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Sample records for fast neutron spectroscopy

  1. Explosives detection via fast neutron transmission spectroscopy

    International Nuclear Information System (INIS)

    Overley, J.C.; Chmelik, M.S.; Rasmussen, R.J.; Schofield, R.M.S.; Sieger, G.E.; Lefevre, H.W.

    2006-01-01

    A review of a five-year project on detection of explosives in luggage is presented. Experimental methods are described. Explosive detection algorithms based on elemental distributions in a 5-dimensional space are also described. Single-blind tests of the method suggest that a false-alarm rate of 4% and a detection rate of 93% are possible. Improvements in the method are suggested. Measurements of neutron total cross sections for chlorine are presented

  2. Illicit substance detection using fast-neutron transmission spectroscopy

    International Nuclear Information System (INIS)

    Micklich, B.J.; Harper, M.K.; Novick, A.H.; Smith, D.L.

    1994-01-01

    Fast-neutron interrogation techniques are of interest for detecting illicit substances such as explosives and drugs because of their ability to identify light elements such as carbon, nitrogen, and oxygen. Fast-Neutron Transmission Spectroscopy (FNTS) uses standard time-of-flight techniques to measure the energy spectrum of neutrons emitted from a collimated continuum source before and after transmission through the interrogated sample. The Monte Carlo transport code MCNP is used to model fast-neutron transmission experiments using a 9 Be(d, n) source (E d =5 MeV). The areal densities (number of atoms per cm 2 ), and the uncertainties, of various elements present in the sample are determined by an unfolding algorithm which includes the effects of cross-section errors and correlations. Results are displayed in the form of normalized densities, including their errors and correlations, which are then compared to the values for explosives and benign substances. Probabilistic interpretations of the results are discussed in terms of substance detection and identification. ((orig.))

  3. Illicit substance detection using Fast-Neutron Transmission Spectroscopy

    International Nuclear Information System (INIS)

    Micklich, B.J.; Harper, M.K.; Novick, A.H.; Smith, D.L.

    1994-01-01

    Fast-neutron interrogation techniques are of interest for detecting illicit substances such as explosives and drugs because of their ability to identify light elements such as carbon, nitrogen, and oxygen. Fast-Neutron Transmission Spectroscopy (FNTS) uses standard time-of-flight techniques to measure the energy spectrum of neutrons emitted from a collimated continuum source before and after transmission through the interrogated sample. The Monte Carlo transport code MCNP is used to model fast-neutron transmission experiments using a 9 Be(d,n) source [E d = 5 MeV]. The areal densities (number of atoms per cm 2 ), and the uncertainties, of various elements present in the sample are determined by an unfolding algorithm which includes the effects of cross-section errors and correlations. Results are displayed in the form of normalized densities, including their errors and correlations, which are then compared to the values for explosives and benign substances. Probabilistic interpretations of the results are discussed in terms of substance detection and identification

  4. Fast neutron spectroscopy with tensioned metastable fluid detectors

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, T.F.; Taleyarkhan, R.P., E-mail: rusi@purdue.edu

    2016-09-11

    This paper describes research into development of a rapid-turnaround, neutron-spectroscopy capable (gamma-beta blind), high intrinsic efficiency sensor system utilizing the tensioned metastable fluid detector (TMFD) architecture. The inability of prevailing theoretical models (developed successfully for the classical bubble chamber) to adequately predict detection thresholds for tensioned metastable fluid conditions is described. Techniques are presented to overcome these inherent shortcomings, leading thereafter, to allow successful neutron spectroscopy using TMFDs – via the newly developed Single Atom Spectroscopy (SAS) approach. SAS also allows for a unique means for rapidly determining neutron energy thresholds with TMFDs. This is accomplished by simplifying the problem of determining Cavitation Detection Events (CDEs) arising from neutron interactions with one in which several recoiling atom species contribute to CDEs, to one in which only one dominant recoil atom need be considered. The chosen fluid is Heptane (C{sub 7}H{sub 16}) for which only recoiling C atoms contribute to CDEs. Using the SAS approach, the threshold curve for Heptane was derived using isotope neutron source data, and then validated against experiments with mono-energetic (2.45/14 MeV) neutrons from D-D and D-T accelerators. Thereafter the threshold curves were used to produce the response matrix for various geometries. The response matrices were in turn combined with experimental data to recover the continuous spectra of fission (Cf-252) and (α,n) Pu–Be isotopic neutron sources via an unfolding algorithm. A generalized algorithm is also presented for performing neutron spectroscopy using any other TMFD fluid that meets the SAS approach assumptions.

  5. Neutron spectroscopy of fast hydrogen diffusion in BCC transition metals

    International Nuclear Information System (INIS)

    Richter, D.; Lottner, V.

    1979-01-01

    Quasielastic neutron scattering reveals microscopic details of both the time and space development of the H-diffusion process on an atomic scale. After outlining the method on the example of PdH/sub x/, new results on the jump geometry in bcc metals are surveyed. In particular, the anomalous diffusion behavior of H in Nb, Ta, and V at elevated temperature is emphasized, where correlated jump processes are important. The influence of impurities on the H-diffusion process is demonstrated by experiments performed on NbH/sub x/ doped with nitrogen impurities, which act as trapping centers for the diffusing hydrogen. The results are discussed in terms of a two-state random walk model which includes multiple trapping and detrapping processes. The concentration and temperature dependence of the capture and escape rates of traps are obtained

  6. Neutron spectroscopy, nuclear structure, related topics. Abstracts

    International Nuclear Information System (INIS)

    Sukhovoj, A.M.

    1996-01-01

    Neutron spectroscopy, nuclear structure and related topics are considered. P, T-breaking, neutron beta decay, neutron radiative capture and neutron polarizability are discussed. Reaction with fast neutrons, methodical aspect low-energy fission are considered too

  7. Neutron spectroscopy measurements and modeling of neutral beam heating fast ion dynamics

    International Nuclear Information System (INIS)

    Hellesen, C; Sunden, E Andersson; Conroy, S; Ericsson, G; Johnson, M Gatu; Hjalmarsson, A; Kaellne, J; Ronchi, E; Sjoestrand, H; Weiszflog, M; Albergante, M; Ballabio, L; Gorini, G; Tardocchi, M; Giacomelli, L; Jenkins, I; Voitsekhovitch, I

    2010-01-01

    The energy spectrum of the neutron emission from beam-target reactions in fusion plasmas at the Joint European Torus (JET) has been investigated. Different beam energies as well as injection angles were used. Both measurements and simulations of the energy spectrum were done. The measurements were made with the time-of-flight spectrometer TOFOR. Simulations of the neutron spectrum were based on first-principle calculations of neutral beam deposition profiles and the fast ion slowing down in the plasma using the code NUBEAM, which is a module of the TRANSP package. The shape of the neutron energy spectrum was seen to vary significantly depending on the energy of the beams as well as the injection angle and the deposition profile in the plasma. Cross validations of the measured and modeled neutron energy spectra were made, showing a good agreement for all investigated scenarios.

  8. Improvements in fast-neutron spectroscopy methods (1961); Amelioration des methodes de spectrometrie des neutrons rapides (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Cambou, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-02-15

    This research aimed at improving fast-neutron electronic detectors based on n-p elastic scattering. The first part concerns proportional counters; careful constructional methods have made it possible to plot mono-energetic neutron spectra in the range 700 keV - 3 MeV with a resolution of 7 per cent. The second part concerns scintillation counters: an organic scintillator and an inorganic scintillator covered with a thin layer of a scattering agent. An exact study of the types of scintillation has made it possible to develop efficient discriminator circuits. Different neutron spectra plotted in the presence of a strong gamma background are presented. The last part deals with the development of form discrimination methods for the study, in the actual beam, of the elastic scattering of 14.58 MeV electrons. With hydrogen, the distribution f ({phi}) of the recoil protons is f({phi}) = 1 + 0.034 cos {phi} + 0.042 cos{sup 2} {phi}. With tritium the scattering is strongly anisotropic; the curve representing the variation of the differential cross-section for the elastic scattering in the centre of mass system is obtained with a target containing 1 cm{sup 3} of tritium. (author) [French] Le travail a porte sur l'amelioration des detecteurs electroniques de neutrons rapides bases sur la diffusion elastique n-p. La premiere partie est relative aux compteurs proportionnels; des methodes soignees de fabrication ont permis des traces de spectres de neutrons monoenergetiques dans le domaine 700 keV - 3 MeV avec une resolution de 7 pour cent. La deuxieme partie est relative au compteur a scintillations; scintillateur organique et scintillateur mineral recouvert d'un diffuseur mince. Une etude precise des formes de scintillations a permis la mise au point de circuits discriminateurs efficaces. Differents spectres de neutrons traces en presence d'un fond gamma intense sont presentes. La derniere partie est relative a la mise en oeuvre des methodes de discrimination de forme pour l

  9. Fast neutrons dosimetry

    International Nuclear Information System (INIS)

    Rzyski, B.M.

    1977-01-01

    A proton recoil technique has been developed for inducing thermoluminescence with incident fast neutrons. CaF 2 was used as the TL phosphor, and cane sugar and polyethylene were used as proton radiators. The phosphor and the hydrogeneous material powders were well mixed, encapsulated in glass tubes and exposed to Am-Be sources, resulting in recoils from incident fast neutrons of energy between 0,25 and 11,25 MeV. The intrinsic response of pure CaF 2 to fast neutrons without a hydrogeneous radiator was checked by using LiF (TLD-700). Glow curves were recorded from room temperature up to 350 0 C after different doses of neutrons and gamma rays of 60 Co. First collision dose due to fast neutrons in tissue like materials such as cane sugar and polyethylene was also calculated [pt

  10. The structure of neutron-rich nuclei explored via in-beam gamma-ray spectroscopy of fast beams

    International Nuclear Information System (INIS)

    Glasmacher, T.; Campbell, C.M.; Church, J.A.; Dinca, D.C.; Hansen, P.G.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R.; Bazin, D.; Enders, J.; Gade, A.; Hu, Z.; Mueller, W.F.

    2003-01-01

    In-beam gamma-ray spectroscopy with fast exotic beams provides an efficient tool to study bound states in exotic neutron-rich nuclei. Specialized experimental techniques have been developed and explore different aspects of nuclear structure. Inelastic scattering experiments with γ-ray detection can measure the response of exotic nuclei to electromagnetic (Coulomb excitation with a heavy target) or hadronic probes (proton scattering with hydrogen target). In-beam fragmentation populates higher-lying bound states to establish levels. Single- and two-nucleon knockout reactions allow for detailed wavefunction spectroscopy of individual levels and for the measurement of spectroscopic factors. Experimental programs employing these techniques are now underway at all projectile-fragmentation facilities around the world. Here we report on several successful in-beam gamma-ray spectroscopy experiments that have been performed at the Coupled Cyclotron Facility at Michigan State University with an emphasis on elucidating the evolution of nuclear structure around neutron numbers N=16, N=20, and N=28 in the π(sd) shell. (orig.)

  11. Modeling of neutron emission spectroscopy in JET discharges with fast tritons from (T)D ion cyclotron heating

    International Nuclear Information System (INIS)

    Tardocchi, M.; Gorini, G.; Andersson Sunden, E.; Conroy, S.; Ericsson, G.; Gatu Johnson, M.; Giacomelli, L.; Hellesen, C.; Hjalmarsson, A.; Kaellne, J.; Ronchi, E.; Sjoestrand, H.; Weiszflog, M.; Johnson, T.; Lamalle, P. U.

    2006-01-01

    The measurement of fast ion populations is one of the diagnostic capabilities provided by neutron emission spectroscopy (NES). NES measurements were carried out during JET trace tritium campaign with the magnetic proton recoil neutron spectrometer. A favorable plasma scenario is (T)D where the resulting 14 MeV neutron yield is dominated by suprathermal emission from energetic tritons accelerated by radio frequency at their fundamental cyclotron frequency. Information on the triton distribution function has been derived from NES data with a simple model based on two components referred to as bulk (B) and high energy (HE). The HE component is based on strongly anisotropic tritium distribution that can be used for routine best-fit analysis to provide tail temperature values (T HE ). This article addresses to what extent the T HE values are model dependent by comparing the model above with a two-temperature (bi-) Maxwellian model featuring parallel and perpendicular temperatures. The bi-Maxwellian model is strongly anisotropic and frequently used for radio frequency theory

  12. Innovating analytical spectroscopies for the improvement of liquid sodium cooled fast neutron reactors safety

    International Nuclear Information System (INIS)

    Maury, C.

    2012-01-01

    In the context of the project of sodium fast reactor ASTRID, CEA is currently developing new analytical techniques to monitor the chemical purity of liquid sodium. Indeed, incidental situations occurring in the reactor, such as fuel clad failures, leakages in the steam generator or in the coolant pumps, and accelerated corrosion, might release several elements in the sodium. Analytical techniques based on laser ablation and emission spectroscopy are well suited for this application. They do not require any sample preparation, and can perform direct on-line analysis. Amongst them, Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Ablation coupled to Laser-Induced Fluorescence (LA-LIF) have been selected for this study. The objective of this work was to characterize the sensitivity of those two techniques for the detection of impurities in liquid sodium. Their limits of detection were calculated for model analytes using calibration lines. Then results were theoretically extrapolated to other analytes of interest. This study shows the feasibility of the detection of steel corrosion products in liquid sodium. However, the LIBS technique is more robust and easier to implement, and would therefore be more suited to nuclear conditions. (author) [fr

  13. Use of the associated particle technique in the fast neutron spectroscopy

    International Nuclear Information System (INIS)

    Aquirre O, G.A.

    1978-01-01

    Selecting a neutrons monoenergetic source it was found that the nuclear reaction D(d,n) 3 He can be used to measure nuclear sections and differentials in elastic nuclear reactions through the associated particle technique; the neutron beam energy is directly determined in time of flight spectrum of the neutron. The flux is determined by the number of 3 He ions observed in the charged particle spectrum. The neutron flux can be increased increasing the solid angle of the neutrons beam in two magnitude orders according to the results of neutrons beam profile measures. (author)

  14. Evaluation of few-view reconstruction parameters for illicit substance detection using fast-neutron transmission spectroscopy

    International Nuclear Information System (INIS)

    Fink, C.L.; Humm, P.G.; Martin, M.M.; Micklich, B.J.

    1996-01-01

    The authors have evaluated the performance of an illicit substance detection system that performs image reconstruction using the Maximum Likelihood algebraic reconstruction algorithm, a fe number of projections, and relatively coarse projection and pixel resolution. This evaluation was done using receiver operator curves and simulated data from the fast-neutron transmission spectroscopy system operated in a mode to detect explosives in luggage. The results show that increasing the number of projection angles is more important than increasing the projection resolution, the reconstructed pixel resolution, of the number of iterations in the Maximum Likelihood algorithm. A 100% detection efficiency with essentially no false positives is possible for a square block of RDX explosive, a projection resolution of 2 cm, a reconstructed pixel size of 2x2 cm, and five projection angles. For rectangular shaped explosives more angles are required to obtain the same system performance

  15. Analysis of resonant fast ion distributions during combined ICRF and NBI heating with transients using neutron emission spectroscopy

    Science.gov (United States)

    Hellesen, C.; Mantsinen, M.; Conroy, S.; Ericsson, G.; Eriksson, J.; Kiptily, V. G.; Nabais, F.; Contributors, JET

    2018-05-01

    ICRF heating at the fundamental cyclotron frequency of a hydrogen minority ion species also gives rise to a partial power absorption by deuterium ions at their second harmonic resonance. This paper studies the deuterium distributions resulting from such 2nd harmonic heating at JET using neutron emission spectroscopy data from the time of flight spectrometer TOFOR. The fast deuterium distributions are obtained over the energy range 100 keV to 2 MeV. Specifically, we study how the fast deuterium distributions vary as ICRF heating is used alone as well as in combination with NBI heating. When comparing the different heating scenarios, we observed both a difference in the shapes of the distributions as well as in their absolute level. The differences are most pronounced below 0.5 MeV. Comparisons are made with corresponding distributions calculated with the code PION. We find a good agreement between the measured distributions and those calculated with PION, both in terms of their shapes as well as their amplitudes. However, we also identified a period with signs of an inverted fast ion distribution, which showed large disagreements between the modeled and measured results. Resonant interactions with tornado modes, i.e. core localized toroidal alfven eigenmodes (TAEs), are put forward as a possible explanation for the inverted distribution.

  16. Fast neutron spectroscopy by gas proton-recoil methods at the light water reactor pressure vessel simulator

    International Nuclear Information System (INIS)

    Rogers, J.W.

    1980-10-01

    Fast neutron spectrum measurements were made in a Light Water Reactor (LWR) Pressure Vessel Simulator (PVS) to provide neutron spectral definition required to appropriately perform and interpret neutron dosimetry measurements related to fast neutron damage in LWR-PV steels. Proton-recoil proportional counter methods using hydrogen and methane gas-filled detectors were applied to obtain the proton spectra from which the neutron spectra were derived. Cylindrical and spherical geometry detectors were used to cover the neutron energy range between 50 keV and 2 MeV. Results show that the neutron spectra shift in energy distribution toward lower energy between the front and back of a PVS. The relative neutron flux densities increase in this energy range with increasing thickness of the steel. Neutron spectrum fine structure shapes and changes are observed. These results should assist in the generation of more accurate effective cross sections and fluences for use in LWR-PV fast neutron dosimetry and materials damage analyses

  17. Fast neutron dosimetry

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1993-01-01

    Research concentrated on three major areas during the last twelve months: (1) investigations of energy fluence and absorbed dose measurements using crystalline and hot pressed TLD materials exposes to ultrasoft beams of photons, (2) fast neutron kerma factor measurements for several important elements as well as NE-213 scintillation material response function determinations at the intense ''white'' source available at the WNR facility at LAMPF, and (3) kerma factor ratio determinations for carbon and oxygen to A-150 tissue equivalent plastic at the clinical fast neutron radiation facility at Harper Hospital, Detroit, MI. Progress summary reports of these efforts are given in this report

  18. Fast neutron dosimetry

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1992-01-01

    This progress report concentrates on two major areas of dosimetry research: measurement of fast neutron kerma factors for several elements for monochromatic and white spectrum neutron fields and determination of the response of thermoluminescent phosphors to various ultra-soft X-ray energies and beta-rays. Dr. Zhixin Zhou from the Shanghai Institute of Radiation Medicine, People's Republic of China brought with him special expertise in the fabrication and use of ultra-thin TLD materials. Such materials are not available in the USA. The rather unique properties of these materials were investigated during this grant period

  19. Neutron resonance spectroscopy

    International Nuclear Information System (INIS)

    Gunsing, F.

    2005-06-01

    The present document has been written in order to obtain the diploma 'Habilitation a Diriger des Recherches'. Since this diploma is indispensable to supervise thesis students, I had the intention to write a document that can be useful for someone starting in the field of neutron resonance spectroscopy. Although the here described topics are already described elsewhere, and often in more detail, it seemed useful to have most of the relevant information in a single document. A general introduction places the topic of neutron-nucleus interaction in a nuclear physics context. The large variations of several orders of magnitude in neutron-induced reaction cross sections are explained in terms of nuclear level excitations. The random character of the resonances make nuclear model calculation predictions impossible. Then several fields in physics where neutron-induced reactions are important and to which I have contributed in some way or another, are mentioned in a first synthetic chapter. They concern topics like parity nonconservation in certain neutron resonances, stellar nucleosynthesis by neutron capture, and data for nuclear energy applications. The latter item is especially important for the transmutation of nuclear waste and for alternative fuel cycles. Nuclear data libraries are also briefly mentioned. A second chapter details the R-matrix theory. This formalism is the foundation of the description of the neutron-nucleus interaction and is present in all fields of neutron resonance spectroscopy. (author)

  20. Neutron resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gunsing, F

    2005-06-15

    The present document has been written in order to obtain the diploma 'Habilitation a Diriger des Recherches'. Since this diploma is indispensable to supervise thesis students, I had the intention to write a document that can be useful for someone starting in the field of neutron resonance spectroscopy. Although the here described topics are already described elsewhere, and often in more detail, it seemed useful to have most of the relevant information in a single document. A general introduction places the topic of neutron-nucleus interaction in a nuclear physics context. The large variations of several orders of magnitude in neutron-induced reaction cross sections are explained in terms of nuclear level excitations. The random character of the resonances make nuclear model calculation predictions impossible. Then several fields in physics where neutron-induced reactions are important and to which I have contributed in some way or another, are mentioned in a first synthetic chapter. They concern topics like parity nonconservation in certain neutron resonances, stellar nucleosynthesis by neutron capture, and data for nuclear energy applications. The latter item is especially important for the transmutation of nuclear waste and for alternative fuel cycles. Nuclear data libraries are also briefly mentioned. A second chapter details the R-matrix theory. This formalism is the foundation of the description of the neutron-nucleus interaction and is present in all fields of neutron resonance spectroscopy. (author)

  1. Fast antihydrogen beam spectroscopy

    International Nuclear Information System (INIS)

    Neumann, R.

    1989-01-01

    The motivation for production and precision spectroscopy of antihydrogen atoms is outlined. An experimental configuration is considered, concerning laser-microwave spectroscopy of a fast hydrogen beam with characteristics similar to those of an antihydrogen beam emanating from an antiproton-positron overlap region in an antiproton storage ring. In particular, a possible experiment for the measurement of the ground state hyperfine structure splitting is described. (orig.)

  2. Direct Fast-Neutron Detection

    International Nuclear Information System (INIS)

    DC Stromswold; AJ Peurrung; RR Hansen; PL Reeder

    2000-01-01

    Direct fast-neutron detection is the detection of fast neutrons before they are moderated to thermal energy. We have investigated two approaches for using proton-recoil in plastic scintillators to detect fast neutrons and distinguish them from gamma-ray interactions. Both approaches use the difference in travel speed between neutrons and gamma rays as the basis for separating the types of events. In the first method, we examined the pulses generated during scattering in a plastic scintillator to see if they provide a means for distinguishing fast-neutron events from gamma-ray events. The slower speed of neutrons compared to gamma rays results in the production of broader pulses when neutrons scatter several times within a plastic scintillator. In contrast, gamma-ray interactions should produce narrow pulses, even if multiple scattering takes place, because the time between successive scattering is small. Experiments using a fast scintillator confirmed the presence of broader pulses from neutrons than from gamma rays. However, the difference in pulse widths between neutrons and gamma rays using the best commercially available scintillators was not sufficiently large to provide a practical means for distinguishing fast neutrons and gamma rays on a pulse-by-pulse basis. A faster scintillator is needed, and that scintillator might become available in the literature. Results of the pulse-width studies were presented in a previous report (peurrung et al. 1998), and they are only summarized here

  3. The polarization of fast neutrons

    International Nuclear Information System (INIS)

    Talov, V.V.

    2000-01-01

    The present work is the review of polarization of fast neutrons and methods of polarization analysis. This also includes information about polarization of fast neutrons from first papers, which described polarization in the D(d,n) 3 He, 7 Li(p,n) 7 Be, and T(p,n) 3 He reactions. (authors)

  4. Contraband detection with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Buffler, Andy E-mail: abuffler@science.uct.ac.za

    2004-11-01

    Recent terror events and the increase in the trade of illicit drugs have fuelled the exploration of the use of fast neutrons as probes for the detection of hidden contraband, especially explosives, in packages ranging in size from small mail items to cargo containers. The various approaches using fast neutrons for contraband detection, presently under development, are reviewed. The role that a neutron system might play in the non-intrusive interrogation of airline luggage is discussed.

  5. Fast beam radiofrequency spectroscopy

    International Nuclear Information System (INIS)

    Pipkin, F.M.

    1983-01-01

    The combination of a fast atom or ion beam derived from a small accelerator with radiofrequency spectroscopy methods provides a powerful method for measuring the fine structure of atomic and molecular systems. The fast beam makes possible measurements in which two separated oscillatory fields are used to obtain resonance lines whose widths are less than the natural line width due to the lifetimes of the states. The separated oscillatory field lines have, in addition, a number of features which make possible measurements with greater precision and less sensitivity to systematic errors. The fast beam also makes accessible multiple photon radiofrequency transitions whose line width is intrinsically narrower than that of the single photon transitions and which offer great potential for high precision measurements. This report focuses on the techniques and their promise. Recent measurements of the fine structure of H and He + are used as illustrations

  6. FaNGaS: a New Instrument for Fast Neutron Gamma Spectroscopy at FRM II Research Reactor at Garching

    Energy Technology Data Exchange (ETDEWEB)

    Randriamalala, T.; Rossbach, M.; Genreith, C. [Institute of Energy and Climate Research, IEK-6: Nuclear Waste and Reactor Safety Fuel Cycle, Forchungszentrum Juelich GmbH in der Helmholtz-Gemeinshaft, 52428 Juelich (Germany); Revay, Zs.; Kudejova, P.; Soellradl, S.; Wagner, F.M. [Heinz Maier-Leibnitz Zentrum - MLZ, Technische Universitaet Muenchen, Lichtenbergstrasse 1, 85748 Garching (Germany)

    2015-07-01

    For the identification and quantification of actinides in radioactive packages, the non-destructive method of Prompt-Gamma Activation Analysis (PGAA) is applied. To investigate the inelastic (n, n 'γ) scattering, a new instrumentation was installed at the FRM II research reactor. It is designed to exploit the 10{sup 8} cm{sup -2}s{sup -1} neutrons at an average neutron energy of 1.9 MeV delivered by the SR10 beam line. The outgoing prompt γ-rays are measured utilizing a 50% efficiency HPGe detector. Since the cross sections are expected to be low for such a process, two related factors had to be taken into account for the design of the instrumentation: the high beam intensity at the sample position and the high signal-to-background ratio seen by the detector. Eventual low energy neutrons due to the multiple scatterings through the beam line can be minimized using collimators in the beam tube. This has also an effect to a prior neutrons and photons background reduction of the experimental environment. A higher efficiency of the counting can be achieved by the lowering of background at the detector. In this case, a heavy shielding for both neutrons and photons, is designed around the detector while optimizing the sample-detector distance. Monte-Carlo simulation studies were conducted to effectively design the fast neutron beam collimators and the detector shield. A detailed description of the setup characterization and results from simulations and experimental measurements will be discussed through this contribution. (authors)

  7. The polarization of fast neutrons

    International Nuclear Information System (INIS)

    Talov, V.V.

    2001-01-01

    It is insufficient to know coordinates and momentum to describe a state of a neutron. It is necessary to define a spin orientation. As far as it is known from quantum mechanics, a half spin has a projection in the positive direction or in the negative direction. The probability of both projections in an unpolarized beam is equal. If a direction exists, in which the projection is more probably then beam is called polarized in this direction. It is essential to know polarization of neutrons for characteristics of a neutron source, which is emitting it. The question of polarization of fast neutrons came up in 50's. The present work is the review of polarization of fast neutrons and methods of polarization analysis. This also includes information about polarization of fast neutrons from first papers, which described polarization in the D(d,n) 3 He, 7 Li (p,n) 7 Be, T(p,n) 3 He reactions. (authors)

  8. $\\gamma$ and fast-timing spectroscopy of the doubly magic $^{132}$Sn and its one- and two-neutron particle/hole neighbours

    CERN Multimedia

    We propose to use fast-timing and spectroscopy to study five nuclei including the doubly magic $^{132}$Sn and its four neighbours: two-neutron hole $^{130}$Sn, one-neutron hole $^{131}$Sn, one-neutron particle $^{133}$Sn and two-neutron particle $^{134}$Sn. There is an increasing interest in these nuclei since they serve to test nuclear models using state-of-the-art interactions and many body approaches, and they provide information relevant to deduce single particle states. In addition properties of these nuclei are very important to model the astrophysical $\\textit{r-process}$. The present ISOLDE facility provides unique capabilities to study these Sn nuclei populated in the $\\beta$-decay of In isomers, produced from a UCx target unit equipped with neutron converter and ionized with RILIS, capable of selective isomer ionization. The increased production yields for $^{132}$In are estimated to be 200 larger than in the previous work done at OSIRIS. We will use the recently commissioned Isolde Decay Station (I...

  9. Fast neutron spectrometry and dosimetry

    International Nuclear Information System (INIS)

    Blaize, S.; Ailloud, J.; Mariani, J.; Millot, J.P.

    1958-01-01

    We have studied fast neutron spectrometry and dosimetry through the recoil protons they produce in hydrogenated samples. In spectrometric, we used nuclear emulsions, in dosimetric, we used polyethylene coated with zinc sulphide and placed before a photomultiplier. (author) [fr

  10. Computerized tomography using fast neutrons

    International Nuclear Information System (INIS)

    Maier-Schuler, P.

    1992-03-01

    The equipment is transportable and can be used at different neutron sources. CT-images are presented showing that it is possible to get good results by using CT with fast neutrons in non destructive testing. Small defects with high contrasts can be detected as well as larger defects with small differences in material density. Since the neutrons interact with the nuclei and not with the electron density the CT-images contain different information compared with X-ray or γ images. As neutron sources always emit γ-radiation too, this radiation can be detected simultaneously with the neutrons. Therefore one can get a γ CT-image along with the neutron image. For the examination of small samples or objects containing materials with great differences in the linear attenuation coefficients like Al and H 2 thermal neutrons have been used for CT-measurements too. A spatial resolution and a density resolution of 0.1 mm and about 5% respectively could be achieved in the CT-images with fast neutrons and 0.04 mm with thermal neutrons. (orig./HP) [de

  11. Fast neutron dosimetry

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1991-01-01

    During 1988--1990 the magnetic resonance dosimetry project was completed, as were the 250 MeV proton shielding measurements. The first cellular experiment using human cells in vitro at the 1 GeV electron storage ring was also accomplished. More detail may be found in DOE Report number-sign DOE/EV/60417-002 and the open literature cited in the individual progress subsections. We report Kinetic Energy Released in Matter (KERMA), factor measurements in several elements of critical importance to neutron radiation therapy and radiation protection for space habitation and exploration for neutron energies below 30 MeV. The results of this effort provide the only direct measurements of the oxygen and magnesium kerma factors above 20 MeV neutron energy, and the only measurements of the iron kerma factor above 15 MeV. They provide data of immediate relevance to neutron radiotherapy and impose strict criteria for normalizing and testing nuclear models used to calculate kerma factors at higher neutron energies

  12. Intermultiplet transitions using neutron spectroscopy

    International Nuclear Information System (INIS)

    Osborn, R.; Lovesey, S.W.; Taylor, A.D.; Balcar, E.

    1989-12-01

    Neutron inelastic scattering is used here to attempt to obtain optical spectra for lanthanide metals and compounds. Intermultiplet spectroscopy provides information about transitions from different electronic configurations and hybridisation of the 4f shell. This report discusses the relatively limited contribution that neutron scattering has played in intermultiplet spectroscopy, and covers spin-orbit transitions and coulomb transitions Racah algebra is developed in calculating the scattering cross sections. (author)

  13. Medical radiography with fast neutrons

    International Nuclear Information System (INIS)

    Duehmke, E.

    1980-01-01

    Neutron radiography is important in medicine for two reasons. On the one hand, macroradiographical findings are different from X-ray findings, i.e. new information may be gained on the morphology of humans and animals. On the other hand, there is a direct practical application in the radiotherapy of malignant tumours if one considers the assessment of the growth of malignant processes. Fast neutrons are required for neutron radiographies of biological objects with a diameter of more than 2 cm. In addition sensitive, two-dimensional detectors must be used which are selective for fast neutrons. The book describes the optimisation and sensitisation of a detector using the example of cellulose nitrate foil for fast reactor neutrons. Images of human spinal chords with tumours proved by pathological and anatomical examinations give a better picture of the dimensions of the tumour than comparative X-ray pictures. For examinations of living patients, neutron radiography should be applied only in those tumour-bearing parts of the bodies in which radiation treatment is required for therapeutical purposes anyway. (orig./MG) [de

  14. Fast neutron physics

    International Nuclear Information System (INIS)

    Moura Neto, C. de; Amorim, E.S. do.

    1979-12-01

    Finite systems of small dimensions were investigated in comparison with systems where the diffusion theory is valid with reasonable precision. Elaborated methods were introduced for the study of small systems, based on different approximations of the neutron transport equation. Experimental data, obtained from the literature, were compared with values by the ANISN-DLC/2D system. (Author) [pt

  15. Dosimetry of fast neutrons

    International Nuclear Information System (INIS)

    Jahr, R.

    1975-03-01

    Following an explanation of the physical fundamentals of neutron dosimetry, the special needs in medicine and biology are gone into. It is shown that the dose equivalent used in radiation protection simplifies in an undue manner the complicated dependence of the biological effects. The reason for this is the fact that the RBE for heavy recoil nuclei, amongst others, depends on the energy and sort of particle, whereas it is approximately equal to one for electrons independent of the energy. It is thus necessary in the fields of biology and medicine to have additional information on energy spectra of the neutrons as well as of all charged secondary particles as a function of the position in the phantom. These are obtained partly by calculation and partly by special dosemeters. The accuracy achieved so far is 5%. (ORU/LH) [de

  16. Fast neutron activation analysis

    International Nuclear Information System (INIS)

    Pepelnik, R.

    1986-01-01

    Since 1981 numerous 14 MeV neutron activation analyses were performed at Korona. On the basis of that work the advantages of this analysis technique and therewith obtained results are compared with other analytical methods. The procedure of activation analysis, the characteristics of Korona, some analytical investigations in environmental research and material physics, as well as sources of systematic errors in trace analysis are described. (orig.) [de

  17. Neutron spectroscopy for confinement studies

    International Nuclear Information System (INIS)

    Zorn, R.

    2010-01-01

    Neutron spectroscopy is an important method for the study of microscopic dynamics because it captures the spatial as well as the temporal aspects of the atomic or molecular motion. In this article techniques will be presented which are of special importance for the study of confined systems. Many of these are based on the fact that neutron scattering is isotope-dependent. Possible sources of systematic errors in measurements of confined systems will be pointed out. (author)

  18. [Fast neutron cross section measurements

    International Nuclear Information System (INIS)

    Knoll, G.F.

    1992-01-01

    From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are ''clean'' and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its ''data production'' phase

  19. Intermediate and fast neutron absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1987-10-01

    The experimental fuel channel EFC is created as one of the fast neutron fields at the RB reactor. The intermediate and fast neutron spectra in EFC are measured by activation technique. The intermediate and fast neutron absorbed doses are computed on the basis of these experimental results. At the end the obtained doses are compared. (author)

  20. Ionization signals from diamond detectors in fast-neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); CIVIDEC Instrumentation, Wien (Austria); Frais-Koelbl, H. [University of Applied Sciences, Wiener Neustadt (Austria); Griesmayer, E.; Kavrigin, P. [CIVIDEC Instrumentation, Wien (Austria); Vienna University of Technology, Wien (Austria)

    2016-09-15

    In this paper we introduce a novel analysis technique for measurements with single-crystal chemical vapor deposition (sCVD) diamond detectors in fast-neutron fields. This method exploits the unique electronic property of sCVD diamond sensors that the signal shape of the detector current is directly proportional to the initial ionization profile. In fast-neutron fields the diamond sensor acts simultaneously as target and sensor. The interaction of neutrons with the stable isotopes {sup 12}C and {sup 13}C is of interest for fast-neutron diagnostics. The measured signal shapes of detector current pulses are used to identify individual types of interactions in the diamond with the goal to select neutron-induced reactions in the diamond and to suppress neutron-induced background reactions as well as γ-background. The method is verified with experimental data from a measurement in a 14.3 MeV neutron beam at JRC-IRMM, Geel/Belgium, where the {sup 13}C(n, α){sup 10}Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the {sup 12}C(n, α){sup 9}Be reaction was substantially improved. The presented analysis technique is especially relevant for diagnostics in harsh radiation environments, like fission and fusion reactors. It allows to extract the neutron spectrum from the background, and is particularly applicable to neutron flux monitoring and neutron spectroscopy. (orig.)

  1. Fast neutron activation analysis in metallurgy

    International Nuclear Information System (INIS)

    Sterlinski, S.

    1981-01-01

    Article discusses the usage of a 14 MeV neutron generator for producing fast neutrons of different energies and intensities. A complete instrumental set-up for the neutron activation analysis (NAA) is given. In metallurgy the device is mainly used in the determination of oxygen and silicon in steel and non-ferrous metal, including different alloys

  2. A silicon diode for fast neutron dosimetry

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    The effect of fast neutrons on both animate and inanimate objects, including human beings, can be extremely serious and cumulative. There is thus a need for a small, simple and cheap component which will provide a permanent or semi-permanent record of the accumulated fast neutron dose

  3. Fast neutron dosimetry: Progress summary

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.

    1988-01-01

    The purpose was to investigate the radiological physics and biology of very low energy photons derived from a 1-GeV electron synchrotron storage ring. An extensive beam line and irradiation apparatus was designed, developed, and constructed. Dosimetry measurements required invention and testing of a miniature absolute calorimeter and a cell irradiation fixture suitable for scanning exposures under computer control. Measurements of the kerma factors of oxygen, aluminum and silicon for 14-20 MeV neutrons. Custom designed miniature proportional counters of cylindrical symmetry were employed in these determinations. The oxygen kerma factor was found significantly lower than values calculated from microscopic cross sections. We also tested Mg and Fe walled conventional spherical counters. The direct neutron-counting gas interaction is significant enough for these counters that a correction is needed. We also investigated the application of Nuclear Magnetic Resonance spectroscopy to radiation dosimetry. Our purpose was to take advantage of recent development of very high-field magnets, complex RF-pulse techniques for solvent suppression, and improved spectral analysis techniques

  4. General remarks on fast neutron reactor physics

    International Nuclear Information System (INIS)

    Barre, J.Y.

    1980-01-01

    The main aspects of fast reactor physics, presented in these lecture notes, are restricted to LMFBR's. The emphasis is placed on the core neutronic balance and the burn-up problems. After a brief description of the power reactor main components and of the fast reactor chronology, the fundamental parameters of the one-group neutronic balance are briefly reviewed. Then the neutronic burn-up problems related to the Pu production and to the doubling time are considered

  5. Neutron molecular spectroscopy: future prospects

    International Nuclear Information System (INIS)

    Tomkinson, J.; Carlile, C.J.; Krishna, P.S.R.

    1994-07-01

    The recent revolution in Neutron Molecular Spectroscopy, caused by extending the spectral range, is briefly reviewed. The need to constantly improve the spectral resolution is underlined and the likely benefits are identified. Recent work on improving the energy resolution on TFXA is presented and three future options for TFXA are outlined. Some preliminary high resolution results, from a mock-up spectrometer, are reported. These clearly show that narrow bands are available in solids and improved resolutions can be achieved to observe them. (Author)

  6. Fast neutron dosimeter with wide base silicon diode

    International Nuclear Information System (INIS)

    Ma Lu

    1986-01-01

    This paper briefly introduces a wide base silicon diode fast neutron dosimeter with wide measuring range and good energy response to fast neutron. It is suitable to be used to detect fast neutrons in the mixed field of γ-ray, thermal neutrons and fast neutrons

  7. Accelerator requirements for fast-neutron interrogation of luggage and cargo

    International Nuclear Information System (INIS)

    Micklich, B.J.; Fink, C.L.; Yule, T.J.

    1995-01-01

    Several different fast-neutron based techniques are being studied for the detection of contraband substances in luggage and cargo containers. The present work discusses the accelerator requirements for fast-neutron transmission spectroscopy (FNTS), pulsed fast-neutron analysis (PFNA), and 14-MeV neutron interrogation. These requirements are based on the results of Monte-Carlo simulations of neutron or gamma detection rates. Accelerator requirements are driven by count-rate considerations, spatial resolution and acceptable uncertainties in elemental compositions. The authors have limited their analyses to luggage inspection with FNTS and to cargo inspection with PFNA or 14-MeV neutron interrogation

  8. Fast neutron radiography using photoluminescent imaging plates

    International Nuclear Information System (INIS)

    Rant, J.; Kristof, E.; Balasko, M.; Stade, J.

    1999-01-01

    Fast neutron radiography (FNR) and resonance neutron radiography (RNR) are complementary to the conventional radiography with high energy gamma-rays or brems-strahlung radiation used for the inspection of thick metal objects. In both non-destructive methods, the contrast sensitivity and the penetration power can be improved by using higher energy neutrons. At present direct techniques based either n Solid State Nuclear Track detectors (SSNTDs) or scintillating screens and transfer techniques using activation threshold detectors and radiographic films are applied for the detection of fast neutron images. Rather low detection sensitivity of film and SSNTD based fast neutron imaging methods and also rather poor inherent image contrast of SSNTD pose a problem for FNR in the fast neutron energy region 1-15 MeV interesting for NDT. For more efficient detection of fast neutron images the use of novel highly sensitive photoluminescent imaging plates (IP) in combination with threshold at the KFKI research reactor. The conventional IP produced by FUJI Photo Film Co. for the detection of beta and X-ray radiation were used. The threshold activation detectors were the reactions 115 In(n, n') 115m In, 64 Zn(n,p) 64 Cu, 56 Fe(n, p) 56 Mn, 24 Mg(n, p) 24 Na and 27 Al(n, α) 24 Na. These threshold reactions cover the fast neutron energy region between 0,7 MeV and 12 MeV. Pure, commercially available metals 0,1 mm to 0,25 mm thick made of In, Zn, Fe, Mg and Al were used as converter screens. The very high sensitivity of IP, the linearity of their response over 5 decades of exposure dose and the high dynamic digitalisation latitude enabled fast neutron radiography of image quality comparable to the quality of thermal NR. In our experimental conditions (φ n ∼ 10 8 n/cm 2 s, R Cd ∼ 2) the neutron exposure and IP exposure periods were still practical and comparable to the half life of the corresponding reaction products (half an hour to several hours). Even with the 27 Al(n.α) 24

  9. Neutron characteristic and spectroscopy logging methods and apparatus

    International Nuclear Information System (INIS)

    Antkiw, S.

    1977-01-01

    Earth formations surrounding a well bore are irradiated with pulses of fast neutrons, and gamma rays resulting from the ensuring thermal neutron capture interactions with nuclei of the formations are detected, from which measurements of the thermal neutron decay times characterizing the respective formations are derived. The gamma ray energy spectra of the respective formations are analyzed. Gating of the gamma ray detection periods is automatically controlled, both for the decay time and the spectroscopy functions, in accrdance with the measured values of the decay times. The duration and repetition rate of the neutron pulses are also controlled as a function of the measured decay times to provide an overall optimized decay time-spectroscopy operating cycle. spectroscopy outputs representative of formation lithology, salinity, porosity and shaliness are developed to supplement and improve decay time log interpretation

  10. Charge deep level transient spectroscopy study of 3 - 7 MeV/amu ion and fast neutron irradiation-induced changes in MOS structures

    International Nuclear Information System (INIS)

    Stano, J.; Skuratov, V.A.; Ziska, M.

    2001-01-01

    Radiation-induced changes in MOS capacitor structures irradiated with Bi (710 MeV), Kr (245 MeV), Ar (280, 155 MeV) ions and fast neutrons (E > 0.1 MeV) have been studied in view of Q-DLTS and C-V techniques. As was found, high energy ion and neutron irradiation enhance the induction of positive charge density in the oxide layer of MOS samples. The number of electrically active defects in this layer strongly decreases under dense electronic excitations. No dependence of vacancy-oxygen center concentration in silicon substrate normalized per number of displaced atoms by nuclear elastic collisions on projectile type have been observed

  11. Some neutronics of innovative subcritical assembly with fast neutron spectrum

    International Nuclear Information System (INIS)

    Kiyavitskaya, H.; Fokov, Yu.; Rutkovskaya, Ch.; Sadovich, S.; Kasuk, D.; Gohar, Y.; Bolshinsky, I.

    2013-01-01

    Conclusion: • New assembly can be used to: • develop the experimental techniques and adapt the existing ones for monitoring the sub-criticality level, neutron spectra measurements, etc; • study the spatial kinetics of sub-critical and critical systems with fast neutron spectra; • measure the transmutation reaction rates of minor-actinides etc

  12. Clinical application of fast neutrons

    International Nuclear Information System (INIS)

    Battermann, J.J.

    1981-01-01

    The results of treatments and clinical experiments with neutrons (from a medical d+T neutron generator with an output of 10 12 neutrons per second) are reported and discussed. Data on RBE values are presented after single doses and multiple fractions of neutrons and 60 Co-gamma rays on pulmonary metastases. The results of pilot studies on head and neck tumours, brain tumours and pelvic tumours are discussed. The accuracy of the calculated dose is tested with some in-vivo experiments during neutron irradiation of the pelvis. Estimations of RBE values for tumour control, skin damage and intestinal damage after fractionated neutron therapy are dealt with and the results obtained in treatment of sarcomas are discussed. The preliminary results are given of some clinical trials in Amsterdam. Also some data from other centres are reviewed. From these data some remarks about the future of neutron therapy are made. (Auth.)

  13. System design considerations for fast-neutron interrogation systems

    International Nuclear Information System (INIS)

    Micklich, B.J.; Curry, B.P.; Fink, C.L.; Smith, D.L.; Yule, T.J.

    1993-01-01

    Nonintrusive interrogation techniques that employ fast neutrons are of interest because of their sensitivity to light elements such as carbon, nitrogen, and oxygen. The primary requirement of a fast-neutron inspection system is to determine the value of atomic densities, or their ratios, over a volumetric grid superimposed on the object being interrogated. There are a wide variety of fast-neutron techniques that can provide this information. The differences between the various nuclear systems can be considered in light of the trade-offs relative to the performance requirements for each system's components. Given a set of performance criteria, the operational requirements of the proposed nuclear systems may also differ. For instance, resolution standards will drive scanning times and tomographic requirements, both of which vary for the different approaches. We are modelling a number of the fast-neutron interrogation techniques currently under consideration, to include Fast Neutron Transmission Spectroscopy (FNTS), Pulsed Fast Neutron Analysis (PFNA), and its variant, 14-MeV Associated Particle Imaging (API). The goals of this effort are to determine the component requirements for each technique, identify trade-offs that system performance standards impose upon those component requirements, and assess the relative advantages and disadvantages of the different approaches. In determining the component requirements, we will consider how they are driven by system performance standards, such as image resolution, scanning time, and statistical uncertainty. In considering the trade-offs between system components, we concentrate primarily on those which are common to all approaches, for example: source characteristics versus detector array requirements. We will then use the analysis to propose some figures-of-merit that enable performance comparisons between the various fast-neutron systems under consideration. The status of this ongoing effort is presented

  14. Fast neutron analysis code SAD1

    International Nuclear Information System (INIS)

    Jung, M.; Ott, C.

    1985-01-01

    A listing and an example of outputs of the M.C. code SAD1 are given here. This code has been used many times to predict responses of fast neutrons in hydrogenic materials (in our case emulsions or plastics) towards the elastic n, p scattering. It can be easily extended to other kinds of such materials and to any kind of incident fast neutron spectrum

  15. Novel applications of fast neutron interrogation methods

    International Nuclear Information System (INIS)

    Gozani, Tsahi

    1994-01-01

    The development of non-intrusive inspection methods for contraband consisting primarily of carbon, nitrogen, oxygen, and hydrogen requires the use of fast neutrons. While most elements can be sufficiently well detected by the thermal neutron capture process, some important ones, e.g., carbon and in particular oxygen, cannot be detected by this process. Fortunately, fast neutrons, with energies above the threshold for inelastic scattering, stimulate relatively strong and specific gamma ray lines from these elements. The main lines are: 6.13 for O, 4.43 for C, and 5.11, 2.31 and 1.64 MeV for N. Accelerator-generated neutrons in the energy range of 7 to 15 MeV are being considered as interrogating radiations in a variety of non-intrusive inspection systems for contraband, from explosives to drugs and from coal to smuggled, dutiable goods. In some applications, mostly for inspection of small items such as luggage, the decision process involves a rudimentary imaging, akin to emission tomography, to obtain the localized concentration of various elements. This technique is called FNA - Fast Neutron Analysis. While this approach offers improvements over the TNA (Thermal Neutron Analysis), it is not applicable to large objects such as shipping containers and trucks. For these challenging applications, a collimated beam of neutrons is rastered along the height of the moving object. In addition, the neutrons are generated in very narrow nanosecond pulses. The point of their interaction inside the object is determined by the time of flight (TOF) method, that is measuring the time elapsed from the neutron generation to the time of detection of the stimulated gamma rays. This technique, called PFNA (Pulsed Fast Neutron Analysis), thus directly provides the elemental, and by inference, the chemical composition of the material at every volume element (voxel) of the object. The various neutron-based techniques are briefly described below. ((orig.))

  16. Spectroscopic study of fast-neutron-irradiated chromatin

    International Nuclear Information System (INIS)

    Radu, L.; Gazdaru, D.; Constantinescu, B.

    2004-01-01

    The effects produced by fast neutrons (0-100 Gy) on chromatin structure were analyzed by (i) [ 1 H]-NMR spectroscopy, (ii) time resolved spectroscopy, and (iii) fluorescence resonance energy transfer (FRET). Two types of chromatin were tested: (i) a chromatin from a normal tissue (liver of Wistar rats) and (ii) a chromatin from a tumoral tissue (Guerin limphotrope epithelioma, a rat solid tumor). The fast-neutron action on chromatin determines greater values of the [ 1 H]-NMR transverse relaxation time, indicating a more injured structure. Time-resolved fluorescence measurements show that the relative contribution of the excited state lifetime of bound ethidium bromide to chromatin DNA diminishes with increasing irradiation doses. This reflects the damage that occurs in DNA structure: production of single- and double-strand breaks due to sugar and base modifications. By the FRET method, the distance between dansyl chloride and acridine orange coupled at chromatin was determined. This distance increases upon fast-neutron action. The radiosensitivity of the tumor tissue chromatin seems higher than that of the normal tissue chromatin, probably because of its higher (loose) euchromatin/(compact) heterochromatin ratio. As the values of the physical parameters analyzed are specific for a determined dose, the establishment of these parameters may constitute a criterion for the microdosimetry of chromatin radiolesions produced by fast neutrons. (author)

  17. Spectroscopic study of fast-neutron-irradiated chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L. [V. Babes National Inst., Dept. of Molecular Genetics, Bucharest (Romania)]. E-mail: serbanradu@pcnet.ro; Gazdaru, D. [Bucharest Univ., Dept. of Biophysics, Physics Faculty, Bucharest (Romania); Constantinescu, B. [H. Hulubei National Inst., Dept. of Cyclotron, Bucharest (Romania)

    2004-02-01

    The effects produced by fast neutrons (0-100 Gy) on chromatin structure were analyzed by (i) [{sup 1}H]-NMR spectroscopy, (ii) time resolved spectroscopy, and (iii) fluorescence resonance energy transfer (FRET). Two types of chromatin were tested: (i) a chromatin from a normal tissue (liver of Wistar rats) and (ii) a chromatin from a tumoral tissue (Guerin limphotrope epithelioma, a rat solid tumor). The fast-neutron action on chromatin determines greater values of the [{sup 1}H]-NMR transverse relaxation time, indicating a more injured structure. Time-resolved fluorescence measurements show that the relative contribution of the excited state lifetime of bound ethidium bromide to chromatin DNA diminishes with increasing irradiation doses. This reflects the damage that occurs in DNA structure: production of single- and double-strand breaks due to sugar and base modifications. By the FRET method, the distance between dansyl chloride and acridine orange coupled at chromatin was determined. This distance increases upon fast-neutron action. The radiosensitivity of the tumor tissue chromatin seems higher than that of the normal tissue chromatin, probably because of its higher (loose) euchromatin/(compact) heterochromatin ratio. As the values of the physical parameters analyzed are specific for a determined dose, the establishment of these parameters may constitute a criterion for the microdosimetry of chromatin radiolesions produced by fast neutrons. (author)

  18. A new electret dosimeter for fast neutrons

    International Nuclear Information System (INIS)

    Campos, L.L.; Suarez, A.A.; Mascarenhas, S.

    1982-01-01

    A new electret for fast-neutron personnel dosimetry is described and calibration curves obtained. Its performance may be improved by changes in the wall composition and geometric parameters. The advantages of electrets over TL and film are the non-erasure of information, low cost, fast reading and portability. (U.K.)

  19. Chemical reactions induced by fast neutron irradiation

    International Nuclear Information System (INIS)

    Katsumura, Y.

    1989-01-01

    Here, several studies on fast neutron irradiation effects carried out at the reactor 'YAYOI' are presented. Some indicate a significant difference in the effect from those by γ-ray irradiation but others do not, and the difference changes from subject to subject which we observed. In general, chemical reactions induced by fast neutron irradiation expand in space and time, and there are many aspects. In the time region just after the deposition of neutron energy in the system, intermediates are formed densely and locally reflecting high LET of fast neutrons and, with time, successive reactions proceed parallel to dissipation of localized energy and to diffusion of the intermediates. Finally the reactions are completed in longer time region. If we pick up the effects which reserve the locality of the initial processes, a significant different effect between in fast neutron radiolysis and in γ-ray radiolysis would be derived. If we observe the products generated after dissipation and diffusion in longer time region, a clear difference would not be observed. Therefore, in order to understand the fast neutron irradiation effects, it is necessary to know the fundamental processes of the reactions induced by radiations. (author)

  20. A system for fast neutron radiography

    International Nuclear Information System (INIS)

    Klann, R.T.

    1996-01-01

    A system has been designed and a neutron generator installed to perform fast neutron radiography. With this sytem, objects as small as a coin or as large as a waste drum can be radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3x10 10 neutrons/second with an average energy of 14.5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available cassettes. The cassettes have been modified to include a thin sheet of plastic to convert neutrons to protons through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9x10 7 to 3.8x10 8 n/cm 2 depending on the type of screen and film

  1. A Direction Sensitive Fast Neutron Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Antolkovic, B; Holmqvist, B; Wiedling, T

    1964-06-15

    A direction sensitive fast neutron monitor is described and its properties are discussed in some detail. The counter is a modification of the standard long counter of the Hanson and McKibben type. Directional sensitivity is obtained by increasing the shielding of the counter and providing it with a 70 cm long collimator channel. The behaviour of this long counter monitor is compared with that of a standard long counter when both are used in neutron experiments.

  2. Fast neutron damage in germanium detectors

    International Nuclear Information System (INIS)

    Kraner, H.W.

