WorldWideScience

Sample records for neutron yields time

  1. Deuterium-tritium neutron yield measurements with the 4.5 m neutron-time-of-flight detectors at NIF.

    Science.gov (United States)

    Moran, M J; Bond, E J; Clancy, T J; Eckart, M J; Khater, H Y; Glebov, V Yu

    2012-10-01

    The first several campaigns of laser fusion experiments at the National Ignition Facility (NIF) included a family of high-sensitivity scintillator∕photodetector neutron-time-of-flight (nTOF) detectors for measuring deuterium-deuterium (DD) and DT neutron yields. The detectors provided consistent neutron yield (Y(n)) measurements from below 10(9) (DD) to nearly 10(15) (DT). The detectors initially demonstrated detector-to-detector Y(n) precisions better than 5%, but lacked in situ absolute calibrations. Recent experiments at NIF now have provided in situ DT yield calibration data that establish the absolute sensitivity of the 4.5 m differential tissue harmonic imaging (DTHI) detector with an accuracy of ± 10% and precision of ± 1%. The 4.5 m nTOF calibration measurements also have helped to establish improved detector impulse response functions and data analysis methods, which have contributed to improving the accuracy of the Y(n) measurements. These advances have also helped to extend the usefulness of nTOF measurements of ion temperature and downscattered neutron ratio (neutron yield 10-12 MeV divided by yield 13-15 MeV) with other nTOF detectors.

  2. Systematics in delayed neutron yields

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1998-03-01

    An attempt was made to reproduce the systematic trend observed in the delayed neutron yields for actinides on the basis of the five-Gaussian representation of the fission yield together with available data sets for delayed neutron emission probability. It was found that systematic decrease in DNY for heavier actinides is mainly due to decrease of fission yields of precursors in the lighter side of the light fragment region. (author)

  3. Diagnostics and equipment for ion temperatures and implosion neutron yields

    International Nuclear Information System (INIS)

    Chen Jiabin; Zheng Zhijian; Peng Hansheng; Wen Shuhuai; Zhang Baohan; Ding Yongkun; Qi Lanying; Chen Ming; Li Chaoguang

    2001-01-01

    Fuel ion temperature is of great importance in the ICF research field. A set of ultra-fast quenched plastic scintillation detector system was fabricated for low yield neutron diagnostic. The detection efficiency and the sensitivity to DT neutrons were scaled using a K-400 accelerator and a pulse neutron tube from Russia with a width 5 - 10 ns, respectively. Its time response functions were calibrated by cosmic ray and implosion neutron separately. Under the conditions of low laser energy so low neutron yield and very limited space, fuel ion temperatures (including implosion neutron yields at the same time) were obtained. The measured ion temperatures for exploding pusher capsules were between 4 keV and 5 keV with errors +-(15 - 25)%. The neutron yields were 5 x 10 8 - 3 x 10 9 for exploding pusher capsules and 1.6 x 10 7 - 3.9 x 10 8 for ablation ones with errors +- (7 - 10)%. Of the six shots of neutron yields calculated, five are in good agreement with authors' experimental results in the range of +- 20%. Not only the heat-conducting mechanism and the effects on implosion of the energy balance of each path of incidence laser, target design, fuel mixture as well as hot electron behavior have been investigated, but also the upgrade level of the laser facility Shengguang II has been tested

  4. Time and Energy Characterization of a Neutron Time of Flight Detector Using a Novel Coincidence Method for Constraining Neutron Yield, Ion Temperature and Liner Density Measurements from MagLIF Experiments

    Science.gov (United States)

    Styron, Jedediah D.

    The focus of this work is the characterization of a typical neutron time-of-flight (NTOF) detector that is fielded on inertial confinement fusion (ICF) experiments conducted at the Z-experimental facility with emphasis on the Magnetized Liner Fusion (MagLIF) concept. An NTOF detector consisting of EJ-228 scintillator and two independent photomultiplier tubes (PMTs), a Hamamatsu-mod 5 and Photek-PMT240, has been characterized in terms of the absolute time and energy response. The characterization was done by measuring single, neutron-induced events in the scintillator by measuring the alpha particle and neutron produced from the D-T reaction in kinematic coincidence. The results of these experiments provided the time dependent instrument response function and the detector sensitivity as a function of applied voltage covering the entire dynamic range of the detector. Historically, impulse response functions have been measured using various photon sources as surrogates for a neutron source. Thus, this measurement using a single hit neutron source results in the most accurate measured response function, which will improve the accuracy of impulse response corrections to the NTOF signals. While this detector has not yet been fielded on any MagLIF experiments, the development of a predictive capability was desired for transferring the measured detector response from the calibration geometry to the more complex Z geometry. As a proof-of-principle, a detailed model of the Z-machine was developed in MCNP6 to correct for geometry issues when transferring the calibration results from a light lab setting to the Z-environment. Representative values for the instrument response function and the sensitivity for the current detectors fielded on MagLIF experiments were convolved with the modeled results. These results were compared with data collected on three previous MagLIF experiments. The comparison shows the model results can be used to constrain three parameters that are

  5. Characterization of plastic scintillators for detection of radioactivity: Light yield, Time decay measurements and Neutron/γ Pulse Shape Discrimination

    International Nuclear Information System (INIS)

    Montbarbon, E.; Pansu, R.B.; Hamel, M.; Coulon, R.

    2015-07-01

    Since Helium-3 shortage, organic scintillators play a major role in neutron detection. CEA LIST decided to focus on plastic scintillators. By definition, a plastic scintillator is a radio-luminescent polymer; this means that it emits light after interaction with an ionizing radiation. A platform was developed to characterize lab-made prepared scintillators and to compare them with commercial scintillators. Three physicochemical criteria are determined with this unique platform. (authors)

  6. Systematics of neutron-induced fission yields

    International Nuclear Information System (INIS)

    Blachot, J.; Brissot, R.

    1983-10-01

    The main characteristics of the mass and charge distributions for thermal neutron induced fission of actinides are reviewed. We show that these distributions can be reasonably reproduced with only 24 data as input. We use a representation where the element yields together with the most probable mass Ap(Z) play the dominant role. The ability of this model to calculate mass yields for the fission of not yet measured actinides is also shown. The influence of the excitation energy of the fissile system on charge and mass distribution is also discussed

  7. Measurements of DT and DD neutron yields by neutron activation on TFTR

    International Nuclear Information System (INIS)

    Barnes, C.W.; Larson, A.R.; LeMunyan, G.

    1995-03-01

    A variety of elemental foils have been activated by neutron fluence from TFTR under conditions with the DT neutron yield per shot ranging from 10 12 to over 10 18 , and with the DT/(DD+DT) neutron ratio varying from 0.5% (from triton burnup) to unity. Linear response over this large dynamic range is obtained by reducing the mass of the foils and increasing the cooling time, all while accepting greatly improved counting statistics. Effects on background gamma-ray lines from foil-capsule-material contaminants, and the resulting lower limits on activation foil mass, have been determined. DT neutron yields from dosimetry standard reactions on aluminum, chromium, iron, nickel, zirconium, and indium are in agreement within the ±9% (one-sigma) accuracy of the measurements; also agreeing are yields from silicon foils using the ACTL library cross-section, while the ENDF/B-V library has too low a cross-section. Preliminary results from a variety of other threshold reactions are presented. Use of the 115 In(n.n') 115m In reaction (0.42 times as sensitive to DT neutrons as DD neutrons) in conjunction with pure-DT reactions allows a determination of the DT/(DD+DT) ratio in trace tritium or low-power tritium beam experiments

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  9. Delayed neutron yield from fast neutron induced fission of sup 2 sup 3 sup 8 U

    CERN Document Server

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

    2001-01-01

    The measurements of the total delayed neutron yield from fast neutron induced fission of sup 2 sup 3 sup 8 U were made. The experimental method based on the periodic irradiation of the fissionable sample by neutrons from a suitable nuclear reaction had been employed. The preliminary results on the energy dependence of the total delayed neutron yield from fission of sup 2 sup 3 sup 8 U are obtained. According to the comparison of experimental data with our prediction based on correlation properties of delayed neutron characteristics, it is concluded that the value of the total delayed neutron yield near the threshold of (n,f) reaction is not a constant.

  10. On the e-linac-based neutron yield

    International Nuclear Information System (INIS)

    Bunatyan, G.G.; Nikolenko, V.G.; Popov, A.B.

    2010-01-01

    We treat neutron generating in high atomic number materials due to the photonuclear reactions induced by the Bremsstrahlung of an electron beam produced by linear electron accelerator (e-linac). The dependence of neutron yield on the electron energy and the irradiated sample size is considered for various sample materials. The calculations are performed without resort to the so-called 'numerical Monte Carlo simulation'. The acquired neutron yields are well correlated with the data asserted in investigations performed at a number of the e-linac-driven neutron sources

  11. Radiogenic neutron yield calculations for low-background experiments

    Science.gov (United States)

    Westerdale, S.; Meyers, P. D.

    2017-12-01

    Nuclear recoil backgrounds are one of the most dangerous backgrounds for many dark matter experiments. A primary source of nuclear recoils is radiogenic neutrons produced in the detector material itself. These neutrons result from fission and (α , n) reactions originating from uranium and thorium contamination. In this paper, we discuss neutron yields from these sources. We compile a list of (α , n) yields for many materials common in low-background detectors, calculated using NeuCBOT (Neutron Calculator Based On TALYS), a new tool introduced in this paper, available at https://github.com/shawest/neucbot. These calculations are compared to computations made using data compilations and SOURCES-4C.

  12. 8-group relative delayed neutron yields for monoenergetic neutron induced fission of 239Pu

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Korolev, G.G.; Roshchenko, V.A.; Tertychnyj, R.G

    2002-01-01

    The energy dependence of the relative yield of delayed neutrons in an 8-group model representation was obtained for monoenergetic neutron induced fission of 239 Pu. A comparison of this data with the available experimental data by other authors was made in terms of the mean half-life of the delayed neutron precursors. (author)

  13. Chain yields from 19.1 MeV neutron-induced fission of 235U

    International Nuclear Information System (INIS)

    Bao Jie; Yang Yi; Liu Yonghui; Feng Jing; Li Ze; Cui Anzhi; Sun Hongqing; Zhang Shengdong; Guo Jingru

    2001-01-01

    Chain yields for 35 mass chains were determined for the fission of 235 U induced by 19.1 MeV neutrons for the first time. Absolute fission rate was monitored with a double fission chamber; fission product activities were measured by HPGe γ-ray spectrometry. Threshold detector method was used to measured the neutron spectrum in order to estimate the fission events induced by break-up neutrons and scattering neutrons from the environment. A mass distribution curve has been obtained

  14. Calibration methodology for proportional counters applied to yield measurements of a neutron burst

    International Nuclear Information System (INIS)

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

    2014-01-01

    This paper introduces a methodology for the yield measurement of a neutron burst using neutron proportional counters. This methodology is to be applied when single neutron events cannot be resolved in time by nuclear standard electronics, or when a continuous current cannot be measured at the output of the counter. The methodology is based on the calibration of the counter in pulse mode, and the use of a statistical model to estimate the number of detected events from the accumulated charge resulting from the detection of the burst of neutrons. The model is developed and presented in full detail. For the measurement of fast neutron yields generated from plasma focus experiments using a moderated proportional counter, the implementation of the methodology is herein discussed. An experimental verification of the accuracy of the methodology is presented. An improvement of more than one order of magnitude in the accuracy of the detection system is obtained by using this methodology with respect to previous calibration methods

  15. Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Čufar, Aljaž, E-mail: aljaz.cufar@ijs.si [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Batistoni, Paola [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044 Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Conroy, Sean [Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Ghani, Zamir [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Lengar, Igor [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Milocco, Alberto; Packer, Lee [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Pillon, Mario [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044 Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Snoj, Luka [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2017-03-01

    At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium–tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle–energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

  16. Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

    Science.gov (United States)

    Čufar, Aljaž; Batistoni, Paola; Conroy, Sean; Ghani, Zamir; Lengar, Igor; Milocco, Alberto; Packer, Lee; Pillon, Mario; Popovichev, Sergey; Snoj, Luka; JET Contributors

    2017-03-01

    At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium-tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle-energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

  17. Neutron emission and fragment yield in high-energy fission

    International Nuclear Information System (INIS)

    Grudzevich, O. T.; Klinov, D. A.

    2013-01-01

    The KRIS special library of spectra and emission probabilities in the decays of 1500 nuclei excited up to energies between 150 and 250 MeV was developed for correctly taking into account the decay of highly excited nuclei appearing as fission fragments. The emission of neutrons, protons, and photons was taken into account. Neutron emission fromprimary fragments was found to have a substantial effect on the formation of yields of postneutron nuclei. The library was tested by comparing the calculated and measured yields of products originating from the fission of nuclei that was induced by high-energy protons. The method for calculating these yields was tested on the basis of experimental data on the thermal-neutroninduced fission of 235 U nuclei

  18. Measurement of neutron yield by 62 MeV proton beam on a thick beryllium target

    Energy Technology Data Exchange (ETDEWEB)

    Osipenko, M., E-mail: osipenko@ge.infn.it [INFN, sezione di Genova, 16146 Genova (Italy); Ripani, M. [INFN, sezione di Genova, 16146 Genova (Italy); Alba, R. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Ricco, G. [INFN, sezione di Genova, 16146 Genova (Italy); Schillaci, M. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Barbagallo, M. [INFN, sezione di Bari, 70126 Bari (Italy); Boccaccio, P. [INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro (Italy); Celentano, A. [Dipartimento di Fisica dell' Università di Genova, 16146 Genova (Italy); Colonna, N. [INFN, sezione di Bari, 70126 Bari (Italy); Cosentino, L.; Del Zoppo, A.; Di Pietro, A. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Esposito, J. [INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro (Italy); Figuera, P.; Finocchiaro, P. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Kostyukov, A. [Moscow State University, Moscow 119992 (Russian Federation); Maiolino, C.; Santonocito, D.; Scuderi, V. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Viberti, C.M. [Dipartimento di Fisica dell' Università di Genova, 16146 Genova (Italy)

    2013-09-21

    The design of a low-power prototype of neutron amplifier recently proposed within the INFN-E project indicated the need for more accurate data on the neutron yield produced by a proton beam with energy of about 70 MeV impinging on a thick beryllium target. Such measurement was performed at the LNS superconducting cyclotron, covering a wide angular range from 0° to 150° and a complete neutron energy interval from thermal to beam energy. Neutrons with energy above 0.5 MeV were measured by liquid scintillators exploiting their time of flight to determine the kinetic energy. For lower energy neutrons, down to thermal energy, a {sup 3}He detector was used. The obtained data are in good agreement with previous measurements at 0° using 66 MeV proton beam, covering neutron energies >10MeV, as well as with measurements at few selected angles using protons of 46, 55 and 113 MeV energy. The present results extend the neutron yield data in the 60–70 MeV beam energy range. A comparison of measured yields to MCNP, FLUKA and Geant4 Monte Carlo simulations was performed.

  19. Measurement of neutron yield by 62 MeV proton beam on a thick beryllium target

    Science.gov (United States)

    Osipenko, M.; Ripani, M.; Alba, R.; Ricco, G.; Schillaci, M.; Barbagallo, M.; Boccaccio, P.; Celentano, A.; Colonna, N.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; Esposito, J.; Figuera, P.; Finocchiaro, P.; Kostyukov, A.; Maiolino, C.; Santonocito, D.; Scuderi, V.; Viberti, C. M.

    2013-09-01

    The design of a low-power prototype of neutron amplifier recently proposed within the INFN-E project indicated the need for more accurate data on the neutron yield produced by a proton beam with energy of about 70 MeV impinging on a thick beryllium target. Such measurement was performed at the LNS superconducting cyclotron, covering a wide angular range from 0° to 150° and a complete neutron energy interval from thermal to beam energy. Neutrons with energy above 0.5 MeV were measured by liquid scintillators exploiting their time of flight to determine the kinetic energy. For lower energy neutrons, down to thermal energy, a 3He detector was used. The obtained data are in good agreement with previous measurements at 0° using 66 MeV proton beam, covering neutron energies >10 MeV, as well as with measurements at few selected angles using protons of 46, 55 and 113 MeV energy. The present results extend the neutron yield data in the 60-70 MeV beam energy range. A comparison of measured yields to MCNP, FLUKA and Geant4 Monte Carlo simulations was performed.

  20. Measurement of neutron yield by 62 MeV proton beam on a thick beryllium target

    International Nuclear Information System (INIS)

    Osipenko, M.; Ripani, M.; Alba, R.; Ricco, G.; Schillaci, M.; Barbagallo, M.; Boccaccio, P.; Celentano, A.; Colonna, N.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; Esposito, J.; Figuera, P.; Finocchiaro, P.; Kostyukov, A.; Maiolino, C.; Santonocito, D.; Scuderi, V.; Viberti, C.M.

    2013-01-01

    The design of a low-power prototype of neutron amplifier recently proposed within the INFN-E project indicated the need for more accurate data on the neutron yield produced by a proton beam with energy of about 70 MeV impinging on a thick beryllium target. Such measurement was performed at the LNS superconducting cyclotron, covering a wide angular range from 0° to 150° and a complete neutron energy interval from thermal to beam energy. Neutrons with energy above 0.5 MeV were measured by liquid scintillators exploiting their time of flight to determine the kinetic energy. For lower energy neutrons, down to thermal energy, a 3 He detector was used. The obtained data are in good agreement with previous measurements at 0° using 66 MeV proton beam, covering neutron energies >10MeV, as well as with measurements at few selected angles using protons of 46, 55 and 113 MeV energy. The present results extend the neutron yield data in the 60–70 MeV beam energy range. A comparison of measured yields to MCNP, FLUKA and Geant4 Monte Carlo simulations was performed

  1. Comprehensive Measurement of Neutron Yield Produced by 62 MeV Protons on Beryllium Target

    International Nuclear Information System (INIS)

    Osipenko, M.; Ripani, M.; Ricco, G.; Alba, R.; Schillaci, M.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; Figuera, P.; Finocchiaro, P.; Maiolino, C.; Santonocito, D.; Scuderi, V.; Barbagallo, M.; Colonna, N.; Boccaccio, P.; Esposito, J.; Celentano, A.; Viberti, C.M.; Kostyukov, A.

    2013-06-01

    A low-power prototype of neutron amplifier, based on a 70 MeV, high current proton cyclotron being installed at LNL for the SPES RIB facility, was recently proposed within INFN-E project. This prototype uses a thick Beryllium converter to produce a fast neutron spectrum feeding a sub-critical reactor core. To complete the design of such facility the new measurement of neutron yield from a thick Beryllium target was performed at LNS. This measurement used liquid scintillator detectors to identify produced neutrons by Pulse Shape Discrimination and Time of Flight technique to measure neutron energy in the range 0.5-62 MeV. To extend the covered neutron energy range 3 He detector was used to measure neutrons below 0.5 MeV. The obtained yields were normalized to the charge deposited by the proton beam on the metallic Beryllium target. These techniques allowed to achieve a wide angular coverage from 0 to 150 degrees and to explore almost complete neutron energy interval. (authors)

  2. Traceable Determination of the Absolute Neutron Emission Yields of UO2F2 Working Reference Materials

    International Nuclear Information System (INIS)

    LaFleur, A.M.; Swinhoe, M.T.; Mayo, D.R.; Sapp, B.A.; Croft, S.; Mayer, R.L.

    2013-06-01

    The nuclear material contained in the process equipment of a uranium enrichment plant (referred to as holdup) is an important component of the overall nuclear material inventory for the plant. Accurate quantification and verification of holdup is needed to improve international safeguards and nuclear material accountancy. This is also needed for criticality safety and waste disposition. Passive neutron and gamma-ray nondestructive assay (NDA) methods are used to measure the holdup in process equipment. A key advantage of neutron measurements is that neutrons are highly penetrating and can be measured through thick walled equipment. The dominant source of neutrons in the UO 2 F 2 holdup is from the 19 F(α, n) 22 Na reaction resulting from 234 U alpha decay when uranium is enriched. There is a considerable spread between different historic determinations of the 19 F(α, n) yield from uranium which limits the accuracy of modeling and the calibration of NDA instruments. Furthermore, the compound form and presence of water also significantly affects the neutron emission rate from the holdup. This paper describes a series of experimental measurements performed at Los Alamos National Laboratory (LANL) to determine the absolute neutron emission yield from 10 different UO 2 F 2 working reference materials (WRMs) fabricated at the Portsmouth Gaseous Diffusion Plant (PGDP). The Mini Epithermal Neutron Multiplicity Counter (Mini ENMC) and a NIST certified 252 Cf neutron source were used for these measurements. The high efficiency and short die-away time of the Mini ENMC provides the high measurement precision needed to certify the neutron emission yield. The experiment was designed to achieve sub 1% accuracy in the net counting rate on each item and to provide assurance that important factors such as instrument stability, item placement and background were well understood. The traceable neutron yields measured from the WRMs were used to determine a more accurate neutron yield

  3. The experimental study of fuel ion temperature and neutron yield for directly driven implosion

    International Nuclear Information System (INIS)

    Chen Ming; Chen Jiabin; Li Chaoguang

    2002-01-01

    An ultra-fast quenched plastic scintillation detector was used to measure DT neutron yield in the first experiment performed on the Shengguang II laser facility. The uncertainties of neutron yields were +-7% - 10%. The measured implosion neutron yields were in agreement with the calculated ones supplied by Institute of Applied Physics and Computational Mathematics in the range of +-20%

  4. Correlation of the neutron yield from the plasma focus upon variations in the magnetic field energy of the discharge circuit

    Science.gov (United States)

    Ablesimov, V. E.; Dolin, Yu. N.; Kalinychev, A. E.; Tsibikov, Z. S.

    2017-10-01

    The relation between neutron yield Y and magnetic field energy variations Δ W in the discharge circuit has been studied for a Mather-type plasma-focus camera. The activation technique (activation of silver isotopes) has been used to measure the integral yield of DD neutrons from the source. The time dependence of the neutron yield has been recorded by scintillation detectors. For the device used in the investigations, the neutron yield exhibits a linear dependence on variations in the magnetic field energy Δ W in the discharge circuit at the instant of neutron generation. It is also found that this dependence is related to the initial deuteron pressure in the discharge chamber.

  5. Fusion neutron yield and flux calculation on HT-7 superconducting tokamak

    International Nuclear Information System (INIS)

    Fu Yanzhang; Zhu Yubao; Chen Juequan

    2006-01-01

    Neutron yield and flux have been numerically estimated on HT-7 tokamak. The total fusion neutron yield and neutron flux distribution on different positions and azimuth angles of the device are presented. Analyses on the errors induced by ion temperature and density distribution factors are given in detail. The results of the calculations provide a useful database for neutron diagnostics and neutron radiation protection. (authors)

  6. Fission product yields of 235U and 238U induced by monoenergetic neutrons

    International Nuclear Information System (INIS)

    Zheng Chunkai; Wang Houji

    1993-01-01

    Using 5-Gauss semi-empirical formula for fragment mass distribution, the pre-neutron fragment yields of 235 U and 238 U induced by monoenergetic neutrons are calculated. The yields of neutron emitted from fragments are obtained by fitting with seven points and linear interpolation formula. Then, the pre-neutron fragment yield is converted to post-neutron product yield with the method given by Terrell. The variation of product yield of 40 95 Zr, 58 144 Ce and 60 147 Nd are calculated and compared with experimental results

  7. Independent yields of Rb and Cs isotopes from thermal-neutron induced fission of 235U

    International Nuclear Information System (INIS)

    Balestrini, S.J.; Decker, R.; Wollnik, H.; Wuensch, K.D.; Jung, G.; Koglin, E.; Siegert, G.

    1979-01-01

    The relative yields of Rb and Cs isotopes from thermal-neutron fission of 235 U have been redetermined using the mass separator OSTIS, on-line at a neutron guide of the High-Flux Beam Reactor at the Institut Laue-Langevin, Grenoble, France. The separator ion source was a hot oven containing 235 U in a graphite matrix. The neutron beam was pulsed. Alkali fission products diffused out of the graphite and were ionized, thus producing a stepwise increase in the analyzed ion beam proportional to the independent fission yield. The ion beam and the fissions in the source were monitored simultaneously. The diffusion of Rb and Cs from the source was exponential in time with half-lives ranging from 2.8 to 18 sec, depending upon the element and source temperature. The independent fission yields of Rb and Cs are normalized by equating their element yields to each other and to a value computed from the charge distributions observed with the recoil separator LOHENGRIN and well established mass yields. Fractional independent yields are deduced from the independent fission yields, and these compare very well with the EOZ model described by Wahl

  8. Delayed neutron yields and spectra from photofission of actinides with bremsstrahlung photons below 20 MeV

    International Nuclear Information System (INIS)

    Dore, D; David, J-C; Giacri, M-L; Laborie, J-M; Ledoux, X; Petit, M; Ridikas, D; Van Lauwe, A

    2006-01-01

    Experimental results for the photofission of 238 U with an endpoint Bremsstrahlung emission of 15 MeV are presented. Absolute yield and time characteristics of the delayed neutrons are extracted. In parallel, calculations for fission fragment distributions and corresponding delayed neutron parameters are given and compared to data

  9. Deploying Solid Targets in Dense Plasma Focus Devices for Improved Neutron Yields

    Science.gov (United States)

    Podpaly, Y. A.; Chapman, S.; Povilus, A.; Falabella, S.; Link, A.; Shaw, B. H.; Cooper, C. M.; Higginson, D.; Holod, I.; Sipe, N.; Gall, B.; Schmidt, A. E.

    2017-10-01

    We report on recent progress in using solid targets in dense plasma focus (DPF) devices. DPFs have been observed to generate energetic ion beams during the pinch phase; these beams interact with the dense plasma in the pinch region as well as the background gas and are believed to be the primary neutron generation mechanism for a D2 gas fill. Targets can be placed in the beam path to enhance neutron yield and to shorten the neutron pulse if desired. In this work, we measure yields from placing titanium deuteride foils, deuterated polyethylene, and non-deuterated control targets in deuterium filled DPFs at both megajoule and kilojoule scales. Furthermore, we have deployed beryllium targets in a helium gas-filled, kilojoule scale DPF for use as a potential AmBe radiological source replacement. Neutron yield, neutron time of flight, and optical images are used to diagnose the effectiveness of target deployments relative to particle-in-cell simulation predictions. A discussion of target holder engineering for material compatibility and damage control will be shown as well. Prepared by LLNL under Contract DE-AC52-07NA27344. Supported by the Office of Defense Nuclear Nonproliferation Research and Development within U.S. DOE's National Nuclear Security Administration and the LLNL Institutional Computing Grand Challenge program.

  10. 8-group relative delayed neutron yields for epithermal neutron induced fission of 235U and 239Pu

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Korolev, G.G.; Roshchenko, V.A.; Tertychnyj, R.G

    2002-01-01

    An 8-group representation of relative delayed neutron yields was obtained for epithermal neutron induced fission of 235 U and 239 Pu. These data were compared with ENDF/B-VI data in terms of the average half- life of the delayed neutron precursors and on the basis of the dependence of reactivity on the asymptotic period. (author)

  11. Measurements of periods, relative abundances and absolute yields of delayed neutrons from fast neutron induced fission of {sup 237}Np

    Energy Technology Data Exchange (ETDEWEB)

    Piksaikine, V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    The experimental method for measurements of the delayed neutron yields and period is presented. The preliminary results of the total yield, relative abundances and periods are shown comparing with the previously reported values. (J.P.N.)

  12. Tests and calibration of NIF neutron time of flight detectors.

    Science.gov (United States)

    Ali, Z A; Glebov, V Yu; Cruz, M; Duffy, T; Stoeckl, C; Roberts, S; Sangster, T C; Tommasini, R; Throop, A; Moran, M; Dauffy, L; Horsefield, C

    2008-10-01

    The National Ignition Facility (NIF) neutron time of flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD(*) implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 1x10(9) to 2x10(19). The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory. Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detector tests and calibration will be presented.

  13. Study on calibration of neutron efficiency and relative photo-yield of plastic scintillator

    International Nuclear Information System (INIS)

    Peng Taiping; Zhang Chuanfei; Li Rurong; Zhang Jianhua; Luo Xiaobing; Xia Yijun; Yang Zhihua

    2002-01-01

    A method used for the calibration of neutron efficiency and the relative photo yield of plastic scintillator is studied. T(p, n) and D(d, n) reactions are used as neutron resources. The neutron efficiencies and the relative photo yields of plastic scintillators 1421 (40 mm in diameter and 5 mm in thickness) and determined in the neutron energy range of 0.655-5 MeV

  14. 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.

  15. Time-of-flight neutron spectrometer for JT-60U

    International Nuclear Information System (INIS)

    Shibata, Y.; Iguchi, T.; Uritani, Akira; Kawarabayashi, Jun; Hoek, Magnus; Nishitani, T.; Morioka, A.

    2001-01-01

    We have developed a 2.45 MeV neutron Double Crystal Time-of-Flight (DC-TOF) spectrometer for Deuterium plasmas in JT-60U. The DC-TOF neutron spectrometer consists of two fast plastic scintillators (BC-408 made by Bicron, 50 cm 2 and 1800 cm 2 , thickness 2 cm), located on constant TOF spheres. The constant TOF spheres have a radius of 1 m which gives a neutron flight length of 1.64 m and a TOF of 92 ns for 2.45 MeV neutrons. The calculated spectrometer efficiency and resolution are 2.8x10 -2 cm 2 and 100 keV, respectively. The energy resolution corresponds to a time resolution of 2.0 ns. The spectrometer has been installed in the basement of JT-60U, 10 m away from the plasma center with vertical line-of-sight. Neutron energy spectra have been obtained when the neutron yield from the plasma is ∼10 15 neutrons/s. (author)

  16. Development and characterization of a high yield transportable pulsed neutron source with efficient and compact pulsed power system

    Science.gov (United States)

    Verma, Rishi; Mishra, Ekansh; Dhang, Prosenjit; Sagar, Karuna; Meena, Manraj; Shyam, Anurag

    2016-09-01

    The results of characterization experiments carried out on a newly developed dense plasma focus device based intense pulsed neutron source with efficient and compact pulsed power system are reported. Its high current sealed pseudospark switch based low inductance capacitor bank with maximum stored energy of ˜10 kJ is segregated into four modules of ˜2.5 kJ each and it cumulatively delivers peak current in the range of 400 kA-600 kA (corresponding to charging voltage range of 14 kV-18 kV) in a quarter time period of ˜2 μs. The neutron yield performance of this device has been optimized by discretely varying deuterium filling gas pressure in the range of 6 mbar-11 mbar at ˜17 kV/550 kA discharge. At ˜7 kJ/8.5 mbar operation, the average neutron yield has been measured to be in the order of ˜4 × 109 neutrons/pulse which is the highest ever reported neutron yield from a plasma focus device with the same stored energy. The average forward to radial anisotropy in neutron yield is found to be ˜2. The entire system is contained on a moveable trolley having dimensions 1.5 m × 1 m × 0.7 m and its operation and control (up to the distance of 25 m) are facilitated through optically isolated handheld remote console. The overall compactness of this system provides minimum proximity to small as well as large samples for irradiation. The major intended application objective of this high neutron yield dense plasma focus device development is to explore the feasibility of active neutron interrogation experiments by utilization of intense pulsed neutron sources.

  17. Development and characterization of a high yield transportable pulsed neutron source with efficient and compact pulsed power system

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Rishi, E-mail: rishiv9@gmail.com, E-mail: rishiv@barc.gov.in; Mishra, Ekansh; Dhang, Prosenjit; Sagar, Karuna; Meena, Manraj; Shyam, Anurag [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre Autonagar, Vishakapatnam 530012 (India)

    2016-09-15

    The results of characterization experiments carried out on a newly developed dense plasma focus device based intense pulsed neutron source with efficient and compact pulsed power system are reported. Its high current sealed pseudospark switch based low inductance capacitor bank with maximum stored energy of ∼10 kJ is segregated into four modules of ∼2.5 kJ each and it cumulatively delivers peak current in the range of 400 kA–600 kA (corresponding to charging voltage range of 14 kV–18 kV) in a quarter time period of ∼2 μs. The neutron yield performance of this device has been optimized by discretely varying deuterium filling gas pressure in the range of 6 mbar–11 mbar at ∼17 kV/550 kA discharge. At ∼7 kJ/8.5 mbar operation, the average neutron yield has been measured to be in the order of ∼4 × 10{sup 9} neutrons/pulse which is the highest ever reported neutron yield from a plasma focus device with the same stored energy. The average forward to radial anisotropy in neutron yield is found to be ∼2. The entire system is contained on a moveable trolley having dimensions 1.5 m × 1 m × 0.7 m and its operation and control (up to the distance of 25 m) are facilitated through optically isolated handheld remote console. The overall compactness of this system provides minimum proximity to small as well as large samples for irradiation. The major intended application objective of this high neutron yield dense plasma focus device development is to explore the feasibility of active neutron interrogation experiments by utilization of intense pulsed neutron sources.

  18. Measuring the absolute DT neutron yield using the Magnetic Recoil Spectrometer at OMEGA and the NIF

    Energy Technology Data Exchange (ETDEWEB)

    Mackinnon, A; Casey, D; Frenje, J A; Johnson, M G; Seguin, F H; Li, C K; Petrasso, R D; Glebov, V Y; Katz, J; Knauer, J; Meyerhofer, D; Sangster, T; Bionta, R; Bleuel, D; Hachett, S P; Hartouni, E; Lepape, S; Mckernan, M; Moran, M; Yeamans, C

    2012-05-03

    A Magnetic Recoil Spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion (ICF) implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  19. Yields of correlated fragment pairs and neutron multiplicity in spontaneous fission of {sup 242}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Veselsky, M.; Kliman, J.; Morhaccaron, M. [Institute of Physics of Slovak Academy of Sciences, Dubravska 9, 84228 Bratislava (Slovakia); Ramayya, A.V.; Kormicki, J.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville (United States)] Rasmussen, J.O. [Lawrence Berkeley National Laboratory, Berkeley (United States)] Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore (United States); Daniel, A.V.; Popeko, G.S.; Oganessian, Yu. Ts. [Joint Institute for Nuclear Research, Dubna (Russia)] Greiner, W. [Institut fur Theoretische Physik, J. W. Goethe Universitaet, Frankfurt a. M. (Germany); Aryaeinejad, R. [Idaho National Engineering Laboratory, Idaho Falls (United States)

    1998-10-01

    Yields of correlated fragment pairs were obtained in spontaneous fission of {sup 242}Pu. Charge, mass and neutron multiplicity distributions of fragment pairs were determined and compared to available data. The yield of cold fission without neutron emission was determined to about 10{percent} for the set of observed correlated fragment pairs. {copyright} {ital 1998 American Institute of Physics.}

  20. Absolute measurement of the DT primary neutron yield on the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Leeper R.J.

    2013-11-01

    Full Text Available The measurement of the absolute neutron yield produced in inertial confinement fusion target experiments conducted on the National Ignition Facility (NIF is essential in benchmarking progress towards the goal of achieving ignition on this facility. This paper describes three independent diagnostic techniques that have been developed to make accurate and precise DT neutron yield measurements on the NIF.

  1. Independent fission yields of Rb and Cs from thermal-neutron-induced fission of 239Pu

    International Nuclear Information System (INIS)

    Balestrini, S.J.; Forman, L.

    1975-01-01

    The relative independent fission yields of Rb and Cs from thermal-neutron-induced fission of 239 Pu have been measured on line using a mass spectrograph and thermalized neutrons from a burst reactor. Independent yields were derived by normalizing the measurements to products of chain yields and fractional independent yields, estimating the latter from measured cumulative yields of Kr and Xe. Comparing the independent yields with those from 238 U fission, the 239 Pu results show shifts in isotopic yield distribution toward lower mass for both Rb and Cs and also toward the production of more Cs and less Rb when 239 Pu is fissioned

  2. Determination of neutron generation time in miniature neutron source reactor by measurement of neutronics transfer function

    International Nuclear Information System (INIS)

    Hainoun, A.; Khamis, I.

    2000-01-01

    The prompt neutron generation time Λ and the total effective fraction of delayed neutrons (including the effect of photoneutrons) β have been experimentally determined for the miniature neutron source reactor (MNSR) of Syria. The neutron generation time was found by taking measurements of the reactor open-loop transfer function using newly devised reactivity-step-ejection method by the reactor pneumatic rabbit system. Small reactivity perturbations i.e. step changes of reactivity starting from steady state, were introduced into the reactor during operation at low power level i.e. zero-power. Relative neutron flux and reactivity versus time were obtained. Using transfer function analysis as well as least square fitting techniques and measuring the delayed neutrons fraction, the neutron generation time was determined to be 74.6±1.57 μs. Using the prompt jump approximation of neutron flux, the total effective fraction of delayed neutrons was measured and found to be 0.00783±0.00017. Measured values of Λ and β were found to be very consistent with calculated ones reported in the safety analysis report. (orig.)

  3. Right-left asymmetry of γ quanta yield in a neutron resonance of 117Sn with parity nonconservation

    International Nuclear Information System (INIS)

    Alfimenkov, V.P.; Borzakov, S.B.; Vo Van Tkhuan; Mareev, Yu.D.; Pikel'ner, L.B.; Frank, I.M.; Khrykin, A.S.; Sharapov, Eh.I.

    1984-01-01

    The right-left asymmetry was observed for the first time in the yield of γ quanta (esub(γ)=9.32 MeV) from radiative capture of polarized neutrons in the channel with total neutron momentum jsub(n)=lsub(n)+ssub(n)=1/2 was obtained d: GITAsub(psup(1/2))sup(n)=(0.27+-0.03)GITAsub(p)sup(n)

  4. 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.

  5. The Absolute Total Delayed Neutron Yields, Relative Abundances and Half-Lives of Delayed Neutron Groups from Neutron Induced Fission of 232Th, 233U, 236U, 239Pu and 241Am

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Egorov, A.S.; Mitrofanov, K.V.

    2013-10-01

    The absolute total yield, relative yields and half-lives of individual delayed neutron groups produced from fast neutron-induced fission of 232 Th, 233 U, 236 U, 239 Pu and 241 Am are measured by performing cyclic irradiations of the sample and subsequently measuring the time dependence of the delayed neutron activity decay. The data are analysed using an iterative least-squares fitting procedure to estimate the temporary delayed neutron parameters both for the 6- and 8-group models at each incident neutron energy. The improved data contribute to the continuing effort to meet the data requirements emerging from the current trends in reactor technologies, including the growing interest in fuel recycling strategies and new concepts of actinide burners. (author)

  6. Measurement of fission yields far from the center of isotopic distributions in the thermal neutron fission of 235U

    International Nuclear Information System (INIS)

    Shmid, M.

    1979-08-01

    The main purpose of this work was to measure independent yields, in the thermal neutron fission of 235 U, of fission products which lie far from the centers of the isotopic and isobaric yield distributions. These measurements were used to test the predictions of semi-empirical systematics of fission yields and theoretical fission models. Delay times were measured as a function of temperature in the range 1200-2000degC. The very low delay times achieved in the present work permitted expanding the measurable region to the isotopes 147 , 148 Cs and 99 Rb which are of special interest in the present work. The delay times of Sr and Ba isotopes achieved were more than two orders of magnitude lower than values reported in the literature and thus short-lived isotopes of these elements could be separated for the first time by mass spectrometry. The half-lives of 147 Ba, 148 Ba, 149 La and 149 Ce were measured for the first time. The isotopic distributions of fission yields were measured for the elements Rb, Sr, Cs and Ba in the thermal neutron fission of 235 U, those of 99 Rb, 147 Cs and 148 Cs having been measured for the first time. A comparison of the experimental yields with the predictions of the currently accepted semi-empirical systematics of fission yields, which is the odd-even effect systematics, shows that the systematics succeeds in accounting for the strong odd-even proton effect and the weaker odd-even neutron effect and also in predicting the shape of the distributions in the central region. It is shown that prompt neutron emission broadens the distribution only slightly in the wing of heavy isotopes and more significantly in the wing of light isotopes. But the effect of prompt neutron emission cannot explain the large discrepancies existing between the predictions of fission models and the experimentally measured fission yield in the wings of the isotopic distributions. (B.G.)

  7. Analysis of incident-energy dependence of delayed neutron yields in actinides

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, Mohamad Nasrun bin Mohd, E-mail: monasr211@gmail.com; Metorima, Kouhei, E-mail: kohei.m2420@hotmail.co.jp; Ohsawa, Takaaki, E-mail: ohsawa@mvg.biglobe.ne.jp; Hashimoto, Kengo, E-mail: kengoh@pp.iij4u.or.jp [Graduate School of Science and Engineering, Kindai University, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2015-04-29

    The changes of delayed neutron yields (ν{sub d}) of Actinides have been analyzed for incident energy up to 20MeV using realized data of precursor after prompt neutron emission, from semi-empirical model, and delayed neutron emission probability data (P{sub n}) to carry out a summation method. The evaluated nuclear data of the delayed neutron yields of actinide nuclides are still uncertain at the present and the cause of the energy dependence has not been fully understood. In this study, the fission yields of precursor were calculated considering the change of the fission fragment mass yield based on the superposition of fives Gaussian distribution; and the change of the prompt neutrons number associated with the incident energy dependence. Thus, the incident energy dependent behavior of delayed neutron was analyzed.The total number of delayed neutron is expressed as ν{sub d}=∑Y{sub i} • P{sub ni} in the summation method, where Y{sub i} is the mass yields of precursor i and P{sub ni} is the delayed neutron emission probability of precursor i. The value of Y{sub i} is derived from calculation of post neutron emission mass distribution using 5 Gaussian equations with the consideration of large distribution of the fission fragments. The prompt neutron emission ν{sub p} increases at higher incident-energy but there are two different models; one model says that the fission fragment mass dependence that prompt neutron emission increases uniformly regardless of the fission fragments mass; and the other says that the major increases occur at heavy fission fragments area. In this study, the changes of delayed neutron yields by the two models have been investigated.

  8. Time recording unit for a neutron time of flight spectrometer

    International Nuclear Information System (INIS)

    Puranik, Praful; Ajit Kiran, S.; Chandak, R.M.; Poudel, S.K.; Mukhopadhyay, R.

    2011-01-01

    Here the architecture and design of Time Recording Unit for a Neutron Time of Flight Spectrometer have been described. The Spectrometer would have an array of 50 Nos. of one meter long linear Position Sensitive Detector (PSD) placed vertically around the sample at a distance of 2000 mm. The sample receives periodic pulsed neutron beam coming through a Fermi chopper. The time and zone of detection of a scattered neutron in a PSD gives information of its flight time and path length, which will be used to calculate its energy. A neutron event zone (position) and time detection module for each PSD provides a 2 bit position/zone code and an event timing pulse. The path length assigned to a neutron detected in a zone (Z1, Z2 etc) in the PSD is the mean path length seen by the neutrons detected in that zone of the PSD. A Time recording unit described here receives event zone code and timing pulse for all the 50 detectors, tags a proper time window code to it, before streaming it to computer for calculation of the energy distribution of neutrons scattered from the sample

  9. Analysis and computation of statistic fluctuations in ICF neutron yield measurement

    International Nuclear Information System (INIS)

    Liu Zhongjie; Zheng Zhijian; Yi Rongqing; Liu Shenye; Ding Yongkun; Deng Caibo

    2011-01-01

    The plastic scintillation detector is used to measure the yield of DD neutrons or DT neutrons. Fast neutrons incident on the scintillator give rise to recoil protons. Because the range of the recoil protons is usually small compared with the dimensions of the scintillator, their full energy is deposited in the scintillator. The statistic fluctuation of the protons' number and that of the protons' total energy are two sources of the measurement uncertainty. Based on DT neutrons, this paper presents the algorithms to compute the probability density functions of the two statistic fluctuations. The algorithms are applicable to the related computation for other fast monoenergetic neutrons in the plastic scintillator. (authors)

  10. Measurement of neutron yield by 62 MeV proton beam on a thick Beryllium target

    International Nuclear Information System (INIS)

    Alba, R; Cosentino, G; Zoppo, A Del; Pietro, A Di; Figuera, P; Finocchiaro, P; Maiolino, C; Santonocito, D; Schillaci, M; Barbagallo, M; Colonna, N; Boccaccio, P; Esposito, J; Celentano, A; Osipenko, M; Ricco, G; Ripani, M; Viberti, C M; Kostyukov, A

    2013-01-01

    In the framework of research on IVth generation reactors and high intensity neutron sources a low-power prototype neutron amplifier was recently proposed by INFN. It is based on a low-energy, high current proton cyclotron, whose beam, impinging on a thick Beryllium converter, produces a fast neutron spectrum. The world database on the neutron yield from thick Beryllium target in the 70 MeV proton energy domain is rather scarce. The new measurement was performed at LNS, covering a wide angular range from 0 to 150 degrees and an almost complete neutron energy interval. In this contribution the preliminary data are discussed together with the proposed ADS facility.

  11. Systematic determination of the JET absolute neutron yield using the MPR spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kronborg-Pettersson, N

    2003-04-01

    This thesis describes the first high-statistics systematic analysis of JET neutron yield and rate measurements obtained by using data acquired with the Magnetic Proton Recoil (MPR) neutron spectrometer. The neutron yield and rate were determined by using the count-rate from the MPR neutron spectrometer together with neutron profile information from other neutron diagnostic systems. This has previously been done manually for a few pulses. To be able to do this in a more systematic way a part of the neutron spectrum evaluation code was extracted and put into a separate custom-made program and modifications were done to extract sets of MPR data automatically. The codes have been used for analysis of a large set of pulses from the deuterium-tritium campaign at JET in 1997. Several results were obtained, the most significant of which was the clear improvement seen when neutron profile corrections were applied. Neutron yield-rates derived from MPR count-rate are shown to be in excellent agreement with other JET neutron diagnostic data.

  12. Time reversal invariance in polarized neutron decay

    Energy Technology Data Exchange (ETDEWEB)

    Wasserman, Eric G. [Harvard Univ., Cambridge, MA (United States)

    1994-03-01

    An experiment to measure the time reversal invariance violating (T-violating) triple correlation (D) in the decay of free polarized neutrons has been developed. The detector design incorporates a detector geometry that provides a significant improvement in the sensitivity over that used in the most sensitive of previous experiments. A prototype detector was tested in measurements with a cold neutron beam. Data resulting from the tests are presented. A detailed calculation of systematic effects has been performed and new diagnostic techniques that allow these effects to be measured have been developed. As the result of this work, a new experiment is under way that will improve the sensitivity to D to 3 x 10-4 or better. With higher neutron flux a statistical sensitivity of the order 3 x 10-5 is ultimately expected. The decay of free polarized neutrons (n → p + e + $\\bar{v}$e) is used to search for T-violation by measuring the triple correlation of the neutron spin polarization, and the electron and proton momenta (σn • pp x pe). This correlation changes sign under reversal of the motion. Since final state effects in neutron decay are small, a nonzero coefficient, D, of this correlation indicates the violation of time reversal invariance. D is measured by comparing the numbers of coincidences in electron and proton detectors arranged symmetrically about a longitudinally polarized neutron beam. Particular care must be taken to eliminate residual asymmetries in the detectors or beam as these can lead to significant false effects. The Standard Model predicts negligible T-violating effects in neutron decay. Extensions to the Standard Model include new interactions some of which include CP-violating components. Some of these make first order contributions to D.

  13. Time reversal invariance in polarized neutron decay

    International Nuclear Information System (INIS)

    Wasserman, E.G.

    1994-03-01

    An experiment to measure the time reversal invariance violating (T-violating) triple correlation (D) in the decay of free polarized neutrons has been developed. The detector design incorporates a detector geometry that provides a significant improvement in the sensitivity over that used in the most sensitive of previous experiments. A prototype detector was tested in measurements with a cold neutron beam. Data resulting from the tests are presented. A detailed calculation of systematic effects has been performed and new diagnostic techniques that allow these effects to be measured have been developed. As the result of this work, a new experiment is under way that will improve the sensitivity to D to 3 x 10 -4 or better. With higher neutron flux a statistical sensitivity of the order 3 x 10 -5 is ultimately expected. The decay of free polarized neutrons (n → p + e + bar v e ) is used to search for T-violation by measuring the triple correlation of the neutron spin polarization, and the electron and proton momenta (σ n · p p x p e ). This correlation changes sign under reversal of the motion. Since final state effects in neutron decay are small, a nonzero coefficient, D, of this correlation indicates the violation of time reversal invariance. D is measured by comparing the numbers of coincidences in electron and proton detectors arranged symmetrically about a longitudinally polarized neutron beam. Particular care must be taken to eliminate residual asymmetries in the detectors or beam as these can lead to significant false effects. The Standard Model predicts negligible T-violating effects in neutron decay. Extensions to the Standard Model include new interactions some of which include CP-violating components. Some of these make first order contributions to D

  14. The light-yield response of a NE-213 liquid-scintillator detector measured using 2–6 MeV tagged neutrons

    International Nuclear Information System (INIS)

    Scherzinger, J.; Al Jebali, R.; Annand, J.R.M.; Fissum, K.G.; Hall-Wilton, R.; Kanaki, K.; Lundin, M.; Nilsson, B.; Perrey, H.; Rosborg, A.; Svensson, H.

    2016-01-01

    The response of a NE-213 liquid-scintillator detector has been measured using tagged neutrons from 2 to 6 MeV originating from an Am/Be neutron source. The neutron energies were determined using the time-of-flight technique. Pulse-shape discrimination was employed to discern between gamma-rays and neutrons. The behavior of both the fast (35 ns) and the combined fast and slow (475 ns) components of the neutron scintillation-light pulses were studied. Three different prescriptions were used to relate the neutron maximum energy-transfer edges to the corresponding recoil-proton scintillation-light yields, and the results were compared to simulations. The overall normalizations of parametrizations which predict the fast or total light yield of the scintillation pulses were also tested. Our results agree with both existing data and existing parametrizations. We observe a clear sensitivity to the portion and length of the neutron scintillation-light pulse considered.

  15. The universal library of fission products and delayed neutron group yields

    International Nuclear Information System (INIS)

    Koldobskiy, A.B.; Zhivun, V.M.

    1997-01-01

    A new fission product yield library based on the Semiempirical method for the estimation of their mass and charge distribution is described. Contrary to other compilations, this library can be used with all possible excitation energies of fissionable actinides. The library of delayed neutron group yields, based on the fission product yield compilation, is described as well. (author). 15 refs, 4 tabs

  16. Simplified geometric model for the calculation of neutron yield in an accelerator of 18 MV for radiotherapy

    International Nuclear Information System (INIS)

    Paredes G, L.C.; Balcazar G, M.; Francois L, J.L.; Azorin N, J.

    2008-01-01

    The results of the neutrons yield in different components of the bolster of an accelerator Varian Clinac 2100C of 18 MV for radiotherapy are presented, which contribute to the radiation of flight of neutrons in the patient and bolster planes. For the calculation of the neutrons yield, a simplified geometric model of spherical cell for the armor-plating of the bolster with Pb and W was used. Its were considered different materials for the Bremsstrahlung production and of neutrons produced through the photonuclear reactions and of electro disintegration, in function of the initial energy of the electron. The theoretical result of the total yield of neutrons is of 1.17x10 -3 n/e, considering to the choke in position of closed, in the patient plane with a distance source-surface of 100 cm; of which 15.73% corresponds to the target, 58.72% to the primary collimator, 4.53% to the levelled filter of Fe, 4.87% to the levelled filter of Ta and 16.15% to the closed choke. For an initial energy of the electrons of 18 MeV, a half energy of the neutrons of 2 MeV was obtained. The calculated values for radiation of experimental neutrons flight are inferior to the maxima limit specified in the NCRP-102 and IEC-60601-201.Ed.2.0 reports. The absorbed dose of neutrons determined through the measurements with TLD dosemeters in the isocenter to 100 cm of the target when the choke is closed one, is approximately 3 times greater that the calculated for armor-plating of W and 1.9 times greater than an armor-plating of Pb. (Author)

  17. Calculated /alpha/-induced thick target neutron yields and spectra, with comparison to measured data

    International Nuclear Information System (INIS)

    Wilson, W.B.; Bozoian, M.; Perry, R.T.

    1988-01-01

    One component of the neutron source associated with the decay of actinide nuclides in many environments is due to the interaction of decay /alpha/ particles in (/alpha/,n) reactions on low Z nuclides. Measurements of (/alpha/,n) thick target neutron yields and associated neutron spectra have been made for only a few combinations of /alpha/ energy and target nuclide or mixtures of actinide and target nuclides. Calculations of thick target neutron yields and spectra with the SOURCES code require /alpha/-energy-dependent cross sections for (/alpha/,n) reactions, as well as branching fractions leading to the energetically possible levels of the product nuclides. A library of these data has been accumulated for target nuclides of Z /le/ 15 using that available from measurements and from recent GNASH code calculations. SOURCES, assuming neutrons to be emitted isotopically in the center-of-mass system, uses libraries of /alpha/ stopping cross sections, (/alpha/,n) reaction cross reactions, product nuclide level branching fractions, and actinide decay /alpha/ spectra to calculate thick target (/alpha/,n) yields and neutron spectra for homogeneous combinations of nuclides. The code also calculates the thick target yield and angle intergrated neutron spectrum produced by /alpha/-particle beams on targets of homogeneous mixtures of nuclides. Illustrative calculated results are given and comparisons are made with measured thick target yields and spectra. 50 refs., 1 fig., 2 tabs

  18. The diagnostic technique of doppler width for low-yield neutrons

    International Nuclear Information System (INIS)

    Chen Jiabin; Teng Hao; Feng Jie; Zheng Zhijian; Tang Daoyuan; Liu Zhongli

    1997-01-01

    The author introduces the diagnostic technique of Doppler Width for low-yield neutrons by ultra-fast-quenched plastic scintillation detector. The relation between measurement error and detector position has been calculated. The result shows that the diagnostic method and detector can be used for as low as 10 7 ∼10 8 neutron yield and 2∼3 KeV ion temperature

  19. Independent yields of Rb and Cs isotopes from thermal-neutron induced fission of /sup 235/U

    Energy Technology Data Exchange (ETDEWEB)

    Balestrini, S.J.; Decker, R.; Wollnik, H.; Wuensch, K.D.; Jung, G.; Koglin, E.; Siegert, G.

    1979-12-01

    The relative yields of Rb and Cs isotopes from thermal-neutron fission of /sup 235/U have been redetermined using the mass separator OSTIS, on-line at a neutron guide of the High-Flux Beam Reactor at the Institut Laue-Langevin, Grenoble, France. The separator ion source was a hot oven containing /sup 235/U in a graphite matrix. The neutron beam was pulsed. Alkali fission products diffused out of the graphite and were ionized, thus producing a stepwise increase in the analyzed ion beam proportional to the independent fission yield. The ion beam and the fissions in the source were monitored simultaneously. The diffusion of Rb and Cs from the source was exponential in time with half-lives ranging from 2.8 to 18 sec, depending upon the element and source temperature. The independent fission yields of Rb and Cs are normalized by equating their element yields to each other and to a value computed from the charge distributions observed with the recoil separator LOHENGRIN and well established mass yields. Fractional independent yields are deduced from the independent fission yields, and these compare very well with the EOZ model described by Wahl.

  20. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Smith, H.D.; Smith, M.P.; Schultz, W.E.

    1981-01-01

    A pulsed high-energy neutron source irradiates the earth formations surrounding a borehole with bursts of fast neutrons. A pair of detectors, one sensitive to epithermal neutrons and the other sensitive to fast neutrons and thermal neutron capture gamma rays, measure the fast and epithermal neutron populations at their effective distances from the source. The fast neutron measurements can be separated from thermal neutron interactions by time gating techniques and by pulse shape discrimination. The measurments of the fast and epithermal neutron populations at the two detectors may then be interpreted in terms of the earth formation porosity in accordance with predetermined relationships. Between neutron bursts capture gamma rays are detected in two or more time intervals, and these measurements are used to derive the thermal neutron capture cross section of the formation

  1. Neutron time-of-flight spectroscopy

    International Nuclear Information System (INIS)

    Copley, J.R.D.; Udovic, T.J.

    1993-01-01

    The time-of-flight technique is employed in two of the instruments at the NIST Cold Neutron Research Facility (CNRF). A pulsed monochromatic beam strikes the sample, and the energies of scattered neutrons are determined from their times-of-flight to an array of detectors. The time-of-flight method may be used in a variety of types of experiments such as studies of vibrational and magnetic excitations, tunneling spectroscopy, and quasielastic scattering studies of diffusional behavior; several examples of experiments are discussed. The authors also present brief descriptions of the CNRF time-of-flight instruments, including their modi operandi and some of their more pertinent parameters and performance characteristics

  2. Correlating neutron yield and reliability for selecting experimental parameters for a plasma focus machine

    International Nuclear Information System (INIS)

    Pross, G.

    Possibilities of optimizing focus machines with a given energy content in the sense of high neutron yield and high reliability of the discharges are investigated experimentally. For this purpose, a focus machine of the Mather type with an energy content of 12 kJ was constructed. The following experimental parameters were varied: the material of the insulator in the ignition zone, the structure of the outside electrode, the length of the inside electrode, the filling pressure and the amount and polarity of the battery voltage. An important part of the diagnostic program consists of measurements of the azimuthal and axial current distribution in the accelerator, correlated with short-term photographs of the luminous front as a function of time. The results are given. A functional schematic has been drafted for focus discharge as an aid in extensive optimization of focus machines, combining findings from theory and experiments. The schematic takes into account the multiparameter character of the discharge and clarifies relationships between the experimental parameters and the target variables neutron yield and reliability

  3. Note: Neutron bang time diagnostic system on Shenguang-III prototype

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Qi; Chen, Jiabin; Liu, Zhongjie; Zhan, Xiayu; Song, Zifeng, E-mail: mphyszf@qq.com [Research Center of Laser Fusion, China Academy of Engineering Physics, P. O. Box 919-986, Mianyang, Sichuan 621900 (China)

    2014-04-15

    A neutron bang time (NBT) diagnostic system has been implemented on Shenguang-III prototype. The bang time diagnostic system is based on a sensitive fusion neutron detector, which consists of a plastic scintillator and a micro-channel plate photomultiplier tube (PMT). An optical fiber bundle is used to couple the scintillator and the PMT. The bang time system is able to measure bang time above a neutron yield of 10{sup 7}. Bang times and start time of laser were related by probing x-ray pulses produced by 200 ps laser irradiating golden targets. Timing accuracy of the NBT is better than 60 ps.

  4. Time interval approach to the pulsed neutron logging method

    International Nuclear Information System (INIS)

    Zhao Jingwu; Su Weining

    1994-01-01

    The time interval of neighbouring neutrons emitted from a steady state neutron source can be treated as that from a time-dependent neutron source. In the rock space, the neutron flux is given by the neutron diffusion equation and is composed of an infinite terms. Each term s composed of two die-away curves. The delay action is discussed and used to measure the time interval with only one detector in the experiment. Nuclear reactions with the time distribution due to different types of radiations observed in the neutron well-logging methods are presented with a view to getting the rock nuclear parameters from the time interval technique

  5. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

    1979-01-01

    A simultaneous pulsed neutron porosity and thermal neutron capture cross section logging system is provided for radiological well logging of subsurface earth formations. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a combination gamma ray and fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations; and, during the bursts, the fast neutron and epithermal neutron populations are sampled. During the interval between bursts the thermal neutron capture gamma ray population is sampled in two or more time intervals. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity phi. The capture gamma ray measurements are combined to provide a simultaneous determination of the thermal neutron capture cross section Σ

  6. Neutron yield from thick lead target by the action of high-energy electrons

    International Nuclear Information System (INIS)

    Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.; Sorokin, P.V.

