WorldWideScience

Sample records for beta-delayed neutron emission

  1. Neutron-gamma competition for $\\beta$-delayed neutron emission

    CERN Document Server

    Mumpower, Matthew; Moller, Peter

    2016-01-01

    We present a coupled Quasi-particle Random Phase Approximation and Hauser-Feshbach (QRPA+HF) model for calculating delayed particle emission. This approach uses microscopic nuclear structure information which starts with Gamow-Teller strength distributions in the daughter nucleus, and then follows the statistical decay until the initial available excitation energy is exhausted. Explicitly included at each particle emission stage is $\\gamma$-ray competition. We explore this model in the context of neutron emission of neutron-rich nuclei and find that neutron-gamma competition can lead to both increases and decreases in neutron emission probabilities, depending on the system considered. A second consequence of this formalism is a prediction of more neutrons on average being emitted after $\\beta$-decay for nuclei near the neutron dripline compared to models that do not consider the statistical decay.

  2. Evidence for beta -delayed neutron emission from /sup 31/Mg and /sup 32/Mg

    CERN Document Server

    Zaidins, C S; De Saint-Simon, M; Détraz, C; Epherre-Rey-Campagnolle, Marcelle; Guillemaud, D; Klapisch, Robert; Langevin, M; Naulin, F; Thibault, C; Touchard, F

    1981-01-01

    Investigates the time spectrum of beta -delayed neutron emission from /sup 30-34/Na and their descendants using beta -neutron coincidence detection. The authors have been able to assign an upper limit of 0,4% to the probability of beta -delayed neutron emission, p/sub n/, from the /sup 30/Na daugher isotope /sup 30/Mg. In fitting the time spectra of beta -delayed neutrons from /sup 31/Na and /sup 32/Na, we find a definitive component from subsequent daughter decay as well. This provides evidence for beta -delayed neutron emission from /sup 31/Mg and /sup 32/Mg with P/sub n/ values of the order of 2% for each. (7 refs).

  3. Summary Report of Consultants' Meeting on Beta-Delayed Neutron Emission Evaluation

    International Nuclear Information System (INIS)

    A summary is given of a Consultants' Meeting assembled to assess the viability of a new IAEA Co-ordinated Research Project (CRP) on Beta-delayed neutron emission evaluation. The current status of the field was reviewed, cases in which new measurements are needed were identified and the current theoretical models were examined. The best known cases were selected as standards and were assessed and preliminary best values of the emission probabilities were obtained. The need of such a CRP was strongly agreed. Both the technical discussions and the expected outcome of such a project are described, along with detailed recommendations for its implementation. (author)

  4. Beta-decay rate and beta-delayed neutron emission probability of improved gross theory

    Science.gov (United States)

    Koura, Hiroyuki

    2014-09-01

    A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for

  5. First-forbidden $\\mathbf{\\beta}$-decay rates, energy rates of $\\beta$-delayed neutrons and probability of $\\beta$-delayed neutron emissions for neutron-rich nickel isotopes

    CERN Document Server

    Nabi, Jameel-Un; Iftikhar, Zafar

    2016-01-01

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar $\\beta$-decay rates, energy rate of $\\beta$-delayed neutrons and probability of $\\beta$-delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the $r$-matter flow.

  6. Beta-delayed proton emission in neutron-deficient lanthanide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Wilmarth, P.A.

    1988-09-30

    Forty-two ..beta..-delayed proton precursors with 56less than or equal toZless than or equal to71 and 63less than or equal toNless than or equal to83 were produced in heavy-ion reactions at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decay properties studied at the on-line mass separation facility OASIS. Twenty-five isotopes and eight delayed proton branches were identified for the first time. Delayed proton energy spectra and proton coincident ..gamma..-ray and x-ray spectra were measured for all precursors. In a few cases, proton branching ratios were also determined. The precursor mass numbers were determined by the separator, while the proton coincident x-ray energies provided unambiguous Z identifications. The proton coincident ..gamma..-ray intensities were used to extract final state branching ratios. Proton emission from ground and isomeric states was observed in many cases. The majority of the delayed proton spectra exhibited the smooth bell-shaped distribution expected for heavy mass precursors. The experimental results were compared to statistical model calculations using standard parameter sets. Calculations using Nilsson model/RPA ..beta..-strength functions were found to reproduce the spectral shapes and branching ratios better than calculations using either constant or gross theory ..beta..-strength functions. Precursor half-life predictions from the Nilsson model/RPA ..beta..-strength functions were also in better agreement with the measured half-lives than were gross theory predictions. The ratios of positron coincident proton intensities to total proton intensities were used to determine Q/sub EC/-B/sub p/ values for several precursors near N=82. The statistical model calculations were not able to reproduce the experimental results for N=81 precursors. 154 refs., 82 figs., 19 tabs.

  7. Beta-delayed neutron spectroscopy using trapped radioactive ions

    OpenAIRE

    Yee, Ryan Matthew

    2013-01-01

    A novel technique for beta-delayed neutron spectroscopy has been developed using trapped radioactive ions. The neutron energy spectrum was reconstructed by measuring the time of flight (TOF) of the nuclear recoil following neutron emission, thereby avoiding all the challenges associated with neutron detection such as backgrounds from scattered neutrons and gamma rays and complicated detector-response functions. A proof-of-principle measurement was conducted on 137I+ by delivering ions from a ...

  8. Beta-delayed particle emission from neutron-deficient tellurium, iodine, xenon, cesium and barium isotopes

    International Nuclear Information System (INIS)

    Using 58Ni, 63Cu(58Ni, xp yn) reactions and on-line mass separation the β-delayed proton and α-particle emission from neutron-deficient isotopes with 52113Xe, (protons), 114Cs (protons and α-particles) and 117Ba (protons). Coincidences between positons and β-delayed protons were recorded for 113Xe and 114Cs, yielding Qsub(EC)-Ssub(p) values of 7.92(15) and 8.73(15) MeV, respectively. The results are discussed within the statistical model. (orig.)

  9. Beta delayed emission of a proton by a one-neutron halo nucleus

    OpenAIRE

    Baye, D.; TURSUNOV, E. M.

    2010-01-01

    Some one-neutron halo nuclei can emit a proton in a beta decay of the halo neutron. The branching ratio towards this rare decay mode is calculated within a two-body potential model of the initial core+neutron bound state and final core+proton scattering states. The decay probability per second is evaluated for the $^{11}$Be, $^{19}$C and $^{31}$Ne one-neutron halo nuclei. It is very sensitive to the neutron separation energy.

  10. Beta-delayed proton emission in neutron-deficient lanthanide isotopes

    International Nuclear Information System (INIS)

    Forty-two β-delayed proton precursors with 56≤Z≤71 and 63≤N≤83 were produced in heavy-ion reactions at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decay properties studied at the on-line mass separation facility OASIS. Twenty-five isotopes and eight delayed proton branches were identified for the first time. Delayed proton energy spectra and proton coincident γ-ray and x-ray spectra were measured for all precursors. In a few cases, proton branching ratios were also determined. The precursor mass numbers were determined by the separator, while the proton coincident x-ray energies provided unambiguous Z identifications. The proton coincident γ-ray intensities were used to extract final state branching ratios. Proton emission from ground and isomeric states was observed in many cases. The majority of the delayed proton spectra exhibited the smooth bell-shaped distribution expected for heavy mass precursors. The experimental results were compared to statistical model calculations using standard parameter sets. Calculations using Nilsson model/RPA β-strength functions were found to reproduce the spectral shapes and branching ratios better than calculations using either constant or gross theory β-strength functions. Precursor half-life predictions from the Nilsson model/RPA β-strength functions were also in better agreement with the measured half-lives than were gross theory predictions. The ratios of positron coincident proton intensities to total proton intensities were used to determine Q/sub EC/-B/sub p/ values for several precursors near N=82. The statistical model calculations were not able to reproduce the experimental results for N=81 precursors. 154 refs., 82 figs., 19 tabs

  11. MONSTER: a TOF Spectrometer for beta-delayed Neutron Spetroscopy

    CERN Document Server

    Martinez, T; Castilla, J; Garcia, A R; Marin, J; Martinez, G; Mendoza, E; Santos, C; Tera, F; Jordan, M D; Rubio, B; Tain, J L; Bhattacharya, C; Banerjee, K; Bhattacharya, S; Roy, P; Meena, J K; Kundu, S; Mukherjee, G; Ghosh, T K; Rana, T K; Pandey, R; Saxena, A; Behera, B; Penttila, H; Jokinen, A; Rinta-Antila, S; Guerrero, C; Ovejero, M C; Villamarin, D; Agramunt, J; Algora, A

    2014-01-01

    Beta-delayed neutron (DN) data, including emission probabilities, P-n, and energy spectrum, play an important role in our understanding of nuclear structure, nuclear astrophysics and nuclear technologies. A MOdular Neutron time-of-flight SpectromeTER (MONSTER) is being built for the measurement of the neutron energy spectra and branching ratios. The TOF spectrometer will consist of one hundred liquid scintillator cells covering a significant solid angle. The MONSTER design has been optimized by using Monte Carlo (MC) techniques. The response function of the MONSTER cell has been characterized with mono-energetic neutron beams and compared to dedicated MC simulations.

  12. Characterization of a neutron-beta counting system with beta-delayed neutron emitters

    OpenAIRE

    Agramunt Ros, Jorge; Taín, J. L.; Gómez Hornillos, María Belén; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere; Pretel Sánchez, Carme; Riego Pérez, Albert; Tarifeño Saldivia, Ariel Esteban

    2016-01-01

    A new detection system for the measurement of beta-delayed neutron emission probabilities has been characterized using fission products with well known ß-delayed neutron emission properties. The setup consists of BELEN-20, a 4p neutron counter with twenty 3He proportional tubes arranged inside a large polyethylene neutron moderator, a thin Si detector for ß counting and a self-triggering digital data acquisition system. The use of delayed-neutron precursors with different neutron emission win...

  13. $\\beta$-decay and $\\beta$-delayed Neutron Emission Measurements at GSI-FRS Beyond N=126, for r-process Nucleosynthesis

    CERN Document Server

    Caballero-Folch, R; Cortès, G; Taín, J L; Agramunt, J; Algora, A; Ameil, F; Ayyad, Y; Benlliure, J; Bowry, M; Calviño, F; Cano-Ott, D; Davinson, T; Dillmann, I; Estrade, A; Evdokimov, A; Faestermann, T; Farinon, F; Galaviz, D; García-Ríos, A; Geissel, H; Gelletly, W; Gernhäuser, R; Gómez-Hornillos, M B; Guerrero, C; Heil, M; Hinke, C; Knöbel, R; Kojouharov, I; Kurcewicz, J; Kurz, N; Litvinov, Y; Maier, L; Marganiec, J; Marta, M; Martínez, T; Montes, F; Mukha, I; Napoli, D R; Nociforo, C; Paradela, C; Pietri, S; Podolyák, Zs; Prochazka, A; Rice, S; Riego, A; Rubio, B; Schaffner, H; Scheidenberger, C; Smith, K; Sokol, E; Steiger, K; Sun, B; Takechi, M; Testov, D; Weick, H; Wilson, E; Winfield, J S; Wood, R; Woods, P J; Yeremin, A

    2014-01-01

    New measurements of very exotic nuclei in the neutron-rich region beyond N=126 have been performed at the GSI facility with the fragment separator (FRS). The aim of the experiment is to determine half-lives and beta-delayed neutron emission branching ratios of isotopes of Hg, Tl and Pb in this region. This contribution summarizes final counting statistics for identification and for implantation, as well as the present status of the data analysis of the half-lives. In summary, isotopes of Pt, Au, Hg, Ti, Pb, Bi, Po, At, Rn and Fr were clearly identified and several of them (Hg208-211, Tl211-215, Pb214-218) were implanted with enough statistics to determine their half-lives. About half of them are expected to be neutron emitters, in such cases it will become possible to obtain the neutron emission probabilities, P-n.

  14. Evidence for Gamow-Teller Decay of 78Ni Core from Beta-Delayed Neutron Emission Studies

    Science.gov (United States)

    Madurga, M.; Paulauskas, S. V.; Grzywacz, R.; Miller, D.; Bardayan, D. W.; Batchelder, J. C.; Brewer, N. T.; Cizewski, J. A.; Fijałkowska, A.; Gross, C. J.; Howard, M. E.; Ilyushkin, S. V.; Manning, B.; Matoš, M.; Mendez, A. J.; Miernik, K.; Padgett, S. W.; Peters, W. A.; Rasco, B. C.; Ratkiewicz, A.; Rykaczewski, K. P.; Stracener, D. W.; Wang, E. H.; Wolińska-Cichocka, M.; Zganjar, E. F.

    2016-08-01

    The β -delayed neutron emission of Ga,8483 isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to 78Ni core-excited states in Ge,8483 favored by shell effects. We developed shell model calculations in the proton f p g9 /2 and neutron extended f p g9 /2+d5 /2 valence space using realistic interactions that were used to understand measured β -decay lifetimes. We conclude that enhanced, concentrated β -decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β -delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models.

  15. Evidence for Gamow-Teller Decay of ^{78}Ni Core from Beta-Delayed Neutron Emission Studies.

    Science.gov (United States)

    Madurga, M; Paulauskas, S V; Grzywacz, R; Miller, D; Bardayan, D W; Batchelder, J C; Brewer, N T; Cizewski, J A; Fijałkowska, A; Gross, C J; Howard, M E; Ilyushkin, S V; Manning, B; Matoš, M; Mendez, A J; Miernik, K; Padgett, S W; Peters, W A; Rasco, B C; Ratkiewicz, A; Rykaczewski, K P; Stracener, D W; Wang, E H; Wolińska-Cichocka, M; Zganjar, E F

    2016-08-26

    The β-delayed neutron emission of ^{83,84}Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to ^{78}Ni core-excited states in ^{83,84}Ge favored by shell effects. We developed shell model calculations in the proton fpg_{9/2} and neutron extended fpg_{9/2}+d_{5/2} valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models. PMID:27610848

  16. Characterization of a neutron–beta counting system with beta-delayed neutron emitters

    OpenAIRE

    Agramunt, J.; Tain, J.L.; Gómez-Hornillos, M. B.; GARCIA A. R.; Albiol, F; Algora, A.; Caballero-Folch, R.; CALVIÑO F.; Cano-Ott, D.; Cortés, G.; Domingo-Pardo, C.; Eronen, Tommi; Gelletly, W.; Gorelov, Dmitry; Gorlychev, V.

    2016-01-01

    A new detection system for the measurement of beta-delayed neutron emission probabilities has been characterized using fission products with well known β-delayed neutron emission properties. The setup consists of BELEN-20, a 4π neutron counter with twenty 3He proportional tubes arranged inside a large polyethylene neutron moderator, a thin Si detector for β counting and a selftriggering digital data acquisition system. The use of delayed-neutron precursors with different neutron emis...

  17. New Beta-delayed Neutron Measurements in the Light-mass Fission Group

    International Nuclear Information System (INIS)

    A new accurate determination of beta-delayed neutron emission probabilities from nuclei in the low mass region of the light fission group has been performed. The measurements were carried out using the BELEN 4π neutron counter at the IGISOL-JYFL mass separator in combination with a Penning trap. The new results significantly improve the uncertainties of neutron emission probabilities for 91Br, 86As, 85As, and 85Ge nuclei

  18. Beta-delayed proton emission from $^{21}$Mg

    CERN Document Server

    Lund, M V; Briz, J A; Cederkäll, J; Fynbo, H O U; Jensen, J H; Jonson, B; Laursen, K L; Nilsson, T; Perea, A; Pesudo, V; Riisager, K; Tengblad, O

    2015-01-01

    Beta-delayed proton emission from $^{21}$Mg has been measured at ISOLDE, CERN, with a detection setup including particle identification capabilities. $\\beta$-delayed protons with center of mass energies between 0.39$\\,$MeV and 7.2$\\,$MeV were measured and used to determine the half life of $^{21}$Mg as $118.6\\pm 0.5\\,$ms. From a line shape fit of the $\\beta p$ branches we extract spectroscopic information about the resonances of $^{21}$Na. Finally an improved interpretation of the decay scheme in accordance with the results obtained in reaction studies is presented.

  19. First measurement of several $\\beta$-delayed neutron emitting isotopes beyond N=126

    CERN Document Server

    Caballero-Folch, R; Agramunt, J; Algora, A; Ameil, F; Arcones, A; Ayyad, Y; Benlliure, J; Borzov, I N; Bowry, M; Calvino, F; Cano-Ott, D; Cortés, G; Davinson, T; Dillmann, I; Estrade, A; Evdokimov, A; Faestermann, T; Farinon, F; Galaviz, D; García, A R; Geissel, H; Gelletly, W; Gernhäuser, R; Gómez-Hornillos, M B; Guerrero, C; Heil, M; Hinke, C; Knöbel, R; Kojouharov, I; Kurcewicz, J; Kurz, N; Litvinov, Y; Maier, L; Marganiec, J; Marketin, T; Marta, M; Martínez, T; Martínez-Pinedo, G; Montes, F; Mukha, I; Napoli, D R; Nociforo, C; Paradela, C; Pietri, S; Podolyák, Zs; Prochazka, A; Rice, S; Riego, A; Rubio, B; Schaffner, H; Scheidenberger, Ch; Smith, K; Sokol, E; Steiger, K; Sun, B; Taín, J L; Takechi, M; Testov, D; Weick, H; Wilson, E; Winfield, J S; Wood, R; Woods, P; Yeremin, A

    2015-01-01

    The $\\beta$-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with $\\beta$-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb and Bi in the mass region N$\\gtrsim$126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the $\\beta$-decay strength distribution. In doing so, it provides important constraints to global theoretical models currently used in $r$-process nucleosynthesis.