    1979-10-01

    The effects of fast neutron radiation damage on the performance of both Ge(Li) and Ge(HP) detectors have been studied during the past decade and will be summarized. A review of the interaction processes leading to the defect structures causing trapping will be made. The neutron energy dependence of observable damage effects will be considered in terms of interaction and defect production cross sections

  3. Fast neutron therapy in advanced malignant tumour treatment

    International Nuclear Information System (INIS)

    Avinc, A.

    1998-01-01

    In this report the fast neutron therapy applications were examined by thoroughly consideration of the fast neutron sources and the interactions of the fast neutron by the medium. The efficacy of fast neutron radiotherapy with that of patients with locally advanced tumours were compared. Radiological data indicate that fast neutrons could bring benefit in the treatment of some tumour types especially salivary glands, paranasal sinuses, soft tissue sarcomas, prostatic adenocarcinomas, palliative treatment of melanoma and rectum. There is a significant improvement in local/regional control for the neutron group, but no improvement in the survival. The neutron therapy is suggested through which this benefit could be achieved

  4. Measurement of fast neutron background in SAGE

    CERN Document Server

    Abdurashitov, J N; Kalikhov, A V; Matushko, V L; Shikhin, A A; Yants, V E; Zaborskaia, O S

    2002-01-01

    The spectrometer intended for direct measurements of ultra low fluxes of fast neutrons is described. It is sensitive to neutron fluxes of 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 +- 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 +- 2.1) x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4700 meters of water equivalent was measured to be (7.3 +- 2.4) x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be < 2.3 x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in 1.0-11.0 MeV energy range.

  5. Measurement of fast neutron background in SAGE

    International Nuclear Information System (INIS)

    Abdurashitov, J.N.; Gavrin, V.N.; Kalikhov, A.V.; Matushko, V.L.; Shikhin, A.A.; Yants, V.E.; Zaborskaia, O.S.

    2002-01-01

    The spectrometer intended for direct measurements of ultra low fluxes of fast neutrons is described. It is sensitive to neutron fluxes of 10 -7 cm -2 s -1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 ± 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 ± 2.1) x 10 -7 cm -2 s -1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4700 meters of water equivalent was measured to be (7.3 ± 2.4) x 10 -7 cm -2 s -1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be -7 cm -2 s -1 in 1.0-11.0 MeV energy range

  6. Investigation of the reflection of fast neutrons

    International Nuclear Information System (INIS)

    Devillers, Christian; Hasselin, Gilbert

    1964-10-01

    The authors report the study of the reflection of fast neutrons on a plane plate having a finite and varying thickness and an infinite width. Calculations are performed by using a Monte-Carlo method which allows the number, the energy, the direction, the emergence point of neutrons reflected on a plate, to be computed with respect to the energy and direction of incident neutrons. The author present how paths, elastic and inelastic shocks, direction after shock are calculated. Different information are calculated: the numbers of elastic shocks, inelastic shocks and transmitted neutrons, the number, energy and dose albedo, the spectrum and angular distribution, the distribution of neutron in terms of energy and direction

  7. Radiation therapy with fast neutrons: A review

    International Nuclear Information System (INIS)

    Jones, D.T.L.; Wambersie, A.

    2007-01-01

    Because of their biological effects fast neutrons are most effective in treating large, slow-growing tumours which are resistant to conventional X-radiation. Patients are treated typically 3-4 times per week for 4-5 weeks (sometimes in combination with X-radiation) for a variety of conditions such as carcinomas of the head and neck, salivary gland, paranasal sinus and breast; soft tissue, bone and uterine sarcomas and malignant melanomas. It is estimated that about 27,000 patients have undergone fast neutron therapy to date

  8. Fast Neutron Radiation Effects on Bacillus Subtili

    International Nuclear Information System (INIS)

    Chen Xiaoming; Zhang Jianguo; Chu Shijin; Ren Zhenglong; Zheng Chun; Yang Chengde; Tan Bisheng

    2009-01-01

    To examine the sterilizing effect and mechanism of neutron radiation, Bacillus subtilis var. niger. strain (ATCC 9372) spores were irradiated with the fast neutron from the Chinese fast burst reactor II(CFBR-II). The plate-count results indicated that the D 10 value was 384.6 Gy with a neutron radiation dose rate of 7.4 Gy/min. The rudimental catalase activity of the spores declined obviously with the increase in the radiation dose. Meanwhile, under the scanning electron microscope, no visible influence of the neutron radiation on the spore configuration was detected even if the dose was increased to 4 kGy. The content and distribution of DNA double-strand breaks induced by neutron radiation at different doses were measured and quantified by pulsed-field gel electrophoresis (PFGE). Further analysis of the DNA release percentage (PR), the DNA breakage level (L), and the average molecular weight, indicated that DNA fragments were obviously distributed around the 5 kb regions at different radiation doses, which suggests that some points in the DNA molecule were sensitive to neutron radiation. Both PR and L varied regularly to some extent with the increase in radiation dose. Thus neutron radiation has a high sterilization power, and can induce falling enzyme activity and DNA breakage in Bacillus subtilis spores

  9. Advances in neutron scattering spectroscopy

    International Nuclear Information System (INIS)

    White, J.W.

    1977-01-01

    Some aspects of the application of neutron scattering to problems in polymer science, surface chemistry, and adsorption phenomena, as well as molecular biology, are reviewed. In all these areas, very significant work has been carried out using the medium flux reactors at Harwell, Juelich and Risoe, even without the use of advanced multidetector techniques or of a neutron cold source. A general tendency can also be distinguished in that, for each of these new fields, a distinct preference for colder neutrons rather than thermal neutron beams can be seen. (author)

  10. Random pulsing of neutron source for inelastic neutron scattering gamma ray spectroscopy

    International Nuclear Information System (INIS)

    Hertzog, R.C.

    1981-01-01

    Method and apparatus are described for use in the detection of inelastic neutron scattering gamma ray spectroscopy. Data acquisition efficiency is enhanced by operating a neutron generator such that a resulting output burst of fast neutrons is maintained for as long as practicably possible until a gamma ray is detected. Upon the detection of a gamma ray the generator burst output is terminated. Pulsing of the generator may be accomplished either by controlling the burst period relative to the burst interval to achieve a constant duty cycle for the operation of the generator or by maintaining the burst period constant and controlling the burst interval such that the resulting mean burst interval corresponds to a burst time interval which reduces contributions to the detected radiation of radiation occasioned by other than the fast neutrons

  11. Risk from fast neutron exposure

    International Nuclear Information System (INIS)

    Bond, V.P.

    1978-01-01

    The recommendations made by Rossi and Mays imply that the risk associated with the current annual dose equivalent limit of 5 rem for all radiations is unacceptably high, that this limit must be reduced by a factor of 10 or more, and that the conservative linear, no threshold hypothesis must be abandoned. It is shown here that these recommendations are not supported by the newly-analyzed neutron data, and certainly cannot be applied selectively to the annual absorbed dose limit for neutrons. In particular, the judgment that the risk of an annual exposure from 0.5 rad (5 rem) of neutrons is unacceptable high, although perhaps defensible as a personal opinion of the authors, does not follow either from the assumption of a linear-quadratic dose effect relation for low-LET radiation or from other radiobiological considerations. At issue is the level of risk that is to be considered acceptable, a question that is societal and thus not resolvable on purely technical or scientific grounds

  12. The Edinburgh experience of fast neutron therapy

    International Nuclear Information System (INIS)

    Duncan, W.; Arnott, S.J.; Orr, J.A.; Kerr, G.R.

    1982-01-01

    The Edinburgh experience is based on a d(15 + Be) neutron beam generated by a compact CS 30 Cyclotron. Neutron therapy alone given in 20 daily fractions over four weeks has been compared with photon therapy given in the same fractionation schedule. Since clinical studies began in March, 1977, over 500 patients have been treated by fast neutrons. Almost all patients are now admitted to randomly controlled trials. In the head and neck trial conducted in collaboration with collegues in Amsterdam and Essen, 192 patients are available for analysis. Most patients had T3 lesions and about 50% had involved nodes. The cumulative regression rate at six months is similar after neutrons and photons (75%). Later recurrence rates (36%) are also similar. The early radiation morbidity is similar in both groups, but the late reactions are greater after neutrons (15%) than photons (6%). Overall survival is better after photon therapy. A trial of patients with glioblastoma has also shown a better survival after photon therapy. Neutron therapy was associated with demyelinization in three of 18 patients. Patients with transitional cell cancer of the bladder have also been the subject of study. Local tumor control was similar (53%) after neutrons and photons. Late radiation morbidity was much greater after neutrons (20%), compared with photons (2%). In a trial of advanced carcinoma of the rectum, the local tumor control was also similar after neutrons and photons (30%), but morbidity was greater after neutrons. Soft tissue sarcomas have shown response rates (37%) that may be expected after photon therapy. Salivary gland tumors have shown a similar experience, although slow growing tumors such as adenoid cystic carcinoma may respond better to neutrons

  13. Structural elements for fast-neutron reactors

    International Nuclear Information System (INIS)

    Blin, J.C.; Sainfort, Gerard; Silvent, Alain; Silvestres, Georges.

    1974-01-01

    These elements are characterized in that they are obtained from a nickel-alloy and at least a material M, selected from the group comprising iron and silicon, in proportions, by weight, such that irradiation by fast neutrons leads to the generation of Ni 3 -M with no noticeable swelling of said elements. This can be applied to fuel assembly cladding [fr

  14. Microdosimetry of intermediate energy neutrons in fast neutron fields

    International Nuclear Information System (INIS)

    Saion, E.B.; Watt, D.E.

    1988-01-01

    A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)

  15. Personal fast neutrons dosimetry using radiophotoluminescent glass

    International Nuclear Information System (INIS)

    Salem, Y. O.; Nachab, A.; Nourreddine, A.; Roy, C.

    2013-06-01

    In a previous paper we described a new ambient RPL dosimeter that detects fast neutrons in a mixed n-γ field via (n, p) reactions in a polyethylene converter. In the present study, a personal dosimeter is introduced to enable evaluating the individual dose equivalent H p (10) taking into account the albedo. A calibration factor for estimating H p (10) has been determined from the diminishing angular response as the angle of neutron incidence increases to 60 deg from the normal. MCNPX simulations for 241 Am-Be and 252 Cf neutrons, together with a series of monoenergetic neutron beams from 0.144 to 5 MeV, have been used to characterize the dosimeter response, which agrees well with the experimental 241 Am-Be response. (authors)

  16. Nuclear spectroscopy using the neutron capture reaction

    International Nuclear Information System (INIS)

    Egidy, T.

    1982-01-01

    Experimental methods using neutron spectroscopy as a means to study the nucleus structure are described. Since reactions of neutron capture (n, γ) are non-selective, they permit to study the nature of excitation (monoparticle and collective) of nuclear levels, the nature of vibrational excitations, to check the connection between shell model and liquid drop model etc. In many cases (n, γ) reactions are the only way to check the forecast of nuclear models. Advantages of (n, γ) spectroscopy, possessing a high precision of measurement and high sensitivity, are underlined. Using neutron spectroscopy on facilities with a high density of neutron flux the structures of energy levels of a large group of nuclei are studied. In different laboratories complete schemes of energy levels of nuclei are obtained, a great number of new levels are found, the evergy level densities are determined, multipolarities of γ-transitions, spins, level parities are considered. StrUctures of rotational bands of heavy deformed nuclei are studied. The study of the structure of high-spin states is possible only using the methods of (n, γ) spectroscopy Investigation results of the nuclei 24 Na, 114 Cd, 154 Eu, 155 Cd, 155 Sm, 233 Th are considered as examples. The most interesting aspects of the investigations using neutron spectroscopy are discUssed

  17. The Edinburgh experience of fast neutron therapy

    International Nuclear Information System (INIS)

    Duncan, W.; Arnott, S.J.; Orr, J.A.; Kerr, G.R.

    1982-01-01

    The Edinburgh experience is based on a d(15 + Be) neutron beam generated by a compact CS 30 Cyclotron. The facility has an iso-center treatment head providing 240 0 of rotation. The most important limitation of the beam is its poor penetrating quality. We have compared neutron therapy alone given in 20 daily fractions over four weeks with photon therapy given in the same fractionation schedule. Since clinical studies began in March, 1977, over 500 patients have been treated by fast neutrons. Almost all patients are now admitted to randomly controlled trials. In the head and neck trial conducted in collaboraton with colleagues in Amsterdam and Essen, 92 patients are available for analysis. Most patients had T3 lesions and about 50% had involved nodes. The cumulative regression rate at six months is similar after neutrons and photons (75%). Later recurrence rates (36%) are also similar. The early radiation morbidity is similar in both groups, but the late reactions are greater after neutrons (15%) than photons (6%). Overall survival is better after photon therapy. A trial of patients with glioblastoma has also shown a better survival after photon therapy. Neutron therapy was associated with demelinization in three of 18 patients. Patients with transitional cell cancer of the bladder have also been the subject of study. Local tumor control was similar (53%) after neutrons and photons. Late radiation morbidity was much greater after neutrons (20%), compared with photons (2%). In a trial of advanced carcinoma of the rectum, the local tumor control was also similar after neutrons and photons (30%), but morbidity was greater after neutrons. Soft tissue sarcomas have shown response rates (37%) that may be expected after photon therapy

  18. Energy dependence of fast neutron dosimetry using electrochemical etching

    International Nuclear Information System (INIS)

    Su, S.J.; Morgan, K.Z.

    1978-01-01

    Registration of fast-neutron induced recoil tracks by the electrochemical etching technique as applied to sensitive Lexan polycarbonate foils provides a simple and inexpensive means of fast neutron personnel dosimetry. The sensitivity (tracks/neutron) of recoil particle registration is given as a function of neutron energy. Neutrons of 7 Li (p,n) 7 Be, 3 T (d,n) 4 He and 9 B, respectively. Results are compared with other studies using other neutron sources and conventional etching method

  19. Fast neutron activation analysis by means of low voltage neutron generator

    Directory of Open Access Journals (Sweden)

    M.E. Medhat

    Full Text Available A description of D-T neutron generator (NG is presented. This machine can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. Procedure of neutron flux determination and efficiency calculation is described. Examples of testing some Egyptian natural cosmetics are given. Keywords: Neutron generator, Fast neutron activation analysis, Elemental analysis

  20. [Fast neutron cross section measurements

    International Nuclear Information System (INIS)

    1991-01-01

    In the 14 MeV Neutron Laboratory, we have continued the development of a facility that is now the only one of its kind in operation in the United States. We have refined the klystron bunching system described in last year's report to the point that 1.2 nanosecond pulses have been directly measured. We have tested the pulse shape discrimination capability of our primary NE 213 neutron detector. We have converted the RF sweeper section of the beamline to a frequency of 1 MHz to replace the function of the high voltage pulser described in last year's report which proved to be difficult to maintain and unreliable in its operation. We have also overcome several other significant experimental difficulties, including a major problem with a vacuum leak in the main accelerator column. We have completed additional testing to prove the remainder of the generation and measurement systems, but overcoming some of these experimental difficulties has delayed the start of actual data taking. We are now in a position to begin our first series of ring geometry elastic scattering measurements, and these will be underway before the end of the current contract year. As part of our longer term planning, we are continuing the conceptual analysis of several schemes to improve the intensity of our current pulsed beam. These include the provision of a duoplasmatron ion source and/or the provision of preacceleration bunching. Additional details are given later in this report. A series of measurements were carried out at the Tandem Dynamatron Facility involving the irradiation of a series of yttrium foils and the determination of activation cross sections using absolute counting techniques. The experimental work has been completed, and final analysis of the cross section data will be completed within several months

  1. Thermoluminescence fast neutron dosimetry by laser heating

    International Nuclear Information System (INIS)

    Mathur, V.K.; Brown, M.D.; Braeunlich, P.

    1984-01-01

    Heating rates in excess of 10 4 K.sec -1 have been achieved for thin layers of TL dosemeters by laser heating. The high heating rate improves the signal to noise ratio up to a factor of 10 3 . Thus sensitive thin film fast neutron dosemeters with negligible self-shielding have become a practical reality. Thin samples of CaSO 4 :Dy have been investigated for their response to fast neutrons from a Pu-Be source and a 14.6 MeV neutron generator by using a hydrogenous radiator. A 15 watt CO 2 laser was focussed on the thin TLD layer to a spot size of less than 1 mm to heat it. An exposure of a few tens of milliseconds was sufficient to obtain a TLD curve, which was displayed and processed by a wave form digitiser. The laser spot could be scanned over the TLD sample by a x-y positioner and a large number of observations were obtained on each sample. Preliminary results show that it is possible to obtain a figure of merit of approx. 5% in a mixed n, γ field. A practical design for a fast neutron dosemeter is proposed. (author)

  2. A study of television imaging system for fast neutron radiography

    International Nuclear Information System (INIS)

    Yoshii, Koji

    1992-01-01

    The neutron radiography with fast neutron beam is a very useful imaging technique for thicker objects, especially those composed of hydrogen-rich materials which are sometimes difficult to image by thermal neutron radiography. The fast neutron radiography has not been studied so much as the thermal neutron radiography. The fast neutron radiography has been studied at the fast neutron source reactor 'Yayoi' of the University of Tokyo built in Tokai-mura. The average neutron energy of the Yayoi is about 1 MeV, and the peak neutron flux at the core center is 0.8 x 10 12 at the maximum operating power of 2 kW. In the experiment on fast neutron radiography, a CR39 nuclear track detector has been used successfully. But in the Yayoi radiography procedure, about 24 hours were required for obtaining an imaging result. To get a prompt imaging result and a real-time imaging result, it is necessary to develop a fast neutron television system, and in this paper, a new fast neutron TV system is proposed. The main difference is the converter material sensitive to fast neutrons. The study on the fast neutron TV system was carried out by using the Baby Cyclotron of Japan Steel Works, and the good images were realized. (K.I.)

  3. Fast neutron dosimetry in research reactors

    International Nuclear Information System (INIS)

    Eckert, R.

    1960-01-01

    This work chiefly concerns the measurement of fast neutron fluxes by means of threshold detectors. It is shown first that the cross sections to use for measurements by threshold detectors depend largely on the neutron spectrum, that is the position in which the measurement is performed. The spectrum is determined by calculation for several positions in the piles EL2 and EL3; from this can be deduced the cross-sections to be used for the measurements carried out in these positions. In the last part of the report, possible methods for the experimental determination of the spectrum are indicated. (author) [fr

  4. Scattering of fast neutrons from 103Rh

    International Nuclear Information System (INIS)

    Barnard, E.; Reitmann, D.

    1978-01-01

    The scattering of fast neutrons from 103 Rh was studied by means of (n, n), (n, n') and (n, n'γ) measurements at neutron energies up to 2 MeV. More than fifty unknown γ-transitions were identified and a level scheme established which includes fifteen unreported excited states. Branching ratios, spins and parities for these levels were deduced, as well as the effective activation cross sections for the 103 Rh(n, n')sup(103m)Rh reaction. The results are compared with existing data and with calculations based on the optical and statistical models. (Auth.)

  5. A system for fast neutron radiography

    International Nuclear Information System (INIS)

    Klann, R.T.

    1997-01-01

    A system has been designed and a neutron generator installed to perform fast neutron radiography. With this system, objects as small as a coin and as large as a 19 liter container have been radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3 x 10[sup 10] neutrons/second with an average energy of 14. 5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available light-tight cassettes. The cassettes have been modified to include a thin sheet of plastic to produce protons from the neutron beam through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9 x 10[sup 7] n/cm[sup 2] to 3.8 x 10[sup 8] n/cm[sup 2] depending on the type of screen and film. The optimum source-to-film distance was found to be 150 cm. At this distance, the geometric unsharpness was determined to be approximately 2.2-2.3 mm and the smallest hole that could be resolved in a 1.25 cm thick sample had a diameter of 0.079 cm

  6. High resolution neutron spectroscopy for helium isotopes

    International Nuclear Information System (INIS)

    Abdel-Wahab, M.S.; Klages, H.O.; Schmalz, G.; Haesner, B.H.; Kecskemeti, J.; Schwarz, P.; Wilczynski, J.

    1992-01-01

    A high resolution fast neutron time-of-flight spectrometer is described, neutron time-of-flight spectra are taken using a specially designed TDC in connection to an on-line computer. The high time-of-flight resolution of 5 ps/m enabled the study of the total cross section of 4 He for neutrons near the 3/2 + resonance in the 5 He nucleus. The resonance parameters were determined by a single level Breit-Winger fit to the data. (orig.)

  7. Fission-neutrons source with fast neutron-emission timing

    Energy Technology Data Exchange (ETDEWEB)

    Rusev, G., E-mail: rusev@lanl.gov; Baramsai, B.; Bond, E.M.; Jandel, M.

    2016-05-01

    A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of {sup 252}Cf. The time is provided by registering the fission fragments in a layer of a thin scintillation film with a signal rise time of 1 ns. The scintillation light output is measured by two silicon photomultipliers with rise time of 0.5 ns. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements using it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  8. Fast and epithermal neutron radiography using neutron irradiator

    International Nuclear Information System (INIS)

    Oliveira, Karol A.M. de; Crispim, Verginia R.; Ferreira, Francisco J.O.

    2013-01-01

    The neutron radiography technique (NR) with neutrons in the energy range fast to epithermal is a powerful tool used in no-destructive inspection of bulky objects of diverse materials, including those rich in hydrogen, oxygen, nitrogen ad carbon. Thus, it can be used to identify, inclusions, voids and thickness differences in materials such as explosive artifacts and narcotics. Aiming at using NR with fast and epithermal neutrons, an Irradiator was constructed by: a 241 Am-Be source, with 5 Ci activity, a collimator with adjustable collimation rate, L/D; and a shield device composed by plates of borated paraffin and iron. The test specimens chosen were a Beam Purity Indicator (BPI) and an Indicator of Visual Resolution (IVR). The neutron radiography images obtained had a resolution of 444.4 μm and 363.6 μm respectively when registered in: 1) the sheet of the nuclear track solid detector, CR-39 type, through X (n,p) Y nuclear reaction; and 2) Kodak Industrex M radiographic film plate in close contact with a boron converter screen, both stored in a Kodak radiographic cassette. (author)

  9. Development of Optical Fiber Detector for Measurement of Fast Neutron

    International Nuclear Information System (INIS)

    YAGI, Takahiro; KAWAGUCHI, Shinichi; MISAWA, Tsuyoshi; PYEON, Cheol Ho; UNESAKI, Hironobu; SHIROYA, Seiji; OKAJIMA, Shigeaki; TANI, Kazuhiro

    2008-01-01

    Measurement of fast neutron flux is important for investigation of characteristic of fast reactors. In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO 2 as converter material because 232 Th makes fission reaction with fast neutrons. The place where 232 Th can be used is limited by regulations because 232 Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without 232 Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons. (authors)

  10. Fast neutron damage of silicon pin photodiodes

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.; Skoczen, A.

    1990-01-01

    A Hamamatsu Photonics photodiode S1723 was tested with respect to the fast neutron radiation. The device was irradiated with neutrons of energies in the range of 0.5 MeV to 12 MeV from a Po-Be source. The irradiation was performed in several steps starting from the relatively low fluence of 2.5 x 10 10 n x cm -2 . The following characteristics were measured: leakage current vs bias voltage, capacitance vs bias voltage and vs frequency, noise vs time constant of a quasigaussian shaper and spectral density of noise. Significant changes of the leakage current and of the noise were observed at the fluence of neutrons as low as 2.5 x 10 10 n x cm -2 . 8 figs., 3 tabs., 15 refs. (author)

  11. Overlapping β decay and resonance neutron spectroscopy

    International Nuclear Information System (INIS)

    Raman, S.; Fogelberg, B.

    1984-01-01

    By carrying out a detailed study of 87 Kr levels, we have shown that delayed neutron spectroscopy can be a viable method for studying individual levels and that a broad resonance-like structure is present in the β-strength distribution. 12 refs., 1 fig

  12. Dosimetry and biological effects of fast neutrons

    International Nuclear Information System (INIS)

    Zoetelief, J.

    1981-01-01

    This thesis contains studies on two types of cellular damage: cell reproductive death and chromosome aberrations induced by irradiation with X rays, gamma rays and fast neutrons of different energies. A prerequisite for the performance of radiobiological experiments is the determination of the absorbed dose with a sufficient degree of accuracy and precision. Basic concepts of energy deposition by ionizing radiation and practical aspects of neutron dosimetry for biomedical purposes are discussed. Information on the relative neutron sensitivity of GM counters and on the effective point of measurement of ionization chambers for dosimetry of neutron and photon beams under free-in-air conditions and inside phantoms which are used to simulate the biological objects is presented. Different methods for neutron dosimetry are compared and the experimental techniques used for the investigations of cell reproductive death and chromosome aberrations induced by ionizing radiation of different qualities are presented. Dose-effect relations for induction cell inactivation and chromsome aberrations in three cultured cell lines for different radiation qualities are presented. (Auth.)

  13. Direct fast neutron detection: A status report

    International Nuclear Information System (INIS)

    Peurrung, A.J.; Hansen, R.R.; Craig, R.A.; Hensley, W.K.; Hubbard, C.W.; Keller, P.E.; Reeder, P.L.; Sunberg, D.S.

    1997-12-01

    This report describes the status of efforts to develop direct fast-neutron detection via proton recoil within plastic scintillator. Since recording proton recoil events is of little practical use without a means to discriminate effectively against gamma-ray interactions, the present effort is concentrated on demonstrating a method that distinguishes between pulse types. The proposed method exploits the different pulse shapes that are to be expected primarily on the basis of the slower speed of the recoiling fission neutrons. Should this effort ultimately prove successful, the resulting novel technology will have the potential to significantly lower cost and increase capability for a number of critical neutron-detection applications. Considerable progress has been made toward a clear and compelling demonstration of this new technique. An exhaustive theoretical and numerical investigation of the method has been completed. The authors have been able to better understand the laboratory results and estimate the performance that could ultimately be achieved using the proposed technique. They have assessed the performance of a number of different algorithms for discriminating between neutron and gamma ray events. The results of this assessment will be critical when the construction of low-cost, field-portable neutron detectors becomes necessary. Finally, a laboratory effort to realize effective discrimination is well underway and has resulted in partial success

  14. Fast-neutron, coded-aperture imager

    Science.gov (United States)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  15. Bertram Brockhouse, the Triple-axis Spectrometer, and Neutron Spectroscopy

    Science.gov (United States)

    Neutron Spectroscopy Resources with Additional Information Bertram Brockhouse Courtesy of McMaster was awarded the 1994 Nobel Prize in Physics for his development of neutron spectroscopy. Bert Physicist, Dies, The New York Times, October 16, 2003 1994: Development of Neutron Spectroscopy, Brookhaven

  16. Neutron and X-ray Spectroscopy

    CERN Document Server

    Hippert, Françoise; Hodeau, Jean Louis; Lelièvre-Berna, Eddy; Regnard, Jean-René

    2006-01-01

    Neutron and X-Ray Spectroscopy delivers an up-to-date account of the principles and practice of inelastic and spectroscopic methods available at neutron and synchrotron sources, including recent developments. The chapters are based on a course of lectures and practicals (the HERCULES course) delivered to young scientists who require these methods in their professional careers. Each chapter, written by a leading specialist in the field, introduces the basic concepts of the technique and provides an overview of recent work. This volume, which focuses on spectroscopic techniques in synchrotron radiation and inelastic neutron scattering, will be a primary source of information for physicists, chemists and materials scientists who wish to acquire a basic understanding of these techniques and to discover the possibilities offered by them. Emphasizing the complementarity of the neutron and X-ray methods, this tutorial will also be invaluable to scientists already working in neighboring fields who seek to extend thei...

  17. Fast-neutron, coded-aperture imager

    International Nuclear Information System (INIS)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-01-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  18. Fast-neutron, coded-aperture imager

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F., E-mail: bernard.phlips@nrl.navy.mil; Hutcheson, Anthony L., E-mail: anthony.hutcheson@nrl.navy.mil; Wulf, Eric A., E-mail: eric.wulf@nrl.navy.mil

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  19. Induced mutation breeding by fast neutron

    International Nuclear Information System (INIS)

    Chen Zhengba; You Risheng

    1988-09-01

    The high-yield and long-grain new variety 'Zhongtie 31' was developed through five generations after irradiation of the rice variety 'Tieqiu 15' dried seeds by 14 MeV fast neutrons with a fluence of (1.33 ∼ 3.33) x 10 11 neutrons cm -2 . It matured earlier 3 to 5 days, the plant is higher 10 cm, bigger ear, more grain than its original variety 'tieqiu 15', and the yield increased by 19.2% to 30.7%. The source of new variety 'Zhongtie 31' was proved by the isoenzyme genetics. In field test, it increased by 7% to 10% as compared with high-yield variety 'Guichao No.2' and the hybrid rive 'Shanyou No.2', and is more palatable. The new variety was initiated by irradiation mutagensis routine rice, its well-grown and bumper-yield performances may be compared favourably with hybrid rice variety. In July 1986, the new variety 'Zhongtie 31' was obtained by inducing mutation with fast neutron. The same year, the planted area of 'Zhongtie 31' has achieved upto 250 thousand mu (1.67 x 10 8 cm 2 )

  20. Core of a fast neutron nuclear reactor

    International Nuclear Information System (INIS)

    Giacometti, Christian; Mougniot, J.-C.; Ravier, Jean.

    1974-01-01

    The fast neutron nuclear reactor described includes an internal area in fissile material completely enclosed in an area of fertile material forming the outside blanket. The internal fissile area is provided with housings exclusively filled with fertile material forming one or more inside blankets. In this core the internal blankets are shaped like rings vertically separating superimposed rings of fissile material. The blanket of material nearest to the periphery is circumscribed externally by a contour having an indented shape on its straight section so as to increase the contact area between this blanket and the external blanket [fr

  1. Fast-neutron solid-state dosimeter

    International Nuclear Information System (INIS)

    Kecker, K.H.; Haywood, F.F.; Perdue, P.T.; Thorngate, J.H.

    1975-01-01

    This patent relates to an improved fast-neutron solid-state dosimeter that does not require separation of materials before it can be read out, that utilizes materials that do not melt or otherwise degrade at about 300 0 C readout temperature, that provides a more efficient dosimeter, and that can be reused. The dosimeters are fabricated by intimately mixing a TL material, such as CaSO 4 :Dy, with a powdered polyphenyl, such as p-sexiphenyl, and hot-pressing the mixture to form pellets, followed by out-gassing in a vacuum furnace at 150 0 C prior to first use dosimeters

  2. Fast neutron spectrometer with pulse shape discrimination

    International Nuclear Information System (INIS)

    Verbitsky, S.S.

    1978-01-01

    A fast neutron spectrometer with a stilbene single crystal designed to operate at high pulsed count rate has been described. Making use of identification and rejection of events, accompanied by pile-up, allowed to increase permissible count rates by an order of magnitude. The results of energy dependence of signal amplitude and shape relative anisotropy in stilbene in the range 4-10 and 2-8 MeV respectively have been presented. Taking into account anisotropy of the detector-scintillation properties allowed to improve particle discrimination. (Auth.)

  3. Neutron resonance spectroscopy at n-TOF at CERN

    International Nuclear Information System (INIS)

    Gunsing, F.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapic, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Kappeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krticka, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martinez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P.M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M.T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J.L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M.C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

    2008-01-01

    Neutron resonance spectroscopy plays an important role in the investigation of neutron induced reaction cross sections and nuclear structure in the MeV excitation range. Neutron time-of-flight facilities are the most used installations to explore neutron resonances. In this paper we describe the basic features of neutron resonance spectroscopy together with recent results from the time-of-flight facility n-TOF at CERN. (authors)

  4. Reprocessing of fast neutron reactor fuel

    International Nuclear Information System (INIS)

    Bourgeois, M.

    1981-05-01

    A PUREX process specially adapted to fast neutron reactor fuels is employed. The results obtained indicate that the aqueous process can be applied to this type of fuel: almost 10 years operation at the AT 1 plant which processes fuel from RAPSODIE; the good results obtained at the MARCOULE pilot plant on large batches of reference fuels. The CEA is continuing its work to transfer this technology onto an industrial scale. Industrial prototypes and the launching of the TOR (traitement d'oxydes rapides) project will facilitate this transfer. In 1984, it is expected that fast fuels will be able to be processed on a significant scale and that supplementary R and D facilities will be available [fr

  5. Fast-neutron coincidence-counter manual

    International Nuclear Information System (INIS)

    Ensslin, N.; Atwell, T.L.; Lee, D.M.; Erkkila, B.; Marshall, R.S.; Morgan, A.; Shonrock, C.; Tippens, B.; Van Lyssel, T.

    1982-03-01

    The fast neutron counter (FNC) described in this report is a computer-based assay system employing fast-pulse counting instrumentation. It is installed below a glove box in the metal electrorefining area of the Los Alamos National Laboratory Plutonium Processing Facility. The instrument was designed to assay plutonium salts and residues from this process and to verify the mass of electrorefined metal. Los Alamos National Laboratory Groups Q-1, Q-3, and CMB-11 carried out a joint test and evaluation plan of this instrument between May 1978 and May 1979. The results of that evaluation, a description of the FNC, and operating instructions for further use are given in this report

  6. Does fast-neutron radiotherapy merely reduce the radiation dose

    International Nuclear Information System (INIS)

    Ando, Koichi

    1984-01-01

    We examined whether fast-neutron radiotherapy is superior to low-LET radiotherpy by comparing the relationship between cell survival and tumor control probabilities after exposure of tumor-bearing (species) to the two modalities. Analysis based on TCD 50 assay and lung colony assay indicated that single dose of fast neutron achieved animal cures at higher survival rates than other radiation modalities including single and fractionated γ-ray doses, fractionated doses of fast neutron, and the mixed-beam scheme with a sequence of N-γ-γ-γ-N. We conclude that fast-neutron radiotherapy cured animal tumors with lower cell killing rates other radiation modalities. (author)

  7. [Fast neutron cross section measurements]: Progress report

    International Nuclear Information System (INIS)

    1988-01-01

    As projected in our previous proposal, the past year on the cross section project at the University of Michigan has been one primarily of construction and assembly of our 14 MeV pulsed Neutron Facility. All the components of the system have now been either purchased or fabricated in our shop facilities and have been assembled in their final configuration. We are now in the process of testing the rf components that have been designed to deliver voltage to both the pulser and buncher stages. We expect that the system will be operational by the end of the current contract year. We have also accomplished the design and construction of several other major pieces of equipment that are needed to begin fast neutron time-of-flight measurements. These include the primary proton recoil detector, and a californium fission chamber needed in the efficiency calibration of the primary detector. We have also added considerable concrete shielding designed to lower the neutron background in the experimental area. 10 figs., 5 tabs

  8. Uncertainty Assessments in Fast Neutron Activation Analysis

    International Nuclear Information System (INIS)

    W. D. James; R. Zeisler

    2000-01-01

    Fast neutron activation analysis (FNAA) carried out with the use of small accelerator-based neutron generators is routinely used for major/minor element determinations in industry, mineral and petroleum exploration, and to some extent in research. While the method shares many of the operational procedures and therefore errors inherent to conventional thermal neutron activation analysis, its unique implementation gives rise to additional specific concerns that can result in errors or increased uncertainties of measured quantities. The authors were involved in a recent effort to evaluate irreversible incorporation of oxygen into a standard reference material (SRM) by direct measurement of oxygen by FNAA. That project required determination of oxygen in bottles of the SRM stored in varying environmental conditions and a comparison of the results. We recognized the need to accurately describe the total uncertainty of the measurements to accurately characterize any differences in the resulting average concentrations. It is our intent here to discuss the breadth of potential parameters that have the potential to contribute to the random and nonrandom errors of the method and provide estimates of the magnitude of uncertainty introduced. In addition, we will discuss the steps taken in this recent FNAA project to control quality, assess the uncertainty of the measurements, and evaluate results based on the statistical reproducibility

  9. Material classification by fast neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Buffler, A. E-mail: abuffler@physci.uct.ac.za; Brooks, F.D. E-mail: brooks@physci.uct.ac.za; Allie, M.S.; Bharuth-Ram, K.; Nchodu, M.R

    2001-02-01

    The scattering of a beam of fast monoenergetic neutrons is used to determine elemental compositions of bulk samples (0.2-0.8 kg) of materials composed from one or more of the elements H, C, N, O, Al, S, Fe and Pb. Scattered neutrons are detected by liquid scintillators placed at forward and at backward angles. Different elements are identified by their characteristic scattering signatures derived either from a combination of time-of-flight and pulse height measurements, or from pulse height measurements alone. Scattering signatures measured for multi-element samples are analysed to determine atom fractions for H, C, N, O and other elements in the sample. Atom fractions determined from scattering signatures are insensitive to neutron interactions in material surrounding the scattering sample, provided the amount of material is not excessive. The atom fraction data are used to classify scattering material into categories including 'explosives', 'illicit drugs' and 'other materials' for the purpose of contraband detection.

  10. Silicon Diode Dosimeter for Fast Neutrons

    International Nuclear Information System (INIS)

    Svansson, L.; Widell, C.O.; Swedberg, P.; Wik, M.

    1968-11-01

    The change of the current-voltage characteristics of a small silicon diode is used as a measure of fast neutron dose in the Fast Neutron Dosimeter 5422. This change is permanent and therefore it is possible to integrate doses over a long period of time. Doses from some rad up to 1000 rad can be measured and the information stored is not destroyed during readout. Considerable research work in this field has previously been carried out by the Swedish Institute for National Defence in collaboration with the Institute of Semiconductor Research Stockholm. The present investigation has been made in order to establish the possibilities of the dosimeter for practical applications and to study the variations of important parameters as a function of the production process. In particular the following parameters have been studied: - dose sensitivity, - energy dependence; - fading effect; - temperature influence; - maximum measurable dose. In general one might conclude that the dosimeter 5422 well fulfills requirements usually specified for a dosimeter for field service. Temperature influence and fading effect are of little practical importance within the recommended range of measurement

  11. Silicon Diode Dosimeter for Fast Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Svansson, L; Widell, C O; Swedberg, P [The Inst. of Semiconductor Researc h, Stockholm (Sweden); Wik, M [The Swedish Institute for National Defence, Sun dbyberg (Sweden)

    1968-11-15

    The change of the current-voltage characteristics of a small silicon diode is used as a measure of fast neutron dose in the Fast Neutron Dosimeter 5422. This change is permanent and therefore it is possible to integrate doses over a long period of time. Doses from some rad up to 1000 rad can be measured and the information stored is not destroyed during readout. Considerable research work in this field has previously been carried out by the Swedish Institute for National Defence in collaboration with the Institute of Semiconductor Research Stockholm. The present investigation has been made in order to establish the possibilities of the dosimeter for practical applications and to study the variations of important parameters as a function of the production process. In particular the following parameters have been studied: - dose sensitivity, - energy dependence; - fading effect; - temperature influence; - maximum measurable dose. In general one might conclude that the dosimeter 5422 well fulfills requirements usually specified for a dosimeter for field service. Temperature influence and fading effect are of little practical importance within the recommended range of measurement.

  12. MPACT Fast Neutron Multiplicity System Prototype Development

    Energy Technology Data Exchange (ETDEWEB)

    D.L. Chichester; S.A. Pozzi; J.L. Dolan; M.T. Kinlaw; S.J. Thompson; A.C. Kaplan; M. Flaska; A. Enqvist; J.T. Johnson; S.M. Watson

    2013-09-01

    This document serves as both an FY2103 End-of-Year and End-of-Project report on efforts that resulted in the design of a prototype fast neutron multiplicity counter leveraged upon the findings of previous project efforts. The prototype design includes 32 liquid scintillator detectors with cubic volumes 7.62 cm in dimension configured into 4 stacked rings of 8 detectors. Detector signal collection for the system is handled with a pair of Struck Innovative Systeme 16-channel digitizers controlled by in-house developed software with built-in multiplicity analysis algorithms. Initial testing and familiarization of the currently obtained prototype components is underway, however full prototype construction is required for further optimization. Monte Carlo models of the prototype system were performed to estimate die-away and efficiency values. Analysis of these models resulted in the development of a software package capable of determining the effects of nearest-neighbor rejection methods for elimination of detector cross talk. A parameter study was performed using previously developed analytical methods for the estimation of assay mass variance for use as a figure-of-merit for system performance. A software package was developed to automate these calculations and ensure accuracy. The results of the parameter study show that the prototype fast neutron multiplicity counter design is very nearly optimized under the restraints of the parameter space.

  13. Development and Characterization of a High Sensitivity Segmented Fast Neutron Spectrometer (FaNS-2).

    Science.gov (United States)

    Langford, T J; Beise, E J; Breuer, H; Heimbach, C R; Ji, G; Nico, J S

    2016-01-01

    We present the development of a segmented fast neutron spectrometer (FaNS-2) based upon plastic scintillator and 3 He proportional counters. It was designed to measure both the flux and spectrum of fast neutrons in the energy range of few MeV to 1 GeV. FaNS-2 utilizes capture-gated spectroscopy to identify neutron events and reject backgrounds. Neutrons deposit energy in the plastic scintillator before capturing on a 3 He nucleus in the proportional counters. Segmentation improves neutron energy reconstruction while the large volume of scintillator increases sensitivity to low neutron fluxes. A main goal of its design is to study comparatively low neutron fluxes, such as cosmogenic neutrons at the Earth's surface, in an underground environment, or from low-activity neutron sources. In this paper, we present details of its design and construction as well as its characterization with a calibrated 252 Cf source and monoenergetic neutron fields of 2.5 MeV and 14 MeV. Detected monoenergetic neutron spectra are unfolded using a Singular Value Decomposition method, demonstrating a 5% energy resolution at 14 MeV. Finally, we discuss plans for measuring the surface and underground cosmogenic neutron spectra with FaNS-2.

  14. The effect of the neutron spectra unfolding method on the fast neutron dose determination

    International Nuclear Information System (INIS)

    Marinkovic, P.; Zavaljevski, N.

    1992-01-01

    Based on Shanon's information theory, a new unfolding method which gives non-negative spectrum values and a relatively low variance, is proposed, and a numerical code suitable for application in fast neutron spectroscopy based on proton recoil is developed. The principles of maximum entropy and maximum likelihood are jointly applied. According to the principle of maximum likelihood, the distribution functions around the mean value of the counts in the MCA channels are assumed to be Gaussians. The Lagrange parameter method is applied in the search for an optimal non-negative solution. The nonlinear system of equations is solved using the gradient and Newton iterative algorithms. (orig.)

  15. The effect of the neutron spectra unfolding method on the fast neutron dose determination

    International Nuclear Information System (INIS)

    Marinkovic, P.; Avdic, S.; Pesic, M.; Zavaljevski, N

    1992-09-01

    Based on Shanon's information theory, a new unfolding method which gives non-negative spectrum values and a relatively low variance, is proposed, and a numerical code suitable for application in fast neutron spectroscopy based on proton recoil is developed. The principles of maximum entropy and maximum likelihood are jointly applied. According to the principle of maximum likelihood, the distribution functions around the mean value of the counts in the MCA channels are assumed to be Gaussians. The Lagrange parameter method is applied in the search for an optimal non-negative solution. The nonlinear system of equations is solved using the gradient and Newton iterative algorithms. (author)

  16. Calculation of the neutron parameters of fast thermal reactor

    International Nuclear Information System (INIS)

    Kukuleanu, V.; Mocioiu, D.; Drutse, E.; Konstantinesku, E.

    1975-01-01

    The system of neutron calculation for fast reactors is given. This system was used for estimation of physical parameters of fast thermal reactors investigated. The results obtained and different specific problems of the reactors of this type are described. (author)

  17. Transmutation of Americium in Fast Neutron Facilities

    International Nuclear Information System (INIS)

    Zhang, Youpeng

    2011-01-01

    In this thesis, the feasibility to use a medium sized sodium cooled fast reactor fully loaded with MOX fuel for efficient transmutation of americium is investigated by simulating the safety performance of a BN600-type fast reactor loaded with different fractions of americium in the fuel, using the safety parameters obtained with the SERPENT Monte Carlo code. The focus is on americium mainly due to its long-term contribution to the radiotoxicity of spent nuclear fuel and its deterioration on core's safety parameters. Applying the SAS4A/SASSYS transient analysis code, it is demonstrated that the power rating needs to be reduced by 6% for each percent additional americium introduction into the reference MOX fuel, maintaining 100 K margin to fuel melting, which is the most limiting failure mechanism. Safety analysis of a new Accelerator Driven System design with a smaller pin pitch-to-diameter ratio comparing to the reference EFIT-400 design, aiming at improving neutron source efficiency, was also performed by simulating performance for unprotected loss of flow, unprotected transient overpower, and protected loss-of-heat-sink transients, using neutronic parameters obtained from MCNP calculations. Thanks to the introduction of the austenitic 15/15Ti stainless steel with enhanced creep rupture resistance and acceptable irradiation swelling rate, the suggested ADS design loaded with nitride fuel and cooled by lead-bismuth eutectic could survive the full set of transients, preserving a margin of 130 K to cladding rupture during the most limiting transient. The thesis concludes that efficient transmutation of americium in a medium sized sodium cooled fast reactor loaded with MOX fuel is possible but leads to a severe power penalty. Instead, preserving transmutation rates of minor actinides up to 42 kg/TWh th , the suggested ADS design with enhanced proton source efficiency appears like a better option for americium transmutation

  18. Boron neutron capture therapy (BNCT) using fast neutrons: Effects in two human tumor cell lines

    International Nuclear Information System (INIS)

    Sauerwein, W.; Ziegler, W.; Szypniewski, H.; Streffer, C.

    1990-01-01

    The results demonstrate that the effect of fast neutrons on cell survival in cell culture can be enhanced by boron neutron capture reaction. Even with lower enhancement ratios, the concept of NCT assisted fast neutron therapy may successfully be applied for tumor treatment with the Essen cyclotron. (orig.)

  19. Activation measurements for fast neutrons. Part E. Evaluation of fast neutron 63Ni transmission factors

    International Nuclear Information System (INIS)

    Egbert, Stephen D.

    2005-01-01

    The 63 Ni measurements for fast neutrons in copper samples are compared to the calculated free-in-air 63 Ni neutron activation given in Chapter 3 by use of transmission factors. Transmission factors were calculated to account for the modification of the fluence and activation at each sample's in situ location. For the purposes of this discussion, the transmission factor (TF) is defined as the ratio of the in situ sample activation divided by the untilted free-in-air (FIA) activation at a height of 1 m above ground at the same ground range. Examples of the application of TF's will be provided in this section. (author)

  20. Generation of laser-induced fast neutron and its application

    International Nuclear Information System (INIS)

    Cha, Hyung Ki; Lee, S.; Kwon, D.; Nam, S.; Park, S.; Rhee, Y.; Jung, Y.; Lee, K.; Cha, Y.; Kwon, S.; Lim, C.; Han, J.; Park, S.; Chung, C.

    2012-04-01

    The supply of high-efficiency neutron source is still problematic even though a fast neutron source is being accepted increasingly for industrial applications. Radioisotopes and a neutron tube are typically being used, but their neutron flux, lifetime, and price are the limiting factors for more diverse applications. As ultra high power, short pulse laser technologies have been developed, a neutron source generated via laser induced nuclear reaction comes to the fore. The laser induced neutron source has a high peak flux in comparison to the traditional neutron source and is like a point source with its diameter less than 1 mm. These properties can be utilized effectively for the analysis of pulsed fast neutron activation or the studies of a fast neutron material damage and/or recover. The purpose of R and D here is to develop a robust neutron source with a yield of 107 neutrons/s during 1st R and D stage ('07 ∼ '09) and to construct a stable laser neutron source in longer operation and to demonstrate its usefulness for a neutron activation analysis of explosive materials and a neutron impact analysis of crystalline in the second R and D stage ('10 ∼ '11)

  1. Feasibility of the Precise Energy Calibration for Fast Neutron Spectrometers

    Science.gov (United States)

    Gaganov, V. V.; Usenko, P. L.; Kryzhanovskaja, M. A.

    2017-12-01

    Computational studies aimed at improving the accuracy of measurements performed using neutron generators with a tritium target were performed. A measurement design yielding an extremely narrow peak in the energy spectrum of DT neutrons was found. The presence of such a peak establishes the conditions for precise energy calibration of fast-neutron spectrometers.

  2. Recent advances in fast neutron radiography for cargo inspection

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

  3. Challenges in neutron spin echo spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, C., E-mail: c.pappas@tudelft.n [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Lelievre-Berna, E.; Falus, P.; Farago, B. [Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Bentley, P. [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Moskvin, E. [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); PNPI, 188300 Gatchina, Leningrad District (Russian Federation); Krist, Th. [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); Grigoriev, S. [PNPI, 188300 Gatchina, Leningrad District (Russian Federation)

    2009-09-01

    With the new brilliant neutron sources and the developments of novel optical elements, neutron spin echo (NSE) spectroscopy evolves to tackle new problems and scientific fields. The new developments pave the way to complex experimental set-ups such as the intensity modulated variant of NSE (IMNSE), a powerful technique which was introduced some 20 years ago but found limited use up to now. With the new compact supermirror or He{sup 3} polarizers IMNSE becomes attractive for a broad range of applications in magnetism, soft matter and biology. A novel development along this line is the polarimetric NSE technique, which combines IMNSE and the zero-field polarimeter Cryopad to access components of the scattered polarization that are transverse to the incoming polarization. Polarimetric NSE is the method of choice for studying chiral fluctuations, as illustrated by new results on the reference helimagnet MnSi.

  4. High-pressure cell for simultaneous dielectric and neutron spectroscopy

    Science.gov (United States)

    Sanz, Alejandro; Hansen, Henriette Wase; Jakobsen, Bo; Pedersen, Ib H.; Capaccioli, Simone; Adrjanowicz, Karolina; Paluch, Marian; Gonthier, Julien; Frick, Bernhard; Lelièvre-Berna, Eddy; Peters, Judith; Niss, Kristine

    2018-02-01

    In this article, we report on the design, manufacture, and testing of a high-pressure cell for simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different time scales, from kilo- to picoseconds, covering universal features such as the α relaxation and fast vibrations at the same time. The cell, constructed in cylindrical geometry, is made of a high-strength aluminum alloy and operates up to 500 MPa in a temperature range between roughly 2 and 320 K. In order to measure the scattered neutron intensity and the sample capacitance simultaneously, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data on dipropylene glycol, using both backscattering and time-of-flight instruments. We have carried out the experiments at different combinations of temperature and pressure in both the supercooled liquid and glassy state.

  5. Code system for fast reactor neutronics analysis

    International Nuclear Information System (INIS)

    Nakagawa, Masayuki; Abe, Junji; Sato, Wakaei.

    1983-04-01

    A code system for analysis of fast reactor neutronics has been developed for the purpose of handy use and error reduction. The JOINT code produces the input data file to be used in the neutronics calculation code and also prepares the cross section library file with an assigned format. The effective cross sections are saved in the PDS file with an unified format. At the present stage, this code system includes the following codes; SLAROM, ESELEM5, EXPANDA-G for the production of effective cross sections and CITATION-FBR, ANISN-JR, TWOTRAN2, PHENIX, 3DB, MORSE, CIPER and SNPERT. In the course of the development, some utility programs and service programs have been additionaly developed. These are used for access of PDS file, edit of the cross sections and graphic display. Included in this report are a description of input data format of the JOINT and other programs, and of the function of each subroutine and utility programs. The usage of PDS file is also explained. In Appendix A, the input formats are described for the revised version of the CIPER code. (author)

  6. Gamma-ray-spectroscopy following high-flux 14-MeV neutron activation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, R.E.

    1981-10-12

    The Rotating Target Neutron Source (RTNS-I), a high-intensity source of 14-MeV neutrons at the Lawrence Livermore National Laboratory (LLNL), has been used for applications in activation analysis, inertial-confinement-fusion diagnostic development, and fission decay-heat studies. The fast-neutron flux from the RTNS-I is at least 50 times the maximum fluxes available from typical neutron generators, making these applications possible. Facilities and procedures necessary for gamma-ray spectroscopy of samples irradiated at the RTNS-I were developed.

  7. Gamma-ray-spectroscopy following high-flux 14-MeV neutron activation

    International Nuclear Information System (INIS)

    Williams, R.E.

    1981-01-01

    The Rotating Target Neutron Source (RTNS-I), a high-intensity source of 14-MeV neutrons at the Lawrence Livermore National Laboratory (LLNL), has been used for applications in activation analysis, inertial-confinement-fusion diagnostic development, and fission decay-heat studies. The fast-neutron flux from the RTNS-I is at least 50 times the maximum fluxes available from typical neutron generators, making these applications possible. Facilities and procedures necessary for gamma-ray spectroscopy of samples irradiated at the RTNS-I were developed

  8. Metal ion protection of DNA to fast neutron irradiation

    International Nuclear Information System (INIS)

    Constantinescu, B.; Bugoi, R.; Radulescu, I.; Radu, L.

    1998-01-01

    time resolved spectroscopy measurements have clearly showed a variation of the chromatin-Pr bound percentage and conformational changes in fluorescent marker proximity, when the chromatin is irradiated with fast neutrons. This indicates chromatin DNA damage produced by irradiation. The damages have been reduced by the presence of protective factors, i.e., the metallic ions (Cs + and Al 3+ ). The single photon counting method proved to be more sensitive than the others in assessing chromatin DNA damage. This approach also clarifies the chromatin-Pr interaction mechanism. (authors)

  9. Japanese experience with clinical trials of fast neutrons

    International Nuclear Information System (INIS)

    Tsunemoto, H.; Arai, T.; Morita, S.; Ishikawa, T.; Aoki, Y.; Takada, N.; Kamata, S.