    1978-01-01

    The results are presented of studying the complete neutron yield from a lead target bombarded by high-energy electrons. Neutrons were recorded by the method of radio-active indicators. The dependence of the neutron yield on the target thickness varying from 0.2 to 8 cm was obtained at the energies of electrons of 230 and 1200 MeV. The neutron yield for the given energies with the target of 6 cm in thickness is in the range of saturation and is 0.1 +-0.03 and 0.65+-0.22 (neutr./MeV.el.), respectively. The neutron angular distributions were measured for different thicknesses of targets at the 201, 230 and 1200 MeV electrons. Within the error limits the angular distributions are isotropic. The dependence of neutron yield on the electron energy was examined for a 3 cm thick target. In the energy range of 100-1200 MeV these values are related by a linear dependence with the proportionality coefficient C=3x10 -4 (neutr./MeV.el.)

  7. Time coder for slow neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Grashilin, V.A.; Ofengenden, R.G.

    1988-01-01

    Time coder for slow neutron time-of-flight spectrometer is described. The time coder is of modular structure, is performed in the CAMAC standard and operates on line with DVK-2 computer. The main coder units include supporting generator, timers, time-to-digital converter, memory unit and crate controller. Method for measuring background symmetrically to the effect is proposed for a more correct background accounting. 4 refs.; 1 fig

  8. Calculational estimations of neutron yield from ADS target

    International Nuclear Information System (INIS)

    Degtyarev, I.I.; Liashenko, O.A.; Yazynin, I.A.; Belyakov-Bodin, V.I.; Blokhin, A.I.

    2002-01-01

    Results of computational studies of high power spallation thick ADS (Accelerator-Driven System) targets with 0.8-1.2 GeV proton beams are given. Comparisons of experiments and calculations of double differential and integral n/p yield are also described. (author)

  9. Neutron Time-Of-Flight (n_TOF) experiment

    CERN Multimedia

    Brugger, M; Kaeppeler, F K; Jericha, E; Cortes rossell, G P; Riego perez, A; Baccomi, R; Laurent, B G; Griesmayer, E; Leeb, H; Dressler, M; Cano ott, D; Variale, V; Ventura, A; Carrillo de albornoz trillo, A; Andrzejewski, J J; Pavlik, A F; Kadi, Y; Zanni vlastou, R; Krticka, M; Kokkoris, M; Praena rodriguez, A J; Cortes giraldo, M A; Perkowski, J; Losito, R; Audouin, L; Weiss, C; Tagliente, G; Wallner, A; Woods, P J; Mengoni, A; Guerrero sanchez, C G; Tain enriquez, J L; Vlachoudis, V; Calviani, M; Junghans, A R; Reifarth, R; Mendoza cembranos, E; Quesada molina, J M; Babiano suarez, V; Schumann, M D; Tsinganis, A; Rauscher, T; Calvino tavares, F; Mingrone, F; Gonzalez romero, E M; Colonna, N; Negret, A L; Chiaveri, E; Milazzo, P M; De almeida carrapico, C A; Castelluccio, D M

    The neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology.

  10. Asymptotic time dependent neutron transport in multidimensional systems

    International Nuclear Information System (INIS)

    Nagy, M.E.; Sawan, M.E.; Wassef, W.A.; El-Gueraly, L.A.

    1983-01-01

    A model which predicts the asymptotic time behavior of the neutron distribution in multi-dimensional systems is presented. The model is based on the kernel factorization method used for stationary neutron transport in a rectangular parallelepiped. The accuracy of diffusion theory in predicting the asymptotic time dependence is assessed. The use of neutron pulse experiments for predicting the diffusion parameters is also investigated

  11. Development of the real-time neutron activation diagnostic system for NIF

    Science.gov (United States)

    Root, Jaben R.; Jedlovec, Donald R.; Edwards, Ellen R.; Yeamans, Charles B.; Golod, Tony; Hernandez, Jose; Adams, Phil; Brunton, Gordon

    2017-08-01

    The National Ignition Facility (NIF) is one of the highest fluence neutron sources provided by the nuclear fusion of deuterium and tritium nuclei. One of the resultant products is 14.1 MeV neutrons which provide key information to the conditions in which they were formed. The degree of polar and azimuthal symmetry of the neutron flux is a key metric for the performance of the capsule, thus a spatially-resolved measurement of the neutron distribution is critical. Implementing a suite of 48 lanthanum bromide detectors with zirconium activation samples around the target chamber has been developed to measure the neutron distribution. The system provides near real-time time estimates of the neutron fluence distribution. It is designed to operate over six orders of magnitude of neutron yield, providing overall yield estimates precise to 2%. The system is designed to operate continuously through the NIF shot cycles, accommodating high data rates. We will describe the nuclear counting system, data acquisition and archiving, analysis, and yield distribution results for some NIF high yield shots. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-CONF-736439

  12. Note: Development of real-time epithermal neutron detector for boron neutron capture therapy.

    Science.gov (United States)

    Tanaka, H; Sakurai, Y; Takata, T; Watanabe, T; Kawabata, S; Suzuki, M; Masunaga, S-I; Taki, K; Akabori, K; Watanabe, K; Ono, K

    2017-05-01

    The real-time detection of epithermal neutrons forms an important aspect of boron neutron capture therapy. In this context, we developed an epithermal neutron detector based on the combination of a small Eu:LiCaAlF 6 scintillator and a quartz fiber in order to fulfill the irradiation-field requirements for boron neutron capture therapy. The irradiation test is performed with the use of a reactor-based neutron source. The thermal and epithermal neutron sensitivities of our epithermal neutron detector are estimated to be 9.52 × 10 -8 ± 1.59 × 10 -8 cm 2 and 1.20 × 10 -6 cm 2 ± 8.96 × 10 -9 cm 2 , respectively. We also subject the developed epithermal neutron detector to actual irradiation fields, and we confirm that the epithermal neutron flux can be measured in realtime.

  13. On the absolute calibration of a DT fusion neutron yield diagnostic

    Directory of Open Access Journals (Sweden)

    Ruiz C.L.

    2013-11-01

    Full Text Available Recent advances in Inertial Confinement Fusion (ICF experiments at Lawrence Livermore National Laboratory's National Ignition Facility (NIF have underscored the need for accurate total yield measurements of DT neutrons because yield measurements provide a measure of the predicted performance of the experiments. Future gas-puff DT experiments at Sandia National Laboratory's Z facility will also require similar measurements. For ICF DT experiments, the standard technique for measuring the neutron (14.1 MeV yield, counts the activity (counts/minute induced in irradiated copper samples. This activity occurs by the 63Cu(n,2n62Cu reaction where 62Cu decays by positrons (β+ with a half-life of 9.67 minutes. The calibrations discussed here employ the associated-particle method (APM, where the α (4He particles from the T(d,n4He reaction are measured to infer neutron fluxes on a copper sample. The flux induces 62Cu activity, measured in a coincidence counting system. The method leads to a relationship between a DT neutron yield and copper activity known as the F-factor. The goal in future experiments is to apply this calibration to measure the yield at NIF with a combined uncertainty approaching 5%.

  14. Real time neutron image processing system in NRF

    International Nuclear Information System (INIS)

    Lee, Yong Deok; Kim, Yi Kyung; Nam, Ki Yong; Lee, Chang Hee; Chang, Jong Hwa

    1999-01-01

    The neutron radiography facility was installed at the neutron radiography beam tube of the HANARO research reactor. The NRF is used for the nondestructive test to inspect and evaluate the material defect and homogeneity by detecting the transmitted neutron image in the nuclear as well as non-nuclear industry. To analyze the dynamical neutron image effectively and efficiently, the real-time image processing system was developed in background subtraction, normalization, geometry correction and beam uniformity, contrast control, filtering. The image quality test and dimension measurements were performed for the neutron beam purity and sensitivity indication. The NRF beam condition represents the highest beam quality for neutron radiography.

  15. Measuring neutron yield and ρR anisotropies with activation foils at the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Bleuel D.L.

    2013-11-01

    Full Text Available Neutron yields at the National Ignition Facility (NIF are measured with a suite of diagnostics, including activation of ∼20–200 g samples of materials undergoing a variety of energy-dependent neutron reactions. Indium samples were mounted on the end of a Diagnostic Instrument Manipulator (DIM, 25–50 cm from the implosion, to measure 2.45 MeV D-D fusion neutron yield. The 336.2 keV gamma rays from the 4.5 hour isomer of 115mIn produced by (n,n′ reactions are counted in high-purity germanium detectors. For capsules producing D-T fusion reactions, zirconium and copper are activated via (n,2n reactions at various locations around the target chamber and bay, measuring the 14 MeV neutron yield to accuracies on order of 7%. By mounting zirconium samples on ports at nine locations around the NIF chamber, anisotropies in the primary neutron emission due to fuel areal density asymmetries can be measured to a relative precision of 3%.

  16. Radial plasma profile and neutron yield in an adiabatic trap with fast atom injection

    International Nuclear Information System (INIS)

    Panov, D.A.

    1988-01-01

    Radial profiles of ion densities depending on two dimensionless parameters, which values are determined by the trap, plasma and injected beam parameters are found in dimensionless units for a plasma generated by fast atom injection in an adiabatic trap. The calculated profiles are used for determining the neutron yield. Simple approximated dimensional relations permitting to estimate quickly neutron yield, required injection power, flux of charge exchange atoms on the wall around the plasma in a wide energy range of injected atoms, trap field modulud, injection angle, trap radius and length are determined. The energetic efficiency of neutron production is estimated and it is shown that it grows with the injection energy. 7 refs.; 7 figs

  17. JD3 - Neutron Stars: Timing in Extreme Environments

    NARCIS (Netherlands)

    Belloni, Tomaso M.; Méndez, Mariano; Zhang, Chengmin

    2009-01-01

    The space-time around Neutron Stars is indeed an extreme environment. Whether they are in accreting binary systems, isolated or in non-accreting binaries (perhaps with another Neutron Star), Neutron Stars provide a window onto physical processes not accessible by other means. In particular, the

  18. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators

    International Nuclear Information System (INIS)

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. (authors)

  19. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

    Science.gov (United States)

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Time-resolved Neutron Powder Diffraction

    International Nuclear Information System (INIS)

    Pannetier, J.

    1986-01-01

    The use of a high-flux neutron source together with a large position sensitive detector (PSD) allows a powder diffraction pattern to be recorded at a time-scale of a few minutes so that crystalline systems under non-equilibrium conditions may now conveniently be investigated. This introduces a new dimension into powder diffraction (the time and transient phenomena like heterogeneous chemical reactions can now be easily studied. The instrumental parameters relevant for the design of such time-dependent experiments are briefly surveyed and the current limits of the method are discussed. The applications are illustrated by two kinds of experiment in the field of inorganic solid state chemistry: true kinetic studies of heterogeneous chemical reactions and thermodiffractometry experiments

  1. Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF.

    Science.gov (United States)

    Casey, D T; Frenje, J A; Gatu Johnson, M; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Knauer, J P; Meyerhofer, D D; Sangster, T C; Bionta, R M; Bleuel, D L; Döppner, T; Glenzer, S; Hartouni, E; Hatchett, S P; Le Pape, S; Ma, T; MacKinnon, A; McKernan, M A; Moran, M; Moses, E; Park, H-S; Ralph, J; Remington, B A; Smalyuk, V; Yeamans, C B; Kline, J; Kyrala, G; Chandler, G A; Leeper, R J; Ruiz, C L; Cooper, G W; Nelson, A J; Fletcher, K; Kilkenny, J; Farrell, M; Jasion, D; Paguio, R

    2012-10-01

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  2. Determination the total neutron yields of several semiconductor compounds using various alpha emitters

    Science.gov (United States)

    Abdullah, Ramadhan Hayder; Sabr, Barzan Nehmat

    2016-03-01

    In the present work, the cross-sections of (α,n) reactions available in the literature as a function of α-particle energies for light and medium elements have been rearranged for α-particle energies from near threshold up to 10 MeV in steps of (0.050MeV) using the (Excel and Matlab) computer programs. The obtained data were used to calculate the neutron yields (n/106α) using the quick basic-computer program (Simpson Rules). The stopping powers of alpha particle energies from near threshold to 10 MeV for light and medium elements such as (nat.Be,10B,11B,13C,14N,nat.O,nat.F,nat.Mg,nat.Al,29Si,30Si, nat.P and 46.48Ti) have been calculated using the Zeigler formula. The kinetic energies (Tα) and the branching ratios of each α-emitters such as (211Bi, 210Po, 211Po, 215Po, 217At, 218Rn, 219Rn, 222Rn, 224Ra, 226Ra, 215Th, 228Th, 232U, 234U, 236U, 238U, 238Pu, 239Pu, 241Am, 245Es, 252Fm, 254Fm, 256Fm, 257Fm and 257Md) are taken into consideration to calculate the mean kinetic energy . The polynomial expressions were used to fitting the calculated weighted average of neutron yields (n/106α) for natural light and medium elements such as (Be, B, C, N, O, F, Mg, Al, Si, P and Ti) to determine the adopted neutron yields from the best fitting equation with minimum (CHISQ) at mean kinetic energies of various α-emitters. The total neutron yields (n/s/gx/ppmi) of the mentioned natural light and medium elements have been calculated using the adopted neutron yields (n/106α) from the fitting equations at mean kinetic energies of various α-emitters. The total neutron yields (n/s/gα-emitters/gcompounds) of semiconductor compounds such as (AlN, AlP, BN, BP, SiC, TiO2, BeSiN2, MgCN2, MgSiN2 and MgSiP2) have been calculated by mixing (1gram) of compounds with (1gram) of pure α-emitters using the quick basic computer program. The aim of the present work is to constructed and fabricate the neutron sources theoretically

  3. Fusion neutron energy spectra measured by time-of-flight spectrometers

    CERN Document Server

    Elevant, T

    2002-01-01

    Evaluation of measured neutron energy spectra provides information on the central ion velocity distribution; e.g. ion temperature and fast ions induced by NBI- or ICR-heating and on impurity content in fusion grade plasmas. Two self-contained high-energy resolution time-of-flight neutron spectrometers have been used at the JET- and JT-60U tokamaks during DD-operation. In the spectrometers, each neutron undergoes (n, p) elastic scattering in two sets of hydrogen based scintillators. Elapsed time between the two scatter events is measured and the energy of the neutron is evaluated. Interpretation of acquired data together with results obtained from other diagnostics yields information on central plasma parameters. Deduced ion temperatures, fast ion fractional contributions during auxiliary NBI- and ICR-heating and impurity content is presented. In general, good agreement is obtained between neutron data and data from other diagnostics.

  4. Monte Carlo analysis of accelerator-driven systems studies on spallation neutron yield and energy gain

    CERN Document Server

    Hashemi-Nezhad, S R; Westmeier, W; Bamblevski, V P; Krivopustov, M I; Kulakov, B A; Sosnin, A N; Wan, J S; Odoj, R

    2001-01-01

    The neutron yield in the interaction of protons with lead and uranium targets has been studied using the LAHET code system. The dependence of the neutron multiplicity on target dimensions and proton energy has been calculated and the dependence of the energy amplification on the proton energy has been investigated in an accelerator-driven system of a given effective multiplication coefficient. Some of the results are compared with experimental findings and with similar calculations by the DCM/CEM code of Dubna and the FLUKA code system used in CERN. (14 refs).

  5. Analyzer of neutron flux in real time

    International Nuclear Information System (INIS)

    Rojas S, A.S.; Carrillo M, R.A.; Balderas, E.G.

    1999-01-01

    With base in the study of the real signals of neutron flux of instability events occurred in the Laguna Verde nuclear power plant where the nucleus oscillation phenomena of the reactor are in the 0 to 2.5 Hz range, it has been seen the possibility about the development a surveillance and diagnostic equipment capable to analyze in real time the behavior of nucleus in this frequencies range. An important method for surveillance the stability of the reactor nucleus is the use of the Power spectral density which allows to determine the frequencies and amplitudes contained in the signals. It is used an instrument carried out by LabVIEW graphic programming with a data acquisition card of 16 channels which works at Windows 95/98 environment. (Author)

  6. Tests and Calibration of the NIF Neutron Time of Flight Detectors

    International Nuclear Information System (INIS)

    Ali, Z.A.; Glebov, V.Yu.; Cruz, M.; Duffy, T.; Stoeckl, C.; Roberts, S.; Sangster, T.C.; Tommasini, R.; Throop, A; Moran, M.; Dauffy, L.; Horsefield, C.

    2008-01-01

    The National Ignition Facility (NIF) Neutron Time of Flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD (D = deuterium, T = tritium, H = hydrogen) implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 10 9 to 2 x 10 19 . The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 m and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory (LLNL). Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detectors tests and calibration will be presented

  7. On the yield of cold and ultracold neutrons for liquid hydrogen at low temperatures near the melting point

    CERN Document Server

    Morishima, N

    1999-01-01

    The neutron scattering cross sections for liquid hydrogen in the temperature range from the melting point to the boiling point are calculated. It is shown that lowering the temperature results in a significant increase in the yield of cold neutrons: for instance, a 44% increase for an incident neutron energy of 19.4 meV. The major cause of this increment is the para-to-ortho transition of a hydrogen molecule though accompanied by an appreciable increase in the density. The results of the cold- and ultracold-neutron yields are discussed in connection with the experimental results of Altarev et al. at the WWR-M reactor.

  8. Propagation of Neutron Cross Section, Fission Yield, and Decay Data Uncertainties in Depletion Calculations

    Science.gov (United States)

    Martinez, J. S.; Zwermann, W.; Gallner, L.; Puente-Espel, F.; Cabellos, O.; Velkov, K.; Hannstein, V.

    2014-04-01

    Propagation of nuclear data uncertainties in reactor calculations is interesting for design purposes and libraries evaluation. Previous versions of the GRS XSUSA library propagated only neutron cross section uncertainties. We have extended XSUSA uncertainty assessment capabilities by including propagation of fission yields and decay data uncertainties due to the their relevance in depletion simulations. We apply this extended methodology to the UAM6 PWR Pin-Cell Burnup Benchmark, which involves uncertainty propagation through burnup.

  9. Determination of the optimum pressure for neutron yield with d2, in the PF facility dena

    International Nuclear Information System (INIS)

    Siahpoush, V.; Khorram, C.; Sobhanian, S.; Hamzeh Fafreshi, M. A.

    2003-01-01

    Using physical model, which describes the dynamics of plasma in the Filipov type plasma focus, we have simulated the pinch current for different voltages and pressures. The results show that for a specific voltage, there is an optimum pressure for which the pinch current has maximum value. A comparison between the simulated and the experimental data from dena shows that the maximum values of pinch current are obtained at the same pressure for which the maximum neutron yield is observed

  10. National Ignition Facility (NIF) Neutron time-of-flight (nTOF) Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lerche, R A; Glebov, V Y; Moran, M J; McNaney, J M; Kilkenny, J D; Eckart, M; Zacharias, R A; Haslam, J J; Clancy, T J; Yeoman, M F; Warwas, D P; Sangster, T C; Stoeckl, C; Knauer, J; Horsfield, C J

    2010-05-13

    The first three of eighteen neutron time-of-flight (nTOF) channels have been installed at the National Ignition Facility (NIF). The role of these detectors includes yield, temperature, and bang time measurements. This article focuses on nTOF data analysis and quality of results obtained for the first set of experiments to use all 192 NIF beams. Targets produced up to 2 x 10{sup 10} 2.45-MeV neutrons for initial testing of the nTOF detectors. Differences in neutron scattering at the OMEGA laser facility where the detectors were calibrated and at NIF result in different response functions at the two facilities. Monte Carlo modeling shows this difference. The nTOF performance on these early experiments indicates the nTOF system with its full complement of detectors should perform well in future measurements of yield, temperature, and bang time.

  11. Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

    Science.gov (United States)

    Du, Rong; Tian, Haolai; Zuo, Taisen; Tang, Ming; Yan, Lili; Zhang, Junrong

    2017-09-01

    Small-angle neutron scattering (SANS) is an experimental technique to detect material structures in the nanometer to micrometer range. The solution of the structural model constructed from SANS strongly depends on the accuracy of the reduced data. The time-of-flight (TOF) SANS data are dependent on the wavelength of the pulsed neutron source. Therefore, data reduction must be handled very carefully to transform measured neutron events into neutron scattering intensity. In this study, reduction algorithms for TOF SANS data are developed and optimized using simulated data from a virtual neutron experiment. Each possible effect on the measured data is studied systematically, and suitable corrections are performed to obtain high-quality data. This work will facilitate scientific research and the instrument design at China Spallation Neutron Source.

  12. Time-gated energy-selected cold neutron radiography

    CERN Document Server

    McDonald, T E; Claytor, T N; Farnum, E H; Greene, G L; Morris, C

    1999-01-01

    A technique is under development at the Los Alamos Neutron Science Center (LANSCE), Manuel Lujan Jr. Neutron Scattering Center (Lujan Center) for producing neutron radiography using only a narrow energy range of cold neutrons. The technique, referred to as time-gated energy-selected (TGES) neutron radiography, employs the pulsed neutron source at the Lujan Center with time of flight to obtain a neutron pulse having an energy distribution that is a function of the arrival time at the imager. The radiograph is formed on a short persistence scintillator and a gated, intensified, cooled CCD camera is employed to record the images, which are produced at the specific neutron energy range determined by the camera gate. The technique has been used to achieve a degree of material discrimination in radiographic images. For some materials, such as beryllium and carbon, at energies above the Bragg cutoff the neutron scattering cross section is relatively high while at energies below the Bragg cutoff the scattering cross ...

  13. Characterization of a diamond detector to be used as neutron yield monitor during the in-vessel calibration of JET neutron detectors in preparation of the DT experiment

    International Nuclear Information System (INIS)

    Pillon, Mario; Angelone, Maurizio; Batistoni, Paola; Loreti, Stefano; Milocco, Alberto

    2016-01-01

    Highlights: • A diamond detector has been characterized for use as neutron yield monitor of a portable 14 MeV neutron generator. • The system will be used for the 14 MeV calibration of JET neutron detector. • The results and the performances of the monitor are very satisfactory in term of accuracy and reliability. - Abstract: A new Deuterium-Tritium (DT) campaign is planned at JET. An accurate calibration for the 14 MeV neutron yield monitors is necessary. In order to perform the calibration a 14 MeV Neutron Generator with suitable intensity (∼10 8 n/s) will be used. Due to the intensity change during the Neutron Generator lifetime it would be necessary to monitor continuously the neutron emission intensity during the calibration using a compact detector attached to it. A high quality diamond detector has been chosen as one of the monitors. This detector has been fully characterized at the 14 MeV Frascati Neutron Generator facility. The characterization procedure and the resulting 14 MeV neutron response of the detector are described in this paper together with the obtained uncertainties.

  14. Investigation of the fission yields of the fast neutron-induced fission of 233U

    International Nuclear Information System (INIS)

    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 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 γ-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 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)

  15. Time-resolved Neutron-gamma-ray Data Acquisition for in Situ Subsurface Planetary Geochemistry

    Science.gov (United States)

    Bodnarik, Julie G.; Burger, Dan Michael; Burger, A.; Evans, L. G.; Parsons, A. M.; Schweitzer, J. S.; Starr R. D.; Stassun, K. G.

    2013-01-01

    The current gamma-ray/neutron instrumentation development effort at NASA Goddard Space Flight Center aims to extend the use of active pulsed neutron interrogation techniques to probe the subsurface elemental composition of planetary bodies in situ. Previous NASA planetary science missions, that used neutron and/or gamma-ray spectroscopy instruments, have relied on neutrons produced from galactic cosmic rays. One of the distinguishing features of this effort is the inclusion of a high intensity 14.1 MeV pulsed neutron generator synchronized with a custom data acquisition system to time each event relative to the pulse. With usually only one opportunity to collect data, it is difficult to set a priori time-gating windows to obtain the best possible results. Acquiring time-tagged, event-by-event data from nuclear induced reactions provides raw data sets containing channel/energy, and event time for each gamma ray or neutron detected. The resulting data set can be plotted as a function of time or energy using optimized analysis windows after the data are acquired. Time windows can now be chosen to produce energy spectra that yield the most statistically significant and accurate elemental composition results that can be derived from the complete data set. The advantages of post-processing gamma-ray time-tagged event-by-event data in experimental tests using our prototype instrument will be demonstrated.

  16. Simplified geometric model for the calculation of neutron yield in an accelerator of 18 MV for radiotherapy; Modelo geometrico simplificado para el calculo del rendimiento de neutrones en un acelerador de 18 MV para radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L.C.; Balcazar G, M. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Francois L, J.L. [FI-UNAM, 04510 Mexico D.F. (Mexico); Azorin N, J. [UAM-I, 09340 Mexico D.F. (Mexico)

    2008-07-01

    The results of the neutrons yield in different components of the bolster of an accelerator Varian Clinac 2100C of 18 MV for radiotherapy are presented, which contribute to the radiation of flight of neutrons in the patient and bolster planes. For the calculation of the neutrons yield, a simplified geometric model of spherical cell for the armor-plating of the bolster with Pb and W was used. Its were considered different materials for the Bremsstrahlung production and of neutrons produced through the photonuclear reactions and of electro disintegration, in function of the initial energy of the electron. The theoretical result of the total yield of neutrons is of 1.17x10{sup -3} n/e, considering to the choke in position of closed, in the patient plane with a distance source-surface of 100 cm; of which 15.73% corresponds to the target, 58.72% to the primary collimator, 4.53% to the levelled filter of Fe, 4.87% to the levelled filter of Ta and 16.15% to the closed choke. For an initial energy of the electrons of 18 MeV, a half energy of the neutrons of 2 MeV was obtained. The calculated values for radiation of experimental neutrons flight are inferior to the maxima limit specified in the NCRP-102 and IEC-60601-201.Ed.2.0 reports. The absorbed dose of neutrons determined through the measurements with TLD dosemeters in the isocenter to 100 cm of the target when the choke is closed one, is approximately 3 times greater that the calculated for armor-plating of W and 1.9 times greater than an armor-plating of Pb. (Author)

  17. Time dispersion in large plastic scintillation neutron detectors

    International Nuclear Information System (INIS)

    De, A.; Dasgupta, S.S.; Sen, D.

    1993-01-01

    Time dispersion (TD) has been computed for large neutron detectors using plastic scintillators. It has been shown that TD seen by the PM tube does not necessarily increase with incident neutron energy, a result not fully in agreement with the usual finding

  18. Real-time thermal neutron radiographic detection systems

    International Nuclear Information System (INIS)

    Berger, H.; Bracher, D.A.

    1976-01-01

    Systems for real-time detection of thermal neutron images are reviewed. Characteristics of one system are presented; the data include contrast, resolution and speed of response over the thermal neutron intensity range 2.5 10 3 n/cm 2 -sec to 10 7 n/cm 2 -sec

  19. Fission-product yields for thermal-neutron fission of curium-243

    International Nuclear Information System (INIS)

    Breederland, D.G.

    1982-01-01

    Cumulative fission yields for 25 gamma rays emitted during the decay of 23 fission products produced by thermal-neutron fission of 243 Cm have been determined. Using Ge(Li) spectroscopy, 33 successive pulse-height spectra of gamma rays emitted from a 77-ng sample of 243 Cm over a period of approximately two and one-half months were analyzed. Reduction of these spectra resulted in the identification and matching of gamma-ray energies and half-lives to specific radionuclides. Using these results, 23 cumulative fission-product yields were calculated. Only those radionuclides having half-lives between 6 hours and 65 days were observed. Prior to this experiment, no fission-product yields had been recorded for 243 Cm

  20. Yields of products from thermal neutron-induced fission of 235U

    International Nuclear Information System (INIS)

    Rudstam, G.; Aagaard, P.; Ekstroem, B.; Lund, E.; Goektuerk, H.; Zwicky, H.U.

    1990-01-01

    A comprehensive study has been carried out of the yield pattern of fission products formed in thermal neutron-induced fission of 235 U. An isotope separator on-line a nuclear reactor was used for rapid separation of the fission products. At a target temperature of 2400deg C all fission elements, with the exception of the little volatile transition elements zirconium, niobium, molybdenum, technetium, ruthenium, and rhodium, are released. Their isotopes are then available for study which means that a very complete mapping of the yield distribution is within reach. In the analysis the delay between production and measurement and the overall separator efficiency for three consecutive elements - the one under study and its parent and grandparent - are taken into account. Independent and/or cumulative yields have been obtained for 195 nuclear species, among them 83 isomeric states. (orig.)

  1. Independent yield pattern in thermal neutron-induced fission of 235U

    International Nuclear Information System (INIS)

    Rudstam, G.; Ekstroem, B.; Lund, E.

    1989-01-01

    A comprehensive study has been carried out of the yield pattern of fission products formed in thermal neutron-induced fission of 235 U. An isotope separator on-line a nuclear reactor was used for rapid separation of the fission products. At a target temperature of 2,400C all fission elements, with the exception of the little volatile transition elements zirconium, niobium, molybdenum, technetium, ruthenium, and rhodium, are released. Their isotopes are then available for study which means that a very complete mapping of the yield distribution is within reach. In the analysis the delay between production and measurement and the overall separator efficiency for three consecutive elements - the one under study and its parent and grandparent - are taken into account. Independent and/or cumulative yields have been obtained for 191 nuclear species, among them 79 isomeric states

  2. Preconcentration method using an activatable yield tracer for neutron activation analysis

    International Nuclear Information System (INIS)

    Tsukada, Masamichi; Yamamoto, Daijiro; Endo, Kazutoyo; Nakahara, Hiromichi

    1991-01-01

    Previously, the use of an enriched stable isotope as an activatable yield tracer in preconcentration steps has been tested by use of commercially available enriched 116 Cd and 156 Dy for biological standard reference materials. In the present work, this method has been further applied to the determination of lanthanoid contents in various kinds of samples: one coal fly-ash, three Japanese standard rocks, and eight standard soils. Samples were decomposed by alkali fusion in the preconcentration step. Thirteen elements were determined for coal fly-ash and soil samples, and 14 elements for rocks. The data obtained for coal fly-ash and standard rocks are compared with the data reported in literature. The data for soil samples have been newly determined in the present work. The ordinary instrumental neutron activation analysis and radiochemical neutron activation analysis were also performed to confirm the accuracy and usefulness of the present method. (author) 10 refs.; 4 tabs

  3. Measurements of neutron yields and radioactive isotope transmutation in collisions of relativistic ions with heavy nuclei

    International Nuclear Information System (INIS)

    Brandt, R.

    1999-01-01

    The paper is based on the report presented at the 85th Session of the JINR Scientific Council. Some aspects of experimental studies of the problem of reprocessing radioactive wastes by means of transmutation in the fields of neutrons generated by relativistic particle beams are discussed. Research results on measurement of neutron yields in heavy targets irradiated with protons at energies up to 3.7 GeV as well as transmutation cross sections of some fission products (I-129) and actinides (Np-237) using radiochemical methods, activation detectors, solid state nuclear track detectors and other methods are presented. Experiments have been performed at the accelerator complex of the Laboratory of High Energies, JINR. Analogous results obtained by other research groups are also discussed

  4. A proton-recoil neutron spectrometer for time-dependent ion temperatures on the National Ignition Facility

    International Nuclear Information System (INIS)

    Murphy, T.J.

    1995-01-01

    Ion temperatures from inertial confinement fusion targets are usually determined by measuring the Doppler broadening of the neutron spectrum using the time-of-flight method. Measurement systems are generally designed so that the contribution of the duration of neutron production (∼100 ps) to the width of the neutron signal is negligible. This precludes the possibility of time-dependent ion temperature. If, however, one could measure the neutron energy and arrival time at a detector independently, then time-dependent neutron spectra could be obtained, and ion temperature information deduced. A concept utilizing a proton-recoil neutron spectrometer has been developed in which recoil protons from a small plastic foil are measured. From the energy, arrival time, and recoil angle of the recoil proton, the birth time and energy of the incident neutron can be deduced. The sensitivity of the system is low, but the higher anticipated neutron yields from the proposed National Ignition Facility may make the technique feasible. Large scintillator arrays currently in use on the Nova facility for neutron spectral measurements consist of ∼1,000 channels and detect between 50 and 500 counts for typical time-integrated data. Time-dependent results would then require about an order of magnitude larger system. Key issues for making this system feasible will be keeping the cost per channel low while allowing adequately time (∼ 50 ps), energy (20 keV), and angular resolution (2 mrad) for each of the proton detectors

  5. Real-Time Active Cosmic Neutron Background Reduction Methods

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  6. Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases

    Science.gov (United States)

    Bang, W.; Barbui, M.; Bonasera, A.; Quevedo, H. J.; Dyer, G.; Bernstein, A. C.; Hagel, K.; Schmidt, K.; Gaul, E.; Donovan, M. E.; Consoli, F.; De Angelis, R.; Andreoli, P.; Barbarino, M.; Kimura, S.; Mazzocco, M.; Natowitz, J. B.; Ditmire, T.

    2013-09-01

    We report on experiments in which the Texas Petawatt laser irradiated a mixture of deuterium or deuterated methane clusters and helium-3 gas, generating three types of nuclear fusion reactions: D(d,3He)n, D(d,t)p, and 3He(d,p)4He. We measured the yields of fusion neutrons and protons from these reactions and found them to agree with yields based on a simple cylindrical plasma model using known cross sections and measured plasma parameters. Within our measurement errors, the fusion products were isotropically distributed. Plasma temperatures, important for the cross sections, were determined by two independent methods: (1) deuterium ion time of flight and (2) utilizing the ratio of neutron yield to proton yield from D(d,3He)n and 3He(d,p)4He reactions, respectively. This experiment produced the highest ion temperature ever achieved with laser-irradiated deuterium clusters.

  7. Thick target neutron yields and spectra from the Li(d,xn) reaction at 35 MeV

    International Nuclear Information System (INIS)

    Johnson, D.L.; Mann, F.M.; Watson, J.W.; Brady, F.P.; Ullmann, J.L.; Romero, J.L.; Castaneda, C.M.; Zanelli, C.I.; Wyckoff, W.G.

    1980-05-01

    Measurements were performed using a 35 MeV deuteron beam from the isochronous cyclotron at the University of California at Davis. Data were obtained using the time-of-flight technique with an NE213 liquid scintillator. One set of measurements was used to observe the neutron spectrum from approx. 1 MeV to approx. 50 MeV, the maximum kinematically allowed energy. Observation angles were from 0 0 to 150 0 with emphasis on forward angles. Spectral data below approx. 1.5 MeV had poor accuracy. It was felt that a significant fraction of the neutron yield might lie at still lower energies, therefore a second set of measurements was performed to investigate the spectra to as low an energy as possible. Additional measurements were performed with a target enriched in the isotope 6 Li replacing the natural lithium target used in previous measurements. The main advantage of a 6 Li target is that the maximum kinematically allowed neutron energy is only about 38 MeV, hence reducing shielding requirements. The experiments, preliminary results, and future needs will be described

  8. Device for Writing the Time Tail from Spallation Neutron Pulses

    International Nuclear Information System (INIS)

    Langan, P.; Schoenborn, Benno P.; Daemen, L.L.

    2001-01-01

    Recent work at Los Alamos Neutron Science Center (LANSCE), has shown that there are large gains in neutron beam intensity to be made by using coupled moderators at spallation neutron sources. Most of these gains result from broadening the pulse-width in time. However the accompanying longer exponential tail at large emission times can be a problem in that it introduces relatively large beam-related backgrounds at high resolutions. We have designed a device that can reshape the moderated neutron beam by cutting the time-tail so that a sharp time resolution can be re-established without a significant loss in intensity. In this work the basic principles behind the tail-cutter and some initial results of Monte Carlo simulations are described. Unwanted neutrons in the long time-tail are diffracted out of the transmitted neutron beam by a nested stack of aperiodic multi-layers, rocking at the same frequency as the source. Nested aperiodic multi-layers have recently been used at X-ray sources and as band-pass filters in quasi-Laue neutron experiments at reactor neutron sources. Optical devices that rock in synchronization with a pulsed neutron beam are relatively new but are already under construction at LANSCE. The tail-cutter described here is a novel concept that uses existing multi-layer technology in a new way for spallation neutrons. Coupled moderators in combination with beam shaping devices offer the means of increasing flux whilst maintaining a sharp time distribution. A prototype device is being constructed for the protein crystallography station at LANSCE. The protein crystallography station incorporates a water moderator that has been judiciously coupled in order to increase the flux over neutron energies that are important to structural biology (3-80meV). This development in moderator design is particularly important because protein crystallography is flux limited and because conventional ambient water and cold hydrogen moderators do not provide relatively

  9. Millisecond time resolution neutron reflection from a nematic liquid crystal

    International Nuclear Information System (INIS)

    Dalgliesh, R.M.; Lau, Y.G.J.; Richardson, R.M.; Riley, D.J.

    2004-01-01

    The director reorientation of the liquid crystal 4,4' octyl cyanobiphenyl in the nematic phase under application of bursts of ac field have been observed using time-resolved neutron scattering in reflection geometry. The relaxation of the director has been shown to agree with existing theory, as determined by material and cell parameters. This result shows that it is possible to use neutron reflection measurements from buried interfaces to follow kinetic processes on a time scale comparable with the pulse length of the ISIS neutron source (20 ms)

  10. Neutron Diffraction Evaluation of Near Surface Residual Stresses at Welds in 1300 MPa Yield Strength Steel

    Directory of Open Access Journals (Sweden)

    Ebrahim Harati

    2017-05-01

    Full Text Available Evaluation of residual stress in the weld toe region is of critical importance. In this paper, the residual stress distribution both near the surface and in depth around the weld toe was investigated using neutron diffraction, complemented with X-ray diffraction. Measurements were done on a 1300 MPa yield strength steel welded using a Low Transformation Temperature (LTT consumable. Near surface residual stresses, as close as 39 µm below the surface, were measured using neutron diffraction and evaluated by applying a near surface data correction technique. Very steep surface stress gradients within 0.5 mm of the surface were found both at the weld toe and 2 mm into the heat affected zone (HAZ. Neutron results showed that the LTT consumable was capable of inducing near surface compressive residual stresses in all directions at the weld toe. It is concluded that there are very steep stress gradients both transverse to the weld toe line and in the depth direction, at the weld toe in LTT welds. Residual stress in the base material a few millimeters from the weld toe can be very different from the stress at the weld toe. Care must, therefore, be exercised when relating the residual stress to fatigue strength in LTT welds.

  11. Neutron Diffraction Evaluation of Near Surface Residual Stresses at Welds in 1300 MPa Yield Strength Steel.

    Science.gov (United States)

    Harati, Ebrahim; Karlsson, Leif; Svensson, Lars-Erik; Pirling, Thilo; Dalaei, Kamellia

    2017-05-29

    Evaluation of residual stress in the weld toe region is of critical importance. In this paper, the residual stress distribution both near the surface and in depth around the weld toe was investigated using neutron diffraction, complemented with X-ray diffraction. Measurements were done on a 1300 MPa yield strength steel welded using a Low Transformation Temperature (LTT) consumable. Near surface residual stresses, as close as 39 µm below the surface, were measured using neutron diffraction and evaluated by applying a near surface data correction technique. Very steep surface stress gradients within 0.5 mm of the surface were found both at the weld toe and 2 mm into the heat affected zone (HAZ). Neutron results showed that the LTT consumable was capable of inducing near surface compressive residual stresses in all directions at the weld toe. It is concluded that there are very steep stress gradients both transverse to the weld toe line and in the depth direction, at the weld toe in LTT welds. Residual stress in the base material a few millimeters from the weld toe can be very different from the stress at the weld toe. Care must, therefore, be exercised when relating the residual stress to fatigue strength in LTT welds.

  12. Characterizing Scintillator Response with Neutron Time-of-Flight

    Science.gov (United States)

    Palmisano, Kevin; Visca, Hannah; Caves, Louis; Wilkinson, Corey; McClow, Hannah; Padalino, Stephen; Forrest, Chad; Katz, Joe; Sangster, Craig; Regan, Sean

    2017-10-01

    Neutron scintillator diagnostics for ICF can be characterized using the neutron time-of-flight (nTOF) line on Geneseo's 1.7 MV Tandem Pelletron Accelerator. Neutron signals can be differentiated from gamma signals by employing a coincidence method called the associated particle technique (APT). In this measurement, a 2.1 MeV beam of deuterons incident on a deuterated polyethylene target produces neutrons via the d(d,n)3He reaction. A BC-412 plastic scintillator, placed at a scattering angle of 152º, detects 1.76 MeV neutrons in coincidence with the 2.56 MeV 3He ions at an associated angle of 10º. The APT is used to identify the 1.76 MeV neutron while the nTOF line determines its energy. By gating only mono-energetic neutrons, the instrument response function of the scintillator can be determined free from background scattered neutrons and gamma rays. Funded in part by a Grant from the DOE, through the Laboratory for Laser Energetics.

  13. Cumulative fission yield of Ce-148 produced by thermal-neutron fission of U-235

    International Nuclear Information System (INIS)

    Hasan, A.A.

    1984-12-01

    Cumulative fission yield of 148 cesium isotopes and some other fission products produced by thermal-neutron fission of 235 uranium is determined by Germanium/Lithium spectroscopic methods. The measuremets were done at Tsing-Hua open pool reactor using 3 to 4 mg of 93.15% enriched 235 uranium samples. Gamma rays are assigned to the responsible fission products by matching gamma rays energies and half lives. Fission rate is calculated by fission track method. Cumulative fission yields of 148 cesium, 90 krypton, 130 iodine, 144 lanthanum, 89 krypton, 136 xenon, 137 xenon and 140 cesium are calculated. This values are compared with previously predicted values and showed good agreement. 21 Ref

  14. Studying Kinetics with Neutrons Prospects for Time-Resolved Neutron Scattering

    CERN Document Server

    Eckold, Götz; Nagler, Stephen E

    2010-01-01

    Neutrons are extremely versatile probes for investigating structure and dynamics in condensed matter. Due to their large penetration depth, they are ideal for in-situ measurements of samples situated in sophisticated and advanced environments. The advent of new high-intensity neutron sources and instruments, as well as the development of new real-time techniques, allows the tracking of transformation processes in condensed matter on a microscopic scale. The present volume provides a review of the state of the art of this new and exciting field of kinetics with neutrons

  15. The neutron-proton charge-exchange amplitudes measured in the dp {yields} ppn reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mchedlishvili, D.; Chiladze, D. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); Barsov, S.; Dzyuba, A. [Petersburg Nuclear Physics Institute, High Energy Physics Department, Gatchina (Russian Federation); Carbonell, J. [Universite Paris-Sud, IN2P3-CNRS, Institut de Physique Nucleaire, Orsay Cedex (France); Dymov, S. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Universitaet Erlangen-Nuernberg, Physikalisches Institut II, Erlangen (Germany); Engels, R.; Gebel, R.; Hartmann, M.; Kacharava, A.; Kamerdzhiev, V.; Lehrach, A.; Lorentz, B.; Maier, R.; Ohm, H.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Seyfarth, H.; Stein, H.J.; Stockhorst, H.; Stroeher, H. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); Glagolev, V. [JINR, Laboratory of High Energies, Dubna (Russian Federation); Grigoryev, K.; Mikirtychyants, M.; Mikirtychyants, S.; Valdau, Yu. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); Petersburg Nuclear Physics Institute, High Energy Physics Department, Gatchina (Russian Federation); Goslawski, P.; Khoukaz, A.; Mielke, M.; Papenbrock, M. [Universitaet Muenster, Institut fuer Kernphysik, Muenster (Germany); Keshelashvili, I. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); University of Basel, Department of Physics, Basel (Switzerland); Komarov, V.; Kulikov, A. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Kulessa, P. [H. Niewodniczanski Institute of Nuclear Physics PAN, Krakow (Poland); Lomidze, N.; Nioradze, M.; Tabidze, M. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); Macharashvili, G. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Merzliakov, S. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Steffens, E. [Universitaet Erlangen-Nuernberg, Physikalisches Institut II, Erlangen (Germany); Trusov, S. [Forschungszentrum Rossendorf, Institut fuer Kern- und Hadronenphysik, Dresden (Germany); Uzikov, Yu. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); M. V. Lomonosov Moscow State University, Department of Physics, Moscow (Russian Federation); Wilkin, C. [UCL, Physics and Astronomy Department, London (United Kingdom)

    2013-04-15

    The unpolarised differential cross section and the two deuteron tensor analysing powers A{sub xx} and A{sub yy} of the vector dp {yields} {l_brace}pp{r_brace}{sub s}n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27GeV, data were obtained for small momentum transfers to a {l_brace}pp{r_brace}{sub s} system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C{sub x,x} and C{sub y,y} that were carried out in the vector dvector p {yields} {l_brace}pp{r_brace}{sub s}n reaction at 1.2 and 2.27GeV. The values obtained for the proton analysing power A{sub y}{sup p} also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. It is therefore clear that such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region. (orig.)

  16. Sensitivity of the 252Cf(sf neutron observables to the FREYA input yield functions Y(A, Z, TKE

    Directory of Open Access Journals (Sweden)

    Randrup Jørgen

    2017-01-01

    Full Text Available Within the framework of the fission event generator FREYA, we are studying the sensitivity of various neutron observables to the yield distribution Y (A,Z,TKE used as input to the code. Concentrating on spontaneous fission of 252Cf, we have sampled a large number of different input yield functions based on χ2 fits to the experimental data on Y (A and Y (TKE|A. For each of these input yield distributions, we then use FREYA to generate a large sample of complete fission events from which we extract a variety of neutron observables, including the multiplicity distribution, the associated correlation coefficients, and its factorial moments, the dependence of the mean neutron multiplicity on the total fragment kinetic energy TKE and on the fragment mass number A, the neutron energy spectrum, and the two-neutron angular correlation function. In this way, we can determine the variation of these observables resulting from the uncertainties in the experimental mesurements. The imposition of a constraint on the resulting mean neutron multiplicity reduces the variation of the calculated neutron observables and provides a means for shrinking the uncertainties associated with the measured data.

  17. Sensitivity of the 252Cf(sf) neutron observables to the FREYA input yield functions Y(A, Z, TKE)

    Science.gov (United States)

    Randrup, Jørgen; Talou, Patrick; Vogt, Ramona

    2017-09-01

    Within the framework of the fission event generator FREYA, we are studying the sensitivity of various neutron observables to the yield distribution Y (A,Z,TKE) used as input to the code. Concentrating on spontaneous fission of 252Cf, we have sampled a large number of different input yield functions based on χ2 fits to the experimental data on Y (A) and Y (TKE|A). For each of these input yield distributions, we then use FREYA to generate a large sample of complete fission events from which we extract a variety of neutron observables, including the multiplicity distribution, the associated correlation coefficients, and its factorial moments, the dependence of the mean neutron multiplicity on the total fragment kinetic energy TKE and on the fragment mass number A, the neutron energy spectrum, and the two-neutron angular correlation function. In this way, we can determine the variation of these observables resulting from the uncertainties in the experimental mesurements. The imposition of a constraint on the resulting mean neutron multiplicity reduces the variation of the calculated neutron observables and provides a means for shrinking the uncertainties associated with the measured data.

  18. Managment oriented analysis of sediment yield time compression

    Science.gov (United States)

    Smetanova, Anna; Le Bissonnais, Yves; Raclot, Damien; Nunes, João P.; Licciardello, Feliciana; Le Bouteiller, Caroline; Latron, Jérôme; Rodríguez Caballero, Emilio; Mathys, Nicolle; Klotz, Sébastien; Mekki, Insaf; Gallart, Francesc; Solé Benet, Albert; Pérez Gallego, Nuria; Andrieux, Patrick; Moussa, Roger; Planchon, Olivier; Marisa Santos, Juliana; Alshihabi, Omran; Chikhaoui, Mohamed

    2016-04-01

    The understanding of inter- and intra-annual variability of sediment yield is important for the land use planning and management decisions for sustainable landscapes. It is of particular importance in the regions where the annual sediment yield is often highly dependent on the occurrence of few large events which produce the majority of sediments, such as in the Mediterranean. This phenomenon is referred as time compression, and relevance of its consideration growths with the increase in magnitude and frequency of extreme events due to climate change in many other regions. So far, time compression has ben studied mainly on events datasets, providing high resolution, but (in terms of data amount, required data precision and methods), demanding analysis. In order to provide an alternative simplified approach, the monthly and yearly time compressions were evaluated in eight Mediterranean catchments (of the R-OSMed network), representing a wide range of Mediterranean landscapes. The annual sediment yield varied between 0 to ~27100 Mg•km-2•a-1, and the monthly sediment yield between 0 to ~11600 Mg•km-2•month-1. The catchment's sediment yield was un-equally distributed at inter- and intra-annual scale, and large differences were observed between the catchments. Two types of time compression were distinguished - (i) the inter-annual (based on annual values) and intra- annual (based on monthly values). Four different rainfall-runoff-sediment yield time compression patterns were observed: (i) no time-compression of rainfall, runoff, nor sediment yield, (ii) low time compression of rainfall and runoff, but high compression of sediment yield, (iii) low compression of rainfall and high of runoff and sediment yield, and (iv) low, medium and high compression of rainfall, runoff and sediment yield. All four patterns were present at inter-annual scale, while at intra-annual scale only the two latter were present. This implies that high sediment yields occurred in

  19. Determination of the fission products yields, lanthanide and yttrium, in the fission of 238U with neutrons of fission spectra

    International Nuclear Information System (INIS)

    Nicoli, I.G.

    1981-06-01

    A radiochemical investigation is performed to measure the cumulative fission product yields of several lantanides and yttrium nuclides in the 238 U by fission neutron spectra. Natural and depleted uranium are irradiated under the same experimental conditions in order to find a way to subtract the contribution of the 235 U fission. 235 U percentage in the natural uranium was 3.5 times higher than in the depleted uranium. Uranium oxides samples are irradiated inside the core of the Argonaut Reactor, at the Instituto de Engenharia Nuclear, and the lantanides and yttrium are chemically separated. The fission products gamma activities were detected, counted and analysed in a system constituted by a high resolution Ge(Li) detector, 4096 multichannel analyser and a PDP-11 computer. Cumulative yields for fission products with half-lives between 1 to 33 hours are measured: 93 Y, 141 La, 142 La, 143 Ce and 149 Nd. The chain total yields are calculated. The cumulative fission yields measured for 93 Y, 141 La, 142 La, 143 Ce and 149 Nd are 4,49%, 4,54%, 4,95%, 4,16% and 1,37% respectively and they are in good agreement with the values found in the literature. (Author) [pt

  20. Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

    Science.gov (United States)

    Tovesson, F.; Duke, D.; Geppert-Kleinrath, V.; Manning, B.; Mayorov, D.; Mosby, S.; Schmitt, K.

    2018-03-01

    Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. Experimental research of neutron yield and spectrum from deuterium gas-puff z-pinch on the GIT-12 generator at current above 2 MA

    Science.gov (United States)

    Cherdizov, R. K.; Fursov, F. I.; Kokshenev, V. A.; Kurmaev, N. E.; Labetsky, A. Yu; Ratakhin, N. A.; Shishlov, A. V.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Dudkin, G. N.; Garapatsky, A. A.; Padalko, V. N.; Varlachev, V. A.

    2017-05-01

    The Z-pinch experiments with deuterium gas-puff surrounded by an outer plasma shell were carried out on the GIT-12 generator (Tomsk, Russia) at currents of 2 MA. The plasma shell consisting of hydrogen and carbon ions was formed by 48 plasma guns. The deuterium gas-puff was created by a fast electromagnetic valve. This configuration provides an efficient mode of the neutron production in DD reaction, and the neutron yield reaches a value above 1012 neutrons per shot. Neutron diagnostics included scintillation TOF detectors for determination of the neutron energy spectrum, bubble detectors BD-PND, a silver activation detector, and several activation samples for determination of the neutron yield analysed by a Sodium Iodide (NaI) and a high-purity Germanium (HPGe) detectors. Using this neutron diagnostic complex, we measured the total neutron yield and amount of high-energy neutrons.

  3. Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA.

    Science.gov (United States)

    Glebov, V Yu; Forrest, C; Knauer, J P; Pruyne, A; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C; Caggiano, J A; Carman, M L; Clancy, T J; Hatarik, R; McNaney, J; Zaitseva, N P

    2012-10-01

    A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

  4. Space-time structure of neutron and X-ray sources in a plasma focus

    International Nuclear Information System (INIS)

    Bostick, W.H.; Nardi, V.; Prior, W.

    1977-01-01

    Systematic measurements with paraffin collimators of the neutron emission intensity have been completed on a plasma focus with a 15-20 kV capacitor bank (hollow centre electrode; discharge period T approximately 8 μs; D 2 filling at 4-8 torr). The space resolution was 1 cm or better. These data indicate that at least 70% of the total neutron yield originates within hot-plasma regions where electron beams and high-energy D beams (approximately > 0.1-1 MeV) are produced. The neutron source is composed of several (approximately > 1-10) space-localized sources of different intensity, each with a duration approximately less than 5 ns (FWHM). Localized neutron sources and hard (approximately > 100 keV) X-ray sources have the same time multiplicity and are usually distributed in two groups over a time interval 40-400 ns long. By the mode of operation used by the authors one group of localized sources (Burst II) is observed 200-400 ns after the other group (Burst I) and its space distribution is broader than for Burst I. The maximum intensity of a localized source of neutrons in Burst I is much higher than the maximum intensity in Burst II. Secondary reactions T(D,n) 4 He (from the tritium produced only by primary reactions in the same discharge; no tritium was used in filling the discharge chamber) are observed in a time coincidence with the strongest D-D neutron pulse of Burst I. The neutron signal from a localized source with high intensity has a relatively long tail of small amplitude (area tail approximately less than 0.2 X area peak). This tail can be generated by the D-D reactions of the unconfined part of an ion beam in the cold plasma. Complete elimination of scattered neutrons on the detector was achieved in these measurements. (author)

  5. Evolution of uranium fission-fragment charge yields with neutron number. Strong effect of multi-chance fission on yield asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, Peter [Los Alamos National Laboratory, Theoretical Division, Los Alamos, NM (United States); Schmitt, Christelle [CEA/DSM-CNRS/IN2P3, Grand Accelerateur National d' Ions Lourds, Caen (France)

    2017-01-15

    We use the Brownian shape-motion model, with its recent extensions, which allow modeling of odd-even staggering, to calculate the evolution of fission-fragment charge distributions with neutron number for the compound-system sequence {sup 234}U, {sup 236}U, {sup 238}U, and {sup 240}U. We compare to experimental data where available, for neutron- and electromagnetic-induced fission over a compound-nucleus excitation energy range from about 6 to 20 MeV. A notable result of the study is that the evolution of the location of the peak charge yield from Z = 54 in {sup 234}U towards Z = 52 in heavier isotopes, seen in the experimental data, is present also in the calculated yields. We further show that to describe yields at higher compound-nucleus excitation energies, then, already at 20 MeV, it is necessary to take multi-chance fission into account. (orig.)

  6. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF).

    Science.gov (United States)

    Frenje, J A; Hilsabeck, T J; Wink, C W; Bell, P; Bionta, R; Cerjan, C; Gatu Johnson, M; Kilkenny, J D; Li, C K; Séguin, F H; Petrasso, R D

    2016-11-01

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (T i ), yield (Y n ), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with a time resolution of ∼20 ps and energy resolution of ∼100 keV for total neutron yields above ∼10 16 . At lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ∼20 ps.

  7. Complete determination of neutron yield from 62 MeV protons on 9Be for the design of a low-power ADS

    International Nuclear Information System (INIS)

    Schillaci, M.; Alba, R.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; Finocchiaro, P.; Maiolino, C.; Santocito, D.; Osipenko, M.; Ripani, M.; Ricco, G.; Celentano, A.; Viberti, C.M.; Barbagallo, M.; Boccaccio, P.; Esposito, J.; Kostyukov, A.

    2014-01-01

    Beryllium is considered as a spallation target for 70 MeV proton beam in a project of a low-power Accelerator Driven System but the experimental data on neutron yield from Be target are scarce in this proton energy range. In this contribution we present the neutron production yield data measured at LNS (South National Laboratory - Italy) in an almost complete energy range and covering polar angles from 0 to 150 degrees. In this experiment the neutrons were produced by bombarding a 3 cm thick Be target with a 30-50 pA 62 MeV proton beam. The energy of the neutrons produced in the target were measured by the Time of Flight (ToF) technique and 8 neutron detectors were installed at 2 different distances on half-circles around the target. With this experimental set-up we have been able to -) achieve low background contribution, -) cover a large angular range moving the detectors at different angles from 0 to 150 degrees and -) cover a large energy range: from 0.5 to 2 MeV with near detectors and up to 62 MeV with far detectors. A general good agreement appears between our measured values with the few, incomplete existing data and with simulations

  8. Numerical solution of time dependent neutron transport equation. An application

    International Nuclear Information System (INIS)

    Barroso, Dalton Ellery Girao

    2000-01-01

    In this work we show a simple method to solve numerically the time-dependent neutron transport equation which is a simple extension of the numerical methods used to solve the time-independent static transport equation. This is possible because the time-discretized transport equation has the same form as the time-independent transport equation, with only some additional terms. A general outline of the method is given and used to evaluate the neutron flux in a microexplosion calculation of a highly compressed micro fissile system composed by DT-Pu-Be microsphere. (author)

  9. Test of time reversal symmetry with resonance neutron scattering

    International Nuclear Information System (INIS)

    Bowman, J.D.

    1986-01-01

    The possibility of searching for time-reversal symmetry violation in the scattering of epithermal neutrons from nuclei is discussed. Sources of both statistical and systematic errors are reviewed. A qualitative assessment of the size of the time reversal is made and a schematic design of an experiment to test time reversal symmetry is presented. (DWL) 10 refs., 1 fig

  10. Decay time and light yield measurements for plastic scintillating fibers

    International Nuclear Information System (INIS)

    Hawkes, C.M.; Kuhlen, M.; Milliken, B.; Stroynowski, R.; Wicklung, E.; Shimizu, T.; Shinji, O.

    1990-01-01

    We have studied light production and propagation in three different samples of plastic scintillating fibers manufactured by Kyowa Gas Co.: SCSF-81, SCSF-38 and SCSF-38 with a quenching additive. The emission time distribution is described phenomenologically by a fast two-step scintillation process and an additional slow component, the time constants of which are determined. The light yield from the fibers is measured as a function of distance for the two light components which propagate by total internal reflection from the core-clad interface and from the clad-air interface. We obtain the absolute light yield and attenuation lengths for the different fibers. (orig.)

  11. Research on the enhancement of the thermonuclear component of the neutron yield in pinch plasma focus devices

    International Nuclear Information System (INIS)

    Soto, L.; Silva, P.; Moreno, J.; Zambra, M.; Sylvester, G.; Pavez, C.; Castillo, F.

