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Sample records for pulsed fast-neutron transmission

  1. Fast-neutron spectrometry using a ³He ionization chamber and digital pulse shape analysis.

    Science.gov (United States)

    Chichester, D L; Johnson, J T; Seabury, E H

    2012-08-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type (3)He ionization chamber to measure the fast-neutron spectra of a deuterium-deuterium electronic neutron generator, a bare (252)Cf spontaneous fission neutron source, and of the transmitted fast neutron spectra of a (252)Cf source attenuated by water, graphite, liquid nitrogen, and magnesium. Rise-time dPSA has been employed using the common approach for analyzing n +(3)He→(1)H+(3)H ionization events and improved to account for wall-effect and pile-up events, increasing the fidelity of these measurements. Simulations have been performed of the different experimental arrangements and compared with the measurements, demonstrating general agreement between the dPSA-processed fast-neutron spectra and predictions. The fast-neutron resonance features of the attenuation cross sections of the attenuating materials are clearly visible within the resolution limits of the electronics used for the measurements, and the potential applications of high-resolution fast-neutron spectrometry for nuclear nonproliferation and safeguards measurements are discussed.

  2. Fast-Neutron Spectrometry Using a 3He Ionization Chamber and Digital Pulse Shape Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. L. Chichester; J. T. Johnson; E. H. Seabury

    2010-05-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type 3He proportional counter to measure the fast neutron spectra of bare 252Cf and 241AmBe neutron sources. Measurements have also been made to determine the attenuated fast neutron spectra of 252Cf shielded by several materials including water, graphite, liquid nitrogen, magnesium, and tungsten. Rise-time dPSA has been employed using the common rise-time approach for analyzing n +3He ? 1H + 3H ionization events and a new approach has been developed to improve the fidelity of these measurements. Simulations have been performed for the different experimental arrangements and are compared, demonstrating general agreement between the dPSA processed fast neutron spectra and predictions.

  3. A charge-collection method for measurements of pulsed fast-neutron flux

    CERN Document Server

    Ouyang, X P; Ho, Y K; Zhang, Z B

    2002-01-01

    A charge-collection method for measuring the flux of pulsed fast neutrons in current mode has been developed, which is based on the well-known recoil-proton method combined with ion-induced secondary electron emission from solid surfaces. The detection unit consists of four elements: an n-p converter, an absorber, a collector, and a rear insulator. The assembly does not require vacuum for operation. Recoil protons from the n-p converter and the secondary electrons induced by the passing protons on the interface of the absorber and the collector contribute to the detector output signal. By properly choosing the materials and the combination of the absorber and the collector, the fraction of secondary electrons in the output signal can be determined experimentally. This detection concept allows one to design a medium type of fast-neutron detector for measurements of extremely intense pulsed neutron flux with a number of advantages over the existing systems.

  4. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, A.A., E-mail: a.a.ivanova@inp.nsk.su [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Zubarev, P.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Ivanenko, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Khilchenko, A.D. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Kotelnikov, A.I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Polosatkin, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Puryga, E.A.; Shvyrev, V.G. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Sulyaev, Yu.S. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2016-08-11

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL–3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL–3 and GDT devices. This analyzer was tested and calibrated with the help of {sup 137}Cs and {sup 252}Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented. - Highlights: • Electronic equipment for measurement of fast neutron flux with stilbene scintillator is presented. • FPGA-implemented digital pulse-shape discrimination algorithm by charge comparison method is shown. • Calibration of analyzer was carried out with {sup 137}Cs and {sup 252}Cf. • Figures of Merit (FOM) values for energy cuts from 1/8 Cs to 2 Cs are from 1.264 to 2.34 respectively.

  5. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    Science.gov (United States)

    Ivanova, A. A.; Zubarev, P. V.; Ivanenko, S. V.; Khilchenko, A. D.; Kotelnikov, A. I.; Polosatkin, S. V.; Puryga, E. A.; Shvyrev, V. G.; Sulyaev, Yu. S.

    2016-08-01

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL-3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL-3 and GDT devices. This analyzer was tested and calibrated with the help of 137Cs and 252Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented.

  6. Fast neutron tomography with real-time pulse-shape discrimination in organic scintillation detectors

    Science.gov (United States)

    Joyce, Malcolm J.; Agar, Stewart; Aspinall, Michael D.; Beaumont, Jonathan S.; Colley, Edmund; Colling, Miriam; Dykes, Joseph; Kardasopoulos, Phoevos; Mitton, Katie

    2016-10-01

    A fast neutron tomography system based on the use of real-time pulse-shape discrimination in 7 organic liquid scintillation detectors is described. The system has been tested with a californium-252 source of dose rate 163 μSv/h at 1 m and neutron emission rate of 1.5×107 per second into 4π and a maximum acquisition time of 2 h, to characterize two 100×100×100 mm3 concrete samples. The first of these was a solid sample and the second has a vertical, cylindrical void. The experimental data, supported by simulations with both Monte Carlo methods and MATLAB®, indicate that the presence of the internal cylindrical void, corners and inhomogeneities in the samples can be discerned. The potential for fast neutron assay of this type with the capability to probe hydrogenous features in large low-Z samples is discussed. Neutron tomography of bulk porous samples is achieved that combines effective penetration not possible with thermal neutrons in the absence of beam hardening.

  7. Statistical properties of an algorithm used for illicit substance detection by fast-neutron transmission

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-06-01

    A least-squares algorithm developed for analysis of fast-neutron transmission data resulting from non-destructive interrogation of sealed luggage and containers is subjected to a probabilistic interpretation. The approach is to convert knowledge of uncertainties in the derived areal elemental densities, as provided by this algorithm, into probability information that can be used to judge whether an interrogated object is either benign or potentially contains an illicit substance that should be investigated further. Two approaches are considered in this paper. One involves integration of a normalized probability density function associated with the least-squares solution. The other tests this solution against a hypothesis that the interrogated object indeed contains illicit material. This is accomplished by an application of the F-distribution from statistics. These two methods of data interpretation are applied to specific sets of neutron transmission results produced by Monte Carlo simulation.

  8. Nuclear data needs and sensitivities for illicit substance detection using fast-neutron transmission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Micklich, B.J.; Harper, M.K.; Sagalovsky, L.; Smith, D.L.

    1994-05-01

    Results from analysis of fast-neutron transmission spectra in the interrogation of luggage for illicit substances are quite sensitive to the neutron total cross section data employed. Monte Carlo and analytical techniques are used to explore the uses for such data and to demonstrate the sensitivity of these results to various total cross sections employed in the analysis. The status of total cross section information required for materials commonly found in containers having both illicit and benign substances, with particular attention to the matter of data uncertainties, is considered in the context of the available nuclear data. Deficiencies in the contemporary nuclear data base for this application are indicated and suggestions are offered for new measurements or evaluations.

  9. Analysis of the scintillation mechanism in a pressurized 4He fast neutron detector using pulse shape fitting

    OpenAIRE

    R.P. Kelley; Murer, D.; Ray, H.; K.A. Jordan

    2015-01-01

    An empirical investigation of the scintillation mechanism in a pressurized 4He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a 252Cf spontaneous fission source and a (d,d) neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactiv...

  10. Irradiation Effects for the Pulsed Fast Neutron Analysis (PFNA) Cargo Interrogation System

    Energy Technology Data Exchange (ETDEWEB)

    Slater, C.O.

    2001-02-02

    At the request of Safety and Ecology Corporation of Tennessee, radiation effects of the proposed Pulsed Fast Neutron Analysis (PFNA) Cargo Interrogation System have been examined. First, fissile cargo were examined to determine if a significant neutron signal would be observable during interrogation. Results indicated that ample multiplication would be seen for near critical bare targets. The water-reflected sphere showed relatively little multiplication. By implication, a fissile target shielded by hydrogenous cargo might not be detectable by neutron interrogation, particularly if reliance is placed on the neutron signal. The cargo may be detectable if use can be made of the ample increase in the photon signal. Second, dose rates were calculated at various locations within and just outside the facility building. These results showed that some dose rates may be higher than the target dose rate of 0.05 mrem/h. However, with limited exposure time, the total dose may be well below the allowed total dose. Lastly, estimates were made of the activation of structures and typical cargo. Most cargo will not be exposed long enough to be activated to levels of concern. On the other hand, portions of the structure may experience buildup of some radionuclides to levels of concern.

  11. Fast neutron imaging device and method

    Science.gov (United States)

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

    2014-02-11

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

  12. The optimisation of the fast neutron and gamma-ray transmission set-up for moisture measurement of coke.

    Science.gov (United States)

    Cywicka-Jakiel, T; Łoskiewicz, J; Tracz, G

    2003-01-01

    In the present paper, modelling calculations with the Monte Carlo (MCNP4C) code were performed for the optimisation of the fast neutron and gamma-ray transmission, set-up, used for the humidity measurement of coke. The optimisation focused on maximising the sensitivity of the neutron flux to humidity changes and on lowering neutron-counting error, both leading to higher accuracy of coke moisture determination. Different materials used for the source shielding and neutron collimation, together with different dimensions of the neutron collimators were studied. The results obtained from the Monte Carlo modelling correlate with the real instrument performance.

  13. Narcotics detection using fast-neutron interrogation

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

    Fast-neutron interrogation techniques are being investigated for detection of narcotics in luggage and cargo containers. This paper discusses two different fast-neutron techniques. The first uses a pulsed accelerator or sealed-tube source to produce monoenergetic fast neutrons. Gamma rays characteristic of carbon and oxygen are detected and the elemental densities determined. Spatial localization is accomplished by either time of flight or collimators. This technique is suitable for examination of large containers because of the good penetration of the fast neutrons and the low attenuation of the high-energy gamma rays. The second technique uses an accelerator to produce nanosecond pulsed beams of deuterons that strike a target to produce a pulsed beam of neutrons with a continuum of energies. Elemental distributions are obtained by measuring the neutron spectrum after the source neutrons pass through the items being interrogated. Spatial variation of elemental densities is obtained by tomographic reconstruction of projection data obtained for three to five angles and relatively low (2 cm) resolution. This technique is best suited for examination of luggage or small containers with average neutron transmissions greater than about 0.01. Analytic and Monte-Carlo models are being used to investigate the operational characteristics and limitations of both techniques.

  14. Transmission of fast neutrons along cylindrical air-filled ducts pierced in ilmenite concrete

    Energy Technology Data Exchange (ETDEWEB)

    Megahid, R.M.; Bashter, I.I.

    1980-01-01

    The variation of flux of fast neutrons along air filled ducts passing through ilmenite concrete of density 4.6 gm. cm/sup -3/ was measured. Ducts of diameter 2.9, 5.8 and 10 cm were used. Measurements were carried out at different distances (up to 120 cm) along the duct axis. The source of neutrons was a collimated beam of reactor neutrons emitted from one of the horizontal channels of ET-RR-1 reactor. All measurements were performed using phosphorus activation detectors. The data obtained show the dependence of flux values on duct length and diameter.

  15. Quantitative discrimination between oil and water in drilled bore cores via fast-neutron resonance transmission radiography

    CERN Document Server

    Vartsky, D; Dangendorf, V; Israelashvili, I; Mor, I; Bar, D; Tittelmeier, K; Weierganz, M; Breskin, A

    2016-01-01

    A novel method based on Fast Neutron Resonance Transmission Radiography is proposed for non-destructive, quantitative determination of the weight percentages of oil and water in cores taken from subterranean or underwater geological formations. The ability of the method to distinguish water from oil stems from the unambiguously-specific energy dependence of the neutron cross-sections for the principal elemental constituents. Monte-Carlo simulations and initial results of experimental investigations indicate that the technique may provide a rapid, accurate and non-destructive method for quantitative evaluation of core fluids in thick intact cores, including those of tight shales for which the use of conventional core analytical approaches appears to be questionable.

  16. Methodology for the use of proportional counters in pulsed fast neutron yield measurements

    CERN Document Server

    Tarifeño-Saldivia, Ariel; Pavez, Cristian; Soto, Leopoldo

    2011-01-01

    This paper introduces in full detail a methodology for the measurement of neutron yield and the necessary efficiency calibration, to be applied to the intensity measurement of neutron bursts where individual neutrons are not resolved in time, for any given moderated neutron proportional counter array. The method allows efficiency calibration employing the detection neutrons arising from an isotopic neutron source. Full statistical study of the procedure is descripted, taking into account contributions arising from counting statistics, piling-up statistics of real detector pulse-height spectra and background fluctuations. The useful information is extracted from the net waveform area of the signal arising from the electric charge accumulated inside the detector tube. Improvement of detection limit is gained, therefore this detection system can be used in detection of low emission neutron pulsed sources with pulses of duration from nanoseconds to up. The application of the methodology to detection systems to be...

  17. System design considerations for fast-neutron interrogation systems

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-10-01

    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.

  18. Transport simulation and image reconstruction for fast-neutron detection of explosives and narcotics

    Energy Technology Data Exchange (ETDEWEB)

    Micklich, B.J.; Fink, C.L.; Sagalovsky, L.

    1995-07-01

    Fast-neutron inspection techniques show considerable promise for explosive and narcotics detection. A key advantage of using fast neutrons is their sensitivity to low-Z elements (carbon, nitrogen, and oxygen), which are the primary constituents of these materials. We are currently investigating two interrogation methods in detail: Fast-Neutron Transmission Spectroscopy (FNTS) and Pulsed Fast-Neutron Analysis (PFNA). FNTS is being studied for explosives and narcotics detection in luggage and small containers for which the transmission ratio is greater than about 0.01. The Monte-Carlo radiation transport code MCNP is being used to simulate neutron transmission through a series of phantoms for a few (3-5) projection angles and modest (2 cm) resolution. Areal densities along projection rays are unfolded from the transmission data. Elemental abundances are obtained for individual voxels by tomographic reconstruction, and these reconstructed elemental images are combined to provide indications of the presence or absence of explosives or narcotics. PFNA techniques are being investigated for detection of narcotics in cargo containers because of the good penetration of the fast neutrons and the low attenuation of the resulting high-energy gamma-ray signatures. Analytic models and Monte-Carlo simulations are being used to explore the range of capabilities of PFNA techniques and to provide insight into systems engineering issues. Results of studies from both FNTS and PFNA techniques are presented.

  19. Measurement of fast neutrons and secondary gamma rays in graphite

    Energy Technology Data Exchange (ETDEWEB)

    Makarious, A.S.; El-Asyd Abdo, A.; Kansouh, W.A. [Atomic Energy Authority, Cairo (Egypt). Nuclear Research Centre; Bashter, I.I. [Zagazig Univ. (Egypt). Faculty of Science

    1996-05-01

    The spatial fluxes and energy distributions of fast neutrons, total gamma rays and secondary gamma rays transmitted through different thicknesses of graphite have been measured. The graphite samples were arranged in front of one of the horizontal channels of the ET-RR-1 reactor. Gamma ray measurements were carried out for bare, cadmium filtered and boron carbide filtered reactor beams. A fast neutron and gamma ray spectrometer with a stilbene crystal was used to measure the spectrum of fast neutrons and gamma rays. Pulse shape discrimination using the zero cross over technique was used to distinguish the proton pulses from the electron pulses. The total fast neutrons macroscopic cross section and the linear attenuation coefficient for gamma rays were derived both for the whole energy range and at different energies. The obtained values were used to calculate the relaxation lengths for fast neutrons and gamma rays. (Author).

  20. Fast neutron detection with a segmented spectrometer

    Science.gov (United States)

    Langford, T. J.; Bass, C. D.; Beise, E. J.; Breuer, H.; Erwin, D. K.; Heimbach, C. R.; Nico, J. S.

    2015-01-01

    A fast neutron spectrometer consisting of segmented plastic scintillator and 3He proportional counters was constructed for the measurement of neutrons in the energy range 1-200 MeV. We discuss its design, principles of operation, and the method of analysis. The detector is capable of observing very low neutron fluxes in the presence of ambient gamma background and does not require scintillator pulse-shape discrimination. The spectrometer was characterized for its energy response in fast neutron fields of 2.5 MeV and 14 MeV, and the results are compared with Monte Carlo simulations. Measurements of the fast neutron flux and energy response at 120 m above sea-level (39.130°N, 77.218°W) and at a depth of 560 m in a limestone mine are presented. Finally, the design of a spectrometer with improved sensitivity and energy resolution is discussed.

  1. Fast Neutron Detection with a Segmented Spectrometer

    CERN Document Server

    Langford, T J; Beise, E J; Breuer, H; Erwin, D K; Heimbach, C R; Nico, J S

    2014-01-01

    A fast neutron spectrometer consisting of segmented plastic scintillator and He-3 proportional counters was constructed for the measurement of neutrons in the energy range 1 MeV to 200 MeV. We discuss its design, principles of operation, and the method of analysis. The detector is capable of observing very low neutron fluxes in the presence of ambient gamma background and does not require scintillator pulse-shape discrimination The spectrometer was characterized for energy resolution and efficiency in fast neutron fields of 2.5 MeV, 14 MeV, and fission spectrum neutrons, and the results are compared with Monte Carlo simulations. Measurements of the fast neutron flux and energy response at 120 m above sea-level (39.130 deg. N, 77.218 deg. W) and at a depth of 560 m in a limestone mine are presented. Finally, the design of a spectrometer with improved sensitivity and energy resolution is discussed.

  2. Fast neutron detection with a segmented spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Langford, T.J., E-mail: thomas.langford@yale.edu [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742 (United States); Bass, C.D. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Beise, E.J.; Breuer, H.; Erwin, D.K. [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Heimbach, C.R.; Nico, J.S. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2015-01-21

    A fast neutron spectrometer consisting of segmented plastic scintillator and {sup 3}He proportional counters was constructed for the measurement of neutrons in the energy range 1–200 MeV. We discuss its design, principles of operation, and the method of analysis. The detector is capable of observing very low neutron fluxes in the presence of ambient gamma background and does not require scintillator pulse-shape discrimination. The spectrometer was characterized for its energy response in fast neutron fields of 2.5 MeV and 14 MeV, and the results are compared with Monte Carlo simulations. Measurements of the fast neutron flux and energy response at 120 m above sea-level (39.130°N, 77.218°W) and at a depth of 560 m in a limestone mine are presented. Finally, the design of a spectrometer with improved sensitivity and energy resolution is discussed.

  3. FAST NEUTRONIC REACTOR

    Science.gov (United States)

    Snell, A.H.

    1957-12-01

    This patent relates to a reactor and process for carrying out a controlled fast neutron chain reaction. A cubical reactive mass, weighing at least 920 metric tons, of uranium metal containing predominantly U/sup 238/ and having a U/sup 235/ content of at least 7.63% is assembled and the maximum neutron reproduction ratio is limited to not substantially over 1.01 by insertion and removal of a varying amount of boron, the reactive mass being substantially freed of moderator.

  4. Comparison of fast neutron rates for the NEOS experiment

    Science.gov (United States)

    Ko, Y. J.; Jang, C. H.; Siyeon, Kim; Kim, J. Y.; Kim, H. S.; Seo, K. M.; Han, B. Y.; Sun, G. M.; Jeon, E. J.; Lee, Jaison; Lee, M. H.; Oh, Y. M.; Park, K. S.; Joo, K. K.; Kim, B. R.; Kim, H. J.; Lee, J. Y.; Kim, Y. D.; Park, H. K.; Park, H. S.

    2016-12-01

    The fast neutron rates are compared at the site of the NEOS (Neutrino Experiment Oscillation Short baseline) experiment, a short-baseline neutrino experiment located in a tendon gallery of a commercial nuclear power plant using a 0.78-liter liquid scintillator detector. A pulse shape discrimination technique is used to identify neutron signals. The measurements are performed during the nuclear reactor-on and -off periods, and the fast neutron rates are found to be consistent with each other. The fast neutron rate is also measured at an overground site with a negligible overburden and is found to be 100 times higher than that at the site of the NEOS experiment.

  5. [Fast neutron cross section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Knoll, G.F.

    1992-10-26

    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.

  6. Measurement of Fast Neutron Rate for NEOS Experiment

    CERN Document Server

    Ko, Y J; Han, B Y; Jang, C H; Jeon, E J; Joo, K K; Kim, B R; Kim, H J; Kim, H S; Kim, Y D; Lee, Jaison; Lee, J Y; Lee, M H; Oh, Y M; Park, H K; Park, H S; Park, K S; Seo, K M; Siyeon, Kim; Sun, G M

    2016-01-01

    The fast neutron rate is measured at the site of NEOS experiment, a short baseline neutrino experiment located in a tendon gallery of a commercial nuclear power plant, using a 0.78-liter liquid scintillator detector. A pulse shape discrimination technique is used to identify neutron signals. The measurements are performed during the nuclear reactor-on and off periods and found to be ~20 per day for both periods. The fast neutron rate is also measured at an overground site with a negligible overburden and is found to be ~100 times higher than that at the NEOS experiment site.

  7. C7LYC Scintillators and Fast Neutron Spectroscopy

    Science.gov (United States)

    Chowdhury, P.; Brown, T.; Doucet, E.; Lister, C. J.; Wilson, G. L.; D'Olympia, N.; Devlin, M.; Mosby, S.

    2016-09-01

    Cs2 LiYCl6 (CLYC) scintillators detect both gammas and neutrons with excellent pulse shape discrimination. At UML, fast neutron measurements with a 16-element 1''x1'' CLYC array show promise for low energy nuclear science. CLYC detects fast neutrons via the 35Cl (n,p) reaction (resolution UML. Results will be discussed in the context of constructing a C7LYC array at FRIB for reaction and decay spectroscopy of neutron-rich fragments. Supported by the NNSA Stewardship Science Academic Alliance Program under Grant DE-NA00013008.

  8. Superconducting High Resolution Fast-Neutron Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Hau, Ionel Dragos [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Superconducting high resolution fast-neutron calorimetric spectrometers based on 6LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, α) reactions with fast neutrons in 6Li and 10B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies kBT on the order of μeV that serve as signal carriers, resulting in an energy resolution ΔE ~ (kBT2C)1/2, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB2 absorber using thermal neutrons from a 252Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in 7Li. Fast-neutron spectra obtained with a 6Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the 6Li(n, α)3H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.

  9. Coiled transmission line pulse generators

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Kenneth Fox (Columbia, MO)

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  10. MPACT Fast Neutron Multiplicity System Design Concepts

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-01

    This report documents work performed by Idaho National Laboratory and the University of Michigan in fiscal year (FY) 2012 to examine design parameters related to the use of fast-neutron multiplicity counting for assaying plutonium for materials protection, accountancy, and control purposes. This project seeks to develop a new type of neutron-measurement-based plutonium assay instrument suited for assaying advanced fuel cycle materials. Some current-concept advanced fuels contain high concentrations of plutonium; some of these concept fuels also contain other fissionable actinides besides plutonium. Because of these attributes the neutron emission rates of these new fuels may be much higher, and more difficult to interpret, than measurements made of plutonium-only materials. Fast neutron multiplicity analysis is one approach for assaying these advanced nuclear fuels. Studies have been performed to assess the conceptual performance capabilities of a fast-neutron multiplicity counter for assaying plutonium. Comparisons have been made to evaluate the potential improvements and benefits of fast-neutron multiplicity analyses versus traditional thermal-neutron counting systems. Fast-neutron instrumentation, using for example an array of liquid scintillators such as EJ-309, have the potential to either a) significantly reduce assay measurement times versus traditional approaches, for comparable measurement precision values, b) significantly improve assay precision values, for measurement durations comparable to current-generation technology, or c) moderating improve both measurement precision and measurement durations versus current-generation technology. Using the MCNPX-PoliMi Monte Carlo simulation code, studies have been performed to assess the doubles-detection efficiency for a variety of counter layouts of cylindrical liquid scintillator detector cells over one, two, and three rows. Ignoring other considerations, the best detector design is the one with the most

  11. 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

  12. Fast Neutron Detector for Fusion Reactor KSTAR Using Stilbene Scintillator

    CERN Document Server

    Lee, Seung Kyu; Kim, Gi-Dong; Kim, Yong-Kyun

    2011-01-01

    Various neutron diagnostic tools are used in fusion reactors to evaluate different aspects of plasma performance, such as fusion power, power density, ion temperature, fast ion energy, and their spatial distributions. The stilbene scintillator has been proposed for use as a neutron diagnostic system to measure the characteristics of neutrons from the Korea Superconducting Tokamak Advanced Research (KSTAR) fusion reactor. Specially designed electronics are necessary to measure fast neutron spectra with high radiation from a gamma-ray background. The signals from neutrons and gamma-rays are discriminated by the digital charge pulse shape discrimination (PSD) method, which uses total to partial charge ratio analysis. The signals are digitized by a flash analog-to-digital convertor (FADC). To evaluate the performance of the fabricated stilbene neutron diagnostic system, the efficiency of 10 mm soft-iron magnetic shielding and the detection efficiency of fast neutrons were tested experimentally using a 252Cf neutr...

  13. A Fast Neutron Spectrometer for Underground Science

    Science.gov (United States)

    Langford, Thomas; Beise, Elizabeth; Breuer, Herbert; Erwin, Dylan; Bass, Christopher; Heimbach, Craig; Nico, Jeff

    2010-02-01

    The characterization of the fast neutron fluence has become a critical issue for experiments that require extreme low-background environments, such as neutrino-less double-beta decay, dark matter searches, and solar neutrino experiments. In such experiments, fast neutrons may be the dominant and a potentially irreducible background, thus necessitating precise information about the fast neutron fluence and energy spectrum. The most reasonable approach to addressing the problem is through the complete characterization of the neutrons through both site-specific measurement and benchmarking of simulation codes. We will discuss the progress toward the development of a large-volume, segmented detector consisting of plastic scintillator and ^3He proportional counters. The detector will be placed in an underground environment to measure the fast neutron flux and energy spectrum. A prototype detector has been constructed and testing is in progress. We will discuss the status of the project and present data from the prototype detector. )

  14. [Fast neutron cross section measurements]. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Knoll, G.F.

    1992-10-26

    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.

  15. 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.)

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

    Science.gov (United States)

    Weiss, C.; Frais-Kölbl, H.; Griesmayer, E.; Kavrigin, P.

    2016-09-01

    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 12 C and 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 13C(n, α)10Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the 12C(n, α)9Be 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.

  17. The Use of Fast Neutron Detection for Materials Accountability

    Science.gov (United States)

    Nakae, L. F.; Chapline, G. F.; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Ouedraogo, S. A.; Prasad, M. K.; Sheets, S. A.; Snyderman, N. J.; Verbeke, J. M.; Wurtz, R. E.

    2014-02-01

    For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) inherent in man-portable systems. Historically, thermal neutron detectors (mainly 3He) were used, taking advantage of the high thermal neutron interaction cross-sections, but more recently we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics that respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production timescales of fission and neutron-induced fission are preserved and measured instead of being lost in the thermalization of thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of high efficiency counters. Faster detector response times and sensitivity to neutron momentum show promise in measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed neutron sources (e.g., Pu oxide or Mixed Cm and Pu). Here we report on measured results with our existing liquid scintillator array and promote the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator becomes competitive and even surpasses the precision of 3He counters measuring correlated pairs in modest (kg) samples of plutonium.

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

    Science.gov (United States)

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

    2011-06-01

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

  19. Capture-Gated Fast Neutron Spectroscopy

    Science.gov (United States)

    Mumm, H. P.; Abdurashitov, J. N.; Beise, E. J.; Breuer, H.; Gavrin, V. N.; Heimbach, C. R.; Langford, T. J.; Mendenhall, M.; Nico, J. S.; Shikhin, A. A.

    2015-10-01

    We present recent developments in fast neutron detection using segmented spectrometers based on the principle of capture-gating. Our approach employs an organic scintillator to detect fast neutrons through their recoil interaction with protons in the scintillator. The neutrons that thermalize and are captured produce a signal indicating that the event was due to a neutron recoil and that the full energy of the neutron was deposited. The delayed neutron capture also serves to discriminate against uncorrelated background events. The segmentation permits reconstruction of the initial neutron energy despite the nonlinear response of the scintillator. We have constructed spectrometers using both He-3 proportional counters and Li-6 doping as capture agents in plastic and liquid organic scintillators. We discuss the operation of the spectrometers for the measurement of low levels of fast neutrons for several applications, including the detection of very low-activity neutron sources and the characterization of the flux and spectrum of fast neutrons at the Earth's surface and in the underground environment.

  20. Comparison of Fast Neutron Detector Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Stange, Sy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mckigney, Edward Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-09

    This report documents the work performed for the Department of Homeland Security Domestic Nuclear Detection O ce as the project Fast Neutron Detection Evaluation under contract HSHQDC-14-X-00022. This study was performed as a follow-on to the project Study of Fast Neutron Signatures and Measurement Techniques for SNM Detection - DNDO CFP11-100 STA-01. That work compared various detector technologies in a portal monitor con guration, focusing on a comparison between a number of fast neutron detection techniques and two standard thermal neutron detection technologies. The conclusions of the earlier work are contained in the report Comparison of Fast Neutron Detector Technologies. This work is designed to address questions raised about assumptions underlying the models built for the earlier project. To that end, liquid scintillators of two di erent sizes{ one a commercial, o -the-shelf (COTS) model of standard dimensions and the other a large, planer module{were characterized at Los Alamos National Laboratory. The results of those measurements were combined with the results of the earlier models to gain a more complete picture of the performance of liquid scintillator as a portal monitor technology.

  1. Fast-Neutron Survey With Compact Plastic Scintillation Detectors.

    Science.gov (United States)

    Preston, Rhys M; Tickner, James R

    2017-07-01

    With the rise of the Silicon Photomultiplier (SiPM), it is now practical to build compact scintillation detectors well suited to portable use. A prototype survey meter for fast-neutrons and gamma-rays, based around an EJ-299-34 plastic scintillator with SiPM readout, has been developed and tested. A custom digital pulse processor was used to perform pulse shape discrimination on-the-fly. Ambient dose equivalent H*(10) was calculated by means of two energy-dependent 'G-functions'. The sensitivity was calculated to be between 0.10 and 0.22 cps/(µSv/hr) for fast-neutrons with energies above 2.5 MeV. The prototype was used to survey various laboratory radiation fields, with the readings compared with commercial survey meters. The high sensitivity and lightweight nature of this detector makes it promising for rapid survey of the mixed neutron/gamma-ray fields encountered in industry and homeland security. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. MCNPX Monte Carlo simulations of particle transport in SiC semiconductor detectors of fast neutrons

    Science.gov (United States)

    Sedlačková, K.; Zat'ko, B.; Šagátová, A.; Pavlovič, M.; Nečas, V.; Stacho, M.

    2014-05-01

    The aim of this paper was to investigate particle transport properties of a fast neutron detector based on silicon carbide. MCNPX (Monte Carlo N-Particle eXtended) code was used in our study because it allows seamless particle transport, thus not only interacting neutrons can be inspected but also secondary particles can be banked for subsequent transport. Modelling of the fast-neutron response of a SiC detector was carried out for fast neutrons produced by 239Pu-Be source with the mean energy of about 4.3 MeV. Using the MCNPX code, the following quantities have been calculated: secondary particle flux densities, reaction rates of elastic/inelastic scattering and other nuclear reactions, distribution of residual ions, deposited energy and energy distribution of pulses. The values of reaction rates calculated for different types of reactions and resulting energy deposition values showed that the incident neutrons transfer part of the carried energy predominantly via elastic scattering on silicon and carbon atoms. Other fast-neutron induced reactions include inelastic scattering and nuclear reactions followed by production of α-particles and protons. Silicon and carbon recoil atoms, α-particles and protons are charged particles which contribute to the detector response. It was demonstrated that although the bare SiC material can register fast neutrons directly, its detection efficiency can be enlarged if it is covered by an appropriate conversion layer. Comparison of the simulation results with experimental data was successfully accomplished.

  3. 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.

  4. Fast neutron activation dosimetry with TLDS

    Energy Technology Data Exchange (ETDEWEB)

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

    1975-01-01

    Fast neutron activation using threshold reactions is the only neutron dosimetry method which offers complete discrimination against gamma-rays and preserves some information about the neutron energy. Conventional activation foil technique requires sensitive radiation detectors to count the decay of the neutron induced activity. For extensive measurements at low neutron fluences, vast outlays of counting equipment are required. TL dosimeters are inexpensive, extremely sensitive radiation detectors. The work of Mayhugh et al. (Proc. Third Int. Conf. on Luminescence Dosimetry, Riso Report 249, 1040, (1971)) showed that CaSO/sub 4/: DyTLDs could be used to measure the integrated dose from the decay of the radioactivity produced in the dosimeters by exposure to thermal neutrons. This neatly combines the activation detector and counter functions in one solid state device. This work has been expanded to fast neutron exposures and other TL phosphors. The reactions /sup 19/F(n, 2n)/sup 18/F, /sup 32/S(n,p)/sup 32/P, /sup 24/Mg(n,p)/sup 24/, and /sup 64/Zn(n,p)/sup 64/Cu were found useful for fast neutron activation in commercial TLDs. As each TLD is its own integrating decay particle counter, many activation measurements can be made at the same time. The subsequent readings of the TL signals can be done serially after the induced radioactivity has decayed, using only one TL reader. The neutron detection sensitivity is limited mainly by the number statistics of the neutron activations. The precision of the neutron measurement is within a factor of two of conventional foil activation for comparable mass detectors. Commercially available TLDs can measure neutron fluences of 10/sup 9/n/cm/sup 2/ with 10 percent precision.

  5. 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.

  6. Compositional terranes on Mercury: Information from fast neutrons

    Science.gov (United States)

    Lawrence, David J.; Peplowski, Patrick N.; Beck, Andrew W.; Feldman, William C.; Frank, Elizabeth A.; McCoy, Timothy J.; Nittler, Larry R.; Solomon, Sean C.

    2017-01-01

    We report measurements of the flux of fast neutrons at Mercury from 20ºS to the north pole. On the basis of neutron transport simulations and remotely sensed elemental compositions, cosmic-ray-induced fast neutrons are shown to provide a measure of average atomic mass, , a result consistent with earlier studies of the Moon and Vesta. The dynamic range of fast neutron flux at Mercury is 3%, which is smaller than the fast-neutron dynamic ranges of 30% and 6% at the Moon and Vesta, respectively. Fast-neutron data delineate compositional terranes on Mercury that are complementary to those identified with X-ray, gamma-ray, and slow-neutron data. Fast neutron measurements confirm the presence of a region with high , relative to the mean for the planet, that coincides with the previously identified high-Mg region and reveal the existence of at least two additional compositional terranes: a low- region within the northern smooth plains and a high- region near the equator centered near 90ºE longitude. Comparison of the fast-neutron map with elemental composition maps show that variations predicted from the combined element maps are not consistent with the measured variations in fast-neutron flux. This lack of consistency could be due to incomplete coverage for some elements or uncertainties in the interpretations of compositional and neutron data. Currently available data and analyses do not provide sufficient constraints to resolve these differences.

  7. Research of Fast Neutron Radiation Effect on Rats

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to research the fast neutron radiation effect on rats,the 8 weeks Wistar male rats were wholly irradiated by 14 MeV fast neutron with 5 Gy. In the experiment,the rats were divided into normal and irradiation group, and killed

  8. Current Amplification Characteristics of BJT on Fast Neutron Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sung Ho; Sun, Gwang Min; Baek, Hani [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    BJT (Bipolar Junction Transistor) is a three-terminal device with an important feature in that the current through two terminals can be controlled by small changes we make in the current or voltage at the third terminal. This control feature allows us to amplify small AC signals or to switch the device from an on state and off state and back. Fast neutron irradiation incurs lattice damage in bulk Si. The recombination rate of minority carriers and register are increased by the lattice damage. This study will investigate the current amplification characteristics of a pnp Si BJT through fast neutron irradiation experiments. In this paper, the current amplification characteristics of a pnp Si BJT were investigated for fast neutron irradiation. The experimental results show that base-tocollector current amplification ratio is decreased with an increase in the fast neutron irradiation. These indicate that the lattice damage caused by fast neutron irradiation increases the recombination rate of minority carriers and resistor.

  9. Photon and fast neutron dosimetry using aluminium oxide thermoluminescence dosemeters.

    Science.gov (United States)

    Santos, J P; Fernandes, A C; Gonçalves, I C; Marques, J G; Carvalho, A F; Santos, L; Cardoso, J; Osvay, M

    2006-01-01

    Al(2)O(3):Mg,Y thermoluminescence (TL) dosemeters were used to measure photon and fast neutron doses in a fast neutron beam recently implemented at the Portuguese Research Reactor, Nuclear and Technological Institute, Portugal. The activation of Al(2)O(3):Mg,Y by fast neutrons provides information about the fast neutron component by measuring the activity of the reaction products and the self-induced TL signal. Additionally, the first TL reading after irradiation determines the photon dose. The elemental composition of the dosemeters was determined by instrumental neutron activation analysis and by particle induced X-ray emission. Results demonstrate that Al(2)O(3):Mg,Y is an adequate material to discriminate photon and fast neutron fields for reactor dosimetry purposes.

  10. Study on fast neutron dosimetry using electrochemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.T. (National Tsing-Hua Univ., Hsin-Chu, Taiwan); Su, S.J.

    1981-03-01

    Registration of fast-neutron-induced-recoil tracks by electrochemical etching technique as applied to polycarbonate foils has provided a simple, sensitive, and inexpensive means of fast neutron personnel dosimetry. Etching parameters are carefully discussed and it was discovered a new method of stirring in KOH aqueous solution offered considerable improvement over previous procedures. Applied frequency can be decreased from 2kHz to regular 60Hz. The sensitivity of fast neutrons is 0.12-0.18 tracks/cm/sup 2/ per mrem with standard deviation of +/- 20.2%.

  11. Methods and Instruments for Fast Neutron Detection

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Reeder, Paul L.; Cooper, Matthew W.; McCormick, Kathleen R.; Peurrung, Anthony J.; Warren, Glen A.

    2005-05-01

    Pacific Northwest National Laboratory evaluated the performance of a large-area (~0.7 m2) plastic scintillator time-of-flight (TOF) sensor for direct detection of fast neutrons. This type of sensor is a readily area-scalable technology that provides broad-area geometrical coverage at a reasonably low cost. It can yield intrinsic detection efficiencies that compare favorably with moderator-based detection methods. The timing resolution achievable should permit substantially more precise time windowing of return neutron flux than would otherwise be possible with moderated detectors. The energy-deposition threshold imposed on each scintillator contributing to the event-definition trigger in a TOF system can be set to blind the sensor to direct emission from the neutron generator. The primary technical challenge addressed in the project was to understand the capabilities of a neutron TOF sensor in the limit of large scintillator area and small scintillator separation, a size regime in which the neutral particle’s flight path between the two scintillators is not tightly constrained.

  12. Removal cross sections and total mass attenuation coefficients of fast neutrons and gamma rays for steel

    CERN Document Server

    Elsayed, A A

    2003-01-01

    The present work deals with the study of the attenuation properties and determination of the cross sections of fast neutrons and gamma rays for structure steel used in different applications in nuclear power plants, particle accelerators, research reactors and different radiation attenuation fields. Investigation has been performed by measuring the transmitted fast neutron and gamma ray spectra behind cylindrical samples of steel (rho=7.87 gem sup - sup 3) of different thicknesses. A reactor collimated beam and neutron - gamma spectrometer with stiblbene scintillator were used for measurements. The pluse shape disriminate technique based on zero cross over method was used to discriminate between neutron and gamma ray pulses. Effective removal cross-section (sigma sub R) and total mass attenuation coefficient (mu) of neureons and gamma rays have been achieved using the attenuation relations. Microscopic removal cross sections sigma sup 9 sup 8 and mass removal cross sections sigma sub R sub / subrho of fast ne...

  13. Development of imaging techniques for fast neutron radiography in Japan

    CERN Document Server

    Fujine, S; Yoshii, K; Kamata, M; Tamaki, M; Ohkubo, K; Ikeda, Y; Kobayashi, H

    1999-01-01

    Neutron radiography with fast neutron beams (FNR) has been studied at the fast neutron source reactor 'YAYOI' of the University of Tokyo since 1986. Imaging techniques for FNR have been developed for CR-39 track-etch detector, electronic imaging system (television method), direct film method, imaging plate and also fast and thermal neutron concurrent imaging method. The review of FNR imaging techniques and some applications are reported in this paper.

  14. 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.

  15. Some Applications of Fast Neutron Activation Analysis of Oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Owrang, Farshid

    2003-07-01

    In this thesis we focus on applications of neutron activation of oxygen for several purposes: A) measuring the water level in a laboratory tank, B) measuring the water flow in a pipe system set-up, C) analysing the oxygen in combustion products formed in a modern gasoline SI engine, and D) measuring on-line the amount of oxygen in bulk liquids. A) Water level measurements. The purpose of this work was to perform radiation based water level measurements, aimed at nuclear reactor vessels, on a laboratory scale. A laboratory water tank was irradiated by fast neutrons from a neutron generator. The water was activated at different water levels and the water level was decreased. The produced gamma radiation was measured using two detectors at different heights. The results showed that the method is suitable for measurement of water level and that a relatively small experimental set-up can be used for developing methods for water level measurements in real boiling water reactors based on activated oxygen in the water. B) Water flows in pipe. The goal in this work was to investigate the asymmetric distribution of activity in flow measurements with pulsed neutron activation (PNA) in a laboratory piping system. Earlier investigations had shown a discrepancy between the measured velocity of the activated water by PNA and the true mean velocity in the pipe. This discrepancy decreased with larger distances from the activation point. It was speculated that the induced activity in the pipe did not distribute homogeneously. With inhomogeneous radial distribution of activity in combination with a velocity profile in the pipe, the activated water may not have the same velocity as the mean velocity of water in the pipe. To study this phenomenon, a water-soluble colour was injected into a transparent pipe for simulation of the transport of the activated water. The radial concentration of the colour, at different distances from the activation point, was determined. The result

  16. 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

  17. Recent Developments In Fast Neutron Detection And Multiplicity Counting With Verification With Liquid Scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Nakae, L; Chapline, G; Glenn, A; Kerr, P; Kim, K; Ouedraogo, S; Prasad, M; Sheets, S; Snyderman, N; Verbeke, J; Wurtz, R

    2011-09-30

    For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, we used thermal neutron detectors (mainly {sup 3}He), taking advantage of the high thermal neutron interaction cross-sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics which respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production time-scales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources like Cm and Pu. We report on measured results with our existing liquid scintillator array, and progress on the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator detectors become competitive and even surpass the precision of {sup 3}He-based counters measuring correlated pairs in modest (kg) samples of plutonium.

  18. Recent Developments in Fast Neutron Detection and Multiplicity Counting with Liquid Scintillator

    Science.gov (United States)

    Nakae, L. F.; Chapline, G. F.; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Ouedraogo, S. A.; Prasad, M. K.; Sheets, S. A.; Snyderman, N. J.; Verbeke, J. M.; Wurtz, R. E.

    2011-12-01

    For many years, LLNL researchers have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of the techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, thermal neutron detectors (mainly 3He) were used, taking advantage of the high thermal neutron interaction cross sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics that respond over 1000 times faster (ns versus tens of μs) than thermal neutron detectors. Fast neutron detection offers considerable advantages since the inherent ns production timescales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources like Cm and Pu. We report on measured results with our existing liquid scintillator array and progress on the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator detectors become competitive and even surpass the precision of 3He-based counters measuring correlated pairs in modest (kg) samples of plutonium.

  19. Gram-scale Plutonium Samples Measured by Experimental Device of Four Detectors Well-type Fast Neutron Coincidence Measurement

    Institute of Scientific and Technical Information of China (English)

    LIU; Guo-rong; LIANG; Qing-lei; LI; Jing-huai; LI; An-li

    2013-01-01

    Experimental device of four detectors well-type fast neutron coincidence measurement(see Fig.1)consists of four?127 mm×50.8 mm BC501A liquid scintillation detectors,DC271A digitizer and other circuits.Application program simultaneously acquires the waveform of each pulse output from each detector,and identifies each pulse from neutron or?particle by offline model,and gets their arrival timing.

  20. Spectrometry and dosimetry of fast neutrons using pin diode detectors

    Energy Technology Data Exchange (ETDEWEB)

    Zaki Dizaji, H., E-mail: hz.dizaji@znu.ac.ir [Physics Department, Faculty of Science, Zanjan University, Zanjan (Iran, Islamic Republic of); Kakavand, T. [Physics Department, Faculty of Science, International Imam Khomeini University, Qazvin (Iran, Islamic Republic of); Abbasi Davani, F. [Radiation Application Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2014-03-21

    Elastic scattering of light nuclei, especially hydrogen, is widely used for detection of fast neutrons. Semiconductor devices based on silicon detectors are frequently used for different radiation detections. In this work, a neutron spectrometer consisting of a pin diode coupled with a polyethylene converter and aluminum degrader layers has been developed. Aluminum layers are used as discriminators of different neutron energies for detectors. The response of the converter–degrader–pin diode configuration, the optimum thickness of the converter and the degrader layers have been extracted using MCNP and SRIM simulation codes. The possibility of using this type of detector for fast neutron spectrometry and dosimetry has been investigated. A fairly good agreement was seen between neutron energy spectrum and dose obtained from our configurations and these specifications from an {sup 241}Am–Be neutron source. - Highlights: • Silicon pin diodes are applied to the fast neutron detection. • The technique of converter degrader pin diode is used for spectrometry of fast neutrons. • The method is used for dosimetry of fast neutron.

  1. Characterization methods for an accelerator based fast-neutron facility

    Science.gov (United States)

    Franklyn, C.; Daniels, G. C.

    2012-02-01

    A fast neutron facility provides a number of complexities in both detection and shielding, the latter arising not only due to uncertainty in the behaviour of the scattered radiation (neutron and gamma-rays) from a fast neutron source, but also on shielding requirements that have to take into account internal and external factors, such as dose limitations, space availability for implementing bulky shielding and secondary interactions of the radiation with materials. This has possible influence on experimental measurements with a low signal to noise ratio. This paper reports on some of the investigations performed at a RFQ accelerator facility generating > 1011 neutrons per second with energies up to 14 MeV, which are used to perform fast neutron radiography studies. Areas highlighted are the neutron cross section libraries, where important data needs to be reviewed or updated.

  2. Characterization of a GEM-based fast neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Esposito, B., E-mail: basilio.esposito@enea.it [Associazione Euratom-ENEA sulla Fusione, Via E. Fermi, 45, I-00044 Frascati, Roma (Italy); Marocco, D.; Villari, R. [Associazione Euratom-ENEA sulla Fusione, Via E. Fermi, 45, I-00044 Frascati, Roma (Italy); Murtas, F. [Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, Via E. Fermi, 40, I-00044 Frascati, Roma (Italy); Rodionov, R. [SRC RF TRINITI Troitsk, Moscow (Russian Federation)

    2014-03-21

    The neutron efficiency of a Gas Electron Multiplier (GEM)-based detector designed for fast neutron measurements in fusion devices was determined through the combined use of Monte Carlo (MCNPX) calculations and analysis of deuterium–deuterium and deuterium–tritium neutron irradiation experiments. The detector, characterized by a triple GEM structure flushed with a Ar/CO{sub 2}/CF{sub 4} – 45/15/40 gas mixture, features a digital read-out system and has two sub-units for the detection of 2.5+14 MeV neutrons and 14 MeV neutrons (U{sub DD} and U{sub DT}, respectively). The pulse height spectra (PHS) determined from the curves of experimental efficiency as a function of the detector's high voltage (HV) and the MCNPX-simulated PHS were compared using a fitting routine that finds the best match between the experimental and simulated PHS by assuming a parametric model for the relation between HV (that determines the detector's gain) and the energy deposited in the gas. This led to express the experimental neutron efficiency as a function of the discrimination level set on the deposited energy (energy threshold). The detector sensitivity to γ-rays was also analyzed and the operational range in which the γ-ray contribution to the signal is not negligible was determined. It is found that this detector can reach a maximum neutron efficiency of ∼1×10{sup −3} counts/n at 2.5 MeV (U{sub DD} sub-unit) and of ∼4×10{sup −3} counts/n at 14 MeV (U{sub DT} and U{sub DD} sub-units)

  3. [Fast neutrons in the treatment of soft tissue sarcomas].

    Science.gov (United States)

    Chernichenko, V A; Tolstopiatov, B A; Monich, A Iu; Konovalenko, V F; Galakhin, K A; Palivets, A Iu; Vorona, A M

    1990-01-01

    Results of treatment of 101 cases of soft tissue sarcoma are presented in the paper. Preoperative irradiation technique and radical program of treatment are described. Combined radiation and surgical treatment was given to 45 patients whereas conservative--to 56. Sixty-three cases received adjuvant combination chemotherapy. Response and three-year survival rates were compared to those in control group treated by photons. The results observed in patients of combined and conservative treatment groups who had been irradiated with fast neutrons proved significantly better than in controls. These data suggest vistas in application of fast neutron irradiation for the treatment of soft tissue sarcomas.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. TRANSMISSION BEHAVIOR OF MUD-PRESSURE PULSE ALONG WELL BORE

    Institute of Scientific and Technical Information of China (English)

    LIU Xiu-shan; LI Bo; YUE Yu-quan

    2007-01-01

    In oil and gas industry, mud-pulse telemetry has been widely used to obtain directional data, drilling parameters, formation evaluation data and safety data, etc. Generally, the drilling mud in most current models was considered to be a single-phase fluid through which the mud pulses travel, despite the fact that the drilling mud is composed of two or more phases. In this article, a multiphase flow formula was proposed to calculate the mud-pulse velocity as mud solids and free-gas content change, and a mathematical model was put forward to simulate the dynamic-transmission behavior of the mud-pressure pulse or waves. Compared to conventional methods, the present model provides more accurate mud-pulse attenuation, and the dynamic-transmission behavior of drilling-mud pulses along well bores can also be easily examined. The model is valuable in improving the existing mud-pulse systems and developing new drilling-mud pulse systems.

  6. Fast neutrons set the pace. [Radiobiological investigations with fast neutrons at the CSIR cyclotron in Pretoria

    Energy Technology Data Exchange (ETDEWEB)

    Hough, J.H.; Slabbert, J.P. (Council for Scientific and Industrial Research, Pretoria (South Africa). National Accelerator Centre)

    1985-01-01

    Radiobiological investigations with fast neutrons have been initiated at the CSIR cyclotron in Pretoria. It was proposed some years ago to create a neutron therapy facility using the CSIR cyclotron. Neutrons are classified as high linear energy transfer (LET) particles. Biological damage occurring in tissue is a direct function of the LET of the incident radiation. To quantify the biological effects of different types of radiation on mammalian cells, several procedures and concepts have evolved from radiobiological research. Probably the most significant laboratory techniques developed, were the derivation of cell survival curves which are obtained by determining the number of cell colonies that have survived a certain radiation dose. A semi-logarithmic plot of surviving fraction versus the absorbed dose yields the survival curve. Dose modifying factors such as the relative biological effectiveness (RBE) of the radiation can be quantified in terms of this relationship. A radiobiological programme has to be undertaken before patients can receive neutron therapy at the CSIR cyclotron. The article is a discussion of this programme.

  7. 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)

  8. 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

  9. RBE of fast neutrons for apoptosis in mouse thymocytes

    NARCIS (Netherlands)

    Warenius, HM; Down, JD

    1995-01-01

    We compared apoptosis in mouse thymocytes following exposure to low doses of high linear energy transfer (LET), 625-MeV (p-->Be+) fast neutrons and low LET, 4-MeV photons by flow cytometric analysis of hypodiploid cells. The incidence of apoptotic cell death rose steeply at very low radiation doses

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

    Science.gov (United States)

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

    2011-05-01

    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 1.03×10(10)-4.89×10(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.

  11. Rotational swashplate pulse continuously variable transmission based on helical gear axial meshing transmission

    Science.gov (United States)

    Sun, Jiandong; Fu, Wenyu; Lei, Hong; Tian, E.; Liu, Ziping

    2012-11-01

    The current research on pulse continuously variable transmission(CVT) is mainly focused on reducing the pulse degree and making pulse degrees a constant value. Current research mainly confined to find out new design parameters by using the method of optimization, and reduce the pulse degree of pulse CVT and its range of variation. But the fact is that the reduction of the pulse degree is not significant. This article presents a new structure of mechanical pulse CVT—the rotational swashplate pulse CVT with driven by helical gear axial meshing. This transmission is simple and compact in structure and low in pulsatile rate (it adopts 6 guide rods), and the pulsatile degree is irrelevant to the transmission ratio. Theoretically, pulsatile rate could be reduced to zero if appropriate curved surface of the swashplate is used. Compared with the connecting rod pulse CVT, the present structure uses helical gear mechanism as transmission part and it avoids unbalanced inertial force in the former model. This paper analyzes the principle of driving of this transmission, presents its mechanical structure, and discusses its motion characteristics. Experimental prototype of this type of CVT has been manufactured. Tests for the transmission efficiency(when the rotational speed of the output shaft is the maximum) and the angular velocity of the output shaft have been carried out, and data have been analyzed. The experimental results show that the speed of the output shaft for the experimental prototype is slightly lower than the theoretical value, and the transmission efficiency of the experimental prototype is about 70%. The pulse degree of the CVT discussed in this paper is less than the existing pulse CVT of other types, and it is irrelevant to the transmission ratio of the CVT. The research provides the new idea to the CVT study.

  12. Accelerated oxygen precipitation in fast neutron irradiated Czochralski silicon

    Institute of Scientific and Technical Information of China (English)

    Ma Qiao-Yun; Li Yang-Xian; Chen Gui-Feng; Yang Shuai; Liu Li-Li; Niu Ping-Juan; Chen Dong-Feng; Li Hong-Tao

    2005-01-01

    Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon (CZ-Si) by infrared absorption spectrum and the optical microscopy. It is found that the fast neutron irradiation greatly accelerates the oxygen precipitation that leads to a sharp decrease of the interstitial oxygen with the annealing time. At room temperature (RT), the 1107cm-1 infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. At low temperature, the infrared absorption peaks appear at 1078cm-1, 1096cm-1, and 1182cm-1, related to different shapes of the oxygen precipitates. The bulk microdefects,including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation.

  13. A novel liquid-Xenon detector concept for combined fast-neutrons and gamma imaging and spectroscopy

    Science.gov (United States)

    Breskin, A.; Israelashvili, I.; Cortesi, M.; Arazi, L.; Shchemelinin, S.; Chechik, R.; Dangendorf, V.; Bromberger, B.; Vartsky, D.

    2012-06-01

    A new detector concept is presented for combined imaging and spectroscopy of fast-neutrons and gamma rays. It comprises a liquid-Xenon (LXe) converter and scintillator coupled to a UV-sensitive gaseous imaging photomultiplier (GPM). Radiation imaging is obtained by localization of the scintillation-light from LXe with the position-sensitive GPM. The latter comprises a cascade of Thick Gas Electron Multipliers (THGEM), where the first element is coated with a CsI UV-photocathode. We present the concept and provide first model-simulation results of the processes involved and the expected performances of a detector having a LXe-filled capillaries converter. The new detector concept has potential applications in combined fast-neutron and gamma-ray screening of hidden explosives and fissile materials with pulsed sources.

  14. Energy-dispersive study of the interactions of fast neutrons with matter

    CERN Document Server

    Altstadt, E; Eckert, S; Freiesleben, H; Galindo, V; Grosse, E; Naumann, B; Weiss, F P

    2003-01-01

    The construction and the first use of a compact time-of-flight system for the energy-dispersive study of the interaction of fast neutrons with materials are content of a network project of the Research Center Rossendorf, to which also the Technical University Dresden contributes in the framework of a common DFG project. The planned time-of-flight experiments with pulsed neutrons will be performed at the radiation source ELBE. First results on the development of a neutron-production target are presented. By means of radiation-transport and finite-element programs the distributions of the energy deposition of the used pulsed electron beam of the radiation source ELBE and the temperature in the neutron radiator as well as the expected particle spectra and fluxes at the measurement place were calculated. Considerations on the development of a beam catcher are discussed.

  15. Final Report on Actinide Glass Scintillators for Fast Neutron Detection

    Energy Technology Data Exchange (ETDEWEB)

    Bliss, Mary; Stave, Jean A.

    2012-10-01

    This is the final report of an experimental investigation of actinide glass scintillators for fast-neutron detection. It covers work performed during FY2012. This supplements a previous report, PNNL-20854 “Initial Characterization of Thorium-loaded Glasses for Fast Neutron Detection” (October 2011). The work in FY2012 was done with funding remaining from FY2011. As noted in PNNL-20854, the glasses tested prior to July 2011 were erroneously identified as scintillators. The decision was then made to start from “scratch” with a literature survey and some test melts with a non-radioactive glass composition that could later be fabricated with select actinides, most likely thorium. The normal stand-in for thorium in radioactive waste glasses is cerium in the same oxidation state. Since cerium in the 3+ state is used as the light emitter in many scintillating glasses, the next most common substitute was used: hafnium. Three hafnium glasses were melted. Two melts were colored amber and a third was clear. It barely scintillated when exposed to alpha particles. The uses and applications for a scintillating fast neutron detector are important enough that the search for such a material should not be totally abandoned. This current effort focused on actinides that have very high neutron capture energy releases but low neutron capture cross sections. This results in very long counting times and poor signal to noise when working with sealed sources. These materials are best for high flux applications and access to neutron generators or reactors would enable better test scenarios. The total energy of the neutron capture reaction is not the only factor to focus on in isotope selection. Many neutron capture reactions result in energetic gamma rays that require large volumes or high densities to detect. If the scintillator is to separate neutrons from gamma rays, the capture reactions should produce heavy particles and few gamma rays. This would improve the detection of a

  16. 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

  17. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Mohamed H. [Nuclear and Radiation Engineering Department, Alexandria University, Alexandria 21544 (Egypt)], E-mail: mhmheg@yahoo.com

    2009-08-01

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

  19. nGEM fast neutron detectors for beam diagnostics

    Science.gov (United States)

    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.

