cell viability of glioma stem/progenitor cells were decreased compared with differentiated glioma cells using the same boronophenylalanine pretreatment and the same dose of neutron flux. BNCT induced cell cycle arrest in the G2/M phase and cell apoptosis via the mitochondrial pathway, with changes in the expression of associated proteins. Conclusions Glioma stem/progenitor cells, which are resistant to current clinical radiotherapy, could be effectively killed by BNCT in vitro via cell cycle arrest and apoptosis using a prolonged neutron irradiation, although radiosensitivity of glioma stem/progenitor cells was decreased compared with differentiated glioma cells when using the same dose of thermal neutron exposure and boronophenylalanine pretreatment. Thus, BNCT could offer an appreciable therapeutic advantage to prevent tumor recurrence, and may become a promising treatment in recurrent glioma. PMID:23915425

  9. Comparative measurement of prompt fission γ -ray emission from fast-neutron-induced fission of 235U and 238U

    NASA Astrophysics Data System (ADS)

    Lebois, M.; Wilson, J. N.; Halipré, P.; Oberstedt, A.; Oberstedt, S.; Marini, P.; Schmitt, C.; Rose, S. J.; Siem, S.; Fallot, M.; Porta, A.; Zakari, A.-A.

    2015-09-01

    Prompt fission γ -ray (PFG) spectra have been measured in a recent experiment with the novel directional fast-neutron source LICORNE at the ALTO facility of the IPN Orsay. These first results from the facility involve the comparative measurement of prompt γ emission in fast-neutron-induced fission of 235U and 238U . Characteristics such as γ multiplicity and total and average radiation energy are determined in terms of ratios between the two systems. Additionally, the average photon energies were determined and compared with recent data on thermal-neutron-induced fission of 235U . PFG spectra are shown to be similar within the precision of the present measurement, suggesting that the extra incident energy does not significantly impact the energy released by prompt γ rays. The origins of some small differences, depending on either the incident energy or the target mass, are discussed. This study demonstrates the potential of the present approach, combining an innovative neutron source and new-generation detectors, for fundamental and applied research on fission in the near future.

  10. Embossed radiography utilizing energy subtraction.

    PubMed

    Osawa, Akihiro; Watanabe, Manabu; Sato, Eiichi; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; Aizawa, Katsuo; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ehara, Shigeru; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2009-01-01

    Currently, it is difficult to carry out refraction-contrast radiography by using a conventional X-ray generator. Thus, we developed an embossed radiography system utilizing dual-energy subtraction for decreasing the absorption contrast in unnecessary regions, and the contrast resolution of a target region was increased by use of image-shifting subtraction and a linear-contrast system in a flat panel detector (FPD). The X-ray generator had a 100-microm-focus tube. Energy subtraction was performed at tube voltages of 45 and 65 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. A 1.0-mm-thick aluminum filter was used for absorbing low-photon-energy bremsstrahlung X-rays. Embossed radiography was achieved with cohesion imaging by use of the FPD with pixel sizes of 48 x 48 microm, and the shifting dimension of an object in the horizontal direction ranged from 100 to 200 microm. At a shifting distance of 100 mum, the spatial resolutions in the horizontal and vertical directions measured with a lead test chart were both 83 microm. In embossed radiography of non-living animals, we obtained high-contrast embossed images of fine bones, gadolinium oxide particles in the kidney, and coronary arteries approximately 100 microm in diameter. PMID:20821133

  11. Study of the muon-induced neutron background with the LVD detector

    SciTech Connect

    Menghetti, H.; Selvi, M.

    2005-09-08

    High energy neutrons, generated as a product of cosmic muon interaction in the rock or in the detector passive material, represent the most dangerous background for a large list of topics like reactor neutrino studies, the search for SN relic neutrinos, solar antineutrinos, etc.Up to now there are few measurements of the muon-produced neutron flux at large depth underground. Moreover it is difficult to reproduce the measured data with Monte Carlo simulation because of the large uncertainties in the neutron production and propagation models.We present here the results of such a measurement with the LVD detector, which is well suited for the detection of neutrons produced by cosmic-ray muons, reporting the neutron flux at various distances from the muon track, for different neutron energies (E > 20 MeV) and as a function of the muon track length in scintillator.

  12. Particular features of ternary fission induced by polarized neutrons in the major actinides U,235233 and Pu,241239

    NASA Astrophysics Data System (ADS)

    Gagarski, A.; Gönnenwein, F.; Guseva, I.; Jesinger, P.; Kopatch, Yu.; Kuzmina, T.; Lelièvre-Berna, E.; Mutterer, M.; Nesvizhevsky, V.; Petrov, G.; Soldner, T.; Tiourine, G.; Trzaska, W. H.; Zavarukhina, T.

    2016-05-01

    Ternary fission in (n ,f ) reactions was studied with polarized neutrons for the isotopes U,235233 and Pu,241239. A cold longitudinally polarized neutron beam was available at the High Flux Reactor of the Institut Laue-Langevin in Grenoble, France. The beam was hitting the fissile targets mounted at the center of a reaction chamber. Detectors for fission fragments and ternary particles were installed in a plane perpendicular to the beam. In earlier work it was discovered that the angular correlations between neutron spin and the momenta of fragments and ternary particles were very different for 233U or 235U. These correlations could now be shown to be simultaneously present in all of the above major actinides though with different weights. For one of the correlations it was observed that up to scission the compound nucleus is rotating with the axis of rotation parallel to the neutron beam polarization. Entrained by the fragments also the trajectories of ternary particles are turned away albeit by a smaller angle. The difference in turning angles becomes observable upon reversing the sense of rotation by flipping neutron spin. All turning angles are smaller than 1∘. The phenomenon was called the ROT effect. As a distinct second phenomenon it was found that for fission induced by polarized neutrons an asymmetry in the emission probability of ternary particles relative to a plane formed by fragment momentum and neutron spin appears. The asymmetry is attributed to the Coriolis force present in the nucleus while it is rotating up to scission. The size of the asymmetry is typically 10-3. This asymmetry was termed the TRI effect. The interpretation of both effects is based on the transition state model. Both effects are shown to be steered by the properties of the collective (J ,K ) transition states which are specific for any of the reactions studied. The study of asymmetries of ternary particle emission in fission induced by slow polarized neutrons provides a new

  13. Genetic effects induced by neutrons in Drosophila melanogaster I. Determination of absorbed dose.

    PubMed

    Delfin, A; Paredes, L C; Zambrano, F; Guzmán-Rincón, J; Ureña-Nuñez, F

    2001-12-01

    A method to obtain the absorbed dose in Drosophila melanogaster irradiated in the thermal column facility of the Triga Mark III Reactor has been developed. The method is based on the measurements of neutron activation of gold foils produced by neutron capture to obtain the neutron fluxes. These fluxes, combined with the calculations of kinetic energy released per unit mass, enables one to obtain the absorbed doses in Drosophila melanogaster. PMID:11761104

  14. Borehole parametric study for neutron induced capture gamma-ray spectrometry using the MCNP code.

    PubMed

    Shahriari, M; Sohrabpour, M

    2000-01-01

    The MCNP Monte Carlo code has been used to simulate neutron transport from an Am-Be source into a granite formation surrounding a borehole. The effects of the moisture and the neutron poison on the thermal neutron flux distribution and the capture by the absorbing elements has been calculated. Thermal and nonthermal captures for certain absorbers having resonance structures in the epithermal and fast energy regions such as W and Si were performed. It is shown that for those absorbers having large resonances in the epithermal regions when they are present in dry formation or when accompanied by neutron poisons the resonance captures may be significant compared to the thermal captures.

  15. Neutron-induced charged-particle emission studies below 100 MeV at WNR

    SciTech Connect

    Haight, R.C.; Lee, T.M.; Sterbenz, S.M.

    1994-07-01

    Charged-particles produced by neutron bombardment of selected targets with Z=5 through 53 have been studied for neutron energies from 1 MeV to about 100 MeV using the spallation neutron source at WNR/LAMPF. Particle detection with energy measurement and particle identification is accomplished by two-element {Delta}E-E counters, three-element {Delta}E{sub l}-{Delta}E{sub 2}-E counters or with pulse-shape discrimination using scintillators directly in the neutron beam. The experimental techniques for these measurements are described and comparisons made among the different approaches. This presentation introduces five papers contributed to this conference.

  16. The application of neutron diffraction to stress mapping in pipeline steels: Measurement of residual, applied, and defect-induced stresses

    SciTech Connect

    Clapham, L.; Krause, T.W.; Olsen, H.; Atherton, D.L.; Holden, T.M.

    1996-12-31

    Gas pipelines are inspected for defects including generalized corrosion, localized corrosion and environmentally-induced cracking. The most common in-line corrosion inspection tools utilize the magnetic flux leakage (MFL) technique, which is also sensitive to the pipeline stress state. Accurate determination of the residual, applied (bulk) and local defect-induced stresses is therefore essential to understand how stress affects MFL signals. This paper summarizes the results of the following work: (1) Measurement of residual stresses in a section of X70 pipe, using neutron diffraction. (2) Examination with neutron diffraction of the local stresses surrounding a blind (i.e., 50% through-wall) hole defect in the X70 pipe wall section, when the section is subjected to a bending stress in the hoop direction.

  17. Analysis of Induced Gamma Activation by D-T Neutrons in Selected Fusion Reactor Relevant Materials with EAF-2010

    NASA Astrophysics Data System (ADS)

    Klix, Axel; Fischer, Ulrich; Gehre, Daniel

    2016-02-01

    Samples of lanthanum, erbium and titanium which are constituents of structural materials, insulating coatings and tritium breeder for blankets of fusion reactor designs have been irradiated in a fusion peak neutron field. The induced gamma activities were measured and the results were used to check calculations with the European activation system EASY-2010. Good agreement for the prediction of major contributors to the contact dose rate of the materials was found, but for minor contributors the calculation deviated up to 50%.

  18. Bayesian Evaluation Including Covariance Matrices of Neutron-induced Reaction Cross Sections of {sup 181}Ta

    SciTech Connect

    Leeb, H. Schnabel, G.; Srdinko, Th.; Wildpaner, V.

    2015-01-15

    A new evaluation of neutron-induced reactions on {sup 181}Ta using a consistent procedure based on Bayesian statistics is presented. Starting point of the evaluation is the description of nuclear reactions via nuclear models implemented in TALYS 1.4. A retrieval of experimental data was performed and covariance matrices of the experiments were generated from an extensive study of the corresponding literature. All reaction channels required for a transport file up to 200 MeV have been considered and the covariance matrices of cross section uncertainties for the most important channels are determined. The evaluation has been performed in one step including all available experimental data. A comparison of the evaluated cross sections and spectra with experimental data and available evaluations is performed. In general the evaluated cross section reflect our best knowledge and give a fair description of the observables. However, there are few deviations from expectation which clearly indicate the impact of the prior and the need to account for model defects. Using the results of the evaluation a complete ENDF-file similarly to those of the TENDL library is generated.

  19. Frequency-Induced Bulk Magnetic Domain-Wall Freezing Visualized by Neutron Dark-Field Imaging

    NASA Astrophysics Data System (ADS)

    Betz, B.; Rauscher, P.; Harti, R. P.; Schäfer, R.; Van Swygenhoven, H.; Kaestner, A.; Hovind, J.; Lehmann, E.; Grünzweig, C.

    2016-08-01

    We use neutron dark-field imaging to visualize and interpret the response of bulk magnetic domain walls to static and dynamic magnetic excitations in (110)-Goss textured iron silicon high-permeability steel alloy. We investigate the domain-wall motion under the influence of an external alternating sinusoidal magnetic field. In particular, we perform scans combining varying levels of dcoffset (0 - 30 A /m ) , oscillation amplitude Aac (0 - 1500 A /m ) , and frequency fac ((0 - 200 Hz ) . By increasing amplitude Aac while maintaining constant values of dcoffset and fac , we record the transition from a frozen domain-wall structure to a mobile one. Vice versa, increasing fac while keeping Aac and dcoffset constant led to the reverse transition from a mobile domain-wall structure into a frozen one. We show that varying both Aac and fac shifts the position of the transition region. Furthermore, we demonstrate that higher frequencies require higher oscillation amplitudes to overcome the freezing phenomena. The fundamental determination and understanding of the frequency-induced freezing process in high-permeability steel alloys is of high interest to the further development of descriptive models for bulk macromagnetic phenomena. Likewise, the efficiency of transformers can be improved based on our results, since these alloys are used as transformer core material.

  20. Improvement of the cold neutron beam line (CN-3) in KUR for neutron optical device development

    NASA Astrophysics Data System (ADS)

    Kawabata, Yuji; Hino, Masahiro; Tasaki, Seiji; Ebisawa, Toru; Maruyama, Ryuji; Horie, Takashi

    2002-01-01

    The cold neutron beam line CN-3 in Kyoto University Reactor (KUR) is being renewed for dedicating to the development of neutron optical devices. CN-3 has a supermirror guide tube with the cross-section of 20 mm (width)× 90 mm (height), and the wide-band neutron spectrum is available. New beam lines are prepared for both time-of-flight (TOF) and monochromatic experiments including a neutron reflectivity measurement. It has a polarized neutron option with a very low magnetic field to cope with polarized neutron devices. In particular, the TOF mode will be used for developing devices, which are suitable for pulsed neutron sources. Cold neutron radiography is also available within a space of 1 m×0.8 m. A neutron imaging plate system is prepared as the neutron imaging detection.

  1. Radiographie par rayons X à haute résolution de défauts topologiques en volume de structures modulées comparée aux neutrons en faisceau blanc

    NASA Astrophysics Data System (ADS)

    Fernandez Palacio, J.; Hamelin, B.; Marmeggi, J. C.

    2004-11-01

    Une émission de rayons X par un générateur à haute tension (plage : 50 - 410 kV) a été développée pour être utilisée avec un diffractomètre à rayons X durs et caractériser en volume des monocristaux. Le fort flux issu d'une installation de radiologie à foyer fin avec un grand pouvoir de pénétration en profondeur autorise l'étude d'échantillons très absorbants. Quelques exemples de l'utilisation de ces propriétés pour des échantillons épais et très absorbants sont présentés ; principalement l'analyse de contraintes et la topographie X projetée 2D dans des matériaux en comparaison avec l'information par la diffraction des neutrons. La diffraction à haute énergie apparaît dans la direction transmise, les angles de Bragg sont petits et ainsi les différentes lignes de réflexions sont réparties autour du faisceau principal. La presse uni-axiale utilisée pour les expériences est optimisée effectivement avec l'absence d'un bruit de fond dû à l'usage de fentes. L'optique des rayons X durs et neutrons appliquée aux échantillons épais donne une information complémentaire dans les expériences sur l'analyse de la densité volumétrique par la diffusion des rayons X et neutrons. On l'applique à des problèmes concernant des cristaux aux structures modulées étudiées sous des charges mécaniques et thermiques.

  2. Characterization of the image quality in neutron radioscopy

    NASA Astrophysics Data System (ADS)

    Brunner, J.; Engelhardt, M.; Frei, G.; Gildemeister, A.; Lehmann, E.; Hillenbach, A.; Schillinger, B.

    2005-04-01

    Neutron radioscopy, or dynamic neutron radiography, is a non-destructive testing method, which has made big steps in the last years. Depending on the neutron flux, the object and the detector, for single events a time resolution down to a few milliseconds is possible. In the case of repetitive processes the object can be synchronized with the detector and better statistics in the image can be reached by adding radiographies of the same phase with a time resolution down to 100 μs. By stepwise delaying the trigger signal a radiography movie can be composed. Radiography images of a combustion engine and an injection nozzle were evaluated quantitatively by different methods trying to characterize the image quality of an imaging system. The main factors which influence the image quality are listed and discussed.

  3. A neutron diffraction and magnetic Barkhausen noise evaluation of defect-induced stress concentrations

    NASA Astrophysics Data System (ADS)

    Sabet-Sharghi, Riaz

    This thesis studies the effect of altering both the drilling technique (mechanical drilling vs. Electro-Chemical Milling) and the sequence of defect introduction and load application on the defect-induced stress distributions in sections of line pipe steel material. The defect-induced stress concentrations in loaded samples with defects introduced whilst loaded (in-situ) and prior to the application of load (pre-drilled) were examined using both neutron diffraction and Magnetic Barkhausen Noise (MBN). These results indicated the presence of potentially large levels of residual stress particularly in the in-situ sample. This is believed to be a result of plastic deformation being introduced by the mechanical drilling process. Similar studies on ECM defects showed no signs of drilling-induced stresses. Experimental stress distribution results from the in-situ and pre-drilled samples were compared to those predicted using a three-dimensional finite element model solution. The overall level of agreement was found to be best for the pre-drilled sample case. The study also aimed to determine the effectiveness of MBN as a non-destructive method for characterizing line pipe samples. Results of an initial experiment are presented showing the effectiveness of MBN for performing quantitative strain analysis on samples. This was determined by comparing MBN-measured stress concentrations with those predicted by theory and reported in the literature. Magnetic Flux Leakage (MFL) tests were also performed on the samples in order to examine any stress-induced differences in MFL response. It was found that the differences in stress distribution between the in-situ and pre-drilled samples were also reflected in the trend of the MFL signal amplitude and shape as a function of applied stress. The original work in this thesis includes the first definitive test of the effects of the order of load application and defect introduction on the resulting stress distributions around through

  4. Neutron yield enhancement in laser-induced deuterium-deuterium fusion using a novel shaped target.

    PubMed

    Zhao, J R; Zhang, X P; Yuan, D W; Chen, L M; Li, Y T; Fu, C B; Rhee, Y J; Li, F; Zhu, B J; Li, Yan F; Liao, G Q; Zhang, K; Han, B; Liu, C; Huang, K; Ma, Y; Li, Yi F; Xiong, J; Huang, X G; Fu, S Z; Zhu, J Q; Zhao, G; Zhang, J

    2015-06-01

    Neutron yields have direct correlation with the energy of incident deuterons in experiments of laser deuterated target interaction [Roth et al., Phys. Rev. Lett. 110, 044802 (2013) and Higginson et al., Phys. Plasmas 18, 100703 (2011)], while deuterated plasma density is also an important parameter. Experiments at the Shenguang II laser facility have produced neutrons with energy of 2.45 MeV using d (d, n) He reaction. Deuterated foil target and K-shaped target were employed to study the influence of plasma density on neutron yields. Neutron yield generated by K-shaped target (nearly 10(6)) was two times higher than by foil target because the K-shaped target results in higher density plasma. Interferometry and multi hydro-dynamics simulation confirmed the importance of plasma density for enhancement of neutron yields.