    1982-01-01

    Between November, 1975 and November, 1981, 825 patients were treated with 30 MeV (d-Be) neutrons at the National Institute of Radiological Sciences, Chiba. At the Institute of Medical Science, Tokyo, 302 patients were referred to the Radiation Therapy department and were treated with 16 MeV (d-Be) neutrons. The emphasis of these clinical trials with fast neutrons was placed on the estimation of the effect of fast neutrons for locally advanced cancers or radioresistant cancers, and on evaluation of the rate of complication of normal tissues following irradiation with fast neutrons. Results were evaluated for patients with previously untreated cancer; local control of the tumor was observed in 59.1%. Complications requiring medical care developed in only 32 patients. Late reaction of soft tissue seemed to be more severe than that observed with photon beams. The results also suggest that for carcinoma of the larynx, esophagus, uterine cervix, Pancoast's tumor of the lung and osteosarcoma, fast neutrons were considered to be effectively applied in this randomized clinical trial. For carcinoma of the larynx, a fast neutron boost was effectively delivered, although an interstitial implant was necessarily combined with fast neutrons for carcinoma of the tongue. The cumulative survival rate of the patients with carcinoma of the esophagus treated with fast neutrons of 26% compared to the survival rate of 10.5% obtained using photons. The results also indicate that local control and relief of the symptom related to Pancoast's tumor of the lung seemed to be better with neutrons than with photons. For patients suffering from osteosarcoma, the surgical procedures preserving the function of the leg and arm were studied according to the better local control rate of the tumor following fast neutron beam therapy

  10. An improved fast neutron radiography quantitative measurement method

    International Nuclear Information System (INIS)

    Matsubayashi, Masahito; Hibiki, Takashi; Mishima, Kaichiro; Yoshii, Koji; Okamoto, Koji

    2004-01-01

    The validity of a fast neutron radiography quantification method, the Σ-scaling method, which was originally proposed for thermal neutron radiography was examined with Monte Carlo calculations and experiments conducted at the YAYOI fast neutron source reactor. Water and copper were selected as comparative samples for a thermal neutron radiography case and a dense object, respectively. Although different characteristics on effective macroscopic cross-sections were implied by the simulation, the Σ-scaled experimental results with the fission neutron spectrum cross-sections were well fitted to the measurements for both the water and copper samples. This indicates that the Σ-scaling method could be successfully adopted for quantitative measurements in fast neutron radiography

  11. Television imaging system for fast neutron radiography using baby cyclotron

    International Nuclear Information System (INIS)

    Yoshii, Koji; Miya, Kenzo; Katoh, Norihiko.

    1993-01-01

    A television imaging system for fast neutron radiography (FNR-TV) developed using the fast neutron source reactor YAYOI was applied to the baby-cyclotron based fast neutron source to get images of thick objects quickly. In the system the same technique as a current television imaging system of thermal neutron radiography was applied, while the luminescent converter was used to detect fast neutrons. Using the CR39 track etch method it took about 7 h to get an image, while the FNR-TV only 20 s enough for taking the same object. However the FNR-TV imaging result of the simulation model of a large explosive device for the space launch vehicle of H-2 type was not so good as the image taken with the CR39 track etch method. The reason was that the luminescence intensity of the FNR-TV converter was a quarter of that in the YAYOI. (author)

  12. Neutron spectrum determination by activation method in fast neutron fields at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1994-01-01

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (author)

  13. Neutron spectrum determination by activation method in fast neutron fields at the RB reactors

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.S.; Pesic, M.P.; Antic, D.P.

    1994-01-01

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (authors). 7 refs., 3 tabs

  14. Generation of laser-induced fast neutron and its application

    International Nuclear Information System (INIS)

    Cha, Hyung Ki; Kwon, D. H.; Nam, S. M.

    2010-04-01

    The supply of high-efficiency neutron source is still problematic even though a fast neutron source is being accepted increasingly for industrial applications. Radioisotopes and a neutron tube are typically being used, but their neutron flux, lifetime, and price are the limiting factors for more diverse applications. As ultra high power, short pulse laser technologies have been developed, a neutron source generated via laser induced nuclear reaction comes to the fore. The laser induced neutron source has a high peak flux in comparison to the traditional neutron source and is like a point source with its diameter less than 1 mm. These properties can be utilized effectively for the analysis of pulsed fast neutron activation or the studies of a fast neutron material damage and/or recover. The purpose of R and D here is to develop a robust neutron source with a yield of 10 7 neutrons/s, and to carry out a preliminary research for application study in the next research stage

  15. Neutron spectroscopy on TFTR [Tokamak Fusion Test Reactor

    International Nuclear Information System (INIS)

    Nishitani, T.; Strachan, J.D.

    1988-05-01

    This paper describes the use of an 3 He ionization chamber for neutron spectroscopy on TFTR during 1987. The ion temperature was measured using neutron spectroscopy for one set of ohmically heated plasmas. The deduced ion temperatures agreed to within 20% with those measured by other diagnostics. 11 refs., 11 figs., 1 tab

  16. New statistical model of inelastic fast neutron scattering

    International Nuclear Information System (INIS)

    Stancicj, V.

    1975-07-01

    A new statistical model for treating the fast neutron inelastic scattering has been proposed by using the general expressions of the double differential cross section in impuls approximation. The use of the Fermi-Dirac distribution of nucleons makes it possible to derive an analytical expression of the fast neutron inelastic scattering kernel including the angular momenta coupling. The obtained values of the inelastic fast neutron cross section calculated from the derived expression of the scattering kernel are in a good agreement with the experiments. A main advantage of the derived expressions is in their simplicity for the practical calculations

  17. Present status of fast neutron therapy for the malignant tumors

    Energy Technology Data Exchange (ETDEWEB)

    Tsunemoto, H; Morita, S; Honke, Y [National Inst. of Radiological Sciences, Chiba (Japan)

    1980-04-01

    Fast neutron therapy has been applied to the treatment of cancer of the head and the neck, prostatic cancer, osteosarcoma, and malignant melanoma, and the basic treatment schedule for this therapy for them has been almost established. The effectiveness of this therapy for squamous cell carcinoma of the uterus will be established by the results of future clinical application of this therapy. It is expected that postoperative irradiation of fast neutron will decrease local recurrence of adenocarcinoma of the uterus. Treatment schedule for fast neutron therapy for esophageal cancer and lung cancer must be established, and moreover, it is necessary to apply this therapy to the treatment of gastric and pancreatic cancer.

  18. Present needs and future trends in neutron crystallography and spectroscopy

    International Nuclear Information System (INIS)

    Williams, J.M.

    1978-11-01

    Topics covered include: structural investigation by neutron and x-ray diffraction; sources and characteristics of neutron radiation; time-of-flight techniques; overview of neutron crystallography and structural chemistry; hydrogen bonds; transition-metal hydride complexes; actinide and lanthanide complexes; carbon-hydrogen-metal interactions in organometallic chemistry and catalysis; metal clusters and catalysis; materials with unusual solid-state properties; biochemical molecules and biological systems; electron and spin density distributions in crystalline solids; incoherent neutron-scattering spectroscopy; and quasielastic neutron scattering and high resolution spectroscopy

  19. Electron spectroscopy with fast heavy ions

    International Nuclear Information System (INIS)

    Schneider, D.

    1983-01-01

    Since about 1970 the spectroscopy of Auger-electrons and characteristic x-rays following energetic ion-atom collisions has received a great deal of attention. An increasing number of accelerators, capable of providing a large number of projectile ion species over a wide range of projectile energies, became available for studying ion-atom collision phenomena. Many charged particles from protons up to heavy ions like uranium can be accelerated to energies ranging over six orders of magnitude. This allows us to study systematically a great variety of effects accompanied by dynamic excitation processes of the atomic shells in either the projectile- or target-atoms. The studies yield fundamental information regarding the excitation mechanism (e.g., Coulomb and quasi-molecular excitation) and allow sensitive tests of atomic structure theories. This information in turn is valuable to other fields in physics like plasma-, astro-, or solid-state (surface) physics. It is a characteristic feature of fast heavy-ion accelerators that they can produce highly stripped ion species which have in turn the capability to highly ionize neutral target atoms or molecules in a single collision. The ionization process, mainly due to the strong electrical fields that are involved, allows us to study few-electron atoms with high atomic numbers Z. High resolution spectroscopy performed with these atoms allows a particularly good test of relativistic and QED effects. The probability of producing these few electron systems is determined by the charge state and the velocity of the projectile ions. In this contribution the possibilities of using electron spectroscopy as a tool to investigate fast ion-atom collisions is discussed and demonstrated with a few examples. 30 references

  20. Fast neutron spectrum measurement in the JMTR

    International Nuclear Information System (INIS)

    Sakurai, K.; Mizuho, M.

    1980-01-01

    Fast neutron spectrum measurement at positions of K-10 (fuel region), J-11 (first beryllium reflector region) and I-12 (second beryllium reflector region) in the JMTRC has been performed with the threshold detectors such as 107 Ag(n,n')sup(107m)Ag, 103 Rh(n,n')sup(103m)Rh, 115 In(n,n')sup(115m)In and 238 U(n,f)F.P. above 0.1 MeV energy region. The activity data have been analyzed by the unfolding code SAND-II using ANISN spectrum for initial spectrum. An effective cross section of 54 Fe(n,p) 54 Mn is calculated with Fabry's cross section data and SAND-II spectrum for K-10, J-11 and I-12. They are 76.7 mb, 69.0 mb and 68.2 mb for K-10, J-11 and I-12 respectively. These values agree with the effective cross sections (calculated by Fabry's cross section data and ANISN spectrum) within +-6%

  1. Medical use of fast neutrons in radiotherapy and radiography

    International Nuclear Information System (INIS)

    Bewley, D.K.

    1975-01-01

    Over 400 patients have been treated with fast neutrons from a cyclotron at Hammersmith Hospital, London, using 16 MeV deuterons on beryllium. A large variety of malignant disease is included in this trial. A randomized trial of fast neutron therapy for cancer of the mouth and throat is in progress and preliminary results will be given. Fast neutron radiographs are often taken to check the positions of the fields used on the patients. These show no contrast from bone, but demonstrate only the presence of gas-filled cavities. As a diagnostic method, fast neutron radiography suffers from a number of disadvantages, the main ones being lack of sensitivity of the image-forming system and the hazard to the patient due to a large Quality Factor. Estimation of the absorbed dose given to different types of tissue is an important factor in the medical use of fast neutrons. More data are needed on the processes whereby fast neutrons impart energy to matter, particularly for neutrons above 15 MeV

  2. Japanese experience with clinical trails of fast neutrons

    International Nuclear Information System (INIS)

    Tsunemoto, H.; Arai, T.; Morita, S.; Ishikawa, T.; Aoki, Y.; Takada, N.; Kamata, S.

    1982-01-01

    Between November, 1975 and November, 1981, 825 patients were treated with 30 MeV (d-Be) neutrons at the National Institute of Radiological Sciences, Chiba. At the Institute of Medical Science, Tokyo, 302 patients were referred to the Radiation Therapy department and were treated with 16 MeV (d-Be) neutrons. The emphasis of these clinical trials with fast neutrons was placed on the estimation of the effect of fast neutrons for locally advanced cancers or radioresistant cancers, and on evaluation of the rate of complication of normal tissues following irradiaton with fast neutrons. Results were evaluated for patients with previously untreated cancer; local control of the tumor was observed in 59.1%. Complications requiring medical care developed in only 32 patients. Patients who had received pre- or postoperative irradiation were excluded from this evaluation. Late reaction of soft tissue seemed to be more severe than that observed with photon beams. The results also suggest that for carcinoma of the larynx, esophagus, uterine cervix, Pancoasts's tumor of the lung and osteosarcoma, fast neutrons were considered to be effectively applied in this randomized clinical trial. For carcinoma of the larynx, a fast nuetron boost was effectively delivered, although an interstitial implant was necessarily combined with fast neutrons for carcinoma of the tongue. The cumulative survival rate of the patients with carcinoma of the esophagus treated with fast neutrons was 26% compared to the survival rate of 10.5% obtained using photons. This was supported by evidence from the pathological studies that showed that the tumor cells which had deeply invaded into the esophagus were effectively destroyed when fast neutrons were applied

  3. Experimental possibilities and fast neutron dose map of the fast neutron fields at the RB reactor facility

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.

    1993-01-01

    The RB is an unshielded, zero power nuclear facility with natural and enriched uranium fuel (2% and 80%) and D 2 O as moderator. It is possible to create different configurations of non-reflected and partially reflected critical systems and to make experiments in the fields of thermal neutrons. The fields of fast neutrons with 'softened' fission spectrum are made by modifying the system: modified experimental fuel channel EFC, coupled fast-thermal system in two configurations CFTS-1 and CFTS-2, coupled fast-thermal core HERBE. The intermediate and fast neutron absorbed doses in fast neutron fields are given. In first configuration of RB reactor it was almost impossible to perform dosimetric and other experiments. By creating these fields, with in our circumstances available fuel elements, the possibilities for different experiments are greatly improved. Now we can irradiate food samples, soil samples, electronic devices, study material properties, perform various dosimetry experiments, etc. (1 tab.)

  4. Fast neutron boost for the treatment of grade IV astrocytomas

    International Nuclear Information System (INIS)

    Breteau, N.; Destembert, B.; Favre, A.; Pheline, C.; Schlienger, M.

    1989-01-01

    A previous study, on grade IV astrocytomas, compared a combination of photons and fast neutron boost to photons only, both treatments being delivered following a concentrated irradiation schedule. A slight improvement in survival was observed after neutron boost for non operated patients, but not for operated patients. Since death was always related to local recurrence and since no complication occurred after neutron boost, the neutron dose was increased from 6 to 7 Gy in January 1985. No improvement in survival was observed for patients treated with neutron boost after complete resection. After subtotal resection, the group that was treated with the higher neutron boost (7 Gy) showed a significant benefit in survival at twelve months. When patients had only a biopsy before irradiation, there was a benefit in survival after neutron boost, but no additional benefit was gained when the size of the neutron boost was increased from 6 to 7 Gy. (orig.) [de

  5. Conceptual design, neutronic and radioprotection study of a fast neutron irradiation station at SINQ

    International Nuclear Information System (INIS)

    Zanini, L.; Baluc, N.; Simone, A. De; Eichler, R.; Joray, S.; Manfrin, E.; Pouchon, M.; Rabaioli, S.; Schumann, D.; Welte, J.; Zhernosekov, K.

    2011-12-01

    This comprehensive, illustrated report by the Paul Scherrer Institute PSI in Switzerland documents the proposals concerning the conceptual design, neutronic and radioprotection study of a fast neutron irradiation station at the PSI's Swiss Spallation Neutron Source SINQ facility. The need for fast neutron irradiation is discussed and the possibility of using SINQ as a fast neutron irradiation facility is considered. The production of isotopes, tracers and medical isotopes is discussed, as are fission and fusion reactor technologies. The characteristics of the neutron spectrum in SINQ are discussed. The neutronic and radioprotection calculations for an irradiation station at SINQ are looked at in detail and extensive examples of work done and results obtained are presented and discussed. Radioprotection issues are also looked at. Further contributions in the report cover the hot/cold irradiation station in the SINQ target. An appendix provides detailed drawings of the facility's pneumatic delivery system

  6. Some Applications of Fast Neutron Activation Analysis of Oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Owrang, Farshid

    2003-07-01

    illustrated how the activated water would propagate along that pipe. C) Combustion products. In order to investigate the oxidation in combustion products (deposits), the total amount of oxygen in the deposits collected from combustion chambers of a modern gasoline engine was measured, using cyclic fast neutron activation analysis (FNAA). As a compartment, the organic compounds containing oxygen were identified using {sup 13}C solid-state nuclear magnetic resonance (NMR) spectroscopy. The results of FNAA showed that the amount of oxygen in deposits varies depending on where the deposits have been formed. {sup 13}C NMR has showed that the carbon backbone of the deposits exists as highly oxidized poly aromatics and/or graphitic structure. D) On-line fast neutron activation analysis. On-line neutron activation analysis was used to detect the amount of oxygen in bulk liquids. The method was optimised for on-line detection of oxygen in rapeseed oil. The goal was to develop a non-intrusive method for measurement of the total amount of oxygen in oil during combustion/oxidation.

  7. Some Applications of Fast Neutron Activation Analysis of Oxygen

    International Nuclear Information System (INIS)

    Owrang, Farshid

    2003-01-01

    illustrated how the activated water would propagate along that pipe. C) Combustion products. In order to investigate the oxidation in combustion products (deposits), the total amount of oxygen in the deposits collected from combustion chambers of a modern gasoline engine was measured, using cyclic fast neutron activation analysis (FNAA). As a compartment, the organic compounds containing oxygen were identified using 13 C solid-state nuclear magnetic resonance (NMR) spectroscopy. The results of FNAA showed that the amount of oxygen in deposits varies depending on where the deposits have been formed. 13 C NMR has showed that the carbon backbone of the deposits exists as highly oxidized poly aromatics and/or graphitic structure. D) On-line fast neutron activation analysis. On-line neutron activation analysis was used to detect the amount of oxygen in bulk liquids. The method was optimised for on-line detection of oxygen in rapeseed oil. The goal was to develop a non-intrusive method for measurement of the total amount of oxygen in oil during combustion/oxidation

  8. Laser spectroscopy of neutron deficient Sn isotopes

    CERN Multimedia

    We propose to study the ground state properties of neutron-deficient Sn isotopes towards the doubly-magic nucleus $^{100}$Sn. Nuclear spins, changes in the rms charge radii and electromagnetic moments of $^{101-121}$Sn will be measured by laser spectroscopy using the CRIS experimental beam line. These ground-state properties will help to clarify the evolution of nuclear structure properties approaching the $\\textit{N = Z =}$ 50 shell closures. The Sn isotopic chain is currently the frontier for the application of state-of-the-art ab-initio calculations. Our knowledge of the nuclear structure of the Sn isotopes will set a benchmark for the advances of many-body methods, and will provide an important test for modern descriptions of the nuclear force.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  10. Damages to gladiolu corm caused by fast neutron irradiation

    International Nuclear Information System (INIS)

    Zhang Zhiwei; Wang Dan; Zhang Dongxue; Zheng Chun

    2007-01-01

    Gladiolus corms were irradiated to 100-500kGy by fast neutrons in the CFBR-II pulsed reactor, Scanning electron microscope images of the irradiated samples revealed significant radiation damages to the gladiolus corms, and the mutagenic effects were studied by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Within the dose range, radiation damage to the corm increased with the dose, with corm epidermis of the samples irradiated in vertical incidence being more serious than those irradiated in side-incidence to the same dose. Biological characters were investigated via field experiments, and the bands of protein subunit were analyzed by SDS-PAGE. The results showed that the fast neutrons irradiation inhibited growth of M1 generation seedling significantly. Protein expression was obviously inhibited by the irradiation. The study indicates that fast neutron induction is an effective way for gladiolus breeding. And the results may lay a foundation for studies on fast neutron mutation breeding. (authors)

  11. Indoor Fast Neutron Generator for Biophysical and Electronic Applications

    Science.gov (United States)

    Cannuli, A.; Caccamo, M. T.; Marchese, N.; Tomarchio, E. A.; Pace, C.; Magazù, S.

    2018-05-01

    This study focuses the attention on an indoor fast neutron generator for biophysical and electronic applications. More specifically, the findings obtained by several simulations with the MCNP Monte Carlo code, necessary for the realization of a shield for indoor measurements, are presented. Furthermore, an evaluation of the neutron spectrum modification caused by the shielding is reported. Fast neutron generators are a valid and interesting available source of neutrons, increasingly employed in a wide range of research fields, such as science and engineering. The employed portable pulsed neutron source is a MP320 Thermo Scientific neutron generator, able to generate 2.5 MeV neutrons with a neutron yield of 2.0 x 106 n/s, a pulse rate of 250 Hz to 20 KHz and a duty factor varying from 5% to 100%. The neutron generator, based on Deuterium-Deuterium nuclear fusion reactions, is employed in conjunction with a solid-state photon detector, made of n-type high-purity germanium (PINS-GMX by ORTEC) and it is mainly addressed to biophysical and electronic studies. The present study showed a proposal for the realization of a shield necessary for indoor applications for MP320 neutron generator, with a particular analysis of the transport of neutrons simulated with Monte Carlo code and described the two main lines of research in which the source will be used.

  12. Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor

    International Nuclear Information System (INIS)

    Yavar, A.R.; Sarmani, S.B.; Wood, A.K.; Fadzil, S.M.; Radir, M.H.; Khoo, K.S.

    2011-01-01

    Determination of thermal to fast neutron flux ratio (f fast ) and fast neutron flux (φ fast ) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The f fast and subsequently φ fast were determined using the absolute method. The f fast ranged from 48 to 155, and the φ fast was found in the range 1.03x10 10 -4.89x10 10 n cm -2 s -1 . These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.

  13. Development of fast neutron radiography system based on portable neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th [Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Rd., Patumwan, Bangkok, THAILAND 10330 (Thailand)

    2016-01-22

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  14. Semi-insulating GaAs detectors of fast neutrons

    International Nuclear Information System (INIS)

    Sagatova, A.; Sedlackova, K.; Necas, V.; Zatko, B.; Dubecky, F.; Bohacek, P.

    2012-01-01

    The present work deals with the technology of HDPE neutron conversion layer application on the surface of semi-insulating (SI) GaAs detectors via developed polypropylene (PP) based glue. The influence of glue deposition on the electric properties of the detectors was studied as well as the ability of the detectors to register the fast neutrons from "2"3"9Pu-Be neutron source. (authors)

  15. Conventional sources of fast neutrons in 'cold fusion' experiments

    International Nuclear Information System (INIS)

    Cribier, M.; Spiro, M.; Favier, J.

    1989-04-01

    In 'cold fusion' experiments with heavy water a source of neutrons is the dissociation of deuterium induced by alpha particles emitted by natural occurring radioisotopes. We evaluate the rate of fast neutron emission as a function of the concentration of U, Th, Rn in contact with deuterium and discuss the possibility that the neutrons claimed to have been observed in 'cold fusion' experiments could be due to this conventional source

  16. A fast neutron detector with IP by track measurement

    International Nuclear Information System (INIS)

    Miao Zhengqiang; Yang Jun; Zhang Qiang; Zhao Xiangfeng; Wang Daohua

    2004-01-01

    Imaging Plate(IP) is very sensitive to electric particles, especially to heavy ions. As we know, the recoiling protons are produced while fast neutrons scattered in light material containing hydrogen. When the recoiling proton enters in the sensitive layer of IP, a track will be recorded by IP. In this paper, a fast neutron detector based on IP and (n, p) reaction is described in detail, the detector's efficiency is studied also. (authors)

  17. Fast neutron activation analysis of Kalewa (Myanmar) coal

    Energy Technology Data Exchange (ETDEWEB)

    Myint, U; Naing, W [Yangon Univ. (Myanmar). Dept. of Chemistry

    1994-06-01

    Aluminium, silicon, copper, iron, magnesium and sulfur in Kalewa (Myanmar) coal were determined by fast neutron activation analysis. For activation a KAMAN A-710 Neutron Generator was used. Kalewa coal was found to be low in sulfur and relatively rich in iron. (author) 2 refs.; 1 fig.; 1 tab.

  18. Fast neutron activation analysis of Kalewa (Myanmar) coal

    International Nuclear Information System (INIS)

    Myint, U.; Naing, W.

    1994-01-01

    Aluminium, silicon, copper, iron, magnesium and sulfur in Kalewa (Myanmar) coal were determined by fast neutron activation analysis. For activation a KAMAN A-710 Neutron Generator was used. Kalewa coal was found to be low in sulfur and relatively rich in iron. (author) 2 refs.; 1 fig.; 1 tab

  19. Fast neutron fluxes distribution in Egyptian ilmenite concrete

    International Nuclear Information System (INIS)

    Megahed, R.M.; Abou El-Nasr, T.Z.; Bashter, I.I.

    1978-01-01

    This work is concerned with the study of the distribution of fast neutron fluxes in a new type of heavy concrete made from Egyptian ilmenite ores. The neutron source used was a collimated beam of reactor neutrons emitted from one of the horizontal channels of the ET-RR-1 reactor. Measurements were carried-out using phosphorous activation detectors. Iso-flux curves were represented which give directly the shape and thickness required to attenuate the emitted fast neutron flux to a certain value. The relaxation lengths were also evaluated from the measured data for both disc monodirectional source and infinite plane monodirectional source. The obtained values were compared with that calculated using the derived values of relative number densities and microscopic removal cross-sections of the different constituents. The obtained data show that ilmenite concrete attenuates fast neutron flux more strongly than ordinary concrete. A semiemperical formula was derived to calculate the fast neutron flux at different thicknesses along the beam axis. Another semiemperical formula was also derived to calculate the fast neutron flux in ordinary concrete along the beam axis using the corresponding value in ilmenite concrete

  20. Correlation properties of delayed neutrons from fast neutron induced fission

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Isaev, S.G.

    1998-01-01

    The experimental studies of the energy dependence of the delayed neutron parameters for various fissioning systems has shown that the behavior of a some combination of delayed neutron parameters (group relative abundances a i and half lives T i ) has a similar features. On the basis of this findings the systematics of delayed neutron experimental data for thorium, uranium, plutonium and americium isotopes have been investigated with the purpose to find a correlation of DN parameters with characteristics of fissioning system as well as a correlation between the delayed neutron parameters themselves. Below we will present the preliminary results which were obtained during this study omitting the physics interpretation of the results. (author)

  1. Delayed neutron yield from fast neutron induced fission of 238U

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Roshchenko, V.A.; Goverdovski, A.A.; Tertytchnyi, R.G.

    2002-01-01

    The measurements of the total delayed neutron yield from fast neutron induced fission of 238 U were made. The experimental method based on the periodic irradiation of the fissionable sample by neutrons from a suitable nuclear reaction had been employed. The preliminary results on the energy dependence of the total delayed neutron yield from fission of 238 U are obtained. According to the comparison of experimental data with our prediction based on correlation properties of delayed neutron characteristics, it is concluded that the value of the total delayed neutron yield near the threshold of (n,f) reaction is not a constant. (author)

  2. Fast neutron sensitivity of polymer dosemeters

    International Nuclear Information System (INIS)

    Harper, M.W.; Pearson, D.W.; Moran, P.R.

    1975-01-01

    The responses of polymer thermocurrent dosemeters to fission spectrum and 14 MeV neutrons were measured. The dosemeters are in the form of disks 1 cm diam by 0.5 mm thick. Relative to Cobalt 60 gamma responses, teflon PTFE dosemeters show a 6 percent response to 14 MeV neutrons and a 5 percent response to fission neutrons on a tissue rad basis. Polymethylpentene dosemeters show a 49 percent response to 14 MeV neutrons and a 40 percent response to fission neutrons on a tissue rad basis when provided with adequate recoil proton buildup. The sensitivity of these dosemeters is limited to neutron doses greater than 10 rads by spurious background currents

  3. Specification of fast neutron radiation quality from cell transformation data

    International Nuclear Information System (INIS)

    Coppola, M.

    1992-01-01

    Experimental data on the neoplastic transformation of C3H 10T1/2 cells measured at Casaccia after neutron and X-ray irradiation were used to determine neutron RBE values for the RSV-Tapiro fast reactor energy spectrum and for monoenergetic neutrons of 0.5, 1, and 6 MeV. In parallel, micro-dosimetric measurements provided the actual lineal energy distributions and related mean parameters for the reactor radiation. From these experiments, values of the neutron quality factor were derived for the reactor neutron energy spectrum and, in turn, for the other neutron energies tested. A mathematical expression giving a smooth dependence on neutron energy was also determined for the effective quality factor in the entire energy range examined. The results were compared with other proposals

  4. The fast neutron facility at the research reactor Munich. Determination of the beam quality and medical applications

    International Nuclear Information System (INIS)

    Wagner, F. M.; Koester, L.

    1990-01-01

    At the research reactor FRM, fast and epithermal neutron beams are generated by a thermal-to-fast neutron converter and/or near core scatterers. The dosimetry and spectroscopy of the resulting intense mixed beams of neutron and gamma radiation with a wide range of energies set spetial tasks for neutron dosimetry and spectroscopy. The twin chamber method and some others are briefly described. Neutron spectroscopy is performed by a Li-6 sandwich spectrometer covering the full neutron spectrum of a well-collimated mixed beam from about 20 keV to 8 MeV. The data registration is assisted by a microcomputer which generates sum and triton spectra on-line. Sum analysis is applied to neutron energies greater than 0.3 MeV; the intermediate neutron spectrum is evaluated by unfolding of the triton spectrum. Moreover, a brief overview of the reactor neutron therapy (RENT) at the FRM is given. After a number of animal experiments for the determination of the biological effectiveness relative to X-rays, clinical irradiations have been started in 1985. The most important indications for RENT are listed. 140 patients with bad prognoses have been treated since. The average tumour control rate of 60% is surprisingly high. Possibilities for an assisting Boron Neutron Capture Therapy (BNCT) are shown. 8 figs., 23 refs

  5. Effect of Fast Neutron to MA/PU Burning/Transmutation Characteristic Using a Fast Reactor

    International Nuclear Information System (INIS)

    Marsodi; Lasman, As Natio; Kimamoto, A.; Marsongkohadi; Zaki, S.

    2003-01-01

    MA/Pu burning/transmutation has been studied and evaluated using fast neutrons. Generally, neutron density at this fast burner reactor and transmutation has spectrum energy level around 0.2 MeV with wide enough variation, i.e. from low neutron spectrum to its peak is 0.2 MeV. This neutron spectrum energy level depends on the kind of cooler material or fuel used. Neutron spectrum higher than fast power reactor neutron spectrum is found by means of changing oxide fuel by metallic fuel and changing natrium cooler material by metallic or gas cooler material. This evaluation is conducted by various variations in accordance with the kind of fuel or cooler, MA/Pu fractions and fuel comparison fraction with respect to its cooler in order to get better neutron usage and MA/Pu burning speed. Reactor calculation evaluation in this paper was conducted with 26-group nuclear data cross section energy spectrum. The main purpose of the discussion is to know the effect of fast neutrons to burning/transmutation MA/Pu using fast neutrons

  6. A new neutron noise technique for fast reactors

    International Nuclear Information System (INIS)

    Zhuo Fengguan; Jin Manyi; Yao Shigui; Su Zhuting

    1987-12-01

    This paper gives a new neutron noise technique for fast reactors, which is known as thermalization measurement technique of the neutron noise. The theoretical formulas of the technique were developed, and a digital delayed coincidence time analyzer consisted of TTL integrated circuits was constructed for the study of this technique. The technique has been tested and applied practically at Df-VI fast zero power reactor. It was shown that the provided technique in this work has a number of significant advantages in comparison with the conventional neutron noise method

  7. Modeling delayed neutron monitoring systems for fast breeder reactors

    International Nuclear Information System (INIS)

    Bunch, W.L.; Tang, E.L.

    1983-10-01

    The purpose of the present work was to develop a general expression relating the count rate of a delayed neutron monitoring system to the introduction rate of fission fragments into the sodium coolant of a fast breeder reactor. Most fast breeder reactors include a system for detecting the presence of breached fuel that permits contact between the sodium coolant and the mixed oxide fuel. These systems monitor for the presence of fission fragments in the sodium that emit delayed neutrons. For operational reasons, the goal is to relate the count rate of the delayed neutron monitor to the condition of the breach in order that appropriate action might be taken

  8. Neutron Spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

    Science.gov (United States)

    Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; Bleuel, D. L.; Bernstein, L. A.; Bevins, J.; Harasty, M.; Laplace, T. A.; Matthews, E. F.

    2018-01-01

    A new double time-of-flight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performed using both GEANT4 and MCNP6. The efficiency-corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. This method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams with frame overlap and opens new opportunities for pulsed white neutron source facilities.

  9. Fast counting electronics for neutron coincidence counting

    International Nuclear Information System (INIS)

    Swansen, J.E.

    1987-01-01

    This patent describes a high speed circuit for accurate neutron coincidence counting comprising: neutron detecting means for providing an above-threshold signal upon neutron detection; amplifying means inputted by the neutron detecting means for providing a pulse output having a pulse width of about 0.5 microseconds upon the input of each above threshold signal; digital processing means inputted by the pulse output of the amplifying means for generating a pulse responsive to each input pulse from the amplifying means and having a pulse width of about 50 nanoseconds effective for processing an expected neutron event rate of about 1 Mpps: pulse stretching means inputted by the digital processing means for producing a pulse having a pulse width of several milliseconds for each pulse received form the digital processing means; visual indicating means inputted by the pulse stretching means for producing a visual output for each pulse received from the digital processing means; and derandomizing means effective to receive the 50 ns neutron event pulses from the digital processing means for storage at a rate up to the neutron event rate of 1 Mpps and having first counter means for storing the input neutron event pulses

  10. Plastic fiber scintillator response to fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Danly, C. R.; Sjue, S.; Wilde, C. H.; Merrill, F. E.; Haight, R. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2014-11-15

    The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.

  11. Elemental analysis of fertilizer by fast neutron activation

    International Nuclear Information System (INIS)

    Bodart, F.; Deconninck, G.

    1977-01-01

    A simple and accurate technique has been developed to analyse commercial fertilizers for phosphorus, potassium, chlorine, magnesium and silicon. The method is based on fast-neutron activation using a neutron flux of 2x10 11 neutrons/second. The optimum analytical conditions are tabulated. After irradiation, the sample is measured on a conventional counting system including a Ge(Li) detector (10% efficiency and 2 keV resolution for 60 Co) and a multichannel analyser. Monitor foils radioactivity are measured separately at the same time with a 2''x2''NaI detector coupled with a single channel analyser and a scaler. Fast neutron activation has proved to be a fast, simple, reliable and low cost analytical technique for the determination of phosphorus, silicon, potassium, magnesium and chlorine in fertilizers. Not less than five phosphorus determinations are possible in one hour, while two potassium, magnesium and chlorine determinations are made at the same time. (T.G.)

  12. Fast neutron radiation inactivation of Bacillus subtilis: Absorbed dose determination

    International Nuclear Information System (INIS)

    Song Lingli; Zheng Chun; Ai Zihui; Li Junjie; Dai Shaofeng

    2011-01-01

    In this paper, fast neutron inactivation effects of Bacillus subtilis were investigated with fission fast neutrons from CFBR-II reactor of INPC (Institute of Nuclear Physics and Chemistry) and mono-energetic neutrons from the Van de Graaff accelerator at Peking University. The method for determining the absorbed dose in the Bacillus subtilis suspension contained in test tubes is introduced. The absorbed dose, on account of its dependence on the volume and the form of confined state, was determined by combined experiments and Monte Carlo method. Using the calculation results of absorbed dose, the fast neutron inactivation effects on Bacillus subtilis were studied. The survival rates and absorbed dose curve was constructed. (authors)

  13. Absorbing rods for nuclear fast neutron reactor absorbing assembly

    International Nuclear Information System (INIS)

    Aji, M.; Ballagny, A.; Haze, R.

    1986-01-01

    The invention proposes a neutron absorber rod for neutron absorber assembly of a fast neutron reactor. The assembly comprises a bundle of vertical rods, each one comprising a stack of pellets made of a neutron absorber material contained in a long metallic casing with a certain radial play with regard to this casing; this casing includes traps for splinters from the pellets which may appear during reactor operation, at the level of contact between adjacent pellets. The present invention prevents the casing from rupture involved by the disintegration of the pellets producing pieces of boron carbide of high hardness [fr

  14. Fast neutron activation analysis at Texas A and M University

    International Nuclear Information System (INIS)

    James, W.D.

    1997-01-01

    Fast neutron generators are used at Texas A and M University to provide a supply of high energy neutrons for nuclear analytical measurements. A series of neutron activation analysis procedures have been developed for determining various major, minor and trace constituents in a variety of materials. These procedures are primarily developed to compliment our reactor based NAA program, thereby expanding the list of determinable elements to include those difficult or impossible to measure using thermal neutrons. A few typical methods are discussed. The unique implementation of the methodologies at Texas A and M are explained. (author)

  15. Dosimetric properties of the fast neutron therapy beams at TAMVEC

    International Nuclear Information System (INIS)

    Almond, P.R.; Smith, A.R.; Smathers, J.R.; Otte, V.A.

    1975-01-01

    In October 1972, M.D. Anderson Hospital and Tumor Institute of the University of Texas System Cancer Center initiated a clinical trial of fast neutron radiotherapy using the cyclotron at Texas A and M University. Initially, the study used neutrons produced by bombarding beryllium with 16 MeV deuterons, but since March, 1973, neutrons from 50 MeV deuterons have been used. The dosimetric properties of the 30 MeV beams have also been measured for comparison with the neutron beams from D-T generators. The three beams are compared in terms of dose rate, skin sparing, depth dose and field flatness. Isodose curves for treatment planning were generated using the decrement line method and compared to curves measured by a computer controlled isodose plotter. This system was also used to measure the isodose curves for wedge fields. Dosimetry checks on various patients were made using silicon diodes as in vivo fast neutron dosimeters

  16. Seminar on Heat-transfer fluids for fast neutron reactors

    International Nuclear Information System (INIS)

    Brechet, Yves; Dautray, Robert; Friedel, Jacques; Brezin, Edouard; Martin, Georges; Pineau, Andre; Carre, Francois; Gauche, Francois; Rodriguez, Guillaume; Latge, Christian; Cabet, Celine; Garnier, Jean-Claude; Bamberger, Yves; Sauvage, Jean-Francois; Buisine, Denis; Agostini, Pietro; Ulyanov, Vladimir; Auger, Thierry; Heuer, Daniel; Ghetta, Veronique; Bubelis, Evaldas; Charlaix, Elisabeth; Barrat, Jean-Louis; Boquet, Lyderic; Glickman, Evgueny; Escaravage, Claude

    2014-03-01

    This book reports the content of a two-day meeting held by the Academy of Sciences on the use of heat-transfer fluids in fast neutron reactors. After a first part which proposes an overview of scientific and technical problems related to these heat-transfer fluids (heat transfer process, nuclear properties, chemistry, materials, risks), a contribution proposes a return on experience on the use of heat-transfer fluids in the different design options of reactors of fourth generation: from mercury to NaK in the first fast neutron reactor projects, specific assets and constraints of sodium used as heat-transfer fluid, concepts of fast neutron reactors cooled by something else than sodium, perspectives for projects and research in fast neutron reactors. The next contribution discusses the specifications of future fast-neutron reactors: expectations for fourth-generation reactors, expectations in terms of performance and of safety, specific challenges. The last contribution addresses actions to be undertaken in the field of research and development: actions regarding all reactor types or specific types as sodium-cooled reactors, lead cooled reactors, molten salt reactors, and gas-cooled fast reactors

  17. Fast Neutrons - LET Distributions and the Response of Mammalian Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bewley, D. K. [Medical Research Council Cyclotron Unit, Hammersmith Hospital, London (United Kingdom)

    1968-03-15

    Distributions of stopping power (LET) are given for four beams of fast neutrons, namely, neutrons of 14.6 MeV, neutrons produced by bombarding a thick beryllium target with 15 MeV deuterons, neutrons of 3 MeV, and fast neutrons produced by bombardment of a {sup 235}U converter plate with thermal neutrons. The track average LET is correlated with mean neutron energy, but the dose average is approximately constant. However, neither of these types of average is expected to have much relevance to radiobiology. Further, specification of a ''biologically effective LET'' depends on the biological test used, and is not solely a function of the radiation quality. An attempt has been made to calculate the response of T.I. kidney cells in tissue culture to these four beams of neutrons, based on their response to charged particles using the track-segment method. The calculated RBE's of the neutron beams are lower than the observed values and the calculated values of the oxygen enhancement ratio are higher. These differences seem too great to be explained by errors in dosimetry and in the calculated LET spectra. The suggestion is made that LET is not an adequate criterion of radiation quality, and that the discrepancies may be explained by more detailed consideration of the part played by delta rays and by heavy recoil tracks of short range. (author)

  18. Pulsed thermal neutron source at the fast neutron generator.

    Science.gov (United States)

    Tracz, Grzegorz; Drozdowicz, Krzysztof; Gabańska, Barbara; Krynicka, Ewa

    2009-06-01

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

  19. Neutron intensity of fast reactor spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Takamatsu, Misao; Aoyama, Takafumi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-03-01

    Neutron intensity of spent fuel of the JOYO Mk-II core with a burnup of 62,500 MWd/t and cooling time of 5.2 years was measured at the spent fuel storage pond. The measured data were compared with the calculated values based on the JOYO core management code system `MAGI`, and the average C/E approximately 1.2 was obtained. It was found that the axial neutron intensity didn`t simply follow the burnup distribution, and the neutron intensity was locally increased at the bottom end of the fuel region due to an accumulation of {sup 244}Cm. (author)

  20. Fast-neutron scattering from elemental cadmium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1982-07-01

    Neutron differential-elastic-scattering cross sections of elemental cadmium are measured from approx. = 1.5 to 4.0 MeV at incident-neutron energy intervals of 50 to 200 keV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Concurrently, lumped-level neutron inelastic-excitation cross sections are measured. The experimental results are used to deduce parameters of an optical-statistical model that is descriptive of the observables and are compared with corresponding quantities given in ENDF/B-V

  1. Preliminary examination of the applicability of imaging plates to fast neutron radiography

    International Nuclear Information System (INIS)

    Matsubayashi, Masahito; Hibiki, Takashi; Mishima, Kaichiro; Yoshii, Koji; Okamoto, Koji

    2001-01-01

    Fast neutron radiography is an attractive non-destructive inspection technique because of the excellent penetration characteristics of fast neutrons in matter. However, the difficulty of detecting fast neutrons reduces this attractive feature. As an experiment to overcome the difficulty, imaging plates were applied to fast neutron radiography. A simple combination of two sheets of imaging plates and a sheet of polyethylene as a proton emitter was examined with the (fast neutron, thermal neutron and gamma ray) FTG discriminator proposed by Yoneda et al. . The experimental results showed that the method could be applicable to fast neutron radiography with effective discrimination of γ-rays

  2. High resolution fast neutron spectrometry without time-of-flight

    International Nuclear Information System (INIS)

    Evans, A.E.; Brandenberger, J.D.

    1978-01-01

    Performance tests of a spectrometer tube of the type developed by Cuttler and Shalev show that the measurement of fast neutron spectra with this device can be made with an energy resolution previously obtainable only in large time-of-flight facilities. In preliminary tests, resolutions of 16.4 keV for thermal neutrons and 30.9 keV for 1-MeV neutrons were obtained. A broad-window pulse-shape discrimination (PSD) system is used to remove from pulse-height distributions most of the continua due to 3 He-recoil events, noise, and wall effect. Use of PSD improved the energy resolution to 12.9 keV for thermal neutrons and 29.2 keV for 1-MeV neutrons. The detector is a viable tool for neutron research at nominally equipped accelerator laboratories

  3. Scattering of fast neutrons from elemental molybdenum

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1982-11-01

    Differential broad-resolution neutron-scattering cross sections of elemental molybdenum were measured at 10 to 20 scattering angles distributed between 20 and 160 degrees and at incident-neutron energy intervals of approx. = 50 to 200 keV from 1.5 to 4.0 MeV. Elastically-scattered neutrons were fully resolved from inelastic events. Lumped-level inelastic-neutron-scattering cross sections were determined corresponding to observed excitation energies of; 789 +- 23, 195 +- 23, 1500 +- 34, 1617 +- 12, 1787, 1874, 1991, 2063 +- 24, 2296, 2569 and 2802 keV. An optical-statistical model was deduced from the measured elastic-scattering results. The experimental values were compared with the respective quantities given in ENDF/B-V

  4. Dosimetry intercomparisons between fast neutron radiotherapy facilities

    International Nuclear Information System (INIS)

    Almond, P.R.; Smith, A.R.; Smathers, J.B.; Otte, V.A.

    1975-01-01

    Neutron dosimetry intercomparisons have been made between M.D. Anderson Hospital and Tumor Institute, Naval Research Laboratory, University of Washington Hospital, and Hammersmith Hospital. The parameters that are measured during these visits are: tissue kerma in air, tissue dose at depth of dose maximum, depth dose, beam profiles, neutron/gamma ratios and photon calibrations of ionization chambers. A preliminary report of these intercomparisons will be given including a comparison of the calculation and statement of tumor doses for each institution

  5. Fast neutron response of coumarin in water and heavy water

    International Nuclear Information System (INIS)

    Krishnan, D.; Kher, R.K.; Gopakumar, K.; Bhandari, N.S.

    1979-01-01

    Response of coumarin in aqueous solution has been studied earlier for gamma rays and fast neutrons by fluorescence measurement. For further fast neutron studies, two systems viz coumarin in H 2 0 and coumarin in D 2 0, were irradiated with fast neutrons in SNIF facility in the swimming pool type APSARA reactor at Trombay. Neutron fluence was estimated by measuring induced activity in sulphur pellet and associated gamma radiation was estimated using CaS0 4 :Dy TLD powder. The KERMA values were calculated for H 2 0 and D 2 0, assuming modified fission spectrum for fast neutron in SNIF position, and they were in the ratio of 2:1. Response of a chemical dosimetric system is expected to be proportional to the absorbed dose in the respective system for the same neutron fluence. This was experimentally found to be the case for coumarin in H 2 0 or D 2 0. These results are likely to be true in general for any aqueous chemical system. The limitations of using such a dual system for dosimetry in a mixed field is discussed. (author)

  6. Determination of contraband using fast neutron resonance technique

    Energy Technology Data Exchange (ETDEWEB)

    Bae, J.; Whang, J. [Kyunghee Univ., Dept. of Nuclear Engineering, Yongin-shi, Kyongki-do (Korea, Republic of)

    2004-07-01

    'Full-text:' Resonance technique with monoenergetic fast neutron beam is able to map features in bulk samples in a way that is sensitive to their elemental composition. It has a number of potential applications, for example, in mining and in the detection of contraband materials such as illicit drugs and explosives. By moving around the neutron detector experiences neutrons in the form of narrow line beam with different energies as the angle to the neutron source changes. Projection data was obtained using the Monte Carlo code MCNP4C. Therefore the fast neutrons scattered from an unknown object are used to determine the elemental content of the object and hence lead to its identification. Scattered features simulated for various test materials are analyzed using the HEPRO program system (PTB, Braunschweig) to determine the atom weight fractions for H. C. N, O and other elements in the materials. Atom weight fractions determined from scattering features are insensitive to neutron interactions in interfering materials surrounding the object. The simulations demonstrate that the fast neutron resonance technique (FNRT) provides reliable elemental characterization of bulk materials and has the necessary sensitivity to distinguish between drugs, explosives and other materials. (author)

  7. Determination of contraband using fast neutron resonance technique

    International Nuclear Information System (INIS)

    Bae, J.; Whang, J.

    2004-01-01

    'Full-text:' Resonance technique with monoenergetic fast neutron beam is able to map features in bulk samples in a way that is sensitive to their elemental composition. It has a number of potential applications, for example, in mining and in the detection of contraband materials such as illicit drugs and explosives. By moving around the neutron detector experiences neutrons in the form of narrow line beam with different energies as the angle to the neutron source changes. Projection data was obtained using the Monte Carlo code MCNP4C. Therefore the fast neutrons scattered from an unknown object are used to determine the elemental content of the object and hence lead to its identification. Scattered features simulated for various test materials are analyzed using the HEPRO program system (PTB, Braunschweig) to determine the atom weight fractions for H. C. N, O and other elements in the materials. Atom weight fractions determined from scattering features are insensitive to neutron interactions in interfering materials surrounding the object. The simulations demonstrate that the fast neutron resonance technique (FNRT) provides reliable elemental characterization of bulk materials and has the necessary sensitivity to distinguish between drugs, explosives and other materials. (author)

  8. Beam profiles for fast neutrons; and reply

    International Nuclear Information System (INIS)

    Bewley, D.K.; Parnell, C.J.; Bloch, P.

    1976-01-01

    The authors express surprise that Bloch et al. (Bloch, P.H., Hendry, G.O., Hilton, J.L., Quam, W.M., Reinhard, D.K., and Wilson, C., 1976, Phys. Med. Biol., Vol. 21, 450) justified a target size of 5.5 x 5.5 cm in a neutron generator by comparison with the profile given by a 2.5 MV X-ray generator. The penumbral width of this new neutron generator is more than twice that of a modern megavoltage X-ray machine, and larger than those of beams from standard 60 Co units, or of the Hammersmith Hospital cyclotron beam. The large target size of the neutron generator may have to be accepted as a necessary evil, but should not be considered satisfactory. In reply, one of the authors of the original note presents the results of calculations of beam profiles for 14 MeV neutron beams in a tissue-equivalent phantom, and suggests that the broader profiles are principally caused by the larger probability of side scatter, not by source size. The most fruitful approach to sharpening the neutron beam profile would seem to be to design a field flattening filter to increase relative dose near the edge inside the geometrically defined field. Calculations indicating that Bewley and Parnell have underestimated the penumbral widths of 60 Co beams are also presented. (U.K.)

  9. Fast neutron flux and intracranial dose distribution at a neutron irradiation facility

    International Nuclear Information System (INIS)

    Matsumoto, Tetsuo; Aizawa, Otohiko; Nozaki, Tetsuya

    1981-01-01

    A head phantom filled with water was used to measure the fast neutron flux using 115 In(n, n')sup(115m)In and 103 Rh(n, n')sup(103m)Rh reactions. γ-ray from sup(115m)In and x-ray from sup(103m)Rh were detected by a Ge(Li) and a Na(Tl)I counter, respectively. TLD was used to investigate the γ-dose rate distribution inside the phantom. Flux of fast neutron inside the phantom was about 1 x 10 6 n/cm 2 sec, which was 3 order smaller than that of thermal neutron. The fast neutron flux decreased to 1/10 at 15 cm depth, and γ-dose rate was about 200 R/h at 100 kW inside the phantom. Total dose at the surface was 350 rad/h, to which, fast neutrons contributed more than γ-rays. The rate of fast neutron dose was about 10% of thermal neutron's in Kerma dose unit (rad), however, the rate was highly dependent on RBE value. (Nakanishi, T.)

  10. Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT)

    Energy Technology Data Exchange (ETDEWEB)

    Cecilia, A.; Baccaro, S.; Cemmi, A. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Colli, V.; Gambarini, G. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy); Rosi, G. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Scolari, L. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy)

    2004-07-01

    A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF{sub 2}:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH{sub 3}CH(NH{sub 2})COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT. (authors)

  11. Real‑time, fast neutron detection for stimulated safeguards assay

    International Nuclear Information System (INIS)

    Joyce, Malcolm J.; Adamczyk, Justyna; Plenteda, Romano; Aspinall, Michael D.; Cave, Francis D.

    2015-01-01

    The advent of low‑hazard organic liquid scintillation detectors and real‑time pulse‑shape discrimination (PSD) processing has suggested a variety of modalities by which fast neutrons, as opposed to neutrons moderated prior to detection, can be used directly to benefit safeguards needs. In this paper we describe a development of a fast‑neutron based safeguards assay system designed for the assessment of 235 U content in fresh fuel. The system benefits from real‑time pulse‑shape discrimination processing and auto‑calibration of the detector system parameters to ensure a rapid and effective set‑up protocol. These requirements are essential in optimising the speed and limit of detection of the fast neutron technique, whilst minimising the intervention needed to perform the assay.

  12. Fast neutron scattering near shell closures: Scandium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1992-08-01

    Neutron differential elastic- and inelastic-scattering cross sections are measured from ∼ 1.5 to 10 MeV with sufficient detail to define the energy-averaged behavior of the scattering processes. Neutrons corresponding to excitations of 465 ± 23, 737 ± 20, 1017 ± 34, 1251 ± 20, 1432 ± 23 and 1692 ± 25 keV are observed. It is shown that the observables, including the absorption cross section, are reasonably described with a conventional optical-statistical model having energy-dependent geometric parameters. These energy dependencies are alleviated when the model is extended to include the contributions of the dispersion relationship. The model parameters are conventional, with no indication of anomalous behavior of the neutron interaction with 45 Sc, five nucleons from the doubly closed shell at 40 Ca

  13. Fast-neutrons incident on rotors: Tantalum

    International Nuclear Information System (INIS)

    Smith, Alan B.

    2005-01-01

    Mono-energetic neutrons are elastically and inelastically scattered from elemental tantalum at incident energies of ∼0.3-10.0 MeV. These experimental results are augmented with neutron total-cross-section and additional neutron-scattering data from the literature to form a composite experimental database. The latter is interpreted in the context of optical-statistical and coupled-channels models, including consideration of collective rotations, dispersion effects and other physical properties. The results are compared with those of similar processes in this region of collective nuclei. A regional model is proposed for the interpretation and prediction of such interactions. The model and the experimental results are compared with corresponding values given in ENDF/B-VI

  14. ISINN-3. Neutron spectroscopy, nuclear structure, related topics

    International Nuclear Information System (INIS)

    1995-01-01

    The proceedings contain the materials presented at the Third International Seminar on Neutron-Nucleus Interactions (ISINN-3) dealing with the problems of neutron spectroscopy, nuclear structure and related topics. The Seminar took place in Dubna on April 26-28, 1995. Over 100 scientists from Belgium, Bulgaria, Czech Republic, Germany, Japan, Latvia, Mexico, Poland, Slovakia, Ukraine, USA and from more than 10 Russian research institutes took part in the Seminar. The Seminar is dedicated to the memory of the founder of the Neutron Physics Laboratory of JINR, the famous soviet scientist Professor Fedor L. Shapiro, whose 80th anniversary is being observed. The main problems discussed are the following: fundamental interactions and symmetries in neutron-induced reactions, fundamental properties of the neutron, properties of excited nuclei after neutron capture and some other ones. Special emphasis is laid upon γ decay and neutron induced nuclear fission as well as upon the methodical aspects of new experiments

  15. Fast neutron dose equivalent rates in heavy ion target areas

    International Nuclear Information System (INIS)

    Fulmer, C.B.; Butler, H.M.; Ohnesorge, W.F.; Mosko, S.W.

    1978-01-01

    At heavy ion accelerators, personnel access to areas near the target is sometimes important for successful performance of experiments. Radiation levels determine the amount of time that can be spent in these areas without exceeding maximum permissible exposures. Inasmuch as the fast neutrons contribute the major part of the Rem dose rates in these areas, knowledge of the fast neutron levels is important for planning permissive entry to target areas. Fast neutron dose rates were measured near thick medium mass targets bombarded with beams of C, N, O, and Ne ions. beam energies ranged from 3 to 16 MeV/amu. Dose rates (mrem/h) 1 meter from the target 90 degrees from the beam direction range from approx. 0.05 at MeV/amu to approx. 50 at 16 MeV/amu. These data should be helpful in planning permissive entry to heavy ion target areas

  16. Fast neutron dose equivalent rates in heavy ion target areas

    Energy Technology Data Exchange (ETDEWEB)

    Fulmer, C.B.; Butler, H.M.; Ohnesorge, W.F.; Mosko, S.W.