    2013-08-01

    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 (σx=14.35 mm, σy=15.75 mm), nGEM counting efficiency (around 10-4 for 3 MeV

  20. Ultradian corticosterone pulses balance glutamatergic transmission and synaptic plasticity.

    Science.gov (United States)

    Sarabdjitsingh, Ratna Angela; Jezequel, Julie; Pasricha, Natasha; Mikasova, Lenka; Kerkhofs, Amber; Karst, Henk; Groc, Laurent; Joëls, Marian

    2014-09-30

    The rodent adrenal hormone corticosterone (CORT) reaches the brain in hourly ultradian pulses, with a steep rise in amplitude before awakening. The impact of a single CORT pulse on glutamatergic transmission is well documented, but it remains poorly understood how consecutive pulses impact on glutamate receptor trafficking and synaptic plasticity. By using high-resolution imaging and electrophysiological approaches, we report that a single pulse of CORT to hippocampal networks causes synaptic enrichment of glutamate receptors and increased responses to spontaneously released glutamatergic vesicles, collectively abrogating the ability to subsequently induce synaptic long-term potentiation. Strikingly, a second pulse of CORT one hour after the first--mimicking ultradian pulses--completely normalizes all aspects of glutamate transmission investigated, restoring the plastic range of the synapse. The effect of the second pulse is precisely timed and depends on a nongenomic glucocorticoid receptor-dependent pathway. This normalizing effect through a sequence of CORT pulses--as seen around awakening--may ensure that hippocampal glutamatergic synapses remain fully responsive and able to encode new stress-related information when daily activities start.

  1. First measurement of low intensity fast neutron background from rock at the Boulby Underground Laboratory

    CERN Document Server

    Tziaferi, E; Kudryavtsev, V A; Lerner, R; Lightfoot, P K; Paling, S M; Robinson, M; Spooner, N J C

    2006-01-01

    A technique to measure low intensity fast neutron flux has been developed. The design, calibrations, procedure for data analysis and interpretation of the results are discussed in detail. The technique has been applied to measure the neutron background from rock at the Boulby Underground Laboratory, a site used for dark matter and other experiments, requiring shielding from cosmic ray muons. The experiment was performed using a liquid scintillation detector. A 6.1 litre volume stainless steel cell was filled with an in-house made liquid scintillator loaded with Gd to enhance neutron capture. A two-pulse signature (proton recoils followed by gammas from neutron capture) was used to identify the neutron events from much larger gamma background from PMTs. Suppression of gammas from the rock was achieved by surrounding the detector with high-purity lead and copper. Calibrations of the detector were performed with various gamma and neutron sources. Special care was taken to eliminate PMT afterpulses and correlated...

  2. Inelastic scattering of fast neutrons from $^{56}$Fe

    CERN Document Server

    Beyer, R; Hannaske, R; Junghans, A R; Massarczyk, R; Anders, M; Bemmerer, D; Ferrari, A; Kögler, T; Röder, M; Schmidt, K; Wagner, A

    2014-01-01

    Inelastic scattering of fast neutrons from $^{56}$Fe was studied at the photoneutron source nELBE. The neutron energies were determined on the basis of a timeof- flight measurement. Gamma-ray spectra were measured with a high-purity germanium detector. The total scattering cross sections deduced from the present experiment in an energy range from 0.8 to 9.6 MeV agree within 15% with earlier data and with predictions of the statistical-reaction code Talys.

  3. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-08-03

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

  5. Diode-Pumped Nanosecond Pulsed Laser with Pulse-Transmission-Mode Q-Switch

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; HUO Yu-Jing; HE Shu-Fang; FENG Li-Chun

    2001-01-01

    Q-switched pulses at 1.064μm with a peak power of 5.02kW and a pulse width of2.8ns were obtained which were pumped by a 1 W laser diode on the Nd:YVO4 microchip at the 1 kHz repetition rate. These values were achieved by combining the techniques of aconsto-optic Q-switching and electro-optic pulse-transmission-mode Q-switching. The temporal characteristics of the pulses were analysed numerically. The experimental results are shown to be in good agreement with theoretical predictions.

  6. A Capture-gated Fast Neutron Detection Method

    CERN Document Server

    Liu, Yi; Tai, Yang; Zhang, Zhi

    2016-01-01

    To address the problem of the shortage of neutron detectors used in radiation portal monitors (RPMs), caused by the 3He supply crisis, research on a cadmium-based capture-gated fast neutron detector is presented in this paper. The detector is composed of many 1 cm * 1 cm * 20 cm plastic scintillator cuboids covered by 0.1 mm thick film of cadmium. The detector uses cadmium to absorb thermal neutrons and produce capture gamma-rays to indicate the detection of neutrons, and uses plastic scintillator to moderate neutrons and register gamma-rays. This design removes the volume competing relationship in traditional 3He counter-based fast neutron detectors, which hinders enhancement of the neutron detection efficiency. Detection efficiency of 21.66 +- 1.22% has been achieved with a 40.4 cm * 40.4 cm * 20 cm overall detector volume. This detector can measure both neutrons and gamma-rays simultaneously. A small detector (20.2 cm * 20.2 cm * 20 cm) demonstrated a 3.3 % false alarm rate for a 252Cf source with a neutro...

  7. Cross-Section Measurements in the Fast Neutron Energy Range

    Science.gov (United States)

    Plompen, Arjan

    2006-04-01

    Generation IV focuses research for advanced nuclear reactors on six concepts. Three of these concepts, the lead, gas and sodium fast reactors (LFR, GFR and SFR) have fast neutron spectra, whereas a fourth, the super-critical water reactor (SCWR), can be configured to have a fast spectrum. Such fast neutron spectra are essential to meet the sustainability objective of GenIV. Nuclear data requirements for GenIV concepts will therefore emphasize the energy region from about 1 keV to 10 MeV. Here, the potential is illustrated of the GELINA neutron time-of-flight facility and the Van de Graaff laboratory at IRMM to measure the relevant nuclear data in this energy range: the total, capture, fission and inelastic-scattering cross sections. In particular, measurement results will be shown for lead and bismuth inelastic scattering for which the need was recently expressed in a quantitative way by Aliberti et al. for Accelerator Driven Systems. Even without completion of the quantitative assessment of the data needs for GenIV concepts at ANL it is clear that this particular effort is of relevance to LFR system studies.

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

    Science.gov (United States)

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

    2014-08-01

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

  9. Pulsed Power for a Dynamic Transmission Electron Microscope

    Energy Technology Data Exchange (ETDEWEB)

    dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

    2009-06-25

    Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

  10. Plasma absorption evidence via chirped pulse spectral transmission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jedrkiewicz, Ottavia, E-mail: ottavia.jedrkiewicz@ifn.cnr.it [Istituto di Fotonica e Nanotecnologie, CNR and CNISM UdR Como, Via Valleggio 11, I-22100 Como (Italy); Minardi, Stefano [Institute of Applied Physics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Couairon, Arnaud; Jukna, Vytautas [Centre de Physique Theorique, CNRS, Ecole Polytechnique, F-91128 Palaiseau (France); Selva, Marco; Di Trapani, Paolo [Dipartimento di Scienza e Alta Tecnologia, University of Insubria and CNISM UdR Como, Via Valleggio 11, I-22100 Como (Italy)

    2015-06-08

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  11. Roll-off factor dependence of Nyquist pulse transmission.

    Science.gov (United States)

    Harako, Koudai; Suzuki, Daiki; Hirooka, Toshihiko; Nakazawa, Masataka

    2016-09-19

    We evaluate the dependence of system performance on the roll-off factor, α, of a Nyquist pulse in a single-channel 1.28 Tbit/s-525 km transmission both experimentally and analytically. Low α values are preferable in terms of spectral efficiency and tolerance to chromatic dispersion and polarization-mode dispersion, while a strong overlap with neighboring symbols results in larger nonlinear impairments. On the other hand, a Nyquist pulse with high α values also suffers from nonlinearity due to higher peak power. As a result, we found experimentally that the optimum α value is 0.4~0.6, which agrees well with the analysis.

  12. The pilot experimental study of 14 MeV fast neutron digital radiography

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    14 MeV Fast neutrons has good penetrability and the 14 MeV fast neutron radiography can meet the need of Non-Destructive Test of the structure and lacuna of heavy-massive sample, whose shell is made of heavy metal and in which there are some hydrogen materials, and the study of fast neutron digital radiography just begins in China. By the use of a D-T accelerator, a digital imaging system made up of a fast neutron scintillation screen made of ZnS(Ag) and polypropylene, lens and a scientific grade CCD, the experimental study of fast neutron radiography has been done between 4.3×1010-6.8×1010 n/s of neutron yield. Some 14 MeV fast neutron digital radiographs have been gotten. According to experimental radiographs and their data, the performance of the fast neutron scintillation screen and the basic characters of 14 MeV fast neutron radiography are analyzed, and it is helpful for the further research.

  13. Genome resilience and prevalence of segmental duplications following fast neutron irradiation of soybean

    Science.gov (United States)

    Fast neutron radiation has been used as a mutagen to develop extensive mutant collections. However, the genome-wide structural consequences of fast neutron radiation are not well understood. Here, we examine the genome-wide structural variants observed among 264 soybean (Glycine max (L.) Merrill) pl...

  14. The pilot experimental study of 14 MeV fast neutron digital radiography

    Institute of Scientific and Technical Information of China (English)

    TANG Bin; ZHOU ChangGen; HUO HeYong; WU Yang; LIU Bin; LOU BenChao; SUN Yong

    2009-01-01

    14 MeV Fast neutrons has good penetrability and the 14 MeV fast neutron radiography can meet the need of Non-Destructive Test of the structure and lacuna of heavy-massive sample,whose shell is made of heavy metal and in which there are some hydrogen materials,and the study of fast neutron digital radiography just begins in China.By the use of a D-T accelerator,a digital imaging system made up of a fast neutron scintillation screen made of ZnS(Ag) and polypropylene,lens and a scientific grade CCD,the experimental study of fast neutron radiography has been done between 4.3×1010-6.8×1010 n/s of neutron yield.Some 14 MeV fast neutron digital radiographs have been gotten.According to ex-perimental radiographs and their data,the performance of the fast neutron scintillation screen and the basic characters of 14 MeV fast neutron radiography are analyzed,and it is helpful for the further re-search.

  15. Effect of Initial Chirping and Pulse Shape on 10 Gb/s Optical Pulse Transmission in Birefringent Nonlinear Fibers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Numerical method to solve the problem related with theinteractive effect of dispersion (both chromatic dispersion and polarization mode dispersion) and nonlinearity on optical pulse transmission is present. Evolutions of pulses with various initial chirping and shape at bit-rate of 10 Gb/s are simulated and compared. Gaussian pulse with appropriate prechirping is propitious for high bit-rate transmission.

  16. 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.

  17. 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.

  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. 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.

  20. [The combination treatment of malignant bone tumors using fast neutrons].

    Science.gov (United States)

    Chernichenko, V A; Tolstopiatov, B A; Konovalenko, V F; Monich, A Iu; Palivets, A Iu

    1990-01-01

    The study deals with results of a clinical trial evaluating treatment efficacy of a 6 MeV neutron beam produced by Y-120 cyclotron (Kiev). Procedures of preoperative radiotherapy and radical treatment are discussed. Radiotherapy was administered to 52 patients suffering chondrosarcoma (30 cases), osteogenic sarcoma (15) or chordoma (7). Combined treatment (radiation + surgery) was given to 22 patients whereas neutron beam therapy--to 30. All patients with osteogenic sarcoma received adjuvant combination chemotherapy. Three-year survival rate was compared to that observed in controls in whom combined treatment had included gamma-therapy. A significant increase in three-year survival rate was observed for osteogenic sarcoma and chordoma whereas for chondrosarcoma the improvement in survival proved insignificant. The use of fast neutrons in combined treatment of bone tumors was considered promising.

  1. Design of a transportable high efficiency fast neutron spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Roecker, C., E-mail: calebroecker@berkeley.edu [Department of Nuclear Engineering, University of California at Berkeley, CA 94720 (United States); Bernstein, A.; Bowden, N.S. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Cabrera-Palmer, B. [Radiation and Nuclear Detection Systems, Sandia National Laboratories, Livermore, CA 94550 (United States); Dazeley, S. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Gerling, M.; Marleau, P.; Sweany, M.D. [Radiation and Nuclear Detection Systems, Sandia National Laboratories, Livermore, CA 94550 (United States); Vetter, K. [Department of Nuclear Engineering, University of California at Berkeley, CA 94720 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-08-01

    A transportable fast neutron detection system has been designed and constructed for measuring neutron energy spectra and flux ranging from tens to hundreds of MeV. The transportability of the spectrometer reduces the detector-related systematic bias between different neutron spectra and flux measurements, which allows for the comparison of measurements above or below ground. The spectrometer will measure neutron fluxes that are of prohibitively low intensity compared to the site-specific background rates targeted by other transportable fast neutron detection systems. To measure low intensity high-energy neutron fluxes, a conventional capture-gating technique is used for measuring neutron energies above 20 MeV and a novel multiplicity technique is used for measuring neutron energies above 100 MeV. The spectrometer is composed of two Gd containing plastic scintillator detectors arranged around a lead spallation target. To calibrate and characterize the position dependent response of the spectrometer, a Monte Carlo model was developed and used in conjunction with experimental data from gamma ray sources. Multiplicity event identification algorithms were developed and used with a Cf-252 neutron multiplicity source to validate the Monte Carlo model Gd concentration and secondary neutron capture efficiency. The validated Monte Carlo model was used to predict an effective area for the multiplicity and capture gating analyses. For incident neutron energies between 100 MeV and 1000 MeV with an isotropic angular distribution, the multiplicity analysis predicted an effective area of 500 cm{sup 2} rising to 5000 cm{sup 2}. For neutron energies above 20 MeV, the capture-gating analysis predicted an effective area between 1800 cm{sup 2} and 2500 cm{sup 2}. The multiplicity mode was found to be sensitive to the incident neutron angular distribution.

  2. 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.

  3. The Effect of Combining Fast Neutron and Photon Irradiation on the Human Osteosarcoma OS-732 Cell Line

    Institute of Scientific and Technical Information of China (English)

    Linchun Feng; Lin Ma; Jingxiang Huang; Dong Yang; Yingxuan Wang; Mingxue Sun; Jinhua Tang; Weike Chang; Chengxiang Liu

    2005-01-01

    OBJECTIVE To determine the lethal effect of combining fast neutron with photon radiation on the OS-732 cell line.METHODS We examined the effect of irradiation by fast neutrons, photons and a mixed beam (fast neutrons plus photons) on the lethality and colony forming ability of the OS-732 cell line at different times.RESULTS Following a single irradiation close, the lethality was markedly strong at 24, 48 and 72 h in the group treated with fast neutrons alone and in the mixed beam group in which there was a high proportion of fast neutrons.CONCLUSION The lethal effect of a fast neutron and mixed beam with a high proportion of fast neutrons on the OS-732 cell line is highly significant. These studies provide guidance for the clinical application of fast neutrons for osteosarcoma treatment.

  4. Development of high pressure deuterium gas targets for the generation of intense mono-energetic fast neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Guzek, J. E-mail: jguzek@debeers.co.za; Richardson, K.; Franklyn, C.B.; Waites, A.; McMurray, W.R.; Watterson, J.I.W.; Tapper, U.A.S

    1999-06-01

    Two different technical solutions to the problem of generation of mono-energetic fast neutron beams on the gaseous targets are presented here. A simple and cost-effective design of a cooled windowed gas target system is described in the first part of this paper. It utilises a thin metallic foil window and circulating deuterium gas cooled down to 100 K. The ultimate beam handling capability of such target is determined by the properties of the window. Reliable performance of this gas target system was achieved at 1 bar of deuterium gas, when exposed to a 45 {mu}A beam of 5 MeV deuterons, for periods in excess of 6 h. Cooling of the target gas resulted in increased fast neutron output and improved neutron to gamma-ray ratio. The second part of this paper discusses the design of a high pressure, windowless gas target for use with pulsed, low duty cycle accelerators. A rotating seal concept was applied to reduce the gas load in a differentially pumped system. This allows operation at 1.23 bar of deuterium gas pressure in the gas cell region. Such a gas target system is free from the limitations of the windowed target but special attention has to be paid to the heat dissipation capability of the beam dump, due to the use of a thin target. The rotating seal concept is particularly suitable for use with accelerators such as radio-frequency quadrupole (RFQ) linacs that operate with a very high peak current at low duty cycle. The performance of both target systems was comprehensively characterized using the time-of-flight (TOF) technique. This demonstrated that very good quality mono-energetic fast neutron beams were produced with the slow neutron and gamma-ray component below 10% of the total target output.

  5. Feasibility of fast neutron analysis for the detection of explosives buried in soil

    Energy Technology Data Exchange (ETDEWEB)

    Faust, A.A. [Defence R and D Canada - Suffield, Medicine Hat, Alta. (Canada); McFee, J.E., E-mail: John.McFee@drdc-rddc.gc.ca [Defence R and D Canada - Suffield, Medicine Hat, Alta. (Canada); Bowman, C.L.; Mosquera, C. [Defence R and D Canada - Suffield, Medicine Hat, Alta. (Canada); Andrews, H.R.; Kovaltchouk, V.D.; Ing, H. [Bubble Technology Industries, Chalk River, Ont. (Canada)

    2011-12-11

    A commercialized thermal neutron analysis (TNA) sensor has been developed to confirm the presence of buried bulk explosives as part of a multi-sensor anti-tank landmine detection system. Continuing improvements to the TNA system have included the use of an electronic pulsed neutron generator that offers the possibility of applying fast neutron analysis (FNA) methods to improve the system's detection capability. This paper describes an investigation into the use of FNA as a complementary component in such a TNA system. The results of a modeling study using simple geometries and a full model of the TNA sensor head are presented, as well as preliminary results from an experimental associated particle imaging (API) system that supports the modeling study results. The investigation has concluded that the pulsed beam FNA approach would not improve the detection performance of a TNA system for landmine or buried IED detection in a confirmation role, and could not be made into a practical stand-alone detection system for buried anti-tank landmines. Detection of buried landmines and IEDs by FNA remains a possibility, however, through the use of the API technique.

  6. Mechanisms of fast neutron penetration in thick layers of sodium

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.Y.

    1975-01-01

    A series of computer experiments was carried out to elucidate the penetration mechanisms of fast neutrons through thick layers of sodium such as occur in LMFBR designs. As a one-dimensional approximation of the actual situation, the calculations concentrated mainly on the flux 5 meters from a plane isotropic fission source in an infinite sodium medium. Most of the transport calculations were made with the moments-method code BMT with a 496-energy point grid. Previously developed methods for reconstructing the flux from the spatial moments were used, except that a set of biorthogonal polynomials was constructed suitable for expansion of the flux in terms of a Gaussian weight function. The moments-method technique lends itself to easy and economical changes of the input cross section data. A large number of such modified cross section sets, built around the ENDF/B-III set, were used in separate calculations designed variously to emphasize or eliminate one or more particular transport processes. It was shown that, as the energy decreases below 190 keV, the flux spectrum at 5 m is increasingly dominated by an age-diffusion process that is quantitatively close to conventional age theory if the age is suitably chosen. Conclusions from this picture of neutron penetration in sodium are made as to the types of transport calculations that can be successfully made in shield design, and the accuracies needed in future cross section measurements. 37 figures, 30 tables.

  7. FNIT: the fast neutron imaging telescope for SNM detection

    Science.gov (United States)

    Bravar, Ulisse; Bruillard, Paul J.; Flückiger, Erwin O.; Macri, John R.; McConnell, Mark L.; Moser, Michael R.; Ryan, James M.

    2006-05-01

    We report on recent progress in the development of the Fast Neutron Imaging Telescope (FNIT), a detector with both imaging and energy measurement capabilities, sensitive to neutrons in the 2-20 MeV range. FNIT was initially conceived to study solar neutrons as a candidate design for the Solar Sentinels program under formulation at NASA. This instrument is now being configured to locate fission neutron sources for homeland security purposes. By accurately identifying the position of the neutron source with imaging techniques and reconstructing the energy spectrum of fission neutrons, FNIT can locate problematic amounts of Special Nuclear Material (SNM), including heavily shielded and masked samples. The detection principle is based on multiple elastic neutron-proton (n-p) scatterings in organic scintillators. By reconstructing the n-p event locations and sequence and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron point sources identified. The performance of FNIT is being evaluated through a series of Monte Carlo simulations and lab tests of detector prototypes. The Science Model One (SM1) of this instrument was recently assembled and is presently undergoing performance testing.

  8. Tagged fast neutron beams En > 6 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Favela, F.; Huerta, A.; Santa Rita, P.; Ramos, A. T.; Lucio, O. de; Andrade, E.; Ortiz, M. E.; Araujo, V.; Chávez, E., E-mail: chavez@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, México D. F. 01000 México (Mexico); Acosta, L. [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, México D. F. 01000 México (Mexico); INFN-Sezione di Catania, Via Santa Sofia 64 I-95123, Catania (Italy); Murillo, G.; Policroniades, R. [Departamento de Aceleradores, Instituto Nacional de Investigaciones Nucleares, Carr. México-Toluca S/N, Ocoyoacac, Edo. Méx., 52750 (Mexico); Varela, A. [Instituto de Ciencias de la Atmósfera, UNAM (Mexico)

    2015-07-23

    Controlled flux of neutrons are produced through the {sup 14}N(d,n){sup 15}O nuclear reaction. Deuteron beams (2-4 MeV) are delivered by the CN-Van de Graaff accelerator and directed with full intensity to our Nitrogen target at SUGAR (SUpersonic GAs jet taRget). Each neutron is electronically tagged by the detection of the associated{sup 15}O. Its energy and direction are known and “beams” of fast monochromatic tagged neutrons (E{sub n}> 6 MeV) are available for basic research and applied work. MONDE is a large area (158 × 63 cm{sup 2}) plastic scintillating slab (5 cm thick), viewed by 16 PMTs from the sides. Fast neutrons (MeV) entering the detector will produce a recoiling proton that induces a light spark at the spot. Signals from the 16 detectors are processed to deduce the position of the spark. Time logic signals from both the {sup 15}O detector and MONDE are combined to deduce a time of flight (TOF) signal. Finally, the position information together with the TOF yields the full momentum vector of each detected neutron.

  9. Feasibility study of fast neutron energy spectrometer using magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yamagishi, Hideshi; Ara, Katsuyuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-09-01

    A feasibility study of a fast neutron energy spectrometer (NES) using magnetic field was performed for development of a spectrometer having a measuring range of 3 decades and a covered energy range of 8 decades. The NES that is a kind of proton recoil spectrometer consists of a proton radiator, a magnet and a screen to detect protons. The pass of each charge particle flying into the magnetic field is deflected with a certain angle depending on the velocity of the particle, and it reaches the screen of charged particle detection after passing through the magnetic field. The energy of the particle is measured from the position on the screen at which the particle collide with. In this paper, optimization of the magnet geometry and the magnetic field intensity of the NES are discussed. The NES that is designed with the optimized geometry provides the measuring range of 3 decades with an energy measuring error of less than {+-}9%. A neutron energy range of 9 decades from 0.1 (eV) to 100 (MeV) is covered by adjusting the magnetic flux density. (author)

  10. Identification of pulse echo impulse responses for multi source transmission

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jensen, Jørgen Arendt

    2004-01-01

    transmitter and receiver pair, using a least squares estimator. The decoding is done instantaneously, making information from several transmitters available after only one transmission. This limits the influence of motion artifacts both in the decoding step and when the STA focusing scheme is applied...... is a mixture of the information corresponding to several transmitters. There is, thus, no direct way of determining which information corresponds to which transmitter, preventing proper focusing. In this paper we decode the received signal by estimating the pulse echo impulse responses between every....... The method is evaluated using the simulation tool Field II. Three point spread functions are simulated where axial movement of 1 m/s is present. The axial resolution for the moving scatterer is 0.249 mm (-3dB) and 0.291 mm (-6dB), which is compared to a standard STA transmission scheme with sequential...

  11. A study of possibility to design a fast neutron spectrometer based on the organic scintillator with surrounding materials

    Directory of Open Access Journals (Sweden)

    Avdić Senada

    2014-01-01

    Full Text Available This paper deals with the design of a novel spectrometer of fast neutrons in nuclear safeguards applications based on the liquid organic scintillator EJ-309 with materials of different thickness surrounding the detector. The investigation was performed on the simulated data obtained by the MCNPX-PoliMi numerical code based on the Monte Carlo method. Among the various materials (polyethylene, iron, aluminum, and graphite investigated as layers around the scintillator, polyethylene and iron have shown the most promising characteristics for evaluation of fast neutron energy spectra. The simulated pulse height distributions were summed up for each energy bin in the neutron energy range between 1 MeV and 15 MeV in order to obtain better counting statistics. The unfolded results for monoenergetic neutron sources obtained by a first order of Tikhonov regularization and non-linear neural network show very good agreement with the reference data while the evaluated spectra of neutron sources continuous in energy follow the trend of the reference spectra. The possible advantages of a novel spectrometer include a less number of input data for processing and a less sensitivity to the noise compared to the scintillation detector without surrounding materials.

  12. The preliminary results of fast neutron flux measurements in the DULB laboratory at Baksan

    OpenAIRE

    2000-01-01

    One of the main sources of a background in underground physics experiments (such as the investigation of solar neutrino flux, neutrino oscillations, neutrinoless double beta decay, and the search for annual and daily Cold Dark Matter particle flux modulation) are fast neutrons originating from the surrounding rocks. The measurements of fast neutron flux in the new DULB Laboratory situated at a depth of 4900 m w.e. in the Baksan Neutrino Observatory have been performed. The relative neutron sh...

  13. Fast neutron leakage in 18 MeV medical electron accelerator

    CERN Document Server

    Paredes, L; Balcazar, M; Tavera, L; Camacho, E

    1999-01-01

    In this work the neutron fluence of the Varian Clinac 2100C Medical Accelerator has been evaluated using CR39 track dosimeter. The assessment of fast neutron dose to a patient for typical treatment of 200 cGy with an 18 MV photons beam is performed at surface-source distance of 100 cm with a field size of 20x20 cm sup 2. Fast neutron leakage around of the accelerator head is evaluated.

  14. Development of fast neutron pinhole camera using nuclear emulsion for neutron emission profile measurement in KSTAR

    Science.gov (United States)

    Izumi, Y.; Tomita, H.; Nakayama, Y.; Hayashi, S.; Morishima, K.; Isobe, M.; Cheon, M. S.; Ogawa, K.; Nishitani, T.; Naka, T.; Nakano, T.; Nakamura, M.; Iguchi, T.

    2016-11-01

    We have developed a compact fast neutron camera based on a stack of nuclear emulsion plates and a pinhole collimator. The camera was installed at J-port of Korea superconducting tokamak advanced research at National Fusion Research Institute, Republic of Korea. Fast neutron images agreed better with calculated ones based on Monte Carlo neutron simulation using the uniform distribution of Deuterium-Deuterium (DD) neutron source in a torus of 40 cm radius.

  15. Fast-neutron induced background in LaBr{sub 3}:Ce detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kiener, J., E-mail: Jurgen.Kiener@csnsm.in2p3.fr [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); Tatischeff, V.; Deloncle, I. [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); Séréville, N. de [Institut de Physique Nucléaire d' Orsay, CNRS-IN2P3 and Université Paris-Sud, 91406 Orsay (France); Laurent, P. [CEA/IRFU Service d' Astrophysique, Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette (France); Laboratoire Astroparticules et Cosmologie (APC), 10, rue A. Domon et L. Duquet, 75205 Paris (France); Blondel, C. [Laboratoire AIM, CEA/IRFU, Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette (France); Chabot, M. [Institut de Physique Nucléaire d' Orsay, CNRS-IN2P3 and Université Paris-Sud, 91406 Orsay (France); Chipaux, R. [CEA/DMS/IRFU/SEDI, CEA Saclay, 91191 Gif sur Yvette (France); Coc, A. [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); Dubos, S. [Laboratoire AIM, CEA/IRFU, Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette (France); Gostojic, A. [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); and others

    2015-10-21

    The response of a scintillation detector with a cylindrical 1.5-in. LaBr{sub 3}:Ce crystal to incident neutrons has been measured in the energy range E{sub n} = 2–12 MeV. Neutrons were produced by proton irradiation of a Li target at E{sub p} = 5–14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr{sub 3}:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced γ rays emitted by the LaBr{sub 3}:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr{sub 3}:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the results of simulations to predict the response of LaBr{sub 3}:Ce detectors for a range of crystal sizes to neutron irradiation in the energy range E{sub n} = 0.5–10 MeV.

  16. Time-resolved fast-neutron pinhole camera for studying thermonuclear plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, R.W.; Weingart, R.C.

    1976-02-02

    A fast-neutron pinhole camera with high detection efficiency and nanosecond time-resolution has been developed and applied to the investigation of the spatial and temporal distributions of DD- and DT-neutrons produced by thermonuclear plasmas. The pinhole consists of a specially designed 1.15 m long copper collimator with an effective aperture of 1 mm diameter. Several different types of spatial resolution detectors have been used at the image plane: (1) a multi-element, scintillation-photomultiplier system used for time-resolved measurements consisting of sixty-one individual detectors, (2) a scintillation-fiber-chamber coupled to a gated image-intensifier tube used for direct photographing of the neutron image, and (3) a propane bubble chamber used for time-integrated recording with a capability to distinguish DD- from DT-neutrons. Pulsed neutron sources with typical dimensions of 1 cm emitting of the order of 10/sup 12/ neutrons over a time period of 10-100 nsec have been investigated. A spatial resolution of 1 mm and a time resolution of approximately 10 nsec was achieved in the investigations of dense plasma compression phenomena.

  17. Fission signal detection using helium-4 gas fast neutron scintillation detectors

    Science.gov (United States)

    Lewis, J. M.; Kelley, R. P.; Murer, D.; Jordan, K. A.

    2014-07-01

    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 4He 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 4He 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.

  18. Mosaic diamond detectors for fast neutrons and large ionizing radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Girolami, Marco; Calvani, Paolo; Trucchi, Daniele M. [Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Rome (Italy); Bellucci, Alessandro [Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Rome (Italy); Dipartimento di Fisica, Universita degli Studi di Roma ' ' La Sapienza' ' , Rome (Italy); Cazzaniga, Carlo; Rebai, Marica; Rigamonti, Davide [Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca, Milano (Italy); Istituto di Fisica dei Plasmi (IFP), Consiglio Nazionale delle Ricerche (CNR), Milano (Italy); Tardocchi, Marco [Istituto di Fisica dei Plasmi (IFP), Consiglio Nazionale delle Ricerche (CNR), Milano (Italy); Pillon, Mario [ENEA, Centro Ricerche di Frascati, Rome (Italy)

    2015-11-15

    First neutron and X-ray beam tests on a novel 12-pixel single-crystal diamond mosaic detector are presented and discussed. Preliminary characterization of single-pixel electronic properties, performed with α particles, results in charge carrier mobilities >2000 cm{sup 2} Vs{sup -1} and saturation velocities of the order of 10{sup 7} cm s{sup -1}. Signal stability over time, measured with a {sup 241}Am source (37 kBq activity), is longer than 5 h. Tests under an intense X-ray beam (1 Gy h{sup -1} dose-rate) show a very good response uniformity (down to about 1% of relative standard deviation from mean value), suggesting a high level of pixel reproducibility at intermediate bias voltages (ranging from 20 to 100 V). Response uniformity reduces at voltages >200 V, due presumably to radiation-assisted detrapping effects. Preliminary results of 12-pixel simultaneous acquisitions of X-ray beam profiles and pulse height spectra under a fast neutron beam (14 MeV) are also presented. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Fast-neutron induced background in LaBr3:Ce detectors

    CERN Document Server

    Kiener, J; Deloncle, I; de Séréville, N; Laurent, P; Blondel, C; Chabot, M; Chipaux, R; Coc, A; Dubos, S; Gostojic, A; Goutev, N; Hamadache, C; Hammache, F; Horeau, B; Limousin, O; Ouichaoui, S; Prévot, G; Rodríguez-Gasén, R; Yavahchova, M S

    2015-01-01

    The response of a scintillation detector with a cylindrical 1.5-inch LaBr3:Ce crystal to incident neutrons has been measured in the energy range En = 2-12 MeV. Neutrons were produced by proton irradiation of a Li target at Ep = 5-14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr3:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced gamma rays emitted by the LaBr3:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr3:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the resul...

  20. 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.

  1. 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.

  2. 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.

  3. Transmission Bandwidth Expansion of SI-POF Using WDM-Pulse-Position Modulations

    Institute of Scientific and Technical Information of China (English)

    Katsumi; Takano; Eiji; Matsumoto; Kiyoshi; Nakagawa

    2003-01-01

    WDM-Pulse-position modulation technique in SI-POF transmission is proposed to overcome the limitation from mode dispersion. It can expand the flat transmission bandwidth to 80MHz with 100m-fiber length.

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

    Science.gov (United States)

    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.

    2016-07-01

    The recently developed Cs2LiYCl6: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 6Li(n,α)t reaction while for the fast neutrons the 35Cl(n,p)35S and 35Cl(n,α)32P 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 35Cl, 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 7LiF target. We tested a CLYC detector 6Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector 7Li-enriched at more than 99%, which is suitable for fast neutron measurements.

  5. Fast neutron measurements with {sup 7}Li and {sup 6}Li enriched CLYC scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Giaz, A., E-mail: agnese.giaz@mi.infn.it [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Blasi, N.; Boiano, C.; Brambilla, S. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Camera, F. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Physics Department, Via Celoria 16, 20133 Milano (Italy); Cattadori, C. [INFN sezione di Milano Bicocca, Piazza della Scienza 3, 20125 Milano (Italy); Ceruti, S. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Physics Department, Via Celoria 16, 20133 Milano (Italy); Gramegna, F.; Marchi, T. [INFN Laboratori Nazionali di Legnaro, Viale dell’Università, 2, 35020 Legnaro, PD (Italy); Mattei, I. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Mentana, A. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Physics Department, Via Celoria 16, 20133 Milano (Italy); Million, B.; Pellegri, L. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Rebai, M. [Università degli Studi di Milano Bicocca, Physics Department, Piazza della Scienza 3, 20126 Milano (Italy); Riboldi, S. [INFN Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Physics Department, Via Celoria 16, 20133 Milano (Italy); Salamida, F. [INFN sezione di Milano Bicocca, Piazza della Scienza 3, 20125 Milano (Italy); Tardocchi, M. [Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, Via R. Cozzi 53, 2015 Milano (Italy)

    2016-07-21

    The recently developed Cs{sub 2}LiYCl{sub 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 {sup 6}Li(n,α)t reaction while for the fast neutrons the {sup 35}Cl(n,p){sup 35}S and {sup 35}Cl(n,α){sup 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 {sup 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 {sup 7}LiF target. We tested a CLYC detector {sup 6}Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector {sup 7}Li-enriched at more than 99%, which is suitable for fast neutron measurements.

  6. Final report on graphite irradiation test OG-3. [Fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Price, R.J.; Beavan, L.A.

    1977-01-01

    The results of dimensional, thermal expansivity, thermal conductivity, Young's modulus, and tensile strength measurements on graphite specimens irradiated in capsule OG-3 are presented. The graphite grades investigated included near-isotropic H-451 (three different preproduction lots), TS-1240, and SO818; needle coke H-327; and European coal tar pitch coke grades P/sub 3/JHA/sub 2/N, P/sub 3/JHAN, and ASI2-500. Data were obtained in the temperature range 823/sup 0/K to 1673/sup 0/K. The peak fast neutron fluence in the experiment was 3 x 10/sup 25/ n/m/sup 3/ (E greater than 29 fJ)/sub HTGR/; the total accumulated fluence exceeded 9 x 10/sup 25/ n/m/sup 2/ on some H-451 specimens and 6 x 10/sup 25/ n/m/sup 2/ on some TS-1240 specimens. Irradiation-induced dimensional changes on H-451 graphite differed slightly from earlier predictions. For an irradiation temperature of about 1225/sup 0/K, axial shrinkage rates at high fluences were somewhat higher than predicted, and the fluence at which radial expansion started (about 9 x 10/sup 25/ n/m/sup 2/ at 1275/sup 0/K) was lower. TS-1240 graphite underwent smaller dimensional changes than H-451 graphite, while limited data on SO818 and ASI2-500 graphites showed similar behavior to H-451. P/sub 3/JHAN and P/sub 3/JHA/sub 2/N graphites displayed anisotropic behavior with rapid axial shrinkage. Comparison of dimensional changes between specimens from three logs of H-451 and of TS-1240 graphites showed no significant log-to-log variations for H-451, and small but significant log-to-log variations for TS-1240. The thermal expansivity of the near-isotropic graphites irradiated at 865-1045/sup 0/K first increased by 5 percent to 10 percent and then decreased. At higher irradiation temperatures the thermal expansivity decreased by up to 50 percent. Changes in thermal conductivity were consistent with previously established curves. Specimens which were successively irradiated at two different temperatures took on the

  7. Energy spectra unfolding of fast neutron sources using the group method of data handling and decision tree algorithms

    Science.gov (United States)

    Hosseini, Seyed Abolfazl; Afrakoti, Iman Esmaili Paeen

    2017-04-01

    Accurate unfolding of the energy spectrum of a neutron source gives important information about unknown neutron sources. The obtained information is useful in many areas like nuclear safeguards, nuclear nonproliferation, and homeland security. In the present study, the energy spectrum of a poly-energetic fast neutron source is reconstructed using the developed computational codes based on the Group Method of Data Handling (GMDH) and Decision Tree (DT) algorithms. The neutron pulse height distribution (neutron response function) in the considered NE-213 liquid organic scintillator has been simulated using the developed MCNPX-ESUT computational code (MCNPX-Energy engineering of Sharif University of Technology). The developed computational codes based on the GMDH and DT algorithms use some data for training, testing and validation steps. In order to prepare the required data, 4000 randomly generated energy spectra distributed over 52 bins are used. The randomly generated energy spectra and the simulated neutron pulse height distributions by MCNPX-ESUT for each energy spectrum are used as the output and input data. Since there is no need to solve the inverse problem with an ill-conditioned response matrix, the unfolded energy spectrum has the highest accuracy. The 241Am-9Be and 252Cf neutron sources are used in the validation step of the calculation. The unfolded energy spectra for the used fast neutron sources have an excellent agreement with the reference ones. Also, the accuracy of the unfolded energy spectra obtained using the GMDH is slightly better than those obtained from the DT. The results obtained in the present study have good accuracy in comparison with the previously published paper based on the logsig and tansig transfer functions.

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

    Science.gov (United States)

    Cecilia, A; Baccaro, S; Cemmi, A; Colli, V; Gambarini, G; Rosi, G; Scolari, L

    2004-01-01

    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 [CaF2:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH3CH(NH2)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.

  9. Concept of a novel fast neutron imaging detector based on THGEM for fan-beam tomography applications

    CERN Document Server

    Cortesi, M; Adams, R; Dangendorf, V; Prasser, H -M

    2012-01-01

    The conceptual design and operational principle of a novel high-efficiency, fast neutron imaging detector based on THGEM, intended for future fan-beam transmission tomography applications, is described. We report on a feasibility study based on theoretical modeling and computer simulations of a possible detector configuration prototype. In particular we discuss results regarding the optimization of detector geometry, estimation of its general performance, and expected imaging quality: it has been estimated that detection efficiency of around 5-8% can be achieved for 2.5MeV neutrons; spatial resolution is around one millimeter with no substantial degradation due to scattering effects. The foreseen applications of the imaging system are neutron tomography in non-destructive testing for the nuclear energy industry, including examination of spent nuclear fuel bundles, detection of explosives or drugs, as well as investigation of thermal hydraulics phenomena (e.g., two-phase flow, heat transfer, phase change, cool...

  10. Concept of a novel fast neutron imaging detector based on THGEM for fan-beam tomography applications

    Science.gov (United States)

    Cortesi, M.; Zboray, R.; Adams, R.; Dangendorf, V.; Prasser, H.-M.

    2012-02-01

    The conceptual design and operational principle of a novel high-efficiency, fast neutron imaging detector based on THGEM, intended for future fan-beam transmission tomography applications, is described. We report on a feasibility study based on theoretical modeling and computer simulations of a possible detector configuration prototype. In particular we discuss results regarding the optimization of detector geometry, estimation of its general performance, and expected imaging quality: it has been estimated that detection efficiency of around 5-8% can be achieved for 2.5 MeV neutrons; spatial resolution is around one millimeter with no substantial degradation due to scattering effects. The foreseen applications of the imaging system are neutron tomography in non-destructive testing for the nuclear energy industry, including examination of spent nuclear fuel bundles, detection of explosives or drugs, as well as investigation of thermal hydraulics phenomena (e.g., two-phase flow, heat transfer, phase change, coolant dynamics, and liquid metal flow).

  11. Fast neutron background characterization with the Radiological Multi-sensor Analysis Platform (RadMAP)

    CERN Document Server

    Davis, John R; Vetter, Kai

    2016-01-01

    In an effort to characterize the fast neutron radiation background, 16 EJ-309 liquid scintillator cells were installed in the Radiological Multi-sensor Analysis Platform (RadMAP) to collect data in the San Francisco Bay Area. Each fast neutron event was associated with specific weather metrics (pressure, temperature, absolute humidity) and GPS coordinates. The expected exponential dependence of the fast neutron count rate on atmospheric pressure was demonstrated and event rates were subsequently adjusted given the measured pressure at the time of detection. Pressure adjusted data was also used to investigate the influence of other environmental conditions on the neutron background rate. Using National Oceanic and Atmospheric Administration (NOAA) coastal area lidar data, an algorithm was implemented to approximate sky-view factors (the total fraction of visible sky) for points along RadMAPs route. Three areas analyzed in San Francisco, Downtown Oakland, and Berkeley all demonstrated a suppression in the backg...

  12. Monte Carlo Calculations for Neutron and Gamma Radiation Fields on a Fast Neutron Irradiation Device

    Science.gov (United States)

    Vieira, A.; Ramalho, A.; Gonçalves, I. C.; Fernandes, A.; Barradas, N.; Marques, J. G.; Prata, J.; Chaussy, Ch.

    We used the Monte Carlo program MCNP to calculate the neutron and gamma fluxes on a fast neutron irradiation facility being installed on the Portuguese Research Reactor (RPI). The purpose of this facility is to provide a fast neutron beam for irradiation of electronic circuits. The gamma dose should be minimized. This is achieved by placing a lead shield preceded by a thin layer of boral. A fast neutron flux of the order of 109 n/cm2s is expected at the exit of the tube, while the gamma radiation is kept below 20 Gy/h. We will present results of the neutron and gamma doses for several locations along the tube and different thickness of the lead shield. We found that the neutron beam is very collimated at the end of the tube with a dominant component on the fast region.

  13. The preliminary results of fast neutron flux measurements in the DULB laboratory at Baksan

    CERN Document Server

    Abdurashitov, J N; Kalikhov, A V; Shikhin, A A; Yants, V E; Zaborskaia, O S; Klimenko, A A; Osetrov, S B; Smolnikov, A A; Vasilev, S I

    2000-01-01

    One of the main sources of a background in underground physics experiments (such as the investigation of solar neutrino flux, neutrino oscillations, neutrinoless double beta decay, and the search for annual and daily Cold Dark Matter particle flux modulation) are fast neutrons originating from the surrounding rocks. The measurements of fast neutron flux in the new DULB Laboratory situated at a depth of 4900 m w.e. in the Baksan Neutrino Observatory have been performed. The relative neutron shielding properties of several commonly available natural materials were investigated too. The preliminary results obtained with a high-sensitive fast neutron spectrometer at the level of sensitivity of about 10^(-7) neutron/ (cm^2 sec) are presented and discussed.

  14. Measurement of the Surface and Underground Neutron Spectra with the UMD/NIST Fast Neutron Spectrometers

    Science.gov (United States)

    Langford, Thomas J.

    The typical fast neutron detector falls into one of two categories, Bonner sphere spectrometers and liquid scintillator proton recoil detectors. These two detector types have traditionally been used to measure fast neutrons at the surface and in low background environments. The cosmogenic neutron spectrum and flux is an important parameter for a number of experimental efforts, including procurement of low background materials and the prediction of electronic device faults. Fast neutrons can also cause problems for underground low-background experiments, through material activation or signals that mimic rare events. Current detector technology is not sufficient to properly characterize these backgrounds. To this end, the University of Maryland and the National Institute of Standards and Technology designed, developed, and deployed two Fast Neutron Spectrometers (FaNS) comprised of plastic scintillator and 3He proportional counters. The detectors are based upon capture-gated spectroscopy, a technique that demands a delayed coincidence between a neutron scatter and the resulting neutron capture after thermalization. This technique provides both particle identification and knowledge that the detected neutron fully thermalized. This improves background rejection capabilities and energy resolution. Presented are the design, development, and deployment of FaNS-1 and FaNS-2. Both detectors were characterized using standard fields at NIST, including calibrated 252Cf neutron sources and two monoenergetic neutron generators. Measurements of the surface fast neutron spectrum and flux have been made with both detectors, which are compared with previous measurements by traditional detectors. Additionally, FaNS-1 was deployed at the Kimballton Underground Research Facility (KURF) in Ripplemead, VA. A measurement of the fast neutron spectrum and flux at KURF is presented as well. FaNS-2 is currently installed in a shallow underground laboratory where it is measuring the muon

  15. Fast neutron-induced damage in INTEGRAL n-type HPGe detectors

    CERN Document Server

    Borrel, V; Albernhe, F; Frabel, P; Cordier, B; Tauzin, G; Crespin, S; Coszach, R; Denis, J M; Leleux, P

    1999-01-01

    Several INTEGRAL n-type HPGe detectors have been irradiated by fast neutrons and their degradation studied through the analysis of line shapes. The availability of three different fast neutron beams (5, 16 and 6-70 MeV) allowed a quantitative analysis of the importance of the neutron energy on the amount of damage. A comparison is made with the degradation induced by high-energy proton irradiations. Transient effects on the measured resolution are reported after high voltage cut-off on degraded detectors.

  16. A system of materials composition and geometry arrangement for fast neutron beam thermalization: An MCNP study

    Science.gov (United States)

    Uhlář, Radim; Alexa, Petr; Pištora, Jaromír

    2013-03-01

    Compact deuterium-tritium neutron generators emit fast neutrons (14.2 MeV) that have to be thermalized for neutron activation analysis experiments. To maximize thermal neutron flux and minimize epithermal and fast neutron fluxes across the output surface of the neutron generator facility, Monte Carlo calculations (MCNP5; Los Alamos National Laboratory) for different moderator types and widths and collimator and reflector designs have been performed. A thin lead layer close to the neutron generator as neutron multiplier followed by polyethylene moderator and surrounded by a massive lead and nickel collimator and reflector was obtained as the optimum setup.

  17. 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.

  18. An Electromagnet for Precession of the Polarization of Fast-Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Aspesund, O.; Bjorkman, J.; Trumpy, G.

    1965-05-15

    The advantages of using a transverse magnetic field for precessing the polarization of fast-neutrons are discussed. Design details of a powerful electromagnet supplying a transverse field of approximately 20 kGauss are given. Precession characteristics for polarized fast neutrons obtained at 50 deg (lab. syst.) from the Li{sup 7} (p, n) Be{sup 7} reaction are reported, using elastic scattering at 42 deg (lab. syst.) off natural carbon as an analyser. Correlation of the precession data with theoretical predictions presented elsewhere is made, and good agreement is found.

  19. 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...

  20. Lithium-containing scintillators for thermal neutron, fast neutron, and gamma detection

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, Natalia P.; Carman, M. Leslie; Faust, Michelle A.

    2016-03-01

    In one embodiment, a scintillator includes a scintillator material; a primary fluor, and a Li-containing compound, where the Li-containing compound is soluble in the primary fluor, and where the scintillator exhibits an optical response signature for thermal neutrons that is different than an optical response signature for fast neutrons and gamma rays.

  1. Fast neutron radiation induced Glu-B1 deficient lines of an elite bread wheat variety

    Science.gov (United States)

    Five isogenic wheat lines deficient in high-molecular weight subunit (HMW-GS) proteins encoded by the B-genome were identified from a fast-neutron radiation-mutagenized population of Summit, an elite variety of bread wheat (Triticum aestivum L.). The mutant lines differ from the wild-type progenit...

  2. Characterization of the fast neutron irradiation facility of the Portuguese Research Reactor after core conversion.

    Science.gov (United States)

    Marques, J G; Sousa, M; Santos, J P; Fernandes, A C

    2011-08-01

    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 1MeV equivalent neutron flux along the facility, in the new irradiation conditions, following ASTM E722 standard.

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

    Science.gov (United States)

    Medhat, M. E.

    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.

  4. Q-factor analysis of nonlinear impairments in ultrahigh-speed Nyquist pulse transmission.

    Science.gov (United States)

    Hirooka, Toshihiko; Nakazawa, Masataka

    2015-12-28

    We present detailed analytical and numerical results of the dispersion and nonlinear tolerances of RZ and Nyquist optical pulses in ultrahigh-speed TDM transmissions. From a Q-map analysis, i.e. by numerically calculating the Q-factor distribution as a function of transmission power and fiber dispersion, we found that Nyquist TDM transmission has a substantially larger Q margin as regards both dispersion and optical power thanks to ISI-free overlapped TDM. We also show that the optimum transmission power for Nyquist pulses is 2 dB lower than for RZ pulses. An analytical model is provided to explain the overlap-induced nonlinear impairments in Nyquist TDM transmission in a high power regime, which agrees well with numerical results.

  5. Chemical weapons detection by fast neutron activation analysis techniques

    Science.gov (United States)

    Bach, P.; Ma, J. L.; Froment, D.; Jaureguy, J. C.

    1993-06-01

    A neutron diagnostic experimental apparatus has been tested for nondestructive verification of sealed munitions. Designed to potentially satisfy a significant number of van-mobile requirements, this equipment is based on an easy to use industrial sealed tube neutron generator that interrogates the munitions of interest with 14 MeV neutrons. Gamma ray spectra are detected with a high purity germanium detector, especially shielded from neutrons and gamma ray background. A mobile shell holder has been used. Possible configurations allow the detection, in continuous or in pulsed modes, of gamma rays from neutron inelastic scattering, from thermal neutron capture, and from fast or thermal neutron activation. Tests on full scale sealed munitions with chemical simulants show that those with chlorine (old generation materials) are detectable in a few minutes, and those including phosphorus (new generation materials) in nearly the same time.

  6. 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.

  7. Intra-Channel Nonlinear Effect on Optical PPM Pulse Transmission

    Institute of Scientific and Technical Information of China (English)

    Sun; Linghao; Jarmo; Takala

    2003-01-01

    PPM encoded Gaussian pulse sequence shows more immunity than non-PPM schemes on optical fiber intra-channel nonlinearity and demonstrated by a numerical study of IXPM and IFWM effects deploying on 100Gb/s single channelsystem.

  8. Finger blood content, light transmission, and pulse oximetry errors.

    Science.gov (United States)

    Craft, T M; Lawson, R A; Young, J D

    1992-01-01

    The changes in light emitting diode current necessary to maintain a constant level of light incident upon a photodetector were measured in 20 volunteers at the two wavelengths employed by pulse oximeters. Three states of finger blood content were assessed; exsanguinated, hyperaemic, and normal. The changes in light emitting diode current with changes in finger blood content were small and are not thought to represent a significant source of error in saturation as measured by pulse oximetry.

  9. Negative Group Velocity Pulse Propagation Through a Left-Handed Transmission Line

    CERN Document Server

    Jiang, Rong; Miao, Jing-Yuan; Liu, Xin-Meng

    2015-01-01

    In this paper, the microwave pulse propagation transferred through a left-handed transmission line using Complementary Omega-Like Structures (COLS) loaded was studied. There was a stop band in transmission from 5.6GHz to 6.1GHz, and the anomalous dispersion was causes in this band. Negative group velocity corresponds to the case in which the peak of the pulse exited before the peak of the incident pulse had entered the sample. The negative group velocity reached (-0.27c~-1.85c).

  10. Time-resolved optical transmission of pulsed laser-irradiated silicon

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.C.; Lo, H.W.; Aydinli, A.; Compaan, A.

    1980-10-20

    The time-resolved optical transmission of silicon has been observed at lambda = 1.15 microns during irradiation by an 8 nsec pulsed laser at 485 nm with several energy densities in the range of .25 to 1.2 J/sq cm. The transmission exhibits a sudden brief drop consistent with the rise and fall of the reflectivity enhancement. However, the transmission does not exhibit the strong absorption expected of molten silicon with a skin depth of approx. 100A.

  11. A novel fast-neutron tomography system based on a plastic scintillator array and a compact D-D neutron generator.

    Science.gov (United States)

    Adams, Robert; Zboray, Robert; Prasser, Horst-Michael

    2016-01-01

    Very few experimental imaging studies using a compact neutron generator have been published, and to the knowledge of the authors none have included tomography results using multiple projection angles. Radiography results with a neutron generator, scintillator screen, and camera can be seen in Bogolubov et al. (2005), Cremer et al. (2012), and Li et al. (2014). Comparable results with a position-sensitive photomultiplier tube can be seen in Popov et al. (2011). One study using an array of individual fast neutron detectors in the context of cargo scanning for security purposes is detailed in Eberhardt et al. (2005). In that case, however, the emphasis was on very large objects with a resolution on the order of 1cm, whereas this study focuses on less massive objects and a finer spatial resolution. In Andersson et al. (2014) three fast neutron counters and a D-T generator were used to perform attenuation measurements of test phantoms. Based on the axisymmetry of the test phantoms, the single-projection information was used to calculate radial attenuation distributions of the object, which was compared with the known geometry. In this paper a fast-neutron tomography system based on an array of individual detectors and a purpose-designed compact D-D neutron generator is presented. Each of the 88 detectors consists of a plastic scintillator read out by two Silicon photomultipliers and a dedicated pulse-processing board. Data acquisition for all channels was handled by four single-board microcontrollers. Details of the individual detector design and testing are elaborated upon. Using the complete array, several fast-neutron images of test phantoms were reconstructed, one of which was compared with results using a Co-60 gamma source. The system was shown to be capable of 2mm resolution, with exposure times on the order of several hours per reconstructed tomogram. Details about these measurements and the analysis of the reconstructed images are given, along with a discussion

  12. Transmission Properties of THz Radiation Pulses through Very Deep Zero-Order Metallic Gratings

    Institute of Scientific and Technical Information of China (English)

    XING Qi-Rong; LI Shu-Xin; ZHANG Wei-Li; LANG Li-Ying; MAO Fang-Lin; XU Shi-Xiang; CHAI Lu; WANG Qing-Yue

    2005-01-01

    @@ Very deep zero-order metallic grating structures are processed to study the transmission properties of THz radiation pulses. The experiments have been performed with two samples. The delay of the THz pulses and the corresponding resonantly enhanced transmission spectra through the samples are observed. To explain the extraordinary transmission we have treated the samples as Fabry-Perot resonators through resonant excitation of the coupled surface plasmon polaritons filled in the cavities between the metal slats. The experimental results are in reasonable agreement with the numerical simulation. Our results show that THz-time-domain spectroscopy may be an effective technique for studying the optical properties of various THz microstructured devices.

  13. Dose estimations of fast neutrons from a nuclear reactor by micronuclear yields in onion seedlings.

    Science.gov (United States)

    Fujikawa, K; Endo, S; Itoh, T; Yonezawa, Y; Hoshi, M

    1999-12-01

    Irradiations of onion seedlings with fission neutrons from bare, Pb-moderated, and Fe-moderated 252Cf sources induced micronuclei in the root-tip cells at similar rates. The rate per cGy averaged for the three sources, , was 19 times higher than rate induced by 60Co gamma-rays. When neutron doses, Dn, were estimated from frequencies of micronuclei induced in onion seedlings after exposure to neutron-gamma mixed radiation from a 1 W nuclear reactor, using the reciprocal of as conversion factor, resulting Dn values agreed within 10% with doses measured with paired ionizing chambers. This excellent agreement was achieved by the high sensitivity of the onion system to fast neutrons relative to gamma-rays and the high contribution of fast neutrons to the total dose of mixed radiation in the reactor's field.

  14. 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.

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

    Science.gov (United States)

    Yi, Chia Jia; Nilsuwankosit, Sunchai

    2016-01-01

    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.