  5. Neutron yield enhancement in laser-induced deuterium-deuterium fusion using a novel shaped target

    SciTech Connect

    Zhao, J. R.; Chen, L. M. Li, Y. T.; Li, F.; Zhu, B. J.; Li, Yan. F.; Liao, G. Q.; Huang, K.; Ma, Y.; Li, Yi. F.; Zhang, X. P.; Fu, C. B.; Yuan, D. W.; Zhang, K.; Han, B.; Zhao, G.; Rhee, Y. J.; Liu, C.; Xiong, J.; Huang, X. G.; and others

    2015-06-15

    Neutron yields have direct correlation with the energy of incident deuterons in experiments of laser deuterated target interaction [Roth et al., Phys. Rev. Lett. 110, 044802 (2013) and Higginson et al., Phys. Plasmas 18, 100703 (2011)], while deuterated plasma density is also an important parameter. Experiments at the Shenguang II laser facility have produced neutrons with energy of 2.45 MeV using d (d, n) He reaction. Deuterated foil target and K-shaped target were employed to study the influence of plasma density on neutron yields. Neutron yield generated by K-shaped target (nearly 10{sup 6}) was two times higher than by foil target because the K-shaped target results in higher density plasma. Interferometry and multi hydro-dynamics simulation confirmed the importance of plasma density for enhancement of neutron yields.

  6. Neutron Based Imaging and Element-mapping at the Budapest Neutron Centre

    NASA Astrophysics Data System (ADS)

    Kis, Z.; Szentmiklósi, L.; Belgya, T.; Balaskó, M.; Horváth, L. Z.; Maróti, B.

    The Budapest Neutron Centre (BNC) is a consortium of institutes to co-ordinate research activities carried out at the Budapest Research Reactor. It hosts two neutron imaging facilities (RAD and NORMA) operated by the Centre for Energy Research, Hungarian Academy of Sciences and offers access to this scientific infrastructure for the domestic and international users. The radiography station (RAD) at the thermal neutron beamline of the reactor gives a possibility to study relatively large objects by thermal neutron-, gamma- and X-ray radiography, and to benefit from the complementary features of the different radiations. RAD is being extended in 2014 with digital imaging and tomographic capabilities. The image detection is based on suitable converter screens. The static radiography and tomography images are acquired by a new, large area sCMOS camera, whereas the dynamic radiography is accomplished by a low-light-level TV camera and a frame grabber card. The NORMA facility is designed to perform neutron radiography and tomography on small samples using guided cold neutrons. Here two non-destructive techniques are coupled to determine the chemical composition and to visualize the internal structure of heterogeneous objects. The position-sensitive element analysis with prompt-gamma activation analysis (PGAA) and the imaging with neutron radiography/tomography (NR/NT) are integrated into a unique facility called NIPS-NORMA. The goal of such a combination of these methods is to save substantial beam time in the so-called NR/NT-driven PGAI (Prompt Gamma Activation Imaging) mode, in which the interesting regions are first visualized and located, and subsequently the time-consuming prompt-gamma measurements are made only where it is really needed. The paper will give an overview about the technical details of the facilities, and the latest results of selected applications from the fields of archaeometry, engineering and material science.

  7. Measurement Of Gas Bubbles In Mercury Using Proton Radiography

    SciTech Connect

    Riemer, Bernie; Bingham, Philip R; Mariam, Fesseha G; Merrill, Frank E

    2007-01-01

    An experiment using proton radiography on a small mercury loop for testing gas bubble injection was conducted at the Los Alamos Neutron Science Center (LANSCE) in December 2006. Small gas bubble injection is one of the approaches under development to reduce cavitation damage in the U.S. Spallation Neutron Source mercury target vessel. Several hundred radiograph images were obtained as the test loop was operated over range of conditions that included two jet type bubble generators, two needle type bubble generators, various mercury flow speeds and gas injection rates, and use of helium, argon and xenon. This paper will describe the analysis of the radiograph images and present the obtained bubble measurement data.

  8. Neutron Transport Characteristics of a Nuclear Reactor Based Dynamic Neutron Imaging System

    SciTech Connect

    Khaial, Anas M.; Harvel, Glenn D.; Chang, Jen-Shih

    2006-07-01

    An advanced dynamic neutron imaging system has been constructed in the McMaster Nuclear Reactor (MNR) for nondestructive testing and multi-phase flow studies in energy and environmental applications. A high quality neutron beam is required with a thermal neutron flux greater than 5.0 x 10{sup 6} n/cm{sup 2}-s and a collimation ratio of 120 at image plane to promote high-speed neutron imaging up to 2000 frames per second. Neutron source strength and neutron transport have been experimentally and numerically investigated. Neutron source strength at the beam tube entrance was evaluated experimentally by measuring the thermal and fast neutron fluxes, and simple analytical neutron transport calculations were performed based upon these measured neutron fluxes to predict facility components in accordance with high-speed dynamic neutron imaging and operation safety requirements. Monte-Carlo simulations (using MCNP-4B code) with multiple neutron energy groups have also been used to validate neutron beam parameters and to ensure shielding capabilities of facility shutter and cave walls. Neutron flux distributions at the image plane and the neutron beam characteristics were experimentally measured by irradiating a two-dimensional array of Copper foils and using a real-time neutron radiography system. The neutron image characteristics -- such as neutron flux, image size, beam quality -- measured experimentally and predicted numerically for beam tube, beam shutter and radiography cave are compared and discussed in detail in this paper. The experimental results show that thermal neutron flux at image plane is nearly uniform over an imaging area of 20.0-cm diameter and its magnitude ranges from 8.0 x 10{sup 6} - 1.0 x 10{sup 7} n/cm{sup 2}-sec while the neutron-to-gamma ratio is 6.0 x 10{sup 5} n/cm{sup 2}-{mu}Sv. (authors)

  9. Chest radiography in dust-exposed miners: Promise and problems, potential and imperfections

    SciTech Connect

    Wagner, G.R.; Attfield, M.D.; Parker, J.E. )

    1993-01-01

    Since the early 1900s, it was recognized that many dust-exposed workers developed abnormal radiographs during life. Chest radiography remains the primary means of determining the presence and extent of dust-induced pneumoconiosis, although it is ineffective for detecting airways obstructions from mine dust exposure. This chapter reviews the uses and limitations of chest radiography in the study, surveillance, screening, clinical diagnosis, and disability determinations of occupational lung diseases in dust-exposed workers. 70 refs.

  10. Time features of delayed neutrons and partial emissive-fission cross sections for the neutron-induced fission of {sup 232}Th nuclei in the energy range 3.2-17.9 MeV

    SciTech Connect

    Roshchenko, V. A. Piksaikin, V. M. Korolev, G. G.; Egorov, A. S.

    2010-06-15

    The energy dependence of the relative abundances of delayed neutrons and the energy dependence of the half-lives of their precursors in the neutron-induced fission of {sup 232}Th nuclei in the energy range 3.2-17.9 MeV were measured for the first time. A systematics of the time features of delayed neutrons is developed. This systematics makes it possible to estimate the half-life of delayed-neutron precursors as a function of the nucleonic composition of fissile nuclei by using a single parameter set for all nuclides. The energy dependence of the partial cross sections for emissive fission in the reaction {sup 232}Th(n, f) was analyzed on the basis of data obtained for the relative abundances of delayed neutrons and the aforementioned half-lives and on the basis of the created systematics of the time features of delayed neutrons. It was shown experimentally for the first time that the decrease in the cross section after the reaction threshold in the fission of {sup 232}Th nuclei (it has a pronounced first-chance plateau) is not an exclusion among the already studied uranium, plutonium, and curium isotopes and complies with theoretical predictions obtained for the respective nuclei with allowance for shell, superfluid, and collective effects in the nuclear-level density and with allowance for preequilibrium neutron emission

  11. Smectic order induced at homeotropically aligned nematic surfaces: a neutron reflection study.

    PubMed

    Lau, Y G J; Richardson, Robert M; Cubitt, R

    2006-06-21

    Neutron reflection was used to measure the buildup of layers at a solid surface as the smectic phase is approached from higher temperatures in a nematic liquid crystal. The liquid crystal was 4-octyl-4'-cyanobiphenyl (8CB), and the solid was silicon with one of five different surface treatments that induce homeotropic alignment: (i) silicon oxide; (ii) a cetyltrimethylammonium bromide coating; (iii) an octadecyltrichlorosilane monolayer; (iv) an n-n-dimethyl-n-octadecyl-3- aminopropyltrimethyloxysilyl chloride monolayer; and (v) a lecithin coating. The development of surface smectic layers in the nematic phase of 8CB was followed by measuring specular reflectivity and monitoring the pseudo-Bragg peak from the layers. The scattering data were processed to remove the scattering from short-ranged smecticlike fluctuations in the bulk nematic phase from the specular reflection. The pseudo-Bragg peak at scattering vector Q approximately 0.2 A(-1) therefore corresponded to the formation of long-range smectic layers at the surface. The amplitude of the smectic density wave decayed with increasing distance from the surface, and the characteristic thickness of this smectic region diverged as the transition temperature was approached. It was found that the characteristic thickness for some of the surface treatments was greater than the correlation length in the bulk nematic. The different surfaces gave different values of the smectic order parameter at the surface. This suggests that the interaction with the surface is significantly different from a "hard wall" which would give the same values of the smectic order parameter and penetration depths similar to the bulk correlation length. Comparison of the different surfaces also suggested that the strength and range of the surface smectic ordering may be varied independently. PMID:16821956

  12. Smectic order induced at homeotropically aligned nematic surfaces: A neutron reflection study

    NASA Astrophysics Data System (ADS)

    Lau, Y. G. J.; Richardson, Robert M.; Cubitt, R.

    2006-06-01

    Neutron reflection was used to measure the buildup of layers at a solid surface as the smectic phase is approached from higher temperatures in a nematic liquid crystal. The liquid crystal was 4-octyl-4'-cyanobiphenyl (8CB), and the solid was silicon with one of five different surface treatments that induce homeotropic alignment: (i) silicon oxide; (ii) a cetyltrimethylammonium bromide coating; (iii) an octadecyltrichlorosilane monolayer; (iv) an n-n-dimethyl-n-octadecyl-3- aminopropyltrimethyloxysilyl chloride monolayer; and (v) a lecithin coating. The development of surface smectic layers in the nematic phase of 8CB was followed by measuring specular reflectivity and monitoring the pseudo-Bragg peak from the layers. The scattering data were processed to remove the scattering from short-ranged smecticlike fluctuations in the bulk nematic phase from the specular reflection. The pseudo-Bragg peak at scattering vector Q ˜0.2Å-1 therefore corresponded to the formation of long-range smectic layers at the surface. The amplitude of the smectic density wave decayed with increasing distance from the surface, and the characteristic thickness of this smectic region diverged as the transition temperature was approached. It was found that the characteristic thickness for some of the surface treatments was greater than the correlation length in the bulk nematic. The different surfaces gave different values of the smectic order parameter at the surface. This suggests that the interaction with the surface is significantly different from a "hard wall" which would give the same values of the smectic order parameter and penetration depths similar to the bulk correlation length. Comparison of the different surfaces also suggested that the strength and range of the surface smectic ordering may be varied independently.

  13. Magnon-induced long-range correlations and their neutron-scattering signature in quantum magnets

    NASA Astrophysics Data System (ADS)

    Bharadwaj, S.; Belitz, D.; Kirkpatrick, T. R.

    2016-10-01

    We consider the coupling of the magnetic Goldstone modes, or magnons, in both quantum ferromagnets and antiferromagnets to the longitudinal order-parameter fluctuations and the resulting nonanalytic behavior of the longitudinal susceptibility. In classical magnets it is well known that long-range correlations induced by the magnons lead to a singular wave-number dependence of the form 1 /k4 -d in all dimensions 2 neutron scattering. For both ferromagnets and antiferromagnets there is a logarithmic singularity at the magnon frequency with a prefactor that vanishes as T →0 . In addition, in the antiferromagnetic case there is a nonzero contribution at T =0 that is missing for ferromagnets. Magnon damping due to quenched disorder restores the expected scaling behavior of the longitudinal susceptibility in the ferromagnetic case; it scales as kd -2 if the order parameter is not conserved (magnetic disorder), or as kd if it is (nonmagnetic disorder). Detailed predictions are made for both two- and three-dimensional systems at both T =0 and in the limit of low temperatures, and the physics behind the various nonanalytic behaviors is discussed.

  14. Candidate Reactions for Mercury Detection Induced by Neutron and Alpha Particles

    SciTech Connect

    Toth, James J.; Wittman, Richard S.; Schenter, Robert E.; Cooper, John A.

    2007-03-21

    This paper summarizes modeling of mercury to activated states with alpha particles, neutrons, or deuterons, and the spectral emission from the activated products. Activation can occur with a source such as 242Cf , 241Am-Be, a neutron generator, or a particle accelerator, and the activation products measured if sufficient signal is provided. Identification and measurement of mercury by prompt gamma emission, generated by bombardment with neutrons is reported. Activation product reactions of (α, xn) (d, xn) (n,γ) and (n,p) are screened as candidate reactions. Initial calculations indicate the potential use of either alpha, or 14 MeV neutron activation to assess part per billion concentrations of mercury in the gaseous phase. Ultimately, data from sample analysis of ambient conditions flue gas will be used to assess mercury detection sensitivity and specificity under typical operating conditions.

  15. Calculated neutron-induced cross sections for /sup 53/Cr from 1 to 20 MeV

    SciTech Connect

    Shibata, K.; Hetrick, D.M.

    1987-05-01

    Neutron-induced cross sections of /sup 53/Cr have been calculated in the energy regions from 1 to 20 MeV. The quantities obtained are the cross sections for the reactions (n,n'..gamma..), (n,2n), (n,np), (n,n..cap alpha..), (n,p..gamma..), (n,pn), (n,..cap alpha gamma..), (n,..cap alpha..n), (n,d), (n,t), (n,/sup 3/He), and (n,..gamma..), as well as the spectra of emitted neutrons, protons, alpha particles, and gamma rays. The precompound process was included above 5 MeV in addition to the compound process. For the inelastic scattering, the contribution of the direct interaction was calculated with DWBA. 36 refs., 23 figs., 11 tabs.

  16. Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

    PubMed

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

    2016-04-11

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level.

  17. Investigation of the maximum accessible kinetic energy of fragments in the neutron-induced fission of {sup 238}U nuclei

    SciTech Connect

    Khryachkov, V. A. Bondarenko, I. P.; Ivanova, T. A.; Kuzminov, B. D.; Semenova, N. N.; Sergachev, A. I.

    2013-03-15

    The masses, total kinetic energies (TKE), and emission angles of fragments originating from the fission of {sup 238}U nuclei that was induced by 5- and 6.5-MeV neutrons were measured by using digital methods for processing signals. A detailed analysis of the shape of digital signals made it possible to reduce substantially the contribution of fragments whose TKE values were distorted because of a superimposition of signals from recoil protons and from alpha particles produced in the spontaneous decay of uranium. The total statistics exceeded two million events for either neutron energy, and this permitted performing a detailed analysis of fission-fragment yields in the region of the highest attainable TKE values. An analysis of fragment yields made it possible to draw specific conclusions on the structure of the potential surface of fissile nuclei.

  18. Measurement of the muon-induced neutron yield in liquid scintillator and stainless steel at LNGS with the LVD experiment

    SciTech Connect

    Persiani, R.; Garbini, M.; Sartorelli, G.; Selvi, M.; Collaboration: LVD Collaboration

    2013-08-08

    We describe the measurement of the muon-induced neutron yield in liquid scintillator and stainless steel (SS) at the Gran Sasso National Laboratory (LNGS), with the LVD experiment. The Large Volume Detector (LVD) is located in Hall A of the LNGS and is made of 1000 t of liquid scintillator and 1000 t of SS. Using an independent measurement to evaluate the background and with the support of a full Monte Carlo simulation based on Geant4, we measured a neutron yield of (2.9±0.6)×10{sup −4} and (1.5±0.3)×10{sup −3} in liquid scintillator and in stainless steel, respectively.