    2005-01-01

    The possibility to enhance the thermonuclear component against the beam target component of the neutron yield in plasma focus devices is being studied. At present, the Chilean Nuclear Energy Commission (CCHEN) has the experimental facilities and diagnostics in order to study plasma focus discharges in a wide range of energies (50J to 100kJ) and currents (40kA to MA). The devices at CCHEN are PF-50J, PF-400J, SPEED4 and SPEED2. As a part of our research program the possibility to study how to enhance the drive parameter (related with the plasma sheath velocity) and the plasma energy density and their role in the thermonuclear component of the neutron yield has been recently included. There are theoretical conjectures suggesting that increasing the drive parameter, it could be possible to increase the thermonuclear component of the neutron yield and to decrease the beam target component. Preliminary results of this research program are presented. (author)

  12. Neutron yield of thick {sup 12}C and {sup 13}C targets with 20 and 30 MeV deuterons

    Energy Technology Data Exchange (ETDEWEB)

    Lhersonneau, G.; Fadil, M. [GANIL, Caen (France); Malkiewicz, T. [CSC - IT Center for Science Ltd., Espoo (Finland); Gorelov, D.; Sorri, J.; Trzaska, W.H. [University of Jyvaskyla, Department of Physics, Jyvaskyla (Finland); Jones, P.; Ngcobo, P.Z. [iThemba Laboratory for Accelerator Based Science, Western Cape (South Africa)

    2016-12-15

    The neutron yield of thick targets of carbon, natural and enriched in {sup 13}C, bombarded by deuterons of 20 and 30 MeV has been measured by the activation method. The gain with respect to a {sup 12}C target is the same as with protons beams. The yield ratio is about 1.2 only and hardly can justify the use of a {sup 13}C target with deuteron beams. The data, apart from being of interest for the design of facilities where secondary neutron beams are used, provide a test case for calculations where both beam and target have a weakly bound neutron. The MCNPx code version 2.6.0, despite failing to reproduce some details of the experimental distributions, describes their global properties fairly well, especially the relative yields of the {sup 12}C and {sup 13}C targets. (orig.)

  13. MODICO, 1-D Time-Dependent 1 Group, 2 Group Neutron Diffusion with Delayed Neutron Precursors

    International Nuclear Information System (INIS)

    Camiciola, P.; Cundari, D.; Montagnini, B.

    1992-01-01

    1 - Description of program or function: The program solves the 1-D time-dependent one and two group coarse-mesh neutron diffusion equations, coupled with the equations for the delayed-neutron precursor, in plane geometry. 2 - Method of solution: The program is based on a simple coarse-mesh cubic approximation formula for the spatial behaviour of the flux inside each interval. An implicit scheme (the time-integrated method) is used for the advancement of the solution. The resulting (block three-diagonal) matrix is inverted at each time step by Thomas' method. 3 - Restrictions on the complexity of the problem: Number of coarse- mesh intervals LE 80; number of material regions LE 10; number of delayed-neutron precursor groups LE 10. Typical mesh sizes range from 5 cm to 20 cm; typical step length (non-prompt critical transients) ranges from 0.005 to 0.1 seconds

  14. Development of a geometry-compensated neutron time-of-flight detector for ICF applications with approximately 200 ps time response

    International Nuclear Information System (INIS)

    Murphy, T.J.; Lerche, R.A.

    1992-01-01

    Current-mode neutron time-of-flight detectors are used on Nova for neutron yield, ion temperature, and neutron emission time measurements. Currently used detectors are limited by the time response of the microchannel plate photomultiplier tubes used with the scintillators, scintillator decay time, scintillator thickness, and oscilloscope response time. A change in the geometry of the scintillator allows one to take advantage of the increased time resolution made possible by more advanced transient recorders and microchannel plate photomultiplier tubes. A prototype detector has been designed to incorporate these changes, and could potentially yield time resolution of less than 150 ps. Experimental results are presented demonstrating an ion temperature measurement of a direct-drive DT implosion on Nova

  15. An intrinsically safe facility for forefront research and training on nuclear technologies —Neutron yield from Be

    Science.gov (United States)

    Osipenko, M.; Ripani, M.; Ricco, G.; Celentano, A.; Viberti, C. M.; Alba, R.; Schillaci, M.; Cosentino, G.; Del Zoppo, A.; Di Pietro, A.; Figuera, P.; Finocchiaro, P.; Maiolino, C.; Santonocito, D.; Barbagallo, M.; Colonna, N.; Boccaccio, P.; Esposito, J.; Kostyukov, A.

    2014-04-01

    We describe a dedicated experiment to measure the neutron yield produced by a 62MeV proton beam impinging on a beryllium thick target. The energy was chosen as close as possible to the 70MeV considered for the ADS layout described in this Focus Point. The neutron yield and energy spectra were measured at several angles with respect to the beam direction. The experiment was performed at the INFN Laboratori Nazionali del Sud in Catania, Italy, using the proton beam delivered by the Superconducting Cyclotron (CS).

  16. An investigation of the neutron die-away time in passive neutron waste assay systems

    International Nuclear Information System (INIS)

    Baeten, P.; Bruggeman, M.; Carchon, R.

    1997-02-01

    Neutron coincidence counting applied to the assay of Pu-bearing waste is commonly based on the assumption that the time intervals between detected fission neutrons are distributed according to a mono-exponential function, often called Rossi-alpha distribution. The time constant of this characteristic exponential function is generally referred to as the die-away time of the detector assembly. In fact, the distribution of time intervals is derived from the more fundamental arrival time distribution, which is also assumed to obey a mono-exponential law. In view of the design studies for a neutron counter, the validity of this basic assumption was investigated. Different parameters such as neutron moderation and absorption in the sample and the presence of cadmium-lining were investigated by means of Monte Carlo simulations using the NCNP-code. The simulation results lead to the conclusion that the description of the arrival time function with a mono-exponential function with a sample-independent die-away time is only a first approximations. The mono-exponential decay is perturbed by a second time component related to the detection of neutrons already thermalized in the sample. This thermal component cannot be described by a mono-exponential function, but has a characteristic shape with a fast build-up reaching a maximum followed by a slow decay as a function of the arrival time. The relative contribution of this component strongly depends on the absorption and moderation of the sample matrix. This component cannot be described by a simple analytical expression involving sample related parameters. Hence, no direct useful information can be withdrawn from the arrival time probability function to characterize the waste matrix. The thermal component can be strongly suppressed by the use of cadmium-lining in front of the detector blocks simplifying the mathematical description of the arrival time probability function. Indications of the bias introduced by an inaccurate

  17. Time-correlated neutron analysis of a multiplying HEU source

    Energy Technology Data Exchange (ETDEWEB)

    Miller, E.C., E-mail: Eric.Miller@jhuapl.edu [Johns Hopkins University Applied Physics Laboratory, Laurel, MD (United States); Kalter, J.M.; Lavelle, C.M. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD (United States); Watson, S.M.; Kinlaw, M.T.; Chichester, D.L. [Idaho National Laboratory, Idaho Falls, ID (United States); Noonan, W.A. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD (United States)

    2015-06-01

    The ability to quickly identify and characterize special nuclear material remains a national security challenge. In counter-proliferation applications, identifying the neutron multiplication of a sample can be a good indication of the level of threat. Currently neutron multiplicity measurements are performed with moderated {sup 3}He proportional counters. These systems rely on the detection of thermalized neutrons, a process which obscures both energy and time information from the source. Fast neutron detectors, such as liquid scintillators, have the ability to detect events on nanosecond time scales, providing more information on the temporal structure of the arriving signal, and provide an alternative method for extracting information from the source. To explore this possibility, a series of measurements were performed on the Idaho National Laboratory's MARVEL assembly, a configurable HEU source. The source assembly was measured in a variety of different HEU configurations and with different reflectors, covering a range of neutron multiplications from 2 to 8. The data was collected with liquid scintillator detectors and digitized for offline analysis. A gap based approach for identifying the bursts of detected neutrons associated with the same fission chain was used. Using this approach, we are able to study various statistical properties of individual fission chains. One of these properties is the distribution of neutron arrival times within a given burst. We have observed two interesting empirical trends. First, this distribution exhibits a weak, but definite, dependence on source multiplication. Second, there are distinctive differences in the distribution depending on the presence and type of reflector. Both of these phenomena might prove to be useful when assessing an unknown source. The physical origins of these phenomena can be illuminated with help of MCNPX-PoliMi simulations.

  18. Time-correlated neutron analysis of a multiplying HEU source

    International Nuclear Information System (INIS)

    Miller, E.C.; Kalter, J.M.; Lavelle, C.M.; Watson, S.M.; Kinlaw, M.T.; Chichester, D.L.; Noonan, W.A.

    2015-01-01

    The ability to quickly identify and characterize special nuclear material remains a national security challenge. In counter-proliferation applications, identifying the neutron multiplication of a sample can be a good indication of the level of threat. Currently neutron multiplicity measurements are performed with moderated 3 He proportional counters. These systems rely on the detection of thermalized neutrons, a process which obscures both energy and time information from the source. Fast neutron detectors, such as liquid scintillators, have the ability to detect events on nanosecond time scales, providing more information on the temporal structure of the arriving signal, and provide an alternative method for extracting information from the source. To explore this possibility, a series of measurements were performed on the Idaho National Laboratory's MARVEL assembly, a configurable HEU source. The source assembly was measured in a variety of different HEU configurations and with different reflectors, covering a range of neutron multiplications from 2 to 8. The data was collected with liquid scintillator detectors and digitized for offline analysis. A gap based approach for identifying the bursts of detected neutrons associated with the same fission chain was used. Using this approach, we are able to study various statistical properties of individual fission chains. One of these properties is the distribution of neutron arrival times within a given burst. We have observed two interesting empirical trends. First, this distribution exhibits a weak, but definite, dependence on source multiplication. Second, there are distinctive differences in the distribution depending on the presence and type of reflector. Both of these phenomena might prove to be useful when assessing an unknown source. The physical origins of these phenomena can be illuminated with help of MCNPX-PoliMi simulations

  19. Tests of time reversal in neutron-nucleus scattering

    International Nuclear Information System (INIS)

    Bowman, J.D.

    1989-01-01

    Experiments to test time-reversal invariance are discussed. The experiments are based on observables constructed from the momentum and spin vectors of epithermal neutrons and from the spin of an aligned or polarized target. It is shown that the proposed tests are detailed balance tests of time-reversal invariance. The status of the experiments is briefly reviewed

  20. Tests of time reversal in neutron-nucleus scattering

    International Nuclear Information System (INIS)

    Bowman, J.D.

    1988-01-01

    Experiments to test time-reversal invariance are discussed. The experiments are based on observables constructed from the momentum and spin vectors of epithermal neutrons and from the spin of an aligned or polarized target. It is shown that the proposed tests are detailed balance tests of time-reversal invariance. The status of the experiments is briefly reviewed

  1. Real-time yield estimation based on deep learning

    Science.gov (United States)

    Rahnemoonfar, Maryam; Sheppard, Clay

    2017-05-01

    Crop yield estimation is an important task in product management and marketing. Accurate yield prediction helps farmers to make better decision on cultivation practices, plant disease prevention, and the size of harvest labor force. The current practice of yield estimation based on the manual counting of fruits is very time consuming and expensive process and it is not practical for big fields. Robotic systems including Unmanned Aerial Vehicles (UAV) and Unmanned Ground Vehicles (UGV), provide an efficient, cost-effective, flexible, and scalable solution for product management and yield prediction. Recently huge data has been gathered from agricultural field, however efficient analysis of those data is still a challenging task. Computer vision approaches currently face diffident challenges in automatic counting of fruits or flowers including occlusion caused by leaves, branches or other fruits, variance in natural illumination, and scale. In this paper a novel deep convolutional network algorithm was developed to facilitate the accurate yield prediction and automatic counting of fruits and vegetables on the images. Our method is robust to occlusion, shadow, uneven illumination and scale. Experimental results in comparison to the state-of-the art show the effectiveness of our algorithm.

  2. 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.

  3. Use of a large time-compensated scintillation detector in neutron time-of-flight measurements

    International Nuclear Information System (INIS)

    Goodman, C.D.

    1979-01-01

    A scintillator for neutron time-of-flight measurements is positioned at a desired angle with respect to the neutron beam, and as a function of the energy thereof, such that the sum of the transit times of the neutrons and photons in the scintillator are substantially independent of the points of scintillations within the scintillator. Extrapolated zero timing is employed rather than the usual constant fraction timing. As a result, a substantially larger scintillator can be employed that substantially increases the data rate and shortens the experiment time. 3 claims

  4. Shock Timing and Yield Sensitivity Studies for NIF Ignition Capsules

    International Nuclear Information System (INIS)

    Olson, Richard E.

    1999-01-01

    A cryogenic, β-layered NIF ignition capsule with a beryllium ablator that employs a BeO dopant (2% O) for opacity control is described. The design has an optimized yield of 12 MJ and uses a reduced drive hohlraum temperature pulse shape that peaks at ∼ 250 eV. Shock timing sensitivity calculations have been performed for this capsule design. Individual uncertainties of: (1) ∼200 ps in the timing of the foot pulse; (2) ∼5% in the x-ray flux of the foot pulse and first step; (3) ∼10% in the ablator EOS; or (4) ∼ 5 microm in the DT ice layer thickness each have a significant impact on thermonuclear yield. Combined uncertainties have greater impact than isolated, individual issues. For example, a combination of uncertainties of 200 ps in the foot + 2 eV in the foot + 5 microm in the DT thickness results in a calculation that produces only ∼ 1% of the original design yield. A second, more speculative, capsule concept utilizing a liquid DT ablator is also discussed. This design produces a 5 MJ yield in a 250 eV peak drive calculation

  5. Calibration of the time response functions of a quenched plastic scintillator for neutron time of flight

    Science.gov (United States)

    Chen, J. B.; Zheng, Z. J.; Peng, H. S.; Tang, C. H.; Zhang, B. H.; Ding, Y. K.; Chen, M.; Chen, H. S.; Li, C. G.; Wen, T. S.; Yu, R. Z.

    2002-10-01

    The time response functions of an ultrafast quenched plastic scintillation detector used to measure neutron time of flight spectra were calibrated by utilizing cosmic rays and implosion neutrons from DT-filled capsules at the Shenguang II laser facility. These sources could be regarded as δ function pulses due to their much narrower time widths than those of the time response functions of the detection system. The results showed that the detector responses to DT neutrons and to cosmic rays were 1.18 and 0.96 ns FWHM, respectively.

  6. Calibration of the time response functions of a quenched plastic scintillator for neutron time of flight

    CERN Document Server

    Chen, J B; Peng, H S; Tang, C H; Zhang, B H; Ding, Y K; Chen, M; Chen, H S; Li, C G; Wen, T S; Yu, R Z

    2002-01-01

    The time response functions of an ultrafast quenched plastic scintillation detector used to measure neutron time of flight spectra were calibrated by utilizing cosmic rays and implosion neutrons from DT-filled capsules at the Shenguang II laser facility. These sources could be regarded as delta function pulses due to their much narrower time widths than those of the time response functions of the detection system. The results showed that the detector responses to DT neutrons and to cosmic rays were 1.18 and 0.96 ns FWHM, respectively.

  7. Distillation time effect on lavender essential oil yield and composition.

    Science.gov (United States)

    Zheljazkov, Valtcho D; Cantrell, Charles L; Astatkie, Tess; Jeliazkova, Ekaterina

    2013-01-01

    Lavender (Lavandula angustifolia Mill.) is one of the most widely grown essential oil crops in the world. Commercial extraction of lavender oil is done using steam distillation. The objective of this study was to evaluate the effect of the length of the distillation time (DT) on lavender essential oil yield and composition when extracted from dried flowers. Therefore, the following distillation times (DT) were tested in this experiment: 1.5 min, 3 min, 3.75 min, 7.5 min, 15 min, 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, and 240 min. The essential oil yield (range 0.5-6.8%) reached a maximum at 60 min DT. The concentrations of cineole (range 6.4-35%) and fenchol (range 1.7-2.9%) were highest at the 1.5 min DT and decreased with increasing length of the DT. The concentration of camphor (range 6.6-9.2%) reached a maximum at 7.5-15 min DT, while the concentration of linalool acetate (range 15-38%) reached a maximum at 30 min DT. Results suggest that lavender essential oil yield may not increase after 60 min DT. The change in essential oil yield, and the concentrations of cineole, fenchol and linalool acetate as DT changes were modeled very well by the asymptotic nonlinear regression model. DT may be used to modify the chemical profile of lavender oil and to obtain oils with differential chemical profiles from the same lavender flowers. DT must be taken into consideration when citing or comparing reports on lavender essential oil yield and composition.

  8. Ion temperature measurement of indirectly-driven implosions using a geometry-compensated neutron time-of-flight detector

    Science.gov (United States)

    Murphy, T. J.; Lerche, R. A.; Bennett, C.; Howe, G.

    1994-05-01

    A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly-driven implosions with yields between 2.5 and 5 x 10(exp 9) DD neutrons. The detector, which has an estimated response time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding.

  9. Ion-temperature measurement of indirectly driven implosions using a geometry-compensated neutron time-of-flight detector

    Science.gov (United States)

    Murphy, T. J.; Lerche, R. A.; Bennett, C.; Howe, G.

    1995-01-01

    A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly driven implosions with yields between 2.5 and 5×109 DD neutrons. The detector, which has an estimated respond time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding.

  10. Ion temperature measurement of indirectly-driven implosions using a geometry-compensated neutron time-of-flight detector

    International Nuclear Information System (INIS)

    Murphy, T.J.; Lerche, R.A.; Bennett, C.; Howe, G.

    1994-05-01

    A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly-driven implosions with yields between 2.5 and 5 x 10 9 DD neutrons. The detector, which has an estimated response time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding

  11. Effects of time and intensity of defoliation on yield and yield components of corn

    Directory of Open Access Journals (Sweden)

    parisa mahmoodi

    2009-06-01

    Full Text Available In order to evaluate the effects of time (20, 40, 60 and 100 days after sowing and intensity of defoliation (0, 33, 66 and 100% on a corn cultivar ( three way cross 647, a complete randomized block design with split plot arrangement and three replications was conducted in Experimental Field of Faculty of Agriculture Ferdowsi University of Mashhad.The main plots were consisted of defoliation time and the sub plots were consisted of defoliation intensity. For this purpose leaves were defoliated at 33, 66, and 100% and at the end of experiment, different morphologic and physiologic criteria such as number of leaves per plent, total dry matter and plant components dry matter, seed yield and yield components and also harvest index were evaluated. Results indicated that defoliation at the early stage of crop growth (20 and 40 days and at the end of crop growth (100 days showed no effects on most of criteria measured. However at the middle of growth period, defoliation reduced these parameters. Intensity of defoliatin up to 66% had no effects, but 100% reduced all those parameters. Therefore, it appears that by defoliation up to more the 50% of plant leaves, plants could recover and appears as a normal plant, but with 100% defoliation this was not happened. Defoliation at early stages had no negative effects, because regrowth of leaves could have compensated for these type of damage. At the end of growing season, plant cycle was completed and so defoliation had no negative effects on growth and development, while at the middle stage (60 and 80 days the negative effect was due to the fact that plants could not recover completely from defoliation. Key words: Zea mays, times of defoliation, intensity of defoliation, yield.

  12. Thermalization time in a model of neutron star

    OpenAIRE

    Ducomet, B.; Nečasová, Š. (Šárka)

    2011-01-01

    We consider an initial boundary value problem for the equation describing heat conduction in a spherical model of neutron star considered by Lattimer et al. We estimate the asymptotic decay of the solution, which provides a plausible estimate for a "thermalization time" for the system.

  13. A neutron time-of-flight data acquisition system

    International Nuclear Information System (INIS)

    Morris, D.V.

    1983-10-01

    A neutron time-of-flight scaler system is described for use with the Harwell Linac. The equipment is sufficiently versatile to be used with several types of computers although normally used with DEC PDP 11/45 and PDP 11/34. Using a combination of different input and memory boards most types of experiments can be accommodated. (author)

  14. Estimating the effective system dead time parameter for correlated neutron counting

    Science.gov (United States)

    Croft, Stephen; Cleveland, Steve; Favalli, Andrea; McElroy, Robert D.; Simone, Angela T.

    2017-11-01

    Neutron time correlation analysis is one of the main technical nuclear safeguards techniques used to verify declarations of, or to independently assay, special nuclear materials. Quantitative information is generally extracted from the neutron-event pulse train, collected from moderated assemblies of 3He proportional counters, in the form of correlated count rates that are derived from event-triggered coincidence gates. These count rates, most commonly referred to as singles, doubles and triples rates etc., when extracted using shift-register autocorrelation logic, are related to the reduced factorial moments of the time correlated clusters of neutrons emerging from the measurement items. Correcting these various rates for dead time losses has received considerable attention recently. The dead time losses for the higher moments in particular, and especially for large mass (high rate and highly multiplying) items, can be significant. Consequently, even in thoughtfully designed systems, accurate dead time treatments are needed if biased mass determinations are to be avoided. In support of this effort, in this paper we discuss a new approach to experimentally estimate the effective system dead time of neutron coincidence counting systems. It involves counting a random neutron source (e.g. AmLi is a good approximation to a source without correlated emission) and relating the second and higher moments of the neutron number distribution recorded in random triggered interrogation coincidence gates to the effective value of dead time parameter. We develop the theoretical basis of the method and apply it to the Oak Ridge Large Volume Active Well Coincidence Counter using sealed AmLi radionuclide neutron sources and standard multiplicity shift register electronics. The method is simple to apply compared to the predominant present approach which involves using a set of 252Cf sources of wide emission rate, it gives excellent precision in a conveniently short time, and it

  15. Time reversal invariance - a test in free neutron decay

    Energy Technology Data Exchange (ETDEWEB)

    Lising, Laura Jean [Univ. of California, Berkeley, CA (United States)

    1999-01-01

    Time reversal invariance violation plays only a small role in the Standard Model, and the existence of a T-violating effect above the predicted level would be an indication of new physics. A sensitive probe of this symmetry in the weak interaction is the measurement of the T-violating ''D''-correlation in the decay of free neutrons. The triple-correlation Dσn∙pe x pv involves three kinematic variables, the neutron spin, electron momentu, and neutrino (or proton) momentum, and changes sign under time reversal. This experiment detects the decay products of a polarized cold neutron beam with an octagonal array of scintillation and solid-state detectors. Data from first run at NIST's Cold Neutron Research Facility give a D-coefficient of -0.1 ± 1.3(stat.) ± 0.7(syst) x 10-3 This measurement has the greatest bearing on extensions to the Standard model that incorporate leptoquarks, although exotic fermion and lift-right symmetric models also allow a D as large as the present limit.

  16. Experimental study of time-reversal invariance in neutron-nucleus interactions

    International Nuclear Information System (INIS)

    Shaparov, E.I.; Shimizu, H.M.

    1996-01-01

    Experimental approaches for the test of time-reversal invariance in neutron-nucleus interactions are reviewed. Possible transmission experiments with polarized neutron beams and polarized or aligned targets are discussed as well as neutron capture experiments with unpolarized resonance neutrons. 102 refs., 13 figs., 3 tabs

  17. Some time dependent aspects of fast neutron induced atomic cascades

    International Nuclear Information System (INIS)

    Williams, M.M.R.

    1976-01-01

    Analytical results are obtained for the time-energy distribution of neutrons and the associated displaced atoms slowing down in an amorphous medium according to a general force law. Explicit results are given for the inverse power law, and applications to hard-sphere and Coulomb scattering are discussed. Complete results are obtained for the steady state energy distribution of particles arising from a primary knock-on, and from a neutron initiated cascade. The speed of the slowing down process is assessed by calculating the slowing down time of particles. Two different concepts of slowing down time are discussed, one based upon a density average and the other on a slowing down density average. It is shown that the latter definition is physically more realistic and mathematically simpler. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-01

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

  19. Pseudo-random neutron time-of-flight spectroscopy using a Van de Graaff accelerator as neutron source

    International Nuclear Information System (INIS)

    Duquesne, Henry; Schmitt, Andre; Poussot, Rene; Pelicier, Henri.

    1976-05-01

    The classical experiments of neutron time-of-flight spectrometry on bulk multiplying media are using recurrent neutron bursts from a linear accelerator. The adaptation of the ion beam issued from the Cadarache Van de Graaff accelerator is described with the test experiments which were effected. Both methods are compared with respect to the accuracy obtained, the energy resolution and the time consumed [fr

  20. Neutron yields from massive lead and uranium targets irradiated with relativistic protons

    International Nuclear Information System (INIS)

    Zamani, M.; Fragopoulou, M.; Stoulos, S.; Manolopoulou, M.; Kulakov, B.A.; Krivopustov, M.I.; Sosnin, N.A.; Brandt, R.; Westmeier, W.; Debeauvais, M.; Hashemi-Nezhad, S.R.

    2005-01-01

    Long-lived isotopes can be transmuted into stable or short-lived elements either by neutron captures or neutron induced fission. The need of a large excess of neutrons has led to the use of accelerator driven sources (ADS). A series of experiments were carried out at the Synchrophasotron/Nuclotron of the Joint Institute for Nuclear Research (JINR) Dubna, using protons of 1.0 GeV. Solid Lead and Uranium targets surrounded by paraffin moderator were irradiated. On the outer surface of the moderator a number of Solid State Track Detectors were placed to monitor neutron spatial distribution. The results showed that the maximum neutron production was reached within the range of one to two proton mean free paths in the target. Then decreasing neutron production follows the proton beam attenuation along the target. Moreover, the results showed both targets neutron production evolution along the target, to be the same. However, neutron flux per incident proton is depended on the target mass, which was found to be higher for the heavier target

  1. Optimization of the neutron yield in fusion plasmas produced by Coulomb explosions of deuterium clusters irradiated by a petawatt laser

    Science.gov (United States)

    Bang, W.; Dyer, G.; Quevedo, H. J.; Bernstein, A. C.; Gaul, E.; Donovan, M.; Ditmire, T.

    2013-02-01

    The kinetic energy of hot (multi-keV) ions from the laser-driven Coulomb explosion of deuterium clusters and the resulting fusion yield in plasmas formed from these exploding clusters has been investigated under a variety of conditions using the Texas Petawatt laser. An optimum laser intensity was found for producing neutrons in these cluster fusion plasmas with corresponding average ion energies of 14 keV. The substantial volume (1-10 mm3) of the laser-cluster interaction produced by the petawatt peak power laser pulse led to a fusion yield of 1.6×107 neutrons in a single shot with a 120 J, 170 fs laser pulse. Possible effects of prepulses are discussed.

  2. Nodal approximations in space and time for neutron kinetics

    International Nuclear Information System (INIS)

    Grossman, L.M.; Hennart, J.P.

    2005-01-01

    A general formalism is described of the nodal type in time and space for the neutron kinetics equations. In space, several nodal methods are given of the Raviart-Thomas type (RT0 and RT1), of the Brezzi-Douglas-Marini type (BDM0 and BDM1) and of the Brezzi-Douglas-Fortin-Marini type (BDFM 1). In time, polynomial and analytical approximations are derived. In the analytical case, they are based on the inclusion of an exponential term in the basis function. They can be continuous or discontinuous in time, leading in particular to the well-known Crank-Nicolson, Backward Euler and θ schemes

  3. Nodal approximations in space and time for neutron kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, L.M. [Department of Nuclear Engineering, University of California, Berkeley, CA 94720 (United States); Hennart, J.P. [Department of Mathematical and Numerical Methods, Institute for Research in Applied Mathematics and Systems, National Autonomous University of Mexico, A.P. 20-726, 01000 Mexico D.F. (Mexico)

    2005-07-01

    A general formalism is described of the nodal type in time and space for the neutron kinetics equations. In space, several nodal methods are given of the Raviart-Thomas type (RT0 and RT1), of the Brezzi-Douglas-Marini type (BDM0 and BDM1) and of the Brezzi-Douglas-Fortin-Marini type (BDFM 1). In time, polynomial and analytical approximations are derived. In the analytical case, they are based on the inclusion of an exponential term in the basis function. They can be continuous or discontinuous in time, leading in particular to the well-known Crank-Nicolson, Backward Euler and {theta} schemes.

  4. Effect of organic manure application on yield distribution over time ...

    African Journals Online (AJOL)

    Temporal distribution of yield over harvests and yield in various truss positions on the main stem in three West African eggplants were studied in the field under five poultry manure rates. Fruit yields were spread over 12-15 weeks, unless where the life of the crop was cut short due to insect pest or disease attack. Two peaks ...

  5. Neutron Time-of-Flight Diffractometer HIPPO at LANSCE

    Science.gov (United States)

    Vogel, Sven; Williams, Darrick; Zhao, Yusheng; Bennett, Kristin; von Dreele, Bob; Wenk, Hans-Rudolf

    2004-03-01

    The High-Pressure Preferred Orientation (HIPPO) neutron diffractometer is the first third-generation neutron time-of-flight powder diffractometer to be constructed in the United States. It produces extremely high intensity by virtue of a short (9 m) initial flight path on a high intensity water moderator and 1380 3He detector tubes covering 4.5 m2 of detector area from 10' to 150' in scattering angles. HIPPO was designed and manufactured as a joint effort between LANSCE and University of California with the goals of attaining world-class science and making neutron powder diffractometry an accessible and available tool to the national user community. Over two decades of momentum transfer are available (0.1-30 A-1) to support studies of amorphous solids; magnetic diffraction; small crystalline samples; and samples subjected to extreme environments such as temperature, pressure, or magnetic fields. The exceptionally high data rates of HIPPO also make it useful for time-resolved studies. In addition to the standard ancillary equipment (100-position sample/texture changer, closed-cycle He refrigerator, furnace), HIPPO has unique high-pressure cells capable of achieving pressures of 30 GPA at ambient and high (2000 K) temperature with samples up to 100 mm3 in volume.

  6. Real-time dosimetry for boron-neutron capture therapy

    International Nuclear Information System (INIS)

    Bliss, M.; Craig, R.A.; Reeder, P.L.; Sunberg, D.S.

    1994-09-01

    Epithermal/thermal boron neutron-capture therapy (BNCT) is promising treatment method for malignant tumors. Because the doses and dose rates for medical therapeutic radiation are very close to the normal tissue tolerance, small errors in radiation delivery can result in harmful overdoses. A substantial need exists for a device that will monitor, in real time, the radiation dose being delivered to a patient. Pacific Northwest Laboratory (PNL) has developed a scintillating glass optical fiber that is sensitive to thermal neutrons. The small size of the fibers offers the possibility of in vivo dose monitoring at several points within the radiation field. The count rate of such detectors can approach 10 MHz because the lifetime of the cerium activator is fast. Fluxes typical of those in BNCT (i.e., 10 9 n/cm 2 /sec) may be measured because of this potentially high count rate and the small diameter of the fiber

  7. Time lens for high-resolution neutron time-of-flight spectrometers

    International Nuclear Information System (INIS)

    Baumann, K.; Gaehler, R.; Grigoriev, P.; Kats, E.I.

    2005-01-01

    We examine in analytic and numeric ways the imaging effects of temporal neutron lenses created by traveling magnetic fields. For fields of parabolic shape we derive the imaging equations, investigate the time magnification, the evolution of the phase-space element, the gain factor, and the effect of finite beam size. The main aberration effects are calculated numerically. The system is technologically feasible and should convert neutron time-of-flight instruments from pinhole to imaging configuration in time, thus enhancing intensity and/or time resolution. Further fields of application for high-resolution spectrometry may be opened

  8. Possible cause of anomalies in storage time of ultra-cold neutrons

    International Nuclear Information System (INIS)

    Frank, I.M.

    Various possible causes of anomalies in the storage time of ultracold neutrons are considered. It is concluded that anomalies in extreme ultracold neutrons, at least partially, are related to surface waves and that this problem requires more detailed theoretical study

  9. A systematic experimental study of thick-target neutron yield for high-energy heavy ions

    International Nuclear Information System (INIS)

    Nakamura, T.; Kurosawa, T.; Shibata, T.; Uwamino, Y.; Fukumura, A.

    1999-01-01

    Angular and energy distributions of neutrons produced by 100 and 180 MeV/nucleon He, 100, 180 and 400 MeV/nucleon C, 100, 180 and 400 MeV/nucleon Ne ions stopping in thick carbon, aluminium, copper and lead targets have been measured using the heavy ion medical accelerator of the National Institute of Radiological Sciences. The neutron spectra in the forward direction have broad peaks located at about 60-70% of the incident particle energy per nucleon due to break-up process and spreading up to almost twice as much as the projectile energy per nucleon. The neutron spectra at all angles consists of two components of cascade neutrons and evaporation neutrons. The experimental results are also compared with the calculations using the HIC and LCS codes, and the calculated results generally agree with the measured ones within a factor of 2 margin of accuracy, except around the high energy end in the forward direction. This systematic study on neutron production from thick targets by high-energy heavy ions is a first experimental work and will be useful in the shielding design of high-energy heavy ion accelerator facilities. (author)

  10. Development of a portable transfer standard for the neutron source yield measurement using Fluka simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Meghnath, E-mail: meghms@barc.gov.in; Sathian, V.; Shobha, G.; Sujatha, P.N.; Yashoda, S.; Kulkarni, M.S.; Babu, D.A.R.

    2015-10-01

    A novel light weight portable transfer standard has been developed for the standardization of the laboratory neutron sources conforming to in-situ measurements. Fluka simulation was used to optimize various design parameters in such a way that it has almost constant efficiency for the neutron energy range of few keV to 10 MeV and also for the commonly available laboratory neutron sources. The optimized total length and radius of the system is 39.4 cm and 13.5 cm, respectively. The weight of the system is about 22 kg. The efficiency of the system obtained from experiment for four laboratory neutron sources ({sup 241}Am–Be, {sup 241}Am–B, {sup 252}Cf and {sup 241}Am–F) is constant within the deviation of ±8% having the average value of 2.85 counts/n.cm{sup 2}. The efficiency of the system was also calculated from Fluka simulation. For mono-energetic neutrons from 1 MeV to 10 MeV the efficiency of the system was found to be constant within ±10% having the average value of 2.9 counts/n.cm{sup 2} and for the above mentioned four neutron sources also it is constant within ±4% with the same average value.

  11. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    International Nuclear Information System (INIS)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A.

    2007-08-01

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron time-of-flight spectra recorded for plasmas subjected to different heating scenarios. A data acquisition rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed

  12. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    Energy Technology Data Exchange (ETDEWEB)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A. (and others)

    2007-08-15

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron time-of-flight spectra recorded for plasmas subjected to different heating scenarios. A data acquisition rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed.

  13. Engineering Applications of Time-of-Flight Neutron Diffraction

    Science.gov (United States)

    Clausen, Bjørn; Brown, Donald W.; Noyan, I. C.

    2012-01-01

    Time-of-flight neutron diffraction is widely used in characterizing the microstructure and mechanical response of heterogeneous systems. Microstructural characterization techniques include spatial or temporal mapping of the phases and determination of grain size, dislocation structure, and grain orientations (texture) within these phases. Mechanical response analysis utilizes the crystallographic selectivity of the diffraction process to measure the partitioning of strain within the system. The microstructural and mechanical response information is then used to develop more realistic constitutive models. In this article we review some examples of such measurements, based on our experiences at the Lujan Center of Los Alamos National Laboratory.

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

    Science.gov (United States)

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

    2017-09-01

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

  15. Theoretical and experimental studies of the neutron rich fission product yields at intermediate energies

    Directory of Open Access Journals (Sweden)

    Äystö J.

    2012-02-01

    Full Text Available A new method to measure the fission product independent yields employing the ion guide technique and a Penning trap as a precision mass filter, which allows an unambiguous identification of the nuclides is presented. The method was used to determine the independent yields in the proton-induced fission of 232Th and 238U at 25 MeV. The data were analyzed with the consistent model for description of the fission product formation cross section at the projectile energies up to 100 MeV. Pre-compound nucleon emission is described with the two-component exciton model using Monte Carlo method. Decay of excited compound nuclei is treated within time-dependent statistical model with inclusion of the nuclear friction effect. The charge distribution of the primary fragment isobaric chain was considered as a result of frozen quantal fluctuations of the isovector nuclear density. The theoretical predictions of the independent fission product cross sections are used for normalization of the measured fission product isotopic distributions.

  16. Experimental approach to measure thick target neutron yields induced by heavy ions for shielding

    Directory of Open Access Journals (Sweden)

    Trinh N.D.

    2017-01-01

    Full Text Available Double differential (angular and energy neutron distributions were measured using an activation foil technique. Reactions were induced by impinging two low-energy heavy-ion beams accelerated with the GANIL CSS1 cyclotron: (36S (12 MeV/u and 208Pb (6.25 MeV/u onto thick natCu targets. Results have been compared to Monte-Carlo calculations from two codes (PHITS and FLUKA for the purpose of benchmarking radiation protection and shielding requirements. This comparison suggests a disagreement between calculations and experiment, particularly for high-energy neutrons.

  17. TOF-SEMSANS—Time-of-flight spin-echo modulated small-angle neutron scattering

    NARCIS (Netherlands)

    Strobl, M.; Tremsin, A.S.; Hilger, A.; Wieder, F.; Kardjilov, N.; Manke, I.; Bouwman, W.G.; Plomp, J.

    2012-01-01

    We report on measurements of spatial beam modulation of a polarized neutron beam induced by triangular precession regions in time-of-flight mode and the application of this novel technique spin-echo modulated small-angle neutron scattering (SEMSANS) to small-angle neutron scattering in the very

  18. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    International Nuclear Information System (INIS)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A.; Kaellne, J.; Weiszflog, M.; Andersson Sunden, E.; Conroy, S.; Ericsson, G.; Hellesen, C.; Ronchi, E.; Sjoestrand, H.; Gorini, G.; Tardocchi, M.; Combo, A.; Cruz, N.; Sousa, J.; Popovichev, S.

    2008-01-01

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range, including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron TOF spectra recorded for plasmas subjected to different heating scenarios. A true event count rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth, where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed

  19. A time-of-flight detector for thermal neutrons from radiotherapy Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Conti, V. [Universita degli Studi di Milano and INFN di Milano (Italy)], E-mail: conti.Valentina@gmail.com; Bartesaghi, G. [Universita degli Studi di Milano and INFN di Milano (Italy); Bolognini, D.; Mascagna, V.; Perboni, C.; Prest, M.; Scazzi, S. [Universita dell' Insubria, Como and INFN di Milano (Italy); Mozzanica, A. [Universita degli Studi di Brescia and INFN sezione di Pavia (Italy); Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A. [Fisica Sanitaria, Ospedale S. Anna di Como (Italy); Giannini, G.; Vallazza, E. [INFN, sezione di Trieste and Universita degli Studi di Trieste (Italy)

    2007-10-21

    Boron Neutron Capture Therapy (BNCT) is a therapeutic technique exploiting the release of dose inside the tumour cell after a fission of a {sup 10}B nucleus following the capture of a thermal neutron. BNCT could be the treatment for extended tumors (liver, stomach, lung), radio-resistant ones (melanoma) or tumours surrounded by vital organs (brain). The application of BNCT requires a high thermal neutron flux (>5x10{sup 8}ncm{sup -2}s{sup -1}) with the correct energy spectrum (neutron energy <10keV), two requirements that for the moment are fulfilled only by nuclear reactors. The INFN PhoNeS (Photo Neutron Source) project is trying to produce such a neutron beam with standard radiotherapy Linacs, maximizing with a dedicated photo-neutron converter the neutrons produced by Giant Dipole Resonance by a high energy (>8MeV) photon beam. In this framework, we have developed a real-time detector to measure the thermal neutron time-of -flight to compute the flux and the energy spectrum. Given the pulsed nature of Linac beams, the detector is a single neutron counting system made of a scintillator detecting the photon emitted after the neutron capture by the hydrogen nuclei. The scintillator signal is sampled by a dedicated FPGA clock thus obtaining the exact arrival time of the neutron itself. The paper will present the detector and its electronics, the feasibility measurements with a Varian Clinac 1800/2100CD and comparison with a Monte Carlo simulation.

  20. Neutron monitors and muon detectors for solar modulation studies: Interstellar flux, yield function, and assessment of critical parameters in count rate calculations

    Science.gov (United States)

    Maurin, D.; Cheminet, A.; Derome, L.; Ghelfi, A.; Hubert, G.

    2015-01-01

    Particles count rates at given Earth location and altitude result from the convolution of (i) the interstellar (IS) cosmic-ray fluxes outside the solar cavity, (ii) the time-dependent modulation of IS into Top-of-Atmosphere (TOA) fluxes, (iii) the rigidity cut-off (or geomagnetic transmission function) and grammage at the counter location, (iv) the atmosphere response to incoming TOA cosmic rays (shower development), and (v) the counter response to the various particles/energies in the shower. Count rates from neutron monitors or muon counters are therefore a proxy to solar activity. In this paper, we review all ingredients, discuss how their uncertainties impact count rate calculations, and how they translate into variation/uncertainties on the level of solar modulation ϕ (in the simple Force-Field approximation). The main uncertainty for neutron monitors is related to the yield function. However, many other effects have a significant impact, at the 5-10% level on ϕ values. We find no clear ranking of the dominant effects, as some depend on the station position and/or the weather and/or the season. An abacus to translate any variation of count rates (for neutron and μ detectors) to a variation of the solar modulation ϕ is provided.

  1. Yields of the rare-earth neutron-deficient isotopes in the reactions of Mo isotopes with 40Ca ions

    International Nuclear Information System (INIS)

    Adam, J.; Chaloun, P.; Gangrskij, Yu.P.

    1999-01-01

    The results of the joint Russian-Chinese experiment on the measurements of the reaction cross sections of the rare-earth neutron-deficient isotopes production and the study of their decay scheme are presented. The studied nuclides were obtained in the reactions 92 Mo + 40 Ca and 97 Mo + 40 Ca on the 4-meter cyclotron of the Flerov Laboratory of Nuclear Reactions, JINR. The recoil nuclei were stopped in the inert gas and transported by the gas flow to the detectors. The single and coincidence spectra of γ-, x-rays and delayed protons were measured. The enhanced yield of the reactions with the charge particle evaporation was observed

  2. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Schultz, W.E.; Smith, H.D.; Smith, M.P.

    1980-01-01

    An improved method and apparatus are described for simultaneously measuring the porosity and thermal neutron capture cross section of earth formations in situ in the vicinity of a well borehole using pulsed neutron well logging techniques. The logging tool which is moved through the borehole consists of a 14 MeV pulsed neutron source, an epithermal neutron detector and a combination gamma ray and fast neutron detector. The associated gating systems, counters and combined digital computer are sited above ground. (U.K.)

  3. Reconstruction of Time-Resolved Neutron Energy Spectra in Z-Pinch Experiments Using Time-of-flight Method

    International Nuclear Information System (INIS)

    Rezac, K.; Klir, D.; Kubes, P.; Kravarik, J.

    2009-01-01

    We present the reconstruction of neutron energy spectra from time-of-flight signals. This technique is useful in experiments with the time of neutron production in the range of about tens or hundreds of nanoseconds. The neutron signals were obtained by a common hard X-ray and neutron fast plastic scintillation detectors. The reconstruction is based on the Monte Carlo method which has been improved by simultaneous usage of neutron detectors placed on two opposite sides from the neutron source. Although the reconstruction from detectors placed on two opposite sides is more difficult and a little bit inaccurate (it followed from several presumptions during the inclusion of both sides of detection), there are some advantages. The most important advantage is smaller influence of scattered neutrons on the reconstruction. Finally, we describe the estimation of the error of this reconstruction.

  4. Search for time reversal violation in neutron decay

    International Nuclear Information System (INIS)

    Gorel, P.

    2006-06-01

    The topic of this thesis is the implementation of an experimental setup designed to measure the R- and N-parameters in polarized neutron decay, together with the data analysis. Four observables are necessary for this measurement: the neutron polarization, the electron momentum and both transverse components of the electron polarization. These last two are measured using a Mott polarimeter. The other observables are determined using the same detectors. The precision to be reached on the R-parameter is 0.5%. A non zero value would sign a time reversal invariance violation and therefore would be a hint of physics beyond the Standard Model. This document presents the work done to prepare and optimize the experimental setup before the data acquisition run performed in 2004. Particular care was taken on the scintillator walls, used to trigger the acquisition and measure the electron energy. The second part concerns the implementation of methods to extract R and N from the data, and the study of the background recorded simultaneously. (author)

  5. Yields of products from thermal-neutron induced fission of 235U

    International Nuclear Information System (INIS)

    Aagaard, P.; Rudstam, G.; Zwicky, H.U.

    1982-01-01

    Methods for fission yield determinations at an ISOL-system connected nuclear reactor have been developed. The present report contains detailed descriptions both of the experimental techniques and of the method used to correct the experimental yields for the decay of short-lived nuclear species in the delay between production and measurement. (Authors)

  6. Quantifying Gamma/Neutron Discrimination in Gadolinium-Rich Real-Time Neutron Detection Materials and Devices

    Science.gov (United States)

    2016-05-01

    Quantifying Gamma/Neutron Discrimination in Gadolinium-Rich Real-time Neutron Detection Materials and Devices Distribution Statement A. Approved...rem [equivalent and effective dose] 1 × 10–2 joule per kilogram (J kg–1) [sievert (Sv)] * Specific details regarding the implementation of SI...crucial data were unsuccessful, as were attempts to clarify the analysis or pedigree of that data with the laboratories from which it came. It appeared as

  7. A real-time neutron-gamma discriminator based on the support vector machine method for the time-of-flight neutron spectrometer

    Science.gov (United States)

    Wei, ZHANG; Tongyu, WU; Bowen, ZHENG; Shiping, LI; Yipo, ZHANG; Zejie, YIN

    2018-04-01

    A new neutron-gamma discriminator based on the support vector machine (SVM) method is proposed to improve the performance of the time-of-flight neutron spectrometer. The neutron detector is an EJ-299-33 plastic scintillator with pulse-shape discrimination (PSD) property. The SVM algorithm is implemented in field programmable gate array (FPGA) to carry out the real-time sifting of neutrons in neutron-gamma mixed radiation fields. This study compares the ability of the pulse gradient analysis method and the SVM method. The results show that this SVM discriminator can provide a better discrimination accuracy of 99.1%. The accuracy and performance of the SVM discriminator based on FPGA have been evaluated in the experiments. It can get a figure of merit of 1.30.

  8. Time-of-flight spectrometer for the measurement of gamma correlated neutron spectra

    International Nuclear Information System (INIS)

    Andriashin, A.V.; Devkin, B.V.; Lychagin, A.A.; Minko, J.V.; Mironov, A.N.; Nesterenko, V.S.; Sztaricskai, T.; Petoe, G.; Vasvary, L.

    1986-01-01

    A time-of-flight spectrometer for the measurement of gamma correlated neutron spectra from (n,xnγ) reactions is described. The operation and the main parameters are discussed. The resolution in the neutron channel is 2.2 ns/m at the 150 keV neutron energy threshold. A simultaneous measurement of the time-of-flight and amplitude distributions makes it possible to study gamma correlated neutron spectra as well as the prompt gamma spectra in coincidence with selected energy neutrons. In order to test the spectrometer, measurements of the neutron spectrum in coincidence with the 846 keV gamma line of 56 Fe were carried out at an incident neutron energy of 14.1 MeV. (Auth.)

  9. Time-of-flight spectrometer for the measurement of gamma correlated neutron spectra

    International Nuclear Information System (INIS)

    Andryashin, A.V.; Devlein, B.V.; Lychagin, A.A.; Minko, Y.V.; Mironov, A.N.; Nesterenko, V.S.

    1986-01-01

    A time-of-flight spectrometer for the measurement of gamma correlated neutron spectra form (n,xnγ) reactions is described. The operation and the main parameters are discussed. The resolution in the neutron channel is 2.2 ns/m at the 150 keV neutron energy threshold. A simultaneous measurement of the time-of-flight and amplitude distributions makes it possible to study gamma correlated neutron spectra as well as the prompt gamma spectra in coincidence with selected energy neutrons. In order to test the spectrometer, measurements of the neutron spectrum in coincidence with the 846 keV gamma line of 56 Fe were carried out at an incident neutron energy of 14.1 MeV. (author). 3 figs., 6 refs

  10. Time-of-flight neutron-correlation spectrometers and their electronics

    International Nuclear Information System (INIS)

    Tsitovich, A.P.

    1976-01-01

    The review is made of the data published on neutron-correlation time-of-flight spectrometers. The operating principle of a correlation neutron time-of-flight spectrometer implies that the neutron beam serving as an input signal is modulated by an inadvertent law, and time spectrum is found by the way of measuring the mutually correlating function of the input signal and the output signal of the neutron detector. The correlation method is grounded in brief, and the specific features of the neutron-beam choppers, pulse analyzers and time encoders used in the correlation spectrometers are given. Also considered are the main functions of the computers operating in line with the spectrometers. As compared with the ordinary time-of-flight spectrometers, the neutron-correlation ones are more effective, which explains their wide application in nuclear spectrometry

  11. Two-dimensional time dependent Riemann solvers for neutron transport

    International Nuclear Information System (INIS)

    Brunner, Thomas A.; Holloway, James Paul

    2005-01-01

    A two-dimensional Riemann solver is developed for the spherical harmonics approximation to the time dependent neutron transport equation. The eigenstructure of the resulting equations is explored, giving insight into both the spherical harmonics approximation and the Riemann solver. The classic Roe-type Riemann solver used here was developed for one-dimensional problems, but can be used in multidimensional problems by treating each face of a two-dimensional computation cell in a locally one-dimensional way. Several test problems are used to explore the capabilities of both the Riemann solver and the spherical harmonics approximation. The numerical solution for a simple line source problem is compared to the analytic solution to both the P 1 equation and the full transport solution. A lattice problem is used to test the method on a more challenging problem

  12. Yields of products from thermal-neutron induced fission of 235U

    International Nuclear Information System (INIS)

    Rudstam, G.; Aagaard, P.; Zwicky, H.U.

    1985-01-01

    Methods for fission yield determinations at an ISOL-system connected to a nuclear reactor have been developed. The present report contains detailed descriptions both of the experimental techniques and of the method used to correct the experimental yields for the decay of short-lived nuclear species in the delay between production and measurement. The methods have been applied to the determination of the fission yields of 40 fission products including 2 isometric pairs in the light mass region and those of 99 fission products including 25 isometric pairs or triplets in the heavy mass region. For 64 cases this is the first determination published. (author)

  13. Neutronics equations: Positiveness; compactness; spectral theory; time asymptotic behavior

    International Nuclear Information System (INIS)

    Mokhtar-Kharroubi, M.

    1987-12-01

    Neutronics equations are studied: the continuous model (with and without delayed neutrons) and the multigroup model. Asymptotic descriptions of these equations (t→+∞) are obtained, either by the Dunford method or by using semigroup perturbation techniques, after deriving the spectral theory for the equations. Compactness problems are reviewed, and a general theory of compact injection in neutronic functional space is derived. The effects of positiveness in neutronics are analyzed: the irreducibility of the transport semigroup, and the properties of the main eigenvalue (existence, nonexistence, frame, strict dominance, strict monotony in relation to all the parameters). A class of transport operators whose real spectrum can be completely described is shown [fr

  14. Principium research of real-time neutron radiography in No. 300 reactor

    International Nuclear Information System (INIS)

    Tang Bin; Zhang Songbao; Xia Ming; Song Yanwei

    2003-01-01

    The characteristics of real-time neutron radiography are described briefly in this paper, and the acquirement of neutron flux, the selection of convertor and the structure of the twilight imaging system and the image-sampling and image-processing system in SPRR-300 reactor are also analyzed detailedly. The experimental result of real-time neutron radiograph is too analyzed in this paper

  15. On the measurement of the delayed neutron yields in effectively infinite critical media

    International Nuclear Information System (INIS)

    Filip, A.; d'Angelo, A.

    1992-01-01

    Considering the persistent uncertainties (∼ 5%) in the prediction of the reactivity scale (β eff ) for a fast power reactor, an international project was recently initiated in the framework of the Organization of Economic Cooperation Development/Nuclear Energy Agency activities for reevaluation, new measurements and integral benchmarking of delayed neutron data and related kinetic parameters (principally β eff ). The integral benchmarking, the β eff experiment, planned at Cadarache (CEA-France) on Masurca fast assembly, aims to extract reliable information both on basic delayed neutron data (namely ν d ) and on the reactor response separation of effects a particular strategy is adopted. Concerning the experimental side, several techniques for measuring the β eff (deterministic and noise) on several clean, large cores of different ratio of fissile nuclides are planned. Concerning the interpretation of the measurements, an adapted method related to the effectively infinite critical media (the Perturbed Fundamental Mode) was developed. Moreover, the information on ν d from direct (nuclear) remeasurements and/or reevaluations are included in the final interpretation. In this paper the authors present a preliminary analysis of the Masurca planned β eff experiment. The results permit the authors to expect firstly a significant reduction of the uncertainties in ν d for U235, Pu 239 and U238 (to ± 2%, 3% and 3.5% respectively) and, secondly, a better insight in the effectiveness problem

  16. Energy spectra and fluence of the neutrons produced in deformed space-time conditions

    Science.gov (United States)

    Cardone, F.; Rosada, A.

    2016-10-01

    In this work, spectra of energy and fluence of neutrons produced in the conditions of deformed space-time (DST), due to the violation of the local Lorentz invariance (LLI) in the nuclear interactions are shown for the first time. DST-neutrons are produced by a mechanical process in which AISI 304 steel bars undergo a sonication using ultrasounds with 20 kHz and 330 W. The energy spectrum of the DST-neutrons has been investigated both at low (less than 0.4 MeV) and at high (up to 4 MeV) energy. We could conclude that the DST-neutrons have different spectra for different energy intervals. It is therefore possible to hypothesize that the DST-neutrons production presents peculiar features not only with respect to the time (asynchrony) and space (asymmetry) but also in the neutron energy spectra.

  17. Measurement of Neutron Energy Spectrum Emitted by Cf-252 Source Using Time-of-Flight Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheol Ho; Son, Jaebum; Kim, Tae Hoon; Lee, Sangmin; Kim, Yong-Kyun [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    The techniques proposed to detect the neutrons usually require the detection of a secondary recoiling nucleus in a scintillator (or other type of detector) to indicate the rare collision of a neutron with a nucleus. This is the same basic technique, in this case detection of a recoil proton that was used by Chadwick in the 1930 s to discover and identify the neutron and determine its mass. It is primary technique still used today for detection of fast neutron, which typically involves the use of a hydrogen based organic plastic or liquid scintillator coupled to a photo-multiplier tube. The light output from such scintillators is a function of the cross section and nuclear kinematics of the n + nucleus collision. With the exception of deuterated scintillators, the scintillator signal does not necessarily produce a distinct peak in the scintillator spectrum directly related to the incident neutron energy. Instead neutron time-of-flight (TOF) often must be utilized to determine the neutron energy, which requires generation of a prompt start signal from the nuclear source emitting the neutrons. This method takes advantage of the high number of prompt gamma rays. The Time-of-Flight method was used to measure neutron energy spectrum emitted by the Cf-252 neutron source. Plastic scintillator that has a superior discrimination ability of neutron and gamma-ray was used as a stop signal detector and liquid scintillator was used as a stat signal detector. In experiment, neutron and gamma-ray spectrum was firstly measured and discriminated using the TOF method. Secondly, neutron energy spectrum was obtained through spectrum analysis. Equation of neutron energy spectrum that was emitted by Cf-252 source using the Gaussian fitting was obtained.

  18. Neutron noise analysis of BWR using time series analysis

    International Nuclear Information System (INIS)

    Fukunishi, Kohyu

    1976-01-01

    The main purpose of this paper is to give more quantitative understanding of noise source in neutron flux and to provide a useful tool for the detection and diagnosis of reactor. The space dependent effects of distributed neutron flux signals at the axial direction of two different strings are investigated by the power contribution ratio among neutron fluxes and the incoherent noise spectra of neutron fluxes derived from autoregressive spectra. The signals are measured on the medium sized commercial BWR of 460 MWe in Japan. From the obtained results, local and global noise sources in neutron flux are discussed. This method is indicated to be a useful tool for detection and diagnosis of anomalous phenomena in BWR. (orig./RW) [de

  19. Resonance analysis of the {sup 12}C,{sup 13}C({alpha},n) reactions and evaluation of neutron yield data of the reaction

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Toru [AITEL Corp., Tokyo (Japan)

    1998-03-01

    The {sup 12}C({alpha},n){sup 15}O reaction and the {sup 13}C({alpha},n){sup 16}O reaction were analyzed with a resonance formula in the incident {alpha}-particle energy range of 1.0 to 16.0 MeV. With the obtained resonance parameters, branching ratios of the emitted neutrons to the several levels of the residual nucleus and their angular distributions were calculated to obtain the energy spectrum of emitted neutrons. Thick target neutron yield of carbon were also calculated and compared with the experimental data. (author)

  20. Reviews for LLNL Fission Chain Yield Determination of Fission Spectrum Neutron Bombardment on Plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Kenneally, Jacqueline [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ahle, Larry [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dardenne, Yves [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hagmann, Chris [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Henderson, Roger [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Moody, Ken [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thompson, Ian [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vogt, Doug [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wu, Ching -Yen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Younes, Walid [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2009-07-16

    This body of work represents the progress to date on the larger-scale issue of conducting an evaluation with a focus to determine the fission chain yields for 95Zr, 99Mo, 144Ce, and 147Nd.

  1. Polarized neutron source and detectors for the TUNL parity-even test of time reversal invariance

    International Nuclear Information System (INIS)

    Huffman, P.R.; Roberson, N.R.; Wilburn, W.S.

    1995-01-01

    The development and implementation of a 10 MHz neutron production target and detector system are presented. The system has been used in a test of parity-even time reversal invariance in neutron transmission through an aligned target. Neutrons were produced via the D(d,n) 3 He reaction using a liquid nitrogen cooled deuterium gas cell. The cryogenic cell required temperature stabilization for minimization of systematic effects. Two four-detector arrays of neutron detectors were developed for 0 degrees transmission measurements and flux monitoring. The system allowed transmission asymmetries to be measured to accuracies better than 10 -6 in a parity-conserving test of time reversal invariance

  2. Time collimation for elastic neutron scattering instrument at a pulsed source

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Nikitenko, Yu.V.

    1996-01-01

    Conditions for carrying out elastic neutron scattering experiments using the time-of-flight technique are considered. It is shown that the employment of time dependent neutron beam collimation in the source-sample flight path increases the luminosity of the spectrometer under certain resolution restrictions. 3 refs., 8 figs

  3. Time dispersion in large plastic scintillation neutron detector [Paper No.:B3

    International Nuclear Information System (INIS)

    De, A.; Dasgupta, S.S.; Sen, D.

    1993-01-01

    Time dispersion seen by photomultiplier (PM) tube in large plastic scintillation neutron detector and the light collection mechanism by the same have been computed showing that this time dispersion (TD) seen by the PM tube does not necessarily increase with increasing incident neutron energy in contrast to the usual finding that TD increases with increasing energy. (author). 8 refs., 4 figs

  4. The multipurpose time-of-flight neutron reflectometer “Platypus” at Australia's OPAL reactor

    Science.gov (United States)

    James, M.; Nelson, A.; Holt, S. A.; Saerbeck, T.; Hamilton, W. A.; Klose, F.