  20. Beta-delayed proton emission from {sup 21}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Lund, M.V.; Fynbo, H.O.U.; Jensen, J.H.; Laursen, K.L.; Riisager, K. [Aarhus University, Department of Physics and Astronomy, Aarhus C (Denmark); Borge, M.J.G. [CSIC, Instituto de Estructura de la Materia, Madrid (Spain); CERN, ISOLDE, PH Department, Geneva 23 (Switzerland); Briz, J.A.; Perea, A.; Pesudo, V.; Tengblad, O. [CSIC, Instituto de Estructura de la Materia, Madrid (Spain); Cederkaell, J. [Lund University, Department of Nuclear Physics, Lund (Sweden); Jonson, B.; Nilsson, T. [Chalmers University of Technology, Department of Fundamental Physics, Goeteborg (Sweden)

    2015-09-15

    Beta-delayed proton emission from {sup 21}Mg has been measured at ISOLDE, CERN, with a detection setup consisting of two charged-particle telescopes surrounding the decay point. Altogether 27 βp branches were measured with center-of-mass energies between 0.4-7.2 MeV. Seven new βp branches were observed. Beta-delayed protons were used to determine the half-life of {sup 21}Mg as 118.6 ± 0.5 ms. From a line shape fit of the βp branches we extract the widths, spins, and parities of the resonances of {sup 21}Na. An improved interpretation of the decay scheme in accordance with the results obtained in reaction studies is presented. (orig.)

  1. $\\beta$-delayed neutron spectroscopy of $^{130-132}$ Cd isotopes with the ISOLDE decay station and the VANDLE array

    CERN Multimedia

    We propose to use the new ISOLDE decay station and the neutron detector VANDLE to measure the $\\beta$-delayed neutron emission of N=82-84 $^{130-132}$Cd isotopes. The large delayed neutron emission probability observed in a previous ISOLDE measurement is indicative of the Gamow-Teller transitions due to the decay of deep core neutrons. Core Gamow-Teller decay has been experimentally proven in the $^{78}$Ni region for the N>50 nuclei using the VANDLE array. The spectroscopic measurement of delayed neutron emission along the cadmium isotopic chain will allow us to track the evolution of the single particle states and the shell gap.

  2. Total Absorption Gamma-Ray Spectroscopy of 87Br, 88Br and 94Rb Beta-Delayed Neutron Emitters

    CERN Document Server

    Valencia, E; Algora, A; Agramunt, J; Rubio, B; Rice, S; Gelletly, W; Regan, P; Zakari-Issoufou, A -A; Fallot, M; Porta, A; Rissanen, J; Eronen, T; Aysto, J; Batist, L; Bowry, M; Bui, V M; Caballero-Folch, R; Cano-Ott, D; Elomaa, V -V; Estevez, E; Farrelly, G F; Garcia, A R; Gomez-Hornillos, B; Gorlychev, V; Hakala, J; Jordan, M D; Jokinen, A; Kolhinen, V S; Kondev, F G; Martinez, T; Mendoza, E; Moore, I; Penttila, H; Podolyak, Zs; Reponen, M; Sonnenschein, V; Sonzogni, A A

    2016-01-01

    We investigate the decay of 87Br, 88Br and 94Rb using total absorption gamma-ray spectroscopy. These important fission products are beta-delayed neutron emitters. Our data show considerable gamma-intensity, so far unobserved in high-resolution gamma-ray spectroscopy, from states at high excitation energy. We also find significant differences with the beta intensity that can be deduced from existing measurements of the beta spectrum. We evaluate the impact of the present data on reactor decay heat using summation calculations. Although the effect is relatively small it helps to reduce the discrepancy between calculations and integral measurements of the photon component for 235U fission at cooling times in the range 1 to 100 s. We also use summation calculations to evaluate the impact of present data on reactor antineutrino spectra. We find a significant effect at antineutrino energies in the range of 5 to 9 MeV. In addition, we observe an unexpected strong probability for gamma emission from neutron unbound s...

  3. Studies of $\\beta$-delayed two-proton emission : The cases of $^{31}$Ar and $^{35}$Ca

    CERN Multimedia

    Riisager, K; Jokinen, A; Canchel, G; Heinz, A M; Jonson, B N G; Dominguez reyes, R R; Koldste, G T; Fraile prieto, L M; Nilsson, T; Audirac, L L

    2008-01-01

    We propose to perform detailed studies of the decays of the two dripline nuclei $^{31}$Ar and $^{35}$Ca. This will allow an in-depth study in the process of $\\beta$-delayed two-proton emission ($\\beta$2p); as well as provide important information on resonances in $^{30}$S and $^{34}$Ar relevant for the astrophysical rp-process.

  4. Systematic trends in beta-delayed particle emitting nuclei: The case of βpα emission from 21Mg

    Directory of Open Access Journals (Sweden)

    M.V. Lund

    2015-11-01

    Full Text Available We have observed β+-delayed α and pα emission from the proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The assignments were cross-checked with a time distribution analysis. This is the third identified case of βpα emission. We discuss the systematic of beta-delayed particle emission decays, show that our observed decays fit naturally into the existing pattern, and argue that the patterns are to a large extent caused by odd–even effects.

  5. $\\beta$-delayed neutrons from oriented $^{137,139}$I and $^{87,89}$Br nuclei

    CERN Multimedia

    We propose a world-first measurement of the angular distribution of $\\beta$‐delayed n and $\\gamma$-radiation from oriented $^{137, 139}$I and $^{87,89}$Br nuclei, polarised at low temperature at the NICOLE facility. $\\beta$­-delayed neutron emission is an increasingly important decay mechanism as the drip line is approached and its detailed understanding is essential to phenomena as fundamental as the r‐process and practical as the safe operation of nuclear power reactors. The experiments offer sensitive tests of theoretical input concerning the allowed and first­‐forbidden $\\beta$‐decay strength, the spin-density of neutron emitting states and the partial wave barrier penetration as a function of nuclear deformation. In $^{137}$I and $^{87}$Br the decay feeds predominantly the ground state of the daughters $^{136}$Xe and $^{86}$Kr whereas in $^{139}$I and $^{89}$Br we will explore the use of n-$\\gamma$- coincidence to study neutron transitions to the first and second excited states in the daughters...

  6. $\\beta$-delayed neutrons from oriented $^{137,139}$I and $^{87,89}$Br nuclei

    CERN Document Server

    Grzywacz, Robert; Stone, Nicholas; Köster, Ulli; Singh, Barlaj; Bingham, Carrol; Gaulard, S; Kolos, Karolina; Madurga, Miguel; Nikolov, J; Otsubo, T; Roccia, S; Veskovic, Miroslav; Walker, Phil; Walters, William

    2013-01-01

    We propose a world-­‐first measurement of the angular distribution of $\\beta$-­‐delayed n and $\\gamma$- radiation from oriented $^{137, 139}$I and $^{87,89}$Br nuclei, polarised at low temperature at the NICOLE facility. $\\beta$-­‐delayed neutron emission is an increasingly important decay mechanism as the drip line is approached and its detailed understanding is essential to phenomena as fundamental as the r‐process and practical as the safe operation of nuclear power reactors. The experiments offer sensitive tests of theoretical input concerning the allowed and first-­‐forbidden $\\beta$‐decay strength, the spin-­‐density of neutron emitting states and the partial wave barrier penetration as a function of nuclear deformation. In $^{137}$I and $^{87}$Br the decay feeds predominantly the ground state of the daughters $^{136}$Xe and $^{86}$Kr whereas in $^{139}$I and $^{89}$Br we will explore the use of n-$\\gamma$- coincidence to study neutron transitions to the first and second excited state...

  7. Determination of uranium in urine samples of fuel element fabrication workers by beta-delayed neutron counting

    Science.gov (United States)

    Gabelmann, H.; Lerch, M.; Kratz, K.-L.; Rudolph, W.

    1984-06-01

    Within the health physics examination of fuel element fabrication workers, the control of uranium incorporation is of importance. This is commonly performed by the determination of the alpha activity concentration of uranium excreted in the urine. However, since the chemical separation procedure and the preparation of alpha-counting samples are complicated and time-consuming, this method may imply restrictions on the routine control of large numbers of persons. Therefore, we have investigated the applicability of measuring the beta-delayed neutrons from thermal neutron induced fission of the 235U in the urine samples. The uranium was separated by coprecipitation with Fe(OH) 3 from the urine samples and irradiated in a rabbit system of the Mainz TRIGA reactor. The neutrons were counted with a 3He long counter. The detection limit of 0.3 to 0.9 pCi 1 -1 is comparable to that of alpha spectrometry, but the time required for one sample, from preparation to data evaluation is less than 25 min.

  8. Total absorption γ-ray spectroscopy of beta delayed neutron emitters

    Science.gov (United States)

    Valencia, E.; Algora, A.; Tain, J. L.; Rice, S.; Agramunt, J.; Zakari-Issoufou, A.-A.; Porta, A.; Fallot, M.; Jordan, M. D.; Molina, F.; Estevez, E.; Bowry, M.; Bui, V. M.; Caballero-Folch, R.; Cano-Ott, D.; Eloma, V.; Eronen, T.; Garcia, A.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Kondev, F. G.; Martinez, T.; Moore, I.; Rissanen, J.; Ńystö, J.; Penttilä, H.; Kankainen, A.; Rubio, B.; Gelletly, W.; Perez, A.; Podolyak, Zs.; Regan, P. H.; Farrelly, G. F.; Weber, C.; Mendoza, E.; Igisol People

    2013-06-01

    Preliminary results of the data analysis of the beta decay of 94Rb using a novel - segmented- total absorption spectrometer are shown in this contribution. This result is part of a systematic study of important contributors to the decay heat problem in nuclear reactors. In this particular case the goal is to determine the beta intensity distribution below the neutron separation energy and the gamma/beta competition above.

  9. Beta-delayed fission probabilities of transfermium nuclei, involved in the r-process

    Science.gov (United States)

    Panov, I.; Lutostansky, Yu; Thielemann, F.-K.

    2016-01-01

    For the nucleosynthesis of heavy and superheavy nuclei fission becomes very important when the r-process runs in a very high neutron density environment. In part, fission is responsible for the formation of heavy nuclei due to the inclusion of fission products as new seed nuclei (fission cycling). More than that, beta-delayed fission, along with spontaneous fission, is responsible in the late stages of the r-process for the suppression of superheavy element yields. For beta-delayed fission probability calculations a model description of the beta-strength- functions is required. Extended theoretical predictions for astro-physical applications were provided long ago, and new predictions also for superheavy nuclei with uptodate nuclear input are needed. For the further extension of data to heavier transactinides the models of strength- functions should be modified, taking into account more complicated level schemes. In our present calculations the strength-function model is based on the quasi-particle approximation of Finite Fermi Systems Theory. The probabilities of beta-delayed fission and beta-delayed neutron emission are calculated for some transfermium neutron-rich nuclei, and the influence of beta-delayed fission upon superheavy element formation is discussed.

  10. Search for $\\beta$-delayed protons from $^{11}$Be

    CERN Multimedia

    $\\beta$-delayed proton emission from $^{11}$Be will be a very rare process. It is believed to decay directly into continuum states. This would imply that it will be a sensitive probe of the halo structure of the one-neutron halo nucleus $^{11}$Be. We propose to improve existing (unpublished) limits on this decay mode by two orders of magnitude. Our earlier experience at ISOLDE indicates that the required intensity and purity of the source can be obtained. The branching ratio will be measured by counting the number of $^{10}$Be atoms produced via accelerator mass spectrometry.

  11. Extension of the T{sub z} = {minus}3/2, A = 4n + 1 series of beta-delayed proton emitters to {sup 65}Se and {sup 73}Sr, and low energy beta-delayed proton emission from the T{sub z} = {minus}3/2, A = 4n + 3 nucleus {sup 23}Al

    Energy Technology Data Exchange (ETDEWEB)

    Batchelder, J.C.

    1993-12-01

    The series of known Tz = {minus}3/2, A = 4n + 1 nuclei has been extended to include the previously undiscovered isotopes {sup 65}Se and {sup 73}Sr, through the observation of beta-delayed proton emission via the isobaric analog state (IAS) of the beta-daughter (emitter). Due to the relatively large proton energies involved, these experiments were conducted using standard Si-Si {Delta}E-E telescopes. Beta-delayed protons arising from {sup 65}Se have been observed at an energy (laboratory) of 3.55 {plus_minus} 0.03 MeV, corresponding to the decay of the T = 3/2 isobaric analog state in {sup 65}As to the ground state of {sup 64}Ge. Similarly, beta-delayed protons from {sup 73}Sr at an energy of 3.75 {plus_minus} 0.04 MeV have been observed, corresponding to decay of the T = 3/2 isobaric analog state in {sup 73}Rb to the ground state of {sup 72}Kr. From the energies of these proton transitions, an improved prediction of the mass excesses of the two parent nuclei ({sup 65}Se and {sup 73}Sr) is made through the use of a Coulomb displacement formula. These predictions are {minus}33.41 {plus_minus} 0.26 and {minus}31.87 {plus_minus} 0.24 MeV for {sup 65}Se and {sup 73}Sr, respectively. Studies of low energy (down to {approximately}200 keV) beta-delayed protons from {sup 23}Al necessitated that a particle identification telescope with a low energy threshold for observation and identification of protons be developed. {sup 23}Al is of interest because of its role in the breakout of the hot CNO cycle leading to the astrophysical rp process.

  12. Beta-decay half-lives and beta-delayed neutron emisison probabilities of nuclei in the region A. 110, relevant for the r-process

    Energy Technology Data Exchange (ETDEWEB)

    Moller, Peter [Los Alamos National Laboratory; Pereira, J [MSU; Hennrich, S [MSU; Aprahamian, A [UNIV OF NOTRE DAME; Arndt, O [GERMANY; Becerril, A [MSU; Elliot, T [MSU; Estrade, A [MSU; Galaviz, D [MSU; Kessler, R [UNIV MAINZ; Kratz, K - L [GERMANY; Lorusso, G [MSU; Mantica, P F [MSU; Matos, M [MSU; Montes, F [MSU; Pfeiffer, B [UNIV MAINZ; Schatz, F [MSU; Schnorrenberger, L [GERMANY; Smith, E [MSU; Stolz, A [MSU; Quinn, M [UNIV OF NOTRE DAME; Walters, W B [UNIV OF MARYLAND; Wohr, A [UNIV OF NOTRE DAME

    2009-01-01

    Measurements of the {beta}-decay properties of A {approx}< 110 r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory, at Michigan State University. {beta}-decay half-lives for {sup 105}Y, {sup 106,107}Zr and {sup 108,111}Mo, along with ,B-delayed neutron emission probabilities of 104Y, 109,11OMo and upper limits for 105Y, 103-107Zr and 108,111 Mo have been measured for the first time. Studies on the basis of the quasi-random phase approximation are used to analyze the ground-state deformation of these nuclei.

  13. Study of multi-neutron emission in the $\\beta$-decay of $^{11}$Li

    CERN Multimedia

    A new investigation of neutron emission in the $\\beta$-decay of $^{11}$Li is proposed. The principal goal of this study will be to directly measure, for the first time for any system, two $\\beta$-delayed neutrons in coincidence and determine the energy and angular correlations. This will be possible using liquid scintillator detectors, capable of distinguishing between neutrons and ambient $\\gamma$ and cosmic-rays, coupled to a new digital electronics and acquisition system. In parallel, a considerably more refined picture of the single-neutron emission will be obtained.

  14. Experimental observation of $\\beta$-delayed neutrons from $^{9}$Li as a way to study short-pulse laser-driven deuteron production

    CERN Document Server

    Favalli, Andrea; Henzlova, Daniela; Falk, Katerina; Croft, Stephen; Gautier, Donald C; Ianakiev, Kiril D; Iliev, Metodi; Palaniyappan, Sasikumar; Roth, Markus; Fernandez, Juan C; Swinhoe, Martyn T

    2016-01-01

    A short-pulse laser-driven deuteron beam is generated in the relativistic transparency regime and aimed at a beryllium converter to generate neutrons at the TRIDENT laser facility. These prompt neutrons have been used for active interrogation to detect nuclear materials, the first such demonstration of a laser-driven neutron source. During the experiments, delayed neutrons from $^9$Li decay was observed. It was identified by its characteristic half-life of 178.3 ms. Production is attributed to the nuclear reactions $^9$Be(d,2p)$^9$Li and $^9$Be(n,p)$^9$Li inside the beryllium converter itself. These reactions have energy thresholds of 18.42 and 14.26 MeV respectively, and we estimate the (d,2p) reaction to be the dominant source of $^9$Li production. Therefore, only the higher-energy portion of the deuteron spectrum contributes to the production of the delayed neutrons. It was observed that the delayed-neutron yield decreases with increasing distance between the converter and the deuteron source. This behavio...

  15. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    International Nuclear Information System (INIS)

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31Cl, 27P and 28P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31Cl and 27P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31Cl were shown to be from the decay of 25Si. In 27P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17Ne and 33Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17Ne and 33Ar were resolved

  16. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ognibene, T.J. [Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.