  19. Experimental and simulation studies of neutron-induced single-event burnout in SiC power diodes

    NASA Astrophysics Data System (ADS)

    Shoji, Tomoyuki; Nishida, Shuichi; Hamada, Kimimori; Tadano, Hiroshi

    2014-01-01

    Neutron-induced single-event burnouts (SEBs) of silicon carbide (SiC) power diodes have been investigated by white neutron irradiation experiments and transient device simulations. It was confirmed that a rapid increase in lattice temperature leads to formation of crown-shaped aluminum and cracks inside the device owing to expansion stress when the maximum lattice temperature reaches the sublimation temperature. SEB device simulation indicated that the peak lattice temperature is located in the vicinity of the n-/n+ interface and anode contact, and that the positions correspond to a hammock-like electric field distribution caused by the space charge effect. Moreover, the locations of the simulated peak lattice temperature agree closely with the positions of the observed destruction traces. Furthermore, it was theoretically demonstrated that the period of temperature increase of a SiC power device is two orders of magnitude less than that of a Si power device, using a thermal diffusion equation.

  20. Long-range electrostatics-induced two-proton transfer captured by neutron crystallography in an enzyme catalytic site

    DOE PAGESBeta

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen -Hsiang; Parks, Jerry M.; Smith, Jeremy C.; Weiss, Kevin L.; Keen, David A.; Blakeley, Matthew P.; Louis, John M.; et al

    2016-03-09

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other asparticmore » proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level.« less

  1. Cross Sections for Neutron-induced Reactions on Actinide Targets Extracted from Surrogate Experiments: A Status Report

    SciTech Connect

    Escher, J E; Burke, J T; Dietrich, F S; Lesher, S R; Scielzo, N D; Thompson, I J; Younes, W

    2009-10-01

    The Surrogate nuclear reactions method, an indirect approach for determining cross sections for compound-nuclear reactions involving difficult-to-measure targets, is reviewed. Focusing on cross sections for neutron-induced reactions on actinides, we review the successes of past and present applications of the method and assess its uncertainties and limitations. The approximations used in the analyses of most experiments work reasonably well for (n,f) cross sections for neutron energies above 1-2 MeV, but lead to discrepancies for low-energy (n,f) reactions, as well as for (n,{gamma}) applications. Correcting for some of the effects neglected in the approximate analyses leads to improved (n,f) results. We outline steps that will further improve the accuracy and reliability of the Surrogate method and extend its applicability to reactions that cannot be approached with the present implementation of the method.

  2. Evaluation of {sup 28,29,30}Si neutron induced cross sections for ENDF/B-VI

    SciTech Connect

    Hetrick, D.M.; Larson, D.C.; Larson, N.M.; Leal, L.C.; Epperson, S.J.

    1997-04-01

    Separate evaluations have been done for the three stable isotopes of silicon for ENDF/B-VI. The evaluations are based on analysis of experimental data, supplemented by results of nuclear model calculations. The computational methods and the parameters required as input to the nuclear model codes are reviewed. Discussion of the evaluated data given for resonance parameters, neutron induced reaction cross sections, associated angular and energy distributions, and gamma-ray production cross sections is included. Extensive comparisons of the evaluated cross sections to measured data are shown in this report. The evaluations include all necessary data to allow KERMA (Kinetic Energy Released in MAterials) and displacement cross sections to be calculated directly. These quantities are fundamental to studies of neutron heating and radiation damage.

  3. Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

    PubMed

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

    2016-04-11

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level. PMID:26958828

  4. Resonance analysis and evaluation of the sup 235 U neutron induced cross sections

    SciTech Connect

    Leal, L.C.

    1990-06-01

    Neutron cross sections of fissile nuclei are of considerable interest for the understanding of parameters such as resonance absorption, resonance escape probability, resonance self-shielding,and the dependence of the reactivity on temperature. In the present study, new techniques for the evaluation of the {sup 235}U neutron cross sections are described. The Reich-Moore formalism of the Bayesian computer code SAMMY was used to perform consistent R-matrix multilevel analyses of the selected neutron cross-section data. The {Delta}{sub 3}-statistics of Dyson and Mehta, along with high-resolution data and the spin-separated fission cross-section data, have provided the possibility of developing a new methodology for the analysis and evaluation of neutron-nucleus cross sections. The results of the analysis consists of a set of resonance parameters which describe the {sup 235}U neutron cross sections up to 500 eV. The set of resonance parameters obtained through a R-matrix analysis are expected to satisfy statistical properties which lead to information on the nuclear structure. The resonance parameters were tested and showed good agreement with the theory. It is expected that the parametrization of the {sub 235}U neutron cross sections obtained in this dissertation represents the current state of art in data as well as in theory and, therefore, can be of direct use in reactor calculations. 44 refs., 21 figs., 8 tabs.

  5. Principles and status of neutron-based inspection technologies

    NASA Astrophysics Data System (ADS)

    Gozani, Tsahi

    2011-06-01

    Nuclear based explosive inspection techniques can detect a wide range of substances of importance for a wide range of objectives. For national and international security it is mainly the detection of nuclear materials, explosives and narcotic threats. For Customs Services it is also cargo characterization for shipment control and customs duties. For the military and other law enforcement agencies it could be the detection and/or validation of the presence of explosive mines, improvised explosive devices (IED) and unexploded ordnances (UXO). The inspection is generally based on the nuclear interactions of the neutrons (or high energy photons) with the various nuclides present and the detection of resultant characteristic emissions. These can be discrete gamma lines resulting from the thermal neutron capture process (n,γ) or inelastic neutron scattering (n,n'γ) occurring with fast neutrons. The two types of reactions are generally complementary. The capture process provides energetic and highly penetrating gamma rays in most inorganic substances and in hydrogen, while fast neutron inelastic scattering provides relatively strong gamma-ray signatures in light elements such as carbon and oxygen. In some specific important cases unique signatures are provided by the neutron capture process in light elements such as nitrogen, where unusually high-energy gamma ray is produced. This forms the basis for key explosive detection techniques. In some cases the elastically scattered source (of mono-energetic) neutrons may provide information on the atomic weight of the scattering elements. The detection of nuclear materials, both fissionable (e.g., 238U) and fissile (e.g., 235U), are generally based on the fissions induced by the probing neutrons (or photons) and detecting one or more of the unique signatures of the fission process. These include prompt and delayed neutrons and gamma rays. These signatures are not discrete in energy (typically they are continua) but temporally

  6. Evaluation of the ²³⁹Pu prompt fission neutron spectrum induced by neutrons of 500 keV and associated covariances

    DOE PAGESBeta

    Neudecker, D.; Talou, P.; Kawano, T.; Smith, D. L.; Capote, R.; Rising, M. E.; Kahler, A. C.

    2015-08-01

    We present evaluations of the prompt fission neutron spectrum (PFNS) of ²³⁹Pu induced by 500 keV neutrons, and associated covariances. In a previous evaluation by Talou et al. 2010, surprisingly low evaluated uncertainties were obtained, partly due to simplifying assumptions in the quantification of uncertainties from experiment and model. Therefore, special emphasis is placed here on a thorough uncertainty quantification of experimental data and of the Los Alamos model predicted values entering the evaluation. In addition, the Los Alamos model was extended and an evaluation technique was employed that takes into account the qualitative differences between normalized model predicted valuesmore » and experimental shape data. These improvements lead to changes in the evaluated PFNS and overall larger evaluated uncertainties than in the previous work. However, these evaluated uncertainties are still smaller than those obtained in a statistical analysis using experimental information only, due to strong model correlations. Hence, suggestions to estimate model defect uncertainties are presented, which lead to more reasonable evaluated uncertainties. The calculated keff of selected criticality benchmarks obtained with these new evaluations agree with each other within their uncertainties despite the different approaches to estimate model defect uncertainties. The keff one standard deviations overlap with some of those obtained using ENDF/B-VII.1, albeit their mean values are further away from unity. Spectral indexes for the Jezebel critical assembly calculated with the newly evaluated PFNS agree with the experimental data for selected (n,γ) and (n,f) reactions, and show improvements for high-energy threshold (n,2n) reactions compared to ENDF/B-VII.1.« less

  7. Evaluation of the ²³⁹Pu prompt fission neutron spectrum induced by neutrons of 500 keV and associated covariances

    SciTech Connect

    Neudecker, D.; Talou, P.; Kawano, T.; Smith, D. L.; Capote, R.; Rising, M. E.; Kahler, A. C.

    2015-08-01

    We present evaluations of the prompt fission neutron spectrum (PFNS) of ²³⁹Pu induced by 500 keV neutrons, and associated covariances. In a previous evaluation by Talou et al. 2010, surprisingly low evaluated uncertainties were obtained, partly due to simplifying assumptions in the quantification of uncertainties from experiment and model. Therefore, special emphasis is placed here on a thorough uncertainty quantification of experimental data and of the Los Alamos model predicted values entering the evaluation. In addition, the Los Alamos model was extended and an evaluation technique was employed that takes into account the qualitative differences between normalized model predicted values and experimental shape data. These improvements lead to changes in the evaluated PFNS and overall larger evaluated uncertainties than in the previous work. However, these evaluated uncertainties are still smaller than those obtained in a statistical analysis using experimental information only, due to strong model correlations. Hence, suggestions to estimate model defect uncertainties are presented, which lead to more reasonable evaluated uncertainties. The calculated keff of selected criticality benchmarks obtained with these new evaluations agree with each other within their uncertainties despite the different approaches to estimate model defect uncertainties. The keff one standard deviations overlap with some of those obtained using ENDF/B-VII.1, albeit their mean values are further away from unity. Spectral indexes for the Jezebel critical assembly calculated with the newly evaluated PFNS agree with the experimental data for selected (n,γ) and (n,f) reactions, and show improvements for high-energy threshold (n,2n) reactions compared to ENDF/B-VII.1.

  8. Neutron yields for reactions induced by 120 GeV protons on thick copper target

    SciTech Connect

    Kajimoto, Tsuyoshi; Sanami, Toshiya; Iwamoto, Yosuke; Shigyo, Nobuhiro; Hagiwara, Masayuki; Saitoh, Kiwamu; Nakashima, Hiroshi; Ishibashi, Kenji; Lee, Hee-Seock; Ramberg, Eric; Coleman, Richard; /Fermilab

    2011-02-01

    We developed an experimental method to measure neutron energy spectrum for 120-GeV protons on a thick copper target at Fermilab Test Beam Facility (FTBF). The spectrum in the energy range from 16 to 1600 MeV was obtained for 60-cm long copper target by time-of-flight technique with an NE213 scintillator and 5.5-m flight path. Energy spectra of neutrons generated from an interaction with beam and materials are important to design shielding structure of high energy accelerators. Until now, the energy spectra for the incident energy up to 3 GeV have been measured by several groups, Ishibashi et al., Amian et al., and Leray et al. In the energy region above 3 GeV, few experimental data are available because of small number of facilities for neutron experiment. On the other hand, concerning simulation codes, theoretical models for particle generation and transportation are switched from intermediate to high energy one around this energy. The spectra calculated by the codes have not been examined using experimental data. In shielding experiments using 120 GeV hadron beam, experimental data shows systematic differences from calculations. Hagiwara et al. have measured leakage neutron spectra behind iron and concrete shield from 120 GeV proton on target at anti-proton target station in Fermilab by using Bonner Spheres with unfolding technique. In CERN, Nakao et al reported experimental results of neutron spectra behind iron and concrete wall from 120 GeV/c proton and pion mixed beam on copper by using NE213 liquid scintillators with unfolding technique. Both of the results reported systematic discrepancies between experimental and calculation results. Therefore, experimental data are highly required to verify neutron production part of calculations. In this study, we developed an experimental method to measure neutron energy spectrum for 120 GeV proton on target. The neutron energy was determined using time-of-flight technique. We used the Fermilab Test Beam Facility (FTBF

  9. Measurement of {sup 235}U content and flow of UF{sub 6} using delayed neutrons or gamma rays following induced fission

    SciTech Connect

    Stromswold, D.C.; Peurrung, A.J.; Reeder, P.L.; Perkins, R.W.

    1996-06-01

    Feasibility experiments conducted at Pacific Northwest National Laboratory demonstrate that either delayed neutrons or energetic gamma rays from short-lived fission products can be used to monitor the blending of UF{sub 6} gas streams. A {sup 252}Cf neutron source was used to induce {sup 235}U fission in a sample, and delayed neutrons and gamma rays were measured after the sample moved {open_quotes}down-stream.{close_quotes} The experiments used a UO{sub 2} powder that was transported down the pipe to simulate the flowing UF{sub 6} gas. Computer modeling and analytic calculation extended the test results to a flowing UF{sub 6} gas system. Neutron or gamma-ray measurements made at two downstream positions can be used to indicate both the {sup 235}U content and UF{sub 6} flow rate. Both the neutron and gamma-ray techniques have the benefits of simplicity and long-term reliability, combined with adequate sensitivity for low-intrusion monitoring of the blending process. Alternatively, measuring the neutron emission rate from (a, n) reactions in the UF{sub 6} provides an approximate measure of the {sup 235}U content without using a neutron source to induce fission.

  10. Recent results form measurements of the energy spectrum of cosmic-ray induced neutrons aboard an ER-2 airplane and on the ground.

    PubMed

    Goldhagen, P; Clem, J M; Wilson, J W

    2003-01-01

    Crews of future high-altitude commercial aircraft may be significantly exposed to atmospheric cosmic radiation from galactic cosmic rays (GCR). To help determine such exposures, the Atmospheric Ionizing Radiation Project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on a NASA ER-2 high-altitude aircraft. The primary instrument was a sensitive extended-energy multisphere neutron spectrometer, which was also used to make measurements on the ground. Its detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using the radiation transport code MCNPX. We have now recalculated the detector responses including the effects of the airplane structure. We are also using new FLUKA calculations of GCR-induced hadron spectra in the atmosphere to correct for spectrometer counts produced by charged hadrons. Neutron spectra are unfolded from the corrected measured count rates using the MAXED code. Results for the measured cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron dose equivalent and effective dose rates, and their dependence on altitude and geomagnetic cutoff generally agree well with results from recent calculations of GCR-induced neutron spectra.

  11. Modeling cosmic ray proton induced terrestrial neutron flux: A look-up table

    NASA Astrophysics Data System (ADS)

    Overholt, Andrew C.; Melott, Adrian L.; Atri, Dimitra

    2013-06-01

    contribute a significant radiation dose at commercial passenger airplane altitudes. With cosmic ray energies > 1 GeV, these effects could, in principle, be propagated to ground level. Under current conditions, the cosmic ray spectrum incident on the Earth is dominated by particles with energies < 1 GeV. Astrophysical shocks from events such as supernovae accelerate high-energy cosmic rays (HECRs) well above this range. The Earth is likely episodically exposed to a greatly increased HECR flux from such events. Solar events of smaller energies are much more common and short lived but still remain a topic of interest due to the ground level enhancements they produce. The air showers produced by cosmic rays (CRs) ionize the atmosphere and produce harmful secondary particles such as muons and neutrons. Although the secondary spectra from current day terrestrial cosmic ray flux are well known, this is not true for spectra produced by many astrophysical events. This work shows the results of Monte Carlo simulations quantifying the neutron flux due to CRs at various primary energies and altitudes. We provide here look-up tables that can be used to determine neutron fluxes from proton primaries with kinetic energies of 1 MeV-1 PeV. By convolution, one can compute the neutron flux for any arbitrary CR spectrum. This contrasts with all other similar works, which are spectrum dependent. Our results demonstrate the difficulty in deducing the nature of primaries from the spectrum of ground level neutron enhancements.

  12. Measurement of neutron energy spectra and neutron dose rates from 7Li(p,n)7Be reaction induced on thin LiF target

    NASA Astrophysics Data System (ADS)

    Atanackovic, Jovica; Matysiak, Witold; Dubeau, Jacques; Witharana, Sampath; Waker, Anthony

    2015-02-01

    The measurements of neutron energy spectra and neutron dose rates were performed using the KN Van de Graaff accelerator, located at the McMaster University Accelerator Laboratory (MAL). Protons were accelerated on the thin lithium fluoride (LiF) target and produced mono-energetic neutrons which were measured using three different spectrometers: Bonner Sphere Spectrometer (BSS), Nested Neutron Spectrometer (NNS), and Rotational Proton Recoil Spectrometer (ROSPEC). The purpose of this work is (1) measurement and quantification of low energy accelerator neutron fields in terms of neutron fluence and dose, (2) comparison of results obtained by three different instruments, (3) comparison of measurements with Monte Carlo simulations based on theoretical neutron yields from 7Li(p,n)7Be nuclear reaction, and (4) comparison of results obtained using different neutron spectral unfolding methods. The nominal thickness of the LiF target used in the experiment was 50 μg /cm2, which corresponds to the linear thickness of 0.19 μm and results in approximately 6 keV energy loss for the proton energies used in the experiment (2.2, 2.3, 2.4 and 2.5 MeV). For each of the proton energies, neutron fluence per incident proton charge was measured and several dosimetric quantities of interest in radiation protection were derived. In addition, theoretical neutron yield calculations together with the results of Monte Carlo (MCNP) modeling of the neutron spectra are reported. Consistent neutron fluence spectra were obtained with three detectors and good agreement was observed between theoretically calculated and measured neutron fluences and derived dosimetric quantities for investigated proton energies at 2.3, 2.4 and 2.5 MeV. In the case of 2.2 MeV, some plausibly explainable discrepancies were observed.

  13. From radiation-induced chromosome damage to cell death: modelling basic mechanisms and applications to boron neutron capture therapy.