    2011-03-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ( λ=2-20 Å) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of Platypus time-of-flight neutron reflectometer are presented.

  5. Time-Dependent Neutron and Photon Dose-Field Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wooten, Hasani Omar [Georgia Inst. of Technology, Atlanta, GA (United States)

    2005-08-01

    A unique tool is developed that allows the user to model physical representations of complicated glovebox facilities in two dimensions and determine neutral-particle flux and ambient dose-equivalent fields throughout that geometry. The Pandemonium code, originally designed to determine flux and dose-rates only, is improved to include realistic glovebox geometries, time-dependent source and detector positions, time-dependent shielding thickness calculations, time-integrated doses, a representative criticality accident scenario based on time-dependent reactor kinetics, and more rigorous photon treatment. A primary benefit of this work has been an extensive analysis and improvement of the photon model that is not limited to the application described in this thesis. The photon model has been extended in energy range to 10 MeV to include photons from fission and new photon buildup factors have been included that account for the effects of photon buildup at slant-path thicknesses as a function of angle, where the mean free path thickness has been preserved. The overall system of codes is user-friendly and it is directly applicable to facilities such as the plutonium facility at Los Alamos National Laboratory, where high-intensity neutron and photon emitters are regularly used. The codes may be used to determine a priori doses for given work scenarios in an effort to supply dose information to process models which will in turn assist decision makers on ensuring as low as reasonably achievable (ALARA) compliance. In addition, coupling the computational results of these tools with the process model visualization tools will help to increase worker safety and radiological safety awareness.

  6. Time-of-flight 3D Neutron Diffraction for Multigrain Crystallography

    OpenAIRE

    Cereser, Alberto; Hall, Stephen A.; Steuwer, Axel; Strobl, Markus; Schmidt, Søren

    2016-01-01

    This thesis presents a new technique for measuring spatially resolved microstructures in crystalline materials using pulsed neutron beams. The method, called Time-of-Flight Three Dimensional Neutron Diffraction (ToF 3DND), identifies the position, shape and crystallographic orientation of the individual grains within the sample. The experiments were conducted at the single crystal diffractometer SENJU at the Japanese neutron source J-PARC. The choice of this instrument was motivated by its la...

  7. Improvement in the calibration time of absolute emission rate of radioisotopic neutron sources using vanadyl sulfate bath

    International Nuclear Information System (INIS)

    Khabaz, Rahim

    2012-01-01

    In this study, for calibration of emission rate of radioisotopic neutron sources, a suitable vanadium salt was proposed instead manganese sulfate because the shorter half-life of 52 V would facilitate faster neutron yield measurements to be made with a shorter delay time between subsequent measurements. Using Monte Carlo method, different correction factors of manganese and vanadyl sulfate baths were calculated and compared with each other. The results showed that for having an appropriate efficiency of VBS, high concentrations of solution must be used. - Highlights: ► The widely used method for measurement of emission rate of radioisotopic neutron sources is MBS. ► One of limitations of MBS is time required for activation to saturation and background measurement. ► The aim of this study is to evaluate a calibration method by VBS with about one-hour full-cycle time. ► The relative efficiency per neutron of VBS was just about half that obtained from MBS. ► The relative efficiency of VBS is compensated with increasing the concentration of solution.

  8. On the timing characteristics of low-yield fast scintillators

    International Nuclear Information System (INIS)

    Galligaris, F.; Ciuti, P.; Gabrielli, I.; Giacomich, R.

    1980-01-01

    The timing characteristics of Ne 111 scintillator quenched with 3% of benzophenone have been studied by the single photon counting technique. Its performances have been compared with the measured characteristics of unquenched Ne 111, PILOT U and NE 104 and with the data available in the literature. (orig.)

  9. A transistorized 1024-channel neutron time-of-flight analyser

    International Nuclear Information System (INIS)

    Giannelli, G.

    1962-01-01

    A transistorized 1024-channel neutron time-of-flight analyser is described. This instrument has been divided in two fully independent parts: the analogue-to-digital converter (ADC) that measures the time-of-flight and the 1024-channel ferrite-core memory. In this way the output signals coming from the ADC can be recorded on a magnetic tape together with the output from other ADCs which measure other physical quantities related to the same nuclear event, with an overall number of channels higher than the capacity of the memory. The AD converter is provided with a temporary memory that, by its regularizing action on the signals rate, (1) when the AD converter, directly connected to the 1024-channel memory, allows a dead time of only 0.5 μs, and (2) when the AD converter drives a magnetic tape recorder and allows a better utilization of the magnetic tape itself. The temporary memory has a capacity of four numbers of up to sixteen bits. The channel-width of the analyser is variable from 0.5 up to 48 μs. The 1024 channels can be divided in two contemporary groups of 512, each connected to two detectors. The temporary memory allows contemporary recordings of signals into the two groups. The channels can also be subdivided over the time-of-flight in two groups of which the first (of 16 channels) is used to record the true zero time of the time-of-flight, while the second group can be set in any position over the total time-of-flight interval. The number of channels used in the recording of the time-of-flight can be reduced in order to record another quantity with 1024 overall channels. The logical design of the instrument is described. In the design advantage has been taken of the possibilities offered by the transistorization and the related mechanical construction systems in order to produce a most flexible instrument and one in which future modifications or extensions, which may be required by the experimenters, are feasible. (author) [fr

  10. Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Oshinowo, Babatunde O. [Fermilab; Izraelevitch, Federico [Buenos Aires U.

    2016-10-17

    The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquires kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.

  11. Current status and future prospect of space and time reversal symmetry violation on low energy neutron reactions

    International Nuclear Information System (INIS)

    Masuda, Yasuhiro

    1993-01-01

    In this report, the papers on symmetry violation under space reflection and time reversal and neutron spin, neutron spin rotation and P-violation, parity nonconservation in neutron capture reaction, some advantage of the search for CP-violation in neutron scattering, dynamic polarization of 139 La target, alexandrite laser for optical pumping, polarized 3 He system for T- and P-violation neutron experiments, control of neutron spin in T-violation neutron experiment, symmetry regarding time and space and angular distribution and angular correlation of radiation and particle beams, T-violation due to low temperature nuclear polarization and axion exploration using nuclear transition are collected. (K.I.)

  12. A Time of flight spectrometer for measurements of double differential neutron scattering cross sections

    International Nuclear Information System (INIS)

    Padron, I.; Dominguez, O.; Sarria, P. Sandin, C.

    1996-01-01

    The time -of-Flight neutron spectrometry technique by associated particle method was improved using a D-T neutron generator at Laboratory of Nuclear Analysis. This technique was implemented for double differential cross section measurements and supported by the IAEA Project CUB/01/005. An stilbene scintillation detector (dia=100 mm, length=50 mm) was used as principal neutron detector detector and was situated outside a hole in the concrete wall. This way the fligth path was extended and the scattered neutron cone accurate collimated throught the 2 m concrete wall. For the associated particle α detection a thin plastic NE-102 scint illator was used, as well as, two scintilation detectors and a long counter for the neutron flux monitoring. In this TOF neutron spectrometer (3.40 m flight path) a 1.7 nseg. temporal resolution was obtained

  13. Dead time of different neutron detectors associated with a pulsed electronics with current collection

    International Nuclear Information System (INIS)

    Bacconnet, Eugene; Duchene, Jean; Duquesne, Henry; Schmitt, Andre

    1968-01-01

    After having outlined that the development of fast neutron reactor physics, notably kinetics, requires highly efficient neutron detectors and pulse measurement chains able to cope with high counting rates, the authors report the measurement of dead time of various neutron detectors which are used in the experimental study of fast neutron reactors. They present the SAITB 1 electronic measurement set, its components, its general characteristics, the protected connection between the detector and the electronics. They present and report the experiment: generalities about detector location and measurements, studied detectors (fission chambers, boron counters), and report the exploitation of the obtained results (principle, data, high-threshold counting gain) [fr

  14. Calculation of the importance-weighted neutron generation time using MCNIC method

    International Nuclear Information System (INIS)

    Feghhi, S.A.H.; Shahriari, M.; Afarideh, H.

    2008-01-01

    In advanced nuclear power systems, such as ADS, the need for reliable kinetics parameters is of considerable importance because of the lower value for β eff due to the large amount of transuranic elements loaded in the core of those systems. All reactor kinetic parameters are weighted quantities. In other words each neutron with a given position and energy is weighted with its importance. Neutron generation time as an important kinetic parameter, in all nuclear power systems has a significant role in the analysis of fast transients. The difference between non-weighted neutron generation time; Λ; standard in most Monte Carlo codes; and the weighted one Λ + can be quite significant depending on the type of the system. In previous work, based on the physical concept of neutron importance, a new method; MCNIC; using the MCNP code has been introduced for the calculation of neutron importance in fissionable assemblies for all criticality states. In the present work the applicability of MCNIC method has been extended for the calculation of the importance-weighted neutron generation time. The influence of reflector thickness on importance-weighted neutron generation time has been investigated by the development of an auxiliary code, IWLA, for a hypothetic assembly. The results of these calculations were compared with the non-weighted neutron generation times calculated using the Monte Carlo code MCNP. The difference between the importance-weighted and non-weighted quantity is more significant in a reflected system and increases with reflector thickness

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

    Science.gov (United States)

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

    2018-01-01

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

  16. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data.

    Science.gov (United States)

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L; Dronskowski, Richard

    2015-12-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh 0.81 Fe 3.19 N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages.

  17. A PCI time digitizer for the new JET time-of-flight neutron spectrometer

    International Nuclear Information System (INIS)

    Sousa, J.; Batista, A.J.N.; Combo, A.; Pereira, R.; Cruz, N.; Carvalho, P.; Varandas, C.A.F.; Conroy, S.; Ericsson, G.; Kaellne, J.

    2004-01-01

    A PCI time digitizer module with eight independent time-to-digital converter (TDC) channels is being developed for the new time-of-flight spectrometer designed for optimized rate (TOFOR) which diagnoses deuterium plasmas of the EFDA-JET tokamak. The module shall measure with high accuracy the flight-times of 2.5 MeV neutrons in the 100 ns range as given by two groups of scintillation detectors operating at average event rates from the expected 500 kHz up to 5 MHz. The module stores up to 64 million hit-times with a resolution of 0.4 ns and incorporates a digital signal processor and a system-on-chip device which performs the data transfer, the device control/monitoring and may perform statistical, data reduction or control algorithms in real-time

  18. Diffraction by the time-of-flight technique at pulsed neutron sources

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1984-06-01

    The recent development of accelerator-based pulsed neutron sources as an alternative to reactor sources has caused a renewed interest in time-of-flight neutron diffraction techniques because the time-of-flight method can be optimally used at pulsed sources. Since neutrons have finite mass, and therefore travel at a velocity proportional to their wavelength, neutron diffraction can be done either by the conventional technique commonly used for X-rays, where a single wavelength is used, or by the time-of-flight technique, where all wavelengths are used. In a conventional diffraction experiment with monochromatic radiation, the Bragg equation d = lambda/(2 sin theta) is satisfied by varying the angle 2 theta at which the scattered radiation is detected. In a time-of-flight diffraction experiment, all wavelengths lambda are allowed to scatter from the sample and are determined by recording the times at which neutrons arrive at a detector in a fixed position. Neutron diffraction has been done by the time-of-flight technique for many years using mechanical neutron choppers at reactor sources, but found only limited application because the chopper instruments could not be properly optimized with respect to beam size, pulse width, and repetition rate. The new accelerator-based pulsed neutron sources produce neutrons in short, intense bursts, eliminating the need for mechanical choppers. The pulse width and repetition rate can be tailored to meet the requirements of a particular instrument. After only a few years of development, this has allowed time-of-flight diffraction instruments at moderately-sized pulsed neutron sources

  19. A review of in situ and/or time resolved neutron scattering

    International Nuclear Information System (INIS)

    Isnard, O.

    2007-01-01

    Thanks to the ability of neutrons to penetrate deep into matter, experiments can be performed in situ in real conditions. The development of dedicated instruments on high flux neutron sources also enables fast data acquisition. As a consequence, it is now possible to investigate not only in situ but also time resolved physical or chemical processes over several time scales ranging from hours to a few milliseconds. Several recent examples are taken in different fields of research: physics, magnetism, chemistry, metallurgy, electrochemistry, polymers and to get information from archaeological objects. Among the scattering techniques that can be used to perform in situ or time resolved experiments we present results of powder neutron diffraction, small angle neutron scattering, and neutron radiography. (author)

  20. Method for simultaneous measurement of borehole and formation neutron decay-times

    International Nuclear Information System (INIS)

    Smith, H.D.; Arnold, D.M.

    1982-01-01

    A method is described of making in situ measurements of the thermal neutron decay time of earth formations in the vicinity of a wellbore. The borehole and earth formations are irradiated, with pulsed fast neutrons and, during the interval between neutron pulses, capture gamma radiation is measured in at least four, non-overlapping, contiguous time intervals. Count-rates representative of thermal neutron populations in the borehole and the formations are made during each of the time intervals. A background radiation measurement for correcting the count-rates is preferably also periodically made. The count-rates are combined to derive simultaneously the formation and borehole neutron lifetime components which are recorded as a function of borehole depth. (author)

  1. Incident spectrum determination for time-of-flight neutron powder diffraction data analysis

    International Nuclear Information System (INIS)

    Hodges, J. P.

    1998-01-01

    Accurate characterization of the incident neutron spectrum is an important requirement for precise Rietveld analysis of time-of-flight powder neutron diffraction data. Without an accurate incident spectrum the calculated model for the measured relative intensities of individual Bragg reflections will possess systematic errors. We describe a method for obtaining an accurate numerical incident spectrum using data from a transmitted beam monitor

  2. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, A.C.; Smith, K. (comps.)

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  3. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    International Nuclear Information System (INIS)

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs

  4. FOCUS: neutron time-of-flight spectrometer at SINQ: recent progress

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S.; Mesot, J.; Holitzner, L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Hempelmann, R. [Saarbruecken Univ. (Germany)

    1997-09-01

    At the Swiss neutron spallation source SINQ a time-of-flight spectrometer for cold neutrons is under construction. The design foresees a Hybrid solution combining a Fermi chopper with a doubly focusing crystal monochromator. During 1996 important progress has been made concerning the main spectrometer components such as the spectrometer housing and the detector system. (author) 2 figs., 3 refs.

  5. Real time neutronic evolution CNE (Embalse nuclear power plant)

    International Nuclear Information System (INIS)

    Notari, C.; Waldman, R.M.

    1993-01-01

    The simulator of the Embalse nuclear power plant uses a Point Reactor Model(PRM) for the neutronic evolution calculation. As this model is not conservative for transients produced by the sudden or localized reactivity insertion in big cores, it is convenient to use spatial models in these cases. In this report we show the results obtained using a nodal model (codes NODOS-TIEMPO). This model has been fitted against a more exact solution for the neutron flux and delayed neutron precursors. This has been done for the reactor at full power with nominal values for the reactivity control devices (liquid zones and adjusters rods). Transients corresponding to the global variation of the liquid zones and to the insertion of fresh fuel in some channels are shown. The results are compared with calculations made with the quasi-static model of the PUMA code. (author). 1 ref

  6. In situ and/or time resolved powder neutron scattering for materials science

    International Nuclear Information System (INIS)

    Isnard, O.

    2006-01-01

    In general, neutrons offer the advantage to be weakly absorbed by materials. Consequently neutron scattering is a very efficient tool to probe deeply inside the materials in a non destructive manner. Time resolved neutron scattering is thus widely used by different scientific fields: materials science, physics, chemistry, etc. It is now possible to perform neutron diffraction in situ, in complex environments: electrochemical reaction cells, pressure cells, etc. In situ neutron diffraction has been widely developed on high neutron flux sources such as those of the Institut Laue Langevin (Grenoble). Neutron scattering is a very useful technique for time resolved reaction processes inside materials. The experimental set-up needed for such type of experiments is briefly presented. Thereafter, examples of recent applications of neutron diffraction are described to illustrate the possible use of thermodiffractometry, in situ and/or time resolved to investigate phase transitions of chemical processes. The examples are taken in different scientific fields: metallurgy, electrochemistry, magnetism, solid state chemistry and archeometry. (author)

  7. DNS: Diffuse scattering neutron time-of-flight spectrometer

    Directory of Open Access Journals (Sweden)

    Yixi Su

    2015-08-01

    Full Text Available DNS is a versatile diffuse scattering instrument with polarisation analysis operated by the Jülich Centre for Neutron Science (JCNS, Forschungszentrum Jülich GmbH, outstation at the Heinz Maier-Leibnitz Zentrum (MLZ. Compact design, a large double-focusing PG monochromator and a highly efficient supermirror-based polarizer provide a polarized neutron flux of about 107 n cm-2 s-1. DNS is used for the studies of highly frustrated spin systems, strongly correlated electrons, emergent functional materials and soft condensed matter.

  8. The dynamic method for time-of-flight measurement of thermal neutron spectra from pulsed sources

    International Nuclear Information System (INIS)

    Pepyolyshev, Yu.N.; Chuklyaev, S.V.; Tulaev, A.B.; Bobrakov, V.F.

    1995-01-01

    A time-of-flight method for measurement of thermal neutron spectra in pulsed neutron sources with an efficiency more than 10 5 times higher than the standard method is described. The main problems associated with the electric current technique for time-of-flight spectra measurement are examined. The methodical errors, problems of special neutron detector design and other questions are discussed. Some experimental results for spectra from the surfaces of water and solid methane moderators obtained at the IBR-2 pulsed reactor (Dubna, Russia) are presented. (orig.)

  9. Time reversal in polarized neutron decay: the emiT experiment

    CERN Document Server

    Jones, G L; Anaya, J M; Bowles, T J; Chupp, T E; Coulter, K P; Dewey, M S; Freedman, S J; Fujikawa, B K; García, A; Greene, G L; Hwang, S R; Lising, L J; Mumm, H P; Nico, J S; Robertson, R G H; Steiger, T D; Teasdale, W A; Thompson, A K; Wasserman, E G; Wietfeldt, F E; Wilkerson, J F

    2000-01-01

    The standard electro-weak model predicts negligible violation of time-reversal invariance in light quark processes. We report on an experimental test of time-reversal invariance in the beta decay of polarized neutrons as a search for physics beyond the standard model. The emiT collaboration has measured the time-reversal-violating triple-correlation in neutron beta decay between the neutron spin, electron momentum, and neutrino momentum often referred to as the D coefficient. The first run of the experiment produced 14 million events which are currently being analyzed. However, a second run with improved detectors should provide greater statistical precision and reduced systematic uncertainties.

  10. Deep inelastic neutron scattering from orthorhombic ordered HCl: Short-time proton dynamics and anomalous neutron cross sections

    International Nuclear Information System (INIS)

    Senesi, R.; Colognesi, D.; Pietropaolo, A.; Abdul-Redah, T.

    2005-01-01

    Deep inelastic neutron scattering measurements from orthorhombic ordered HCl are presented and analyzed in order to clarify the problem of an anomalous deficit in the neutron-proton cross section found in previous experiments on various materials. A reliable model for the HCl short-time single-particle dynamics, including atomic vibrational anisotropies and deviations from the impulsive approximation, is set up. The model HCl response function is transformed into simulated time-of-flight spectra, taking carefully into account the effects of instrumental resolution and the filter absorption profile used for neutron energy analysis. Finally, the experimental values of the anomalous reduction factor for the neutron-proton cross section are extracted by comparing simulated and experimental data. Results show a 34% reduction of the H cross section, varying with the scattering angle in a range centered at 53 deg. In addition, the same approximate procedure used in earlier studies is also employed, providing results in reasonable agreement with the more rigorous ones, and confirming the substantial reliability of the past work on this subject

  11. The real-time neutron radiography system at Texas A and M University

    International Nuclear Information System (INIS)

    Reuscher, Jon A.

    1990-01-01

    This paper reports on the development and fabrication of a real-time system at Texas A and M University using commercially available and relatively inexpensive components. The real-time neutron radiography system consists of two major components: a camera and image processing equipment. The neutron beam provides a thermal neutron flux of 10 neutrons/cm -sec (cadmium ratio of 4.0) with the TRIGA reactor operating at a power of 1 MW. A remotely operated turntable is used to position the sample in the neutron beam for optimum viewing and ease of changing position. The front surface mirror at 45 deg. to the neutron beam reflects the scintillation image to the lens. The IRO and CCD camera are placed behind shielding out of the neutron. Results using the imaging system for a cadmium plate (0.032 inch thick) with several holes of different diameters are presented. Applications of this neutron radiography system include sensitivity indicators for the spatial resolution of bubbles in water-filled tubes, moisture content of zeolite samples, operating heat pipes and the freezing and thawing of metallic samples

  12. 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.

  13. Invited Article: Polarization ``Down Under'': The polarized time-of-flight neutron reflectometer PLATYPUS

    Science.gov (United States)

    Saerbeck, T.; Klose, F.; Le Brun, A. P.; Füzi, J.; Brule, A.; Nelson, A.; Holt, S. A.; James, M.

    2012-08-01

    This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

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

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1994-01-01

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

  15. Structural studies at high pressure using time-of-flight neutron powder diffraction

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1989-07-01

    Time-of-flight neutron powder diffraction offers unique capabilities for structural studies at high pressure. Scientific applications have included studies of compression mechanisms, new high-pressure structures, and phase transitions. 11 refs., 1 fig

  16. Method for simultaneous measurement of borehole and formation neutron decay-times employing iterative fitting

    International Nuclear Information System (INIS)

    Schultz, W.E.

    1982-01-01

    A method is described of making in situ measurements of the thermal neutron decay time of earth formations in the vicinity of a wellbore. The borehole and earth formations in its vicinity are repetitively irradiated with pulsed fast neutrons and, during the intervals between pulses, capture gamma radiation is measured in at least four, non-overlapping, contiguous time intervals. A background radiation measurement is made between successive pulses and used to correct count-rates representative of thermal neutron populations in the borehole and the formations, the count-rates being generated during each of the time intervals. The background-corrected count-rate measurements are iteratively fitted to exponential curves using a least squares technique to simultaneously derive signals representing borehole component and formation component of the thermal neutron decay time. The signals are recorded as a function of borehole depth. (author)

  17. Application of Trotter approximation for solving time dependent neutron transport equation

    International Nuclear Information System (INIS)

    Stancic, V.

    1987-01-01

    A method is proposed to solve multigroup time dependent neutron transport equation with arbitrary scattering anisotropy. The recurrence relation thus obtained is simple, numerically stable and especially suitable for treatment of complicated geometries. (author)

  18. A time-dependent neutron transport method of characteristics formulation with time derivative propagation

    International Nuclear Information System (INIS)

    Hoffman, Adam J.; Lee, John C.

    2016-01-01

    A new time-dependent Method of Characteristics (MOC) formulation for nuclear reactor kinetics was developed utilizing angular flux time-derivative propagation. This method avoids the requirement of storing the angular flux at previous points in time to represent a discretized time derivative; instead, an equation for the angular flux time derivative along 1D spatial characteristics is derived and solved concurrently with the 1D transport characteristic equation. This approach allows the angular flux time derivative to be recast principally in terms of the neutron source time derivatives, which are approximated to high-order accuracy using the backward differentiation formula (BDF). This approach, called Source Derivative Propagation (SDP), drastically reduces the memory requirements of time-dependent MOC relative to methods that require storing the angular flux. An SDP method was developed for 2D and 3D applications and implemented in the computer code DeCART in 2D. DeCART was used to model two reactor transient benchmarks: a modified TWIGL problem and a C5G7 transient. The SDP method accurately and efficiently replicated the solution of the conventional time-dependent MOC method using two orders of magnitude less memory.

  19. Status and outlook of the neutron time-of-flight facility n_TOF at CERN

    CERN Document Server

    Gunsing, F

    2007-01-01

    The neutron time-of-flight facility n_TOF at CERN, fully operational since 2002, combines a high instantaneous neutron flux with high energy resolution. The wide energy range and the high neutron flux per time-of-flight burst result in a much enhanced signal to background ratio for neutron capture of radioactive isotopes and makes this facility well suited for the measurement of high quality neutron-induced reaction cross-sections. Neutrons are created by spallation reactions induced by a pulsed 20 GeV/c proton beam impinging on a lead target. A 5 cm water slab surrounding the lead target serves as a coolant and at the same time as a moderator of the spallation neutron spectrum, providing a wide energy spectrum from 0.1 eV to about 250 MeV. By the end of 2005, a first phase of data taking has been successfully terminated. Fission and capture experiments have been performed on a variety of isotopes of interest for nuclear astrophysics, advanced nuclear technologies and for basic nuclear physics. The instrument...

  20. Thermalization time in a model of neutron star

    Czech Academy of Sciences Publication Activity Database

    Ducomet, B.; Nečasová, Šárka

    2011-01-01

    Roč. 16, č. 3 (2011), s. 801-818 ISSN 1531-3492 R&D Projects: GA ČR GA201/08/0012 Institutional research plan: CEZ:AV0Z10190503 Keywords : comressible * heat conducting fluids * one-dimensional symmetry * neutron star Subject RIV: BA - General Mathematics Impact factor: 0.921, year: 2011 http://aimsciences.org/journals/displayArticlesnew.jsp?paperID=6325

  1. Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

    International Nuclear Information System (INIS)

    Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Woznicka, U.

    1993-01-01

    A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a 3 He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs

  2. High efficiency moderator for pulsed neutron diffraction

    International Nuclear Information System (INIS)

    Mayer, R.E.; Granada, J.R.; Gillette, V.H.; Dawidowski, J.

    1990-01-01

    Moderators consisting of clusters of smaller slow-neutron-decoupled moderating elements were tested through experiments of pulsed neutron diffraction, leakage spectrum measurement, and neutron pulse decay. A simple slab and a thin 'sandwich' moderator were also measured for comparison purposes. For a given time width of the neutron pulse in the usual wavelength range for neutron diffraction, the proposed assembly produced a much higher neutron yield. Clues to the implementation of the desired time-response in moderator design and optimization are suggested by the present results. (orig.)

  3. Milk yield affects time budget in daiyr cows kept in tie-stalls

    DEFF Research Database (Denmark)

    Norring, M.; Valros, A.; Munksgaard, Lene

    2012-01-01

    Effective selection in breeding programs and improved management has increased the milk production per cow. However, the effects of the increased yield on behavior have not yet been clarified. We investigated the effect of milk yield on the time budget of 29 Finnish Ayrshire cows in the same stage...

  4. Effects of harvesting time on some yield and quality traits of different ...

    African Journals Online (AJOL)

    Jane

    2011-07-25

    Jul 25, 2011 ... Soils are classified as clay. The region has a warm climate in summer and the mean annual rainfall is around 450 mm, most of which fall ..... methods to increase tuber yield need to be expanded the harvesting time until 120 DAP. Early cultivars carrera and felsina gave more than 2 t ha-1 tuber yield at 120 ...

  5. Real-Time Magnetic Resonance Imaging Guidance Improves the Diagnostic Yield of Endomyocardial Biopsy

    Directory of Open Access Journals (Sweden)

    Toby Rogers, BM BCh

    2016-08-01

    Full Text Available Diagnostic yield of endomyocardial biopsy is low, particularly in disease that affects the myocardium in a nonuniform distribution. The authors hypothesized that real-time MRI guidance could improve the yield through targeted biopsy of focal myocardial pathology. They tested this hypothesis in an animal model of focal myocardial pathology using intracoronary ethanol and microspheres. The authors compared real-time MRI-guided endomyocardial biopsy in swine using a custom actively visualized MRI bioptome against x-ray–guided biopsy using a commercial bioptome by skilled operators. Real-time MRI guidance significantly increased the diagnostic yield of endomyocardial biopsy.

  6. Geant4 Analysis of a Thermal Neutron Real-Time Imaging System

    Science.gov (United States)

    Datta, Arka; Hawari, Ayman I.

    2017-07-01

    Thermal neutron imaging is a technique for nondestructive testing providing complementary information to X-ray imaging for a wide range of applications in science and engineering. Advancement of electronic imaging systems makes it possible to obtain neutron radiographs in real time. This method requires a scintillator to convert neutrons to optical photons and a charge-coupled device (CCD) camera to detect those photons. Alongside, a well collimated beam which reduces geometrical blurriness, the use of a thin scintillator can improve the spatial resolution significantly. A representative scintillator that has been applied widely for thermal neutron imaging is 6LiF:ZnS (Ag). In this paper, a multiphysics simulation approach for designing thermal neutron imaging system is investigated. The Geant4 code is used to investigate the performance of a thermal neutron imaging system starting with a neutron source and including the production of charged particles and optical photons in the scintillator and their transport for image formation in the detector. The simulation geometry includes the neutron beam collimator and sapphire filter. The 6LiF:ZnS (Ag) scintillator is modeled along with a pixelated detector for image recording. The spatial resolution of the system was obtained as the thickness of the scintillator screen was varied between 50 and 400 μm. The results of the simulation were compared to experimental results, including measurements performed using the PULSTAR nuclear reactor imaging beam, showing good agreement. Using the established model, further examination showed that the resolution contribution of the scintillator screen is correlated with its thickness and the range of the neutron absorption reaction products (i.e., the alpha and triton particles). Consequently, thinner screens exhibit improved spatial resolution. However, this will compromise detection efficiency due to the reduced probability of neutron absorption.

  7. Rare-gas yields in 238U and 232Th fission by 14MeV neutrons, measured by an emanating method

    International Nuclear Information System (INIS)

    Feu Alvim, C.A.; Bocquet, J.P.; Brissot, R.; Crancon, J.; Moussa, A.

    1977-01-01

    A direct method, using emanation of rare gases by uranyle stearate and thorium stearate, has been applied to the measurement of cumulative fractional yields of certain isotopes of krypton and xenon, in the fissions of 238 U and 232 Th by 14MeV-neutrons. The independent yields of the same isotopes were measured previously by means of isotopic on-line separation. From these results, the widths of the mass and charge distributions, the relative chain yields, the fractional cumulative yields of certain bromine and iodine isotopes, the values of Zsub(p) the most probable charge, in the isobaric chains 87-93 and 137-142, and the elemental yields of krypton and xenon were calculated [fr

  8. DN-12 time of flight neutron spectrometer for investigation of structure and dynamics of microsamples

    International Nuclear Information System (INIS)

    Savenko, B.N.; Aksenov, V.L.; Balagurov, A.M.; Kozlenko, D.P.; Sheptyakov, D.V.

    1999-01-01

    DN-12 time of flight neutron spectrometer operating at IBR-2 high flux pulsed reactor at FLNP JINR, Dubna, Russia is described. It is designed for experiments with microsamples in wide range of temperatures and pressures. DN-12 allows to perform neutron diffraction experiments at temperatures down to 15 K and pressures up to 7 Gpa and inelastic incoherent scattering experiments (with samples which have large incoherent neutron scattering cross section) at pressures up to 5 GPa with sapphire anvil high pressure cells. The parameters of the spectrometer, recent results and future prospects are reviewed. (author)

  9. A neutron time of flight spectrometer appropriate for D-T plasma diagnostics

    International Nuclear Information System (INIS)

    Elevant, T.

    1984-02-01

    A neutron time-of-flight spectrometer with 2 m flight path for diagnostics of deuterium plasmas in JET is presently under construction. An upgrade of this spectrometer to make it appropriate for 14-MeV neutron spectroscopy is presented here. It is suggested to use backscattering in a deuterium based scintillator. The flight path length is 1-2 m and the efficiency is of the order of 2.10 -5 cm -5 . Results from test of principle are presented with estimates for neutron and gamma backgrounds

  10. Complementarity of real-time neutron and synchrotron radiation structural investigations in molecular biology

    International Nuclear Information System (INIS)

    Aksenov, V. L.; Kiselev, M. A.

    2010-01-01

    General problems of the complementarity of different physical methods and specific features of the interaction between neutron and matter and neutron diffraction with respect to the time of flight are discussed. The results of studying the kinetics of structural changes in lipid membranes under hydration and self-assembly of the lipid bilayer in the presence of a detergent are reported. The possibilities of the complementarity of neutron diffraction and X-ray synchrotron radiation and developing a free-electron laser are noted.

  11. Complementarity of real-time neutron and synchrotron radiation structural investigations in molecular biology

    Science.gov (United States)

    Aksenov, V. L.; Kiselev, M. A.

    2010-12-01

    General problems of the complementarity of different physical methods and specific features of the interaction between neutron and matter and neutron diffraction with respect to the time of flight are discussed. The results of studying the kinetics of structural changes in lipid membranes under hydration and self-assembly of the lipid bilayer in the presence of a detergent are reported. The possibilities of the complementarity of neutron diffraction and X-ray synchrotron radiation and developing a free-electron laser are noted.

  12. Neutron source for generating fast neutrons

    International Nuclear Information System (INIS)

    Schraube, H.; Morhart, A.

    1980-01-01

    In radiotherapeutics, neutron sources are needed, generating a dose rate as high as possible and neutrons as energetic as possible. By bombardment of tritium targets with deuterons of some 100 keV, neutrons of about 15 MeV are produced, but because of the large slow-down effect in the target consisting of heavy metal the yield is too small. On applying beryllium targets the neutron yields are too small below a deuteron energy of 15 MeV; at the same time, the high percentage of low energy neutrons is undesirable. Based on the favorable yield of the D(d,n) He 3 reaction for deuterons of about 100 MeV, a gas-target chamber is designed. The pressure chamber is designed for a deuterium pressure of up to 11 atmospheres and provided with cooling devices. The flux density in beam direction at a distance of 1 m reaches 108 per cm 2 , the maximum energy of the neutrons amounts to 12 MeV at deuteron energies of 9 MeV, and the neutron share below 9 MeV is small. The maximum dose rate in a tissue-equivalent phantom lies at 40 rads/min. (orig./PW)

  13. Complete determination of neutron yield from 62 MeV protons on 9Be for the design of a low - power ADS

    Science.gov (United States)

    Schillaci, Maria; Osipenko, Mikhail; Ripani, Marco; Alba, Rosa; Ricco, Giovanni; Barbagallo, Massimo; Celentano, Andrea; Boccaccio, Pasquale; Cosentino, Luigi; Del Zoppo, Antonio; Di Pietro, Alessia; Esposito, Juan; Finocchiaro, Paolo; Kostyukov, Alexander; Maiolino, Concettina; Santonocito, Domenico; Viberti, Carlo Maria

    2014-03-01

    Within the European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of fundamental reactor physics of future fast neutron-based reactors are very important. In this respect, an Accelerator Driven System low-power prototype, based on a 70 MeV proton beam impinging on a thick Beryllium converter, was recently proposed and designed within the INFN-E project. The world data on neutron yield from Be target are scarce in this proton energy range. This lack of data calls for a dedicated measurement which was performed at INFN Laboratori Nazionali del Sud, covering a wide angular range, from 0 to 150 degrees, and an almost complete neutron energy interval, from thermal up to the beam energy. In this contribution the results are discussed together with the description of the proposed ADS facility.

  14. Development of the time-of-flight smaller-angle neutron scattering instrument TAIKAN

    International Nuclear Information System (INIS)

    Suzuki, Jun-ichi; Takata, Shin-ichi; Shinohara, Takenao; Oku, Takayuki; Kira, Hiroshi; Suzuya, Kentaro; Aizawa, Kazuya; Arai, Masatoshi; Otomo, Toshiya; Sugiyama, Masaaki

    2010-01-01

    The technique of small-angle neutron scattering has been used to analyze structures of size between about 1 nm and 10 μm in materials and life science. This article introduces the development of the smaller-angle neutron scattering instrument 'TAIKAN' of MLF/J-PARC, which will provide opportunity for efficient structure analysis with high spatial- and time-resolution. (author)

  15. A preliminary time-of-flight neutron diffraction study of Streptomyces rubiginosus D-xylose isomerase.

    Science.gov (United States)

    Hanson, B Leif; Langan, Paul; Katz, Amy K; Li, Xinmin; Harp, Joel M; Glusker, Jenny P; Schoenborn, Benno P; Bunick, Gerard J

    2004-02-01

    The metalloenzyme D-xylose isomerase forms well ordered crystals that diffract X-rays to ultrahigh resolution (diffraction data has as yet been unable to differentiate between several postulated mechanisms that describe the catalytic activity of this enzyme. Neutrons, with their greater scattering sensitivity to H atoms, could help to resolve this by determining the protonation states within the active site of the enzyme. As the first step in the process of investigating the mechanism of action of D-xylose isomerase from Streptomyces rubiginosus using neutron diffraction, data to better than 2.0 A were measured from the unliganded protein at the Los Alamos Neutron Science Center Protein Crystallography Station. Measurement of these neutron diffraction data represents several milestones: this is one of the largest biological molecules (a tetramer, MW approximately 160 000 Da, with unit-cell lengths around 100 A) ever studied at high resolution using neutron diffraction. It is also one of the first proteins to be studied using time-of-flight techniques. The success of the initial diffraction experiments with D-xylose isomerase demonstrate the power of spallation neutrons for protein crystallography and should provide further impetus for neutron diffraction studies of biologically active and significant proteins. Further data will be measured from the enzyme with bound substrates and inhibitors in order to provide the specific information needed to clarify the catalytic mechanism of this enzyme.

  16. Development and Applications of Time of Flight Neutron Depth Profiling

    International Nuclear Information System (INIS)

    Cady, Bingham; Unlu, Kenan

    2005-01-01

    The depth profiles of intentional or intrinsic constituents of a sample provide valuable information for the characterization of materials. For example, the subtle differences in spatial distribution and composition of many chemical species in the near surface region and across interfacial boundaries can significantly alter the electronic and optical properties of materials. A number of analytical techniques for depth profiling have been developed during the last two decades. neutron Depth Profiling (NDP) is one of the leading analytical techniques. The NDP is a nondestructive near surface technique that utilizes thermal/cold neutron beam to measure the concentration of specific light elements versus their depth in materials. The depth is obtained from the energy loss of protons, alphas or recoil atoms in substrate materials. Since the charged particle energy determination using surface barrier detector is used for NDP, the depth resolution is highly dependent on the detectors an d detection instruments. The depth resolutions of a few tens of nm are achieved with available NDP facilities in the world. However, the performance of NDP needs to be improved in order to obtain a few A depth resolutions

  17. Measurements of angular and energy distributions of prompt neutrons from thermal neutron-induced fission

    Science.gov (United States)

    Vorobyev, A. S.; Shcherbakov, O. A.; Pleva, Yu. S.; Gagarski, A. M.; Val'ski, G. V.; Petrov, G. A.; Petrova, V. I.; Zavarukhina, T. A.

    2009-01-01

    The experimental setup and methodology used to measure prompt neutron angular and energy distributions from thermal neutron-induced fission are described. The neutrons are detected using two scintillation detectors, while the fission fragments are detected by multi-wire proportional detectors in conjunction with the TOF technique. To separate events corresponding to neutrons and γ-quanta, a double discrimination by the pulse shape and the time-of-flight is applied. Some preliminary results of an experiment performed with the 235U target are presented and briefly discussed. The yield of "scission" neutrons has been estimated in the framework of a simple evaporation model and was found not to exceed 5% of the total neutron yield. Including an assumed of anisotropy of the fission neutron angular distribution in the center-of-mass system of fission fragments into the model calculation leads to an increase in the "scission" neutron yields inferred from the data.

  18. Anaerobic digestion of industrial hemp-effect of harvest time on methane energy yield per hectare

    Energy Technology Data Exchange (ETDEWEB)

    Kreuger, E.; Escobar, F.; Bjoernsson, L. [Department of Biotechnology, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden); Prade, T.; Svensson, S.-E.; Englund, J.-E. [Department of Agriculture-Farming Systems, Technology and Product Quality, Swedish University of Agricultural Sciences, P.O. Box 104, SE-230 53 Alnarp (Sweden)

    2011-02-15

    There is a worldwide emphasis to increase the share of renewable transportation fuels. When using agricultural land for production of renewable transportation fuels, the energy output per hectare for different crops and transportation fuels is a crucial factor. In this study, the gross methane energy yield per hectare from anaerobic digestion of industrial hemp (Cannabis sativa L.), was determined at four different harvest times between July and October in Southern Sweden, a cold climate region. The biomass yield was determined for three years and the methane yield was determined for two years through the biochemical methane potential test. The highest biomass yield, 16 tonnes dry matter per hectare on an average, and the highest methane energy yield per hectare was achieved when the hemp was harvested in September or October, with an average gross methane energy yield of 136 {+-} 24 GJ per hectare. There was no significant difference in the specific methane yield between the harvest times; the average being 234 {+-} 35 m{sup 3} per tonne volatile solids. Biogas from hemp turned out to be a high yielding alternative to the currently dominating renewable transportation fuels produced from crops grown in Sweden: ethanol from wheat and biodiesel from rapeseed. (author)

  19. HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    SHAPIRO,S.M.; ZALIZNYAK,I.A.

    2002-12-30

    This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual

  20. Neutron activation system for spectral measurements of pulsed ion diode neutron production

    International Nuclear Information System (INIS)

    Hanson, D.L.; Kruse, L.W.

    1980-02-01

    A neutron energy spectrometer has been developed to study intense ion beam-target interactions in the harsh radiation environment of a relativistic electron beam source. The main component is a neutron threshold activation system employing two multiplexed high efficiency Ge(Li) detectors, an annihilation gamma coincidence system, and a pneumatic sample transport. Additional constraints on the neutron spectrum are provided by total neutron yield and time-of-flight measurements. A practical lower limit on the total neutron yield into 4π required for a spectral measurement with this system is approx. 10 10 n where the neutron yield is predominantly below 4 MeV and approx. 10 8 n when a significant fraction of the yield is above 4 MeV. Applications of this system to pulsed ion diode neutron production experiments on Hermes II are described

  1. Subprimal purchasing and merchandising decisions for pork: relationship to retail yield and fabrication time.

    Science.gov (United States)

    Lorenzen, C L; Griffin, D B; Dockerty, T R; Walter, J P; Johnson, H K; Savell, J W

    1996-01-01

    Boxed pork was obtained to represent four different purchase specifications (different anatomical separation locations and[or] external fat trim levels) common in the pork industry to conduct a study of retail yields and labor requirements. Bone-in loins (n = 180), boneless loins (n = 94), and Boston butts (n = 148) were assigned randomly to fabrication styles within subprimals. When comparing cutting styles within subprimals, it was evident that cutting style affected percentage of retail yield and cutting time. When more bone-in cuts were prepared from bone-in loin subprimals, retail yields ranged from 92.80 +/- .61 to 95.28 +/- .45%, and processing times ranged from 222.57 +/- 10.13 to 318.99 +/- 7.85 s, from the four suppliers. When more boneless cuts were prepared from bone-in loin subprimals, retail yields ranged from 71.12 +/- 1.10 to 77.92 +/- .77% and processing times ranged from 453.49 +/- 8.95 to 631.09 +/- 15.04 s from the different loins. Comparing boneless to bone-in cuts from bone-in loins resulted in lower yields and required greater processing times. Significant variations in yields and times were found within cutting styles. These differences seemed to have been the result of variation in supplier fat trim level and anatomical separation (primarily scribe length).

  2. Measurement of time-dependent fast neutron energy spectra in a depleted uranium assembly

    International Nuclear Information System (INIS)

    Whittlestone, S.

    1980-10-01

    Time-dependent neutron energy spectra in the range 0.6 to 6.4 MeV have been measured in a depleted uranium assembly. By selecting windows in the time range 0.9 to 82 ns after the beam pulse, it was possible to observe the change of the neutron energy distributions from spectra of predominantly 4 to 6 MeV neutrons to spectra composed almost entirely of fission neutrons. The measured spectra were compared to a Monte Carlo calculation of the experiment using the ENDF/B-IV data file. At times and energies at which the calculation predicted a fission spectrum, the experiment agreed with the calculation, confirming the accuracy of the neutron spectroscopy system. However, the presence of discrepancies at other times and energies suggested that there are significant inconsistencies in the inelastic cross sections in the 1 to 6 MeV range. The time response generated concurrently with the energy spectra was compared to the Monte Carlo calculation. From this comparison, and from examination of time spectra measured by other workers using 235 U and 237 Np fission detectors, it would appear that there are discrepancies in the ENDF/B-IV cross sections below 1 MeV. The predicted decay rates were too low below and too high above 0.8 MeV

  3. CVD Diamond Detectors for Current Mode Neutron Time-of-Flight Spectroscopy at OMEGA/NIF

    International Nuclear Information System (INIS)

    G. J. Schmid; V. Yu. Glebov; A. V. Friensehner; D. R. Hargrove; S. P. Hatchett; N. Izumi; R. A. Lerche; T. W. Phillips; T. C. Sangster; C. Silbernagel; C. Stoecki

    2001-01-01

    We have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.4 mA/W at 500 V/mm and 4.0 mA/W at 1000 V/mm. These values are approximately 2 to 5x times higher than those reported for natural Type IIa diamond at similar E-field and thickness (1mm). These characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to target chamber center (TCC), and would record neutron spectra fast enough such that backscattered neutrons and x-rays from the target chamber wall would not be a concern. The acquired neutron spectra could then be used to extract DD fuel areal density from the downscattered secondary to secondary ratio

  4. The multipurpose time-of-flight neutron reflectometer 'Platypus' at Australia's OPAL reactor

    International Nuclear Information System (INIS)

    James, M.; Nelson, A.; Holt, S.A.; Saerbeck, T.; Hamilton, W.A.; Klose, F.

    2011-01-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam (λ=2-20 A) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of -7 are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  5. CVD diamond detectors for current mode neutron time-of-flight spectroscopy at OMEGA/NIF

    Science.gov (United States)

    Schmid, Gregory J.; Glebov, Vladimir Y.; Friensehner, Allen V.; Hargrove, Dana R.; Hatchett, Steven P., II; Izumi, Nobuhiko; Lerche, Richard A.; Phillips, Thomas W.; Sangster, Thomas C.; Silbernagel, Christopher T.; Stoeckl, Christian

    2001-12-01

    We have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.4 mA/W at 500 V/mm and 4.0 mA/W at 100 V/mm. These values are approximately 2 to 5x times higher than those reported for natural Type IIa diamond at similar E-field and thickness (1mm). These characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to target chamber center (TCC), and would record neutron spectra fast enough such that backscattered neutrons and (gamma) rays from the target chamber wall would not be a concern. The acquired neutron spectra could then be used to extract DD fuel areal density from the downscattered secondary to secondary ratio.

  6. Development of a “Fission-proxy” Method for the Measurement of 14-MeV Neutron Fission Yields at CAMS

    Energy Technology Data Exchange (ETDEWEB)

    Gharibyan, Narek [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-25

    Relative fission yield measurements were made for 50 fission products from 25.6±0.5 MeV alpha-induced fission of Th-232. Quantitative comparison of these experimentally measured fission yields with the evaluated fission yields from 14-MeV neutron-induced fission of U-235 demonstrates the feasibility of the proposed fission-proxy method. This new technique, based on the Bohr-independence hypothesis, permits the measurement of fission yields from an alternate reaction pathway (Th-232 + 25.6 MeV α → U-236* vs. U-235 + 14-MeV n → U-236*) given that the fission process associated with the same compound nucleus is independent of its formation. Other suitable systems that can potentially be investigated in this manner include (but are not limited to) Pu-239 and U-237.

  7. Studies on fission with ALADIN. Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI

    International Nuclear Information System (INIS)

    Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Belier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric; Alvarez-Pol, Hector; Ayyad, Yassid; Benlliure, Jose; Cortina Gil, Dolores; Caamano, Manuel; Fernandez Dominguez, Beatriz; Paradela, Carlos; Ramos, Diego; Rodriguez-Sanchez, Jose-Luis; Vargas, Jossitt; Audouin, Laurent; Tassan-Got, Laurent; Aumann, Thomas; Casarejos, Enrique; Farget, Fanny; Rodriguez-Tajes, Carme; Heinz, Andreas; Jurado, Beatriz; Kelic-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Pietri, Stephane; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Voss, Bernd; Weick, Helmut

    2015-01-01

    A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism. (orig.)

  8. Studies on fission with ALADIN. Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Belier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric [CEA DAM Bruyeres-le-Chatel, Arpajon (France); Alvarez-Pol, Hector; Ayyad, Yassid; Benlliure, Jose; Cortina Gil, Dolores; Caamano, Manuel; Fernandez Dominguez, Beatriz; Paradela, Carlos; Ramos, Diego; Rodriguez-Sanchez, Jose-Luis; Vargas, Jossitt [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Audouin, Laurent; Tassan-Got, Laurent [CNRS/IN2P3, IPNO, Orsay (France); Aumann, Thomas [Technische Universitaet Darmstadt, Darmstadt (Germany); Casarejos, Enrique [Universidad de Vigo, Vigo (Spain); Farget, Fanny; Rodriguez-Tajes, Carme [CNRS/IN2P3, GANIL, Caen (France); Heinz, Andreas [Chalmers University of Technology, Gothenburg (Sweden); Jurado, Beatriz [CNRS/IN2P3, CENBG, Gradignan (France); Kelic-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Pietri, Stephane; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Voss, Bernd; Weick, Helmut [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

    2015-12-15

    A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism. (orig.)

  9. Digital Real-Time Multiple Channel Multiple Mode Neutron Flux Estimation on FPGA-based Device

    Directory of Open Access Journals (Sweden)

    Thevenin Mathieu

    2016-01-01

    Full Text Available This paper presents a complete custom full-digital instrumentation device that was designed for real-time neutron flux estimation, especially for nuclear reactor in-core measurement using subminiature Fission Chambers (FCs. Entire fully functional small-footprint design (about 1714 LUTs is implemented on FPGA. It enables real-time acquisition and analysis of multiple channels neutron's flux both in counting mode and Campbelling mode. Experimental results obtained from this brand new device are consistent with simulation results and show good agreement within good uncertainty. This device paves the way for new applications perspectives in real-time nuclear reactor monitoring.

  10. Utilizing the slowing-down-time technique for benchmarking neutron thermalization in graphite

    International Nuclear Information System (INIS)

    Zhou, T.; Hawari, A. I.; Wehring, B. W.

    2007-01-01

    Graphite is the moderator/reflector in the Very High Temperature Reactor (VHTR) concept of Generation IV reactors. As a thermal reactor, the prediction of the thermal neutron spectrum in the VHTR is directly dependent on the accuracy of the thermal neutron scattering libraries of graphite. In recent years, work has been on-going to benchmark and validate neutron thermalization in 'reactor grade' graphite. Monte Carlo simulations using the MCNP5 code were used to design a pulsed neutron slowing-down-time experiment and to investigate neutron slowing down and thermalization in graphite at temperatures relevant to VHTR operation. The unique aspect of this experiment is its ability to observe the behavior of neutrons throughout an energy range extending from the source energy to energies below 0.1 eV. In its current form, the experiment is designed and implemented at the Oak Ridge Electron Linear Accelerator (ORELA). Consequently, ORELA neutron pulses are injected into a 70 cm x 70 cm x 70 cm graphite pile. A furnace system that surrounds the pile and is capable of heating the graphite to a centerline temperature of 1200 K has been designed and built. A system based on U-235 fission chambers and Li-6 scintillation detectors surrounds the pile. This system is coupled to multichannel scaling instrumentation and is designed for the detection of leakage neutrons as a function of the slowing-down-time (i.e., time after the pulse). To ensure the accuracy of the experiment, careful assessment was performed of the impact of background noise (due to room return neutrons) and pulse-to-pulse overlap on the measurement. Therefore, the entire setup is surrounded by borated polyethylene shields and the experiment is performed using a source pulse frequency of nearly 130 Hz. As the basis for the benchmark, the calculated time dependent reaction rates in the detectors (using the MCNP code and its associated ENDF-B/VI thermal neutron scattering libraries) are compared to measured

  11. Wheat Yield Forecasting for Punjab Province from Vegetation Index Time Series and Historic Crop Statistics

    Directory of Open Access Journals (Sweden)

    Jan Dempewolf

    2014-10-01

    Full Text Available Policy makers, government planners and agricultural market participants in Pakistan require accurate and timely information about wheat yield and production. Punjab Province is by far the most important wheat producing region in the country. The manual collection of field data and data processing for crop forecasting by the provincial government requires significant amounts of time before official reports can be released. Several studies have shown that wheat yield can be effectively forecast using satellite remote sensing data. In this study, we developed a methodology for estimating wheat yield and area for Punjab Province from freely available Landsat and MODIS satellite imagery approximately six weeks before harvest. Wheat yield was derived by regressing reported yield values against time series of four different peak-season MODIS-derived vegetation indices. We also tested deriving wheat area from the same MODIS time series using a regression-tree approach. Among the four evaluated indices, WDRVI provided more consistent and accurate yield forecasts compared to NDVI, EVI2 and saturation-adjusted normalized difference vegetation index (SANDVI. The lowest RMSE values at the district level for forecast versus reported yield were found when using six or more years of training data. Forecast yield for the 2007/2008 to 2012/2013 growing seasons were within 0.2% and 11.5% of final reported values. Absolute deviations of wheat area and production forecasts from reported values were slightly greater compared to using the previous year's or the three- or six-year moving average values, implying that 250-m MODIS data does not provide sufficient spatial resolution for providing improved wheat area and production forecasts.

  12. Foodservice yield and fabrication times for beef as influenced by purchasing options and merchandising styles.

    Science.gov (United States)

    Weatherly, B H; Griffin, D B; Johnson, H K; Walter, J P; De La Zerda, M J; Tipton, N C; Savell, J W

    2001-12-01

    Selected beef subprimals were obtained from fabrication lines of three foodservice purveyors to assist in the development of a software support program for the beef foodservice industry. Subprimals were fabricated into bone-in or boneless foodservice ready-to-cook portion-sized cuts and associated components by professional meat cutters. Each subprimal was cut to generate mean foodservice cutting yields and labor requirements, which were calculated from observed weights (kilograms) and processing times (seconds). Once fabrication was completed, data were analyzed to determine means and standard errors of percentage yields and processing times for each subprimal. Subprimals cut to only one end point were evaluated for mean foodservice yields and processing times, but no comparisons were made within subprimal. However, those traditionally cut into various end points were additionally compared by cutting style. Subprimals cut by a single cutting style included rib, roast-ready; ribeye roll, lip-on, bone-in; brisket, deckle-off, boneless; top (inside) round; and bottom sirloin butt, flap, boneless. Subprimals cut into multiple end points or styles included ribeye, lip-on; top sirloin, cap; tenderloin butt, defatted; shortloin, short-cut; strip loin, boneless; top sirloin butt, boneless; and tenderloin, full, side muscle on, defatted. Mean yields of portion cuts, and mean fabrication times required to manufacture these cuts differed (P < 0.05) by cutting specification of the final product. In general, as the target portion size of fabricated steaks decreased, the mean number of steaks derived from any given subprimal cut increased, causing total foodservice yield to decrease and total processing time to increase. Therefore, an inverse relationship tended to exist between processing times and foodservice yields. With a method of accurately evaluating various beef purchase options, such as traditional commodity subprimals, closely trimmed subprimals, and pre-cut portion

  13. 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.

  14. Neutron coincidence counting based on time interval analysis with dead time corrected one and two dimensional Rossi-alpha distributions: an application for passive neutron waste assay

    International Nuclear Information System (INIS)

    Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R.

    1996-03-01

    The report describes a new neutron multiplicity counting method based on Rossi-alpha distributions. The report also gives the necessary dead time correction formulas for the multiplicity counting method. The method was tested numerically using a Monte Carlo simulation of pulse trains. The use of this multiplicity method in the field of waste assay is explained: it can be used to determine the amount of fissile material in a waste drum without prior knowledge of the actual detection efficiency

  15. Time dependet behaviour of the neutron field in in two interacting cylindrical disks

    International Nuclear Information System (INIS)

    Hedlund, T.

    1979-01-01

    The influence of a void on the neutron flux in a moderating system has been studied mainly by the Monte Carlo method. The calculations simulate the decay of the neutron field in a pulsed neutron source measurement. The neutron flux was studied as a function of space, angle, energy and time for a system of two flat cylindrical polyethylene disks. The slab thickness was varied between 1.1 and 4.4 cm and the radius was 9.0 cm. The gap between the slabs was varied from zero to 18 cm. Some calculations have also been made for absorbers in the gap. The purpose of these absorbers was to eliminate the time delay effect for the low velocity neutrons accumulating in the gap. The calculations showed the usefulness of the absorber method. From the results in the time dependent cases the interaction parameter for the two slabs in the corresponding stationary cases has been calculated. The agreement with measurements made by Grosshoeg is good. In the one velocity cases some other methods have also been used to predict the decay rates. For small gap widths the best agreement with the Monte Carlo results was obtained with the variational method. (author)

  16. Influence of wholesale lamb marketing options and merchandising styles on retail yield and fabrication time.

    Science.gov (United States)

    Lorenzen, C L; Martin, A M; Griffin, D B; Dockerty, T R; Walter, J P; Johnson, H K; Savell, J W

    1997-01-01

    Lamb carcasses (n = 94) from five packing plants, selected to vary in weight class and fat thickness, were used to determine retail yield and labor requirements of wholesale lamb fabrication. Carcasses were allotted randomly according to weight class to be fabricated as whole carcasses (n = 20), three-piece boxes (n = 22), or subprimals (n = 52). Processing times (seconds) were recorded and wholesale and retail weights (kilograms) were obtained to calculate retail yield. Subprimals were fabricated into bone-in retail cuts or boneless or semi-boneless retail cuts. Retail yield for subprimal lamb legs decreased from 85.3 +/- .6% for bone-in to 68.0 +/- .7% for a completely boneless retail product. Correspondingly, processing times increased from 126.1 +/- 5.4 s to 542.0 +/- 19.2 s for bone-in and boneless legs, respectively. For all subprimals, retail yield percentage tended to decrease and total processing time increase as cuts were fabricated to boneless or semi-boneless end points compared with a bone-in end point. Percentage retail yield did not differ (P > .05) among whole carcass, three-piece box, and subprimal marketing methods. Total processing time was shorter for subprimals (P < .05) than for the other two marketing methods.

  17. The influence of rotor type and centrifugation time on the yield and purity of extracellular vesicles

    Directory of Open Access Journals (Sweden)

    Aleksander Cvjetkovic

    2014-03-01

    Full Text Available Background: Extracellular vesicles (EV, the collective term for vesicles released from cells, consist of vesicle species ranging in size from 30 nm to 5 µm in diameter. These vesicles are most commonly isolated by differential centrifugations, which pellets particles based on their differential movement through the liquid medium in which they are immersed. Multiple parameters, including the utilization of different rotor types, can influence the yield and purity of isolated vesicles; however, the understanding of how these factors affect is limited. Materials and methods: Here, we compare the influence of multiple centrifugation parameters, including the use of swinging bucket and fixed angle rotors, as well as different centrifugation times, for the isolation of the smallest EVs, “exosomes.” In particular, we determine the yields of exosomal RNA and protein, as well as the nature of the isolated vesicles and possible protein contamination with methods such as electron microscopy, western blot and flow cytometry. Results: Our results show that application of a specific g-force or rotation speed by itself does not predict the ability of pelleting exosomes, and that prolonged centrifugation times can achieve greater yields of exosomal RNA and protein, whereas very long centrifugation times result in excessive protein concentrations in the exosome pellet. Conclusion: In conclusion, rotor type, g-force and centrifugation times significantly influence exosome yield during centrifugation-based isolation procedures, and current commonly recommended isolation protocols may not be fully optimized for yield and purity of exosomes.