    1996-03-01

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of {sup 31}Cl, {sup 27}P and {sup 28}P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas {Delta}E-gas {Delta}E-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in {sup 31}Cl and {sub 27}P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of {sup 31}Cl were shown to be from the decay of {sup 25}Si. In {sup 27}P, two proton groups at 459 {+-} 14 keV and 610 {+-} 11 keV, with intensities of 7 {+-} 3% and 92 {+-} 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the {beta}-decay of {sup 28}P, at 1,444 {+-} 12 keV with a 1.7 {+-} 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, {sup 17}Ne and {sup 33}Ar, were studied. A new proton group with energy 729 {+-} 15 keV was observed following the beta-decay of {sup 17}Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from {sup 17}Ne and {sup 33}Ar were resolved.

  17. Fission neutron statistical emission

    International Nuclear Information System (INIS)

    The statistical model approach FINESSE (FIssion NEutronS' Statistical Emission) for the description of fission neutron multiplicities, energy spectra and angular distributions is described. Based on an extended Weisskopf ansatz and on a realistic temperature distribution it provides a fragment mass number dependent description of fission neutron data. Model parameters (optical potential, n/γ competition) were fixed on the basis of the 252Cf(sf) (nuclear data standard). Combined with a phenomenological fission model for predicting relevant fragment data as function of asymmetry. FINESSE can be applied to any fission reaction of actinides in the Th-Cf region without further parameter adjustment. Results are presented for 252Cf(sf) and neutron induced fission of 235U, 239Pu, 232Th. Effects of multiple-chance fission are discussed for 232Th(n,xnf) reacation. (author). 46 refs, 11 figs

  18. Modeling the Production of Beta-Delayed Gamma Rays for the Detection of Special Nuclear Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hall, J M; Pruet, J A; Brown, D A; Descalle, M; Hedstrom, G W; Prussin, S G

    2005-02-14

    The objective of this LDRD project was to develop one or more models for the production of {beta}-delayed {gamma} rays following neutron-induced fission of a special nuclear material (SNM) and to define a standardized formatting scheme which will allow them to be incorporated into some of the modern, general-purpose Monte Carlo transport codes currently being used to simulate inspection techniques proposed for detecting fissionable material hidden in sea-going cargo containers. In this report, we will describe a Monte Carlo model for {beta}-delayed {gamma}-ray emission following the fission of SNM that can accommodate arbitrary time-dependent fission rates and photon collection histories. The model involves direct sampling of the independent fission yield distributions of the system, the branching ratios for decay of individual fission products and spectral distributions representing photon emission from each fission product and for each decay mode. While computationally intensive, it will be shown that this model can provide reasonably detailed estimates of the spectra that would be recorded by an arbitrary spectrometer and may prove quite useful in assessing the quality of evaluated data libraries and identifying gaps in the libraries. The accuracy of the model will be illustrated by comparing calculated and experimental spectra from the decay of short-lived fission products following the reactions {sup 235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f). For general-purpose transport calculations, where a detailed consideration of the large number of individual {gamma}-ray transitions in a spectrum may not be necessary, it will be shown that a simple parameterization of the {gamma}-ray source function can be defined which provides high-quality average spectral distributions that should suffice for calculations describing photons being transported through thick attenuating media. Finally, a proposal for ENDF-compatible formats that describe each of the models and

  19. Recent activities for β-decay half-lives and β-delayed neutron emission of very neutron-rich isotopes

    International Nuclear Information System (INIS)

    Beta-delayed neutron (βn) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material β-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure βn-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 β-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 β-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of β-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and theoretical models

  20. First observation of $\\beta$-delayed $\\gamma$-proton decay in the $T_z$ = -2, $^{56}$Zn nucleus

    CERN Document Server

    Orrigo, S E A; Fujita, Y; Blank, B; Gelletly, W; Agramunt, J; Algora, A; Ascher, P; Bilgier, B; Cáceres, L; Cakirli, R B; Fujita, H; Ganioğlu, E; Gerbaux, M; Giovinazzo, J; Grévy, S; Kamalou, O; Kozer, H C; Kucuk, L; Kurtukian-Nieto, T; Molina, F; Popescu, L; Rogers, A M; Susoy, G; Stodel, C; Suzuki, T; Tamii, A; Thomas, J C

    2014-01-01

    We report on the first experimental observation of a very exotic decay mode at the proton drip-line, the $\\beta$-delayed $\\gamma$-proton decay, clearly seen in the $\\beta$ decay of the $T_z$ = -2, $^{56}$Zn nucleus. The $^{56}$Zn half-life and decay scheme have been determined. The decay proceeds by $\\beta$-delayed proton emission and $\\beta$-delayed $\\gamma$ de-excitation. The exotic $\\beta$-delayed $\\gamma$-proton emission was also detected in three cases. It affects the usual determination of the Gamow-Teller (GT) strength. Absolute Fermi and GT strengths have been deduced. Evidence for fragmentation of the Fermi strength due to isospin mixing is found.

  1. Neutron emission prior to fission

    International Nuclear Information System (INIS)

    In recent years, many groups have measured neutrons and light charged particles in coincidence with fission fragments in heavy ion reactions. In most cases, particles emitted with an energy spectrum and angular distribution characteristic of that of compound nucleus evaporation have been measured in excess of statistical model predictions. They have chosen to investigate this effect in detail by studying neutron emission in the 158Er composite system. The advantage of this system is that it can be produced by a variety of projectile target combinations. They have chosen four combinations which form 158Er with similar critical angular momenta but varying excitation energy. The rationale is to form the same system with different neutron emission times; if the enhanced neutrons are being emitted during the fission process, the different emission time scales might possibly be used to time the fission process. In addition, they impose an additional constraint - that they have a significant fission barrier for most of the partial waves involved in the fission process. The reactions they have selected are 16O + 142Nd (207 MeV beam energy), 24Mg + 134Ba (180 MeV), 32S + 126Te (180 MeV), 50Ti + 108Pd (216 MeV)

  2. Neutron-emission measurements at a white neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Robert C [Los Alamos National Laboratory

    2010-01-01

    Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

  3. Observation of Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay

    CERN Document Server

    Schwartz, S B; Bennett, M B; Liddick, S N; Perez-Loureiro, D; Bowe, A; Chen, A A; Chipps, K A; Cooper, N; Irvine, D; McNeice, E; Montes, F; Naqvi, F; Ortez, R; Pain, S D; Pereira, J; Prokop, C; Quaglia, J; Quinn, S J; Sakstrup, J; Santia, M; Shanab, S; Simon, A; Spyrou, A; Thiagalingam, E

    2015-01-01

    Background: The Doppler broadening of $\\gamma$-ray peaks due to nuclear recoil from $\\beta$-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using $\\beta$-delayed proton emission or applied to a recoil heavier than $A=10$. Purpose: To test and apply this Doppler broadening method using $\\gamma$-ray peaks from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Methods: A fast beam of $^{26}$P was implanted into a planar Ge detector, which was used as a $^{26}$P $\\beta$-decay trigger. The SeGA array of high-purity Ge detectors was used to detect $\\gamma$ rays from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Results: Radiative Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613 keV $\\gamma$-ray line for which the proton energies were previously known. The 1776 keV $\\gamma$ ray de-exciting the 2720 keV $^{25}$Al level was observed...

  4. Beta-delayed gamma decay of 26P: Possible evidence of a proton halo

    CERN Document Server

    Pérez-Loureiro, D; Bennett, M B; Liddick, S N; Bowe, A; Brown, B A; Chen, A A; Chipps, K A; Cooper, N; Irvine, D; McNeice, E; Montes, F; Naqvi, F; Ortez, R; Pain, S D; Pereira, J; Prokop, C J; Quaglia, J; Quinn, S J; Sakstrup, J; Santia, M; Schwartz, S B; Shanab, S; Simon, A; Spyrou, A; Thiagalingam, E

    2016-01-01

    Background: Measurements of $\\beta$ decay provide important nuclear structure information that can be used to probe isospin asymmetries and inform nuclear astrophysics studies. Purpose: To measure the $\\beta$-delayed $\\gamma$ decay of $^{26}$P and compare the results with previous experimental results and shell-model calculations. Method: A $^{26}$P fast beam produced using nuclear fragmentation was implanted into a planar germanium detector. Its $\\beta$-delayed $\\gamma$-ray emission was measured with an array of 16 high-purity germanium detectors. Positrons emitted in the decay were detected in coincidence to reduce the background. Results: The absolute intensities of $^{26}$P $\\beta$-delayed $\\gamma$-rays were determined. A total of six new $\\beta$-decay branches and 15 new $\\gamma$-ray lines have been observed for the first time in $^{26}$P $\\beta$-decay. A complete $\\beta$-decay scheme was built for the allowed transitions to bound excited states of $^{26}$Si. $ft$ values and Gamow-Teller strengths were a...

  5. $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with radioactive At beams

    CERN Multimedia

    We propose to study the $\\beta$-delayed fission, laser spectroscopy and radioactive decay of the newly available pure beams of neutron-deficient and neutron-rich astatine (Z=85) isotopes. The fission probability and the fission fragment distribution of the even-even isotopes $^{194,196}$Po following the $\\beta$-decay of the isotopes $^{194,196}$At will be studied with the Windmill setup. In-source laser spectroscopy will be performed on the entire astatine isotopic chain, using a combination of the Windmill setup, ISOLTRAP MR-ToF and ISOLDE Faraday. Radioactive decay data will be acquired at the Windmill setup throughout those studies and contribute to the global understanding of the phenomenon of shape coexistence in the neutron-deficient lead region.

  6. Physics of neutron emission in fission

    International Nuclear Information System (INIS)

    The document contains the proceedings of the IAEA Consultants' Meeting on the Physics of Neutron Emission in Fission, Mito City (Japan), 24-27 May 1988. Included are the conclusions and recommendations reached at the meeting and the papers presented by the meeting participants. These papers cover the following topics: Energy dependence of the number of fission neutrons ν-bar (3 papers), multiplicity distribution of fission neutrons (3 papers), competition between neutron and γ-ray emission (4 papers), the fission neutron yield in resonances (2 papers) and the energy spectrum of fission neutrons in experiment (9 papers), theory (4 papers) and evaluation (1 paper). A separate abstract was prepared for each of these papers. Refs, figs and tabs

  7. The Mechanism of $\\beta$-Delayed Two-Proton Emission

    CERN Multimedia

    2002-01-01

    The nucleus $^{31}$Ar seems to be the most prolific ${\\beta}$-2p precursor known to date and is at the same time the one with the largest production yields at ISOLDE, where the most sensitive experiments can be done. Our purpose with this experiment is to study the ${\\beta}$-2p branches in detail, search for ${\\beta}$-3p events, place them in the decay scheme and obtain information on the decay mechanism for ${\\beta}$-2p via the energy distribution and the angular correlation between the two protons. As a by product we shall also resolve existing inconsistencies in the level scheme.\\\\ \\\\ The nucleus $^{31}$Ar, produced in a cold plasma ion source unit by the impact of a 1 GeV proton beam of 0.5 Hz frequency, had an average yield over one week of 1.5 $^{31}$Ar atoms/s. The beam passed through the central hole of an annular Si detector ($\\Omega$ = 4.3~\\%) and stopped in a thin carbon foil tilted 45$^o$ with respect to the beam direction. A 70~\\% coaxial HPGe-detector ($\\Omega$~=~7.4~\\%) was located opposite to ...

  8. Emission processes in quiescent neutron star transients

    OpenAIRE

    Campana, Sergio

    2003-01-01

    We review the observational properties of transient systems made by a neutron star primary and a late dwarf companion (known also as Soft X-ray Transients) during their quiescent state. We focus on the several emission mechanisms proposed and try to compare them with observations. Finally, we review new tools to improve our comprehension of the physics of the emission processes.

  9. $\\beta$-delayed proton decays near the proton drip line

    CERN Document Server

    Xu, S W; Huang, W X; Li, Z K; Pan Qiang Yan; Shu, N C; Wang, K; Wang, X D; Xie, Y X; Xing, Y B; Xu, F R; Yu, Y; 10.1103/PhysRevC.71.054318

    2005-01-01

    We briefly reviewed and summarized the experimental study on beta - delayed proton decays published by our group over the last 8 years, namely the experimental observation of beta -delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with N approximately=Z by utilizing the p- gamma coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half- lives for /sup 85/Mo, /sup 92/Rh, as well as the predicted "waiting point" nuclei /sup 89/Ru and /sup 93/Pd were 5-10 times longer than the macroscopic-microscopic model predictions of Moller et al. At. Data Nucl. Data Tables 66,131(1997). These data considerably influenced the predictions of the mass abundances of the nuclides produced in the rp p...

  10. Introduction to neutron stimulated emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Floyd, Carey E Jr [Department of Biomedical Engineering and Department of Radiology, Duke Advanced Imaging Laboratories Box 2623DUMC, Duke University, Durham, NC 27710 (United States); Bender, Janelle E [Department of Biomedical Engineering and Department of Radiology, Duke Advanced Imaging Laboratories Box 2623DUMC, Duke University, Durham, NC 27710 (United States); Sharma, Amy C [Department of Biomedical Engineering and Department of Radiology, Duke Advanced Imaging Laboratories Box 2623DUMC, Duke University, Durham, NC 27710 (United States); Kapadia, Anuj [Department of Biomedical Engineering and Department of Radiology, Duke Advanced Imaging Laboratories Box 2623DUMC, Duke University, Durham, NC 27710 (United States); Xia, Jessie [Department of Biomedical Engineering and Department of Radiology, Duke Advanced Imaging Laboratories Box 2623DUMC, Duke University, Durham, NC 27710 (United States); Harrawood, Brian [Department of Radiology, Duke Advanced Imaging Laboratories Box 3202DUMC, Duke University, Durham, NC 27710 (United States); Tourassi, Georgia D [Department of Radiology, Duke Advanced Imaging Laboratories Box 3202DUMC, Duke University, Durham, NC 27710 (United States); Lo, Joseph Y [Department of Radiology, Duke Advanced Imaging Laboratories Box 3202DUMC, Duke University, Durham, NC 27710 (United States); Crowell, Alexander [Department of Physics and Triangle Universities Nuclear Laboratory, Duke University, Durham, NC 27710 (United States); Howell, Calvin [Department of Physics and Triangle Universities Nuclear Laboratory, Duke University, Durham, NC 27710 (United States)

    2006-07-21

    Neutron stimulated emission computed tomography (NSECT) is presented as a new technique for in vivo tomographic spectroscopic imaging. A full implementation of NSECT is intended to provide an elemental spectrum of the body or part of the body being interrogated at each voxel of a three-dimensional computed tomographic image. An external neutron beam illuminates the sample and some of these neutrons scatter inelastically, producing characteristic gamma emission from the scattering nuclei. These characteristic gamma rays are acquired by a gamma spectrometer and the emitting nucleus is identified by the emitted gamma energy. The neutron beam is scanned over the body in a geometry that allows for tomographic reconstruction. Tomographic images of each element in the spectrum can be reconstructed to represent the spatial distribution of elements within the sample. Here we offer proof of concept for the NSECT method, present the first single projection spectra acquired from multi-element phantoms, and discuss potential biomedical applications.

  11. Neutron stimulated emission computed tomography: Background corrections

    Energy Technology Data Exchange (ETDEWEB)

    Floyd, Carey E. [Dept. of Biomedical Engineering, Duke University, Durham, NC 27708 (United States)]|[Duke Advanced Imaging Laboratories, Dept. of Radiology, Duke University, Durham, NC 27708 (United States)]|[Medical Physics Graduate Program, Duke University, Durham, NC 27708 (United States); Sharma, Amy C. [Dept. of Biomedical Engineering, Duke University, Durham, NC 27708 (United States)]|[Duke Advanced Imaging Laboratories, Dept. of Radiology, Duke University, Durham, NC 27708 (United States); E-mail: anc4@duke.edu; Bender, Janelle E.; Kapadia, Anuj J.; Xia, Jessie Q. [Dept. of Biomedical Engineering, Duke University, Durham, NC 27708 (United States)]|[Duke Advanced Imaging Laboratories, Dept. of Radiology, Duke University, Durham, NC 27708 (United States); Harrawood, Brian P. [Duke Advanced Imaging Laboratories, Dept. of Radiology, Duke University, Durham, NC 27708 (United States); Tourassi, Georgia D. [Duke Advanced Imaging Laboratories, Dept. of Radiology, Duke University, Durham, NC 27708 (United States); Lo, Joseph Y. [Dept. of Biomedical Engineering, Duke University, Durham, NC 27708 (United States)]|[Duke Advanced Imaging Laboratories, Dept. of Radiology, Duke University, Durham, NC 27708 (United States)]|[Medical Physics Graduate Program, Duke University, Durham, NC 27708 (United States); Kiser, Matthew R.; Crowell, Alexander S. [Dept. of Physics and Triangle Universities Nuclear Laboratory, Duke University, Durham, NC 27708 (United States); Pedroni, Ronald S. [North Carolina A and T State University, Greensboro, NC (United States); Macri, Robert A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Tajima, Shigeyuki [Dept. of Physics, University of Virginia, Charlottesville, VA (United States); Howell, Calvin R. [Medical Physics Graduate Program, Duke University, Durham, NC 27708 (United States)]|[Dept. of Physics and Triangle Universities Nuclear Laboratory, Duke University, Durham, NC 27708 (United States)

    2007-01-15

    Neutron stimulated emission computed tomography (NSECT) is an imaging technique that provides an in-vivo tomographic spectroscopic image of the distribution of elements in a body. To achieve this, a neutron beam illuminates the body. Nuclei in the body along the path of the beam are stimulated by inelastic scattering of the neutrons in the beam and emit characteristic gamma photons whose unique energy identifies the element. The emitted gammas are collected in a spectrometer and form a projection intensity for each spectral line at the projection orientation of the neutron beam. Rotating and translating either the body or the beam will allow a tomographic projection set to be acquired. Images are reconstructed to represent the spatial distribution of elements in the body. Critical to this process is the appropriate removal of background gamma events from the spectrum. Here we demonstrate the equivalence of two background correction techniques and discuss the appropriate application of each.