  16. Influence of Fast Neutron Irradiation on Critical Current Densities of Bi-2223/Ag Tape

    Institute of Scientific and Technical Information of China (English)

    Duan Zhenzhong

    2004-01-01

    Experimental results on the magnetic field behavior of the critical current in silver sheathed Bi-2223 tapes are presented. The experiments consist of transport and magnetic measurements in a wide temperature range and in external magnetic field up to 6 T. Significant enhancement of the intragrain critical current densities Jc are observed after irradiation with fast neutron. This is attributed to an improvement of flux pinning capability by the neutron induced defects, but the weak link structure is somewhat damaged as evidenced by the small degradation of transport critical current at low field. According to the measurement of remanent magnetic moment before and after irradiation with fast neutron, the connectivity in Bi-2223 tapes is reduced by 50% after irradiated to a fluence of 2 × 1021 m-2, which resulted in the critical currents degradated by a factor of 10%.

  17. SWAN - Detection of explosives by means of fast neutron activation analysis

    Science.gov (United States)

    Gierlik, M.; Borsuk, S.; Guzik, Z.; Iwanowska, J.; Kaźmierczak, Ł.; Korolczuk, S.; Kozłowski, T.; Krakowski, T.; Marcinkowski, R.; Swiderski, L.; Szeptycka, M.; Szewiński, J.; Urban, A.

    2016-10-01

    In this work we report on SWAN, the experimental, portable device for explosives detection. The device was created as part of the EU Structural Funds Project "Accelerators & Detectors" (POIG.01.01.02-14-012/08-00), with the goal to increase beneficiary's expertise and competencies in the field of neutron activation analysis. Previous experiences and budged limitations lead toward a less advanced design based on fast neutron interactions and unsophisticated data analysis with the emphasis on the latest gamma detection and spectrometry solutions. The final device has been designed as a portable, fast neutron activation analyzer, with the software optimized for detection of carbon, nitrogen and oxygen. SWAN's performance in the role of explosives detector is elaborated in this paper. We demonstrate that the unique features offered by neutron activation analysis might not be impressive enough when confronted with practical demands and expectations of a generic homeland security customer.

  18. Influence of rapid thermal process on intrinsic gettering in fast neutron irradiated Czochralski silicon

    Institute of Scientific and Technical Information of China (English)

    CHEN Gui-feng; LI Yang-xian; LI Xing-hua; CAI Li-li; MA Qiao-yun; NIU Ping-juan; NIU Sheng-li; CHEN Dong-feng

    2006-01-01

    A rapid thermal process (RTP) was first introduced into the intrinsic gettering (IG) processes of fast neutron irradiated Czochralski (CZ) silicon. The effect of RTP conditions on bulk microdefects (BMDs) and denuded zone (DZ) was investigated. Fourier transform infrared absorption spectrometer (FTIR) was used to measure the concentration of interstitial oxygen ([Oi]). Bulk microdefects were observed by optical microscope. The results show that,according to the variation of [Oi],it is found that RTP doesn't change the processes of oxygen precipitation in fast neutron irradiated Czochralski silicon. Perfect denuded zone,dense oxygen precipitates and defects form in the bulk of irradiated samples. With increasing temperature of RTP,the width of denuded zone decreases. Increasing RTP cooling rate,the density of Bulk microdefects increases. DZ forms in the sample that annealed in nitrogen atmosphere.

  19. Measured Thermal and Fast Neutron Fluence Rates for ATF-1 Holders During ATR Cycle 157D

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Larry Don [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, David Torbet [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 157D which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains measurements of the fluence rates corresponding to the particular elevations relative to the 80-ft. core elevation. The data in this report consist of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, and (3) plots of both the thermal and fast neutron fluence rates. The fluence rates reported are for the average power levels given in the table of power history and distribution.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Applications of tunable high energy/pressure pulsed lasers to atmospheric transmission and remote sensing

    Science.gov (United States)

    Hess, R. V.; Seals, R. K.

    1974-01-01

    Atmospheric transmission of high energy C12 O2(16) lasers were improved by pulsed high pressure operation which, due to pressure broadening of laser lines, permits tuning the laser 'off' atmospheric C12 O2(16) absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers, and for vertical transmission through the entire atmosphere. The atmospheric transmission of tuned C12 O2(16) lasers compares favorably with C12 O2(18) isotope lasers and CO lasers. The advantages of tunable, high energy, high pressure pulsed lasers over tunable diode lasers and waveguide lasers, in combining high energies with a large tuning range, are evaluated for certain applications to remote sensing of atmospheric constituents and pollutants. Pulsed operation considerably increases the signal to noise ratio without seriously affecting the high spectral resolution of signal detection obtained with laser heterodyning.

  3. 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.

  4. 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.

  5. A unified Monte Carlo approach to fast neutron cross section data evaluation.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.; Nuclear Engineering Division

    2008-03-03

    A unified Monte Carlo (UMC) approach to fast neutron cross section data evaluation that incorporates both model-calculated and experimental information is described. The method is based on applications of Bayes Theorem and the Principle of Maximum Entropy as well as on fundamental definitions from probability theory. This report describes the formalism, discusses various practical considerations, and examines a few numerical examples in some detail.

  6. Radiation Detection and Classification of Heavy Oxide Inorganic Scintillator Crystals for Detection of Fast Neutrons

    Science.gov (United States)

    2016-06-01

    and alkali-halide scintillators for potential use in neutron and gamma detection systems .” M.S. thesis, Dept. Physics , Naval Posgraduate School...DETECTION AND CLASSIFICATION OF HEAVY OXIDE INORGANIC SCINTILLATOR CRYSTALS FOR DETECTION OF FAST NEUTRONS by Jacob W. Capps June 2016 Thesis...DATE June 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE RADIATION DETECTION AND CLASSIFICATION OF HEAVY OXIDE

  7. Fast neutron background characterization with the Radiological Multi-sensor Analysis Platform (RadMAP)

    Science.gov (United States)

    Davis, John R.; Brubaker, Erik; Vetter, Kai

    2017-06-01

    In an effort to characterize the fast neutron radiation background, 16 EJ-309 liquid scintillator cells were installed in the Radiological Multi-sensor Analysis Platform (RadMAP) to collect data in the San Francisco Bay Area. Each fast neutron event was associated with specific weather metrics (pressure, temperature, absolute humidity) and GPS coordinates. The expected exponential dependence of the fast neutron count rate on atmospheric pressure was demonstrated and event rates were subsequently adjusted given the measured pressure at the time of detection. Pressure adjusted data was also used to investigate the influence of other environmental conditions on the neutron background rate. Using National Oceanic and Atmospheric Administration (NOAA) coastal area lidar data, an algorithm was implemented to approximate sky-view factors (the total fraction of visible sky) for points along RadMAPs route. Three areas analyzed in San Francisco, Downtown Oakland, and Berkeley all demonstrated a suppression in the background rate of over 50% for the range of sky-view factors measured. This effect, which is due to the shielding of cosmic-ray produced neutrons by surrounding buildings, was comparable to the pressure influence which yielded a 32% suppression in the count rate over the range of pressures measured.

  8. 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.

  9. The effects of fast neutron irradiation on oxygen in Czochralski silicon

    Institute of Scientific and Technical Information of China (English)

    Chen Gui-Feng; Yan Wen-Bo; Chen Hong-Jian; Li Xing-Hua; Li Yang-Xian

    2009-01-01

    The effects of fast neutron irradiation on oxygen atoms in Czochralski silicon (CZ-Si) are investigated systemically by using Fourier transform infrared (FTIR) spectrometer and positron annihilation technique (PAT). Through isochronal annealing, it is found that the trend of variation in interstitial oxygen concentration ([Oi]) in fast neutrons irradiated CZ-Si fluctuates largely with temperature increasing, especially between 500 and 700℃. After the CZ-Si is annealed at 600℃, the V4 appearing as three-dimensional vacancy clusters causes the formation of the molecule-like oxygen clusters, and more importantly these dimers with small binding energies (0.1-1.0eV) can diffuse into the Si lattices more easily than single oxygen atoms, thereby leading to the strong oxygen agglomerations. When the CZ-Si is annealed at temperature increasing up to 700℃, three-dimensional vacancy clusters disappear and the oxygen agglomerations decompose into single oxygen atoms (O) at interstitial sites. Results from FTIR spectrometer and PAT provide an insight into the nature of the [Oi] at temperatures between 500 and 700℃. It turns out that the large fluctuation of [Oi] after short-time annealing from 500 to 700℃ results from the transformation of fast neutron irradiation defects.

  10. Influence of thermal and resonance neutron on fast neutron flux measurement by Pu-239 fission chamber

    CERN Document Server

    zeng, Lina; Song, Lingli; Zheng, Chun

    2014-01-01

    The Pu-239 fission chambers are widely used to measure fission spectrum neutron flux due to a flat response to fast neutrons. However, in the mean time the resonance and thermal neutrons can cause a significant influence on the measurement if they are moderated, which could be eliminated by using B and Cd covers. At a column enriched uranium fast neutron critical assembly, the fission reaction rates of Pu-239 are measured as 1.791*10-16,2.350*10-16 and 1.385*10-15 per second for 15mm thick B cover, 0.5mm thick Cd cover, and no cover respectively. While the fission reaction rate of Pu-239 is rapidly increased to 2.569*10-14 for a 20mm thick polythene covering fission chamber. The average Pu-239 fission cross-section of thermal and resonance neutrons is calculated to be 500b and 24.95b with the assumption of 1/v and 1/E spectra respectively, then thermal, resonance and fast neutron flux are achieved to be 2.30*106,2.24*106 and 1.04*108cm-2s-1.

  11. Statistical estimation of the performance of a fast-neutron multiplicity system for nuclear material accountancy

    Energy Technology Data Exchange (ETDEWEB)

    Chichester, David L., E-mail: david.chichester@inl.gov [Idaho National Laboratory, 2525 N. Fremont Avenue, Idaho Falls, ID 83415 (United States); Thompson, Scott J.; Kinlaw, Mathew T.; Johnson, James T. [Idaho National Laboratory, 2525 N. Fremont Avenue, Idaho Falls, ID 83415 (United States); Dolan, Jennifer L.; Flaska, Marek; Pozzi, Sara A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104 (United States)

    2015-06-01

    Statistical analyses have been performed to develop bounding estimates of the expected performance of a conceptual fast-neutron multiplicity system (FNMS) for assaying plutonium. The conceptual FNMS design includes 32 cubic liquid scintillator detectors, measuring 7.62 cm per side, configured into 4 stacked rings of 8 detectors each. Expected response characteristics for the individual FNMS detectors, as well as the response characteristics of the entire FNMS, were determined using Monte Carlo simulations based on prior validation experiments. The results from these simulations were then used to estimate the Pu assay capabilities of the FNMS in terms of counting time, assay mass, and assay mass variance, using assay mass variance as a figure of merit. The analysis results are compared against a commonly used thermal-neutron coincidence counter. The advantages of using a fast-neutron counting system versus a thermal-neutron counting system are significant. Most notably, the time required to perform an assay to an equivalent assay mass variance is greatly reduced with a fast-neutron system, by more than an order of magnitude compared with that of the thermal-neutron system, due to the reduced probability of random summing with the fast system. The improved FNMS performance is especially relevant for assays involving Pu masses of 10 g or more.

  12. High-frame rate, fast neutron imaging of two-phase flow in a thin rectangular channel

    CERN Document Server

    Zboray, R; Dangendorf, V; Stark, M; Tittelmeier, K; Cortesi, M; Adams, R

    2015-01-01

    We have demonstrated the feasibility of performing high-frame-rate, fast neutron radiography of air-water two-phase flows in a thin channel with rectangular cross section. The experiments have been carried out at the accelerator facility of the Physikalisch-Technische Bundesanstalt. A polychromatic, high-intensity fast neutron beam with average energy of 6 MeV was produced by 11.5 MeV deuterons hitting a thick Be target. Image sequences down to 10 millisecond exposure times were obtained using a fast-neutron imaging detector developed in the context of fast-neutron resonance imaging. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two phase flow parameters like the volumetric gas fraction, bubble size and bubble velocities have been measured. The first results are promising, improvements for future experiments are also discussed.

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

    CERN Document Server

    Kroc, T K

    2012-01-01

    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 optimization. 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.

  14. Characterization of Heavy Oxide Inorganic Scintillator Crystals for Direct Detection of Fast Neutrons Based on Inelastic Scattering

    Science.gov (United States)

    2015-03-01

    emission of additional gamma photons that likewise cause scintillation [4]. The specific goals of this research are to:  explore the physics of fast ...reaction products are registered; also in the sense that, in the case of fast neutrons, moderation is normally required before the absorption event...various other forms of radiation, fast neutrons are the crux of the overall study, and every effort should be made to test with them. 39 LIST OF

  15. Experimental setup for the determination of the correction factors of the neutron doseratemeters in fast neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Iliescu, Elena; Bercea, Sorin; Dudu, Dorin; Celarel, Aurelia [National Institute of R and D for Physics and Nuclear Engineering-Horia Hulubei, Reactorului 30 St, P.O.BOX MG-6,Magurele, cod 077125 (Romania)

    2013-12-16

    The use of the U-120 Cyclotron of the IFIN-HH allowed to perform a testing bench with fast neutrons in order to determine the correction factors of the doseratemeters dedicated to neutron measurement. This paper deals with researchers performed in order to develop the irradiation facility testing the fast neutrons flux generated at the Cyclotron. This facility is presented, together with the results obtain in determining the correction factor for a doseratemeter dedicated to the neutron dose equivalent rate measurement.

  16. 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

  17. Enhancement of Time Reversal Sub-wavelength Wireless Transmission Using Pulse Shaping Technique (submit/1139227)

    CERN Document Server

    Ding, Shuai; Zang, Rui; Zou, Lianfeng; Wang, Bing-Zhong; Caloz, Christophe

    2014-01-01

    A novel time-reversal subwavelength transmission technique, based on pulse shaping circuits (PSCs), is proposed. This technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. It is shown that, compared to our previous time-reversal system based on chirped delay lines, the PSC approach offers greater flexibility and larger possible numbers of channels, i.e. ultimately higher transmission throughput. The PSC based time-reversal system is also demonstrated experimentally.

  18. Global dynamics behaviors for new delay SEIR epidemic disease model with vertical transmission and pulse vaccination

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A robust SEIR epidemic disease model with a profitless delay and vertical transmission is formulated, and the dynamics behaviors of the model under pulse vaccination are analyzed.By use of the discrete dynamical system determined by the the model are under appropriate conditions.Using the theory on delay functional and impulsive differential equation, the sufficient condition with time delay for the permanence of the system is obtained, and it is proved that time delays, pulse vaccination and vertical transmission can bring obvious effects on the dynamics behaviors of the model.

  19. Enhancement of Time-Reversal Subwavelength Wireless Transmission Using Pulse Shaping

    CERN Document Server

    Ding, Shuai; Zou, Lianfeng; Wang, Bingzhong; Caloz, Christophe

    2014-01-01

    A novel time-reversal subwavelength transmission technique, based on pulse shaping circuits (PSCs), is proposed. Compared to previously reported approaches, this technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. Moreover, the pulse shaping circuits (PSCs) are based on Radio Analog Signal Processing (R-ASP), and therefore do not suffer from the well-known issues of digital signal processing in ultrafast regimes. The proposed PSC time-reversal systems is mathematically shown to offer high channel discrimination under appropriate PSC design conditions, and is experimentally demonstrated for the case of two receivers.

  20. Effect of pulse chirp parameter on the soliton high-speed transmission systems

    Science.gov (United States)

    Ladanyi, L.; Scholtz, L.; Solanska, M.; Mullerova, J.

    2016-12-01

    The word soliton refers to a special kind of wave packets that can propagate undistorted over long distances. As a source for generating soliton pulses in 1990 erbium doped lasers were used. Soliton transmission systems have been the subject of interest for years. It is known that interaction and the balance between the dispersion and nonlinear effects in optical fibers can lead to a special pulse behavior. Soliton pulses can propagate without any changes of the amplitude and the shape via long transmission systems. Due to this advantage they are of interest in long haul communication systems. Here we describe how the random change of input pulse chirp in optical fibers can affect the soliton propagation and interaction between two or more solitons. We have focused on describing some numerical approaches to solve the coupled nonlinear Schrödinger equations, which are useful by solving this kind of problem. Most of laser sources can be approximated by Gaussian distribution or in special cases the second hyperbolic pulses are generated to produce a soliton shaped pulse. The effect of pulse chirp can generate new frequencies due to the frequency chirp. In high bitratetransmission systems this chirp is very important to reduce, because of this new frequency can influence the neighbor channels and lead to BER increasing.

  1. Use of CR 39 Films for Evaluation of Shielding Efficacy of Materials against Fast Neutrons

    OpenAIRE

    1992-01-01

    CR-39 films have been used for evaluation of neutron shielding of metal alloys, different types of rubbers, sand polymers, etc. These films have been chosen because of their ability to record fast neutrons from 200 keV-10 MeV and their insensitivity to gamma radiations. Tenth value layer (TVL) for the materials studied varies from 10.5 to 28.6 cm. In addition, the values of TVL have also been computed for standard material, such as Al, steel, etc. Using neutron removal cross-section da...

  2. 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.

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

    Institute of Scientific and Technical Information of China (English)

    DOU Hai-Feng; TANG Bin

    2011-01-01

    Scattering neutrons are one of the key factors that may affect the images of fast neutron radiog- raphy. 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 LiD are given.

  4. N-acetylcysteine and captopril protect DNA and cells against radiolysis by fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Spotheim-Maurizot, M. (CNRS, 45 - Orleans (France). Centre de Biophysique Moleculaire); Garnier, F. (CNRS, 45 - Orleans (France). Centre de Biophysique Moleculaire); Kieda, C. (CNRS, 45 - Orleans (France). Centre de Biophysique Moleculaire); Sabattier, R. (Centre Hospitalier Regional d' Orleans, 45 (France). Service de Radiotherapie); Charlier, M. (CNRS, 45 - Orleans (France). Centre de Biophysique Moleculaire)

    1993-10-01

    N-Acetylcysteine and captopril, respectively mucolytic and antihypertensive drugs, contain free sulfhydryl groups. Since in general thiols have well-established radioprotective abilities, we sought putative radioprotective effects of these drugs against therapeutic fast neutrons. We show that pBR322 plasmid DNA is indeed protected against radiolytic strand breakage by both drugs. The oxygen independent protection is consistent with a hydroxyl radical scavenging mechanism. A clonogenicity assay reveals an increase of the survival of SCL-1 cultured keratinocytes irradiated in the presence of the drugs compared with cells irradiated without drugs. Our results suggest possible interferences between treatment with drugs bearing-SH groups and radiotherapy. (orig.)

  5. The fast neutron SEU cross section of a 4 Mb SRAM memory

    Energy Technology Data Exchange (ETDEWEB)

    Pereira Junior, Evaldo C.F.; Goncalez, Odair L.; Cruz, Marco Aurelio da; Prado, Adriane Cristina Mendes; Federico, Claudio Antonio; Gaspar, Felipe de Barros, E-mail: claudiofederico@ieav.cta.br, E-mail: odairlelisgoncalez@gmail.com, E-mail: evaldocarlosjr@gmail.com, E-mail: adriane.acm@hotmail.com [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil)

    2013-07-01

    The results of a static test of single event upset (SEU) produced by fast neutrons on an ISSI 4Mb SRAM memory are reported in this work. To perform the tests, it was built a platform based on a motherboard which is controlled by microprocessor, whose function is to perform the writing, reading and control of the memories under irradiation. The irradiation was performed with a set of 8 {sup 241}Am-Be neutrons source in a quasi-isotropic incidence. The SEU cross was calculated from the accumulated bit flip count. (author)

  6. Integral test on activation cross section of tag gas nuclides using fast neutron spectrum fields

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-03-01

    Activation cross sections of tag gas nuclides, which will be used for the failed fuel detection and location in FBR plants, were evaluated by the irradiation tests in the fast neutron spectrum fields in JOYO and YAYOI. The comparison of their measured radioactivities and the calculated values using the JENDL-3.2 cross section set showed that the C/E values ranged from 0.8 to 2.8 for the calibration tests in YAYOI and that the present accuracies of these cross sections were confirmed. (author)

  7. NeuLAND MRPC-based detector prototypes tested with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Caesar, C., E-mail: c.caesar@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Aumann, T. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Bemmerer, D. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Elekes, Z. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); ATOMKI, Debrecen (Hungary); Gonzalez-Diaz, D.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Reifarth, R.; Rossi, D.; Simon, H. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Stach, D.; Wagner, A.; Yakorev, D. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Zilges, A. [ATOMKI, Debrecen (Hungary)

    2012-01-01

    Recent results from a first irradiation of multi-gap resistive plate chambers with fast neutrons are presented. The counters have been built at GSI and FZD. The experiment was performed at the 'The Svedberg Laboratory' (TSL) in Uppsala, Sweden, utilizing a quasi-monoenergetic neutron beam with an energy E{sub n}=175 MeV. For a 2 Multiplication-Sign 4 gap prototype operated at E=100 kV/cm, an efficiency of (0.77 {+-}0.33)% was measured.

  8. Defects in Fast-Neutron Irradiated Nitrogen-Doped Czochralski Silicon after Annealing at High Temperature

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Fast-neutron irradiated nitrogen-doped Czochralski silicon (NCZ-Si) was annealed at 1100 ℃ for different time, then FTIR and optical microscope were used to study the behavior of oxygen. It is found that [Oi] increase at the early stage then decrease along with the increasing of anneal time. High density induced-defects can be found in the cleavage plane. By comparing NCZ-Si with Czochralski silicon (CZ-Si), [Oi] in NCZ-Si decrease more after anneal 24 h.

  9. Methodology for the use of proportional counters in pulsed fast neutron yield measurements

    OpenAIRE

    Tarifeño-Saldivia, Ariel; Mayer, Roberto E.; Pavez, Cristian; Soto, Leopoldo

    2011-01-01

    This paper introduces in full detail a methodology for the measurement of neutron yield and the necessary efficiency calibration, to be applied to the intensity measurement of neutron bursts where individual neutrons are not resolved in time, for any given moderated neutron proportional counter array. The method allows efficiency calibration employing the detection neutrons arising from an isotopic neutron source. Full statistical study of the procedure is descripted, taking into account cont...

  10. Regional spectroscopy of paraffin-embedded breast cancer tissue using pulsed terahertz transmission imaging

    Science.gov (United States)

    Bowman, Tyler; El-Shenawee, Magda; Campbell, Lucas

    2016-03-01

    This work seeks to obtain the properties of paraffin-embedded breast cancer tumor tissues using transmission imaging and spectroscopy. Formalin-fixed and paraffin-embedded breast tumors are first sectioned into slices of 20 μm and 30 μm and placed between two tsurupica slides. The slides are then scanned in a pulsed terahertz system using transmission imaging. The tissue regions in adjacent pathology section are compared to the transmission imaging scan in order to define a region of points over which to average the electrical properties results from the scan.

  11. Effect of Third-order Dispersion of Birefringent Fiber on Pulse Transmission

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of thirdorder dispersion on pulse transmission is discussed. The coupled nonlinear Schrdinger equations characterizing the birefringent singlemode fibers is solved numerically with combined consideration on chromatic dispersion, including second and thirdorder dispersions, polarization mode dispersion (PMD) and nonlinearity. Various simulation results are presented.

  12. Low index-contrast photonic bandgap fiber for transmission of short pulsed light

    DEFF Research Database (Denmark)

    Riishede, Jesper; Lægsgaard, Jesper; Broeng, Jes

    2004-01-01

    The use of low-index-contrast photonic bandgap (PBG) fiber for transmission of short pulsed light is discussed. PBG fibers have positive waveguide dispersion at long wavelengths at which conventional index-guiding fibers have negative waveguide dispersion. PBG fibers with low-index contrast can...

  13. [Effect of pulsed electromagnetic field on orthodontic tooth movement through transmission electromicroscopy].

    Science.gov (United States)

    Chen, Q

    1991-01-01

    This experiment is to observe the effect of pulsed electromagnetic field (PEMF) on orthodontic tooth movement of guinea pigs through transmission electron microscope (TEM). 14-days observations indicate that PEMF could accelerate the rate of orthodontic tooth movement as a result of the increase in quantity of active cell without changing the ultrastructures of cells and have no unfavorable effects on periodontal tissues.

  14. A low-power high-speed ultra-wideband pulse radio transmission system.

    Science.gov (United States)

    Wei Tang; Culurciello, E

    2009-10-01

    We present a low-power high-speed ultra-wideband (UWB) transmitter with a wireless transmission test platform. The system is specifically designed for low-power high-speed wireless implantable biosensors. The integrated transmitter consists of a compact pulse generator and a modulator. The circuit is fabricated in the 0.5-mum silicon-on-sapphire process and occupies 420 mum times 420 mum silicon area. The transmitter is capable of generating pulses with 1-ns width and the pulse rate can be controlled between 90 MHz and 270 MHz. We built a demonstration/testing system for the transmitter. The transmitter achieves a 14-Mb/s data rate. With 50% duty cycle data, the power consumption of the chip is between 10 mW and 21 mW when the transmission distance is from 3.2 to 4 m. The core circuit size is 70 mum times 130 mum.

  15. Understanding fast neutrons utilizing a water Cherenkov detector and a gas-filled detector at the soudan underground laboratory

    Science.gov (United States)

    Ghimire, Chiranjibi

    Many experiments are currently searching for Weakly Interactive Massive Particles (WIMPs), a well-motivated class of hypothetical dark matter candidates. These direct dark matter detection experiments are located in deep underground to shield from cosmic-ray muons and the fast neutrons they produce. Fast neutrons are particularly dangerous to WIMP detectors because they can penetrate a WIMP-search experiment's neutron shielding. Once inside, these fast neutrons can interact with high-Z material near the WIMP detector, producing slower neutrons capable of mimicking the expected WIMP signal. My research uses two detectors located in Soudan Underground Laboratory to understand fast neutron production by muons in an underground environment: a water-Cherenkov detector sensitive to fast neutrons; and a gas-filled detector sensitive to charged particles like muons. The different kinds of selection criterion and their efficiencies are reported in this thesis. This thesis estimate the number of high energy neutron-like candidates associated with a nearby muon by using data from both detector systems.

  16. A re-sequencing based assessment of genomic heterogeneity and fast neutron-induced deletions in a common bean cultivar

    Directory of Open Access Journals (Sweden)

    Jamie A. O'Rourke

    2013-06-01

    Full Text Available A small fast neutron mutant population has been established from Phaseolus vulgaris cv. Red Hawk. We leveraged the available P. vulgaris genome sequence and high throughput next generation DNA sequencing to examine the genomic structure of five Phaseolus vulgaris cv. Red Hawk fast neutron mutants with striking visual phenotypes. Analysis of these genomes identified three classes of structural variation; between cultivar variation, natural variation within the fast neutron mutant population, and fast neutron induced mutagenesis. Our analyses focused on the latter two classes. We identified 23 large deletions (>40 bp common to multiple individuals, illustrating residual heterogeneity and regions of structural variation within the common bean cv. Red Hawk. An additional 18 large deletions were identified in individual mutant plants. These deletions, ranging in size from 40 bp to 43,000 bp, are potentially the result of fast neutron mutagenesis. Six of the 18 deletions lie near or within gene coding regions, identifying potential candidate genes causing the mutant phenotype.

  17. Fluorescence anisotropy excitation by polarization-shaped laser pulses after transmission through a kagome fiber

    Science.gov (United States)

    Otto, J.; Patas, A.; Althoff, J.; Lindinger, A.

    2016-08-01

    We report improved fluorescence contrast between dyes by two-photon excitation with polarization-shaped laser pulses after transmission through a kagome fiber utilizing the anisotropy of the dye molecules. Particularly phase- and polarization-tailored pulse shapes are employed for two-photon excited fluorescence of dyes in a liquid environment at the distal end of the kagome fiber. The distortions due to the optical fiber properties are precompensated in order to receive predefined polarization-shaped laser pulses after the kagome fiber. This enables to optimally excite one dye in one polarization direction and simultaneously the other dye in the other polarization direction. The presented method has a high potential for endoscopic applications due to the unique properties of kagome fibers for guiding ultrashort laser pulses.

  18. 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 3He 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 3He 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 252Cf 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.

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

    CERN Document Server

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

    2015-01-01

    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...

  20. High energy fast neutrons from the Harwell variable energy cyclotron. I. Physical characteristics.

    Science.gov (United States)

    Goodhead, D T; Berry, R J; Bance, D A; Gray, P; Stedeford, J B

    1977-10-01

    A high energy fast neutron beam potentially suitable for radiotherapy was built at the Harwell variable energy cyclotron. The beam line is described and results are given of physical measurements on the fast neutron beams produced by 42 MeV deuterons on thick (4 mm) and thin (2 mm) beryllium targets. With 20 muA beam current the entrance dose rate in a phantom 150 cm from the target was about 130 rad min-1 with the thick target and about 60 rad min-1 with the thin target. Therefore, it is possible to use both the thin target and the relatively large target-skin distance of 150 cm to improve depth dose for radiotherapy or radiobiology. With this arrangement the dose rate decreased to 50% at depths in the phantom of 11.3-15.4 cm, depending on the field size. The use of primarily hydrogenous materials for shielding and collimation provided beam edge definition similar to that of 60Co teletherapy units, and off-axis radiation levels of approximately 1% which compare favorably with 14 MeV deuteron-tritium generators. The copper backing of the thin target became highly radioactive and an alterative material may be preferable. Biologic characteristics of the beam are described in a companion paper.

  1. Time-resolved Fast Neutron Radiography of Air-water Two-phase Flows

    Science.gov (United States)

    Zboray, Robert; Dangendorf, Volker; Mor, Ilan; Tittelmeier, Kai; Bromberger, Benjamin; Prasser, Horst-Michael

    Neutron imaging, in general, is a useful technique for visualizing low-Z materials (such as water or plastics) obscured by high-Z materials. However, when significant amounts of both materials are present and full-bodied samples have to be examined, cold and thermal neutrons rapidly reach their applicability limit as the samples become opaque. In such cases one can benefit from the high penetrating power of fast neutrons. In this work we demonstrate the feasibility of time-resolved, fast neutron radiography of generic air-water two-phase flows in a 1.5 cm thick flow channel with Aluminum walls and rectangular cross section. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany. Exposure times down to 3.33 ms have been achieved at reasonable image quality and acceptable motion artifacts. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two-phase flow parameters like the volumetric gas fraction, bubble size and bubble velocities have been measured.

  2. A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cortesi, M.; Prasser, H.-M. [Nuclear Energy and Safety Research Department, Paul Scherrer Institut, Villigen PSI 5234 (Switzerland); Mechanical Engineering Department, Swiss Federal Institute of Technology, Zurich 8092 (Switzerland); Dangendorf, V. [Ion and Neutron Radiation Department, Physikalisch-Technische Bundesanstalt, Braunschweig 38116 (Germany); Zboray, R. [Mechanical Engineering Department, Swiss Federal Institute of Technology, Zurich 8092 (Switzerland)

    2014-07-15

    We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.

  3. Cisplatin enhances the cytotoxicity of fast neutrons in a murine lymphoma cell line

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, B.; Benzina, S.; Ganansia-Leymarie, V. [Hopitaux Universitaires, Lab. de Cancerologie Experimentale et de Radiobiologie, Strasbourg CEDEX (France); Denis, J.M. [Universite Catholique de Louvain (UCL-RBNT), Lab. de Radiobiologie et de Radioprotection, Faculte de Medecine, Bruxelles (Belgium); Bergerat, J.P.; Dufour, P. [Hopitaux Universitaires, Lab. de Cancerologie Experimentale et de Radiobiologie, Strasbourg CEDEX (France); Gueulette, J. [Universite Catholique de Louvain (UCL-RBNT), Lab. de Radiobiologie et de Radioprotection, Faculte de Medecine, Bruxelles (Belgium); Bischoff, P. [Hopitaux Universitaires, Lab. de Cancerologie Experimentale et de Radiobiologie, Strasbourg CEDEX (France)]. E-mail: Pierre.Bischoff@ircad.u-strasbg.fr

    2004-02-01

    The utilization of high linear energy transfer (LET) radiations, such as fast neutrons or carbon ions (hadrontherapy), offers promising perspectives in radiotherapy. While it is well known that by combining radiotherapy and chemotherapy, important therapeutic advantages can be obtained to cure cancer, there have been, so far, very few investigations on the effects of treatments combining an irradiation with high-LET particles and cancer drugs. The present study was therefore undertaken to examine the effects of exposure to 65 MeV fast neutrons combined with cisplatin in a murine T cell lymphoma (RDM4) in vitro. The cells were irradiated at doses ranging from 2 to 8 Gy without or with addition of cisplatin shortly before the irradiation, at concentrations between 0.3 and 12.5 {mu}M. These treatments were applied concomitantly. Proliferation and apoptosis were assessed at different time intervals thereafter. The combination of irradiation with cisplatin was found to be more cytotoxic than either treatment alone. Furthermore, the cytotoxicity induced by this cotreatment resulted not only from apoptosis but also from other forms of cell death. (author)

  4. Determination of the fast neutrons spectra by the Elastic scattering method (n, p)

    CERN Document Server

    Elizalde, J

    1973-01-01

    This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spect...

  5. Computed Tomography with X-rays and Fast Neutrons for Restoration of Wooden Artwork

    Science.gov (United States)

    Osterloh, Kurt; Bellon, Carsten; Hohendorf, Stefan; Kolkoori, Sanjeevareddy; Wrobel, Norma; Nusser, Amélie; Freitag, Markus; Bücherl, Thomas; Bar, Doron; Mor, Ilan; Tamin, Noam; Weiss-Babai, Ruth; Bromberger, Benjamin; Dangendorf, Volker; Tittelmeier, Kai

    The objects of this investigation were sculptures taken from a ca. three hundred years old baroque epitaph of a church in Tönning, a town in Northern Germany. Around 1900 it was found in a disastrous state heavily damaged by wood-worm. At that time, the whole artwork was treated with the tar extract carbolineum as a remedy. Nowadays, this substance has been identified as carcinogenic, and its presence can be perceived by its stench and visually at certain spots on the surface where it has penetrated the covering paint. A gold-painted sculpture of a massive wooden skull was interrogated with X-rays and fast neutrons to investigate the internal distribution of the carbolineum. The X-ray tomography, with its excellent spatial resolution revealed galleries left over from the worm infestation in the outer areas and cracks in the central region. The golden color coating appeared as a thick and dense layer. In comparison the tomography with fast neutrons, though being of lower resolution and yet unresolved artefacts revealed sections of slightly different densities in the bulk of the wood. These differences we attribute to the differences in the distribution of the impregnant in the wood, visible due to its higher hydrogen content making it less transparent for neutrons.

  6. Numerical study of point spread function of a fast neutron radiography system based on scintillating-fiber array

    Institute of Scientific and Technical Information of China (English)

    ZHANG; FaQiang

    2007-01-01

    For a scintillating-fiber array fast-neutron radiography system, a point-spread- function computing model was introduced, and the simulation code was developed. The results of calculation show that fast-neutron radiographs vary with the size of fast neutron sources, the size of fiber cross-section and the imaging geometry. The results suggest that the following qualifications are helpful for a good point spread function: The cross-section of scintillating fibers not greater than 200μm×200μm, the size of neutron source as small as a few millimeters, the distance between the source and the scintillating fiber array greater than 1 m, and inspected samples placed as close as possible to the array. The results give suggestions not only to experiment considerations but also to the estimation of spatial resolution for a specific system.……

  7. Numerical study of point spread function of a fast neutron radiography system based on scintillating-fiber array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ For a scintillating-fiber array fast-neutron radiography system, a point-spread- function computing model was introduced, and the simulation code was developed. The results of calculation show that fast-neutron radiographs vary with the size of fast neutron sources, the size of fiber cross-section and the imaging geometry. The results suggest that the following qualifications are helpful for a good point spread function: The cross-section of scintillating fibers not greater than 200μm×200μm, the size of neutron source as small as a few millimeters, the distance between the source and the scintillating fiber array greater than 1 m, and inspected samples placed as close as possible to the array. The results give suggestions not only to experiment considerations but also to the estimation of spatial resolution for a specific system.

  8. Analysis of a measured neutron background below 6 MeV for fast-neutron imaging systems

    Science.gov (United States)

    Ide, K.; Becchetti, M. F.; Flaska, M.; Poitrasson-Riviere, A.; Hamel, M. C.; Polack, J. K.; Lawrence, C. C.; Clarke, S. D.; Pozzi, S. A.

    2012-12-01

    Detailed and accurate information on the neutron background is relevant for many applications that involve radiation detection, both for non-coincidence and coincidence countings. In particular, for the purpose of developing advanced neutron-detection techniques for nuclear non-proliferation and nuclear safeguards, the energy-dependent, ground-level, neutron-background information is needed. There are only a few previous studies available about the neutron background below 10 MeV, which is a typical neutron energy range of interest for nuclear non-proliferation and nuclear-safeguards applications. Thus, there is a potential for further investigation in this energy range. In this paper, neutron-background measurement results using organic-liquid scintillation detectors are described and discussed, with a direct application in optimization simulations of a fast-neutron imager based on liquid scintillators. The measurement was performed in summer 2011 in Ann Arbor, Michigan, USA, and the measurement setup consisted of several EJ-309 liquid scintillators and a fast waveform digitizer. The average neutron flux below 6 MeV was measured to be approximately 4e-4 counts/cm2/s. In addition, the relationship between the neutron-background count rate and various environmental quantities, such as humidity, at Earth's ground level was investigated and the results did not reveal any straightforward dependences. The measured pulse height distribution (PHD) was unfolded to determine the energy spectrum of the background neutrons. The unfolded neutron-background spectrum was implemented to a previously-created MCNPX-PoliMi model of the neutron-scatter camera and simple-backprojection images of the background neutrons were acquired. Furthermore, a simulated PHD was obtained with the MCNPX-PoliMi code using the "Cosmic-Ray Shower Library" (CRY) source sub-routine which returns various types of radiation, including neutrons and photons at a surface, and accounts for solar cycle

  9. Neutron diffraction analysis of Cr-Ni-Mo-Ti austenitic steel after cold plastic deformation and fast neutrons irradiation

    Science.gov (United States)

    Voronin, V. I.; Valiev, E. Z.; Berger, I. F.; Goschitskii, B. N.; Proskurnina, N. V.; Sagaradze, V. V.; Kataeva, N. F.

    2015-04-01

    A quantitative assessment is presented of the dislocation density and relative fractions of edge and screw dislocations in reactor-steel samples 16Cr-15Ni-3Mo-1Ti subjected to preliminary cold deformation by rolling and subsequent fast neutron irradiation using neutron diffraction analysis. The Williamson-Hall modified method was used for calculations. It is shown that the fast neutron irradiation leads to a decrease in the density of dislocations that appeared after samples deformation. The applicability of neutron diffraction analysis to the examination of dislocation structure of deformed and irradiated materials is shown.

  10. Accelerated multidimensional radiofrequency pulse design for parallel transmission using concurrent computation on multiple graphics processing units.

    Science.gov (United States)

    Deng, Weiran; Yang, Cungeng; Stenger, V Andrew

    2011-02-01

    Multidimensional radiofrequency (RF) pulses are of current interest because of their promise for improving high-field imaging and for optimizing parallel transmission methods. One major drawback is that the computation time of numerically designed multidimensional RF pulses increases rapidly with their resolution and number of transmitters. This is critical because the construction of multidimensional RF pulses often needs to be in real time. The use of graphics processing units for computations is a recent approach for accelerating image reconstruction applications. We propose the use of graphics processing units for the design of multidimensional RF pulses including the utilization of parallel transmitters. Using a desktop computer with four NVIDIA Tesla C1060 computing processors, we found acceleration factors on the order of 20 for standard eight-transmitter two-dimensional spiral RF pulses with a 64 × 64 excitation resolution and a 10-μsec dwell time. We also show that even greater acceleration factors can be achieved for more complex RF pulses. Copyright © 2010 Wiley-Liss, Inc.

  11. Pulse-transmission Oscillators: Autonomous Boolean Models and the Yeast Cell Cycle

    Science.gov (United States)

    Sevim, Volkan; Gong, Xinwei; Socolar, Joshua

    2010-03-01

    Models of oscillatory gene expression typically involve a constitutively expressed or positively autoregulated gene which is repressed by a negative feedback loop. In Boolean representations of such systems, which include the repressilator and relaxation oscillators, dynamical stability stems from the impossibility of satisfying all of the Boolean rules at once. We consider a different class of networks, in which oscillations are due to the transmission of a pulse of gene activation around a ring. Using autonomous Boolean modeling methods, we show how the circulating pulse can be stabilized by decoration of the ring with certain feedback and feed-forward motifs. We then discuss the relation of these models to ODE models of transcriptional networks, emphasizing the role of explicit time delays. Finally, we show that a network recently proposed as a generator of cell cycle oscillations in yeast contains the motifs required to support stable transmission oscillations.

  12. A long-pulse repetitive operation magnetically insulated transmission line oscillator.

    Science.gov (United States)

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

    2014-05-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

  13. Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector.

    Science.gov (United States)

    Pöllänen, R; Siiskonen, T

    2014-08-01

    The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum.

  14. Coded moderator approach for fast neutron source detection and localization at standoff

    Science.gov (United States)

    Littell, Jennifer; Lukosi, Eric; Hayward, Jason; Milburn, Robert; Rowan, Allen

    2015-06-01

    Considering the need for directional sensing at standoff for some security applications and scenarios where a neutron source may be shielded by high Z material that nearly eliminates the source gamma flux, this work focuses on investigating the feasibility of using thermal neutron sensitive boron straw detectors for fast neutron source detection and localization. We utilized MCNPX simulations to demonstrate that, through surrounding the boron straw detectors by a HDPE coded moderator, a source-detector orientation-specific response enables potential 1D source localization in a high neutron detection efficiency design. An initial test algorithm has been developed in order to confirm the viability of this detector system's localization capabilities which resulted in identification of a 1 MeV neutron source with a strength equivalent to 8 kg WGPu at 50 m standoff within ±11°.

  15. Use of CR 39 Films for Evaluation of Shielding Efficacy of Materials against Fast Neutrons

    Directory of Open Access Journals (Sweden)

    S. Kumar

    1992-10-01

    Full Text Available CR-39 films have been used for evaluation of neutron shielding of metal alloys, different types of rubbers, sand polymers, etc. These films have been chosen because of their ability to record fast neutrons from 200 keV-10 MeV and their insensitivity to gamma radiations. Tenth value layer (TVL for the materials studied varies from 10.5 to 28.6 cm. In addition, the values of TVL have also been computed for standard material, such as Al, steel, etc. Using neutron removal cross-section data, the results have been compared with those of experimentally determined values. The results seem to be in agreement within approximate 10 per cent variation.

  16. Magnetization studies of YBa 2Cu 3O 7-x irradiated by fast neutrons

    Science.gov (United States)

    Wisniewski, A.; Baran, M.; Przysłupski, P.; Szymczak, H.; Pajaczkowska, A.; Pytel, B.; Pytel, K.

    1988-02-01

    Studies of the effect of fast neutron damage on the magnetic hysteresis of YBa 2Cu 3O 7-x ceramic samples subjected to fluence of neutrons of 2∗10 16 n/cm 2 up to 6∗10 17 n/cm 2 have been performed. irradiation up to dose of 1∗10 17 did not cause any change in the critical temperature. However it causes a strong increase of the magnetic hysteresis which is presumably connected with the creation of defects. The critical current density at 77 K in H = 10 k0e for the sample irradiated with the dose 1∗10 17 n/cm 2 was estimated to be 520 A/cm 2 as compared to 29 A/cm 2 for the reference non-irradiated sample, non-irradiated sample.

  17. 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.

  18. Theoretical study and calculation of the response of a fast neutron dosemeter based on track detection

    Energy Technology Data Exchange (ETDEWEB)

    Decossas, J.L.; Vareille, J.C.; Moliton, J.P.; Teyssier, J.L. (Limoges Univ., 87 (France). Lab. d' Electronique des Polymeres sous Faisceaux Ioniques)

    1983-01-01

    A fast neutron dosemeter is generally composed of a radiator in which n-p elastic scattering occurs and a detector which registers protons. A theoretical study, and the calculation (FORTRAN program) of the response of such a dosemeter is presented involving two steps: 1) The proton flux emerging from a thick radiator on which monoenergetic neutrons are normally incident is studied. This is characterised by its energy spectrum depending on the neutron energy and on the radiator thickness. 2) Proton detection being achieved with a solid state nuclear track detector whose performance is known, the number of registered tracks are calculated. The dosemeter sensitivity (tracks cm/sup -2/. Sv/sup -1/) is deduced. Then, the calculations show that it is possible to optimise the radiator thickness to obtain the smallest variation in sensitivity with neutron energy. The theoretical results are in good agreement with the experimental ones found in the literature.

  19. Unfolding the fast neutron spectra of a BC501A liquid scintillation detector using GRAVEL method

    CERN Document Server

    Chen, Yonghao; Lei, Jiarong; An, Li; Zhang, Xiaodong; Shao, Jianxiong; Zheng, Pu; Wang, Xinhua

    2013-01-01

    Accurate knowledge of the neutron energy spectra is useful in basic research and applications. The overall procedure of measuring and unfolding the fast neutron energy spectra with BC501A liquid scintillation detector is described. The recoil proton spectrum of Am-Be neutrons was obtained experimentally. With the NRESP7 code, the response matrix of detector was simulated. Combining the recoil proton spectrum and response matrix, the unfolding of neutron spectra was performed by GRAVEL iterative algorithm. A MatLab program based on the GRAVEL method was developed. The continuous neutron spectrum of Am-Be source and monoenergetic neutron spectrum of D-T source have been unfolded successfully and are in good agreement with their standard reference spectra. The unfolded Am-Be spectrum are more accurate than the spectra unfolded by artificial neural networks in recent years.

  20. Unfolding the fast neutron spectra of a BC501A liquid scintillation detector using GRAVEL method

    Science.gov (United States)

    Chen, YongHao; Chen, XiMeng; Lei, JiaRong; An, Li; Zhang, XiaoDong; Shao, JianXiong; Zheng, Pu; Wang, XinHua

    2014-10-01

    Accurate knowledge of the neutron energy spectra is useful in basic research and applications. The overall procedure of measuring and unfolding the fast neutron energy spectra with BC501A liquid scintillation detector is described. The recoil proton spectrum of 241Am-Be neutrons was obtained experimentally. With the NRESP7 code, the response matrix of detector was simulated. Combining the recoil proton spectrum and response matrix, the unfolding of neutron spectra was performed by GRAVEL iterative algorithm. A MatLab program based on the GRAVEL method was developed. The continuous neutron spectrum of 241Am-Be source and monoenergetic neutron spectrum of D-T source have been unfolded successfully and are in good agreement with their standard reference spectra. The unfolded 241Am-Be spectrum are more accurate than the spectra unfolded by artificial neural networks in recent years.

  1. Radiolysis of Boric Acid Solutions under Mixed Thermal and Fast Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Im, Heejung; Choi, Ke Chon; Yeon, Jeiwon; Song, Kyuseok; Jung Hoansung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    The thermal neutron irradiation of water samples containing neutron absorbers has not been published except for a paper reporting the experimental data obtained at high temperatures. However, irradiation or simulations of water and voluminous liquid samples with fast neutrons and gamma rays are frequently discussed in several published papers. Several water samples containing {sup 10}B-enriched boric acid, and natural and {sup 10}B-enriched mixed boric acids in the range of 0 to 2000 μg/mL for the function of {sup 10}B concentration, were irradiated to study the radiolysis of the cooling water containing boric acid. The concentration of natural boron in the primary coolant of pressurized water reactors (PWRs) is known to start at 1500 μg/mL, and boric acid is used for the purpose of nuclear reaction control.

  2. Texas Instruments TPS7H1101-SP Fast Neutron Irradiation Results

    CERN Document Server

    The ATLAS collaboration

    2015-01-01

    Texas Instruments’s TPS7H1101-SP is an ultra low drop-out voltage regulator that operates under a wide range of input voltages - 1.5 to 7V. It can operate under a load of at most 3A and is radiation qualified by Texas Instruments for Total Ionizing Dose (TID) effects and Single Event Effects (SEE). For the application of the TPS7H1101-SP on the Front End Boards (FEBs) of the New Small Wheel (NSW) of the ATLAS detector, we study its susceptibility to a third kind of radiation effect -displacement damage- and present its performance in fast neutrons up to a dose of 6 x 10$^{14}$ 1MeVNE/cm$^{2}$.

  3. 640 Gbaud (1.28 Tbit/s/ch) optical Nyquist pulse transmission over 525 km with substantial PMD tolerance.

    Science.gov (United States)

    Harako, Koudai; Seya, Daiki; Hirooka, Toshihiko; Nakazawa, Masataka

    2013-09-01

    We report a substantial increase in PMD tolerance in a single-channel ultrahigh-speed transmission using optical Nyquist pulses. We demonstrate both analytically and experimentally a large reduction in depolarization-induced crosstalk with optical Nyquist pulses, which is one of the major obstacles facing polarization-multiplexed ultrashort pulse transmission. By taking advantage of the high PMD tolerance, a low-penalty 1.28 Tbit/s/ch optical Nyquist TDM transmission at 640 Gbaud was achieved over 525 km.

  4. Development of ionization technique for measurement of fast neutron induced fission products yields of {sup 237}Np

    Energy Technology Data Exchange (ETDEWEB)

    Goverdovski, A.A.; Khryachkov, V.A.; Ketlerov, V.V.; Mitrofanov, V.F.; Ostapenko, Yu.B.; Semenova, N.N.; Fomichev, A.N.; Rodina, L.F. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    Twin gridded ionization chamber and corresponding software was designed for measurements of masses, kinetic energies and nuclear charges of fission fragments from fast neutron induced fission of {sup 237}Np. The ionization detector design, electronics, data acquisition and processing system and the test results are presented in this paper. (J.P.N.)

  5. Inverse magnetocaloric effect in Ce(Fe0.96Ru0.04)2: Effect of fast neutron irradiation

    Science.gov (United States)

    Dube, V.; Mishra, P. K.; Rajarajan, A. K.; Prajapat, C. L.; Sastry, P. U.; Thakare, S. V.; Singh, M. R.; Ravikumar, G.

    2013-02-01

    We have shown the effect of fast neutron irradiation on the magnetic phase transition and magnetocaloric effect (MCE) in a doped Ce(Fe0.96Ru0.04)2, intermettalic. We show that this leads to suppression of MCE and a to a disordered ferromagnetic phase.

  6. Influence of temperature on the behaviour of INTEGRAL n-type HPGe detectors irradiated with fast neutrons

    CERN Document Server

    Kandel, B; Albernhe, F; Frabel, P; Cordier, B; Tauzin, G; Crespin, S; Coszach, R; Denis, J M; Leleux, P

    1999-01-01

    Several INTEGRAL n-type HPGe detectors have been irradiated by fast neutrons at different temperatures and their performances have been evaluated. Their behaviour during warm-up and cool-down cycles following the irradiations show evidence for irreversible temperature effects above 100 K. The detectors recovery after annealing was also studied.

  7. X-Ray- and fast neutron induced mutations in Arabidopsis thaliana, and the effect of dithiothreitol upon the mutant spectrum

    NARCIS (Netherlands)

    Dellaert, L.M.W.

    1980-01-01

    The genetic effects of X-ray and fast neutron seed-irradiation of Arabidopsis thaliana (L.) Heynh., and the influence of a pre-irradiation treatment with the radio-protector dithiothreitol (DTT), are the main subjects of this thesis.Chapters I and II deal with the effects of radiation - with or with

  8. Development of ionization technique for measurement of fast neutron induced fission products yields of {sup 237}Np

    Energy Technology Data Exchange (ETDEWEB)

    Goverdovski, A.A.; Khryachkov, V.A.; Ketlerov, V.V.; Mitrofanov, V.F.; Ostapenko, Yu.B.; Semenova, N.N.; Fomichev, A.N.; Rodina, L.F. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    Twin gridded ionization chamber and corresponding software was designed for measurements of masses, kinetic energies and nuclear charges of fission fragments from fast neutron induced fission of {sup 237}Np. The ionization detector design, electronics, data acquisition and processing system and the test results are presented in this paper. (J.P.N.)

  9. Pulse position modulation for a subcarrier-multiplexed optical fiber transmission system

    Science.gov (United States)

    Wickramasinghe, V. R.; Ghassemlooy, Zabih F.

    1996-11-01

    Subcarrier multiplexed (SCM) optical network s offer a near to medium term alternative solution over high cost, evolving digital technology to distribute broadband services. Majority of existing systems are based on analogue optical transmission techniques and their principle disadvantage is the sensitivity to noise and system nonlinearities. Therefore, conventional SCM systems impose stringent noise and linearity requirements and as a result their performance is limited. A simple and attractive solution is to introduce an appropriate second stage modulator in order to improve the receiver sensitivity, hence the system performance.In this paper a SCM optical transmission system employing pulse position modulation as a second stage modulator, for transmission of video, audio and data channels is reported. Signal to noise ratio measurements obtained shows an improvement in optical receiver sensitivity compared with standard SCM systems.

  10. Transmission line pulse system for avalanche characterization of high power semiconductor devices

    Science.gov (United States)

    Riccio, Michele; Ascione, Giovanni; De Falco, Giuseppe; Maresca, Luca; De Laurentis, Martina; Irace, Andrea; Breglio, Giovanni

    2013-05-01

    Because of the increasing in power density of electronic devices for medium and high power application, reliabilty of these devices is of great interest. Understanding the avalanche behaviour of a power device has become very important in these last years because it gives an indication of the maximum energy ratings which can be seen as an index of the device ruggedness. A good description of this behaviour is given by the static IV blocking characteristc. In order to avoid self heating, very relevant in high power devices, very short pulses of current have to be used, whose value can change from few milliamps up to tens of amps. The most used method to generate short pulses is the TLP (Transmission Line Pulse) test, which is based on charging the equivalent capacitance of a transmission line to high value of voltage and subsequently discharging it onto a load. This circuit let to obtain very short square pulses but it is mostly used for evaluate the ESD capability of semiconductor and, in this environment, it generates pulses of low amplitude which are not high enough to characterize the avalanche behaviour of high power devices . Advanced TLP circuit able to generate high current are usually very expensive and often suffer of distorption of the output pulse. In this article is proposed a simple, low cost circuit, based on a boosted-TLP configuration, which is capable to produce very square pulses of about one hundreds of nanosecond with amplitude up to some tens of amps. A prototype is implemented which can produce pulses up to 20A of amplitude with 200 ns of duration which can characterize power devices up to 1600V of breakdown voltage. Usage of microcontroller based logic make the circuit very flexible. Results of SPICE simulation are provided, together with experimental results. To prove the effectiveness of the circuit, the I-V blocking characteristics of two commercial devices, namely a 600V PowerMOS and a 1200V Trench-IGBT, are measured at different

  11. Superluminal reflection and transmission of light pulses via resonant four-wave mixing in cesium vapor.

    Science.gov (United States)

    Jiang, Qichang; Zhang, Yan; Wang, Dan; Ahrens, Sven; Zhang, Junxiang; Zhu, Shiyao

    2016-10-17

    We report the experimental manipulation of the group velocities of reflected and transmitted light pulses in a degenerate two-level atomic system driven by a standing wave, which is created by two counter-propagating light beams of equal frequencies but variable amplitudes. It is shown that the light pulse is reflected with superluminal group velocity while the transmitted pulse propagates from subluminal to superluminal velocities via changing the power of the backward coupling field. We find that the simultaneous superluminal light reflection and transmission can be reached when the power of the backward field becomes closer or equal to the forward power, in this case the periodical absorption modulation for photonic structure is established in atoms. The theoretical discussion shows that the anomalous dispersion associated with a resonant absorption dip within the gain peak due to four-wave mixing leads to the superluminal reflection, while the varying dispersion from normal to anomalous at transparency, transparency within absorption, and electromagnetically induced absorption windows leads to the subluminal to superluminal transmission.