  18. The influence of rotor type and centrifugation time on the yield and purity of extracellular vesicles

    Science.gov (United States)

    Cvjetkovic, Aleksander; Lötvall, Jan; Lässer, Cecilia

    2014-01-01

    Background Extracellular vesicles (EV), the collective term for vesicles released from cells, consist of vesicle species ranging in size from 30 nm to 5 µm in diameter. These vesicles are most commonly isolated by differential centrifugations, which pellets particles based on their differential movement through the liquid medium in which they are immersed. Multiple parameters, including the utilization of different rotor types, can influence the yield and purity of isolated vesicles; however, the understanding of how these factors affect is limited. Materials and methods Here, we compare the influence of multiple centrifugation parameters, including the use of swinging bucket and fixed angle rotors, as well as different centrifugation times, for the isolation of the smallest EVs, “exosomes.” In particular, we determine the yields of exosomal RNA and protein, as well as the nature of the isolated vesicles and possible protein contamination with methods such as electron microscopy, western blot and flow cytometry. Results Our results show that application of a specific g-force or rotation speed by itself does not predict the ability of pelleting exosomes, and that prolonged centrifugation times can achieve greater yields of exosomal RNA and protein, whereas very long centrifugation times result in excessive protein concentrations in the exosome pellet. Conclusion In conclusion, rotor type, g-force and centrifugation times significantly influence exosome yield during centrifugation-based isolation procedures, and current commonly recommended isolation protocols may not be fully optimized for yield and purity of exosomes. PMID:24678386

  19. Evaluating a Contribution of the Knock-on Deuterons to the Neutron Yield in the Experiments with Weakly Collisional Plasma Jets (Part 1)

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-12-01

    Laser-generated interpenetrating plasma jets are widely used in the studies of collisionless interaction of counter-streaming plasmas in conjunction with possible formation of collisionless shocks. In a number of experiments of this type the plasma is formed on plastic targets made of CH or CD. The study of the DD neutron production from the interaction between two CD jets on the one hand and between a CD jet and a CH jet could serve as a qualitative indicator of the collisionless shock formation. The purpose of this memo is a discussion of the effect of collisions on the neutron generation in the interpenetrating CH and CD jets. First, the kinematics of the large-deflection collisions of the deuterons and carbon are discussed. Then the scattering angles are related with the corresponding Rutherford cross-section. After that expression for the number of the backscattered deuterons is provided, and their contribution to the neutron yield is evaluated. The results may be of some significance to the kinetic codes benchmarking and developing the neutron diagnostic.

  20. Digital image processing for real-time neutron radiography and its applications

    International Nuclear Information System (INIS)

    Fujine, Shigenori

    1989-01-01

    The present paper describes several digital image processing approaches for the real-time neutron radiography (neutron television-NTV), such as image integration, adaptive smoothing and image enhancement, which have beneficial effects on image improvements, and also describes how to use these techniques for applications. Details invisible in direct images of NTV are able to be revealed by digital image processing, such as reversed image, gray level correction, gray scale transformation, contoured image, subtraction technique, pseudo color display and so on. For real-time application a contouring operation and an averaging approach can also be utilized effectively. (author)

  1. Optimal timing of neutron irradiation for boron neutron capture therapy after intravenous infusion of sodium borocaptate in patients with glioblastoma

    International Nuclear Information System (INIS)

    Kageji, Teruyoshi; Nagahiro, Shinji; Kitamura, Katsushi; Nakagawa, Yoshinobu; Hatanaka, Hiroshi; Haritz, Dietrich; Grochulla, Frank; Haselsberger, Klaus; Gabel, Detlef

    2001-01-01

    Purpose: A cooperative study in Europe and Japan was conducted to determine the pharmacokinetics and boron uptake of sodium borocaptate (BSH: Na 2 B 12 H 11 SH), which has been introduced clinically as a boron carrier for boron neutron capture therapy in patients with glioblastoma. Methods and Materials: Data from 56 patients with glioblastoma who received BSH intravenous infusion were retrospectively reviewed. The pharmacokinetics were evaluated in 50 patients, and boron uptake was investigated in 47 patients. Patients received BSH doses between 12 and 100 mg/kg of body weight. For the evaluation, the infused boron dose was scaled linearly to 100 mg/kg BSH. Results: In BSH pharmacokinetics, the average value for total body clearance, distribution volume of steady state, and mean residence time was 3.6±1.5 L/h, 223.3±160.7 L, and 68.0±52.5 h, respectively. The average values of the boron concentration in tumor adjusted to 100 mg/kg BSH, the boron concentration in blood adjusted to 100 mg/kg BSH, and the tumor/blood boron concentration ratio were 37.1±35.8 ppm, 35.2±41.8 ppm, and 1.53±1.43, respectively. A good correlation was found between the logarithmic value of T adj and the interval from BSH infusion to tumor tissue sampling. About 12-19 h after infusion, the actual values for T adj and tumor/blood boron concentration ratio were 46.2±36.0 ppm and 1.70±1.06, respectively. The dose ratio between tumor and healthy tissue peaked in the same interval. Conclusion: For boron neutron capture therapy using BSH administered by intravenous infusion, this work confirms that neutron irradiation is optimal around 12-19 h after the infusion is started

  2. Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources

    International Nuclear Information System (INIS)

    David, W.I.F.; Jorgensen, J.D.

    1990-10-01

    The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which make Rietveld refinement possible for complex structures. In this paper we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods. 50 refs., 12 figs., 14 tabs

  3. On the resolution and intensity of a time-of-flight neutron reflectometer

    International Nuclear Information System (INIS)

    Well, A.A. van; Fredrikze, H.

    2005-01-01

    In a neutron reflection experiment, the reflectivity is determined as a function of wave-vector transfer q=4πθ/λ, with θ the glancing angle and λ the neutron wavelength. At a continuous neutron source, it may be advantageous to use the time-of-flight technique to determine λ. Then, a chopper system is used to pulse the beam. We will discuss all contributions to both q resolution and intensity. Special attention is paid to the comparison of using a single- and double-disc chopper system. Examples of the performance of both systems are given. The double-disc chopper produces a burst time proportional to λ. By matching the different contributions to the resolution, the resulting intensity can be optimised

  4. The IRK time-of-flight facility for measurements of double-differential neutron emission cross sections

    International Nuclear Information System (INIS)

    Pavlik, A.; Priller, A.; Steier, P.; Vonach, H.; Winkler, G.

    1994-01-01

    In order to improve the present experimental data base of energy- and angle-differential neutron emission cross sections at 14 MeV incident-neutron energy, a new time-of-flight (TOF) facility was installed at the Institut fuer Radiumforschung und Kernphysik (IRK), Vienna. The set-up was particularly designed to more precisely measure the high-energy part of the secondary neutron spectra and consists of three main components: (1) a pulsed neutron generator of Cockcroft-Walton type producing primary neutrons via the T(d,n)-reaction, (2) a tube system which can be evacuated containing the neutron flight path, the sample, collimators and the sample positioning system, and (3) the neutron detectors with the data acquisition equipment. Removing the air along the neutron flight path results in a drastic suppression of background due to air-scattered neutrons in the spectrum of the secondary neutrons. For every secondary neutron detected in the main detector, the time-of-flight, the pulse-shape information and the recoil energy are recorded in list-mode via a CAMAC system connected to a PDP 11/34 on-line computer. Using a Micro VAX, the multiparameter data are sorted and reduced to double-differential cross sections

  5. MONITORING SHORT-TERM COSMIC-RAY SPECTRAL VARIATIONS USING NEUTRON MONITOR TIME-DELAY MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Ruffolo, D.; Sáiz, A.; Mangeard, P.-S.; Kamyan, N.; Muangha, P. [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Nutaro, T.; Rujiwarodom, M.; Tooprakai, P. [Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400 (Thailand); Sumran, S.; Chaiwattana, C.; Gasiprong, N.; Channok, C.; Wuttiya, C. [Department of Physics, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190 (Thailand); Asavapibhop, B. [Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Bieber, J. W.; Clem, J.; Evenson, P. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Munakata, K., E-mail: david.ruf@mahidol.ac.th [Physics Department, Shinshu University, Matsumoto, Nagano 390-8621 (Japan)

    2016-01-20

    Neutron monitors (NMs) are ground-based detectors of cosmic-ray showers that are widely used for high-precision monitoring of changes in the Galactic cosmic-ray (GCR) flux due to solar storms and solar wind variations. In the present work, we show that a single neutron monitor station can also monitor short-term changes in the GCR spectrum, avoiding the systematic uncertainties in comparing data from different stations, by means of NM time-delay histograms. Using data for 2007–2014 from the Princess Sirindhorn Neutron Monitor, a station at Doi Inthanon, Thailand, with the world’s highest vertical geomagnetic cutoff rigidity of 16.8 GV, we have developed an analysis of time-delay histograms that removes the chance coincidences that can dominate conventional measures of multiplicity. We infer the “leader fraction” L of neutron counts that do not follow a previous neutron count in the same counter from the same atmospheric secondary, which is inversely related to the actual multiplicity and increases for increasing GCR spectral index. After correction for atmospheric pressure and water vapor, we find that L indicates substantial short-term GCR spectral hardening during some but not all Forbush decreases in GCR flux due to solar storms. Such spectral data from Doi Inthanon provide information about cosmic-ray energies beyond the Earth’s maximum geomagnetic cutoff, extending the reach of the worldwide NM network and opening a new avenue in the study of short-term GCR decreases.

  6. The multiple disk chopper neutron time-of-flight spectrometer at NIST

    International Nuclear Information System (INIS)

    Altorfer, F.B.; Cook, J.C.; Copley, J.R.D.

    1995-01-01

    A highly versatile multiple disk chopper neutron time-of-flight spectrometer is being installed at the Cold Neutron Research Facility of the National institute of Standards and Technology. This new instrument will fill an important gap in the portfolio of neutron inelastic scattering spectrometers in North America. It will be used for a wide variety of experiments such as studies of magnetic and vibrational excitations, tunneling spectroscopy, and quasielastic neutron scattering investigations of local and translational diffusion. The instrument uses disk choppers to monochromate and pulse the incident beam, and the energy changes of scattered neutrons are determined from their times-of-flight to a large array of detectors. The disks and the guide have been designed to make the instrument readily adaptable to the specific performance requirements of experimenters. The authors present important aspects of the design, as well as estimated values of the flux at the sample and the energy resolution for elastic scattering. The instrument should be operational in 1996

  7. Neutron measurements with Time-Resolved Event-Counting Optical Radiation (TRECOR) detector

    Science.gov (United States)

    Brandis, M.; Vartsky, D.; Dangendorf, V.; Bromberger, B.; Bar, D.; Goldberg, M. B.; Tittelmeier, K.; Friedman, E.; Czasch, A.; Mardor, I.; Mor, I.; Weierganz, M.

    2012-04-01

    Results are presented from the latest experiment with a new neutron/gamma detector, a Time-Resolved, Event-Counting Optical Radiation (TRECOR) detector. It is composed of a scintillating fiber-screen converter, bending mirror, lens and Event-Counting Image Intensifier (ECII), capable of specifying the position and time-of-flight of each event. TRECOR is designated for a multipurpose integrated system that will detect Special Nuclear Materials (SNM) and explosives in cargo. Explosives are detected by Fast-Neutron Resonance Radiography, and SNM by Dual Discrete-Energy gamma-Radiography. Neutrons and gamma-rays are both produced in the 11B(d,n+γ)12C reaction. The two detection modes can be implemented simultaneously in TRECOR, using two adjacent radiation converters that share a common optical readout. In the present experiment the neutron detection mode was studied, using a plastic scintillator converter. The measurements were performed at the PTB cyclotron, using the 9Be(d,n) neutron spectrum obtained from a thick Be-target at Ed ~ 13 MeV\\@. The basic characteristics of this detector were investigated, including the Contrast Transfer Function (CTF), Point Spread Function (PSF) and elemental discrimination capability.

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

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Malcolm J., E-mail: m.joyce@lancaster.ac.uk [Department of Engineering, Lancaster University, Lancaster, Lancashire LA1 4YW (United Kingdom); Agar, Stewart [Department of Engineering, Lancaster University, Lancaster, Lancashire LA1 4YW (United Kingdom); Aspinall, Michael D. [Hybrid Instruments Ltd., Gordon Manley Building, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YW (United Kingdom); Beaumont, Jonathan S.; Colley, Edmund; Colling, Miriam; Dykes, Joseph; Kardasopoulos, Phoevos; Mitton, Katie [Department of Engineering, Lancaster University, Lancaster, Lancashire LA1 4YW (United Kingdom)

    2016-10-21

    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 1.5×10{sup 7} per second into 4π and a maximum acquisition time of 2 h, to characterize two 100×100×100 mm{sup 3} 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.

  9. Dose and time dependent efficacy alteration of different defoliants on seed cotton yield.

    Science.gov (United States)

    Singh, Kulvir; Rathore, Pankaj; Singh, Kuldeep

    2015-07-01

    Field experiments were conducted during 2012 and 2013 to determine the effect of select defoliants i.e dropp ultra and ethrel, their optimal dose and suitable time of application on earliness and seed cotton yield in 3 American cotton cultivars. MRC7361BGII (3055.2 kg ha(-1)) and MRC7017BGII (2913.0 kg ha(-1)) resulted in significantly improved seed cotton yield as compared to F1 861 (2346.0 kg ha(-1)). Dropp ultra? @ 200 ml ha(-1) revealed highest yield (3018.7 kg ha(-1)) followed by ethrel @ 2000 ppm (2820.1 kg ha(-1)) and control (2730.0 kg ha(-1)) , while statistically least yield (2516.9 kg ha(-1)) was observed with higher dose of dropp ultra @ 225 ml ha(-1). Defoliants applied 150 days after sowing (DAS) resulted in significantly better yield (2853.3 kg ha(-1)) as compared to the early application at 140 DAS (2689.5 kg ha(-1) owing to improvement in open bolls and boll weight. Pooled data indicated that dropp ultra @ 200 ml ha(-1) has potential to promote crop earliness, better boll opening and their retention by keeping vegetative and reproductive growth in harmony to enhance seed cotton yield.

  10. Visualization of Crust in Metallic Piping Through Real-Time Neutron Radiography Obtained with Low Intensity Thermal Neutron Flux

    Directory of Open Access Journals (Sweden)

    Leandro C. Luiz

    2017-06-01

    Full Text Available The presence of crust on the inner walls of metallic ducts impairs transportation because crust completely or partially hinders the passage of fluid to the processing unit and causes damage to equipment connected to the production line. Its localization is crucial. With the development of the electronic imaging system installed at the Argonauta/Nuclear Engineering Institute (IEN/National Nuclear Energy Commission (CNEN reactor, it became possible to visualize crust in the interior of metallic piping of small diameter using real-time neutron radiography images obtained with a low neutron flux. The obtained images showed the resistance offered by crust on the passage of water inside the pipe. No discrepancy of the flow profile at the bottom of the pipe, before the crust region, was registered. However, after the passage of liquid through the pipe, images of the disturbances of the flow were clear and discrepancies in the flow profile were steep. This shows that this technique added the assembled apparatus was efficient for the visualization of the crust and of the two-phase flows.

  11. Visualization of crust in metallic piping through real-time neutron radiography obtained with low intensity thermal neutron flux

    Energy Technology Data Exchange (ETDEWEB)

    Luiz, Leandro C.; Crispim, Verginia R. [Nuclear Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro (Brazil); Ferreira, Francisco J. O. [National Nuclear Energy Commission, CNEN/IEN, Division Reactors, Rio de Janeiro (Brazil)

    2017-06-15

    The presence of crust on the inner walls of metallic ducts impairs transportation because crust completely or partially hinders the passage of fluid to the processing unit and causes damage to equipment connected to the production line. Its localization is crucial. With the development of the electronic imaging system installed at the Argonauta/Nuclear Engineering Institute (IEN)/National Nuclear Energy Commission (CNEN) reactor, it became possible to visualize crust in the interior of metallic piping of small diameter using real-time neutron radiography images obtained with a low neutron flux. The obtained images showed the resistance offered by crust on the passage of water inside the pipe. No discrepancy of the flow profile at the bottom of the pipe, before the crust region, was registered. However, after the passage of liquid through the pipe, images of the disturbances of the flow were clear and discrepancies in the flow profile were steep. This shows that this technique added the assembled apparatus was efficient for the visualization of the crust and of the two-phase flows.

  12. Optimized design of the chopper disks and the neutron guide in a disk chopper neutron time-of-flight spectrometer

    International Nuclear Information System (INIS)

    Copley, J.R.D.

    1990-01-01

    We consider important aspects of the performance of a disk chopper neutron time-of-flight spectrometer. The intensity at the sample position, and the contributions of the choppers to the resolution of the instrument, are evaluated as a function of the widths of the slots in the chopper disks and the width of the neutron guide between the disks. We find that there is an optimum choice of the ratios of these widths and that this choice depends on a single parameter which, for elastic scattering, is a simple ratio of distances. When pairs of counter-rotating disks are employed, the widths of the slots can be modified by grossly changing the phase relationship between the members of a chopper pair. If the slot widths are changed, the width of the guide should also be altered in order to maintain the spectrometer in an optimized state. This change in the guide width may be effectively achieved using an arrangement of nested guides. Resolution and intensity calculations demonstrate the important gains which may be realized using this approach. (orig.)

  13. Visualization of crust in metallic piping through real-time neutron radiography obtained with low intensity thermal neutron flux

    International Nuclear Information System (INIS)

    Luiz, Leandro C.; Crispim, Verginia R.; Ferreira, Francisco J. O.

    2017-01-01

    The presence of crust on the inner walls of metallic ducts impairs transportation because crust completely or partially hinders the passage of fluid to the processing unit and causes damage to equipment connected to the production line. Its localization is crucial. With the development of the electronic imaging system installed at the Argonauta/Nuclear Engineering Institute (IEN)/National Nuclear Energy Commission (CNEN) reactor, it became possible to visualize crust in the interior of metallic piping of small diameter using real-time neutron radiography images obtained with a low neutron flux. The obtained images showed the resistance offered by crust on the passage of water inside the pipe. No discrepancy of the flow profile at the bottom of the pipe, before the crust region, was registered. However, after the passage of liquid through the pipe, images of the disturbances of the flow were clear and discrepancies in the flow profile were steep. This shows that this technique added the assembled apparatus was efficient for the visualization of the crust and of the two-phase flows

  14. The new Athens center on data processing from the neutron monitor network in real time

    Directory of Open Access Journals (Sweden)

    Mavromichalaki

    2005-11-01

    Full Text Available The ground-based neutron monitors (NMs record galactic and solar relativistic cosmic rays which can play a useful key role in space weather forecasting, as a result of their interaction with interplanetary disturbances. The Earth's-based neutron monitor network has been used in order to produce a real-time prediction of space weather phenomena. Therefore, the Athens Neutron Monitor Data Processing Center (ANMODAP takes advantage of this unique multi-directional device to solve problems concerning the diagnosis and forecasting of space weather. At this moment there has been a multi-sided use of neutron monitors. On the one hand, a preliminary alert for ground level enhancements (GLEs may be provided due to relativistic solar particles and can be registered around 20 to 30 min before the arrival of the main part of lower energy particles responsible for radiation hazard. To make a more reliable prognosis of these events, real time data from channels of lower energy particles and X-ray intensity from the GOES satellite are involved in the analysis. The other possibility is to search in real time for predictors of geomagnetic storms when they occur simultaneously with Forbush effects, using hourly, on-line accessible neutron monitor data from the worldwide network and applying a special method of processing. This chance of prognosis is only being elaborated and considered here as one of the possible uses of the Neutron Monitor Network for forecasting the arrival of interplanetary disturbance to the Earth. The achievements, the processes and the future results, are discussed in this work.

  15. The new Athens center on data processing from the neutron monitor network in real time

    Directory of Open Access Journals (Sweden)

    Mavromichalaki

    2005-11-01

    Full Text Available The ground-based neutron monitors (NMs record galactic and solar relativistic cosmic rays which can play a useful key role in space weather forecasting, as a result of their interaction with interplanetary disturbances. The Earth's-based neutron monitor network has been used in order to produce a real-time prediction of space weather phenomena. Therefore, the Athens Neutron Monitor Data Processing Center (ANMODAP takes advantage of this unique multi-directional device to solve problems concerning the diagnosis and forecasting of space weather. At this moment there has been a multi-sided use of neutron monitors. On the one hand, a preliminary alert for ground level enhancements (GLEs may be provided due to relativistic solar particles and can be registered around 20 to 30 min before the arrival of the main part of lower energy particles responsible for radiation hazard. To make a more reliable prognosis of these events, real time data from channels of lower energy particles and X-ray intensity from the GOES satellite are involved in the analysis. The other possibility is to search in real time for predictors of geomagnetic storms when they occur simultaneously with Forbush effects, using hourly, on-line accessible neutron monitor data from the worldwide network and applying a special method of processing. This chance of prognosis is only being elaborated and considered here as one of the possible uses of the Neutron Monitor Network for forecasting the arrival of interplanetary disturbance to the Earth. The achievements, the processes and the future results, are discussed in this work.

  16. Timing of mounding for bambara groundnut affects crop development and yield in a rainfed tropical environment

    DEFF Research Database (Denmark)

    Ouedrago, Mahama; M'bi, Bertin Zagre; Liu, Fulai

    2013-01-01

    -ecological zone of Burkina Faso were conducted. Yield data confirm the findings from a drier part of Burkina Faso; i.e., mounding of bambara groundnut should not be carried out around the time of flowering. In a semi-arid area, such as Sudan–Sahel agro-ecological zone and with germplasm maturing within 90 days...

  17. Effect of boron application time on yield of wheat, rice and cotton crop in Pakistan

    Directory of Open Access Journals (Sweden)

    Riaz Ahmad* and Muhammad Irshad

    2011-04-01

    Full Text Available Boron (B, one of the essential micronutrients, plays vital role in plant growth. Thirty one field experimentswere conducted to evaluate the response of wheat, rice and cotton to B application throughout Pakistan during2005-08. Boron was applied at 1 kg ha-1 as Borax decahydrate (11.3% B at different times along withrecommended doses of N, P and K. The results revealed that B application at sowing time to wheat increasedsignificantly the number of tillers plant-1 (15%, number of grains spike-1 (11%, 1000-grain weight (7% and grainyield (10% over control. Among the treatments, B application at sowing time showed best results followed by Bapplication at 1st irrigation and at booting stage. In rice (coarse, B application before transplanting substantiallyincreased number of tillers hill-1 (21%, plant height (3%, panicle length (10%, and number of paddy grainspanicle-1 (17%, 1000-grain weight (11% and paddy yield (31% over control. Response of fine rice to Bapplication was similar for all yield parameters as in coarse rice. In cotton, B application considerably increasedplant height (3%, number of mature bolls plant-1 (12%, seed weight boll-1 (8% and seed cotton yield (9% overcontrol. Although, B application at all stages significantly increased yield parameters tested but B application atsowing time was best among all treatments.

  18. Grain yield and quality responses of tropical hybrid rice to high night-time temperature

    NARCIS (Netherlands)

    Shi, W.; Yin, X.; Struik, P.C.; Xie, F.; Schmidt, R.C.; Jagadish, K.S.V.

    2016-01-01

    High temperature has a pronounced effect on grain yield and quality in rice. Climate change has increased night temperature more than day temperature in many parts of the world. How rice responds to high night-time temperature (HNT) is largely unknown. This study presents the first effort to assess

  19. Modification of yield and composition of essential oils by distillation time

    Science.gov (United States)

    Field and laboratory experiments were conducted to model the length of the steam distillation time (DT) on essential oil yield and oil composition of peppermint, lemongrass, and palmarosa oils. The DTs tested were 1.25, 2.5, 5, 10, 20, 40, 80, and 160 min for peppermint, and 1.25, 2.5, 5, 10, 20, 40...

  20. Effect of time of fertilizer application on growth and yield of maize ...

    African Journals Online (AJOL)

    An experiment was carried out during the 2006 growing season, between June and November, to investigate the growth and yield responses of four varieties of maize (SUWAN-1-Y, TZSR-Y, DMESR-W and ACROSS-97 TZL) to time of fertilizer application (2,4 and 6 weeks after planting). The experiment was laid out in a 3 x ...

  1. The effect of autumn and spring planting time on seed yield and ...

    African Journals Online (AJOL)

    The objective of this study was to investigate the effects of autumn and spring plantings on seed yield and quality of chickpea genotypes. Fourteen chickpea genotypes were grown over the consecutive two growing seasons in northwest Turkey. The results showed that planting time had significant effects on the investigated ...

  2. Study on neutron diffusion and time dependence heat ina fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Vilhena, M.T. de.

    1988-01-01

    The purpose of this work is to model the neutron diffusion and heat transfer for a Fluidized Bed Nuclear Reactor and its solution by Laplace Transform Technique with numerical inversion using Fourier Series. Also Gaussian quadrature and residues techniques were applied for numerical inversion. The neutron transport, diffusion, and point Kinetic equation for this nuclear reactor concept are developed. A matricial and Taylor Series methods are proposed for the solution of the point Kinetic equation which is a time scale problem of Stiff type

  3. Measurement of detector neutron energy response using time-of-flight techniques

    International Nuclear Information System (INIS)

    Janee, H.S.

    1973-09-01

    The feasibility of using time-of-flight techniques at the EG and G/AEC linear accelerator for measuring the neutron response of relatively sensitive detectors over the energy range 0.5 to 14 MeV has been demonstrated. The measurement technique is described in detail as are the results of neutron spectrum measurements from beryllium and uranium photoneutron targets. The sensitivity of a fluor photomultiplier LASL detector with a 2- by 1-inch NE-111 scintillator was determined with the two targets, and agreement in the region of overlap was very good. (U.S.)

  4. Measurement of thick target neutron yield from the reaction (p+181 Ta) with projectiles in the range of 6-20 MeV

    Science.gov (United States)

    Paul, Sabyasachi; Sahoo, G. S.; Tripathy, S. P.; Sharma, S. C.; Joshi, D. S.; Bandyopadhyay, T.

    2018-02-01

    181Ta is a commonly used backing material for many targets in nuclear reaction studies. When the target thickness is less than the range of bombarded projectiles, the interaction via Ta(p,n) reactions in the backing can be a significant source of background. In this study, the neutron spectral yields from the reaction of protons of different energies (between 6 to 20 MeV) with a thick Ta target were determined using CR-39 detectors. The results from this study can be used as a correction factor in such situations. The parameters of registered tracks in CR-39 were analysed using an in-house image analysing program autoTRAK_n and then to derive the associated dose values. The spectral yields obtained experimentally were compared with those obtained from the theoretical calculations. The neutron yield was found to increase with increase in projectile energy mainly due to the opening of reaction channels from (p, n) to (p, 3n).

  5. Robust high-yield methodologies for (2)H and (2)H/(15)N/(13)C labeling of proteins for structural investigations using neutron scattering and NMR.

    Science.gov (United States)

    Duff, Anthony P; Wilde, Karyn L; Rekas, Agata; Lake, Vanessa; Holden, Peter J

    2015-01-01

    We have developed a method that has proven highly reliable for the deuteration and triple labeling ((2)H/(15)N/(13)C) of a broad range of proteins by recombinant expression in Escherichia coli BL21. Typical biomass yields are 40-80g/L wet weight, yielding 50-500mg/L purified protein. This method uses a simple, relatively inexpensive defined medium, and routinely results in a high-yield expression without need for optimization. The key elements are very tight control of expression, careful starter culture adaptation steps, media composition, and strict maintenance of aerobic conditions ensuring exponential growth. Temperature is reduced as required to prevent biological oxygen demand exceeding maximum aeration capacity. Glycerol is the sole carbon source. We have not encountered an upper limit for the size of proteins that can be expressed, achieving excellent expression for proteins from 11 to 154kDa and the quantity produced at 1L scale ensures that no small-angle neutron scattering, nuclear magnetic resonance, or neutron crystallography experiment is limited by the amount of deuterated material. Where difficulties remain, these tend to be cases of altered protein solubility due to high protein concentration and a D2O-based environment. © 2015 Elsevier Inc. All rights reserved.

  6. Time dependent and asymptotic neutron number probability distribution calculation using discrete Fourier transform

    International Nuclear Information System (INIS)

    Humbert, Ph.

    2005-01-01

    In this paper we consider the probability distribution of neutrons in a multiplying assembly. The problem is studied using a space independent one group neutron point reactor model without delayed neutrons. We recall the generating function methodology and analytical results obtained by G.I. Bell when the c 2 approximation is used and we present numerical solutions in the general case, without this approximation. The neutron source induced distribution is calculated using the single initial neutron distribution which satisfies a master (Kolmogorov backward) equation. This equation is solved using the generating function method. The generating function satisfies a differential equation and the probability distribution is derived by inversion of the generating function. Numerical results are obtained using the same methodology where the generating function is the Fourier transform of the probability distribution. Discrete Fourier transforms are used to calculate the discrete time dependent distributions and continuous Fourier transforms are used to calculate the asymptotic continuous probability distributions. Numerical applications are presented to illustrate the method. (author)

  7. Diting: A polarized time-of-flight neutron reflectometer at CMRR reactor in China

    Science.gov (United States)

    Li, Xinxi; Huang, Chaoqiang; Wang, Yan; Chen, Bo; Sun, Guang'ai; Liu, Yaoguang; Gong, Jian; Kang, Wu; Liu, Hangang

    2016-11-01

    A new time-of-flight neutron reflectometer with a polarization option is developed and tested at the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, China. Its scattering geometry is horizontal. The constructed neutron reflectometer is a multipurpose instrument that can be used for the characterization of a stratified microstructure and hidden interfaces of solid thin films. Diting is designed for both magnetic and nonmagnetic multi-layer thin films. Spin polarization and analysis are achieved by transmission magnetized supermirrors. The sample unit is equipped with an electromagnet, which can provide a vertical magnetic field range of 0-1.2 tesla. The available neutron beam is a white beam with wavelength range of 0.15-1.25 nm, which can be cut into different wavelength resolution neutron pulses by a four-disk chopper. A two-dimensional position-sensitive detector is employed to count the specular and off-specular reflected neutron beam. A minimum reflectivity of 10-6 is measured on this instrument.

  8. A neutron spectrometer based on the combination of time-of-flight and Larmor modulation

    International Nuclear Information System (INIS)

    Mulder, F.M.; Kreuger, R.; Grigoriev, S.V.; Kraan, W.H.; Rekveldt, M.Th.; Van Well, A.A.

    1999-01-01

    A study on the feasibility of neutron beam instrumentation that applies Larmor modulation for incoming, and time-of-flight for scattered wavelength determination (or vice versa) is currently under way at IRI. The instrument resulting from this combination can in principle measure quasi elastic and inelastic scattering with a flexible resolution and dynamic range. An important difference with current spectrometers is that there is no selection of neutron wavelengths for either the incoming beam (direct geometry) or scattered beam (inverted geometry). Therefore much of the available flux is used and there is no a priory selection of the energy transfer range and resolution. This instrument will be mainly applicable for quasi-elastic scattering and complex line shapes that are extended over a broad range in energy transfer. Line shapes can be measured directly in Fourier space, which is often advantageous. Due to signal to noise considerations, this instrument will be less suitable for the determination of weak, discrete energy transfer signals. A requirement for the Larmor modulator is that it can work with a white neutron beam. This can be realised for neutrons having a wavelength above ∼ 0.1 nm by use of 'adiabatic resonance π flippers'. This type of instrument may be applied at the future ESS pulsed neutron source in order to complement current spectrometers. (author)

  9. The Space-, Time-, and Energy-distribution of Neutrons from a Pulsed Plane Source

    Energy Technology Data Exchange (ETDEWEB)

    Claesson, Arne

    1962-05-15

    The space-, time- and energy-distribution of neutrons from a pulsed, plane, high energy source in an infinite medium is determined in a diffusion approximation. For simplicity the moderator is first assumed to be hydrogen gas but it is also shown that the method can be used for a moderator of arbitrary mass.

  10. Computer-controlled neutron time-of-flight spectrometer. Part II

    Energy Technology Data Exchange (ETDEWEB)

    Merriman, S.H.

    1979-12-01

    A time-of-flight spectrometer for neutron inelastic scattering research has been interfaced to a PDP-15/30 computer. The computer is used for experimental data acquisition and analysis and for apparatus control. This report was prepared to summarize the functions of the computer and to act as a users' guide to the software system.

  11. Neutron time-like electromagnetic form factor measurement with direct scan method at BESIII

    Energy Technology Data Exchange (ETDEWEB)

    Larin, Paul; Ahmed, Samer Ali Nasher; Lin, Dexu; Rosner, Christoph; Wang, Yadi [Helmholtz-Institut Mainz (Germany); Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz (Germany); Dbeyssi, Alaa; Morales, Cristina [Helmholtz-Institut Mainz (Germany); Maas, Frank [Helmholtz-Institut Mainz (Germany); Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz (Germany); PRISMA Cluster of Excellence, Johannes Gutenberg-Universitaet Mainz (Germany); Collaboration: BESIII-Collaboration

    2016-07-01

    The internal structure and dynamics of the neutron can be understood through the study of its electromagnetic (EM) form factors (FF). In comparison to proton FF measurements, less data on the neutron is available in the space-like as well as in the time-like region. None of the previous experiments were able to measure the ratio of the electric and the magnetic FF in the time-like region so far. The BESIII (Beijing Spectrometer III) experiment at BEPCII (Beijing Electron Positron Collider II) collected in 2014/15 a large sample of e{sup +}e{sup -} scan data in the region between 2.0 and 3.08 GeV with a total luminosity of 523.5 pb{sup -1}. With this poster we show our efforts to measure the effective FF of the neutron in a large energy region and the possibility to measure for the first time the ratio of the neutron form factors in the time-like region.

  12. Time factor of BSH from intravenous infusion to neutron irradiation for BNCT in patients with glioblastoma

    International Nuclear Information System (INIS)

    Kageji, T.; Nagahiro, S.; Kitamura, K.; Nakagawa, Y.; Hatanaka, H.; Haritz, D.; Grochulla, F.; Haselsberger, K.; Gabel, D.

    2000-01-01

    The present report evaluates the time factor of BSH from infusion to irradiation in patients with glioblastoma as a cooperative study in Europe and Japan. For BNCT with BSH after intravenous infusion, this work confirms that the planned neutron irradiation after intravenous BSH infusion appears to be optimal around 12-19 hours after the infusion. (author)

  13. AMOR–the time-of-flight neutron reflectometer at SINQ/PSI

    Indian Academy of Sciences (India)

    The apparatus for multioptional reflectometry (AMOR) at SINQ/PSI is a versatile reflectometer operational in the time-of-flight (TOF) mode (in a wavelength range of 0.15 nm > > 1.3 nm) as well as in the monochromatic ( - 2) mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry ...

  14. AMOR – the time-of-flight neutron reflectometer at SINQ/PSI

    Indian Academy of Sciences (India)

    Abstract. The apparatus for multioptional reflectometry (AMOR) at SINQ/PSI is a versatile reflectometer operational in the time-of-flight (TOF) mode (in a wavelength range of 0.15 nm <λ< 1.3 nm) as well as in the monochromatic mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry ...

  15. Dwell time dependent morphological transition and sputtering yield of ion sputtered Sn

    International Nuclear Information System (INIS)

    Qian, H X; Zeng, X R; Zhou, W

    2010-01-01

    Self-organized nano-scale patterns may appear on a wide variety of materials irradiated with an ion beam. Good manipulation of these structures is important for application in nanostructure fabrication. In this paper, dwell time has been demonstrated to be able to control the ripple formation and sputtering yield on Sn surface. Ripples with a wavelength of 1.7 μm were observed for a dwell time in the range 3-20 μs, whereas much finer ripples with a wavelength of 540 nm and a different orientation were observed for a shorter dwell time in the range 0.1-2 μs. The sputtering yield increases with dwell time significantly. The results provide a new basis for further steps in the theoretical description of morphology evolution during ion beam sputtering.

  16. Time-of-flight neutron Bragg-edge transmission imaging of microstructures in bent steel plates

    International Nuclear Information System (INIS)

    Su, Yuhua; Oikawa, Kenichi; Harjo, Stefanus; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Zhang, Shuoyuan; Parker, Joseph Don; Sato, Hirotaka; Shiota, Yoshinori; Kiyanagi, Yoshiaki; Tomota, Yo

    2016-01-01

    Neutron Bragg-edge transmission imaging makes it possible to quantitatively visualize the two-dimensional distribution of microstructure within a sample. In order to examine its application to engineering products, time-of-flight Bragg-edge transmission imaging experiments using a pulsed neutron source were performed for plastically bent plates composed of a ferritic steel and a duplex stainless steel. The non-homogeneous microstructure distributions, such as texture, crystalline size, phase volume fraction and residual elastic strain, were evaluated for the cross sections of the bent plates. The obtained results were compared with those by neutron diffraction and electron back scatter diffraction, showing that the Bragg-edge transmission imaging is powerful for engineering use.

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

    CERN Multimedia

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

  18. 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.)

  19. Retail yield and fabrication times for veal as influenced by purchasing options and merchandising styles.

    Science.gov (United States)

    McNeill, M S; Griffin, D B; Dockerty, T R; Walter, J P; Johnson, H K; Savell, J W

    1998-06-01

    Twenty-nine selected styles of subprimals or sections of veal were obtained from a commercial facility to assist in the development of a support program for retailers. They were fabricated into bone-in or boneless retail cuts and associated components by trained meat cutters. Each style selected (n = 6) was used to generate mean retail yields and labor requirements, which were calculated from wholesale and retail weights and processing times. Means and standard errors for veal ribs consisting of five different styles (n = 30) concluded that style #2, 7-rib 4 (10 cm) x 4 (10 cm), had the lowest percentage of total retail yield (P < .05) owing to the greatest percentage of bone. Furthermore, rib style #2 required the longest total processing time (P < .05). Rib styles #3, 7-rib chop-ready, and #5, 6-rib chop ready, yielded the greatest percentage of total retail yield and also had the shortest total processing time (P < .05). Within veal loins, style #2, 4 (10 cm) x 4 (10 cm) loin kidney fat in, had the greatest percentage fat (P < .05). Loin styles #2 and #3, 4 (10 cm) x 4 (10 cm) loin special trimmed, generated more lean and fat trimmings and bone, resulting in lower percentage of total retail yields than loin style #1, 0 (0 cm) x 1 (2.5 cm) loin special trimmed (P < .05). Results indicated that bone-in subprimals and sections required more processing time if fabricated into a boneless end point. In addition, as the number of different retail cuts increased, processing times also increased.

  20. Scintillation yield and time dependence from electronic and nuclear recoils in liquid neon

    Science.gov (United States)

    Lippincott, W. H.; Coakley, K. J.; Gastler, D.; Kearns, E.; McKinsey, D. N.; Nikkel, J. A.

    2012-07-01

    We have performed measurements of scintillation light in liquid neon, observing a signal yield in our detector as high as (3.5 ± 0.4) photoelectrons/keV. We measure pulse shape discrimination efficiency between electronic and nuclear recoils in liquid neon from 50 to 300 keV nuclear recoil energy. We also measure the Leff parameter in liquid neon between 30 and 370 keV nuclear recoil energy, observing an average Leff=0.24 above 50 keV. We observe a dependence of the scintillation time distribution and signal yield on the pressure and temperature of the liquid neon.

  1. Conception of a New Recoil Proton Telescope for Real-Time Neutron Spectrometry in Proton-Therapy

    Science.gov (United States)

    Combe, Rodolphe; Arbor, Nicolas; el Bitar, Ziad; Higueret, Stéphane; Husson, Daniel

    2018-01-01

    Neutrons are the main type of secondary particles emitted in proton-therapy. Because of the risk of secondary cancer and other late occurring effects, the neutron dose should be included in the out-of-field dose calculations. A neutron spectrometer has to be used to take into account the energy dependence of the neutron radiological weighting factor. Due to its high dependence on various parameters of the irradiation (beam, accelerator, patient), the neutron spectrum should be measured independently for each treatment. The current reference method for the measurement of the neutron energy, the Bonner Sphere System, consists of several homogeneous polyethylene spheres with increasing diameters equipped with a proportional counter. It provides a highresolution reconstruction of the neutron spectrum but requires a time-consuming work of signal deconvolution. New neutron spectrometers are being developed, but the main experimental limitation remains the high neutron flux in proton therapy treatment rooms. A new model of a real-time neutron spectrometer, based on a Recoil Proton Telescope technology, has been developed at the IPHC. It enables a real-time high-rate reconstruction of the neutron spectrum from the measurement of the recoil proton trajectory and energy. A new fast-readout microelectronic integrated sensor, called FastPixN, has been developed for this specific purpose. A first prototype, able to detect neutrons between 5 and 20 MeV, has already been validated for metrology with the AMANDE facility at Cadarache. The geometry of the new Recoil Proton Telescope has been optimized via extensive Geant4 Monte Carlo simulations. Uncertainty sources have been carefully studied in order to improve simultaneously efficiency and energy resolution, and solutions have been found to suppress the various expected backgrounds. We are currently upgrading the prototype for secondary neutron detection in proton therapy applications.

  2. Space-time neutronic analysis of postulated LOCA's in CANDU reactors

    International Nuclear Information System (INIS)

    Luxat, J.C.; Frescura, G.M.

    1978-01-01

    Space-time neutronic behaviour of CANDU reactors is of importance in the analysis and design of reactor safety systems. A methodology has been developed for simulating CANDU space-time neutronics with application to the analysis of postulated LOCA'S. The approach involves the efficient use of a set of computer codes which provide a capability to perform simulations ranging from detailed, accurate 3-dimensional space-time to low-cost survey calculations using point kinetics with some ''effective'' spatial content. A new, space-time kinetics code based upon a modal expansion approach is described. This code provides an inexpensive and relatively accurate scoping tool for detailed 3-dimensional space-time simulations. (author)

  3. Comparison of time domain reflectometry, capacitance methods and neutron scattering in soil moisture measurements

    International Nuclear Information System (INIS)

    Khorasani, A.; Mousavi Shalmani, M. A.; Piervali Bieranvand, N.

    2011-01-01

    An accurate, precise, fast and ease as well as the ability for measurements in depth are the characteristics that are desirable in measuring soil moisture methods. To compare methods (time domain reflectometry and capacitance) with neutron scattering for soil water monitoring, an experiment was carried out in a randomized complete block design (Split Split plot) on tomato with three replications on the experimental field of International Atomic Energy Agency (Seibersdorf-Austria). The treatment instruments for the soil moisture monitoring (main factor) consist of neutron gauge, Diviner 2000, time domain reflectometer and an EnviroScan and different irrigation systems (first sub factor) consist of trickle and furrow irrigations and different depths of soil (second sub factor) consist of 0-20, 20-40 and 40-60 cm. The results showed that for the neutron gauge and time domain reflectometer the amount of soil moisture in both of trickle and furrow irrigations were the same, but the significant differences were recorded in Diviner 2000 and EnviroScan measurements. The results of this study showed that the neutron gauge is an acceptable and reliable means with the modern technology, with a precision of ±2 mm in 450 mm soil water to a depth of 1.5 meter and can be considered as the most practical method for measuring soil moisture profiles and irrigation planning program. The time domain reflectometer method in most mineral soils, without the need for calibration, with an accuracy ±0.01m 3 m -3 has a good performance in soil moisture and electrical conductivity measurements. The Diviner 2000 and EnviroScan are not well suitable for the above conditions for several reasons such as much higher soil moisture and a large error measurement and also its sensitivity to the soil gap and to the small change in the soil moisture in comparison with the neutron gauge and the time domain reflectometer methods.

  4. Detection of renal cell carcinoma using neutron time of flight spectroscopy

    International Nuclear Information System (INIS)

    Viana, Rodrigo S.; Yoriyaz, Helio; Lakshmanan, Manu N.; Agasthya, Greeshma A.; Kapadia, Anuj J.

    2013-01-01

    The diagnosis of renal cell carcinoma (RCC) is challenging because the symptoms accompanying it are not unique to the disease, and can therefore be misdiagnosed as other diseases. Due to this characteristic, detection of renal cancer is incidental most of time, occurring via abdominal radiographic examinations unrelated to the disease. Presently, biopsy, which is invasive and an unpleasant procedure for the patient, is the most commonly used technique to diagnose RCC. In this study, we demonstrate the application of a novel noninvasive technique for detecting and imaging RCC in vivo. The elemental composition of biological tissues including kidneys has been investigated using a new technique called Neutron Stimulated Emission Computed Tomography (NSECT). This technique is based on detecting the energy signature emitted by the stable isotopes of elements in the body, which are stimulated to emit gamma radiation via inelastic neutron scattering. Methods for improving detection sensitivity and reducing dose, such as time-of-flight neutron spectroscopy have been explored. MCNP5 simulations were used to model the NSECT scanning of the human kidney where the energy and time of arrival of gamma photons were recorded in an ideal detector placed around the human torso. A 5 MeV collimated neutron beam was used to irradiate the kidney containing an RCC lesion. The resulting spectra were resolved in 100 picosecond and 1 keV time and energy bins, respectively. The preliminary results demonstrate the ability to localize the lesion through neutron time of flight spectroscopy and generate a tomographic image at a low dose to the patient. (author)

  5. DETERMINATION THE EFFECT OF DEFOLIATION TIMING ON COTTON YIELD AND QUALITY

    Directory of Open Access Journals (Sweden)

    Karademir Emine

    2007-12-01

    Full Text Available This study was carried out for determining the effect of different application times at 40, 50, 60 and 70 % boll opening and untreated plot of the defoliant on cotton yield, earliness and technological properties in Southeast Anatolia Region conditions in Turkey. Maras 92 cotton variety was used as plant material in the experiment field of the Southeast Anatolia Agricultural Research Institute during 2000-2001. Defoliant was including thidiazuron + diuron chemical substance. The result of this study showed that ginning percentage, 100 seed weight, seed germination percentage, fiber fineness, fiber length, fiber strength, reflectance, elongation and seed cotton yield were not affected by the treatment; plant height and first picking percentage in 2001, fiber uniformity in 2000 were 5 % significantly affected. This study showed that application of defoliant didn’t affect significantly yield and technological properties of cotton and after 40 % boll opening the defoliant can be used.

  6. Pulsed neutron generator

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

    1986-03-01

    The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

  7. Time-of-flight 3D Neutron Diffraction for Multigrain Crystallography

    DEFF Research Database (Denmark)

    Cereser, Alberto

    This thesis presents a new technique for measuring spatially resolved microstructures in crystalline materials using pulsed neutron beams. The method, called Time-of-Flight Three Dimensional Neutron Diffraction (ToF 3DND), identifies the position, shape and crystallographic orientation of the ind......This thesis presents a new technique for measuring spatially resolved microstructures in crystalline materials using pulsed neutron beams. The method, called Time-of-Flight Three Dimensional Neutron Diffraction (ToF 3DND), identifies the position, shape and crystallographic orientation...... measurements: a time resolved imaging detector, developed at University of Berkeley, California, was fitted in the interior of SENJU in order to record the extinction spots in the transmitted beam (i.e. areas with missing intensity due to Bragg diffraction of the individual grains). The arrangement of the two...... steps have been developed in this study. The work also shows that based on the transmission data alone the orientations are not uniquely determined; however, it is possible to find an unique solution by including diffraction signals from the imaging detector. The second version uses an existing method...

  8. OECD/NEA benchmark for time-dependent neutron transport calculations without spatial homogenization

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Jason, E-mail: jason.hou@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Ivanov, Kostadin N. [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Boyarinov, Victor F.; Fomichenko, Peter A. [National Research Centre “Kurchatov Institute”, Kurchatov Sq. 1, Moscow (Russian Federation)

    2017-06-15

    Highlights: • A time-dependent homogenization-free neutron transport benchmark was created. • The first phase, known as the kinetics phase, was described in this work. • Preliminary results for selected 2-D transient exercises were presented. - Abstract: A Nuclear Energy Agency (NEA), Organization for Economic Co-operation and Development (OECD) benchmark for the time-dependent neutron transport calculations without spatial homogenization has been established in order to facilitate the development and assessment of numerical methods for solving the space-time neutron kinetics equations. The benchmark has been named the OECD/NEA C5G7-TD benchmark, and later extended with three consecutive phases each corresponding to one modelling stage of the multi-physics transient analysis of the nuclear reactor core. This paper provides a detailed introduction of the benchmark specification of Phase I, known as the “kinetics phase”, including the geometry description, supporting neutron transport data, transient scenarios in both two-dimensional (2-D) and three-dimensional (3-D) configurations, as well as the expected output parameters from the participants. Also presented are the preliminary results for the initial state 2-D core and selected transient exercises that have been obtained using the Monte Carlo method and the Surface Harmonic Method (SHM), respectively.

  9. Estimation of optimum time interval for neutron- γ discrimination by simplified digital charge collection method

    International Nuclear Information System (INIS)

    Singh, Harleen; Singh, Sarabjeet

    2014-01-01

    The discrimination of mixed radiation field is of prime importance due to its application in neutron detection which leads to radiation safety, nuclear material detection etc. The liquid scintillators are one of the most important radiation detectors because the relative decay rate of neutron pulse is slower as compared to gamma radiation in these detectors. There are techniques like zero crossing and charge comparison which are very popular and implemented using analogue electronics. In the recent years due to availability of fast ADC and FPGA, digital methods for discrimination of mixed field radiations have been investigated. Some of the digital time domain techniques developed are pulse gradient analysis (PGA), simplified digital charge collection method (SDCC), digital zero crossing method. The performance of these methods depends on the appropriate selection of gate time for which the pulse is processed. In this paper, the SDCC method is investigated for a neutron-gamma mixed field. The main focus of the study is to get the knowledge of optimum gate time which is very important in neutron gamma discrimination analysis in a mixed radiation field. The comparison with charge collection (CC) method is also investigated

  10. Development of the STEFF detector for the neutron Time Of Flight facility (n_TOF), CERN

    CERN Document Server

    AUTHOR|(CDS)2092031

    Signicant work has been performed on the development of STEFF (SpecTrometer for Exotic Fission Fragments), a 2E2V (2-Energy 2-Velocity) spectrometer built by the University of Manchester Fission Group. The majority of this work was in the development of the time-of-flight systems, in particular the stop detector; with the main goals of improving the timing resolution and the detection eciency of the ssion fragments. Further development of the STEFF spectrometer was done to enable 2E2V measurements of the $^{235}$U(n,f) reaction with coincident measurements using a white neutron spectra of energies ranging from 10 meV to 200 MeV provided by the n_TOF (neutron Time Of Flight) facility, CERN. The STEFF spectrometer was successfully operated twice on the Experimental Area-2 high flux pulsed neutron beam line resulting in 2E2V measurements for ssion events with neutron energies ranging from 20 meV to 10 MeV. The first experiment received 1.36 X 10$^{18}$ POT (Protons On Target) with stable conditions and the seco...

  11. Effect of Harvest Time and Nitrogen Doses on Cassava Root Yield and Quality

    Directory of Open Access Journals (Sweden)

    Natália Trajano de Oliveira

    Full Text Available ABSTRACT Nitrogen is considered the most limiting nutrient for cassava, and N availability can influence the crop cycle, including earlier harvest. The aim of this study was to study the effect of harvest time on the production components of cassava, “Aciolina” cultivar, at different rates of N fertiliser. The experiment was carried out in an area newly incorporated into the productive system in a savannah ecosystem in the northern Amazon. A randomised block experimental design was used in a split plot arrangement with four replications. The N rates (0, 30, 60, 150, and 330 kg ha-1 were allocated to the main plots, and the harvest times (90, 120, 150, 180, 240, 300, and 360 days after emergence of the stalks - DAE were allocated to the subplots. Plant height, shoot fresh matter yield, number of roots per plant, average root diameter, and root fresh matter yield display an increasing linear response up to 360 DAE in cassava cv. “Aciolina”. For all harvest times, the N rates promote an increase in root fresh matter yield. At 300 and 360 DAE, the root fresh matter and starch yield and the harvest index show a quadratic response as a function of the N level. The greatest efficiency of N topdressing on the production of root fresh matter occurs at 300 DAE, promoting an earlier harvest. At that time, the dose of maximum technical efficiency, 226 kg ha-1 N, results in a yield of 62 Mg ha-1 of root fresh matter, 13 Mg ha-1 of starch, and a harvest index of 81 %.

  12. Hydrodistillation extraction time effect on essential oil yield, composition, and bioactivity of coriander oil.

    Science.gov (United States)

    Zheljazkov, Valtcho D; Astatkie, Tess; Schlegel, Vicki

    2014-01-01

    Coriander (Coriandrum sativum L.) is a major essential oil crop grown throughout the world. Coriander essential oil is extracted from coriander fruits via hydrodistillation, with the industry using 180-240 min of distillation time (DT), but the optimum DT for maximizing essential oil yield, composition of constituents, and antioxidant activities are not known. This research was conducted to determine the effect of DT on coriander oil yield, composition, and bioactivity. The results show that essential oil yield at the shorter DT was low and generally increased with increasing DT with the maximum yields achieved at DT between 40 and 160 min. The concentrations of the low-boiling point essential oil constituents: α-pinene, camphene, β-pinene, myrcene, para-cymene, limonene, and γ-terpinene were higher at shorter DT (essential oil constituent, linalool, was 51% at DT 1.15 min, and increased steadily to 68% with increasing DT. In conclusion, 40 min DT is sufficient to maximize yield of essential oil; and different DT can be used to obtain essential oil with differential composition. Its antioxidant capacity was affected by the DT, with 20 and 240 min DT showing higher antioxidant activity. Comparisons of coriander essential oil composition must consider the length of the DT.

  13. Effect of Time and Level of Pruning on Vegetative Growth, Flowering, Yield, and Quality of Guava

    DEFF Research Database (Denmark)

    Adhikari, Shiva; Kandel, Tanka Prasad

    2015-01-01

    Poor quality fruit production in the rainy season and failure to manipulate production periods are common problems for guava production in India and Nepal. As a possible management to overcome these problems, a field experiment was conducted to understand the effect of time and level of pruning...... on growth, flowering, yield, and quality of guava. An experiment was laid out with split-pot design allocating three pruning times (mid-April, early May, and mid-May) and four pruning levels (0-, 10-, 20-, and 30-cm tip removal) with three replications in each treatment. Increased level of pruning in early...... (%) of fruits increased with the increased level of pruning in both seasons irrespective of timing of pruning, but fruit acidity was not affected by both treatments. In conclusion, pruning plants at a 20 cm pruning level in early May was the most effective management to reduce yield in the rainy season...

  14. SEVERITY OF RAMULARIA LEAF SPOT AND SEED COTTON YIELD IN DIFFERENT SOWING TIMES

    Directory of Open Access Journals (Sweden)

    JOÃO PAULO ASCARI

    2016-01-01

    Full Text Available The ramularia leaf spot (RLS disease causes cotton yield losses. Choosing a less susceptible cultivar and a sowing time that are less favorable to the pathogen contribute to the management of this disease. The objective of this work was to evaluate the severity of ramularia leaf spot on cotton cultivars sowed in two different times. The experiment was conducted in a triple factorial design (4x3x2, consisted of four cultivars, the three thirds of the plant and two sowing times, with four replications. Each plot was divided in two twin plots, one with fungicide application (with disease control and the other without fungicide application (without disease control. The severity assessments were performed every seven days, considering each third of the plant with a diagrammatic scale. Yield was evaluated in each plot. There was a significant interaction between sowing times and the thirds of the plant in the plots without disease control for RLS severity, with the highest values of area under the disease progress curve (AUDPC in the first sowing time (ST1 and in the lower third of the plant. The FMT705 cultivar had the highest and FM951LL the lowest value of AUDPC. The AUDPC of these cultivars were no statistically different in the second sowing time (ST2, but they had higher AUDPC values in the lower third. Highest yields were found with ST1 in plots with disease control, with no differences between the cultivars, however, lower yields were found in plots without disease control.

  15. The Magnetic Recoil Spectrometer for time-resolved neutron measurements (MRSt) at the NIF

    Science.gov (United States)

    Parker, C. E.; Frenje, J. A.; Wink, C. W.; Gatu Johnson, M.; Lahmann, B.; Li, C. K.; Seguin, F. H.; Petrasso, R. D.; Hilsabeck, T. J.; Kilkenny, J. D.; Bionta, R.; Casey, D. T.; Khater, H. Y.; Forrest, C. J.; Glebov, V. Yu.; Sorce, C.; Hares, J. D.; Siegmund, O. H. W.

    2017-10-01

    The next-generation Magnetic Recoil Spectrometer, called MRSt, will provide time-resolved measurements of the DT-neutron spectrum. These measurements will provide critical information about the time evolution of the fuel assembly, hot-spot formation, and nuclear burn in Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). The neutron spectrum in the energy range 12-16 MeV will be measured with high accuracy ( 5%), unprecedented energy resolution ( 100 keV) and, for the first time ever, time resolution ( 20 ps). An overview of the physics motivation, conceptual design for meeting these performance requirements, and the status of the offline tests for critical components will be presented. This work was supported in part by the U.S. DOE, LLNL, and LLE.

  16. Cf-252 based neutron radiography using real-time image processing system

    International Nuclear Information System (INIS)

    Mochiki, Koh-ichi; Koiso, Manabu; Yamaji, Akihiro; Iwata, Hideki; Kihara, Yoshitaka; Sano, Shigeru; Murata, Yutaka

    2001-01-01

    For compact Cf-252 based neutron radiography, a real-time image processing system by particle counting technique has been developed. The electronic imaging system consists of a supersensitive imaging camera, a real-time corrector, a real-time binary converter, a real-time calculator for centroid, a display monitor and a computer. Three types of accumulated NR image; ordinary, binary and centroid images, can be observed during a measurement. Accumulated NR images were taken by the centroid mode, the binary mode and ordinary mode using of Cf-252 neutron source and those images were compared. The centroid mode presented the sharpest image and its statistical characteristics followed the Poisson distribution, while the ordinary mode showed the smoothest image as the averaging effect by particle bright spots with distributed brightness was most dominant. (author)

  17. Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

    Science.gov (United States)

    Noguere, G.; Tommasi, J.; Privas, E.; Schmidt, K.-H.; Rochman, D.

    2018-03-01

    Systematics of cumulative fission yields of the neodymium isotopes for the thermal and fast neutron fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu were obtained by combining integral results from the PROFIL experiments with theoretical calculations from the GEF code. The systematic behavior with the neodymium mass number ( A = 143, 145, 146, 148, 150) deduced from the experimental trends is consistent with the smooth variation predicted by the GEF calculations, excepted for the 238U(n,f) reaction. For this system, isotopic and isotonic effects in fission-fragment shell structures are not adequately taken into account in the theoretical calculation. The obtained results also confirm the weak energy dependence of the Nd cumulative fission yields in the energy range of interest for thermal and sodium fast reactors. They suggest an energy dependency comparable to the experimental uncertainty which lies below 3%, for the 235U, 239Pu and 241Pu fissile isotopes.