    1978-01-01

    At heavy ion accelerators, personnel access to areas near the target is sometimes important for successful performance of experiments. Radiation levels determine the amount of time that can be spent in these areas without exceeding maximum permissible exposures. Inasmuch as the fast neutrons contribute the major part of the Rem dose rates in these areas, knowledge of the fast neutron levels is important for planning permissive entry to target areas. Fast neutron dose rates were measured near thick medium mass targets bombarded with beams of C, N, O, and Ne ions. beam energies ranged from 3 to 16 MeV/amu. Dose rates (mrem/h) 1 meter from the target 90 degrees from the beam direction range from approx. 0.05 at MeV/amu to approx. 50 at 16 MeV/amu. These data should be helpful in planning permissive entry to heavy ion target areas.

  17. Measurements of fast neutrons by bubble detectors

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, F.; Martinez, H. [Laboratorio de Espectroscopia, Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251, Cuernavaca Morelos (Mexico); Leal, B. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Ciudad Universitaria, Mexico D. F. (Mexico); Rangel, J. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Ciudad Universitaria, Mexico D. F (Mexico); Reyes, P. G. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario 100, Col. Centro, 50000, Toluca Estado de Mexico (Mexico)

    2013-07-03

    Neutron bubble detectors have been studied using Am-Be and D-D neuron sources, which give limited energy information. The Bubble Detector Spectrometer (BDS) have six different energy thresholds ranging from 10 KeV to 10 Mev. The number of bubbles obtained in each measurement is related to the dose (standardized response R) equivalent neutrons through sensitivity (b / {mu}Sv) and also with the neutron flux (neutrons per unit area) through a relationship that provided by the manufacturer. Bubble detectors were used with six different answers (0.11 b/ {mu}Sv, 0093 b/{mu}Sv, 0.14 b/{mu}Sv, 0.17 b/{mu}Sv, 0051 b/{mu}Sv). To test the response of the detectors (BDS) radiate a set of six of them with different energy threshold, with a source of Am-Be, placing them at a distance of one meter from it for a few minutes. Also, exposed to dense plasma focus Fuego Nuevo II (FN-II FPD) of ICN-UNAM, apparatus which produces fusion plasma, generating neutrons by nuclear reactions of neutrons whose energy emitting is 2.45 MeV. In this case the detectors were placed at a distance of 50 cm from the pinch at 90 Degree-Sign this was done for a certain number of shots. In both cases, the standard response is reported (Dose in {mu}Sv) for each of the six detectors representing an energy range, this response is given by the expression R{sub i}= B{sub i} / S{sub i} where B{sub i} is the number of bubbles formed in each and the detector sensitivity (S{sub i}) is given for each detector in (b / {mu}Sv). Also, reported for both cases, the detected neutron flux (n cm{sup -2}), by a given ratio and the response involves both standardized R, as the average cross section sigma. The results obtained have been compared with the spectrum of Am-Be source. From these measurements it can be concluded that with a combination of bubble detectors, with different responses is possible to measure the equivalent dose in a range of 10 to 100 {mu}Sv fields mixed neutron and gamma, and pulsed generated fusion

  18. Fast neutron capture cross section facility at Cadarache

    International Nuclear Information System (INIS)

    Le Rigoleur, C.; Arnaud, A.

    1975-01-01

    The total energy weighting technique has been applied to measure absolute fast neutron capture cross section at Cadarache. We use a non hydrogeneous liquid scintillator to detect the gamma from the cascade. The neutron flux is measured with a B 10 INa(Tl) detector or Li 6 glass scintillator of well known efficiency. Time of flight technique is used with on line digital computer data processing. (orig.) [de

  19. Fast neutron activating detectors for pulsed flow measurements

    International Nuclear Information System (INIS)

    Dyatlov, V.D.; Kunaev, G.T.; Popytaev, A.N.; Cheremukhov, B.V.

    1979-01-01

    The requirements to the activation detectors of the pulsed flows of the fast neutrons are considered; the criteria of optimum measurement time, geometrical moderator sizes and radioactive detector element properties have been obtained. On their analysis parameter selection has been carried out. The neutron detector to register the short pulses has been designed and calibrated. The ways of further increase of sensitivity and efficiency of such detectors are discussed

  20. Transportable, Low-Dose Active Fast-Neutron Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mihalczo, John T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wright, Michael C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McConchie, Seth M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Archer, Daniel E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Palles, Blake A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    This document contains a description of the method of transportable, low-dose active fast-neutron imaging as developed by ORNL. The discussion begins with the technique and instrumentation and continues with the image reconstruction and analysis. The analysis discussion includes an example of how a gap smaller than the neutron production spot size and detector size can be detected and characterized depending upon the measurement time.

  1. Wide-range scintillation spectrometer of fast neutrons

    International Nuclear Information System (INIS)

    Blinov, M.V.; Gavrilov, B.P.; Ivannikova, L.L.; Kozulin, Eh.M.; Mozhaev, A.N.; Saidgareev, V.M.; Tyurin, G.P.

    1984-01-01

    A spectrometer of fast neutrons developed on the base of stilbene crystas and permitting to detect neutrons simultaneously by time-of-flight and recoil protons with analysis of pulse shape in the 0.5-50 MeV energy range is described. The detecting part is performed in the CAMAC standard. The ''Minsk-32'' computer was used for data storage and preliminary processing

  2. Coupled hydro-neutronic calculations for fast burst reactor accidents

    International Nuclear Information System (INIS)

    Paternoster, R.; Kimpland, R.; Jaegers, P.; McGhee, J.

    1994-01-01

    Methods are described for determining the fully coupled neutronic/hydrodynamic response of fast burst reactors (FBR) under disruptive accident conditions. Two code systems, PAD (1 -D Lagrangian) and NIKE-PAGOSA (3-D Eulerian) were used to accomplish this. This is in contrast to the typical methodology that computes these responses by either single point kinetics or in a decoupled manner. This methodology is enabled by the use of modem supercomputers (CM-200). Two examples of this capability are presented: an unreflected metal fast burst assembly, and a reflected fast burst assembly typical of the Skua or SPR-III class of fast burst reactor

  3. Fast neutron radiotherapy: for equal or for better

    International Nuclear Information System (INIS)

    Broerse, J.J.; Battermann, J.J.

    1981-01-01

    The renewed application of fast neutrons in clinical radiotherapy has been stimulated by fundamental radiobiological findings. The biological effects of high LET radiation, including fast neutrons, are different from those obtained with x rays in at least three respects: the oxygen enhancement ratio, the sensitivity of cells at different phases of the cell cycle, and the contribution of sublethal damage to cell reproductive death. Furthermore, wide variations in relative biological effectiveness (RBE) have been observed for different tumors and normal tissues. Measurements of volume changes in human pulmonary metastases indicate that the RBE for slowly growing tumors which are generally well-differentiated is higher than that for poorly differentiated lesions. Six thousand patients have now been treated with fast neutron beams. The results of the clinical applications vary according to the method of application and to the type of cancer involved: treatment of inoperable malignancies of the salivary gland is very encouraging: the therapeutic gain is rather small for bladder and rectal cancers, soft tissue sarcomas and advanced carcinomas of the cervix; the responses of brain tumors are very disappointing. Most neutron radiotherapy applications have been less than optimal because of inadequate physical and technical conditions. Despite these difficulties, some interesting clinical data have become available. Due to the technical shortcomings, the possible advantages of fast neutrons are probably underestimated for many tumor sites. Well-designed clinical trials, preferably performed with high energy cyclotrons in clinical environments, will provide a decisive answer to the question of the usefulness of the new radiation modality

  4. Neutron gamma competition in fast fission

    International Nuclear Information System (INIS)

    Frehaut, J.

    1989-01-01

    In the present paper we analyse the data we have obtained on the distribution of the gamma-ray energy per fission, as well as on the average energy E-barγ released per fission for the neutron induced fission of several isotopes, in the energy range up to 15 MeV. 6 refs, 9 figs

  5. Fast Neutron Dose Distribution in a Linac Radiotherapy Facility

    International Nuclear Information System (INIS)

    Al-Othmany, D.Sh.; Abdul-Majid, S.; Kadi, M.W.

    2011-01-01

    CR-39 plastic detectors were used for fast neutron dose mapping in the radiotherapy facility at King AbdulAziz University Hospital (KAUH). Detectors were calibrated using a 252 Cf neutron source and a neutron dosimeter. After exposure chemical etching was performed using 6N NaOH solution at 70 degree C. Tracks were counted using an optical microscope and the number of tracks/cm 2 was converted to a neutron dose. 15 track detectors were distributed inside and outside the therapy room and were left for 32 days. The average neutron doses were 142.3 mSv on the accelerator head, 28.5 mSv on inside walls, 1.4 mSv beyond the beam shield, and 1 mSv in the control room

  6. Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

    Science.gov (United States)

    Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

    2013-10-01

    Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

  7. Neutron cross section measurements for the Fast Breeder Program

    International Nuclear Information System (INIS)

    Block, R.C.

    1979-06-01

    This research was concerned with the measurement of neutron cross sections of importance to the Fast Breeder Reactor. The capture and total cross sections of fission products ( 101 102 104 Ru, 143 145 Nd, 149 Sm, 95 97 Mo, Cs, Pr, Pd, 107 Pd, 99 Tc) and tag gases (Kr, 78 80 Kr) were measured up to 100 keV. Filtered neutron beams were used to measure the capture cross section of 238 U (with an Fe filter) and the total cross section of Na (with a Na filter). A radioactive neutron capture detector was developed. A list of publications is included

  8. Transparent fast neutron shielding material and shielding method

    International Nuclear Information System (INIS)

    Nashimoto, Tetsuji; Katase, Haruhisa.

    1993-01-01

    Polyisobutylene having a viscosity average molecular weight of 20,000 to 80,000 and a hydrogen atom density of greater than 7.0 x 10 22 /cm 3 is used as a fast neutron shielding material. The shielding material is excellent in the shielding performance against fast neutrons, and there is no worry of leakage even when holes should be formed to a vessel. Further, it is excellent in fabricability, relatively safe even upon occurrence of fire and, in addition, it is transparent to enable to observe contents easily. (T.M.)

  9. Fast infrared spectroscopy in supercritical fluids

    International Nuclear Information System (INIS)

    Sun, X.

    2000-05-01

    the relative wavelength of the visible absorption maximum for Cr(CO) 5 Xe and Cr(CO) 5 (CO 2 ) all indicate a similar strength of interaction for Xe and CO 2 with the M(CO) 5 moiety. Chapter 4: Step-scan fourier transform time resolved infrared spectroscopy. In this chapter, conventional FTIR spectroscopy is introduced. Four methods of applying FTIR for time-resolved studies, i.e., rapid-scan FTIR, synchronous rapid-scan FTIR, asynchronous rapid-scan FTIR, and step-scan time-resolved FTIR are described. The using the step-scan FTIR spectrometer (Nicolet 860) in Nottingham for fast time resolved measurements is discussed. Time-resolved measurements on the photochemistry of [CpFe(CO) 2 ] 2 and Ciba Irgacure 184 in n-heptane solution show that this apparatus offers high spectral resolution, high sensitivity and fast time resolution. Chapter 5: Photochemistry of [CpMo(CO) 3 ] 2 and [Cp*Fe(CO) 2 ] 2 in supercritical CO 2 . This is the first study of the photochemistry of organometallic dimers in supercritical CO 2 . Radicals generated from visible (532nm) photolysis of [CpMo(CO) 3 ] 2 in scCO 2 , scXe, and n-heptane solution pressurised with CO 2 have been identified with ν(CO) bands. Three ν(CO) bands observed in scCO 2 and n-heptane solution pressurised with CO 2 , indicate coordination between Mo and CO 2 . A similar study with photolysis (532nm) of [Cp*Fe(CO) 2 ] 2 in scCO 2 finds no evidence of possible coordination between Fe and CO 2 . Radical recombination in scCO 2 is a second-order reaction. Study on pressure dependence of radical recombination rate shows no evidence of solvation enhancement on reaction rate in scCO 2 since the second-order rate constant is well below the diffusion controlled limit. lsomerisation of gauche-[CpMo(CO) 3 ] 2 and cis-[Cp*Fe(CO) 3 ] 2 is independent of the pressure of the solution. No cage effect is observed on the time scale of this measurement. Appendix: Three papers are attached outlining the work that I have completed during my

  10. Measurement of fast neutron spectra. 1-2

    International Nuclear Information System (INIS)

    Kimura, Itsuro

    1976-01-01

    The present status of the techniques for the measurement of fast neutron spectra is reviewed with particular attention to the recent activities in Japan. The first section of this report defines the energy range of fast neutrons, and various techniques are classified into four groups. In the following sections, recent development in each group is reviewed. The first part is the integral method represented mainly by the activation method. The variation of this method is shortly reviewed, and some results of the spectrum measurement for JRR-4 (a thermal research reactor) and YAYOI (a fast neutron source reactor) are presented together with the results of computed spectra. The second part is the method of proton recoil. The improvement of a proportional counter by Ichimori is shortly reviewed. The use of liquid scintillator is also discussed together with the experimental and computational results of YAYOI benchmark spectra of fast neutrons transmitted through the layers of iron. The utilization of n-α or n-p reaction as a sandwitch counter is discussed in the third part. Measured and calculated spectra in the FCA (a fast critical assembly) core are presented as examples. The method of time-of-flight is discussed in the fourth part. Recent developments in Japan such as the method with a double-scintillation counter are shortly presented together with its block diagram. (Aoki, K.)

  11. Neutron absorption spectroscopy for identification of light elements in actinides

    Energy Technology Data Exchange (ETDEWEB)

    Hau, I.D. [Lawrence Livermore National Laboratory, Advanced Detector Group, 7000 East Ave., L-270, Livermore, CA 94550 (United States) and Department of Nuclear Engineering, University of California Berkeley, Berkeley, CA 94720 (United States)]. E-mail: hau2@llnl.gov; Niedermayr, T.R. [Lawrence Livermore National Laboratory, Advanced Detector Group, 7000 East Ave., L-270, Livermore, CA 94550 (United States); Drury, O.B. [Lawrence Livermore National Laboratory, Advanced Detector Group, 7000 East Ave., L-270, Livermore, CA 94550 (United States); Burger, A. [Fisk University, 1000 17th Ave. North, Nashville, TN 37208 (United States); Bell, Z. [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831 (United States); Friedrich, S. [Lawrence Livermore National Laboratory, Advanced Detector Group, 7000 East Ave., L-270, Livermore, CA 94550 (United States)]. E-mail: friedrich1@llnl.gov

    2006-04-15

    We are developing cryogenic high-energy resolution fast-neutron spectrometers using superconducting transition-edge sensors (TES) for nuclear science and non-proliferation applications. Fast neutrons are absorbed in 94% enriched {sup 6}LiF single crystals with volumes of {approx}1 cm{sup 3} in an exothermic {sup 6}Li(n,{alpha}){sup 3}H capture reaction. The neutron energy is measured from the subsequent temperature rise with a Mo/Cu multilayer TES. Fast-neutron spectra from a {sup 252}Cf source show an energy resolution of 55 kev. Here, we discuss the instrument performance, with emphasis on the identification of light elements in actinide matrices.

  12. Transmutation of Americium in Fast Neutron Facilities

    OpenAIRE

    Zhang, Youpeng

    2011-01-01

    In this thesis, the feasibility to use a medium sized sodium cooled fast reactor fully loaded with MOX fuel for efficient transmutation of americium is investigated by simulating the safety performance of a BN600-type fast reactor loaded with different fractions of americium in the fuel, using the safety parameters obtained with the SERPENT Monte Carlo code. The focus is on americium mainly due to its long-term contribution to the radiotoxicity of spent nuclear fuel and its deterioration on c...

  13. Fast neutron spectrometry by bolometers lithium target for the reduction of background experiences of direct detection of dark matter

    International Nuclear Information System (INIS)

    Gironnet, J.

    2010-01-01

    Fast neutron spectrometry is a common interest for both direct dark matter detection and for nuclear research centres. Fast neutrons are usually detected indirectly. Neutrons are first slowed down by moderating materials for being detected in low energy range. Nevertheless, these detection techniques are and are limited in energy resolution. A new kind of fast neutron spectroscopy has been developed at the Institut d'Astrophysique Spatiale (IAS) in the aim of having a better knowledge of neutron backgrounds by the association of the bolometric technique with neutron sensitive crystals containing Li. Lithium-6 is indeed an element which has one the highest cross section for neutron capture with the 6 Li(n,α) 3 H reaction. This reaction releases 4,78 MeV tagging energetically each neutron capture. In particular for fast neutrons, the total energy measured by the bolometer would be the sum of this energy reaction and of the incoming fast neutron energy. To validate this principle, a spectrometer for fast neutrons, compact and semi-transportable, was built in IAS. This cryogenic detector, operated at 300 - 400 mK, consists of a 0.5 g LiF 95% 6 Li enriched crystal read out by a NTD-Ge sensor. This PhD thesis was on the study of the spectrometer characteristics, from the first measurements at IAS, to the measurements in the nuclear research centre of the Paul Scherrer Institute (PSI) until the final calibration with the Amande instrument of the Institut de Radioprotection et de Surete Nucleaire (IRSN). (author)

  14. Fast neutron biological effects on normal and tumor chromatin

    International Nuclear Information System (INIS)

    Constantinescu, B.; Bugoi, Roxana; Paunica, Tatiana; Radu, Liliana

    1997-01-01

    Growing interest in neutron therapy and radioprotection requires complex studies on the mechanisms of neutron action on biological systems, especially on chromatin (the complex of deoxyribonucleic acid-DNA- with proteins in eukaryotic cells). Our study aims to investigate the fast neutrons induced damages in normal and tumor chromatin, studying thermal transition, intrinsic fluorescence and fluorescence of chromatin-ethidium bromide complexes behavior versus irradiation dose. The Bucharest U-120 variable energy Cyclotron was employed as an intense source of fast neutrons produced by 13.5 MeV deuterons on a thick beryllium target (166.5 mg/cm 2 ) placed at 20 angle against the incident beam. The average energy is 5.24 MeV. The total yield at 0 angle is 6.7 x 10 16 n/sr·C·MeV. To determine neutron and gamma irradiation doses, home made thermoluminescent detectors-TLD(γ) and TLD (γ + n) were used: for gamma MgF 2 : Mn mixed with Teflon pellets (φ 12.5 mm, 0.6±0.1 mm thick) and for gamma plus neutrons MgF 2 :Mn mixed with 6 LiF and Teflon pellets (same dimensions). Using a 8.022 x 10 -2 albedo factor value and the equivalence 1Gy (n)=2·10 10 fast neutron/cm 2 , the dose for the irradiation of 1.2 x 10 2 Gy/μC, with an estimated precision of 15% C for neutrons and 7.8 x 10 -4 Gy/μC for gamma, at 10 cm behind Be target, was found, respectively. A diminution of the negative fluorescence intensity for chromatin-ethidium bromide complexes with the increasing of neutron dose (from 0.98 at 5 Gy to 0.85 at 100 Gy) was observed for normal chromatin. This fact reflects chromatin DNA injuries, with the decrease of double helix DNA proportion. To study the influence of gyrostan, thyroxine and D3 vitamin treatments on fast neutron radiolysis in tumor chromatin,10 mg/kg of anticancer drug gyrostan, 40μg/kg of hormonal compound thyroxine and 30,000 IU/kg of D3 vitamin were administrated, separately or associated, to Wistar rats bearing Walker carcinosarcoma. Representing

  15. An empirical formula for scattered neutron components in fast neutron radiography

    International Nuclear Information System (INIS)

    Dou Haifeng; Tang Bin

    2011-01-01

    Scattering neutrons are one of the key factors that may affect the images of fast neutron radiography. In this paper, a mathematical model for scattered neutrons is developed on a cylinder sample, and an empirical formula for scattered neutrons is obtained. According to the results given by Monte Carlo methods, the parameters in the empirical formula are obtained with curve fitting, which confirms the logicality of the empirical formula. The curve-fitted parameters of common materials such as 6 LiD are given. (authors)

  16. The investigation of fast neutron Threshold Activation Detectors (TAD)

    International Nuclear Information System (INIS)

    Gozani, T; King, M J; Stevenson, J

    2012-01-01

    The detection of fast neutrons is usually done by liquid hydrogenous organic scintillators, where the separation between the ever present gamma rays and neutrons is achieved by the pulse shape discrimination (PSD). In many practical situation the detection of fast neutrons has to be carried out while the intense source (be it neutrons, gamma rays or x-rays) that creates these neutrons, for example by the fission process, is present. This source, or ''flash'', usually blinds the neutron detectors and temporarily incapacitates them. By the time the detectors recover the prompt neutron signature does not exist. Thus to overcome the blinding background, one needs to search for processes whereby the desired signature, such as fission neutrons could in some way be measured long after the fission occurred and when the neutron detector is fully recovered from the overload. A new approach was proposed and demonstrated a good sensitivity for the detection of fast neutrons in adverse overload situations where normally it could not be done. A temporal separation of the fission event from the prompt neutrons detection is achieved via the activation process. The main idea, called Threshold Activation Detection (or detector)-TAD, is to find appropriate substances that can be selectively activated by the fission neutrons and not by the source radiation, and then measure the radioactively decaying activation products (typically beta and γ-rays) well after the source pulse has ended. The activation material should possess certain properties: a suitable half-life; an energy threshold below which the numerous source neutrons will not activate it (e.g. about 3 MeV); easily detectable activation products and has a usable cross section for the selected reaction. Ideally the substance would be part of the scintillator. There are several good candidates for TAD. The first one we have selected is based on fluorine. One of the major advantages of this element is the fact that it is a major

  17. The investigation of fast neutron Threshold Activation Detectors (TAD)

    Science.gov (United States)

    Gozani, T.; King, M. J.; Stevenson, J.

    2012-02-01

    The detection of fast neutrons is usually done by liquid hydrogenous organic scintillators, where the separation between the ever present gamma rays and neutrons is achieved by the pulse shape discrimination (PSD). In many practical situation the detection of fast neutrons has to be carried out while the intense source (be it neutrons, gamma rays or x-rays) that creates these neutrons, for example by the fission process, is present. This source, or ``flash'', usually blinds the neutron detectors and temporarily incapacitates them. By the time the detectors recover the prompt neutron signature does not exist. Thus to overcome the blinding background, one needs to search for processes whereby the desired signature, such as fission neutrons could in some way be measured long after the fission occurred and when the neutron detector is fully recovered from the overload. A new approach was proposed and demonstrated a good sensitivity for the detection of fast neutrons in adverse overload situations where normally it could not be done. A temporal separation of the fission event from the prompt neutrons detection is achieved via the activation process. The main idea, called Threshold Activation Detection (or detector)-TAD, is to find appropriate substances that can be selectively activated by the fission neutrons and not by the source radiation, and then measure the radioactively decaying activation products (typically beta and γ-rays) well after the source pulse has ended. The activation material should possess certain properties: a suitable half-life; an energy threshold below which the numerous source neutrons will not activate it (e.g. about 3 MeV); easily detectable activation products and has a usable cross section for the selected reaction. Ideally the substance would be part of the scintillator. There are several good candidates for TAD. The first one we have selected is based on fluorine. One of the major advantages of this element is the fact that it is a major

  18. The interaction of fast neutrons with hafnium

    International Nuclear Information System (INIS)

    Smith, A.B.

    2002-01-01

    Elemental hafnium neutron total cross sections are measured from ∼0.75 to 4.5 MeV in steps of ∼40 keV. Differential neutron elastic-scattering cross sections are measured from ∼4.5 to 10.0 MeV in ∼0.5 MeV steps and at 40 scattering angles distributed between ∼17 and 160 deg. These data are combined with those found in the literature to construct a comprehensive experimental data base which is interpreted in terms of coupled-channels models. Physical characteristics of the resulting potentials are discussed. Comparisons are made with ENDF/B-6 (MAT 7200). A detailed report of this work is given by Smith (Smith, A., 2001. Argonne National Laboratory Report ANL/NDM-153)

  19. Improved Delayed-Neutron Spectroscopy Using Trapped Ions

    Energy Technology Data Exchange (ETDEWEB)

    Norman, Eric

    2018-04-24

    The neutrons emitted following the  decay of fission fragments (known as delayed neutrons because they are emitted after fission on a timescale of the -decay half-lives) play a crucial role in reactor performance and control. Reviews of delayed-neutron properties highlight the need for high-quality data for a wide variety of delayed-neutron emitters to better understand the timedependence and energy spectrum of the neutrons as these properties are essential for a detailed understanding of reactor kinetics needed for reactor safety and to understand the behavior of these reactors under various accident and component-failure scenarios. For fast breeder reactors, criticality calculations require accurate delayed-neutron energy spectra and approximations that are acceptable for light-water reactors such as assuming the delayed-neutron and fission-neutron energy spectra are identical are not acceptable and improved -delayed neutron data is needed for safety and accident analyses for these reactors. With improved nuclear data, the delayedneutrons flux and energy spectrum could be calculated from the contributions from individual isotopes and therefore could be accurately modeled for any fuel-cycle concept, actinide mix, or irradiation history. High-quality -delayed neutron measurements are also critical to constrain modern nuclear-structure calculations and empirical models that predict the decay properties for nuclei for which no data exists and improve the accuracy and flexibility of the existing empirical descriptions of delayed neutrons from fission such as the six-group representation

  20. Fast neutron scattering on actinide nuclei

    International Nuclear Information System (INIS)

    1982-01-01

    More and more sophisticated neutron experiments have been carried out with better samples in several laboratories and it was necessary to intercompare them. In this respect, let us quote for example (n,n'e) and (n,n'#betta#) measurements. Moreover, high precision (p,p), (p,p') and (p,n) measurements have been made, thus supplementing neutron experiments in the determination of the parameters of the optical model, still widely used to describe the neutron-nucleus interaction. The optical model plays a major role and it is therefore essential to know it well. The spherical optical model is still very useful, especially because of its simplicity and of the relatively short calculation times, but is obviously insufficient to treat deformed nuclei such as actinides. For accurate calculations about these nuclei, it is necessary to use a deformed potential well and solve a set of coupled equations, hence long computational times. The importance of compound nucleus formation at low energy requires also a good knowledge of the statistical model together with that of all the reaction mechanisms which are involved, including fission for which an accurate barrier is necessary and, of course, well-adjusted level densities. The considerations form the background of the Scientific Programme set up by a Programme Committee whose composition is given further on in this book

  1. The risk from fast neutron exposure

    International Nuclear Information System (INIS)

    Bond, V.P.

    1979-01-01

    The conclusions and recommendations made by Rossi and Mays in recent papers (Rad. Res. 71, 1, 1977; Rad. Environ. Biophys. 14, 275, 1977; Health Phys. 34, 353, 1978), based on their analysis of recent Japanese data are discussed. They imply that the risk associated with the current annual dose equivalent limit of 5 rem for all radiations is unacceptably high, that this limit must be reduced by a factor of 10 or more, and that the conservative linear, no threshold hypothesis must be abandoned. It is shown in this paper that these recommendations are not supported by the newly-analyzed neutron data, and certainly cannot be applied selectively to the annual absorbed dose limit for neutrons. In particular the judgement that the risk of an annual exposure from 0.5 rad (5 rem) of neutrons is unacceptably high, is a personal opinion of the authors, and does not necessarily follow either from the assumption of a linear-quadratic dose effect relation for low-LET radiation or from other radiobiological considerations. At issue is the level of risk that is to be considered 'acceptable', a question that is societal and thus not resolvable on purely technical or scientific grounds. (author)

  2. Fast ultrasonic visualisation under sodium. Application to the fast neutron reactors

    International Nuclear Information System (INIS)

    Imbert, Ch.

    1997-01-01

    The fast ultrasonic visualization under sodium is in the programme of research and development on the inspection inside the fast neutron reactors. This work is about the development of a such system of fast ultrasonic imaging under sodium, in order to improve the existing visualization systems. This system is based on the principle of orthogonal imaging, it uses two linear antennas with an important dephasing having 128 piezo-composite elements of central frequency equal to 1.6 MHz. (N.C.)

  3. He-4 fast neutron detectors in nuclear security applications

    International Nuclear Information System (INIS)

    Murer, D. E.

    2014-01-01

    This work presents studies of "4He fast neutron detectors for nuclear security applications. Such devices are high pressure gas scintillation detectors, sensitive to neutrons in the energy range of fission sources. First, an introduction to the scope of the intended application is given. This is followed by a description of all components relevant to the operation of the detector. The next chapter presents studies of various characteristics of the neutron detector, among them properties of its scintillation response, differences between neutron and gamma interactions and effects of the light collection process. The results of the detector characterization are used to develop neutron gamma discrimination methods. These methods are put to the test using measurements with a high gamma flux, and the results are compared to performance requirements of Radiation Portal Monitors. Background neutron measurements are presented next. Measured neutron rates are compared to values published in scientific literature. The fluctuation of the background count rate was studied, and the contribution of muons evaluated. Two applications of the detectors in the field of nuclear security are discussed in the last two chapters. The first one is a novel method to measure the plutonium mass in a container filled with Mixed Oxide Fuel. The last chapter presents the development of a Radiation Portal Monitor which, in addition to neutron and gamma counting, exploits time correlation to detect threats such as plutonium and "6"0Co. (author)

  4. He-4 fast neutron detectors in nuclear security applications

    Energy Technology Data Exchange (ETDEWEB)

    Murer, D. E.

    2014-07-01

    This work presents studies of {sup 4}He fast neutron detectors for nuclear security applications. Such devices are high pressure gas scintillation detectors, sensitive to neutrons in the energy range of fission sources. First, an introduction to the scope of the intended application is given. This is followed by a description of all components relevant to the operation of the detector. The next chapter presents studies of various characteristics of the neutron detector, among them properties of its scintillation response, differences between neutron and gamma interactions and effects of the light collection process. The results of the detector characterization are used to develop neutron gamma discrimination methods. These methods are put to the test using measurements with a high gamma flux, and the results are compared to performance requirements of Radiation Portal Monitors. Background neutron measurements are presented next. Measured neutron rates are compared to values published in scientific literature. The fluctuation of the background count rate was studied, and the contribution of muons evaluated. Two applications of the detectors in the field of nuclear security are discussed in the last two chapters. The first one is a novel method to measure the plutonium mass in a container filled with Mixed Oxide Fuel. The last chapter presents the development of a Radiation Portal Monitor which, in addition to neutron and gamma counting, exploits time correlation to detect threats such as plutonium and {sup 60}Co. (author)

  5. ISINN-2. Neutron spectroscopy, nuclear structure and related topics

    International Nuclear Information System (INIS)

    1994-01-01

    The proceedings contain the materials presented at the Second International Seminar on Neutron-Nucleus Interactions (ISINN-2) dealing with the problems of neutron spectroscopy, nuclear structure and related topics. The Seminar took place in Dubna on April 26-28, 1994. Over 120 scientists from Belgium, Bulgaria, Czech Republic, Germany, Holland, Italy, Japan, Latvia, Mexico, Poland, Slovakia, Slovenia, Ukraine, US and about 10 Russian research institutes took part in the Seminar. The main problems discussed are the following: P-odd and P-even angular correlation and T-reversal invariance in neutron reactions, nuclear structure investigations by neutron capture, the mechanism of neutron reactions, nuclear fission processes, as well as neutron data for nuclear astrophysics

  6. Detection of land mines using fast and thermal neutron analysis

    International Nuclear Information System (INIS)

    Bach, P.

    1998-01-01

    The detection of land mines is made possible by using nuclear sensor based on neutron interrogation. Neutron interrogation allows to detect the sensitive elements (C, H, O, N) of the explosives in land mines or in unexploded shells: the evaluation of characteristic ratio N/O and C/O in a volume element gives a signature of high explosives. Fast neutron interrogation has been qualified in our laboratories as a powerful close distance method for identifying the presence of a mine or explosive. This method could be implemented together with a multisensor detection system - for instance IR or microwave - to reduce the false alarm rate by addressing the suspected area. Principle of operation is based on the measurement of gamma rays induced by neutron interaction with irradiated nuclei from the soil and from a possible mine. Specific energy of these gamma rays allows to recognise the elements at the origin of neutron interaction. Several detection methods can be used, depending on nuclei to be identified. Analysis of physical data, computations by simulation codes, and experimentations performed in our laboratory have shown the interest of Fast Neutron Analysis (FNA) combined with Thermal Neutron Analysis (TNA) techniques, especially for detection of nitrogen 14 N, carbon 12 C and oxygen 16 O. The FNA technique can be implemented using a 14 MeV sealed neutron tube, and a set of detectors. The mines detection has been demonstrated from our investigations, using a low power neutron generator working in the 10 8 n/s range, which is reasonable when considering safety rules. A fieldable demonstrator would be made with a detection head including tube and detectors, and with remote electronics, power supplies and computer installed in a vehicle. (author)

  7. Neutronics methods for transient and safety analysis of fast reactors

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, Marco

    2017-07-01

    Modeling the evolution of possible or postulated accidents in nuclear reactors is fundamental in designing safe systems. For the next generation of reactors, in particular fast reactors, fuel movement during an accident can, in principle, drive an energetic event. Such is the issue of recriticality. The thermal energy produced during these events will, possibly, be converted into mechanical energy by some mechanisms. For example, the nuclear heat deposited in the fuel could cause fuel vaporization and its subsequent expansion. This movement would accelerate the surrounding sodium: part of the initial energy in the fuel is thus converted into sodium kinetic energy. This mechanical energy will finally be absorbed, in some way or another, by the reactor vessel. Providing an accurate estimate for the maximum mechanical work that any accidental sequence can do onto the reactor vessel is an essential step in designing a reactor containment that would withstand any load generated by any accident. That would assure accident containment, without consequences for the general public. Fast reactor accident modeling is a complicated task. The outcome of an accident is determined by different physical phenomena, all acting at almost the same time. Safety analysts must track all these different phenomena. Multi-physics codes have been developed for this task. They must contain accurate models for fluid-dynamics, neutronics, and structures. This work has to do with neutronics modeling of such accidents. Past and recent analyses have been limited to the approximate description of the neutronic field, for example by using a rough description of the energy and/or of the angular dependence of the neutron flux. In this work, different neutronic solvers are selected and coupled into a general multi-physics code for fast reactor accident analysis. Performances of each of them is then assessed. Some emphasis has been put also in assessing the speed of these solvers for determining the

  8. Fast Neutron Emission Tomography of Used Nuclear Fuel Assemblies

    Science.gov (United States)

    Hausladen, Paul; Iyengar, Anagha; Fabris, Lorenzo; Yang, Jinan; Hu, Jianwei; Blackston, Matthew

    2017-09-01

    Oak Ridge National Laboratory is developing a new capability to perform passive fast neutron emission tomography of spent nuclear fuel assemblies for the purpose of verifying their integrity for international safeguards applications. Most of the world's plutonium is contained in spent nuclear fuel, so it is desirable to detect the diversion of irradiated fuel rods from an assembly prior to its transfer to ``difficult to access'' storage, such as a dry cask or permanent repository, where re-verification is practically impossible. Nuclear fuel assemblies typically consist of an array of fuel rods that, depending on exposure in the reactor and consequent ingrowth of 244Cm, are spontaneous sources of as many as 109 neutrons s-1. Neutron emission tomography uses collimation to isolate neutron activity along ``lines of response'' through the assembly and, by combining many collimated views through the object, mathematically extracts the neutron emission from each fuel rod. This technique, by combining the use of fast neutrons -which can penetrate the entire fuel assembly -and computed tomography, is capable of detecting vacancies or substitutions of individual fuel rods. This paper will report on the physics design and component testing of the imaging system. This material is based upon work supported by the U.S. Department of Energy, Office of Defense Nuclear Nonproliferation Research and Development within the National Nuclear Security Administration, under Contract Number DE-AC05-00OR22725.

  9. ACTIV87 Fast neutron activation cross section file 1987

    International Nuclear Information System (INIS)

    Manokhin, V.N.; Pashchenko, A.B.; Plyaskin, V.I.; Bychkov, V.M.; Pronyaev, V.G.; Schwerer, O.

    1989-10-01

    This document summarizes the content of the Fast Neutron Activation Cross Section File based on data from different evaluated data libraries and individual evaluations in ENDF/B-5 format. The entire file or selective retrievals from it are available on magnetic tape, free of charge, from the IAEA Nuclear Data Section. (author)

  10. Fast neutron induced increase of flowering in portulaca grandiflora linn

    International Nuclear Information System (INIS)

    Abraham, V.; Desai, B.M.

    1975-01-01

    Unbranched cuttings were exposed to fast neutron doses of 71-284 rads and planted along with unirradiated controls. There was a significant increase in the numbers of flowers in the treated populations due to the increased production of primary and secondary branches. (MG) [de

  11. Fast neutron sensitivity of dry and germinating tomato seeds

    NARCIS (Netherlands)

    Contant, R.B.

    1970-01-01

    A study was made of changes in fast neutron effectiveness during the hydration and germination of tomato seeds. The main findings and conclusions are the following,

    Section 3.6

    Samples of unirradiated seeds and their constituent parts (seedcoat+endosperm and embryo) were taken at short

  12. Semiclassical model of cross section for fast neutrons

    International Nuclear Information System (INIS)

    Rosato, A.; D'Oliveira, A.A.

    1977-01-01

    A study for main aspects of fast neutron scattering is presented and, a semiclassical approximation applying to several pratic cases is described. The obtained results are compared with experimental data for deformed nuclei, and, with theoretical data based on optical model without treatment of deformations. (M.C.K.) [pt

  13. FERMILAB: operation resumes in meson area; fast neutron therapy

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Improvements and modifications in the Meson Area at Fermilab are described. The target train was rebuilt and energy range of some beams raised to 400 GeV with provisions for Tevatron beams of 1000 GeV in the future. The work of the fast neutron therapy facility is summarised. (W.D.L.).

  14. Basic concepts underlying fast-neutron-based contraband interrogation technology

    International Nuclear Information System (INIS)

    Fink, C.L.; Guenther, P.T.; Smith, D.L.

    1992-01-01

    All accelerator-based fast-neutron contraband interrogation systems have many closely interrelated subsystems, whose performance parameters will be critically interdependent. For optimal overall performance, a systems analysis design approach is required. This paper provides a general overview of the interrelationships and the tradeoffs to be considered for optimization of nonaccelerator subsystems

  15. Nuclear structure effects on calculated fast neutron reaction cross sections

    International Nuclear Information System (INIS)

    Avrigeanu, V.

    1992-01-01

    The importance of accurate low-lying level schemes for reaction cross section calculation and need for microscopically calculated levels are proved with reference to fast neutron induced reactions in the A = 50 atomic mass range. The uses of the discrete levels both for normalization of phenomenological level density approaches and within Hauser-Feshbach calculations are discussed in this respect. (Author)

  16. Determination of fast neutron fluence at WWER-1000 pressure vessel

    International Nuclear Information System (INIS)

    Valenta, V. et al.

    1989-01-01

    The influence function method is an effective tool making it possible, by means of tabulated values to rapidly perform three-dimensional calculations of fast neutron fluences for various reactor core loadings and for various nuclear power plant units. The procedure for determining the spatial dependence of the fast neutron fluences in a WWER-1000 pressure vessel is described. For this, the reactor core is divided into sufficiently fine volume elements within which the neutron source can be regarded as coordinate-independent. The influence functions point to a substantial role of sources lying at the reactor core periphery. In WWER-1000 reactors, only 1 or 2 rows of peripheral assemblies are important. The influence function method makes possible a rapid and easy determination of preconditions for the assessment of the residual lifetime of the pressure vessel based on the actual reactor core loadings. (Z.M.). 7 figs., 8 refs

  17. Application of Van Hove theory to fast neutron inelastic scattering

    International Nuclear Information System (INIS)

    Stanicicj, V.

    1974-11-01

    The Vane Hove general theory of the double differential scattering cross section has been used to derive the particular expressions of the inelastic fast neutrons scattering kernel and scattering cross section. Since the considered energies of incoming neutrons being less than 10 MeV, it enables to use the Fermi gas model of nucleons. In this case it was easy to derive an analytical expression for the time-dependent correlation function of the nucleus. Further, by using an impulse approximation and a short-collision time approach, it was possible to derive the analytical expression of the scattering kernel and scattering cross section for the fast neutron inelastic scattering. The obtained expressions have been used for Fe nucleus. It has been shown a surprising agreement with the experiments. The main advantage of this theory is in its simplicity for some practical calculations and for some theoretical investigations of nuclear processes

  18. Energy-resolved fast neutron resonance radiography at CSNS

    Science.gov (United States)

    Tan, Zhixin; Tang, Jingyu; Jing, Hantao; Fan, Ruirui; Li, Qiang; Ning, Changjun; Bao, Jie; Ruan, Xichao; Luan, Guangyuan; Feng, Changqin; Zhang, Xianpeng

    2018-05-01

    The white neutron beamline at the China Spallation Neutron Source will be used mainly for nuclear data measurements. It will be characterized by high flux and broad energy spectra. To exploit the beamline as a neutron imaging source, we propose a liquid scintillator fiber array for fast neutron resonance radiography. The fiber detector unit has a small exposed area, which will limit the event counts and separate the events in time, thus satisfying the requirements for single-event time-of-flight (SEToF) measurement. The current study addresses the physical design criteria for ToF measurement, including flux estimation and detector response. Future development and potential application of the technology are also discussed.

  19. Neutron spin-echo spectroscopy for diffusion in crystalline solids

    International Nuclear Information System (INIS)

    Kaisermayr, M.; Rennhofer, M.; Vogl, G.; Pappas, C.; Longeville, S.

    2002-01-01

    Neutron spin-echo spectroscopy (NSE) offers unprecedented opportunities in the investigation of diffusion in crystalline systems due to its outstanding energy resolution. NSE not only enables measurements at lower diffusivities than the established techniques of neutron spectroscopy, but it also gives a very immediate access to the different time scales involved in the diffusion process. This is demonstrated in detail on the example of the binary alloy NiGa where the Ni atoms hop between regular sites on the Ni sublattice and anti-sites on the Ga sublattice. Experiments on two different NSE instruments are compared to measurements using neutron backscattering spectroscopy. The potential of NSE for the investigation of jump diffusion and experimental requirements are discussed

  20. First- and second-chance proton emission in the interactions of fast neutrons with 92Mo

    International Nuclear Information System (INIS)

    Qaim, S.M.; Wolfle, R.; Strohmaier, B.

    1989-01-01

    Cross sections were measured radiochemically for the 92 Mo(n,p) 92 Nb m and 92 Mo(n,n'p +pn+d) 91 Nb m reactions over the neutron energy range of 9.0--10.6 MeV, and for the latter reaction also between 12.6 and 14.4 MeV. Use was made of high-resolution γ-ray and x-ray spectroscopy. Statistical-model calculations taking into account precompound effects were performed for fast neutron induced reactions on 92 Mo. The calculational results agree well with the experimental data on emitted proton spectra as well as on the excitation functions of various reaction channels. The second-chance proton emission is significant for incident neutron energies above 11 MeV; between 13 and 14 MeV it is comparable to the first-chance proton emission

  1. Structure and Spatial Distribution of Ge Nanocrystals Subjected to Fast Neutron Irradiation

    Directory of Open Access Journals (Sweden)

    Alexander N. Ionov

    2011-07-01

    Full Text Available The influence of fast neutron irradiation on the structure and spatial distribution of Ge nanocrystals (NC embedded in an amorphous SiO2 matrix has been studied. The investigation was conducted by means of laser Raman Scattering (RS, High Resolution Transmission Electron Microscopy (HR-TEM and X-ray photoelectron spectroscopy (XPS. The irradiation of Ge- NC samples by a high dose of fast neutrons lead to a partial destruction of the nanocrystals. Full reconstruction of crystallinity was achieved after annealing the radiation damage at 8000C, which resulted in full restoration of the RS spectrum. HR-TEM images show, however, that the spatial distributions of Ge-NC changed as a result of irradiation and annealing. A sharp decrease in NC distribution towards the SiO2 surface has been observed. This was accompanied by XPS detection of Ge oxides and elemental Ge within both the surface and subsurface region.

  2. A measurement of the response to fast neutrons of several materials dosemeters

    International Nuclear Information System (INIS)

    Jones, L.T.; Kitching, S.J.; Lewis, T.A.; Playle, T.S.

    1986-07-01

    The response to fast neutrons was measured for three types of materials testing dosemeters: fast neutron dosimetry silicon diodes; beryllia, alumina and calcium fluoride TLDs; graphite walled ionisation chambers. The calibrations were made using a 3MW positive ion accelerator. The arrangement of the target, beam monitor and devices is described, and the measured fast neutron sensitivities are presented. (UK)

  3. System and plastic scintillator for discrimination of thermal neutron, fast neutron, and gamma radiation

    Science.gov (United States)

    Zaitseva, Natalia P.; Carman, M. Leslie; Faust, Michelle A.; Glenn, Andrew M.; Martinez, H. Paul; Pawelczak, Iwona A.; Payne, Stephen A.

    2017-05-16

    A scintillator material according to one embodiment includes a polymer matrix; a primary dye in the polymer matrix, the primary dye being a fluorescent dye, the primary dye being present in an amount of 3 wt % or more; and at least one component in the polymer matrix, the component being selected from a group consisting of B, Li, Gd, a B-containing compound, a Li-containing compound and a Gd-containing compound, wherein the scintillator material exhibits an optical response signature for thermal neutrons that is different than an optical response signature for fast neutrons and gamma rays. A system according to one embodiment includes a scintillator material as disclosed herein and a photodetector for detecting the response of the material to fast neutron, thermal neutron and gamma ray irradiation.

  4. Spectroscopy with cold and ultra-cold neutrons

    Directory of Open Access Journals (Sweden)

    Abele Hartmut

    2015-01-01

    Full Text Available We present two new types of spectroscopy methods for cold and ultra-cold neutrons. The first method, which uses the R×B drift effect to disperse charged particles in a uniformly curved magnetic field, allows to study neutron β-decay. We aim for a precision on the 10−4 level. The second method that we refer to as gravity resonance spectroscopy (GRS allows to test Newton’s gravity law at short distances. At the level of precision we are able to provide constraints on any possible gravity-like interaction. In particular, limits on dark energy chameleon fields are improved by several orders of magnitude.

  5. High-pressure cell for simultaneous dielectric and neutron spectroscopy

    DEFF Research Database (Denmark)

    Sanz, Alejandro; Hansen, Henriette Wase; Jakobsen, Bo

    2018-01-01

    In this article, we report on the design, manufacture, and testing of a high-pressure cell for simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different time scales, from kilo- to picoseconds, covering universal features such as the α relaxation......, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data...

  6. Nuclear fuel assembly for fast neutron reactors

    International Nuclear Information System (INIS)

    Ilyunin, V.G.; Murogov, V.M.; Troyanov, M.F.; Rinejskij, A.A.; Ustinov, G.G.; Shmelev, A.N.

    1982-01-01

    The fuel assembly of a fast reactor consists of fuel elements comprising sections with fissionable and breeding material and tubes with hollows designed for entrapping gaseous fission products. Tubes joining up to the said sections are divided in a middle and a peripheral group such that at least one of the tube groups is placed in the space behind the coolant inlet ports. The configuration above allows reducing internal overpressure in the fuel assembly, thus reducing the volume of necessary structural elements in the core. (J.B.)

  7. EDF research on fast neutron reactors

    International Nuclear Information System (INIS)

    In order to make possible the calculation of the temperatures of the sodium, of the sheath and of the fuel in fast reactor assemblies, taking into account the mixing phenomena induced by the helicoidal wires, two design codes have been developed. Those codes have then been adapted for their integration in the Superalcyon system. This system shall constitute the reference tool for the development of those codes that shall manage Phenix, and other reactors of the family. Cooling accidents, thermohydraulic studies, and steam generator studies are also in progress

  8. A multi-group neutron noise simulator for fast reactors

    International Nuclear Information System (INIS)

    Tran, Hoai Nam; Zylbersztejn, Florian; Demazière, Christophe; Jammes, Christian; Filliatre, Philippe

    2013-01-01

    Highlights: • The development of a neutron noise simulator for fast reactors. • The noise equation is solved fully in a frequency-domain. • A good agreement with ERANOS on the static calculations. • Noise calculations induced by a localized perturbation of absorption cross section. - Abstract: A neutron noise simulator has been developed for fast reactors based on diffusion theory with multi-energy groups and several groups of delayed neutron precursors. The tool is expected to be applicable for core monitoring of fast reactors and also for other reactor types with hexagonal fuel assemblies. The noise sources are modeled through small stationary fluctuations of macroscopic cross sections, and the induced first order noise is solved fully in the frequency domain. Numerical algorithms are implemented for solving both the static and noise equations using finite differences for spatial discretization, where a hexagonal assembly is radially divided into finer triangular meshes. A coarse mesh finite difference (CMFD) acceleration has been used for accelerating the convergence of both the static and noise calculations. Numerical calculations have been performed for the ESFR core with 33 energy groups and 8 groups of delayed neutron precursors using the cross section data generated by the ERANOS code. The results of the static state have been compared with those obtained using ERANOS. The results show an adequate agreement between the two calculations. Noise calculations for the ESFR core have also been performed and demonstrated with an assumption of the perturbation of the absorption cross section located at the central fuel ring

  9. nGEM fast neutron detectors for beam diagnostics

    International Nuclear Information System (INIS)

    Croci, G.; Claps, G.; Cavenago, M.; Dalla Palma, M.; Grosso, G.; Murtas, F.; Pasqualotto, R.; Perelli Cippo, E.; Pietropaolo, A.; Rebai, M.; Tardocchi, M.; Tollin, M.; Gorini, G.

    2013-01-01

    Fast neutron detectors with a sub-millimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. A nGEM detector has been developed for the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a triple GEM gaseous detector equipped with polypropylene and polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a nGEM detector at the ISIS spallation source on the VESUVIO beam line. Beam profiles (σ x =14.35 mm, σ y =15.75 mm), nGEM counting efficiency (around 10 -4 for 3 MeV n <15 MeV), detector stability (≈4.5%) and the effect of filtering the beam with different type of materials were successfully measured. The x beam profile was compared to the one measured by a single crystal diamond detector. Finally, the efficiency of the detector was simulated exploiting the GEANT4 tool

  10. Neutron spectroscopy at the turn of the century

    CERN Document Server

    Popov, Yu P

    2003-01-01

    Neutron spectrometry is a powerful method of investigating atomic nuclei and condensed matter. Such investigations provide necessary data for a very wide spectrum of scientific and technological applications from the fundamental problems of the structure of matter and nucleosynthesis in the Universe to atomic power technologies and the structure of condensed matter. The most frequently utilized is the time-of-flight (TOF) method for powerful pulsed neutron sources. However, in many cases, one can use more effective, simpler and cheaper methods. For example, for astrophysics and radioactive waste transmutation problems, it is sufficient to know an average resonance cross section or "resonance integrals" for capture and fission reactions for neutron spectra specific to neutron fluxes in stars or in the active zone of a transmutation reactor. In these cases, the slow-down neutron spectroscopy (SDNS) methods in lead and graphite moderators will be useful. Compared to the TOF method, the lead SDNS gives a 10/sup 3...

  11. Apparatus and method for detecting contraband using fast neutron activation

    International Nuclear Information System (INIS)

    Gozani, T.; Sawa, Z.P.; Shea, P.M.

    1992-01-01

    This patent describes a method of detecting contraband within an object under investigation. It comprises: generating a beam of case neutrons; irradiating the object with the beam of fast neutrons, the fast neutrons interacting with atomic nuclei of the elements contained within the object to produce a gamma-ray spectrum having spectral lines characteristic of the elements contained within the object; measuring the spectral lines of the gamma-ray spectrum using a multiplicity of gamma-ray detectors judiciously positioned around the object; detecting the number of neutrons that pass through the object without interacting substantially with atomic nuclei within the object; determining the spatial and density distributions of the atomic nuclei of the elements contained within the object from the measured gamma-ray spectrum obtained from the multiplicity of gamma-ray detectors and the number of neutrons that pass through the object; comparing the measured spatial and density distributions of the atomic nuclei of the elements within the object with known spatial and density distributions of atomic nuclei for elements characteristic of contraband; and determining that contraband is present within the object when the comparison indicates a substantial match

  12. Material characterization using cold neutron transmission spectroscopy

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki; Kamiyama, Takashi; Nagata, Toshiyuki; Hiraga, Fujio; Suzuki, Shun

    2006-01-01

    Transmission data using a pulsed neutron source have information on neutron cross-section that reflects the crystal structure of the object, and combined with area detector we can obtain the structural change depending on the position in the object. We performed several experimental studies to observe the change of the structure. We demonstrate position-dependent structural change of the lead in solid. It was indicated that the structure changed largely within few millimeters region. Furthermore, we observed the cross-section change of stainless steel (SS) samples with different treatments, which may be the effect of crystal grain structure of the SS samples caused by different treatment

  13. Proceedings of the 14. International Symposium on the Interaction of Fast Neutrons with Nuclei - Neutron Generators and Application - organized by the Technical University of Dresden

    International Nuclear Information System (INIS)

    Seeliger, D.; Jahn, U.

    1985-07-01

    The symposium was devoted to current problems of intense fast neutron sources, especially 14 MeV DT-neutron generators, and their broad spectrum of application in nuclear physics. 56 participants from 12 countries and the IAEA demonstrate the high interest on this selected topics. The submitted contributions can be divided into two general parts. The first one gives a review about the different possibilities of the technical and technological solution in development, the present status of operation and also the problems connected with the use of intense neutron sources. Various experimental arrangements for neutron spectroscopy, determination of nuclear data and theoretical aspects are the content of the second part. The participation in this meeting of designer and operators on the one hand and users of neutron sources on the other hand was a good choice and stimulated productive discussions during the conference. (author)

  14. Optimization of CR-39 for fast neutron dosimetry applications

    International Nuclear Information System (INIS)

    Vilela, E.; Fantuzzi, E.; Giacomelli, G.; Giorgini, M.; Morelli, B.; Patrizii, L.; Serra, P.; Togo, V.

    1999-01-01

    We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: 241 Am-Be, 252 Cf and 238 Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose

  15. Computer aided design of fast neutron therapy units

    International Nuclear Information System (INIS)

    Gileadi, A.E.; Gomberg, H.J.; Lampe, I.