    PubMed

    Ballarini, F; Bortolussi, S; Clerici, A M; Ferrari, C; Protti, N; Altieri, S

    2011-02-01

    Cell death is a crucial endpoint in radiation-induced biological damage: on one side, cell death is a reference endpoint to characterise the action of radiation in biological targets; on the other side, any cancer therapy aims to kill tumour cells. Starting from Lea's target theory, many models have been proposed to interpret radiation-induced cell killing; after briefly discussing some of these models, in this paper, a mechanistic approach based on an experimentally observed link between chromosome aberrations and cell death was presented. More specifically, a model and a Monte Carlo code originally developed for chromosome aberrations were extended to simulate radiation-induced cell death applying an experimentally observed one-to-one relationship between the average number of 'lethal aberrations' (dicentrics, rings and deletions) per cell and -ln S, S being the fraction of surviving cells. Although such observation was related to X rays, in the present work, the approach was also applied to protons and alpha particles. A good agreement between simulation outcomes and literature data provided a model validation for different radiation types. The same approach was then successfully applied to simulate the survival of cells enriched with boron and irradiated with thermal neutrons at the Triga Mark II reactor in Pavia, to mimic a typical treatment for boron neutron capture therapy. PMID:21159746

  14. T invariance and T-odd asymmetries for the cold-polarized-neutron-induced fission of nonoriented nuclei

    SciTech Connect

    Kadmensky, S. G.; Bunakov, V. E.; Titova, L. V.

    2014-12-15

    It is shown that the coefficients D{sup exp} for all T-odd asymmetries observed experimentally in the cross sections for the reactions of cold-polarized-neutron-induced fission of nonoriented target nuclei (which involves the emission of prescission and evaporated particles) comply in shape and scale with the coefficients D{sup theor} calculated for the analogous asymmetries on the basis of quantum-mechanical nuclear-fission theory for T-invariant Hamiltonians of fissile systems. It is also shown that the asymmetries in question arise upon taking into account the effect of (i) the interference between the fission amplitudes of s- and p-wave resonances of a polarized fissile compound nucleus formed in the aforementioned reactions; (ii) the collective rotation of the compound nucleus in question (this rotation entails a change in the angular distributions of fission fragments and third particles); and (iii) the wriggling vibrations of this compound nucleus in the vicinity of its scission point, which lead to the appearance of high aligned spins of fission fragments, with the result that the emission of neutrons and photons evaporated from these fragments becomes anisotropic. The possible contribution of T-noninvariant interactions to the formation of the T-odd asymmetries under analysis is estimated by using the results obtained in experimentally testing the detailed-balance principle, (P-A) theorem, and T invariance of cross sections for elastic proton-proton and proton-neutron scattering.

  15. Influence of butylated hydroxytoluene-induced cell proliferation on mouse lung damage after x rays or fission neutrons

    SciTech Connect

    Ullrich, R.L.; Meyer, K.R.

    1982-02-01

    To examine the relative importance of endothelial cells vs type II alveolar cells in the development of lung damage, we irradiated the lungs of mice with X rays either 2 or 6 days after treatment with butylated hydroxytoluene (BHT) and determined LD/sub 50///sub 180/ values. LD/sub 50///sub 180/ was 959 rad when no BHT was given, 269 rad when 2 days elapsed after BHT treatment, and 1445 rad at 6 days after BHT. The pattern of response was similar after fission neutron irradiation to the thorax. LD/sub 50///sub 180/ after fission neutrons alone was 476 rad, but at 2 and 6 days after BHT, the LD/sub 50///sub 180/ values were 98 and 575 rad, respectively. Clearly 2 days after BHT, when radiation injury to type II cells predominated, the sensitivity to both X rays and fission neutrons increased markedly, suggesting that injury to alveolar epithelial cells may be of primary importance in the development of lung damage in the mouse. Further, since certain antineoplastic drugs may induce a proliferative response in the lung similar to that produced by BHT, these data stress the fact that the timing between chemotherapy and radiation may be critical in the treatment of some cancers to avoid serious complications.

  16. Measurement and analysis of radioactivity induced in steels and a vanadium alloy by 14-MeV neutrons

    NASA Astrophysics Data System (ADS)

    Richter, D.; Forrest, R. A.; Freiesleben, H.; Kovalchuk, Va. D.; Kovalchuk D, Vi.; Markovskij, D. V.; Seidel, K.; Tereshkin, V. I.; Unholzer, S.

    2000-12-01

    Samples of the structural material of the International Thermonuclear Experimental Reactor (SS316), of the low-activation steels MANET and F82H, and of the vanadium alloy V4Ti4Cr were irradiated with D-T fusion neutrons. The radioactivities induced were determined after irradiation several times during decay by γ-spectroscopy. The results were analysed with the European Activation System (EASY-97). In order to validate EASY-97, the total activities of the samples are compared, and ratios of calculated-to-experimental values for the individual activities are derived and discussed.

  17. Development of Mechanistic Modeling Capabilities for Local Neutronically-Coupled Flow-Induced Instabilities in Advanced Water-Cooled Reactors

    SciTech Connect

    Michael Podowski

    2009-11-30

    The major research objectives of this project included the formulation of flow and heat transfer modeling framework for the analysis of flow-induced instabilities in advanced light water nuclear reactors such as boiling water reactors. General multifield model of two-phase flow, including the necessary closure laws. Development of neurton kinetics models compatible with the proposed models of heated channel dynamics. Formulation and encoding of complete coupled neutronics/thermal-hydraulics models for the analysis of spatially-dependent local core instabilities. Computer simulations aimed at testing and validating the new models of reactor dynamics.

  18. PROTON RADIOGRAPHY FOR AN ADVANCED HYDROTEST FACILITY

    SciTech Connect

    C. MORRIS

    2000-11-01

    Analysis of data from BNL experiment 933 is presented. Results demonstrate that proton radiography can meet many of the requirements for an Advanced Hydrotest Facility (AHF). Results for background, position resolution, metrology, quantitative radiography, material identification, and edge resolution are presented.

  19. INDUSTRIAL RADIOGRAPHY STUDENT GUIDE AND LABORATORY EXERCISES.

    ERIC Educational Resources Information Center

    Bureau of Adult, Vocational, and Technical Education (DHEW/OE), Washington, DC. Div. of Vocational and Technical Education.

    THIS INSTRUCTOR'S GUIDE TO AN 80-HOUR COURSE IN INDUSTRIAL RADIOGRAPHY IS COORDINATED WITH LESSONS IN THE STUDENT GUIDE AND LABORATORY EXERCISES AND IS BASED ON MATERIAL IN THE COURSE MANUAL, INDUSTRIAL RADIOGRAPHY. THE COURSE IS INTENDED TO TRAIN HIGH SCHOOL GRADUATES AS BEGINNING RADIOGRAPHERS WHO ARE EXPECTED TO BE ABLE TO EXTEND THEIR…

  20. Protactinium neutron-induced fission up to 200 MeV

    NASA Astrophysics Data System (ADS)

    Maslov, V.

    2010-03-01

    The theoretical evaluation of 230-233Pa(n,F) cross sections is based on direct data, 230-234Pa fission probabilities and ratios of fission probabilities in first-chance and emissive fission domains, surrogate for neutroninduced fission. First chance fission cross sections trends of Pa are based on consistent description of 232Th(n,F), 232Th(n,2n) and 238U(n,F), 238U(n,xn) data, supported by the ratio surrogate data by Burke et al., 2006, for the 237U(n,F) reaction. Ratio surrogate data on fission probabilities of 232Th(6 Li,4 He)234Pa and 232 Th(6 Li,d)236U by Nayak et al., 2008, support the predicted 233Pa(n, F) cross section at En=11.5-16.5 MeV. The predicted trends of 230-232Pa(n, F) cross section up to En=20 MeV, are consistent with fissilities of Pa nuclides, extracted by 232Th(p,F) (Isaev et al., 2008) and 232Th(p,3n) (Morgenstern et al., 2008) data analysis. The excitation energy and nucleon composition dependence of the transition from asymmetric to symmetric scission for fission observables of Pa nuclei is defined by analysis of p-induced fission of 232Th at Ep=1-200 MeV. Predominantly symmetric fission in 232Th(p,F) at En( p)=200 MeV as revealed by experimental branching ratios (Dujvestijn et al., 1999) is reproduced. Steep transition from asymmetric to symmetric fission with increase of nucleon incident energy is due to fission of neutron-deficient Pa (A≤229) nuclei. A structure of the potential energy surface (a drop of f f symmetric and asymmetric fission barriers difierence (EfSYM - EfASYM) from ~3.5 MeV to ~1 MeV) of N-deficient Pa nuclides (A≤226) and available phase space at outer fission saddles, are shown to be responsible for the sharp increase with En( p) of the symmetric fission component contribution for 232Th(p,F) and 230-233 Pa(n, F) reactions. That is a strong evidence of emissive fission nature of moderately excited Pa nuclides, reliably quantified only up to En( p)~20(30) MeV. Predicted fission cross section of 232Pa(n,F) coincides

  1. Modeling of neutron induced backgrounds in x-ray framing camerasa)

    NASA Astrophysics Data System (ADS)

    Hagmann, C.; Izumi, N.; Bell, P.; Bradley, D.; Conder, A.; Eckart, M.; Khater, H.; Koch, J.; Moody, J.; Stone, G.

    2010-10-01

    Fast neutrons from inertial confinement fusion implosions pose a severe background to conventional multichannel plate (MCP)-based x-ray framing cameras for deuterium-tritium yields >1013. Nuclear reactions of neutrons in photosensitive elements (charge coupled device or film) cause some of the image noise. In addition, inelastic neutron collisions in the detector and nearby components create a large gamma pulse. The background from the resulting secondary charged particles is twofold: (1) production of light through the Cherenkov effect in optical components and by excitation of the MCP phosphor and (2) direct excitation of the photosensitive elements. We give theoretical estimates of the various contributions to the overall noise and present mitigation strategies for operating in high yield environments.

  2. Radiation cataractogenesis induced by neutron or gamma irradiation in the rat lens is reduced by vitamin E

    SciTech Connect

    Ross, W.M.; Creighton, M.O.; Trevithick, J.R. )

    1990-09-01

    Although cataract of the eye lens is a known late effect of ionizing radiation exposure, most of the experimental work to date has concentrated on single, acute high doses or multiple, fractionated, chronic exposures. Many papers have dealt with biochemical alterations in metabolism and cellular components, with microscopic and electron microscopic lesions to the epithelial and cortical layers, and with clinical cataract formation. However, the minimum cataractogenic dose for rats has for many years been considered to be about 2 Gy for a single, acute dose of low LET radiation. Our purpose in designing this pilot study was three fold: firstly, to determine whether any physical damage could be detected after low, acute exposure to neutron radiation (10 and 100 cGy); secondly, to compare the relative effectiveness of fast (14 MeV) neutrons with gamma-rays; and thirdly, to investigate the possibility that vitamin E could protect the lenses from radiation damage. The results revealed that morphological damage was already discernible within minutes after exposure to neutrons or gamma-rays, that it became greater after 24 hours, that neutrons were more damaging than gamma-rays, and that vitamin E could effectively reduce the cataractogenic damage induced by ionizing radiation. Control, non-irradiated lenses with or without vitamin E, either in vivo or in vitro, showed no damage. Also, it appeared that in vitro irradiation was more damaging to lenses than in vivo irradiation, so this culture technique may prove to be a sensitive tool for assessing early damage caused by ionizing radiation.

  3. Measurements of Neutron Induced Cross Sections at the Oak Ridge Electron Linear Accelerator

    SciTech Connect

    Guber, K.H.; Harvey, J.A.; Hill, N.W.; Koehler, P.E.; Leal, L.C.; Sayer, R.O.; Spencer, R.R.

    1999-09-20

    We have used the Oak Ridge Electron Linear Accelerator (ORELA) to measure neutron total and the fission cross sections of 233U in the energy range from 0.36 eV to ~700 keV. We report average fission and total cross sections. Also, we measured the neutron total cross sections of 27Al and Natural chlorine as well as the capture cross section of Al over an energy range from 100 eV up to about 400 keV.

  4. Neutron Induced Fission Measurements of ^242mAm at DANCE

    NASA Astrophysics Data System (ADS)

    Chyzh, A.; Wu, C. Y.; Macri, R. A.; Agvaanlusan, U.; Parker, W. E.; Wilk, P. A.; Becker, J. A.; Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Keksis, A. L.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D.; Wilhelmy, J. B.; Wouters, J. M.

    2010-11-01

    Neutron capture and fission reactions on actinieds often present challenges in measuring each of the reaction. Fission tagging detector used along with the Detector for Advanced Neutron Capture Experiments (DANCE) provides a way to measure (n,f) and (n,γ) reactions simultaneously. DANCE was used to measure ^242mAm(n,f) reaction along with a custom made fission-tagging parallel plate avalanche counter (PPAC). The results on fission related γ-ray multiplicity distribution, the ^242mAm(n,f) cross section, and the average γ-ray energy distribution are presented.

  5. Measurements of neutron emission induced by muons stopped in metal deuteride targets

    NASA Astrophysics Data System (ADS)

    Chen, M.; Steadman, S. G.; Gaudreau, M. P. J.; Luckhardt, S. C.; Parker, R. R.; Albagli, D.; Cammarata, V.; Schloh, M.; Wrighton, M. S.; Kwok, K.; Thieme, C.; Lowenstein, D. I.; Debbe, R.; Reilly, J. J.

    1990-06-01

    An 80-MeV/c negative muon beam from the Alternating Gradient Synchrotron at Brookhaven National Laboratory was used to investigate the stopping of muons inside Pd, Ti, and Y targets saturated with deuterium. Neutron emission from the targets was measured with an array of3He detectors, and in some runs, the temperature of the target was monitored as a function of time, with and without a flux of muons on the target. The neutron rates were also measured for Pd cathodes in an active electrochemical cell similar in design to those used in so-called “cold fusion” experiments, and the electrolyte solution was analyzed for excess tritium. No evidence was found for muon-catalyzed fusion at rates consistent with those claimed in “cold fusion” experiments. Neutron production from catalyzed fusion due to the presence of deuterium in palladium deuteride, PdD0.7, exposed to muons was determined to be 0.0±0.03 (stat.) ±0.25 (syst.) neutrons per stopped muon.

  6. Residual 152Eu and 60Co activities induced by neutrons from the Hiroshima atomic bomb.

    PubMed

    Shizuma, K; Iwatani, K; Hasai, H; Hoshi, M; Oka, T; Morishima, H

    1993-09-01

    Specific activities of 152Eu:Eu in stone samples exposed to the Hiroshima atomic bomb were determined for 70 samples up to a 1,500-m slant range from the epicenter. The specific activities of 60Co:Co were also determined for six samples near the Hiroshima hypocenter. First, the 152Eu data were investigated to find out the directional dependence of neutron activation. Directional anisotropy was not definite; however, there was an indication that the activation in the west-southwest was lower than in other directions. Second, measured 152Eu and 60Co radioactivity data were compared with activation calculations based on DS86 neutrons. It is clearly shown that the measured data are lower than the calculation near the hypocenter and vice versa at long distances beyond 1,000 m. The calculated-to-measured ratios of 152Eu are 1.6 at the hypocenter, 1.0 at approximately 900 m, and 0.05 at a 1,500-m slant range. Present results indicate that systematic errors exist in the DS86 neutrons concerning the source-term spectrum, neutron transport calculations in air, and/or activation measurements.

  7. Fast neutron induced structural rearrangements at a soybean NAP1 locus result in gnarled trichomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A soybean (Glycine max (L.) Merr.) gnarled trichome mutant, exhibiting stunted trichomes compared to wild-type, was identified in a fast neutron mutant population. Genetic mapping using whole genome sequence-based bulked segregant analysis identified a 26.6 megabase interval on chromosome 20 that ...

  8. Neutron-induced gamma-ray production from carbon and nitrogen

    SciTech Connect

    Nelson, R.O.; Wender, S.A.

    1994-06-01

    Gamma-ray production cross sections and angular distributions were measured with five 7.6 cm diameter {times} 7.6 cm long BGO detectors at the high-energy white neutron source of the WNR facility at Los Alamos for targets of C {sup 14}NH{sub 3} and {sup 15}NH{sub 3}. Gamma rays were measured in the energy range from 1.4 to 25 MeV. The incident neutron energies spanned the range from 2 to over 100 MeV. The detectors were positioned at angles of 39{degree}, 55{degree}, 90{degree}, 125{degree}, and 144{degree} with respect to the neutron beam. We have extracted angular distributions and cross sections for the 4.44 and 15.1 MeV {gamma} rays from inelastic excitation of C for 4 < E{sub n} < 150 MeV. In ENDF-B/VI these {gamma}-rays are treated as being isotropic. Our angular distributions show that this is not the case. For the nitrogen isotopes we have extracted angular distributions and cross sections for several {gamma} rays in the neutron energy range, 2 < E{sub n} < 20 MeV.

  9. Evidence for Neutron Star Formation from Accretion Induced Collapse of a White Dwarf

    NASA Technical Reports Server (NTRS)

    Paradijis, J. Van; VanDenHeuvel, E. P. J.; Kouveliotou, C.; Fishman, G. J.; Finger, M. H.; Lewin, W. H. G.

    1997-01-01

    The orbital parameters of the recently discovered transient burster/pulsar GRO J1744-28 indicate that this system is a low-mass X-ray binary in an advanced stage of its mass transfer, with several tenths of a solar mass already transferred from the donor to the compact star. All neutron stars known to have accreted such an amount have very weak magnetic fields, and this has led to the idea that the magnetic fields of neutron stars decay as a result of accretion. The observation of a strongly magnetized neutron star in GRO J1744-28 then suggests that this neutron star was formed recently as a result of the collapse of a white dwarf during an earlier stage of the current phase of mass transfer. It is shown that this model can consistently explain the observed characteristics of GRO J1744-28. Attractive progenitors for such an evolution are the luminous supersoft X-ray sources detected with ROSAT.