  12. Development of a dual phantom technique for measuring the fast neutron component of dose in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Yoshinori, E-mail: yosakura@rri.kyoto-u.ac.jp; Tanaka, Hiroki; Kondo, Natsuko; Kinashi, Yuko; Suzuki, Minoru; Masunaga, Shinichiro; Ono, Koji; Maruhashi, Akira [Kyoto University Research Reactor Institute, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2015-11-15

    Purpose: Research and development of various accelerator-based irradiation systems for boron neutron capture therapy (BNCT) is underway throughout the world. Many of these systems are nearing or have started clinical trials. Before the start of treatment with BNCT, the relative biological effectiveness (RBE) for the fast neutrons (over 10 keV) incident to the irradiation field must be estimated. Measurements of RBE are typically performed by biological experiments with a phantom. Although the dose deposition due to secondary gamma rays is dominant, the relative contributions of thermal neutrons (below 0.5 eV) and fast neutrons are virtually equivalent under typical irradiation conditions in a water and/or acrylic phantom. Uniform contributions to the dose deposited from thermal and fast neutrons are based in part on relatively inaccurate dose information for fast neutrons. This study sought to improve the accuracy in the dose estimation for fast neutrons by using two phantoms made of different materials in which the dose components can be separated according to differences in the interaction cross sections. The development of a “dual phantom technique” for measuring the fast neutron component of dose is reported. Methods: One phantom was filled with pure water. The other phantom was filled with a water solution of lithium hydroxide (LiOH) capitalizing on the absorbing characteristics of lithium-6 (Li-6) for thermal neutrons. Monte Carlo simulations were used to determine the ideal mixing ratio of Li-6 in LiOH solution. Changes in the depth dose distributions for each respective dose component along the central beam axis were used to assess the LiOH concentration at the 0, 0.001, 0.01, 0.1, 1, and 10 wt. % levels. Simulations were also performed with the phantom filled with 10 wt. % {sup 6}LiOH solution for 95%-enriched Li-6. A phantom was constructed containing 10 wt. % {sup 6}LiOH solution based on the simulation results. Experimental characterization of the

  13. Monte Carlo simulation of the response to fast neutrons of a multi-gap RPC (MRPC) by using the GEANT4 code

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, J. T.; Jo, H. Y.; Jamil, M.; Jeon, Y. J. [Konkuk University, Seoul (Korea, Republic of)

    2012-04-15

    This article reports the simulated response to fast neutrons of a multi-gap resistive plate chamber (MRPC) by using the GEANT4 MC code. In this study, a thin polyethylene layer, which acted as the converter material for the detection of fast neutrons, was coated on the surface of the MRPC, which acts as the converter material for the detection of fast neutrons. The converter based on the polyethylene material improved the chamber's ability to detect fast neutrons. By employing the GEANT4 MC code, fast neutrons were inserted into the converter-based MRPC chamber in the energy range of 1.0 - 20.0 MeV. The response of the polyethylene-coated MRPC were evaluated as a function of the neutron energy by using the QGSP{sub B}ERT{sub H}P and the QGSP{sub B}IC{sub H}P physics list with the GEANT4 code. For a 0.13-mm converter thickness, a detection efficiency of 6.4x10{sup -3} were found for fast neutrons with an energy of E{sub n} = 6.0 by the QGSP{sub B}ERT{sub H}P physics list. The simulation test further confirmed that a higher response of the fast neutrons could be achieved if the converter thickness were to be increased. A detailed outline of the simulation test and the obtained results are presented.

  14. Relative biological effectiveness of fast neutrons in a multiorgan assay for apoptosis in mouse.

    Science.gov (United States)

    Lee, Hae-June; Kim, Joong-Sun; Moon, Changjong; Kim, Jong-Choon; Jo, Sung-Kee; Kim, Sung-Ho

    2008-04-01

    This study compared the effects of high linear energy transfer (LET) fast neutrons on the induction of apoptosis in several tissue types (hair follicle, intestine crypt, testis) of ICR mouse exposed to low LET 60Co gamma-rays. The changes that occurred from 0 to 24 h after exposing the mice to either 2 Gy of gamma-rays (2 Gy/min) or 0.8 Gy of neutrons (94 mGy/min, 35 MeV) were examined. The maximum frequency of apoptosis was observed at 8 or 12 h after irradiation. The mice that had received 0-8 Gy of gamma-rays or 0-1.6 Gy of neutrons were examined 8 h after irradiation. The best-fitting dose-response curves were linear-quadratic, and there was a significant relationship between the number of apoptotic cells and the dose. The stained products in the TUNEL-positive cells or bodies correlated with the typical morphologic characteristics of apoptosis observed by optical microscopy. In the follicles showing an apoptosis frequency between 2 and 14 per hair follicle, the relative biological effectiveness (RBE) of the neutrons in the small and large follicles was 2.09 +/- 0.31 and 2.15 +/- 0.18, respectively. In the intestine crypts showing an apoptosis frequency between 1 and 3 per crypt, the RBE of the neutrons was 4.03 +/- 0.06 and 3.87 +/- 0.04 in the base and total crypts, respectively. The RBE of the neutrons in the seminiferous tubule showing an apoptosis frequency between 0.5 and 2 per tubule was 5.18 +/- 0.06. The results determined the time-response relations and the RBE for fast neutron-induced apoptosis in several organs at the same time. The differences in RBE observed between the high and low LET radiation and it is believed that the difference in the DSB repair capacity in hair follicle, intestine crypt, and seminiferous tubule cells plays a role in determining the RBE of the high-LET radiation for the induced apoptotic cell formation.

  15. Radiation hardness tests of piezoelectric actuators with fast neutrons at liquid helium temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fouaidy, M.; Martinet, G.; Hammoudi, N.; Chatelet, F.; Olivier, A.; Blivet, S.; Galet, F. [CNRS-IN2P3-IPN Orsay, Orsay (France)

    2007-07-01

    Piezoelectric actuators, which are integrated into the cold tuning system and used to compensate the small mechanical deformations of the cavity wall induced by Lorentz forces due to the high electromagnetic surface field, may be located in the radiation environment during particle accelerator operation. In order to provide for a reliable operation of the accelerator, the performance and life time of piezoelectric actuators ({approx}24.000 units for ILC) should not show any significant degradation for long periods (i.e. machine life duration: {approx}20 years), even when subjected to intense radiation (i.e. gamma rays and fast neutrons). An experimental program, aimed at investigating the effect of fast neutrons radiation on the characteristics of piezoelectric actuators at liquid helium temperature (i.e. T{approx}4.2 K), was proposed for the working package WPNo.8 devoted to tuners development in the frame of CARE project. A neutrons irradiation facility, already installed at the CERI cyclotron located at Orleans (France), was upgraded and adapted for actuators irradiations tests purpose. A deuterons beam (maximum energy and beam current: 25 MeV and 35{mu}A) collides with a thin (thickness: 3 mm) beryllium target producing a high neutrons flux with low gamma dose ({approx}20%): a neutrons fluence of more than 10{sup 14} n/cm{sup 2} is achieved in {approx}20 hours of exposure. A dedicated cryostat was developed at IPN Orsay and used previously for radiation hardness test of calibrated cryogenic thermometers and pressure transducers used in LHC superconducting magnets. This cryostat could be operated either with liquid helium or liquid argon. This irradiation facility was upgraded for allowing fast turn-over of experiments and a dedicated experimental set-up was designed, fabricated, installed at CERI and successfully operated for radiation hardness tests of several piezoelectric actuators at T{approx}4.2 K. This new apparatus allows on-line automatic measurements

  16. Long-distance pulse propagation on high-frequency dissipative nonlinear transmission lines/resonant tunneling diode line cascaded maps

    Energy Technology Data Exchange (ETDEWEB)

    Klofai, Yerima [Department of Physics, Higher Teacher Training College, University of Maroua, PO Box 46 Maroua (Cameroon); Essimbi, B Z [Department of Physics, Faculty of Science, University of Yaounde 1, PO Box 812 Yaounde (Cameroon); Jaeger, D, E-mail: bessimb@yahoo.fr [ZHO, Optoelectronik, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany)

    2011-10-15

    Pulse propagation on high-frequency dissipative nonlinear transmission lines (NLTLs)/resonant tunneling diode line cascaded maps is investigated for long-distance propagation of short pulses. Applying perturbative analysis, we show that the dynamics of each line is reduced to an expanded Korteweg-de Vries-Burgers equation. Moreover, it is found by computer experiments that the soliton developed in NLTLs experiences an exponential amplitude decay on the one hand and an exponential amplitude growth on the other. As a result, the behavior of a pulse in special electrical networks made of concatenated pieces of lines is closely similar to the transmission of information in optical/electrical communication systems.

  17. Broadband THz pulse emission and transmission properties of nanostructured Pt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Mingzhe [Department of Physics and Electronics, Liupanshui Normal University, Liupanshui, Guizhou 553004 (China); College of Electronics and Information, Guizhou University, Huaxi 550025, Guiyang, Guizhou (China); Mu, Kaijun; Zhang, Cunlin [Department of Physics, Capital Normal University, Yuquan Road 100082, Beijing (China); Gu, Haoshuang, E-mail: guhs@hubu.edu.cn [Department of Electronic Sci& Tech, Hubei University, Xueyuan Road 430062, Wuhan, Hubei (China); Ding, Zhao [College of Electronics and Information, Guizhou University, Huaxi 550025, Guiyang, Guizhou (China)

    2015-10-01

    The THz transmission and emitting properties of a composite metallic nanostructure, composed of Ag nanowires electrodeposited in an anodic aluminum oxide (AAO) template and a Pt thin film, were investigated by using a femtosecond pulse laser irradiation. The microstructure of the above sub-wavelength nanostructure was investigated by XRD, SEM, AFM and TEM. The results indicated that the thickness of the Pt thin film was about 200 nm and the Ag nanowire array had a sparse and random distribution inside the AAO template, with a length distribution in the range of 10–25 μm. The THz radiation properties of above sub-wavelength nanostructure indicated that the generated THz fluence from the Pt film was a magnitude of μW scale with a broadband frequency range and its subsequent transmission could be significantly improved by the better impedance matching property of the Ag nanowire embedded AAO film compared with that of the empty AAO film.

  18. Hundred-picosecond narrowband chirped-pulse generation in an Yb:YAG regenerative amplifier using transmission gratings

    Science.gov (United States)

    Hwang, SungIn; Tokita, Shigeki; Kawashima, Toshiyuki; Nishioka, Hajime; Kawanaka, Junji

    2016-12-01

    We have demonstrated a seed source for an optical parametric chirped pulse amplification pumping source through a cryogenically cooled Yb:YAG regenerative amplifier, which can vary the pulse duration depending on the number of passes and generate a very high chirp rate. The Fourier-transform-limited pulse duration of 10 ps was extended to a few hundred picoseconds (109 to 165 ps) to prevent damage to the gain medium in the subsequent high-pulse-energy pumping source, which was seeded by the regenerative amplifier. This was achieved by inserting a transmission diffraction grating pair inside the cavity of the regenerative amplifier. The variable pulse duration could be set between 109 and 165 ps by electronically adjusting the pass number of pulses inside the cavity. The stretched pulse duration and the spectral width as functions of the pass number were characterized by considering the dispersion from the grating stretcher as well as the gain narrowing effect.

  19. Radioactive Ion Beam Production by Fast-Neutron-Induced Fission in Actinide Targets at EURISOL

    CERN Document Server

    Herrera-Martínez, Adonai

    The European Isotope Separation On-Line Radioactive Ion Beam Facility (EURISOL) is set to be the 'next-generation' European Isotope Separation On-Line (ISOL) Radioactive Ion Beam (RIB) facility. It will extend and amplify current research on nuclear physics, nuclear astrophysics and fundamental interactions beyond the year 2010. In EURISOL, the production of high-intensity RIBs of specific neutron-rich isotopes is obtained by inducing fission in large-mass actinide targets. In our contribution, the use of uranium targets is shown to be advantageous to other materials, such as thorium. Therefore, in order to produce fissions in U-238 and reduce the plutonium inventory, a fast neutron energy spectrum is necessary. The large beam power required to achieve these RIB levels requires the use of a liquid proton-to-neutron converter. This article details the design parameters of the converter, with special attention to the coupled neutronics of the liquid converter and fission target. Calculations performed with the ...

  20. Fast Neutron Tomography of Low-Z Object in High-Z Material Shielding

    Science.gov (United States)

    Babai, Ruth Weiss; Sabo-Napadensky, Iris; Bar, Doron; Mor, Ilan; Tamim, Noam; Dangendorf, Volker; Tittelmeier, Kai; Bromberger, Benjamin; Weierganz, Mathias

    The technique and first results of Fast Neutron Tomography (FNCT) experiments are presented which are performed at the accelerator facility of PTB, Germany. A high-intensity neutron beam of broad spectral distribution with an average energy of 5.5 MeV, was produced by 11.5 MeV deuterons impinging upon a thick beryllium target. The capability of FNCT for high contrast imaging of low-Z materials embedded in thick high-Z shielding materials is demonstrated, which is superior to more conventional high-energy X-ray imaging techniques. For demonstrating the method special test objects were prepared: One consisted of an assembled polyethylene cylinder with holes of various diameters and directions drilled in its surface and inner parts. The plastic phantom was inserted into lead cylinders of different thicknesses. The detector system consisted of a plastic scintillator along with a dedicated optics, image-intensifier and a CCD camera. Two scintillator screens were compared: a bulk plastic scintillator screen and a fibres optical scintillator screen. The tomographic scans were taken in two geometrical configurations: cone beam and semi-fan beam configuration. The image quality favours the semi-fan beam configuration which on the other hand is more time consuming The obtained tomographic images and a comparison of the imaging quality between the different experimental conditions will be presented.

  1. Development and performance of the Fast Neutron Imaging Telescope for SNM detection

    Science.gov (United States)

    Ryan, James M.; Bravar, Ulisse; Flückiger, Erwin O.; Macri, John R.; McConnell, Mark L.; Pirard, Benoit; Woolf, Richard S.

    2008-04-01

    FNIT (the Fast Neutron Imaging Telescope), a detector with both imaging and energy measurement capabilities, sensitive to neutrons in the range 0.8-20 MeV, was initially conceived to study solar neutrons as a candidate design for the Inner Heliosphere Sentinel (IHS) spacecraft of NASA's Solar Sentinels program and successively reconfigured to locate fission neutron sources. By accurately identifying the position of the source with imaging techniques and reconstructing the Watt spectrum of fission neutrons, FNIT can detect samples of special nuclear material (SNM), including heavily shielded and masked ones. The detection principle is based on multiple elastic neutron-proton scatterings in organic scintillators. By reconstructing n-p event locations and sequence and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron sources identified. We describe the design of the FNIT prototype and present its energy reconstruction and imaging performance, assessed by exposing FNIT to a neutron beam and to a Pu fission neutron source.

  2. Transient and chronic neurological complications of fast neutron radiation for adenocarcinoma of the prostate

    Energy Technology Data Exchange (ETDEWEB)

    Russell, K.J.; Laramore, G.E.; Wiens, L.W.; Griffeth, J.T.; Koh, W.J.; Griffin, B.R.; Austin-Seymour, M.M.; Griffin, T.W. (Washington Univ., Seattle, WA (USA). Lab. of Radiation Ecology); Krieger, J.N. (Washington University, Seattle (USA). Department of Urology); Davis, L.W. (Albert Einstein Coll. of Medicine, Bronx, NY (USA))

    1990-07-01

    The records of 132 patients participating in clinical trials using fast neutron (n = 94), mixed neutron and photon (n = 16), or conventional photon (n = 22) irradiation for primary management of prostatic cancer were retrospectively reviewed to assess treatment-related neurological complications. With a median follow-up of 14 months (range 1 to 101 months), 31/132 patients (26 neutron, 3 mixed beam, 2 photon) have experienced either sciatica beginning during or shortly after treatment, or diminished bladder or bowel continence that developed at a median time of 6.5 months following treatment. Sciatica responded to oral steroids and was usually self-limited, whereas sphincter dysfunction appears to be permanent. Pre-treatment risk factors for complications included a history of hypertension, diabetes, cigarette smoking or peripheral vascular disease, with 81% of affected patients having one or more risk factors compared witn 55% of unaffected patients (p = 0.01). Seven patients have moderate (5) or severe (2) residual problems, all in the cohorts receiving neutrons (6/7) or mixed beam therapy (1/7). (author). 31 refs.; 5 tabs.

  3. A novel approach to correct the coded aperture misalignment for fast neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F. N.; Hu, H. S., E-mail: huasi-hu@mail.xjtu.edu.cn; Wang, D. M.; Jia, J. [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhang, T. K. [Laser Fusion Research Center, CAEP, Mianyang, 621900 Sichuan (China); Jia, Q. G. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)

    2015-12-15

    Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, “residual watermark,” certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used to determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 μm. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.

  4. Thermal stability and kinetics of defects in magnesium aluminate spinel irradiated with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Kazuhiro E-mail: yasudak@nucl.kyushu-u.ac.jp; Kinoshita, Chiken; Fukuda, Korehisa; Garner, Frank A

    2000-12-01

    Thermal stability of interstitial-type dislocation loops and cavities in single crystals of MgAl{sub 2}O{sub 4} was examined during isochronal and isothermal annealing. The specimens were irradiated with fast-neutrons in FFTF/MOTA at 658 and 1023 K up to 249 dpa. During the isochronal annealing, dislocation loops started to shrink around 1000 K and completely disappeared at 1470 K without changing their character. Cavities grew slightly around 1570 K, and above this temperature, cavities shrunk with increasing annealing temperature. The recovery stage of point defects in MgAl{sub 2}O{sub 4} was discussed in terms of the thermal stability of defect clusters; vacancy migration starts around 1000 K (corresponding to stage III), whereas vacancy clusters start to dissociate around 1570 K (corresponding to stage V). The vacancy migration energy for rate controlling species was estimated from the shrinkage process of interstitial-type dislocation loops to be 2.0 {+-} 0.7 eV.

  5. A feasibility study using radiochromic films for fast neutron 2D passive dosimetry

    Science.gov (United States)

    Brady, Samuel L.; Gunasingha, Rathnayaka; Yoshizumi, Terry T.; Howell, Calvin R.; Crowell, Alexander S.; Fallin, Brent; Tonchev, Anton P.; Dewhirst, Mark W.

    2010-09-01

    The objective of this paper is threefold: (1) to establish sensitivity of XRQA and EBT radiochromic films to fast neutron exposure; (2) to develop a film response to radiation dose calibration curve and (3) to investigate a two-dimensional (2D) film dosimetry technique for use in establishing an experimental setup for a radiobiological irradiation of mice and to assess the dose to the mice in this setup. The films were exposed to a 10 MeV neutron beam via the 2H(d,n)3He reaction. The XRQA film response was a factor of 1.39 greater than EBT film response to the 10 MeV neutron beam when exposed to a neutron dose of 165 cGy. A film response-to-soft tissue dose calibration function was established over a range of 0-10 Gy and had a goodness of fit of 0.9926 with the calibration data. The 2D film dosimetry technique estimated the neutron dose to the mice by measuring the dose using a mouse phantom and by placing a piece of film on the exterior of the experimental mouse setup. The film results were benchmarked using Monte Carlo and aluminum (Al) foil activation measurements. The radiochromic film, Monte Carlo and Al foil dose measurements were strongly correlated, and the film within the mouse phantom agreed to better than 7% of the externally mounted films. These results demonstrated the potential application of radiochromic films for passive 2D neutron dosimetry.

  6. Design and expected performance of a fast neutron attenuation probe for light element density measurements

    Science.gov (United States)

    Sweany, M.; Marleau, P.

    2016-10-01

    We present the design and expected performance of a proof-of-concept 32 channel material identification system. Our system is based on the energy-dependent attenuation of fast neutrons for four elements: hydrogen, carbon, nitrogen and oxygen. We describe a new approach to obtaining a broad range of neutron energies to probe a sample, as well as our technique for reconstructing the molar densities within a sample. The system's performance as a function of time-of-flight energy resolution is explored using a Geant4-based Monte Carlo. Our results indicate that, with the expected detector response of our system, we will be able to determine the molar density of all four elements to within a 20-30% accuracy in a two hour scan time. In many cases this error is systematically low, thus the ratio between elements is more accurate. This degree of accuracy is enough to distinguish, for example, a sample of water from a sample of pure hydrogen peroxide: the ratio of oxygen to hydrogen is reconstructed to within 8±0.5% of the true value. Finally, with future algorithm development that accounts for backgrounds caused by scattering within the sample itself, the accuracy of molar densities, not ratios, may improve to the 5-10% level for a two hour scan time.

  7. Feasibility of the Utilization of BNCT in the Fast Neutron Therapy Beam at Fermilab

    Science.gov (United States)

    Langen, Katja; Lennox, Arlene J.; Kroc, Thomas K.; DeLuca, Jr., Paul M.

    2000-06-01

    The Neutron Therapy Facility at Fermilab has treated cancer patients since 1976. Since then more than 2,300 patients have been treated and a wealth of clinical information accumulated. The therapeutic neutron beam at Fermilab is produced by bombarding a beryllium target with 66 MeV protons. The resulting continuous neutron spectrum ranges from thermal to 66 MeV in neutron energy. It is clear that this spectrum is not well suited for the treatment of tumors with boron neutron capture therapy (BNCT) only However, since this spectrum contains thermal and epithermal components the authors are investigating whether BNCT can be used in this beam to boost the tumor dose. There are clinical scenarios in which a selective tumor dose boost of 10 - 15% could be clinically significant. For these cases the principal treatment would still be fast neutron therapy but a tumor boost could be used either to deliver a higher dose to the tumor tissue or to reduce the dose to the normal healthy tissue while maintaining the absorbed dose level in the tumor tissue.

  8. Membrane solubilization in erythrocytes as a measure of radiation exposure to fast neutrons

    Science.gov (United States)

    Soltan Monem, A.; Ali, Fadel M.; Al-thani, Noura J. J.; Ali, Samira A.

    1999-02-01

    Membrane solubilization and osmotic fragility of rat erythrocytes irradiated in vivo with fast neutron fluences ranging from to using a source were measured instantaneously using a light scattering technique. The solubilization of erythrocyte membrane by a non-ionic detergent, octylglucoside (OG), was found to exhibit a two stage transition from vesicular form to mixed micellar form in the range of detergent concentrations 1.5-7.8 mM. The coexistence phase, vesicular/mixed micellar, was shifted towards higher detergent concentrations with increase in the neutron fluence, indicating increasing membrane resistance to the detergent and hence change in the natural membrane permeation properties. The technique shows an adequate sensitivity in detecting membrane damage in erythrocytes and has potential as a biophysical marker of radiation exposure. The osmotic fragility of irradiated erythrocytes shows a decreasing trend with increasing irradiation fluence measured directly and two weeks post-irradiation. Blood films photographed two weeks post-irradiation show developed elliptocytosis and crenated cell anaemia.

  9. Covariance generation and uncertainty propagation for thermal and fast neutron induced fission yields

    Science.gov (United States)

    Terranova, Nicholas; Serot, Olivier; Archier, Pascal; De Saint Jean, Cyrille; Sumini, Marco

    2017-09-01

    Fission product yields (FY) are fundamental nuclear data for several applications, including decay heat, shielding, dosimetry, burn-up calculations. To be safe and sustainable, modern and future nuclear systems require accurate knowledge on reactor parameters, with reduced margins of uncertainty. Present nuclear data libraries for FY do not provide consistent and complete uncertainty information which are limited, in many cases, to only variances. In the present work we propose a methodology to evaluate covariance matrices for thermal and fast neutron induced fission yields. The semi-empirical models adopted to evaluate the JEFF-3.1.1 FY library have been used in the Generalized Least Square Method available in CONRAD (COde for Nuclear Reaction Analysis and Data assimilation) to generate covariance matrices for several fissioning systems such as the thermal fission of U235, Pu239 and Pu241 and the fast fission of U238, Pu239 and Pu240. The impact of such covariances on nuclear applications has been estimated using deterministic and Monte Carlo uncertainty propagation techniques. We studied the effects on decay heat and reactivity loss uncertainty estimation for simplified test case geometries, such as PWR and SFR pin-cells. The impact on existing nuclear reactors, such as the Jules Horowitz Reactor under construction at CEA-Cadarache, has also been considered.

  10. NeuLAND MRPC-based detector prototypes tested with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Caesar, Christoph [GSI Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany)

    2010-07-01

    A detector for momentum measurements of high-energy neutrons in the energy range 0.2-1 GeV is being developed for the R{sup 3}B (Reactions with Relativistic Radioactive Beams) experiment at FAIR. Based on the running LAND detector at GSI, the currently pursued concept for NeuLAND is a layered structure made of iron converters and charged particle detectors. As charged particle detectors Multigap Resistive Plate Chamber (MRPC) detectors will be used. The excellent time resolution of the MRPC units will allow for a very good time-of-flight resolution of NeuLAND. The design goal for the full detector is {sigma}{sub time} <100 ps. The full NeuLAND detector will consist of about 60 layers of the basic structure (converter+MRPC), leading to a detection efficiency of close to 100% for neutrons with energies higher than 200 MeV. Prototypes built at GSI and FZD were tested using MIPs at the ELBE electron beam facility at FZD. Here we present recent results from a first irradiation of the prototypes with fast neutrons. The TSL Uppsala monoenergetic neutron beam of E{sub n}=175 MeV is well-suited for such a study. These data will serve both for the validation of the basic detection scheme and as important input to refine GEANT4 and FLUKA simulations of the final detector.

  11. Using the transportable, computer-operated, liquid-scintillator fast-neutron spectrometer system

    Energy Technology Data Exchange (ETDEWEB)

    Thorngate, J.H.

    1988-11-01

    When a detailed energy spectrum is needed for radiation-protection measurements from approximately 1 MeV up to several tens of MeV, organic-liquid scintillators make good neutron spectrometers. However, such a spectrometer requires a sophisticated electronics system and a computer to reduce the spectrum from the recorded data. Recently, we added a Nuclear Instrument Module (NIM) multichannel analyzer and a lap-top computer to the NIM electronics we have used for several years. The result is a transportable fast-neutron spectrometer system. The computer was programmed to guide the user through setting up the system, calibrating the spectrometer, measuring the spectrum, and reducing the data. Measurements can be made over three energy ranges, 0.6--2 MeV, 1.1--8 MeV, or 1.6--16 MeV, with the spectrum presented in 0.1-MeV increments. Results can be stored on a disk, presented in a table, and shown in graphical form. 5 refs., 51 figs.

  12. Radiation damage in InGaAs photodiodes by 1 MeV fast neutrons

    CERN Document Server

    Ohyama, H; Vanhellemont, J; Takami, Y; Sunaga, H

    1998-01-01

    Irradiation damage in In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As p-i-n photodiodes by 1 MeV fast neutrons has been studied as a function of fluence for the first time, and the results are discussed in this paper. The degradation of the electrical and optical performance of diodes increases with increasing fluence. The induced lattice defects in the In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As epitaxial layers and the InP substrate are studied by Deep Level Transient Spectroscopy (DLTS) methods. In the In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As epitaxial layers, hole and electron capture levels are induced by irradiation. The influence of the type of radiation source on the device degradation is then discussed by comparison to 1 MeV electrons with respect to the numbers of knock-on atoms and the nonionizing energy loss (NIEL). The radiation source dependence of performance degradation is attributed to the difference of mass between the two irradiating particles and the p...

  13. Fast neutron incineration in the energy amplifier as alternative to geologic storage the case of Spain

    CERN Document Server

    Rubbia, Carlo; Kadi, Y; Rubio, Juan Antonio

    1997-01-01

    In previous reports [1][2] we have presented the conceptual design of a fast neutron driven sub-critical device (Energy Amplifier) designed both for energy amplification (production) and for the incineration of unwanted ³waste² from Nuclear Light Water Reactors (LWR). The latter scheme is here applied to the specific case of Spain, where 9 large LWR¹s are presently in operation. It is shown that a cluster of 5 EA¹s is a very effective and realistic solution to the elimination (in 37 years) of the present and foreseen (till 2029) LWR-Waste stockpiles of Spain, but with major improvements over Geologic Storage, since: (1) only a Low Level Waste (LLW) surface repository of reasonable size is ultimately required; (2) the large amount of energy stored in the trans-Uranics is recovered, amounting for each of the 37 years of incineration to a saving of about 8% of the present primary energy demand of Spain (100 MTep/y); (3) the slightly enriched (1.1%) Uranium, unburned by LWR¹s, can be recovered for further us...

  14. DETEC, a Subprogram for Simulation of the Fast-Neutron Detection Process in a Hydro-Carbonous Plastic Scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, B.; Aspelund, O.

    1966-07-15

    A description is given of the subprogram DETEC, which for energies below 5 MeV simulates the detection process of a fast-neutron within a large cylindrical plastic scintillator. DETEC has been coded in FORTRAN IV, and consists of a subroutine and a BLOCK-DATA subprogram. The latter is in its present form adapted to the dimensions 5 cm diam. x 8 cm of the scintillating materials NE102 and NE102A. The character of DETEC as a subprogram is manifest through the requirement of a main routine for generation of the following input parameters: 1. fast-neutron position; 2. direction; 3. energy; 4. entrance time; 5. input weight (all referred to the detector surface), and 6. the discriminator threshold. When these are provided, the virtues of DETEC are recording of the detected weight and the time elapsed prior to the detection event. The merits of DETEC are finally demonstrated in two typical applications.

  15. Application of fast neutron radiography to three-dimensional visualization of steady two-phase flow in a rod bundle

    CERN Document Server

    Takenaka, N; Fujii, T; Mizubata, M; Yoshii, K

    1999-01-01

    Three-dimensional void fraction distribution of air-water two-phase flow in a 4x4 rod-bundle near a spacer was visualized by fast neutron radiography using a CT method. One-dimensional cross sectional averaged void fraction distribution was also calculated. The behaviors of low void fraction (thick water) two-phase flow in the rod bundle around the spacer were clearly visualized. It was shown that the void fraction distributions were visualized with a quality similar to those by thermal neutron radiography for low void fraction two-phase flow which is difficult to visualize by thermal neutron radiography. It is concluded that the fast neutron radiography is efficiently applicable to two-phase flow studies.

  16. Monte-Carlo Simulations of Radiation-Induced Activation in a Fast-Neutron and Gamma- Based Cargo Inspection System

    CERN Document Server

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

    2012-01-01

    An air cargo inspection system combining two nuclear reaction based techniques, namely Fast-Neutron Resonance Radiography and Dual-Discrete-Energy Gamma Radiography is currently being developed. This system is expected to allow detection of standard and improvised explosives as well as special nuclear materials. An important aspect for the applicability of nuclear techniques in an airport inspection facility is the inventory and lifetimes of radioactive isotopes produced by the neutron and gamma radiation inside the cargo, as well as the dose delivered by these isotopes to people in contact with the cargo during and following the interrogation procedure. Using MCNPX and CINDER90 we have calculated the activation levels for several typical inspection scenarios. One example is the activation of various metal samples embedded in a cotton-filled container. To validate the simulation results, a benchmark experiment was performed, in which metal samples were activated by fast-neutrons in a water-filled glass jar. T...

  17. A novel structure of transmission line pulse transformer with mutually coupled windings.

    Science.gov (United States)

    Yu, Binxiong; Su, Jiancang; Li, Rui; Zhao, Liang; Zhang, Xibo; Wang, Junjie

    2014-03-01

    A novel structure of transmission line transformer (TLT) with mutually coupled windings is described in this paper. All transmission lines except the first stage of the transformer are wound on a common ferrite core for the TLT with this structure. A referral method was introduced to analyze the TLT with this structure, and an analytic expression of the step response was derived. It is shown that a TLT with this structure has a significantly slower droop rate than a TLT with other winding structures and the number of ferrite cores needed is largely reduced. A four-stage TLT with this structure was developed, whose input and output impedance were 4.2 Ω and 67.7 Ω, respectively. A frequency response test of the TLT was carried out. The test results showed that pulse response time of the TLT is several nanoseconds. The TLT described in this paper has the potential to be used as a rectangle pulse transformer with very fast response time.

  18. A hybrid pulse combining topology utilizing the combination of modularized avalanche transistor Marx circuits, direct pulse adding, and transmission line transformer.

    Science.gov (United States)

    Li, Jiangtao; Zhao, Zheng; Sun, Yi; Liu, Yuhao; Ren, Ziyuan; He, Jiaxin; Cao, Hui; Zheng, Minjun

    2017-03-01

    Numerous applications driven by pulsed voltage require pulses to be with high amplitude, high repetitive frequency, and narrow width, which could be satisfied by utilizing avalanche transistors. The output improvement is severely limited by power capacities of transistors. Pulse combining is an effective approach to increase the output amplitude while still adopting conventional pulse generating modules. However, there are drawbacks in traditional topologies including the saturation tendency of combining efficiency and waveform oscillation. In this paper, a hybrid pulse combining topology was adopted utilizing the combination of modularized avalanche transistor Marx circuits, direct pulse adding, and transmission line transformer. The factors affecting the combining efficiency were determined including the output time synchronization of Marx circuits, and the quantity and position of magnetic cores. The numbers of the parallel modules and the stages were determined by the output characteristics of each combining method. Experimental results illustrated the ability of generating pulses with 2-14 kV amplitude, 7-11 ns width, and a maximum 10 kHz repetitive rate on a matched 50-300 Ω resistive load. The hybrid topology would be a convinced pulse combining method for similar nanosecond pulse generators based on the solid-state switches.

  19. A hybrid pulse combining topology utilizing the combination of modularized avalanche transistor Marx circuits, direct pulse adding, and transmission line transformer

    Science.gov (United States)

    Li, Jiangtao; Zhao, Zheng; Sun, Yi; Liu, Yuhao; Ren, Ziyuan; He, Jiaxin; Cao, Hui; Zheng, Minjun

    2017-03-01

    Numerous applications driven by pulsed voltage require pulses to be with high amplitude, high repetitive frequency, and narrow width, which could be satisfied by utilizing avalanche transistors. The output improvement is severely limited by power capacities of transistors. Pulse combining is an effective approach to increase the output amplitude while still adopting conventional pulse generating modules. However, there are drawbacks in traditional topologies including the saturation tendency of combining efficiency and waveform oscillation. In this paper, a hybrid pulse combining topology was adopted utilizing the combination of modularized avalanche transistor Marx circuits, direct pulse adding, and transmission line transformer. The factors affecting the combining efficiency were determined including the output time synchronization of Marx circuits, and the quantity and position of magnetic cores. The numbers of the parallel modules and the stages were determined by the output characteristics of each combining method. Experimental results illustrated the ability of generating pulses with 2-14 kV amplitude, 7-11 ns width, and a maximum 10 kHz repetitive rate on a matched 50-300 Ω resistive load. The hybrid topology would be a convinced pulse combining method for similar nanosecond pulse generators based on the solid-state switches.

  20. Investigation of Fast Neutron Production by 100 to 250~GeV Muon Interactions on Thin Targets

    CERN Multimedia

    2002-01-01

    % NA55 \\\\ \\\\ The production of fast (1~MeV~-~1~GeV) neutrons in high energy muon-nucleon interactions is poorly understood. Yet it is essential to the understanding of the background in many underground neutrino experiments and, in particular, may hold relevance for the atmospheric neutrino anomaly. We propose an experiment to investigate fast neutron production using the M2 muon beam at the CERN SPS.

  1. Design of flattening filters for the fast-neutron beam at TAMVEC by use of decrement lines.

    Science.gov (United States)

    Otte, V A; Smathers, J B; Wright, R E

    1976-01-01

    Isodose distributions in a tissue-equivalent phantom produced by fast neutrons from 50-MeV deuterons incident on a thick beryllium target exhibit strong forward peaking, particularly for large fields. The design by use of decrement lines and the construction of polyethylene filters used to "flatten" those distributions are discussed and the results are illustrated. Also, the compromises of central-axis attenuation versus effective filter width and of off-axis peaking versus depth of "flattening" are discussed.

  2. Development of SiPM-based scintillator tile detectors for a multi-layer fast neutron tracker

    Directory of Open Access Journals (Sweden)

    Jakubek J.

    2012-10-01

    Full Text Available We are developing thin tile scintillator detectors with silicon photomultiplier (SiPM readout for use in a multi-layer fast-neutron tracker. The tracker is based on interleaved Timepix and plastic scintillator layers. The thin 15 × 15 × 2 mm plastic scintillators require suitable optical readout in order to detect and measure the energy lost by energetic protons that have been recoiled by fast neutrons. Our first prototype used dual SiPMs, coupled to opposite edges of the scintillator tile using light-guides. An alternative readout geometry was designed in an effort to increase the fraction of scintillation light detected by the SiPMs. The new prototype uses a larger SiPM array to cover the entire top face of the tile. This paper details the comparative performance of the two prototype designs. A deuterium-tritium (DT fast-neutron source was used to compare the relative light collection efficiency of the two designs. A collimated UV light source was scanned across the detector face to map the uniformity. The new prototype was found to have 9.5 times better light collection efficiency over the original design. Both prototypes exhibit spatial non-uniformity in their response. Methods of correcting this non-uniformity are discussed.

  3. Improvement of switching speed of a 600-V nonpunch through insulated gate bipolar transistor using fast neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Ha Ni; Sun, Gwang Min; Kim, Ji Suck; Hoang, Sy Minh Tuan; Jin, Mi Eun; Ahn, Sung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    Fast neutron irradiation was used to improve the switching speed of a 600-V nonpunch-through insulated gate bipolar transistor. Fast neutron irradiation was carried out at 30-MeV energy in doses of 1 × 10{sup 8} n/cm{sup 2}, 1 × 10{sup 9} n/cm{sup 2}, 1 × 10{sup 10} n/cm{sup 2}, and 1 × 10{sup 11} n/cm{sup 2}. Electrical characteristics such as current–voltage, forward on-state voltage drop, and switching speed of the device were analyzed and compared with those prior to irradiation. The on-state voltage drop of the initial devices prior to irradiation was 2.08 V, which increased to 2.10 V, 2.20 V, 2.3 V, and 2.4 V, respectively, depending on the irradiation dose. This effect arises because of the lattice defects generated by the fast neutrons. In particular, the turnoff delay time was reduced to 92 nanoseconds, 45% of that prior to irradiation, which means there is a substantial improvement in the switching speed of the device.

  4. MCNP5 and GEANT4 comparisons for preliminary Fast Neutron Pencil Beam design at the University of Utah TRIGA system

    Science.gov (United States)

    Adjei, Christian Amevi

    The main objective of this thesis is twofold. The starting objective was to develop a model for meaningful benchmarking of different versions of GEANT4 against an experimental set-up and MCNP5 pertaining to photon transport and interactions. The following objective was to develop a preliminary design of a Fast Neutron Pencil Beam (FNPB) Facility to be applicable for the University of Utah research reactor (UUTR) using MCNP5 and GEANT4. The three various GEANT4 code versions, GEANT4.9.4, GEANT4.9.3, and GEANT4.9.2, were compared to MCNP5 and the experimental measurements of gamma attenuation in air. The average gamma dose rate was measured in the laboratory experiment at various distances from a shielded cesium source using a Ludlum model 19 portable NaI detector. As it was expected, the gamma dose rate decreased with distance. All three GEANT4 code versions agreed well with both the experimental data and the MCNP5 simulation. Additionally, a simple GEANT4 and MCNP5 model was developed to compare the code agreements for neutron interactions in various materials. Preliminary FNPB design was developed using MCNP5; a semi-accurate model was developed using GEANT4 (because GEANT4 does not support the reactor physics modeling, the reactor was represented as a surface neutron source, thus a semi-accurate model). Based on the MCNP5 model, the fast neutron flux in a sample holder of the FNPB is obtained to be 6.52×107 n/cm2s, which is one order of magnitude lower than gigantic fast neutron pencil beam facilities existing elsewhere. The MCNP5 model-based neutron spectrum indicates that the maximum expected fast neutron flux is at a neutron energy of ~1 MeV. In addition, the MCNP5 model provided information on gamma flux to be expected in this preliminary FNPB design; specifically, in the sample holder, the gamma flux is to be expected to be around 108 γ/cm 2s, delivering a gamma dose of 4.54×103 rem/hr. This value is one to two orders of magnitudes below the gamma

  5. Fast Neutron Spectrum Potassium Worth for Space Power Reactor Design Validation

    Energy Technology Data Exchange (ETDEWEB)

    Bess, John D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Marshall, Margaret A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Briggs, J. Blair [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tsiboulia, Anatoli [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rozhikhin, Yevgeniy [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mihalczo, John T. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    A variety of critical experiments were constructed of enriched uranium metal (oralloy ) during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, one was performed that consisted of uranium metal annuli surrounding a potassium-filled, stainless steel can. The outer diameter of the annuli was approximately 13 inches (33.02 cm) with an inner diameter of 7 inches (17.78 cm). The diameter of the stainless steel can was 7 inches (17.78 cm). The critical height of the configurations was approximately 5.6 inches (14.224 cm). The uranium annulus consisted of multiple stacked rings, each with radial thicknesses of 1 inch (2.54 cm) and varying heights. A companion measurement was performed using empty stainless steel cans; the primary purpose of these experiments was to test the fast neutron cross sections of potassium as it was a candidate for coolant in some early space power reactor designs.The experimental measurements were performed on July 11, 1963, by J. T. Mihalczo and M. S. Wyatt (Ref. 1) with additional information in its corresponding logbook. Unreflected and unmoderated experiments with the same set of highly enriched uranium metal parts were performed at the Oak Ridge Critical Experiments Facility in the 1960s and are evaluated in the International Handbook for Evaluated Criticality Safety Benchmark Experiments (ICSBEP Handbook) with the identifier HEU MET FAST 051. Thin

  6. A feasibility study using radiochromic films for fast neutron 2D passive dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Samuel L; Fallin, Brent [Medical Physics Graduate Program, Duke University, Durham, NC 27705 (United States); Gunasingha, Rathnayaka; Yoshizumi, Terry T [Radiation Safety Division, Duke University, Durham, NC 27705 (United States); Howell, Calvin R; Crowell, Alexander S; Tonchev, Anton P [Department of Physics, Duke University, Durham, NC 27706 (United States); Dewhirst, Mark W, E-mail: yoshi003@mc.duke.ed [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States)

    2010-09-07

    The objective of this paper is threefold: (1) to establish sensitivity of XRQA and EBT radiochromic films to fast neutron exposure; (2) to develop a film response to radiation dose calibration curve and (3) to investigate a two-dimensional (2D) film dosimetry technique for use in establishing an experimental setup for a radiobiological irradiation of mice and to assess the dose to the mice in this setup. The films were exposed to a 10 MeV neutron beam via the {sup 2}H(d,n){sup 3}He reaction. The XRQA film response was a factor of 1.39 greater than EBT film response to the 10 MeV neutron beam when exposed to a neutron dose of 165 cGy. A film response-to-soft tissue dose calibration function was established over a range of 0-10 Gy and had a goodness of fit of 0.9926 with the calibration data. The 2D film dosimetry technique estimated the neutron dose to the mice by measuring the dose using a mouse phantom and by placing a piece of film on the exterior of the experimental mouse setup. The film results were benchmarked using Monte Carlo and aluminum (Al) foil activation measurements. The radiochromic film, Monte Carlo and Al foil dose measurements were strongly correlated, and the film within the mouse phantom agreed to better than 7% of the externally mounted films. These results demonstrated the potential application of radiochromic films for passive 2D neutron dosimetry.

  7. Evaluating the CDM-Robustness of the input buffer with very fast transmission line pulse

    Science.gov (United States)

    Kao, Tzu-Cheng; Lee, Jian-Hsing; Hung, Chung-Yu; Lien, Chen-Hsin; Su, Hung-Der

    2015-02-01

    In this paper, a scheme for how to utilize VFTLP (very fast transmission line pulse) data to design an input buffer circuit for CDM (charged-device model) ESD protection is reported. The impedance of the ESD device under VFTLP stress is nearly 120 Ω at the beginning of turn-on transient, and decreases with time toward 10 Ω prior to the voltage falling below 0 V. In this work, the fact that the dynamic-characteristic impedance of the ESD device under VFTLP testing is independent of the stress current is found. Since both VFTLP zapping and the CDM are nanosecond events, the dynamic-characteristic impedance of the ESD device can be used to evaluate the CDM threshold voltage of the input buffer based on the equivalent and simplified RLC circuit.

  8. Novel high-frequency, high-power, pulsed oscillator based on a transmission line transformer.

    Science.gov (United States)

    Burdt, R; Curry, R D

    2007-07-01

    Recent analysis and experiments have demonstrated the potential for transmission line transformers to be employed as compact, high-frequency, high-power, pulsed oscillators with variable rise time, high output impedance, and high operating efficiency. A prototype system was fabricated and tested that generates a damped sinusoidal wave form at a center frequency of 4 MHz into a 200 Omega load, with operating efficiency above 90% and peak power on the order of 10 MW. The initial rise time of the pulse is variable and two experiments were conducted to demonstrate initial rise times of 12 and 3 ns, corresponding to a spectral content from 4-30 and from 4-100 MHz, respectively. A SPICE model has been developed to accurately predict the circuit behavior and scaling laws have been identified to allow for circuit design at higher frequencies and higher peak power. The applications, circuit analysis, test stand, experimental results, circuit modeling, and design of future systems are all discussed.

  9. Transmission of reactive pulsed laser deposited VO2 films in the THz domain

    Science.gov (United States)

    Émond, Nicolas; Hendaoui, Ali; Ibrahim, Akram; Al-Naib, Ibraheem; Ozaki, Tsuneyuki; Chaker, Mohamed

    2016-08-01

    This work reports on the characteristics of the insulator-to-metal transition (IMT) of reactive pulsed laser deposited vanadium dioxide (VO2) films in the terahertz (THz) frequency range, namely the transition temperature TIMT, the amplitude contrast of the THz transmission over the IMT ΔA, the transition sharpness ΔT and the hysteresis width ΔH. XRD analysis shows the sole formation of VO2 monoclinic structure with an enhancement of (011) preferential orientation when varying the O2 pressure (PO2) during the deposition process from 2 to 25 mTorr. THz transmission measurements as a function of temperature reveal that VO2 films obtained at low PO2 exhibit low TIMT, large ΔA, and narrow ΔH. Increasing PO2 results in VO2 films with higher TIMT, smaller ΔA, broader ΔH and asymmetric hysteresis loop. The good control of the VO2 IMT features in the THz domain could be further exploited for the development of advanced smart devices, such as ultrafast switches, modulators, memories and sensors.

  10. A fast-neutron generator for experiments; Um dispositivo gerador de neutrons rapidos para experimentacao

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Charles F.; Souza, Manuel Jorge M.T. de; Campos, Tarcisio P.R. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares]. E-mail: campos@nuclear.ufmg.br

    2005-07-01

    The present article presents an irradiation device of fast neutrons generated by sealed sources of AmBe, placed diametrically opposed to a central channel. The paper addresses the project, the shield calculations using the nuclear code MCNP5, and radioprotection issues. Considerations of the assembly of the device will be presented. The device is in a licensing phase. A cylinder of 30 cm diameter and 200 cm length are positioned buried 200 cm deep, whose opening is in the level of the floor Six sealed sources are available for the load of the irradiator. The sources will be positioned inside of the irradiator, receiving a double cast, a polyethylene one and another made of a steel tube. In the bottom and top of the cylinder there are paraffin shielding and in the center a central channel exists for lifting down samples to the irradiation position. In the central channel of this irradiator, a guide tube holds safely the sample close to 60 mm at center distance from sources, diametrically placed. The system is built-in into the soil, with the opening in the floor and all stamped against humidity. The sample's space to be irradiated has 20cm{sup 3} and it receives irradiation of fast to thermal neutrons. At vertical level, the sources will be shielded with 120 cm of boronate paraffin. A solid cylinder of 10 cm of diameter is positioned internally in the irradiator. The cylinder receives a restraint so that it cannot be removed unaware. In the half middle of the cylinder an opening of 8 cm length exists, in the form of a camera. Puling over the cylinder in a meter height liberates the camera at the level of the floor for placement of samples, at the same time in that shields the hole with a meter of boronate paraffin. The sample is placed inside of the camera of steel. After going down the cylinder at level of sources the sample is irradiated. Radioprotection aspects will be presented. The neutron flux at camera position is close to 10{sup 8}n/cm{sup 2}.seg. at 6

  11. Temperature Dependence of the Primary Species Yields of Liquid Water Radiolysis by 0.8-MeV Fast Neutrons

    Directory of Open Access Journals (Sweden)

    S.L. Butarbutar

    2016-04-01

    Full Text Available The yields of species such as e-aq, H•, •OH, H2 and H2O2, formed from the radiolysis of neutral liquid water by the incidence of 0.8-MeV neutrons at temperatures between 25 and 350°C, were calculated by using Monte Carlo simulations. The slowing down of these neutrons through elastic scattering produced recoil protons elastically of ~0.5057, 0.186, and 0.0684 MeV which had linear energy transfers (LETs of ~40, 67 and 76 keV/µm, respectively, at 25°C. The effects of neutron radiation can be predicted based on the contribution of those first three recoil protons by neglecting the radiation effects due to oxygen ion recoils. Then, the fast neutron yields could be estimated by summing the yields of contributing protons after corresponding weightings were used according to their energy. In this work, yields were calculated at 10-7 and 10-6 s after incidence of neutron radiation in water at the aforementioned temperature range. Overall, there is a reasonably good agreement between our calculated and existing experimental G-values for the entire temperature range. However, we proposed an hypothesis that the not very significant difference between experimental data and our calculated data is due to the different measuring time used in obtaining the experimental data as compared to the ones used in our calculation. Our computed yields for 0.8-MeV fast neutron radiation show an essentially similar temperature dependences over the range of temperature studied with 2-MeV fast neutron and low-LET radiation, but with lower values for yields of free radicals and higher values for molecular yields.

  12. Pulse shaping for high data rate ultra-wideband wireless transmission under the Russian spectral emission mask

    DEFF Research Database (Denmark)

    Rommel, Simon; Grakhova, Elizaveta P.; Jurado-Navas, Antonio

    2017-01-01

    This paper addresses impulse-radio ultra-wideband (IR-UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well-kno...

  13. Effects of irradiation - fast neutrons and implantation on sintered Y sbnd Ba sbnd Cu sbnd O superconductors

    Science.gov (United States)

    Rao, K. V.; PuŹniak, R.; Chen, D.-X.; Karpe, N.; Baran, M.; Wiśniewski, A.; Pytel, K.; Szymczak, H.; Dyrbye, K.; Bøttiger, J.

    1988-06-01

    Effects of irradiation damage by fast neutrons, and nitrogen implantation on magnetic and electrical properties of Y sbnd Ba sbnd Cu sbnd O materials have been studied. The samples were subjected to a fluence of 2 × 10 17 and 1 × 10 17 neutrons / cm 2. In the implantation studies dosages of 10 15 and 10 16ions/ cm 2 of N + were used. Here we will report on the detailed changes in the magnetic hysteresis loop due to irradiation. It is found that the transport inter-grain critical current decreases with irradiation, while the critical current inside the grains is enhanced.

  14. Assessment of sensitivity of neutron-physical parameters of fast neutron reactor to purification of reprocessed fuel from minor actinides

    Science.gov (United States)

    Cherny, V. A.; Kochetkov, L. A.; Nevinitsa, A. I.

    2013-12-01

    The work is devoted to computational investigation of the dependence of basic physical parameters of fast neutron reactors on the degree of purification of plutonium from minor actinides obtained as a result of pyroelectrochemical reprocessing of spent nuclear fuel and used for manufacturing MOX fuel to be reloaded into the reactors mentioned. The investigations have shown that, in order to preserve such important parameters of a BN-800 type reactor as the criticality, the sodium void reactivity effect, the Doppler effect, and the efficiency of safety rods, it is possible to use the reprocessed fuel without separation of minor actinides for refueling (recharging) the core.

  15. Transmission of 10 GHz,3.5 ps Optical Pulses Over 100-km Standard Fiber Using Mid-span Spectral Inversion

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jianfeng; YAO Minyu; PENG Can; ZHANG Hongming; XU Qianfan; GAO Yizhi

    2002-01-01

    Transmission of 3.5ps optical pulses over 100-km standard fiber was demonstrated by employing phase conjugation in a semiconductor optical amplifier to compensate the chromatic dispersion.The pulses were broadened to 5 ps after transmission,which confirms the applicability of this technique to ultra high-bit-rate system beyond 40 Gb/s.

  16. Effects of high power microwave pulses on synaptic transmission and long term potentiation in hippocampus.

    Science.gov (United States)

    Pakhomov, Andrei G; Doyle, Joanne; Stuck, Bruce E; Murphy, Michael R

    2003-04-01

    Effects of short, extremely high power microwave pulses (EHPP) on neuronal network function were explored by electrophysiological techniques in the isolated rat hippocampal slice model. Population spikes (PS) in the CA1 area were evoked by repeated stimulation (1 per 30 s) of the Schaffer collateral pathway. A brief tetanus (2 s at 50 Hz) was used to induce long term potentiation (LTP) of synaptic transmission. In three different series of experiments with a total of 160 brain slices, the EHPP irradiation was performed before, during, or after the tetanus. The EHPP carrier frequency was 9.3 GHz, the pulse width and repetition rate were from 0.5 to 2 micros and from 0.5 to 10 Hz, respectively, and the peak specific absorption rate (SAR) in brain slices reached up to 500 MW/kg. Microwave heating of the preparation ranged from 0.5 degrees C (at 0.3 kW/kg time average SAR) to 6 degrees C (at 3.6 kW/kg). The experiments established that the only effect caused by EHPP exposure within the studied range of parameters was a transient and fully reversible decrease in the PS amplitude. Recovery took no more than a few minutes after the cessation of exposure and return to the initial temperature. This effect's features were characteristic of an ordinary thermal response: it was proportional to the temperature rise but not to any specific parameter of EHPP, and it could also be induced by a continuous wave (CW) irradiation or conventional heating. Irradiation did not affect the ability of neurons to develop LTP in response to tetanus or to retain the potentiated state that was induced before irradiation. No lasting or delayed effects of EHPP were observed. The results are consistent with the thermal mechanism of EHPP action and thus far provided no indication of EHPP-specific effects on neuronal function.

  17. 2.56 Tbit/s/ch (640 Gbaud) polarization-multiplexed DQPSK non-coherent Nyquist pulse transmission over 525 km.

    Science.gov (United States)

    Harako, Koudai; Seya, Daiki; Suzuki, Daiki; Hirooka, Toshihiko; Nakazawa, Masataka

    2015-11-30

    We demonstrate a single-channel 2.56 Tbit/s polarization-multiplexed DQPSK transmission using 640 Gbaud non-coherent optical Nyquist pulses. By virtue of a large tolerance to polarization-mode dispersion, the detrimental depolarization-induced crosstalk was reduced by 3.8 dB compared with RZ pulses. As a result, the transmission distance was substantially extended to 525 km compared with the distance of 300 km obtained with a Gaussian pulse.

  18. Disclosure of the oscillations in kinetics of the reactor pressure vessel steel damage at fast neutron intensity decreasing

    Science.gov (United States)

    Krasikov, E.; Nikolaenko, V.

    2017-01-01

    Fast neutron intensity influence on reactor materials radiation damage is a critically important question in the problem of the correct use of the accelerated irradiation tests data for substantiation of the materials workability in real irradiation conditions that is low neutron intensity. Investigations of the fast neutron intensity (flux) influence on radiation damage and experimental data scattering reveal the existence of non-monotonous sections in kinetics of the reactor pressure vessels (RPV) steel damage. Discovery of the oscillations as indicator of the self-organization processes presence give reasons for new ways searching on reactor pressure vessel (RPV) steel radiation stability increasing and attempt of the self-restoring metal elaboration. Revealing of the wavelike process in the form of non monotonous parts of the kinetics of radiation embrittlement testifies that periodic transformation of the structure take place. This fact actualizes the problem of more precise definition of the RPV materials radiation embrittlement mechanisms and gives reasons for search of the ways to manage the radiation stability (nanostructuring and so on to stimulate the radiation defects annihilation), development of the means for creating of more stableness self recovering smart materials.

  19. Genome-wide analysis of mutations in mutant lineages selected following fast-neutron irradiation mutagenesis of Arabidopsis thaliana

    KAUST Repository

    Belfield, E.J.

    2012-04-12

    Ionizing radiation has long been known to induce heritable mutagenic change in DNA sequence. However, the genome-wide effect of radiation is not well understood. Here we report the molecular properties and frequency of mutations in phenotypically selected mutant lines isolated following exposure of the genetic model flowering plant Arabidopsis thaliana to fast neutrons (FNs). Previous studies suggested that FNs predominantly induce deletions longer than a kilobase in A. thaliana. However, we found a higher frequency of single base substitution than deletion mutations. While the overall frequency and molecular spectrum of fast-neutron (FN)-induced single base substitutions differed substantially from those of "background" mutations arising spontaneously in laboratory-grown plants, G:C>A:T transitions were favored in both. We found that FN-induced G:C>A:T transitions were concentrated at pyrimidine dinucleotide sites, suggesting that FNs promote the formation of mutational covalent linkages between adjacent pyrimidine residues. In addition, we found that FNs induced more single base than large deletions, and that these single base deletions were possibly caused by replication slippage. Our observations provide an initial picture of the genome-wide molecular profile of mutations induced in A. thaliana by FN irradiation and are particularly informative of the nature and extent of genome-wide mutation in lines selected on the basis of mutant phenotypes from FN-mutagenized A. thaliana populations.

  20. Enhancement of critical current density in fast neutron irradiated melt-textured YBa 2Cu 3O 7- x

    Science.gov (United States)

    Puźniak, R.; Wiśniewski, A.; Baran, M.; Szymczak, H.; Pingxiang, Zhang; Jingrong, Wang; Lian, Zhou; Pytel, K.; Pytel, B.