  12. Theory of neutron emission in fission

    International Nuclear Information System (INIS)

    Following a summary of the observables in neutron emission in fission, a brief history is given of theoretical representations of the prompt fission neutron spectrum N(E) and average prompt neutron multiplicity bar νp. This is followed by descriptions, together with examples, of modern approaches to the calculation of these quantities including recent advancements. Emphasis will be placed upon the predictability and accuracy of the modern approaches. In particular, the dependence of N(E) and bar νp on the fissioning nucleus and its excitation energy will be discussed, as will the effects of and competition between first-, second- and third-chance fission in circumstances of high excitation energy. Finally, properties of neutron-rich (fission-fragment) nuclei are discussed that must be better known to calculate N(E) and bar νp with higher accuracy than is currently possible

  13. Nuclear data for neutron emission in the fission process

    International Nuclear Information System (INIS)

    This document contains the proceedings of the IAEA Consultants' Meeting on Nuclear Data for Neutron Emission in the Fission Process, Vienna, 22 - 24 October 1990. Included are the conclusions and recommendations reached at the meeting and the papers presented by the meeting participants. These papers provide a review of the status of experimental and theoretical data on neutron emission in spontaneous and neutron induced fission with reference to the data needs for reactor applications oriented towards actinide burner studies. The specific topics covered are the following: experimental measurements and theoretical predictions and evaluations of fission neutron energy spectra, average prompt fission neutron multiplicity, correlation in neutron emission from complementary fragments, neutron emission during acceleration of fission fragments, statistical properties of neutron rich nuclei by study of emission spectra of neutrons from the excited fission fragments, integral qualification of nu-bar for the major fissile isotopes, nu-bar total of 239Pu and 235U, and related problems. Refs figs and tabs

  14. LORINE: Neutron emission Locator by SOI detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hamrita, H.; Kondrasovs, V.; Borbotte, J. M.; Normand, S. [CEA, LIST, Laboratoire Capteurs et Architectures Electronique, F-91191 Gif-sur-Yvette Cedex (France); Saurel, N. [CEA, DAM, VALDUC, F-21120 Is sur Tille (France)

    2009-07-01

    The aim of this work is to develop a fast Neutron Emission Locator based on silicon on Insulator detector (LORINE). This locator can be used in the presence of significant flux of gamma radiation. LORINE was developed to locate areas containing a significant amount of actinide during the dismantling operations of equipment. From the results obtained in laboratory, we have proposed the prototype of neutron emission locator as follows: the developed design consists of 5 SOI (Silicon-on-insulator) detectors (1*1 cm{sup 2}) with their charge preamplifiers and their respective converters. All are installed on 5 faces of a boron polyethylene cube (5*5*5 cm{sup 3}). This cube plays the role of neutron shielding between the several detectors. The design must be so compact for use in glove boxes. An electronic card based on micro-controller has been made to control sensors and to send the necessary information to the computer. Location of fast neutron sources does not yet exist in a so compact design and it can be operated in the presence of very important gamma radiation flux

  15. Study of neutron-rich $^{51−53}$ Ca isotopes via $\\beta$-decay

    CERN Multimedia

    The high Q$_\\beta$ values in certain neutron-rich regions of the chart of nuclides opens up the possibility to study states in the daughter nuclei which lie at high excitation energy, above the neutron separation threshold. We propose to perform spectroscopy of the $\\beta$-delayed neutron emission of the $^{51-53}$K isotopes to study the population of single-particle or particle-hole states both below and above the neutron separation threshold. The VANDLE neutron detector will be used in combination with the IDS tape station setup and Ge detectors.

  16. Microscopic description of neutron emission rates in compound nuclei

    CERN Document Server

    Zhu, Yi

    2014-01-01

    The neutron emission rates in thermal excited nuclei are conventionally described by statistical models with a phenomenological level density parameter that depends on excitation energies, deformations and mass regions. In the microscopic view of hot nuclei, the neutron emission rates can be determined by the external neutron gas densities without any free parameters. Therefore the microscopic description of thermal neutron emissions is desirable that can impact several understandings such as survival probabilities of superheavy compound nuclei and neutron emissivity in reactors. To describe the neutron emission rates microscopically, the external thermal neutron gases are self-consistently obtained based on the Finite-Temperature Hartree-Fock-Bogoliubov (FT-HFB) approach. The results are compared with the statistical model to explore the connections between the FT-HFB approach and the statistical model. The Skyrme FT-HFB equation is solved by HFB-AX in deformed coordinate spaces. Based on the FT-HFB approach...

  17. Neutrino emissivity of anisotropic neutron superfluids

    OpenAIRE

    Leinson, L. B.

    2013-01-01

    We examine the influence of the anisotropy of the superfluid energy gap and residual Fermi-liquid interactions in the triplet-correlated neutron liquid onto neutrino energy losses through neutral weak currents. The neutrino-pair emission caused by the pair breaking and formation processes and by the spin-wave decays is considered for the case of the $^{3}P_{2}$ pairing in the state with $m_{j}=0$. The simple analytical formulae are obtained. A comparison with the previous results of the avera...

  18. Calculation of delayed-neutron energy spectra in a QRPA-Hauser-Feshbach model

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Toshihiko [Los Alamos National Laboratory; Moller, Peter [Los Alamos National Laboratory; Wilson, William B [Los Alamos National Laboratory

    2008-01-01

    Theoretical {beta}-delayed-neutron spectra are calculated based on the Quasiparticle Random-Phase Approximation (QRPA) and the Hauser-Feshbach statistical model. Neutron emissions from an excited daughter nucleus after {beta} decay to the granddaughter residual are more accurately calculated than in previous evaluations, including all the microscopic nuclear structure information, such as a Gamow-Teller strength distribution and discrete states in the granddaughter. The calculated delayed-neutron spectra agree reasonably well with those evaluations in the ENDF decay library, which are based on experimental data. The model was adopted to generate the delayed-neutron spectra for all 271 precursors.

  19. Search for beta-delayed protons from 11Be

    International Nuclear Information System (INIS)

    The one-neutron halo nucleus 11Be can emit a proton in a beta decay of the halo neutron. However, due to the Q-value of this decay channel (280.7±0.3 keV) the expected branching ratio will be very low - most estimates are a few times 10-8 - and the detection of the outgoing proton with a kinetic energy of a few hundred keV is challenging. Therefore our attempt was to detect the remaining nucleus 10Be with the help of accelerator mass spectrometry (AMS). AMS is a highly sensitive tool to detect radioisotopes at the ultra-trace level. A beam of 11Be ions was produced at the ISOLDE facility at CERN and implanted in a collection sample. The sample was transferred to the VERA AMS facility at the University of Vienna where the 10Be content was determined. In my talk I present details of the experiment and results of the successful detection of this rare decay channel.

  20. Prompt Emission in Fission Induced with Fast Neutrons

    Science.gov (United States)

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

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

  1. Superfluid Response and the Neutrino Emissivity of Neutron Matter

    OpenAIRE

    Steiner, Andrew W.; Reddy, Sanjay

    2008-01-01

    {We calculate the neutrino emissivity of superfluid neutron matter in the inner crust of neutron stars. We find that neutrino emission due to fluctuations resulting from the formation of Cooper pairs at finite temperature is highly suppressed in non-relativistic systems. This suppression of the pair breaking emissivity in a simplified model of neutron matter with interactions that conserve spin is of the order of $v_F^4$ for density fluctuations and $v_F^2$ for spin fluctuations, where $v_F$ ...

  2. A compact plasma focus device and its neutron emission

    Institute of Scientific and Technical Information of China (English)

    王新新; 韩旻; 王志文; 刘坤

    1999-01-01

    A 2.2-kJ compact plasma focus device was developed and its characteristics of neutron emission were investigated. A maximum neutron yield of (3.1 ± 1.5) × 10~7 was obtained at 15 hPa deuterium filling pressure. It was found that the neutron yield Y_n is strongly correlated with the amplitude of the pinch dip in di/dt waveform. The time resolved measurement of the neutron pulse indicated that both the hard X-rays and the neutrons are emitted from plasma focus at the same instant and the width of neutron pulse (FWHM) changes slightly from 50 to 53 ns. The pinch time t_p varies from 1.5 to 16.5 ns and it is usually the case that the shorter t_p, the higher the neutron yield. It was also found that the squirrel cage cathode is better than the tubular cathode.

  3. Baryon superfluidity and neutrino emissivity of neutron stars

    OpenAIRE

    Takatsuka, T.; Tamagaki, R.

    2004-01-01

    For neutron stars with hyperon-mixed core, neutrino emissivity is studied under the equation of state, obtained by introducing repulsive three-body force universal for all baryons so as to assure the maximum mass compatible with the observation. By paying attention to the density-dependence of critical temperatures of baryon superfluids, which reflect the nature of baryon-baryon interaction and control neutron star cooling, we show what neutrino emission processes are efficient in the regions...

  4. Importance of ~5He Emission in Neutron Induced Reactions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The statistical model codes as the evaluation tool widely used in the world have long been performedto set up neutron data library below 20 MeV However, an important particle emission of ~5He has neverbeen included in the widely used codes. Based on the calculated threshold energies of ~3He and ~5He emissions for various nuclei, one can find

  5. Modelling of reaction cross sections and prompt neutron emission

    Science.gov (United States)

    Hambsch, F.-J.; Tudora, A.; Oberstedt, S.

    2010-10-01

    Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f) and 237Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  6. Modelling of reaction cross sections and prompt neutron emission

    OpenAIRE

    Oberstedt S.; Tudora A.; Hambsch F.-J.

    2010-01-01

    Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f) and 237Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  7. Neutrino emission in neutron matter from magnetic moment interactions

    CERN Document Server

    Jaikumar, P; Gale, C; Jaikumar, Prashanth; Gale, Charles

    2004-01-01

    Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low energy ($\\sim$ keV) nature of this process, one expects very few nonstandard particle physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the tau magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak interaction by a factor two, signalling the importance of new particle physics input to ...

  8. $^{11}$Be($\\beta$p), a quasi-free neutron decay?

    CERN Document Server

    Riisager, K.; Borge, M.J.G.; Briz, J.A.; Carmona-Gallardo, M.; Fraile, L.M.; Fynbo, H.O.U.; Giles, T.; Gottberg, A.; Heinz, A.; Johansen, J.G.; Jonson, B.; Kurcewicz, J.; Lund, M.V.; Nilsson, T.; Nyman, G.; Rapisarda, E.; Steier, P.; Tengblad, O.; Thies, R.; Winkler, S.R.

    2014-01-01

    We have observed $\\beta$-delayed proton emission from the neutron-rich nucleus $^{11}$Be by analysing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.4 $\\pm$ 0.6)$\\times$ 10$^{-6}$ the strength of this decay mode, as measured by the B$_\\mathrm{GT}$-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the $^{11}$Be halo neutron into a single-proton state.

  9. A parametric model for fusion neutron emissivity tomography for the KN3 neutron camera at JET

    International Nuclear Information System (INIS)

    A parametric model for fusion neutron emissivity is presented and applied to the KN3 neutron camera data collected during the trace tritium experiment at the Joint European Torus. This work is aimed at achieving a good compromise between accuracy of tomographic reconstruction and low model complexity. This means low numerical degeneracy and good time consistency of the results. The model is compared both with plasma simulation codes and other tomographic techniques, which use KN3 line integrated emissivity data, showing good agreement over the entire data set analysed (∼500 plasma discharges).

  10. Possibility of 5He emission in neutron induced reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jingshang

    2004-01-01

    The unstable nucleus 5He emission has never been included in the widely used statistical model codes as the evaluation tool and interpretation experimental data.The calculated threshold energies of 5He emission from light nuclei to heavy nuclei indicate that in most cases the compound nucleus induced by incident neutron would emit 5He rather than 3He. Since 5He is unstable and can be separated into n+α spontaneously,so neutron is produced in 5He emission process. The formulation of the double-differential cross section of the neutron from the two-body breakup process of emitted 5He is established. Because of the strong recoil effect, the energy balance is strictly taken into account to meet the needs in nuclear engineering. Further improvement of the statistical model calculation codes on this respect is proposed. It is expected that the correlative measurement will be available to account the outgoing neutron and alpha particle simultaneously and to test and verify the existence of 5He emission.

  11. On evaluated nuclear data for beta-delayed gamma rays following of special nuclear materials

    Energy Technology Data Exchange (ETDEWEB)

    Mencarini, Leonardo de H.; Caldeira, Alexandre D., E-mail: mencarini@ieav.cta.b, E-mail: alexdc@ieav.cta.b [Instituto de Estudos Avancados (IEAv/CTA), Sao Jose dos Campos, SP (Brazil)

    2011-07-01

    In this paper, a new type of information available in ENDF is discussed. During a consistency check of the evaluated nuclear data library ENDF/B-VII.0 performed at the Nuclear Data Subdivision of the Institute for Advanced Studies, the size of the files for some materials drew the attention of one of the authors. Almost 94 % of all available information for these special nuclear materials is used to represent the beta-delayed gamma rays following fission. This is the first time this information is included in an ENDF version. (author)

  12. On evaluated nuclear data for beta-delayed gamma rays following of special nuclear materials

    International Nuclear Information System (INIS)

    In this paper, a new type of information available in ENDF is discussed. During a consistency check of the evaluated nuclear data library ENDF/B-VII.0 performed at the Nuclear Data Subdivision of the Institute for Advanced Studies, the size of the files for some materials drew the attention of one of the authors. Almost 94 % of all available information for these special nuclear materials is used to represent the beta-delayed gamma rays following fission. This is the first time this information is included in an ENDF version. (author)

  13. Monte Carlo Models for the Production of beta-delayed Gamma Rays Following Fission of Special Nuclear Materials

    Energy Technology Data Exchange (ETDEWEB)

    Pruet, J; Prussin, S; Descalle, M; Hall, J

    2004-02-03

    A Monte Carlo method for the estimation of {beta}-delayed {gamma}-ray spectra following fission is described that can accommodate an arbitrary time-dependent fission rate and photon collection history. The method invokes direct sampling of the independent fission yield distributions of the fissioning system, the branching ratios for decay of individual fission products and the spectral distributions for photon emission for each decay mode. Though computationally intensive, the method can provide a detailed estimate of the spectrum that would be recorded by an arbitrary spectrometer, and can prove useful in assessing the quality of evaluated data libraries, for identifying gaps in these libraries, etc. The method is illustrated by a first comparison of calculated and experimental spectra from decay of short-lived fission products following the reactions {sup 235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f). For general purpose transport calculations, where detailed consideration of the large number of individual {gamma}-ray transitions in a spectrum may be unnecessary, it is shown that an accurate and simple parameterization of a {gamma}-ray source function can be obtained. These parametrizations should provide high-quality average spectral distributions that should prove useful in calculations describing photons escaping from thick attenuating media.

  14. 5He Emission in Neutron-Induced 10B Reactions

    Institute of Scientific and Technical Information of China (English)

    WANG Ji-Min; DUAN Jun-Feng; YAN Yu-Liang; SUN Xiao-Jun; ZHANG Jing-Shang

    2006-01-01

    In n + 10B reactions, 5He cluster emission has been discussed with the updated level scheme and the new optical model parameters. In this paper the reaction channels related to 5He emission are listed in detail. By using the new reaction model for light nuclei, the double-differential cross sections of total outgoing neutrons for n + 10 B reactions at En = 14.2 MeV have been calculated, and the results agree fairly well with the measurements. Particularly, in the energy-angular spectra the contribution from the 5He-emission to the total outgoing neutron double-differential cross sections has also been analyzed, and the partial energy-angular spectra of 60° at En = 14.2 MeV have been given.The calculated results indicate that once the 5He emission is taken into account, the fitting with the double-differential measurements of total outgoing neutrons at the low energy region could be improved. Therefore, to consider the 5He emission properly in the reaction processes of light nuclei is necessary.

  15. Neutrino emission in neutron matter from magnetic moment interactions

    International Nuclear Information System (INIS)

    Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low-energy (∼keV) nature of this process, one expects very few nonstandard particle-physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the τ magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak interaction by a factor 2, signaling the importance of new particle physics input to a standard calculation of relevance to neutron star cooling. However, astrophysical bounds on the neutrino magnetic moment imply smaller effects

  16. Study of neutron rich nuclei by delayed neutron decay using the Tonnerre multidetector; Etude de la decroissance par neutrons retardes de noyaux legers riches en neutrons avec le multidetecteur tonnerre

    Energy Technology Data Exchange (ETDEWEB)

    Timis, C.N

    2001-07-01

    A new detection array for beta delayed neutrons was built. It includes up to 32 plastic scintillation counters 180 cm long located at 120 cm from the target. Neutron energy spectra are measured by time-of-flight in the 300 keV-15 MeV range with good energy resolution. The device was tested with several known nuclei. Its performances are discussed in comparison with Monte Carlo simulations. They very high overall detection efficiency on the TONNERRE array made it possible to study one and two neutron emission of {sup 11}Li. A complete decay scheme was obtained. The {sup 33}Mg and {sup 35}Al beta decays were investigated for the first time by neutron and gamma spectroscopy. Complete decay schemes were established and compared to large scale shell-model calculations. (authors)

  17. Modelling of reaction cross sections and prompt neutron emission

    Directory of Open Access Journals (Sweden)

    Oberstedt S.