    1980-01-01

    Conceptual design of a radiation-therapy unit using fusion neutrons is presently being considered by KMS Fusion, Inc. As part of this effort, a powerful and versatile computer code, TBEAM, has been developed which enables the user to determine physical characteristics of the fast neutron beam generated in the facility under consideration, using certain given design parameters of the facility as inputs. TBEAM uses the method of statistical sampling (Monte Carlo) to solve the space, time and energy dependent neutron transport equation relating to the conceptual design described by the user-supplied input parameters. The code traces the individual source neutrons as they propagate throughout the shield-collimator structure of the unit, and it keeps track of each interaction by type, position and energy. In its present version, TBEAM is applicable to homogeneous and laminated shields of spherical geometry, to collimator apertures of conical shape, and to neutrons emitted by point sources or such plate sources as are used in neutron generators of various types. TBEAM-generated results comparing the performance of point or plate sources in otherwise identical shield-collimator configurations are presented in numerical form. (H.K.)

  16. Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yavar, A.R. [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Sarmani, S.B. [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Wood, A.K. [Analytical Chemistry Application Group, Industrial Technology Division, Malaysian Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor (Malaysia); Fadzil, S.M. [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Radir, M.H. [Analytical Chemistry Application Group, Industrial Technology Division, Malaysian Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor (Malaysia); Khoo, K.S., E-mail: khoo@ukm.m [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2011-05-15

    Determination of thermal to fast neutron flux ratio (f{sub fast}) and fast neutron flux ({phi}{sub fast}) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The f{sub fast} and subsequently {phi}{sub fast} were determined using the absolute method. The f{sub fast} ranged from 48 to 155, and the {phi}{sub fast} was found in the range 1.03x10{sup 10}-4.89x10{sup 10} n cm{sup -2} s{sup -1}. These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.

  17. Design of a boron neutron capture enhanced fast neutron therapy assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu [Georgia Inst. of Technology, Atlanta, GA (United States)

    2006-12-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm 10B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The

  18. Development of resonant detectors for epithermal neutron spectroscopy at pulsed neutron sources

    International Nuclear Information System (INIS)

    Tardocchi, M.; Pietropaolo, A.; Senesi, R.; Andreani, C.; Gorini, G.

    2004-01-01

    New perspectives for epithermal neutron spectroscopy are opened by the development of new detectors for inverse geometry time of flight spectrometers at pulsed neutron sources. One example is the Very Low Angle Detector (VLAD) bank planned to be delivered, within the next 4 years, within the eVERDI project, on the neutron spectrometer VESUVIO, at the ISIS pulsed neutron source (UK). VLAD will extend the (q,ω) kinematical region for neutron scattering to low wavefactor transfer (q -1 ) still keeping energy transfer >1 eV, thus allowing the investigations of new experimental studies in condensed matter systems. The technique being developed for detection of epithermal neutrons, within this low q and high-energy transfer region, is the Resonance Detection Technique. In this work, the state of the detector development will be presented with special focus on the results obtained with some prototype detectors, namely YAP scintillators and cadmium-zinc-telluride semiconductors

  19. Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl2O3

    International Nuclear Information System (INIS)

    Rahman, Abu Zayed Mohammad Saliqur; Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long; Xu, Qiu; Atobe, Kozo

    2014-01-01

    Highlights: •Detection of Al monovacancy by positron lifetime spectroscopy in fast neutron-irradiated MgO·nAl 2 O 3 (n=2). •Concentration of defects is also estimated for Al monovacancy. •O atom peak was observed by using coincidence Doppler broadening spectroscopy. -- Abstract: The positron lifetimes of fast-neutron-irradiated MgO·nAl 2 O 3 single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10 −3 m 0 c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies

  20. Fast neutron scintillation spectrometer in a heavy ion accelerator

    International Nuclear Information System (INIS)

    Blinov, M.V.; Gavrilov, B.P.; Ivannikova, L.L.; Kozulin, Eh.M.; Mozhaev, A.N.; Tyurin, G.P.

    1984-01-01

    Scintillation fast neutron spectrometer in a heavy ion accelerator is described in short. The spectrometer is used to measure characteristics of neutrons emitted in heavy ion interaction with different nuclei. Experiment was performed on the base of particle flight from 0.7 up to 2 m. Within the angle range of 0-150 deg. The technique is based on recording of two-dimensional neutron spectra obtained due to combination of the time-of-flight method and the method of recoil proton energy detection. Two measuring channels were used in the spectrometer. Each channel comprise both amplitude and time tracks. Detector on the base microchannel plates (MCP) generated a signal in passing the next ion bunch was used in order to obtain the time mark. Data from the scintillation block are recorded with respect to three parameters: recoil proton amplitude, time of neutron or γ-quantum arrival in respect of MCP-sensor pulse. Apparatus is carried out within the CAMAC standard. The spectrometer calibration within the 1-20 MeV neutron range was conducted in the Van-de-Graaf accelerator, and for higher energies - with the use of lightguides. Spectrometer time resolution for neutron energies of 0.5-50 MeV constituted 1.5-1.8 ns. The above measuring of neutron spectra from 1 /H2C+ 181 Ta and sup(20, 22)Ne+sup(181)Ta reaction have revealed a possibility of the experiment organization in heavy ion accelerators in the presence of strong neutron and γ-fields. Organization of multi-dimensional analysis combining two methods allows one to separate accelerator cycle, a region of the most reliable information, free of a low-energy gamma background and limited both by a dynamic threshold and a region of permissible energy values

  1. Fast analysis of carbon content by inelastic scattering of neutrons

    International Nuclear Information System (INIS)

    Heinrich, B.; Irmer, K.; Poetschke, R.

    1986-01-01

    The direct measurement of carbon concentration of conveyor belts is a difficult problem. The great penetration depth by the fast neutrons and the 4.43 MeV γ-radiation gives an especially suitable method. The measurement were performed by the following methods: excitation of γ-radiation by a Pu-Be neutron source, excitation of γ-radiation by DT-neutron generator in stationary regime, in pulse regime, or coupled with time correlated associated particle method. Furthermore, a special Monte Carlo code in which the geometry of the measuring equipment could be specified, was written to calculate the 4.43 MeV γ counting rate for backscatter geometries and for penetration geometries. The influence of conveyor belt, of content of H, O, Fe and of mass by surface for 4.43 MeV γ-radiation was calculated for application brown coal in industry. (author)

  2. NeuLand submodules exposed to fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Gasparic, Igor [Technische Univ. Darmstadt (Germany); Rudjer Boskovic Institute, Zagreb (Croatia); Aumann, Thomas [Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Boretzky, Konstanze; Heil, Michael; Simon, Haik [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Jaehrling, Simon [Technische Univ. Darmstadt (Germany); Collaboration: R3B-Collaboration

    2013-07-01

    Within the R{sup 3}B collaboration (Reactions with Relativistic Radioactive Beams), a new neutron detector NeuLAND (New Large Area Neutron Detector) is being developed. The technical design was finalized in November 2011, a fully active scintillator concept was chosen. It will be a box-shaped 2.5 x 2.5 x 3 m{sup 3} detector consisting of 3000 scintillator bars arranged in 60 planes with mutually orthogonal orientation. An array of 150 NeuLAND bars was exposed to fast ''mono-energetic'' neutrons stemming from quasi-free deuteron breakup reactions on a CH{sub 2} target (250 to 1500 AMeV). The experiment carried out at GSI in Nov. 2012 aims for determination of both time resolution and efficiency of NeuLAND submodules. Preliminary results of the analysis are presented.

  3. Quantitative fuel motion determination with the CABRI fast neutron hodoscope

    International Nuclear Information System (INIS)

    Baumung, K.; Augier, G.

    1991-01-01

    The fast neutron hodoscope installed at the CABRI reactor in Cadarache, France, is employed to provide quantitative fuel motion data during experiments in which single liquid-metal fast breeder reactor test pins are subjected to simulated accident conditions. Instrument design and performance are reviewed, the methods for the quantitative evaluation are presented, and error sources are discussed. The most important findings are the axial expansion as a function of time, phenomena related to pin failure (such as time, location, pin failure mode, and fuel mass ejected after failure), and linear fuel mass distributions with a 2-cm axial resolution. In this paper the hodoscope results of the CABRI-1 program are summarized

  4. Fast neutron reactors: the safety point of view

    International Nuclear Information System (INIS)

    Laverie, M.; Avenas, M.

    1984-01-01

    All versions of nuclear reactors present favourable and unfavourable characteristics from the point of view of safety. The safety of the installations is obtained by making efforts to utilize in the best possible way those which are favourable and by taking proper steps in the face of those which are unfavourable. The present article shows how this general principle has been applied as regards the fast neutron reactors of integrated design which have been developped in France, taking into account the specific features of this version. A qualitative method to compare the safety of this version with that of pressurized water reactors which has been widely put to the test commercially all over the world is presented. These analyses make, generally speaking, several positive characteristics stand out for these fast neutron reactors from the safety aspects [fr

  5. Chromatin damage induced by fast neutrons or UV laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L.; Constantinescu, B.; Gazdaru, D.; Mihailescu, I

    2002-07-01

    Chromatin samples from livers of Wistar rats were subjected to fast neutron irradiation in doses of 10-100 Gy or to a 248 nm excimer laser radiation, in doses of 0.5-3 MJ.m{sup -2}. The action of the radiation on chromatin was monitored by chromatin intrinsic fluorescence and fluorescence lifetimes (of bound ethidium bromide to chromatin) and by analysing fluorescence resonance energy transfer between dansyl chloride and acridine orange coupled to chromatin. For the mentioned doses of UV excimer laser radiation, the action on chromatin was more intense than in the case of fast neutrons. The same types of damage are produced by the two radiations: acidic and basic destruction of chromatin protein structure, DNA strand breaking and the increase of the distance between DNA and proteins in chromatin. (author)

  6. Chromatin damage induced by fast neutrons or UV laser radiation

    International Nuclear Information System (INIS)

    Radu, L.; Constantinescu, B.; Gazdaru, D.; Mihailescu, I.

    2002-01-01

    Chromatin samples from livers of Wistar rats were subjected to fast neutron irradiation in doses of 10-100 Gy or to a 248 nm excimer laser radiation, in doses of 0.5-3 MJ.m -2 . The action of the radiation on chromatin was monitored by chromatin intrinsic fluorescence and fluorescence lifetimes (of bound ethidium bromide to chromatin) and by analysing fluorescence resonance energy transfer between dansyl chloride and acridine orange coupled to chromatin. For the mentioned doses of UV excimer laser radiation, the action on chromatin was more intense than in the case of fast neutrons. The same types of damage are produced by the two radiations: acidic and basic destruction of chromatin protein structure, DNA strand breaking and the increase of the distance between DNA and proteins in chromatin. (author)

  7. Preliminary experiment of fast neutron imaging with direct-film method

    International Nuclear Information System (INIS)

    Pei Yuyang; Tang Guoyou; Guo Zhiyu; Zhang Guohui

    2005-01-01

    A preliminary experiment is conducted with direct-film method under the condition that fast neutron is generated by the reaction of 9 Be(d, n) on the Beijing University 4.5 MV Van de Graaff, whose energy is lower than 7 MeV. Basic characteristics of direct-film neutron radiography system are investigated with the help of samples in different materials, different thickness and holes of different diameter. The fast neutron converter, which is vital for fast neutron imaging, is produced with the materials made in China. The result indicates that fast neutron converter can meet the requirement of fast neutron imaging; further research of fast neutron imaging can be conducted on the accelerator and neutron-generator in China. (authors)

  8. Physics and chemistry of materials from neutron diffraction and spectroscopy

    International Nuclear Information System (INIS)

    Dahlborg, U.; Lovesey, S.W.; Uppsala Univ.

    1990-11-01

    A short introduction to the powerful techniques of neutron diffraction and spectroscopy is illustrated largely with achievements by Swedish researchers in the past few years. Background material on sources and instrumentation is included, together with a directory of facilities routinely available to the Swedish scientific community. (author)

  9. Recent results on neutron rich tin isotopes by laser spectroscopy

    CERN Document Server

    Roussière, B; Crawford, J E; Essabaa, S; Fedosseev, V; Geithner, W; Genevey, J; Girod, M; Huber, G; Horn, R; Kappertz, S; Lassen, J; Le Blanc, F; Lee, J K P; Le Scornet, G; Lettry, Jacques; Mishin, V I; Neugart, R; Obert, J; Oms, J; Ouchrif, A; Peru, S; Pinard, J; Ravn, H L; Sauvage, J; Verney, D

    2001-01-01

    Laser spectroscopy measurements have been performed on neutron rich tin isotopes using the COMPLIS experimental setup. The nuclear charge radii of the even-even isotopes from A=108 to 132 are compared to the results of macroscopic and microscopic calculations. The improvements and optimizations needed to perform the isotope shift measurement on $^{134}$Sn are presented.

  10. Status of the development of electron volt inelastic neutron spectroscopy

    International Nuclear Information System (INIS)

    Newport, R.J.; Taylor, A.D.; Williams, W.G.

    1984-05-01

    High energy inelastic neutron scattering spectroscopy is reviewed in the light of material presented at the 'High Energy Excitations in Condensed Matter' (HEECM) Workshop, held at Los Alamos National Laboratory 13-15 February 1984. Particular attention is paid to the development of instrumentation based on nuclear resonance analysers. (author)

  11. Pulsed neutron intensity from rectangular shaped light water moderator with fast-neutron reflector

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki; Iwasa, Hirokatsu

    1982-01-01

    With a view to enhancing the thermal-neutron intensity obtained from a pulsed neutron source, an experimental study has been made to determine the optimum size of a rectangular shaped light water moderator provided with fast neutron reflector of beryllium oxide or graphite, and decoupled thermal-neutronically by means of Cd sheet. The optimum dimensions for the moderator are derived for the neutron emission surface and the thickn ess, for the cases in which the neutron-producing target is placed beneath the moderator (''wing geometry'') or immediately behind the moderator (''slab geometry''). The major conclusions drawn from the experimental results are as follows. The presence of the Cd decoupler inserted between the moderator and reflector prevent the enhancement of thermal-neutron emission time gained by the provision of reflector. With a graphite reflector about 14 cm thick, (a) the optimum area of emission surface would be 25 x 25 cm 2 for wing geometry and still larger for slab geometry, and (b) the optimum moderator thickness would be 5.5 cm for slab geometry and 8.5 cm for wing geometry. It is thus concluded that a higher neutron emission intensity can be obtained with slab than with wing geometry provided that a large emission surface can be adopted for the moderator. (author)

  12. Geometric (Berry) phases in neutron molecular spectroscopy

    International Nuclear Information System (INIS)

    Lovesey, S.W.

    1992-02-01

    A theory of neutron scattering by nuclei in a molecule, accompanied by an electronic transition, is formulated with attention to gauge potentials and geometric phases in the Born-Oppenheimer scheme. Non-degenerate and nearly degenerate electronic levels are considered. For nearly degenerate levels it is shown that, the cross-section is free of the singular structure which characterizes the corresponding gauge potential for the phase, and much larger than for well separated electronic states. (author)

  13. Fast Neutron Elastic and Inelastic Scattering of Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T

    1969-11-15

    Fast neutron scattering interactions with vanadium were studied using time-of-flight techniques at several energies in the interval 1.5 to 8.1 MeV. The experimental differential elastic scattering cross sections have been fitted to optical model calculations and the inelastic scattering cross sections have been compared with Hauser-Feshbach calculations, corrected for the fluctuation of compound-nuclear level widths.

  14. Theoretical and Experimental Analysis of Fast Neutron Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Van Dam, H.; Kleijn, H. R. [Reactor Instituut, Delft (Netherlands)

    1968-04-15

    The reactor physics division of the Inter-Academic Reactor Institute at Delft is concentrating its efforts in the field of fast reactor physics on problems of a more fundamental nature. The object of the programme is to determine experimentally a number of microscopic reactor physics parameters such as conversion potentials, fission ratios and Doppler coefficients for simple geometries and material compositions. Because of the extreme importance of knowledge of the neutron spectrum for the interpretation of the results, attention has initially been concentrated on both the measurement and the calculation of fast neutron spectra. The transport of neutrons in absorbing and non-absorbing heavy atom materials is studied by solving the Boltzmann equation. Both isotropic and anisotropic scattering are considered. Anisotropic scattering is treated by the P{sub n}-approximation, while flux-anisotropy is handled with the S{sub N}-method. In the code FAST-DELFT, scattering is treated up to the P{sub 4} component, a further extension of which is useless because of the lack of available cross-section data. By using this method, the effect of scattering anisotropy on the spectrum formation has been studied. In addition the influence of group cross-section inaccuracies was determined. The experimental work has been concentrated on methods to determine in-core spectra. Using home-made proportional counters with gamma-ray discrimination provisions fast neutron spectra have been measured in simple geometries. These experiments were complemented by foil measurements in the lower energy region. The results of this work are presented in this paper. (author)

  15. Symmetrized neutron transport equation and the fast Fourier transform method

    International Nuclear Information System (INIS)

    Sinh, N.Q.; Kisynski, J.; Mika, J.

    1978-01-01

    The differential equation obtained from the neutron transport equation by the application of the source iteration method in two-dimensional rectangular geometry is transformed into a symmetrized form with respect to one of the angular variables. The discretization of the symmetrized equation leads to finite difference equations based on the five-point scheme and solved by use of the fast Fourier transform method. Possible advantages of the approach are shown on test calculations

  16. A study of the NRPB fast neutron personal monitoring service

    International Nuclear Information System (INIS)

    Bartlett, D.T.; Knight, A.; Marshall, T.O.

    1975-10-01

    The NRPB Fast Neutron Personal Monitoring Service has been reviewed and modifications have been, or are being, introduced to improve the accuracy and reliability of the nuclear emulsion dosemeter employed by the Service. This report presents the conclusions of the study. Experimental results of the investigations undertaken in the course of this study, together with full details of the dosemeter and Service, are appended. (author)

  17. Fast neutron radiography of extended biological and medical objects

    International Nuclear Information System (INIS)

    Duehmke, E.; Greim, L.

    1978-01-01

    The fast neutron radiography enables us to image extended objects and yields quite different pictures than conventional roentgenograms. Using foils of cellulose nitrate and the track etching technique a γ-ray-insensitive detector is available providing sufficient imaging qualities. One of the biological neutrograms shown in the paper is of special importance because one can see a malignant tumor of the columna vertebralis. This finding was not detectable by roentgenological examination. (orig.) [de

  18. A methodology of neutronic-thermodynamics simulation for fast reactor

    International Nuclear Information System (INIS)

    Waintraub, M.

    1986-01-01

    Aiming at a general optimization of the project, controlled fuel depletion and management, this paper develop a neutronic thermodynamics simulator, SIRZ, which besides being sufficiently precise, is also economic. That results in a 75% reduction in CPU time, for a startup calculation, when compared with the same calculation at the CITATION code. The simulation system by perturbation calculations, applied to fast reactors, which produce errors smaller than 1% in all components of the reference state given by the CITATION code was tested. (author)

  19. Note: Fast neutron efficiency in CR-39 nuclear track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, S. [Dipartimento di Fisica ed Astronomia,Università di Catania, Via S. Sofia 44, 95123 Catania, Italy and INFN-LNS, Via S. Sofia 42, 95123 Catania (Italy)

    2015-03-15

    CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.

  20. Fast Neutron Detection Using Pixelated CdZnTe Spectrometers

    Science.gov (United States)

    Streicher, Michael; Goodman, David; Zhu, Yuefeng; Brown, Steven; Kiff, Scott; He, Zhong

    2017-07-01

    Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed.

  1. Fast amplification system for gamma spectroscopy

    International Nuclear Information System (INIS)

    Jesus, E.F.O.; Lopes, R.T.

    1992-01-01

    An amplification system for gamma spectroscopy with high counting rates was developed. The system was constructed with operational amplifiers, and tested and compared with ORTEC conventional system, using Iridium-192 as source of 9,25 x 10 1 0 Bq of activity and NaI (Tl) detector. The constructed system showed a better performance in relation to efficiency and resolution parameters, tested before. (C.G.C.)

  2. Influence of Neutron Spectra Unfolding Method on Fast Neutron Dose Determination

    International Nuclear Information System (INIS)

    Marinkovic, P.

    1991-01-01

    Full text: Accuracy of knowing the fast neutron spectra has great influence on equivalent dose determination. In usual fast neutron spectrum measurements with scintillation detectors based on proton recoil, the main difficulty is confidence of unfolding method. In former ones variance of obtained result is usually great and negative values are possible too, which does means that we don't now exactly is obtained neutron spectrum real one. The new unfolding method based on Shanon's information theory, which gives non-negative spectrum and relative low variance, is obtained and appropriate numerical code for application in fast neutron spectrometry based on proton recoil is realized. In this method principle of maximum entropy and maximum likelihood are used together. Unknown group density distribution functions, which are considered as desired normalized mean neutron group flux, are constl u cted using only constrain of knowing mean value. Obtained distributions are consistent to available information (counts in NCA from proton recoil), while being maximally noncommittal with respect to all other unknown circumstances. For maximum likelihood principle, distribution functions around mean value of counts in the channels of MCA are taken to be Gauss function shape. Optimal non-negative solution is searched by means of Lagrange parameter method. Nonlinear system of equations, is solved using gradient and Newton iterative algorithm. Error covariance matrix is obtained too. (author)

  3. Genes involved in yeast survival after irradiation with fast neutrons

    International Nuclear Information System (INIS)

    Bozin, D.; Milosevic, M.J.

    2001-01-01

    Life on the Earth has evolved against a continuous background of ionizing radiation. It would be expected, therefore, that all possible mutations have been produced at some time or another; man-made radiation from medical or industrial sources will not result in any new types of mutation but will simply increase the whole spectrum of mutations that occur spontaneously. Any such lesion can be mutagenic and, in principle, lethal. To counteract the consequences of DNA damage, evolution has equipped all living cells with an intricate network of defense and repair systems. Together, these systems act as a kind of nuclear 'immune system' that is able to recognize and eliminate many types of DNA lesions. In the case of the yeast Saccharomyces cerevisiae, in these processes over 30 RAD genes participate. We tested the survival of haploid and diploid rad1 yeast mutant strains at a dose of 15 Gy of γ or fast neutron radiation. We demonstrated that the lethality of rad1 mutants both haploid and diploid are significantly higher after fast neutron irradiation. The results indicate to the role and position of these genes in the DNA repair of damages specifically induced by fast neutrons. (authors)

  4. Effects of fast neutrons on chromatin: dependence on chromatin structure

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L. [Dept. of Molecular Genetics, V. Babes National Inst., Bd. Timisoara, Bucharest (Romania); Constantinescu, B. [Dept. of Cyclotron, H. Hulubei National Inst., Bucharest (Romania); Gazdaru, D. [Dept. of Biophysics, Physics Faculty, Univ. of Bucharest (Romania)

    2002-07-01

    The effects of fast neutrons (10-100 Gy) on chromatin extracted from normal (liver of Wistar rats) and tumor (Walker carcinosarcoma maintained on Wistar rats) tissues were compared. The spectroscopic assays used were (i) chromatin intrinsic fluorescence, (ii) time-resolved fluorescence of chromatin-proflavine complexes, and (iii) fluorescence resonance energy transfer (FRET) between dansyl chloride and acridine orange coupled to chromatin. For both normal and tumor chromatin, the intensity of intrinsic fluorescence specific for acidic and basic proteins decreased with increasing dose. The relative contributions of the excited-state lifetime of proflavine bound to chromatin were reduced upon fast-neutron irradiation, indicating a decrease in the proportion of chromatin DNA available for ligand binding. The Forster energy transfer efficiencies were also modified by irradiation. These effects were larger for chromatin from tumor tissue. In the range 0-100 Gy, fast neutrons induced alterations in DNA and acidic and basic proteins, as well as in global chromatin structure. The radiosensitivity of chromatin extracted from tumor tissue seems to be higher than that of chromatin extracted from normal tissue, probably because of its higher euchromatin (loose)-heterochromatin (compact) ratio. (author)

  5. Effects of fast neutrons on chromatin: dependence on chromatin structure

    International Nuclear Information System (INIS)

    Radu, L.; Constantinescu, B.; Gazdaru, D.

    2002-01-01

    The effects of fast neutrons (10-100 Gy) on chromatin extracted from normal (liver of Wistar rats) and tumor (Walker carcinosarcoma maintained on Wistar rats) tissues were compared. The spectroscopic assays used were (i) chromatin intrinsic fluorescence, (ii) time-resolved fluorescence of chromatin-proflavine complexes, and (iii) fluorescence resonance energy transfer (FRET) between dansyl chloride and acridine orange coupled to chromatin. For both normal and tumor chromatin, the intensity of intrinsic fluorescence specific for acidic and basic proteins decreased with increasing dose. The relative contributions of the excited-state lifetime of proflavine bound to chromatin were reduced upon fast-neutron irradiation, indicating a decrease in the proportion of chromatin DNA available for ligand binding. The Forster energy transfer efficiencies were also modified by irradiation. These effects were larger for chromatin from tumor tissue. In the range 0-100 Gy, fast neutrons induced alterations in DNA and acidic and basic proteins, as well as in global chromatin structure. The radiosensitivity of chromatin extracted from tumor tissue seems to be higher than that of chromatin extracted from normal tissue, probably because of its higher euchromatin (loose)-heterochromatin (compact) ratio. (author)

  6. Photo-induced current transient spectroscopy for high-resistivity neutron-transmutation-doped silicon

    International Nuclear Information System (INIS)

    Tokuda, Yutaka; Inoue, Yajiro; Usami, Akira

    1987-01-01

    Defects in high-resistivity neutron-transmutation-doped (NTD) silicon prior to annealing were studied by photo-induced current transient spectroscopy (PICTS). The thermal-neutron fluence was 9.5 x 10 17 cm -2 to give a resistivity of about 30 Ω after annealing, and the fast-neutron fluence was 9.5 x 10 16 cm -2 . Four traps with thermal emission activation energies of 0.15, 0.41. 0.47 and 0.50 eV were observed in NTD silicon. A trap with the thermal emission activation energy of 0.15 eV was considered to correspond to the divacancy. Although the clustered nature of the defects was observed, PICTS measurements suggest that the material state of high-resistivity NTD silicon is still crystalline and not amorphous. (author)

  7. Radiation protection aspects of a high flux, fast neutron generator

    International Nuclear Information System (INIS)

    DeLuca, P.M.; Torti, R.P.; Chenevert, G.M.; Tesmer, J.R.; Kelsey, C.A.

    1976-01-01

    During the development and operation of a gas target, DT neutron generator for use in cancer therapy, two radiation hazards were routinely encountered - personnel exposure to neutrons and to tritium. The principal hazard was irradiation by fast neutrons. By assembling the source below ground level, adding shielding and the use of a controlled access, key identification interlock, the neutron hazard has been reduced. With the present source strength of 2 x 10 12 n/sec, an average neutron dose rate in the control room of 20 mrem/hr was measured- a level compatible with a limited run schedule. The second hazard was exposure to tritium in both gaseous and solid forms. A target inventory of 90 Ci, and overall inventory of 500 Ci, and the need to modify and repair the generator present significant potential hazard due to tritium exposure. The use of protective gloves, wipe tests, urine assays, continuous room air monitoring, and equipment decontamination minimized personnel exposure and effectively confined contamination. The dose due to tritium has been ∼ 0.5 rem/year and negligible spread of contamination has occurred

  8. The multielement potential of fast neutron cyclic activation analysis

    International Nuclear Information System (INIS)

    Nonie, S.E.; Randle, K.

    1994-01-01

    Cyclic neutron activation analysis (CNAA) has, in recent years been developed as a useful analytical tool for the assay of short-lived isotopes in single element situations. The work described in this paper investigates the potential of the technique for composite samples having a wide range of elements that produce short-lived and long-lived isotopes on neutron irradiation. Accelerator-derived neutrons with average energies of 3 MeV, 6 MeV and 14 MeV were employed in what has been dubbed 'Fast Neutron Cyclic Neutron Activation Analysis' (FNCAA). The approach to multi-element analysis entailed: determination of cycle parameters in single element samples via the reactions 27 Al(n,p) 27 Mg(9.6 min,E γ =840keV), and 137 Ba(n,n 'γ137m Ba(2.3 min,E γ 137m Ba(2.3 min,E γ =662 keV), a test of the method on a composite rock sample, determination of analytical sensitivities using both powdered kale and rock standards and a comparison of analytical results with other techniques. The results obtained in all these measurements are presented and discussed. (author) 10 refs.; 3 figs.; 5 tabs

  9. Polarization of fast neutrons in VVR-M reactor

    International Nuclear Information System (INIS)

    Garusov, E.A.; Lifshits, E.P.; Petrov, Yu.V.

    1987-01-01

    Neutron polarization in the reactor leads to circular polarization of γ quanta emitted both in radiational capture of neutrons and in the transition of nuclei excited as a result of inelastic scattering to the ground state. This may be used to determine the polarization of reactor neutrons. The circular polarization of γ quanta at light-water and graphite targets at the center of the active zone of the VVR-M reactor at the B.P. Konstantinov Leningrad Institute of Nuclear Physics was recently measured. A simplified experimental scheme is shown. Fast neutrons leaving the active zone of the reactor were excited in the inelastic scattering at the target nuclei. The polarization of the γ quanta emitted by nuclei in transitions to the ground state was measured by a polarimeter positioned above the active zone. The reason for the circular polarization of γ quanta may also be nonconservation of P parity on account of weak interaction in the capture of a neutron by hydrogen

  10. Spent Nuclear Fuel Cask and Storage Monitoring with {sup 4}He Scintillation Fast Neutron Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hee jun; Kelley, Ryan P; Jordan, Kelly A [Univ. of Florida, Florida (United States); Lee, Wanno [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chung, Yong Hyun [Yonsei Univ., Wonju (Korea, Republic of)

    2014-10-15

    With this increasing quantity of spent nuclear fuel being stored at nuclear plants across S. Korea, the demand exists for building a long-term disposal facility. However, the Korean government first requires a detailed plan for the monitoring and certification of spent fuel. Several techniques have been developed and applied for the purpose of spent fuel monitoring, including the digital Cerenkov viewing device (DCVD), spent fuel attribute tester (SFAT), and FORK detector. Conventional gamma measurement methods, however, suffer from a lack of nuclear data and interfering background radiation. To date, the primary method of neutron detection for spent fuel monitoring has been through the use of thermal neutron detectors such as {sup 3}He and BF{sub 3} proportional counters. Unfolding the neutron spectrum becomes extremely complicated. In an attempt to overcome these difficulties, a new fast neutron measurement system is currently being developed at the University of Florida. This system is based on the {sup 4}He scintillation detector invented by Arktis Radiation Detectors Ltd. These detectors are a relatively new technological development and take advantage of the high {sup 4}He cross-section for elastic scattering at fast neutron energies, particularly the resonance around 1 MeV. This novel {sup 4}He scintillation neutron detector is characterized by its low electron density, leading to excellent gamma rejection. This detector also has a fast response time on the order of nanoseconds and most importantly, preserves some neutron energy information since no moderator is required. Additionally, these detectors rely on naturally abundant {sup 4}He as the fill gas. This study proposes a new technique using the neutron spectroscopy features of {sup 4}He scintillation detectors to maintain accountability of spent fuel in storage. This research will support spent fuel safeguards and the detection of fissile material, in order to minimize the risk of nuclear proliferation

  11. Activation measurements of fast neutron radiative capture for 139La

    International Nuclear Information System (INIS)

    Luo, Junhua; Han, Jiuning; Liu, Rong; Jiang, Li; Liu, Zhenlai; Sun, Guihua; Ge, Suhong

    2013-01-01

    The neutron capture cross section of the neutron magic isotope 139 La has been measured relative to that of 27 Al by means of the activation method. The fast neutrons were produced via the 3 H(d,n) 4 He reaction on Pd-300 neutron generator. The natural high-purity La 2 O 3 powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The new values for E n =13.5±0.2, 14.1±0.2, and 14.8±0.2 MeV are found to be 1.30±0.08, 1.15±0.08 and 0.99±0.07 mb, respectively. Results were discussed and compared with some corresponding values found in the literature. - Highlights: ► D–T neutron source was used to measure cross sections using activation method. ► 27 Al(n,α) 24 Na was used as the monitor for the measurement. ► The cross sections for the (n,γ) reactions on neutron magic isotope 139 La have been measured. ► The data for 139 La(n,γ) 140 La reaction are presented. ► The results were compared with previous data and with evaluation data

  12. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  13. Effect of neutron anisotropic scattering in fast reactor analysis

    International Nuclear Information System (INIS)

    Chiba, Gou

    2004-01-01

    Numerical tests were performed about an effect of a neutron anisotropic scattering on criticality in the Sn transport calculation. The simplest approximation, the consistent P approximation and the extended transport approximation were compared with each other in one-dimensional slab fast reactor models. JAERI fast set which has been used for fast reactor analyses is inadequate to evaluate the effect because it doesn't include the scattering matrices and the self-shielding factors to calculate the group-averaged cross sections weighted by the higher-order moment of angular flux. In the present study, the sub-group method was used to evaluate the group-averaged cross sections. Results showed that the simplest approximation is inadequate and the transport approximation is effective for evaluating the anisotropic scattering. (author)

  14. Study on neutron streaming effect in large fast critical assembly

    International Nuclear Information System (INIS)

    Takeda, Toshikazu; Yamaoka, Mitsuaki; Sakurai, Shungo; Tanimoto, Koichi; Abe, Yuhei

    1981-03-01

    A cell calculation method taking into account the neutron leakage from a cell and a transport calculation method treating the neutron streaming have been developed, and their applicability has been investigated. In the cell calculation method, the neutron leakage in the perpendicular direction to plates was treated by introducing an albedo collision probability which is a first-flight collision probability incorporating albedos at cell boundaries, and that in the parallel direction was treated by the pseudo absorption method. The use of the albedo collision probability made it possible to calculate the flux tilt in a cell exactly. This cell calculation method was applied to two slab models where fuel drawers were stacked in perpendicular and parallel directions to plates. Cell averaged cross sections calculated by the proposed method agreed well with those obtained from exact transport calculations treating the plate-wise heterogeneity, while the infinite cell calculation and the conventional pseudo absorption method produced about 2% errors in the cell-averaged cross sections. The cell-averaging procedure for control-rod channels was also proposed, and this method was applied to the calculation of control-rod worths and control-rod position worths. A transport calculation method based on the response matrix method has been proposed to treat the neutron streaming in fast critical assemblies directly. A response matrix code in two dimensional XY geometry RES2D was made. The accuracy of response matrices obtained from the RES2D code was checked by applying it to a slab cell and by comparing cell-averaged cross sections and k-infinity with those from a reference cell calculation based on the collision probability. The agreement of the results was good, and it was found that the response matrix method is very promising for the treatment of the neutron streaming in fast critical assemblies. (author)

  15. A high gain energy amplifier operated with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Rubbia, C. [CERN, Geneva (Switzerland)

    1995-10-01

    The basic concept and the main practical considerations of an Energy Amplifier (EA) have been exhaustively described elsewhere. Here the concept of the EA is further explored and additional schemes are described which offer a higher gain, a larger maximum power density and an extended burn-up. All these benefits stem from the use of fast neutrons, instead of thermal or epithermal ones, which was the case in the original study. The higher gain is due both to a more efficient high energy target configuration and to a larger, practical value of the multiplication factor. The higher power density results from the higher permissible neutron flux, which in turn is related to the reduced rate of {sup 233}Pa neutron captures (which, as is well known, suppress the formation of the fissile {sup 233}U fuel) and the much smaller k variations after switch-off due to {sup 233}Pa decays for a given burn-up rate. Finally a longer integrated burn-up is made possible by reduced capture rate by fission fragments of fast neutrons. In practice a 20 MW proton beam (20 mA @ 1 GeV) accelerated by a cyclotron will suffice to operate a compact EA at the level of {approx} 1 GW{sub e}. The integrated fuel burn-up can be extended in excess of 100 GW d/ton, limited by the mechanical survival of the fuel elements. Radio-Toxicity accumulated at the end of the cycle is found to be largely inferior to the one of an ordinary Reactor for the same energy produced. Schemes are proposed which make a {open_quotes}melt-down{close_quotes} virtually impossible. The conversion ratio, namely the rate of production of {sup 233}U relative to consumption is generally larger than unity, which permits production of fuel for other uses. Alternatively the neutron excess can be used to transform unwanted {open_quotes}ashes{close_quotes} into more acceptable elements.

  16. Fast-neutron activation analysis of manganese nodules

    International Nuclear Information System (INIS)

    Michaelis, W.; Fanger, H.U.; Mueller, A.; Pepelnik, R.

    1976-01-01

    The present paper describes the development of a new nuclear method that allows rapid determinations of the most relevant metals Ni and Cu without sample treatment, thus being particularly suited for quasi-continuous elemental analyses in mining and processing. The measurement is based on fast-neutron activation using Cockcroft-Walton generators, sealed neutron tubes or, possibly, (α,n)-type natural sources. Fast-neutron activation of manganese nodules is dominated by the (n,p)-reactions on Si, Al, Fe; the (n,α)-reaction on Mn and the (n,2n)-reaction on Cu. By choosing appropriate irradiation and cooling periods gamma-ray activities with comparatively simple spectral distributions are induced. From these spectra the Mn/Fe ratio in the nodules can be determined without the elaborate procedures usually required in absolute methods for eliminating systematic errors from fluctuations in sample and/or irradiation parameters. It is connected with the absolute Ni and Cu contents via well-known geochemical correlations which according to a lot of statistical data apply to quite different deposits and nodule types in the Pacific. Using these correlations the determination of the most important metals reduces to the evaluation of a peak area ratio. Measurements of the neutron flux distribution and the apparent sample density are unnecessary. The simple structure of the spectra allows the application of detectors with modest energy resolution, e.g. scintillation counters which can be manufactured as ruggedized crystal assemblies with great resistance to thermal and mechanical shock. The method is described in detail and possible interference, in particular from thermal and epithermal neutrons, are discussed. (orig.) [de

  17. An attempt to fabricate an ion injection type fast neutron dosimeter

    International Nuclear Information System (INIS)

    Pells, G.P.; Hughes, A.E.

    1976-10-01

    This report describes the results of work carried out to investigate a novel type of solid state, fast neutron dosimeter. The concept and quantitative features of the dosimeter, in which collisions between fast neutrons and ions in a source compound cause the ions to be injected into a host compound where they could then be detected by their characteristic luminescence, are described. It is shown that with the aid of a complex reader mrad sensitivities should in principle be possible. Initial experiments showed that accelerator implantation of Bi 3+ ions into CaO gives a linear dependence of luminescence output with fluence of activator ions. A number of host/activator combinations were investigated from which SiO 2 :Gd 3+ appeared the most promising. Host/activator configurations are briefly considered. The production of compacts of SiO 2 and Gd 2 O 3 ultrafine powders is described. Attempts were made to characterise these compacts using scanning electron microscopy and luminescence spectroscopy. After fast neutron irradiation to 250 Mrad no Gd 3+ ion injection could be detected. An alternative configuration of ultrafine SiO 2 powder dispersed in a solid Gd(NO 3 ) 3 .5H 2 O matrix is described but again no Gd 3+ ion injection into the SiO 2 could be detected after fast neutron irradiation. Perspex, as a host, was also tried without success. An appendix is included which demonstrates that the lack of success in detecting ion-injection may be largely due to the optically opaque nature of the specimens that could be produced. (author)

  18. Fast neutron dosimetry. Progress report, July 1, 1979-June 30, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Attix, F.H.

    1980-01-01

    Progress is reported in: the development and testing of new gas mixtures more suitable for fast neutron dosimetry using the common A150-type Tissue-equivalent plastic ion chambers; comparison of photon doses determined with a graphite-walled proportional counter and with paired dosimeters irradiated by 14.8-MeV neutrons; a detector for the direct measurement of LET distributions from irradiation with fast neutrons; LET distributions from fast neutron irradiation of TE-plastic and graphite measured in a cylindrically symmetric geometry; progress in development of a tandem fast neutron and /sup 60/Co gamma ray source irradiation facility; an approach to the correlation of cellular response with lineal energy; calculated and measured HTO atmospheric dispersion rates within meters of a release site; application of cavity theory to fast neutrons; and fast neutron dosimetry by thermally stimulated currents in Al/sub 2/O/sub 3/. (GHT)

  19. Fast neutron dosimetry. Progress report, July 1, 1979-June 30, 1980

    International Nuclear Information System (INIS)

    Attix, F.H.

    1980-01-01

    Progress is reported in: the development and testing of new gas mixtures more suitable for fast neutron dosimetry using the common A150-type Tissue-equivalent plastic ion chambers; comparison of photon doses determined with a graphite-walled proportional counter and with paired dosimeters irradiated by 14.8-MeV neutrons; a detector for the direct measurement of LET distributions from irradiation with fast neutrons; LET distributions from fast neutron irradiation of TE-plastic and graphite measured in a cylindrically symmetric geometry; progress in development of a tandem fast neutron and 60 Co gamma ray source irradiation facility; an approach to the correlation of cellular response with lineal energy; calculated and measured HTO atmospheric dispersion rates within meters of a release site; application of cavity theory to fast neutrons; and fast neutron dosimetry by thermally stimulated currents in Al 2 O 3

  20. Deuterated scintillators and their application to neutron spectroscopy

    International Nuclear Information System (INIS)

    Febbraro, M.; Lawrence, C.C.; Zhu, H.; Pierson, B.; Torres-Isea, R.O; Becchetti, F.D.; Kolata, J.J.; Riggins, J.

    2015-01-01

    Deuterated scintillators have been used as a tool for neutron spectroscopy without Neutron Time-of-Flight (n-ToF) for more than 30 years. This article will provide a brief historical overview of the technique and current uses of deuterated scintillators in the UM-DSA and DESCANT arrays. Pulse-shape discrimination and spectrum unfolding with the maximum-likelihood expectation maximization algorithm will be discussed. Experimental unfolding and cross section results from measurements of (d,n), ( 3 He,n) and (α,n) reactions are shown

  1. On the problem of monitoring the neutron parameters of the Fast Energy Amplifier

    International Nuclear Information System (INIS)

    Behringer, K.; Wydler, P.

    1998-10-01

    The conceptual Fast Energy Amplifier, proposed by Rubbia et al. (1995), consists of a combination of a U-233/Th-232 fuelled fast-neutron subcritical facility with a proton accelerator. An intense beam of 1 GeV protons is injected into liquid lead at the core centre and drives the reactor by producing spallation neutrons. The burst of spallation neutrons produced by a single proton alters the basic neutron statistics which are well known for thermal neutrons in conventional nuclear reactors. A short assessment of standard neutron noise analysis methods is made with respect to monitoring neutron parameter data. (author)

  2. Simulation and prototyping of 2 m long resistive plate chambers for detection of fast neutrons and multi-neutron event identification

    Energy Technology Data Exchange (ETDEWEB)

    Elekes, Z., E-mail: z.elekes@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Bemmerer, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Caesar, C. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Cowan, T.C. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Hehner, J.; Heil, M. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Rossi, D. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Röder, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Simon, H. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Sobiella, M.; Stach, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Reinhardt, T. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Wagner, A.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Zilges, A. [Universität zu Köln, Köln (Germany); Zuber, K. [Technische Universität Dresden, Dresden (Germany)

    2013-02-11

    Resistive plate chamber (RPC) prototypes of 2 m length were simulated and built. The experimental tests using a 31 MeV electron beam, discussed in details, showed an efficiency higher than 90% and an excellent time resolution of around σ=100ps. Furthermore, comprehensive simulations were performed by GEANT4 toolkit in order to study the possible use of these RPCs for fast neutron (200 MeV–1 GeV) detection and multi-neutron event identification. The validation of simulation parameters was carried out via a comparison to experimental data. A possible setup for invariant mass spectroscopy of multi-neutron emission is presented and the characteristics are discussed. The results show that the setup has a high detection efficiency. Its capability of determining the momentum of the outgoing neutrons and reconstructing the relative energy between the fragments from nuclear reactions is demonstrated for different scenarios.

  3. Preliminary investigations of Monte Carlo Simulations of neutron energy and LET spectra for fast neutron therapy facilities

    International Nuclear Information System (INIS)

    Kroc, T.K.

    2009-01-01

    No fast neutron therapy facility has been built with optimized beam quality based on a thorough understanding of the neutron spectrum and its resulting biological effectiveness. A study has been initiated to provide the information necessary for such an optimization. Monte Carlo studies will be used to simulate neutron energy spectra and LET spectra. These studies will be bench-marked with data taken at existing fast neutron therapy facilities. Results will also be compared with radiobiological studies to further support beam quality ptimization. These simulations, anchored by this data, will then be used to determine what parameters might be optimized to take full advantage of the unique LET properties of fast neutron beams. This paper will present preliminary work in generating energy and LET spectra for the Fermilab fast neutron therapy facility.

  4. Fast neutron dosimetry: [Progress report, 1986-1987

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Gould, M.N.; Meisner, L.F.; Pearson, D.W.

    1987-01-01

    A new research area was initiated in ultrasoft x-rays with the University of Wisconsin 1-GeV electron storage ring used as a radiation source. A new beam line and irradiation apparatus was designed and constructed. Amongst the distinguishing features are an irradiation vessel of considerable generality allowing many types of radiological/biological experiments to be performed; the ability to maintain low-pressure, high humidity environments with good control; and a computer controlled sample slide for [X,Y,Z] motions of high precision that allows fully controlled velocities and accelerations for complex sample irradiations. Work in the area of chromosomal aberration studies has continued after the completion of the investigation into the possible synergistic effects of mixed beams of neutrons and photons. Of special interest is the damage dependence on absorbed dose and dose rate for low-dose and low-dose rate exposures to high LET radiation. A unique microdosimetric instrument was employed in the continuing effort to measure dose distribution in LET from fast neutron irradiation of metal-metal oxide walls. Our purpose is to determine this distribution for oxygen, an element of critical importance to fast neutron dosimetry. 31 refs., 7 figs., 2 tabs

  5. Detection of hidden explosives by fast neutron activation analysis

    International Nuclear Information System (INIS)

    Li Xinnian; Guo Junpeng; Luo Wenyun; Wang Chuanshan; Fang Xiaoming; Yu Tailiu

    2008-01-01

    The paper describes the method and principle for detection of hidden explosive by fast neutron activation analysis (FNAA). The method of detection of explosives by FNAA has the specific properties of simple determination equipments, high reliability, and low detecting cost, and would be beneficial to the applicability and popularization in the field of protecting and securing nation. The contents of nitrogen and oxygen in four explosives, more then ten common materials and TNT samples covered with soil, were measured by FNAA. 14 MeV fast neutrons were generated from (d, t) reaction with a 400 kV Cockcroft Walton type accelerator. The two-dimension distributions for nitro- gen and oxygen counting rates per unit mass of determined matters were obtained, and the characteristic area of explosives and non-explosives can be defined. By computer aided pattern recognition, the samples were identified with low false alarm or omission rates. The Monte-Carlo simulation indicates that there is no any radiation at 15 m apart from neutron source and is safe for irradiation after 1 h. It is suggested that FNAA may be potential in remote controlling for detection hidden explosive system with multi-probe large array. (authors)

  6. Fast neutron spectrometry and dosimetry; Spectrometrie et dosimetrie des neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Blaize, S; Ailloud, J; Mariani, J; Millot, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    We have studied fast neutron spectrometry and dosimetry through the recoil protons they produce in hydrogenated samples. In spectrometric, we used nuclear emulsions, in dosimetric, we used polyethylene coated with zinc sulphide and placed before a photomultiplier. (author)Fren. [French] Nous avons etudie la spectrometrie et la dosimetrie des neutrons rapides en utilisant les protons de recul qu'ils produisent dans une matiere hydrogenee. En spectrometrie, nous avons employe des emulsions nucleaires, en dosimetrie, du polyethylene recouvert de sulfure de zinc place devant un photomultiplicateur. (auteur)

  7. Measured and evaluated fast neutron cross sections of elemental nickel

    International Nuclear Information System (INIS)

    Guenther, P.; Smith, A.; Smith, D.; Whalen, J.; Howerton, R.

    1975-07-01

    Fast neutron total and scattering cross sections of elemental nickel are measured. Differential elastic scattering cross sections are determined from incident energies of 0.3 to 4.0 MeV. The cross sections for the inelastic neutron excitation of states at: 1.156 +- 0.015, 1.324 +- 0.015, 1.443 +- 0.015, 2.136 +- 0.013, 2.255 +- 0.030, 2.449 +- 0.030, 2.614 +- 0.020 and 2.791 +- 0.025 MeV are measured to incident neutron energies of 4.0 MeV. The total neutron cross sections are determined from 0.25 to 5.0 MeV. The experimental results are discussed in the context of optical and statistical models. It is shown that resonance width-fluctuation and correlation effects are significant. The present experimental and theoretical results, together with previously reported values, are used to construct a comprehensive evaluated elemental data file in the ENDF format. Some comparisons are made with previously reported evaluated files. In addition, some selected reactions which are widely used in dosimetry and other applications are presented as supplemental evaluated isotopic-data files. The numerical quantities are presented in tabular form. (3 tables, 29 figures)

  8. Research on Fast-Doppler-Broadening of neutron cross sections

    International Nuclear Information System (INIS)

    Li, S.; Wang, K.; Yu, G.

    2012-01-01

    A Fast-Doppler-Broadening method is developed in this work to broaden Continuous Energy neutron cross-sections for Monte Carlo calculations. Gauss integration algorithm and parallel computing are implemented in this method, which is unprecedented in the history of cross section processing. Compared to the traditional code (NJOY, SIGMA1, etc.), the new Fast-Doppler-Broadening method shows a remarkable speedup with keeping accuracy. The purpose of using Gauss integration is to avoid complex derivation of traditional broadening formula and heavy load of computing complementary error function that slows down the Doppler broadening process. The OpenMP environment is utilized in parallel computing which can take full advantage of modern multi-processor computers. Combination of the two can reduce processing time of main actinides (such as 238 U, 235 U) to an order of magnitude of 1∼2 seconds. This new method is fast enough to be applied to Online Doppler broadening. It can be combined or coupled with Monte Carlo transport code to solve temperature dependent problems and neutronics-thermal hydraulics coupled scheme which is a big challenge for the conventional NJOY-MCNP system. Examples are shown to determine the efficiency and relative errors compared with the NJOY results. A Godiva Benchmark is also used in order to test the ACE libraries produced by the new method. (authors)

  9. Random mask optimization for fast neutron coded aperture imaging

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, Kyle [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Univ. of California, Los Angeles, CA (United States); Marleau, Peter [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Brubaker, Erik [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-05-01

    In coded aperture imaging, one of the most important factors determining the quality of reconstructed images is the choice of mask/aperture pattern. In many applications, uniformly redundant arrays (URAs) are widely accepted as the optimal mask pattern. Under ideal conditions, thin and highly opaque masks, URA patterns are mathematically constructed to provide artifact-free reconstruction however, the number of URAs for a chosen number of mask elements is limited and when highly penetrating particles such as fast neutrons and high-energy gamma-rays are being imaged, the optimum is seldom achieved. In this case more robust mask patterns that provide better reconstructed image quality may exist. Through the use of heuristic optimization methods and maximum likelihood expectation maximization (MLEM) image reconstruction, we show that for both point and extended neutron sources a random mask pattern can be optimized to provide better image quality than that of a URA.

  10. Ionizing Energy Depositions After Fast Neutron Interactions in Silicon

    CERN Document Server

    Bergmann, Benedikt; Caicedo, Ivan; Kierstead, James; Takai, Helio; Frojdh, Erik

    2016-01-01

    In this study we present the ionizing energy depositions in a 300 μm thick silicon layer after fast neutron impact. With the Time-of-Flight (ToF) technique, the ionizing energy deposition spectra of recoil silicons and secondary charged particles were assigned to (quasi-)monoenergetic neutron energies in the range from 180 keV to hundreds of MeV. We show and interpret representative measured energy spectra. By separating the ionizing energy losses of the recoil silicon from energy depositions by products of nuclear reactions, the competition of ionizing (IEL) and non-ionizing energy losses (NIEL) of a recoil silicon within the silicon lattice was investigated. The data give supplementary information to the results of a previous measurement and are compared with different theoretical predictions.

  11. Optimization of CR-39 for fast neutron dosimetry applications

    CERN Document Server

    Vilela, E; Giacomelli, G; Giorgini, M; Morelli, B; Patrizii, L; Serra, P; Togo, V

    1999-01-01

    We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: sup 2 sup 4 sup 1 Am-Be, sup 2 sup 5 sup 2 Cf and sup 2 sup 3 sup 8 Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose.

  12. Fast neutron attenuation measurements for detection of illicit materials

    International Nuclear Information System (INIS)

    Lee, Hee Seock; Chung, Chin Wha; Guon, Ki Il; Lee, Bo Young; Ko, Seung Kook; Shin, Yong Mu

    2002-01-01

    Experiments were carried out to develop a novel method using neutron attenuation for the detection of illicit materials. By using pulsed fast neutrons generated from a Bi target bombarded with a 2 GeV electron beam, attenuation spectra of C, N, and O have been measured to study the feasibility of a practical application. The spectral dependence on the material thickness and the geometrical distribution as well as the ability to identify different elements in a layered environment have been studied. For the elements mentioned here, the total cross sections have been obtained from the measured attenuation spectra and compared with ENDF-VI, which showed good agreement. The study confirms that a conventional low energy electron linac can be put into a practical use, and some practical idea is presented

  13. Prototype fast neutron counter for the assay of impure plutonium

    International Nuclear Information System (INIS)

    Wachter, J.R.; Adams, E.L.; Ensslin, N.

    1987-01-01

    A fast coincident neutron counter using liquid scintillators and gamma-ray/neutron pulse-shape discrimination has been constructed for the analysis of plutonium samples with unknown self-multiplication and (α,n) production. The counter was used to measure plutonium-bearing materials that cover a range of masses and (α,n) reaction rates of importance to the safeguards community. Measured values of the 240 Pu effective mass differed, on average, from their declared values by 0.4% for plutonium oxides and by -2.2% for metal and MgO-loaded samples. Poorer results were obtained for materials with large (α,n) reaction rates and low self-multiplication such as plutonium ash and plutonium fluoride

  14. Axial distribution of absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.

    1988-11-01

    The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)

  15. Preliminary studies on the observation of oxygen-18 exchange in coal by Fourier Transform Infrared spectroscopy, investigations in the use of FTIR for coal ultimate analysis, and a fast pneumatic transfer system for 0-18 determination by neutron activation analysis

    International Nuclear Information System (INIS)

    DeKeyser, C.F. Jr.