  18. Analytical applications for delayed neutrons

    International Nuclear Information System (INIS)

    Eccleston, G.W.

    1983-01-01

    Analytical formulations that describe the time dependence of neutron populations in nuclear materials contain delayed-neutron dependent terms. These terms are important because the delayed neutrons, even though their yields in fission are small, permit control of the fission chain reaction process. Analytical applications that use delayed neutrons range from simple problems that can be solved with the point reactor kinetics equations to complex problems that can only be solved with large codes that couple fluid calculations with the neutron dynamics. Reactor safety codes, such as SIMMER, model transients of the entire reactor core using coupled space-time neutronics and comprehensive thermal-fluid dynamics. Nondestructive delayed-neutron assay instruments are designed and modeled using a three-dimensional continuous-energy Monte Carlo code. Calculations on high-burnup spent fuels and other materials that contain a mix of uranium and plutonium isotopes require accurate and complete information on the delayed-neutron periods, yields, and energy spectra. A continuing need exists for delayed-neutron parameters for all the fissioning isotopes

  19. Two-phase fluid flow measurements in small diameter channels using real-time neutron radiography

    International Nuclear Information System (INIS)

    Carlisle, B.S.; Johns, R.C.; Hassan, Y.A.

    2004-01-01

    A series of real-time, neutron radiography, experiments are ongoing at the Texas A and M Nuclear Science Center Reactor (NSCR). These tests determine the resolving capabilities for radiographic imaging of two phase water and air flow regimes through small diameter flow channels. Though both film and video radiographic imaging is available, the real-time video imaging was selected to capture the dynamic flow patterns with results that continue to improve. (author)

  20. Testing P-even time reversal invariance with MeV neutrons

    International Nuclear Information System (INIS)

    Gould, C.R.; Haase, D.G.; Keith, C.D.; Seely, M.L.; Huffman, P.R.; Roberson, N.R.; Wilburn, W.S.

    1995-01-01

    A new measurement of the parity-conserving, time reversal noninvariant (PC TRNI) fivefold correlation has been performed at TUNL, using 6.7 MeV polarized neutrons and a cryogenically aligned holmium target. The PC TRNI spin correlation coefficient A 5 is measured to be (1.1±2.3)x10 -5 , consistent with time reversal invariance. copyright 1995 American Institute of Physics

  1. SEVERITY OF RAMULARIA LEAF SPOT AND SEED COTTON YIELD IN DIFFERENT SOWING TIMES

    OpenAIRE

    JOÃO PAULO ASCARI; DEJÂNIA VIEIRA DE ARAÚJO; LEONARDO DIOGO EHLE DIAS; GIOVANI JUNIOR BAGATINI; INÊS ROEDER NOGUEIRA MENDES

    2016-01-01

    The ramularia leaf spot (RLS) disease causes cotton yield losses. Choosing a less susceptible cultivar and a sowing time that are less favorable to the pathogen contribute to the management of this disease. The objective of this work was to evaluate the severity of ramularia leaf spot on cotton cultivars sowed in two different times. The experiment was conducted in a triple factorial design (4x3x2), consisted of four cultivars, the three thirds of the plant and two sowing times, with four rep...

  2. Neutron radiography, a powerful method to determine time-dependent moisture distributions in concrete

    International Nuclear Information System (INIS)

    Zhang Peng; Wittmann, Folker H.; Zhao Tiejun; Lehmann, Eberhard H.; Vontobel, Peter

    2011-01-01

    Highlights: ► For the first time water movement in cement-based materials could be quantified in a non-destructive way. ► neutron radiography has a sensitivity and a spatial resolution unknown so far. ► Results are essential for prediction of service life. ► Results will contribute to more durable and more ecological construction. - Abstract: Service life of reinforced concrete structures is often limited by penetration of water and compounds dissolved in water into concrete. Concrete can be damaged in this way and corrosion of steel reinforcement can be initiated. There is an urgent need to study water penetration into concrete in order to better understand deterioration mechanisms and to find appropriate ways to improve durability. Neutron radiography provides us with an advanced non-destructive technique with high spatial resolution and extraordinary sensitivity. In this contribution, neutron radiography was successfully applied to study the process of water absorption of two types of concrete with different water–cement ratios, namely 0.4 and 0.6. The influence cracks and of water repellent treatment on water absorption has been studied on mortar specimens. It is possible to visualize migration of water into concrete and other cement-based composites and to quantify the time-dependent moisture distributions as function of time with high spatial resolution by means of neutron radiography. Water penetration depth obtained from neutron radiography is in good agreement with corresponding values obtained from capillary suction tests. Surface impregnation of concrete with silane prevents capillary uptake of water. Even fine cracks are immediately filled with water as soon as the surface gets in contact. Results provide us with a solid basis for a better understanding of deteriorating processes in concrete and other cement-based materials.

  3. First records of thermal neutrons with the spectrometer for time of flight (TOF) in the RP-10 Nuclear Reactor

    International Nuclear Information System (INIS)

    Munive, M.; Baltuano, O; Soto, C; Ravello, Y

    2002-01-01

    To obtain the first spectrum of an emergent beam of neutrons of a nuclear reactor is the main parameter of the characterization in the use of this reactor; one of ways to get this spectrum is for the technique of time of flight, TOF, which registers the time that a neutron need to cover a certain distance, associating this time then to the kinetic energy of the neutron. The kinetic study of the beam of neutrons is carried out on neutron pulses that are generated by a revolving choke called Chopper; and the analysis in the time of the detected pulses is carried out for a system MCS. Using this technique it is achieved the record of the spectra in energy, or in wavelength , of the irradiation facilities No 2 and 4, and of the exit N o 5 of the thermal column of the Nuclear Reactor RP-10 of the Nuclear Center Oscar de la Guerra RACSO, Peru (au)

  4. Real-time multi-mode neutron multiplicity counter

    Science.gov (United States)

    Rowland, Mark S; Alvarez, Raymond A

    2013-02-26

    Embodiments are directed to a digital data acquisition method that collects data regarding nuclear fission at high rates and performs real-time preprocessing of large volumes of data into directly useable forms for use in a system that performs non-destructive assaying of nuclear material and assemblies for mass and multiplication of special nuclear material (SNM). Pulses from a multi-detector array are fed in parallel to individual inputs that are tied to individual bits in a digital word. Data is collected by loading a word at the individual bit level in parallel, to reduce the latency associated with current shift-register systems. The word is read at regular intervals, all bits simultaneously, with no manipulation. The word is passed to a number of storage locations for subsequent processing, thereby removing the front-end problem of pulse pileup. The word is used simultaneously in several internal processing schemes that assemble the data in a number of more directly useable forms. The detector includes a multi-mode counter that executes a number of different count algorithms in parallel to determine different attributes of the count data.

  5. Stochastic analog reactor period - time achievement a given level of number of neutrons

    International Nuclear Information System (INIS)

    Ryazanov, V.V.

    2012-01-01

    In theory and in practice the operation of nuclear reactors to control the safety of the reactor is widely used the deterministic value of period of the reactor. It is proposed along with the period of the reactor using a stochastic analogue of this magnitude - a random value of time to achieve a given level of a random process for the number of neutrons in the reactor. The paper discusses various models for the distribution function of the lifetime of neutrons in the reactor, the knowledge which is important in the study of time to achieve the level and impact of the maximum possible time to achieve the level of the characteristics of the random variable

  6. Fragment Angular Distributions in Neutron-Induced Fission of w235U and 239Pu using a Time Projection Chamber

    Science.gov (United States)

    Kleinrath, Verena

    2014-09-01

    Fission fragment angular distributions can lend insights into fission barrier shapes and level densities at the scission point, both important for fission theory development. Fragment emission anisotropies are also valuable for precision cross section ratio measurements, if the distributions are different for the two isotopes used in the ratio. Available angular data is sparse for 235U and even more so for 239Pu, especially at neutron energies above 5 MeV. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) time projection chamber, which enables precise tracking of charged particles, can be used to study angular distributions and emission anisotropies of fission fragments in neutron-induced fission. Analysis of in-beam data collected at the Los Alamos Neutron Science Center with a 239Pu/235U target will provide angular distributions as a function of incident neutron energy for these isotopes. Preliminary angular distributions for 235U and 239Pu using the NIFFTE time projection chamber will be presented. Fission fragment angular distributions can lend insights into fission barrier shapes and level densities at the scission point, both important for fission theory development. Fragment emission anisotropies are also valuable for precision cross section ratio measurements, if the distributions are different for the two isotopes used in the ratio. Available angular data is sparse for 235U and even more so for 239Pu, especially at neutron energies above 5 MeV. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) time projection chamber, which enables precise tracking of charged particles, can be used to study angular distributions and emission anisotropies of fission fragments in neutron-induced fission. Analysis of in-beam data collected at the Los Alamos Neutron Science Center with a 239Pu/235U target will provide angular distributions as a function of incident neutron energy for these isotopes. Preliminary angular distributions for 235U and

  7. Small angle neutron scattering at very high time resolution: Principle and simulations of 'TISANE'

    International Nuclear Information System (INIS)

    Kipping, D.; Gaehler, R.; Habicht, K.

    2008-01-01

    The time resolution of SANS experiments is generally limited by frame overlap to some ms. We report on a new time-resolved stroboscopic SANS method, called TISANE, offering μs time resolution without a major sacrifice in intensity by making use of very large frame overlap. We may explore a new field in neutron scattering and complement the emerging field of time resolved small angle X-ray scattering. Here we discuss the principle of TISANE, its mathematical treatment and its limitations

  8. Short collision time approximation for neutron scattering using discrete frequency distributions

    International Nuclear Information System (INIS)

    Ryskamp, J.M.

    1980-01-01

    A completely general form for computing any scattering cross section based on the incoherent approximation without extending f(ω) to negative frequencies and without integrating over the complex plane is presented. A simple derivation of the short collision time approximation for discrete frequency distributions is also given. The approximation works well for large incident neutron energies when the duration of a collision is short compared with the natural periods of atomic motion. Single-differential scattering cross sections for light water as computed with the free proton and Nelkin scattering models at 561 0 K, and the short collision time approximation with T/sub eff/ = 1468 0 K, are shown for an incident neutron energy of 1.0 eV. 1 figure

  9. A time-of-flight spectrometer for neutron diffraction under high pressure or at high temperature

    International Nuclear Information System (INIS)

    Roult, G.; Buevoz, J.L.

    1975-01-01

    For high pressure neutron diffraction studies (40 kilobars) the sample is placed in a very thick cell. In order to allow the neutron beam to go through the cell loosing as little intensity as possible, the inner part is kept solid while the external part has some windows facing the incident and reflected beam. The window dimensions are small (a few millimeters wide and a few centimeters long). There are two alternatives: to have the window either in a perpendicular plane or in a plane parallel to the axis. In the first case a fixed wavelength spectrometer can be used but the sample is small and the contribution of the cell to the diffraction pattern is relatively great. In the second case samples can be something like ten times greater and the cell contribution can be eliminated but a fixed wavelength spectrometer cannot be used. Thus the time-of-flight method is very convenient. The second alternative was chosen

  10. Study of parity and time reversal violation in neutron-nucleus interactions

    International Nuclear Information System (INIS)

    Yen, Yi-Fen; Bowman, J.D.; Frankle, C.M.; Crawford, B.E.

    1994-01-01

    The parity and time-reversal symmetries can be studies in neutron-nucleus interactions. Parity non-conserving asymmetries have been observed for many p-wave resonances in a compound nucleus and measurements were performed on several nuclei in the mass region of A∼100 and A∼230. The statistical model of the compound nucleus provides a theoretical basis for extracting mean-squared matrix elements from the experimental asymmetry data, and for interpreting the mean-squared matrix elements. The constraints on the weak meson-exchange couplings calculated from the compound-nucleus asymmetry data agree qualitatively with the results from few-body and light-nuclei experiments. The tests of time-reversal invariance in various experiments using thermal, epithermal and MeV neutrons are being developed

  11. Time-resolved small-angle neutron scattering of a micelle-to-vesicle transition

    Energy Technology Data Exchange (ETDEWEB)

    Egelhaaf, S.U. [Institut Max von Laue - Paul Langevin (ILL), 38 -Grenoble (France); Schurtenberger, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-04-01

    Amphiphilic molecules spontaneously self-assemble in solution to form a variety of aggregates. Only limited information is available on the kinetics of the structural transitions as well as on the existence of non-equilibrium or metastable states. Aqueous mixtures of lecithin and bile salt are very interesting biological model-systems which exhibit a spontaneous transition from polymer-like mixed micelles to vesicles upon dilution. The small-angle neutron scattering (SANS) instrument D22, with its very high neutron flux and the broad range of scattering vectors covered in a single instrumental setting, allowed us for the first time to perform time-resolved scattering experiments in order to study the micelle-to-vesicle transition. The temporal evolution of the aggregate structures were followed and detailed information was obtained even on molecular length-scales. (author). 5 refs.

  12. Energy dependence of fission product yields from 235U, 238U, and 239Pu with monoenergetic neutrons between thermal and 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Arnold, Charles; Bhike, Megha; Bredeweg, Todd; Fowler, Malcolm; Krishichayan; Tonchev, Anton; Tornow, Werner; Stoyer, Mark; Vieira, David; Wilhelmy, Jerry

    2017-09-01

    Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements has been performed. The energy dependence of a number of cumulative fission product yields (FPY) have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of fission counting using specially designed dual-fission chambers and γ-ray counting. Each dual-fission chamber is a back-to-back ionization chamber encasing an activation target in the center with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the total number of fissions in the activation target with no reference to the fission cross-section, thus reducing uncertainties. γ-ray counting of the activation target was performed on well-shielded HPGe detectors over a period of two months post irradiation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 3.6, 4.6, 5.5, 7.5, 8.9 and 14.8 MeV. Preliminary results from thermal irradiations at the MIT research reactor will also be presented and compared to present data and evaluations. This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Security, LLC under contract DE-AC52-06NA25396, Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and by Duke University and Triangle Universities Nuclear Laboratory through NNSA Stewardship Science Academic Alliance grant No. DE-FG52-09NA29465, DE-FG52-09NA29448 and Office of Nuclear Physics Grant No. DE-FG02-97ER41033.

  13. Time resolved analysis of water drainage in porous asphalt concrete using neutron radiography.

    Science.gov (United States)

    Poulikakos, L D; Sedighi Gilani, M; Derome, D; Jerjen, I; Vontobel, P

    2013-07-01

    Porous asphalt as a road surface layer controls aquaplaning as rain water can drain through its highly porous structure. The process of water drainage through this permeable layer is studied using neutron radiography. Time-resolved water configuration and distribution within the porous structure are reported. It is shown that radiography depicts the process of liquid water transport within the complex geometry of porous asphalt, capturing water films, filled dead end pores and water islands. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Deformation dynamics study of a wrought magnesium alloy by real-time in situ neutron diffraction

    International Nuclear Information System (INIS)

    Wu, Wei; An, Ke; Huang, Lu; Lee, Soo Yeol; Liaw, Peter K.

    2013-01-01

    The deformation dynamics and the effect of deformation history on plastic deformation in a wrought magnesium alloy at room temperature have been studied by real-time in situ neutron diffraction measurements under a continuous loading condition. The experimental results reveal that no detwinning occurred during unloading after compression and even in an elastic region during reverse tension. It is found that the serration behavior is closely related to the twinning- and detwinning-dominated deformation

  15. Parameters’ Covariance in Neutron Time of Flight Analysis – Explicit Formulae

    Energy Technology Data Exchange (ETDEWEB)

    Odyniec, M. [NSTec; Blair, J. [NSTec

    2014-12-01

    We present here a method that estimates the parameters’ variance in a parametric model for neutron time of flight (NToF). The analytical formulae for parameter variances, obtained independently of calculation of parameter values from measured data, express the variances in terms of the choice, settings, and placement of the detector and the oscilloscope. Consequently, the method can serve as a tool in planning a measurement setup.

  16. Time-resolved small-angle neutron scattering study on soap-free emulsion polymerization

    International Nuclear Information System (INIS)

    Motokawa, Ryuhei; Koizumi, Satoshi; Hashimoto, Takeji; Nakahira, Takayuki; Annaka, Masahiko

    2006-01-01

    We investigated an aqueous soap-free emulsion polymerization process of Poly(N-isopropylacrylamide)-block-poly(ethylene glycol) by ultra-small-angle and time-resolved small-angle neutron scattering methods. The results indicate that the compartmentalization of chain end radicals into solid-like micelle cores crucially leads to the quasi-living behavior of the radical polymerization by prohibiting recombination process

  17. SLUDGE BATCH SUPPLEMENTAL SRAT RUNS EFFECTS OF YIELD STRESS AND CYCLE TIME INCREASE

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.

    2010-08-10

    The Defense Waste Processing Facility (DWPF) has transitioned from Sludge Batch 5 (SB5) processing to Sludge Batch 6 (SB6) processing. Phase III-Tank 40 Chemical Process Cell (CPC) flowsheet simulations have been completed to determine the initial processing conditions for the DWPF transition. The impact of higher yield stress (SB-25) and cycle time extension (SB6-26) on the physical and chemical effects of SB6 processing during the SRAT (Sludge Receipt and Adjustment Tank) cycle were evaluated. No significant impacts on the SRAT chemistry were noted during the higher yield stress run. In particular, no impact on mercury stripping was noted, indicating that settling of elemental mercury was not the primary factor in the low mercury recovery noted in the flowsheet testing. The SRAT product from this run retained the higher yield stress of the starting sludge. The run indicated that ultrasonication is an effective tool to increase the yield stress of simulants to targeted values and the chemistry of downstream processing is not impacted. Significant differences were noted in the cycle time extension test compared to the Phase III flowsheet baseline runs. Large decreases in the ammonia and hydrogen generation rates were noted along with reduced mercury stripping efficiency. The latter effect is similar to that of operating under a high acid stoichiometry. It is conceivable that, under the distinctly different conditions of high formic acid concentration (high acid run) or slow formic acid addition (extended run), that mercury could form amalgams with noble metals, possibly rendering both inert. Thus, the removal of free mercury and noble metals could decrease the rate of catalytic formic acid reactions which would decrease generation of ammonium and hydrogen. The potential underlying reasons for the behavior noted during this run would require additional testing.

  18. Applications of a micro-pixel chamber (μPIC) based, time-resolved neutron imaging detector at pulsed neutron beams

    Science.gov (United States)

    Parker, J. D.; Harada, M.; Hattori, K.; Iwaki, S.; Kabuki, S.; Kishimoto, Y.; Kubo, H.; Kurosawa, S.; Matsuoka, Y.; Miuchi, K.; Mizumoto, T.; Nishimura, H.; Oku, T.; Sawano, T.; Shinohara, T.; Suzuki, J.-I.; Takada, A.; Tanimori, T.; Ueno, K.; Ikeno, M.; Tanaka, M.; Uchida, T.

    2014-04-01

    The realization of high-intensity, pulsed spallation neutron sources such as J-PARC in Japan and SNS in the US has brought time-of-flight (TOF) based neutron techniques to the fore and spurred the development of new detector technologies. When combined with high-resolution imaging, TOF-based methods become powerful tools for direct imaging of material properties, including crystal structure/internal strain, isotopic/temperature distributions, and internal and external magnetic fields. To carry out such measurements in the high-intensities and high gamma backgrounds found at spallation sources, we have developed a new time-resolved neutron imaging detector employing a micro-pattern gaseous detector known as the micro-pixel chamber (μPIC) coupled with a field-programmable-gate-array-based data acquisition system. The detector combines 100μm-level (σ) spatial and sub-μs time resolutions with low gamma sensitivity of less than 10-12 and a rate capability on the order of Mcps (mega-counts-per-second). Here, we demonstrate the application of our detector to TOF-based techniques with examples of Bragg-edge transmission and neutron resonance transmission imaging (with computed tomography) carried out at J-PARC. We also consider the direct imaging of magnetic fields with our detector using polarized neutrons.

  19. A time-dependent neutron transport model and its coupling to thermal-hydraulics

    International Nuclear Information System (INIS)

    Pautz, A.

    2001-01-01

    A new neutron transport code for time-dependent analyses of nuclear systems has been developed. The code system is based on the well-known Discrete Ordinates code DORT, which solves the steady-state neutron/photon transport equation in two dimensions for an arbitrary number of energy groups and the most common regular geometries. For the implementation of time-dependence a fully implicit first-order scheme was employed to minimize errors due to temporal discretization. This requires various modifications to the transport equation as well as the extensive use of elaborated acceleration mechanisms. The convergence criteria for fluxes, fission rates etc. had to be strongly tightened to ensure the reliability of results. To perform coupled analyses, an interface to the GRS system code ATHLET has been developed. The nodal power densities from the neutron transport code are passed to ATHLET to calculate thermal-hydraulic system parameters, e.g. fuel and coolant temperatures. These are in turn used to generate appropriate nuclear cross sections by interpolation of pre-calculated data sets for each time step. Finally, to demonstrate the transient capabilities of the coupled code system, the research reactor FRM-II has been analysed. Several design basis accidents were modelled, like the loss of off site power, loss of secondary heat sink and unintended control rod withdrawal. (author)

  20. An experiment to measure the electromagnetic form factors of the neutron in the time like region at Adone

    International Nuclear Information System (INIS)

    Antonelli, A.

    1987-01-01

    A physics program is presented that will be run starting in 1987 at the Adone machine in Frascati, when it will come back to e + e - -yields antineutron neutron; other channels are under consideration for new measurements or monitoring purposes. The machine developments related to the e + e - - operation are discussed and the detection apparatus, presently under construction, is described

  1. Real time observation of the hydrothermal crystallization of barium titanate using in situ neutron powder diffraction.

    Science.gov (United States)

    Walton, R I; Millange, F; Smith, R I; Hansen, T C; O'Hare, D

    2001-12-19

    The hydrothermal crystallization of barium titanate, BaTiO3, has been studied in situ by time-resolved powder neutron diffraction methods using the recently developed Oxford/ISIS hydrothermal cell. This technique has allowed the formation of the ferroelectric ceramic to be followed in a noninvasive manner in real time and under genuine reaction conditions. In a first set of experiments, Ba(OD)2-8D2O was reacted with two different titanium sources, either crystalline TiO2 (anatase) or amorphous TiO2-H2O in D2O, at 100-140 degrees C and the reaction studied using the POLARIS time-of-flight neutron powder diffractometer, at the ISIS Facility. In a second series of experiments, the reaction between barium chloride and crystalline TiO2 (anatase) in NaOD/D2O was studied at temperatures between 100 and 200 degrees C and at different deuterioxide concentrations using the constant-wavelength D20 neutron powder diffractometer at the Institut Laue Langevin. Quantitative growth and decay curves were determined from analysis of the integrated intensities of Bragg reflections of starting materials and product phases. In both sets of experiments the rapid dissolution of the barium source was observed, followed by dissolution of the titanium source before the onset of crystallization of barium titanate. Using a nucleation-growth model we are able to simulate the growth curve of barium titanate at three temperatures. Our results indicate the predominance of a homogeneous dissolution-precipitation mechanism for the hydrothermal formation of barium titanate, rather than other possible mechanisms that have been discussed in the literature. Analysis of the line widths of the Bragg reflections in the neutron diffraction data indicates that the particle size of the BaTiO3 product phase prepared from the amorphous TiO2-H2O is smaller than that prepared from crystalline TiO2 (anatase).

  2. Real time neutron transmission investigation of the austenite-bainite transformation in grey iron

    International Nuclear Information System (INIS)

    Meggers, Kay; Priesmeyer, Hans G.; Trela, Walter J.; Bowman, Charles D.; Dahms, Michael

    1994-01-01

    The first successful application of a new method to investigate phase transformations in real time, like the decomposition of austenite into bainite in grey iron, is described. During the ongoing transformation, transmission spectra of thermal neutrons, which contain Bragg edges corresponding to the crystal structure of the transforming phases, are recorded. By evaluating the height of these Bragg edges, which is a measure of the volume fraction of the phase, at different transformation times, the transformation can be followed in-situ in a time resolved manner. The method is compared to other previously used methods (micrographs, dilatometry, diffraction techniques); also a summary and an outlook are given. ((orig.))

  3. Distillation time alters essential oil yield, composition, and antioxidant activity of male Juniperus scopulorum trees.

    Science.gov (United States)

    Zheljazkov, Valtcho D; Astatkie, Tess; Jeliazkova, Ekaterina A; Schlegel, Vicki

    2012-01-01

    The objective of this study was to evaluate the effect of 15 distillation times (DT), ranging from 1.25 to 960 min, on oil yield, essential oil profiles, and antioxidant capacity of male J. scopulorum trees. Essential oil yields were 0.07% at 1.25 min DT and reached a maximum of 1.48% at 840 min DT. The concentrations of alpha-thujene (1.76-2.75%), alpha-pinene (2.9-8.7%), sabinene (45-74.7%), myrcene (2.4-3.4%), and para-cymene (0.8-3.1%) were highest at the shortest DT (1.5 to 5 min) and decreased with increasing DT. Cis-sabinene hydrate (0.5-0.97%) and linalool plus trans-sabinene (0.56-1.6%) reached maximum levels at 40 min DT. Maximum concentrations of limonene (2.3-2.8%) and pregeijerene-B (0.06-1.4%) were obtained at 360-480 min DT, and 4-terpinenol (0.7-5.7%) at 480 min DT. Alpha-terpinene (0.16-2.9%), gamma-terpinene (0.3-4.9%) and terpinolene (0.3-1.4%) reached maximum at 720 min DT. The concentrations of delta-cadinene (0.06-1.65%), elemol (0-6.0%), and 8-alpha-acetoxyelemol (0-4.4%) reached maximum at 840 min DT. The yield of the essential oil constituents increased with increasing DT. Only linalool/transsabinene hydrate reached a maximum yield at 360 min DT. Maximum yields of the following constituents were obtained at 720 min DT: alpha-thujene, alpha-pinene, camphene, sabinene, myrcene, alpha-terpinene, para-cimene, limonene, gamma-terpinene, terpinolene, and 4-terpinenol. At 840 min DT, cis-sabinene hydrate, prejeijerene-B, gamma muurolene, delta-cadinene, reached maximum. At 960 min DT, maximum yields of beta-pinene, elemol, alphaeudesmol/betaeudesmol, 8-alpha-acetoxyelemol were reached. These changes were adequately modeled by either the Michaelis-Menten or the Power (Convex) nonlinear regression models. Oils from the 480 min DT showed higher antioxidant activity compared to samples collected at 40, 160, or 960 min DT. These results show the potential for obtaining essential oils with various compositions and antioxidant capacity from male J

  4. Neutron diagnostics at the Wendelstein 7-X stellarator

    Science.gov (United States)

    Schneider, W.; Wiegel, B.; Grünauer, F.; Burhenn, R.; Koch, S.; Schuhmacher, H.; Zimbal, A.

    2012-03-01

    The stellarator W7-X, presently under construction at the Institute for Plasma Physics in Greifswald, will be equipped with a set of neutron monitors in order to study the time behaviour of neutron emission generated during D-D plasma operation and neutral beam heating with Deuterium. Each of these neutron monitors consists of several neutron detector tubes inserted in a dedicated moderator. The neutron monitors at W7-X are designed to monitor neutron yields with a time resolution of 5 ms and with a statistical uncertainty of better than 15%. One of the monitors is located in the centre above the stellarator. The other five monitors are distributed around the torus. A prerequisite for the determination of the absolute neutron source strength produced by D(d,n)3He fusion reactions in the plasma is an in-situ calibration with a neutron source of known source strength. During such a calibration procedure, the neutron source will be moved along the torus axis and the count rates of the different neutron monitors will be measured. In a first benchmark experiment, an 241AmBe neutron source was moved along the torus axis within one module of the stellarator and the neutron signals were measured by a De Pangher Long Counter outside of the cryostat chamber as a function of the neutron source position. These measurements have been compared with predictions of Monte Carlo calculations (MCNP) of the neutron propagation from the location of the neutron source to the long counter. The concept of neutron monitors will be reported together with results from the benchmark experiment and results from MCNP calculations. The neutron monitor system is the first part of several neutron diagnostic systems such as neutron activation system, neutron profile camera planned for future neutron analysis. A short survey of these neutron diagnostic tools of W7-X will be given.

  5. Impact of harvesting time on ultimate methane yield of switchgrass grown in eastern Canada

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Y.; Masse, D. [Agriculture and Agri-Food Canada, Sherbrooke, PQ (Canada). Dairy and Swine Research and Development Centre; Savoie, P.; Belanger, G.; Parent, G. [Agriculture and Agri-Food Canada, Quebec City, PQ (Canada). Soils and Crops Research and Development Centre; Babineau, D.L. [Groupe EBI, Berthierville, PQ (Canada)

    2010-07-01

    European research in green energy production from crops has resulted in the development of full scale bioreactors that use energy crops as feedstock. Switchgrass has been touted as one of the most promising crops for energy production among several perennial grass species grown under moderate to hot climates. However, few studies have been conducted in colder climate conditions. This study examined the mesophilic methane yield of switchgrass grown under the cooler growing conditions that exist in northeastern North America. In 2007, switchgrass was harvested in late July, August and September and conserved as silage. The regrowth of plots harvested in late July was also harvested in late September as a two-cut strategy. A 30 L small-scale laboratory digester was used to anaerobically digest the switchgrass silage samples. Specific methane yield decreased considerably with advancing plant development, but was similar between the first harvest in late July and the regrowth in late September. Nearly 25 per cent more methane could be produced by hectare for the two-cut strategy compared to harvesting once in late August. It was concluded that additional studies are needed to determine the effect of cutting times and strategies on the long term yield of switchgrass and to establish the production cost of this renewable energy.

  6. Influence of Sowing Times, Densities, and Soils to Biomass and Ethanol Yield of Sweet Sorghum

    Directory of Open Access Journals (Sweden)

    Tran Dang Xuan

    2015-08-01

    Full Text Available The use of biofuels helps to reduce the dependency on fossil fuels and therefore decreases CO2 emission. Ethanol mixed with gasoline in mandatory percentages has been used in many countries. However, production of ethanol mainly depends on food crops, commonly associated with problems such as governmental policies and social controversies. Sweet sorghum (Sorghum bicolor (L. Moench is one of the most potential and appropriate alternative crops for biofuel production because of its high biomass and sugar content, strong tolerance to environmental stress conditions and diseases, and wide adaptability to various soils and climates. The aim of this study was to select prospective varieties of sweet sorghum, optimum sowing times and densities to achieve high yields of ethanol production and to establish stable operational conditions in cultivating this crop. The summer-autumn cropping season combined with the sowing densities of 8.3–10.9 plant m−2 obtained the highest ethanol yield. Among cultivated locations, the soil with pH of 5.5 and contents of Al and Zn of 39.4 and 0.6 g kg−1, respectively, was the best condition to have an ethanol yield >5000 L ha−1. The pH ≥ 6.0 may be responsible for the significant reduction of zinc content in soils, which decreases both biomass of sweet sorghum and ethanol yield, while contents of N, P, K, organic carbon (OC and cation exchange capacity (CEC, and Fe likely play no role. The cultivar 4A was the preferred candidate for ethanol production and resistant to pests and diseases, especially cut worm (Agrotis spp..

  7. Time changes of vertical profile of neutron fluence rate in LVR-15 reactor

    International Nuclear Information System (INIS)

    Viererbl, L.; Stehno, J.; Erben, O.; Lahodova, Z.; Marek, M.

    2003-01-01

    The LVR-15 reactor is a light water research type reactor, which is situated, in Nuclear Research Institute, Rez near Prague. The reactor is used as a multipurpose facility. For some experiments and material productions, e.g. for homogeneity of silicon resistance in production of radiation doped silicon, the time changes of vertical profile of neutron fluence rate are particularly important. The assembly used for silicon irradiation has two self-powered neutron detectors installed in a vertical irradiation channel in LVR-15 reactor. Vertical profile of thermal neutron fluence rate was automatically scanned during reactor operation. The results of measurements made in 2002 and 2003 with these detectors are presented. A set of vertical profile measurements was made during two 21-days reactor cycles. During the cycle the vertical profile slightly changes both in the position of its maximum and in the shape. The time dependences of the position of profile maximum and the profile width at half maximum during the cycle are given. (author)

  8. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

    DEFF Research Database (Denmark)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A.

    2017-01-01

    constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND......-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure....... The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD)....

  9. Some aspects of time domain reflectometry, neutron scattering, and capacitance methods for soil water content measurement

    International Nuclear Information System (INIS)

    Evett, S.R.

    2000-01-01

    Soil-water measurements encounter particular problems related to the physics of the method used. For time domain reflectometry (TDR), these relate to wave form shape changes caused by soil, soil water, and TDR probe properties. Methods of wave form interpretation that overcome these problems are discussed and specific computer algorithms are presented. Neutron scattering is well understood, but calibration methods remain critical to accuracy and precision, and are discussed with recommendations for field calibration and use. Capacitance probes tend to exhibit very small radii of influence, thus are sensitive to small-scale changes in soil properties, and are difficult or impossible to field calibrate. Field comparisons of neutron and capacitance probes are presented. (author)

  10. Time reversal invariance and the deformation effect for neutron resonances in aligned 165Ho

    International Nuclear Information System (INIS)

    Gould, C.R.; Haase, D.G.; Huffman, P.R.; Roberson, N.R.; Frankle, C.M.

    1993-01-01

    Neutron transmission tests of time reversal invariance on resonance have attracted considerable attention because of the large enhancement of symmetry violating observables. The P-even T-odd five fold correlation (FC) term s · (I x k)I · k is measured with an aligned target. We discuss how to identify suitable resonances in an aligned target by means of the deformation effect. We focus on neutron transmission through aligned 165 Ho, and consider the possibility of locating small d-wave admixtures in weak, predominantly s-wave resonances. We estimate the sensitivity of the FC test to α T , the ratio of the T-odd to T-even parts of the effective nucleon-nucleon interaction

  11. Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

    Energy Technology Data Exchange (ETDEWEB)

    Baudron, Anne-Marie, E-mail: anne-marie.baudron@cea.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex (France); Lautard, Jean-Jacques, E-mail: jean-jacques.lautard@cea.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex (France); Maday, Yvon, E-mail: maday@ann.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions and Institut Universitaire de France, F-75005, Paris (France); Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); Brown Univ, Division of Applied Maths, Providence, RI (United States); Riahi, Mohamed Kamel, E-mail: riahi@cmap.polytechnique.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CMAP, Inria-Saclay and X-Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Salomon, Julien, E-mail: salomon@ceremade.dauphine.fr [CEREMADE, Univ Paris-Dauphine, Pl. du Mal. de Lattre de Tassigny, F-75016, Paris (France)

    2014-12-15

    In this paper we present a time-parallel algorithm for the 3D neutrons calculation of a transient model in a nuclear reactor core. The neutrons calculation consists in numerically solving the time dependent diffusion approximation equation, which is a simplified transport equation. The numerical resolution is done with finite elements method based on a tetrahedral meshing of the computational domain, representing the reactor core, and time discretization is achieved using a θ-scheme. The transient model presents moving control rods during the time of the reaction. Therefore, cross-sections (piecewise constants) are taken into account by interpolations with respect to the velocity of the control rods. The parallelism across the time is achieved by an adequate use of the parareal in time algorithm to the handled problem. This parallel method is a predictor corrector scheme that iteratively combines the use of two kinds of numerical propagators, one coarse and one fine. Our method is made efficient by means of a coarse solver defined with large time step and fixed position control rods model, while the fine propagator is assumed to be a high order numerical approximation of the full model. The parallel implementation of our method provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch–Maurer–Werner benchmark.

  12. Yield, content, and composition of peppermint and spearmints as a function of harvesting time and drying.

    Science.gov (United States)

    Zheljazkov, Valtcho D; Cantrell, Charles L; Astatkie, Tess; Hristov, Alex

    2010-11-10

    Peppermint ( Mentha × piperita L.) and spearmints ('Scotch' spearmint, M. × gracilis Sole, and 'Native' spearmint, Mentha spicata L.) are widely grown essential oil crops in more northern latitudes; however, there is limited information on how harvest time and drying influence peppermint and spearmint yield, oil composition, and bioactivity, when grown south of the 41st parallel. In this 2-year study, the effects of harvest time and drying on the yield, oil composition, and bioactivity of peppermint ('Black Mitcham' and 'B90-9'), 'Scotch' spearmint, and 'Native' spearmint were evaluated. Peppermint oil from the dried material had higher menthol and eucalyptol concentrations. Menthone in both peppermint cultivars decreased from harvest 1 (late June) to harvest 5 (late August) or 6 (early September), whereas menthol increased. (-)-Carvone in spearmints accumulated early, before flowering, allowing for early harvest. Oil yields from the dried spearmint biomass reached the maximum at harvest 3 (mid-July). The essential oil compositions of the four mint genotypes were similar to that of 11 commercially available oils, suggesting that these genotypes can be grown in the hot, humid environment of the southeastern United States. The antioxidant activities (ORAC(oil) values) of the essential oils were 4372, 1713, 1107, and 471 μmol of TE L(-1) for 'Scotch' spearmint, 'Native' spearmint, peppermint, and Japanese cornmint ( Mentha canadensis ), respectively. The oils of the four mint genotypes did not affect ruminal fermentation in vivo, and did not exhibit antimicrobial, antileishmanial, or antimalarial activity at levels that would warrant bioassay-directed fractionation in a drug-discovery screening program. Specifically, the oils did not show greater than 50% growth inhibition against Leishmania donovani , Plasmodium falciparum clones D6 and W2, Candida albicans , Escherichia coli , Pseudomonas aeruginosa , Cryptococcus neoformans , Mycobacterium intracellulare , or

  13. Varying plant density and harvest time to optimize cowpea leaf yield and nutrient content

    Science.gov (United States)

    Ohler, T. A.; Nielsen, S. S.; Mitchell, C. A.

    1996-01-01

    Plant density and harvest time were manipulated to optimize vegetative (foliar) productivity of cowpea [Vigna unguiculata (L.) Walp.] canopies for future dietary use in controlled ecological life-support systems as vegetables or salad greens. Productivity was measured as total shoot and edible dry weights (DW), edible yield rate [(EYR) grams DW per square meter per day], shoot harvest index [(SHI) grams DW per edible gram DW total shoot], and yield-efficiency rate [(YER) grams DW edible per square meter per day per grams DW nonedible]. Cowpeas were grown in a greenhouse for leaf-only harvest at 14, 28, 42, 56, 84, or 99 plants/m2 and were harvested 20, 30, 40, or 50 days after planting (DAP). Shoot and edible dry weights increased as plant density and time to harvest increased. A maximum of 1189 g shoot DW/m2 and 594 g edible DW/m2 were achieved at an estimated plant density of 85 plants/m2 and harvest 50 DAP. EYR also increased as plant density and time to harvest increased. An EYR of 11 g m-2 day-1 was predicted to occur at 86 plants/m2 and harvest 50 DAP. SHI and YER were not affected by plant density. However, the highest values of SHI (64%) and YER (1.3 g m-2 day-1 g-1) were attained when cowpeas were harvested 20 DAP. The average fat and ash contents [dry-weight basis (dwb)] of harvested leaves remained constant regardless of harvest time. Average protein content increased from 25% DW at 30 DAP to 45% DW at 50 DAP. Carbohydrate content declined from 50% DW at 30 DAP to 45% DW at 50 DAP. Total dietary fiber content (dwb) of the leaves increased from 19% to 26% as time to harvest increased from 20 to 50 days.

  14. A comparison of time-of-flight and Larmor modulation neutron powder diffraction at a continuous reactor source

    CERN Document Server

    Mulder, F M

    1999-01-01

    A neutron powder diffraction instrument for application at a continuous reactor source based on time-of-flight (TOF) is compared with an instrument based on Larmor modulation (LM). For instruments with a similar wave-vector resolution (delta q/q=4x10 sup - sup 3) it is found that the signal-to-noise ratios in a TOF experiment are generally better when using a wide wavelength neutron spectrum. This is caused by the fact that the noise in a LM experiment comes from the integrated neutron flux scattered in the detector, while in TOF the noise stems only from the intensity scattered into individual time channels.

  15. Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

    Science.gov (United States)

    Moon, S.; Simnett, G. M.; White, R. S.

    1976-01-01

    A large-area solid-angle double-scatter neutron telescope was flown to search for solar neutrons on three balloon flights in 1971 and 1972. The first two flights were launched from Palestine, Texas, and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet-time solar neutron fluxes at the 95-per cent confidence level are 2.8, 4.6, 9.6, and 9.0 x 10 to the -4th power neutron/sq cm/sec in the energy intervals of 10-30, 30-50, 50-100, and 10-100 MeV, respectively.

  16. Time-of-Flight Neutron Imaging on IMAT@ISIS: A New User Facility for Materials Science

    Directory of Open Access Journals (Sweden)

    Winfried Kockelmann

    2018-02-01

    Full Text Available The cold neutron imaging and diffraction instrument IMAT at the second target station of the pulsed neutron source ISIS is currently being commissioned and prepared for user operation. IMAT will enable white-beam neutron radiography and tomography. One of the benefits of operating on a pulsed source is to determine the neutron energy via a time of flight measurement, thus enabling energy-selective and energy-dispersive neutron imaging, for maximizing image contrasts between given materials and for mapping structure and microstructure properties. We survey the hardware and software components for data collection and image analysis on IMAT, and provide a step-by-step procedure for operating the instrument for energy-dispersive imaging using a two-phase metal test object as an example.

  17. The Effect of Nitroxin Biofertilizer and Foliar Applicatin of Micronutrients Time Consumption on Yield and Yield Components of New Wheat Cultivars under Khorramabad Climatic Conditions

    Directory of Open Access Journals (Sweden)

    A. Vaez

    2016-02-01

    Full Text Available Introduction In order to study the effects of Nitroxin biofertilizer and foliar application of micronutrients time consumption on yield and yield components of new wheat cultivars (Triticum aestivum & T. durum under Khorramabad climatic conditions, an experiment was conducted as factorial based on a randomized complete block design with three replications at the research farm khorramabad during growing season of 2012-2013. Considering the positive effect of inoculation with bio-fertilizer and foliar Nitroxin micronutrients and reaction of cultivars to this type of fertilizer instead of chemical fertilizers and the importance of wheat as one of the main crops, this study aims to determine the most appropriate time for foliar and Nitroxin application of micronutrients at the different stages of plant growth and bio-fertilizer application on yield and yield components. Materials and Methods The first factor was considered in six levels: N0: The lack of the seed insemination with nitroxin biofertilizer and without the foliar application of micronutrients (control, N1: the seed inoculation with the nitroxin biofertilizer, N2: the foliar application of micronutrients at the jointing stage, N3: the foliar application of micronutrients at the heading stage, N4: the seed insemination with nitroxin biofertilizer and foliar application of micronutrients at the jointing stage, N5: the seed insemination with nitroxin biofertilizer and foliar application of micronutrients at the heading stage. The second factor was considered at two levels, consisting: V1: Parsi cultivar and V2: Dena cultivar. MSTATC Software was used for data analysis and means were compared by Duncan's multiple range test at the 5% level. Results and Discussion In this experiment the grain yield, biological yield, harvest index, 1000- grain weight, spike number per m-2, grain number per spike and spikelet number per spike of wheat were studied. The results of the data variance analysis has

  18. Ratio of basin lag times for runoff and sediment yield processes recorded in various environments

    Directory of Open Access Journals (Sweden)

    K. Banasik

    2015-03-01

    Full Text Available River basin lag time (LAG, defined as the elapsed time between the occurrence of the centroids of the effective rainfall intensity hyetograph and the storm runoff hydrograph, is an important factor in determining the time to peak and the peak value of the instantaneous unit hydrograph (IUH. In the procedure of predicting a sedimentgraph (suspended sediment load as a function of time, the equivalent parameter is the lag time for the sediment yield (LAGs, which is defined as the elapsed time between the occurrence of the centroids of sediment production during a storm event and the observed sedimentgraph at the gauging station. Data of over 150 events recorded in 11 small river catchments (located in Poland, Germany, UK and USA with a drainage area of 0.02 km2 to 82 km2 have been analysed to estimate the ratio of LAGs/LAG. The ratio, in majority of cases was smaller than 1, and decreased with increase of river basin slope. Special attention is given to the data collected in a small agricultural catchment and also during snowmelt periods, which is located in central Poland.

  19. Implosion anisotropy of neutron kinetic energy distributions as measured with the neutron time-of-flight diagnostics at the National Ignition Facility

    Science.gov (United States)

    Hartouni, Edward; Eckart, Mark; Field, John; Grim, Gary; Hatarik, Robert; Moore, Alastair; Munro, David; Sayer, Daniel; Schlossberg, David

    2017-10-01

    Neutron kinetic energy distributions from fusion reactions are characterized predominantly by the excess energy, Q, of the fusion reaction and the variance of kinetic energy which is related to the thermal temperature of the plasma as shown by e.g. Brysk. High statistics, high quality neutron time-of-flight spectra obtained at the National Ignition Facility provide a means of measuring small changes to the neutron kinetic energy due to the spatial and temporal distribution of plasma temperature, density and velocity. The modifications to the neutron kinetic energy distribution as described by Munro include plasma velocity terms with spatial orientation, suggesting that the neutron kinetic energy distributions could be anisotropic when viewed by multiple lines-of-sight. These anisotropies provide a diagnostic of burn averaged plasma velocity distributions. We present the results of measurements made for a variety of DT implosions and discuss their possible physical interpretations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.

  20. Design of a new time-of-flight small-angle neutron scattering instrument at CPHS

    International Nuclear Information System (INIS)

    Huang, T.C.; Gong, H.; Shao, B.B.; Wang, D.; Zhang, X.Z.; Zhang, K.; Wei, J.; Wang, X.W.; Guan, X.L.; Loong, C.-K.; Tao, J.Z.; Zhou, L.; Ke, Y.B.

    2012-01-01

    A new time-of-flight (TOF) small-angle neutron scattering (SANS) diffractometer is to be built at the Compact Pulsed Hadron Source (CPHS) of Tsinghua University, China. This SANS project strives to serve two purposes: its instrumental design, fabrication and optimization will help glean valuable scientific and engineering experiences; and its utilization will help promote fruitful domestic user programs on research of large structures in advanced materials using neutrons. The design draws experiences from other TOF SANS instruments, particularly that of the long-pulse LENS of Indiana University and also considers the source features at CPHS. The design team enjoyed the guidance and assistance from experts through international collaborations. For simultaneous collection of scattering data in the Q-range (∼7×10 -3 -1 ) with reasonable Q-resolution and high efficiency, this instrument is designed to use large area detector (1×1 m 2 ) and broad wavelength bandwidth (1-10 Å) within the first frame. It also pays attention to possible use of optical devices such as neutron guides, focusing lenses and novel detectors.

  1. Finite difference solution of the time dependent neutron group diffusion equations

    International Nuclear Information System (INIS)

    Hendricks, J.S.; Henry, A.F.

    1975-08-01

    In this thesis two unrelated topics of reactor physics are examined: the prompt jump approximation and alternating direction checkerboard methods. In the prompt jump approximation it is assumed that the prompt and delayed neutrons in a nuclear reactor may be described mathematically as being instantaneously in equilibrium with each other. This approximation is applied to the spatially dependent neutron diffusion theory reactor kinetics model. Alternating direction checkerboard methods are a family of finite difference alternating direction methods which may be used to solve the multigroup, multidimension, time-dependent neutron diffusion equations. The reactor mesh grid is not swept line by line or point by point as in implicit or explicit alternating direction methods; instead, the reactor mesh grid may be thought of as a checkerboard in which all the ''red squares'' and '' black squares'' are treated successively. Two members of this family of methods, the ADC and NSADC methods, are at least as good as other alternating direction methods. It has been found that the accuracy of implicit and explicit alternating direction methods can be greatly improved by the application of an exponential transformation. This transformation is incompatible with checkerboard methods. Therefore, a new formulation of the exponential transformation has been developed which is compatible with checkerboard methods and at least as good as the former transformation for other alternating direction methods

  2. Study of building materials impregnation processes by quasi-real-time neutron radiography

    Science.gov (United States)

    Nemec, T.; Rant, J.; Apih, V.; Glumac, B.

    1999-11-01

    Neutron radiography (NR) is a useful non-destructive method for determination of hydrogen content in various building and technical materials. Monitoring of transport processes of moisture and hydrogenous liquids in porous building materials is enabled by fast, quasi-real-time NR methods based on novel imaging plate neutron detectors (IP-NDs). Hydrogen content in the samples is determined by quantitative analysis of measured profiles of neutron attenuation in the samples. Detailed description of quantitative NR method is presented by the authors in another accompanying contribution at this conference. Deterioration of building materials is originated by different processes that all require presence of water therefore it is essential to limit or prevent the transport of water through the porous material. In this presentation, results of a study of clay brick impregnation by silicone based hydrophobic agents will be presented. Quantitative results obtained by NR imaging successfully explained the processes that occur during the impregnation of porous materials. Efficiency of hydrophobic treatment was quantitatively evaluated.

  3. The measurement programme at the neutron time-of-flight facility n_TOF at CERN

    Science.gov (United States)

    Gunsing, F.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Balibrea-Correa, J.; Barbagallo, M.; Barros, S.; Bečvář, F.; Beinrucker, C.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés-Giraldo, M. A.; Cortés, G.; Cosentino, L.; Damone, L. A.; Deo, K.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Frost, R. J. W.; Furman, V.; Ganesan, S.; García, A. R.; Gawlik, A.; Gheorghe, I.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González, E.; Goverdovski, A.; Griesmayer, E.; Guerrero, C.; Göbel, K.; Harada, H.; Heftrich, T.; Heinitz, S.; Hernández-Prieto, A.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Kalamara, A.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Kurtulgil, D.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lerendegui, J.; Licata, M.; Meo, S. Lo; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Negret, A.; Oprea, A.; Palomo-Pinto, F. R.; Paradela, C.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, I.; Praena, J.; Quesada, J. M.; Radeck, D.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Robles, M.; Rout, P.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Suryanarayana, S. V.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Weiss, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2017-09-01

    Neutron-induced reaction cross sections are important for a wide variety of research fields ranging from the study of nuclear level densities, nucleosynthesis to applications of nuclear technology like design, and criticality and safety assessment of existing and future nuclear reactors, radiation dosimetry, medical applications, nuclear waste transmutation, accelerator-driven systems and fuel cycle investigations. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN's neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of its scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n_TOF will be presented.

  4. The measurement programme at the neutron time-of-flight facility n_TOF at CERN

    Directory of Open Access Journals (Sweden)

    Gunsing F.

    2017-01-01

    Full Text Available Neutron-induced reaction cross sections are important for a wide variety of research fields ranging from the study of nuclear level densities, nucleosynthesis to applications of nuclear technology like design, and criticality and safety assessment of existing and future nuclear reactors, radiation dosimetry, medical applications, nuclear waste transmutation, accelerator-driven systems and fuel cycle investigations. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN’s neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of its scientific measurement programme in 2001. While for a long period a single measurement station (EAR1 located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2 in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n_TOF will be presented.

  5. Commissioning of the IDS Neutron Detector and $\\beta$-decay fast-timing studies at IDS

    CERN Document Server

    Piersa, Monika

    2016-01-01

    The following report describes my scientific activities performed during the Summer Student Programme at ISOLDE. The main part of my project was focused on commissioning the neutron detector dedicated to nuclear decay studies at ISOLDE Decay Station (IDS). I have participated in all the steps needed to make it operational for the IS609 experiment. In the testing phase, we obtained expected detector response and calibrations confirmed its successful commissioning. The detector was mounted in the desired geometry at IDS and used in measurements of the beta-delayed neutron emission of $^8$He. After completing aforementioned part of my project, I became familiar with the fast-timing method. This technique was applied at IDS in the IS610 experiment performed in June 2016 to explore the structure of neutron-rich $^{130-134}$Sn nuclei. Since the main part of my PhD studies will be the analysis of data collected in this experiment, the second part of my project was dedicated to acquiring knowledge about technical de...

  6. Some contributions towards the parallel simulation of time dependent neutron transport and the integration of observed data in real time

    International Nuclear Information System (INIS)

    Mula-Hernandez, Olga

    2014-01-01

    In this thesis, we have first developed a time dependent 3D neutron transport solver on unstructured meshes with discontinuous Galerkin finite elements spatial discretization. The solver (called MINARET) represents in itself an important contribution in reactor physics thanks to the accuracy that it can provide in the knowledge of the state of the core during severe accidents. It will also play an important role on vessel fluence calculations. From a mathematical point of view, the most important contribution has consisted in the implementation of modern algorithms that are well adapted for modern parallel architectures and that significantly decrease the computing times. A special effort has been done in order to efficiently parallelize the time variable by the use of the parareal in time algorithm. For this, we have first analyzed the performances that the classical scheme of parareal can provide when applied to the resolution of the neutron transport equation in a reactor core. Then, with the purpose of improving these performances, a parareal scheme that takes more efficiently into account the presence of other iterative schemes in the resolution of each time step has been proposed. The main idea consists in limiting the number of internal iterations for each time step and to reach convergence across the parareal iterations. A second phase of our work has been motivated by the following question: given the high degree of accuracy that MINARET can provide in the modeling of the neutron population, could we somehow use it as a tool to monitor in real time the population of neutrons on the purpose of helping in the operation of the reactor? And, what is more, how to make such a tool be coherent in some sense with the measurements taken in situ? One of the main challenges of this problem is the real time aspect of the simulations. Indeed, despite all of our efforts to speed-up the calculations, the discretization methods used in MINARET do not provide simulations

  7. A fast large-area position-sensitive time-of-flight neutron detection system

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, R.K.; Haumann, J.R.

    1989-10-13

    A new position-sensitive time-of-flight neutron detection and histograming system has been developed for use at the Intense Pulsed Neutron Source. Spatial resolution of roughly 1 cm {times} 1 cm and time-of-flight resolution of {approximately}1 {mu}sec are combined in a detection system which can ultimately be expanded to cover several square meters of active detector area. This system is based on the use of arrays of cylindrical one-dimensional position-sensitive proportional counters, and is capable of collecting the x-y-t data and sorting them into histograms at time-averaged data rates up to {approximately}300,000 events/sec over the full detector area and with instantaneous data rates up to more than fifty times that. Numerous hardware features have been incorporated to facilitate initial tuning of the position encoding, absolute calibration of the encoded positions, and automatic testing for drifts. 7 refs., 11 figs., 1 tabs.

  8. Is timing noise important in the gravitational wave detection of neutron stars?

    International Nuclear Information System (INIS)

    Jones, D.I.

    2004-01-01

    In this paper we ask whether the phenomenon of timing noise long known in electromagnetic pulsar astronomy is likely to be important in gravitational wave (GW) observations of spinning-down neutron stars. We find that timing noise is strong enough to be of importance only in the young pulsars, which must have larger triaxialities than theory predicts for their GW emission to be detectable. However, assuming that their GW emission is detectable, we list the pulsars for which timing noise is important, either because it is strong enough that its neglect by the observer would render the source undetectable or else because it is a measurable feature of the GW signal. We also find that timing noise places a limit on the observation duration of a coherent blind GW search, and suggest that hierarchical search techniques might be able to cope with this problem. Demonstration of the presence or absence of timing noise in the GW channel would give a new probe of neutron star physics

  9. Timing noise of radio pulsars and implications to neutron star's interior structure and gravitational wave detection

    Science.gov (United States)

    Zhang, Shuang-Nan; Xie, Yi

    Abstract: Radio pulsars are the most stable natural clocks in the universe, yet timing irregularities or noises can still be substantial when the times of arrivals of their pulses are fitted with some well accepted spin-down models or templates of pulsars. In this talk, I will review our recent work on modeling the timing noises of radio pulsars. Our model includes a long-term power-law decay modulated by periodic oscillations of the surface magnetic fields of neutron stars. Our model can explain the statistical properties of their timing noises. We find that the spin-down evolutions of young and old pulsars are dominated by the power-law decay and periodic oscillations, respectively. By applying our model to the individual spin-down evolutions of several well-measured radio pulsars, we find evidence for Hall drifts and Hall waves in the crusts of neutron stars. The relaxation behaviors of both classical and slow glitches can also be modeled as evolution of their surface magnetic fields, but with opposite trends. Finally we also attempt to improve the sensitivity of detecting gravitational waves with pulsars by applying our model to reduce the timing residuals of millisecond radio pulsars. Our main publications related to this talk are: 2012, ApJ, 757, 153; 2012, ApJ, 761, 102; 2013, ApJ, 778, 31; arXiv:1307.6413, 1312.3049.

  10. Time-of-flight neutron diffraction study of bovine γ-chymotrypsin at the Protein Crystallography Station.

    Science.gov (United States)

    Lazar, Louis M; Fisher, S Zoe; Moulin, Aaron G; Kovalevsky, Andrey; Novak, Walter R P; Langan, Paul; Petsko, Gregory A; Ringe, Dagmar

    2011-05-01

    The overarching goal of this research project is to determine, for a subset of proteins, exact hydrogen positions using neutron diffraction, thereby improving H-atom placement in proteins so that they may be better used in various computational methods that are critically dependent upon said placement. In order to be considered applicable for neutron diffraction studies, the protein of choice must be amenable to ultrahigh-resolution X-ray crystallography, be able to form large crystals (1 mm(3) or greater) and have a modestly sized unit cell (no dimension longer than 100 Å). As such, γ-chymotrypsin is a perfect candidate for neutron diffraction. To understand and probe the role of specific active-site residues and hydrogen-bonding patterns in γ-chymotrypsin, neutron diffraction studies were initiated at the Protein Crystallography Station (PCS) at Los Alamos Neutron Science Center (LANSCE). A large single crystal was subjected to H/D exchange prior to data collection. Time-of-flight neutron diffraction data were collected to 2.0 Å resolution at the PCS with ~85% completeness. Here, the first time-of-flight neutron data collection from γ-chymotrypsin is reported.

  11. Prompt gamma activation analysis and time of flight neutron diffraction on 'black boxes' in the 'Ancient Charm' project

    International Nuclear Information System (INIS)

    Kasztovszky, Zs.; Kis, Z.; Belgya, T.; Kirfel, A.; Biro, K.T.