  10. Effects of x rays and fission neutrons on an induced proliferative response in lung type 2 epithelial cells

    SciTech Connect

    Meyer, K.R.; Ullrich, R.L.

    1981-02-01

    The recovery of the proliferative response induced by butylated hydroxytoluene (BHT) was evaluated in the type 2 epithelial cell population of BALB/c mouse lung after x-ray or fission neutron irradiation. Previous autoradiographic studies revealed that the proliferative changes in the lung 2 days after BHT administration were due primarily to type 2 alveolar cells. When given immediately before BHT, radiation caused a dose-dependent decrease in the BHT-induced proliferative response, measured by (/sup 14/C)thymidine incorporation into DNA and by labeling studies. When the time between irradiation and BHT injection was lengthened, the proliferative response gradually returned in a dose-dependent manner. Two types of recovery processes were investigated.

  11. Radiation damage induced in Al2O3 single crystal sequentially irradiated with reactor neutrons and 90 MeV Xe ions

    NASA Astrophysics Data System (ADS)

    Zirour, H.; Izerrouken, M.; Sari, A.

    2016-06-01

    The present investigation reports the effect of 90 MeV Xe ion irradiation on neutron irradiated Al2O3 single crystals. Three irradiation experiments were performed, with neutrons only, 90 MeV Xe ions only and with neutrons followed by 90 MeV Xe ions. Neutron and 90 MeV Xe ion irradiations were performed at NUR research reactor, Algiers, Algeria and at GANIL accelerator, Caen, France respectively. After irradiation, the radiation damage was investigated by Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), optical absorption measurements, and X-ray diffraction (XRD) techniques. Raman technique revealed that the concentration of the defects formed in Al2O3 samples subsequently irradiated with neutrons and 90 MeV Xe ions is lower than that formed in Al2O3 samples which were irradiated only with neutrons. This reveals the occurrence of ionization-induced recovery of the neutron damage. Furthermore, as revealed by XRD analysis, a new peak is appeared at about 2θ = 38.03° after irradiation at high fluence (>3 × 1013 Xe/cm2). It can be assigned to the formation of new lattice plane.

  12. Computational Study of Integrated Neutron/Photon Imaging for Illicit Material Detection

    NASA Astrophysics Data System (ADS)

    Hartman, Jessica; Barzilov, Alexander

    The feasibility of integration of photon and neutron radiography for nondestructive detection of illicit materials was examined. The MCNP5 code was used to model a radiography system consisting of accelerator-based neutron and photon sources and the imaging detector array, with an object under scrutiny placed between them. For this examination, the objects consisted of a matrix of low-Z and high-Z materials of various shapes and density. Transmission-radiography computations were carried out using 2.5-MeV deuterium-deuterium and 14-MeV deuterium-tritium neutron sources, and a 0.3-MeV photon source. The radiography tallies for both neutron and photon sources were modeled for the same geometry of the system. The photon-to- neutron transmission ratios were determined for each pixel of the detector array and utilized to identify the presence of specific materials in the radiographic images. By focusing on the inherent difference between neutron and photon interactions, it was possible to determine the shape and material composition of complex objects present within a pallet or a shipping container. The use of a single imaging array of scintillation detectors for simultaneous measurements of fast neutrons and photons is discussed, and its function in the dual neutron/photon radiography applications is addressed.

  13. The energy spectrum of cosmic-ray induced neutrons measured on an airplane over a wide range of altitude and latitude.

    PubMed

    Goldhagen, P; Clem, J M; Wilson, J W

    2004-01-01

    Crews of high-altitude aircraft are exposed to radiation from galactic cosmic rays (GCRs). To help determine such exposures, the Atmospheric Ionizing Radiation Project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on a NASA ER-2 high-altitude airplane. The primary instrument was a sensitive extended-energy multisphere neutron spectrometer. Its detector responses were calculated for energies up to 100 GeV using the radiation transport code MCNPX 2.5.d with improved nuclear models and including the effects of the airplane structure. New calculations of GCR-induced particle spectra in the atmosphere were used to correct for spectrometer counts produced by protons, pions and light nuclear ions. Neutron spectra were unfolded from the corrected measured count rates using the deconvolution code MAXED 3.1. The results for the measured cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron dose equivalent and effective dose rates, and their dependence on altitude and geomagnetic cut-off agree well with results from recent calculations of GCR-induced neutron spectra.

  14. Neutron-induced fission cross section of {sup nat}Pb and {sup 209}Bi from threshold to 1 GeV: An improved parametrization

    SciTech Connect

    Tarrio, D.; Duran, I.; Paradela, C.; Tassan-Got, L.; Audouin, L.; Berthier, B.; Ferrant, L.; Isaev, S.; Le Naour, C.; Stephan, C.; Trubert, D.; David, S.; Aerts, G.; Andriamonje, S.; Berthoumieux, E.

    2011-04-15

    Neutron-induced fission cross sections for {sup nat}Pb and {sup 209}Bi were measured with a white-spectrum neutron source at the CERN Neutron Time-of-Flight (n{sub T}OF) facility. The experiment, using neutrons from threshold up to 1 GeV, provides the first results for these nuclei above 200 MeV. The cross sections were measured relative to {sup 235}U and {sup 238}U in a dedicated fission chamber with parallel plate avalanche counter detectors. Results are compared with previous experimental data. Upgraded parametrizations of the cross sections are presented, from threshold energy up to 1 GeV. The proposed new sets of fitting parameters improve former results along the whole energy range.

  15. Analyses of cosmic ray induced-neutron based on spectrometers operated simultaneously at mid-latitude and Antarctica high-altitude stations during quiet solar activity

    NASA Astrophysics Data System (ADS)

    Hubert, G.

    2016-10-01

    In this paper are described a new neutron spectrometer which operate in the Concordia station (Antarctica, Dome C) since December 2015. This instrument complements a network including neutron spectrometers operating in the Pic-du-Midi and the Pico dos Dias. Thus, this work present an analysis of cosmic ray induced-neutron based on spectrometers operated simultaneously in the Pic-du-Midi and the Concordia stations during a quiet solar activity. The both high station platforms allow for investigating the long period dynamics to analyze the spectral variation and effects of local and seasonal changes, but also the short term dynamics during solar flare events. A first part is devoted to analyze the count rates, the spectrum and the neutron fluxes, implying cross-comparisons between data obtained in the both stations. In a second part, measurements analyses were reinforced by modeling based on simulations of atmospheric cascades according to primary spectra which only depend on the solar modulation potential.

  16. Neutron-induced fission cross section of {sup 234}U and {sup 237}Np measured at the CERN Neutron Time-of-Flight (n{sub T}OF) facility

    SciTech Connect

    Paradela, C.; Duran, I.; Tarrio, D.; Alvarez, H.; Tassan-Got, L.; Berthier, B.; Ferrant, L.; Isaev, S.; Le Naour, C.; Stephan, C.; Trubert, D.; David, S.; Abbondanno, U.; Fujii, K.; Milazzo, P. M.; Moreau, C.; Aerts, G.

    2010-09-15

    A high-resolution measurement of the neutron-induced fission cross section of {sup 234}U and {sup 237}Np has been performed at the CERN Neutron Time-of-Flight facility. The cross sections have been determined in a wide energy range from 1 eV to 1 GeV using the evaluated {sup 235}U cross section as reference. In these measurements the energy determination for the {sup 234}U resonances could be improved, whereas previous discrepancies for the {sup 237}Np resonances were confirmed. New cross-section data are provided for high neutron energies that go beyond the limits of prior evaluations, obtaining important differences in the case of {sup 237}Np.

  17. Neutron-emission measurements at a white neutron source

    SciTech Connect

    Haight, Robert C

    2010-01-01

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

  18. Activation cross sections for reactions induced by 14 MeV neutrons on natural tantalum

    SciTech Connect

    Luo Junhua; Tuo Fei; Kong Xiangzhong

    2009-05-15

    Cross sections for (n,2n), (n,p), (n,n{sup '}{alpha}), (n,t), (n,d{sup '}), and (n,{alpha}) reactions have been measured on tantalum isotopes at the neutron energies of 13.5 to 14.7 MeV using the activation technique. Data are reported for the following reactions: {sup 181}Ta(n,2n){sup 180}Ta{sup g}, {sup 181}Ta(n,p){sup 181}Hf, {sup 181}Ta(n,n{sup '}{alpha}){sup 177}Lu{sup m}, {sup 181}Ta(n,t){sup 179}Hf{sup m2}, {sup 181}Ta(n,d{sup '}){sup 180}Hf{sup m}, and {sup 181}Ta(n,{alpha}){sup 178}Lu{sup m}. The neutron fluences were determined using the monitor reaction {sup 27}Al(n,{alpha}){sup 24}Na. Results were discussed and compared with the previous works.

  19. Heat Source Neutron Emission Rate Reduction Studies - Water Induced HF Liberation

    NASA Astrophysics Data System (ADS)

    Matonic, John; Brown, John; Foltyn, Liz; Garcia, Lawrence; Hart, Ron; Herman, David; Huling, Jeff; Pansoy-Hjelvik, M. E. Lisa; Sandoval, Fritz; Spengler, Diane

    2004-02-01

    Plutonium-238 oxide (238PuO2) is used in the fabrication of general purpose heat sources (GPHS) or light-weight radioisotope heater units (LWRHUs). The heat sources supply the thermal energy used in radioisotope thermoelectric generators to power spacecraft for deep space missions and to heat critical components in the cold environs of space. Los Alamos National Laboratory has manufactured heat sources for approximately two decades. The aqueous purification of 238PuO2 is required, due to rigorous total Pu-content, actinide and non-actinide metal impurity, and neutron emission rate specifications. The 238PuO2 aqueous purification process is a new capability at Los Alamos National Laboratory as previously, aqueous purified 238PuO2 occurred at other DOE complexes. The Pu-content and actinide and non-actinide metal impurity specifications are met well within specification in the Los Alamos process, though reduction in neutron emission rates have been challenging. High neutron emission rates are typically attributed to fluoride content in the oxide. The alpha decay from 238Pu results in α,n reactions with light elements such as 17O, 18O, and 19F resulting in high neutron emission rates in the purified 238PuO2. Simple 16O-exchange takes care of the high NER due to 17O, and 18O. A new method to reduce the NER due to 19F in the purified 238PuO2 is presented in this paper. The method involves addition of water to purified 238PuO2, followed by heating to remove the water and liberating fluoride as HF.

  20. α and 2p2n emission in fast neutron-induced reactions on Ni60

    DOE PAGESBeta

    Fotiades, N.; Devlin, M.; Haight, R. C.; Nelson, R. O.; Kunieda, S.; Kawano, T.

    2015-06-19

    The cross sections for populating the residual nucleus in the reaction AZX(n,x)A-4Z-2Y exhibit peaks as a function of incident neutron energy corresponding to the (n,n'α) reaction and, at higher energy, to the (n,2p3n) reaction. In addition, the relative magnitudes of these peaks vary with the Z of the target nucleus.

  1. Coated semiconductor devices for neutron detection

    DOEpatents

    Klann, Raymond T.; McGregor, Douglas S.

    2002-01-01

    A device for detecting neutrons includes a semi-insulated bulk semiconductor substrate having opposed polished surfaces. A blocking Schottky contact comprised of a series of metals such as Ti, Pt, Au, Ge, Pd, and Ni is formed on a first polished surface of the semiconductor substrate, while a low resistivity ("ohmic") contact comprised of metals such as Au, Ge, and Ni is formed on a second, opposed polished surface of the substrate. In one embodiment, n-type low resistivity pinout contacts comprised of an Au/Ge based eutectic alloy or multi-layered Pd/Ge/Ti/Au are also formed on the opposed polished surfaces and in contact with the Schottky and ohmic contacts. Disposed on the Schottky contact is a neutron reactive film, or coating, for detecting neutrons. The coating is comprised of a hydrogen rich polymer, such as a polyolefin or paraffin; lithium or lithium fluoride; or a heavy metal fissionable material. By varying the coating thickness and electrical settings, neutrons at specific energies can be detected. The coated neutron detector is capable of performing real-time neutron radiography in high gamma fields, digital fast neutron radiography, fissile material identification, and basic neutron detection particularly in high radiation fields.

  2. Status of the Neutron Imaging and Diffraction Instrument IMAT

    NASA Astrophysics Data System (ADS)

    Kockelmann, Winfried; Burca, Genoveva; Kelleher, Joe F.; Kabra, Saurabh; Zhang, Shu-Yan; Rhodes, Nigel J.; Schooneveld, Erik M.; Sykora, Jeff; Pooley, Daniel E.; Nightingale, Jim B.; Aliotta, Francesco; Ponterio, Rosa C.; Salvato, Gabriele; Tresoldi, Dario; Vasi, Cirino; McPhate, Jason B.; Tremsin, Anton S.

    A cold neutron imaging and diffraction instrument, IMAT, is currently being constructed at the ISIS second target station. IMAT will capitalize on time-of-flight transmission and diffraction techniques available at a pulsed neutron source. Analytical techniques will include neutron radiography, neutron tomography, energy-selective neutron imaging, and spatially resolved diffraction scans for residual strain and texture determination. Commissioning of the instrument will start in 2015, with time-resolving imaging detectors and two diffraction detector prototype modules. IMAT will be operated as a user facility for material science applications and will be open for developments of time-of-flight imaging methods.

  3. LENS: A New Pulsed Neutron Source for Research and Education

    PubMed Central

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

    2005-01-01

    A new pulsed neutron source is under construction at the Indiana University Cyclotron Facility (IUCF). Neutrons are produced via (p,n) reactions by a low-energy proton beam incident on a thin beryllium target. The source is tightly coupled to a cold methane moderator held at a temperature of 20 K or below. The resulting time-averaged cold neutron flux is expected to be comparable to that of the Intense Pulsed Neutron Source (IPNS) facility at Argonne National Laboratory. The initial experimental suite will include instrumentation for small angle neutron scattering (SANS), moderator studies, radiography, and zero-field spin-echo SANS. PMID:27308113

  4. Information extraction from muon radiography data

    SciTech Connect

    Borozdin, K. N.; Asaki, T. J.; Chartrand, R.; Hengartner, N. W.; Hogan, G. E.; Morris, C. L.; Priedhorsky, W. C.; Schirato, R.C.; Schultz, L. J.; Sottile, M. J.; Vixie, K. R.; Wohlberg, B. E.; Blanpied, G.

    2004-01-01

    Scattering muon radiography was proposed recently as a technique of detection and 3-d imaging for dense high-Z objects. High-energy cosmic ray muons are deflected in matter in the process of multiple Coulomb scattering. By measuring the deflection angles we are able to reconstruct the configuration of high-Z material in the object. We discuss the methods for information extraction from muon radiography data. Tomographic methods widely used in medical images have been applied to a specific muon radiography information source. Alternative simple technique based on the counting of high-scattered muons in the voxels seems to be efficient in many simulated scenes. SVM-based classifiers and clustering algorithms may allow detection of compact high-Z object without full image reconstruction. The efficiency of muon radiography can be increased using additional informational sources, such as momentum estimation, stopping power measurement, and detection of muonic atom emission.

  5. Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation

    NASA Technical Reports Server (NTRS)

    Plaza-Rosado, Heriberto

    1991-01-01

    Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.

  6. High Intensity, Pulsed, D-D Neutron Generator

    SciTech Connect

    Williams, D. L.; Vainionpaa, J. H.; Jones, G.; Piestrup, M. A.; Gary, C. K.; Harris, J. L.; Fuller, M. J.; Cremer, J. T.; Ludewigt, Bernhard A.; Kwan, J. W.; Reijonen, J.; Leung, K.-N.; Gough, R. A.

    2008-08-01

    Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1E10 n/s. Previously, Adelphi and LBNL have demonstrated these generators' applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

  7. Inelastic neutron scattering study of light-induced dynamics of a photosynthetic membrane system

    SciTech Connect

    Furrer, A.; Stoeckli, A.

    2010-01-15

    Inelastic neutron scattering was employed to study photoeffects on the molecular dynamics of membranes of the photosynthetic bacterium Rhodopseudomonas viridis. The main photoactive parts of this biomolecular system are the chlorophyll molecules whose dynamics were found to be affected under illumination by visible light in a twofold manner. First, vibrational modes are excited at energies of 12(2) and 88(21) cm{sup -1}. Second, a partial 'freezing' of rotational modes is observed at energies of 1.2(3) and 2.9(5) cm{sup -1}. These results are attributed to a possible coupling between molecular motions and particular mechanisms in the photosynthetic process.

  8. Ultra-high-speed embossed radiography system

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Abderyim, Purkhet; Osawa, Akihiro; Enomoto, Toshiyuki; Tanaka, Etsuro; Sato, Koetsu; Izumisawa, Mitsuru; Ogawa, Akira; Sato, Shigehiro; Takayama, Kazuyoshi

    2008-11-01

    Embossed radiography is an important technique for imaging target region by decreasing absorption contrast of objects. The ultra-high-speed embossed radiography system consists of a computed radiography system, an intense flash x-ray generator, and a computer program for shifting the image pixel. In the flash x-ray generator, a high-voltage condenser of 200 nF was charged to 50 kV, and the electric charges in the condenser were discharged to the flash x-ray tube after triggering the cathode electrode. The molybdenum-target evaporation lead to the formation of weakly ionized linear plasma, and intense molybdenum K-series x-rays were produced. High-speed radiography was performed using molybdenum K-rays, and the embossed radiography was carried out utilizing single-energy subtraction after the image shifting. The minimum spatial resolution was equal to the sampling pitch of the CR system of 87.5 μm, and concavoconvex radiography such as phase-differential imaging was performed with an x-ray duration of approximately 0.5 Μs.