    1984-01-01

    Use of isotope exchange kinetics for functional group determination in coal is investigated. Net exchange kinetics determined by time dependent Neutron Activation Analysis measurements (NAA) would be related to individual functional group exchange kinetics determined by Fourier Transform Infrared (FTIR) spectroscopy measurements. The work described herein can be grouped into three categories: 1) work relating to the FTIR spectroscopy of coal, 2) work relating to oxygen exchange in coal, and 3) work relating to measurements of O-18 by NAA. Methods are discussed for preparing IR observable samples of coal and ash, obtaining FTIR spectra of these samples, and reducing the spectral data to numerical form. Also included in this category is an investigation into the use of IR spectroscopic methods for the ultimate analysis of coals. An initial attempt at the observation of oxygen exchange in coal is described which includes two exchange schemes and the FTIR spectroscopic observation of their end products. A facile exchange between O-18 water and O-16 in coal was attempted with and without catalysts. Also, the design and construction of a fast pneumatic transfer system for the determination of O-18 is described

  16. Mass-selective Neutron Spectroscopy Beyond the Proton

    International Nuclear Information System (INIS)

    Krzystyniak, M; Seel, A G; Richards, S E; Gutmann, M J; Fernandez-Alonso, F

    2014-01-01

    We discuss ongoing methodological developments underpinning the determination of nuclear-momentum distributions from mass-resolved neutron Compton data of lightweight materials. To this end, two systems are considered in detail, namely, lithium hydride (including its deuterated counterpart) and squaric acid, an organic antiferroelectric material containing hydrogen, carbon, and oxygen. Beyond the usual case of the proton, our approach enables direct access to detailed line shape information associated with the underlying nuclear-momentum distributions of both deuterium and lithium. For oxygen and carbon, mean kinetic energies can also be obtained directly from the neutron data, as demonstrated by a detailed analysis of mass- resolved data from squaric acid. From an instrumentation point of view, this work provides a suitable platform for a detailed assessment of existing capabilities and future developments in mass-selective neutron spectroscopy on the VESUVIO spectrometer at ISIS

  17. Charge exchange spectroscopy as a fast ion diagnostic on TEXTOR

    International Nuclear Information System (INIS)

    Delabie, E.; Jaspers, R. J. E.; Hellermann, M. G. von; Nielsen, S. K.; Marchuk, O.

    2008-01-01

    An upgraded charge exchange spectroscopy diagnostic has been taken into operation at the TEXTOR tokamak. The angles of the viewing lines with the toroidal magnetic field are close to the pitch angles at birth of fast ions injected by one of the neutral beam injectors. Using another neutral beam for active spectroscopy, injected counter the direction in which fast ions injected by the first beam are circulating, we can simultaneously measure a fast ion tail on the blue wing of the D α spectrum while the beam emission spectrum is Doppler shifted to the red wing. An analysis combining the two parts of the spectrum offers possibilities to improve the accuracy of the absolute (fast) ion density profiles. Fast beam modulation or passive viewing lines cannot be used for background subtraction on this diagnostic setup and therefore the background has to be modeled and fitted to the data together with a spectral model for the slowing down feature. The analysis of the fast ion D α spectrum obtained with the new diagnostic is discussed.

  18. Modern methods to improve the accuracy in fast neutron dosimetry

    International Nuclear Information System (INIS)

    Baers, B.; Karnani, H.; Seren, T.

    1985-01-01

    In order to improve the quality of fast neutron dose estimates at the reactor pressure vessel (PV) some modern methods are presented. In addition to basic principles, some error reduction procedures are also presented based on the combined use of relative measurements, direct sample taking from the pressure vessel and the use of iron and niobium as dosimeters. The influence of large systematic errors could be significantly reduced by carrying out relative measurements. This report also presents the successful use of niobium as a dosimeter by destructive treatment of PV samples. (author)

  19. Estimation of sulfur in coal by fast neutron activation

    International Nuclear Information System (INIS)

    Das, G.C.; Bhattacharyya, P.K.

    1995-01-01

    A simple method is described for estimation of sulfur in coal using fast neutron activation of sulfur, i.e. 32 S(n,p) 32 P and subsequent measurement of 32 P β-activity (1.72 MeV) by a Geiger-Mueller counter. Since the sulfur content of Indian coal ranges from 0.25 to 3%, simulated samples of coal containing sulfur in the range from 0.25 to 3% and common impurities like oxides of aluminium, calcium, iron and silicon have been used to establish the method. (author). 6 refs., 2 figs., 1 tab

  20. Nuclear theory for fast neutron nuclear data evaluation

    International Nuclear Information System (INIS)

    1988-11-01

    The proceedings contain all invited and contributed papers presented at the Advisory Group Meeting on Nuclear Theory for Fast Neutron Data Evaluation held in Beijing 12-16 October 1987, as well as the conclusions and recommendations and the Chairman's summary of the meeting. The meeting presentations have been divided into six sessions devoted to the following topics: introductory speech (1 paper), optical potential (9 papers), compound nuclear theory (10 papers), pre-compound nuclear theory (13 papers), isomeric cross-section (1 paper) and intercomparison of nuclear model computer codes (1 paper). A separate abstract was prepared for each of these papers. Refs, figs and tabs

  1. Fast neutrons and the optical model: some observations

    International Nuclear Information System (INIS)

    Smith, A.B.; Lawson, R.D.; Guenther, P.T.

    1985-01-01

    The optical model of fast-neutron-induced phenomena is considered from the observational viewpoint. Experimental characteristics governing the reliability of the modeling are outlined with attention to implications on model parameters and their uncertainties. The physical characteristics of experimentally-deduced ''regional'' and ''specific'' model parameters are examined including: parameter trends with mass and energy, implications of collective effects, and fundamental relations between real and imaginary potentials. These physical properties are illustrated by studies in the A=60 and 90 regions. General trends are identified and outstanding issues cited. Throughout, the approach is that of observational interpretation for basic and applied purposes. 20 refs., 11 figs., 2 tabs

  2. Gas loop - continuous measurement of thermal and fast neutron fluxes

    International Nuclear Information System (INIS)

    Droulers, Y.; Pleyber, G.; Sciers, P.; Maurin, G.

    1964-01-01

    The measurement method described in this report can be applied both to thermal and fast neutron fluxes. A description is given of two practical applications in each of these two domains. This method is particularly suitable for measurements carried out on 'loop' type equipment. The measurement of the relative flux variations are carried out with an accuracy of 5 per cent. The choice of the shape of the gas circuit leaves a considerable amount of liberty for the adaptation of the measurement circuit to the experimental conditions. (authors) [fr

  3. Non-destructive characterization using pulsed fast-thermal neutrons

    International Nuclear Information System (INIS)

    Womble, P.C.

    1995-01-01

    Explosives, illicit drugs, and other contraband materials contain various chemical elements in quantities and ratios that differentiate them from each other and from innocuous substances. Furthermore, the major chemical elements in coal can provide information about various parameters of importance to the coal industry. In both examples, the non-destructive identification of chemical elements can be performed using pulsed fast-thermal neutrons that, through nuclear reactions, excite the nuclei of the various elements. This technique is being currently developed for the dismantling of nuclear weapons classified as trainers, and for the on-line coal bulk analysis. (orig.)

  4. Study on the fast neutron sensitivity of thermoluminescent detectors

    International Nuclear Information System (INIS)

    Szabo, P.P.; Palfalvi, J.

    1984-03-01

    Fast neutron (14.7 MeV) sensitivity of several thermoluminescent detectors was determined. The investigated detectors were MTS-N type pellets (made in Poland) used routinely in the authors' institute for personnel dosimetry, 7 LiF powder used for accident dosimetry, CaSO 4 :Dy and CaSO 4 :Tm powders (made in Hungary) used for enviromental monitoring and space dosimetry. Both free-in-air and on-phantom irradiations were performed. The new results are compared with responses calculated and measured earlier. (author)

  5. Overview of US fast-neutron facilities and testing capabilities

    International Nuclear Information System (INIS)

    Evans, E.A.; Cox, C.M.; Jackson, R.J.

    1982-01-01

    Rather than attempt a cataloging of the various fast neutron facilities developed and used in this country over the last 30 years, this paper will focus on those facilities which have been used to develop, proof test, and explore safety issues of fuels, materials and components for the breeder and fusion program. This survey paper will attempt to relate the evolution of facility capabilities with the evolution of development program which use the facilities. The work horse facilities for the breeder program are EBR-II, FFTF and TREAT. For the fusion program, RTNS-II and FMIT were selected

  6. Calibration of a NE213 detector for neutron spectroscopy

    International Nuclear Information System (INIS)

    Blazquez Martinez, J.; Butragueno Casado, J. L.

    1974-01-01

    This work describes the experimental way followed for getting the calibration of a NE213 detector with a beam of neutrons from the J.E.N. 2 MeV Van de Graaff and using at once pulse shape discrimination. Detector has been used for measuring the spectrum of the fast reactor CORAL-1. There is also included an experimental method in order to get with precision where the Compton edge is placed on the electron spectrum. (Author) 9 refs

  7. Neutron spectroscopy by means of artificial diamond detectors using a remote read out scheme

    International Nuclear Information System (INIS)

    Angelone, M.; Lattanzi, D.; Pillon, M.; Almaviva, S.; Marinelli, M.; Milani, E.; Prestopino, G.; Verona, C.; Verona Rinati, G.; Aielli, G.; Sintonico, R.; Cardarelli, R.

    2009-01-01

    Artificial crystal diamond neutron detectors have been tested since 2003 and they have demonstrated to be reliable and stable as well as to withstand the harsh working condition available in a large tokamak. Up to now they were used to measure the total and time dependent neutron emission while neutron spectroscopy was never attempted. On the other hand neutron spectrometry con yields important information on the burning plasma and it is requested for future experiments that will use DT plasmas so producing 14 MeV neutrons. Neutron spectrometry can only be attempted by using single crystal diamond (SCD) which, as it has been demonstrated, can show an energy resolution (FWHM) as low as 0.5%. However, in ITER, the huge neutron and gamma fluxes as well as the high temperature will not allow the electronics to be located close to the detector measuring point and near the plasma. For this reason it is necessary to develop a new approach in which new detectors able to withstand harsh environments and the electronics are far apart. This is a very challenging task if it is devoted to perform signal Pulse Height Analyses (PHS) with high energy resolution. To exploit this concept a SCD detector covered with a thin layer of 6 LiF was installed at JET during the 2008 experimental campaigns and equipped with a remote read-out scheme located about 100 m away from the detector. The detector's signal was transported up to a conceptually new fast charge amplifier (FCA) developed to fulfill the task by means of a high frequency, single, low attenuation, super-screened cable. This FCA is able to read, stretch (up to 100 ns) and amplify the small (some μV) and ultra fast (< 100 ps wide) signal produced by the radiation in the diamond detector. The signal amplified by the FCA was then processed through a commercial fast digitizer (NI-5114) 250 Ms/sec, 200 MHz equipped with 64 MB ram memory. Both signal amplitude and area can be used to get a PHS spectrum demonstrating the unique

  8. Recent developments in fast spectroscopy for plant mineral analysis

    Directory of Open Access Journals (Sweden)

    Marie evan Maarschalkerweerd

    2015-03-01

    Full Text Available Ideal fertilizer management to optimize plant productivity and quality is more relevant than ever, as global food demands increase along with the rapidly growing world population. At the same time, sub-optimal or excessive use of fertilizers leads to severe environmental damage in areas of intensive crop production. The approaches of soil and plant mineral analysis are briefly compared and discussed here, and the new techniques using fast spectroscopy that offer cheap, rapid and easy-to-use analysis of plant nutritional status are reviewed. The majority of these methods use vibrational spectroscopy, such as Visual-Near Infrared (Vis-NIR and to a lesser extent Ultraviolet (UV and Mid-Infrared (MIR spectroscopy. Advantages of and problems with application of these techniques are thoroughly discussed. Spectroscopic techniques considered having major potential for plant mineral analysis, such as chlorophyll a fluorescence, X-ray fluorescence (XRF and Laser-Induced Breakdown Spectroscopy (LIBS are also described.

  9. Relative measurements of fast neutron contamination in 18-MV photon beams from two linear accelerators and a betatron

    International Nuclear Information System (INIS)

    Gur, D.; Bukovitz, A.G.; Rosen, J.C.; Holmes, B.G.

    1979-01-01

    Fast neutron contamination in photon beams in the 20 MV range have been reported in recent years. In order to determine if the variations were due mainly to differences in measurement procedures, or inherent in the design of the accelerators, three different 18-MV (BJR) photon beams were compared using identical analytical techniques. The units studied were a Philips SL/75-20 and a Siemens Mevatron-20 linear accelerators and a Schimadzu betatron. Gamma spectroscopy of an activated aluminum foil was the method used. By comparing the relative amounts of neutron contamination, errors associated with absolute measurements such as detector efficiency and differences in activation foils were eliminated. Fast neutron contaminations per rad of x rays in a ratio of 6.7:3.7:1 were found for the Philips, Schimadzu and Siemens accelerators, respectively

  10. Microstructural evolution of martensitic steels during fast neutron iradiation

    International Nuclear Information System (INIS)

    Maziasz, P.J.

    1989-01-01

    Irradiation of martensitic/ferritic steels with fast neutrons (E > 0.1 MeV) to displacement damage levels of 30--50 dpa at temperatures of 300--500 degree C produces significant changes in the as-tempered microstructure. Dislocation loops and networks can be produced, irradiation-induced precipitates can form, the lath/subgrain boundary structure and the thermal precipitates produced during tempering can become unstable, and if helium is present, bubbles and voids can form. These microstructural changes caused by irradiation can have important effects on the properties of this class of steels for both fast breeder reactor (FBR) and magnetic fusion reactor (MFR) applications. The purpose of this paper is to compare reactor-irradiated and long-term thermally aged 9Cr--1MoVNb specimens, in order to distinguish effects due to displacement damage from those caused by elevated-temperature exposure alone. 7 refs., 1 fig

  11. A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Cester, D., E-mail: davide.cester@gmail.com [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Lunardon, M.; Moretto, S. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Pino, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Sajo-Bohus, L. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Apartado 89000, 1080 A Caracas (Venezuela, Bolivarian Republic of); Stevanato, L.; Bonesso, I.; Turato, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2016-09-11

    A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

  12. A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

    International Nuclear Information System (INIS)

    Cester, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pino, F.; Sajo-Bohus, L.; Stevanato, L.; Bonesso, I.; Turato, F.

    2016-01-01

    A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

  13. Microstructural evolution in fast-neutron-irradiated austenitic stainless steels

    International Nuclear Information System (INIS)

    Stoller, R.E.

    1987-12-01

    The present work has focused on the specific problem of fast-neutron-induced radiation damage to austenitic stainless steels. These steels are used as structural materials in current fast fission reactors and are proposed for use in future fusion reactors. Two primary components of the radiation damage are atomic displacements (in units of displacements per atom, or dpa) and the generation of helium by nuclear transmutation reactions. The radiation environment can be characterized by the ratio of helium to displacement production, the so-called He/dpa ratio. Radiation damage is evidenced microscopically by a complex microstructural evolution and macroscopically by density changes and altered mechanical properties. The purpose of this work was to provide additional understanding about mechanisms that determine microstructural evolution in current fast reactor environments and to identify the sensitivity of this evolution to changes in the He/dpa ratio. This latter sensitivity is of interest because the He/dpa ratio in a fusion reactor first wall will be about 30 times that in fast reactor fuel cladding. The approach followed in the present work was to use a combination of theoretical and experimental analysis. The experimental component of the work primarily involved the examination by transmission electron microscopy of specimens of a model austenitic alloy that had been irradiated in the Oak Ridge Research Reactor. A major aspect of the theoretical work was the development of a comprehensive model of microstructural evolution. This included explicit models for the evolution of the major extended defects observed in neutron irradiated steels: cavities, Frank faulted loops and the dislocation network. 340 refs., 95 figs., 18 tabs

  14. The resonant detector and its application to epithermal neutron spectroscopy

    International Nuclear Information System (INIS)

    Gorini, G.; Perelli-Cippo, E.; Tardocchi, M.; Andreani, C.; D'Angelo, A.; Pietropaolo, A.; Senesi, R.; Imberti, S.; Bracco, A.; Previtali, E.; Pessina, G.; Rhodes, N.J.; Schooneveld, E.M.

    2004-01-01

    New perspectives for epithermal neutron spectroscopy are being opened by the development of the resonant detector (RD) and its use on inverse geometry time of flight spectrometers at spallation sources. The RD was first proposed in the 1980s and was recently brought to a performance level exceeding conventional neutron-sensitive Li-glass scintillator detectors. It features a photon counter coupled to a neutron analyzer foil. Resonant neutron absorption in the foil results in the emission of prompt gamma rays that are detected in the photon counter. The dimensions of the RD set the spatial resolution that can be achieved, ranging from a fraction of a cm to several cm. It can thus be tailored to the construction of detector arrays of different geometry. The main results of the research on this kind of detector are reported leading to the present optimized RD design based on a combination of YAP scintillation photon counter and uranium or gold analyzer foils. This detector has already been selected for application in the upgrade of the VESUVIO spectrometer on ISIS. A special application is the Very Low Angle Detector (VLAD) bank, which will extend the kinematical region for neutron scattering to low momentum transfer ( -1 ) whilst still keeping energy transfer >1 eV, thus allowing new experimental studies in condensed matter systems. The first results of tests made with prototype VLAD detectors are presented, confirming the usefulness of the RD for measurements at scattering angles as low as 2-5 deg

  15. Neutron Capture Gamma-Ray Spectroscopy. Proceedings of the International Symposium on Neutron Capture Gamma-Ray Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1969-11-15

    Experimental capabilities in the field of neutron capture gamma-ray spectroscopy have expanded greatly in the last few years; this has been due in large part to the advent of high-quality Ge(Li) detectors, improvements in electronic data processing, and improvements in bent-crystal spectrometers. Previously unsuspected phenomena, such as the '5. 5-MeV1 anomaly, have appeared and new research tools, such as neutron guide tubes, have been brought into use. Equally exciting developments have occurred in the theory of neutron capture. Complex spectra have yielded to analysis after account had been taken of such effects as vibration, rotation and Coriolis forces, and the theoretical prediction of capture spectra seems to be a future possibility. In view of the International Atomic Energy Agency's close interest in this subject and the need for an international exchange of ideas to analyse and study the latest developments, the organizers of the Symposium felt that work on neutron capture gamma-ray spectroscopy had achieved such valuable and significant results that the time had come for this information to be presented, examined and discussed internationally.

  16. Neutron Capture Gamma-Ray Spectroscopy. Proceedings of the International Symposium on Neutron Capture Gamma-Ray Spectroscopy

    International Nuclear Information System (INIS)

    1969-01-01

    Experimental capabilities in the field of neutron capture gamma-ray spectroscopy have expanded greatly in the last few years; this has been due in large part to the advent of high-quality Ge(Li) detectors, improvements in electronic data processing, and improvements in bent-crystal spectrometers. Previously unsuspected phenomena, such as the '5. 5-MeV1 anomaly, have appeared and new research tools, such as neutron guide tubes, have been brought into use. Equally exciting developments have occurred in the theory of neutron capture. Complex spectra have yielded to analysis after account had been taken of such effects as vibration, rotation and Coriolis forces, and the theoretical prediction of capture spectra seems to be a future possibility. In view of the International Atomic Energy Agency's close interest in this subject and the need for an international exchange of ideas to analyse and study the latest developments, the organizers of the Symposium felt that work on neutron capture gamma-ray spectroscopy had achieved such valuable and significant results that the time had come for this information to be presented, examined and discussed internationally

  17. Fast neutron activation analysis using short-lived radionuclides

    International Nuclear Information System (INIS)

    Salma, I.; Zemplen-Papp, E.

    1993-01-01

    Fast neutron activation analysis experiments were performed to investigate the analytical possibilities and prospective utilization of short-lived activation products. A rapid pneumatic transfer system for use with neutron generators has been installed and applied for detecting radionuclides with a half-life from ∼300 ms to 20 s. The transport time for samples of total mass of 1-4 g is between 130 and 160 ms for pressurized air of 0.1-0.4 MPa. The reproducibility of transport times is less than 2%. The employed method of correcting time-dependent counting losses is based on the virtual pulse generator principle. The measuring equipment consists of CAMAC modules and a special gating circuit. Typical time distributions of counting losses are presented. The same 14 elements were studied by the conventional activation method (single irradiation and single counting) by both a typical pneumatic transport system (run time 3 s) and the fast pneumatic transport facility. Furthermore, the influence of the cyclic activation technique on the elemental sensitivities was investigated. (author) 15 refs.; 5 figs.; 3 tabs

  18. Bubble masks for time-encoded imaging of fast neutrons.

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John T.; Sweany, Melinda; Throckmorton, Daniel J.

    2013-09-01

    Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is inducedtypically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gapsbubblespropagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.

  19. Dose Calibration of the ISS-RAD Fast Neutron Detector

    Science.gov (United States)

    Zeitlin, C.

    2015-01-01

    The ISS-RAD instrument has been fabricated by Southwest Research Institute and delivered to NASA for flight to the ISS in late 2015 or early 2016. ISS-RAD is essentially two instruments that share a common interface to ISS. The two instruments are the Charged Particle Detector (CPD), which is very similar to the MSL-RAD detector on Mars, and the Fast Neutron Detector (FND), which is a boron-loaded plastic scintillator with readout optimized for the 0.5 to 10 MeV energy range. As the FND is completely new, it has been necessary to develop methodology to allow it to be used to measure the neutron dose and dose equivalent. This talk will focus on the methods developed and their implementation using calibration data obtained in quasi-monoenergetic (QMN) neutron fields at the PTB facility in Braunschweig, Germany. The QMN data allow us to determine an approximate response function, from which we estimate dose and dose equivalent contributions per detected neutron as a function of the pulse height. We refer to these as the "pSv per count" curves for dose equivalent and the "pGy per count" curves for dose. The FND is required to provide a dose equivalent measurement with an accuracy of ?10% of the known value in a calibrated AmBe field. Four variants of the analysis method were developed, corresponding to two different approximations of the pSv per count curve, and two different implementations, one for real-time analysis onboard ISS and one for ground analysis. We will show that the preferred method, when applied in either real-time or ground analysis, yields good accuracy for the AmBe field. We find that the real-time algorithm is more susceptible to chance-coincidence background than is the algorithm used in ground analysis, so that the best estimates will come from the latter.

  20. Workshop on the next plan for the study of 'physics of fast neutron reactions and measurements'

    International Nuclear Information System (INIS)

    1985-03-01

    A work shop titled ''Physics of fast neutron reaction and measurements'' was held on 25 December 1984, where discussions were made on the new approach and techniques for neutron measurements. The possibilities of experimental tests with AVF cyclotron was also discussed. The followings are the list of papers presented at the work shop (all papers are written in Japanese except for the abstracts). (1) Monoenergetic neutron beam in Tohoku Cyclotron. (2) Spin-dependent response probed in (p,n) and (n,p) reactions. (3) Measurement of D(n,p) 2n reaction and instrumentation for (n,x) reactions in the 40 - 80 MeV region. (4) Two comments related to the neutron reaction. (5) High energy neutron production facilities in the world and a possibility of neutron induced reaction experiments at RCNP. (6) A neutron counter by detection of recoil protons with solid state detectors and development of neutron source by heavy ions. (7) The measurement of neutrons with the recoil detector. (8) Polarization transfer measurements (Py, Dss, Ds 1 , · · ·) with fast neutron beams. (9) Neutron elastic scattering. (10) Neutron capture gamma reaction and effective charge. (11) Comparison between neutron and charged particle induced reactions. (12) Study of giant resonances by fast neutrons. (Aoki, K.)

  1. A fast and flexible reactor physics model for simulating neutron spectra and depletion in fast reactors - 202

    International Nuclear Information System (INIS)

    Recktenwald, G.D.; Bronk, L.A.; Deinert, M.R.

    2010-01-01

    Determining the time dependent concentration of isotopes within a nuclear reactor core is central to the analysis of nuclear fuel cycles. We present a fast, flexible tool for determining the time dependent neutron spectrum within fast reactors. The code (VBUDS: visualization, burnup, depletion and spectra) uses a two region, multigroup collision probability model to simulate the energy dependent neutron flux and tracks the buildup and burnout of 24 actinides, as well as fission products. While originally developed for LWR simulations, the model is shown to produce fast reactor spectra that show high degree of fidelity to available fast reactor benchmarks. (authors)

  2. Fast neutron measurements with 7Li and 6Li enriched CLYC scintillators

    International Nuclear Information System (INIS)

    Giaz, A.; Blasi, N.; Boiano, C.; Brambilla, S.; Camera, F.; Cattadori, C.; Ceruti, S.; Gramegna, F.; Marchi, T.; Mattei, I.; Mentana, A.; Million, B.; Pellegri, L.; Rebai, M.; Riboldi, S.; Salamida, F.; Tardocchi, M.

    2016-01-01

    The recently developed Cs 2 LiYCl 6 :Ce (CLYC) crystals are interesting scintillation detectors not only for their gamma energy resolution (<5% at 662 keV) but also for their capability to identify and measure the energy of both gamma rays and fast/thermal neutrons. The thermal neutrons were detected by the 6 Li(n,α)t reaction while for the fast neutrons the 35 Cl(n,p) 35 S and 35 Cl(n,α) 32 P neutron-capture reactions were exploited. The energy of the outgoing proton or α particle scales linearly with the incident neutron energy. The kinetic energy of the fast neutrons can be measured using both the Time Of Flight (TOF) technique and using the CLYC energy signal. In this work, the response to monochromatic fast neutrons (1.9–3.8 MeV) of two CLYC 1″×1″ crystals was measured using both the TOF and the energy signal. The observables were combined to identify fast neutrons, to subtract the thermal neutron background and to identify different fast neutron-capture reactions on 35 Cl, in other words to understand if the detected particle is an α or a proton. We performed a dedicated measurement at the CN accelerator facility of the INFN Legnaro National Laboratories (Italy), where the fast neutrons were produced by impinging a proton beam (4.5, 5.0 and 5.5 MeV) on a 7 LiF target. We tested a CLYC detector 6 Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector 7 Li-enriched at more than 99%, which is suitable for fast neutron measurements.

  3. High resolution neutron spectroscopy - a tool for the investigation of dynamics of polymers and soft matter

    International Nuclear Information System (INIS)

    Monkenbusch, M.; Richter, D.

    2007-01-01

    Neutron scattering, with the ability to vary the contrast of molecular items by hydrogen/deuterium exchanges, is an invaluable tool for soft matter research. Besides the structural information on the mesoscopic scale that is obtained by diffraction methods like small angle neutron scattering, the slow dynamics of molecular motion on mesoscopic scale is accessible by high resolution neutron spectroscopy. The basic features of neutron backscattering spectroscopy, and in particular neutron spin-echo spectroscopy, are presented, in combination with illustrations of results from polymer melt dynamics to protein dynamics which are obtained by these techniques. (authors)

  4. Assessment of fast and thermal neutron ambient dose equivalents around the KFUPM neutron source storage area using nuclear track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fazal-ur-Rehman [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: fazalr@kfupm.edu.sa; Al-Jarallah, M.I. [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Abu-Jarad, F. [Radiation Protection Unit, Environmental Protection Department, Saudi Aramco, P. O. Box 13027, Dhahran 31311 (Saudi Arabia); Qureshi, M.A. [Center for Applied Physical Sciences, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2005-11-15

    A set of five {sup 241}Am-Be neutron sources are utilized in research and teaching at King Fahd University of Petroleum and Minerals (KFUPM). Three of these sources have an activity of 16Ci each and the other two are of 5Ci each. A well-shielded storage area was designed for these sources. The aim of the study is to check the effectiveness of shielding of the KFUPM neutron source storage area. Poly allyl diglycol carbonate (PADC) Nuclear track detectors (NTDs) based fast and thermal neutron area passive dosimeters have been utilized side by side for 33 days to assess accumulated low ambient dose equivalents of fast and thermal neutrons at 30 different locations around the source storage area and adjacent rooms. Fast neutron measurements have been carried out using bare NTDs, which register fast neutrons through recoils of protons, in the detector material. NTDs were mounted with lithium tetra borate (Li{sub 2}B{sub 4}O{sub 7}) converters on their surfaces for thermal neutron detection via B10(n,{alpha})Li6 and Li6(n,{alpha})H3 nuclear reactions. The calibration factors of NTD both for fast and thermal neutron area passive dosimeters were determined using thermoluminescent dosimeters (TLD) with and without a polyethylene moderator. The calibration factors for fast and thermal neutron area passive dosimeters were found to be 1.33 proton tracks cm{sup -2}{mu}Sv{sup -1} and 31.5 alpha tracks cm{sup -2}{mu}Sv{sup -1}, respectively. The results show variations of accumulated dose with the locations around the storage area. The fast neutron dose equivalents rates varied from as low as 182nSvh{sup -1} up to 10.4{mu}Svh{sup -1} whereas those for thermal neutron ranged from as low as 7nSvh{sup -1} up to 9.3{mu}Svh{sup -1}. The study indicates that the area passive neutron dosimeter was able to detect dose rates as low as 7 and 182nSvh{sup -1} from accumulated dose for thermal and fast neutrons, respectively, which were not possible to detect with the available active neutron

  5. Fast neutron dosimetry in research reactors; Dosimetrie en neutrons rapides dans les reacteurs de recherche

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    This work chiefly concerns the measurement of fast neutron fluxes by means of threshold detectors. It is shown first that the cross sections to use for measurements by threshold detectors depend largely on the neutron spectrum, that is the position in which the measurement is performed. The spectrum is determined by calculation for several positions in the piles EL2 and EL3; from this can be deduced the cross-sections to be used for the measurements carried out in these positions. In the last part of the report, possible methods for the experimental determination of the spectrum are indicated. (author) [French] On etudie principalement la mesure des flux de neutrons rapides a l'aide de detecteurs a seuil. On montre d'abord que les sections efficaces a utiliser pour les mesures par detecteurs a seuil, dependent grandement du spectre des neutrons, c'est-a-dire de l'emplacement ou s'effectue la mesure. La determination du spectre est effectuee par le calcul pour plusieurs emplacements des piles EL2 et EL3; on en deduit les sections efficaces a utiliser pour les mesures effectuees a ces emplacements. Dans la derniere partie du rapport, on indique quelles methodes sont possibles pour la determination experimentale du spectre. (auteur)

  6. Neutron transport. Physics and calculation of nuclear reactors with applications to pressurized water reactors and fast neutron reactors. 2 ed.

    International Nuclear Information System (INIS)

    Bussac, J.; Reuss, P.

    1985-01-01

    This book presents the main physical bases of neutron theory and nuclear reactor calculation. 1) Interactions of neutrons with matter and basic principles of neutron transport; 2) Neutron transport in homogeneous medium and the neutron field: kinetic behaviour, slowing-down, resonance absorption, diffusion equation, processing methods; 3) Theory of a reactor constituted with homogeneous zones: critical condition, kinetics, separation of variables, calculation and neutron balance of the fundamental mode, one-group and multigroup theories; 4) Study of heterogeneous cell lattices: fast fission factor, resonance absorption, thermal output factor, diffusion coefficient, computer codes; 5) Operation and control of reactors: perturbation theory, reactivity, fuel properties evolution, poisoning by fission products, calculation of a reactor and fuel management; 6) Study of some types of reactors: PWR and fast breeder reactors, the main reactor types of the present French program [fr

  7. Integral test of JENDL dosimetry file using fast neutron field in the Experimental Fast Reactor JOYO

    International Nuclear Information System (INIS)

    Aoyama, Takafumi; Sekine, Takashi

    1999-09-01

    In order to evaluate the applicability of the JENDL dosimetry file, an integral test using a fast neutron spectrum field in the Experimental Fast Reactor JOYO Mark-II core was performed. The dosimeter set consisting of eight reactions of 46 Ti(n,p) 46 Sc, 54 Fe(n,p) 54 Mn, 58 Fe(n,γ) 59 Fe, 58 Ni(n,p) 58 Co, 59 Co(n,γ) 60 Co, 63 Cu(n,α) 60 Co, 238 U fission and 237 Np fission was irradiated for approximately 30 days near the core center of the JOYO Mk-II. Neutron flux at the dosimeter position was calculated using the two dimensional discrete ordinate transport code 'DORT'. The core configuration was modeled in XY geometry, and the 100 group cross section set of JSD-J2 / JFT-J2, which was processed from JENDL-2, was utilized. The absolute value of neutron flux was normalized so that the 235 U fission rate using the calculated neutron spectrum agreed with the measured reaction rate. The 103 group cross section data were processed by 'NJOY' code for nuclides to be used in the JOYO dosimetry. As the results of integral test for JENDL/D-99 (new file) and JENDL/D-91 (previous file), calculated values by JENDL/D-99 agreed well with the experimental values, and the C/E ratios ranged from 0.95 to 1.22. By comparing the results between JENDL/D-99 and JENDL/D-91, small differences exist, except for 58 Fe(n, γ) 59 Fe reaction, which was improved significantly in JENDL/D-99. (author)

  8. How resilient is the soybean genome? Insights from fast neutron mutagenesis

    Science.gov (United States)

    Previously, we described the development of a fast neutron mutant population resource in soybean and identified mutations of interest through phenotypic screening. Here, we consider the resiliency of the soybean genome by examining genomic rearrangements and mutations that arise from fast neutron ra...

  9. Neutron and gamma ray streaming experiments at the fast neutron source reactor 'YAYOI'

    International Nuclear Information System (INIS)

    Oka, Yoshiaki; Yanagisawa, Ichiro; Akiyama, Masatsugu; An, Shigehiro

    1979-07-01

    Neutron and gamma ray streaming experiments were performed in the ducts and cavities that were located in the heavy concrete shields of the fast neutron source reactor YAYOI of University of Tokyo. The configurations have the feature that the streaming through the ducts are occurred following the scattering in the cavity. The axes of the ducts are perpendicular to the source radiation from the core. The spectrum of the source was modified by putting a plug in the beam hole of the core. An aluminum plug and the plug which contains paraffin were used. The decay in the ducts, however, hardly depends on the source spectrum. The decay in the ducts is nearly exponential. (author)

  10. Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

    CERN Document Server

    Flanagan, K T; Ruiz, R F Garcia; Budincevic, I; Procter, T J; Fedosseev, V N; Lynch, K M; Cocolios, T E; Marsh, B A; Neyens, G; Strashnov, I; Stroke, H H; Rossel, R E; Heylen, H; Billowes, J; Rothe, S; Bissell, M L; Wendt, K D A; de Groote, R P; De Schepper, S

    2013-01-01

    The magnetic moments and isotope shifts of the neutron-deficient francium isotopes Fr202-205 were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1\\% was measured for Fr-202. The background from nonresonant and collisional ionization was maintained below one ion in 10(5) beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to Fr-205, with a departure observed in Fr-203 (N = 116).

  11. Bulk moisture determination in building materials by fast neutron/gamma technique

    International Nuclear Information System (INIS)

    Padron Diaz, I.; Felipe Desdin, L.; Martin Hernandez, G.; Shtejer, K.; Perez Tamayo, N.; Ceballos, C.; Lemus, O.

    1998-01-01

    Fast Neutron/Gamma Transmission technique has been improved to allow to measure moisture content in building materials. In order to improve fast neutron/gamma discrimination in the transmission system employing the NE-213 scintillation detector a pulse shape discrimination system was constructed at the CEADEN. A separate neutron/gamma detection approach was used with neutron transmission measurement using an Am-Be neutron source and a BF 3 detector and gamma transmission measurement using a collimated 137 Cs source and a NaI scintillator

  12. Moessbauer spectroscopy on amorphous Fe/sub x/Ni/sub 80-x/B20 after neutron irradiation

    International Nuclear Information System (INIS)

    Sitek, J.; Miglierini, M.

    1985-01-01

    Amorphous Fe/sub x/Ni/sub 80-x/B 20 glassy alloys (x = 40, 50, 60, and 70) irradiated with fast neutrons in a fluence range of 10 14 to 10 19 cm -2 were investigated by Moessbauer spectroscopy. There were some significant changes in the Moessbauer spectrum parameters of the 10 19 cm -2 irradiated samples except Fe 40 Ni 40 B 20 . This corresponds to a change in the direction of the easy axis of magnetization. The measurements show that the resistance of the Fe-Ni-B system against neutron irradiation improves with increasing Ni content up to a certain point

  13. Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source

    International Nuclear Information System (INIS)

    Tarifeño-Saldivia, Ariel; Soto, Leopoldo

    2014-01-01

    This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode. (paper)

  14. Detection of fast neutrons in a plastic scintillator using digital pulse processing to reject gammas

    International Nuclear Information System (INIS)

    Reeder, P.L.; Peurrung, A.J.; Hansen, R.R.; Stromswold, D.C.; Hensley, W.K.; Hubbard, C.W.

    1999-01-01

    We report on neutron-gamma discrimination in a plastic scintillator based on the time delay inherent in second and third chance neutron scattering. Because of the time delay (∼3 ns) between the first and second scattering of a neutron, calculations of gammas and neutrons in a plastic scintillator predict that a neutron signal should be significantly broader than a pulse from a gamma event. Experimentally, we have used a fast digital oscilloscope coupled to a computer to examine individual pulses from neutron or gamma induced signals in fast scintillators coupled to a fast PMT. Individual neutron-induced signals were consistent with the predictions of our model, but gamma pulses were broader than expected. We present various tests to understand this phenomenon and discuss a way to overcome this problem

  15. Indium antimonide crystal defects formed by fast neutron irradiation

    International Nuclear Information System (INIS)

    Vitovskij, N.A.; Dolgolenko, A.P.; Mashovets, T.V.; Oganesyan, O.V.

    1979-01-01

    It is shown, that indium antimonide irradiation with fast neutrons of reactor results in the formation of disorded regions with a mean radius of approximately 130 A surrounded with space charge regions forming barriers for main carriers. But the found values of defect cluster depolarization coefficient (Lsub(x)sup(n)=0.18 and Lsub(x)sup(p)=0.29) show, that the clusters have marked conductivity for main charge carriers. The found position of the Fermi level in the disorded regions Esub(F)=Esub(c)-0.085 eV does not depend on the impurity type and its concentration in an initial material. The disorded regions play the main part in charge carrier scattering at low temperatures and markedly contribute to the change of mobility at 80 K. It is found, that irradiation temperature change in the range from 77 to 300 K does not effect practically on the disorded region parameters

  16. FAST RADIO BURSTS FROM THE INSPIRAL OF DOUBLE NEUTRON STARS

    International Nuclear Information System (INIS)

    Wang, Jie-Shuang; Yang, Yuan-Pei; Dai, Zi-Gao; Wang, Fa-Yin; Wu, Xue-Feng

    2016-01-01

    In this Letter, we propose that a fast radio burst (FRB) could originate from the magnetic interaction between double neutron stars (NSs) during their final inspiral within the framework of a unipolar inductor model. In this model, an electromotive force is induced on one NS to accelerate electrons to an ultra-relativistic speed instantaneously. We show that coherent curvature radiation from these electrons moving along magnetic field lines in the magnetosphere of the other NS is responsible for the observed FRB signal, that is, the characteristic emission frequency, luminosity, duration, and event rate of FRBs can be well understood. In addition, we discuss several implications of this model, including double-peaked FRBs and possible associations of FRBs with short-duration gamma-ray bursts and gravitational-wave events.

  17. Fast neutron detection using solid state nuclear track detectors

    International Nuclear Information System (INIS)

    Vilela, E.C.

    1990-01-01

    CR-39 and Makrofol-E solid state nuclear track detectors were studied aiming their application to fast neutron detection. Optimum etching conditions of those two kinds of materials were determined the followings - the Makrofol-E detector is electrochemically etched in a PEW solution (15% KOH, 40% ethilic alcohol and 45% water) for 2 h., with an applied electric field strength of 30 kV/cm (r/m/s/) and frequency of 2 kHz, at room temperature; - the CR-39 detector is chemically pre-etched during 1 h in a 20% (w/v) NaOH solution at 70 sup(0)C, followed by 13 h electrochemical etch using the same solution at room temperature and an electric field strength of 30 kV/cm (r.m.s.) and frequency of 2 kHz.(E.G.)

  18. Fast Neutron Damage Studies on NdFeB Materials

    CERN Document Server

    Spencer, James; Baldwin, A; Boussoufi, Moe; Pellet, David; Volk, James T; Wolf, Zachary

    2005-01-01

    Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas over the life of the facility. Although the linacs will be superconducting, there are still many potential uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the radiation damage situation for rare earth permanent magnet materials was presented at PAC2003 and our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC2004 where the damage appeared proportional to the distances between the effective operating points and Hc. Here we have extended those doses and included more commercial samples together with the induced radioactivities associated with their respective dopants. Hall probe data for the external induction distributions are compared with vector magnetizatio...

  19. Fast Neutron Damage Studies on NdFeB Materials

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.; Spencer, J.; Wolf, Z.; /SLAC; Baldwin, A.; Pellett, D.; Boussoufi, M.; /UC, Davis

    2005-05-17

    Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) since both accelerator and detectors will be subjected to large fluences of hadrons, leptons and {gamma}'s over the life of the facility [1]. While the linacs will be superconducting, there are still many uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the situation for rare earth, permanent magnet materials was presented at PAC03 [2]. Our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC04 [3]. We have extended the doses, included other manufacturer's samples, and measured induced radioactivities which are discussed in detail.

  20. Electrical properties of indium arsenide irradiated with fast neutrons

    International Nuclear Information System (INIS)

    Kolin, N.G.; Osvenskii, V.B.; Rytova, N.S.; Yurova, E.S.

    1987-01-01

    A study was made of the influence of irradiation with fast reactor neutrons on electrical properties of indium arsenide samples with different dopant concentrations. The laws governing the formation and annealing of radiation defects in indium arsenide were found to be governed by the donor-acceptor interaction. Depending on the density of free carriers in the original crystal, irradiation could produce charged defects of predominantly donor or acceptor types. Donor defects in irradiated InAs samples were annealed practically completely, whereas a considerable fraction of residual acceptor defects was retained even after heat treatment at 900 degree C. The concentration of these residual acceptors depended on the electron density at the annealing temperature

  1. Computer dosimetry for flattened and wedged fast-neutron beams

    International Nuclear Information System (INIS)

    Hogstrom, K.R.; Smith, A.R.; Almond, P.R.; Otte, V.A.; Smathers, J.B.

    1976-01-01

    Beam flattening by the use of polyethylene filters has been developed for the 50-MeV d→Be fast-neutron therapy beam at the Texas AandM Variable-Energy Cyclotron (TAMVEC) as a result of the need for a more uniform dose distribution at depth within the patient. A computer algorithm has been developed that allows the use of a modified decrement line method to calculate dose distributions; standard decrement line methods do not apply because of off-axis peaking. The dose distributions for measured flattened beams are transformed into distributions that are physically equivalent to an unflattened distribution. In the transformed space, standard decrement line theory yields a distribution for any field size which, by applying the inverse transformation, generates the flattened dose distribution, including the off-axis peaking. A semiempirical model has been constructed that allows the calculation of dose distributions for wedged beams from open-beam data

  2. FAST RADIO BURSTS FROM THE INSPIRAL OF DOUBLE NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jie-Shuang; Yang, Yuan-Pei; Dai, Zi-Gao; Wang, Fa-Yin [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, Xue-Feng, E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-05-01

    In this Letter, we propose that a fast radio burst (FRB) could originate from the magnetic interaction between double neutron stars (NSs) during their final inspiral within the framework of a unipolar inductor model. In this model, an electromotive force is induced on one NS to accelerate electrons to an ultra-relativistic speed instantaneously. We show that coherent curvature radiation from these electrons moving along magnetic field lines in the magnetosphere of the other NS is responsible for the observed FRB signal, that is, the characteristic emission frequency, luminosity, duration, and event rate of FRBs can be well understood. In addition, we discuss several implications of this model, including double-peaked FRBs and possible associations of FRBs with short-duration gamma-ray bursts and gravitational-wave events.

  3. Fast neutron irradiation effects on liver chromatin structure

    International Nuclear Information System (INIS)

    Constantinescu, B.; Radu, L.

    1996-01-01

    The growing interest in neutron therapy requires complex studies on the mechanisms of neutron action on biological systems, especially on chromatin. The chromatin was extracted from a normal tissue-livers of Wistar rats - and from a tumoral tissue - Walker tumour maintained on Wistar rats. Irradiation doses from 5 Gy to 100 Gy by fast neutron intense beams produced via d(13.5 MeV) +Be (thick target) reaction at Bucharest U-120 Classical Cyclotron were used. To study the post-irradiation effects, various methods were employed. So, the variation in the 260 nm absorbency in chromatin thermal transition was pursuit. The chromatin-ethidium bromide complexes fluorescence with λ ex =480 nm and λ em =600 nm was analyzed. To determine chromatin DNA strand breaks a fluorimetric method, with cells' suspensions as starting material was used. This method requires a partial treatment with alkali producing three components: T-estimating the total fluorescence of DNA double helix, P-assigning the untwisting rate and B-the blank, where DNA is completely unfolded The percentsge of DNA double strand,-D-, remaining after this treatment, is: %D=100x(P-B)/(T-B). The intrinsic chromatin fluorescence was determined for tyrosine (λ ex =280 nm, λ em =305 nm), specific for badic chromatin prooteins, and for tryptophane (λ ex =290 nm, λ em =345 nm) specific for acid chromatin proteins. Polyacrylamide gel electrophoresis was performed: The double fluorescent labelling of chromatin was realized with acridine orange for DNA and with dansyl chloride for chromatin proteins. Fluorescence intensity determinations were done with λ ex =505 nm, λ em =530 nm for acridine orange and with λ ex =323 nm, λ em =505 nm for dansyl chloride. A Pye Unicam SP 1800 spectrophotometer and a Aminco SPF 500 spectrofluorimeter were employed. (author)

  4. Tests for validation of fast neutron reactors safety

    International Nuclear Information System (INIS)

    Nagata, T.; Yamashita, H.

    2001-01-01

    Japanese scientific research and design enterprises in cooperation with industrial and power generating corporations implement a project on creating a fast neutron reactor of the ultimate safety. One of the basic expected results from such a development is creation of a reactor core structure that is able to eliminate recriticality occurrence in the course of reactor accident involving fuel melting. One of the possible ways to solve this problem is to include pipes (meant for specifying directed (controlled) molten fuel relocation) into fuel assembly structure. In the course of conduction and subsequent implementation of such a design the basic issue is to experimentally confirm the operating capacity of FA having such a structure and that is called FAIDUS. Within EAGLE Project on experimental basis of IAE NNC RK an activity has been started on preparation and conduction of out-of-pile and in-pile tests. During tests a sodium coolant will be used. Studies are conducted by NNC RK in cooperation with the Japanese corporations JAPC and JNC. Basic objective of out-of-pile tests was to obtain preliminary information on fuel relocation behavior under conditions simulating accident involving melting of core consisting of FAIDUS FA, which will help to clarify simulation criteria and to develop the most optimum structure of the experimental channel for reactor experiments conduction. The basic objective of in-pile tests was the experimental confirmation of operating capacity of FAIDUS FA model under reactor conditions. According to the program two tests are planned to be performed at IGR reactor: tests for validation of fast neutron reactor safety, and out-of-pile tests at EAGLE experimental facility without sodium coolant

  5. Calorimetric and ionometric dosimetry for cyclotron produced fast neutrons

    International Nuclear Information System (INIS)

    McDonald, J.C.; Ma, I.C.; Laughlin, J.S.

    1977-01-01

    A portable tissue equivalent (TE) calorimeter, constructed of A-150 plastic, has been employed for the measurement of absorbed dose in two fast neutron fields produced by the 9 Be( 3 He,n) and 9 Be(d,n) interactions. A disc shaped ionization chamber has also been constructed of A-150 plastic and has a collecting volume geometrically equivalent to the calorimeter core (2 cm in diameter and 0.2 cm thick). A flow of methane compounded TE gas was maintained through the chamber at a rate of approximately 5 cc/min during the measurements. The ionization chamber was mounted within an irradiation enclosure which simulated the outer dimensions of the calorimeter housing. In this way, both detectors were placed at the same depth in TE plastic and each received approximately the same scattered radiation. The gamma-ray component of absorbed dose has been determined by the use of a miniature Geiger-Mueller dosimeter. It was found that the response sensitivity ratio for the TE ionization chamber in the two neutron fields relative to the 60 Co gamma-ray field, when normalized to the absorbed dose measured by the TE calorimeter, was approximately 1.07. Uncertainties in these calorimetric and ionometric methods for the measurements of the absorbed dose will be discussed along with measurements of the thermal defect for A-150 TE plastic

  6. Lower detectable limit of sulfur by fast neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shani, G; Cohen, D [Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Nuclear Engineering

    1976-07-01

    For the purpose of air pollution research, the possibility of fast neutron activation analysis of sulfur was investigated. The only reaction that can be used for this purpose is S/sup 34/(n, p)P/sup 34/. A rabbit system was installed, synchronized with a 150 kV D-T neutron generator and an electronic analysing system. The whole system was operated so that the sample was irradiated for 10 sec and the 2.13 MeV ..gamma..-ray was counted for 10 sec. 5 samples were prepared containing sulfur from 0.5 to 0.1 g. Each measurement lasted 30 min and the activity was plotted as a function of sulfur weight. The relative error is increased very much when the amount of sulfur is below 0.1 g. This is what sets the lower detectable limit. Collection of more than 0.1 g of sulfur even during a long collection time means a very high SO/sub 2/ concentration in the air.

  7. A Time of Flight Fast Neutron Imaging System Design Study

    Science.gov (United States)

    Canion, Bonnie; Glenn, Andrew; Sheets, Steven; Wurtz, Ron; Nakae, Les; Hausladen, Paul; McConchie, Seth; Blackston, Matthew; Fabris, Lorenzo; Newby, Jason

    2017-09-01

    LLNL and ORNL are designing an active/passive fast neutron imaging system that is flexible to non-ideal detector positioning. It is often not possible to move an inspection object in fieldable imager applications such as safeguards, arms control treaty verification, and emergency response. Particularly, we are interested in scenarios which inspectors do not have access to all sides of an inspection object, due to interfering objects or walls. This paper will present the results of a simulation-based design parameter study, that will determine the optimum system design parameters for a fieldable system to perform time-of-flight based imaging analysis. The imaging analysis is based on the use of an associated particle imaging deuterium-tritium (API DT) neutron generator to get the time-of-flight of radiation induced within an inspection object. This design study will investigate the optimum design parameters for such a system (e.g. detector size, ideal placement, etc.), as well as the upper and lower feasible design parameters that the system can expect to provide results within a reasonable amount of time (e.g. minimum/maximum detector efficiency, detector standoff, etc.). Ideally the final prototype from this project will be capable of using full-access techniques, such as transmission imaging, when the measurement circumstances allow, but with the additional capability of producing results at reduced accessibility.

  8. Fast neutron (14.5 MeV) radiography: a comparative study

    International Nuclear Information System (INIS)

    Klann, R.T.

    1996-01-01

    Fast neutron (14.5 MeV) radiography is a type of non-destructive analysis tool that offers its own benefits and drawbacks. Because cross-sections vary with energy, a different range of materials can be examined with fast neutrons than can be studied with thermal neutrons, epithermal neutrons, or x-rays. This paper details these differences through a comparative study of fast neutron radiography to the other types of radiography available. The most obvious difference among the different types of radiography is in the penetrability of the sources. Fast neutrons can probe much deeper and can therefore obtain details of the internals of thick objects. Good images have been obtained through as much as 15 cm of steel, 10 cm of water, and 15 cm of borated polyethylene. In addition, some objects were identifiable through as much as 25 cm of water or 30 cm of borated polyethylene. The most notable benefit of fast neutron radiography is in the types of materials that can be tested. Fast neutron radiography can view through materials that simply cannot be viewed by X rays, thermal neutrons, or epithermal neutrons due to the high cross-sections or linear attenuation coefficients involved. Cadmium was totally transparent to the fast neutron source. Fast neutron radiography is not without drawbacks. The most pronounced drawback has been in the quality of radiograph produced. The image resolution is only about 0.8 mm for a 1.25 cm thick object, whereas, other forms of radiography have much better resolution

  9. Resolving Fast, Confined Diffusion in Bacteria with Image Correlation Spectroscopy.

    Science.gov (United States)

    Rowland, David J; Tuson, Hannah H; Biteen, Julie S

    2016-05-24

    By following single fluorescent molecules in a microscope, single-particle tracking (SPT) can measure diffusion and binding on the nanometer and millisecond scales. Still, although SPT can at its limits characterize the fastest biomolecules as they interact with subcellular environments, this measurement may require advanced illumination techniques such as stroboscopic illumination. Here, we address the challenge of measuring fast subcellular motion by instead analyzing single-molecule data with spatiotemporal image correlation spectroscopy (STICS) with a focus on measurements of confined motion. Our SPT and STICS analysis of simulations of the fast diffusion of confined molecules shows that image blur affects both STICS and SPT, and we find biased diffusion rate measurements for STICS analysis in the limits of fast diffusion and tight confinement due to fitting STICS correlation functions to a Gaussian approximation. However, we determine that with STICS, it is possible to correctly interpret the motion that blurs single-molecule images without advanced illumination techniques or fast cameras. In particular, we present a method to overcome the bias due to image blur by properly estimating the width of the correlation function by directly calculating the correlation function variance instead of using the typical Gaussian fitting procedure. Our simulation results are validated by applying the STICS method to experimental measurements of fast, confined motion: we measure the diffusion of cytosolic mMaple3 in living Escherichia coli cells at 25 frames/s under continuous illumination to illustrate the utility of STICS in an experimental parameter regime for which in-frame motion prevents SPT and tight confinement of fast diffusion precludes stroboscopic illumination. Overall, our application of STICS to freely diffusing cytosolic protein in small cells extends the utility of single-molecule experiments to the regime of fast confined diffusion without requiring advanced

  10. Benchmark test of evaluated nuclear data files for fast reactor neutronics application

    International Nuclear Information System (INIS)

    Chiba, Go; Hazama, Taira; Iwai, Takehiko; Numata, Kazuyuki

    2007-07-01

    A benchmark test of the latest evaluated nuclear data files, JENDL-3.3, JEFF-3.1 and ENDF/B-VII.0, has been carried out for fast reactor neutronics application. For this benchmark test, experimental data obtained at fast critical assemblies and fast power reactors are utilized. In addition to comparing of numerical solutions with the experimental data, we have extracted several cross sections, in which differences between three nuclear data files affect significantly numerical solutions, by virtue of sensitivity analyses. This benchmark test concludes that ENDF/B-VII.0 predicts well the neutronics characteristics of fast neutron systems rather than the other nuclear data files. (author)

  11. Gamma-ray bursts from fast, galactic neutron stars

    International Nuclear Information System (INIS)

    Colgate, S.A.; Leonard, P.J.