    2008-01-01

    The aim of the 'Ancient Charm' project is combining neutron tomography, prompt gamma activation analysis, time of flight neutron diffraction and neutron resonance transmission to generate elemental, and phase compositions of complex museum objects in 3D. To develop a protocol for such investigations, complex test samples were constructed and then analyzed by each method. The 'black boxes' are sealed iron and aluminum walled cubes, containing 2D or 3D arrangements of materials relevant for the compositions of archaeological samples. The experimental results obtained from bulk PGAA at BNC and TOF-ND at ISIS on two selected boxes are reported. (author)

  12. Phosphorescence quantum yield determination with time-gated fluorimeter and Tb(III)-acetylacetonate as luminescence reference

    Energy Technology Data Exchange (ETDEWEB)

    Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Fakultät für Physik, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg (Germany)

    2013-03-29

    Highlights: ► Procedure for absolute phosphorescence quantum yield measurement is described. ► Experimental setup for absolute luminescence quantum yield standard calibration. ► Tb(acac){sub 3} proposed as phosphorescence quantum yield reference standard. ► Luminescence quantum yield of Tb(acac){sub 3} in cyclohexane measured. ► Luminescence lifetime of Tb(acac){sub 3} in cyclohexane measured. - Abstract: Phosphorescence quantum yield measurements of fluorescent and phosphorescent samples require the use of time-gated fluorimeters in order to discriminate against the fluorescence contribution. As reference standard a non-fluorescent luminescent compound is needed for absolute phosphorescence quantum yield determination. For this purpose the luminescence behavior of the rare earth chelate terbium(III)-acetylacetonate (Tb(acac){sub 3}) was studied (determination of luminescence quantum yield and luminescence lifetime). The luminescence quantum yield of Tb(acac){sub 3} was determined by using an external light source and operating the fluorimeter in chemo/bioluminescence mode with a fluorescent dye (rhodamine 6G in methanol) as reference standard. A procedure is developed for absolute luminescence (phosphorescence) quantum yield determination of samples under investigation with a time-gated fluorimeter using a non-fluorescent luminescent compound of known luminescence quantum yield and luminescence lifetime.

  13. Neutron time-of-flight techniques for investigation of the extinction effect

    International Nuclear Information System (INIS)

    Niimura, N.; Tomiyoshi, S.; Takahashi, J.; Harada, J.

    1975-01-01

    An application of the time-of-flight neutron diffraction technique to an investigation of the nature of the extinction effect in a single-crystal specimen is given. It is shown that the wavelength dependence of the extinction can be easily obtained by changing the scattering angle. An estimation of the extinction factor for a CuCl single crystal is given as an example and a comparison of the results with recent extinction theory [Becker and Coppens. Acta Cryst.(1974). A30, 129-147; 148-153] is made. (Auth.)

  14. Search for Time Reversal Violation in Neutron Decay: A Measurement of the Transverse Polarization of Electrons

    International Nuclear Information System (INIS)

    Bodek, K.; Kaczmarek, A.; Kistryn, St.; Kuzniak, M.; Zejma, J.; Pulut, J.; Kirch, K.; Bialek, A.; Kozela, A.; Ban, G.; Naviliat-Cuncic, O.; Gorel, P.; Beck, M.; Lindroth, A.; Severijns, N.; Stephan, E.; Czarnecki, A.

    2006-01-01

    A non-zero value of the R-correlation coefficient due to the e - polarization component, perpendicular to the plane spanned by the spin of the decaying neutron and the electron momentum, would signal a violation of time reversal symmetry and thus physics beyond the Standard Model. The value of the N-correlation coefficient, given by the transverse e - polarization component within that plane, is expected to be finite. The measurement of N serves as an important systematic check of the apparatus for the R-measurement. The first phase of data taking has been completed. Preliminary results from a limited data sample show no deviations from the Standard Model predictions

  15. Integration of neutron time-of-flight single-crystal Bragg peaks in reciprocal space

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Arthur J [ORNL; Joergensen, Mads [ORNL; Wang, Xiaoping [ORNL; Mikkelson, Ruth L [ORNL; Mikkelson, Dennis J [ORNL; Lynch, Vickie E [ORNL; Peterson, Peter F [ORNL; Green, Mark L [ORNL; Hoffmann, Christina [ORNL

    2014-01-01

    The intensity of single crystal Bragg peaks obtained by mapping neutron time-of-flight event data into reciprocal space and integrating in various ways are compared. These include spherical integration with a fixed radius, ellipsoid fitting and integrating of the peak intensity and one-dimensional peak profile fitting. In comparison to intensities obtained by integrating in real detector histogram space, the data integrated in reciprocal space results in better agreement factors and more accurate atomic parameters. Furthermore, structure refinement using integrated intensities from one-dimensional profile fitting is demonstrated to be more accurate than simple peak-minus-background integration.

  16. An archaeometallurgical study of two harquebusier breastplates using time-of-flight neutron diffraction

    Science.gov (United States)

    Leever, S.; Visser, D.; Kockelmann, W.; Dik, J.

    2006-11-01

    Neutron diffraction patterns were collected from two harquebusier breastplates: one dated round 1600-1650 AD while a second, initially bought as an object dated to the same period, showed after our analysis to be a replica from around 1850-1900 AD. Using data from the time-of-flight diffractometers GEM and ROTAX we determined the compositional variations of the plates and also investigated their manufacturing using texture analysis. The fragments and distinct positions on the breastplates shows that the iron plates are mainly ferrite with a few percent cementite. Oxidation products like wuestite and magnetite have been detected.

  17. Neutron xyz – polarization analysis at a time-of-flight instrument

    Directory of Open Access Journals (Sweden)

    Ehlers G.

    2015-01-01

    Full Text Available When implementing a dedicated polarization analysis setup at a neutron time-of-flight instrument with a large area detector, one faces enormous challenges. Nevertheless, significant progress has been made towards this goal over the last few years. This paper addresses systematic limitations of the traditional method that is used to make these measurements, and a possible strategy to overcome these limitations. This will be important, for diffraction as well as inelastic experiments, where the scattering occurs mostly out-of-plane.

  18. High temperature neutron diffraction (time-of-flight) in Si-Al-O-N compounds

    International Nuclear Information System (INIS)

    Cartz, L.; Roult, G.; Billy, M.

    1977-01-01

    The Si-Al-O-N compounds, intermediate between the Al 2 O 3 -Si 3 N 4 -AlN or SiO 2 phase, can be used as refractory compounds. The resistance to thermal shocks essentially depends on the coefficients of anisotropic thermal expansion, that explains their experimental determination for Si 2 N 2 O by time-of-flight neutron diffraction at high temperature. The nature of the anisotropies was shown to correspond to a crystal structure of Si 2 N 2 O involving Si-O-Si bounds along the x axis, and Si-N bounds in the y-z plane [fr

  19. The Impact of Changing Snowmelt Timing on Non-Irrigated Crop Yield: A Parametric and Non-Parametric Approach

    Science.gov (United States)

    Murray, E. M.; Cobourn, K.; Flores, A. N.; Pierce, J. L.

    2014-12-01

    As climate changes, the final date of spring snowmelt is projected to occur earlier in the year within the western United States. This earlier snowmelt timing may impact crop yield in snow-dominated watersheds by changing the timing of water delivery to agricultural fields. There is considerable uncertainty about how agricultural impacts of snowmelt timing may vary by region, crop-type, and practices like irrigation vs. dryland farming. Establishing the relationship between snowmelt timing and agricultural yield is important for understanding how changes in large-scale climatic indices (like snowmelt date) may be associated with changes in agricultural yield. A better understanding of the influence of changes in snowmelt on non-irrigated crop yield may additionally be extrapolated to better understand how climate change may alter biomass production in non-managed ecosystems. We utilized parametric regression techniques to isolate the magnitude of impact snowmelt timing has had on historical crop yield independently of climate and spatial variables that also impact yield. To do this, we examined the historical relationship between snowmelt timing and non-irrigated wheat and barley yield using a multiple linear regression model to predict yield in several Idaho counties as a function of snowmelt date, climate variables (precipitation and growing degree-days), and spatial differences between counties. We utilized non-parametric techniques to determine where snowmelt timing has positively versus negatively impacted yield. To do this, we developed classification and regression trees to identify spatial controls (e.g. latitude, elevation) on the relationship between snowmelt timing and yield. Most trends suggest a decrease in crop yield with earlier snowmelt, but a significant opposite relationship is observed in some regions of Idaho. An earlier snowmelt date occurring at high latitudes corresponds with higher than average wheat yield. Therefore, Northern Idaho may

  20. Dead-time measurement of neutron counters by reactor-power variational technique

    International Nuclear Information System (INIS)

    Hashimoto, Kengo; Ohsawa, Takaaki

    1994-01-01

    The measurements of dead time of BF 3 , 3 He, fission and proton-recoil neutron counters were performed on the basis of the reactor-power variational technique in the reactor, UTR-KINKI reactor. The advantage of this method consists in making it possible to change the flux of irradiation field continuously and over a wide range. The reactor UTR-KINKI is well suited for the measurements since the power of the reactor can be easily changed and the range of flux is just appropriate to evaluate the dead time. The results indicate that the nonparalysable model for the dead time characteristics is applicable to the counters employed. The measured dead time of fission counter is about 1.4 μs, while those of others range of 6-9 μs. (author)

  1. Fission-product energy release for times following thermal-neutron fission of 235U between 2 and 14000 seconds

    International Nuclear Information System (INIS)

    Dickens, J.K.; Emery, J.F.; Love, T.A.; McConnell, J.W.; Northcutt, K.J.; Peelle, R.W.; Weaver, H.

    1977-10-01

    Fission-product decay energy-releases rates were measured for thermal-neutron fission of 235 U. Samples of mass 1 to 10 μg were irradiated for 1 to 100 sec by use of the fast pneumatic-tube facility at the Oak Ridge Research Reactor. The resulting beta- and gamma-ray emissions were counted for times-after-fission between 2 and 14,000 seconds. The data were obtained for beta and gamma rays separately as spectral distributions, N(E/sub γ/) vs E/sub γ/ and N(E/sub beta/) vs E/sub β/. For the gamma-ray data the spectra were obtained by using a NaI detector, while for the beta-ray data the spectra were obtained by using an NE-110 detector with an anticoincidence mantle. The raw data were unfolded to provide spectral distributions of modest resolution. These were integrated over E/sub γ/ and E/sub β/ to provide total yield and energy integrals as a function of time after fission. Results are low compared to the present 1973 ANS Decay-heat standard. A complete description of the experimental apparatus and data-reduction techniques is presented. The final integral data are given in tabular and graphical form and are compared with published data. 41 figures, 13 tables

  2. Low-methane yield sheep have smaller rumens and shorter rumen retention time.

    Science.gov (United States)

    Goopy, John P; Donaldson, Alastair; Hegarty, Roger; Vercoe, Philip E; Haynes, Fay; Barnett, Mark; Oddy, V Hutton

    2014-02-01

    In the present study, following the measurement of methane emissions from 160 mature ewes three times, a subset of twenty ewes was selected for further emission and physiological studies. Ewes were selected on the basis of methane yield (MY; g CH4/kg DM intake) being low (Low MY: >1 sd below the mean; n 10) or high (High MY: >1 sd above the mean; n 10) when fed a blended chaff ration at a fixed feeding level (1·2-fold maintenance energy requirements). The difference between the Low- and High-MY groups observed at the time of selection was maintained (P= 0·001) when remeasured 1-7 months later during digesta kinetics studies. Low MY was associated with a shorter mean retention time of particulate (Psheep's rumens after an overnight fast revealed a trend towards the Low-MY sheep having more clearly demarcated rumen gas and liquid phases (P= 0·10). These findings indicate that the selection of ruminants for low MY may have important consequences for an animal's nutritional physiology.

  3. Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering

    KAUST Repository

    Ruocco, N.

    2016-05-27

    We present a small angle neutron scattering (SANS) investigation of a blend composed of a dendritic polymer and a linear matrix with comparable viscosity in start-up of an elongational flow at Tg + 50. The two-generation dendritic polymer is diluted to 10% by weight in a matrix of a long well-entangled linear chains. Both components consist of mainly 1,4-cis-polyisoprene but differ in isotopic composition. The resulting scattering contrast is sufficiently high to permit time-resolved measurements of the system structure factor during the start-up phase and to follow the retraction processes involving the inner sections of the branched polymer in the nonlinear deformation response. The outer branches and the linear matrix, on the contrary, are in the linear deformation regime. The linear matrix dominates the rheological signature of the blend and the influence of the branched component can barely be detected. However, the neutron scattering intensity is predominantly that of the (branched) minority component so that its dynamics is clearly evident. In the present paper, we use the neutron scattering data to validate the branch point withdrawal process, which could not be unambiguously discerned from rheological measurements in this blend. The maximal tube stretch that the inner branches experience, before the relaxed outer arm material is incorporated into the tube is determined. The in situ scattering experiments demonstrate for the first time the leveling-off of the strain as the result of branch point withdrawal and chain retraction directly on the molecular level. We conclude that branch point motion in the mixture of architecturally complex polymers occurs earlier than would be expected in a purely branched system, presumably due to the different topological environment that the linear matrix presents to the hierarchically deep-buried tube sections. © 2016 American Chemical Society.

  4. Fission-fragment total kinetic energy and mass yields for neutron-induced fission of 235U and 238U with En =200 keV - 30 MeV

    Science.gov (United States)

    Duke, D. L.; Tovesson, F.; Brys, T.; Geppert-Kleinrath, V.; Hambsch, F.-J.; Laptev, A.; Meharchand, R.; Manning, B.; Mayorov, D.; Meierbachtol, K.; Mosby, S.; Perdue, B.; Richman, D.; Shields, D.; Vidali, M.

    2017-09-01

    The average Total Kinetic Energy (TKE) release and fission-fragment yields in neutron-induced fission of 235U and 238U was measured using a Frisch-gridded ionization chamber. These observables are important nuclear data quantites that are relevant to applications and for informing the next generation of fission models. The measurements were performed a the Los Alamos Neutron Science Center and cover En = 200 keV - 30 MeV. The double-energy (2E) method was used to determine the fission-fragment yields and two methods of correcting for prompt-neutron emission were explored. The results of this study are correlated mass and TKE data.

  5. Fission-fragment total kinetic energy and mass yields for neutron-induced fission of 235U and 238U with En =200 keV – 30 MeV

    Directory of Open Access Journals (Sweden)

    Duke D.L.

    2017-01-01

    Full Text Available The average Total Kinetic Energy (TKE release and fission-fragment yields in neutron-induced fission of 235U and 238U was measured using a Frisch-gridded ionization chamber. These observables are important nuclear data quantites that are relevant to applications and for informing the next generation of fission models. The measurements were performed a the Los Alamos Neutron Science Center and cover En = 200 keV – 30 MeV. The double-energy (2E method was used to determine the fission-fragment yields and two methods of correcting for prompt-neutron emission were explored. The results of this study are correlated mass and TKE data.

  6. Fission Fragment Angular Anisotropy in Neutron-Induced Fission of $^{235}$U Measured with a Time Projection Chamber

    OpenAIRE

    Geppert-Kleinrath, V.; Tovesson, F.; Barrett, J. S.; Bowden, N. S.; Bundgaard, J.; Casperson, R. J.; Cebra, D. A.; Classen, T.; Cunningham, M.; Duke, D. L.; Gearhart, J.; Greife, U.; Guardincerri, E.; Hagmann, C.; Heffner, M.

    2017-01-01

    Fission fragment angular distributions can provide insights into the quantum mechanical state of the transition nucleus at the saddle point and are therefore an important constraint on fission theory. Available anisotropy data is sparse, especially at neutron energies above 5 MeV. For the first time, a three-dimensional tracking detector is employed to study fragment emission angles and provide a direct measurement of angular anisotropy. The Neutron Induced Fission Fragment Tracking Experimen...

  7. Effects of Sowing Time on Yield of Black Seed (Nigella sativa L. Ecotypes under Mashhad Conditions

    Directory of Open Access Journals (Sweden)

    F Javadi hedayat abad

    2015-04-01

    Full Text Available Growth and yield of medicinal plants affected by planting date as an important management factor. In order to study the effects of planting dates on yield and yield components of some black seed (Nigella sativa L. ecotypes, a field experiment was arranged in a randomized complete block design as a split-plot with three replications at the Agricultural Research Station of Ferdowsi University of Mashhad during growing season 2009-2010. Four planting dates (24 Feb., 16 Mar., 4 Apr. and 25 Apr. and four black seed ecotypes (Birjand, Gonabad, Neyshabour and Sabzevar were allocated to the main and sub plots, respectively. Results showed that there were significant differences between planting dates for number of follicles per plant, number of seeds per follicles and 1000-seed weight, seed yield, biological yield and harvest index. Maximum numbers of follicles per plant, number of seed per follicles, biological yield and seed yield were observed in first planting date, maximum 1000-seed weight was observed in fourth planting dates and maximum harvest index were recorded in the third planting date. Yield components, seed yield, biological yield and harvest index also were affected by ecotypes and interaction effects of planting dates and black cumin ecotypes. The highest and the lowest of all traits, expect 1000-seed weight were achieved in Gonabad and Neyshabour ecotypes, respectively. The maximum and minimum 1000-seed weights were obtained in Neyshabour and Gonabad ecotypes, respectively. Planting in 24 Feb., 16 Mar. and 4 Apr. have had high seed yield and there was a reduction on seed yield due to delay planting to 25 Apr. Also, Birjand ecotype in the last planting date had the highest seed yield. According to the seed yield, Gonabad and birjand ecotypes were better than from two other ecotypes in range of planting dates.

  8. Measurement of isomeric yield ratios of 86m,gY and 87m,gY in the quasi-monoenergetic neutron induced reactions of 89Y

    Science.gov (United States)

    Nadeem, Muhammad; Zaman, Muhammad; Naik, Haladhara; Kim, Kwangsoo; Kim, Guinyun

    2018-02-01

    The isomeric yield ratios (IR) of 86m,gY and 87m,gY were measured in the 23 to 37 MeV quasi-monoenergetic neutron induced reaction of 89Y by using an off-line γ-ray spectrometric technique. The IR values in the 89Y(n , xn) reactions were also calculated using the TALYS 1.8 code and found to be in good agreement for 87m,gY but slightly less for 86m,gY. The IR values of 86m,gY and 87m,gY from the present work in the 89Y(n , xn) reactions were compared with the literature data in the 89Y(γ , xn), 89Y(p , x) and 89Y(α , x) reactions. It was found that the IR values of 86m,gY and 87m,gY in all these reactions increase with excitation energy. At the same excitation energy, the IR values are higher in the alpha induced reaction than in the proton, neutron and photon induced reactions due to higher input angular momentum in the former than in the later. These two observations indicate the role of entrance parameters. However, it is surprising to see that at the same excitation energy, the IR values of 86m,gY and 87m,gY in the 89Y(n , xn) reaction are nearly constant and significantly higher than in the 89Y(γ , xn) reaction.

  9. Precision Neutron Time-of-Flight Detectors Provide Insight into NIF Implosion Dynamics

    Science.gov (United States)

    Schlossberg, David; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Moore, A. S.; Waltz, C. S.

    2017-10-01

    During inertial confinement fusion, higher-order moments of neutron time-of-flight (nToF) spectra can provide essential information for optimizing implosions. The nToF diagnostic suite at the National Ignition Facility (NIF) was recently upgraded to include novel, quartz Cherenkov detectors. These detectors exploit the rapid Cherenkov radiation process, in contrast with conventional scintillator decay times, to provide high temporal-precision measurements that support higher-order moment analyses. Preliminary measurements have been made on the NIF during several implosions and initial results are presented here. Measured line-of-sight asymmetries, for example in ion temperatures, will be discussed. Finally, advanced detector optimization is shown to advance accessible physics, with possibilities for energy discrimination, gamma source identification, and further reduction in quartz response times. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  10. Quantum recurrence in neutron resonances and a time unit in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ohkubo, Makio [SOHONRR, Mito, Ibaraki (Japan)

    2001-03-01

    Non-statistical properties of the neutron resonance level dispositions are investigated considering time behaviors of the compound nucleus. A resonance which is a quasi-stable state can be decomposed into a set of normal modes. From the requirement of the time periodic recurrence of the resonance state, frequencies of these normal mode must be commensurable (integer ratios) with each other. Therefore the excitation energy of a resonance is described as a sum of inverse integers. We tentatively adopt an expression E{sub x}=C{sigma}1/n, where n=integer and C=34.5 MeV. Time unit in recurrence is 1.20x10{sup -22}s. Possible sets of inverse integers are deduced for the resonances of light e-e nuclei. (author)

  11. Time to reach a given level of number of neutrons is stochastic analog of reactor period

    International Nuclear Information System (INIS)

    Ryazanov, V.V.

    2012-01-01

    In theory and in practice the operation of nuclear reactors to control the safety of the reactor is widely used deterministic value - the period of the reactor. It is proposed along with the period of the reactor using a stochastic analogue of this magnitude - a random amount of time to achieve a given level of a random process for the number of neutrons in the reactor. The paper discusses various features of the behavior of the mean and variance of time to achieve a specified level. This kind of features can be associated with impaired behavior of the reactor system. Introduced the value of time required to reach the level can be used to monitor and improve the safety of nuclear power plants

  12. Development of Real-Time Measurement of Effective Dose for High Dose Rate Neutron Fields

    International Nuclear Information System (INIS)

    Braby, L. A.; Reece, W. D.; Hsu, W. H.

    2003-01-01

    Studies of the effects of low doses of ionizing radiation require sources of radiation which are well characterized in terms of the dose and the quality of the radiation. One of the best measures of the quality of neutron irradiation is the dose mean lineal energy. At very low dose rates this can be determined by measuring individual energy deposition events, and calculating the dose mean of the event size. However, at the dose rates that are normally required for biology experiments, the individual events can not be separated by radiation detectors. However, the total energy deposited in a specified time interval can be measured. This total energy has a random variation which depends on the size of the individual events, so the dose mean lineal energy can be calculated from the variance of repeated measurements of the energy deposited in a fixed time. We have developed a specialized charge integration circuit for the measurement of the charge produced in a small ion chamber in typical neutron irradiation experiments. We have also developed 4.3 mm diameter ion chambers with both tissue equivalent and carbon walls for the purpose of measuring dose mean lineal energy due to all radiations and due to all radiations except neutrons, respectively. By adjusting the gas pressure in the ion chamber, it can be made to simulate tissue volumes from a few nanometers to a few millimeters in diameter. The charge is integrated for 0.1 seconds, and the resulting pulse height is recorded by a multi channel analyzer. The system has been used in a variety of photon and neutron radiation fields, and measured values of dose and dose mean lineal energy are consistent with values extrapolated from measurements made by other techniques at much lower dose rates. It is expected that this technique will prove to be much more reliable than extrapolations from measurements made at low dose rates because these low dose rate exposures generally do not accurately reproduce the attenuation and

  13. Enhanced Processing of 1-km Spatial Resolution fAPAR Time Series for Sugarcane Yield Forecasting and Monitoring

    Directory of Open Access Journals (Sweden)

    Bettina Baruth

    2013-03-01

    Full Text Available A processing of remotely-sensed Fraction of Absorbed Photosynthetically Active Radiation (fAPAR time series at 1-km spatial resolution is established to estimate sugarcane yield over the state of São Paulo, Brazil. It includes selecting adequate time series according to the signal spatial purity, using thermal time instead of calendar time and smoothing temporally the irregularly sampled observations. A systematic construction of various metrics and their capacity to predict yield is explored to identify the best performance, and see how timely the yield forecast can be made. The resulting dataset not only reveals a strong spatio-temporal structure, but is also capable of detecting both absolute changes in biomass accumulation and changes in its inter-annual variability. Sugarcane yield can thus be estimated with a RMSE of 1.5 t/ha (or 2% without taking into account the strong linear trend in yield increase witnessed in the past decade. Including the trend reduces the error to 0.6 t/ha, correctly predicting whether the yield in a given year is above or below the trend in 90% of cases. The methodological framework presented here could be applied beyond the specific case of sugarcane in São Paulo, namely to other crops in other agro-ecological landscapes, to enhance current systems for monitoring agriculture or forecasting yield using remote sensing.

  14. Optimizing Laser-accelerated Ion Beams for a Collimated Neutron Source

    International Nuclear Information System (INIS)

    Ellison, C.L.; Fuchs, J.

    2010-01-01

    High-flux neutrons for imaging and materials analysis applications have typically been provided by accelerator- and reactor-based neutron sources. A novel approach is to use ultraintense (>1018W/cm2) lasers to generate picosecond, collimated neutrons from a dual target configuration. In this article, the production capabilities of present and upcoming laser facilities are estimated while independently maximizing neutron yields and minimizing beam divergence. A Monte-Carlo code calculates angular and energy distributions of neutrons generated by D-D fusion events occurring within a deuterated target for a given incident beam of D+ ions. Tailoring of the incident distribution via laser parameters and microlens focusing modifies the emerging neutrons. Projected neutron yields and distributions are compared to conventional sources, yielding comparable on-target fluxes per discharge, shorter time resolution, larger neutron energies and greater collimation.

  15. Beyond-one-loop quantum gravity action yielding both inflation and late-time acceleration

    Directory of Open Access Journals (Sweden)

    E. Elizalde

    2017-08-01

    Full Text Available A unified description of early-time inflation with the current cosmic acceleration is achieved by means of a new theory that uses a quadratic model of gravity, with the inclusion of an exponential F(R-gravity contribution for dark energy. High-curvature corrections of the theory come from higher-derivative quantum gravity and yield an effective action that goes beyond the one-loop approximation. It is shown that, in this theory, viable inflation emerges in a natural way, leading to a spectral index and tensor-to-scalar ratio that are in perfect agreement with the most reliable Planck results. At low energy, late-time accelerated expansion takes place. As exponential gravity, for dark energy, must be stabilized during the matter and radiation eras, we introduce a curing term in order to avoid nonphysical singularities in the effective equation of state parameter. The results of our analysis are confirmed by accurate numerical simulations, which show that our model does fit the most recent cosmological data for dark energy very precisely.

  16. Beyond-one-loop quantum gravity action yielding both inflation and late-time acceleration

    Science.gov (United States)

    Elizalde, E.; Odintsov, S. D.; Sebastiani, L.; Myrzakulov, R.

    2017-08-01

    A unified description of early-time inflation with the current cosmic acceleration is achieved by means of a new theory that uses a quadratic model of gravity, with the inclusion of an exponential F (R)-gravity contribution for dark energy. High-curvature corrections of the theory come from higher-derivative quantum gravity and yield an effective action that goes beyond the one-loop approximation. It is shown that, in this theory, viable inflation emerges in a natural way, leading to a spectral index and tensor-to-scalar ratio that are in perfect agreement with the most reliable Planck results. At low energy, late-time accelerated expansion takes place. As exponential gravity, for dark energy, must be stabilized during the matter and radiation eras, we introduce a curing term in order to avoid nonphysical singularities in the effective equation of state parameter. The results of our analysis are confirmed by accurate numerical simulations, which show that our model does fit the most recent cosmological data for dark energy very precisely.

  17. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures.

    Science.gov (United States)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A; Steuwer, Axel; Kiyanagi, Ryoji; Tremsin, Anton S; Knudsen, Erik B; Shinohara, Takenao; Willendrup, Peter K; da Silva Fanta, Alice Bastos; Iyengar, Srinivasan; Larsen, Peter M; Hanashima, Takayasu; Moyoshi, Taketo; Kadletz, Peter M; Krooß, Philipp; Niendorf, Thomas; Sales, Morten; Schmahl, Wolfgang W; Schmidt, Søren

    2017-08-25

    The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure. The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD).

  18. Time-of-Flight Polarized Neutron Reflectometry on PLATYPUS: Status and Future Developments

    Science.gov (United States)

    Saerbeck, T.; Cortie, D. L.; Brück, S.; Bertinshaw, J.; Holt, S. A.; Nelson, A.; James, M.; Lee, W. T.; Klose, F.

    Time-of-flight (ToF) polarized neutron reflectometry enables the detailed investigation of depth-resolved magnetic structures in thin film and multilayer magnetic systems. The general advantage of the time-of-flight mode of operation over monochromatic instruments is a decoupling of spectral shape and polarization of the neutron beam with variable resolution. Thus, a wide Q-range can be investigated using a single angle of incidence, with resolution and flux well-adjusted to the experimental requirement. Our paper reviews the current status of the polarization equipment of the ToF reflectometer PLATYPUS and presents first results obtained on stratified Ni80Fe20/α-Fe2O3 films, revealing the distribution of magnetic moments in an exchange bias system. An outlook on the future development of the PLATYPUS polarization system towards the implementation of a polarized 3He cell is presented and discussed with respect to the efficiency and high Q-coverage up to 1 Å-1 and 0.15 Å-1 in the vertical and lateral momentum transfer, respectively.

  19. Finite moments approach to the time-dependent neutron transport equation

    International Nuclear Information System (INIS)

    Kim, Sang Hyun

    1994-02-01

    Currently, nodal techniques are widely used in solving the multidimensional diffusion equation because of savings in computing time and storage. Thanks to the development of computer technology, one can now solve the transport equation instead of the diffusion equation to obtain more accurate solution. The finite moments method, one of the nodal methods, attempts to represent the fluxes in the cell and on cell surfaces more rigorously by retaining additional spatial moments. Generally, there are two finite moments schemes to solve the time-dependent transport equation. In one, the time variable is treated implicitly with finite moments method in space variable (implicit finite moments method), the other method uses finite moments method in both space and time (space-time finite moments method). In this study, these two schemes are applied to two types of time-dependent neutron transport problems. One is a fixed source problem, the other a heterogeneous fast reactor problem with delayed neutrons. From the results, it is observed that the two finite moments methods give almost the same solutions in both benchmark problems. However, the space-time finite moments method requires a little longer computing time than that of the implicit finite moments method. In order to reduce the longer computing time in the space-time finite moments method, a new iteration strategy is exploited, where a few time-stepwise calculation, in which original time steps are grouped into several coarse time divisions, is performed sequentially instead of performing iterations over the entire time steps. This strategy results in significant reduction of the computing time and we observe that 2-or 3-stepwise calculation is preferable. In addition, we propose a new finite moments method which is called mixed finite moments method in this thesis. Asymptotic analysis for the finite moments method shows that accuracy of the solution in a heterogeneous problem mainly depends on the accuracy of the

  20. SENJU: a new time-of-flight single-crystal neutron diffractometer at J-PARC.

    Science.gov (United States)

    Ohhara, Takashi; Kiyanagi, Ryoji; Oikawa, Kenichi; Kaneko, Koji; Kawasaki, Takuro; Tamura, Itaru; Nakao, Akiko; Hanashima, Takayasu; Munakata, Koji; Moyoshi, Taketo; Kuroda, Tetsuya; Kimura, Hiroyuki; Sakakura, Terutoshi; Lee, Chang-Hee; Takahashi, Miwako; Ohshima, Ken-Ichi; Kiyotani, Tamiko; Noda, Yukio; Arai, Masatoshi

    2016-02-01

    SENJU is a new single-crystal time-of-flight neutron diffractometer installed at BL18 at the Materials and Life Science Experimental Facility of the Japan Accelerator Research Complex (J-PARC). The diffractometer was designed for precise crystal and magnetic structure analyses under multiple extreme sample environments such as low temperature, high pressure and high magnetic field, and for diffraction measurements of small single crystals down to 0.1 mm 3 in volume. SENJU comprises three choppers, an elliptical shape straight supermirror guide, a vacuum sample chamber and 37 scintillator area detectors. The moderator-to-sample distance is 34.8 m, and the sample-to-detector distance is 800 mm. The wavelength of incident neutrons is 0.4-4.4 Å (first frame). Because short-wavelength neutrons are available and the large solid angle around the sample position is covered by the area detectors, a large reciprocal space can be simultaneously measured. Furthermore, the vacuum sample chamber and collimator have been designed to produce a very low background level. Thus, the measurement of a small single crystal is possible. As sample environment devices, a newly developed cryostat with a two-axis (ω and φ axes) goniometer and some extreme environment devices, e.g. a vertical-field magnet, high-temperature furnace and high-pressure cell, are available. The structure analysis of a sub-millimetre size (0.1 mm 3 ) single organic crystal, taurine, and a magnetic structure analysis of the antiferromagnetic phase of MnF 2 have been performed. These results demonstrate that SENJU can be a powerful tool to promote materials science research.

  1. The multipurpose time-of-flight neutron reflectometer 'Platypus' at Australia's OPAL reactor

    Energy Technology Data Exchange (ETDEWEB)

    James, M., E-mail: mja@ansto.gov.a [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); School of Chemistry, University of New South Wales, Kensington, NSW 2052 (Australia); Nelson, A.; Holt, S.A.; Saerbeck, T.; Hamilton, W.A.; Klose, F. [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2011-03-11

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ({lambda}=2-20 A) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of <10{sup -7} are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  2. High resolution spectroscopy at FRM II: neutron resonance spin echo, back scattering and time-of-flight instrumentation

    International Nuclear Information System (INIS)

    Petry, W.

    2001-01-01

    The new German neutron source FRM II is equipped with a D 2 cold source placed in the maximum of the thermal flux in the D 2 O moderator. This cold source feeds six large neutron guides. Among others a neutron resonance spin echo (NRSE), a back scattering (BS) and a time-of-flight (TOF) spectrometer will be placed at end positions of theses guides. By detailed Monte-Carlo simulations each of the instruments is optimized for highest intensity without scarifying energy resolution. A polarized neutron guide in combination with a non magnetic wave-length selector provides high flux at the sample position of the NRSE instrument with typical spin-echo times of 30 ns at all accessible scattering angles. The BS instrument uses phase-space transformation to compress a large spread of incoming wave length to an intense monoenergetic but angular disperse beam at the sample. An intensity gain by a factor of four has been calculated without losses in energy resolution of <1 μeV (fwhm) when compared to conventional BS. The TOF spectrometer suppresses background from fast neutrons by a S-curved super-mirror guide and focusses a large incoming neutron beam onto a small sample volume, thereby increasing the flux at the sample position by a factor 3.2. Energy resolution of typical 30 μeV (fwhm) at a wave length of λ=5 A is achieved by extremely fast turning chopper discs made of carbon fiber. (author)

  3. Measurement of the Time Dependence of Neutron Slowing-Down and Therma in Heavy Water

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, E.

    1966-03-15

    The behaviour of neutrons during their slowing-down and thermalization in heavy water has been followed on the time scale by measurements of the time-dependent rate of reaction between the flux and the three spectrum indicators indium, cadmium and gadolinium. The space dependence of the reaction rate curves has also been studied. The time-dependent density at 1.46 eV is well reproduced by a function, given by von Dardel, and a time for the maximum density of 7.1 {+-} 0.3 {mu}s has been obtained for this energy in deuterium gas in agreement with the theoretical value of 7.2 {mu}s. The spatial variation of this time is in accord with the calculations by Claesson. The slowing- down time to 0.2 eV has been found to be 16.3 {+-}2.4 {mu}s. The approach to the equilibrium spectrum takes place with a time constant of 33 {+-}4 {mu}s, and the equilibrium has been established after about 200 {mu}s. Comparison of the measured curves for cadmium and gadolinium with multigroup calculations of the time-dependent flux and reaction rate show the superiority of the scattering models for heavy water of Butler and of Brown and St. John over the mass 2 gas model. The experiment has been supplemented with Monte Carlo calculations of the slowing down time.

  4. Measurement of the Time Dependence of Neutron Slowing-Down and Therma in Heavy Water

    International Nuclear Information System (INIS)

    Moeller, E.

    1966-03-01

    The behaviour of neutrons during their slowing-down and thermalization in heavy water has been followed on the time scale by measurements of the time-dependent rate of reaction between the flux and the three spectrum indicators indium, cadmium and gadolinium. The space dependence of the reaction rate curves has also been studied. The time-dependent density at 1.46 eV is well reproduced by a function, given by von Dardel, and a time for the maximum density of 7.1 ± 0.3 μs has been obtained for this energy in deuterium gas in agreement with the theoretical value of 7.2 μs. The spatial variation of this time is in accord with the calculations by Claesson. The slowing- down time to 0.2 eV has been found to be 16.3 ±2.4 μs. The approach to the equilibrium spectrum takes place with a time constant of 33 ±4 μs, and the equilibrium has been established after about 200 μs. Comparison of the measured curves for cadmium and gadolinium with multigroup calculations of the time-dependent flux and reaction rate show the superiority of the scattering models for heavy water of Butler and of Brown and St. John over the mass 2 gas model. The experiment has been supplemented with Monte Carlo calculations of the slowing down time

  5. Real-Time Neutron Imaging to Detect Origin of Blocking in Drug Injection Devices.

    Science.gov (United States)

    Kaestner, A; Roth, J; Grünzweig, C

    2016-01-01

    Nondestructive testing is a common method for root cause investigations of malfunction of mechanical devices, for example, medical devices for drug dose delivery. Radiography is a method that has the advantage that it is possible to see through the sample. In this work we are using neutron radiography to observe drug distribution in drug injection devices during the injection process and as post-injection examination. Using neutrons it is possible to show small amounts of liquid in capillaries, and foam bubbles are shown with great contrast compared to metal and glass. The investigation has two parts optimized for high spatial and high temporal resolution, respectively. Using high spatial resolution it is possible to resolve the thin films of drug product in foam and even to detect the drug residues in the injection needle. Switching to high temporal resolution we demonstrate that it is possible to follow the injection process. Spatio-temporal data sets of the injection process were acquired using remotely triggered injection devices and a camera allowing sub-second frame rates.The motion analysis required the application of an edge-preserving spatio-temporal denoising filter to improve the signal-to-noise ratio. After filtering it is possible to detect relevant edges and extract motion curves from the spatio-temporal data. Neutron imaging is a nondestructive method based on radiography using neutrons and is suitable for detecting small amounts of aqueous liquids even in metallic casing/sheath/tubing. This property has here been used to visualize the distribution of a drug product in a syringe needle of a drug injection device. In the static case the method clearly showed the difference between needles that were empty, full, or contained a mix of gas and liquid. A second investigation was aimed to visualize the dynamic behavior of an auto-injector device. In this experiment the imaging method was capable of following the injection phase of the device. By analyzing

  6. Neutron Time-of-Flight Quantification of Water Desorption Isotherms of Montmorillonite

    DEFF Research Database (Denmark)

    Gates, Will P.; Bordallo, Heloisa N.; Aldridge, Laurence P.

    2012-01-01

    The multiple energy states of water held by surfaces of a clay mineral can be effectively probed with time-of-flight and fixed elastic window neutron scattering. We used these techniques to quantitatively differentiate water types, including rotational and translational diffusions, in Ca- and Na...... enabled us to differentiate at least two water motions during dehydration of Ca- and Na-SAz-1 (initially equilibrated at RH = 55%) by using a "controlled water loss" time-of-flight procedure. This work confirms that (a) interlayer and cationic water in dioctahedral smectites are characterized by slower...... motions than interparticle water, (b) interlayer cations influenced the dynamics of water loss, probably through its affect on clay fabric, and (c) interparticle water behaves more like bulk water. At 55% RH the Ca montmorillonite held more interparticle water, but on dehydration under controlled...

  7. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    Energy Technology Data Exchange (ETDEWEB)

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  8. Internal flow measurements of the SSME fuel preburner injector element using real time neutron radiography

    Science.gov (United States)

    Lindsay, John T.; Elam, Sandy; Koblish, Ted; Lee, Phil; Mcauliffe, Dave

    1990-01-01

    Due to observations of unsteady flow in the Space Shuttle Main Engine fuel preburner injector element, several flow studies have been performed. Real time neutron radiography tests were recently completed. This technique provided real time images of MiL-c-7024 and Freon-22 flow through an aluminum liquid oxygen post model at three back pressures (0, 150, and 545 psig) and pressure drops up to 1000 psid. Separated flow appeared only while operating at back pressures of 0 and 150 psig. The behavior of separated flow was similar to that observed for water in a 3x acrylic model of the LOX post. On the average, separated flow appeared to reattach near the exit of the post when the ratio of pressure drop to supply pressure was about 0.75.

  9. Neutrons and fusion

    International Nuclear Information System (INIS)

    Maynard, C.W.

    1976-01-01

    The production of energy from fusion reactions does not require neutrons in the fundamental sense that they are required in a fission reactor. Nevertheless, the dominant fusion reaction, that between deuterium and tritium, yields a 14 MeV neutron. To contrast a fusion reactor based on this reaction with the fission case, 3 x 10 20 such neutrons produced per gigawatt of power. This is four times as many neutrons as in an equivalent fission reactor and they carry seven times the energy of the fission neutrons. Thus, they dominate the energy recovery problem and create technological problems comparable to the original plasma confinement problem as far as a practical power producing device is concerned. Further contrasts of the fusion and fission cases are presented to establish the general role of neutrons in fusion devices. Details of the energy deposition processes are discussed and those reactions necessary for producing additional tritium are outlined. The relatively high energy flux with its large intensity will activate almost any materials of which the reactor may be composed. This activation is examined from the point of view of decay heat, radiological safety, and long-term storage. In addition, a discussion of the deleterious effects of neutron interactions on materials is given in some detail; this includes the helium and hydrogen producing reactions and displacement rate of the lattice atoms. The various materials that have been proposed for structural purposes, for breeding, reflecting, and moderating neutrons, and for radiation shielding are reviewed from the nuclear standpoint. The specific reactions of interest are taken up for various materials and finally a report is given on the status and prospects of data for fusion studies

  10. Microscopic predictions of fission yields based on the time dependent GCM formalism

    Directory of Open Access Journals (Sweden)

    Regnier D.

    2016-01-01

    Full Text Available Accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r-process to fuel cycle optimization in nuclear energy. The need for a predictive theory applicable where no data is available, together with the variety of potential applications, is an incentive to develop a fully microscopic approach to fission dynamics. One of the most promising theoretical frameworks is the time-dependent generator coordinate method (TDGCM applied under the Gaussian overlap approximation (GOA. Previous studies reported promising results by numerically solving the TDGCM+GOA equation with a finite difference technique. However, the computational cost of this method makes it difficult to properly control numerical errors. In addition, it prevents one from performing calculations with more than two collective variables. To overcome these limitations, we developed the new code FELIX-1.0 that solves the TDGCM+GOA equation based on the Galerkin finite element method. In this article, we briefly illustrate the capabilities of the solver FELIX-1.0, in particular its validation for n+239Pu low energy induced fission. This work is the result of a collaboration between CEA,DAM,DIF and LLNL on nuclear fission theory.

  11. Time resolved photoluminescence of [alpha] centers in neutron irradiated SiO[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Anedda, A. (Dipartimento di Scienze Fisiche dell' Universita, via Ospedale 72, 09123 Cagliari (Italy)); Congiu, F. (Dipartimento di Scienze Fisiche dell' Universita, via Ospedale 72, 09123 Cagliari (Italy)); Raga, F. (Dipartimento di Scienze Fisiche dell' Universita, via Ospedale 72, 09123 Cagliari (Italy)); Corazza, A. (Dipartimento di Fisica dell' Universita, via Celoria 16, 20133 Milano (Italy)); Martini, M. (Dipartimento di Fisica dell' Universita, via Celoria 16, 20133 Milano (Italy)); Spinolo, G. (Dipartimento di Fisica dell' Universita, via Celoria 16, 20133 Milano (Italy)); Vedda, A. (Dipartimento di Fisica dell' Universita, via Celoria 16, 20133 Milano (Italy))

    1994-06-01

    Photoluminescence in various types of silica (a-SiO[sub 2]) both unirradiated and neutron irradiated has been studied in the range 10-300 K. The already reported [alpha] emissions at 4.25 eV and at 4.35 eV, whose respective excitation bands peak at 5.10 eV and 4.96 eV, have been found to be excited also in a band peaking at similar 7.6 eV; the temperature dependence of their intensities has also been investigated for both excitations. Time resolved emission spectroscopy excited by KrF excimer laser (5 eV) allowed the detection of the different lifetimes of the two [alpha] emissions. Similar studies on neutron irradiated quartz (c-SiO[sub 2]) have evidenced the presence of the center emitting at 4.35 eV up to now observed only in a-SiO[sub 2]. ((orig.))

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

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, B.L., E-mail: macdonbl@mcmaster.ca [McMaster University, Department of Medical Physics and Applied Radiation Sciences, Hamilton (Canada); Vanderstelt, J., E-mail: joshv@nray.ca [Nray Services Inc., 56A Head Street, Dundas, ON (Canada); O’Meara, J. [University of Guelph, Department of Physics, Guelph (Canada); McNeill, F.E. [McMaster University, Department of Medical Physics and Applied Radiation Sciences, Hamilton (Canada)

    2016-01-15

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

  13. Positive solution of a time and energy dependent neutron transport problem

    International Nuclear Information System (INIS)

    Pao, C.V.

    1975-01-01

    A constructive method is given for the determination of a solution and an existence--uniqueness theorem for some nonlinear time and energy dependent neutron transport problems, including the linear transport system. The geometry of the medium under consideration is allowed to be either bounded or unbounded which includes the geometry of a finite or infinite cylinder, a half-space and the whole space R/subm/ (m=1,2,center-dotcenter-dotcenter-dot). Our approach to the problem is by successive approximation which leads to various recursion formulas for the approximations in terms of explicit integrations. It is shown under some Lipschitz conditions on the nonlinear functions, which describe the process of neutrons absorption, fission, and scattering, that the sequence of approximations converges to a unique positive solution. Since these conditions are satisfied by the linear transport equation, all the results for the nonlinear system are valid for the linear transport problem. In the general nonlinear problem, the existence of both local and global solutions are discussed, and an iterative process for the construction of the solution is given

  14. Timing and Spectroscopy Requirements for a Plastic Scintillating Fiber Bundle Time-of-Flight Neutron Spectrometer

    Science.gov (United States)

    2013-12-01

    reflections in- volves two different methods. The first is pulse height discrimination and the the second is time discrimination. For pulse height ...noise. All acquired data requires pulse height discrimination in the post-processing of the data. The time discrimination method involves calculating... discrimination , the majority of scin- tillation photons that are totally internally reflected down the scintillator toward the ends will exit and escape the

  15. Distillation time modifies essential oil yield, composition, and antioxidant capacity of fennel (Foeniculum vulgare Mill).

    Science.gov (United States)

    Zheljazkov, Valtcho D; Horgan, Thomas; Astatkie, Tess; Schlegel, Vicki

    2013-01-01

    Fennel (Foeniculum vulgare Mill) is an essential oil crop grown worldwide for production of essential oil, as medicinal or as culinary herb. The essential oil is extracted via steam distillation either from the whole aboveground biomass (herb) or from fennel fruits (seed). The hypothesis of this study was that distillation time (DT) can modify fennel oil yield, composition, and antioxidant capacity of the oil. Therefore, the objective of this study was to evaluate the effect of eight DT (1.25, 2.5, 5, 10, 20, 40, 80, and 160 min) on fennel herb essential oil. Fennel essential oil yield (content) reached a maximum of 0.68% at 160 min DT. The concentration of trans-anethole (32.6-59.4% range in the oil) was low at 1.25 min DT, and increased with an increase of the DT. Alpha-phelandrene (0.9-10.5% range) was the lowest at 1.25 min DT and higher at 10, 80, and 160 min DT. Alpha-pinene (7.1-12.4% range) and beta-pinene (0.95-1.64% range) were higher in the shortest DT and the lowest at 80 min DT. Myrcene (0.93-1.95% range), delta-3-carene (2.1-3.7% range), cis-ocimene (0-0.23% range), and gamma-terpinene (0.22-2.67% range) were the lowest at 1.25 min DT and the highest at 160 min DT. In contrast, the concentrations of paracymene (0.68-5.97% range), fenchone (9.8-22.7% range), camphor (0.21-0.51% range), and cis-anethole (0.14-4.66% range) were highest at shorter DT (1.25-5 min DT) and the lowest at the longer DT (80-160 min DT). Fennel oils from the 20 and 160 min DT had higher antioxidant capacity than the fennel oil obtained at 1.25 min DT. DT can be used to obtain fennel essential oil with differential composition. DT must be reported when reporting essential oil content and composition of fennel essential oil. The results from this study may be used to compare reports in which different DT to extract essential oil from fennel biomass were used.

  16. Effect of application time of integratedchemical fertilizer with cattle manure on the growth, yield and yield components of black cumin (Nigella sativa L.

    Directory of Open Access Journals (Sweden)

    aliye salehi

    2016-05-01

    Full Text Available One of the important aspects of the medicinal plants production is using less chemical inputs. It could be effective for increasing of production and environmental purposes. In order to investigate the effects of application time of integrated chemical fertilizer with cattle manure on growth, yield and yield components of black cumin (Nigella sativa L., an experiment was conducted based on a randomized complete block design with nine treatments and three replications in Research Farm of Shahrekord University during growing season 2011-2012. The treatments consisted of control (no amended nitrogen, cattle manure, urea, three levels of split integrated fertilizers such as cattle manure + urea, cattle manure + cattle manure + urea, and three levels of full integrated fertilizers including cattle manure + urea, cattle manure + cattle manure + urea. The results indicated that integrated application of cattle manure with chemical fertilizer caused significant increase in number of main branch per plant (%11.5, number of capsules per plant (%9.5, 1000-seed weight (%7.4, capsule weight (%5.9, biological yield (%36.7 of black cumin. Full dose application of urea fertilizer with cattle manure (50:50 due to improve of capsules per plant and 1000-seed weight increased significantly grain yield (2397 kg.ha-1. In general, use of integrated cattle manure with chemical fertilizer, full dose application of urea specially, with increasing of fertilizer efficiency led to improve of quantitative characteristic in black cumin. This method caused to cost eliminate of top dressing fertilizer and it can be effective for environment and medicinal plant health.

  17. The Proton Beams for the New Time-of-Flight Neutron Facility at the CERN-PS

    CERN Document Server

    Cappi, R; Métral, G

    2000-01-01

    The experimental determination of neutron cross sections in fission and capture reactions as a function of the neutron energy is of primary importance in nuclear physics. Recent developments at CERN and elsewhere have shown that many fields of research and development, such as the design of Accelerator-Driven Systems (ADS) for nuclear waste incineration, nuclear astrophysics, fundamental nuclear physics, dosimetry for radiological protection and therapy, would benefit from a better knowledge of neutron cross sections. A neutron facility at the CERN-PS has been proposed with the aim of carrying out a systematic and high resolution study of neutron cross sections through Time-Of-Flight (n-TOF) measurement. The facility requires a high intensity proton beam (about 0.7x1013 particles/bunch) distributed in a short bunch (about 25 ns total length) to produce the neutrons by means of a spallation process in a lead target. To achieve these characteristics, a number of complex beam gymnastics have to be performed. All...

  18. Neutron fan beam source for neutron radiography purpose

    International Nuclear Information System (INIS)

    Le Tourneur, P.; Bach, P.; Dance, W. E.

    1999-01-01

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

  19. Development of an ion time-of-flight spectrometer for neutron depth profiling

    Science.gov (United States)

    Cetiner, Mustafa Sacit

    Ion time-of-flight spectrometry techniques are investigated for applicability to neutron depth profiling. Time-of-flight techniques are used extensively in a wide range of scientific and technological applications including energy and mass spectroscopy. Neutron depth profiling is a near-surface analysis technique that gives concentration distribution versus depth for certain technologically important light elements. The technique uses thermal or sub-thermal neutrons to initiate (n, p) or (n, alpha) reactions. Concentration versus depth distribution is obtained by the transformation of the energy spectrum into depth distribution by using stopping force tables of the projectiles in the substrate, and by converting the number of counts into concentration using a standard sample of known dose value. Conventionally, neutron depth profiling measurements are based on charged particle spectrometry, which employs semiconductor detectors such as a surface barrier detector (SBD) and the associated electronics. Measurements with semiconductor detectors are affected by a number of broadening mechanisms, which result from the interactions between the projectile ion and the detector material as well as fluctuations in the signal generation process. These are inherent features of the detection mechanism that involve the semiconductor detectors and cannot be avoided. Ion time-of-flight spectrometry offers highly precise measurement capabilities, particularly for slow particles. For high-energy low-mass particles, measurement resolution tends to degrade with all other parameters fixed. The threshold for more precise ion energy measurements with respect to conventional techniques, such as direct energy measurement by a surface barrier detector, is directly related to the design and operating parameters of the device. Time-of-flight spectrometry involves correlated detection of two signals by a coincidence unit. In ion time-of-flight spectroscopy, the ion generates the primary input

  20. Prompt neutron spectrum of the spontaneous fission of californium-252

    International Nuclear Information System (INIS)

    Zamyatnin, Yu.S.; Kroshkin, N.I.; Korostylev, V.A.; Nefedov, V.N.; Ryazanov, D.K.; Starostov, B.I.; Semenov, A.F.

    1976-01-01

    The californium-252 spontaneous fission neutron spectrum was measured in the energy range of 0.01 to 10 MeV by the time-of-flight technique using various neutron detectors. The measurements of 252 Cf neutron spectrum at energies of 0.01 to 5 MeV were performed as a function of fission fragment kinetic energy. The mean neutron spectrum energy in the range of 0.7 to 10 MeV was found from the results of measurements. The irregularity in the 252 Cf neutron spectrum in the neutron energy range of less than 0.7 MeV compared to theoretical values is discussed. The mechanism of 252 Cf neutron emission is also discussed on the basis of neutron yield angle measurements. 12 references

  1. Development of a New Class of Scintillating Fibres with Very Short Decay Time and High Light Yield

    International Nuclear Information System (INIS)

    Borshchev, O.; Ponomarenko, S.; Surin, N.; Cavalcante, A.B.R.; Gavardi, L.; Gruber, L.; Joram, C.; Shinji, O.

    2017-01-01

    We present first studies of a new class of scintillating fibres which are characterised by very short decay times and high light yield. The fibres are based on a novel type of luminophores admixed to a polystyrene core matrix. These so-called Nanostructured Organosilicon Luminophores (NOL) have high photoluminescense quantum yield and decay times just above 1 ns. A blue and a green emitting prototype fibre with 250 μm diameter were produced and characterised in terms of attenuation length, ionisation light yield, decay time and tolerance to x-ray irradiation. The well-established Kuraray SCSF-78 and SCSF-3HF fibres were taken as references. Even though the two prototype fibres mark just an intermediate step in an ongoing development, their performance is already on a competitive level. In particular, their decay time constants are about a factor of two shorter than the fastest known fibres, which makes them promising candidates for time critical applications.

  2. The Space-Time Variation of Global Crop Yields, Detecting Simultaneous Outliers and Identifying the Teleconnections with Climatic Patterns

    Science.gov (United States)

    Najafi, E.; Devineni, N.; Pal, I.; Khanbilvardi, R.

    2017-12-01

    An understanding of the climate factors that influence the space-time variability of crop yields is important for food security purposes and can help us predict global food availability. In this study, we address how the crop yield trends of countries globally were related to each other during the last several decades and the main climatic variables that triggered high/low crop yields simultaneously across the world. Robust Principal Component Analysis (rPCA) is used to identify the primary modes of variation in wheat, maize, sorghum, rice, soybeans, and barley yields. Relations between these modes of variability and important climatic variables, especially anomalous sea surface temperature (SSTa), are examined from 1964 to 2010. rPCA is also used to identify simultaneous outliers in each year, i.e. systematic high/low crop yields across the globe. The results demonstrated spatiotemporal patterns of these crop yields and the climate-related events that caused them as well as the connection of outliers with weather extremes. We find that among climatic variables, SST has had the most impact on creating simultaneous crop yields variability and yield outliers in many countries. An understanding of this phenomenon can benefit global crop trade networks.

  3. Effect of various sucker sizes and planting times on growth and flower yield of chrysanthemum

    International Nuclear Information System (INIS)

    Nawaz, A.; Gul, S.; Anjum, M.A.

    2009-01-01

    Small and large sized suckers of Chrysanthemum morifolium were planted on four different dates, i.e. 18th February, 18th April, 17th June and 16th August to find out their effect on growth and flower yield. Plants resulting from small sized suckers produced significantly higher number of primary and secondary branches and leaves plant/sup -1/. However, plant height, leaf area, number of suckers produced, biomass (fresh plant weight) and flower yield plant/sup -1/ were not affected by the sucker sizes. As the planting was delayed, plant growth and flower yield was reduced. Early plantings resulted in increased plant height, more number of branches and leaves plant/sup -1/, greater biomass, and higher flower yields but reduced leaf area as compared to late plantings. (author)

  4. Towards Real-Time Mapping of Smallholder Maize Yields Using Multiple New Sensors

    Science.gov (United States)

    Campolo, J.; Azzari, G.; Maurice, S.; Nakalembe, C. L.; Becker-Reshef, I.; Lobell, D. B.

    2016-12-01

    Remote sensing is an invaluable tool for efficiently tracking crop production and understanding causes of yield losses in farmers' fields. Previous work has used MODIS and Landsat imagery to estimate crop yield, but the limited resolution of these satellites (250m and 30m per pixel, respectively) precluded the exposure of between- and within-field patterns in smallholder-dominated landscapes. In this project we use a satellite-based technique named Scalable Crop Yield Mapper (SCYM) with data collected from various finer resolution sensors, including commercial "cubesats", in Morogoro, Tanzania. Results derived from four sensors - Sentinel-2 MSI (10m), RapidEye (5m), PlanetScope Dove (3m), and Terra Bella SkySat (2m) - were compared with ground data collected from whole-field harvests in 33 maize fields. The results help to demonstrate the ability to map yields in smallholder systems and the relative merits of the different data sources by themselves and in combination.

  5. Neutron diffraction

    International Nuclear Information System (INIS)

    James, M.; Howard, C.J.; Kennedy, S.

    1999-01-01

    Diffraction methods, especially X-ray diffraction, are widely used in materials science. Neutron diffraction is in many ways similar to X-ray diffraction, but is also complementary to the X-ray technique so that in some cases it yields information not accessible using X-rays. Successes of neutron diffraction include the elucidation of the crystal structures of high temperature superconductors and materials that display colossal magnetoresistance, the phase analysis of zirconia engineering ceramics, in depth stress determination in composites, successful determination of the structures of metal hydrides, transition metal polymer complexes and the determination of magnetic structure. A brief description of current studies, using neutron diffraction is given

  6. Quasielastic and low-energy inelastic neutron scattering study of HoCrO3 by high resolution time-of-flight neutron spectroscopy.

    Science.gov (United States)

    Chatterji, Tapan Kumar; Demmel, F; Jalarvo, Niina; Podlesnyak, Andrey; Chogondalli Muniraju, Naveen Kumar; Xiao, Yinguo; Brueckel, Thomas

    2017-10-10

    n order to understand the origin of the huge quasielastic magnetic scattering observed previously with a back-scattering neutron spectrometer we have re-investigated the low energy excitations in HoCrO$_3$ by inelastic neutron scattering in a much wider energy range with time-of-flight neutron spectrometers. The inelastic signals are due to the excitations between the ground state doublet of the Ho ion. The quasielastic signal is due to the fluctuation of the disordered Ho moments. At low temperature the intensity of quasielastic scattering is small. It starts increasing as the temperature increases above 30 K. At the same temperature the elastic intensity due to Ho moment ordering decreases in a similar way. This observation strengthens the hypothesis that the quasielastic scattering is due the fluctuations of the disordered Ho moments. The time scale of fluctuations has been determine from the quasielastic scattering and was found to vary from about 22 ps at T = 70 K to about 2.5 ps at T = 160 K. The stretched exponential line shape indicates a distribution of decay rates at low temperatures. © 2017 IOP Publishing Ltd.

  7. Quasielastic and low-energy inelastic neutron scattering study of HoCrO3 by high resolution time-of-flight neutron spectroscopy

    Science.gov (United States)

    Chatterji, T.; Demmel, F.; Jalarvo, N.; Podlesnyak, A.; Kumar, C. M. N.; Xiao, Y.; Brückel, T.