  9. Measurements and Monte Carlo simulations of the spectral variations of the cosmic-ray-induced neutrons at the Pic du Midi over a 2-y period.

    PubMed

    Cheminet, A; Hubert, G; Lacoste, V; Boscher, D

    2014-10-01

    In this paper, a Bonner Sphere Spectrometer extended to high energies (HERMEIS) was employed to measure continuously the cosmic-ray-induced neutron spectra over a long-term period (2 y) at mountain altitude and medium geomagnetic latitude (Pic du Midi de Bigorre in the French Pyrenees, +2885 m, 5.6 GV). The results showed 1-y sinusoidal oscillations in the integrated fluence rates. The amplitude of these oscillations depends on the neutron energetic domain. The fluence rate of thermal neutrons was 53 % higher in August than that in February. Those of epithermal neutrons with energies between 0.4 eV and 0.1 MeV and evaporation neutrons (from 0.1 to 20 MeV) were ∼25 % higher in the summer than those in the winter. Finally, the cascade neutron fluence rate (>20 MeV) remained quite the same (<10 % variation). To understand the effects of local and seasonal changes in the measurement environment, GEANT4 simulations were performed. The nature of rock and thickness of the snow cover during the winter period (given by meteorological data) were investigated. A reasonable agreement between experiments and calculations was found.

  10. Measurements and Monte Carlo simulations of the spectral variations of the cosmic-ray-induced neutrons at the Pic du Midi over a 2-y period.

    PubMed

    Cheminet, A; Hubert, G; Lacoste, V; Boscher, D

    2014-10-01

    In this paper, a Bonner Sphere Spectrometer extended to high energies (HERMEIS) was employed to measure continuously the cosmic-ray-induced neutron spectra over a long-term period (2 y) at mountain altitude and medium geomagnetic latitude (Pic du Midi de Bigorre in the French Pyrenees, +2885 m, 5.6 GV). The results showed 1-y sinusoidal oscillations in the integrated fluence rates. The amplitude of these oscillations depends on the neutron energetic domain. The fluence rate of thermal neutrons was 53 % higher in August than that in February. Those of epithermal neutrons with energies between 0.4 eV and 0.1 MeV and evaporation neutrons (from 0.1 to 20 MeV) were ∼25 % higher in the summer than those in the winter. Finally, the cascade neutron fluence rate (>20 MeV) remained quite the same (<10 % variation). To understand the effects of local and seasonal changes in the measurement environment, GEANT4 simulations were performed. The nature of rock and thickness of the snow cover during the winter period (given by meteorological data) were investigated. A reasonable agreement between experiments and calculations was found. PMID:24345464

  11. Modeled Neutron and Charged-Particle Induced Nuclear Reaction Cross Sections for Radiochemistry in the Region of Yttrium, Zirconium, Niobium, and Molybdenum

    SciTech Connect

    Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R; Mustafa, M G

    2006-06-13

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron, proton, and deuteron induced nuclear reaction cross sections for targets ranging from strontium (Z = 38) to rhodium (Z = 45).

  12. Analysis of Fragment Mass Distribution in Asymmetric Area at Fission of {sup 235}U Induced by Thermal Neutrons

    SciTech Connect

    Pikul, V.P.; Koblik, Yu.N.; Khugaev, A.V.; Yuldashev, B.S.; Jovliev, U.Yu.; Muminov, A.I.; Pavliy, K.V.; Nasirov, A.K.

    2005-02-01

    The fragment mass yields in fission of {sup 235}U induced by thermal neutrons for A=145 - 160 and E{sub K}=50 - 75 MeV were measured using a mass spectrometer. The fine structure is observed at A=153, 154 and E{sub K}=50 - 60 MeV. The obtained results were described in the framework of a model based on the dinuclear system concept. The analyzed correlation between the total kinetic energy and mass distribution of fission fragments is connected with the shell structure of the formed fragments of fission. From this correlation and the time dependence of the calculated mass distribution of the binary reaction products, one can conclude that the descent time from a saddle point to a scission point for the more deformed fragments is longer than that for fragments of more compact shape.

  13. Energy-dependent RBE of neutrons to induce micronuclei in root-tip cells of Allium cepa onion irradiated as dry dormant seeds and seedlings.

    PubMed

    Zhang, Wenyi; Fujikawa, Kazuo; Endo, Satoru; Ishikawa, Masayori; Ohtaki, Megu; Ikeda, Hideo; Hoshi, Masaharu

    2003-06-01

    The relative biological effectiveness (RBE) of various energy neutrons produced from a Schenkel-type accelerator at the Research Institute for Radiation Biology and Medicine, Hiroshima University (HIRRAC), compared with 60Co gamma-ray radiation was determined. The neutron radiations and gamma-ray radiation produced good linear changes in the frequency of micronuclei induced in the root-tip cells of Allium cepa onion irradiated as dry dormant seeds (seed assay) and seedlings (seedling assay) with varying radiation doses. Therefore the RBE for radiation-induced micronuclei can be calculated as the ratio of the slopes of the fitted linear dose response for the neutron radiations and the 60Co gamma-ray radiation. The RBE values by seed assay and seedling assay decreased to 174 +/- 7, from 216 +/- 9, and to 31.4 +/- 1.0, from 45.3 +/- 1.3 (one standard error), respectively, when neutron energies increased to 1.0 MeV, from 0.2 MeV, in the present study. Furthermore, the ratio of the micronucleus induction rates of seed assay to seedling assay by gamma-ray radiation was much lower than that by neutron radiations.

  14. Cross Section Measurements of Neutron Induced Reactions on GaAs using Monoenergetic Beams from 7.5 to 15 MeV

    NASA Astrophysics Data System (ADS)

    Raut, R.; Crowell, A. S.; Fallin, B.; Howell, C. R.; Huibregtse, C.; Kelley, J. H.; Kawano, T.; Kwan, E.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2011-09-01

    Cross section measurements for the neutron induced reactions on GaAs have been carried out at ten different neutron energies from 7.5 to 15 MeV, using the activation technique. The monoenergetic neutron beams were produced via the 2H(d,n)3He reaction, known for it's high neutron yield in the chosen energy regime. GaAs samples were activated along with the Au and Al monitor foils, for estimating the incident neutron flux. The induced activiy was measured using high resolution γ-ray spectroscopy. Five reaction channels viz., 69Ga(n, 2n) Ga, 69Ga(n,p)69mZn, 71Ga(n,p)71mZn, 75As(n, 2n)74As and 75As(n,p)75Ge, have been reported for the comprehensive cross section measurements. The results are compared with the existing literature data and the available evaluations. Statistical model calculations, based on the Hauser-Feshbach formalism, have been carried out using the TALYS and EMPIRE codes and are compared with the experimental values.

  15. Neutron-induced reactions relevant for Inertial-Cofinement Fusion Experiments

    NASA Astrophysics Data System (ADS)

    Boswell, Melissa; Merrill, Frank; Rundberg, R.; Grim, Gary; Wilde, Carl; Hayes, Anna; Fowler, Malcom; Wilhelmy, Jerry

    2012-10-01

    Measuring the fluencies of both the low- & high-energy neutrons is a powerful mechanism for studying the implosion process, and the various parameters that drive inertial confinement fusion. We have developed a number of tools to measure the spectral characteristics of the NIF neutron spectrum. Most of these methods rely on exploiting the energy dependence of (n,γ), (n,2n), (n,3n) and (n,p) reactions on a variety of materials either implicitly present in the NIF implosion or through doping the target capsule or holraum. I will be discussing both prompt activation measurements, and debris activation measurements of these materials currently under development at LANL. Focusing specifically on the development of an in-situ detector to measure short-lived activation products, as well as a low-background counting facility we are developing at the Waste Isolation Pilot Plant (WIPP) to study longer-lived activation products. Furthermore, I will also be discussing several cross section measurements that are important for the interpretation of the data collected from these activation products.

  16. Neutron transfer reactions induced by {sup 8}Li on {sup 9}Be

    SciTech Connect

    Guimaraes, V.; Lichtenthaeler, R.; Camargo, O.; Barioni, A.; Assuncao, M.; Kolata, J. J.; Amro, H.; Becchetti, F. D.; Jiang, Hao; Aguilera, E. F.; Lizcano, D.; Martines-Quiroz, E.; Garcia, H.

    2007-05-15

    Angular distributions for the elastic scattering of {sup 8}Li on {sup 9}Be and the neutron transfer reactions {sup 9}Be({sup 8}Li,{sup 7}Li){sup 10}Be and {sup 9}Be({sup 8}Li,{sup 9}Li){sup 8}Be were measured with a 27 MeV {sup 8}Li radioactive nuclear beam. Spectr- oscopic factors for {sup 8}Li (multiply-in-circle sign)n{sup 9}Li and {sup 7}Li (multiply-in-circle sign)n{sup 8}Li bound systems were obtained from the comparison between the experimental differential cross section and finite-range distorted-wave Born approximation calculations with the code FRESCO. The spectroscopic factors obtained were compared to shell model calculations and to other experimental values from (d,p) reactions. Using the present values for the spectroscopic factor, cross sections for the direct neutron-capture reactions {sup 7}Li(n,{gamma}){sup 8}Li and {sup 8}Li(n,{gamma}){sup 9}Li were calculated in the framework of a potential model.

  17. Induced radioactivity in the blood of cancer patients following Boron Neutron Capture Therapy

    PubMed Central

    Fujiwara, Keiko; Kinashi, Yuko; Takahashi, Tomoyuki; Yashima, Hiroshi; Kurihara, Kouta; Sakurai, Yoshinori; Tanaka, Hiroki; Ono, Koji; Takahashi, Sentaro

    2013-01-01

    Since 1990, Boron Neutron Capture Therapy (BNCT) has been used for over 400 cancer patients at the Kyoto University Research Reactor Institute (KURRI). After BNCT, the patients are radioactive and their 24Na and 38Cl levels can be detected via a Na-I scintillation counter. This activity is predominantly due to 24Na, which has a half-life of 14.96 h and thus remains in the body for extended time periods. Radioactive 24Na is mainly generated from 23Na in the target tissue that is exposed to the neutron beam in BNCT. The purpose of this study is to evaluate the relationship between the radioactivity of blood 24Na following BNCT and the absorbed gamma ray dose in the irradiated field. To assess blood 24Na, 1 ml of peripheral blood was collected from 30 patients immediately after the exposure, and the radioactivity of blood 24Na was determined using a germanium counter. The activity of 24Na in the blood correlated with the absorbed gamma ray doses in the irradiated field. For the same absorbed gamma ray dose in the irradiated field, the activity of blood 24Na was higher in patients with neck or lung tumors than in patients with brain or skin tumors. The reasons for these findings are not readily apparent, but the difference in the blood volume and the ratio of bone to soft tissue in the irradiated field, as well as the dose that leaked through the clinical collimator, may be responsible. PMID:23392825

  18. Welding-induced mechanical properties in austenitic stainless steels before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stoenescu, R.; Schäublin, R.; Gavillet, D.; Baluc, N.

    2007-03-01

    The effects of neutron irradiation on the mechanical properties of welded joints made of austenitic stainless steels have been investigated. The materials are welded AISI 304 and AISI 347, so-called test weld materials, irradiated with neutrons at 573 K to doses of 0.3 and 1.0 dpa. In addition, an AISI 304 from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 573 K, was investigated. The mechanical properties of heat-affected zones and base materials were analysed before and after irradiation. Tensile parameters were determined at room temperature and at 573 K, for all materials and irradiation conditions. In the test weld materials it is found that radiation hardening is lower and loss of ductility is higher in the heat-affected zone than in the base material. In the in-service material radiation hardening is about the same in heat-affected zone and base material. After irradiation, deformation takes place by stacking faults and twins, at both room temperature and high temperature, contrary to unirradiated materials, where deformation takes place by twinning at room temperature and by dislocation cells at high temperature. No defect free channels are observed.

  19. Neutron activation analysis of nuclides from stellar and man-induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Oliver, L. L.

    Neutron activation and gamma counting were used to determine the relative abundances of six stable tellurium isotopes in the acid-etched residues of the Allende meteorite. The results were correlated with the isotopic compositions of xenon and the elemental abundances of helium and neon in similarly prepared residues. Nucleosynthesis appears to be the only viable explanation or the anomalous isotopic and elemental compositions observed in these residues. Results suggest that the solar system condensed from an isotopically and chemically zoned nebula that was produced by the explosion of a supernova, concentric with the present Sun. A combination of neutron activation and mass spectrometry was used to determine the concentrations of fissiogenic iodine 129 and stable iodine 127 in rain, milk and the thyroids of man, cow and deer from Missouri. Rain and deer thyroids show the highest average values of the iodine 129/iodine 127 ratio. Milk and the thyroids of cattle and humans show successively lower values of the iodine 129/iodine 127 ratio due to dietary additives of mineral iodine and to biological averaging.

  20. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    NASA Astrophysics Data System (ADS)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-01

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 × 10-5. The upper limit for the asymmetry coefficient has been set to | D n | < 6 × 10-5 at 99% confidence level, whereas for ternary fission correlation coefficient D α = (170±20) × 10-5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation coefficient was found to be (1.57 ± 0.20) × 10-4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt γ-rays.

  1. Mobile real time radiography system

    SciTech Connect

    Vigil, J.; Taggart, D.; Betts, S.

    1997-11-01

    A 450-keV Mobile Real Time Radiography (RTR) System was delivered to Los Alamos National Laboratory (LANL) in January 1996. It was purchased to inspect containers of radioactive waste produced at (LANL). Since its delivery it has been used to radiograph more than 600 drums of radioactive waste at various LANL sites. It has the capability of inspecting waste containers of various sizes from <1-gal. buckets up to standard waste boxes (SWB, dimensions 54.5 in. x 71 in. x 37 in.). It has three independent x-ray acquisition formats. The primary system used is a 12- in. image intensifier, the second is a 36-in. linear diode array (LDA) and the last is an open system. It is fully self contained with on board generator, HVAC, and a fire suppression system. It is on a 53-ft long x 8-ft. wide x 14-ft. high trailer that can be moved over any highway requiring only an easily obtainable overweight permit because it weights {approximately}38 tons. It was built to conform to industry standards for a cabinet system which does not require an exclusion zone. The fact that this unit is mobile has allowed us to operate where the waste is stored, rather than having to move the waste to a fixed facility.

  2. Modified Bootstrap Sensitometry In Radiography

    NASA Astrophysics Data System (ADS)

    Bednarek, Daniel R.; Rudin, Stephen

    1981-04-01

    A new modified bootstrap approach to sensitometry is presented which provides H and D curves that show almost exact agreement with those obtained using conventional methods. Two bootstrap techniques are described; both involve a combination of inverse-square and stepped-wedge modulation of the radiation field and provide intensity-scale sensitometric curves as appropriate for medical radiography. H and D curves obtained with these modified techniques are compared with those obtained for screen-film combinations using inverse-square sensitometry as well as with those obtained for direct x-ray film using time-scale sensitometry. The stepped wedge of the Wisconsin X-Ray Test Cassette was used in the bootstrap approach since it provides sufficient exposure latitude to encompass the useful density range of medical x-ray film. This approach makes radiographic sensitometry quick and convenient, allowing accurate characteristic curves to be obtained for any screen-film cassette using standard diagnostic x-ray equipment.

  3. Determination of relative krypton fission product yields from 14 MeV neutron induced fission of 238U at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Edwards, E. R.; Cassata, W. S.; Velsko, C. A.; Yeamans, C. B.; Shaughnessy, D. A.

    2016-11-01

    Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of 88Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the 85mKr/88Kr ratio, which may be the result of incorrect nuclear data.

  4. Activation cross sections for reactions induced by 14 MeV neutrons on natural ruthenium

    NASA Astrophysics Data System (ADS)

    Luo, Junhua; Liu, Gang; Tuo, Fei; Kong, Xiangzhong; Liu, Rong; Jiang, Li; Lou, Benchao

    2007-11-01

    Cross sections for (n,2n), (n,p), (n,α), and (n,d*)1 reactions have been measured on ruthenium isotopes at the neutron energies of 13.5 to 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Data are reported for the following reactions: Ru104(n,2n)Ru103, Ru98(n,2n)Ru97, Ru96(n,2n)Ru95, Ru96(n,p)Tc96g, Ru96(n,p)Tc96m, Ru104(n,p)Tc104, Ru102(n,p)Tc102m, Ru104(n,α)Mo101, Ru102(n,α)Mo99, Ru96(n,α)Mo93m, and Ru96(n,d*)Tc95m. Results were discussed and compared with the previous works.

  5. Influence of different data tables on neutron induced reactions in quasi-infinite 238U and 232Th targets irradiated by protons with relativistic energy

    NASA Astrophysics Data System (ADS)

    Zhivkov, P.; Stoyanov, Ch; Tyutyunnikov, S.; Furman, W.