    The critical current density in melt-textured samples obtained by the powder melting process was determined from magnetization measurements. Linear dependence between the width of the hysteresis loop and sample size was observed for both unirradiated and irradiated samples. This indicates that the critical current is circulating through the whole sample and is not disconnected by weak links, even when a magnetic field is applied in the irradiated sample. After fast neutron irradiation with fluences from 5 × 10 16 to 6 × 10 17 n cm -2 ( E > 0.5 MeV), significant enhancement of the critical current density, jc, was observed. Critical current density, determined from magnetization measurements, for magnetic field perpendicular to the a-b plane, jcab, reaches - 10 5 A cm 42 at 77 K in 1 T. For H parallel to the a-b plane, jcc along the c-axis reaches 5 × 10 3 A cm -2. An increase in the anisotropy of the critical current was observed after fast neutron irradiation in the temperature range 60 - 80 K.

  1. Detection of fast neutrons from D-T nuclear reaction using a 4H-SiC radiation detector

    Science.gov (United States)

    Zatko, Bohumir; Sagatova, Andrea; Sedlackova, Katarina; Necas, Vladimir; Dubecky, Frantisek; Solar, Michael; Granja, Carlos

    2016-09-01

    The particle detector based on a high purity epitaxial layer of 4H-SiC exhibits promising properties in detection of various types of ionizing radiation. Due to the wide band gap of 4H-SiC semiconductor material, the detector can reliably operate at room and also elevated temperatures. In this work we focused on detection of fast neutrons generated the by D-T (deuterium-tritium) nuclear reaction. The epitaxial layer with a thickness of 105 μm was used as a detection part. A circular Schottky contact of a Au/Ni double layer was evaporated on both sides of the detector material. The detector structure was characterized by current-voltage and capacitance-voltage measurements, at first. The results show very low current density (SiC detector is caused by the elastic and inelastic scattering on the silicon or carbide component of the detector material. Another possibility that increases the detection efficiency is the use of a conversion layer. In our measurements, we glued a HDPE (high density polyethylene) conversion layer on the detector Schottky contact to transform fast neutrons to protons. Hydrogen atoms contained in the conversion layer have a high probability of interaction with neutrons through elastic scattering. Secondary generated protons flying to the detector can be easily detected. The detection properties of detectors with and without the HDPE conversion layer were compared.

  2. Radiation induced changes in electrical conductivity of chemical vapor deposited silicon carbides under fast neutron and gamma-ray irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Bun, E-mail: btsuchiya@meijo-u.ac.jp [Department of General Education, Faculty of Science and Technology, Meijo University, 1-501, Shiogamaguchi, Tempaku-ku, Nagoya 468-8502 (Japan); Shikama, Tatsuo; Nagata, Shinji; Saito, Kesami [Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamamoto, Syunya [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233, Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Ohnishi, Seiki [Tokai Research and Development Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Nozawa, Takashi [Aomori Research and Development Center, Japan Atomic Energy Agency, 2-166, Omotedate, Obuchi, Rokkasho, Aomori 039-3212 (Japan)

    2011-10-15

    The radiation-induced changes in the volume electrical conductivities of chemical vapor deposited silicon carbides (CVD-SiCs) were in-site investigated by performing irradiation using 1.17 and 1.33-MeV gamma-ray and 14-MeV fast neutron beams in air and vacuum. Under gamma-ray irradiation at ionization dose rates of 3.6 and 5.9 Gy/s and irradiation temperature of approximately 300 K, the initial rapid increase in electrical conductivity; this is indicative of radiation-induced conductivity (RIC), occurred due to electronic excitation, and a more gradual increase followed up to a dose of approximately 10-50 kGy corresponding to the results in base conductivity without radiation; this is indicative of radiation-induced electrical degradation (RIED). However, the radiation-induced phenomena were not observed at irradiation temperatures above 373 K. Under neutron irradiation at a further low dose rate below approximately 2.1 Gy/s, a fast neutron flux of 9.2 x 10{sup 14} n/m{sup 2} s, and 300 K, the RIED-like behavior according to radiation-induced modification of the electrical property occurred with essentially no displacement damage, but ionizing effects (radiolysis).

  3. High Hydrogen Content Graphene Hydride Compounds & High Cross-­ Section Cladding Coatings for Fast Neutron Detection

    Energy Technology Data Exchange (ETDEWEB)

    Chandrashekhar, MVS [Univ. of South Carolina, Columbia, SC (United States)

    2017-06-21

    The objective is to develop and implement a superior low-cost, large area (potentially >32in), easily deployable, close proximity, harsh environment innovative neutron sensor needed for next generation fuel cycle monitoring. We will exploit recent breakthroughs at the PI’s lab on the electrochemistry of epitaxial graphene (EG) formed on commercial SiC wafers, a transformative nanomaterial system with superior radiation detection and durability properties to develop a new paradigm in detection for fast neutrons, a by-product of fission reactors. There are currently few effective detection/monitoring schemes, especially solid-state ones at present. This is essential for monitoring and control of future fuel cycles to make them more efficient and reliable. By exploiting these novel materials, as well as innovative hybrid SiC/EG/Cladding device architectures conceived by the team, will develop low-cost, high performance solutions to fast-neutron detection. Finally, we will also explore 3-terminal device implementations for neutron detectors with built-in electronic gain to further shrink these devices and improve their sensitivity.

  4. Phase calibration of sonar systems using standard targets and dual-frequency transmission pulses.

    Science.gov (United States)

    Islas-Cital, Alan; Atkins, Philip R; Foo, Kae Y; Picó, Ruben

    2011-10-01

    The phase angle component of the complex frequency response of a sonar system operating near transducer resonance is usually distorted. Interpretation and classification of the received sonar signal benefits from the preservation of waveform fidelity over the full bandwidth. A calibration process that measures the phase response in addition to the amplitude response is thus required. This paper describes an extension to the standard-target calibration method to include phase angle, without affecting the experimental apparatus, by using dual-frequency transmission pulses and frequency-domain data processing. This approach reduces the impact of unknown range and sound speed parameters upon phase calibration accuracy, as target phase is determined from the relationship of the two frequency components instead of relying on a local phase reference. Tungsten carbide spheres of various sizes were used to simultaneously calibrate the amplitude and phase response of an active sonar system in a laboratory tank. Experimental measurements of target phase spectra are in good agreement with values predicted from a theoretical model based upon full-wave analysis, over an operating frequency of 50-125 kHz.

  5. Energy-dispersive study of the interaction of fast neutrons with matter. Common final report of the DFG projects GR 1674/2 and FR 575/5 together with the institute for nuclear and particle physics, technical university Dresden; Energiedispersive Untersuchung der Wechselwirkung schneller Neutronen mit Materie. Gemeinsamer Abschlussbericht der DFG Projekte GR 1674/2 und FR 575/5, zusammen mit dem Institut fuer Kern- und Teilchenphysik, Technische Universitaet Dresden

    Energy Technology Data Exchange (ETDEWEB)

    Altstadt, E.; Beckert, C. [Forschungszentrum Rossendorf e.V. (FZR) (Germany). Inst. fuer Sicherheitsforschung; Beyer, R. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (DE). Inst. fuer Kern- und Hadronenphysik] [and others

    2005-04-01

    In this final report on the research project ''Energy-dispersive study of the interaction of fast neutrons with matter, especially materials for fusion and materials from fission reactors the status reached after three years promotion is described. The aim of this project is the construction and first usage of a very complex time-of-flight system for the study of the interaction of fast neutrons with construction materials for fusion and fission reactors as well as with long-lived radioisotopes. Furthermore astrophysically relevant experiments on problems of the element synthesis shall be performed. The whole project is devided into two sections: 1. Development, construction and test of a pulsed photoneutron source at the ELBE accelerator of the FZ Rossendorf, 2. Application of the photoneutron sources for measurements of cross sections induced by fast, energy-selected neutrons.

  6. Study on the DOP of Output Pulse in Optical Fiber Transmission Systems

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper the expression of the output pulse Stokes vector is derived based on the Jones matrix model proposed by A.Orlandini et al. The basic properties of degree of polarization (DOP) for output pulse are investigated.

  7. Pulse

    Science.gov (United States)

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the person's heart is pumping. Pulse ... rate gives information about your fitness level and health.

  8. The effect of biological shielding on fast neutron and photon transport in the VVER-1000 mock-up model placed in the LR-0 reactor.

    Science.gov (United States)

    Košťál, Michal; Cvachovec, František; Milčák, Ján; Mravec, Filip

    2013-05-01

    The paper is intended to show the effect of a biological shielding simulator on fast neutron and photon transport in its vicinity. The fast neutron and photon fluxes were measured by means of scintillation spectroscopy using a 45×45 mm(2) and a 10×10 mm(2) cylindrical stilbene detector. The neutron spectrum was measured in the range of 0.6-10 MeV and the photon spectrum in 0.2-9 MeV. The results of the experiment are compared with calculations. The calculations were performed with various nuclear data libraries.

  9. Measurement of the thermal and fast neutron flux in a research reactor with a Li and Th loaded optical fibre detector

    CERN Document Server

    Yamane, Y; Misawa, T; Karlsson, J K H; Pázsit, I

    1999-01-01

    The spatial dependence of thermal and fast neutron flux was measured axially in the core of a 1 MW research reactor. The measurements were made by a thin optical fibre detector with a neutron sensitive ZnS(Ag) scintillation tip. For thermal neutrons sup 6 Li was used, whereas for fast neutrons sup 2 sup 3 sup 2 Th was used as neutron converter. The spatial dependence was measured by moving the fibre axially with a uniform speed. The measurement takes a few minutes, compared to up to 10 h with the conventional wire activation method. Comparison with traditional measurements shows a good agreement. (author)

  10. Ringing in the pulse response of long and wideband coaxial transmission lines due to group delay dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Kotzian,G.; de Maria,R.; Caspers, F.; Federmann, S.; Hofle, W.

    2009-05-04

    In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated outer and/or inner conductor. This particular construction exhibits a significant amount of frequency dependent group delay variation. A comparison of simulations based on theoretical models, numerical simulations and S{sub 21} network analyzer measurements up to 2.5 GHz is presented. It is shown how the non-linear phase response and varying group delay leads to ringing in the pulse response and subsequent distortion of signal s transmitted through such coaxial transmission lines.

  11. Simulation calculation for the energy deposition profile and the transmission fraction of intense pulsed electron beam at various incident angles

    CERN Document Server

    Yang Hai Liang; Zhang Jia Sheng; Huang Jian Jun; Sun Jian Feng

    2002-01-01

    The incident angles have a heavy effect on the intense pulsed electron beam energy deposition profile, energy deposition fraction and beam current transmission fraction in material. The author presents electron beam energy deposition profile and energy deposition fraction versus electron energy (0.5-2.0 MeV), at various incident angles for three aluminum targets of various thickness via theoretical calculation. The intense pulsed electron beam current transmission fractions versus electron energy (0.4-1.4 MeV) at various incident angles for three thickness of carbon targets were also theoretically calculated. The calculation results indicate that the deposition energy in unit mass of material surface layer increase with the rise of electron beam incident angle, and electron beam with low incident angle (closer to normal incident angle) penetrates deeper into the target material. The electron beams deposit more energy in unit mass of material surface layer at 60 degree-70 degree incident angle

  12. Pulse Restoration for Long-Distance Transmission of Wavelength Division Multiplexed Signals Using Gain Saturable Erbium-Doped Fiber Amplifiers

    Science.gov (United States)

    Singh, Surinder

    2010-05-01

    In this article, the pulse restoration of different fibers is compared to obtain the optimum fiber. The dispersion-compensated fiber, having a high ability for pulse restoration, is optimized to reduce the self-phase modulation effect by taking the effective core area of the fiber. Then the optimized dispersion-compensated fibers are used in wavelength division multiplex transmission to increase the maximum distance of transmission. Here, 16 channels with a channel spacing of 200 GHz are modulated by an optical LiNbO3 phase modulator with non-return-to-zero format and transmitted over 1,050 km by using dispersion-compensated fibers with an effective core area of 30 pm2 and erbium-doped fiber amplifiers. The adequate quality factor and output power of different channels are observed at 70 km, 350 km, and 1,050 km. As the distance is increased, the quality factor falls.

  13. 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

  14. Measurement and calculations of long-lived radionuclide activity forming in the fast neutron field in some ITER construction steels

    Energy Technology Data Exchange (ETDEWEB)

    Pohorecki, W., E-mail: poho@agh.edu.pl [AGH University of Science and Technology, Faculty of Energy and Fuels, Al. Mickiewicza 30, 30-059 Krakow (Poland); Jodłowski, P. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. Mickiewicza 30, 30-059 Krakow (Poland); Pytel, K.; Prokopowicz, R. [National Centre for Nuclear Research, ul. Sołtana 7, 05-400 Otwock-Świerk (Poland)

    2014-10-15

    Highlights: • Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, in some ITER construction steels. • The neutron flux density was measured by means of activation foil method and unfolding technique. • Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TALYS-2011. • The activity measurements were done by means of gamma-ray spectrometry. - Abstract: Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, for some ITER construction steels. The activation was conducted in fast neutron irradiation channel of the MARIA research fission reactor (Poland). The dimensions of steel samples were 10 mm × 10 mm × 1 mm and mass was approximately 0.8 g. The neutron flux density was measured by means of activation foil method and unfolding technique; fraction of neutrons above 1 keV was 95%. The activation lasted 242 h and cooling took 100 days; the mean neutron flux density was 2.9E12 n/(cm{sup 2} s) (neutrons above 500 keV are 53% of total) whereas total fluency 2.53E18 cm{sup −2}. The activity measurements were done by means of gamma-ray spectrometry. Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TENDL-2011 and experimentally determined neutron flux. Measured activity of long-lived gamma emitting radionuclides was, in average, about 6.3 MBq/g 100 days after activation; the dominant radionuclides were {sup 58}Co and {sup 54}Mn (about 81% and 14% of total activity respectively). The C/E ratio differs for particular radionuclides and is in the range 0.86–0.92 for {sup 51}Cr, 0.93–1.21 for {sup 54}Mn, 0.77–0.98 for {sup 57}Co, 0.91–1.21 for {sup 58}Co, 1.17–1.27 for {sup 59}Fe, and 1.75–2.44 for {sup 60}Co.

  15. The fast neutron fluence and the activation detector activity calculations using the effective source method and the adjoint function

    Energy Technology Data Exchange (ETDEWEB)

    Hep, J.; Konecna, A.; Krysl, V.; Smutny, V. [Calculation Dept., Skoda JS plc, Orlik 266, 31606 Plzen (Czech Republic)

    2011-07-01

    This paper describes the application of effective source in forward calculations and the adjoint method to the solution of fast neutron fluence and activation detector activities in the reactor pressure vessel (RPV) and RPV cavity of a VVER-440 reactor. Its objective is the demonstration of both methods on a practical task. The effective source method applies the Boltzmann transport operator to time integrated source data in order to obtain neutron fluence and detector activities. By weighting the source data by time dependent decay of the detector activity, the result of the calculation is the detector activity. Alternatively, if the weighting is uniform with respect to time, the result is the fluence. The approach works because of the inherent linearity of radiation transport in non-multiplying time-invariant media. Integrated in this way, the source data are referred to as the effective source. The effective source in the forward calculations method thereby enables the analyst to replace numerous intensive transport calculations with a single transport calculation in which the time dependence and magnitude of the source are correctly represented. In this work, the effective source method has been expanded slightly in the following way: neutron source data were performed with few group method calculation using the active core calculation code MOBY-DICK. The follow-up neutron transport calculation was performed using the neutron transport code TORT to perform multigroup calculations. For comparison, an alternative method of calculation has been used based upon adjoint functions of the Boltzmann transport equation. Calculation of the three-dimensional (3-D) adjoint function for each required computational outcome has been obtained using the deterministic code TORT and the cross section library BGL440. Adjoint functions appropriate to the required fast neutron flux density and neutron reaction rates have been calculated for several significant points within the RPV

  16. Fast neutron damage studies of La/sub 1. 85/Sr/sub 0. 15/CuO/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Sekula, S.T.; Christen, D.K.; Kerchner, H.R.; Thompson, J.R.; Boatner, L.A.; Sales, B.C.

    1987-04-01

    The effect of fast neutron damage on the superconducting transition temperature T/sub c/ and the critical current density j/sub c/ of the compound La/sub 1.85/Sr/sub 0.15/CuO/sub 4/ has been investigated. Irradiation to a fluence of 1.3 x 10/sup 18/ n/cm/sup 2/ (E > 0.1 MeV) resulted in a decrease of T/sub c/ of about 3 K while j/sub c/ at 4.2 K and H = 2 T increased by a factor of two to 1.2 x 10/sup 4/ A/cm/sup 2/.

  17. Measuring the Cosmic Ray Muon-Induced Fast Neutron Spectrum by (n,p) Isotope Production Reactions in Underground Detectors

    CERN Document Server

    Galbiati, C; Galbiati, Cristiano; Beacom, John. F.

    2005-01-01

    While cosmic ray muons themselves are relatively easy to veto in underground detectors, their interactions with nuclei create more insidious backgrounds via: (i) the decays of long-lived isotopes produced by muon-induced spallation reactions inside the detector, (ii) spallation reactions initiated by fast muon-induced neutrons entering from outside the detector, and (iii) nuclear recoils initiated by fast muon-induced neutrons entering from outside the detector. These backgrounds, which are difficult to veto or shield against, are very important for solar, reactor, dark matter, and other underground experiments, especially as increased sensitivity is pursued. We used fluka to calculate the production rates and spectra of all prominent secondaries produced by cosmic ray muons, in particular focusing on secondary neutrons, due to their importance. Since the neutron spectrum is steeply falling, the total neutron production rate is sensitive just to the relatively soft neutrons, and not to the fast-neutron compon...

  18. Magnetization studies of YBa/sub 2/Cu/sub 3/Osub(7-x) irradiated by fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Wisniewski, A.; Baran, M.; Przyslupski, P.; Szymczak, H.; Pajaczkowska, A.; Pytel, B.; Pytel, K.

    1988-02-01

    Studies of the effect of fast neutron damage on the magnetic hysteresis of YBa/sub 2/Cu/sub 3/Osub(7-x) ceramic samples subjected to fluence of neutrons of 2x10/sup 16/ n/cm/sup 2/ up to 6x10/sup 17/ n/cm/sup 2/ have been performed. Irradiation up to dose of 1x10/sup 17/ did not cause any change in the critical temperature. However it causes a strong increase of the magnetic hysteresis which is presumably connected with the creation of defects. The critical current density at 77 K in H = 10 KOe for the sample irradiated with the dose 1x10/sup 17/ n/cm/sup 2/ was estimated to be 520 A/cm/sup 2/ as compared to 29 A/cm/sup 2/ for the reference non-irradiated sample.

  19. Maxillo-dental lesions produced in cats, after gamma and fast neutron irradiation. Radiographical and microradiographical study

    Energy Technology Data Exchange (ETDEWEB)

    Dambrain, R.; Dhem, A.; Meulders, J.P.; Wambersie, A.

    1988-01-01

    Gamma doses of 50 Gy, in 5 fractions over 29 days, induce severe modifications of the irradiated jaw in the cat, as shown by radiographical and microradiographical techniques. Four out 5 animals could survive up to one year; a fifth one died as a consequence of osteoradionecrosis. In addition, 2 animals, on which a tooth extraction was performed, died from osteoradionecrosis (role of trauma). Similar irradiations were performed with fast neutrons d(50) + Be at a total dose of 16.1 Gy in 5 fractions over 29 days. The ratio 50 Gy/16.1 Gy = 3.1 is the CNPF adopted for neutrontherapy applications at Louvain-la-Neuve. This irradiation was well tolerated by 7/7 animals. Only alveolodental ankylosis was observed in 3 cases, as well as a slight reduction in bone vitality in the dorsal part of the jaw. An eighth animal died from osteoradionecrosis induced by tooth extraction.

  20. Defects in metal crystals. Progress report, May 1, 1976--April 30, 1977. [Heavy ions and fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Seidman, D N

    1977-02-01

    Work performed during 1976 to investigate point defects, aggregates of point defects and their interactions with one another is described. Strong emphasis is placed on the use of different irradiating species (300 to 700 eV Xe/sup +/ ions, 300 eV and 30 keV He/sup +/ ions, 20- to 40-keV W/sup +/ ions, 20- to 40-keV Mo/sup +/ ions, 20- to 40-keV Cr/sup +/ ions and fast neutrons) to introduce both vacancies and interstitials in a number of pure metals (Mo, W, Au, Ta) and alloys (Pt-Au, W-Re, Mo-Ti, Mo-Ti-Zr, Ni/sub 4/Mo, Ni/sub 3/Fe, Ni/sub 3/Mn, low swelling 316 stainless steel and commercial 316 stainless steel). (GHT)

  1. Light charged particle emission induced by fast neutrons (25 to 65 MeV) on sup 5 sup 9 Co

    CERN Document Server

    Nica, N; Raeymackers, E; Slypen, I; Meulders, J P; Corcalciuc, V

    2002-01-01

    Double-differential cross sections (energy spectra) for the proton, deuteron, triton and alpha-particle production in fast neutron induced reactions on cobalt are reported for ten incident neutron energies between 25 and 65 MeV. Energy spectra were obtained at nine laboratory angles between 20 deg. and 160 deg. and extrapolated or interpolated to other ten angles covering uniformly the laboratory angular domain of 0 deg. to 180 deg. The experimental set-up and procedures for data reduction including corrections and normalization are presented and discussed. Based on the measured double-differential cross sections, energy-differential and total cross sections are reported as well. Experimental cross sections are compared with similar available data from neutron- and proton-induced reactions. Theoretical calculations based on semiclassical exciton model and Hauser-Feshbach statistical theory (GNASH code) and intranuclear cascade model for nucleon-induced interactions (INCL3 code) were done and compared to the e...

  2. The use of the neutronic calculation code CORNER for evaluating the protection of fast neutron reactor and CNFC equipment

    Science.gov (United States)

    Shekhanova, M. E.

    2017-01-01

    In this paper we propose a method of using neutronic calculation code CORNER to the analysis of experiments on the protection of fast neutron reactor and CNFC equipment. An example of Winfrith Graphite Benchmark experiment calculation using this approach is presented. This task can be considered as one step in the general theme of the safety analysis of FR with liquid metal coolant, their fuel cycles and related equipment. CORNER implement a solution of the kinetic equation with a source in the three-dimensional hexagonal geometry based on Sn-method. The purpose of this paper is a demonstration of the application of CORNER’s possibilities for the analysis of the actual reactor problems.

  3. Generation of parallel transmission sub-pulses of spatial distribution based on polarizing splitting prism

    Science.gov (United States)

    Yang, Haifeng; Yang, Xiaoping; Sun, Xuna; Liu, Jun; Yang, Yong

    2016-09-01

    Parallel processing is the forefront of femtosecond laser micro-nano processing. The key to parallel processing is obtaining multichannel parallel femtosecond laser beams. A method of spatial parallel pulse splitting based on birefringence properties of polarizing splitting prism is proposed for obtaining multichannel parallel ultra-short pulse trains. The generated sub-pulses have the characteristics of equal energy and high similarity. More than that, the compact structure of the polarizing splitting prism makes it easier to be implemented. The accurate relationship between the space interval of pulse sequences and the structural angle, dimension and the distance between the two prisms is mathematically derived. The realizable array form of sub-pulse sequences is theoretically analyzed. The feasibility of the proposed method of femtosecond laser parallel processing is analyzed by software simulation and numerical calculation. The results will provide a new research direction for application of ultrashort pulse in parallel processing.

  4. Multiphase Oscillator Using Traveling Pulses Developed in a System of Transmission Lines with Regularly Spaced Resonant-tunneling Diodes

    Science.gov (United States)

    Narahara, Koichi

    2017-02-01

    A scheme is proposed for generating multiphase oscillatory signals in millimeter-wave frequencies based on the dynamics of a traveling pulse developed in a closed transmission line periodically loaded with resonant-tunneling diodes (RTDs) that is coupled with several straight RTD lines. When supplied with an appropriate voltage at the end of an RTD line, a pulse edge is shown to exhibit a spatially extended limit-cycle oscillation on the line. We consider the case where several RTD lines are connected halfway to a closed one at even intervals. In this case, the oscillatory edge developed in each straight RTD line is mutually synchronized such that a pulse-shaped rotary traveling wave develops on the closed RTD line. The oscillating edge on each straight line is also synchronized with the traveling pulse on the closed line, such that the leading edge of the traveling pulse on the closed line and the forward edge on the straight line pass the cross point simultaneously. As a result, when N L straight lines are connected to the closed line, the phase difference between two adjacent oscillatory edges becomes 2π/N L . On the other hand, the trailing edge of the traveling pulse at the cross point breaks the voltage wave on the straight line into two pieces, one of which travels forward to form a solitary wave and the other of which travels backward to reach the input end, where it is reflected and starts to travel forward and this forward moving edge is supposed to be synchronized with the leading edge of the traveling pulse. It means that a back-and-forth edge and a forward-moving solitary wave develop periodically on each straight line. Because the time required for the traveling pulse to go around the closed line must be coincident with the period of the edge oscillation on each straight line, a unique traveling pulse cannot synchronize with each oscillating edge when the cell size of the closed line becomes large, resulting in the development of multiple traveling

  5. Inverse magnetocaloric effect in Ce(Fe{sub 0.96}Ru{sub 0.04}){sub 2}: Effect of fast neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Dube, V.; Mishra, P. K.; Prajapat, C. L.; Singh, M. R.; Ravikumar, G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai-4000085 (India); Rajarajan, A. K.; Sastry, P. U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-4000085 (India); Thakare, S. V. [Radio Pharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai-4000085 (India)

    2013-02-05

    We have shown the effect of fast neutron irradiation on the magnetic phase transition and magnetocaloric effect (MCE) in a doped Ce(Fe{sub 0.96}Ru{sub 0.04}){sub 2}, intermettalic. We show that this leads to suppression of MCE and a to a disordered ferromagnetic phase.

  6. Relative biological effectiveness and tolerance dose of fission neutrons in canine skin for a potential combination of neutron capture therapy and fast-neutron therapy.

    Science.gov (United States)

    Kadosawa, Tsuyoshi; Ohashi, Fumihito; Nishimura, Ryohei; Sasaki, Nobuo; Saito, Isao; Wakabayashi, Hiroaki; Takeuchi, Akira

    2003-10-01

    To investigate the potential efficacy of fission neutrons from a fast-neutron reactor for the treatment of radioresistant tumors, the relative biological effectiveness (RBE) and tolerance dose of fission neutrons in canine skin were determined. The forelimbs of 34 healthy mongrel dogs received a single dose of fission neutrons (5.6, 6.8, 8.2, 9.6 or 11 Gy) or 137Cs gamma rays (10, 15, 20, 25 or 30 Gy). Based on observations of radiodermatitis for each radiation, the single-fraction RBE of fission neutrons in the sixth month was calculated as approximately 3. The tolerance doses of fission neutrons and gamma rays, defined as the highest doses giving no moist desquamation on the irradiated skin in the recovery phase, were estimated as 7.6 Gy and 20 Gy, respectively. The tolerance dose of 7.6 Gy of fission neutrons included 5.0 Gy of fast neutrons possessing high anti-tumor effects and 1.4 x 10(12) n/cm2 of thermal neutrons, which could be applicable to neutron capture therapy (NCT). The combination of fast-neutron therapy and NCT using a fast-neutron reactor might be useful for the treatment of radioresistant tumors.

  7. HADES. A computer code for fast neutron cross section from the Optical Model; HADES. Un programa numerico para el calculo de seccciones eficaces neutronicas mediante el modelo optico

    Energy Technology Data Exchange (ETDEWEB)

    Guasp, J.; Navarro, C.

    1973-07-01

    A FORTRAN V computer code for UNIVAC 1108/6 using a local Optical Model with spin-orbit interaction is described. The code calculates fast neutron cross sections, angular distribution, and Legendre moments for heavy and intermediate spherical nuclei. It allows for the possibility of automatic variation of potential parameters for experimental data fitting. (Author) 55 refs.

  8. Optical fiber link for transmission of 1-nJ femtosecond laser pulses at 1550 nm

    DEFF Research Database (Denmark)

    Eichhorn, Finn; Olsson, Rasmus Kjelsmark; Buron, Jonas Christian Due

    2010-01-01

    We report on numerical and experimental characterization of the performance of a fiber link optimized for the delivery of sub-100-fs laser pulses at 1550 nm over several meters of fiber. We investigate the power handling capacity of the link, and demonstrate all-fiber delivery of 1-nJ pulses over...... a distance of 5.3 m. The fiber link consists of dispersion-compensating fiber (DCF) and standard single-mode fiber. The optical pulses at different positions in the fiber link are measured using frequency-resolved optical gating (FROG). The results are compared with numerical simulations of the pulse...... propagation based on the generalized nonlinear Schrödinger equation. The high input power capacity of the fiber link allows the splitting and distribution of femtosecond pulses to an array of fibers with applications in multi-channel fiber-coupled terahertz time-domain spectroscopy and imaging systems. We...

  9. Gamma-rays and fast neutron responses calculations for personal electronic dosimetry purpose

    Science.gov (United States)

    Jung, M.; Teissier, C.; Siffert, P.

    2001-02-01

    Real-time dosimeters with small size N-type silicon diodes are proposed here for low-dose rate controls. Numerical simulations are used to predict the responses of various associated filters, neutron converters and sensors. The monitor is foreseen to work as a counter with acceptance cut-offs set on each individual pulse height. Discussions are undertaken against the minimal outline necessary to reach convenient measurement accuracies in unknown gamma-neutron fields.

  10. Multi-purpose fast neutron spectrum analyzer with real-time signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Sulyaev, Yu.S., E-mail: sulyaev@inp.nsk.su [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Puryga, E.A.; Khilchenko, A.D. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Kvashnin, A.N. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Polosatkin, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Rovenskikh, A.F. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Burdakov, A.V.; Grishnyaev, E.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation)

    2013-08-21

    Diagnostics of hot ion component of plasma on the products of fusion reactions is widely used on thermonuclear facilities. In case of employment of neutron spectrometers, based on organics scintillators, there is advanced technique developed to eliminate neutron pulses from gamma background—digital pulse shape discrimination. For every DPSD application it is necessary to use the fast (2–5 ns) and precise (12 bit) transient ADC unit with large amount of onboard memory for storing every digitized scintillation pulses during shot time. At present time the duration of hot thermonuclear plasma burning in large tokamaks approximate to 1 min, and this requires very high onboard memory capacity (∼100 GB). This paper describes a neutron spectrum analyzer with real-time DPSD algorithm, implemented to ADC unit. This approach saves about two orders of onboard memory capacity, gives the possibility of instant use of outcome to feedback systems. This analyzer was tested and calibrated with help of {sup 60}Co and {sup 252}Cf radiation sources, and deuterium neutron generator.

  11. Distortion-Less 610 fs Pulse Transmission over 160 km SSMF-DCF Using Wavelength Selective Switch for Compensation of Chromatic Dispersion

    DEFF Research Database (Denmark)

    Tologlou, G.; Mulvad, Hans Christian Hansen; Dalgaard, Kjeld;

    2011-01-01

    We demonstrate a nearly distortion-less transmission of 610 fs pulses over a 160 km standard-SMF span compensated by DCF, enabled by compensation of the residual higher order chromatic dispersion with a wavelength selective switch.......We demonstrate a nearly distortion-less transmission of 610 fs pulses over a 160 km standard-SMF span compensated by DCF, enabled by compensation of the residual higher order chromatic dispersion with a wavelength selective switch....

  12. Optical fiber link for transmission of 1-nJ femtosecond laser pulses at 1550 nm.

    Science.gov (United States)

    Eichhorn, Finn; Olsson, Rasmus Kjelsmark; Buron, Jonas C D; Grüner-Nielsen, Lars; Pedersen, Jens Engholm; Jepsen, Peter Uhd

    2010-03-29

    We report on numerical and experimental characterization of the performance of a fiber link optimized for the delivery of sub-100-fs laser pulses at 1550 nm over several meters of fiber. We investigate the power handling capacity of the link, and demonstrate all-fiber delivery of 1-nJ pulses over a distance of 5.3 m. The fiber link consists of dispersion-compensating fiber (DCF) and standard single-mode fiber. The optical pulses at different positions in the fiber link are measured using frequency-resolved optical gating (FROG). The results are compared with numerical simulations of the pulse propagation based on the generalized nonlinear Schrödinger equation. The high input power capacity of the fiber link allows the splitting and distribution of femtosecond pulses to an array of fibers with applications in multi-channel fiber-coupled terahertz time-domain spectroscopy and imaging systems. We demonstrate THz pulse generation and detection using a distributed fiber link with 32 channels and 2.6 nJ input pulse energy.

  13. High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines.

    Science.gov (United States)

    Homma, Akira

    2011-07-01

    A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components.

  14. Design of non-selective refocusing pulses with phase-free rotation axis by gradient ascent pulse engineering algorithm in parallel transmission at 7T.

    Science.gov (United States)

    Massire, Aurélien; Cloos, Martijn A; Vignaud, Alexandre; Le Bihan, Denis; Amadon, Alexis; Boulant, Nicolas

    2013-05-01

    At ultra-high magnetic field (≥ 7T), B1 and ΔB0 non-uniformities cause undesired inhomogeneities in image signal and contrast. Tailored radiofrequency pulses exploiting parallel transmission have been shown to mitigate these phenomena. However, the design of large flip angle excitations, a prerequisite for many clinical applications, remains challenging due the non-linearity of the Bloch equation. In this work, we explore the potential of gradient ascent pulse engineering to design non-selective spin-echo refocusing pulses that simultaneously mitigate severe B1 and ΔB0 non-uniformities. The originality of the method lays in the optimization of the rotation matrices themselves as opposed to magnetization states. Consequently, the commonly used linear class of large tip angle approximation can be eliminated from the optimization procedure. This approach, combined with optimal control, provides additional degrees of freedom by relaxing the phase constraint on the rotation axis, and allows the derivative of the performance criterion to be found analytically. The method was experimentally validated on an 8-channel transmit array at 7T, using a water phantom with B1 and ΔB0 inhomogeneities similar to those encountered in the human brain. For the first time in MRI, the rotation matrix itself on every voxel was measured by using Quantum Process Tomography. The results are complemented with a series of spin-echo measurements comparing the proposed method against commonly used alternatives. Both experiments confirm very good performance, while simultaneously maintaining a low energy deposition and pulse duration compared to well-known adiabatic solutions. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Simulations of Laser Pulse Coupling and Transmission Efficiency in Plasma Channels

    CERN Document Server

    Giacone, Rodolfo; Cary, John R; Dimitrov, Dimitre; Esarey, Eric; Geddes, Cameron G R; Leemans, Wim; Messmer, Peter

    2005-01-01

    Optical guiding of the laser pulse in a laser wakefield accelerator (LWFA) via plasma channels can greatly increase the interaction length and, hence, the maximun energy of trapped electrons.* Energy efficient coupling of laser pulses from vacuum into plasma channels is very important for optimal LWFA performance. We present 2D particle-in-cell simulations of this problem using the VORPAL code.** Some of the mechanisms considered are enhanced leakage of laser energy transversely through the channel walls, enhanced refraction due to tunneling ionization of neutral gas on the periphery of the gas jet, ionization of neutral gas by transverse wings of the laser pulse and effect of the pulse being off axis of the channel. Using power spectral diagnostics,*** we are able to differentiate between pump depletion and leakage from the channel. The results from our simulations show that for short (≈λp

  16. Design and performance analysis of transmission line-based nanosecond pulse multiplier

    Indian Academy of Sciences (India)

    Rishi Verma; A Shyam; Kunal G Shah

    2006-10-01

    Conventionally, Marx generators are used for the production of short duration, high voltage pulses but since many discharge gap switches are utilized for stepping up the voltage, there are many disadvantages. Here, an alternative and much simpler technique for the multiplication of nanosecond high voltage pulses has been presented in which multiplication takes place by switching single spark gap providing voltage gain of $‘nxV’$ where is the subsequent number of stages. Stepped up high voltage pulse with fixed voltage gain of defined shape with fast rise time and good flat top is produced without using additional pulse-forming network. Its operation has been made repetitive by switching single spark gap. Multipurpose use, low cost, small size, light weight (weighing less than 50 kg) and portability are the additional benefits of the system. The reported nanosecond pulser has been made by cascading three stages of Blumlein. To cross check its performance the parasitic impedance of the system has been evaluated to realize its adverse effect on the voltage gain and pulse shape. Also its operation has been simulated by PSPICE circuit simulator program and good agreement has been obtained between simulated and experimental results. Applications of this pulse generator include X-ray generation, breakdown tests, ion implantation, streamer discharge studies and ultra wideband generation, among others.

  17. Design of Current Mode Wide-band Semicondutor Detector for Reactor Fast Neutron Fluence Rate Measurement%测量反应堆快中子注量率的电流型宽禁带半导体探测器设计

    Institute of Scientific and Technical Information of China (English)

    苏春磊; 欧阳晓平; 李达; 刘洋; 宋晓靓; 余小任; 欧阳潇

    2014-01-01

    为解决强流混合场快中子注量率实时测量的难题,本文基于反冲质子法,以耐辐照性能强、噪声低的半绝缘型(SI)GaN半导体材料为基础,采用带石墨平衡体及聚乙烯转换靶的并联结构,设计补偿式电流型探测器的方案,有效地降低了γ射线灵敏度。利用该探测器测量了西安脉冲堆1#径向孔道内混合场的快中子注量率,其结果与已有测量结果符合较好,验证了该方案的可行性。%In order to solve the problem of fast neutron fluence rate real‐time measure‐ment in intense neutron‐gamma mixed field ,a new neutron fluence rate measurement scheme based on recoil proton method and semi‐insulating (SI) GaN detector was pro‐posed .The compensation current parallel structure with graphite balancer and polyethy‐ene converting target for fast neutron fluence rate detection ,w hich effectively reduced the interference of γ ray and improved detection sensitivity of neutron radiation ,was used in this scheme .This fast neutron fluence rate measurement scheme was implemen‐ted in the mixed field of Xi’an Pulsed Reactor 1# radial channel ,and the results show consistency with previous measurement results and the validity of the scheme .

  18. Measurements of fast neutron-induced fission data of Np-237

    Energy Technology Data Exchange (ETDEWEB)

    Win, Than; Saito, Keiichiro; Baba, Mamoru; Iwasaki, Tomohiko; Ibaraki, Masanobu; Miura, Takako; Sanami, Toshiya; Nauchi, Yasushi; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1998-03-01

    We have performed the following measurements for {sup 237}Np using the 4.5 MV Dynamitron accelerator of Tohoku University as the pulsed neutron source: (1) Prompt fission neutron spectrum for 0.62 MeV incident neutrons, and (2) Neutron-Induced fission cross-section between 10 and 100 keV. The prompt fission neutron spectrum was measured using TOF method with a heavily shielded NE213 scintillation detector. The Maxwellian temperature T{sub m} derived is 1.28 MeV, which is lower than that of 1.38 MeV in JENDL-3.2. The fission cross sections were measured between 10 - 100 keV. The results are between JENDL-3.2 and ENDF/B-VI. (author)

  19. Melt-cast organic glasses as high-efficiency fast neutron scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Joseph S.; Feng, Patrick L., E-mail: plfeng@sandia.gov

    2016-10-01

    In this work we report a new class of organic-based scintillators that combines several of the desirable attributes of existing crystalline, liquid, and plastic organic scintillators. The prepared materials may be isolated in single crystalline form or melt-cast to produce highly transparent glasses that have been shown to provide high light yields of up to 16,000 photons/MeVee, as evaluated against EJ-200 plastic scintillators and solution-grown trans-stilbene crystals. The prepared organic glasses exhibit neutron/gamma pulse-shape discrimination (PSD) and are compatible with wavelength shifters to reduce optical self-absorption effects that are intrinsic to pure materials such as crystalline organics. The combination of high scintillation efficiency, PSD capabilities, and facile scale-up via melt-casting distinguishes this new class of amorphous materials from existing alternatives.

  20. Measured and calculated fast neutron spectra in a depleted uranium and lithium hydride shielded reactor

    Science.gov (United States)

    Lahti, G. P.; Mueller, R. A.

    1973-01-01

    Measurements of MeV neutron were made at the surface of a lithium hydride and depleted uranium shielded reactor. Four shield configurations were considered: these were assembled progressively with cylindrical shells of 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, and 3-centimeter-thick depleted uranium. Measurements were made with a NE-218 scintillation spectrometer; proton pulse height distributions were differentiated to obtain neutron spectra. Calculations were made using the two-dimensional discrete ordinates code DOT and ENDF/B (version 3) cross sections. Good agreement between measured and calculated spectral shape was observed. Absolute measured and calculated fluxes were within 50 percent of one another; observed discrepancies in absolute flux may be due to cross section errors.

  1. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    Science.gov (United States)

    Evans, Louise G.; Swinhoe, Martyn T.; Menlove, Howard O.; Schwalbach, Peter; Baere, Paul De; Browne, Michael C.

    2013-11-01

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd2O3) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available 241AmLi (α,n) interrogation source strength of 5.7×104 s-1. Furthermore, the calibration range of the new collar has been extended to verify 235U content in variable PWR fuel designs in the presence of up to 32

  2. Absolute Calibration of Proportional Counter Based Fast Pulsed Neutron Detectors with Resolution Below 105 neutron/pulse

    Science.gov (United States)

    Tarifeño-Saldivia, A.; Mayer, R. E.; Pavez, C.; Soto, L.

    2014-05-01

    A method for absolute calibration of proportional counters for pulsed fast neutrons is presented. The method is based on the use of an isotopic standard source and development of a model for counting detected events from area of a signal compounded by single piled up neutron pulses. Effects of detection counting statistics and electrical background noise are also considered. The method is applied in detectors used for D-D neutron yield measurements in low emission plasma focus devices.

  3. Measurements of response functions of EJ-299-33A plastic scintillator for fast neutrons

    Science.gov (United States)

    Hartman, J.; Barzilov, A.; Peters, E. E.; Yates, S. W.

    2015-12-01

    Monoenergetic neutron response functions were measured for an EJ-299-33A plastic scintillator. The 7-MV Van de Graaff accelerator at the University of Kentucky Accelerator Laboratory was used to produce proton and deuteron beams for reactions with gaseous tritium and deuterium targets, yielding monoenergetic neutrons by means of the 3H(p,n)3He, 2H(d,n)3He, and 3H(d,n)4He reactions. The neutron energy was selected by tuning the charged-particle's energy and using the angular dependence of the neutron emission. The resulting response functions were measured for 0.1-MeV steps in neutron energy from 0.1 MeV to 8.2 MeV and from 12.2 MeV to 20.2 MeV. Experimental data were processed using a procedure for digital pulse-shape discrimination, which allowed characterization of the response functions of the plastic scintillator to neutrons only. The response functions are intended for use in neutron spectrum unfolding methods.

  4. Measuring the Density of Different Materials by Using the Collimated Fast Neutron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Sudac, D.; Nad, K.; Orlic, Z.; Obhodas, J. [Rudjer Boskovic Institute, Bijenicka c. 54, 10000 Zagreb (Croatia); Valkovic, V. [Rudjer Boskovic Institute, Zagreb (Croatia); Kvinticka 62, Zagreb (Croatia)

    2015-07-01

    It was demonstrated in the previous work that various threat materials could be detected inside the sea going cargo container by measuring the three variables, carbon and oxygen concentration and density of investigated material. Density was determined by measuring transmitted neutrons, which is not always practical in terms of setting up the instrument geometry. In order to enable more geometry flexibility, we have investigated the possibility of using the scattered neutrons in cargo material identification. For that purpose, the densities of different materials were measured depending on the position of neutron detectors and neutron generator with respect to the target position. One neutron detector was put above the target, one behind and one in front of the target, above the neutron generator. It was shown that all three positions of neutron detectors can be successfully used to measure the target density, but only if the detected neutrons are successfully discriminated from the gamma rays. Although the associated alpha particle technique/associate particle imaging (API) was used to discriminate the neutrons from the gamma rays, it is believed that the same results would be obtained by using the pulse shape discrimination method. In that way API technique can be avoided and the neutron generator which produces much higher beam intensity than 10{sup 8} n/s can be used. (authors)

  5. Used fuel storage monitoring using novel 4He scintillation fast neutron detectors and neutron energy discrimination analysis

    Science.gov (United States)

    Kelley, Ryan P.

    With an increasing quantity of spent nuclear fuel being stored at power plants across the United States, the demand exists for a new method of cask monitoring. Certifying these casks for transportation and long-term storage is a unique dilemma: their sealed nature lends added security, but at the cost of requiring non-invasive measurement techniques to verify their contents. This research will design and develop a new method of passively scanning spent fuel casks using 4He scintillation detectors to make this process more accurate. 4He detectors are a relatively new technological development whose full capabilities have not yet been exploited. These detectors take advantage of the high 4He cross section for elastic scattering at fast neutron energies, particularly the resonance around 1 MeV. If one of these elastic scattering interactions occurs within the detector, the 4He nucleus takes energy from the incident neutron, then de-excites by scintillation. Photomultiplier Tubes (PMTs) at either end of the detector tube convert this emitted light into an electrical signal. The goal of this research is to use the neutron spectroscopy features of 4He scintillation detectors to maintain accountability of spent fuel in storage. This project will support spent fuel safeguards and the detection of fissile material, in order to minimize the risk of nuclear proliferation and terrorism.

  6. 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...

  7. Study on γ-ray exposure buildup factors and fast neutron-shielding properties of some building materials

    Science.gov (United States)

    Singh, Vishwanath P.; Badiger, N. M.; El-Khayatt, A. M.

    2014-06-01

    We have computed γ-ray exposure buildup factors (EBF) of some building materials; glass, marble, flyash, cement, limestone, brick, plaster of paris (POP) and gypsum for energy 0.015-15 MeV up to 40 mfp (mfp, mean free path) penetration depth. Also, the macroscopic effective removal cross-sections (ΣR) for fast neutron were calculated. We discussed the dependency of EBF values on photon energy, penetration depth and chemical elements. The half-value layer and kinetic energy per unit mass relative to air of building materials were calculated for assessment of shielding effectiveness. Shielding thicknesses for glass, marble, flyash, cement, limestone and gypsum plaster (or Plaster of Paris, POP) were found comparable with ordinary concrete. Among the studied materials limestone and POP showed superior shielding properties for γ-ray and neutron, respectively. Radiation safety inside houses, schools and primary health centers for sheltering and annual dose can be assessed by the determination of shielding parameters of common building materials.

  8. Different dose rate-dependent responses of human melanoma cells and fibroblasts to low dose fast neutrons.

    Science.gov (United States)

    Dionet, Claude; Müller-Barthélémy, Melanie; Marceau, Geoffroy; Denis, Jean-Marc; Averbeck, Dietrich; Gueulette, John; Sapin, Vincent; Pereira, Bruno; Tchirkov, Andrei; Chautard, Emmanuel; Verrelle, Pierre

    2016-09-01

    To analyze the dose rate influence in hyper-radiosensitivity (HRS) of human melanoma cells to very low doses of fast neutrons and to compare to the behaviour of normal human skin fibroblasts. We explored different neutron dose rates as well as possible implication of DNA double-strand breaks (DSB), apoptosis, and energy-provider adenosine-triphosphate (ATP) levels during HRS. HRS in melanoma cells appears only at a very low dose rate (VLDR), while a high dose rate (HDR) induces an initial cell-radioresistance (ICRR). HRS does not seem to be due either to DSB or to apoptosis. Both phenomena (HRS and ICRR) appear to be related to ATP availability for triggering cell repair. Fibroblast survival after neutron irradiation is also dose rate-dependent but without HRS. Melanoma cells or fibroblasts exert their own survival behaviour at very low doses of neutrons, suggesting that in some cases there is a differential between cancer and normal cells radiation responses. Only the survival of fibroblasts at HDR fits the linear no-threshold model. This new insight into human cell responses to very low doses of neutrons, concerns natural radiations, surroundings of accelerators, proton-therapy devices, flights at high altitude. Furthermore, ATP inhibitors could increase HRS during high-linear energy transfer (high-LET) irradiation.

  9. Use of chemical etching of CR-39 foils at elevated temperature for fast neutron personnel monitoring in India

    Science.gov (United States)

    Sathian, Deepa; Rohatgi, Rupali; Jayalakshmi, V.; Marathe, P. K.; Nair, Sarala; Kolekar, R. V.; Chourasiya, G.; Kannan, S.

    2009-06-01

    CR-39 Solid State Nuclear Track Detecting foils (SSNTD), along with 1 mm thick polyethylene radiator, sealed in triple laminated pouches, are used for country wide Fast Neutron Personnel Monitoring in India. With the present system of processing by elevated temperature electrochemical etching (ETECE) and evaluation using automatic image analysis, only 16 foils are processed at a time and it is useful over the dose equivalent range 0.2 mSv to 10 mSv. It has been reported that, by processing CR-39 of good detection efficiency by chemical etching at elevated temperature, more numbers of foils can be processed simultaneously. In the present study, CR-39 foils from Pershore Moulding (UK) have been chemically etched using 7 N KOH under various conditions of temperature and etching durations and evaluated using high magnification microscope. The duration of chemical etching, has been optimized at a constant temperature of 60°C for chemical etching process. The characteristics of the chemically etched CR-39 foils are compared with the characteristics of the CR-39 foils processed by the existing system of ETECE and the detailed results are presented in the full text of the paper. It has been observed that by chemical etching process, the dose equivalent range of CR-39 foils can be extended above 60 mSv.

  10. Characterization and simulation of fast neutron detectors based on surface-barrier VPE GaAs structures with polyethylene converter

    Science.gov (United States)

    Chernykh, A. V.; Chernykh, S. V.; Baryshnikov, F. M.; Didenko, S. I.; Burtebayev, N.; Britvich, G. I.; Kostin, M. Yu.; Chubenko, A. P.; Nassurlla, Marzhan; Nassurlla, Maulen; Kerimkulov, Zh.; Zholdybayev, T.; Glybin, Yu. N.; Sadykov, T. Kh.

    2016-12-01

    Fast neutron detectors with an active area of 80 mm2 based on surface-barrier VPE GaAs structures were fabricated and tested. Polyethylene with density of 0.90 g/cm3 was used as a converter layer. The recoil-proton surface-barrier sensor was fabricated on high purity VPE GaAs epilayers with a thickness of 50 μm. The neutron detection efficiency measured with a 241Am-Be source was 1.30 · 10-3 puls./neutr. for the PE converter thickness of 670 μm. The signal-to-gamma-background ratio was at the level of 50. Simulation of the detector characteristics with Geant4 toolkit has showed good correlation with the experimental data and allowed to estimate the maximal theoretical detection efficiency of the detector which is determined by the PE converter and equals to 1.37 · 10-3 puls./neutr. The difference between the measured and simulated values of the detection efficiency is due to the fact that the events with energies below 0.5 MeV were not taken into account during the measurements.

  11. On the possible use of the MASURCA reactor as a flexible, high-intensity, fast neutron beam facility

    Science.gov (United States)

    Dioni, Luca; Jacqmin, Robert; Sumini, Marco; Stout, Brian

    2017-09-01

    In recent work [1, 2], we have shown that the MASURCA research reactor could be used to deliver a fairly-intense continuous fast neutron beam to an experimental room located next to the reactor core. As a consequence of the MASURCA favorable characteristics and diverse material inventories, the neutron beam intensity and spectrum can be further tailored to meet the users' needs, which could be of interest for several applications. Monte Carlo simulations have been performed to characterize in detail the extracted neutron (and photon) beam entering the experimental room. These numerical simulations were done for two different bare cores: A uranium metallic core (˜30% 235U enriched) and a plutonium oxide core (˜25% Pu fraction, ˜78% 239Pu). The results show that the distinctive resonance energy structures of the two core leakage spectra are preserved at the channel exit. As the experimental room is large enough to house a dedicated set of neutron spectrometry instruments, we have investigated several candidate neutron spectrum measurement techniques, which could be implemented to guarantee well-defined, repeatable beam conditions to users. Our investigation also includes considerations regarding the gamma rays in the beams.

  12. Transmission of laser pulses with high output beam quality using step-index fibers having large cladding

    Science.gov (United States)

    Yalin, Azer P; Joshi, Sachin

    2014-06-03

    An apparatus and method for transmission of laser pulses with high output beam quality using large core step-index silica optical fibers having thick cladding, are described. The thick cladding suppresses diffusion of modal power to higher order modes at the core-cladding interface, thereby enabling higher beam quality, M.sup.2, than are observed for large core, thin cladding optical fibers. For a given NA and core size, the thicker the cladding, the better the output beam quality. Mode coupling coefficients, D, has been found to scale approximately as the inverse square of the cladding dimension and the inverse square root of the wavelength. Output from a 2 m long silica optical fiber having a 100 .mu.m core and a 660 .mu.m cladding was found to be close to single mode, with an M.sup.2=1.6. Another thick cladding fiber (400 .mu.m core and 720 .mu.m clad) was used to transmit 1064 nm pulses of nanosecond duration with high beam quality to form gas sparks at the focused output (focused intensity of >100 GW/cm.sup.2), wherein the energy in the core was 20 mJ delivered for 50 ns pulses) without damaging the silica fiber.

  13. Novel technologies and theoretical models in radiation therapy of cancer patients using 6.3 MeV fast neutrons produced by U-120 cyclotron

    Science.gov (United States)

    Musabaeva, L. I.; Startseva, Zh. A.; Gribova, O. V.; Velikaya, V. V.; Lisin, V. A.

    2016-08-01

    The analysis of clinical use of neutron therapy with 6 MeV fast neutrons compared to conventional radiation therapy was carried out. The experience of using neutron and mixed neutron and photon therapy in patients with different radio-resistant malignant tumors shows the necessity of further studies and development of the novel approaches to densely-ionizing radiation. The results of dosimetry and radiobiological studies have been the basis for planning clinical programs for neutron therapy. Clinical trials over the past 30 years have shown that neutron therapy successfully destroys radio-resistant cancers, including salivary gland tumors, adenoidcystic carcinoma, inoperable sarcomas, locally advanced head and neck tumors, and locally advanced prostate cancer. Radiation therapy with 6.3 MeV fast neutrons used alone and in combination with photon therapy resulted in improved long-term treatment outcomes in patients with radio-resistant malignant tumors.

  14. Simulation analysis and exp erimental verification of fast neutron radiography%快中子照相模拟分析与实验验证∗

    Institute of Scientific and Technical Information of China (English)

    鲁昌兵; 许鹏; 鲍杰; 王朝辉; 张凯; 任杰; 刘艳芬

    2015-01-01

    Expression for the formation of the pixel value of fast neutron radiography has been derived. The contrast inequality for the photograph has been established using the derived expression;then the relationships of the image contrast with the source intensity, the exposure time, and the scattering have therefore been obtained through the acquired inequality. A simulation on the process of fast neutron radiography is carried out based on the pixel value analysis, and the spatial resolution and image contrast have also been considered. Simulation results show that the spatial resolution is better than that from experiments and the effect of image contrast is equivalent to that of the experiments. Finally, various samples, such as Pb samples, with slits, Fe samples with square holes and multiple materials-combined samples, are used to test the performance of the simulation. Results demonstrate that the simulations are in agreement with the experiments, thus providing a reference to the future experimental design and engineering application.

  15. Effects of fractionated doses of fast neutrons or photons on the canine brain: evaluation by computerized tomography and evoked response recording

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, E.W.; Davis, D.O.; Gaskill, J.W.; Deye, J.A.; Fisher, M.P.; Sloan, G.E.; Rogers, C.C.

    1980-12-01

    The use of fast neutrons in the treatment of cancer necessitates a knowledge of the normal tissue responses. This study was designed to compare the late effects of fractionated doses of fast neutrons with fractionated doses of photons on canine brains by evoked response recording and viewing computerized tomograms (CT). A relative biological effectiveness (RBE) of 4 was obtained for normal brain tissue assessed by mortality and onset of neurologic symptoms. Every three months post-irradiation, visual and sensory evoked responses were recorded. Changes over time appeared to be minimal; however, computerized tomographs showed marked brain shrinkage. A method of quantitating cerebrospinal fluid and parenchymal volumes from scans is described and future use of these CT ratios to generate dose response curves and RBE values is postulated.

  16. Novel technologies and theoretical models in radiation therapy of cancer patients using 6.3 MeV fast neutrons produced by U-120 cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Musabaeva, L. I., E-mail: musabaevaLI@oncology.tomsk.ru; Lisin, V. A., E-mail: Lisin@oncology.tomsk.ru [Tomsk Cancer Research Institute, Kooperativny Street 5, Tomsk, 634050 (Russian Federation); Startseva, Zh. A., E-mail: zhanna.alex@rambler.ru; Gribova, O. V., E-mail: gribova79@mail.ru; Velikaya, V. V., E-mail: viktoria.v.v@inbox.ru [Tomsk Cancer Research Institute, Kooperativny Street 5, Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk, 634050 (Russian Federation)

    2016-08-02

    The analysis of clinical use of neutron therapy with 6 MeV fast neutrons compared to conventional radiation therapy was carried out. The experience of using neutron and mixed neutron and photon therapy in patients with different radio-resistant malignant tumors shows the necessity of further studies and development of the novel approaches to densely-ionizing radiation. The results of dosimetry and radiobiological studies have been the basis for planning clinical programs for neutron therapy. Clinical trials over the past 30 years have shown that neutron therapy successfully destroys radio-resistant cancers, including salivary gland tumors, adenoidcystic carcinoma, inoperable sarcomas, locally advanced head and neck tumors, and locally advanced prostate cancer. Radiation therapy with 6.3 MeV fast neutrons used alone and in combination with photon therapy resulted in improved long-term treatment outcomes in patients with radio-resistant malignant tumors.