    2017-11-01

    In order to understand the origin of the huge quasielastic magnetic scattering observed previously with a back-scattering neutron spectrometer, we have re-investigated the low energy excitations in HoCrO3 by inelastic neutron scattering in a much wider energy range with time-of-flight neutron spectrometers. The inelastic signals are due to the excitations between the ground state doublet of the Ho ion. The quasielastic signal is due to the fluctuation of the disordered Ho moments. At low temperature the intensity of quasielastic scattering is small. It starts increasing as the temperature increases above 30 K. At the same temperature, the elastic intensity due to Ho moment ordering decreases in a similar way. This observation strengthens the hypothesis that the quasielastic scattering is due the fluctuations of the disordered Ho moments. The time scale of fluctuations has been determine from the quasielastic scattering and was found to vary from about 22 ps at T = 70 K to about 2.5 ps at T = 160 K. The stretched exponential line shape indicates a distribution of decay rates at low temperatures.

  8. Accelerators and neutron capture therapy

    International Nuclear Information System (INIS)

    Burlon, A. A.; Kreiner, A. J.; Valda, A.

    2002-01-01

    Within the frame of Accelerator Based Boron Neutron Capture Therapy (AB-BNCT), the 7Li(p,n)7Be reaction, relatively near its energy threshold is one of the most promising, due to its high yield and low neutron energy. In this work a thick LiF target irradiated with a proton beam was studied as a neutron source. The 1.88-2.0 MeV proton beam was produced by the tandem accelerator TANDAR at CNEA's facilities in Buenos Aires. A water-filled phantom, containing a boron sample was irradiated with the resulting neutron flux. The 10B(n,αγ)7Li boron neutron capture reaction produces a 0.478 MeV gamma ray in 94% of the cases. The neutron yield was measured through the detection of this gamma ray using a hyperpure germanium detector with an anti-Compton shield. In addition, the thermal neutron flux was evaluated at different depths inside the phantom using bare and Cd-covered gold foils. A maximum neutron thermal flux of 1.4x108 cm-2s-1mA-1 was obtained at 4.2 cm from the phantom surface. In order to optimize the design of the neutron production target and the beam shaping assembly extensive Monte Carlo Neutron and Photon (MCNP) simulations have been performed. Neutron fields from a thick LiF and a Li metal target (with both a D2O-graphite and a Al/AlF3-graphite moderator/reflector assembly) were evaluated along the centerline of a head and a whole body phantom. Simulations were carried out for 1.89, 2.0 and 2.3 MeV proton beams. The results show that it is more advantageous to irradiate the target with 2.3 MeV near-resonance protons, instead of very near threshold, because of the higher neutron yield at this energy. On the other hand, the Al/AlF3-graphite exhibits a more efficient performance than D2O in terms of tumor to maximum healthy tissue dose ratio. Treatment times of less than 15 min and tumor control probabilities larger than 98% are obtained for a 50 mA, 2.3 MeV proton beam. The alternative neutron-producing reaction 13C(d,n) is also briefly reviewed. A proposal

  9. Analyzer of neutron flux in real time; Analizador de flujo neutronico en tiempo real

    Energy Technology Data Exchange (ETDEWEB)

    Rojas S, A.S.; Carrillo M, R.A.; Balderas, E.G. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    With base in the study of the real signals of neutron flux of instability events occurred in the Laguna Verde nuclear power plant where the nucleus oscillation phenomena of the reactor are in the 0 to 2.5 Hz range, it has been seen the possibility about the development a surveillance and diagnostic equipment capable to analyze in real time the behavior of nucleus in this frequencies range. An important method for surveillance the stability of the reactor nucleus is the use of the Power spectral density which allows to determine the frequencies and amplitudes contained in the signals. It is used an instrument carried out by LabVIEW graphic programming with a data acquisition card of 16 channels which works at Windows 95/98 environment. (Author)

  10. Time-resolved neutron diffraction analyses of hydrothermal synthesis using a novel autoclave cell

    International Nuclear Information System (INIS)

    Polak, E.; Munn, J.; Barnes, P.; Tarling, S.E.

    1990-01-01

    An autoclave cell has been designed for performing time-resolved neutron diffraction analyses of the dynamic processes occurring during hydrothermal syntheses under hostile (corrosive and explosive) conditions: Such conditions include those of hot NaOH/NaOD solutions and pressurized steam. The cell is also capable of measuring differential pressures and accurate sample temperatures as required for the study of reactions which are temperature sensitive. The cell is described and examples of its successful use are given illustrating the synthesis of basic zeolites and a layered calcium silicate hydrate. This technique has considerable potential for studying a variety of synthesis processes of industrial importance, such as in the production of catalysts and the hydration of cements. (orig.)

  11. Real-time observations of lithium battery reactions-operando neutron diffraction analysis during practical operation.

    Science.gov (United States)

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-06-30

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries.

  12. Real-time observations of lithium battery reactions—operando neutron diffraction analysis during practical operation

    Science.gov (United States)

    Taminato, Sou; Yonemura, Masao; Shiotani, Shinya; Kamiyama, Takashi; Torii, Shuki; Nagao, Miki; Ishikawa, Yoshihisa; Mori, Kazuhiro; Fukunaga, Toshiharu; Onodera, Yohei; Naka, Takahiro; Morishima, Makoto; Ukyo, Yoshio; Adipranoto, Dyah Sulistyanintyas; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Suzuki, Kota; Hirayama, Masaaki; Kanno, Ryoji

    2016-01-01

    Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries. PMID:27357605

  13. New moderator for pulsed neutron diffraction

    International Nuclear Information System (INIS)

    Mayer, R.E.; Granada, J.R.; Gillette, V.H.; Dawidowski, J.

    1989-01-01

    Experiments of neutron diffraction, leakage spectrum and pulse decay have been carried out on a new geometry, heterogeneously poisoned, set of moderators and on conventional sandwich and slab moderators for comparison purposes. For a given time pulse width, great increase in neutron leakage intensity has been found in these assemblies, up to 2.7 times that of a sandwich moderator. Clues to implementation of desired time-response in moderator design and of further increases in neutron yields are suggested by present results. 8 refs., 4 figs., 1 tab

  14. Effects of Phosphorus and Harvest Time on Dry Matter Yield, Nitrogen and Phosphorus Contents of Horsegram Macrotyloma uniflorum

    OpenAIRE

    Omokanye, AT.; Amodu, JT.; Onifade, OS.

    1996-01-01

    A two year field study was conducted at Shika, Northern Nigeria to determine the effects of phosphorus levels (0, 40, 80 and 120 kg P205/ha) and harvest times (6, 9, 12 and 15 weeks after planting, WAP) on dry matter yield (DM), N and P distribution in plant parts of horsegram (Macrotyloma uniflorum). Leafand stem DM yields (2.8 and 2.3 t/ha) were hig-hest (P

  15. Effects of gauge volume on pseudo-strain induced in strain measurement using time-of-flight neutron diffraction

    Science.gov (United States)

    Suzuki, Hiroshi; Harjo, Stefanus; Abe, Jun; Xu, Pingguang; Aizawa, Kazuya; Akita, Koichi

    2013-07-01

    Spurious or pseudo-strains observed in time-of-flight (TOF) neutron diffraction due to neutron attenuation, surface-effects and a strain distribution within the gauge volume were investigated. Experiments were carried out on annealed and bent ferritic steel bars to test these effects. The most representative position in the gauge volume corresponds to the neutron-weighted center of gravity (ncog), which takes into account variations in intensity within the gauge volume due to neutron attenuation and/or absence of material in the gauge volume. The average strain in the gauge volume was observed to be weighted towards the ncog position but following an increase in the size of the gauge volume the weighted average strain was changed because of the change in the ncog position when a strain gradient appeared within the gauge volume. On the other hand, typical pseudo-strains, which are well known, did appear in through-surface strain measurements when the gauge volume was incompletely filled by the sample. Tensile pseudo-strains due to the surface-effect increased near the sample surface and exhibited a similar trend regardless of the size of the gauge volume, while the pseudo-strains increased faster for the smaller gauge volume. Furthermore, a pseudo-strain due to a change in the ncog position was observed even when the gauge volume was perfectly filled in the sample, and it increased with an increase in the size of the gauge volume. These pseudo-strains measured were much larger than those simulated by the conventional modeling, whereas they were simulated by taking into account an incident neutron beam divergence additionally in the model. Therefore, the incident divergence of the incident neutron beam must be carefully designed to avoid pseudo-strains in time-of-flight neutron diffractometry.

  16. Calibration issues for neutron diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Sadler, G.J. [JET Joint Undertaking, Abingdon (United Kingdom); Adams, J.M. [AEA Technology, Harwell (United Kingdom); Barnes, C.W. [Los Alamos National Lab., NM (United States)] [and others

    1997-12-01

    The performance of diagnostic systems are limited by their weakest constituents, including their calibration issues. Neutron diagnostics are notorious for problems encountered while determining their absolute calibrations, due mainly to the nature of the neutron transport problem. In order to facilitate the determination of an accurate and precise calibration, the diagnostic design should be such as to minimize the scattered neutron flux. ITER will use a comprehensive set of neutron diagnostics--comprising radial and vertical neutron cameras, neutron spectrometers, a neutron activation system and internal and external fission chambers--to provide accurate measurements of fusion power and power densities as a function of time. The calibration of such an important diagnostic system merits careful consideration. Some thoughts have already been given to this subject during the conceptual design phase in relation to the time-integrated neutron activation and time-dependent neutron yield monitors. However, no overall calibration strategy has been worked out so far. This paper represents a first attempt to address this vital issue. Experience gained from present large tokamaks (JET, TFTR and JT60U) and proposals for ITER are reviewed. The need to use a 14-MeV neutron generator as opposed to radioactive sources for in-situ calibration of D-T diagnostics will be stressed. It is clear that the overall absolute determination of fusion power will have to rely on a combination of nuclear measuring techniques, for which the provision of accurate and independent calibrations will constitute an ongoing process as ITER moves from one phase of operation to the next.

  17. Time-of-flight neutron rejection to improve prompt gamma imaging for proton range verification: a simulation study.

    Science.gov (United States)

    Biegun, Aleksandra K; Seravalli, Enrica; Lopes, Patrícia Cambraia; Rinaldi, Ilaria; Pinto, Marco; Oxley, David C; Dendooven, Peter; Verhaegen, Frank; Parodi, Katia; Crespo, Paulo; Schaart, Dennis R

    2012-10-21

    Therapeutic proton and heavier ion beams generate prompt gamma photons that may escape from the patient. In principle, this allows for real-time, in situ monitoring of the treatment delivery, in particular, the hadron range within the patient, by imaging the emitted prompt gamma rays. Unfortunately, the neutrons simultaneously created with the prompt photons create a background that may obscure the prompt gamma signal. To enhance the accuracy of proton dose verification by prompt gamma imaging, we therefore propose a time-of-flight (TOF) technique to reject this neutron background, involving a shifting time window to account for the propagation of the protons through the patient. Time-resolved Monte Carlo simulations of the generation and transport of prompt gamma photons and neutrons upon irradiation of a PMMA phantom with 100, 150 and 200 MeV protons were performed using Geant4 (version 9.2.p02) and MCNPX (version 2.7.D). The influence of angular collimation and TOF selection on the prompt gamma and neutron longitudinal profiles is studied. Furthermore, the implications of the proton beam microstructure (characterized by the proton bunch width and repetition period) are investigated. The application of a shifting TOF window having a width of ΔTOF(z) = 1.0 ns appears to reduce the neutron background by more than 99%. Subsequent application of an energy threshold does not appear to sharpen the distal falloff of the prompt gamma profile but reduces the tail that is observed beyond the proton range. Investigations of the influence of the beam time structure show that TOF rejection of the neutron background is expected to be effective for typical therapeutic proton cyclotrons.

  18. The Relationship between the thermal time accumulated during the long period of growth in agricultural yields of sugarcane

    Directory of Open Access Journals (Sweden)

    Maira Ferrer Reyes

    2016-10-01

    Full Text Available The work was carried out at the station for irrigation and drainage of sugarcane, Havana province. The time heat in the great period of growth was determined in eight stools grow Ja 60-5, under irrigation and rain fed conditions. The thermal time accumulated during the great period of growth, plants and sprouts was superior to that obtained under rain fed conditions and tended to decrease as the great period started later to the month of may, similarly behaved the agricultural yield. Greater heat time was obtained by the plant "noviembre.81" and their respective offspring under irrigation conditions, with 1314,3 and 117,35 0C day, respectively. The yields of these plantations were: 166 and to117.5 tha-1 the tendency found between the thermal time and agricultural yields, with the date of commencement of the great period of growth was adjusted to a logarithmic type model.

  19. Test of parity-conserving time-reversal invariance using polarized neutrons and nuclear spin aligned holmium

    International Nuclear Information System (INIS)

    Huffman, P.R.; Roberson, N.R.; Wilburn, W.S.; Gould, C.R.; Haase, D.G.; Keith, C.D.; Raichle, B.W.; Seely, M.L.; Walston, J.R.

    1997-01-01

    A test of parity-conserving, time-reversal noninvariance (PC TRNI) has been performed in 5.9 MeV polarized neutron transmission through nuclear spin aligned holmium. The experiment searches for the T-violating fivefold correlation via a double modulation technique emdash flipping the neutron spin while rotating the alignment axis of the holmium. Relative cross sections for spin-up and spin-down neutrons are found to be equal to within 1.2x10 -5 (80% confidence). This is a two orders of magnitude improvement compared to traditional detailed balance studies of time reversal, and represents the most precise test of PC TRNI in a dynamical process, to our knowledge. copyright 1997 The American Physical Society

  20. A novel method for modeling the neutron time of flight (nTOF) detector response in current mode to inertial confinement fusion experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Alan J. [University of New Mexico, Albuquerque, NM; Cooper, Gary Wayne [University of New Mexico, Albuquerque, NM; Ruiz, Carlos L.; Chandler, Gordon Andrew; Fehl, David Lee; Hahn, Kelly Denise; Leeper, Ramon Joe; Smelser, Ruth Marie; Torres, Jose A.

    2013-09-01

    There are several machines in this country that produce short bursts of neutrons for various applications. A few examples are the Zmachine, operated by Sandia National Laboratories in Albuquerque, NM; the OMEGA Laser Facility at the University of Rochester in Rochester, NY; and the National Ignition Facility (NIF) operated by the Department of Energy at Lawrence Livermore National Laboratory in Livermore, California. They all incorporate neutron time of flight (nTOF) detectors which measure neutron yield, and the shapes of the waveforms from these detectors contain germane information about the plasma conditions that produce the neutrons. However, the signals can also be %E2%80%9Cclouded%E2%80%9D by a certain fraction of neutrons that scatter off structural components and also arrive at the detectors, thereby making analysis of the plasma conditions more difficult. These detectors operate in current mode - i.e., they have no discrimination, and all the photomultiplier anode charges are integrated rather than counted individually as they are in single event counting. Up to now, there has not been a method for modeling an nTOF detector operating in current mode. MCNPPoliMiwas developed in 2002 to simulate neutron and gammaray detection in a plastic scintillator, which produces a collision data output table about each neutron and photon interaction occurring within the scintillator; however, the postprocessing code which accompanies MCNPPoliMi assumes a detector operating in singleevent counting mode and not current mode. Therefore, the idea for this work had been born: could a new postprocessing code be written to simulate an nTOF detector operating in current mode? And if so, could this process be used to address such issues as the impact of neutron scattering on the primary signal? Also, could it possibly even identify sources of scattering (i.e., structural materials) that

  1. Seed yield of radish as affected by uprooting time and root cutting

    Directory of Open Access Journals (Sweden)

    A. H. M. Shohidul Hoque

    2015-08-01

    Full Text Available The experiment was conducted at the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU, Gazipur, Bangladesh during November 2005 to April 2006 to study the seed production potentiality of BSMRAU developed open pollinated radish varieties (viz., BU Mula 1 and BU Mula 2 under two levels of root cutting (viz., one third and no cutup and three levels of uprooting namely 30, 40 and 50 days after sowing (DAS. Results revealed that both root cutting and uprooting days significantly influenced most of the characters pertaining to seed yield per plant. Root cutting delayed the flowering, pod initiation, maturation of siliqua and reduced plant height, number of branches per plant, number of siliqua per plant, and number of seeds per siliqua. The yields were also impaired by root cutting. In general, the entire yield components and seed yield were highly affected with the one third root cutting. Various uprooting days also had influenced these characters. In case of treatment combination of no cut and 30 days of uprooting there was a significant difference between the varieties. The variety BU Mula 2 produced better seed yield per plot than BU Mula 1. Also in both the varieties the 1/3rd cut treatment with 30 or 50 days uprooting sequence showed unsatisfied number of seeds per siliqua in comparison to the no cut treatment except 40 days uprooting.

  2. 252Cf fission-neutron spectrum using a simplified time-of-flight setup: An advanced teaching laboratory experiment

    Science.gov (United States)

    Becchetti, F. D.; Febbraro, M.; Torres-Isea, R.; Ojaruega, M.; Baum, L.

    2013-02-01

    The removal of PuBe and AmBe neutron sources from many university teaching laboratories (due to heightened security issues) has often left a void in teaching various aspects of neutron physics. We have recently replaced such sources with sealed 252Cf oil-well logging sources (nominal 10-100 μCi), and developed several experiments using them as neutron sources. This includes a fission-neutron time-of-flight experiment using plastic scintillators, which utilizes the prompt γ rays emitted in 252Cf spontaneous fission as a fast timing start signal. The experiment can be performed with conventional nuclear instrumentation and a 1-D multi-channel pulse-height analyzer, available in most advanced teaching laboratories. Alternatively, a more sophisticated experiment using liquid scintillators and n/γ pulse-shape discrimination can be performed. Several other experiments using these neutron sources are also feasible. The experiments can introduce students to the problem of detecting the dark matter thought to dominate the universe and to the techniques used to detect contraband fissionable nuclear materials.

  3. Design of auto-control high-voltage control system of pulsed neutron generator

    International Nuclear Information System (INIS)

    Lv Juntao

    2008-01-01

    It is difficult to produce multiple anode controlling time sequences under different logging mode for the high-voltage control system of the conventional pulsed neutron generator. It is also difficult realize sequential control among anode high-voltage, filament power supply and target voltage to make neutron yield stable. To these problems, an auto-control high-voltage system of neutron pulsed generator was designed. It not only can achieve anode high-voltage double blast time sequences, which can measure multiple neutron blast time sequences such as Σ, activated spectrum, etc. under inelastic scattering mode, but also can realize neutron generator real-time measurement of multi-state parameters and auto-control such as target voltage pulse width modulation (PWM), filament current, anode current, etc., there by it can produce stable neutron yield and realize stable and accurate measurement of the pulsed neutron full spectral loging tool. (authors)

  4. Digital pulse-timing technique for the neutron detector array NEDA

    Energy Technology Data Exchange (ETDEWEB)

    Modamio, V., E-mail: victor.modamio@lnl.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Valiente-Dobón, J.J. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Jaworski, G. [Faculty of Physics, Warsaw University of Technology, 00-662 Warszawa (Poland); Heavy Ion Laboratory, University of Warsaw, 02-093 Warszawa (Poland); Hüyük, T. [Instituto de Física Corpuscular, CSIC-Universitat de València, E-46980 Valencia (Spain); Triossi, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Egea, J. [Instituto de Física Corpuscular, CSIC-Universitat de València, E-46980 Valencia (Spain); Department of Electronic Engineering, Universitat de València, E-46100 Burjassot (Spain); Di Nitto, A. [Johannes Gutenberg-Universität Mainz, D-55099 Mainz (Germany); Söderström, P.-A. [RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan); Agramunt Ros, J. [Instituto de Física Corpuscular, CSIC-Universitat de València, E-46980 Valencia (Spain); Angelis, G. de [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); France, G. de [GANIL, CEA/DSAM and CNRS/IN2P3, F-14076 Caen (France); Erduran, M.N. [Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University, 34303 Istanbul (Turkey); and others

    2015-03-01

    A new digital pulse-timing algorithm, to be used with the future neutron detector array NEDA, has been developed and tested. The time resolution of four 5 in. diameter photomultiplier tubes (XP4512, R4144, R11833-100, and ET9390-kb), coupled to a cylindrical 5 in. by 5 in. BC501A liquid scintillator detector was measured by employing digital sampling electronics and a constant fraction discriminator (CFD) algorithm. The zero crossing of the CFD algorithm was obtained with a cubic spline interpolation, which was continuous up to the second derivative. The performance of the algorithm was studied at sampling rates of 500 MS/s and 200 MS/s. The time resolution obtained with the digital electronics was compared to the values acquired with a standard analog CFD. The result of this comparison shows that the time resolution from the analog and the digital measurements at 500 MS/s and at 200 MS/s are within 15% for all the tested photomultiplier tubes.

  5. Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

    Directory of Open Access Journals (Sweden)

    Xuejun Dong

    2016-05-01

    Full Text Available High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm

  6. The influence of crop density and harvesting time on yield and quality of various sugar beet cultivars

    Directory of Open Access Journals (Sweden)

    Filipović Vladimir

    2009-01-01

    Full Text Available In this paper the influence of crop density and harvesting time on yield and quality of various sugar beet cultivars has been analyzed. During three year research conducted on soil of carbonate chernozem on loess terrace on experimental field of Institute Tamiš in Pančevo. Method of completely random block system in four repetitions we're analyzed the influence of crop density (80.000 plants per ha, 100.000 plants per ha and 120.000 plants per ha and harvesting time (10th Sept, 01st Oct and 20th Oct on yield and quality of various sugar beet cultivars of different technological type (Esprit N - type, Belinda Z - type and Chiara NE - type. Increase in crop density had very little effect on increase on sugar beet yield. The yield was considerably increased in the period between the first harvesting date and the second. The highest yield of consumable sugar was obtained of cultivars of N - type Esprit and lower yield was obtained of cultivars of Z - type (Belinda. .

  7. Data processing workflow for time of flight polarized neutrons inelastic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Savici, Andrei T [ORNL; Zaliznyak, Igor [Brookhaven National Laboratory (BNL); Garlea, Vasile O [ORNL; Winn, Barry L [ORNL

    2017-01-01

    We discuss the data processing workflow for polarized neutron scattering measurements performed at HYSPEC spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. The effects of the focusing Heusler crystal polarizer and the wide-angle supermirror transmission polarization analyzer are added to the data processing flow of the non-polarized case. The implementation is done using the Mantid software package.

  8. The data acquisition system of the neutron time-of-flight facility nTOF at CERN

    CERN Document Server

    Abbondanno, U; Alvarez, F; Alvarez, H; Andriamonje, Samuel A; Andrzejewski, J; Badurek, G; Baumann, P; Becvar, F; Benlliure, J; Berthomieux, E; Betev, B; Calviño, F; Cano-Ott, D; Capote, R; Cennini, P; Chepel, V Yu; Chiaveri, Enrico; Colonna, N; Cortés, G; Cortina-Gil, D; Couture, A; Cox, J; Dababneh, S; David, S; Dolfini, R; Domingo-Pardo, C; Durán, I; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Frais-Kölbl, H; Furman, W; Gonçalves, I; González-Romero, E M; Goverdovski, A A; Gramegna, F; Griesmayer, E; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Isaev, S; Jericha, E; Kadi, Y; Käppeler, F K; Kerveno, M; Ketlerov, V; Köhler, P E; Konovalov, V; Krticka, M; Leeb, H; Lindote, A; Lopes, M I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martínez-Val, J M; Mastinu, P; Mengoni, A; Milazzo, P M; Molina-Coballes, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, Heinz; O'Brien, S; Pancin, J; Papaevangelou, T; Paradela, C; Pavlik, A; Pavlopoulos, P; Perlado, J M; Perrot, L; Peskov, Vladimir; Plag, R; Plompen, A; Plukis, A; Poch, A; Policarpo, Armando; Pretel, C; Quesada, J M; Rapp, W; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, V; Schäfer, E; Soares, J C; Stephanq, C; Tagliente, G; Taín, J L; Tassan-Got, L; Tavora, L M N; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín-Fernández, D; Vincente-Vincente, M; Vlachoudis, V; Voss, F; Wendler, H; Wiescher, M; Wisshak, K

    2005-01-01

    The n_TOF facility at CERN has been designed for the measurement of neutron capture, fission and (n, multiplied by n) cross-sections with high accuracy. This requires a flexible and - due to the high instantaneous neutron flux - almost dead time free data acquisition system. A scalable and versatile data solution has been designed based on 8-bit flash-ADCs with sampling rates up to 2 GHz and 8 Mbyte memory buffer. The software is written in C and C++ and is running on PCs equipped with RedHat Linux.

  9. In situ deformation apparatus for time-of-flight neutron diffraction: Texture development of polycrystalline ice Ih

    International Nuclear Information System (INIS)

    McDaniel, S.; Bennett, K.; Durham, W. B.; Waddington, E. D.

    2006-01-01

    This article documents a new in situ deformation apparatus built for neutron diffraction investigations of polycrystalline materials in low-temperature environments and the first experiment in which it was used. We performed texture analysis of fine-grained polycrystalline D 2 O ice I h deformed uniaxially between 230 and 240 K using time-of-flight neutron diffraction on the high-pressure preferred orientation diffractometer at the Manuel Lujan, Jr. Neutron Scattering Center at Los Alamos National Laboratory. The new deformation apparatus operates at 1 atm of ambient pressure and over temperatures in the range of 77 K< T<298 K, and accommodates up to 667 N of uniaxially applied load. It is suitable for diffraction studies of any bulk polycrystalline material, ideally cylindrical in shape, and is adaptable to multiple neutron spectrometers, including those at other polychromatic and monochromatic neutron facilities. The first experiment on a hexagonal ice sample demonstrates development of fiber texture in the direction of the applied load. The equipment has many applications to earth science, glaciology, and ice engineering

  10. Demonstration of a time-integrated short line of sight neutron imaging system for inertial confinement fusion

    International Nuclear Information System (INIS)

    Simpson, R.; Danly, C.; Fatherley, V. E.; Merrill, F. E.; Volegov, P.; Wilde, C.; Christensen, K.; Fittinghoff, D.; Grim, G. P.; Izumi, N.; Jedlovec, D.; Skulina, K.

    2015-01-01

    The Neutron Imaging System (NIS) is an important diagnostic for understanding implosions of deuterium-tritium capsules at the National Ignition Facility. While the detectors for the existing system must be positioned 28 m from the source to produce sufficient imaging magnification and resolution, recent testing of a new short line of sight neutron imaging system has shown sufficient resolution to allow reconstruction of the source image with quality similar to that of the existing NIS on a 11.6 m line of sight. The new system used the existing pinhole aperture array and a stack of detectors composed of 2 mm thick high-density polyethylene converter material followed by an image plate. In these detectors, neutrons enter the converter material and interact with protons, which recoil and deposit energy within the thin active layer of the image plate through ionization losses. The described system produces time-integrated images for all neutron energies passing through the pinhole. We present details of the measurement scheme for this novel technique to produce energy-integrated neutron images as well as source reconstruction results from recent experiments at NIF

  11. A new monitor set for the determination of neutron flux parameters in short-time k0-NAA

    Czech Academy of Sciences Publication Activity Database

    Kubešová, Marie; Kučera, Jan; Fikrle, Marek

    2011-01-01

    Roč. 656, č. 1 (2011), s. 61-64 ISSN 0168-9002 R&D Projects: GA ČR GA202/09/0363 Institutional research plan: CEZ:AV0Z10480505 Keywords : Short-time activation analysis * ko standartizacion * neutron flux parameters Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.207, year: 2011

  12. Dipole resonances in light neutron-rich nuclei studied with time-dependent calculations of antisymmetrized molecular dynamics

    International Nuclear Information System (INIS)

    Kanada-En'yo, Y.; Kimura, M.

    2005-01-01

    To study isovector dipole responses of neutron-rich nuclei, we applied a time-dependent method of antisymmetrized molecular dynamics. The dipole resonances in Be, B, and C isotopes were investigated. In 10 Be, 15 B, and 16 C, collective modes of the vibration between a core and valence neutrons cause soft resonances at the excitation energy E x =10-15 MeV below the giant dipole resonance (GDR). In 16 C, we found that a remarkable peak at E x =14 MeV corresponds to the coherent motion of four valence neutrons against a 12 C core, whereas the GDR arises in the E x >20 MeV region because of vibration within the core. In 17 B and 18 C, the dipole strengths in the low-energy region decline compared with those in 15 B and 16 C. We also discuss the energy-weighted sum rule for the E1 transitions

  13. Global Distribution of Shallow Water on Mars: Neutron Mapping of Summer-Time Surface by HEND/Odyssey

    Science.gov (United States)

    Mitrofanov, I. G.; Litvak, M. L.; Kozyrev, A. S.; Sanin, A. B.; Tretyakov, V. I.; Boynton, W.; Hamara, D.; Shinohara, C.; Saunders, R. S.; Drake, D.

    2003-01-01

    Orbital mapping of induced neutrons and gamma-rays by Odyssey has recently successfully proven the applicability of nuclear methods for studying of the elementary composition of Martian upper-most subsurface. In particular, the suite of Gamma-Ray Spectrometer (GRS) has discovered the presence of large water-ice rich regions southward and northward on Mars. The data of neutron mapping of summer-time surface are presented below from the Russian High Energy Neutron Spectrometer (HEND), which is a part of GRS suite. These maps represent the content of water in the soil for summer season at Southern and Northern hemispheres, when the winter deposit of CO2 is absent on the surface. The seasonal evolution of CO2 coverage on Mars is the subject of the complementary paper.

  14. Neutronics methods for thermal radiative transfer

    International Nuclear Information System (INIS)

    Larsen, E.W.

    1988-01-01

    The equations of thermal radiative transfer are time discretized in a semi-implicit manner, yielding a linear transport problem for each time step. The governing equation in this problem has the form of a neutron transport equation with fission but no scattering. Numerical methods are described, whose origins lie in neutron transport, and that have been successfully adapted to this new problem. Acceleration methods that have been developed specifically for the radiative transfer problem, but may have generalizations applicable in neutronics problems, are also discussed

  15. Nanosecond neutron generator

    International Nuclear Information System (INIS)

    Lobov, S.I.; Pavlovskaya, N.G.; Pukhov, S.P.

    1991-01-01

    High-voltage nanosecond neutron generator for obtaining neutrons in D-T reaction is described. Yield of 6x10 6 neutron/pulse was generated in a sealed gas-filled diode with a target on the cathode by accelerating pulse voltage of approximately 0.5 MV and length at half-height of 0.5 ns and deuterium pressure of 6x10 -2 Torr. Ways of increasing neutron yield and possibilities of creating generators of nanosecond neutron pulses with great service life are considered

  16. Techniques Closely Related to Pulsed Neutron Research

    International Nuclear Information System (INIS)

    Uhrig, R.E.

    1965-01-01

    Techniques related to pulsed neutron research involve the injection of neutrons at one of the boundaries of a nuclear system, and the localized perturbation of the neutron population then propagates throughout the system. The disturbance introduced at the boundary may be continuous, such as a sinusoidal modulation (neutron wave technique) or a pseudo-random (on-off) variation of source strength (pseudo-random pulsing), or it may be a single burst of neutrons. Propagation of the perturbation can be dealt with as a spatially dependent pulse propagation problem. Hence, the impulse response (and source transfer function) of the system at any point can be determined from neutron wave or pseudo-random pulsing experiments which, in turn, allow the evaluation of the nuclear parameters of the system. The neutron wave technique is used to measure diffusion parameters of moderators, the nuclear properties of subcritical assemblies, and to measure thermalization power and diffusion cooling in crystalline moderators. The pseudo-random pulsing technique was developed as a means of measuring subcriticality of nuclear systems. Cross-correlation of the input with the neutron density at several points throughout the system yields the spatially dependent impulse response of the system which can be Fourier-transformed to yield a dispersion (or transfer) function. Other phenomena, including reflection of neutron waves from the interface between heavy water and graphite, interference between propagating disturbances and the lattice of a heavy water, natural uranium system, and neutron pulse propagation in graphite using a pulsed TRIGA reactor as an intense neutron source have been demonstrated. Recent trends in data reduction are toward the incorporation of ''on-line'' digital computers for data reduction. Such techniques, now used for pulse height analysis, are being developed for multichannel time analysis for all types of pulsed neutron research. Data analysis often involves

  17. Diagnostic Technique of Neutron Doppler Broadening for Indirectly-Driven Implosions

    Science.gov (United States)

    Xiong, Yong; Ding, Yongkun; Zheng, Zhijian; Chen, Ming

    2004-06-01

    The neutron Doppler broadening in inertial confinement fusion has been acquired from the time of flight for the neutron, from which the fuel ion temperature can be derived. An ultrafast-quenched plastic scintillation detector was used to measure the time of flight for the neutron at a low-imploded DT neutron yield (5×107-1×108) in the experiment performed on the Shenguang II laser facility. The typical temperatures of ablating targets for indirect drive were around 2.8 keV and the uncertainties were ±30%-±40%. The detection efficiency of the detector for DT neutrons was calibrated at a K-400 accelerator. The time response function of the detection system was calibrated by imploded neutrons from a DT-filled capsule, which can be regarded as a δ function pulsed neutron source due to its much narrower pulse width than that of the measured neutron time-of-flight spectrum.

  18. Diagnostic technique of neutron doppler broadening for indirectly-driven implosions

    International Nuclear Information System (INIS)

    Xiong Yong; Ding Yongkun; Zheng Zhijian; Chen Ming

    2004-01-01

    The neutron Doppler broadening in inertial confinement fusion has been acquired from the time of flight for the neutron, from which the fuel ion temperature can be derived. An ultrafast-quenched plastic scintillation detector was used to measure the time of flight for the neutron at a low-imploded DT neutron yield (5 x 10 7 - 1 x 10 8 ) in the experiment performed on the Shenguang II laser facility. The typical temperatures of ablating targets for indirect drive were around 2.8 keV and the uncertainties were ±30%-±40%. The detection efficiency of the detector for DT neutrons was calibrated at a K-400 accelerator. The time response function of the detection system was calibrated by imploded neutrons from a DT-filled capsule, which can be regarded as a δ function pulsed neutron source due to its much narrower pulse width than that of the measured neutron time-of-flight spectrum. (authors)

  19. Effect of nitrogen fertilizer application timing on nitrogen use efficiency and grain yield of winter wheat in Ireland

    Directory of Open Access Journals (Sweden)

    Efretuei A.

    2016-06-01

    Full Text Available The objectives of this work were to determine the effects of initiating application of fertilizer nitrogen (N to winter wheat at different growth stages (GSs on grain yield and N use efficiency (NUE. A factorial experiment was carried out in two growing seasons (2011 and 2012 with five timings of first N application (GS 24/26 [tillering], GS 30, GS 31, GS 32 or GS 37 and an unfertilized control, two sowing densities (100 and 400 seeds/m2 and a cattle slurry treatment (with or without slurry. The latter was included to simulate variation in soil N supply (SNS. Delaying the first application of N from the tillering stage until GS 30 had no significant effect on grain yield in either year. Further delaying the initial N application until GS 31 caused a significant yield reduction in 2011, in comparison to GS 30 application, but not in 2012. Differences in efficiency of recovery and use of fertilizer N by the crop among the first three application timings were small. There was no evidence to support alteration in the timing of the first application of N in response to low plant density. Slurry application did not influence SNS, so the interaction between SNS and fertilizer N application timing could not be determined. It is concluded that in order to maximise yield and NUE, the first N application should be applied to winter wheat between late tillering and GS 30 and that delaying the first N until GS 31 can lead to yield reductions compared to the yield obtained with earlier application.

  20. Growth of mesoporous silica nanoparticles monitored by time-resolved small-angle neutron scattering.

    Science.gov (United States)

    Hollamby, Martin J; Borisova, Dimitriya; Brown, Paul; Eastoe, Julian; Grillo, Isabelle; Shchukin, Dmitry

    2012-03-06

    Since the first development of surfactant-templated mesoporous silicas, the underlying mechanisms behind the formation of their structures have been under debate. Here, for the first time, time-resolved small-angle neutron scattering (tr-SANS) is applied to study the complete formation of mesoporous silica nanoparticles. A distinct advantage of this technique is the ability to detect contributions from the whole system, enabling the visualization not only of particle genesis and growth but also the concurrent changes to the coexistent micelle population. In addition, using contrast-matching tr-SANS, it is possible to highlight the individual contributions from the silica and surfactant. An analysis of the data agrees well with the previously proposed "current bun" model describing particle growth: Condensing silica oligomers adsorb to micelles, reducing intermicellar repulsion and resulting in aggregation to form initial particle nuclei. From this point, the growth occurs in a cooperative manner, with condensing silica filling the gaps between further aggregating micelles. The mechanistic results are discussed with respect to different reaction conditions by changing either the concentration of the silica precursor or the temperature. In doing so the importance of in situ techniques is highlighted, in particular, tr-SANS, for mechanism elucidation in the broad field of materials science.

  1. Real time processing of neutron monitor data using the edge editor algorithm

    Directory of Open Access Journals (Sweden)

    Mavromichalaki Helen

    2012-09-01

    Full Text Available The nucleonic component of the secondary cosmic rays is measured by the worldwide network of neutron monitors (NMs. In most cases, a NM station publishes the measured data in a real time basis in order to be available for instant use from the scientific community. The space weather centers and the online applications such as the ground level enhancement (GLE alert make use of the online data and are highly dependent on their quality. However, the primary data in some cases are distorted due to unpredictable instrument variations. For this reason, the real time primary data processing of the measured data of a station is necessary. The general operational principle of the correction algorithms is the comparison between the different channels of a NM, taking advantage of the fact that a station hosts a number of identical detectors. Median editor, Median editor plus and Super editor are some of the correction algorithms that are being used with satisfactory results. In this work an alternative algorithm is proposed and analyzed. The new algorithm uses a statistical approach to define the distribution of the measurements and introduces an error index which is used for the correction of the measurements that deviate from this distribution.

  2. Development of a sealed-accelerator-tube neutron generator

    Science.gov (United States)

    Verbeke; Leung; Vujic

    2000-10-01

    Sealed-accelerator-tube neutron generators are being developed in Lawrence Berkeley National Laboratory (LBNL) for applications ranging from neutron radiography to boron neutron capture therapy and neutron activation analysis. The new generation of high-output neutron generators is based on the D-T fusion reaction, producing 14.1-MeV neutrons. The main components of the neutron tube--the ion source, the accelerator and the target--are all housed in a sealed metal container without external pumping. Thick-target neutron yield computations are performed in this paper to estimate the neutron yield of titanium and scandium targets. With an average deuteron beam current of 1 A and an energy of 120 keV, a time-averaged neutron production of approximately 10(14) n/s can be estimated for a tritiated target, for both pulsed and cw operations. In mixed deuteron/triton beam operation, a beam current of 2 A at 150 keV is required for the same neutron output. Recent experimental results on ion sources and accelerator columns are presented and discussed.

  3. The influence of purge times on the yields of essential oil components extracted from plants by pressurized liquid extraction.

    Science.gov (United States)

    Wianowska, Dorota

    2014-01-01

    The influence of different purge times on the yield of the main essential oil constituents of rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and chamomile (Chamomilla recutita L.) was investigated. The pressurized liquid extraction process was performed by applying different extraction temperatures and solvents. The results presented in the paper show that the estimated yield of essential oil components extracted from the plants in the pressurized liquid extraction process is purge time-dependent. The differences in the estimated yields are mainly connected with the evaporation of individual essential oil components and the applied solvent during the purge; the more volatile an essential oil constituent is, the greater is its loss during purge time, and the faster the evaporation of the solvent during the purge process is, the higher the concentration of less volatile essential oil components in the pressurized liquid extraction receptacle. The effect of purge time on the estimated yield of individual essential oil constituents is additionally differentiated by the extraction temperature and the extraction ability of the applied solvent.

  4. Effect of cutting height and time on seed yield and seed quality of Stylosanthes guianensis CIAT 184

    Directory of Open Access Journals (Sweden)

    Pimpaporn Pholsen

    2002-10-01

    Full Text Available The objectives of this experiment were to study the effect of cutting height and time on seed yield and seed quality of Stylosanthes guianensis CIAT 184 in Korat soil series at Khon Kaen Animal Nutrition Research Center, during April 2000 - May 2001. The experimental design was 2 × 4 factorial in randomized complete block design with 4 replications. The treatment consisted of 2 factors: - 1 Two levels of cutting height viz. 20 and 30 cm above ground; 2 Four periods of cutting time viz. at 60, 75, 90 days before 50% flowering date and uncut.The results revealed that seed yield and seed quality were unaffected by cutting height (P>0.05. Seed yield and PGSY obtained from cutting at 90 days and uncut were significantly higher (P<0.05 than cutting at 75 and 60 days (1,575 and 1,438; 1,563 and 1,425; 1,119 and 988; 644 and 563 kg/ha, respectively. There were no significant differences between cutting at 60 and 75 days in 1000-seed weight, but both treatments were significant higher (P<0.05 than cutting at 90 days and uncut. Seed purity and germination percentages were unaffected by cutting height and time, ranging from 93 to 95 and 93 to 96 %, respectively. Significant interactions between cutting height and time on seed yield and seed quality were not found.

  5. Climate change impacts on crop yields, land use and environment in response to crop sowing dates and thermal time requirements

    NARCIS (Netherlands)

    Zimmermann, Andrea; Webber, Heidi; Zhao, Gang; Ewert, Frank; Kros, Hans; Wolf, Joost; Britz, Wolfgang; Vries, de Wim

    2017-01-01

    Impacts of climate change on European agricultural production, land use and the environment depend on its impact on crop yields. However, many impact studies assume that crop management remains unchanged in future scenarios, while farmers may adapt their sowing dates and cultivar thermal time

  6. Effect of enzyme concentration, addition of water and incubation time on increase in yield of starch from potato.

    Science.gov (United States)

    Sit, Nandan; Agrawal, U S; Deka, Sankar C

    2014-05-01

    Enzymatic treatment process for starch extraction from potato was investigated using cellulase enzyme and compared with conventional process. The effects of three parameters, cellulase enzyme concentration, incubation time and addition of water were evaluated for increase in starch yield as compared to the conventional process i.e., without using enzyme. A two-level full factorial design was used to study the process. The results indicated that all the main parameters and their interactions are statistically significant. Enzyme concentration and incubation time had a positive effect on the increase in starch yield while addition of water had a negative effect. The increase in starch yield ranged from 1.9% at low enzyme concentration and incubation time and high addition of water to a maximum of 70% increase from conventional process in starch yield was achieved when enzyme concentration and incubation time were high and addition of water was low suggesting water present in the ground potato meal is sufficient for access to the enzyme with in the slurry ensuring adequate contact with the substrate.

  7. SAM-CE, Time-Dependent 3-D Neutron Transport, Gamma Transport in Complex Geometry by Monte-Carlo

    International Nuclear Information System (INIS)

    2003-01-01

    1 - Nature of physical problem solved: The SAM-CE system comprises two Monte Carlo codes, SAM-F and SAM-A. SAM-F supersedes the forward Monte Carlo code, SAM-C. SAM-A is an adjoint Monte Carlo code designed to calculate the response due to fields of primary and secondary gamma radiation. The SAM-CE system is a FORTRAN Monte Carlo computer code designed to solve the time-dependent neutron and gamma-ray transport equations in complex three-dimensional geometries. SAM-CE is applicable for forward neutron calculations and for forward as well as adjoint primary gamma-ray calculations. In addition, SAM-CE is applicable for the gamma-ray stage of the coupled neutron-secondary gamma ray problem, which may be solved in either the forward or the adjoint mode. Time-dependent fluxes, and flux functionals such as dose, heating, count rates, etc., are calculated as functions of energy, time and position. Multiple scoring regions are permitted and these may be either finite volume regions or point detectors or both. Other scores of interest, e.g., collision and absorption densities, etc., are also made. 2 - Method of solution: A special feature of SAM-CE is its use of the 'combinatorial geometry' technique which affords the user geometric capabilities exceeding those available with other commonly used geometric packages. All nuclear interaction cross section data (derived from the ENDF for neutrons and from the UNC-format library for gamma-rays) are tabulated in point energy meshes. The energy meshes for neutrons are internally derived, based on built-in convergence criteria and user- supplied tolerances. Tabulated neutron data for each distinct nuclide are in unique and appropriate energy meshes. Both resolved and unresolved resonance parameters from ENDF data files are treated automatically, and extremely precise and detailed descriptions of cross section behaviour is permitted. Such treatment avoids the ambiguities usually associated with multi-group codes, which use flux

  8. Fluctuations of radiative widths and the relaxation time of neutron resonances

    International Nuclear Information System (INIS)

    Kal'chenko, A.I.; Prokopets, G.A.

    1989-01-01

    The process of equilibrium state formation is discussed as the first step to be compound nucleus after slow neutron capture. Analysis of 78 nuclei with mass numbers A=27-238 is carried out. 20 refs.; 6 figs.; 2 tabs

  9. Parameters affecting image quality with Time-Resolved Optical Integrative Neutron (TRION) detector

    Science.gov (United States)

    Mor, I.; Vartsky, D.; Feldman, G.; Dangendorf, V.; Bar, D.; Goldberg, M. B.; Tittelmeier, K.; Bromberger, B.; Weierganz, M.; Brandis, M.

    2011-06-01

    We have investigated by simulations and experimentally the parameters that affect image quality (contrast and spatial-resolution) of the fast neutron TRION detector. A scintillating fiber screen with 0.5×0.5 mm 2 square fibers, few centimeters thick, provides superior spatial-resolution to that of a slab scintillator of the same thickness. A detailed calculation of the neutron interaction processes that influence the point-spread function (PSF) in the scintillating screen has been performed using the GEANT 3.21 code. The calculations showed that neutron scattering within the screen accounts for a significant loss of image contrast. The factors that limit the spatial-resolution of the image are the cross-sectional scintillating-fiber dimensions within the screen and the spatial response of the image-intensifier. A deconvolution method has been applied for restoring the contrast and the spatial-resolution of the fast neutron image.

  10. Cellular neural networks (CNN) simulation for the TN approximation of the time dependent neutron transport equation in slab geometry

    International Nuclear Information System (INIS)

    Hadad, Kamal; Pirouzmand, Ahmad; Ayoobian, Navid

    2008-01-01

    This paper describes the application of a multilayer cellular neural network (CNN) to model and solve the time dependent one-speed neutron transport equation in slab geometry. We use a neutron angular flux in terms of the Chebyshev polynomials (T N ) of the first kind and then we attempt to implement the equations in an equivalent electrical circuit. We apply this equivalent circuit to analyze the T N moments equation in a uniform finite slab using Marshak type vacuum boundary condition. The validity of the CNN results is evaluated with numerical solution of the steady state T N moments equations by MATLAB. Steady state, as well as transient simulations, shows a very good comparison between the two methods. We used our CNN model to simulate space-time response of total flux and its moments for various c (where c is the mean number of secondary neutrons per collision). The complete algorithm could be implemented using very large-scale integrated circuit (VLSI) circuitry. The efficiency of the calculation method makes it useful for neutron transport calculations

  11. The analysis and attribution of the time-dependent neutron background resultant from sample irradiation in a SLOWPOKE-2 reactor

    International Nuclear Information System (INIS)

    Sellers, M.T.; Corcoran, E.C.; Kelly, D.G.

    2013-01-01

    The Royal Military College of Canada (RMCC) has commissioned a Delayed Neutron Counting (DNC) system for the analysis of special nuclear materials. A significant, time-dependent neutron background with an initial maximum count rate, more than 50 times that of the time-independent background, was characterised during the validation of this system. This time-dependent background was found to be dependent on the presence of the polyethylene (PE) vials used to transport the fissile samples, yet was not an activation product of vial impurities. The magnitude of the time-dependent background was found to be irradiation site specific and independent of the mass of PE. The capability of RMCC's DNC system to analyze the neutron count rates in time intervals 235 U contamination was present on each irradiated vial. However, Inductively Coupled Plasma-Mass Spectroscopy measurements of material leached from the outer vial surfaces after their irradiations found only trace amounts of uranium, 0.118 ± 0.048 ng of 235 U derived from natural uranium. These quantities are insufficient to account for the time-independent background, and in fact could not be discriminated from the noise associated with time-independent background. It is suggested that delayed neutron emitters are deposited in the vial surface following fission recoil, leaving the main body of uranium within the irradiation site. This hypothesis is supported by the physical cleaning of the site with materials soaked in distilled water and HNO 3 , which lowered the background from a nominal 235 U mass equivalent of 120 to 50 ng per vial. (author)

  12. Spectral-Timing Analysis of Kilohetrz Quasi-Periodic Osciallations in Neutron Star Low-Mass X-ray Binaries

    Science.gov (United States)

    Cackett, Edward; Troyer, Jon; Peille, Philippe; Barret, Didier

    2018-01-01

    Kilohertz quasi-periodic oscillations or kHz QPOs are intensity variations that occur in the X-ray band observed in neutron star low-mass X-ray binary (LMXB) systems. In such systems, matter is transferred from a secondary low-mass star to a neutron star via the process of accretion. kHz QPOs occur on the timescale of the inner accretion flow and may carry signatures of the physics of strong gravity (c2 ~ GM/R) and possibly clues to constraining the neutron star equation of state (EOS). Both the timing behavior of kHz QPOs and the time-averaged spectra of these systems have been studied extensively. No model derived from these techniques has been able to illuminate the origin of kHz QPOs. Spectral-timing is an analysis technique that can be used to derive information about the nature of physical processes occurring within the accretion flow on the timescale of the kHz QPO. To date, kHz QPOs of (4) neutron star LMXB systems have been studied with spectral-timing techniques. We present a comprehensive study of spectral-timing products of kHz QPOs from systems where data is available in the RXTE archive to demonstrate the promise of this technique to gain insights regarding the origin of kHz QPOs. Using data averaged over the entire RXTE archive, we show correlated time-lags as a function of QPO frequency and energy, as well as energy-dependent covariance spectra for the various LMXB systems where spectral-timing analysis is possible. We find similar trends in all average spectral-timing products for the objects studied. This suggests a common origin of kHz QPOs.

  13. Effects of sowing time and plant density on yield and essential oil production of medicinal plant, peppermint (Mentha piperita L.

    Directory of Open Access Journals (Sweden)

    S. Jabarpour

    2016-05-01

    Full Text Available In order to investigate the effects of two sowing time (middle of May and early June and four plant density (8, 12, 16 and 20 plants.m-2 on yield and essential oil content of peppermint at two cutting stages, an experiment was conducted at the Research Farm of the Faculty of Agriculture, University of Tabriz during growing season of 2003-2004. These treatments were performed as factorial based of randomized complete block design with three replications. The result of the first cutting showed that plant sowing at the early June and eight plants.m-2densities had the highest leaf (4.47% and plant (2.92% essential oil percentage, but these factors and their interaction effects did not effect on the essential oil yield. In the second cutting, the highest plant essential oil was observed in plant sowing at early June and 12 plants/m2 densities. The highest essential oil yield in second cutting produced in middle of May sowing time. The results of two cutting stages showed that the fresh and dry yield decreased by delaying in sowing time.

  14. In-situ hydrogen in metal determination using a minimum neutron source strength and exposure time.

    Science.gov (United States)

    Hatem, M; Agamy, S; Khalil, M Y

    2013-08-01

    Water is frequently present in the environment and is a source of hydrogen that can interact with many materials. Because of its small atomic size, a hydrogen atom can easily diffuse into a host metal, and though the metal may appear unchanged for a time, the metal will eventually abruptly lose its strength and ductility. Thus, measuring the hydrogen content in metals is important in many fields, such as in the nuclear industry, in automotive and aircraft fabrication, and particularly, in offshore oil and gas fields. It has been demonstrated that the use of nuclear methods to measure the hydrogen content in metals can achieve sensitivity levels on the order of parts per million. However, the use of nuclear methods in the field has not been conducted for two reasons. The first reason is due to exposure limitations. The second reason is due to the hi-tech instruments required for better accuracy. In this work, a new method using a low-strength portable neutron source is explored in conjunction with detectors based on plastic nuclear detection films. The following are the in-situ requirements: simplicity in setup, high reliability, minimal exposure dose, and acceptable accuracy at an acceptable cost. A computer model of the experimental setup is used to reproduce the results of a proof-of-concept experiment and to predict the sensitivity levels under optimised experimental conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Disentanglement time of the crystallites in RPDM irradiated with a low neutron flux

    International Nuclear Information System (INIS)

    Mocellini, R.R.; Lambri, O.A.; Celauro, C.A.; Rodriguez Garraza, A.L.; Sorichetti, P.A.

    2006-01-01

    Electrical insulators of organic type are composed by a rigid nucleus of some type of epoxy resin and for a housing commonly made of EPDM (ethylene-propylene-diene monomer). In the electrical industry, organic insulators with housings made of different kinds of rubber have been employed since more than 20 years in high voltage transmission lines. However, the mechanisms of deterioration of the rubber are still unclear. In fact the progressive deterioration can to produce the unexpected failure of the material. The wide range of mechanical and electrical properties achieved by the polymers cannot be obtained with other type of material. Organic insulators have the advantages of low density, easy handling and good resistance to vandalism. However, environmental agents can damage them. In fact, rain, dust deposition, corona effect and ultraviolet radiation, among others, deteriorate the quality of the polymeric housing employed as watersheds. In the present work we analyse the disentanglement of the crystalline phase in the EPDM by means of the application of an electro-rheological model, recently published. We have performed dynamical mechanical analysis in EPDM samples obtained from commercial insulators. Samples were checked under different doses of irradiation with a low neutron flux. Irradiated sample with the largest crystalline degree exhibits the smallest relaxation time. Cross-linking process developed during the irradiation would appear to have a small effect on the disentanglement of crystals, in contrast to the chain-scission process. (author)

  16. Time structure of charge signals and noise studies of GaAs detectors irradiated by neutrons and protons

    International Nuclear Information System (INIS)

    Braunschweig, W.; Chu, Z.H.; Karpinski, W.; Kubicki, Th.; Lubelsmeyer, K.; Rente, C.; Syben, O.; Tenbusch, F.; Toporowsky, M.; Wittmer, B.; Xiao, W.J.

    1996-01-01

    Semiconductor detectors processed in Aachen using Si GaAs from different manufactures have been irradiated with neutrons (peak energy ∼ 1 MeV) up to 4.0·10 14 n/cm 2 and protons (energy 24 GeV) up to 8.2·10 13 p/cm 2 . All detectors work well after the exposure. The leakage current density at 200 V of detectors made of AXT material increases by a factor of four after the highest neutron fluence and a factor of three after the maximal proton fluence. For the FEW-LC material the leakage current decreases significantly after irradiation. No significant difference can be observed between biased and non-biased detectors during the exposure to neutrons. The equivalent noise charged (ENC) calculated from the noise density spectra agrees well with that extracted from the pedestal width for the different neutron and proton fluences. Before irradiation the charge signals for minimum ionizing particles (MIPs) increase with the peaking time in the range of 40 ns to 2 μs, while this dependence cannot be observed after the exposure to neutrons or protons. The reason for this behaviour is the different time structure of the charge signals before and after irradiation. For AXT material the charge signals for MIPs correspond to 7100 electrons after 4.0·10 14 n/cm 2 and of 4300 electrons after 8.2·10 13 p/cm 2 are obtained. For FEW-LC material the signals at 200 V are reduced from 15700 electrons before irradiation to 6000 electrons after 8.2·10 13 p/cm 2 for this peaking time

  17. Effects of Phosphorus and Harvest Time on Dry Matter Yield, Nitrogen and Phosphorus Contents of Horsegram Macrotyloma uniflorum

    Directory of Open Access Journals (Sweden)

    Omokanye, AT.

    1996-01-01

    Full Text Available A two year field study was conducted at Shika, Northern Nigeria to determine the effects of phosphorus levels (0, 40, 80 and 120 kg P205/ha and harvest times (6, 9, 12 and 15 weeks after planting, WAP on dry matter yield (DM, N and P distribution in plant parts of horsegram (Macrotyloma uniflorum. Leafand stem DM yields (2.8 and 2.3 t/ha were hig-hest (P <0.05 when 80 kg P205/ha was applied. Total DM yields ranged from 1.9 t/ha in the control to 5.1 t/ha at the 80 kg P205/ha treatment. The leaf (2.9 t/ha and stem (2.6 t/ha DM yields were greatest at 12 and 15 WAP respectively. The total DM yields were lowest (2.3 t/ha and highest (5.3 t/ha at 6 and 12 WAP respectively. The application of 80 kg P205/ha when harvested 9 WAP favoured total plant N content. The P content in the herbage increased with increase in P application, and was highest at 6 WAP.

  18. 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)

  19. Incident-angle sensitive neutron detector using scintillating fibers

    International Nuclear Information System (INIS)

    Iguchi, Tetsuo; Kawarabayashi, Jun; Mizuno, Ryoji; Inui, Daisuke; Watanabe, Kenichi; Nishitani, Takeo; Yamauchi, Michinori

    2004-01-01

    Neutron measurement in fusion experimental devices is very important for burning plasma diagnostics and control. In particular, neutron emission profile measurement provides useful information on the profile of ion temperatures and densities as well as the time-dependent neutron yield profile. So far several studies have been made on the neutron emission profile monitor, which are almost based on a large number of neutron threshold detectors or neutron spectrometers combined with a massive multichannel neutron collimator. The detectors can provide line-integrated neutron emissivity along the direction of collimator. Neutron emissivity over a poloidal section of plasma is determined by installing a vertical neutron camera and a horizontal neutron camera. However, one of the most serious problems on this type of system is that the spatial resolution is restricted by the collimator design. The restriction of location to install the massive and heavy collimator system is also a difficult problem for the complicated and tight machine integration. To improve these difficulties, we propose a novel incident-angle sensitive neutron detector using scintillating fibers. In this report, we describe the results on preliminary experiments to confirm the operational principle and basic performance a prototype detector element. (author)

  20. Phenology and yield of strawberry as influenced by planting time and genotypes in a sub tropical region

    International Nuclear Information System (INIS)

    Rahman, M.M.; Islam, N.

    2016-01-01

    Effects of planting time on phenology of five strawberry genotypes Sweet Charlie, Festival, Camarosa, FA 008, and BARI strawberry-1 were evaluated at Bangladesh Agricultural Research Institute in two consecutive years 2009-2010 and 2010-2011. Sweet Charlie took the shorter time to begin flowering, followed by BARI Strawberry-1 and Festival when planted in 1st October. Genotype FA 008 took longer time to flower when planted in 1st December. Days to flowering of all the varieties was found to decrease with the increase in air temperature. Regardless of planting year, the genotype FA 005 followed by Camarosa and Festival, planted on 1st September, exhibited the longest harvest duration, while Sweet Charlie planted on 1st December exhibited the shortest harvest duration in both years. Genotype Festival planted on October yielded fruit with the greatest fruit weight, followed by Sweet Charlie and Camarosa planted on the same date. Plants of FA 008 and BARI Strawberry-1 planted in December produced minimum fruit weight. Maximum number of fruits/plant as well as yield/plant obtained from Sweet Charlie planted in October, while BARI Strawberry-1 planted in December yielded the least. With the use of quadratic equation it was estimated that maximum yield was obtained at ambient temperature 18.5 degree C then it was decreased with the increase of temperature. Strawberry planted in early October was found to be the most suitable in Bangladesh. Among the studied genotypes, Sweet Charlie was found to be superior in yield and early planting, and Camarosa was suitable for late planting. Festival was found less sensitive to planting date. (author)