    2010-10-01

    Full Text Available Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f and 237Np(n, f both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  18. beta-delayed fission from sup 2 sup 3 sup 0 Ac

    CERN Document Server

    Yang Wei Fan; Xu Yan Bing; Xong Bing; Pan Qiang Yan; He Jian Jun; Xiao Yong Hou; Li Yi

    2002-01-01

    ThO sub 2 is irradiated with 60 MeV/u sup 1 sup 8 O beams. sup 2 sup 3 sup 0 Ra is produced via the multi-nucleon transfer and dissipative fragmentation reactions of the target. sup 2 sup 3 sup 0 Ra is radio-chemical separated from ThO sub 2 and the other reaction products. The thin Ra sources are prepared. The mica fission track detectors are exposed to the Ra sources. gamma-rays of Ra decay in the sources are measured by a HPGe detector. The mica foil is etched in HF solution. The etched mica foil is scanned with an optical microscope. The fission tracks that should come from beta-delayed fission of sup 2 sup 3 sup 0 Ac are observed. The beta-delayed fission probability of sup 2 sup 3 sup 0 Ac is determined to be (1.19 +- 0.85) x 10 sup - sup 8

  19. Competition between $\\beta$-delayed proton and $\\beta$-delayed $\\gamma$ decay of the exotic $T_z$ = -2 nucleus $^{56}$Zn and fragmentation of the IAS

    CERN Document Server

    Rubio, B; Fujita, Y; Blank, B; Gelletly, W; Agramunt, J; Algora, A; Ascher, P; Bilgier, B; Cáceres, L; Cakirli, R B; Fujita, H; Ganioglu, E; Gerbaux, M; Giovinazzo, J; Grévy, S; Kamalou, O; Kozer, H C; Kucuk, L; Kurtukian-Nieto, T; Molina, F; Popescu, L; Rogers, A M; Susoy, G; Stodel, C; Suzuki, T; Tamii, A; Thomas, J C

    2015-01-01

    A very exotic decay mode at the proton drip-line, $\\beta$-delayed $\\gamma$-proton decay, has been observed in the $\\beta$ decay of the $T_z$ = -2 nucleus $^{56}$Zn. Three $\\gamma$-proton sequences have been observed following the $\\beta$ decay. The fragmentation of the IAS in $^{56}$Cu has also been observed for the first time. The results were reported in a recent publication. At the time of publication the authors were puzzled by the competition between proton and $\\gamma$ decays from the main component of the IAS. Here we outline a possible explanation based on the nuclear structure properties of the three nuclei involved, namely $^{56}$Zn, $^{56}$Cu and $^{55}$Ni, close to the doubly magic nucleus $^{56}$Ni. From the fragmentation of the Fermi strength and the excitation energy of the two populated 0$^{+}$ states we could deduce the off-diagonal matrix element of the charge-dependent part of the Hamiltonian responsible for the mixing. These results are compared with the decay of $^{55}$Cu with one proton ...

  20. Solar neutron emissivity during the large flare on 1982 June 3

    Science.gov (United States)

    Chupp, E. L.; Forrest, D. J.; Kanbach, G.; Flueckiger, E.; Golliez, F.

    1987-01-01

    For the solar neutron event on June 3, 1982, it is shown here that the combined SMM Gamma Ray Spectrometer and Jungfraujoch neutron monitor data require a time-extended emission of neutrons at the sun with energies of 100 MeV to about 2 GeV. The solar neutron emissivity spectrum is shown to have a strong downward curvature or truncation between 2 and 4 GeV. A Bessel function and truncated power law give acceptable fits to the observational data, but only the power law can explain the rapid rise of the neutron monitor count rate. The integrated emissivity of neutrons above E(n) of 100 MeV is strongly constrained at 8 x 10 to the 28th neutrons/sr and is essentially independent of neutron spectral shape. At neutron energies of about 100 MeV, good agreement is found for both spectral forms with observations of neutron decay protons.

  1. Deformations of Accreting Neutron Star Crusts and Gravitational Wave Emission

    OpenAIRE

    Ushomirsky, Greg; Cutler, Curt; Bildsten, Lars

    2000-01-01

    Motivated by the narrow range of spin frequencies of nearly 20 accreting neutron stars, Bildsten (1998) conjectured that their spin-up had been halted by the emission of gravitational waves. He also pointed out that small nonaxisymmetric temperature variations in the accreted crust will lead to "wavy" electron capture layers, whose horizontal density variations naturally create a mass quadrupole moment. We present a full calculation of the crust's elastic adjustment to these density perturbat...

  2. Neutron stimulated emission computed tomography: a Monte Carlo simulation approach

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, A C [Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Durham, NC 27708 (United States); Harrawood, B P [Duke Advance Imaging Labs, Department of Radiology, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (United States); Bender, J E [Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Durham, NC 27708 (United States); Tourassi, G D [Duke Advance Imaging Labs, Department of Radiology, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (United States); Kapadia, A J [Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Durham, NC 27708 (United States)

    2007-10-21

    A Monte Carlo simulation has been developed for neutron stimulated emission computed tomography (NSECT) using the GEANT4 toolkit. NSECT is a new approach to biomedical imaging that allows spectral analysis of the elements present within the sample. In NSECT, a beam of high-energy neutrons interrogates a sample and the nuclei in the sample are stimulated to an excited state by inelastic scattering of the neutrons. The characteristic gammas emitted by the excited nuclei are captured in a spectrometer to form multi-energy spectra. Currently, a tomographic image is formed using a collimated neutron beam to define the line integral paths for the tomographic projections. These projection data are reconstructed to form a representation of the distribution of individual elements in the sample. To facilitate the development of this technique, a Monte Carlo simulation model has been constructed from the GEANT4 toolkit. This simulation includes modeling of the neutron beam source and collimation, the samples, the neutron interactions within the samples, the emission of characteristic gammas, and the detection of these gammas in a Germanium crystal. In addition, the model allows the absorbed radiation dose to be calculated for internal components of the sample. NSECT presents challenges not typically addressed in Monte Carlo modeling of high-energy physics applications. In order to address issues critical to the clinical development of NSECT, this paper will describe the GEANT4 simulation environment and three separate simulations performed to accomplish three specific aims. First, comparison of a simulation to a tomographic experiment will verify the accuracy of both the gamma energy spectra produced and the positioning of the beam relative to the sample. Second, parametric analysis of simulations performed with different user-defined variables will determine the best way to effectively model low energy neutrons in tissue, which is a concern with the high hydrogen content in

  3. Fast neutron-gamma discrimination on neutron emission profile measurement on JT-60U

    International Nuclear Information System (INIS)

    A digital signal processing (DSP) system is applied to stilbene scintillation detectors of the multichannel neutron emission profile monitor in JT-60U. Automatic analysis of the neutron-γ pulse shape discrimination is a key issue to diminish the processing time in the DSP system, and it has been applied using the two-dimensional (2D) map. Linear discriminant function is used to determine the dividing line between neutron events and γ-ray events on a 2D map. In order to verify the validity of the dividing line determination, the pulse shape discrimination quality is evaluated. As a result, the γ-ray contamination in most of the beam heating phase was negligible compared with the statistical error with 10 ms time resolution.

  4. Beamed neutron emission driven by laser accelerated light ions

    CERN Document Server

    Kar, S; Ahmed, H; Alejo, A; Robinson, A P L; Cerchez, M; Clarke, R; Doria, D; Dorkings, S; Fernandez, J; Mirfyazi, S R; McKenna, P; Naughton, K; Neely, D; Norreys, P; Peth, C; Powell, H; Ruiz, J A; Swain, J; Willi, O; Borghesi, M

    2015-01-01

    We report on the experimental observation of beam-like neutron emission with peak flux of the order of 10^9 n/sr, from light nuclei reactions in a pitcher-catcher scenario, by employing MeV ions driven by high power laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of 70 degrees, with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitcher-catcher materials indicates the dominant reactions being d(p, n+p)^1H and d(d,n)^3He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons' spatial and spectral profiles are most likely related to the directionality and high energy of the projectile ions.

  5. Contributions to the theory of fission neutron emission

    International Nuclear Information System (INIS)

    This report gives a compilation of recent work performed at Technical University, Dresden by D. Seeliger, H. Maerten and A. Ruben on the topic of fission neutron emission. In the first paper calculated fission neutron spectra are presented using the temperature distribution model FINESSE for fissioning actinide nuclei. In the second paper, starting from a general energy balance, Terrell's approach is generalized to describe average fragment energies as a function of incident energy; trends of fragment energy data in the Th-Pu region are well reproduced. In the third contribution, prompt fission neutron spectra and fragment characteristics for spontaneous fission of even Pu-isotopes are presented and discussed in comparison with experimental data using a phenomenological scission point model including temperature dependent shell effects. In the fourth paper, neutron multiplicities and energy spectra as well as average fragment energies for incident energies from threshold to 20 MeV (including multiple-chance fission) for U-238 are compared with traditional data representations. (author). Refs, figs and tabs

  6. Study of Beta-delayed Proton Emission of 36,37Ca

    Institute of Scientific and Technical Information of China (English)

    SUN; Li-jie; LIN; Cheng-jian; XU; Xin-xing; JIA; Hui-ming; YANG; Lei; BAO; Peng-fei; MA; Nan-ru; ZHANG; Huan-qiao; LIU; Zu-hua; WU; Zhen-dong; ZHENG; Lei; WANG; Jian-song; YANG; Yan-yun; HU; Zheng-guo; XU; Hu-shan; WANG; Meng; JIN; Shi-lun; HAN; Jian-long; ZHANG; Ning-tao; MA; Jun-bing; MA; Peng; ZHANG; Yu-hu; ZHOU; Xiao-hong; MA; Xin-wen; XIAO; Guo-qing

    2013-01-01

    Our experiment on the decays of 37Ca(QEC=11 639(22)keV)and 36Ca(QEC=10 990(40)keV)was performed at the Heavy Ion Research Facility in Lanzhou(HIRFL).The radioactive ion beam(RIB)37,36Ca was produced by projectile fragmentation,then separated and purified by the Radioactive Ion Beam Line in Lanzhou(RIBLL)spectrometer.By employing the silicon detector array and segmented

  7. Study of the $\\beta$-delayed Particle Emission of $^{17}$Ne

    CERN Multimedia

    2002-01-01

    We intend to investigate the charged particle decay modes from the excited states of $^{17}$F populated in the $\\beta^+$- decay of $^{17}$Ne. In particular, we propose to study the proton decay branches to $^{16}$O states which are unstable to $\\alpha$- decay. We plan to use the recently developed ISOLDE Si-ball detector array in order to efficiently detect the charged particles in a wide solid angle. We ask for a total of 12 shifts, including 9 shifts for $^{17}$Ne and 3 shifts for stable beam and calibrations. We request the use of a Mg oxide target coupled to a plasma ion source with cooled transfer line or, if possible, to the new MINIMONOECRIS. We would like to make use of the ISOLDE VME DAQ and CERN data storage system.

  8. Gamow-Teller response in deformed even and odd neutron-rich Zr and Mo isotopes

    CERN Document Server

    Sarriguren, P; Pereira, J

    2014-01-01

    Beta-decay properties of neutron-rich Zr and Mo isotopes are investigated within a microscopic theoretical approach based on the proton-neutron quasiparticle random-phase approximation. The underlying mean field is described self-consistently from deformed Skyrme Hartree-Fock calculations with pairing correlations. Residual separable particle-hole and particle-particle forces are also included in the formalism. The structural evolution in these isotopic chains including both even and odd isotopes is analyzed in terms of the equilibrium deformed shapes. Gamow-Teller strength distributions, beta-decay half-lives, and beta-delayed neutron-emission probabilities are studied, stressing their relevance to describe the path of the nucleosynthesis rapid neutron capture process.

  9. Acoustic, electromagnetic, neutron emissions from fracture and earthquakes

    CERN Document Server

    Lacidogna, Giuseppe; Manuello, Amedeo

    2015-01-01

    This book presents the relevant consequences of recently discovered and interdisciplinary phenomena, triggered by local mechanical instabilities. In particular, it looks at emissions from nano-scale mechanical instabilities such as fracture, turbulence, buckling and cavitation, focussing on vibrations at the TeraHertz frequency and Piezonuclear reactions. Future applications for this work could include earthquake precursors, climate change, energy production, and cellular biology. A series of fracture experiments on natural rocks demonstrates that the TeraHertz vibrations are able to induce fission reactions on medium weight elements accompanied by neutron emissions. The same phenomenon appears to have occurred in several different situations, particularly in the chemical evolution of the Earth and Solar System, through seismicity (rocky planets) and storms (gaseous planets). As the authors explore, these phenomena can also explain puzzles related to the history of our planet, like the ocean formation or th...

  10. Classification of JET Neutron and Gamma Emissivity Profiles

    Science.gov (United States)

    Craciunescu, T.; Murari, A.; Kiptily, V.; Vega, J.; Contributors, JET

    2016-05-01

    In thermonuclear plasmas, emission tomography uses integrated measurements along lines of sight (LOS) to determine the two-dimensional (2-D) spatial distribution of the volume emission intensity. Due to the availability of only a limited number views and to the coarse sampling of the LOS, the tomographic inversion is a limited data set problem. Several techniques have been developed for tomographic reconstruction of the 2-D gamma and neutron emissivity on JET. In specific experimental conditions the availability of LOSs is restricted to a single view. In this case an explicit reconstruction of the emissivity profile is no longer possible. However, machine learning classification methods can be used in order to derive the type of the distribution. In the present approach the classification is developed using the theory of belief functions which provide the support to fuse the results of independent clustering and supervised classification. The method allows to represent the uncertainty of the results provided by different independent techniques, to combine them and to manage possible conflicts.

  11. Empirical description of beta-delayed fission partial half-lives

    CERN Document Server

    Ghys, L; Antalic, S; Huyse, M; Van Duppen, P

    2015-01-01

    Background: The process of beta-delayed fission (bDF) provides a versatile tool to study low-energy fission in nuclei far away from the beta-stability line, especially for nuclei which do not fission spontaneously. Purpose: The aim of this paper is to investigate systematic trends in bDF partial half-lives. Method: A semi-phenomenological framework was developed to systematically account for the behavior of bDF partial half-lives. Results: The bDF partial half-life appears to exponentially depend on the difference between the Q value for beta decay of the parent nucleus and the fission-barrier energy of the daughter (after beta decay) product. Such dependence was found to arise naturally from some simple theoretical considerations. Conclusions: This systematic trend was confirmed for experimental bDF partial half-lives spanning over 7 orders of magnitudes when using fission barriers calculated from either the Thomas-Fermi or the liquid-drop fission model. The same dependence was also observed, although less p...

  12. $\\beta$-delayed fission in proton-rich nuclei in the lead region

    CERN Document Server

    AUTHOR|(CDS)2085005; Huyse, Mark; Popescu, Lucia

    Nuclear fission is the breakup of an atomic nucleus into two (sometimes three) fragments, thereby releasing a large amount of energy. Soon after its discovery in the late 1930’s, the gross properties of the fission phenomenon were explained by macroscopic nuclear models. Certain features however, such as asymmetric fission-fragment mass distributions in the actinide region, require the inclusion of microscopic effects. This interplay of the microscopic motion of individual nucleons on this macroscopic process is, until today, not yet fully understood. The phenomenon of fission has therefore been of recurring interest for both theoretical and experimental studies. This thesis work focuses on the $\\beta$-delayed fission ($\\beta$DF) process, an excellent tool to study low-energy fission of exotic nuclei, which was discovered in 1966 in the actinide region. In this two-step process, a precursor nucleus first undergoes $\\beta$-decay to an excited level in the daughter nucleus, which may subsequently fission. Rec...

  13. Polarization of neutron star surface emission: a systematic analysis

    Science.gov (United States)

    Taverna, Roberto

    2016-07-01

    New-generation X-ray polarimeters currently under development promise to open a new window in the study of high-energy astrophysical sources. Among them, neutron stars (NSs) appear particularly suited for polarization measurements. Radiation from the (cooling) surface of an NS is expected to exhibit a large intrinsic polarization degree due to the star strong magnetic field (≈ 10 ^{12}-10 ^{15} G). We present an efficient method for computing the observed polarization fraction and polarization angle in the case of radiation coming from the entire surface of an NS, accounting for both vacuum polarization and geometrical effects due to the extended emitting region. Our approach is fairly general and is illustrated in the case of blackbody emission from an NS with either a dipolar or a (globally) twisted magnetic field.

  14. Low-background measurements of neutron emission from Ti metal in pressurized deuterium gas

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, H.O.; Paciotti, M.A.; Claytor, T.N.; Tuggle, D.G.