    2016-06-01

    The last decade saw the emergence of various theoretical analysis and developments of ADS (Accelerator Driving System). Different transport codes, nuclear models and nuclear cross sections have been used to predict and estimate the properties of ADS. The energy of the proton beam is supposed to range between 1 and 1.5 GeV, but some analyses suggest higher energy - up to 10 GeV. The recent papers examine the influence of the nuclear models on neutron induced reactions (n,f), (n,g), (n,xn), (n,el.) and (n,inel.). The experimental set-ups and the presumable ADS constructions consist of thousands of segments and details for example project Myrrha, Belgum [1]. The calculation of the above reactions depends on the neutron spectrum in each segment. There is a considerable difference in the size of these segments in ADS, which makes the estimation of the influence of the nuclear models and the cross sections on the integral number of neutron induced reactions more difficult. This article considers the influence of different cross section data tables on neutron induced reactions in 238U or 232Th targets. One nuclear model describing the high energy part of the nuclear interaction and various cross section data tagble (ENDF, ENDL, TENDL2014 and etc.) are used. All particles generated in the nuclear interaction process deposit their energy in the target volume. MCNP 6.1 transport code was used.

  6. Grazing-Incidence Neutron Optics based on Wolter Geometries

    NASA Technical Reports Server (NTRS)

    Gubarev, M. V.; Ramsey, B. D.; Mildner, D. F. R.

    2008-01-01

    The feasibility of grazing-incidence neutron imaging optics based on the Wolter geometries have been successfully demonstrated. Biological microscopy, neutron radiography, medical imaging, neutron crystallography and boron neutron capture therapy would benefit from high resolution focusing neutron optics. Two bounce optics can also be used to focus neutrons in SANS experiments. Here, the use of the optics would result in lower values of obtainable scattering angles. The high efficiency of the optics permits a decrease in the minimum scattering vector without lowering the neutron intensity on sample. In this application, a significant advantage of the reflective optics over refractive optics is that the focus is independent of wavelength, so that the technique can be applied to polychromatic beams at pulsed neutron sources.

  7. [Malignant transformation of human fibroblasts by neutrons and by gamma radiation: Relationship to mutations induced

    SciTech Connect

    1993-12-31

    A brief overview if provided of selected reports presented at the International Symposium on Molecular Mechanisms of Radiation- and Chemical Carcinogen-Induced Cell Transformation held at Mackinac Island, Michigan on September 19-23, 1993.

  8. mBAND analysis of chromosome aberrations in human epithelial cells induced by gamma-rays and secondary neutrons of low dose rate.

    PubMed

    Hada, M; Gersey, B; Saganti, P B; Wilkins, R; Cucinotta, F A; Wu, H

    2010-08-14

    Human risks from chronic exposures to both low- and high-LET radiation are of intensive research interest in recent years. In the present study, human epithelial cells were exposed in vitro to gamma-rays at a dose rate of 17 mGy/h or secondary neutrons of 25 mGy/h. The secondary neutrons have a broad energy spectrum that simulates the Earth's atmosphere at high altitude, as well as the environment inside spacecrafts like the Russian MIR station and the International Space Station (ISS). Chromosome aberrations in the exposed cells were analyzed using the multicolor banding in situ hybridization (mBAND) technique with chromosome 3 painted in 23 colored bands that allows identification of both inter- and intrachromosome exchanges including inversions. Comparison of present dose responses between gamma-rays and neutron irradiations for the fraction of cells with damaged chromosome 3 yielded a relative biological effectiveness (RBE) value of 26+/-4 for the secondary neutrons. Our results also revealed that secondary neutrons of low dose rate induced a higher fraction of intrachromosome exchanges than gamma-rays, but the fractions of inversions observed between these two radiation types were indistinguishable. Similar to the previous findings after acute radiation exposures, most of the inversions observed in the present study were accompanied by other aberrations. The fractions of complex type aberrations and of unrejoined chromosomal breakages were also found to be higher in the neutron-exposed cells than after gamma-rays. We further analyzed the location of the breaks involved in chromosome aberrations along chromosome 3, and observed hot spots after gamma-ray, but not neutron, exposures.

  9. mBAND analysis of chromosome aberrations in human epithelial cells induced by gamma-rays and secondary neutrons of low dose rate.

    PubMed

    Hada, M; Gersey, B; Saganti, P B; Wilkins, R; Cucinotta, F A; Wu, H

    2010-08-14

    Human risks from chronic exposures to both low- and high-LET radiation are of intensive research interest in recent years. In the present study, human epithelial cells were exposed in vitro to gamma-rays at a dose rate of 17 mGy/h or secondary neutrons of 25 mGy/h. The secondary neutrons have a broad energy spectrum that simulates the Earth's atmosphere at high altitude, as well as the environment inside spacecrafts like the Russian MIR station and the International Space Station (ISS). Chromosome aberrations in the exposed cells were analyzed using the multicolor banding in situ hybridization (mBAND) technique with chromosome 3 painted in 23 colored bands that allows identification of both inter- and intrachromosome exchanges including inversions. Comparison of present dose responses between gamma-rays and neutron irradiations for the fraction of cells with damaged chromosome 3 yielded a relative biological effectiveness (RBE) value of 26+/-4 for the secondary neutrons. Our results also revealed that secondary neutrons of low dose rate induced a higher fraction of intrachromosome exchanges than gamma-rays, but the fractions of inversions observed between these two radiation types were indistinguishable. Similar to the previous findings after acute radiation exposures, most of the inversions observed in the present study were accompanied by other aberrations. The fractions of complex type aberrations and of unrejoined chromosomal breakages were also found to be higher in the neutron-exposed cells than after gamma-rays. We further analyzed the location of the breaks involved in chromosome aberrations along chromosome 3, and observed hot spots after gamma-ray, but not neutron, exposures. PMID:20338263

  10. Fabrication of thin, free-standing BPSG films for metrological methods utilizing neutron-induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Trivelpiece, C. L.; Brenizer, J. S., Jr.; Pantano, C. G.

    2010-08-01

    Thin, free-standing boro-phosphosilicate glass (BPSG) films (<1.5 μm thick, 10 - 20 mm2) were fabricated (PSU NSF - NNIN Site) to serve as neutron converting media for a proposed high-resolution neutron imaging system capable of submicron sample imaging . The B and P concentration in the BPSG films was 4.5 and 3.5 w%, respectively, measured by ICP-OES. Silicon nitride (Si3N4) was deposited on both sides of the wafer to act as an etch mask and a protective layer over the BPSG. The bulk wafer stress induced by the lower expansion Si3N4 and BPSG layers was ~90 MPa (tensile). The Si substrate was removed from the photolithography-patterned areas via wet etch in KOH:DI H2O (45:55) solution at 100°C so that the exposed areas consisted of free-standing Si3N4/BPSG/Si3N4 stacked windows. The Si3N4 was removed via MERIE from the windows. NDP of the processed films showed that the boron concentration was constant and uniform throughout the exposed BPSG film. Visual observations of the free-standing windows showed long-range spatial deformation of the films in terms of "waves" caused by stress gradients, which were observed near the edges of the windows using optical birefringence. An annealing schedule was implemented to determine if the glass film deformation was caused by residual stress in the as-deposited film. Preliminary results of these experiments imply another mechanism is responsible for the deformation of the free-standing films. This work will review the processing techniques used in film fabrication and present the results of the thermal treatments of the thin, free-standing BPSG films.

  11. Hyperthermia increases gamma-ray and fission neutron-induced translocations in Drosophila

    SciTech Connect

    Mittler, S.

    1984-01-01

    Hyperthermia has been reported in Drosophila melanogaster to increase radiation-induced chromosome rearrangements, chromosome loss, recessive and dominant lethals. To determine whether hyperthermia would also affect high linear energy transfer (LET)-induced genetic damage such as translocations, which involve breakage and reunion of chromosomes, a genetic system was employed not only allowing detection of ordinary 2;3 translocations, but also permitting a more accurate measure of Y-autosome translocations.

  12. Irradiation effects in 6H-SiC induced by neutron and heavy ions: Raman spectroscopy and high-resolution XRD analysis

    NASA Astrophysics Data System (ADS)

    Chen, Xiaofei; Zhou, Wei; Feng, Qijie; Zheng, Jian; Liu, Xiankun; Tang, Bin; Li, Jiangbo; Xue, Jianming; Peng, Shuming

    2016-09-01

    Irradiation effects of neutron and 3 MeV C+, Si+ in 6H-SiC were investigated by Raman spectroscopy and high-resolution XRD. The total disorder values of neutron irradiated SiC agree well with that of samples irradiated by ions at the same doses respectively. On the other hand, high-resolution XRD results shows that the lattice strain rate caused by neutron irradiation is 6.8%/dpa, while it is only 2.6%/dpa and 4.2%/dpa for Si+ and C+ irradiations respectively. Our results illustrate that the total disorder in neutron irradiated SiC can be accurately simulated by MeV Si+ or C+ irradiations at the same dose, but for the lattice strain and strain-related properties like surface hardness, the depth profile of irradiation damages induced by energetic ions must be considered. This research will contribute to a better understanding of the difference in irradiation effects between neutron and heavy ions.

  13. Neutron and light-charged-particle productions in proton-induced reactions on 208Pb at 62.9 MeV

    NASA Astrophysics Data System (ADS)

    Guertin, A.; Marie, N.; Auduc, S.; Blideanu, V.; Delbar, Th.; Eudes, P.; Foucher, Y.; Haddad, F.; Kirchner, T.; Le Brun, Ch.; Lebrun, C.; Lecolley, F. R.; Lecolley, J. F.; Ledoux, X.; Lefèbvres, F.; Lefort, T.; Louvel, M.; Ninane, A.; Patin, Y.; Pras, Ph.; Rivière, G.; Varignon, C.

    2005-01-01

    Neutrons and light charged particles produced in 62.9MeV proton-induced reactions on 208Pb were measured during a single experiment performed at the CYCLONE facility in Louvain-la-Neuve (Belgium). Two independent experimental set-ups were used to extract double differential cross-sections for neutrons, protons, deuterons, tritons, 3He and alpha-particles. Charged particles were detected using a set of Si- Si- CsI telescopes from 25° to 155°, by step of 10 degrees. Neutrons were measured using shielded DeMoN counters, liquid NE213 scintillators, at 24°, 35°, 55°, 80° and 120°. These data allowed the determination of angle differential, energy differential and total production cross-sections. A comparison with theoretical calculations (MCNPX, FLUKA and TALYS) has been performed. It shows that the neutron and proton production rates are well predicted by MCNPX, using the INCL4 option. All the other codes underestimate the neutron production whereas they overestimate the proton one. For composite particles, which represent 17% of the charged particle total reaction cross-section, neither the shape nor the amplitude of the cross-sections are correctly predicted by the models.

  14. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    SciTech Connect

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-15

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -5}. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt {gamma}-rays.

  15. Neutron production in several americium compounds

    SciTech Connect

    Shores, E. F.

    2004-01-01

    Americium, like other alpha emitting actinides, may indirectly produce neutrons when combined with light target materials. These (alpha,n) reaction neutrons, along with well known photon lines, have been an advantage of the {sup 241}Am isotope for diverse applications such as radiography, thickness gauges, neutron sources, and even common household smoke detectors. To characterize these sources, the SOURCES code was used to calculate neutron yields and spectra from {sup 241}Am metal, americium oxide, and americium aluminum alloys. Such information may be used as source terms for future transport problems (e.g. shielding calculations). Table 1 contains neutron yields for six americium configurations. The metal, oxides, and alloys were run as homogeneous problems while the interface case was run in both two- and three-region interface modes.

  16. Triggering Mechanism for Neutron Induced Single-Event Burnout in Power Devices

    NASA Astrophysics Data System (ADS)

    Shoji, Tomoyuki; Nishida, Shuichi; Hamada, Kimimori

    2013-04-01

    Cosmic ray neutrons can trigger catastrophic failures in power devices. It has been reported that parasitic transistor action causes single-event burnout (SEB) in power metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). However, power diodes do not have an inherent parasitic transistor. In this paper, we describe the mechanism triggering SEB in power diodes for the first time using transient device simulation. Initially, generated electron-hole pairs created by incident recoil ions generate transient current, which increases the electron density in the vicinity of the n-/n+ boundary. The space charge effect of the carriers leads to an increase in the strength of the electric field at the n-/n+ boundary. Finally, the onset of impact ionization at the n-/n+ boundary can trigger SEB. Furthermore, this failure is closely related to diode secondary breakdown. It was clarified that the impact ionization at the n-/n+ boundary is a key point of the mechanism triggering SEB in power devices.

  17. Measurement of Neutron-Induced, Angular-Momentum-Dependent Fission Probabilities Direct Reactions

    NASA Astrophysics Data System (ADS)

    Koglin, Johnathon; Jovanovic, Igor; Burke, Jason; Casperson, Robert

    2015-04-01

    The surrogate method has previously been used to successfully measure (n , f) cross sections of a variety of difficult to produce actinide isotopes. These measurements are inaccurate at excitation energies below 1.5 MeV where the distribution of angular momentum states populated in the compound nucleus created by neutron absorption significantly differs from that arising from direct reactions. A method to measure the fission probability of individual angular momentum states arising from 239 Pu(d , pf) and 239 Pu(α ,α' f) reactions has been developed. This method consists on charged particle detectors with 40 keV FWHM resolution at 13 angles up and downstream of the beam. An array of photovoltaic (solar) cells is used to measure the angular distribution of fission fragments with high angular resolution. This distribution uniquely identifies the populated angular momentum states. These are fit to expected distributions to determine the contribution of each state. The charged particle and fission matrix obtained from these measurements determines fission probabilities of specific angular momentum states in the transition nucleus. Development of this scheme and first results will be discussed. This material is based upon work supported by the U.S. Department of Homeland Security under Grant Award Number 2012-DN-130-NF0001.

  18. Exploring Strain Induced Magnetization Effects in Metamagnetic Artificial Multiferroics using Polarized Neutron Reflectometry

    NASA Astrophysics Data System (ADS)

    Bennett, Steven; Herklotz, Andreas; Wong, Anthony; Ward, Thomas; Lauter, Valeria

    There is currently a strong drive to realize a controllable magnetic ordering transition for use in next generation spintronic based memory and computation devices. One proposed method to gain such control is the use of a changing strain in a thin film metamagnetic artificial multiferroic system. While basic concepts using electric field actuated piezoelectric strain have been recently demonstrated1, there is very little understanding of the details of strains effect on such magnetic phase transitions. Using the depth sensitive method of polarized neutron reflectometry we have been able to probe the fine details of strains contribution to the metamagnetic transition in thin films of metamagnetic FeRh2. Here we explore the effects of changing lattice strain as a function of depth using both a barium titanate substrate's structural phase transitions3 and He ion implantation. These studies have discovered a remarkably large coupling between the systems strain state and the switching behavior across the magnetostructural metamagnetic transition. 1 Cherifi, R. O. et al. Nat. Mater. 31, 345-351 (2014), 2 Bennett, S. P. et al. Sci. Rep. 5, 9142 (2015), 3 Bennett, S. P. et al. submitted (2015)

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

    SciTech Connect

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

    2011-07-01

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

  20. X-ray and neutron interrogation of air cargo for mobile applications

    NASA Astrophysics Data System (ADS)

    Van Liew, Seth

    2015-06-01

    A system for scanning break-bulk cargo for mobile applications is presented. This combines a 140 kV multi-view, multi-energy X-ray system with 2.5 MeV neutrons. The system uses dual energy X-ray radiography with neutron radiography. The X-ray and neutron systems were designed to be collocated in a mobile environment. Various materials were interrogated with the intent of distinguishing threat materials such as explosives from similar benign materials. In particular, the identification of threats and bengins with nearly identical effective atomic numbers has been demonstrated.

  1. Thyroid dose distribution in dental radiography

    SciTech Connect

    Bristow, R.G.; Wood, R.E.; Clark, G.M. )

    1989-10-01

    The anatomic position and proven radiosensitivity of the thyroid gland make it an organ of concern in dental radiography. A calibrated thermoluminescent dosimetry system was used to investigate the absorbed dose (microGy) to the thyroid gland resultant from a minimum irradiated volume, intraoral full-mouth radiography technique with the use of rectangular collimation with a lead-backed image receptor, and conventional panoramic radiography performed with front and rear lead aprons. Use of the minimum irradiated volume technique resulted in a significantly decreased absorbed dose over the entire thyroid region ranging from 100% to 350% (p less than 0.05). Because this intraoral technique results in radiographs with greater image quality and also exposes the thyroid gland to less radiation than the panoramic, this technique may be an alternative to the panoramic procedure.

  2. Cross-section measurements of neutron-induced reactions on GaAs using monoenergetic beams from 7.5 to 15 MeV

    NASA Astrophysics Data System (ADS)

    Raut, R.; Crowell, A. S.; Fallin, B.; Howell, C. R.; Huibregtse, C.; Kelley, J. H.; Kawano, T.; Kwan, E.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2011-04-01

    Cross-section measurements for neutron-induced reactions on GaAs have been carried out at twelve different neutron energies from 7.5 to 15 MeV using the activation technique. The monoenergetic neutron beams were produced via the H2(d,n)He3 reaction. GaAs samples were activated along with Au and Al monitor foils to determine the incident neutron flux. The activities induced by the reaction products were measured using high-resolution γ-ray spectroscopy. Cross sections for five reaction channels, viz., Ga69(n,2n)Ga68, Ga69(n,p)Zn69m, Ga71(n,p)Zn71m, As75(n,2n)As74, and As75(n,p)Ge75, are reported. The results are compared with the previous measurements and available data evaluations. Statistical-model calculations, based on the Hauser-Feshbach formalism, have been carried out using the TALYS and the COH3 codes and are compared with the experimental results.