  17. Fast neutron cross section measurements. Final technical report, March 1, 1987--September 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Knoll, G.F.

    1997-06-01

    The time-of-flight technique was used with the ring scattering geometry in a laboratory with low neutron scattering background to measure the angular distributions of the cross sections for elastic and inelastic scattering of 14 MeV neutrons in natural chromium, iron, nickel, and niobium. Specifically for inelastic scattering included were: the 1.43 MeV and 4.56 MeV levels of {sup 52}Cr, the 0.85 MeV level, and (2.94-3.12) MeV and (4.46-4.51) MeV level groups of {sup 56}Fe, the 1.33 MeV level of {sup 60}Ni combined with the 1.45 MeV level of {sup 58}Ni, and the 4.48 MeV level of {sup 58}Ni. Pulses of neutrons with time width of 0.9-1.1 ns were produced via the {sup 3}H(d,n){sup 4}He reaction in a 150 keV Cockcroft-Walton linear accelerator, with average intensities of 9x10{sup 8} n/s. The energy of the incident neutrons was between 14.75 MeV (at 16{degree}) and 13.48 MeV (at 160{degree}). High purity scattering ring samples were used. The scattering angles ranged from {approx}16{degree} to {approx}150{degree}, for iron, chromium, and nickel, and from {approx}16{degree} to {approx}160{degree} for niobium, with a typical step of {approx}10{degree}. High purity ring samples were used.

  18. Timing and position response of a block detector for fast neutron time-of-flight imaging

    Science.gov (United States)

    Laubach, M. A.; Hayward, J. P.; Zhang, X.; Cates, J. W.

    2014-11-01

    Our research effort seeks to improve the spatial and timing performance of a block detector made of a pixilated plastic scintillator (EJ-200), first demonstrated as part of Oak Ridge National Laboratory's Advanced Portable Neutron Imaging System. Improvement of the position and time response is necessary to achieve better resolution and contrast in the images of shielded special nuclear material. Time-of-flight is used to differentiate between gamma and different sources of neutrons (e.g., transmission and fission neutrons). Factors limiting the timing and position performance of the neutron detector have been revealed through simulations and measurements. Simulations have suggested that the degradation in the ability to resolve pixels in the neutron detector is due to those interactions occurring near the light guide. The energy deposition within the neutron detector is shown to affect position performance and imaging efficiency. This examination details how energy cuts improve the position performance and degrade the imaging efficiency. Measurements have shown the neutron detector to have a timing resolution of σ=238 ps. The majority of this timing uncertainty is from the depth-of-interaction (DOI) of the neutron which is confirmed by simulations and analytical calculations.

  19. 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.)

  20. The European JASMIN Project for the Development of a New Safety Simulation Code, ASTEC-Na, for Na-cooled Fast Neutron Reactors

    OpenAIRE

    GIRAULT N.; VAN DORSSELAERE J.p.; Jacq, F.; BRILLANT G.; KISSANE Martin; BANDINI, G; Buck,M.; CHAMPIGNY J.; Hering, W; Perez-Martin, S.; Herranz, L; RAISON Philippe; Reinke, N; TUCEK Kamil; VERWAERDE D.

    2012-01-01

    The 4-year JASMIN collaborative project, involving 9 organizations, was launched by IRSN end of 2011 within the 7th European R&D Framework Programme on the enhancement of Na-cooled Fast Neutron Reactors (SFR) safety for a higher resistance to severe accidents. The project aims at developing a new European simulation code, ASTEC-Na, with a modern architecture, sufficiently flexible to account for innovative reactor designs and eventually new types of fuel and claddings and accounting for resul...

  1. Conceptual study of a compact accelerator-driven neutron source for radioisotope production, boron neutron capture therapy and fast neutron therapy

    CERN Document Server

    Angelone, M; Rollet, S

    2002-01-01

    The feasibility of a compact accelerator-driven device for the generation of neutron spectra suitable for isotope production by neutron capture, boron neutron capture therapy and fast neutron therapy, is analyzed by Monte Carlo simulations. The device is essentially an extension of the activator proposed by Rubbia left bracket CERN/LHC/97-04(EET) right bracket , in which fast neutrons are diffused and moderated within a properly sized lead block. It is shown that by suitable design of the lead block, as well as of additional elements of moderating and shielding materials, one can generate and exploit neutron fluxes with the spectral features required for the above applications. The linear dimensions of the diffusing-moderating device can be limited to about 1 m. A full-scale device for all the above applications would require a fast neutron source of about 10**1**4 s**-**1, which could be produced by a 1 mA, 30 MeV proton beam impinging on a Be target. The concept could be tested at the Frascati Neutron Gener...

  2. Performance of a plasma window for a high pressure differentially pumped deuterium gas target for mono-energetic fast neutron production - Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Beer, A. de; Hershcovitch, A.; Franklyn, C.B.; Straaten, S. van; Guzek, J. E-mail: jguzek@debeers.co.za

    2000-09-01

    The reactions D(d,n){sup 3}He and T(d,n){sup 4}He are frequently used for production of the mono-energetic or quasi mono-energetic neutron beams but successful applications are often limited by the intensity of the generated neutron beams. The development of a suitable neutron source for such applications as studies of resonance phenomena, fast neutron radiography, selective fast neutron activation, explosives and contraband detection and others, depends on the output ion current of the accelerator and the design of the target system. A practical solution for a high pressure gas target was previously developed and successfully implemented at De Beers Diamond Research Laboratory in Johannesburg (Guzek et al., 1999), but it is limited to applications using low (<20%) duty cycle accelerators. The concept of a plasma window for the separation of a high pressure gas target region and accelerator vacuum, that was originally developed by Hershcovitch (1995) for electron welding applications, may be suitable for operation with continuous wave accelerators at high particle current output. Preliminary test results, which have been performed with various gases (argon, helium and deuterium), indicate that implementation of the plasma window into a gas target system, for the production of intense mono-energetic fast neutron beams will be achievable.

  3. High Power, Pulsed, RF Generation from Nonlinear Lumped Element Transmission Lines (NLETLs)

    Science.gov (United States)

    2011-02-05

    Matlab Implementation of Direct Method on KdV Equation 225 B Periodic Cnoidal Wave Train Solution of KdV Equation with Elliptic Inte- grals 228...in part to jus- tify the labelling of XLETL pulses as solitons since the KdV equation is known to support such solutions . An assessment of the... KdV equation 4.3 are found by this method in section 4.4 and compared qualitatively with numerical and experimental NLETL voltage waveforms. The

  4. Comparison of Performance Metrics for QPSK and OQPSK Transmission Using Root Raised Cosine and Raised Cosine Pulse shaping Filters for Applications in Mobile Communication

    CERN Document Server

    Chattopadhyay, Sudipta

    2009-01-01

    Quadrature Phase Shift Keying (QPSK) and Offset Quadrature Phase Shift Keying (OQPSK) are two well accepted modulation techniques used in Code Division Multiple Access (CDMA) system. The Pulse Shaping Filters play an important role in digital transmission. The type of Pulse Shaping Filter used, and its behavior would influence the performance of the communication system. This in turn, would have an effect on the performance of the Mobile Communication system, in which the digital communication technique has been employed. In this paper we have presented comparative study of some performance parameters or performance metrics of a digital communication system like, Error Vector Magnitude (EVM), Magnitude Error, Phase Error and Bandwidth Efficiency for a QPSK transmission system. Root Raised Cosine (RRC) and Raised Cosine (RC) Pulse shaping filters have been used for comparison. The measurement results serve as a guideline to the system designer to select the proper pulse shaping filter with the appropriate valu...

  5. Electromagnetic plane-wave pulse transmission into a Lorentz half-space.

    Science.gov (United States)

    Cartwright, Natalie A

    2011-12-01

    The propagation of an electromagnetic plane-wave signal obliquely incident upon a Lorentz half-space is studied analytically. Time-domain asymptotic expressions that increase in accuracy with propagation distance are derived by application of uniform saddle point methods on the Fourier-Laplace integral representation of the transmitted field. The results are shown to be continuous in time and comparable with numerical calculations of the field. Arrival times and angles of refraction are given for prominent transient pulse features and the steady-state signal.

  6. Performance Study of an aSi Flat Panel Detector for Fast Neutron Imaging of Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, M.; Mauerhofer, E. [Institute of Energy and Climate Research - Nuclear Waste Management and Reactor Safety, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Engels, R.; Kemmerling, G. [Central Institute for Engineering, Electronics and Analytics - Electronic Systems, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Frank, M. [MATHCCES - Department of Mathematics, RWTH Aachen University, 52062 Aachen (Germany); Havenith, A.; Kettler, J.; Klapdor-Kleingrothaus, T. [Institute of Nuclear Engineering and Technology Transfer, RWTH Aachen University, 52062 Aachen (Germany); Schitthelm, O. [Corporate Technology, Siemens AG, 91058 Erlangen (Germany)

    2015-07-01

    Radioactive waste must be characterized to check its conformance for intermediate storage and final disposal according to national regulations. For the determination of radio-toxic and chemo-toxic contents of radioactive waste packages non-destructive analytical techniques are preferentially used. Fast neutron imaging is a promising technique to assay large and dense items providing, in complementarity to photon imaging, additional information on the presence of structures in radioactive waste packages. Therefore the feasibility of a compact Neutron Imaging System for Radioactive waste Analysis (NISRA) using 14 MeV neutrons is studied in a cooperation framework of Forschungszentrum Juelich GmbH, RWTH Aachen University and Siemens AG. However due to the low neutron emission of neutron generators in comparison to research reactors the challenging task resides in the development of an imaging detector with a high efficiency, a low sensitivity to gamma radiation and a resolution sufficient for the purpose. The setup is composed of a commercial D-T neutron generator (Genie16GT, Sodern) with a surrounding shielding made of polyethylene, which acts as a collimator and an amorphous silicon flat panel detector (aSi, 40 x 40 cm{sup 2}, XRD-1642, Perkin Elmer). Neutron detection is achieved using a general propose plastic scintillator (EJ-260, Eljen Technology) linked to the detector. The thermal noise of the photodiodes is reduced by employing an entrance window made of aluminium. Optimal gain and integration time for data acquisition are set by measuring the response of the detector to the radiation of a 500 MBq {sup 241}Am-source. Detector performance was studied by recording neutron radiography images of materials with various, but well known, chemical compositions, densities and dimensions (Al, C, Fe, Pb, W, concrete, polyethylene, 5 x 8 x 10 cm{sup 3}). To simulate gamma-ray emitting waste radiographs in presence of a gamma-ray sources ({sup 60}Co, {sup 137}Cs, {sup 241

  7. Soil water content determination with cosmic-ray neutron sensor: Correcting aboveground hydrogen effects with thermal/fast neutron ratio

    Science.gov (United States)

    Tian, Zhengchao; Li, Zizhong; Liu, Gang; Li, Baoguo; Ren, Tusheng

    2016-09-01

    The cosmic-ray neutron sensor (CRNS), which estimates field scale soil water content, bridges the gap between point measurement and remote sensing. The accuracy of CRNS measurements, however, is affected by additional hydrogen pools (e.g., vegetation, snow, and rainfall interception). The objectives of this study are to: (i) evaluate the accuracy of CRNS estimates in a farmland system using depth and horizontal weighted point measurements, (ii) introduce a novel method for estimating the amounts of hydrogen from biomass and snow cover in CRNS data, and (iii) propose a simple approach for correcting the influences of aboveground hydrogen pool (expressed as aboveground water equivalent, AWE) on CRNS measurements. A field experiment was conducted in northeast China to compare soil water content results from CRNS to in-situ data with time domain reflectometry (TDR) and neutron probe (NP) in the 0-40 cm soil layers. The biomass water equivalent (BWE) and snow water equivalent (SWE) were observed to have separate linear relationships with the thermal/fast neutron ratio, and the dynamics of BWE and SWE were estimated correctly in the crop seasons and snow-covered seasons, respectively. A simple approach, which considered the AWE, AWE at calibration, and the effective measurement depth of CRNS, was introduced to correct the errors caused by BWE and SWE. After correction, the correlation coefficients between soil water contents determined by CRNS and TDR were 0.79 and 0.77 during the 2014 and 2015 crop seasons, respectively, and CRNS measurements had RMSEs of 0.028, 0.030, and 0.039 m3 m-3 in the 2014 and 2015 crop seasons and the snow-covered seasons, respectively. The experimental results also indicated that the accuracies of CRNS estimated BWE and SWE were affected by the distributions of aboveground hydrogen pools, which were related to the height of the CRNS device above ground surface.

  8. MCNPX simulations of the silicon carbide semiconductor detector response to fast neutrons from D-T nuclear reaction

    Science.gov (United States)

    Sedlačková, Katarína; Šagátová, Andrea; Zat'ko, Bohumír; Nečas, Vladimír; Solar, Michael; Granja, Carlos

    2016-09-01

    Silicon Carbide (SiC) has been long recognized as a suitable semiconductor material for use in nuclear radiation detectors of high-energy charged particles, gamma rays, X-rays and neutrons. The nuclear interactions occurring in the semiconductor are complex and can be quantified using a Monte Carlo-based computer code. In this work, the MCNPX (Monte Carlo N-Particle eXtended) code was employed to support detector design and analysis. MCNPX is widely used to simulate interaction of radiation with matter and supports the transport of 34 particle types including heavy ions in broad energy ranges. The code also supports complex 3D geometries and both nuclear data tables and physics models. In our model, monoenergetic neutrons from D-T nuclear reaction were assumed as a source of fast neutrons. Their energy varied between 16 and 18.2 MeV, according to the accelerating voltage of the deuterons participating in D-T reaction. First, the simulations were used to calculate the optimum thickness of the reactive film composed of High Density PolyEthylene (HDPE), which converts neutral particles to charged particles and thusly enhancing detection efficiency. The dependency of the optimal thickness of the HDPE layer on the energy of the incident neutrons has been shown for the inspected energy range. Further, from the energy deposited by secondary charged particles and recoiled ions, the detector response was modeled and the effect of the conversion layer on detector response was demonstrated. The results from the simulations were compared with experimental data obtained for a detector covered by a 600 and 1300 μm thick conversion layer. Some limitations of the simulations using MCNPX code are also discussed.

  9. Modeling Methods for the Main Switch of High Pulsed-Power Facilities Based on Transmission Line Code

    Science.gov (United States)

    Hu, Yixiang; Zeng, Jiangtao; Sun, Fengju; Wei, Hao; Yin, Jiahui; Cong, Peitian; Qiu, Aici

    2014-09-01

    Based on the transmission line code (TLCODE), a circuit model is developed here for analyses of main switches in the high pulsed-power facilities. With the structure of the ZR main switch as an example, a circuit model topology of the switch is proposed, and in particular, calculation methods of the dynamic inductance and resistance of the switching arc are described. Moreover, a set of closed equations used for calculations of various node voltages are theoretically derived and numerically discretized. Based on these discrete equations and the Matlab program, a simulation procedure is established for analyses of the ZR main switch. Voltages and currents at different key points are obtained, and comparisons are made with those of a PSpice L-C model. The comparison results show that these two models are perfectly in accord with each other with discrepancy less than 0.1%, which verifies the effectiveness of the TLCODE model to a certain extent.

  10. Bundled hollow optical fibers for transmission of high-peak-power Q-switched Nd:YAG laser pulses.

    Science.gov (United States)

    Yilmaz, Ozgur; Miyagi, Mitsunobu; Matsuura, Yuji

    2006-09-20

    A hollow-fiber bundle was designed and used to deliver high-peak-power pulses from a Q-switched Nd:YAG laser. An 80 cm long bundle with a total diameter of 5.5 mm was composed of 37 glass capillaries with bore diameters of 0.7 mm. Beam-resizing optics with two lenses were used to couple the laser beam into the bundle. The measured coupling loss due to the limited aperture ratio of the bundle was 2.3 dB, and the transmission loss at wavelengths of 1064 and 532 nm was 0.3 dB. When an inert gas flowed through the bores of the capillaries, the maximum output pulse energy was 200 mJ, which was the limit of the laser used in the experiment. Hollow-fiber bundles withstand irradiation better than single hollow fibers and silica-glass optical fibers do. They are suitable for many dermatological applications because they can be used to irradiate a large area.

  11. Experimental study of transmission of a pulsed focused beam through a skull phantom in nonlinear regime

    Energy Technology Data Exchange (ETDEWEB)

    Tsysar, S. A., E-mail: sergey@acs366.phys.msu.ru; Nikolaeva, A. V.; Khokhlova, V. A.; Yuldashev, P. V. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Svet, V. D. [Andreyev Acoustics Institute, 4, Shvernik Street, Moscow 117036 (Russian Federation); Sapozhnikov, O. A. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105 (United States)

    2015-10-28

    In the paper the use of receiving and radiating system, which allows to determine the parameters of bone by nonlinear pulse-echo technique and to image of brain structures through the skull bones, was proposed. Accuracy of the skull bone characterization is due to higher measured harmonic and is significantly better than in linear case. In the experimental part focused piezoelectric transducer with diameter 100 mm, focal distance 100 mm, the frequency of 1.092 MHz was used. It was shown that skull bone profiling can be performed with the use of 3rd harmonic since 1st harmonic can be used for visualization of the underlying objects. The use of wideband systems for both skull profiling and brain visualization is restricted by skull attenuation and resulting low effective sensitivity.

  12. Long range transmission loss of broadband seismic pulses in the Arctic under ice-free conditions.

    Science.gov (United States)

    Thode, Aaron; Kim, Katherine H; Greene, Charles R; Roth, Ethan

    2010-10-01

    In 2008 the Louis S. St-Laurent (LSSL) surveyed deep Arctic waters using a three-airgun seismic source. Signals from the seismic survey were detected between 400 km and 1300 km range on a directional autonomous acoustic recorder deployed in water 53 m deep off the Alaskan North Slope. Observations of received signal levels between 10-450 Hz versus LSSL range roughly fit a cylindrical transmission loss model plus 0.01 dB/km attenuation in deep ice-free waters, and fit previous empirical models in ice-covered waters. The transition between ice-free and ice-covered propagation conditions shifted 200 km closer to the recorder during the survey.

  13. Fast neutron environments.

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, Thomas Edward; Kotula, Paul Gabriel; Lu, Ping; Brewer, Luke N. (Naval Postgraduate School, Monterey, CA); Goods, Steven Howard (Sandia National Laboratories, Livermore, CA); Foiles, Stephen Martin; Puskar, Joseph David; Hattar, Khalid Mikhiel; Doyle, Barney Lee; Boyce, Brad Lee; Clark, Blythe G.

    2011-10-01

    The goal of this LDRD project is to develop a rapid first-order experimental procedure for the testing of advanced cladding materials that may be considered for generation IV nuclear reactors. In order to investigate this, a technique was developed to expose the coupons of potential materials to high displacement damage at elevated temperatures to simulate the neutron environment expected in Generation IV reactors. This was completed through a high temperature high-energy heavy-ion implantation. The mechanical properties of the ion irradiated region were tested by either micropillar compression or nanoindentation to determine the local properties, as a function of the implantation dose and exposure temperature. In order to directly compare the microstructural evolution and property degradation from the accelerated testing and classical neutron testing, 316L, 409, and 420 stainless steels were tested. In addition, two sets of diffusion couples from 316L and HT9 stainless steels with various refractory metals. This study has shown that if the ion irradiation size scale is taken into consideration when developing and analyzing the mechanical property data, significant insight into the structural properties of the potential cladding materials can be gained in about a week.

  14. Factors that affect pulse wave time transmission in the monitoring of cardiovascular system.

    Science.gov (United States)

    Foo, Jong Yong A; Wilson, Stephen J; Wang, Ping

    2008-04-01

    Vascular transit time (VTT) can be defined as the first heart sound of the phonocardiography (PCG) signal to its arrival at the photoplethysmography (PPG). Studies have shown that monitoring VTT can be useful as an early prognosis of cardiac diseases. However, there is limited study conducted to understand the physiologic factors that affect VTT at the upper limb. In this study, the effect associated with difference in subject height, weight, heart rate, mean arterial pressure, systolic and diastolic blood pressure was assessed. A study population of 31 healthy Chinese young adults (21 male; age range 20-33 yr) were recruited. PCG and PPG were recorded non-invasively from the fourth costal cartilage at the midclavicular line and right index finger, respectively. A single sample Kolmogorov-Smirnov (K-S) goodness-of-fit hypothesis test, a univariate linear regression analysis, and a multiple linear regression modelling were performed on the VTT measurements and the associated physiologic parameters. The results from the K-S test showed that the physiologic parameters and VTT measurements had a normal cumulative distribution function. Furthermore, all physiologic parameters were significantly and independently related to VTT (P VTT regression model was also derived (r (2) = 0.79). The findings herein suggest that the observed physiologic parameters have significant contributions to the nominal VTT value of a subject. Unlike pulse transit time, the VTT technique has the added advantage that the left ventricular isometric contraction time is not included in the timing derivation.

  15. Neutron Transmission through Sapphire Crystals

    DEFF Research Database (Denmark)

    Sapphire crystals are excellent filters of fast neutrons, while at the same time exhibit moderate to very little absorption at smaller energies. We have performed an extensive series of measurements in order to quantify the above effect. Alongside our experiments, we have performed a series...... of simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Those simulations were part of the effort of validating and improving the newly developed interface between the Monte-Carlo neutron transport code MCNP and the Monte Carlo ray-tracing code McStas....

  16. 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

  17. Aspects of the physics and chemistry of water radiolysis by fast neutrons and fast electrons in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    McCracken, D.R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Tsang, K.T. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Laughton, P.J

    1998-09-01

    Detailed radiation physics calculations of energy deposition have been done for the coolant of CANDU reactors and Pressurized Water Reactors (PWRs). The geometry of the CANDU fuel channel was modelled in detail. Fluxes and energy-deposition rates for neutrons, recoil ions, photons, and fast electrons have been calculated using MCNP4B, WIMS-AECL, and specifically derived energy-transfer factors. These factors generate the energy/flux spectra of recoil ions from fast-neutron energy/flux spectra. The energy spectrum was divided into 89 discrete ranges (energy bins).The production of oxidizing species and net coolant radiolysis can be suppressed by the addition of hydrogen to the coolant of nuclear reactors. It is argued that the net dissociation of coolant by gamma rays is suppressed by lower levels of excess hydrogen than when dissociation is by ion recoils. This has consequences for the modelling of coolant radiolysis by homogeneous kinetics. More added hydrogen is required to stop water radiolysis by recoil ions acting alone than if recoil ions and gamma rays acted concurrently in space and time. Homogeneous kinetic models and experimental data suggest that track overlap is very inefficient in providing radicals from gamma-ray tracks to recombine molecular products in ion-recoil tracks. An inhomogeneous chemical model is needed that incorporates ionizing-particle track structure and track overlap. Such a model does not yet exist, but a number of limiting cases using homogeneous kinetics are discussed. There are sufficient uncertainties and contradictions in the data relevant to the radiolysis of reactor coolant that the relatively high CHC's (critical hydrogen concentration) observed in NRU reactor experiments (compared to model predictions) may be explainable by errors in fundamental data and understanding of water radiolysis under reactor conditions. The radiation chemistry program at CRL has been focused to generate quantitative water-radiolysis data in a

  18. Absolute fission yields in the fast neutron induced fission of sup 2 sup 3 sup 3 U by track etch combined with gamma-ray spectrometry

    CERN Document Server

    Ramaswami, A; Kalsi, P C; Dange, S P

    2003-01-01

    The absolute fission yields of twenty seven fission products were determined in the fast neutron induced fission of sup 2 '3 sup 3 U, employing track etch in combination with gamma-ray spectrometry. The total number of fissions was measured by registering the fission tracks on a small strip of lexan, a solid state track detector. The fission products were analysed by gamma-ray spectrometry. The measured yield values were compared to the ENDF/B-VI compilation and show a good agreement. (author)

  19. Use of D-T-produced fast neutrons for in vivo body composition analysis: a reference method for nutritional assessment in the elderly

    Energy Technology Data Exchange (ETDEWEB)

    Kehayias, J.J. [USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington St., Boston, 02111-1524 MA (United States)

    2004-05-01

    Body composition has become the main outcome of many nutritional intervention studies including osteoporosis, malnutrition, obesity, AIDS, and aging. Traditional indirect body composition methods developed with healthy young adults do not apply to the elderly or diseased. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used to assess in vivo elements characteristic of specific body compartments. Non-bone phosphorus for muscle is measured by the {sup 31}P(n,{alpha}){sup 28}Al reaction, and nitrogen for protein via the {sup 14}N(n,2n){sup 13}N fast neutron reaction. Inelastic neutron scattering is used to measure total body carbon and oxygen. Body fat is derived from carbon after correcting for contributions from protein, bone, and glycogen. Carbon-to-oxygen ratio (C/O) is used to measure the distribution of fat and lean tissue in the body and to monitor small changes of lean mass. A sealed, D-T neutron generator is used for the production of fast neutrons. Carbon and oxygen mass and their ratio are measured in vivo at a radiation exposure of less than 0.06 mSv. Gamma-ray spectra are collected using large BGO detectors and analyzed for the 4.43 MeV state of carbon and 6.13 MeV state of oxygen, simultaneously with the irradiation. P and N analysis by delayed fast neutron activation is performed by transferring the patient to a shielded room equipped with an array of NaI(Tl) detectors. A combination of measurements makes possible the assessment of the ''quality'' of fat-free mass. The neutron generator system is used to evaluate the efficacy of new treatments, to study mechanisms of lean tissue depletion with aging, and to investigate methods for preserving function and quality of life in the elderly. It is also used as a reference method for the validation of portable instruments of nutritional assessment. (orig.)

  20. Modeling the radiolysis of supercritical water by fast neutrons: density dependence of the yields of primary species at 400°c.

    Science.gov (United States)

    Butarbutar, Sofia Loren; Meesungnoen, Jintana; Guzonas, David A; Stuart, Craig R; Jay-Gerin, Jean-Paul

    2014-12-01

    A reliable understanding of radiolysis processes in supercritical water (SCW)-cooled reactors is crucial to developing chemistry control strategies that minimize the corrosion and degradation of materials. However, directly measuring the chemistry in reactor cores is difficult due to the extreme conditions of high temperature and pressure and mixed neutron and gamma-radiation fields, which are incompatible with normal chemical instrumentation. Thus, chemical models and computer simulations are an important route of investigation for predicting the detailed radiation chemistry of the coolant in a SCW reactor and the consequences for materials. Surprisingly, information on the fast neutron radiolysis of water at high temperatures is limited, and even more so for fast neutron irradiation of SCW. In this work, Monte Carlo simulations were used to predict the G values for the primary species e(-)aq, H(•), H2, (•)OH and H2O2 formed from the radiolysis of pure, deaerated SCW (H2O) by 2 MeV monoenergetic neutrons at 400°C as a function of water density in the range of ∼0.15-0.6 g/cm(3). The 2 MeV neutron was taken as representative of a fast neutron flux in a reactor. For light water, the moderation of these neutrons after knock-on collisions with water molecules generated mostly recoil protons of 1.264, 0.465, 0.171 and 0.063 MeV. Neglecting oxygen ion recoils and assuming that the most significant contribution to the radiolysis came from these first four recoil protons, the fast neutron yields were estimated as the sum of the G values for these protons after appropriate weightings were applied according to their energy. Calculated yields were compared with available experimental data and with data obtained for low-LET radiation. Most interestingly, the reaction of H(•) atoms with water was found to play a critical role in the formation yields of H2 and (•)OH at 400°C. Recent work has underscored the potential importance of this reaction above 200°C, but its

  1. Fast-Neutron Tomography using a Mobile Neutron Generator for Assessment of Steam-Water Distributions in Two-Phase Flows

    OpenAIRE

    Andersson, Peter

    2014-01-01

    This thesis describes the measurement technique of fast-neutron tomography for assessing spatial distributions of steam and water in two-phase flows. This so-called void distribution is of importance both for safe operation and for efficient use of the fuel in light water reactors, which compose the majority of the world’s commercial nuclear reactors. The technique is aimed for usage at thermal-hydraulic test loops, where heated two-phase flows are being investigated under reactor-relevant co...

  2. In-Pile Experiment of a New Hafnium Aluminide Composite Material to Enable Fast Neutron Testing in the Advanced Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Donna Post Guillen; Douglas L. Porter; James R. Parry; Heng Ban

    2010-06-01

    A new hafnium aluminide composite material is being developed as a key component in a Boosted Fast Flux Loop (BFFL) system designed to provide fast neutron flux test capability in the Advanced Test Reactor. An absorber block comprised of hafnium aluminide (Al3Hf) particles (~23% by volume) dispersed in an aluminum matrix can absorb thermal neutrons and transfer heat from the experiment to pressurized water cooling channels. However, the thermophysical properties, such as thermal conductivity, of this material and the effect of irradiation are not known. This paper describes the design of an in-pile experiment to obtain such data to enable design and optimization of the BFFL neutron filter.

  3. Antenna Parts and Waveguide Transmission Line of Short Pulse Radar System Design

    Directory of Open Access Journals (Sweden)

    M. E. Golubcov

    2014-01-01

    Full Text Available The main point of this research was работы являлось to create a stand to explore the application of short pulse radio signals in radar. The stand consists of antenna and waveguide elements. Each element out to guarantee operation in X-band with 10 percent working bank and 5 percent instantaneous bandwidth and the power output gotta be 1.5 kW. The form of the antenna beam patten need to be similar to cosecant pattern Side-lobe level need to be less than -25 dB. Background level got to be at least -30 dB. Wave friction, which is radiated from the antenna aperture, got to simultaneous formed in a space.As the most easily realizing variant of such antenna cutting parabolic mirror antenna with offset irradiator was chosen. The irradiator phase centre is shifted from the focal point of the paraboloid to form a cosecant pattern. Method of physical optics is used for the analysis of antennas. Calculating pattern of horn irradiator and mirror antenna which were met the requirements was received. The construction choice was limited by the preproduction possibilities, mass and dimensions. Mirror antenna consists of skeleton framing with mirroring elements which are fixing on it. Mirroring plane is multiplex and consists off rectangular planes made by hydroforming method. Antenna was tested and adjusted at the antenna darkroom after fabricating. The results were meted requirements.Besides the mirror antenna and the horn antenna waveguide elements, waveguide bends and rotating joints were calculated, manufactured and researched. All calculations included the manufacturers tolerances, technological corner R etc. As the construction base of rotating joint coaxial waveguide was chosen. The decision on the one hand: let keep the axial symmetry of excited wave at rotating part of the waveguide, on the other hand there’s no necessary to apply resonant rings, which are plug into dielectric beads for the transition from rotating ring part to

  4. A 13.56-mbps pulse delay modulation based transceiver for simultaneous near-field data and power transmission.

    Science.gov (United States)

    Kiani, Mehdi; Ghovanloo, Maysam

    2015-02-01

    A fully-integrated near-field wireless transceiver has been presented for simultaneous data and power transmission across inductive links, which operates based on pulse delay modulation (PDM) technique. PDM is a low-power carrier-less modulation scheme that offers wide bandwidth along with robustness against strong power carrier interference, which makes it suitable for implantable neuroprosthetic devices, such as retinal implants. To transmit each bit, a pattern of narrow pulses are generated at the same frequency of the power carrier across the transmitter (Tx) data coil with specific time delays to initiate decaying ringing across the tuned receiver (Rx) data coil. This ringing shifts the zero-crossing times of the undesired power carrier interference on the Rx data coil, resulting in a phase shift between the signals across Rx power and data coils, from which the data bit stream can be recovered. A PDM transceiver prototype was fabricated in a 0.35- μm standard CMOS process, occupying 1.6 mm(2). The transceiver achieved a measured 13.56 Mbps data rate with a raw bit error rate (BER) of 4.3×10(-7) at 10 mm distance between figure-8 data coils, despite a signal-to-interference ratio (SIR) of -18.5 dB across the Rx data coil. At the same time, a class-D power amplifier, operating at 13.56 MHz, delivered 42 mW of regulated power across a separate pair of high-Q power coils, aligned with the data coils. The PDM data Tx and Rx power consumptions were 960 pJ/bit and 162 pJ/bit, respectively, at 1.8 V supply voltage.

  5. Improved fission neutron energy discrimination with 4He detectors through pulse filtering

    Science.gov (United States)

    Zhu, Ting; Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit; Chandra, Rico; Kiff, Scott; Chung, Heejun; Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A.

    2017-03-01

    This paper presents experimental and computational techniques implemented for 4He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since 4He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the 4He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with 252Cf spontaneous fission neutrons. Given the 4He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a 4He fast neutron detection system.

  6. Single-channel 1.92 Tbit/s, Pol-Mux-64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 7.5 bit/s/Hz.

    Science.gov (United States)

    Otuya, David Odeke; Kasai, Keisuke; Yoshida, Masato; Hirooka, Toshihiko; Nakazawa, Masataka

    2014-10-01

    Coherent Nyquist pulses have been used for optical time division multiplexed (OTDM) digital coherent transmission, and a single-channel 1.92 Tbit/s, Pol-Mux-64 QAM coherent Nyquist pulse transmission over 150 km is demonstrated. The ability to considerably reduce the spectral bandwidth of the data signal enabled us to increase the spectral efficiency from 3.2 bit/s/Hz to 7.5 bit/s/Hz when using a Gaussian pulse train.

  7. Effects of pressure-dependent segmental arterial compliance and postural changes on pulse wave transmission in an arterial model of the human upper limb.

    Science.gov (United States)

    Xu, Ke; Butlin, Mark; Avolio, Alberto P

    2011-01-01

    With increasing interest in the effect of postural changes on arterial blood pressure and vascular properties, it is important to understand effects of pressure-dependent arterial compliance. This study investigates effects of pressure-dependent compliance on pulse wave velocity (PWVar), pressure wave shape, and transmission characteristics in an arterial model of the human arm from heart to radial artery from supine to standing. Estimated central pressure waveform was used as the input for the model, calculated using a validated transfer function (SphygmoCor, AtCor Medical) from recorded radial pulses in 10 healthy male subjects (53.8 ± 7.9 years) during 0, 30, 60 and 90 degree head-up tilt. A 5-segment linear model was optimized using estimated central and recorded radial arterial pulse; each segment represented by an equivalent inductance, resistance and capacitance (compliance (C)) Pressure-dependent compliance (C(P)=a · e(b · P) was added to develop a nonlinear model, and the radial pulse calculated. Comparison of the radial pulse calculated by the linear and nonlinear models showed no statistical difference in systolic, diastolic, mean, and pulse pressure in any position of tilt. However, waveform shape was increasingly divergent at higher angles of tilt (RMS error 2.3 ± 1.2 mmHg supine, 6.5 ± 3.0 mmHg standing) as was PWVar (0% increase from supine to standing in the linear model, 16.7% increase in nonlinear model). Fourier analysis demonstrated peak amplitude of transmission being at higher frequencies and phase delay being lower in the nonlinear model relative to the linear model. Pressure-dependent arterial compliance, whilst having no effect on peak values of pressure, has significant effects on waveform shape and transmission speed, especially with a more upright position.

  8. Fast neutron spectrum unfolding of a TRIGA Mark II reactor and measurement of spectrum-averaged cross sections. Integral tests of differential cross sections of neutron threshold reactions

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M.S.; Hossain, S.M.; Khan, R. [Atomic Energy Research Establishment, Dhaka (Bangladesh). Inst. of Nuclear Science and Technology (INST); Sudar, S. [Debrecen Univ. (Hungary). Inst. of Experimental Physics; Zulquarnain, M.A. [Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Qaim, S.M. [Forschungszentrum Juelich (Germany). Inst. fuer Neurowissenschaften und Medizin (INM-5)

    2013-07-01

    The spectrum of fast neutrons having energies from 0.5 to 20 MeV in the core of the 3MW TRIGA Mark II reactor at Savar, Dhaka, Bangladesh, was unfolded by activating several metal foils to induce threshold nuclear reactions covering the whole spectrum, and then doing necessary iterative calculations utilizing the activation results and the code SULSA. The analysed shape of the spectrum in the TRIGA core was found to be similar to that of the pure {sup 235}U-fission spectrum, except for the energies between 0.5 and 1.5 MeV, where it was slightly higher than the fission spectrum. Spectrum-averaged cross sections were determined by integral measurements. The integral values measured in this work were compared with the recommended values for a pure fission spectrum as well as with the integrated data deduced from measured and evaluated excitation functions of a few reactions given in some data files. The good agreement between integral measurements and integrated data in case of well-investigated reactions shows that the fast neutron field at the TRIGA Mark II reactor can be used for validation of evaluated data of neutron threshold reactions. (orig.)

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

    CERN Document Server

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

    2015-01-01

    In a previous work we have demonstrated the feasibility of high-frame-rate, fast-neutron radiography of generic air-water two-phase flows in a 1.5 cm thick, rectangular flow channel. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany, using an multi-frame, time-resolved detector developed for fast neutron resonance radiography. The results were however not fully optimal and therefore we have decided to modify the detector and optimize it for the given application, which is described in the present work. Furthermore, we managed to improve the image post-processing methodology and the noise suppression. Using the tailored detector and the improved post-processing significant increase in the image quality and an order of magnitude lower exposure times, down to 3.33 ms, have been achieved with minimized motion artifacts. Similar to the previous study, different two-phase flow regimes such as bubbly slug and churn flows have been e...

  10. Are high energy proton beams ideal for AB-BNCT? A brief discussion from the viewpoint of fast neutron contamination control.

    Science.gov (United States)

    Lee, Pei-Yi; Liu, Yuan-Hao; Jiang, Shiang-Huei

    2014-06-01

    High energy proton beam (>8MeV) is favorable for producing neutrons with high yield. However, the produced neutrons are of high energies. These high energy neutrons can cause severe fast neutron contamination and degrade the BNCT treatment quality if they are not appropriately moderated. Hence, this study aims to briefly discuss the issue, from the viewpoint of fast neutron contamination control, whether high energy proton beam is ideal for AB-BNCT or not. In this study, D2O, PbF4, CaF2, and Fluental(™) were used standalone as moderator materials to slow down 1-, 6-, and 10-MeV parallelly incident neutrons. From the calculated results, we concluded that neutrons produced by high energy proton beam could not be easily moderated by a single moderator to an acceptable contamination level and still with reasonable epithermal neutron beam intensity. Hence, much more complicated and sophisticated designs of beam shaping assembly have to be developed when using high energy proton beams.

  11. A facility for fast-neutron irradiations at Jyväskylä and its use for nuclide cross-section measurements in fission

    Science.gov (United States)

    Lhersonneau, G.; Malkiewicz, T.; Jones, P.; Karvonen, P.; Ketelhut, S.; Bajeat, O.; Fadil, M.; Gaudu, S.; Saint-Laurent, M. G.; Trzaska, W. H.

    2013-01-01

    An efficient and reliable transport system for fast-neutron irradiations has been built at the Physics Department, Jyväskylä, Finland. It is constructed from commercial bicycle components and is driven by a computer-controlled stepping motor. It can be operated in single or cyclic mode. The neutron irradiated targets are moved within 1.2 s (full stop to full stop) to a well-shielded position 3 m away where they can be removed or directly investigated by γ spectroscopy. The system has been built with the aim to experimentally verify the calculated production rates of neutron-rich nuclei in the SPIRAL2 uranium target. However, the facility can be used for various kinds of fast-neutron irradiations, with a neutron spectrum up to 60 MeV produced by stopping a deuteron beam of several μA in a thick target. Examples of applications are activation and integral cross-section measurements, evaluation of damages in materials and biological cells.

  12. Enhancement of critical current density in fast neutron irradiated melt-textured YBa[sub 2]Cu[sub 3]O[sub 7-x

    Energy Technology Data Exchange (ETDEWEB)

    Puzniak, R.; Wisniewski, A.; Baran, M.; Szymczak, H. (Polska Akademia Nauk, Warsaw (Poland). Inst. Fizyki); Zhang Pingxiang; Wang Jingrong; Zhou Lian (Northwest Inst. for Nonferrous Metal Research, Baoji, SN (China)); Pytel, K.; Pytel, B. (Institute of Atomic Energy, Otwock-Swierk (Poland))

    1993-01-01

    The critical current density in melt-textured samples of YBa[sub 2]Cu[sub 3]O[sub 7]-x obtained by the powder melting process was determined from magnetization measurements. A linear dependence between the width of the hysteresis loop and sample size was observed for both unirradiated and irradiated samples. This indicates that the critical current is circulating through the whole sample and is not disconnected by weak links, even when a magnetic field is applied in the irradiated sample. After fast neutron irradiation with fluences form 5 x 10[sup 16] to 6 x 10[sup 17] n cm[sup -2] (E > 0.5 MeV), significant enhancement of the critical current density, j[sub c], was observed. Critical current density, determined from magnetization measurements, for magnetic field perpendicular to the a-b plane j[sub c][sup ab], reaches [approx] 10[sup 5] A cm[sup -2] at 77 K in 1 T. For H parallel to the a-b plane, j[sub c][sup c] along the c-axis reaches 5 x 10[sup 3] A cm[sup -2]. An increase in the anisotropy of the critical current was observed after fast neutron irradiation in the temperature range 60-80 K. (Author).

  13. Fast neutron tolerance of the perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions with junction diameters between 46 and 64 nm

    Science.gov (United States)

    Narita, Yuzuru; Takahashi, Yutaka; Harada, Masahide; Oikawa, Kenichi; Kobayashi, Daisuke; Hirose, Kazuyuki; Sato, Hideo; Ikeda, Shoji; Endoh, Tetsuo; Ohno, Hideo

    2017-08-01

    This work represents the first-ever investigation of the effects of fast neutron exposure on the perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions (p-MTJs) with practical junction diameters (D) between 46 and 64 nm. In this study, 461 p-MTJs, each with a tunnel magnetoresistance (TMR) ratio above 90%, were irradiated with fast neutrons at a total 1 MeV equivalent fluence of 3.79 × 1012 cm-2, corresponding to 1.90 × 1011 h irradiation with fast atmospheric neutrons (20 cm-2 h-1), without applying a bias voltage. Following irradiation, there were no changes in the properties of these devices, such as their resistance versus magnetic field curves, resistance values in the parallel and anti-parallel states, or TMR ratios, regardless of the neutron fluence. On the basis of these data, the nuclear reactions that occur under the specific experimental neutron irradiation conditions employed in this work are discussed.

  14. Effect of pre-exposure to beta rays of tritium on some biochemical parameters measured in organs of rats subsequently irradiated with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Petcu, I.; Moisoi, N.; Savu, D.; Constantinescu, B. [Dept. of Health and Environmental Physics, Horia Hulubei Inst. of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

    2002-07-01

    The experiment examined biological responses produced by combined sequential exposure to low-level tritium contamination, followed by challenging irradiation with fast neutrons. Modifications of endogenous antioxidant potential of different organs in rats were discussed in relation to tissue radiosensitivity. Rats pre-contaminated to 7 cGy and 35 cGy have been additionally irradiated to 1 Gy with fast neutrons. Lipid peroxide level was determined in liver, kidney, small intestine, spleen, bone marrow, and plasma. Reduced glutathione (GSH) level and glucose-6-phosphate dehydrogenase (G6PDH) activity were determined in erythrocytes. An in vitro thymidine uptake assay was performed in isolated bone marrow cells. The lipid peroxide level decreased significantly only in liver and kidney from rats pre-exposed to 35 cGy. For small intestine and spleen, tissues of comparatively higher radiosensitivity, no induced radioprotection was observed, as reflected in the homeostasis of the lipid peroxides. The same behavior was observed in bone marrow, the most radiosensitive tissue studied. However, the bone marrow thymidine-incorporation assay revealed a possible adaptive-type reaction in rats pre-exposed to 35 cGy. We conclude that for radiosensitive tissues pre-exposure to chronic low doses of low linear energy transfer (LET) irradiation has no protective effect on their antioxidant status, whereas a protective effect is observed in radioresistent tissues. (author)

  15. Determination of the fast neutrons spectra by the Elastic scattering method (n, p); Determinacion del espectro de neutrones rapidos por el metodo de la dispersion elastica (n, p)

    Energy Technology Data Exchange (ETDEWEB)

    Elizalde D, J

    1973-07-01

    This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spectra it is obtained the falling on neutron spectra over the film. (Author)

  16. Localized fast neutron flux enhancement for damage experiments in a research reactor; Accroissement local du flux rapide pour des experiences de dommages dans un reacteur de recherche

    Energy Technology Data Exchange (ETDEWEB)

    Malouch, F

    2003-06-01

    In irradiation experiments on materials in the core of the Osiris reactor (CEA-Saclay) we seek to increase damage in irradiated samples and to reduce the duration of their stay in the core. Damage is essentially caused by fast neutrons (E {>=} 1 MeV); we have therefore pursued the possibility of a localized increase of their level in an irradiation experiment by using a flux converter device made up of fissile material arranged according to a suitable geometry that allows the converter to receive experiments. We have studied several parameters that are influential in the increase of fast neutron flux within the converter. We have also considered the problem of the converter's cooling in the core and its effect on the operation of the reactor. We have carried out a specific neutron calculation scheme based on the modular 2D-transport code APOLLO2 using a two-level transport method. Experimental validation of the flux calculation scheme was carried out in the ISIS reactor, the mock-up of OSIRIS, by optimizing the loading of fuel elements in the core. The experimental results show that the neutron calculation scheme computes the fluxes in close agreement with the measurements especially the fast flux. This study allows us to master the essential physical parameters needed for the design of a flux converter in an MTR reactor. (author)

  17. Paving the Road for Modern Particle Therapy – What can we Learn from the experience gained with Fast Neutron Therapy in Munich?

    Directory of Open Access Journals (Sweden)

    Hanno Martin Specht

    2015-11-01

    Full Text Available While neutron therapy was a highly topical subject in the 70’s and 80’s, today there are only a few remaining facilities offering fast neutron therapy. Nevertheless, up to today more than 30,000 patients were treated with neutron therapy. For some indications like salivary gland tumors and malignant melanoma there is clinical evidence that the addition of Fast Neutron Therapy (FNT leads to superior local control compared to photon treatment alone. FNT was available in Munich from 1985 until 2000 at the RENT facility (Reactor Neutron Therapy. Patient treatment continued at the new research reactor FRM II in 2007 under improved treatment conditions and today it can still be offered to selected patients as an individual treatment option. As there is a growing interest in high-linear energy transfer (LET therapy with new hadron therapy centers emerging around the globe, the clinical data generated by neutron therapy might help to develop biologically driven treatment planning algorithms. Also FNT might experience its resurgence as a combinational partner of modern immunotherapies.

  18. Temporal characterization of short-pulse third-harmonic generation in an atomic gas by a transmission-grating Michelson interferometer.

    Science.gov (United States)

    Papadogiannis, N A; Nersisyan, G; Goulielmakis, E; Rakitzis, T P; Hertz, E; Charalambidis, D; Tsakiris, G D; Witte, K

    2002-09-01

    By use of a transmission-grating-based Michelson interferometer, second-order interferometric as well as intensity autocorrelation traces of the third harmonic of a Ti:sapphire 50-fs laser beam produced in Ar have been measured. The duration of the harmonic is found to be that expected from lowest-order perturbation theory. At this wavelength, the performance of the interferometer with respect to pulse-front distortion and dispersion is found to be satisfactory. This result is a first step toward the use of the interferometer for the temporal characterization of higher harmonics or harmonic superposition forming attosecond pulse trains.

  19. Neutron Transmission through Sapphire Crystals: Experiments and Simulations

    OpenAIRE

    Rantsiou, Emmanouela; Filges, Uwe; Panzner, Tobias; Klinkby, Esben Bryndt

    2013-01-01

    Sapphire crystals are excellent filters of fast neutrons, while at the same time exhibit moderate to very little absorption at smaller energies. We have performed an extensive series of measurements in order to quantify the above effect. Alongside our experiments, we have performed a series of simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Thosesimulations were part of the effort of validating and improving the newly developed interface between...

  20. Simplified flexible-PON upstream transmission using pulse position modulation at ONU and DSP-enabled soft-combining at OLT for adaptive link budgets.

    Science.gov (United States)

    Liu, Xiang; Effenberger, Frank; Chand, Naresh

    2015-03-09

    We demonstrate a flexible modulation and detection scheme for upstream transmission in passive optical networks using pulse position modulation at optical network unit, facilitating burst-mode detection with automatic decision threshold tracking, and DSP-enabled soft-combining at optical line terminal. Adaptive receiver sensitivities of -33.1 dBm, -36.6 dBm and -38.3 dBm at a bit error ratio of 10(-4) are respectively achieved for 2.5 Gb/s, 1.25 Gb/s and 625 Mb/s after transmission over a 20-km standard single-mode fiber without any optical amplification.

  1. Mathematical Constraints on the Use of Transmission Line Models for Simulating Initial Breakdown Pulses in Lightning Discharges

    Science.gov (United States)

    da Silva, C. L.; Merrill, R. A.; Pasko, V. P.

    2015-12-01

    A significant portion of the in-cloud lightning development is observed as a series of initial breakdown pulses (IBPs) that are characterized by an abrupt change in the electric field at a remote sensor. Recent experimental and theoretical studies have attributed this process to the stepwise elongation of an initial lightning leader inside the thunderstorm [da Silva and Pasko, JGR, 120, 4989-5009, 2015, and references therein]. Attempts to visually observe these events are hampered due to the fact that clouds are opaque to optical radiation. Due to this reason, throughout the last decade, a number of researchers have used the so-called transmission line models (also commonly referred to as engineering models), widely employed for return stroke simulations, to simulate the waveshapes of IBPs, and also of narrow bipolar events. The transmission line (TL) model approach is to prescribe the source current dynamics in a certain manner to match the measured E-field change waveform, with the purpose of retrieving key information about the source, such as its height, peak current, size, speed of charge motion, etc. Although the TL matching method is not necessarily physics-driven, the estimated source characteristics can give insights on the dominant length- and time-scales, as well as, on the energetics of the source. This contributes to better understanding of the environment where the onset and early stages of lightning development takes place.In the present work, we use numerical modeling to constrain the number of source parameters that can be confidently inferred from the observed far-field IBP waveforms. We compare different modified TL models (i.e., with different attenuation behaviors) to show that they tend to produce similar waveforms in conditions where the channel is short. We also demonstrate that it is impossible to simultaneously retrieve the speed of source current propagation and channel length from an observed IBP waveform, in contrast to what has been

  2. Performance Analysis of High-speed Optical Pulse Transmission in Dispersion-managed Nonlinear Birefringent Fiber Using Quantum Well Laser Diode Sources

    Institute of Scientific and Technical Information of China (English)

    YAN Minhui; CHEN Jianping

    2002-01-01

    This paper analyzes the high bit-rate optical pulse trasmission in single mode optical fiber with chromatic dispersion, polarization mode dispersion (small random birefringence) and nonlinearity. Numerical method employed can precisely describe their interactive effect on transmission performance. Different dispersion maps and the related performance are analysed. Various simulation results and discussion are given. The results show that chromatic dispersion compensation should be carefully designed. Appropriate dispersion management can also alleviate the effect of polarization mode dispersion.

  3. Transmission Properties of a New Glass Ceramic and Doped with Co2+ as Saturable Absorber for 1.54 μm Er Glass Short Pulse Laser

    Institute of Scientific and Technical Information of China (English)

    YU Chunlei; CHEN Li; FENG Suya; HE Dongbing; WANG Meng; HU Lili

    2012-01-01

    The preparation and characteristics of a new transparent glass ceramic were described.Crystal phase particles with nanometer size were successfully precipitated in glass matrix,which was confirmed to be one of indium aluminum zinc oxide compounds (InxAlyZnzO).The presence of aluminum (Al) and indium (In) impurities in the zinc oxides (ZnO) crystal lattice leads to some changes of the carrier concentration in the material and then promote the sharply changes of transmission spectra in IR range wavelength.And subsequently,the IR cut-off edge blue shifted from 5.5 μm in base glass to 3 μm in transparent glass ceramic sample.Furthermore,passive Q switched 1.54 μm Er glass laser pulses with pulse energy of 10 mJ and pulse width of 800 ns were successfully obtained by using the cobalt doped transparent glass ceramic as a saturable absorber.

  4. The n,{gamma} discrimination in recoil-proton proportional counters. Application to the measurement of fast neutron spectra; Discrimination n,{gamma} dans les compteurs proportionnels a protons de recul. Application a la mesure des spectres de neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

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

    1969-07-01

    A description is given of a spectrometry chain working in the energy range of a few keV to 1 MeV, and designed for measurement of fast neutron spectra. It consists of detectors, recoil proton proportional counters built especially for this work by R. COMTE (DEG/SER) and which make it possible to cover the energy range and also associated electronic equipment. A brief description is first given of the physical processes involved: (n,p) collisions in the gas, influence of {gamma} radiation; the method of discrimination is then presented. It is based on the difference in the rise-times of the pulses. In the experiments described here the use of a bi-parametric system made it possible to employ the most simple discrimination device, based on the fact that the high frequency gamma pulse components are, at a given energy, weaker than those of the neutron pulses. Results are given of measurements carried out on the Van der Graaff (mono-energetic neutrons for testing the linearity of the chain and the resolving power of the counters), and of those made in a sub-critical system Hug at Cadarache. (author) [French] On decrit une chaine de spectrometrie travaillant dans le domaine d'energie de quelques keV a 1 MeV destinee a la mesure des spectres de neutrons rapides. Elle comprend les detecteurs, compteurs proportionnels a protons de recul, realises specialement pour cette etude par M. R. COMTE (DEG/SER), permettant de couvrir la gamme d'energie et l'electronique associee. Apres un rappel des processus physiques mis en jeu: chocs (n,p) dans les gaz, influence des rayonnements {gamma}, on expose la methode de discrimination utilisee. Celle-ci est basee sur la difference des temps de montee des impulsions. Au cours des experiences rapportees ici, la mise en oeuvre d'un ensemble bi-parametrique a permis d'utiliser le dispositif de discrimination le plus simple, base sur la remarque que les composantes a haute frequence des impulsions {gamma} sont, a

  5. Preliminary studies leading to a conceptual design of a 1000 MWe fast neutron reactor; Etudes preliminaires conduisant a un concept de reacteur a neutrons rapides de 1000 MWe

    Energy Technology Data Exchange (ETDEWEB)

    Vendryes, G.; Zaleski, C.P. [Association Euratom-CEA Cadarache (France). Centre d' Etudes Nucleaires

    1964-07-01

    This report presents the results of studies which seemed important to undertake in connexion with the development of fast neutron reactors. - It points out the advantage of high internal breeding ratios ({approx}1, 1) which are necessary in order to get a small change in time both in power distribution and reactivity (less: than 0.005 {delta}k/k in 18 months). - It shows how to achieve this goal, when simultaneously power distribution flattening is obtained. These results in a higher mean specific power (which is an economic gain) and therefore in a smaller doubling time (about 10 years). - It attempts to find criteria concerning the specific power that should be used in future reactor designs -It presents a conceptional design of a 1000 MWe fast neutron reactor, for the realisation of which no technological impossibility appears. - It shows that the dynamic behaviour seems satisfactory despite a positive total isothermal sodium coefficient. - It tries to predict the development of fast reactors within the future total nuclear program. It does not appear that fissile materials supply problems should in France slow down the development of fast neutron reactors, which will be essentially tied up to its economical ability to produce cheap electric power. (authors) [French] Ce rapport presente les etudes qu'il nous a paru important d'aborder dans le cadre du developpement des reacteurs a neutrons rapides. - Il met en evidence l'interet des taux de regeneration internes eleves ({approx}1, 1) pour obtenir une bonne evolution dans le temps de la distribution de puissance et de la reactivite (moins de 0,005 {delta}k/k pour 18 mois). - Il montre la possibilite d'y parvenir tout en applatissant la distribution des fissions, ce qui se traduit par une puissance specifique moyenne plus elevee (gain economique), et donc un temps de doublement plus faible de l'ordte de 10 ans - Il tente de definir un optimum de la puissance specifique valable pour les

  6. Uncertainty study of nuclear model parameters for the n+ ^{56}Fe reactions in the fast neutron region below 20 MeV

    CERN Document Server

    Duan, Junfeng; Sjöstrand, Henrik; Alhassan, Erwin; Gustavsson, Cecilia; Österlund, Michael; Koning, Arjan; Rochman, Dimitri

    2013-01-01

    In this work, we study the uncertainty of nuclear model parameters for neutron induced ^{56}Fe reactions in fast neutron region by using the Total Monte Carlo method. We perform a large number of TALYS runs and compare the calculated results with the experimental data of the cross sections to obtain the uncertainties of the model parameters. Based on the derived uncertainties another 1000 TALYS runs have been performed to create random cross section files. For comparison with the experimental data we calculate a weighted \\chi^2 value for each random file as well as the ENDF/B-VII.1, JEFF3.1, JENDL4.0 and CENDL3.1 data libraries. Furthermore, we investigate the optical model parameters correlation obtained by way of this procedure.