    1991-01-01

    A wide variety of neutron detector systems have been used at various research facilities to search for anomalous neutron emission from deuterated metals. Some of these detector systems are summarized here together with possible sources of spurious signals from electronic noise. During the past two years, we have performed experiments to measure neutron emission from pressurized D{sub 2} gas mixed with various forms of titanium metal chips and sponge. Details concerning the neutron detectors, experimental procedures, and results have been reported previously. Our recent experiments have focused on increasing the low-level neutron emission and finding a way to trigger the emission. To improve our detection sensitivity, we have increased the shielding in our counting laboratory, changed to low-background {sup 3}He tubes, and set up additional detector systems in deep underground counting stations. This report is an update on this experimental work. 7 refs., 5 figs., 4 tabs.

  15. Preequilibrium neutron emission in heavy ion reaction: Mean field effect and multiple emission

    Science.gov (United States)

    Paul, Sabyasachi; Nandy, Maitreyee; Mohanty, A. K.; Gambhir, Y. K.

    2016-09-01

    Effects of nuclear mean field and of multiple preequilibrium (PEQ) emission on double differential neutron multiplicity distribution from heavy ion reactions (12C+165Ho and 20Ne+165Ho ) at 10-30 MeV/u have been investigated in the framework of the semiclassical formalism for heavy ion reaction (henceforth termed "HION") developed earlier. HION follows the equilibration of a target+projectile composite system through the kinematics of two-body scattering. In the present work nuclear density distribution in the composite system is estimated in the relativistic mean field (RMF) approach. The nucleon-nucleon collision rates and subsequently the nucleon emission probability are calculated from this density distribution. A second approach based on a semiphenomenological formalism is also used for nuclear density distribution. Energy-angle distribution of neutron multiplicities calculated with this modified HION model coupled with multiple PEQ emission could reproduce the measured data of earlier workers in the projectile energy range of 10-30 MeV/u.

  16. Pion mass effects on axion emission from neutron stars through NN bremsstrahlung processes

    International Nuclear Information System (INIS)

    The rates of axion emission by nucleon-nucleon bremsstrahlung are calculated with the inclusion of the full momentum contribution from a nuclear one pion exchange (OPE) potential. The contributions of the neutron-neutron (nn), proton-proton ( pp) and neutron-proton (np) processes in both the non-degenerate and degenerate limits are explicitly given. We find that the finite-momentum corrections to the emissivities are quantitatively significant for the non-degenerate regime and temperature-dependent, and should affect the existing axion mass bounds. The trend of these nuclear effects is to diminish the emissivities.

  17. An empirical fit to estimated neutron emission cross sections from proton induced reactions

    Indian Academy of Sciences (India)

    Moumita Maiti; Maitreyee Nandy; S N Roy; P K Sarkar

    2003-01-01

    Neutron emission cross section for various elements from 9Be to 209Bi have been calculated using the hybrid model code ALICE-91 for proton induced reactions in the energy range 25 MeV to 105 MeV. An empirical expression relating neutron emission cross section to target mass number and incident proton energy has been obtained. The simple expression reduces the computation time significantly. The trend in the variation of neutron emission cross sections with respect to the target mass number and incident proton energy has been discussed within the framework of the model used.

  18. Investigating Prompt Fission Neutron Emission from 235U(n,f) in the Resolved Resonance Region

    Science.gov (United States)

    Göök, Alf; Hambsch, Franz-Josef; Oberstedt, Stephan

    2016-03-01

    Investigations of prompt emission in fission is of importance in understanding the fission process in general and the sharing of excitation energy among the fission fragments in particular. Experimental activities at IRMM on prompt neutron emission from fission in response to OECD/NEA nuclear data requests is presented in this contribution. Main focus lies on currently on-going investigations of prompt neutron emission from the reaction 235U(n,f) in the region of the resolved resonances. For this reaction strong fluctuations of fission fragment mass distributions and mean total kinetic energy have been observed [Nucl. Phys. A 491, 56 (1989)] as a function of incident neutron energy in the resonance region. In addition fluctuations of prompt neutron multiplicities were also observed [Phys. Rev. C 13, 195 (1976)]. The goal of the present study is to verify the current knowledge of prompt neutron multiplicity fluctuations and to study correlations with fission fragment properties.

  19. Investigating Prompt Fission Neutron Emission from 235U(n,f in the Resolved Resonance Region

    Directory of Open Access Journals (Sweden)

    Göök Alf

    2016-01-01

    Full Text Available Investigations of prompt emission in fission is of importance in understanding the fission process in general and the sharing of excitation energy among the fission fragments in particular. Experimental activities at IRMM on prompt neutron emission from fission in response to OECD/NEA nuclear data requests is presented in this contribution. Main focus lies on currently on-going investigations of prompt neutron emission from the reaction 235U(n,f in the region of the resolved resonances. For this reaction strong fluctuations of fission fragment mass distributions and mean total kinetic energy have been observed [Nucl. Phys. A 491, 56 (1989] as a function of incident neutron energy in the resonance region. In addition fluctuations of prompt neutron multiplicities were also observed [Phys. Rev. C 13, 195 (1976]. The goal of the present study is to verify the current knowledge of prompt neutron multiplicity fluctuations and to study correlations with fission fragment properties.

  20. Effect of insulator sleeve length on neutron emission in a plasma focus

    International Nuclear Information System (INIS)

    Neutron emission from a small Mather-type plasma focus facility operated by a single 32 μF, 15 kV capacitor is studied. Specifically, the effects of insulator sleeve length and a ''ceiling'' introduced in front of the central electrode on the neutron yield and on the fluence anisotropy are investigated. (orig.)

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

    Science.gov (United States)

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

    2016-11-01

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

  2. Neutrino emissivity from Goldstone boson decay in magnetized neutron matter

    OpenAIRE

    Bedaque, Paulo; Sen, Srimoyee

    2013-01-01

    Neutron matter at densities somewhat above nuclear densities is believed to be superfluid due to the condensation of neutron pairs in the 3 P2 channel. This condensate breaks rotational symmetry spontaneously and leads to the existence of Goldstone bosons (angulons). We show that the coupling to magnetic fields mediated by the magnetic moment of the neutron makes angulons massive and capable of decaying into a neutrino-antineutrino pair. We compute the rate for this process and argue they bec...

  3. Strategy for the absolute neutron emission measurement on ITER.

    Science.gov (United States)

    Sasao, M; Bertalot, L; Ishikawa, M; Popovichev, S

    2010-10-01

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10(10) n/s (neutron/second) for DT and 10(8) n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  4. Strategy for the absolute neutron emission measurement on ITER

    International Nuclear Information System (INIS)

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 1010 n/s (neutron/second) for DT and 108 n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  5. Neutron time-of-flight and emission time diagnostics for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, T. J.; Jimerson, J. L.; Berggren, R. R.; Faulkner, J. R.; Oertel, J. A.; Walsh, P. J.

    2001-01-01

    Current plans call for a system of current mode neutron detectors for the National Ignition Facility for extending the range of neutron yields below that of the neutron activation system, for ion-temperature measurements over a wide yield range, and for determining the average neutron emission time. The system will need to operate over a yield range of 10{sup 6} for the lowest-yield experiments to 10{sup 19} for high-yield ignited targets. The requirements will be satisfied using several detectors located at different distances from the target. This article presents a conceptual design for the NIF nToF system.

  6. Neutron emission in 19F+181Ta reaction at 150 MeV

    International Nuclear Information System (INIS)

    In this work we concentrate on the HMS Model and the ALICE 2014 code. In fact one of the aims of the present study is to produce new data that will provide stringent test of the code. Neutron emission and light charged particle emission are useful tools for such a study. In the experiment we measured both neutron and charged particle spectra for a range of targets, and at three 19F beam energies. In this contribution we present the angle-dependent neutron spectra for 19F + 181Ta at beam energy of 150 MeV

  7. Dynamics and gravitational-wave emission of neutron-star merger remnants

    CERN Document Server

    Bauswein, A; Stergioulas, N; Janka, H -T

    2016-01-01

    The coalescence of a neutron-star binary is likely to result in the formation of a neutron-star merger remnant for a large range of binary mass configurations. The massive merger remnant shows strong oscillations, which are excited by the merging process, and emits gravitational waves. Here we discuss possibilities and prospects of inferring unknown stellar properties of neutron stars by the detection of postmerger gravitational-wave emission, which thus leads to constraints of the equation of state of high-density matter. In particular, the dominant oscillation frequency of the postmerger remnant provides tight limits to neutron-star radii. We mention first steps towards a practical implementation of future gravitational-wave searches for the postmerger emission. Moreover, we outline possibilities to estimate the unknown maximum mass of nonrotating neutron stars from such types of measurements. Finally, we review the origin and scientific implications of secondary peaks in the gravitational-wave spectrum of ...

  8. MCNP calculations of neutron emission anisotropy caused by the GIT-12 hardware

    Directory of Open Access Journals (Sweden)

    Šíla Ondřej

    2015-06-01

    Full Text Available The MCNP6 and MCNPX calculations for the GIT-12 device in Tomsk were performed to determine the influence of the gas-puff hardware on the neutron emission anisotropy and the neutron scattering rate. A monoenergetic 2.45 MeV neutron source and F1 and F6 tallies were declared in the simulation input. A comparison between MCNP results and the measured data was made. Differences between MCNPX and MCNP6 output data were investigated. In the experiment, two nTOF scintillation detectors with the Bicron BC-408 scintillator were used to measure the neutron waveform. Four bubble BD-PND detectors were used to estimate the amount of neutrons in different places around the neutron source.

  9. Beta-delayed gamma and proton spectroscopy near the Z=N line

    Energy Technology Data Exchange (ETDEWEB)

    Kankainen, A.; Eronen, T.; Hager, U.; Hakala, J.; Huang, W.; Huikari, J.; Jokinen, A.; Kopecky, S.; Moore, I.; Nieminen, A.; Penttilae, H.; Rinta-Antila, S.; Wang, Y.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, Jyvaeskylae (Finland); Eliseev, S.A. [Petersburg Nuclear Physics Inst. (Russian Federation); GSI, Darmstadt (Germany); Fox, S.P.; Jenkins, D. [University of York, Department of Physics, Heslington (United Kingdom); Novikov, Yu.N.; Vorobjev, G.K. [Petersburg Nuclear Physics Inst. (Russian Federation); St. Petersburg Univ. (Russian Federation); Popov, A.V.; Seliverstov, D.M. [Petersburg Nuclear Physics Institute, Petersburg (Russian Federation); Schatz, H. [Michigan State University, East Lansing, MI (United States)

    2005-09-01

    A series of beta decay experiments on nuclei near the Z=N line has been performed using the ISOL technique at the IGISOL facility in Jyvaeskylae and at ISOLDE, CERN. The decay properties of these neutron-deficient nuclei are important in astrophysics as well as in the studies of isospin symmetry. (orig.)

  10. $\\beta$-decay study of neutron-rich Tl and Pb isotopes

    CERN Multimedia

    It is proposed to study the structure of neutron-rich nuclei beyond $^{208}$Pb. The one-proton hole $^{211-215}$Tl and the semi magic $^{213}$Pb will be produced and studied via nuclear and atomic spectroscopy searching for long-lived isomers and investigating the $\\beta$-delayed $\\gamma$- emission to build level schemes. Information on the single particle structure in $^{211-215}$Pb, especially the position of the g$_{9/2}$ and i$_{11/2}$ neutron orbitals, will be extracted along with lifetimes. The $\\beta$-decay will be complemented with the higher spin selectivity that can be obtained by resonant laser ionization to single-out the decay properties of long-living isomers in $^{211,213}$Tl and $^{213}$Pb.

  11. MONDO: A neutron tracker for particle therapy secondary emission fluxes measurements

    Science.gov (United States)

    Marafini, M.; Patera, V.; Pinci, D.; Sarti, A.; Sciubba, A.; Spiriti, E.

    2016-07-01

    Cancer treatment is performed, in Particle Therapy, using accelerated charged particles whose high irradiation precision and conformity allows the tumor destruction while sparing the surrounding healthy tissues. Dose release monitoring devices using photons and charged particles produced by the beam interaction with the patient body have already been proposed, but no attempt based on the detection of the abundant secondary radiation neutron component has been made yet. The reduced attenuation length of neutrons yields a secondary particle sample that is larger in number when compared to photons and charged particles. Furthermore, neutrons allow for a backtracking of the emission point that is not affected by multiple scattering. Since neutrons can release a significant dose far away from the tumor region, a precise measurement of their flux, production energy and angle distributions is eagerly needed in order to improve the Treatment Planning Systems (TPS) software, so to predict not only the normal tissue toxicity in the target region but also the risk of late complications in the whole body. All the aforementioned issues underline the importance for an experimental effort devoted to the precise characterization of the neutron production gaining experimental access both to the emission point and production energy. The technical challenges posed by a neutron detector aiming for a high detection efficiency and good backtracking precision will be addressed within the MONDO (MOnitor for Neutron Dose in hadrOntherapy) project. The MONDO's main goal is to develop a tracking detector targeting fast and ultrafast secondary neutrons. The tracker is composed by a scintillating fiber matrix (4 × 4 × 8cm3). The full reconstruction of protons, produced in elastic interactions, will be used to measure energy and direction of the impinging neutron. The neutron tracker will measure the neutron production yields, as a function of production angle and energy, using different

  12. Influence of Neutron Shell Closure (Nc=126) on Prescission Particle Emission of Fissioning Systems 216,224Th

    Institute of Scientific and Technical Information of China (English)

    叶巍

    2003-01-01

    The effect of neutron shell closure Nc = 126 on the prescission-particle emission of 216Th and 224Th nuclei is investigated within the framework of an extensive Smoluchowski equation. It is found that there is a large difference in the prescission neutron multiplicity for the two Th nuclei, indicating a strong shell effect in neutron emission. Moreover, shell effects on particle emission are also investigated as functions of excitation energy,angular momentum and nuclear viscosity. The results show that with increasing excitation energy shell effects in prefission neutron evolve from continual strength to gradual weakness. Both high angular momenta and low viscosity weaken the shell effects on the particle emission.

  13. Low-Energy X-ray Emission from Young Isolated Neutron Stars

    CERN Document Server

    Ruderman, M

    2003-01-01

    A young neutron star with large spin-down power is expected to be closely surrounded by an e+/- pair plasma maintained by the conversion of gamma-rays associated with the star's polar-cap and/or outer-gap accelerators. Cyclotron-resonance scattering by the e- and e+ within several radii of such neutron stars prevents direct observations of thermal X-rays from the stellar surface. Estimates are presented for the parameters of the Planck-like X-radiation which ultimately diffuses out through this region. Comparisons with observations, especially of apparent blackbody emission areas as a function of neutron star age, support the proposition that we are learning about a neutron star's magnetosphere rather than about its surface from observations of young neutron star thermal X-rays.

  14. Measurements of double-differential neutron emission cross sections of {sup 6}Li and {sup 7}Li for 18 MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ibaraki, Masanobu; Baba, Mamoru; Matsuyama, Shigeo; Sanami, Toshiya; Win, T.; Miura, Takako; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1997-03-01

    Double-differential neutron emission cross sections of {sup 6}Li and {sup 7}Li were measured for 18 MeV neutrons at Tohoku University 4.5 MV Dynamitron facility. Neutron emission spectra were obtained down to 1 MeV at 13 angles with energy resolution good enough to separate discrete levels. A care was taken to eliminate the sample-dependent background due to parasitic neutrons. Experimental results were in fair agreement with the JENDL-3.2 data and a simple model considering a three-body breakup process and discrete level excitations. (author)

  15. Neutrino emission due to Cooper-pair recombination in neutron stars reexamined

    International Nuclear Information System (INIS)

    Neutrino emission in processes of breaking and formation of neutron and proton Cooper pairs is calculated within the Larkin-Migdal-Leggett approach for a superfluid Fermi liquid. We demonstrate explicitly that the Fermi-liquid renormalization respects the Ward identity and ensures the weak vector-current conservation. The systematic expansion of the emissivities for small temperatures and nucleon Fermi velocity vF,i,i=n,p, is performed. Both neutron and proton processes are mainly controlled by the axial-vector current contributions, which are not strongly changed in the superfluid matter. Thus, compared to earlier calculations, the total emissivity of processes on neutrons paired in the 1S0 state is suppressed by a factor of ≅(0.9-1.2)vF,n2. A similar suppression factor (∼vF,p2) arises for processes on protons

  16. Neutrino Emission from Cooper Pairs and Minimal Cooling of Neutron Stars

    CERN Document Server

    Page, Dany; Prakash, Madappa; Steiner, Andrew W

    2009-01-01

    The minimal cooling paradigm for neutron star cooling assumes that enhanced cooling due to neutrino emission from any direct Urca process, due either to nucleons or to exotica such as hyperons, Bose condensates, or deconfined quarks, does not occur. This scenario was developed to replace and extend the so-called standard cooling scenario to include neutrino emission from the Cooper pair breaking and formation processes that occur near the critical temperature for superfluid/superconductor pairing. Recently, it has been found that Cooper-pair neutrino emission from the vector channel is suppressed by a large factor compared to the original estimates that violated vector current conservation. We show that Cooper-pair neutrino emission remains, nevertheless, an efficient cooling mechanism through the axial channel. As a result, the elimination of neutrino emission from Cooper-paired nucleons through the vector channel has only minor effects on the long-term cooling of neutron stars within the minimal cooling par...