  3. Simultaneous and integrated neutron-based techniques for material analysis of a metallic ancient flute

    NASA Astrophysics Data System (ADS)

    Festa, G.; Pietropaolo, A.; Grazzi, F.; Sutton, L. F.; Scherillo, A.; Bognetti, L.; Bini, A.; Barzagli, E.; Schooneveld, E.; Andreani, C.

    2013-09-01

    A metallic 19th century flute was studied by means of integrated and simultaneous neutron-based techniques: neutron diffraction, neutron radiative capture analysis and neutron radiography. This experiment follows benchmark measurements devoted to assessing the effectiveness of a multitask beamline concept for neutron-based investigation on materials. The aim of this study is to show the potential application of the approach using multiple and integrated neutron-based techniques for musical instruments. Such samples, in the broad scenario of cultural heritage, represent an exciting research field. They may represent an interesting link between different disciplines such as nuclear physics, metallurgy and acoustics.

  4. Probing the Potential of Neutron Imaging for Biomedical and Biological Applications

    NASA Astrophysics Data System (ADS)

    Watkin, K. L.; Bilheux, H. Z.; Ankner, J. F.

    Neutron imaging of biological specimens began soon after the discovery of the neutron by Chadwick in 1932. The first samples included tumors in tissues, internal organs in rats, and bones. These studies mainly employed thermal neutrons and were often compared with X-ray images of the same or equivalent samples. Although neutron scattering is widely used in biological studies, neutron imaging has yet to be exploited to its full capability in this area. This chapter summarizes past and current research efforts to apply neutron radiography to the study of biological specimens, in the expectation that clinical and medical research, as well as forensic science, may benefit from it.

  5. Probing the potential of neutron imaging for biomedical and biological applications

    SciTech Connect

    Watkin, Kenneth L; Bilheux, Hassina Z; Ankner, John Francis

    2009-01-01

    Neutron imaging of biological specimens began soon after the discovery of the neutron by Chadwick in 1932. The first samples included tumors in tissues, internal organs in rats, and bones. These studies mainly employed thermal neutrons and were often compared with X-ray images of the same or equivalent samples. Although neutron scattering is widely used in biological studies, neutron imaging has yet to be exploited to its full capability in this area. This chapter summarizes past and current research efforts to apply neutron radiography to the study of biological specimens, in the expectation that clinical and medical research, as well as forensic science, may benefit from it.

  6. Proton Radiography: Its uses and Resolution Scaling

    SciTech Connect

    Mariam, Fesseha G.

    2012-08-09

    Los Alamos National Laboratory has used high energy protons as a probe in flash radiography for over a decade. In this time the proton radiography project has used 800 MeV protons, provided by the LANSCE accelerator facility at LANL, to diagnose over five-hundred dynamic experiments in support of stockpile stewardship programs as well as basic materials science. Through this effort significant experience has been gained in using charged particles as direct radiographic probes to diagnose transient systems. The results of this experience will be discussed through the presentation of data from experiments recently performed at the LANL pRad.

  7. Searches for T-odd correlations in the emission of prompt neutrons in the polarized-neutron-induced fission of 235U nuclei

    NASA Astrophysics Data System (ADS)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2010-07-01

    The results of an experiment aimed at searches for formally T-odd correlations in the angular distribution of prompt neutrons from the fission of 235U nuclei are presented. The experiment was performed in the MEPHISTO polarized cold-neutron beam from the Munich FRMII reactor. The correlation coefficient proved to be (-3.5 ± 3.4) × 10-5 for a three-vector correlation (TRI effect) and (-5.0 ± 3.4) × 10-5 for a five-vector correlation (ROT effect). This means that no significant effects were discovered within the measurement errors. A comparison with the analogous effects in the ternary fission of 235U nuclei was performed. The values of the corresponding correlations in the angular distribution of prompt fission gamma rays were refined.

  8. Compact neutron generator developement and applications

    SciTech Connect

    Leung, Ka-Ngo; Reijonen, Jani; Gicquel, Frederic; Hahto, Sami; Lou, Tak-Pui

    2004-01-18

    The Plasma and Ion Source Technology Group at the Lawrence Berkeley National Laboratory has been engaging in the development of high yield compact neutron generators for the last ten years. Because neutrons in these generators are formed by using either D-D, T-T or D-T fusion reaction, one can produce either mono-energetic (2.4 MeV or 14 MeV) or white neutrons. All the neutron generators being developed by our group utilize 13.5 MHz RF induction discharge to produce a pure deuterium or a mixture of deuterium-tritium plasma. As a result, ion beams with high current density and almost pure atomic ions can be extracted from the plasma source. The ion beams are accelerated to {approx}100 keV and neutrons are produced when the beams impinge on a titanium target. Neutron generators with different configurations and sizes have been designed and tested at LBNL. Their applications include neutron activation analysis, oil-well logging, boron neutron capture therapy, brachytherapy, cargo and luggage screening. A novel small point neutron source has recently been developed for radiography application. The source size can be 2 mm or less, making it possible to examine objects with sharper images. The performance of these neutron generators will be described in this paper.

  9. The need for precise and well-documented experimental data on prompt fission neutron spectra from neutron-induced fission of 239Pu

    DOE PAGESBeta

    Neudecker, Denise; Taddeucci, Terry Nicholas; Haight, Robert Cameron; Lee, Hye Young; White, Morgan Curtis; Rising, Michael Evans

    2016-01-06

    The spectrum of neutrons emitted promptly after 239Pu(n,f)—a so-called prompt fission neutron spectrum (PFNS)—is a quantity of high interest, for instance, for reactor physics and global security. However, there are only few experimental data sets available that are suitable for evaluations. In addition, some of those data sets differ by more than their 1-σ uncertainty boundaries. We present the results of MCNP studies indicating that these differences are partly caused by underestimated multiple scattering contributions, over-corrected background, and inconsistent deconvolution methods. A detailed uncertainty quantification for suitable experimental data was undertaken including these effects, and test-evaluations were performed with themore » improved uncertainty information. The test-evaluations illustrate that the inadequately estimated effects and detailed uncertainty quantification have an impact on the evaluated PFNS and associated uncertainties as well as the neutron multiplicity of selected critical assemblies. A summary of data and documentation needs to improve the quality of the experimental database is provided based on the results of simulations and test-evaluations. Furthermore, given the possibly substantial distortion of the PFNS by multiple scattering and background effects, special care should be taken to reduce these effects in future measurements, e.g., by measuring the 239Pu PFNS as a ratio to either the 235U or 252Cf PFNS.« less

  10. Neutron Imaging Developments at LANSCE

    NASA Astrophysics Data System (ADS)

    Nelson, Ron; Hunter, James; Schirato, Richard; Vogel, Sven; Swift, Alicia; Ickes, Tim; Ward, Bill; Losko, Adrian; Tremsin, Anton

    2015-10-01

    Neutron imaging is complementary to x-ray imaging because of its sensitivity to light elements and greater penetration of high-Z materials. Energy-resolved neutron imaging can provide contrast enhancements for elements and isotopes due to the variations with energy in scattering cross sections due to nuclear resonances. These cross section differences exist due to compound nuclear resonances that are characteristic of each element and isotope, as well as broader resonances at higher energies. In addition, multi-probe imaging, such as combined photon and neutron imaging, is a powerful tool for discerning properties and features in materials that cannot be observed with a single probe. Recently, we have demonstrated neutron imaging, both radiography and computed tomography, using the moderated (Lujan Center) and high-energy (WNR facility) neutron sources at LANSCE. Flat panel x-ray detectors with suitable scintillator-converter screens provide good sensitivity for both low and high neutron energies. Micro-Channel-Plate detectors and iCCD scintillator camera systems that provide the fast time gating needed for energy-resolved imaging have been demonstrated as well. Examples of recent work will be shown including fluid flow in plants and imaging through dense thick objects. This work is funded by the US Department of Energy, National Nuclear Security Administration, and performed by Los Alamos National Security LLC under Contract DE-AC52-06NA25396.

  11. Fatigue behavior of Type 316 stainless steel following neutron irradiation inducing helium

    SciTech Connect

    Grossbeck, M.L.; Liu, K.C.

    1980-01-01

    Since a tokamak reactor operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially in the first wall and blanket. There has been limited work on fatigue in irradiated alloys but none on irradiated materials containing significant amounts of irradiation-induced helium. To provide scoping data and to study the effects of irradiation on fatigue behavior, 20%-cold-worked type 316 stainless steel from the MFE reference heat was studied.

  12. A new calculation method adapted to the experimental conditions for determining samples γ-activities induced by 14 MeV neutrons

    NASA Astrophysics Data System (ADS)

    Rzama, A.; Erramli, H.; Misdaq, M. A.

    1994-09-01

    Induced gamma-activities of different disk shaped irradiated samples and standards with 14 MeV neutrons have been determined by using a Monte Carlo calculation method adapted to the experimental conditions. The self-absorption of the multienergetic emitted gamma rays has been taken into account in the final samples activities. The influence of the different activation parameters has been studied. Na, K, Cl and P contents in biological (red beet) samples have been determined.

  13. Measurement of the energy spectrum of cosmic-ray induced neutrons aboard an ER-2 high-altitude airplane.

    PubMed

    Goldhagen, P; Reginatto, M; Kniss, T; Wilson, J W; Singleterry, R C; Jones, I W; Van Steveninck, W

    2002-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial aircraft flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the atmospheric ionizing radiation (AIR) project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on five flights of a NASA ER-2 high-altitude aircraft. The primary AIR instrument was a highly sensitive extended-energy multisphere neutron spectrometer with lead and steel shells placed within the moderators of two of its 14 detectors to enhance response at high energies. Detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using MCNPX. Neutron spectra were unfolded from the measured count rates using the new MAXED code. We have measured the cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron effective dose and dose equivalent rates and their dependence on altitude and geomagnetic cutoff. The measured cosmic-ray neutron spectra have almost no thermal neutrons, a large "evaporation" peak near 1 MeV and a second broad peak near 100 MeV which contributes about 69% of the neutron effective dose. At high altitude, geomagnetic latitude has very little effect on the shape of the spectrum, but it is the dominant variable affecting neutron fluence rate, which was eight times higher at the northernmost measurement location than it was at the southernmost. The shape of the spectrum varied only slightly with altitude from 21 km down to 12 km (56-201 g cm-2 atmospheric depth), but was significantly different on the ground. In all cases, ambient dose equivalent was greater than effective dose for cosmic-ray neutrons.

  14. Resorption kinetics of four hydroxyapatite-based ceramics by particle induced X-ray emission and neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Jallot, E.; Irigaray, J. L.; Oudadesse, H.; Brun, V.; Weber, G.; Frayssinet, P.

    1999-05-01

    From the viewpoint of hard tissue response to implant materials, calcium phosphates are probably the most compatible materials presently known. During the last few years, much attention has been paid to hydroxyapatite and β-tricalcium phosphate as potential biomaterials for bone substitute. A good implantation of biomaterials in the skeleton is to reach full integration of non-living implant with living bone. The aim of this study is to compare the resorption kinetics of four kinds of calcium phosphate ceramics: hydroxyapatite (Ca{10}(PO4)6(OH)2), hydroxyapatite doped with manganese or zinc and a composite material of 75% hydroxyapatite and 25% β-tricalcium phosphate (Ca3(PO4)2). Cylinders (5 6 mm in diameter) of these ceramics were packed into holes made in the femur diaphysis of mature ovine. At 2, 4, 8, 12, 16, 20, 28, 36 and 48 weeks after the operation, bone/implant interface was embedded in polymethylmethacrylate. We used the PIXE method (particle induced X-ray emission) to measure the distribution of mineral elements (Ca, P, Sr, Zn, Mn and Fe) at the bone/implant interface. At 4, 8, 16, 28 and 48 weeks after implantation we studied a biopsy of the ceramics by neutron activation method. Then, we have a global measurement of mineral elements in the biomaterial. The results showed that the resorption kinetics of hydroxyapatite doped with zinc was faster than that of the three other bioceramics.

  15. Determination of (187)Os in molybdenite by ICP-MS with neutron-induced (186)Os and (188)Os spikes.

    PubMed

    Qu, W; Du, A; Zhao, D

    2001-10-31

    The article describes a method for the determination of (187)Os in molybdenite by isotope dilution inductively coupled plasma-mass spectrometry (ID-ICP-MS) with neutron-induced (186)Os and (188)Os spike. The spike used in the present work was prepared in line with the principle by which artificial nuclides are produced in a nuclear reaction. The concentration and isotopic composition of osmium in the prepared spike were evaluated accurately with the isotope dilution method, using negative thermal ion mass spectrometry (N-TIMS). The advantage of this method is that using (186)Os and (188)Os double spikes can effectively compensate for the mass discrimination effects of ICP-MS. Thus, the common correction practice for mass bias in the isotope dilution method with a single spike is unnecessary. In addition, the method enables one to reduce the determined error arising from instrumental instability. The precision for the (187)Os/((186)Os+(188)Os) ratio was approximately 2% (2sigma, RSD), but in the case of (187)Os/(186)Os, (187)Os/(188)Os and (186)Os/(188)Os, precision ranged from 2.0 to 8% (2sigma, RSD). The results for (187)Os concentration in a molybdenite sample determined with this method showed good agreement with reference values.

  16. ON THE INDUCED GRAVITATIONAL COLLAPSE OF A NEUTRON STAR TO A BLACK HOLE BY A TYPE Ib/c SUPERNOVA

    SciTech Connect

    Rueda, Jorge A.; Ruffini, Remo E-mail: ruffini@icra.it

    2012-10-10

    It is understood that the supernovae (SNe) associated with gamma-ray bursts (GRBs) are of Type Ib/c. The temporal coincidence of the GRB and the SN continues to represent a major enigma of Relativistic Astrophysics. We elaborate here, from the earlier paradigm, that the concept of induced gravitational collapse is essential to explain the GRB-SN connection. The specific case of a close (orbital period <1 hr) binary system composed of an evolved star with a neutron star (NS) companion is considered. We evaluate the accretion rate onto the NS of the material expelled from the explosion of the core progenitor as a Type Ib/c SN and give the explicit expression of the accreted mass as a function of the nature of the components and binary parameters. We show that the NS can reach, in a few seconds, critical mass and consequently gravitationally collapse to a black hole. This gravitational collapse process leads to the emission of the GRB.

  17. Time-resolved neutron imaging at ANTARES cold neutron beamline

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Dangendorf, V.; Tittelmeier, K.; Schillinger, B.; Schulz, M.; Lerche, M.; Feller, W. B.

    2015-07-01

    In non-destructive evaluation with X-rays light elements embedded in dense, heavy (or high-Z) matrices show little contrast and their structural details can hardly be revealed. Neutron radiography, on the other hand, provides a solution for those cases, in particular for hydrogenous materials, owing to the large neutron scattering cross section of hydrogen and uncorrelated dependency of neutron cross section on the atomic number. The majority of neutron imaging experiments at the present time is conducted with static objects mainly due to the limited flux intensity of neutron beamline facilities and sometimes due to the limitations of the detectors. However, some applications require the studies of dynamic phenomena and can now be conducted at several high intensity beamlines such as the recently rebuilt ANTARES beam line at the FRM-II reactor. In this paper we demonstrate the capabilities of time resolved imaging for repetitive processes, where different phases of the process can be imaged simultaneously and integrated over multiple cycles. A fast MCP/Timepix neutron counting detector was used to image the water distribution within a model steam engine operating at 10 Hz frequency. Within <10 minutes integration the amount of water was measured as a function of cycle time with a sub-mm spatial resolution, thereby demonstrating the capabilities of time-resolved neutron radiography for the future applications. The neutron spectrum of the ANTARES beamline as well as transmission spectra of a Fe sample were also measured with the Time Of Flight (TOF) technique in combination with a high resolution beam chopper. The energy resolution of our setup was found to be ~ 0.8% at 5 meV and ~ 1.7% at 25 meV. The background level (most likely gammas and epithermal/fast neutrons) of the ANTARES beamline was also measured in our experiments and found to be on the scale of 3% when no filters are installed in the beam. Online supplementary data available from stacks.iop.org/jinst/10

  18. Safety Testing of Industrial Radiography Devices

    SciTech Connect

    Trapp, D.J.

    1999-09-29

    The Nuclear Regulatory Commission contracted the Savannah River Technology Center to verify the relevancy of the 10 CFR Part 34 requirements for the normal use of portable gamma radiography systems and to propose recommendations for changes or modifications to the requirements.

  19. INDUSTRIAL RADIOGRAPHY COURSE, INSTRUCTORS' GUIDE. VOLUME 2.

    ERIC Educational Resources Information Center

    Texas A and M Univ., College Station. Engineering Extension Service.

    INFORMATION RELATIVE TO THE LESSON PLANS IN "INDUSTRIAL RADIOGRAPHY COURSE, INSTRUCTOR'S GUIDE, VOLUME I" (VT 003 565) IS PRESENTED ON 52 INFORMATION SHEETS INCLUDING THE SUBJECTS SHIELDING EQUATIONS AND LOGARITHMS, METAL PROPERTIES, FIELD TRIP INSTRUCTIONS FOR STUDENTS, WELDING SYMBOLS AND SIZES, SAMPLE REPORT FORMS, AND TYPICAL SHIPPING…

  20. A re-sequencing based assessment of genomic heterogeneity and fast neutron-induced deletions in a common bean cultivar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A small fast neutron mutant population has been established from Phaseolus vulgaris cv. Red Hawk. We leveraged the available P. vulgaris genome sequence and high throughput next generation DNA sequencing to examine the genomic structure of five Phaseolus vulgaris cv. Red Hawk fast neutron mutants wi...