  7. Radiobiological aspects of high altitude flight: relative biological effectiveness of fast neutrons in suppressing immune capacity to an infective agent. [Mice

    Energy Technology Data Exchange (ETDEWEB)

    Friedberg, W.; Neas, B.R.; Faulkner, D.N.; Hanneman, G.D.; Darden, E.B. Jr.

    1978-02-01

    The authors investigated the relative biological effectiveness (RBE) of fast neutrons compared with x rays in impeding development of immunity to an infective agent, the intestinal cestode Hymenolepis nana. Mice were irradiated with neutrons or x rays and 2 days later given an immunizing dose of H. nana eggs. After another 2 days, the mice received a challenge dose of the eggs. Challenge egg doses were also given to sham-irradiated unimmunized and immunized controls. All mice were killed 90 to 92 hours after challenge, and the H. nana larvae (cysticercoids) that developed in the intestinal tissue were counted. An increased cysticercoid count in the irradiated mice, as compared with the count in unirradiated immunized controls, reflects suppression of immune capacity by the radiation. The results indicate a neutron RBE of 4 at 50 and 101 rad.

  8. Calculations of the thermal and fast neutron fluxes in the Syrian miniature neutron source reactor using the MCNP-4C code.

    Science.gov (United States)

    Khattab, K; Sulieman, I

    2009-04-01

    The MCNP-4C code, based on the probabilistic approach, was used to model the 3D configuration of the core of the Syrian miniature neutron source reactor (MNSR). The continuous energy neutron cross sections from the ENDF/B-VI library were used to calculate the thermal and fast neutron fluxes in the inner and outer irradiation sites of MNSR. The thermal fluxes in the MNSR inner irradiation sites were also measured experimentally by the multiple foil activation method ((197)Au (n, gamma) (198)Au and (59)Co (n, gamma) (60)Co). The foils were irradiated simultaneously in each of the five MNSR inner irradiation sites to measure the thermal neutron flux and the epithermal index in each site. The calculated and measured results agree well.

  9. Measurement and calculation of the fast-neutron and photon spectra from the core boundary to the biological shielding in the WWER-1000 reactor model.

    Science.gov (United States)

    Osmera, B; Cvachovec, F; Kyncl, J; Smutný, V

    2005-01-01

    The fast-neutron and photon space-energy distributions have been measured in an axially (1.25 m active height) and azimuthally (60 degree symmetry sector) shortened model of the WWER-1000 reactor assembled in the LR-0 experimental reactor. The space-energy distributions have been calculated with the stochastic code MCNP and the deterministic three-dimensional code TORT. Selected results are presented and discussed in the paper. This work has been done in the frame of the EU 5th FW project REDOS REDOS, Reactor Dosimetry: Accurate determination and benchmarking of radiation field parameters, relevant for reactor pressure vessel monitoring. EURATOM Programme, Call 2000/C 294/04). All geometry and material composition data of the model as well as the available experimental data were carefully checked and revised.

  10. Fast Neutron Transport in the Biological Shielding Model and Other Regions of the VVER-1000 Mock-Up on the LR-0 Research Reactor

    Science.gov (United States)

    Košťál, Michal; Milčák, Ján; Cvachovec, František; Jánský, Bohumil; Rypar, Vojtěch; Juříček, Vlastimil; Novák, Evžen; Egorov, Alexander; Zaritskiy, Sergey

    2016-02-01

    A set of benchmark experiments was carried out in the full scale VVER-1000 mock-up on the reactor LR-0 in order to validate neutron transport calculation methodologies and to perform the optimization of the shape and locations of neutron flux operation monitors channels inside the shielding of the new VVER-1000 type reactors. Compared with previous experiments on the VVER-1000 mock-up on the reactor LR-0, the fast neutron spectra were measured in the extended neutron energy interval (0.1-10 MeV) and new calculations were carried out with the MCNPX code using various nuclear data libraries (ENDF/B VII.0, JEFF 3.1, JENDL 3.3, JENDL 4, ROSFOND 2009, and CENDL 3.1). Measurements and calculations were carried out at different points in the mock-up. The calculation and experimental data are compared.

  11. Fast Neutron Transport in the Biological Shielding Model and Other Regions of the VVER-1000 Mock-Up on the LR-0 Research Reactor

    Directory of Open Access Journals (Sweden)

    Košťál Michal

    2016-01-01

    Full Text Available A set of benchmark experiments was carried out in the full scale VVER-1000 mock-up on the reactor LR-0 in order to validate neutron transport calculation methodologies and to perform the optimization of the shape and locations of neutron flux operation monitors channels inside the shielding of the new VVER-1000 type reactors. Compared with previous experiments on the VVER-1000 mock-up on the reactor LR-0, the fast neutron spectra were measured in the extended neutron energy interval (0.1–10 MeV and new calculations were carried out with the MCNPX code using various nuclear data libraries (ENDF/B VII.0, JEFF 3.1, JENDL 3.3, JENDL 4, ROSFOND 2009, and CENDL 3.1. Measurements and calculations were carried out at different points in the mock-up. The calculation and experimental data are compared.

  12. 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.

  13. SiC-based neutron detector in quasi-realistic working conditions: efficiency and stability at room and high temperature under fast neutron irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Ferone, Raffaello; Issa, Fatima; Ottaviani, Laurent; Biondo, Stephane; Vervisch, Vanessa [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231,13397 Marseille Cedex 20, (France); Szalkai, Dora; Klix, Axel [KIT- Karlsruhe Institute of Technology, Institute of Neutron Physics and Reactor Technology Karlsruhe 76344, (Germany); Vermeeren, Ludo [SCK-CEN, Boeretang 200, B-2400 Mol, (Belgium); Saenger, Richard [Schlumberger, Clamart, (France); Lyoussi, Abadallah [CEA, DEN, Departement d' Etudes des Reacteurs, Service de Physique Experimentale, Laboratoire Dosimetrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance, (France)

    2015-07-01

    In the framework of the European I SMART project, we have designed and made new SiC-based nuclear radiation detectors able to operate in harsh environments and to detect both fast and thermal neutrons. In this paper, we report experimental results of fast neutron irradiation campaign at high temperature (106 deg. C) in quasi-realistic working conditions. Our device does not suffer from high temperature, and spectra do show strong stability, preserving features. These experiments, as well as others in progress, show the I SMART SiC-based device skills to operate in harsh environments, whereas other materials would strongly suffer from degradation. Work is still demanded to test our device at higher temperatures and to enhance efficiency in order to make our device fully exploitable from an industrial point of view. (authors)

  14. The perturbation of backscattered fast neutrons spectrum caused by the resonances of C, N and O for possible use in pyromaterial detection

    Science.gov (United States)

    Abedin, Ahmad Firdaus Zainal; Ibrahim, Noorddin; Zabidi, Noriza Ahmad; Abdullah, Abqari Luthfi Albert

    2015-04-01

    Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines.

  15. The perturbation of backscattered fast neutrons spectrum caused by the resonances of C, N and O for possible use in pyromaterial detection

    Energy Technology Data Exchange (ETDEWEB)

    Abedin, Ahmad Firdaus Zainal, E-mail: firdaus087@gmail.com; Ibrahim, Noorddin; Zabidi, Noriza Ahmad; Abdullah, Abqari Luthfi Albert [Department of Defence Science, Universiti Pertahanan Nasional Malaysia, Kem Sungai Besi, Kuala Lumpur 57000 (Malaysia)

    2015-04-29

    Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines.

  16. Microstructure changes during non-conventional heat treatment of thin Ni-Ti wires by pulsed electric current studied by transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Delville, R., E-mail: remi.delville@ua.ac.be [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Malard, B.; Pilch, J.; Sittner, P. [Institute of Physics, Na Slovance 2, 182 21 Praha (Czech Republic); Schryvers, D. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2010-08-15

    Transmission electron microscopy, electrical resistivity measurements and mechanical testing were employed to investigate the evolution of microstructure and functional superelastic properties of 0.1 mm diameter as-drawn Ni-Ti wires subjected to a non-conventional heat treatment by controlled electric pulse currents. This method enables a better control of the recovery and recrystallization processes taking place during the heat treatment and accordingly a better control on the final microstructure. Using a stepwise approach of millisecond pulse annealing, it is shown how the microstructure evolves from a severely deformed state with no functional properties to an optimal nanograined microstructure (20-50 nm) that is partially recovered through polygonization and partially recrystallized and that has the best functional properties. Such a microstructure is highly resistant against dislocation slip upon cycling, while microstructures annealed for longer times and showing mostly recrystallized grains were prone to dislocation slip, particularly as the grain size exceeds 200 nm.

  17. On Variant Strategies To Solve The Magnitude Least Squares Optimization Problem In Parallel Transmission Pulse Design And Under Strict SAR And Power Constraints

    CERN Document Server

    Hoyos-Iruarrizaga, Andres; Massire, Aurélien; Amadon, Alexis; Boulant, Nicolas

    2013-01-01

    Parallel transmission has been a very promising candidate technology to mitigate the inevitable radio-frequency field inhomogeneity in magnetic resonance imaging (MRI) at ultra-high field (UHF). For the first few years, pulse design utilizing this technique was expressed as a least squares problem with crude power regularizations aimed at controlling the specific absorption rate (SAR), hence the patient safety. This approach being suboptimal for many applications sensitive mostly to the magnitude of the spin excitation, and not its phase, the magnitude least squares (MLS) problem then was first formulated in 2007. Despite its importance and the availability of other powerful numerical optimization methods, this problem yet has been faced exclusively by the pulse designer with the so-called variable exchange method. In this paper, we investigate other strategies and incorporate directly the strict SAR and hardware constraints. Different schemes such as sequential quadratic programming (SQP), interior point (I-...

  18. The modified SRRS threshold criteria for high peak power laser pulses in long air-path transmission considering the near-field beam quality

    Science.gov (United States)

    Zhu, C. Y.; Lin, D. Y.; Lu, Z. W.; Wang, Y. X.; Wang, Z.; Liang, L. X.; Ba, D. X.

    2016-11-01

    This paper demonstrates that the stimulated rotational Raman scattering (SRRS) threshold for high peak power laser pulses propagating through a long air path can be influenced strongly by the near-field quality of the laser beams, and the relationship between the SRRS threshold and the near-field beam quality (i.e., spatial intensity modulation index and contrast ratio) can be evaluated quantitatively. By using our three-dimensional numerical model, which can describe the spatial-temporal evolution behaviors of SRRS and is verified by previously published SRRS experimental data, the criteria of the safe transmission distance for high peak power nanosecond laser pulses are obtained, and the modified SRRS threshold criterion formulas considering the near-field beam conditions are presented.

  19. Modified Approach for Harmonic Reduction in Transmission System Using 48-pulse UPFC Employing Series Zig-Zag Primary and Y-Y Secondary Transformer

    OpenAIRE

    Ragini Malviya; Rakesh Kumar Saxena

    2013-01-01

    In this paper THD (Total Harmonic Distortion) is analysed and compared by using UPFC in a multi-line transmission system of 500 KV having 5-buses in two different arrangements. The UPFC converters are arranged as a Diode Clamped multilevel Converter (DCMLC) that leads to the cost reduction as compared with other multi-level converters. The comparison has been done by both series zig-zag/2Y-2Δ and series zig-zag/4Y transformer configuration for 48-pulses GTO based diode clamped converter. The ...

  20. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses.

    Science.gov (United States)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-09-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals.

  1. Transmission of endemic ST22-MRSA-IV on four acute hospital wards investigated using a combination of spa, dru and pulsed-field gel electrophoresis typing.

    LENUS (Irish Health Repository)

    Creamer, E

    2012-11-01

    The transmission of meticillin-resistant Staphylococcus aureus (MRSA) between individual patients is difficult to track in institutions where MRSA is endemic. We investigated the transmission of MRSA where ST22-MRSA-IV is endemic on four wards using demographic data, patient and environmental screening, and molecular typing of isolates. A total of 939 patients were screened, 636 within 72 h of admission (on admission) and 303 >72 h after admission, and 1,252 environmental samples were obtained. Isolates were typed by spa, dru and pulsed-field gel electrophoresis (PFGE) typing. A composite dendrogram generated from the three sets of typing data was used to divide isolates into \\'dendrogram groups\\' (DGs). Ten percent of patients (92\\/939) were MRSA-positive; 7 % (44\\/636) on admission and 16 % (48\\/303) >72 h after admission (p = 0.0007). MRSA was recovered from 5 % of environmental specimens (65\\/1,252). Most isolates from patients (97 %, 85\\/88) and the environment (97 %, 63\\/65) exhibited the ST22-MRSA-IV genotype. Four DGs (DG1, DG4, DG16 and DG17) accounted for 58 % of ST22-MRSA-IV isolates from patients. Epidemiological evidence suggested cross-transmission among 44\\/92 patients (48 %) but molecular typing confirmed probable cross-transmission in only 11 instances (13 %, 11\\/88), with the majority of cross-transmission (64 %; 7\\/11) occurring on one ward. In the setting of highly clonal endemic MRSA, the combination of local epidemiology, PFGE, spa and dru typing provided valuable insights into MRSA transmission.

  2. Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

    CERN Document Server

    Lauck, Ronald; Bromberger, Benjamin; Dangendorf, Volker; Goldberg, Mark B; Mor, Ilan; Tittelmeier, Kai; Vartsky, David

    2009-01-01

    For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specif...

  3. Control of transmission of right circularly polarized laser light in overdense plasma by applied magnetic field pulses.

    Science.gov (United States)

    Ma, Guangjin; Yu, Wei; Yu, M Y; Luan, Shixia; Wu, Dong

    2016-05-01

    The effect of a transient magnetic field on right-hand circularly polarized (RHCP) laser light propagation in overcritical-density plasma is investigated. When the electron gyrofrequency is larger than the wave frequency, RHCP light can propagate along the external magnetic field in an overcritical density plasma without resonance or cutoff. However, when the magnetic field falls to below the cyclotron resonance point, the propagating laser pulse will be truncated and the local plasma electrons resonantly heated. Particle-in-cell simulation shows that when applied to a thin slab, the process can produce intense two-cycle light pulses as well as long-lasting self-magnetic fields.

  4. Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

    Energy Technology Data Exchange (ETDEWEB)

    Meisner, Ludmila L.; Semin, Viktor O.; Gudimova, Ekaterina Y. [Institute of Strength Physicists and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Neiman, Alexey A., E-mail: nasa@ispms.tsc.ru; Lotkov, Alexander I.; Ostapenko, Marina G. [Institute of Strength Physicists and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Koval, Nikolai N.; Teresov, Anton D. [National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    By transmission electron microscopy method the evolution of structural-phase states on a depth of close to equiatomic NiTi modified layer has been studied. Modification performed by pulse impact on its surface low-energy high-current electron beam (beam energy density 10 J/sm{sup 2}, 10 pulses, pulse duration 50mks). It is established that during the treatment in the layer thickness of 8–10 μm, the melting of primary B2 phase and contained therein as Ti2Ni phase particles occurs. The result is change in the concentration ratio of titanium and nickel in the direction of increasing titanium content, which was confirmed by X-ray analysis in the form of increased unit cell parameter B2 phase. Analysis of the electron diffraction pattern showed that the modified layer is characterized as a highly distorted structure on the basis of bcc lattice. Lattice distortions are maximal near the surface and extends to a depth of melt. In subjacent layer there is gradual decline lattice distortions is observed.

  5. Validation of 3D Code KATRIN For Fast Neutron Fluence Calculation of VVER-1000 Reactor Pressure Vessel by Ex-Vessel Measurements and Surveillance Specimens Results

    Science.gov (United States)

    Dzhalandinov, A.; Tsofin, V.; Kochkin, V.; Panferov, P.; Timofeev, A.; Reshetnikov, A.; Makhotin, D.; Erak, D.; Voloschenko, A.

    2016-02-01

    Usually the synthesis of two-dimensional and one-dimensional discrete ordinate calculations is used to evaluate neutron fluence on VVER-1000 reactor pressure vessel (RPV) for prognosis of radiation embrittlement. But there are some cases when this approach is not applicable. For example the latest projects of VVER-1000 have upgraded surveillance program. Containers with surveillance specimens are located on the inner surface of RPV with fast neutron flux maximum. Therefore, the synthesis approach is not suitable enough for calculation of local disturbance of neutron field in RPV inner surface behind the surveillance specimens because of their complicated and heterogeneous structure. In some cases the VVER-1000 core loading consists of fuel assemblies with different fuel height and the applicability of synthesis approach is also ambiguous for these fuel cycles. Also, the synthesis approach is not enough correct for the neutron fluence estimation at the RPV area above core top. Because of these reasons only the 3D neutron transport codes seem to be satisfactory for calculation of neutron fluence on the VVER-1000 RPV. The direct 3D calculations are also recommended by modern regulations.

  6. A Comprehensive Study on Gamma-Ray Exposure Build-Up Factors and Fast Neutron Removal Cross Sections of Fly-Ash Bricks

    Directory of Open Access Journals (Sweden)

    Vishwanath P. Singh

    2013-01-01

    Full Text Available Geometric progression (GP method was utilized to investigate gamma-ray exposure build-up factors of fly-ash bricks for energies from 0.015 to 15 MeV up to 40 mfp penetration depth. The EBFs of the fly-ash bricks are dependent upon the photon energy, penetration depths, and the chemical compositions of the elements. Appreciable variations in exposure build-up factor (EBF are noted for the fly-ash bricks. The EBFs were found to be small in low and high photon energy regions whereas very large in medium energy region. EBF of the bricks is inversely proportional to equivalent atomic number below 10 mfp for entire energy region of interest 0.015 to 15 MeV. The EBFs of fly-ash, brick of mud, and common brick were similar at 1.5 MeV photon energy. The EBF of the fly-ash bricks was found to be higher than that of the brick of mud, and common brick. The fast neutron removal cross sections of the fly-ash bricks, brick of mud, and common bricks were also calculated which were found to be in the same order. It is expected that this study should be very directly useful for shielding effectiveness of fly-ash brick materials and dose estimation.

  7. The influence of fast neutron irradiation on the intra- and intergrain properties of the polycrystalline BiPbSrCaCuO system

    Science.gov (United States)

    Wiśniewski, A.; Baran, M.; Kozioł, Z.; Przysłupski, P.; Piechota, J.; Puźniak, R.; Pajaçzkowska, A.; Pȩkała, M.; Pytel, B.; Pytel, K.

    1990-09-01

    The influence of irradiation by fast neutrons with fluences from 3.3 x 10 16n/ cm2 up to 3 x 10 18n/ cm2 on the physical properties of polycrystalline Bi0.7Pb0.3SrCaCu1.8Ox was examined. Studies of DC magnetization, AC susceptibility, transport and thermoelectric power were performed. The irradiation caused a decrease of Tc, determined from the onset of diamagnetism, by as much as 31 K for a fluence of 3 x 10 18n/ cm2. A strong influence of neutron irradiation on both intra- and intergranular properties was observed. The defects within the superconducting grains created by neutrons caused an increase of the pinning forces which enhanced the critical magnetization current. A gradual decoupling of Josephson weak links with increasing neutron fluence was observed in transport and low field magnetization measurements. From the AC susceptibility measurements the irreversibility lines between the flux-creep and flux-flow regions were determined. An increase of the absolute values of thermoelectric power with rising fluence was noticed.

  8. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Pignol, J.-P. [Toronto-Sunnybrook Regional Cancer Centre, Radiotherapy Dept., Toronto, Ontario (Canada); Slabbert, J. [National Accelerator Centre, Faure (South Africa)

    2001-02-01

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,{alpha}) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends. (author)

  9. Cosmic-ray-induced sup 6 sup 3 Ni -A potential confounder of fast-neutron-induced sup 6 sup 3 Ni in copper samples from Hiroshima

    CERN Document Server

    Rühm, W; Wallner, A; Fästermann, T; Knie, K; Heisinger, B; Nolte, E; Korschinek, G; Marchetti, A A; Martinelli, R E; Carroll, K L

    2003-01-01

    Recently, the determination of sup 6 sup 3 Ni in copper samples has been suggested as a means to assess fast-neutron fluences in Hiroshima and Nagasaki. In those samples, sup 6 sup 3 Ni (half-life: 100.07 years) was produced by MeV neutrons from the A-bomb explosions via the reaction sup 6 sup 3 Cu(n,p) sup 6 sup 3 Ni. For large distances from the hypocenters, cosmic-ray-induced production of sup 6 sup 3 Ni might also be important and, therefore, it is calculated here. The effective probability f sup * which is required to quantify the cosmic-ray-induced production by stopped muons, was measured, and a value of (12.6 +-1.6)% obtained. The cross-section for the cosmic-ray-induced production by fast muons was measured to be (0.64 +-0.33) mb, at a muon energy of 100 GeV. To validate the proposed method, cosmic-ray-induced production of sup 3 sup 2 P in sulfur and of sup 3 sup 9 Ar in granite was also calculated, and reasonable agreement with literature values was found. Our estimates indicate that as many as (4 ...

  10. Use of fast neutrons for assessing sarcopenia by measuring body phosphorus: relevance to health and quality of life of the elderly

    Science.gov (United States)

    Kehayias, Joseph J.; Zhuang, Hong; Doherty, Patricia L.

    1997-02-01

    Sarcopenia, defined as the loss of skeletal muscle with age, may lead to frailty, fractures due to falls, and reduced immunity to disease. By understanding the causes of muscle loss with age we will be able to develop ways of maintaining functional capacity and quality of life for the elderly. Elemental Partition Analysis (EPA) is a new approach to body composition assessment. A major element of the body is measured and then, by means of other measurements, is partitioned to the contributing body compartments. We developed a model for measuring total body muscle by applying the EPA method to total body phosphorus (TBP). We measure TBP by in vivo fast neutron activation analysis using the reaction 31P(n,(alpha) )28Al. The main contributors to TBP are bone and skeletal muscle. Adipose tissue and the liver contribute less than 3 percent. We use dual-energy x-ray absorptiometry (DXA) to evaluate the contribution of bone to TBP. COrrections are applied for the small contributions of the liver and adipose tissue to TBP to derive muscle phosphorus. The technique requires high precision measurements for both TBP and DXA. The total body radiation exposure for measuring human subjects is 0.30 mSv.

  11. Oxidative Damage and Mutagenic Potency of Fast Neutron and UV-B Radiation in Pollen Mother Cells and Seed Yield of Vicia faba L.

    Directory of Open Access Journals (Sweden)

    Ekram Abdel Haliem

    2013-01-01

    Full Text Available In recent years, there has been a great deal of attention toward free radicals, reactive oxygen species (ROS generated by exposure of crop plant cells to physical radiations. Henceforth, the current study was planned to compare oxidative stress and mutagenic potential of different irradiation doses of fast neutron (FN and UV-B on meiotic-pollen mother cells (PMCs, pollen grains (PGs and seeds yielded from irradiated faba beans seedlings. On the cytogenetic level, each irradiation type had special interference with DNA of PMC and exhibited wide range of mutagenic action on the frequency and type of chromosomal anomalies, fertility of PGs and seed yield productivity based on the irradiation exposure dose and radiation sensitivity of faba bean plants compared with un-irradiated ones. On the molecular level, SDS-PAGE and RPAD-PCR analyses of seeds yielded from irradiated seedlings exhibited distinctive polymorphisms based on size, intensity, appearance, and disappearance of polypeptides bands compared with un-irradiated ones. The total values of protein and DNA polymorphisms reached 88% and 90.80% respectively. The neutron fluency (2.3 × 106 n/cm2 and UV-B dose for 1 hr were recorded as bio-positive effects. The present study proved that genetic variations revealed by cytogenetic test could be supported by gene expression (alterations in RAPD and protein profiles.

  12. Effects of Fission Yield Data in the Calculation of Antineutrino Spectra for 235U (n ,fission) at Thermal and Fast Neutron Energies

    Science.gov (United States)

    Sonzogni, A. A.; McCutchan, E. A.; Johnson, T. D.; Dimitriou, P.

    2016-04-01

    Fission yields form an integral part of the prediction of antineutrino spectra generated by nuclear reactors, but little attention has been paid to the quality and reliability of the data used in current calculations. Following a critical review of the thermal and fast ENDF/B-VII.1 235U 235 fission yields, deficiencies are identified and improved yields are obtained, based on corrections of erroneous yields, consistency between decay and fission yield data, and updated isomeric ratios. These corrected yields are used to calculate antineutrino spectra using the summation method. An anomalous value for the thermal fission yield of 86Ge generates an excess of antineutrinos at 5-7 MeV, a feature which is no longer present when the corrected yields are used. Thermal spectra calculated with two distinct fission yield libraries (corrected ENDF/B and JEFF) differ by up to 6% in the 0-7 MeV energy window, allowing for a basic estimate of the uncertainty involved in the fission yield component of summation calculations. Finally, the fast neutron antineutrino spectrum is calculated, which at the moment can only be obtained with the summation method and may be relevant for short baseline reactor experiments using highly enriched uranium fuel.

  13. Effects of Fission Yield Data in the Calculation of Antineutrino Spectra for ^{235}U(n,fission) at Thermal and Fast Neutron Energies.

    Science.gov (United States)

    Sonzogni, A A; McCutchan, E A; Johnson, T D; Dimitriou, P

    2016-04-01

    Fission yields form an integral part of the prediction of antineutrino spectra generated by nuclear reactors, but little attention has been paid to the quality and reliability of the data used in current calculations. Following a critical review of the thermal and fast ENDF/B-VII.1 ^{235}U fission yields, deficiencies are identified and improved yields are obtained, based on corrections of erroneous yields, consistency between decay and fission yield data, and updated isomeric ratios. These corrected yields are used to calculate antineutrino spectra using the summation method. An anomalous value for the thermal fission yield of ^{86}Ge generates an excess of antineutrinos at 5-7 MeV, a feature which is no longer present when the corrected yields are used. Thermal spectra calculated with two distinct fission yield libraries (corrected ENDF/B and JEFF) differ by up to 6% in the 0-7 MeV energy window, allowing for a basic estimate of the uncertainty involved in the fission yield component of summation calculations. Finally, the fast neutron antineutrino spectrum is calculated, which at the moment can only be obtained with the summation method and may be relevant for short baseline reactor experiments using highly enriched uranium fuel.

  14. Validation of 3D Code KATRIN For Fast Neutron Fluence Calculation of VVER-1000 Reactor Pressure Vessel by Ex-Vessel Measurements and Surveillance Specimens Results

    Directory of Open Access Journals (Sweden)

    Dzhalandinov A.

    2016-01-01

    Full Text Available Usually the synthesis of two-dimensional and one-dimensional discrete ordinate calculations is used to evaluate neutron fluence on VVER-1000 reactor pressure vessel (RPV for prognosis of radiation embrittlement. But there are some cases when this approach is not applicable. For example the latest projects of VVER-1000 have upgraded surveillance program. Containers with surveillance specimens are located on the inner surface of RPV with fast neutron flux maximum. Therefore, the synthesis approach is not suitable enough for calculation of local disturbance of neutron field in RPV inner surface behind the surveillance specimens because of their complicated and heterogeneous structure. In some cases the VVER-1000 core loading consists of fuel assemblies with different fuel height and the applicability of synthesis approach is also ambiguous for these fuel cycles. Also, the synthesis approach is not enough correct for the neutron fluence estimation at the RPV area above core top. Because of these reasons only the 3D neutron transport codes seem to be satisfactory for calculation of neutron fluence on the VVER-1000 RPV. The direct 3D calculations are also recommended by modern regulations.

  15. Determination of radionuclides induced by fast neutrons from the JCO criticality accident in Tokai-mura, Japan for estimating neutron doses.

    Science.gov (United States)

    Kojima, S; Imanaka, T; Takada, J; Mitsugashira, T; Nakanishi, T; Seki, R; Kondo, M; Sasaki, K I; Saito, T; Yamaguchi, Y; Furukawa, M

    2001-09-01

    A criticality accident occurred at a uranium conversion facility in Tokai-mura, Japan on September 30, 1999, and fission neutrons were continuously emitted for about 20 hours. Materials of stainless steel or iron, and chemical reagents were collected at places between 2 m and 270 m from the criticality accident site on October 25 and 26, 1999, November 27, 1999 and February 11, 2000. Neutron-induced radionuclides. such as 54Mn and 58Co, in the materials exposed to fast neutrons from the accident were measured to estimate the neutron fluences and energy distributions. Highly sensitive y-ray spectrometry with a well-type Ge detector was performed after radiochemical separation of Mn and Co from the materials. An instrumental neutron activation analysis was mainly applied for determinations of the target elements and chemical yields. The concentrations of 54Mn and 58Co in a mesh screen of stainless steel collected at a location 2.0 m from the accident site were determined. The total number of fission events was evaluated to be 2.5 x 10(18) by Monte-Carlo calculations of neutron transfer by considering the observed values of 54Mn and 58Co. The results presented here are fundamental to estimate the neutron doses at various distances.

  16. Paving the Road for Modern Particle Therapy – What Can We Learn from the Experience Gained with Fast Neutron Therapy in Munich?

    Science.gov (United States)

    Specht, Hanno M.; Neff, Teresa; Reuschel, Waltraud; Wagner, Franz M.; Kampfer, Severin; Wilkens, Jan J.; Petry, Winfried; Combs, Stephanie E.

    2015-01-01

    While neutron therapy was a highly topical subject in the 70s and 80s, today there are only a few remaining facilities offering fast neutron therapy (FNT). Nevertheless, up to today more than 30,000 patients were treated with neutron therapy. For some indications like salivary gland tumors and malignant melanoma, there is clinical evidence that the addition of FNT leads to superior local control compared to photon treatment alone. FNT was available in Munich from 1985 until 2000 at the Reactor Neutron Therapy (RENT) facility. Patient treatment continued at the new research reactor FRM II in 2007 under improved treatment conditions, and today it can still be offered to selected patients as an individual treatment option. As there is a growing interest in high-linear energy transfer (LET) therapy with new hadron therapy centers emerging around the globe, the clinical data generated by neutron therapy might help to develop biologically driven treatment planning algorithms. Also FNT might experience its resurgence as a combinational partner of modern immunotherapies. PMID:26640777

  17. Paving the Road for Modern Particle Therapy - What Can We Learn from the Experience Gained with Fast Neutron Therapy in Munich?

    Science.gov (United States)

    Specht, Hanno M; Neff, Teresa; Reuschel, Waltraud; Wagner, Franz M; Kampfer, Severin; Wilkens, Jan J; Petry, Winfried; Combs, Stephanie E

    2015-01-01

    While neutron therapy was a highly topical subject in the 70s and 80s, today there are only a few remaining facilities offering fast neutron therapy (FNT). Nevertheless, up to today more than 30,000 patients were treated with neutron therapy. For some indications like salivary gland tumors and malignant melanoma, there is clinical evidence that the addition of FNT leads to superior local control compared to photon treatment alone. FNT was available in Munich from 1985 until 2000 at the Reactor Neutron Therapy (RENT) facility. Patient treatment continued at the new research reactor FRM II in 2007 under improved treatment conditions, and today it can still be offered to selected patients as an individual treatment option. As there is a growing interest in high-linear energy transfer (LET) therapy with new hadron therapy centers emerging around the globe, the clinical data generated by neutron therapy might help to develop biologically driven treatment planning algorithms. Also FNT might experience its resurgence as a combinational partner of modern immunotherapies.

  18. Procedure of calculation of the spatial distribution of temperatures and heat fluxes in the steam generator of a nuclear power installation with an RBEC fast-neutron reactor

    Science.gov (United States)

    Frolov, A. A.; Sedov, A. A.

    2016-08-01

    A method for combined 3D/1D-modeling of thermohydraulics of a once-through steam generator (SG) based on the joint analysis of three-dimensional thermo- and hydrodynamics of a single-phase heating coolant in the intertube space and one-dimensional thermohydraulics of steam-generating channels (tubes) with the use of well-known friction and heat-transfer correlations under various boiling conditions is discussed. This method allows one to determine the spatial distribution of temperatures and heat fluxes of heat-exchange surfaces of SGs with a single-phase heating coolant in the intertube space and with steam generation within tubes. The method was applied in the analytical investigation of typical operation of a once-through SG of a nuclear power installation with an RBEC fast-neutron heavy-metal reactor that is being designed by Kurchatov Institute in collaboration with OKB GIDROPRESS and Leipunsky Institute of Physics and Power Engineering. Flow pattern and temperature fields were obtained for the heavy-metal heating coolant in the intertube space. Nonuniformities of heating of the steam-water coolant in different heat-exchange tubes and nonuniformities in the distribution of heat fluxes at SG heat-exchange surfaces were revealed.

  19. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation.

    Science.gov (United States)

    Pignol, J P; Slabbert, J

    2001-02-01

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,alpha) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.

  20. J{sub c} increase of MPMG-processed YBa{sub 2}Cu{sub 3}O{sub 7-x} (Y-123) bulk due to fast neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Terai, Takayuki [University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656 (Japan)], E-mail: tera@n.t.u-tokyo.ac.jp; Nagamoto, Yoshifumi; Kubo, Toshiharu [University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656 (Japan); Chikumoto, Noriko [SRL-ISTEC, 1-10-13 Shinonome, Tokyo 135-0062 (Japan); Sawa, Kazuhiro [Japan Atomic Energy Agency, 3607 Narita-cho, Oarai 311-1394 (Japan)

    2007-09-01

    The change in pinning properties of YBa{sub 2}Cu{sub 3}O{sub 7-x} (Y-123) prepared by MPMG process due to fast neutron irradiation and thermal annealing treatment was investigated in order to confirm that fast neutron irradiation is effective for the J{sub c} increase in practical material as well as single crystal. In this study, MPMG-processed Y-123 specimens (1.5 mm x 1.0 mm x 0.5 mm) with 0.5 wt% of Pt were irradiated with fast neutrons from 2.9 x 10{sup 15} cm{sup -2} to 8.0 x 10{sup 18} cm{sup -2} below 313 K. Before and after the fast neutron irradiation, J{sub c} was evaluated from the magnetic hysteresis loop at 20 K, 40 K and 60 K using the extended Bean's model, and pinning potential was obtained from the magnetic relaxation curve at 20 K. In addition, T{sub c} was evaluated by AC magnetization measurement. The maximum values of J{sub c} were 1200 kA cm{sup -2} at 20 K and 7 T, and 400 kA cm{sup -2} at 40 K and 7 T. They exceeded the target value for its practical superconducting magnet uses e.g. nuclear fusion reactor, magnetic levitation, etc. Furthermore, T{sub c} was recovered sufficiently by the thermal annealing treatment. It turns out that the pinning centers introduced by neutron irradiation work effectively also in the practical material which has already included the strong pinning centers of dispersed Y-211 phase.

  1. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons; Etude de la production de faisceaux riches en neutrons par fission induite par neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Ch

    2000-09-15

    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.

  2. Development of a Scanning Microscale Fast Neutron Irradiation Platform for Examining the Correlation Between Local Neutron Damage and Graphite Microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Pinhero, Patrick [Univ. of Missouri, Columbia, MO (United States); Windes, William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-10

    The fast particle radiation damage effect of graphite, a main material in current and future nuclear reactors, has significant influence on the utilization of this material in fission and fusion plants. Atoms on graphite crystals can be easily replaced or dislocated by fast protons and result in interstitials and vacancies. The currently accepted model indicates that after most of the interstitials recombine with vacancies, surviving interstitials form clusters and furthermore gather to create loops with each other between layers. Meanwhile, surviving vacancies and interstitials form dislocation loops on the layers. The growth of these inserted layers cause the dimensional increase, i.e. swelling, of graphite. Interstitial and vacancy dislocation loops have been reported and they can easily been observed by electron microscope. However, observation of the intermediate atom clusters becomes is paramount in helping prove this model. We utilize fast protons generated from the University of Missouri Research Reactor (MURR) cyclotron to irradiate highly- oriented pyrolytic graphite (HOPG) as target for this research. Post-irradiation examination (PIE) of dosed targets with high-resolution transmission electron microscopy (HRTEM) has permit observation and analysis of clusters and dislocation loops to support the proposed theory. Another part of the research is to validate M.I. Heggie’s Ruck and Tuck model, which introduced graphite layers may fold under fast particle irradiation. Again, we employed microscopy to image irradiated specimens to determine how the extent of Ruck and Tuck by calculating the number of folds as a function of dose. Our most significant accomplishment is the invention of a novel class of high-intensity pure beta-emitters for long-term lightweight batteries. We have filed four invention disclosure records based on the research conducted in this project. These batteries are lightweight because they consist of carbon and tritium and can be

  3. Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators: State of the art

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Guillaume H.V. [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France); Hamel, Matthieu, E-mail: matthieu.hamel@cea.fr [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France); Normand, Stéphane [CEA, DAM, Le Ponant, 25 rue Leblanc, F-75015 Paris (France); Sguerra, Fabien [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France)

    2015-03-11

    We would like to present here with the eyes of the chemist the most recent developments of plastic scintillators (PS) for neutron detection. This review covers the period from 2000 to August 2014, and is fragmented in two main chapters. The first chapter deals with the chemical modifications for thermal neutron capture, whereas the second chapter presents the various strategies used to enhance the response to fast neutrons via pulse shape discrimination. For each chapter the theory is also explained.

  4. The HEMP (High-Altitude Electromagnetic Pulse) Response of a Long Transmission Line Buried in the Earth.

    Science.gov (United States)

    1984-09-01

    Carnahan, H. A. Luther, and J. 0. Wilkes, Applied Numerical methods , John Wiley and Sons (1969), 440-442. *6. Alf red G. Brandatein and Egon Marx... Numerical Methods , John Wiley and Sons (1969), 440-442. 10 ." . *..,** .,.. *..;.* . . . . ....... .. . * . *o .. . *. .*. ..*. . . .. . -S . ° .S...the transmission line, as shown in figure 3. Hence, equation (6) is expanded in the form5 5 B. Carnahan, H. A. Luther, and J. 0. Wilkes, Applied

  5. Modified Approach for Harmonic Reduction in Transmission System Using 48-pulse UPFC Employing Series Zig-Zag Primary and Y-Y Secondary Transformer

    Directory of Open Access Journals (Sweden)

    Ragini Malviya

    2013-10-01

    Full Text Available In this paper THD (Total Harmonic Distortion is analysed and compared by using UPFC in a multi-line transmission system of 500 KV having 5-buses in two different arrangements. The UPFC converters are arranged as a Diode Clamped multilevel Converter (DCMLC that leads to the cost reduction as compared with other multi-level converters. The comparison has been done by both series zig-zag/2Y-2Δ and series zig-zag/4Y transformer configuration for 48-pulses GTO based diode clamped converter. The THD is reduced to 42.59% and 58.82% of input waveform at bus B_2 by using series zig-zag/4Y transformer configuration. This transformer converter configuration also reduces the difficulty of designing the transformer winding ratio. For calculation of THD, FFT analysis is carried out using MATLAB.

  6. Polystyrene-based scintillator with pulse-shape discrimination capability

    Energy Technology Data Exchange (ETDEWEB)

    Zhmurin, P.N.; Lebedev, V.N.; Titskaya, V.D.; Adadurov, A.F., E-mail: adadurov@isma.kharkov.ua; Elyseev, D.A.; Pereymak, V.N.

    2014-10-11

    Polystyrene-based scintillators with 2-phenyl-5-(4-tert-butylephenyl)-1,3,4-oxadiazole (tert-BuPPD) or 2,5-di-(3-methylphenyl)-1,3,4 oxadiazole (m-DMePPD) are proposed for pulse-shape n/γ-discrimination. These scintillators have improved mechanical properties, long operational time and high n/γ discrimination parameter – figure of merit (1.49 and 1.81 in a wide energy region), so they can be used as detectors of fast neutrons in the presence of gamma radiation background.

  7. Neutron Resonance Transmission Analysis (NRTA): Initial Studies of a Method for Assaying Plutonium in Spent Fuel

    Energy Technology Data Exchange (ETDEWEB)

    David L. Chichester; James W. Sterbentz

    2011-05-01

    Neutron Resonance Transmission Analysis (NRTA) is an analytical technique that uses neutrons to assay the isotopic content of bulk materials. The technique uses a pulsed accelerator to produce an intense, short pulse of neutrons in a time-of-flight configuration. These neutrons, traveling at different speeds according to their energy, can be used to interrogate a spent fuel (SF) assembly to determine its plutonium content. Neutron transmission through the assembly is monitored as a function of neutron energy (time after the pulse), similar to the way neutron cross-section data is often collected. The transmitted neutron intensity is recorded as a function of time, with faster (higher-energy) neutrons arriving first and slower (lower-energy) neutrons arriving later. The low-energy elastic scattering and absorption resonances of plutonium and other isotopes modulate the transmitted neutron spectrum. Plutonium content in SF can be determined by analyzing this attenuation. Work is currently underway at Idaho National Laboratory, as a part of United States Department of Energy's Next Generation Safeguards Initiative (NGSI), to investigate the NRTA technique and to assess its feasibility for quantifying the plutonium content in SF and for determining the diversion of SF pins from assemblies. Preliminary results indicate that NRTA has great potential for being able to assay intact SF assemblies. Operating in the 1-40 eV range, it can identify four plutonium isotopes (239, 240, 241, & 242Pu), three uranium isotopes (235, 236, & 238U), and six resonant fission products (99Tc, 103Rh, 131Xe, 133Cs, 145Nd, and 152Sm). It can determine the areal density or mass of these isotopes in single- or multiple-pin integral transmission scans. Further, multiple observables exist to allow the detection of material diversion (pin defects) including fast-neutron and x-ray radiography, gross-transmission neutron counting, plutonium resonance absorption analysis, and fission

  8. An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions

    Science.gov (United States)

    Ajay Kumar, M.; Srikanth, N.

    2014-03-01

    In HVDC Light transmission systems, converter control is one of the major fields of present day research works. In this paper, fuzzy logic controller is utilized for controlling both the converters of the space vector pulse width modulation (SVPWM) based HVDC Light transmission systems. Due to its complexity in the rule base formation, an intelligent controller known as adaptive neuro fuzzy inference system (ANFIS) controller is also introduced in this paper. The proposed ANFIS controller changes the PI gains automatically for different operating conditions. A hybrid learning method which combines and exploits the best features of both the back propagation algorithm and least square estimation method is used to train the 5-layer ANFIS controller. The performance of the proposed ANFIS controller is compared and validated with the fuzzy logic controller and also with the fixed gain conventional PI controller. The simulations are carried out in the MATLAB/SIMULINK environment. The results reveal that the proposed ANFIS controller is reducing power fluctuations at both the converters. It also improves the dynamic performance of the test power system effectively when tested for various ac fault conditions.

  9. 一种新型脉动无级变速器及运动特性分析%A new type of pulse continuously variable transmission and motion characteristics analysis

    Institute of Scientific and Technical Information of China (English)

    孙建东; 雷红; 刘自萍; 田娥; 付文宇

    2012-01-01

    介绍一种具有自主知识产权的新型脉动无级变速器,讨论了该变速器的工作原理,分析了该变速器的主要运动特性,并与现有的其他类型的脉动无级变速器进行对比分析.分析结论表明,该变速器具有比较优异的运动性能.%Describes a new type of pulse continuously variable transmission; discuss the working principle, analyzes the major sports characteristics, and compare with other types of current pulse Continuously Variable Transmission ( CVT). The results show that the transmission has a relatively superior sports performance.

  10. Study of fast neutron scattering. The displacement cross-section (1962); Etude de la diffusion des neutrons rapides. Section efficace de deplacement (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Millot, J.P. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1962-07-01

    We propose a method for calculating the biological efficiency of fast neutrons emitted by in-pile fission sources. This method justifies the empirical theory of Albert and Welton. In making simple assumptions concerning the cross-sections, we have supposed that the propagation can ben reduced to a mono-kinetic problem. A system of orthonormal functions is then set up making it possible to calculate the flux leaving a planar source. This method generalises the results obtained by Platzek to the case where the elastic cross-sections are not isotropic, and make it possible in particular to define a displacement cross-section: extension of the diffusion coefficient. This method can be generalised to the case of neutron diffraction as a function of time, and to the study of slowing-down. Numerical results are given in an appendix for the following: H{sub 2}O, D{sub 2}O, Fe, Be, Pb, CH, CH{sub 2}. These cross-sections have been verified experimentally in water and in graphite for neutrons of 2.5 and 14 MeV using a SAMES accelerator and a 2 MeV Van De Graaff. (author) [French] Nous proposons une methode permettant de calculer l'efficacite biologique des neutrons rapides issus des sources de fission dans la protection d'une pile. Cette methode justifie la theorie empirique d'Albert et Welton. En faisant des hypotheses simples sur les sections efficaces, nous avons suppose que la propagation pouvait etre ramenee a un probleme monocinetique. Nous construisons alors un systeme de fonctions orthonormales qui permet de calculer le flux issu d'une source plane. Cette methode generalise les resultats obtenus par Platzek au cas ou les sections efficaces elastiques ne sont pas isotropes et en particulier permet de definir une section efficace de deplacement: extension du coefficient de diffusion. Cette methode peut etre generalisee a la diffusion des neutrons en fonction du temps et a l'etude du ralentissement. Les resultats numeriques sont donnes en annexe

  11. Aquelarre. A computer code for fast neutron cross sections from the statistical model; AQUELARRE. Un programa numerico para el calculo de secciones eficaces neutronicas mediante el modelo de nucleo compuesto

    Energy Technology Data Exchange (ETDEWEB)

    Guasp, J.

    1974-07-01

    A Fortran V computer code for Univac 1108/6 using the partial statistical (or compound nucleus) model is described. The code calculates fast neutron cross sections for the (n, n'), (n, p), (n, d) and (n, {alpha}) reactions and the angular distributions and Legendre moments for the (n, n) and (n, n') processes in heavy and intermediate spherical nuclei. A local Optical Model with spin-orbit interaction for each level is employed, allowing for the width fluctuation and Moldauer corrections, as well as the inclusion of discrete and continuous levels. (Author) 67 refs.

  12. Determination of nitrogen in wheat flour through Activation analysis using Fast neutron flux of a Thermal nuclear reactor; Determinacion de nitrogeno en harina de trigo mediante analisis por activacion empleando el flujo de neutrones rapidos de un reactor nuclear termico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, T

    1976-07-01

    In this work is done a technical study for determining Nitrogen (protein) and other elements in wheat flour Activation analysis, with Fast neutrons from a Thermal nuclear reactor. Initially it is given an introduction about the basic principles of the methods of analysis. Equipment used in Activation analysis and a brief description of the neutron source (Thermal nuclear reactor). The realized experiments for determining the flux form in the irradiation site, the half life of N-13 and the interferences due to the sample composition are included too. Finally, the obtained results by Activation and the Kjeldahl method are tabulated. (Author)

  13. High-resolution transmission electron microscopy investigation of nanostructures in SnO 2 thin films prepared by pulsed laser deposition

    Science.gov (United States)

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.

    2005-03-01

    Pulsed laser deposition (PLD) was used to grow nanocrystalline SnO 2 thin films onto glass substrates. The nanocrystallites and microstructures in SnO 2 thin films grown by PLD techniques have been investigated in detail by using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). The PLD process was carried out at room temperature under a working pressure of about 2×10 -6 mbar. Experimental results indicate that thin films are composed of a polycrystalline SnO 2 and an amorphous SnO phase. In particular, the presence of such an amorphous SnO phase in the thin films greatly limits their practical use as gas-sensing devices. HRTEM observations revealed that SnO 2 nanocrystallites with tetragonal rutile structure embed in an amorphous SnO matrix, which are approximatively equiaxed. These approximatively equiaxed SnO 2 nanocrystallites contain a high density of defects, such as twin boundaries and edge dislocations. The grain growth of SnO 2 thin films may be discussed in terms of the coalescent particle growth mechanism.

  14. Modal dispersion, pulse broadening and maximum transmission rate in GRIN optical fibers encompass a central dip in the core index profile

    Science.gov (United States)

    El-Diasty, Fouad; El-Hennawi, H. A.; El-Ghandoor, H.; Soliman, Mona A.

    2013-12-01

    Intermodal and intramodal dispersions signify one of the problems in graded-index multi-mode optical fibers (GRIN) used for LAN communication systems and for sensing applications. A central index dip (depression) in the profile of core refractive-index may occur due to the CVD fabrication processes. The index dip may also be intentionally designed to broaden the fundamental mode field profile toward a plateau-like distribution, which have advantages for fiber-source connections, fiber amplifiers and self-imaging applications. Effect of core central index dip on the propagation parameters of GRIN fiber, such as intermodal dispersion, intramodal dispersion and root-mean-square broadening, is investigated. The conventional methods usually study optical signal propagation in optical fiber in terms of mode characteristics and the number of modes, but in this work multiple-beam Fizeau interferometry is proposed as an inductive but alternative methodology to afford a radial approach to determine dispersion, pulse broadening and maximum transmission rate in GRIN optical fiber having a central index dip.

  15. Estimation of fast neutron fluence in steel specimens type Laguna Verde in TRIGA Mark III reactor; Estimacion de la fluencia de neutrones rapidos en probetas de acero tipo Laguna Verde en el reactor Triga Mark III

    Energy Technology Data Exchange (ETDEWEB)

    Galicia A, J.; Francois L, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Aguilar H, F., E-mail: blink19871@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    The main purpose of this work is to obtain the fluence of fast neutrons recorded within four specimens of carbon steel, similar to the material having the vessels of the BWR reactors of the nuclear power plant of Laguna Verde when subjected to neutron flux in a experimental facility of the TRIGA Mark III reactor, calculating an irradiation time to age the material so accelerated. For the calculation of the neutron flux in the specimens was used the Monte Carlo code MCNP5. In an initial stage, three sheets of natural molybdenum and molybdenum trioxide (MoO{sub 3}) were incorporated into a model developed of the TRIGA reactor operating at 1 M Wth, to calculate the resulting activity by setting a certain time of irradiation. The results obtained were compared with experimentally measured activities in these same materials to validate the calculated neutron flux in the model used. Subsequently, the fast neutron flux received by the steel specimens to incorporate them in the experimental facility E-16 of the reactor core model operating at nominal maximum power in steady-state was calculated, already from these calculations the irradiation time required was obtained for values of the neutron flux in the range of 10{sup 18} n/cm{sup 2}, which is estimated for the case of Laguna Verde after 32 years of effective operation at maximum power. (Author)

  16. Evaluation of adaptation to visually induced motion sickness based on the maximum cross-correlation between pulse transmission time and heart rate

    Directory of Open Access Journals (Sweden)

    Chiba Shigeru

    2007-09-01

    Full Text Available Abstract Background Computer graphics and virtual reality techniques are useful to develop automatic and effective rehabilitation systems. However, a kind of virtual environment including unstable visual images presented to wide field screen or a head mounted display tends to induce motion sickness. The motion sickness induced in using a rehabilitation system not only inhibits effective training but also may harm patients' health. There are few studies that have objectively evaluated the effects of the repetitive exposures to these stimuli on humans. The purpose of this study is to investigate the adaptation to visually induced motion sickness by physiological data. Methods An experiment was carried out in which the same video image was presented to human subjects three times. We evaluated changes of the intensity of motion sickness they suffered from by a subjective score and the physiological index ρmax, which is defined as the maximum cross-correlation coefficient between heart rate and pulse wave transmission time and is considered to reflect the autonomic nervous activity. Results The results showed adaptation to visually-induced motion sickness by the repetitive presentation of the same image both in the subjective and the objective indices. However, there were some subjects whose intensity of sickness increased. Thus, it was possible to know the part in the video image which related to motion sickness by analyzing changes in ρmax with time. Conclusion The physiological index, ρmax, will be a good index for assessing the adaptation process to visually induced motion sickness and may be useful in checking the safety of rehabilitation systems with new image technologies.

  17. Development of High - voltage Pulse - transmission Electric Cable for Plasma Drill%等离子体钻机高压脉冲传输电缆的研制

    Institute of Scientific and Technical Information of China (English)

    季念迎; 裴彦良; 闫克平; 刘晨光; 章志成

    2012-01-01

    设计了等离子钻机高压脉冲传输电缆的结构,讨论了高压绝缘层的设计及材料选择.在此基础上,开展了高压脉冲传输电缆的绝缘阻抗和波阻抗测试实验.实验测试结果表明,所研制的传输电缆具有较高的绝缘性能和较小的波阻抗,可基本满足等离子体钻机的需要.%The structure of the high - voltage pulse - transmission electric cable was designed. The design of high - voltage insulation layer and the insulation material were discussed. Based on what mentioned above, the insulating resistance and the wave resistance tests of the high - voltage pulse - transmission electric cable were carried out. The test results show that the high - voltage pulse - transmission electric cable has good insulating property and little wave resistance, which meets the challenges of the plasma drill.

  18. The fast neutrons reactors, the sodium, the fuel cycle: evaluation of the knowledge, innovation potential and forecast; Les reacteurs a neutrons rapides, le sodium, le cycle du combustible: bilan de l'acquis, potentiel d'innovation et perspectives d'avenir

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, J

    2002-07-01

    This document presents the study, the design and the construction of fast neutrons reactors, cooled with sodium. From this evaluation, it details the innovation possibilities of this sector in the sustainable development context of the nuclear energy. Chapter one presents the physical and physico-chemical properties of the sodium. Chapter two analyzes the properties of the fast cores and the sodium advantages. Chapter three analyzes the great contribution of the EFR project. Chapter four takes stock on the innovation possibilities. And before the conclusion, chapter five shows that the fast neutrons reactors allow the electric power production in agreement with a sustainable development. (A.L.B.)

  19. Comparative analysis of pulse shape discrimination methods in a {sup 6}Li loaded plastic scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Balmer, Matthew J.I., E-mail: m.balmer@lancaster.ac.uk [Department of Engineering, Lancaster University, LA1 4YR (United Kingdom); Gamage, Kelum A.A. [Department of Engineering, Lancaster University, LA1 4YR (United Kingdom); Taylor, Graeme C. [Neutron Metrology Group, National Physical Laboratory, Teddington, TW11 0LW (United Kingdom)

    2015-07-11

    Three algorithms for discriminating between fast neutrons, thermal neutrons and gamma rays in a {sup 6}Li loaded plastic scintillator have been compared. Following a literature review of existing pulse shape discrimination techniques, the performance of the charge comparison method, triangular filtering and frequency gradient analysis were investigated in this work. The scintillator was exposed to three different mixed gamma/neutron radiation fields. The figure of merit of neutron/gamma separation was investigated over a broad energy range, as well as for the neutron capture energy region. After optimisation, all three methods were found to perform similarly in terms of neutron/gamma separation.

  20. Design Study for Pulsed Proton Beam Generation

    Directory of Open Access Journals (Sweden)

    Han-Sung Kim

    2016-02-01

    Full Text Available Fast neutrons with a broad energy spectrum, with which it is possible to evaluate nuclear data for various research fields such as medical applications and the development of fusion reactors, can be generated by irradiating proton beams on target materials such as beryllium. To generate short-pulse proton beam, we adopted a deflector and slit system. In a simple deflector with slit system, most of the proton beam is blocked by the slit, especially when the beam pulse width is short. Therefore, the available beam current is very low, which results in low neutron flux. In this study, we proposed beam modulation using a buncher cavity to increase the available beam current. The ideal field pattern for the buncher cavity is sawtooth. To make the field pattern similar to a sawtooth waveform, a multiharmonic buncher was adopted. The design process for the multiharmonic buncher includes a beam dynamics calculation and three-dimensional electromagnetic simulation. In addition to the system design for pulsed proton generation, a test bench with a microwave ion source is under preparation to test the performance of the system. The design study results concerning the pulsed proton beam generation and the test bench preparation with some preliminary test results are presented in this paper.

  1. Accelerated reduction of used CANDU fuel waste with fast-neutron reactors: fuel cycle strategy cuts TRU waste lifespan from 400,000 years to less than 80 years

    Energy Technology Data Exchange (ETDEWEB)

    Ottensmeyer, P., E-mail: peter.ottensmeyer@utoronto.ca [Univ. of Toronto, Toronto, Ontario, (Canada)

    2013-07-01

    Canada's 45,000 tonnes of nuclear fuel waste contain over 99% heavy atoms whose nuclear energy can provide $50 trillion of non-carbon electricity in fast-neutron reactors (FNRs), equivalent to 4000 years of nuclear power at present levels. FNRs can utilize the 98.9% uranium in CANDU fuel waste and also the 0.38% transuranic actinides which impose its 400,000-year radiotoxicity. Separation of uranium from CANDU nuclear fuel waste would permit refueling of FNRs primarily with transuranics, hugely accelerating the elimination of the long-term radiotoxicity of the CANDU fuel waste. Practicable separations of uranium would result in the complete elimination of the transuranics in about 80 years using FNRs at current Canadian nuclear energy output, while ideal separations could lower this to 16 years. (author)

  2. Investigation of the fission yields of the fast neutron-induced fission of {sup 233}U; Mesure de la distribution en masse et en charge des produits de la fission rapide de l'{sup 233}U

    Energy Technology Data Exchange (ETDEWEB)

    Galy, J

    1999-09-01

    As a stars, a survey of the different methods of investigations of the fission product yields and the experimental data status have been studied, showing advantages and shortcomings for the different approaches. An overview of the existing models for the fission product distributions has been as well intended. The main part of this thesis was the measurement of the independent yields of the fast neutron-induced fission of{sup 233}U, never investigated before this work. The experiment has been carried out using the mass separator OSIRIS (Isotope Separator On-Line). Its integrated ion-source and its specific properties required an analysis of the delay-parameter and ionisation efficiency for each chemical species. On the other hand, this technique allows measurement of independent yields and cumulative yields for elements from Cu to Ba, covering most of the fission yield distribution. Thus, we measured about 180 independent yields from Zn (Z=30) to Sr (Z=38) in the mass range A=74-99 and from Pd (Z=46) to Ba (Z=56) in the mass range A=113-147, including many isomeric states. An additional experiment using direct {gamma}-spectroscopy of aggregates of fission products was used to determine more than 50 cumulative yields of element with half-life from 15 min to a several days. All experimental data have been compared to estimates from a semi-empirical model, to calculated values and to evaluated values from the European library JEF 2.2. Furthermore, a study of both thermal and fast neutron-induced fission of {sup 233}U measured at Studsvik, the comparison of the OSIRIS and LOHENGRIN facilities and the trends in new data for the Reactors Physics have been discussed. (author)

  3. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality...... a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, an anthropomorfized archive of a past intimacy and an all-encompassing immersive environment modulating continuously in real space-time....