  17. First-forbidden β -decay rates, energy rates of β -delayed neutrons and probability of β -delayed neutron emissions for neutron-rich nickel isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nabi, Jameel-Un; Iftikhar, Zafar [GIK Institute of Engineering Sciences and Technology, Faculty of Engineering Sciences, Khyber Pakhtunkhwa (Pakistan); Cakmak, Necla [Karabuek University, Department of Physics, Karabuek (Turkey)

    2016-01-15

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar β -decay rates, energy rate of β -delayed neutrons and probability of β -delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow. (orig.)

  18. First-forbidden β -decay rates, energy rates of β -delayed neutrons and probability of β -delayed neutron emissions for neutron-rich nickel isotopes

    International Nuclear Information System (INIS)

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar β -decay rates, energy rate of β -delayed neutrons and probability of β -delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow. (orig.)

  19. Neutron emission tomography for nuclear fissile materials safeguards

    International Nuclear Information System (INIS)

    Any nondestructive method for fissile assay in spent nuclear fuel must sample a substantial portion of the total number of reactor fuel elements to account for the radial and axial asymmetry of fissile material distribution that may arise during fuel burnup. Cross-sectional scans of the spatial distribution of the fissile isotopes can be tomographically reconstructed while a spent fuel element is being assayed in a lead slowing-down-time (SDT) spectrometer by employing image reconstruction techniques. The SDT approach employs threshold detectors (fission chambers), which measure the induced prompt fast fission neutrons emitted from the fissile isotopes in spent fuel while being interrogated with a slowing pulse of source neutrons. The objectives of this work were to examine to what extent a cross section representing an array of partially void (missing pins) and intact fuel pins could be reconstructed and how sensitive this method is to diversion, spatial burnup distribution, and gross fissile contents consistency

  20. A study on fast digital discrimination of neutron and gamma-ray for improvement neutron emission profile measurement

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Y., E-mail: h1312101@mailg.nc-toyama.ac.jp; Takada, E.; Fujisaki, A. [National Institute of Technology, Toyama College, 13 Hongo-machi, Toyama 939-8630 (Japan); Isobe, M. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); The Graduate University for Advanced Studies (SOKENDAI), 322-6 Oroshi-cho, Toki 509-5292 (Japan); Ogawa, K. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Shinohara, K. [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka 311-0913 (Japan); Tomita, H.; Kawarabayashi, J.; Iguchi, T. [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2014-11-15

    Neutron and γ-ray (n-γ) discrimination with a digital signal processing system has been used to measure the neutron emission profile in magnetic confinement fusion devices. However, a sampling rate must be set low to extend the measurement time because the memory storage is limited. Time jitter decreases a discrimination quality due to a low sampling rate. As described in this paper, a new charge comparison method was developed. Furthermore, automatic n-γ discrimination method was examined using a probabilistic approach. Analysis results were investigated using the figure of merit. Results show that the discrimination quality was improved. Automatic discrimination was applied using the EM algorithm and k-means algorithm.

  1. Colliding neutron stars --- Gravitational waves, neutrino emission, and gamma-ray bursts

    OpenAIRE

    Ruffert, Maximilian; Janka, H. -Thomas

    1998-01-01

    Three-dimensional hydrodynamical simulations are presented for the direct head-on or off-center collision of two neutron stars, employing a basically Newtonian PPM code but including the emission of gravitational waves and their back-reaction on the hydrodynamical flow. A physical nuclear equation of state is used that allows us to follow the thermodynamical evolution of the stellar matter and to compute the emission of neutrinos. Predicted gravitational wave signals, luminosities and wavefor...

  2. Surface emission from neutron stars and implications for the physics of their interiors.

    Science.gov (United States)

    Ozel, Feryal

    2013-01-01

    Neutron stars are associated with diverse physical phenomena that take place in conditions characterized by ultrahigh densities as well as intense gravitational, magnetic and radiation fields. Understanding the properties and interactions of matter in these regimes remains one of the challenges in compact object astrophysics. Photons emitted from the surfaces of neutron stars provide direct probes of their structure, composition and magnetic fields. In this review, I discuss in detail the physics that governs the properties of emission from the surfaces of neutron stars and their various observational manifestations. I present the constraints on neutron star radii, core and crust composition, and magnetic field strength and topology obtained from studies of their broadband spectra, evolution of thermal luminosity, and the profiles of pulsations that originate on their surfaces.

  3. Heterogeneity of solid neutron-star matter: transport coefficients and neutrino emissivity

    CERN Document Server

    Jones, P B

    2004-01-01

    Calculations of weak-interaction transition rates and of nuclear formation enthalpies show that in isolated neutron stars, the solid phase, above the neutron-drip threshold, is amorphous and heterogeneous in nuclear charge. The neutrino emissivities obtained are very dependent on the effects of proton shell structure but may be several orders of magnitude larger than the electron bremsstrahlung neutrino-pair emissivity at temperatures of 10^9 K. In this phase, electrical and thermal conductivities are much smaller than for a homogeneous bcc lattice. In particular, the reduced electrical conductivity, which is also temperature-independent, must have significant consequences for the evolution of high-multipole magnetic fields in neutron stars.

  4. Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus

    Science.gov (United States)

    Bielecki, J.; Giacomelli, L.; Kiptily, V.; Scholz, M.; Drozdowicz, K.; Conroy, S.; Craciunescu, T.; Kempenaars, M.

    2015-09-01

    A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape of normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET.

  5. Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus

    Energy Technology Data Exchange (ETDEWEB)

    Bielecki, J.; Scholz, M.; Drozdowicz, K. [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland); Giacomelli, L. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Istituto di Fisica del Plasma “P. Caldirola,” Milano (Italy); Kiptily, V.; Kempenaars, M. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Conroy, S. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Department of Physics and Astronomy, Uppsala University (Sweden); Craciunescu, T. [IAP, National Institute for Laser Plasma and Radiation Physics, Bucharest (Romania); Collaboration: EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2015-09-15

    A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape of normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET.

  6. Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus.

    Science.gov (United States)

    Bielecki, J; Giacomelli, L; Kiptily, V; Scholz, M; Drozdowicz, K; Conroy, S; Craciunescu, T; Kempenaars, M

    2015-09-01

    A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape of normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET. PMID:26429441

  7. Neutron Emission Characteristics of Two Mixed-Oxide Fuels: Simulations and Initial Experiments

    Energy Technology Data Exchange (ETDEWEB)

    D. L. Chichester; S. A. Pozzi; J. L. Dolan; M. Flaska; J. T. Johnson; E. H. Seabury; E. M. Gantz

    2009-07-01

    Simulations and experiments have been carried out to investigate the neutron emission characteristics of two mixed-oxide (MOX) fuels at Idaho National Laboratory (INL). These activities are part of a project studying advanced instrumentation techniques in support of the U.S. Department of Energy's Fuel Cycle Research and Development program and it's Materials Protection, Accounting, and Control for Transmutation (MPACT) campaign. This analysis used the MCNP-PoliMi Monte Carlo simulation tool to determine the relative strength and energy spectra of the different neutron source terms within these fuels, and then used this data to simulate the detection and measurement of these emissions using an array of liquid scintillator neutron spectrometers. These calculations accounted for neutrons generated from the spontaneous fission of the actinides in the MOX fuel as well as neutrons created via (alpha,n) reactions with oxygen in the MOX fuel. The analysis was carried out to allow for characterization of both neutron energy as well as neutron coincidences between multiple detectors. Coincidences between prompt gamma rays and neutrons were also analyzed. Experiments were performed at INL with the same materials used in the simulations to benchmark and begin validation tests of the simulations. Data was collected in these experiments using an array of four liquid scintillators and a high-speed waveform digitizer. Advanced digital pulse-shape discrimination algorithms were developed and used to collect this data. Results of the simulation and modeling studies are presented together with preliminary results from the experimental campaign.

  8. Axion cyclotron emissivity of magnetized white dwarfs and neutron stars

    OpenAIRE

    Kachelriess, M.; Wilke, C.; Wunner, G.

    1997-01-01

    The energy loss rate of a magnetized electron gas emitting axions a due to the process $e^- \\to e^- +a$ is derived for arbitrary magnetic field strength B. Requiring that for a strongly magnetized neutron star the axion luminosity is smaller than the neutrino luminosity we obtain the bound $g_{ae}\\lsim 10^{-10}$ for the axion electron coupling constant. This limit is considerably weaker than the bound derived earlier by Borisov and Grishina using the same method. Applying a similar argument t...

  9. Spin Response and Neutrino Emissivity of Dense Neutron Matter

    OpenAIRE

    Shen, G.; Gandolfi, S.; S. Reddy; Carlson, J.

    2012-01-01

    We study the spin response of cold dense neutron matter in the limit of zero momentum transfer, and show that the frequency dependence of the long-wavelength spin response is well constrained by sum-rules and the asymptotic behavior of the two-particle response at high frequency. The sum-rules are calculated using Auxiliary Field Diffusion Monte Carlo technique and the high frequency two-particle response is calculated for several nucleon-nucleon potentials. At nuclear saturation density, the...

  10. Measurement of double-differential neutron emission cross sections of 238U, 232Th and 12C for 18 MeV neutrons

    International Nuclear Information System (INIS)

    Double-differential neutron emission cross sections of 238U, 232Th and 12C have been measured for 18-MeV incident neutrons using the neutron time-of-flight technique and Tohoku University 4.5MV Dynamitron accelerator as a pulsed neutron generator. In the experiment, energy resolution of the spectrometer was improved by employing a newly developed post-acceleration beam-chopper and by adjustment of timing property of the neutron detector. Measurements were made at laboratory angles between 30- and 145- deg., and data were obtained for secondary neutrons between 0.8 and 18 MeV. In the data processing, a care was taken for the data correction for the effects of parasitic neutrons associated with primary neutrons; the correction proved to be of special importance in the present measurement. We compared the data obtained in the present experiment with the evaluated data, JENDL-3 and ENDF/B-IV (B-V for 12C), and discussed the origin of the discrepancies. The anisotropy observed for secondary neutrons from 238U and 232Th was found to be reproduced by Kalbach-Mann systematics on the assumption of isotropy of fission neutrons. The experimental results for 12C showed marked discrepancies concerning the scattering cross sections and neutron spectrum in the continuum region. (author)

  11. Measurements of double-differential neutron emission cross sections of Nb and Bi for 11.5 MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ibaraki, Masanobu; Matsuyama, Shigeo; Soda, Daisuke; Baba, Mamoru; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1997-03-01

    Double-differential neutron emission cross sections (DDXs) of Nb and Bi have been measured for 11.5MeV neutrons using the {sup 15N}(d,n){sup 16}O quasi-monoenergetic neutron source at Tohoku University 4.5MV Dynamitron facility. For En`>6MeV, DDXs were measured by the conventional TOF method (single-TOF:S-TOF). For En`<6MeV, where the S-TOF spectra were distorted by the background neutrons, we adopted a double-TOF method (D-TOF). By applying D-TOF method, we obtained DDXs down to 1MeV. (author)

  12. Tomographic analysis of data from the JET neutron profile monitor to deduce the 2-D spatial and temporal evolution of neutron emissivity

    International Nuclear Information System (INIS)

    Measurements from the JET neutron profile monitor are analyzed tomographically to deduce the two-dimensional spatial distribution of neutron emissivity and its temporal evolution. The most dramatic change in the emissivity profile is produced by a sawtooth crash. The profiles before and after a sawtooth crash are determined and changes in their characteristics, such as width and amplitude, are compared to those deduced from other diagnostics, including soft X-rays, electron density interferometers and electron cyclotron emission. The drop in the central neutron emissivity can be much larger than that obtained from the integrated global neutron emission, and hollow emissivity profiles are produced. The observed inversion radius is the same on neutron, soft X-ray, and electron temperature profiles. This hollow profile can be understood by observations of the soft X-ray emissivity on the fastest time-scale. A major theme of this paper is that much more information and understanding can be gained if several diagnostics are used together, with their different resolutions, time-scales and physical properties measured. (author). 12 refs, 5 figs

  13. Target screening effect on the pre-emission of neutrons from Li11 halo nuclei

    Science.gov (United States)

    Petrascu, M.; Constantinescu, A.; Cruceru, I.; Giurgiu, M.; Isbasescu, A.; Petrascu, H.; Bordeanu, C.; Serban, S.; Stoica, V.; Tanihata, I.; Lynch, W. G.; Famiano, M. A.; Lyuboshits, V. L.; Lyuboshits, V. V.; Ieki, K.

    2006-05-01

    For the first time to our knowledge the target screening effect on the pre-emission of halo neutrons from Li11 has been quantitatively analyzed. Our work has been performed in the 7.5 15 MeV neutron energy range. In this range the target nuclei are likely to behave as opaque, and therefore the sharp-cutoff calculations are most appropriate for the target screening determination. It has been observed that the ζ probability used in the sharp-cutoff calculations is an observable of the experiment, because it can be directly obtained from measured quantities, which are the number of single detected neutrons and the number of detected neutron pairs. The value of ζexp obtained this way in the case of a Si target appears to be close to the ζ value calculated for the Li11 halo radius RH=4.8 fm, independently determined in another experiment [Phys. Lett. B287, 307 (1992)]. This property also allows investigation of Borromean halo nuclei such as He6, Be14, and B17, for which RH was not yet measured. The calculated value within the present approach of the two-neutron pre-emission yield appears to be 3.5 times larger in the case of C12 than in the case of a Si target.

  14. Single photon image from position emission tomography with insertable collimator for boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Joo Young; Yoo, Do Kun; Suh, Tae Suk [Dept. of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul (Korea, Republic of); Hong, Key Jo [Molecular Imaging Program at Stanford (MIPS), Dept. of Radiology, Stanford University, Stanford (United States)

    2014-04-15

    The aim of our proposed system is to confirm the feasibility of extraction of two types of images from one positron emission tomography (PET) module with an insertable collimator for brain tumor treatment during the boron neutron capture therapy (BNCT). The BNCT theory and conceptual diagram of our proposed system are shown fig.1. Data from the PET module, neutron source, and collimator was entered in the Monte Carlon-particle extende source code. We attempted to acquire the PET and SPECT images simultaneously using only PET without an additional isotope. Single photon images were acquired using an insertable collimator on a PET detector.

  15. New Limits on Radio Emission from X-ray Dim Isolated Neutron Stars

    CERN Document Server

    Kondratiev, V I; Lorimer, D R; Burgay, M; Possenti, A; Turolla, R; Popov, S B; Zane, S

    2009-01-01

    We have carried out a search for radio emission at 820 MHz from six X-ray dim isolated neutron stars with the Robert C. Byrd Green Bank Radio Telescope. No transient or pulsed emission was found using fast folding, fast Fourier transform, and single-pulse searches. The corresponding flux limits are about 0.01 mJy for pulsed emission, depending on the integration time for the particular source and assuming a duty cycle of 2%, and 20 mJy for single dispersed pulses. These are the most sensitive limits to date on radio emission from X-ray dim isolated neutron stars. There is no evidence for isolated radio pulses, as seen in a class of neutron stars known as rotating radio transients. Our results imply that either the radio luminosities of these objects are lower than those of any known radio pulsars, or they could simply be long-period nearby radio pulsars with high magnetic fields beaming away from the Earth. To test the latter possibility, we would need around 40 similar sources to provide a 1 sigma probabilit...

  16. 232Th and 238U neutron emission cross section calculations and analysis of experimental data

    International Nuclear Information System (INIS)

    In this study, pre-equilibrium neutron-emission spectra produced by (n,xn) reactions on nuclei 232Th and 238U have been calculated. Angle-integrated cross sections in neutron induced reactions on targets 232Th and 238U have been calculated at the bombarding energies up to 18 MeV. We have investigated multiple pre-equilibrium matrix element constant from internal transition for 232Th (n,xn) neutron emission spectra. In the calculations, the geometry dependent hybrid model and the cascade exciton model including the effects of pre-equilibrium have been used. In addition, we have described how multiple pre-equilibrium emissions can be included in the Feshbach-Kerman-Koonin (FKK) fully quantum-mechanical theory. By analyzing (n,xn) reaction on 232Th and 238U, with the incident energy from 2 Me V to 18 Me V, the importance of multiple pre-equilibrium emission can be seen cleady. All calculated results have been compared with experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other

  17. Measurement of very neutron-rich r-process nuclei with the BELEN setup

    International Nuclear Information System (INIS)

    Full text: Very neutron-rich nuclei can emit neutrons after β--decay when their reaction Q-value is larger than the (one/two/three) neutron separation energy. This decay mode is called -delayed (one/two/three)-neutron emission and was discovered in 1939 by Roberts et al. [1], shortly after the discoveries of fission by Meitner, Hahn, and Strassmann in 1938, and the neutron by Chadwick in 1932. Delayed in this context means, that the neutron is emitted with the -decay half-life of the precursor AZ, ranging from few milliseconds for the most neutron-rich isotopes up to 55.65 s for the (up to now) longest-lived βn-precursor 87Br. These delayed neutrons have to be distinguished from the prompt neutrons evaporated immediately (in the order of 10-14 s) after a fission event from a neutron-rich nucleus. βn measurements are commonly carried out since many decades, especially for fission fragments. With present and future nuclear physics facilities more and more neutron-rich isotopes outside the fission region become accessible which can also emit multiple neutrons. This exotic decay mode is of special interest for the astrophysical rapid neutron capture process (r process) since it leads to a deviation of the reaction flow to lower mass chains during the freeze-out phase. The exact knowledge of the beta-delayed neutron emission probability (Pn) is required to interpret the observed solar abundance peaks and draw conclusions from this about the participating r-process progenitor isotopes and their contributions. The BELEN (BEta-deLayEd Neutron) detector with its state-of-the-art digital electronics is one of the most powerful setups for the measurement of β-delayed neutrons in the world. Its present version consists of 48 3He-filled long counters and achieves - depending on the design - a neutron detection efficiency of up to 60%. This high efficiency is necessary for the detection of very neutron-rich n-emitters as well as for the detection of multiple neutronemitters

  18. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    Science.gov (United States)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-01

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 × 10-5. The upper limit for the asymmetry coefficient has been set to | D n | < 6 × 10-5 at 99% confidence level, whereas for ternary fission correlation coefficient D α = (170±20) × 10-5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation coefficient was found to be (1.57 ± 0.20) × 10-4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt γ-rays.