    1996-01-01

    What makes a Galactic model of gamma-ray bursts (GBs) feasible is the observation of a new population of objects, fast neutron stars, that are isotropic with respect to the galaxy following a finite period, ∼30 My, after their formation (1). Our Galactic model for the isotropic component of GBs is based upon high-velocity neutron stars (NSs) that have accretion disks. These fast NSs are formed in tidally locked binaries, producing a unique population of high velocity (approx-gt 10 3 kms -1 ) and slowly rotating (8 s) NSs. Tidal locking occurs due to the meridional circulation caused by the conservation of angular momentum of the tidal lobes. Following the collapse to a NS and the explosion, these lobes initially perturb the NS in the direction of the companion. Subsequent accretion (1 to 2 s) occurs on the rear side of the initial motion, resulting in a runaway acceleration of the NS by neutrino emission from the hot accreted matter. The recoil momentum of the relativistic neutrino emission from the localized, down flowing matter far exceeds the momentum drag of the accreted matter. The recoil of the NS is oriented towards the companion, but the NS misses because of the pre-explosion orbital motion. The near miss captures matter from the companion and forms a disk around the NS. Accretion onto the NS from this initially gaseous disk due to the ''alpha'' viscosity results in a soft gamma-ray repeater phase, which lasts ∼10 4 yr. Later, after the neutron star has moved ∼30 kpc from its birthplace, solid bodies form in the disk, and accrete to planetoid size bodies after ∼3x10 7 years. Some of these planetoid bodies, with a mass of ∼10 21 endash 10 22 g, are perturbed into an orbit inside the tidal distortion radius of approx-gt 10 5 km. Of these ∼1% are captured by the magnetic field of the NS at R 3 km to create GBs

  12. High-sensitive spectrometer of fast neutrons and the results of fast neutron background flux measurements at the gallium-germanium solar neutrino experiment (SAGE)

    International Nuclear Information System (INIS)

    Abdurashitov, D.N.; Gavrin, V.N.; Kalikhov, A.V.; Matushko, V.L.; Shikhin, A.A.; Yants, V.E.; Zaborskaya, O.S.

    2001-01-01

    The principle of operation, design, registration system and main characteristics of a fast neutron spectrometer are described. The spectrometer is intended for direct measurements of ultra-low fluxes of fast neutrons. It is sensitive to neutron fluxes of 10 -7 cm -2 · s -1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 ± 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 ± 2.1) · 10 -7 cm -2 · s -1 in the range of 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4600 meters of water equivalent was measured to be (7.3 ± 2.4) · 10 -7 cm -2 · s -1 in the interval 1.0 -11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be 2.3 · 10 -7 cm -2 · s -1 in 1.0 - 11.0 MeV energy range

  13. High-sensitive spectrometer of fast neutrons and the results of fast neutron background flux measurements at the Gallium-Germanium Solar Neutrino Experiment

    CERN Document Server

    Abdurashitov, J N; Kalikhov, A V; Matushko, V L; Shikhin, A A; Yants, V E; Zaborskaia, O S

    2002-01-01

    The principle of operation, design, registration system and main characteristics of a fast neutron spectrometer are described. The spectrometer is intended for direct measurements of ultra low fluxes of fast neutrons. It is sensitive to neutron fluxes of 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11+-0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5+-2.1)x10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4600 m of water equivalent was measured to be (7.3+-2.4)x10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be <2.3x10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in 1.0-11.0 MeV energy range.

  14. Validation of computational methods for treatment planning of fast-neutron therapy using activation foil techniques

    International Nuclear Information System (INIS)

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

    1997-12-01

    A closed-form direct method for unfolding neutron spectra from foil activation data is presented. The method is applied to measurements of the free-field neutron spectrum produced by the proton-cyclotron-based fast-neutron radiotherapy facility at the University of Washington (UW) School of Medicine. The results compare favorably with theoretical expectations based on an a-priori calculational model of the target and neutron beamline configuration of the UW facility

  15. Fast-neutron capture in fissile and fertile nuclides

    International Nuclear Information System (INIS)

    Peelle, R.W.

    1982-01-01

    Extensive graphical and numerical presentations, available to the working group, assisted us in exploring the rich data base established through the labors of many skilled persons. Consistent with the meeting setting, the working group discussion concentrated on data for fast-breeder reactor (FBR) applications. All but 1 to 3% of the magnitude of cross section sensitivities of FBR parameters come from the energy region below approx. = 1.5 MeV, so the statistical model is the relevant theoretical concept. The Meeting emphasizes energies above approx. = 10 keV where resonance fluctuations are not a dominant factor. However, we should remember that approximately half the FBR sensitivity to 238 U capture data, as relfected in integral parameters, lies below 25 keV where resonance fluctuations are strong and resonance self-protection is a most important consideration in reactor physics. There are similar low-energy aspects to 239 Pu capture in that approx. = 30% of the FBR-parameter data sensitivity lies below approx. = 4 keV. Even with the discussion largely cofined to the approx. = 10 to 1500 keV region, the working group could only scratch the surface of the available body of information. The reader is referred to the papers presented at the Meeting and to the references contained therein in order to obtain a more detailed understanding of current issues related to fissile and fertile fast-neutron capture

  16. Spectroscopy of neutron-rich isotopes of nickel and iron

    International Nuclear Information System (INIS)

    Girod, M.; Dessagne, P.; Bernas, M.; Langevin, M.; Pougheon, F.; Roussel, P.

    1987-01-01

    Spectroscopy of neutron rich isotopes of 67 Ni, 68 Ni and 62 Fe is studied using the quasi-elastic transfer reactions ( 14 C, 16 O) and ( 14 C, 17 O) on mass separated targets of 70 Zn and of 64 Ni. The structure of these new nuclei is investigated through the Hartree-Fock-Bogoliubov (HFB) calculations, using the D1SA interaction. Inertial parameters are calculated in the cranking approximation. Collective excited states are obtained consistently by solving the Bohr Hamiltonian. Based on these results, quantum numbers are tentatively assigned to the observed states and angular distributions, measured and calculated from the DWBA, are used to check this assignment. The spectroscopy of more neutron rich nuclei, yet unknown, is anticipated. A sharper test of wave functions is provided by the monopole operator of the O 2 + → O 1 + transition in 68 Ni, which have been deduced from the halflife measurement performed in delayed coincidence experiments. An impressive agreement is obtained between the measured halflife and its value calculated using complete HFB wave functions

  17. The CLYC-6 and CLYC-7 response to γ-rays, fast and thermal neutrons

    International Nuclear Information System (INIS)

    Giaz, A.; Pellegri, L.; Camera, F.; Blasi, N.; Brambilla, S.; Ceruti, S.; Million, B.; Riboldi, S.; Cazzaniga, C.; Gorini, G.; Nocente, M.; Pietropaolo, A.; Pillon, M.; Rebai, M.; Tardocchi, M.

    2016-01-01

    The crystal Cs 2 LiYCl 6 :Ce (CLYC) is a very interesting scintillator material because of its good energy resolution and its capability to identify γ-rays and fast/thermal neutrons. The crystal Cs 2 LiYCl 6 :Ce contains 6 Li and 35 Cl isotopes, therefore, it is possible to detect thermal neutrons through the reaction 6 Li(n, α)t while 35 Cl ions allow to measure fast neutrons through the reactions 35 Cl(n, p) 35 S and 35 Cl(n, α) 32 P. In this work two CLYC 1″×1″ crystals were used: the first crystal, enriched with 6 Li at 95% (CLYC-6) is ideal for thermal neutron measurements while the second one, enriched with 7 Li at >99% (CLYC-7) is suitable for fast neutron measurements. The response of CLYC scintillators was measured with different PMT models: timing or spectroscopic, with borosilicate glass or quartz window. The energy resolution, the neutron-γ discrimination and the internal activity are discussed. The capability of CLYC scintillators to discriminate γ rays from neutrons was tested with both thermal and fast neutrons. The thermal neutrons were measured with both detectors, using an AmBe source. The measurements of fast neutrons were performed at the Frascati Neutron Generator facility (Italy) where a deuterium beam was accelerated on a deuterium or on a tritium target, providing neutrons of 2.5 MeV or 14.1 MeV, respectively. The different sensitivity to thermal and fast neutrons of a CLYC-6 and of a CLYC-7 was additionally studied.

  18. New Ways to Determine Plant Nutrient Deficiences Using Fast Spectroscopy

    DEFF Research Database (Denmark)

    van Maarschalkerweerd, Marie

    In a global perspective, the agricultural sector is right now facing its biggest challenge ever. The world population is rapidly increasing, and food production has to grow at the same, or higher, speed to be able to feed everyone. At the same time, the effect on environmental and natural resources...... must be limited. Over-fertilization must be stopped to secure aquatic environments and to reduce greenhouse gas emissions, caused by production and use of inorganic fertilizers. For production of P fertilizer, furthermore a non-renewable natural resource is used, which is expected to be exhausted...... for soil and plant analysis are described and the usability of each technique is discussed. Focus is put particularly on the newest methods for plant analysis based on fast spectroscopy, such as visual and near-infrared (Vis-NIR) reflectance and chlorophyll a fluorescence. These methods enable easy, fast...

  19. Polarization Studies in Fast-Ion Beam Spectroscopy

    International Nuclear Information System (INIS)

    Trabert, E

    2001-01-01

    In a historical review, the observations and the insight gained from polarization studies of fast ions interacting with solid targets are presented. These began with J. Macek's recognition of zero-field quantum beats in beam-foil spectroscopy as indicating alignment, and D.G. Ellis' density operator analysis that suggested the observability of orientation when using tilted foils. Lastly H. Winter's studies of the ion-beam surface interaction at grazing incidence yielded the means to produce a high degree of nuclear orientation in ion beams

  20. Fast gas spectroscopy using pulsed quantum cascade lasers

    Science.gov (United States)

    Beyer, T.; Braun, M.; Lambrecht, A.

    2003-03-01

    Laser spectroscopy has found many industrial applications, e.g., control of automotive exhaust and process monitoring. The midinfrared region is of special interest because it has stronger absorption lines compared to the near infrared (NIR). However, in the NIR high quality reliable laser sources, detectors, and passive optical components are available. A quantum cascade laser could change this situation if fundamental advantages can be exploited with compact and reliable systems. It will be shown that, using pulsed lasers and available fast detectors, lower residual sensitivity levels than in corresponding NIR systems can be achieved. The stability is sufficient for industrial applications.

  1. Fast-neutron detecting system with n, γ discrimination

    International Nuclear Information System (INIS)

    Ouyang Xiaoping; Huang Bao; Cao Jinyun

    1997-11-01

    In the present work, a new type neutron detecting system is reported, which can absolutely measure neutron parameters in n + γ mixed fields and has a long continuance of static high vacuum of 10 -4 Pa. The detecting system, with middle neutron-detecting sensitivity, short time response and big linear current output, has applied successfully in pulsed neutron beam measurement

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

    International Nuclear Information System (INIS)

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

    1980-05-01

    Experimental methods related to the production of neutrons for cross section studies at the Argonne Fast-Neutron Generator are reviewed. Target assemblies commonly employed in these measurements are described, and some of the relevant physical properties of the neutron source reactions are discussed. Various measurements have been performed to ascertain knowledge about these source reaction that is required for cross section data analysis purposes. Some results from these studies are presented, and a few specific examples of neutron-source-related corrections to cross section data are provided. 16 figures, 3 tables

  3. Feasibility study of Self Powered Neutron Detectors in Fast Reactors for detecting local change in neutron flux distribution

    International Nuclear Information System (INIS)

    Jammes, Christian; Filliatre, Philippe; Verma, Vasudha; Hellesen, Carl; Jacobsson Svard, Staffan

    2015-01-01

    Neutron flux monitoring system forms an integral part of the design of a Generation IV sodium cooled fast reactor system. Diverse possibilities of detector systems installation have to be investigated with respect to practicality and feasibility according to the detection parameters. In this paper, we demonstrate the feasibility of using self powered neutron detectors as in-core detectors in fast reactors for detecting local change in neutron flux distribution. We show that the gamma contribution from fission products decay in the fuel and activation of structural materials is very small compared to the fission gammas. Thus, it is possible for the in-core SPND signal to follow changes in local neutron flux as they are proportional to each other. This implies that the signal from an in-core SPND can provide dynamic information on the neutron flux perturbations occurring inside the reactor core. (authors)

  4. Feasibility study of Self Powered Neutron Detectors in Fast Reactors for detecting local change in neutron flux distribution

    Energy Technology Data Exchange (ETDEWEB)

    Jammes, Christian; Filliatre, Philippe [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St Paul-Lez-Durance, (France); Verma, Vasudha; Hellesen, Carl; Jacobsson Svard, Staffan [Division of Applied Nuclear Physics, Uppsala University, SE-75120 Uppsala, (Sweden)

    2015-07-01

    Neutron flux monitoring system forms an integral part of the design of a Generation IV sodium cooled fast reactor system. Diverse possibilities of detector systems installation have to be investigated with respect to practicality and feasibility according to the detection parameters. In this paper, we demonstrate the feasibility of using self powered neutron detectors as in-core detectors in fast reactors for detecting local change in neutron flux distribution. We show that the gamma contribution from fission products decay in the fuel and activation of structural materials is very small compared to the fission gammas. Thus, it is possible for the in-core SPND signal to follow changes in local neutron flux as they are proportional to each other. This implies that the signal from an in-core SPND can provide dynamic information on the neutron flux perturbations occurring inside the reactor core. (authors)

  5. Fast ultrasonic visualisation under sodium. Application to the fast neutron reactors; Visualisation ultrasonore rapide sous sodium. application aux reacteurs a neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Imbert, Ch

    1997-05-30

    The fast ultrasonic visualization under sodium is in the programme of research and development on the inspection inside the fast neutron reactors. This work is about the development of a such system of fast ultrasonic imaging under sodium, in order to improve the existing visualization systems. This system is based on the principle of orthogonal imaging, it uses two linear antennas with an important dephasing having 128 piezo-composite elements of central frequency equal to 1.6 MHz. (N.C.)

  6. Development of a hand-held fast neutron survey meter

    International Nuclear Information System (INIS)

    Yoshida, T.; Tsujimura, N.; Yamano, T.

    2011-01-01

    A neutron survey meter with a ZnS(Ag) scintillator to measure recoil protons was built. The detection probe weighs ∼2 kg, therefore providing us with true portability. Performance tests exhibited satisfactory neutron dosimetry characteristics in unmoderated or lightly moderated fission neutron fields and in particular work environments at a mixed oxide fuel facility. This new survey meter will augment a routine of neutron monitoring that is inconveniently being carried out by moderator-based neutron survey meters. (authors)

  7. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Niobium

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method describes procedures for measuring reaction rates by the activation reaction 93Nb(n,n′)93mNb. 1.2 This activation reaction is useful for monitoring neutrons with energies above approximately 0.5 MeV and for irradiation times up to about 30 years. 1.3 With suitable techniques, fast-neutron reaction rates for neutrons with energy distribution similar to fission neutrons can be determined in fast-neutron fluences above about 1016cm−2. In the presence of high thermal-neutron fluence rates (>1012cm−2·s−1), the transmutation of 93mNb due to neutron capture should be investigated. In the presence of high-energy neutron spectra such as are associated with fusion and spallation sources, the transmutation of 93mNb by reactions such as (n,2n) may occur and should be investigated. 1.4 Procedures for other fast-neutron monitors are referenced in Practice E 261. 1.5 Fast-neutron fluence rates can be determined from the reaction rates provided that the appropriate cross section information ...

  8. Sensitivity Analysis and Requirements for Temporally and Spatially Resolved Thermometry Using Neutron Resonance Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Juan Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Barnes, Cris William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mocko, Michael Jeffrey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavorka, Lukas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-01-31

    This report is intended to examine the use of neutron resonance spectroscopy (NRS) to make time- dependent and spatially-resolved temperature measurements of materials in extreme conditions. Specifically, the sensitivities of the temperature estimate on neutron-beam and diagnostic parameters is examined. Based on that examination, requirements are set on a pulsed neutron-source and diagnostics to make a meaningful measurement.

  9. Recent progress in fast neutron activation cross section data

    International Nuclear Information System (INIS)

    Michaelis, W.

    A brief review is given of some significant investigations performed during the past few years in the area of fast neutron activation cross sections that may be relevant for the use of nuclear techniques in the exploration of mineral resources, in process and quality control in industry as well as for general analytical purposes. Differential capture cross sections are considered for the natural elements or isotopes of Fe, Cu, Se, Y, Nb, Cd, In, Gd, W, Os and Au. Some of the data are compared with statistical model calculations. Experimental and evaluated average cross sections for capture and threshold reactions in the spontaneous fission neutron field of 252 Cf are reviewed taking into account the elements or isotopes of Mg, Al, Si, S, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Nb, Cd, In, Ba, Ta and Au. A summary of recent studies of differential cross sections for threshold reactions comprises data on Al, Si, S, Ti, Fe, Co, Ni, Cu, Zn, Zr, Nb, Ta, W and Au. Besides experimental investigations, evaluations and theoretical model calculations are considered. Cross sections at 14 MeV and in the region around this energy are reviewed for Na, Mg, Al, Cl, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Zr, Nb, In, Er, Yb, Ta, W, Os, Ir, Au and Pb. Particular emphasis is laid on (n,p), (n,2n) and (n,α) reactions. (n,n') reactions are allowed for if the half-life of the metastable state excited permits elemental analyses by common experimental techniques. (orig.)

  10. A hybrid source-driven method to compute fast neutron fluence in reactor pressure vessel - 017

    International Nuclear Information System (INIS)

    Ren-Tai, Chiang

    2010-01-01

    A hybrid source-driven method is developed to compute fast neutron fluence with neutron energy greater than 1 MeV in nuclear reactor pressure vessel (RPV). The method determines neutron flux by solving a steady-state neutron transport equation with hybrid neutron sources composed of peripheral fixed fission neutron sources and interior chain-reacted fission neutron sources. The relative rod-by-rod power distribution of the peripheral assemblies in a nuclear reactor obtained from reactor core depletion calculations and subsequent rod-by-rod power reconstruction is employed as the relative rod-by-rod fixed fission neutron source distribution. All fissionable nuclides other than U-238 (such as U-234, U-235, U-236, Pu-239 etc) are replaced with U-238 to avoid counting the fission contribution twice and to preserve fast neutron attenuation for heavy nuclides in the peripheral assemblies. An example is provided to show the feasibility of the method. Since the interior fuels only have a marginal impact on RPV fluence results due to rapid attenuation of interior fast fission neutrons, a generic set or one of several generic sets of interior fuels can be used as the driver and only the neutron sources in the peripheral assemblies will be changed in subsequent hybrid source-driven fluence calculations. Consequently, this hybrid source-driven method can simplify and reduce cost for fast neutron fluence computations. This newly developed hybrid source-driven method should be a useful and simplified tool for computing fast neutron fluence at selected locations of interest in RPV of contemporary nuclear power reactors. (authors)

  11. Lethal and mutagenic effects of fast neutrons of different energy on Streptomyces griseus spores

    International Nuclear Information System (INIS)

    Podgorskaya, M.E.; Tulina, G.G.; Serdechnaya, A.I.; Matselyukh, B.P.

    1986-01-01

    A study was made of lethal and mutagenic effects of fast neutrons of different energy on spores of prototrophic and auxotrophic strains of Streptomyces griseus. Relative biological effectiveness of fast neutrons is higher than that of γ-rays and depends on beam energy. Neutrons of 22-50 MeV induce Streptomyces griseus mutations more frequently (by one order of magnitude) than neutrons of 1.4-1.6 MeV do. The obtained mutants can be used in studying Streptomyces griseus genetics

  12. High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification

    Energy Technology Data Exchange (ETDEWEB)

    David L. Chichester; James T. Johnson; Edward H. Seabury

    2012-07-01

    Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials. The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations

  13. Possibility of construction in Bulgaria of a fast neutron therapy center on the base of the U-250 isochronous cyclotron

    International Nuclear Information System (INIS)

    Angelov, V.A.; Enchevich, I.B.

    1985-01-01

    Development of oncological disease treatment by fast neutrons in the world practice is reviewed. Main radiobiological results, which point to peculiarities of neutron therapy in comparison with standard X-ray therapy are considered. Main requirements for devices to be met, used in fast neutron therapy, are enumerated. On the basis of it, the possibility of construction in Bulgaria a fast neutron therapy center using the U-250 multipurpose cyclotron has been made. The conclusion is made that the main parameters of a proton beam in combination with an isocentrical head as a fast neutron source will create the conditions for realization of high-efficiency neutron therapy

  14. Radiobiological response of fast neutrons on seedling growth of rice varieties with different amylose content

    International Nuclear Information System (INIS)

    Baradjanegara, A.A.; Sugiyanto, T.; Rahayu, S.

    1978-01-01

    Many studies are reported on radiation effects and on factors modifying the biological response of radiation in rice. However, little attention was directed towards studying effects of fast neutrons on seedling growth response of rice as a function of chemical constituents (e.g. amylose content). Experiments were conducted to investigate the dependency of amylose content in 4 rice cultivars on radiosensitivity to fast neutrons. From the results obtained a clear relationship between amylose content and sensitivity to fast neutrons could be shown. (author)

  15. Passive and Active Fast-Neutron Imaging in Support of Advanced Fuel Cycle Initiative Safeguards Campaign

    International Nuclear Information System (INIS)

    Blackston, Matthew A.; Hausladen, Paul

    2010-01-01

    Results from safeguards-related passive and active coded-aperture fast-neutron imaging measurements of plutonium and highly enriched uranium (HEU) material configurations performed at Idaho National Laboratory s Zero Power Physics Reactor facility are presented. The imaging measurements indicate that it is feasible to use fast neutron imaging in a variety of safeguards-related tasks, such as monitoring storage, evaluating holdup deposits in situ, or identifying individual leached hulls still containing fuel. The present work also presents the first demonstration of imaging of differential die away fast neutrons.

  16. Measurement of the fast neutron flux in the MNSR inner irradiation site

    International Nuclear Information System (INIS)

    Khattab, K.

    2007-01-01

    The WIMSD4 code was used to calculate the fast neutron flux spectrum and the fast neutron fission cross sections for 238 U, using six energy groups ranging from 0.5 to 10 MeV. These results, with the measured radioactivities of the 140 Ba, 131 I, 103 Ru, 95 Zr and 97 Zr fission products emerging from the fission of the 238 U foil covered with a cadmium filter, were used to measure the fast neutron flux in the Syrian MNSR inner irradiation site. (author)

  17. A conceptual design of neutron tumor therapy reactor facility with a YAYOI based fast neutron source reactor

    International Nuclear Information System (INIS)

    Wakabayashi, Hiroaki; An, Shigehiro.

    1983-01-01

    Fast neutron is known as one of useful radiations for radiation therapy of tumors. Boron neutron capture therapy (BNCT) of tumors which makes use of 10 B(n, α) 7 Li reaction of 10 B compounds selectively attached to tumor cells with thermal and intermediate neutrons is another way of neutron based radiation therapy which is, above all, attractive enough to kill tumor cells selectively sparing normal tissue. In Japan, BNCT has already been applied and leaned to be effective. After more than a decade operational experiences and the specific experiments designed for therapeutical purposes, in this paper, a conceptual design of a special neutron therapy reactor facility based on YAYOI - fast neutron source reactor of Nuclear Engineering Research Laboratory, Faculty of Engineering, the University of Tokyo - modified to provide an upward beam of fast and intermediate neutrons is presented. Emphasis is placed on the in-house nature of facility and on the coordinating capability of biological and physical researches as well as maintenances of the facility. (author)

  18. Applications of resonance ionization spectroscopy in neutron dosimetry

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Hurst, G.S.

    1982-01-01

    Resonance Ionization Spectroscopy (RIS) is a new analytical technique which is orders of magnitude more sensitive than previous methods of atomic analysis. In this method, lasers are used to selectively excite specific electronic transitions in the element being analyzed. A second laser photon can then ionize the excited atoms. Commercial lasers have sufficient intensity to assure that every atom located in the central portion of the laser beam will be ionized, and therefore can be detected. In this paper the concept of a xenon-containing matrix (XCM) which would release xenon atoms when exposed to neutrons is explored. Accumulated xenon would be measured using RIS to determine total dose. The total dosimeter would consist of an XCM, a radiator, and an encapsulation around both to contain released xenon atoms

  19. Application of fast neutrons in the mutagenesis of peas

    International Nuclear Information System (INIS)

    Huczkowski, J.; Kubajak, A.

    1976-01-01

    Air dry seeds of two varieties of peas were irradiated with fast neutrons of average energy of 5,6 MeV obtained in the U-120 cyclotron at the Cracow Institute of Nuclear Physics. The doses varied from 60 to 1600 rads. It was found that even very low doses (less than 100 rads) cause a conspicuous delay of germination; a significant decrease of seedling height was only observed at doses higher than 200 rads. In the 170-620 rad range seedling height diminished lineraly with increase of dose. On the basis of the greenhouse experiment five doses were chosen for field experiments: 200, 300, 500, 800 and 1000 rads. It was found that a dose of about 500 rads was the maximum that could be applied for breeding purposes: the survival and fertility rate at that dose was about 40% of the control, doses of 800 to 900 rads caused full mortality. The M2 seeds were sown in the greenhouse and the frequency of chlorophyl mutations was examined in generation M2. It was found to be very high: for doses of 200 t0 300 rads the mutations ocurred in about 4% of M2 seedlings. (author)

  20. New wheat cultivars induced by fast neutrons in Iraq

    International Nuclear Information System (INIS)

    Ibrahim, I.F.; Al-Maaroof, E.M.; Al-Aubaidi, M.O.; Al-Janabi, K.K.; Al-Janabi, A.A.; Al-Rawi, L.; Ali, A.H.

    1994-01-01

    Wheat (Triticum aestivum L. ssp. aestivum) seeds from the cultivar Mexipak and F2 of the cross SaberBeg/Mexipak and saberBeg/Mexipak/Abu-Ghraib-4 were irradiated with fast neutrons and screened for resistance to leaf rust (Puccinia recondita Rob. ex Desm.) during three generations. Thirty-eight and 226 variants showing resistant and moderately resistant reactions, respectively, were selected. Of these variants three mutants showing genetic purity and stability were studied for yield components for four successive generations. Analyses of proteins and isozymes along with chemical and physical properties were conducted on these mutants and their parents. Data on disease incidence, lodging, shattering and yield components indicated that all the mutants significantly surpassed the cultivars Mexipak, SaberBeg and Abu-Ghraib-4. Both mutants Tamuz-1 and Tamuz-2 surpassed Mexipak in bread-making quality, while the mutant Tamuz-3 had a higher tendency for better bread-making quality than Mexipak or SeberBeg

  1. Laser Spectroscopy Studies in the Neutron-Rich Sn Region

    CERN Multimedia

    Obert, J

    2002-01-01

    We propose to use the powerful laser spectroscopy method to determine the magnetic moment $\\mu$ and the variation of the mean square charge radius ($\\delta\\,\\langle$r$_{c}^{2}\\,\\rangle$) for ground and long-lived isomeric states of the Sn isotopes from A=125 to the doubly-magic $^{132}$Sn isotope and beyond. For these neutron-rich Sn nuclei, numerous $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ curves have already been calculated and the predictions depend upon the effective interactions used. Therefore, a study of the effect of the shell closure N=82 on the $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ values in the Z=50 magic nuclei is of great interest, especially because $^{132}$Sn is located far from the stability valley. It will help to improve the parameters of the effective interactions and make them more suitable to predict the properties of exotic nuclei. \\\\ \\\\The neutron-rich Sn isotopes produced with an uranium carbide target, are ionized using either a hot plasma ion source or the resonant ionization laser ion ...

  2. Isomer spectroscopy of neutron-rich 168 Tb 103

    Energy Technology Data Exchange (ETDEWEB)

    Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yag, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C. -B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Yoshida, S.; Valiente-Dòbon, J. J.

    2017-11-01

    In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.

  3. JENDL-4.0 benchmarking for effective delayed neutron fraction of fast neutron systems

    International Nuclear Information System (INIS)

    Chiba, Go; Tsuji, Masashi; Sugiyama, Ken-ichiro; Narabayashi, Tadashi

    2011-01-01

    The performance of the latest Japanese evaluated nuclear data library JENDL-4.0 for the prediction of effective delayed neutron fraction β eff is assessed using experimental data of a wide range of fast neutron systems. Covariance data of JENDL-4.0 are used to quantify nuclear-data-induced uncertainties. Calculations with other libraries. JENDL-3.3, ENDF/B-VII.0, and JEFF-3.1, are also carried out for a quantitative comparison. JENDL-4.0 results in good agreement between calculation and experimental values within total uncertainties, and consistency between the differential nuclear data and integral experimental data is confirmed. While the other libraries also show good performance for β eff prediction, there are small differences in the predicted values of β eff among different libraries and ENDF/B-VII.0 gives the most stable results. Furthermore, a simple and convenient procedure to calculate sensitivity profiles of β eff to nuclear data is proposed. (author)

  4. Distinguishing Pu Metal from Pu Oxide and Determining alpha-ratio using Fast Neutron Counting

    Energy Technology Data Exchange (ETDEWEB)

    Verbeke, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chapline, G. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nakae, L. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Prasad, M. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sheets, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Snyderman, N. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-01-07

    We describe a new method for determining the ratio of the rate of (α, n) source neutrons to the rate of spontaneous fission neutrons, the so called α-ratio. This method is made possible by fast neutron counting with liquid scintillator detectors, which can determine the shape of the fast neutron spectrum. The method utilizes the spectral difference between fission spectrum neutrons from Pu metal and the spectrum of (α, n) neutrons from PuO2. Our method is a generalization of the Cifarelli-Hage method for determining keff for fissile assemblies, and also simultaneously determines keff along with the α-ratio.

  5. Laser spectroscopy of neutron deficient gold and platinum isotopes

    International Nuclear Information System (INIS)

    Savard, G.

    1988-03-01

    A new method for on-line laser spectroscopy of radioactive atoms based on the resonant ionization spectroscopy of laser-desorbed radioactive samples has been devised. An experimental setup has been installed on-line at the ISOCELE mass separator in Orsay (France) and experiments have been performed on the region of transitional nuclei around Z=79. Isotopic shift measurements on four new isotopes 194 Au, 196 Au, 198 Au, 199 Au have been performed on gold and results on the neutron deficient isotopes down to 186 Au have been obtained confirming the nuclear ground-state shape transition from oblate to prolate between 187 Au and 186 Au. The first isotopic shift measurements on radioactive platinum isotopes have been obtained on 186 Pt, 188 Pt, 189 Pt. Indications of a shape transition have been observed between 186 Pt and 188 Pt. The extracted experimental changes in mean square charge radii δ 2 > A,A' along isotopic chains are compared to self-consistent Hartree-Fock plus BCS calculations

  6. Long-term prognosis of maxillary sinus malignant tumor patients treated by fast neutron radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, Hirohisa; Numata, Tsutomu; Yuza, Jun; Suzuki, Haruhiko; Konno, Akiyoshi [Chiba Univ. (Japan). School of Medicine; Miyamoto, Tadaaki

    1995-03-01

    From 1976 through 1990, 19 patients with maxillary sinus malignant tumor were treated with combination therapy consisting of maxillectomy and radiation of fast neutron. Fast neutron radiotherapy was performed at National Institute of Radiological Sciences. Eight patients had adenoid cystic carcinomas, three patients squamous cell carcinomas, one patient a carcinoma in pleomorphic adenoma, four patients fibrosarcomas, one patient osteosarcoma, one patient chondrosarcoma and one patient rhabdomyosarcoma. Fast neutron therapy after/before surgery was effective in fresh cases with T2-3N0M0 adenoid cystic carcinomas and sarcomas (except for fibrosarcoma). Nine patients were alive more than three years after treatment. And serious complications of fast neutron radiation therapy appeared in six of these nine patients. Visual impairment of opposite side occurred in four patients. Bone necrosis occured in one patient and brain dysfunction in one patient. (author).

  7. Long-term prognosis of maxillary sinus malignant tumor patients treated by fast neutron radiation therapy

    International Nuclear Information System (INIS)

    Kishi, Hirohisa; Numata, Tsutomu; Yuza, Jun; Suzuki, Haruhiko; Konno, Akiyoshi; Miyamoto, Tadaaki.

    1995-01-01

    From 1976 through 1990, 19 patients with maxillary sinus malignant tumor were treated with combination therapy consisting of maxillectomy and radiation of fast neutron. Fast neutron radiotherapy was performed at National Institute of Radiological Sciences. Eight patients had adenoid cystic carcinomas, three patients squamous cell carcinomas, one patient a carcinoma in pleomorphic adenoma, four patients fibrosarcomas, one patient osteosarcoma, one patient chondrosarcoma and one patient rhabdomyosarcoma. Fast neutron therapy after/before surgery was effective in fresh cases with T2-3N0M0 adenoid cystic carcinomas and sarcomas (except for fibrosarcoma). Nine patients were alive more than three years after treatment. And serious complications of fast neutron radiation therapy appeared in six of these nine patients. Visual impairment of opposite side occurred in four patients. Bone necrosis occured in one patient and brain dysfunction in one patient. (author)

  8. Radiosensitivity and repair capacity of two xenografted human soft tissue sarcomas to photons and fast neutrons

    International Nuclear Information System (INIS)

    Budach, V.; Stuschke, M.; Budach, W.; Krause, U.; Streffer, C.; Sack, H.

    1989-01-01

    The radiation response, the relative biological effectiveness (RBE) and sublethal damage repair of two xenografted human soft tissue sarcomas after single doses and fractionated irradiation with 60 Co and 5.8 MeV fast neutrons are presented. (author)

  9. Demonstration of a Fast, Precise Propane Measurement Using Infrared Spectroscopy

    Science.gov (United States)

    Zahniser, M. S.; Roscioli, J. R.; Nelson, D. D.; Herndon, S. C.

    2016-12-01

    Propane is one of the primary components of emissions from natural gas extraction and processing activities. In addition to being an air pollutant, its ratio to other hydrocarbons such as methane and ethane can serve as a "fingerprint" of a particular facility or process, aiding in identifying emission sources. Quantifying propane has typically required laboratory analysis of flask samples, resulting in low temporal resolution and making plume-based measurements infeasible. Here we demonstrate fast (1-second), high precision (infrared spectroscopy at 2967 wavenumbers. In addition, we explore the impact of nearby water and ethane absorption lines on the accuracy and precision of the propane measurement. Finally, we discuss development of a dual-laser instrument capable of simultaneous measurements of methane, ethane, and propane (the C1-C3 compounds), all within a small spatial package that can be easily deployed aboard a mobile platform.

  10. A two-dimensional simulator of the neutronic behaviour of low power fast reactors

    International Nuclear Information System (INIS)

    Penha, M.A.V.R. da.

    1984-01-01

    A model to simulate the temporal neutronic behaviour of fast breeder reactors was developed. The effective cross-sections are corrected, whenever the reactor state change; by using linear correlations and interpolation schemes with data contained in a library previously compiled. This methodology was coupled with a simplified spatial neutronic calculation to investigate the temporal behaviour of neutronic parameters such as breeding gain, flux and power. (Author) [pt

  11. Design basis for creep of zirconium alloy components in a fast neutron flux

    International Nuclear Information System (INIS)

    Ross-Ross, P.A.; Fidleris, V.

    1975-01-01

    The chalk River Nuclear Laboratory's experience with the creep of zirconium alloys in a neutron flux is described. Fast neutron flux changes the creep behaviour of zirconium alloys and new design criteria for in-reactor applications are needed. From experimental results empirical relations describing the effects of neutron flux, stress, temperature, time and anisotropy on creep rate were established. The relations are applied to the design of pressure tubes. (author)

  12. Analysis of some Egyptian cosmetic samples by fast neutron activation analysis

    International Nuclear Information System (INIS)

    Medhat, M.E.; Ali, M.A.; Hassan, M.F.

    2001-01-01

    A description of D-T neutron generator (NG) is presented. This generator can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. The concentrations of the elements Na, Mg, Al, Si, K, Cl, Ca and Fe were determined in two domestic brands of face powder by using 14 MeV neutron activation analysis

  13. Inhomogeneous strain induced by fast neutron irradiation in NaKSO/sub 4/ crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kandil, S.H.; Kassem, M.E.; El-Khatib, A.; El-Gamal, M.A.; El-Wahidy, E.F.

    1987-11-01

    The paper reports the effect of fast neutron irradiation on the thermal properties of NaKSO/sub 4/ crystals in the temperature range 400-475 K. Results are presented for the thermal expansion, tensile strain and specific heat of NaKSO/sub 4/, as a function of neutron irradiation dose. All these results revealed an inhomogeneous strain induced by the radiation. It is suggested that this induced inhomogeneous strain could be used to detect neutron exposure doses.

  14. Inhomogeneous strain induced by fast neutron irradiation in NaKSO4 crystals

    International Nuclear Information System (INIS)

    Kandil, S.H.; Kassem, M.E.; El-Khatib, A.; El-Gamal, M.A.; El-Wahidy, E.F.

    1987-01-01

    The paper reports the effect of fast neutron irradiation on the thermal properties of NaKSO 4 crystals in the temperature range 400-475 K. Results are presented for the thermal expansion, tensile strain and specific heat of NaKSO 4 , as a function of neutron irradiation dose. All these results revealed an inhomogeneous strain induced by the radiation. It is suggested that this induced inhomogeneous strain could be used to detect neutron exposure doses. (UK)

  15. Analysis of Some Egyptian Cosmetic Samples by Fast Neutron Activation Analysis

    CERN Document Server

    Medhat, M E; Fayez-Hassan, M

    2001-01-01

    A description of D-T neutron generator (NG) is presented. This generator can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. In our work, the concentration of the elements Na, Mg, Al, Si, K, Cl, Ca and Fe, were determined in two domestic brands of face powder by using 14 MeV neutron activation analysis.

  16. Design basis for creep of zirconium alloy components in a fast neutron flux

    International Nuclear Information System (INIS)

    Ross-Ross, P.A.; Fidleris, V.

    1974-01-01

    The Chalk River Nuclear Laboratory's experience with the creep of zirconium alloys in a neutron flux is described. Fast neutron flux changes the creep behavior of zirconium alloys and new design criteria for in-reactor applications are needed. From experimental results empirical relations describing the effects of neutron flux, stress, temperature, time, and anisotropy on creep rate were established. The relations are applied to the design of pressure tubes. (author)

  17. Comparison of fast neutron-induced tracks in plastics using the electrochemical etching method

    International Nuclear Information System (INIS)

    Cotter, S.J.; Gammage, R.B.; Thorngate, J.H.; Ziemer, P.L.

    1979-01-01

    Four plastics were examined by the electrochemical etching method for their suitability in registering fast neutron-induced recoil particle tracks. The plastics were cellulose acetate, cellulose triacetate, cellulose acetobutyrate and polycarbonate. Cellulose acetate and triacetate displayed high levels of water absorptivity during etching while the acetobutyrate foils cracked due to electromechanical stresses at high frequencies (>500 Hz). The clarity of the etched track was superior in the polycarbonate foils, suggesting the latter as the generally preferred dosimeter for fast neutrons. (author)

  18. Sensitivities and interferences in activation analysis with cyclotron-produced fast neutrons

    International Nuclear Information System (INIS)

    Esprit, M.; Vandecasteele, C.; Hoste, J.

    1985-01-01

    Fast neutrons are produced by irradiation of a thick beryllium target with deuterons from a cyclotron. The spatial neutron flux distribution was studied. Ge(Li) gamma-ray spectrometry was used to measure the radionuclides produced. Detection limits are tabulated along with the nuclear interferences. (author)

  19. Characterization of the fast neutron irradiation facility of the Portuguese Research Reactor after core conversion

    International Nuclear Information System (INIS)

    Marques, J.G.; Sousa, M.; Santos, J.P.; Fernandes, A.C.

    2011-01-01

    The fast neutron irradiation facility of the Portuguese Research Reactor was characterized after the reduction in uranium enrichment and rearrangement of the core configuration. In this work we report on the determination of the hardness parameter and the 1 MeV equivalent neutron flux along the facility, in the new irradiation conditions, following ASTM E722 standard.

  20. Detection of fast burst of neutrons in the background of intense electromagnetic pulse

    International Nuclear Information System (INIS)

    Shyam, Anurag

    1999-01-01

    There are many experiments, in which fast neutron burst is emitted along with strong electromagnetic pulse. This pulse has frequency spectrum starting from few tens of khz to hard x-rays. Detecting these neutrons bursts require special measurement techniques, which are described. (author)

  1. Time Evolving Fission Chain Theory and Fast Neutron and Gamma-Ray Counting Distributions

    International Nuclear Information System (INIS)

    Kim, K. S.; Nakae, L. F.; Prasad, M. K.; Snyderman, N. J.; Verbeke, J. M.

    2015-01-01

    Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutrons in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.

  2. Measurement of fast neutron spectra inside reactors with a Li{sup 6} semiconductor counter spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Ajdacic, V S; Lalovic, B I; Petrovic, B P [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1963-12-15

    The possibility of using the Li{sup 6} semiconductor counter spectrometer for measuring fast neutron spectra inside reactors has been investigated in details and some solutions of the difficulties associated with the high interference of thermal neutrons in well-moderated reactors are suggested and checked experimentally (author)

  3. Designing research of fast neutron radiation field based on the reactor

    International Nuclear Information System (INIS)

    Zhang Wenzhong; Zhang Xiaomin

    2009-01-01

    Based on the Tsinghua University experimental nuclear reactor neutron source, this research designed moderate theory technical scheme, and the thickness of materials in the scheme were selected by means of Monte Carlo simulating method. An fast neutron radiation field was gained. (authors)

  4. Measurements of thermal and fast neutron fluxes at the TRIGA reactor

    International Nuclear Information System (INIS)

    Zerdin, F.; Grabovsek, Z.; Klinc, T.; Solinc, H.

    1966-01-01

    Gold foils were placed at different positions in the TRIGA reactor core and in the experimental devices. Absolute values of the thermal neutron flux at these positions were obtained by coincidence method. Preliminary fast neutron spectrum was measured by threshold detector and by 'Li 6 sandwich' detector. A short description of the applied method and obtained measurements results are included [sl

  5. The fluence research of filter material for fast neutron fluence measurement

    International Nuclear Information System (INIS)

    Tang Xiding

    2010-01-01

    When the fast neutron fluence is measured by radioactivation techniques in the nuclear reactor the fast neutron is also filtered a little by the thermal neutron filter material, and if the filter material thickness increase the filtered fast neutron increases therewith. For fast neutron fluenc measurement, there are only cadmium, boron and gadolinium three elements filtering fluence can be calculated ordinarily. In order to calculate the filtered fast neutron fluence of the all elements in the filter material, the many total cross sections of nuclides had checked out from nuclear cross section data library, converted them into the same energy group structure, then element's total cross section, compound's total cross section and multilayer filters' total cross section had calculated from these total cross sections with same energy group structure, a new cross section data library can be obtained lastly through merging these cross sections into the old cross section data library used for neutron fluence measurement. The calculation analysis indicates that the results of the unit 2 surveillance capsule U of DAYA Bay NPP and the unit 1 surveillance capsule A of the Second Nuclear Power Plant of Qinshan by considering the all elements subtracting iron are smaller about 1.5% and 2.6% respectively than the ones only to consider cadmium, boron. The old measured results accord with the new values under the measurement uncertainty, are reliable. The new results are more accuracy. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Shigeo, E-mail: neutron@keyaki.cc.u-tokai.ac.jp [Department of Energy Science and Engineering, School of Engineering, Tokai University, Hiratsuka, Kanagawa 259-1292 (Japan); Murata, Isao [Division of Electrical, Electronic and Information Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Nakagawa, Tsutomu; Saito, Isao [Nuclear Professional School, School of Engineering, The University of Tokyo, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

    2011-10-01

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

  7. Advances in neutronics calculation of fast neutron reactors - Demonstration on Super-Phenix reactor

    International Nuclear Information System (INIS)

    Czernecki, Sebastien

    1998-01-01

    The fast reactor european neutronics calculations system, ERANOS, has integrated recent improvements both in nuclear data, with the use of the adjusted nuclear library ERALIB 1 from the JEF2.2 library, and calculation methods, with the use of the new european cell code, ECCO, and the deterministic code, TGV/VARIANT. This code performs full 3-D reactor calculation in the transport theory with variational method. The aim of this work is to create and validate a new calculational scheme for fast spectrum systems offering good compromise between accuracy and running time. The new scheme is based on these improvements plus a special procedure accounting for control rod heterogeneity, which uses a reactivity equivalence homogenization. The new scheme has been validated by means of experiment/calculation comparisons, using the extensive start-up program measurements performed in Super-Phenix reactor. The validation uses also recent measurements performed in the Phenix reactor. The results are very satisfactory and show a significant improvement for almost all core parameters, especially for critical mass, control rod worth and radial subassembly power distribution. A detailed analysis of the discrepancies between the old scheme and the new one for this parameter allows to understand the separate effects of methods and nuclear data on the radial power distribution shape. (author) [fr

  8. FEASIBILITY OF MEASURING IRON IN VIVO USING FAST 14 MEV NEUTRONS.

    Energy Technology Data Exchange (ETDEWEB)

    WIELOPOLSKI, L.

    2005-05-01

    In this short report, I reassess the feasibility of measuring iron in vivo in the liver and heart of thalassemia patients undergoing chelation therapy. Despite the multiplicity of analytical methods for analyzing iron, only two, magnetic resonance imaging, and magnetic susceptibility, are suitable for in vivo applications, and these are limited to the liver because of the heart's beat. Previously, a nuclear method, gamma-resonance scattering, offered a quantitative measure of iron in these organs; however, it was abandoned because it necessitated a nuclear reactor to produce the radioactive source. I reviewed and reassessed the status of two alternative nuclear methods, based on iron spectroscopy of gamma rays induced by fast neutron inelastic scattering and delayed activation in iron. Both are quantitative methods with high specificity for iron and adequate penetrating power to measure it in organs sited deep within the human body. My experiments demonstrated that both modalities met the stated qualitative objectives to measure iron. However, neutron dosimetry revealed that the intensity of the neutron radiation field was too weak to reliably assess the minimum detection limits, and to allow quantitative extrapolations to measurements in people. A review of the literature, included in this report, showed that these findings agree qualitatively with the published results, although the doses reported were about three orders-of-magnitude higher than those I used. Reviewing the limitations of the present work, steps were outlined for overcoming some of the shortcomings. Due to a dearth of valid quantitative alternatives for determining iron in vivo, I conclude that nuclear methods remain the only viable option. However, from the lessons learned, further systematic work is required before embarking on clinical studies.

  9. Generalized synthetic kernel approximation for elastic moderation of fast neutrons

    International Nuclear Information System (INIS)

    Yamamoto, Koji; Sekiya, Tamotsu; Yamamura, Yasunori.

    1975-01-01

    A method of synthetic kernel approximation is examined in some detail with a view to simplifying the treatment of the elastic moderation of fast neutrons. A sequence of unified kernel (fsub(N)) is introduced, which is then divided into two subsequences (Wsub(n)) and (Gsub(n)) according to whether N is odd (Wsub(n)=fsub(2n-1), n=1,2, ...) or even (Gsub(n)=fsub(2n), n=0,1, ...). The W 1 and G 1 kernels correspond to the usual Wigner and GG kernels, respectively, and the Wsub(n) and Gsub(n) kernels for n>=2 represent generalizations thereof. It is shown that the Wsub(n) kernel solution with a relatively small n (>=2) is superior on the whole to the Gsub(n) kernel solution for the same index n, while both converge to the exact values with increasing n. To evaluate the collision density numerically and rapidly, a simple recurrence formula is derived. In the asymptotic region (except near resonances), this recurrence formula allows calculation with a relatively coarse mesh width whenever hsub(a)<=0.05 at least. For calculations in the transient lethargy region, a mesh width of order epsilon/10 is small enough to evaluate the approximate collision density psisub(N) with an accuracy comparable to that obtained analytically. It is shown that, with the present method, an order of approximation of about n=7 should yield a practically correct solution diviating not more than 1% in collision density. (auth.)

  10. Experimental detection of iron overload in liver through neutron stimulated emission spectroscopy

    International Nuclear Information System (INIS)

    Kapadia, A J; Tourassi, G D; Sharma, A C; Crowell, A S; Kiser, M R; Howell, C R

    2008-01-01

    Iron overload disorders have been the focus of several quantification studies involving non-invasive imaging modalities. Neutron spectroscopic techniques have demonstrated great potential in detecting iron concentrations within biological tissue. We are developing a neutron spectroscopic technique called neutron stimulated emission computed tomography (NSECT), which has the potential to diagnose iron overload in the liver at clinically acceptable patient dose levels through a non-invasive scan. The technique uses inelastic scatter interactions between atomic nuclei in the sample and incoming fast neutrons to non-invasively determine the concentration of elements in the sample. This paper discusses a non-tomographic application of NSECT investigating the feasibility of detecting elevated iron concentrations in the liver. A model of iron overload in the human body was created using bovine liver tissue housed inside a human torso phantom and was scanned with a 5 MeV pulsed beam using single-position spectroscopy. Spectra were reconstructed and analyzed with algorithms designed specifically for NSECT. Results from spectroscopic quantification indicate that NSECT can currently detect liver iron concentrations of 6 mg g -1 or higher and has the potential to detect lower concentrations by optimizing the acquisition geometry to scan a larger volume of tissue. The experiment described in this paper has two important outcomes: (i) it demonstrates that NSECT has the potential to detect clinically relevant concentrations of iron in the human body through a non-invasive scan and (ii) it provides a comparative standard to guide the design of iron overload phantoms for future NSECT liver iron quantification studies

  11. Towards radiation hard converter material for SiC-based fast neutron detectors

    Science.gov (United States)

    Tripathi, S.; Upadhyay, C.; Nagaraj, C. P.; Venkatesan, A.; Devan, K.

    2018-05-01

    In the present work, Geant4 Monte-Carlo simulations have been carried out to study the neutron detection efficiency of the various neutron to other charge particle (recoil proton) converter materials. The converter material is placed over Silicon Carbide (SiC) in Fast Neutron detectors (FNDs) to achieve higher neutron detection efficiency as compared to bare SiC FNDs. Hydrogenous converter material such as High-Density Polyethylene (HDPE) is preferred over other converter materials due to the virtue of its high elastic scattering reaction cross-section for fast neutron detection at room temperature. Upon interaction with fast neutrons, hydrogenous converter material generates recoil protons which liberate e-hole pairs in the active region of SiC detector to provide a detector signal. The neutron detection efficiency offered by HDPE converter is compared with several other hydrogenous materials viz., 1) Lithium Hydride (LiH), 2) Perylene, 3) PTCDA . It is found that, HDPE, though providing highest efficiency among various studied materials, cannot withstand high temperature and harsh radiation environment. On the other hand, perylene and PTCDA can sustain harsh environments, but yields low efficiency. The analysis carried out reveals that LiH is a better material for neutron to other charge particle conversion with competent efficiency and desired radiation hardness. Further, the thickness of LiH has also been optimized for various mono-energetic neutron beams and Am-Be neutron source generating a neutron fluence of 109 neutrons/cm2. The optimized thickness of LiH converter for fast neutron detection is found to be ~ 500 μm. However, the estimated efficiency for fast neutron detection is only 0.1%, which is deemed to be inadequate for reliable detection of neutrons. A sensitivity study has also been done investigating the gamma background effect on the neutron detection efficiency for various energy threshold of Low-Level Discriminator (LLD). The detection

  12. Identification of the fast and thermal neutron characteristics of transuranic waste drums

    Energy Technology Data Exchange (ETDEWEB)

    Storm, B.H. Jr.; Bramblett, R.L. [Lockheed Martin Specialty Components, Largo, FL (United States); Hensley, C. [Oak Ridge National Lab., TN (United States)

    1997-11-01

    Fissile and spontaneously fissioning material in transuranic waste drums can be most sensitively assayed using an active and passive neutron assay system such as the Active Passive Neutron Examination and Assay. Both the active and the passive assays are distorted by the presence of the waste matrix and containerization. For accurate assaying, this distortion must be characterized and accounted for. An External Matrix Probe technique has been developed that accomplishes this task. Correlations between in-drum neutron flux measurements and monitors in the Active Passive Neutron Examination and Assay chamber with various matrix materials provide a non-invasive means of predicting the thermal neutron flux in waste drums. Similarly, measures of the transmission of fast neutrons emitted from sources in the drum. Results obtained using the Lockheed Martin Specialty Components Active Passive Neutron Examination and Assay system are discussed. 12 figs., 1 tab.

  13. Measurement and evaluation of fast neutron flux of CT and OR5 irradiation hole in HANARO

    International Nuclear Information System (INIS)

    Yang, Seong Woo; Choo, Kee Nam; Lee, Seung-Kyu; Kim, Yong Kyun

    2012-01-01

    The irradiation test has been conducted to evaluate the irradiation performance of many materials by a material capsule at HANARO. Since the fast neutron fluence above 1 MeV is important for the irradiation test of material, it must be measured and evaluated exactly at each irradiation hole. Therefore, a fast neutron flux was measured and evaluated by a 09M-02K capsule irradiated in an OR5 irradiation hole and a 10M-01K capsule irradiated in a CT irradiation hole. Fe, Ni, and Ti wires as the fluence monitor were used for the detection of fast neutron flux. Before the irradiation test, the neutron flux and spectrum was calculated for each irradiation hole using an MCNP code. After the irradiation test, the activity of the fluence monitor was measured by an HPGe detector and the reaction rate was calculated. For the OR5 irradiation hole, the radial difference of the fast neutron flux was observed from a calculated data due to the OR5 irradiation hole being located outside the core. Furthermore, a control absorber rod was withdrawn from the core as the increase of the irradiation time at the same irradiation cycle, so the distribution of neutron flux was changed from the beginning to the end of the cycle. These effects were considered to evaluate the fast neutron flux. Neutron spectrums of the CT and OR5 irradiation hole were adjusted by the measured data. The fluxes of a fast neutron above 1 MeV were compared with calculated and measured value. Although the maximum difference was shown at 18.48%, most of the results showed good agreement. (author)

  14. Fast Neutron Dosimetry Using CR-39 Nuclear Track Detector

    International Nuclear Information System (INIS)

    ZAKI, M.; ABDEL-NABY, A.; MORSY, A.