  4. Transmission electron microscopy studies of YBCO coated conductors prepared by pulsed-laser deposition and multiple-stage chemical vapor deposition processes

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Takeharu [Materials R and D Lab, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan)]. E-mail: tkato@jfcc.or.jp; Sasaki, Hirokazu [Materials R and D Lab, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Iwai, Hiroyuki [SRL-Nagoya Coated Conductor Center, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Ibi, Akira [SRL-Nagoya Coated Conductor Center, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Kashima, Naoji [Chubu Electric Power Co., Inc., Kitasekiyama, Ohdaka-cho, Midori-ku, Nagoya 459-8522 (Japan); Niwa, Toshiharu [Chubu Electric Power Co., Inc., Kitasekiyama, Ohdaka-cho, Midori-ku, Nagoya 459-8522 (Japan); Muroga, Takemi [SRL-Nagoya Coated Conductor Center, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Miyata, Seiki [SRL-Nagoya Coated Conductor Center, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Watanabe, Tomonori; Yamada, Yutaka; Izumi, Teruo [SRL-Nagoya Coated Conductor Center, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Iijima, Yasuhiro; Kakimoto, Kazuomi; Sutoh, Yasunori [Material Technology Lab, Fujikura Ltd., 1-5-1 Kiba, Koto-ku, Tokyo 135-8512 (Japan); Nagaya, Shigeo [Chubu Electric Power Co., Inc., Kitasekiyama, Ohdaka-cho, Midori-ku, Nagoya 459-8522 (Japan); Saitoh, Takashi [Material Technology Lab, Fujikura Ltd., 1-5-1 Kiba, Koto-ku, Tokyo 135-8512 (Japan); Sasaki, Yukichi; Hirayama, Tsukasa [Materials R and D Lab, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Shiohara, Yuh [SRL-Nagoya Coated Conductor Center, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan)]|[SRL-Division of Superconducting Tapes and Wires, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan); Ikuhara, Yuichi [Materials R and D Lab, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan)

    2005-10-01

    Three types of YBCO films were deposited on metal tapes with biaxially textured CeO{sub 2}/Gd{sub 2}Zr{sub 2}O{sub 7} multilayer. One YBCO film 4 {mu}m in thickness was formed by pulsed-laser deposition (PLD) on the stationary substrate and another film 3 {mu}m in thickness by PLD using a reel-to-reel substrate tape transferring system. I {sub c} values of the films were 173 A and 293 A, respectively A further film 1 {mu}m in thickness was fabricated by multiple-stage chemical vapor deposition (MSCVD). The I {sub c} value of the MSCVD-YBCO film was 100 A. The microstructures of these YBCO films were characterized using transmission electron microscopy (TEM). In the PLD-YBCO films, the films less than 1 {mu}m thick were predominantly composed of c-axis oriented grains which were considered to grow spirally, however, irregular instances of a-axis oriented grains were also found. The a-axis oriented grains size increased with increasing thickness of the YBCO films. In the 4 {mu}m-thick PLD-YBCO film with an I {sub c} value of 173 A, a-axis oriented grains were considered to nucleate on the CeO{sub 2}. We found many Y{sub 2}O{sub 3} and cupper oxides at the boundaries between a- and c-axes oriented grains and the orientation relationships between YBCO and Y{sub 2}O{sub 3} were determined to be as follows: (0 0 1)YBCO//(0 0 1)Y{sub 2}O{sub 3} and (1 0 0)YBCO//(1 1 0)Y{sub 2}O{sub 3}. We also found many gaps and pores between YBCO grains. Nucleation of a-axis oriented grains was completely suppressed on the CeO{sub 2} in the 3 {mu}m-thick PLD-YBCO film with an I {sub c} value of 293 A. In the MSCVD-YBCO film, the YBCO film mostly consisted of c-axis oriented grains, however a-axis oriented grains and polycrystal also formed in the film. As the MSCVD-YBCO film became thicker, the a-axis oriented grains grew large, as same as in the PLD-YBCO films. The growth rate of a-axis oriented grain along the substrate normal was much higher than that of c-axis oriented grains in

  5. Improvements in apparatus and procedures for using an organic liquid scintillator as a fast-neutron spectrometer for radiation protection applications

    Energy Technology Data Exchange (ETDEWEB)

    Thorngate, J.H.

    1987-05-15

    For use in radiation protection measurements, a neutron spectrometer must have a wide energy range, good sensitivity, medium resolution, and ease of taking and reducing data. No single spectrometer meets all of these requirements. Several experiments aimed at improving and characterizing the detector response to gamma rays and neutrons were conducted. A light pipe (25 mm) was needed between the scintillator cell and the photomultiplier tube to achieve the best resolution. The light output of the scintillator as a function of gamma-ray energy was measured. Three experiments were conducted to determine the light output as a function of neutron energy. Monte Carlo calculations were made to evaluate the effects of multiple neutron scattering and edge effects in the detector. The electronic systems associated with the detector were improved with a transistorized circuit providing the bias voltage for the photomultiplier tube dynodes. This circuit was needed to obtain pulse-height linearity over the wide range of signal sizes. A special live-time clock was built to compensate for the large amount of dead time generated by the pulse-shape discrimination circuit we chose to use. 64 refs., 58 figs., 9 tabs.

  6. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality......“Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... of the visitor’s beating heart to the blink of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the blinking light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant...

  7. A Single Pulse Sub-Nanosecond Proton RFQ

    Energy Technology Data Exchange (ETDEWEB)

    Hamm, R W; Pearce-Percy, H; Pearson, D; Rougieri, M; Weir, J; Zografos, A; Guethlein, G; Hawkins, S; Falabella, S; Poole, B; Blackfield, D

    2011-03-29

    A Radio Frequency Quadrupole (RFQ) linac system has been developed to provide a single pulse of 2 MeV protons with a beam pulse width of {approx}300 ps and a charge of 30 pC, either for injection into a pulsed Dielectric Wall Accelerator or for bombardment of a target to produce a fast neutron pulse. The 1.2 m long RFQ structure operates at 425 MHz and bunches and accelerates a single 2.35 ns beam pulse injected into it at 35 keV using a parallel plate deflector placed directly in front of the RFQ entrance. The input acceptance properties of the RFQ allow a simple dc bias voltage on the plates to block acceleration of the unwanted beam, with a short rf voltage pulse applied to null the deflection field for the ions within the 8 mm 'kicker' plate length. The use of the RFQ as the accelerating structure allows one to efficiently produce a large charge in a single sub-ns bunch. In addition, the kicker can also be used without the dc bias voltage to produce a 'notch' in the normal RFQ output beam for synchrotron injection.

  8. Characterization of liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system

    Energy Technology Data Exchange (ETDEWEB)

    Lombigit, L., E-mail: lojius@nm.gov.my; Yussup, N., E-mail: nolida@nm.gov.my; Ibrahim, Maslina Mohd; Rahman, Nur Aira Abd; Rawi, M. Z. M. [Instrumentation Group, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2015-04-29

    A digital n/γ pulse shape discrimination (PSD) system is currently under development at Instrumentation and Automation Centre, Malaysian Nuclear Agency. This system aims at simultaneous detection of fast neutron and gamma ray in mixed radiations environment. This work reports the system characterization performed on the liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system. The characterization involves measurement of electron light output from the BC-501A detector and energy channels calibration of the pulse height spectra acquired with DPSD system using set of photon reference sources. The main goal of this experiment is to calibrate the ADC channel of our DPSD system, characterized the BC-501 detector and find the position of Compton edge which later could be used as threshold for the n/γ PSD experiment. The detector resolution however is worse as compared to other published data but it is expected as our detector has a smaller active volume.

  9. REFLECTANCE PULSE OXIMETRY IN FETAL LAMBS

    NARCIS (Netherlands)

    DASSEL, AC; GRAAFF, R; AARNOUDSE, JG; ELSTRODT, JM; HEIDA, P; KOELINK, MH; DEMUL, FF; GREVE, J

    1992-01-01

    Transmission pulse oximetry is used for monitoring in many clinical settings. However, for fetal monitoring during labor and in situations with poor peripheral perfusion, transmission pulse oximetry cannot be used. Therefore, we developed a reflectance pulse oximeter, which uses the relative intensi

  10. Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

    Science.gov (United States)

    Richardson, Norman E., IV

    nuclear and radiological material. Moreover, the production of 3He isotope as a byproduct of security programs was drastically decreased. This isotope shortage coupled with the disadvantages of relying on a detector that requires neutron moderation before the detection of fission neutrons, poses a significant challenge in supporting the existing detection systems and the development of future technologies. To address this problem, a reliable and accurate alternative technology to detect neutrons emitted in fissions must be developed. One such alternative technology that shows promise in this application is the use of scintillators based on solid state materials (plastics) which are sensitive to fast neutrons. However, plastic scintillators are also sensitive to photons. Hence, it is necessary to separate the neutron signals from the photon signals, using the pulse shape discrimination (PSD) analysis. The PSD is based on the comparison of the pulse shapes of digitized signal waveforms. This approach allows for the measurement of fast neutrons without the necessity of their moderation. Because the fission spectrum neutrons are mainly fast, methods employing fast neutron detection are applicable for the assay of fissile materials. In addition, the average time of scintillation of the plastic medium is much shorter than those of the gaseous counters, thus allowing scintillation detectors to be used in high count rate environments. Furthermore, the temporal information of the fast neutron detection using multiple sensors enables the time correlation analysis of the fission neutron multiplicity. The study of time correlation measurements of fast neutrons using the array of plastic scintillators is the basis of this work. The array of four plastic scintillator detectors equipped with the digital data acquisition and analysis system was developed. The digital PSD analysis of detector signals "on-the-fly" was implemented for the array. The time coincidence measurement technique

  11. 6LiF Semiconductor Sandwich Spectrometer for Fast Neutron Spectrum Measurement%用于快中子能谱测量的6LiF夹心半导体谱仪

    Institute of Scientific and Technical Information of China (English)

    蒋勇; 李俊杰; 张涛; 范晓强; 郑春

    2012-01-01

    A detector of 6LiF semiconductor sandwich spectrometer was designed and manufactured. Characteristics of the spectrometer were tested in the fast neutron critical assembly. Measurement principle, configuration of detector and electronic circuit were introduced. Fast neutron spectrum was measured using the 6LiF semiconductor sandwich spectrometer. When the detector's 6 LiF mass thickness is 186 μg/cm2, the spectrometer's energy resolution is 363 keV in the thermal neutron field. For this spectrometer, the optimal fathomable neutron energy range is 0. 3-7. 5 MeV, and the background counts only take possession of 1 % in this area.%本文介绍了6 LiF夹心谱仪的测量原理、自行设计研制的6LiF夹心半导体谱仪探头结构及电子学系统组成等.在热中子场中测试了夹心谱仪的性能,获得了α粒子峰、T粒子峰及“和”峰在多道上的位置与能量分辨率,并用T粒子与“和”峰两个能量点的峰位对谱仪系统进行了能量刻度.分别用效应探头和本底探头测量了临界装置表面的效应谱和本底谱,当效应探头采用的6 LiF镀层质量厚度为186 μg/cm2时,6 LiF夹心谱仪对热中子的能量分辨率为363 keY,测量中子最佳能区为0.3~7.5 MeV,在该能区内,本底谱约占1%.

  12. Pulse shape discrimination in helium-4 scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Ryan P., E-mail: rpkelley@ufl.edu; Enqvist, Andreas; Jordan, Kelly A.

    2016-09-11

    Three algorithms were investigated for discriminating between neutrons and gamma rays in a pressurized {sup 4}He gas fast neutron detector: charge comparison, weighted integration, and neutron-gamma model analysis (NGMA). For each algorithm, a comprehensive pulse shape discrimination study was conducted using time-of-flight measurements, receiver operator characteristic curves, figure of merit performance measures, and a comparison of performance between {sup 252}Cf and PuBe mixed neutron/gamma sources. The NGMA method was found to have the best overall performance by both the figure of merit and the receiver operator characteristic curve. The results also illustrated the high gamma rejection efficiency of these detectors, which is desirable in a variety of neutron monitoring applications.

  13. Gamma–neutron imaging system utilizing pulse shape discrimination with CLYC

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, Chad M., E-mail: cwhitney@rmdinc.com; Soundara-Pandian, Lakshmi; Johnson, Erik B.; Vogel, Sam; Vinci, Bob; Squillante, Michael; Glodo, Jarek; Christian, James F.

    2015-06-01

    Recently, RMD has investigated the use of CLYC (Cs{sub 2}LiYCl{sub 6}:Ce), a new and emerging scintillation material, in a gamma–neutron coded aperture imaging system based on RMD's commercial RadCam{sup TM} instrument. CLYC offers efficient thermal neutron detection, fast neutron detection capabilities, excellent pulse shape discrimination (PSD), and gamma-ray energy resolution as good as 4% at 662 keV. PSD improves the isolation of higher energy gammas from thermal neutron interactions (>3 MeV electron equivalent peak), compared to conventional pulse height techniques. The scintillation emission time in CLYC provides the basis for PSD; where neutron interactions result in a slower emission rise and decay components while gamma interactions result in a faster emission components. By creating a population plot based on the ratio of the decay tail compared to the total integral amplitude (PSD ratio), discrimination of gammas, thermal neutrons, and fast neutrons is possible. Previously, we characterized the CLYC-based RadCam system for imaging gammas and neutrons using a layered W-Cd coded aperture mask and employing only pulse height discrimination. In this paper, we present the latest results which investigate gamma-neutron imaging capabilities using PSD. An FPGA system is used to acquire the CLYC–PSPMT last dynode signals, determine a PSD ratio for each event, and compare it to a calibrated PSD cutoff. Each event is assigned either a gamma (low) or neutron (high) flag signal which is then correlated with the imaging information for each event. - Highlights: • The latest results are presented for our CLYC RadCam-2 system which investigate gamma–neutron imaging using pulse shape discrimination. • CLYC RadCam-2 system successfully discriminates gammas, thermal neutrons, and fast neutrons by employing a fully integrated, FPGA-based PSD system. • Imaging of our {sup 252}Cf source was possible using both pulse height and pulse shape discrimination with

  14. Photonuclear Contributions to SNS Pulse Shapes

    Energy Technology Data Exchange (ETDEWEB)

    McClanahan, Tucker C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Iverson, Erik B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gallmeier, Franz X. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    Short-pulsed sources like the Spallation Neutron Source (SNS) and ISIS produce bursts of neutron pulses at rates of 10-60 Hz, with sub-microsecond proton pulses impacting on high-Z target materials. Moderators are grouped around the target to receive the fast neutrons generated from spallation reactions to moderate them effciently to thermal and sub-thermal energies and to feed narrow neutron pulses to neutron scattering instruments. The scattering instruments use the neutrons as a probe for material investigations, and make use of time-of-flight (TOF) methods for resolving the neutron energy. The energy resolution of scattering instruments depends on the narrow time-structure of the neutron pulses, while neutrons in the long tail of the emission time distributions can degrade the instrument performance and add undesired background to measurements. The SNS neutronics team is investigating a possible source term impacting the background at short-pulsed spallation sources. The ISIS TS2 project claims to have significantly reduced neutron scattering instrument background levels by the elimination or reduction of iron shielding in the target-moderator-reflector assembly. An alternative hypothesis, also proposed by ISIS, suggests that this apparent reduction arises from moving beamline shielding away from the neutron guide channels, reducing albedo down the beamlines. In both hypotheses, the background neutrons in question are believed to be generated by photonuclear reactions. If the background neutrons are indeed generated via photonuclear channels, then they are generated in a time-dependent fashion, since most of the high-energy photons capable of inducing photonuclear production are gone within a few microseconds following the proton pulse. To evaluate this e ect, we have enabled photonuclear reactions in a series of studies for the SNS first target station (FTS) taking advantage of its Monte Carlo model. Using a mixture of ENDF/B VII.0 and TENDL-2014 photonuclear

  15. Charge distribution studies in the fast-neutron-induced fission of sup 2 sup 3 sup 2 Th, sup 2 sup 3 sup 8 U, sup 2 sup 4 sup 0 Pu and sup 2 sup 4 sup 4 Cm

    CERN Document Server

    Naik, H; Iyer, R H

    2003-01-01

    Charge distribution studies for heavy-mass fission products were carried out in the fast-neutron-induced fission of sup 2 sup 3 sup 2 Th, sup 2 sup 3 sup 8 U, sup 2 sup 4 sup 0 Pu and sup 2 sup 4 sup 4 Cm using radiochemical and gamma-ray spectrometric techniques. The width parameter(sigma sub Z /sigma sub A), the most probable charge/mass (Z sub P /A sub P), the charge polarization (DELTA Z) and the slope of charge polarization [ delta(DELTA Z)/delta A sup '] as a function of the fragment mass (A sup ') were deduced. The average charge dispersion parameter (left angle sigma sub Z right angle) and proton odd-even effect (delta sub p) were also obtained for these fissioning systems. The left angle sigma sub Z right angle and delta sub p values in the fissioning systems sup 2 sup 4 sup 1 Pu sup * and sup 2 sup 4 sup 5 Cm sup * were determined for the first time. The delta(DELTA Z)/delta A sup ' value is also determined for the first time in the fissioning systems sup 2 sup 3 sup 9 U sup * , sup 2 sup 4 sup 1 Pu...

  16. Optical fiber transmission of radar RF pulse with stable time delay based on wavelength control%基于波长控制的雷达射频脉冲稳时光纤传输方案

    Institute of Scientific and Technical Information of China (English)

    乔宁; 余岚; 钟炎平

    2015-01-01

    In view of the problem of transmission time delay being unstable between the passive radar system stations with the time difference of arrival (TDOA) location, this paper proposes an optical fiber transmission scheme of radar RF pulse with stable time delay based on the wavelength control. The relations between the trans-mission time delay of optical links and the wavelength of the lasers are analyzed theoretically, firstly, the method of stabilizing the time delay by changing the lasers’wavelength proposed next, and finally, the simulations to this proposed scheme performed. Simulation results show that this proposed scheme can make the peak-to-peak value of time delay fluctuations lower than 374ps, which meets the stability requirement for transmission time delay in TDOA passive radar system.%针对时差定位的无源雷达系统站间传输时延不稳定问题,提出了一种基于波长控制的雷达射频脉冲稳时光纤传输方案.首先理论分析了光纤链路的传输时延和激光器波长之间的关系,然后提出了通过改变激光器波长稳定传输时延的方法,最后对所提方案进行了仿真.仿真结果表明,该方案能使传输时延波动的峰-峰值小于374 ps.满足了时差定位的无源雷达系统对传输时延稳定性的要求.

  17. Fiber transmission and generation of ultrawideband pulses by direct current modulation of semi-conductor lasers and chirp-to-intensity conversion

    DEFF Research Database (Denmark)

    Company Torres, Victor; Prince, Kamau; Tafur Monroy, Idelfonso

    2008-01-01

    Optical pulses generated by current modulation of semiconductor lasers are strongly frequency chirped. This effect has been considered pernicious for optical communications. We take advantage of this effect for the generation of ultrawideband microwave signals by using an optical filter to achieve...... chirp-to-intensity conversion. We also experimentally achieve propagation through a 20 km nonzero dispersion shifted fiber with no degradation of the signal at the receiver. Our method constitutes a prospective low-cost solution and offers integration capabilities with fiber...

  18. Low-background detection of fission neutrons produced by pulsed neutron interrogation

    Science.gov (United States)

    Ruddy, Frank H.; Flammang, Robert W.; Seidel, John G.

    2009-01-01

    Measurements designed to detect shielded Special Nuclear Materials (SNM) have been carried out using a pulsed 8.5-MeV neutron source. Fission-neutron counts were detected as a function of time in the intervals between 100-μs neutron bursts at burst frequencies of 500, 1000, and 2000 Hz. The pulse timing sequences were chosen to optimize detection of fission neutrons produced by thermal-neutron-induced fission in the SNM. Fission neutrons were detected directly as proton, carbon, and silicon recoils in silicon carbide (SiC) semiconductor fast neutron detectors. SiC detectors recorded neutron counts during and immediately following the source neutron bursts, allowing detection of fission neutrons with short (120 μs) die-away times. The SiC detectors demonstrated excellent background discrimination with more than 2000 neutron counts observed in time intervals where zero background counts were detected.

  19. Pulse Control and Bifurcation Analysis of a SIRS Epidemic Model with Vertical Transmission%具垂直传染的SIRS传染病模型的脉冲控制和分岔分析

    Institute of Scientific and Technical Information of China (English)

    郝丽杰; 蒋贵荣; 鹿鹏

    2012-01-01

    In this paper,the dynamical behavior of a SIRS epidemic model with birth pulse,pulse vaccination and vertical transmission are studied. The condition of existence for supercritical bifurcation is derived,and then the threshold for a disease to be extinct or endemic is established. The Poincare map and center manifold theorem are used to discuss flip bifurcation of endemic periodic solution. Numerical results for periodic solutions and bifurcation diagrams,which are illustrated with an example,are in good agreement with the theoretical analysis.%本文研究一个具有脉冲生育、脉冲接种和垂直传染的SIRS传染病模型的动力学行为,给出超临界分岔发生的条件,得到了疾病流行与否的阈值.通过利用Poincaré映射和中心流形定理,讨论了地方病周期解的flip分岔,并给出能验证理论分析的数值结果.

  20. Control of high power pulse extracted from the maximally compressed pulse in a nonlinear optical fiber

    CERN Document Server

    Yang, Guangye; Jia, Suotang; Mihalache, Dumitru

    2013-01-01

    We address the possibility to control high power pulses extracted from the maximally compressed pulse in a nonlinear optical fiber by adjusting the initial excitation parameters. The numerical results show that the power, location and splitting order number of the maximally compressed pulse and the transmission features of high power pulses extracted from the maximally compressed pulse can be manipulated through adjusting the modulation amplitude, width, and phase of the initial Gaussian-type perturbation pulse on a continuous wave background.

  1. Fast neutron spectrum in the reflector of swimming pool reactor behind metallics slabs; Spectre des neutrons rapides dans le reflecteur d'une pile a eau legere derriere des ecrans metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Brousse, J.C. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-07-01

    The large perturbations of fast neutron spectrum were measured behind lead, aluminium and iron slabs in the Siloette reflector at the CENG. The neutron slowing down is chiefly depending of the inelastic reaction. The reaction cross section increases with energy; a spectrum softening is deduced. This is verified. We tried to determine the spectrum shape by calculation to fit the measurements. Calculations were firstly made in unidimensional geometry by the NIOBE transport equation resolution code and by the SANE Monte-Carlo code. The results does not agree with the experimental determined values. Finally a semi-empirical method for studying a tridimensional geometry was chosen. We have obtained calculation results in a perfect agreement with measurements. The method is described. (author) [French] Les experiences realisees dans le reflecteur de la pile a eau legere SILOETTE du CENG avec des ecrans de plomb, d'aluminium et de fer, nous ont permis de caracteriser les deformations importantes du spectre des neutrons rapides par ces materiaux. Nous avons verifie que la loi de ralentissement preponderante est la reaction de diffusion inelastique dont la section efficace croit avec l'energie, ce qui entraine un amollissement du spectre. Nous avons cherche a determiner par le calcul la trace des spectres de neutrons rapides correspondant aux points de mesure. Les premiers calculs effectues en geometrie unidimensionnelle a l'aide d'un code de resolution de l'equation du transport (NIOBE) et d'un code de Monte-Carlo (SANE) nous ont donne des resultats imparfaits. On a alors choisi une methode de calcul approche capable d'etudier une geometrie tridimensionnelle. Cette methode nous a donne des resultats de calcul qui s'approchaient a quelques pour cent des resultats experimentaux. La methode est decrite. (auteur)

  2. Study of the propagation of fast neutrons in water, by Monte-Carlo methods; Etude de la propagation des neutrons rapides dans l'eau par des methodes de Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Lafore, P.; Lattes, R.; Millot, J.P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    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)Fren. [French] Nous etudions la propagation dans l'eau des neutrons a partir de sources planes monodirectionnelles dont les energies sont repartis de 300 keV a 19,66 MeV, placees dans un milieu infini d'eau. Nous determinons les trajectoires exactes d'un certain nombre de neutrons en tenant compte des sections microscopiques, en supposant que les chocs inelastiques des neutrons sur l'oxygene sont des absorptions, et en negligeant la perte d'energie par chocs elastiques sur l'oxygene. Les vies de neutrons ont ete exploitees pour etudier la propagation des neutrons a partir de sources de fission, Po-Be, Po-B et Ra-Be, ainsi que la reflexion des neutrons rapides sur un milieu semi-infini d'eau. On a tenu compte integralement du premier choc pour ameliorer la precision des resultats. Les calculs ont ete effectues par Mme J. VASSEUR et M.A. GUILLOU. (auteur)

  3. Pulse distortion in single-mode fibers. 3: Chirped pulses.

    Science.gov (United States)

    Marcuse, D

    1981-10-15

    The theory of pulse distortion in single-mode fibers is extended to include laser sources that suffer a linear wavelength sweep (chirp) during the duration of the pulse. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the chirp on the shape and rms width of the pulse. A somewhat paradoxical situation exists. A given input pulse can be made arbitrarily short by a sufficiently large amount of chirping, and, after a given fiber length, this chirped pulse returns to its original width. But at this particular distance an unchirped pulse would be only [equiation] times longer. Thus chirping can improve the rate of data transmission by only 40%.

  4. Determination of inlet transmission and conversion efficiencies for in situ measurements of the nocturnal nitrogen oxides, NO3, N2O5 and NO2, via pulsed cavity ring-down spectroscopy.

    Science.gov (United States)

    Fuchs, Hendrik; Dubé, William P; Ciciora, Steven J; Brown, Steven S

    2008-08-01

    Pulsed cavity ring-down spectroscopy is a highly sensitive method for direct absorption spectroscopy that has been applied to in situ detection of NO3, N2O5 and NO2 in the atmosphere from a variety of platforms, including ships, aircraft, and towers. In this paper, we report the development of schemes to significantly improve the accuracy of these measurements. This includes the following: (1) an overall improvement in the inlet transmission efficiencies (92 +/- 2% for NO3 and 97 +/- 1% for N2O5) achieved primarily through a reduction in the inlet residence time; and (2) the development of a calibration procedure that allows regular determination of these efficiencies in the field by addition of NO3 or N2O5 to the inlet from a portable source followed by conversion of NO3 to NO2. In addition, the dependence of the instrument's sensitivity and accuracy to a variety of conditions encountered in the field, including variations in relative humidity, aerosol loading, and VOC levels, was systematically investigated. The rate of degradation of N2O5 transmission efficiency on the inlet and filter system due to the accumulation of inorganic aerosol was determined, such that the frequency of filter changes required for accurate measurements could be defined. In the absence of aerosol, the presence of varying levels of relative humidity and reactive VOC were found to be unimportant factors in the instrument's performance. The 1 sigma accuracy of the NO3, N2O5, and NO2 measured with this instrument are -9/+12, -8/+11, +/- 6%, respectively, where the -/+ signs indicate that the actual value is low/high relative to the measurement. The largest contribution to the overall uncertainty is now due to the NO3 absorption cross section rather than the inlet transmission efficiency.

  5. A wide-band measurement method for transmission coefficients based on pulse compression technique%基于脉冲压缩技术的宽带透射系数测量方法

    Institute of Scientific and Technical Information of China (English)

    于盛齐; 黄益旺; 吴琼

    2013-01-01

    Transmission coefficient is one of the most significant parameters of underwater acoustic materials. In order to measure a transmission coefficient in a tank, a method based on pulse compression technique was proposed. With it, a directive wave was extracted from a compressed signal. The method could overcome unavoidable multi-path disturbance in tests, and easily obtain transmission coefficients for all the frequencies in the measured frequency band simultaneously, i. e. , a wide-band measurement was realized. This method was verified through comparison between the results of narrow and wide-band measurements of a glass box, they were conducted in the frequency range of 20 ~60 kHz in a tank.%透射系数是水声材料的一项重要声学参数,为在水池中对水声材料的透射系数进行测量,提出基于脉冲压缩技术的测量方法,对接收信号进行压缩提取直达波.该方法不仅能克服实验过程中经常遇到的多途干扰,且测量过程简单,可同时获得测量频带内所有频点的透射系数,实现对透射系数的宽带测量.在水池环境下,通过对20 ~60 kHz频率范围内玻璃缸的窄带测量与宽带测量结果比较,验证该方法的有效性.

  6. 不可控12脉波整流的输电线路直流融冰研究%Study on DC De-icing Method Based on Uncontrollable 12-Pulse Rectification for Transmission Line

    Institute of Scientific and Technical Information of China (English)

    罗小龙; 廖振; 彭峰; 郭浩; 胡晓羲

    2012-01-01

    在覆冰输电线路的融冰方法中,与传统的交流融冰法和机械除冰法相比,直流融冰法具有所需电源容量小、高效、方便等优势。研究了采用不可控12脉波整流的直流融冰方法,分析了不可控12脉波整流直流融冰原理,在确定相应型号导线融冰电流的基础上,计算出实现导线融冰所需的融冰电压和交流侧电压,并由此确定整流变压器的额定电压比,分别推导出上下整流桥串/并联两种接线方式条件下覆冰导线的可融长度。仿真结果表明,该方法在不同型号导线的一定长度范围内具有良好的融冰效果,为解决输电线路覆冰问题提供了一种可靠技术。%In many de-icing methods for icing transmission lines, DC de-icing method has many advantages when it is compared to the traditional AC or artificial de-icing method, such as smaller power supply capacity, higher efficiency and convenience. This paper studies a DC de-icing method which is based on uncontrollable 12 pulse rectifier. It analyzes DC de-icing principle of uncontrollable 12 pulse rectification. According to the de-icing current of a given conductor, the AC side voltage and the DC de-icing voltage, which could make the ice covering on the conductor de-iced, will be calculated. Then the rated voltage ratio of rectifying transformer can be easily determined, and the icing conductor's de-icing range is deduced by making the two rectifier bridges connected in series and in parallel. Simulation shows that this method is really efficient to de-ice the ice covering on the transmission line in a certain range. It provides a reliable technology for solving the problem of icing transmission lines.

  7. Epidemiological Characteristics and Clinical Treatment Outcome of Typhoid Fever in Ningbo, China, 2005-2014: Pulsed-Field Gel Electorophoresis Results Revealing Great Proportion of Common Transmission Sources.

    Science.gov (United States)

    Song, Qifa; Yang, Yuanbin; Lin, Wenping; Yi, Bo; Xu, Guozhang

    2017-09-25

    We aimed to describe the molecular epidemiological characteristics and clinical treatment outcome of typhoid fever in Ningbo, China during 2005-2014. Eighty-eight Salmonella Typhi isolates were obtained from 307 hospitalized patients. Three prevalent pulsed-field gel electrophoresis (PFGE) patterns of 54 isolates from 3 outbreaks were identified. Overall, there were 64 (72.7%) isolates from clustered cases and 24 (27.3%) isolates from sporadic cases. Resistance to nalidixic acid (NAL) (n = 47; 53.4%) and ampicillin (AMP) (n = 40; 45.4%) and rare resistance to tetracycline (TET) (n = 2; 2.3%) and gentamicin (GEN) (n = 2; 2.3%) were observed. No isolates resistant to cefotaxime (CTX), chloramphenicol (CL), ciprofloxacin (CIP), and trimethoprim-sulfamethoxazole (SXT) were found. The occurrence of reduced sensitivity to CIP was 52.3% (n = 46). The medians of fever clearance time in cases with and without complications were 7 (interquartile range (IQR): 4-10) and 5 (IQR: 3-7) days (P = 0.001), respectively, when patients were treated with CIP or levofloxacin (LEV) and/or third-generation cephalosporins (CEP). Rates of serious complications were at low levels: peritonitis (2.3%), intestinal hemorrhage (6.8%), and intestinal perforation (1.1%). The present study revealed a long-term clustering trend with respect to PFGE patterns, occasional outbreaks, and the rapid spread of AMP resistance and decreased CIP susceptibility among S. Typhi isolates in recent years.

  8. Transmission electron microscopy study of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} films induced by an ultraviolet single-pulse laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.J. [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Liu, F.R., E-mail: Liufr@bjut.edu.cn [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Han, X.X.; Zhu, Z. [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Lin, X.; Liu, F. [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 10072 (China); Sun, N.X. [Electrical and Computer Engineering Department, Northeastern University, MA 02115 (United States)

    2014-08-30

    Highlights: • Crystalline grains are plate grains for 30 nm films upon UV laser irradiation. • Crystalline colonies growth method is similar to the dendrite growth for 30 nm films. • Increasing film thickness will decrease grain size if laser fluences are the same. • Increasing laser fluence can significantly promote crystalline grain growth. • Possible crystallization processes are analyzed based on a crystallization model. - Abstract: Crystallization behaviors of α-GST films with the thickness of 80 and 30 nm induced by an ultraviolet pulse laser were investigated by using TEM integrated with SAED. Firstly, crystalline phase morphologies were shown and analyzed. Both plate grains and spherical grains were found for 80 nm thick film, while only plate grains were found for 30 nm thick film. Then the relationship between the grain size and laser fluence for the 80 nm thick film was studied and the effects of film thickness on crystallization morphology were analyzed. Finally a crystallization process model based on the relationship of the crystallization starting temperature and heating temperature was constructed to elucidate how the solid-phase crystallization and melt-cooling crystallization occurred and developed. It also unified the crystallization starting temperature under static conditions and the crystallization starting temperature under laser inducing conditions.

  9. Petawatt pulsed-power accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Stygar, William A. (Albuquerque, NM); Cuneo, Michael E. (Albuquerque, NM); Headley, Daniel I. (Albuquerque, NM); Ives, Harry C. (Albuquerque, NM); Ives, legal representative; Berry Cottrell (Albuquerque, NM); Leeper, Ramon J. (Albuquerque, NM); Mazarakis, Michael G. (Albuquerque, NM); Olson, Craig L. (Albuquerque, NM); Porter, John L. (Sandia Park, NM); Wagoner; Tim C. (Albuquerque, NM)

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  10. Spectral unfolding of fast neutron energy distributions

    Science.gov (United States)

    Mosby, Michelle; Jackman, Kevin; Engle, Jonathan

    2015-10-01

    The characterization of the energy distribution of a neutron flux is difficult in experiments with constrained geometry where techniques such as time of flight cannot be used to resolve the distribution. The measurement of neutron fluxes in reactors, which often present similar challenges, has been accomplished using radioactivation foils as an indirect probe. Spectral unfolding codes use statistical methods to adjust MCNP predictions of neutron energy distributions using quantified radioactive residuals produced in these foils. We have applied a modification of this established neutron flux characterization technique to experimentally characterize the neutron flux in the critical assemblies at the Nevada National Security Site (NNSS) and the spallation neutron flux at the Isotope Production Facility (IPF) at Los Alamos National Laboratory (LANL). Results of the unfolding procedure are presented and compared with a priori MCNP predictions, and the implications for measurements using the neutron fluxes at these facilities are discussed.

  11. 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.

  12. Digital Acquisition Development for Fast Neutron Detectors

    Science.gov (United States)

    Seagren, T.; Mosby, S.; Mona Collaboration; Lansce P-27 Team

    2015-10-01

    The use of the Modular Neutron Array (MoNA) at FRIB requires a thorough understanding of how neutrons propagate through the array. This leads to the increasing importance of accuracy in detector response simulations, particularly in the case of FRIB's higher beam energies. An upcoming experiment at the LANSCE facility at Los Alamos National Lab will benchmark neutron propagation through the MoNA array and provide a more complete validation of the simulation software. LANSCE also hosts the Chi-Nu experiment, which seeks to measure fission output neutrons using the high-intensity neutron beams there. In both experiments, the instantaneous rate on the detectors involved is expected to be very high, due to the LANSCE/WNR beam structure. Therefore, waveform digitizers with on-board processing are required in order for the experiments to succeed. These digitizers provide on-board timing algorithms using FPGA firmware, and several tests were preformed in order to determine what the optimal timing filter settings were for a variety of detectors, including the plastic and liquid scintillators to be used in MoNA and Chi-Nu respectively. This work will inform the execution of the MoNA and Chi-Nu experiments at LANSCE. The details of the methods used and results will be presented. Supported by funding through Los Alamos National Lab and NSF Grant PHY-1506402.

  13. 快中子辐射诱变对绿色木霉产纤维素酶的影响%Effect of Fast Neutron Irradiation on Production of Cellulase from Trichoderma viride

    Institute of Scientific and Technical Information of China (English)

    陈光; 徐杨; 孙旸; 刘洁心; 王香琪

    2011-01-01

    The effect of deuterium ion bombardment majority targeted to produce 14Mev fast neutron irradiation, with dosage 0.6—4.8Gy, on production of cellulose from Trichoderma viride AS3.3711 was studied. The death rate was in a rising trend when irradiation dosage was 0.6—4.8 Gy. The results indicated the death rate of spores reached 80.0 % when radiation dosage was 1.2 Gy. It was shown that one positive mutant had significant difference compared to the original with paired samples test (t-test). The filter paper activity of cellulase of strain Fnl0 - 1 reached 633.63 U/mL, with 4 times enhanced, compared with the initial strain. And the CMC activity of cellulase of strain Fnl0 - 1 reached 914.4 U/mL,with 30 times enhanced, compared with the initial strain.%利用快中子对绿色木霉AS3.3711进行辐照,辐照剂量为0.6~4.8 Gy.研究不同剂量快中子对绿色木霉孢子致死率和遗传稳定性的影响,得到了提高纤维素酶活性的菌株.结果表明:辐照剂量在0.6~4.8 Gy 范围内绿色木霉的致死率呈逐渐上升趋势,辐照剂量为1.2 Gy时,绿色木霉的致死率达到80.0%,此突变株的羧甲基纤维素酶活(CMC酶活)可达914.4 U/mL,比出发菌株提高了30倍,滤纸酶活(FPA酶活)为633.63 U/mL,比出发菌株提高了4倍.

  14. Pulse subtraction Doppler

    Science.gov (United States)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

  15. Measurement of the Ratio of High Energy Neutron in the Pulse Nuclear Reactor

    Institute of Scientific and Technical Information of China (English)

    MAO; Guo-shu; DING; You-qian; YANG; Lei; MA; Peng; YU; Zhen-hua

    2012-01-01

    <正>In the production of radioisotopes and neutron activation analysis, the fast neutron densities are very important to estimate the yields of the radioisotopes. In order to determine the fast neutron flux ratio, different foils are used to measure the thermal neutron flux and the fast neutron flux. In this paper 238U was used as only a monitor to measure the ratio of high energy neutron (>6 MeV). By measuring the

  16. 不同频率和脉宽的方波激励下无线电能传输效果分析%Effect Analysis of Wireless Power Transmission Under Excitation of Square Wave with Different Frequencies and Pulse Widths

    Institute of Scientific and Technical Information of China (English)

    宋显锦; 刘国强; 张超; 张瑞华; 徐小宇

    2015-01-01

    Magnetic resonant wireless power transmission is a new type of technology for conducting non-radiative,mid-range power transmission using the near magnetic field based on resonant coupling phenomena.Many research findings were achieved through calculating the coupling voltage and power with the sinusoidal alternating current as the exciting source.The pulse current can also produce alternating magnetic field which induces the alternating current,and wireless power transmission excited by the pulse current has its own features.The circuit response process and the mechanism of resonant coupling excited by the pulse current are discussed,and the conclusion that the coupling process using pulse excitation is in essence also the sine wave coupling is drawn.With this transmission method,higher power can be transmitted to the load compared with sinusoidal excitation.The transfer effects of pulse waves with different pulse widths are compared by experiment and high-frequency resonant coils can be controlled by low frequency pulse signals,by which even more effective wireless power transfer can be achieved.%磁谐振式无线电能传输技术是基于磁谐振耦合现象利用近区磁场进行非辐射性、中距离输电的新技术。许多结果采用正弦交变电流作为激励,计算耦合电压和传输功率。脉冲激励也可以产生交变磁场从而感生交变电流,此方式下的无线电能传输有其自身特点。文中分析了脉冲激励下的电路响应过程及谐振耦合机理,其耦合过程本质上也是正弦波的耦合。在同一输出电压的情况下,与正弦激励相比,用脉冲方波做激励,负载可以获得较大的传输功率。最后,通过实验比较了几种脉宽和频率不同的方波激励的传输效果。实验结果表明,可以使用低频脉冲信号控制高频谐振线圈,从而实现更为有效的无线电能传输。

  17. Downhole pulse radar

    Science.gov (United States)

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  18. Slow light pulse propagation in dispersive media

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Mørk, Jesper; Lavrinenko, Andrei

    2009-01-01

    -difference-time-domain Maxwell-Bloch simulations and compared to analytic results. For long pulses the group index (transmission) for the combined system is significantly enhanced (reduced) relative to slow light based on purely material or waveguide dispersion. Shorter pulses are strongly distorted and depending on parameters......We present a theoretical and numerical analysis of pulse propagation in a semiconductor photonic crystal waveguide with embedded quantum dots in a regime where the pulse is subjected to both waveguide and material dispersion. The group index and the transmission are investigated by finite...... broadening or break-up of the pulse may be observed. The transition from linear to nonlinear pulse propagation is quantified in terms of the spectral width of the pulse. To cite this article: T.R. Nielsen et al., C. R. Physique 10 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All...

  19. Optical pulses, lasers, measuring techniques

    CERN Document Server

    Früngel, Frank B A

    1965-01-01

    High Speed Pulse Technology: Volume II: Optical Pulses - Lasers - Measuring Techniques focuses on the theoretical and engineering problems that result from the capacitor discharge technique.This book is organized into three main topics: light flash production from a capacitive energy storage; signal transmission and ranging systems by capacitor discharges and lasers; and impulse measuring technique. This text specifically discusses the air spark under atmospheric conditions, industrial equipment for laser flashing, and claims for light transmitting system. The application of light impulse sign

  20. The System of Nanosecond 280-keV-He+ Pulsed Beam

    CERN Document Server

    Junphong, Pimporn; Lekprasert, Banyat; Suwannakachorn, Dusadee; Thongnopparat, N; Vilaithong, Thiraphat; Wiedemann, Helmut

    2005-01-01

    At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a t...

  1. Compilation of the ``Atlas of Gamma-rays from the Inelastic Scattering of Reactor Fast Neutrons'' (1978DE41) by A.M. Demidov, L.I. Govor, Yu. K. Cherepantsev, M.R. Ahmed, S. Al-Najjar, M.A. Al-Amili, N. Al-Assafi, and N. Rammo

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, Aaron M. [Univ. of California, Berkeley, CA (United States); Bernstein, Lee A. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chong, Su-Ann [Univ. of California, Berkeley, CA (United States)

    2017-07-26

    A Structured Query Language (SQL) relational database has been developed based on the original (n,n'gamma) work carried out by A.M. Demidov et al., at the Nuclear Research Institute in Baghdad, Iraq [``Atlas of Gamma-Ray Spectra from the Inelastic Scattering of Reactor Fast Neutrons'', Nuclear Research Institute, Baghdad, Iraq (Moscow, Atomizdat 1978)] for 105 independent measurements comprising 76 elemental samples of natural composition and 29 isotopically-enriched samples. The information from this ATLAS includes: gamma-ray energies and intensities; nuclide and level data corresponding to where the gamma-ray originated from; target (sample) experimental-measurement data. Taken together, this information allows for the extraction of the flux-weighted (n,n'gamma) cross sections for a given transition relative to a defined value. Currently, we are using the fast-neutron flux-weighted partial gamma-ray cross section from ENDF/B-VII.1 for the production of the 847-keV transition from the first excited 2+ state to the 0+ ground state in 56Fe, 468 mb. This value also takes into account contributions to the 847-keV transition following beta(-) decay of 56Mn formed in the 56Fe(n,p) reaction. However, this value can easily be adjusted to accommodate the user preference. The (n,n'gamma) data has been compiled into a series of ASCII comma separated value tables and a suite of Python scripts and C modules are provided to build the database. Upon building, the database can then be interacted with directly via the SQLite engine or accessed via the Jupyter Notebook Python-browser interface. Several examples exploiting these utilities are also provided with the complete software package.

  2. Transmission eigenvalues

    Science.gov (United States)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  3. Pulse Voltammetry.

    Science.gov (United States)

    Osteryoung, Janet

    1983-01-01

    Discusses the nature of pulse voltammetry, indicating that its widespread use arises from good sensitivity and detection limits and from ease of application and low cost. Provides analytical and mechanistic applications of the procedure. (JN)

  4. Ultrafast optomechanical pulse picking

    Science.gov (United States)

    Lilienfein, Nikolai; Holzberger, Simon; Pupeza, Ioachim

    2017-01-01

    State-of-the-art optical switches for coupling pulses into and/or out of resonators are based on either the electro-optic or the acousto-optic effect in transmissive elements. In high-power applications, the damage threshold and other nonlinear and thermal effects in these elements impede further improvements in pulse energy, duration, and average power. We propose a new optomechanical switching concept which is based solely on reflective elements and is suitable for switching times down to the ten-nanosecond range. To this end, an isolated section of a beam path is moved in a system comprising mirrors rotating at a high angular velocity and stationary imaging mirrors, without affecting the propagation of the beam thereafter. We discuss three variants of the concept and exemplify practical parameters for its application in regenerative amplifiers and stack-and-dump enhancement cavities. We find that optomechanical pulse picking has the potential to achieve switching rates of up to a few tens of kilohertz while supporting pulse energies of up to several joules.

  5. 100 Gb/s single VCSEL data transmission link

    DEFF Research Database (Denmark)

    Rodes Lopez, Roberto; Estaran Tolosa, Jose Manuel; Li, Bomin

    2012-01-01

    100 Gb/s optical fiber transmission link with a single 1.5 um VCSEL has been experimentally demonstrated using 4-level pulse amplitude modulation.......100 Gb/s optical fiber transmission link with a single 1.5 um VCSEL has been experimentally demonstrated using 4-level pulse amplitude modulation....

  6. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  7. The Soliton Transmissions in Optical Fibers

    Directory of Open Access Journals (Sweden)

    Leos Bohac

    2010-01-01

    Full Text Available The objective of this paper is to familiarize readers with the basic analytical propagation model of short optical pulses in optical fiber. Based on this model simulation of propagation of the special type of pulse, called a soliton, will be carried out. A soliton transmission is especially attractive in the fiber optic telecommunication systems as it does not change a pulses shape during propagating right-down the fiber link to the receiver. The model of very short pulse propagation is based on the numerical solution of the nonlinear Schroedinger equation (NLSE, although in some specific cases it is possible to solve it analytically.

  8. 基于C8051F120的透射式脉搏血氧仪的设计%Design of transmission pulse oximeter based on C8051F120

    Institute of Scientific and Technical Information of China (English)

    方启超; 周严

    2013-01-01

    Pulse oximeter plays an important role in clinical practice because of it's continuous, non-invasive, rapid and accurate monitoring for the human arterial oxygen saturation and heart rate. This paper introduces the hardware and software design which based on the Lambert-Beer law, choice the adult finger clip Spo2 probe format the system of microcontroller,complete the detection of the arterial oxygen saturation. Six people use the designed pulse oximeter to measure the oxygen saturation, the test results show that the pulse oximeter has met the design requirements and complete the expected functionality, the results show that the oximeter measurement of the arterial oxygen saturation and pulse rate values accurate,the pulse waveform is available.%脉搏血氧仪具有连续、无创、快速、准确监测人体动脉血氧饱和度和心率的功能,在临床上具有重要作用.以朗伯比尔定律为理论基础,采用成人指夹式血氧探头为传感器,以C8051F120单片机组建微处理器系统,进行了血样检测的软硬件设计,实现了血氧饱和度检测.使用设计的脉搏血氧仪对6名受试者进行血氧测试,结果表明该血氧仪测量的血氧饱和度值和脉率值准确,脉搏波波形可用.

  9. High-speed pulse techniques

    CERN Document Server

    Coekin, J A

    1975-01-01

    High-Speed Pulse Techniques covers the many aspects of technique in digital electronics and encompass some of the more fundamental factors that apply to all digital systems. The book describes the nature of pulse signals and their deliberate or inadvertent processing in networks, transmission lines and transformers, and then examines the characteristics and transient performance of semiconductor devices and integrated circuits. Some of the problems associated with the assembly of these into viable systems operating at ultra high speed are also looked at. The book examines the transients and w

  10. HIV Transmission

    Science.gov (United States)

    ... Abroad Treatment Basic Statistics Get Tested Find an HIV testing site near you. Enter ZIP code or city Follow HIV/AIDS CDC HIV CDC HIV/AIDS See RSS | ... on HIV Syndicated Content Website Feedback HIV/AIDS HIV Transmission Language: English (US) Español (Spanish) Recommend ...

  11. Ultrasonic Pulse Propagation in Constant-Group-Velocity Media.

    Science.gov (United States)

    1982-06-01

    Results are presented of calculations made of distortion experienced by ultrasonic pulses in transmission through dispersive constant-group-velocity media, and the effects that it may have on velocity measurements. Three types of pulses were considered; a pulsed sine wave of constant amplitude, a pulsed sine wave with amplitude varying as sine-squared, and a rectangular pulse. It is shown that the individual waves in the pulsed sine waves move with the phase velocity of a continuous wave, and the envelope moves with the group velocity

  12. Pulsed thermoelectricity

    Science.gov (United States)

    Apostol, M.; Nedelcu, M.

    2010-07-01

    A special mechanism of thermoelectric transport is described, consisting of pulses of charge carriers which "fly" periodically through the external circuit from the hot end of the sample to the cold end, with a determined duration of the "on" and "off" times of the electric contacts, while maintaining continuously the thermal contacts. It is shown that such a "resonant" ideal thermogenerator may work cyclically, with the same efficiency quotient as the ideal efficiency quotient of the thermoelectric devices operated in the usual stationary transport regime but the electric flow and power are increased, as a consequence of the concentration of the charge carriers on pulses of small spatial extent. The process is reversible, in the sense that it can be operated either as a thermoelectric generator or as an electrothermal cooler.

  13. Pulse shape discrimination of Cs2LiYCl6:Ce3+ detectors at high count rate based on triangular and trapezoidal filters

    Science.gov (United States)

    Wen, Xianfei; Enqvist, Andreas

    2017-09-01

    Cs2LiYCl6:Ce3+ (CLYC) detectors have demonstrated the capability to simultaneously detect γ-rays and thermal and fast neutrons with medium energy resolution, reasonable detection efficiency, and substantially high pulse shape discrimination performance. A disadvantage of CLYC detectors is the long scintillation decay times, which causes pulse pile-up at moderate input count rate. Pulse processing algorithms were developed based on triangular and trapezoidal filters to discriminate between neutrons and γ-rays at high count rate. The algorithms were first tested using low-rate data. They exhibit a pulse-shape discrimination performance comparable to that of the charge comparison method, at low rate. Then, they were evaluated at high count rate. Neutrons and γ-rays were adequately identified with high throughput at rates of up to 375 kcps. The algorithm developed using the triangular filter exhibits discrimination capability marginally higher than that of the trapezoidal filter based algorithm irrespective of low or high rate. The algorithms exhibit low computational complexity and are executable on an FPGA in real-time. They are also suitable for application to other radiation detectors whose pulses are piled-up at high rate owing to long scintillation decay times.

  14. Pulsed Power Driven Fusion Energy

    Energy Technology Data Exchange (ETDEWEB)

    SLUTZ,STEPHEN A.

    1999-11-22

    Pulsed power is a robust and inexpensive technology for obtaining high powers. Considerable progress has been made on developing light ion beams as a means of transporting this power to inertial fusion capsules. However, further progress is hampered by the lack of an adequate ion source. Alternatively, z-pinches can efficiently convert pulsed power into thermal radiation, which can be used to drive an inertial fusion capsule. However, a z-pinch driven fusion explosion will destroy a portion of the transmission line that delivers the electrical power to the z-pinch. They investigate several options for providing standoff for z-pinch driven fusion. Recyclable Transmission Lines (RTLs) appear to be the most promising approach.

  15. Production of fast neutrons from deuteron beams in view of producing radioactive heavy ions beams; Etude de la production de neutrons rapides a partir de faisceaux de deutons en vue de la mise en oeuvre de faisceaux d'ions lourds radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Pauwels, N

    2000-11-01

    This thesis is part of two research and development programmes for the study of neutron rich radioactive nuclear beam production. The technique is based on the ISOL method and can be summarized as follows. Fast neutrons are generated by the break-up of deuterons in a thick target. These neutrons irradiate a fissionable {sup 238}U target. The resulting fission products are extracted from the target, ionised, mass selected and post-accelerated. The aim of the thesis is to study the neutron angular and energetic distributions. After a bibliographical research to justify the choice of deuterons as the best projectile, we developed more specifically three points: - the extension of the activation detector method for neutron spectroscopy to a wide energy range (1 to 150 MeV), - the experimental measurement of neutron angular and energetic distributions produced by deuterons on thick targets. The deuteron energy ranges from 17 to 200 MeV and the thick targets were Be, C and U, - the realization of a code based on Serber's theory to predict the neutron distribution for any couple (deuteron energy-thick target). We conclude that for our application the most suitable target is C and the best deuteron energy is about 100 MeV. (author)

  16. Study of Associated α Particle Imaging Technique for Explosives Detection

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The explosive detecting technique about neutron mainly include the thermal neutron analysis (TNA), the fast neutron analysis (FNA), the pulse fast and thermal neutron analysis (PFTNA) and the associated α particle imaging technique about fast neutron (API).

  17. An algorithm for charge-integration, pulse-shape discrimination and estimation of neutron/photon misclassification in organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Polack, J.K., E-mail: kpolack@umich.edu [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Flaska, M. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Enqvist, A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Sosa, C.S.; Lawrence, C.C.; Pozzi, S.A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2015-09-21

    Organic scintillators are frequently used for measurements that require sensitivity to both photons and fast neutrons because of their pulse shape discrimination capabilities. In these measurement scenarios, particle identification is commonly handled using the charge-integration pulse shape discrimination method. This method works particularly well for high-energy depositions, but is prone to misclassification for relatively low-energy depositions. A novel algorithm has been developed for automatically performing charge-integration pulse shape discrimination in a consistent and repeatable manner. The algorithm is able to estimate the photon and neutron misclassification corresponding to the calculated discrimination parameters, and is capable of doing so using only the information measured by a single organic scintillator. This paper describes the algorithm and assesses its performance by comparing algorithm-estimated misclassification to values computed via a more traditional time-of-flight estimation. A single data set was processed using four different low-energy thresholds: 40, 60, 90, and 120 keVee. Overall, the results compared well between the two methods; in most cases, the algorithm-estimated values fell within the uncertainties of the TOF-estimated values.

  18. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  19. Free space optical communication based on pulsed lasers

    Science.gov (United States)

    Drozd, Tadeusz; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek

    2016-12-01

    Most of the current optical data transmission systems are based on continuous wave (cw) lasers. It results from the tendency to increase data transmission speed, and from the simplicity in implementation (straightforward modulation). Pulsed lasers, which find many applications in a variety of industrial, medical and military systems, in this field are not common. Depending on the type, pulsed lasers can generate instantaneous power which is many times greater when compared with cw lasers. As such, they seem to be very attractive to be used in data transmission technology, especially due to the potentially larger ranges of transmission, or in adverse atmospheric conditions where low power cw-lasersbased transmission is no longer feasible. It is also a very practical idea to implement data transmission capability in the pulsed laser devices that have been around and already used, increasing the functionality of this type of equipment. At the Institute of Optoelectronics at Military University of Technology, a unique method of data transmission based on pulsed laser radiation has been developed. This method is discussed in the paper in terms of both data transmission speed and transmission range. Additionally, in order to verify the theoretical assumptions, modules for voice and data transmission were developed and practically tested which is also reported, including the measurements of Bit Error Rate (BER) and performance vs. range analysis.

  20. Bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.