    2010-01-01

    Measurement of the neutron dose in and around the neutron sources is important for the purpose of personnel and environmental neutron dosimetry. In the present study, a method for the measurement of neutron dose using the UV-Vis spectra of CR-39 plastic track detector was investigated. A set of CR-39 plastic detectors was exposed to 252 Cf neutron source, which had the yield of 0.68x10 8 /s, and neutron dose equivalent rate 1m apart from the source is equal to 3.8 mrem/h. The samples were etched for 10 h in 6.25 N NaOH at 70 o C. The absorbance of the etched samples was measured using UV-visible spectrophotometer as a function of neutron dose. It was observed that there was a linear relationship between the optical absorption of these detectors and neutron dose. This means that the exposure dose of neutron can be determined by knowing the optical absorption of the sample. These results were compared with previous study. It was found that there was a matching and good agreement with their investigations.

  15. Fission signal detection using helium-4 gas fast neutron scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, J. M., E-mail: lewisj@ufl.edu; Kelley, R. P.; Jordan, K. A. [Nuclear Engineering Program, University of Florida, Gainesville, Florida 32611 (United States); Murer, D. [Arktis Radiation Detectors Ltd., 8045 Zurich (Switzerland)

    2014-07-07

    We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure {sup 4}He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the {sup 4}He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.

  16. Fast neutron dosimetry by means of different solid state nuclear track detectors

    International Nuclear Information System (INIS)

    Spurny, F.; Turek, K.

    1977-01-01

    The comparative study of three different types of fast neutron dosimeters based on solid state nuclear track detectors is presented; the dosimeters studied were: - microscopic soda glass in contact with 232 Th; - polycarbonate Makrofol E; and - cellulose nitrate Kodak LR 115. All detectors were evaluated by visual counting in a microscope. The authors have studied such properties as the background, angular as well as energetical dependences of detectors. The results obtained show that all studied detectors are suitable for fast neutron dosimetry; their application depends however on the concrete experimental conditions (neutron spectrum, fluence etc.). Both advantages and disadvantages of each of them are presented. (Auth.)

  17. Study on beam geometry and image reconstruction algorithm in fast neutron computerized tomography at NECTAR facility

    Science.gov (United States)

    Guo, J.; Bücherl, T.; Zou, Y.; Guo, Z.

    2011-09-01

    Investigations on the fast neutron beam geometry for the NECTAR facility are presented. The results of MCNP simulations and experimental measurements of the beam distributions at NECTAR are compared. Boltzmann functions are used to describe the beam profile in the detection plane assuming the area source to be set up of large number of single neutron point sources. An iterative algebraic reconstruction algorithm is developed, realized and verified by both simulated and measured projection data. The feasibility for improved reconstruction in fast neutron computerized tomography at the NECTAR facility is demonstrated.

  18. Study on beam geometry and image reconstruction algorithm in fast neutron computerized tomography at NECTAR facility

    International Nuclear Information System (INIS)

    Guo, J.; Buecherl, T.; Zou, Y.; Guo, Z.

    2011-01-01

    Investigations on the fast neutron beam geometry for the NECTAR facility are presented. The results of MCNP simulations and experimental measurements of the beam distributions at NECTAR are compared. Boltzmann functions are used to describe the beam profile in the detection plane assuming the area source to be set up of large number of single neutron point sources. An iterative algebraic reconstruction algorithm is developed, realized and verified by both simulated and measured projection data. The feasibility for improved reconstruction in fast neutron computerized tomography at the NECTAR facility is demonstrated.

  19. Study on beam geometry and image reconstruction algorithm in fast neutron computerized tomography at NECTAR facility

    Energy Technology Data Exchange (ETDEWEB)

    Guo, J. [State Key Laboratory of Nuclear Physics and Technology and School of Physics, Peking University, 5 Yiheyuan Lu, Beijing 100871 (China); Lehrstuhl fuer Radiochemie, Technische Universitaet Muenchen, Garching 80748 (Germany); Buecherl, T. [Lehrstuhl fuer Radiochemie, Technische Universitaet Muenchen, Garching 80748 (Germany); Zou, Y., E-mail: zouyubin@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology and School of Physics, Peking University, 5 Yiheyuan Lu, Beijing 100871 (China); Guo, Z. [State Key Laboratory of Nuclear Physics and Technology and School of Physics, Peking University, 5 Yiheyuan Lu, Beijing 100871 (China)

    2011-09-21

    Investigations on the fast neutron beam geometry for the NECTAR facility are presented. The results of MCNP simulations and experimental measurements of the beam distributions at NECTAR are compared. Boltzmann functions are used to describe the beam profile in the detection plane assuming the area source to be set up of large number of single neutron point sources. An iterative algebraic reconstruction algorithm is developed, realized and verified by both simulated and measured projection data. The feasibility for improved reconstruction in fast neutron computerized tomography at the NECTAR facility is demonstrated.

  20. Preliminary research on measuring grease in petroleum pipeline using fast neutron transmission method

    International Nuclear Information System (INIS)

    Liu Qingwei; Liu Shengkang; Zhang Zhiping; Ding Xiaoping

    2006-01-01

    The principle, experiment and conclusion on the grease stain measurement using fast neutron are reported. The experiment equipment consist of 241 Am-Be fast neutron source, ZnS detector and BH1224 multichannel spectrometer. Paraffin is used instead of real grease stain. Steel plates are used instead of pipeline. The results of the experiment indicate that there is a good linearship between the logarithm of the reciprocal of the neutron transmissivity and the paraffin thickness. The measuring accuracy of the paraffin thickness is 0.6 mm in this experiment. (authors)

  1. Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Abu Zayed Mohammad Saliqur, E-mail: zayed82000@yahoo.com [Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquanlu Shijingshan District, Beijing 100049 (China); Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long [Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquanlu Shijingshan District, Beijing 100049 (China); Xu, Qiu [Reactor Research Institute, Kyoto University 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Atobe, Kozo [Nuclear Safety Technology Center, 9-15, 1-chome, Utsubohonmachi, Nishi Ku, Osaka 550-0004 (Japan)

    2014-09-15

    Highlights: •Detection of Al monovacancy by positron lifetime spectroscopy in fast neutron-irradiated MgO·nAl{sub 2}O{sub 3}(n=2). •Concentration of defects is also estimated for Al monovacancy. •O atom peak was observed by using coincidence Doppler broadening spectroscopy. -- Abstract: The positron lifetimes of fast-neutron-irradiated MgO·nAl{sub 2}O{sub 3} single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10{sup −3} m{sub 0}c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies.

  2. Measurements of prompt gamma-rays from fast-neutron induced fission with the LICORNE directional neutron source

    CERN Document Server

    Wilson, J N; Halipre, P; Oberstedt, S; Oberstedt, A

    2014-01-01

    At the IPN Orsay we have developed a unique, directional, fast neutron source called LICORNE, intended initially to facilitate prompt fission gamma measurements. The ability of the IPN Orsay tandem accelerator to produce intense beams of $^7$Li is exploited to produce quasi-monoenergetic neutrons between 0.5 - 4 MeV using the p($^7$Li,$^7$Be)n inverse reaction. The available fluxes of up to 7 × 10$^7$ neutrons/second/steradian for the thickest hydrogen-rich targets are comparable to similar installations, but with two added advantages: (i) The kinematic focusing produces a natural neutron beam collimation which allows placement of gamma detectors adjacent to the irradiated sample unimpeded by source neutrons. (ii) The background of scattered neutrons in the experimental hall is drastically reduced. The dedicated neutron converter was commissioned in June 2013. Some preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fas...

  3. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    DESIG: E 263 09 ^TITLE: Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron ^SIGNUSE: Refer to Guide E 844 for guidance on the selection, irradiation, and quality control of neutron dosimeters. Refer to Practice E 261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors. Pure iron in the form of foil or wire is readily available and easily handled. Fig. 1 shows a plot of cross section as a function of neutron energy for the fast-neutron reaction 54Fe(n,p)54Mn (1). This figure is for illustrative purposes only to indicate the range of response of the 54Fe(n,p)54Mn reaction. Refer to Guide E 1018 for descriptions of recommended tabulated dosimetry cross sections. 54Mn has a half-life of 312.13 days (3) (2) and emits a gamma ray with an energy of 834.845 keV (5). (2) Interfering activities generated by neutron activation arising from thermal or fast neutron interactions are 2.57878 (46)-h 56Mn, 44.95-d (8) 59Fe, and 5.27...

  4. MCNPX simulations of fast neutron diagnostics for accelerator-driven systems

    International Nuclear Information System (INIS)

    Habib, Moinul

    2005-12-01

    In accelerator-driven systems, the neutron spectrum will extend all the way up to the incident beam energy, i.e., several hundred MeV or even up to GeV energies. The high neutron energy allows novel diagnostics with a set of measurement techniques that can be used in a sub-critical reactor environment. Such measurements are primarily connected to system safety and validation. This report shows that in-core fast-neutron diagnostics can be employed to monitor changes in the position of incidence of the primary proton beam onto the neutron production target. It has also been shown that fast neutrons can be used to detect temperature-dependent density changes in a liquid lead-bismuth target. Fast neutrons can escape the system via the beam pipe for the incident proton beam. Out-of-core monitoring of these so called back-streaming neutrons could potentially be used to monitor beam changes if the target has a suitable shape. Moreover, diagnostics of back-streaming neutrons might be used for validation of the system design

  5. MCNPX simulations of fast neutron diagnostics for accelerator-driven systems

    Energy Technology Data Exchange (ETDEWEB)

    Habob, Moinul

    2005-12-15

    In accelerator-driven systems, the neutron spectrum will extend all the way up to the incident beam energy, i.e., several hundred MeV or even up to GeV energies. The high neutron energy allows novel diagnostics with a set of measurement techniques that can be used in a sub-critical reactor environment. Such measurements are primarily connected to system safety and validation. This report shows that in-core fast-neutron diagnostics can be employed to monitor changes in the position of incidence of the primary proton beam onto the neutron production target. It has also been shown that fast neutrons can be used to detect temperature-dependent density changes in a liquid lead-bismuth target. Fast neutrons can escape the system via the beam pipe for the incident proton beam. Out-of-core monitoring of these so called back-streaming neutrons could potentially be used to monitor beam changes if the target has a suitable shape. Moreover, diagnostics of back-streaming neutrons might be used for validation of the system design.

  6. Investigations of fast neutron production by 190 GeV/c muon interactions on graphite target

    CERN Document Server

    Chazal, V; Cook, B; Henrikson, H; Jonkmans, G; Paic, A; Mascarenhas, N; Vogel, P; Vuilleumier, J L

    2002-01-01

    The production of fast neutrons (1 MeV - 1 GeV) in high energy muon-nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments. The aim of the present experiment (CERN NA55) was to measure spallation neutrons produced by 190 GeV/c muons scattering on carbon target. We have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross section.

  7. Investigations of fast neutron production by 190 GeV/c muon interactions on different targets

    International Nuclear Information System (INIS)

    Chazal, V.; Boehm, F.; Cook, B.; Henrikson, H.; Jonkmans, G.; Paic, A.; Mascarenhas, N.; Vogel, P.; Vuilleumier, J.-L.

    2002-01-01

    The production of fast neutrons (1 MeV-1 GeV) in high-energy muon-nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments. The aim of the present experiment (CERN NA55) was to measure spallation neutrons produced by 190 GeV/c muons scattering on carbon, copper and lead targets. We have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross-section

  8. Fast-neutron-induced fission of 242Pu at nELBE

    Directory of Open Access Journals (Sweden)

    Kögler Toni

    2017-01-01

    Full Text Available The fast neutron-induced fission cross section of 242Pu was determined in the range of 0.5 MeV to 10 MeV relative to 235U(n,f at the neutron time-of-flight facility nELBE. The number of target nuclei was calculated by means of measuring the spontaneous fission rate of 242Pu. Neutron transport simulations with Geant4 and MCNP6 are used to correct the relative cross section for neutron scattering. The determined results are in good agreement with current experimental and evaluated data sets.

  9. Inelastic scattering of fast neutrons on Fe-56; Inelastische Streuung schneller Neutronen an {sup 56}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Roland

    2014-11-24

    The relevant reaction cross sections for the nuclear transmutation will be measured at the neutron flight time facility nELBE in Dresden-Rossendorf. Transmutation by fast neutron irradiation is supposed to reduce the radiotoxicity of high-level radioactive wastes. The thesis is aimed to measure the inelastic neutron scattering cross sections of Fe-56 using a new double flight-time method. With combined plastic and BaF2 scintillation detectors for the first time the emitted neutrons and photons are observed in coincidence.

  10. Numerical study of the particle transport in fast neutron detectors with conversion layer

    International Nuclear Information System (INIS)

    Sedlackova, K.; Zatko, B.; Necas, V.

    2012-01-01

    This paper deals with fast neutron and recoil proton transport simulation using statistical analysis of Monte Carlo radiation transport code (MCNPX). Its possibilities in the detector design and optimization are presented. MCNPX proved as a very advantageous self-contained simulation program for fast neutron and secondary proton tracking. Simulations of respective particle transport through conversion layer of HDPE and further in the active volume of detector let us to follow important characteristics as neutron/proton flux density, reaction rate of elastic scattering on hydrogen nuclei and deposited energy as well as their dependencies on incident neutron energy and conversion layer/active region thickness. The efficiency of neutrons to protons conversion has been calculated and its maximum was reached for 500 μm thick conversion layer. The minimum active region thickness has been estimated to be about 300 μm.(authors)

  11. Corrections on energy spectrum and scattering for fast neutron radiography at NECTAR facility

    International Nuclear Information System (INIS)

    Liu Shuquan; Thomas, Boucherl; Li Hang; Zou Yubin; Lu Yuanrong; Guo Zhiyu

    2013-01-01

    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 Universitaet Mounchen (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. (authors)

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

    Science.gov (United States)

    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.

  13. Fast neutron personnel dosimetry by CR-39 plastics a new electrochemical etching procedure

    International Nuclear Information System (INIS)

    Djeffal, S.

    1984-07-01

    In the first part of this work a brief description of solid state nuclear track detectors, the principles of track registration and the different reading techniques are given. In the experimental part of the present work we systematically analysed different etching procedures and set a new electrochemical etching method, which enables us to develop a new fast neutron dosimeter. This fast neutron dosimeter makes possible the measurement of low neutron doses in the energy range from 10 Kev to 20 Mev with a reasonably flat energy response. These new developments are very attractive in personnel neutron dosimetry where nuclear emulsions are still used despite their insensitivity to neutron energies down to 500 Kev (i.e. the energy range one often encounters around nuclear facilities)

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

    Energy Technology Data Exchange (ETDEWEB)

    Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Shinohara, T.; Kai, T.; Ooi, M. [Japan Atomic Energy Agency, 2–4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kamiyama, T.; Kiyanagi, Y.; Shiota, Y. [Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo-shi, Hokkaido 060-8628 (Japan); McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W. [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Feller, W.B. [NOVA Scientific, Inc., 10 Picker Rd., Sturbridge, MA 01566 (United States)

    2014-05-11

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

  15. Technical Meeting on Existing and Proposed Experimental Facilities for Fast Neutron Systems. Working Material

    International Nuclear Information System (INIS)

    2013-01-01

    The objective of the TM on “Existing and proposed experimental facilities for fast neutron systems” was threefold: 1) presenting and exchanging information about existing and planned experimental facilities in support of the development of innovative fast neutron systems; 2) allow creating a catalogue of existing and planned experimental facilities currently operated/developed within national or international fast reactors programmes; 3) once a clear picture of the existing experimental infrastructures is defined, new experimental facilities are discussed and proposed, on the basis of the identified R&D needs

  16. Technical Meeting on Existing and Proposed Experimental Facilities for Fast Neutron Systems. Presentations

    International Nuclear Information System (INIS)

    2013-01-01

    The objective of the TM on “Existing and proposed experimental facilities for fast neutron systems” is threefold: first, it is intended for presenting and exchanging information about existing and planned experimental facilities in support of the development of innovative fast neutron systems; second, it will allow to create a catalogue of existing and planned experimental facilities currently operated/developed within national or international fast reactors programmes; third, once a clear picture of the existing experimental infrastructures is defined, new experimental facilities will be discussed and proposed, on the basis of the identified R&D needs

  17. In-Pile Qualification of the Fast-Neutron-Detection-System

    Science.gov (United States)

    Fourmentel, D.; Villard, J.-F.; Destouches, C.; Geslot, B.; Vermeeren, L.; Schyns, M.

    2018-01-01

    In order to improve measurement techniques for neutron flux assessment, a unique system for online measurement of fast neutron flux has been developed and recently qualified in-pile by the French Alternative Energies and Atomic Energy Commission (CEA) in cooperation with the Belgian Nuclear Research Centre (SCK•ECEN). The Fast-Neutron-Detection-System (FNDS) has been designed to monitor accurately high-energy neutrons flux (E > 1 MeV) in typical Material Testing Reactor conditions, where overall neutron flux level can be as high as 1015 n.cm-2.s-1 and is generally dominated by thermal neutrons. Moreover, the neutron flux is coupled with a high gamma flux of typically a few 1015 γ.cm-2.s-1, which can be highly disturbing for the online measurement of neutron fluxes. The patented FNDS system is based on two detectors, including a miniature fission chamber with a special fissile material presenting an energy threshold near 1 MeV, which can be 242Pu for MTR conditions. Fission chambers are operated in Campbelling mode for an efficient gamma rejection. FNDS also includes a specific software that processes measurements to compensate online the fissile material depletion and to adjust the sensitivity of the detectors, in order to produce a precise evaluation of both thermal and fast neutron flux even after long term irradiation. FNDS has been validated through a two-step experimental program. A first set of tests was performed at BR2 reactor operated by SCK•CEN in Belgium. Then a second test was recently completed at ISIS reactor operated by CEA in France. FNDS proved its ability to measure online the fast neutron flux with an overall accuracy better than 5%.

  18. Signal predictions for a proposed fast neutron interrogation method

    International Nuclear Information System (INIS)

    Sale, K.E.

    1992-12-01

    We have applied the Monte Carlo radiation transport code COG) to assess the utility of a proposed explosives detection scheme based on neutron emission. In this scheme a pulsed neutron beam is generated by an approximately seven MeV deuteron beam incident on a thick Be target. A scintillation detector operating in the current mode measures the neutrons transmitted through the object as a function of time. The flight time of unscattered neutrons from the source to the detector is simply related to the neutron energy. This information along with neutron cross section excitation functions is used to infer the densities of H, C, N and O in the volume sampled. The code we have chosen to use enables us to create very detailed and realistic models of the geometrical configuration of the system, the neutron source and of the detector response. By calculating the signals that will be observed for several configurations and compositions of interrogated object we can investigate and begin to understand how a system that could actually be fielded will perform. Using this modeling capability many early on with substantial savings in time and cost and with improvements in performance. We will present our signal predictions for simple single element test cases and for explosive compositions. From these studies it is dear that the interpretation of the signals from such an explosives identification system will pose a substantial challenge

  19. Fast radio bursts and their possible neutron star origins

    Science.gov (United States)

    Hessels, J. W. T.

    2017-12-01

    The discovery of the ‘Lorimer Burst’, a little over a decade ago, ignited renewed interest in searching for short-duration radio transients (Lorimer et al 2007 Science 318 777). This event is now considered to be the first established Fast Radio Burst (FRB), which is a class of millisecond-duration radio transients (Thornton et al 2013 Science 341 53). The large dispersive delays observed in FRBs distinguish them from the individual bright pulses from Galactic pulsars, and suggests that they originate deep in extragalactic space. Amazingly, FRBs are not rare: the implied event rate ranges up to many thousands of events per sky, per day (Champion et al 2016 MNRAS 460 L30). The fact that only two dozen FRBs have been discovered to date is a consequence of the limited sensitivity and field of view of current radio telescopes (Petroff et al 2016 PASA 33 e045). The precise localization of FRB 121102, the first and currently only FRB observed to repeat (Spitler et al 2014 ApJ 790 101; Spitler et al 2016 Nature 531 202; Scholz et al 2016 ApJ 833 177), has led to the unambiguous identification of its host galaxy and thus proven its extragalactic origin and large energy scale (Chatterjee et al 2017 Nature 541 58; Tendulkar et al 2017 ApJL 834 L7; Marcote et al 2017 ApJL 834 L8). It remains unclear, however, whether all FRBs are capable of repeating [many appear far less active (Petroff et al 2015 MNRAS 454 457)] or whether FRB 121102 implies that there are multiple sub-classes. Regardless, the repetitive nature of FRB 121102 and its localization to within a star-forming region in the host galaxy (Bassa et al 2017 ApJL 843 L8) imply that the bursts might originate from an exceptionally powerful neutron star - one necessarily quite unlike any we have observed in the Milky Way. In these proceedings, I give a very brief introduction to the FRB phenomenon and focus primarily on the insights that FRB 121102 has provided thus far.

  20. Fast determination of impurities in metallurgical grade silicon for photovoltaics by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Hampel, J.; Boldt, F.M.; Gerstenberg, H.; Hampel, G.; Kratz, J.V.; Reber, S.; Wiehl, N.

    2011-01-01

    Standard wafer solar cells are made of near-semiconductor quality silicon. This high quality material makes up a significant part of the total costs of a solar module. Therefore, new concepts with less expensive so called solar grade silicon directly based on physiochemically upgraded metallurgical grade silicon are investigated. Metallurgical grade silicon contains large amounts of impurities, mainly transition metals like Fe, Cr, Mn, and Co, which degrade the minority carrier lifetime and thus the solar cell efficiency. A major reduction of the transition metal content occurs during the unidirectional crystallization due to the low segregation coefficient between the solid and liquid phase. A further reduction of the impurity level has to be done by gettering procedures applied to the silicon wafers. The efficiency of such cleaning procedures of metallurgical grade silicon is studied by instrumental neutron activation analysis (INAA). Small sized silicon wafers of approximately 200 mg with and without gettering step were analyzed. To accelerate the detection of transition metals in a crystallized silicon ingot, experiments of scanning whole vertical silicon columns with a diameter of approximately 1 cm by gamma spectroscopy were carried out. It was demonstrated that impurity profiles can be obtained in a comparably short time. Relatively constant transition metal ratios were found throughout an entire silicon ingot. This led to the conclusion that the determination of several metal profiles might be possible by the detection of only one 'leading element'. As the determination of Mn in silicon can be done quite fast compared to elements like Fe, Cr, and Co, it could be used as a rough marker for the overall metal concentration level. Thus, a fast way to determine impurities in photovoltaic silicon material is demonstrated. - Highlights: → We demonstrate a fast way to determine impurities in photovoltaic silicon by NAA. → We make first experiments of locally

  1. Reactions with fast radioactive beams of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  2. Reactions with fast radioactive beams of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Aumann, T.

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like 11 Li and 12 Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  3. Fast neutron therapy at the end of 1988 - a survey of the clinical data

    International Nuclear Information System (INIS)

    Wambersie, A.

    1990-01-01

    The clinical results reported from the different neutron therapy centres, in USA, Europe and Asia, are reviewed. Fast neutrons were proven to be superior to photons for locally extended inoperable salivary gland tumours. The reported overall local control rates are 67% and 24% respectively. Paranasal sinuses and some tumours of the head and neck area, especially extended tumours with large fixed lymph nodes, are also indications for neutrons. By contrast, the results obtained for brain tumours were, in general, disappointing. Neutrons were shown to bring a benefit in the treatment of well differentiated slowly growing soft tissue sarcomas. The reported overall local control rates are 53% and 38% after neutron and photon irradiation respectively. Better results were also reported for bone- and chondrosarcomas. The reported local control rates are 54% for osteosarcomas and 49% for chondrosarcomas after neutron irradiation; the corresponding values are 21% and 33% respectively after photon irradiation. For locally extended prostatic adenocarcinoma, the superiority of mixed schedule (neutrons+photons) was demonstrated by a RTOG randomized trial (local control rates 77% for mixed schedule compared to 31% for photons). Neutrons were also shown to be useful for palliative treatment of melanomas. Further studies are needed in order to evaluate the benefit of fast neutrons for other localisations such as cervix, bladder, rectum. It can be concluded that fast neutrons are superior to photons for at least 10% of the radiotherapy patients. It is likely that the new high-energy hospital-based cyclotron will further extend the indications of neutron therapy. However, patient selection remains one of the main problems and there is a need for development of individual predictive tests. (orig.)

  4. The fast neutron emission spectrum of 252-Cf

    International Nuclear Information System (INIS)

    Bensch, F.

    1979-07-01

    The aim of this work was a new measurement of the neutron emission spectrum of 252-Cf neutron standard sources as the IAEA is offering to users. The main feature was the application of gas-filled proton-recoil spectrometers and no TOF technique. The special interest of this document was in the temperature parameter of the Maxwellian distribution and in its relative deviations. In this connection, special measurements with high energy resolution were carried out in a search for fine structure neutron groups, which have been observed in some TOF measurements, but could not be reproduced during this measurement

  5. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: the EXILL campaign

    Directory of Open Access Journals (Sweden)

    de France G.

    2014-03-01

    Full Text Available A combination of germanium detectors has been installed at the PF1B neutron guide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in the neutron-capture induced-fission of 235U and 241Pu. In addition LaBr3 detectors from the FATIMA collaboration have been installed in complement with the EXOGAM clovers to measure lifetimes of low-lying excited states. The measured characteristics and online spectra indicate very good performances of the overall setup.

  6. Scanning tunneling spectroscopy on neutron irradiated MgB2 thin films

    International Nuclear Information System (INIS)

    Di Capua, Roberto; Salluzzo, Marco; Vaglio, Ruggero; Ferdeghini, Carlo; Ferrando, Valeria; Putti, Marina; Xi Xiaoxing; Aebersold, Hans U.

    2007-01-01

    Neutron irradiation was performed on MgB 2 thin films grown by hybrid physical chemical vapor deposition. Samples irradiated with different neutron fluences, having different critical temperatures, were studied by scanning tunneling spectroscopy in order to investigate the effect of the introduced disorder on the superconducting and spectroscopic properties. A monotonic increase of the π gap with increasing disorder was found

  7. Scanning tunneling spectroscopy on neutron irradiated MgB{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Di Capua, Roberto [University of Napoli and CNR-INFM/Coherentia, Via Cinthia, Naples I-80126 (Italy)], E-mail: rdicapua@na.infn.it; Salluzzo, Marco; Vaglio, Ruggero [University of Napoli and CNR-INFM/Coherentia, Via Cinthia, Naples I-80126 (Italy); Ferdeghini, Carlo [CNR-INFM/LAMIA, Via Dodecaneso 33, Genova I-16146 (Italy); Ferrando, Valeria [CNR-INFM/LAMIA, Via Dodecaneso 33, Genova I-16146 (Italy); Pennsylvania State University, University Park, PA 16802 (United States); Putti, Marina [CNR-INFM/LAMIA, Via Dodecaneso 33, Genova I-16146 (Italy); Xi Xiaoxing [Pennsylvania State University, University Park, PA 16802 (United States); Aebersold, Hans U. [Paul Scherrer Institut, Villigen CH-5232 (Switzerland)

    2007-09-01

    Neutron irradiation was performed on MgB{sub 2} thin films grown by hybrid physical chemical vapor deposition. Samples irradiated with different neutron fluences, having different critical temperatures, were studied by scanning tunneling spectroscopy in order to investigate the effect of the introduced disorder on the superconducting and spectroscopic properties. A monotonic increase of the {pi} gap with increasing disorder was found.

  8. Study on the identification method of chemical warfare agents with spectroscopy of neutron induced γ rays

    International Nuclear Information System (INIS)

    Liu Boxue; Li Yun; Li Xiangbao

    1996-01-01

    The paper briefly describes some non-destructive verification technologies of chemical warfare agents in-site, and some application of neutron induced gamma ray analysis, such as multi-elements analysis of coal, hidden explosive detection and identification of chemical agents. It also describes some problems in developing the portable isotopic neutron spectroscopy for non-destructive evaluation of chemical warfare agents

  9. Fast neutron fields at the RB reactor; Polja brzih neutron na reacktoru RB

    Energy Technology Data Exchange (ETDEWEB)

    Strugar, P; Pesic, M; Dasic, N [Institut za nuklearne nauke Boris Kidric Vinca, Beograd (Yugoslavia)

    1984-07-01

    Paper deals with the reasons and methods of realization of the RB neutron converters. The methods and results of neutron flux intensities and spectra measurements as well as gamma dose determination are presented. (author)

  10. Qualification and characterization of electronics of the fast neutron Hodoscope detectors using neutrons from CABRI core

    Science.gov (United States)

    Mirotta, S.; Guillot, J.; Chevalier, V.; Biard, B.

    2018-01-01

    The study of Reactivity Initiated Accidents (RIA) is important to determine up to which limits nuclear fuels can withstand such accidents without clad failure. The CABRI International Program (CIP), conducted by IRSN under an OECD/NEA agreement, has been launched to perform representative RIA Integral Effect Tests (IET) on real irradiated fuel rods in prototypical Pressurized Water Reactors (PWR) conditions. For this purpose, the CABRI experimental pulse reactor, operated by CEA in Cadarache, France, has been strongly renovated, and equipped with a pressurized water loop. The behavior of the test rod, located in that loop in the center of the driver core, is followed in real time during the power transients thanks to the hodoscope, a unique online fuel motion monitoring system, and one of the major distinctive features of CABRI. The hodoscope measures the fast neutrons emitted by the tested rod during the power pulse with a complete set of 153 Fission Chambers and 153 Proton Recoil Counters. During the CABRI facility renovation, the electronic chain of these detectors has been upgraded. In this paper, the performance of the new system is presented describing gain calibration methodology in order to get maximal Signal/Noise ratio for amplification modules, threshold tuning methodology for the discrimination modules (old and new ones), and linear detectors response limit versus different reactor powers for the whole electronic chain.

  11. Direct mass measurements of light neutron-rich nuclei using fast recoil spectrometers

    International Nuclear Information System (INIS)

    Vieira, D.J.; Wouters, J.M.

    1987-01-01

    Extensive new mass measurement capabilities have evolved with the development of recoil spectrometers. In the Z = 3 to 9 neutron-rich region alone, 12 neutron-rich nuclei have been determined for the first time by the fast-recoil direct mass measurement method. A recent experiment using the TOFI spectrometer illustrates this technique. A systematic investigation of nuclei that lie along or near the neutron-drip line has provided a valuable first glimpse into the nuclear structure of such nuclei. No evidence for a large single-particle energy gap at N = 14 is observed; however, a change in the two-neutron separation model calculations, and is interpreted in terms of the smaller 1s/sub 1/2/ - 1s/sub 1/2/ interaction compared to that of the 0d/sub 5/2/ - 0d/sub 5/2/ neutron-neutron interaction. 18 refs., 7 figs., 1 tab

  12. Effect of Gamma Rays on Fast Neutron Registration in CR-39

    CERN Document Server

    Kobzev, A P; El-Halem, A A; Abdul-Ghaphar, U S; Salama, T A

    2002-01-01

    A set of CR-39 plastic detectors with front PE radiator was exposed to Am-Be neutron source, which has an emission rate of 0.86\\cdot 10^{7} sec^{-1}, and the neutron dose equivalent rate 1 m apart from the source is equal to 11 mrem/hr. Another set of samples was irradiated by a neutron dose of 4 rem, then exposed to different gamma-ray doses using ^{60}Co source. It was found that the track density grows with the increase of neutron dose and etching time. It was also found that the bulk etching rate V_{B}, the track diameter and the sensitivity of the CR-39 plastic detector with respect to the neutron irradiation increased with increasing gamma-ray dose in the range 1?10 Mrad. These results show that CR-39 can be considered as a promising fast neutron dosimeter and gamma-ray dosimeter.

  13. Fast neutron detection by means of an organic solid state track detector

    International Nuclear Information System (INIS)

    Doerschel, B.; Streubel, G.

    1980-01-01

    Solid state track detectors consisting of cellulose triacetate foils are appropriate for measuring the fast neutron fluence without applying external radiators. Detector sensitivity has been determined as a function of neutron energy by performing irradiations with various neutron sources and monoenergetic neutrons of different energies. A comparison with theoretical results given in the literature for a simple model of track recording has shown sufficient agreement. The measuring errors and the influence of spectral changes in the neutron field on detector response are discussed for the studied method of fluence measurement. By means of these errors the measuring range has been determined for well defined irradiation conditions, taking into account spectral changes in the neutron field. (author)

  14. Attenuation of Reactor Gamma Radiation and Fast Neutrons Through Large Single-Crystal Materials

    International Nuclear Information System (INIS)

    Adib, M.

    2009-01-01

    A generalized formula is given which, for neutron energies in the range 10-4< E< 10 eV and gamma rays with average energy 2 MeV , permits calculation of the transmission properties of several single crystal materials important for neutron scattering instrumentation. A computer program Filter was developed which permits the calculation of attenuation of gamma radiation, nuclear capture, thermal diffuse and Bragg-scattering cross-sections as a function of materials constants, temperature and neutron energy. The applicability of the deduced formula along with the code checked from the obtained agreement between the calculated and experimental neutron transmission through various single-crystals A feasibility study for use of Si, Ge, Pb, Bi and sapphire is detailed in terms of optimum crystal thickness, mosaic spread and cutting plane for efficient transmission of thermal reactor neutrons and for rejection of the accompanying fast neutrons and gamma rays.

  15. Fast neutron spectrometry based on proton detection in CR-39 detector

    Energy Technology Data Exchange (ETDEWEB)

    Dajko, G.; Somogyi, G.

    1986-01-01

    The authors have developed a home-made proton-sensitive CR-39 track detector called MA-ND/p. Using this and the n-p scattering process the performance of a fast neutron spectrometer has been studied by applying two different methods. These are based on track density determinations by using varying radiator thicknesses at constant etching time and by using varying etching times at fixed radiator thickness, respectively. For both methods studied a computer programme is made to calculate the theoretically expected neutron sensitivity as a function of neutron energy. For both methods the neutron sensitivities, expressed in terms of observable etched proton tracks per neutron, are determined experimentally for 3.3 and 14.7 MeV neutron energies. The theoretical and experimental data obtained are compared.

  16. Fast neutron spectrometry based on proton detection in CR-39 detector

    International Nuclear Information System (INIS)

    Dajko, G.; Somogyi, G.

    1986-01-01

    The authors have developed a home-made proton-sensitive CR-39 track detector called MA-ND/p. Using this and the n-p scattering process the performance of a fast neutron spectrometer has been studied by applying two different methods. These are based on track density determinations by using varying radiator thicknesses at constant etching time and by using varying etching times at fixed radiator thickness, respectively. For both methods studied a computer programme is made to calculate the theoretically expected neutron sensitivity as a function of neutron energy. For both methods the neutron sensitivities, expressed in terms of observable etched proton tracks per neutron, are determined experimentally for 3.3 and 14.7 MeV neutron energies. The theoretical and experimental data obtained are compared. (author)

  17. Study of the propagation of fast neutrons in water, by Monte-Carlo methods

    International Nuclear Information System (INIS)

    Lafore, P.; Lattes, R.; Millot, J.P.

    1958-01-01

    We have studied the propagation in water of neutrons from mono-directional plane sources with energies ranging from 300 keV to 19,66 MeV, placed in an infinite water medium. The exact paths of a number of neutrons are determined, taking into account the microscopic sections, assuming that inelastic collisions of the neutrons on oxygen are absorptions, and neglecting the loss of energy by elastic collisions on oxygen. The neutron lifetimes have been made use of to study the propagation of neutrons from fission sources, Po-Be, Po-B and Ra-Be, as well as the reflection of fast neutrons on a semi-infinite water medium. We have taken complete account of the first collision in order to improve the precision of the results. The calculations were carried out by Mrs J. VASSEUR and Mr A. GUILLOU. (author) [fr

  18. Microdosimetric investigations at the fast neutron therapy facility at Fermilab

    International Nuclear Information System (INIS)

    Langen, K.M.

    1997-01-01

    Microdosimetry was used to investigate three issues at the neutron therapy facility (NTF) at Fermilab. Firstly, the conversion factor from absorbed dose in A-150 tissue equivalent plastic to absorbed dose in ICRU tissue was determined. For this, the effective neutron kerma factor ratios, i.e., oxygen tissue equivalent plastic and carbon to A-150 tissue equivalent plastic, were measured in the neutron beam. An A-150 tissue equivalent plastic to ICRU tissue absorbed dose conversion factor of 0.92 ± 0.04 was determined. Secondly, variations in the radiobiological effectiveness (RBE) in the beam were mapped by determining variations in two related quantities, e * and R, with field size and depth in tissue. Maximal variation in e * and R of 9% and 15% respectively were determined. Lastly, the feasibility of utilizing the boron neutron capture reaction on boron-10 to selectively enhance the tumor dose in the NTF beam was investigated

  19. Fast Neutron Dosimeter for the Space Environment, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Model calculations and risk assessment estimates indicate that secondary neutrons, with energies ranging between 0.5 to >150 MeV, make a significant contribution...

  20. Tritium release from fast neutron irradiated boron carbide

    International Nuclear Information System (INIS)

    Hollenberg, G.W.

    1977-01-01

    A high-energy neutron reaction with boron produces tritium. In the LMFBR control material, B 4 C, most of the tritium that is generated remains in the pellets. Potential retention mechanisms are discussed. 5 figures

  1. Energy spectra of fast neutrons by nuclear emulsion method

    International Nuclear Information System (INIS)

    Quaresma, A.A.

    1977-01-01

    An experimental method which uses nuclear emulsion plates to determine the energy spectrum of fission neutrons is described. By using this technique, we have obtained the energy distribution of neutrons from spontaneous fission of Cf 2 5 2 . The results are in good agreement with whose obtained previously by others authors who have used different detection techniques, and they are consistent with a Maxwellian distribution as expected by Weisskopf's nuclear evaporation theory. (author)

  2. Attenuation of fast neutron in concretes for biological shielding

    International Nuclear Information System (INIS)

    Labrada, A.; Chavez, A.; Gonzalez Mateu, D.; Desdin, F.; Tenjeiro, J.I.; Tellez, E.

    1993-01-01

    The attenuation of neutrons emitted by an 10 6 n/s. Am-Be source, in concretes elaborated with different aggregates is discussed in this paper. Two measurement methods were used an dosimetric system with Bonner spheres and 6 LiI(Eu) detector, and LAVSAN dielectric nuclear track detectors - with 238 U converts. The concretes elaborated with magnetite is reported as the best for neutron shielding while the Bauxite is not advisable for this purpose

  3. Recoil-proton fast-neutron counter telescope

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R. (Padua Univ. (Italy). Ist. di Fisica); Galeazzi, G.; Bressanini, G.

    1981-12-01

    A recoil-proton neutron counter telescope is described composed of a solid-state silicon transmission detector and a NE 102 A plastic scintillator, measuring the energy loss, the energy of the recoil protons and the time of flight between the two detectors. The counter exposed to monoenergetic neutron beams of energy from 6 to 20 MeV presents a low background and a moderate energy resolution. Its absolute efficiency is calculated up to 50 MeV.

  4. Recoil-proton fast-neutron-counter telescope

    Energy Technology Data Exchange (ETDEWEB)

    Galeazzi, G.; Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.; Bressanini, G.

    1981-01-01

    A proton-recoil neutron counter telescope is described composed of a solid state silicon transmission detector and a NE 102 A plastic scintillator, measuring the energy loss, the energy of the recoil protons and the time-of-flight between the two detectors. The counter exposed to monoenergetic neutron beams of energy from 6 to 20 MeV, presents a low background and a moderate energy resolution. Its absolute efficiency is calculated up to 50 MeV.

  5. A recoil-proton fast-neutron counter telescope

    International Nuclear Information System (INIS)

    Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.; Galeazzi, G.; Bressanini, G.

    1981-01-01

    A recoil-proton neutron counter telescope is described composed of a solid-state silicon transmission detector and a NE 102 A plastic scintillator, measuring the energy loss, the energy of the recoil protons and the time of flight between the two detectors. The counter exposed to monoenergetic neutron beams of energy from 6 to 20 MeV presents a low background and a moderate energy resolution. Its absolute efficiency is calculated up to 50 MeV. (author)

  6. Survey of neutron spectra generated by the fission of heavy nuclei induced by fast neutrons

    International Nuclear Information System (INIS)

    Lovchikova, G.N.; Trufanov, A.M.

    1997-01-01

    A review of neutron fission spectra measurements is presented. This review and the results of this analysis was performed with the participation of the authors. It is shown that there is a need for additional measurements of the energy and angular distributions of secondary neutrons in order to improve the understanding of the neutron emission mechanism in fission. (author). 21 refs, 6 figs

  7. Neutron Collar Evolution and Fresh PWR Assembly Measurements with a New Fast Neutron Passive Collar

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, Howard Olsen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Geist, William H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Root, Margaret A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rael, Carlos D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Belian, Anthony P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-02

    The passive neutron collar approach removes the effect of poison rods when using a 1mm Gd liner. This project sets out to solve the following challenges: BWR fuel assemblies have less mass and less neutron multiplication than PWR; and effective removal of cosmic ray spallation neutron bursts needed via QC tests.

  8. Measurements of the energy spectrum of backscattered fast neutrons

    International Nuclear Information System (INIS)

    Segal, Y.

    1976-03-01

    Experimental measurements have been made of the energy spectra of neutrons transmitted through slabs of iron, lead and perspex for incident neutron energies of 0.5, 1.0, 1.5 and 1.8 MeV. The neutron energy measurements were made using a He-3 spectrometer. The dependence of the neutrons energy spectrum as a function of scattering thickness was determined. The neutrons source used was a 3MeV Van de Graaff accelerator with a tritium target using the H 3 (p,n) He 3 reaction. The results obtained by the investigator on energy dependence of transmitted neutrons as a function of thickness of scattering material were compared, where possible, with the results obtained by other workers. The comparisons indicated good agreement. The experiment's results are compared with MORSE Monte Carlo calculated values. It is worthwhile to note that direct comparison between measured cross section values and the recommended ones are very far from satisfactory. In almost all cases the calculated spectrum is harder than the experimental one, a situation common to the penetrating and the back-scattered flux

  9. Monitoring the fast neutrons in a high flux: The case for 242Pu fission chambers

    International Nuclear Information System (INIS)

    Filliatre, P.; Jammes, C.; Oriol, L.; Geslot, B.; Vermeeren, L.

    2009-01-01

    Fission chambers are widely used for on-line monitoring of neutron fluxes in irradiation reactors. A selective measurement of a component of interest of the neutron flux is possible in principle thanks to a careful choice of the deposit material. However, measuring the fast component is challenging when the flux is high (up to 10 15 n/cm 2 /s) with a significant thermal component. The main problem is that the isotopic content of a material selected for its good response to fast neutrons evolves with irradiation, so that the material is more and more sensitive to thermal neutrons. Within the framework of the FNDS (Fast Neutron Detector System) project, we design tools that simulate the evolution of the isotopic composition and fission rate for several deposits under any given flux. In the case of a high flux with a significant thermal component, 242 Pu is shown after a comprehensive study of all possibilities to be the best choice for measuring the fast component, as long as its purity is sufficient. If an estimate of the thermal flux is independently available, one can correct the signal for that component. This suggests a system of two detectors, one of which being used for such a correction. It is of very high interest when the detectors must be operated up to a high neutron fluence. (authors)

  10. Monitoring the fast neutrons in a high flux: The case for {sup 242}Pu fission chambers

    Energy Technology Data Exchange (ETDEWEB)

    Filliatre, P.; Jammes, C.; Oriol, L.; Geslot, B. [Commissariat a l' Energie Atomique, DEN/SPEX/LDCI, Centre de Cadarache, F-13108 Saint-Paul-lez-Durance (France); Vermeeren, L. [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)

    2009-07-01

    Fission chambers are widely used for on-line monitoring of neutron fluxes in irradiation reactors. A selective measurement of a component of interest of the neutron flux is possible in principle thanks to a careful choice of the deposit material. However, measuring the fast component is challenging when the flux is high (up to 10{sup 15} n/cm{sup 2}/s) with a significant thermal component. The main problem is that the isotopic content of a material selected for its good response to fast neutrons evolves with irradiation, so that the material is more and more sensitive to thermal neutrons. Within the framework of the FNDS (Fast Neutron Detector System) project, we design tools that simulate the evolution of the isotopic composition and fission rate for several deposits under any given flux. In the case of a high flux with a significant thermal component, {sup 242}Pu is shown after a comprehensive study of all possibilities to be the best choice for measuring the fast component, as long as its purity is sufficient. If an estimate of the thermal flux is independently available, one can correct the signal for that component. This suggests a system of two detectors, one of which being used for such a correction. It is of very high interest when the detectors must be operated up to a high neutron fluence. (authors)

  11. Commissioning optically stimulated luminescence in vivo dosimeters for fast neutron therapy

    Energy Technology Data Exchange (ETDEWEB)

    Young, Lori A., E-mail: layoung@uw.edu; Sandison, George [Department of Radiation Oncology, University of Washington, Seattle, Washington 98115 (United States); Yang, Fei [Sylvester comprehensive Cancer Center, University of Miami, Miami, Florida 33124 (United States); Woodworth, Davis [Department of Physics, University of Reno, Reno, Nevada 89557 (United States); McCormick, Zephyr [Department of Physics, University of California, Santa Barbara, California 93106 (United States)

    2016-01-15

    Purpose: Clinical in vivo dosimeters intended for use with photon and electron therapies have not been utilized for fast neutron therapy because they are highly susceptible to neutron damage. The objective of this work was to determine if a commercial optically stimulated luminescence (OSL) in vivo dosimetry system could be adapted for use in fast neutron therapy. Methods: A 50.5 MeV fast neutron beam generated by a clinical neutron therapy cyclotron was used to irradiate carbon doped aluminum oxide (Al{sub 2}O{sub 3}:C) optically simulated luminescence dosimeters (OSLDs) in a solid water phantom under standard calibration conditions, 150 cm SAD, 1.7 cm depth, and 10.3 × 10.0 cm field size. OSLD fading and electron trap depletion studies were performed with the OSLDs irradiated with 20 and 50 cGy and monitored over a 24-h period to determine the optimal time for reading the dosimeters during calibration. Four OSLDs per group were calibrated over a clinical dose range of 0–150 cGy. Results: OSLD measurement uncertainties were lowered to within ±2%–3% of the expected dose by minimizing the effect of transient fading that occurs with neutron irradiation and maintaining individual calibration factors for each dosimeter. Dose dependent luminescence fading extended beyond the manufacturer’s recommended 10 min period for irradiation with photon or electron beams. To minimize OSL variances caused by inconsistent fading among dosimeters, the observed optimal time for reading the OSLDs postirradiation was between 30 and 90 min. No field size, wedge factor, or gantry angle dependencies were observed in the OSLDs irradiated by the studied fast neutron beam. Conclusions: Measurements demonstrated that uncertainties less than ±3% were attainable in OSLDs irradiated with fast neutrons under clinical conditions. Accuracy and precision comparable to clinical OSL measurements observed with photons can be achieved by maintaining individual OSLD calibration factors and

  12. Review of clinical results of fast neutron therapy in the USA

    International Nuclear Information System (INIS)

    Peters, L.J.; Maor, M.H.; Laramore, G.E.; Griffin, T.W.; Hendrickson, F.R.

    1986-01-01

    Fast neutron radiotherapy in the United States is entering a new era in which dedicated hospital-based generators with isocentric beam capability are replacing treatment facilities based on fixed beams extracted from physics accelerators. All available clinical data, however, come from the older facilities. The majority of randomized trials conducted in the U.S. have used neutrons in a mixed schedule with photons, in which the aim was to deliver two-fifths of the total dose with neutrons; the neutron dose per fraction was set as the estimated equivalent of 2 Gy photons in terms of late normal tissue injury. Overall treatment time was held constant compared with the control photon therapy regimens (usually 6-8 weeks). Random studies of this type showed no evidence of a therapeutic gain in the treatment of advanced primary carcinomas of the head and neck, lung, uterine cervix, or pancreas. Based on a reassessment of all the available clinical and radiobiological data, and taking advantage of the greater technical flexibility offered by hospital-based facilities, the strategy of fast neutron therapy for future trials has been changed. In these trials neutrons are being used in a 12 fraction, 4 week regimen to treat gross disease, with elective therapy given wherever possible using low LET irradiation. Concomitantly, research is proceeding to define predictors of tumor response to high LET radiations in order to better select patients for fast neutron radiotherapy

  13. Method and apparatus for dual-spaced fast/epithermal neutron porosity measurements

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.

    1986-01-01

    A method is described for determining the porosity of earth formations in the vicinity of a well borehole, comprising: (a) irradiating the earth formations in the vicinity of the well borehole with a continuous chemical type source of fast neutrons, (b) detecting the fast neutron population at a first shorter spaced distance from the neutron source in the borehole and generating signals representative thereof, (c) detecting the epithermal neutron population at a second space distance from the neutron source in the borehole and generating signals representative thereof, the second spaced distance being greater than the first spaced distance from the neutron source, (d) forming a ratio of the signals representing the fast and epithermal neutron populations to derive a measurement signal functionally related to the porosity of the earth formations in the vicinity of the borehole, and (e) calibrating the measurement signal according to a predetermined functional relationship to derive a porosity signal quantitatively representative of the porosity of the earth formations in the vicinity of the borehole

  14. Fast neutron measurements at the nELBE time-of-flight facility

    Directory of Open Access Journals (Sweden)

    Junghansa A. R.

    2015-01-01

    Full Text Available The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV. nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.

  15. Characterization of a fast to thermal neutron spectrum converter on PROSPERO reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet, X.; Authier, N.; Casoli, P.; Combacon, S. [CEA, Valduc Center, 21120 Is sur Tille (France); Calzavarra, Y. [ILL, Institut Laue Langevin, 38000 Grenoble (France)

    2009-07-01

    The PROSPERO reactor is located at CEA Valduc Center in France. The reactor is composed of an internal core made of High Enriched Uranium metal alloy surrounded by a reflector of depleted uranium. The reactor is used as a fast neutron spectrum source and is operated in delayed critical state with a continuous and steady power for several hours, which can vary from 3 mW to 3 kW, which is the nominal power. The flux at nominal power varies from 5.10{sup +10} n.cm{sup -2}/s at the reflector surface to 10{sup +7} n.cm{sup -2}/s at 5 meters from reactor axis. It has been decided to build a neutron energy converter allowing the production of a neutron thermal spectrum. As the core produces fast neutrons spectrum, we built a hollow cubic box of 50 cm x 50 cm x 50 cm with 10-cm-thick polyethylene bricks and placed one meter away from central reactor axis to moderate as much as possible neutrons to lower energies (E<0.6 eV). Analysis of the moderated flux inside the converter was performed using different activation foils such as indium or gold. We have developed a model of the experiment in the Monte Carlo neutron transport code TRIPOLI-4. A non-analogous transport calculation scheme was necessary to reproduce properly the experimental activities. The results of the calculated activations are within 4% of the experimental measurements given with 10% uncertainty (2 sigma). We show that the converter realizes thermalization of 80 % of the PROSPERO reactor fast neutrons below the cadmium threshold of 0.6 eV. Epithermal neutrons represent 15% of the spectrum and only 5% are in the fast neutron range above 1 MeV. The total flux at the center of the converter is 1.4 10{sup +9} n.cm{sup -2}/s at 3000 W

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  17. Comparison of Experiment and Simulation of the triple GEM-Based Fast Neutron Detector

    International Nuclear Information System (INIS)

    Wang Xiao-Dong; Luo Wen; Zhang Jun-Wei; Yang He-Run; Duan Li-Min; Lu Chen-Gui; Hu Rong-Jiang; Hu Bi-Tao; Zhang Chun-Hui; Yang Lei; Zhou Jian-Rong; An Lv-Xing

    2015-01-01

    A detector for fast neutrons based on a 10 × 10 cm"2 triple gas electron multiplier (GEM) device is developed and tested. A neutron converter, which is a high density polyethylene (HDPE) layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium (DT, 14 MeV), deuterium-deuterium (DD, 2.45 MeV), and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton (GEM material), and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented. (paper)

  18. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons

    International Nuclear Information System (INIS)

    Lau, Ch.

    2000-01-01

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons

  19. DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

    OpenAIRE

    Sunardi, Sunardi; Muryono, Muryono

    2010-01-01

    Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec).  At this research condition of neutron generator was set at...

  20. Scanning of Cargo Containers by Gamma-Ray and Fast Neutron Radiography

    International Nuclear Information System (INIS)

    Yousri, A.M.; Bashter, I.I.; Megahid, M.R.; Osman, A.M.; Kansouh, W.A.; Reda, A.M.

    2011-01-01

    This paper describes the combined systems which were installed and tested to detect contraband smuggled in cargo containers. These combined systems are based on radiographers work by gamma-rays emitted from point source 60 Co with 0.5 Ci activity and neutrons emitted from point isotopic sources of Pu-α-Be as well as 14 MeV neutrons emitted from sealed tube neutron generator. The transmitted gamma ray through the inspected object was measured by gamma detection system with NaI(Tl) detector while the transmitted fast neutron beam was measured by a neutron gamma detection system with stilbene organic scintillator. The later possess the capability of discrimination between between gamma and neutron pulses using a discrimination system based on pulse shape discrimination method. The measured intensities of primary incident and transmitted beams of gamma-rays and fast neutrons were used to construct 2D cross-sectional images of the inspected objects hidden directly within benign materials of the container and for object screened by high dense material to stop object detection by gamma or X-rays. The constructed images for the inspected objects show the good capability and effectiveness of the installed gamma and neutron radiographers to detect illicit materials hidden in air cargo containers and sea containers of med size. They have also indicated that the developed scanning systems possess the ease of mobility and low cost of scanning