  19. Models of Kilonova/macronova emission from black hole-neutron star mergers

    CERN Document Server

    Kawaguchi, Kyohei; Shibata, Masaru; Tanaka, Masaomi

    2016-01-01

    Black hole-neutron star mergers are among the promising gravitational-wave sources for ground-based detectors, and gravitational waves from black hole-neutron mergers are expected to be detected in the next few years. Simultaneous detection of electromagnetic counterparts with gravitational-wave detection provides rich information about the merger events. Among the possible electromagnetic counterparts from the black hole-neutron merger, the emission powered by the decay of radioactive r-process nuclei, so called kilonova/macronova, is one of the best targets for follow-up observation. We derive fitting formulas for the mass and the velocity of ejecta from a generic black hole-neutron merger based on recently performed numerical relativity simulations. We combined these fitting formulas with a new semi-analytic model for a black hole-neutron kilonova/macronova lightcurve which reproduces the results of radiation-transfer simulations. Specifically, the semi-analytic model reproduces the result of each band mag...

  20. Neural networks based neutron emissivity tomography at JET with real-time capabilities

    International Nuclear Information System (INIS)

    Tomographic reconstruction techniques typically require computationally intensive algorithms which are not suitable for real-time application. This paper describes a framework to perform neutron emissivity tomography at the Joint European Torus (JET) using neural networks with successful results over a broad range of magnetic configurations, heating and fueling schemes. Application times in the μs time scale allows for real-time applicability of the method.

  1. Heat Source Neutron Emission Rate Reduction Studies - Water Induced HF Liberation

    Science.gov (United States)

    Matonic, John; Brown, John; Foltyn, Liz; Garcia, Lawrence; Hart, Ron; Herman, David; Huling, Jeff; Pansoy-Hjelvik, M. E. Lisa; Sandoval, Fritz; Spengler, Diane

    2004-02-01

    Plutonium-238 oxide (238PuO2) is used in the fabrication of general purpose heat sources (GPHS) or light-weight radioisotope heater units (LWRHUs). The heat sources supply the thermal energy used in radioisotope thermoelectric generators to power spacecraft for deep space missions and to heat critical components in the cold environs of space. Los Alamos National Laboratory has manufactured heat sources for approximately two decades. The aqueous purification of 238PuO2 is required, due to rigorous total Pu-content, actinide and non-actinide metal impurity, and neutron emission rate specifications. The 238PuO2 aqueous purification process is a new capability at Los Alamos National Laboratory as previously, aqueous purified 238PuO2 occurred at other DOE complexes. The Pu-content and actinide and non-actinide metal impurity specifications are met well within specification in the Los Alamos process, though reduction in neutron emission rates have been challenging. High neutron emission rates are typically attributed to fluoride content in the oxide. The alpha decay from 238Pu results in α,n reactions with light elements such as 17O, 18O, and 19F resulting in high neutron emission rates in the purified 238PuO2. Simple 16O-exchange takes care of the high NER due to 17O, and 18O. A new method to reduce the NER due to 19F in the purified 238PuO2 is presented in this paper. The method involves addition of water to purified 238PuO2, followed by heating to remove the water and liberating fluoride as HF.

  2. Neural networks based neutron emissivity tomography at JET with real-time capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Ronchi, E., E-mail: emanuele.ronchi@tsl.uu.s [JET-EFDA, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Association EURATOM-VR, Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala (Sweden); Conroy, S.; Andersson Sunden, E.; Ericsson, G.; Gatu Johnson, M.; Hellesen, C.; Sjoestrand, H.; Weiszflog, M. [JET-EFDA, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Association EURATOM-VR, Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala (Sweden)

    2010-02-01

    Tomographic reconstruction techniques typically require computationally intensive algorithms which are not suitable for real-time application. This paper describes a framework to perform neutron emissivity tomography at the Joint European Torus (JET) using neural networks with successful results over a broad range of magnetic configurations, heating and fueling schemes. Application times in the mus time scale allows for real-time applicability of the method.

  3. Nuclear spectroscopy with Geant4: Proton and neutron emission & radioactivity

    Science.gov (United States)

    Sarmiento, L. G.; Rudolph, D.

    2016-07-01

    With the aid of a novel combination of existing equipment - JYFLTRAP and the TASISpec decay station - it is possible to perform very clean quantum-state selective, high-resolution particle-γ decay spectroscopy. We intend to study the determination of the branching ratio of the ℓ = 9 proton emission from the Iπ = 19/2-, 3174-keV isomer in the N = Z - 1 nucleus 53Co. The study aims to initiate a series of similar experiments along the proton dripline, thereby providing unique insights into "open quantum systems". The technique has been pioneered in case studies using SHIPTRAP and TASISpec at GSI. Newly available radioactive decay modes in Geant4 simulations are going to corroborate the anticipated experimental results.

  4. Estimates of the neutron emission during large solar flares in the rising and maximum period of solar cycle 24

    Science.gov (United States)

    Lopez, D.; Matsubara, Y.; Muraki, Y.; Sako, T.; Valdés-Galicia, J. F.

    2016-03-01

    We searched for solar neutrons using the data collected by six detectors from the International Network of Solar Neutron Telescopes and one Neutron Monitor between January 2010 and December 2014. We considered the peak time of the X-ray intensity of thirty five ≥ X1.0 class flares detected by GOES satellite as the most probable production time of solar neutrons. We prepared a light-curve of the solar neutron telescopes and the neutron monitor for each flare, spanning ± 3 h from the peak time of GOES. Based on these light curves, we performed a statistical analysis for each flare. Setting a significance level at greater than 3σ, we report that no statistically significant signals due to solar neutrons were found. Therefore, upper limits are determined by the background level and solar angle of these thirty five solar flares. Our calculation assumed a power-law neutron energy spectrum and an impulsive emission profile at the Sun. The estimated upper limits of the neutron emission are consistent within the order of magnitude of the successful detections of solar neutrons made in solar cycle 23.

  5. Theory of neutrino emission from nucleon-hyperon matter in neutron stars: angular integrals

    Science.gov (United States)

    Kaminker, A. D.; Yakovlev, D. G.; Haensel, P.

    2016-08-01

    Investigations of thermal evolution of neutron stars with hyperon cores require neutrino emissivities for many neutrino reactions involving strongly degenerate particles (nucleons, hyperons, electrons, muons). We calculate the angular integrals In (over orientations of momenta of n degenerate particles) for major neutrino reactions with n=3, 4, 5 at all possible combinations of particle Fermi momenta. The integrals In are necessary ingredients for constructing a uniform database of neutrino emissivities in dense nucleon-hyperon matter. The results can also be used in many problems of physical kinetics of strongly degenerate systems.

  6. Theory of neutrino emission from nucleon-hyperon matter in neutron stars: Angular integrals

    CERN Document Server

    Kaminker, A D; Haensel, P

    2016-01-01

    Investigations of thermal evolution of neutron stars with hyperon cores require neutrino emissivities for many neutrino reactions involving strongly degenerate particles (nucleons, hyperons, electrons, muons). We calculate the angular integrals $I_n$ (over orientations of momenta of $n$ degenerate particles) for major neutrino reactions with $n$ =3, 4, 5 at all possible combinations of particle Fermi momenta. The integrals $I_n$ are necessary ingredients for constructing a uniform database of neutrino emissivities in dense nucleon-hyperon matter. The results can also be used in many problems of physical kinetics of strongly degenerate systems.

  7. Electromagnetic and neutron emissions from brittle rocks failure: Experimental evidence and geological implications

    Indian Academy of Sciences (India)

    A Carpinteri; G Lacidogna; O Borla; A Manuello; G Niccolini

    2012-02-01

    It has been observed energy emission in the form of electromagnetic radiation, clearly indicating charge redistribution, and neutron bursts, necessarily involving nuclear reactions, during the failure process of quasi-brittle materials such as rocks, when subjected to compression tests. The material used is Luserna stone, which presents a very brittle behaviour during compression failure. The observed phenomenon of high-energy particle emission, i.e., electrons and neutrons, can be explained in the framework of the superradiance applied to the solid state, where individual atoms lose their identity and become part of different plasmas, electronic and nuclear. Since the analysed material contains iron, it can be conjectured that piezonuclear reactions involving fission of iron into aluminum, or into magnesium and silicon, should have occurred during compression damage and failure. These complex phenomenologies are confirmed by Energy Dispersive X-ray Spectroscopy (EDS) tests conducted on Luserna stone specimens, and found additional evidences at the Earth’s Crust scale, where electromagnetic and neutron emissions are observed just in correspondence with major earthquakes. In this context, the effects of piezonuclear reactions can be also considered from a geophysical and geological point of view.

  8. Probing Shell Correction at High Spin by Neutron Emission of Doubly Magic Nuclei 208pb and 132Sn

    Institute of Scientific and Technical Information of China (English)

    YEWei

    2005-01-01

    Shell effects in particle emission for two doubly magic nuclei 132Sn and 208pb were studied in the framework of Smoluchowski equation taking into account temperature and spin-dependent shell correction. It is shown that the shelle ffects in the emission of pre-scission neutrons are sensitive to the spin dependence of the shell correction at a moderate excitation energy. Therefore, we propose to use neutron multiplicity as an observable to probe the shell correction at high spins.

  9. Impact of new data for neutron-rich heavy nuclei on theoretical models for $r$-process nucleosynthesis

    CERN Document Server

    Kajino, Toshitaka

    2016-01-01

    Current models for the $r$ process are summarized with an emphasis on the key constraints from both nuclear physics measurements and astronomical observations. In particular, we analyze the importance of nuclear physics input such as beta-decay rates; nuclear masses; neutron-capture cross sections; beta-delayed neutron emission; probability of spontaneous fission, beta- and neutron-induced fission, fission fragment mass distributions; neutrino-induced reaction cross sections, etc. We highlight the effects on models for $r$-process nucleosynthesis of newly measured $\\beta$-decay half-lives, masses, and spectroscopy of neutron-rich nuclei near the $r$-process path. We overview r-process nucleosynthesis in the neutrino driven wind above the proto-neutron star in core collapse supernovae along with the possibility of magneto-hydrodynamic jets from rotating supernova explosion models. We also consider the possibility of neutron star mergers as an r-process environment. A key outcome of newly measured nuclear prope...

  10. Low mass binary neutron star mergers: Gravitational waves and neutrino emission

    Science.gov (United States)

    Foucart, Francois; Haas, Roland; Duez, Matthew D.; O'Connor, Evan; Ott, Christian D.; Roberts, Luke; Kidder, Lawrence E.; Lippuner, Jonas; Pfeiffer, Harald P.; Scheel, Mark A.

    2016-02-01

    Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients powered by r-process nucleosynthesis in neutron-rich material ejected by the merger, and radio emission from the interaction of that ejecta with the interstellar medium. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and postmerger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the Spectral Einstein Code to simulate the merger of low mass neutron star binaries (two 1.2 M⊙ neutron stars) for a set of three nuclear-theory-based, finite temperature equations of state. We show that the frequency peaks of the postmerger gravitational wave signal are in good agreement with predictions obtained from recent simulations using a simpler treatment of gravity. We find, however, that only the fundamental mode of the remnant is excited for long periods of time: emission at the secondary peaks is damped on a millisecond time scale in the simulated binaries. For such low mass systems, the remnant is a massive neutron star which, depending on the equation of state, is either permanently stable or long lived (i.e. rapid uniform rotation is sufficient to prevent its collapse). We observe strong excitations of l =2 , m =2 modes, both in the massive neutron star and in the form of hot, shocked tidal arms in the surrounding accretion torus. We estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk

  11. Part I: $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with astatine beams; Part II: Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

    CERN Document Server

    Andreyev, Andrei

    2013-01-01

    Part I: $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with astatine beams; Part II: Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

  12. The Statistics of Emission and Detection of Neutrons and Photons from Fissile Samples for Safeguard Applications

    Energy Technology Data Exchange (ETDEWEB)

    Enqvist, Andreas

    2008-03-15

    One particular purpose of nuclear safeguards, in addition to accounting for known materials, is the detection, identifying and quantifying unknown material, to prevent accidental and clandestine transports and uses of nuclear materials. This can be achieved in a non-destructive way through the various physical and statistical properties of particle emission and detection from such materials. This thesis addresses some fundamental aspects of nuclear materials and the way they can be detected and quantified by such methods. Factorial moments or multiplicities have long been used within the safeguard area. These are low order moments of the underlying number distributions of emission and detection. One objective of the present work was to determine the full probability distribution and its dependence on the sample mass and the detection process. Derivation and analysis of the full probability distribution and its dependence on the above factors constitutes the first part of the thesis. Another possibility of identifying unknown samples lies in the information in the 'fingerprints' (pulse shape distribution) left by a detected neutron or photon. A study of the statistical properties of the interaction of the incoming radiation (neutrons and photons) with the detectors constitutes the second part of the thesis. The interaction between fast neutrons and organic scintillation detectors is derived, and compared to Monte Carlo simulations. An experimental approach is also addressed in which cross correlation measurements were made using liquid scintillation detectors. First the dependence of the pulse height distribution on the energy and collision number of an incoming neutron was derived analytically and compared to numerical simulations. Then an algorithm was elaborated which can discriminate neutron pulses from photon pulses. The resulting cross correlation graphs are analyzed and discussed whether they can be used in applications to distinguish possible

  13. The Statistics of Emission and Detection of Neutrons and Photons from Fissile Samples for Safeguard Applications

    International Nuclear Information System (INIS)

    One particular purpose of nuclear safeguards, in addition to accounting for known materials, is the detection, identifying and quantifying unknown material, to prevent accidental and clandestine transports and uses of nuclear materials. This can be achieved in a non-destructive way through the various physical and statistical properties of particle emission and detection from such materials. This thesis addresses some fundamental aspects of nuclear materials and the way they can be detected and quantified by such methods. Factorial moments or multiplicities have long been used within the safeguard area. These are low order moments of the underlying number distributions of emission and detection. One objective of the present work was to determine the full probability distribution and its dependence on the sample mass and the detection process. Derivation and analysis of the full probability distribution and its dependence on the above factors constitutes the first part of the thesis. Another possibility of identifying unknown samples lies in the information in the 'fingerprints' (pulse shape distribution) left by a detected neutron or photon. A study of the statistical properties of the interaction of the incoming radiation (neutrons and photons) with the detectors constitutes the second part of the thesis. The interaction between fast neutrons and organic scintillation detectors is derived, and compared to Monte Carlo simulations. An experimental approach is also addressed in which cross correlation measurements were made using liquid scintillation detectors. First the dependence of the pulse height distribution on the energy and collision number of an incoming neutron was derived analytically and compared to numerical simulations. Then an algorithm was elaborated which can discriminate neutron pulses from photon pulses. The resulting cross correlation graphs are analyzed and discussed whether they can be used in applications to distinguish possible sample

  14. Detailed Study of the Angular Correlations in the Prompt Neutron Emission in Spontaneous Fission of 252Cf

    Science.gov (United States)

    Kopatch, Yu.; Chietera, A.; Stuttgé, L.; Gönnenwein, F.; Mutterer, M.; Gagarski, A.; Guseva, I.; Chernysheva, E.; Dorvaux, O.; Hambsch, F.-J.; Hanappe, F.; Mezentseva, Z.; Telezhnikov, S.

    An experiment has been performed at IPHC Strasbourg, aimed at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf. Fission fragments were measured by the angle-sensitive double ionization chamber CODIS while neutrons were detected by a set of 60 DEMON scintillator counters. The main aim of the experiment is the observation of the correlation between the fragment spins and neutron emission anisotropy. Preliminary results, based on the Monte-Carlo simulations, as well as the preliminary analysis of the experimental data are shown.

  15. Landau quantization and neutron emissions by nuclei in the crust of a magnetar

    Science.gov (United States)

    Chamel, N.; Mutafchieva, Y. D.; Stoyanov, Zh K.; Mihailov, L. M.; Pavlov, R. L.

    2016-06-01

    Magnetars are neutron stars endowed with surface magnetic fields of the order of 1014 - 1015 G, and with presumably much stronger fields in their interior. As a result of Landau quantization of electron motion, the neutron-drip transition in the crust of a magnetar is shifted to either higher or lower densities depending on the magnetic field strength. The impact of nuclear uncertainties is explored considering the recent series of Brussels-Montreal microscopic nuclear mass models. All these models are based on the Hartree-Fock-Bogoliubov method with generalized Skyrme functionals. They differ in their predictions for the symmetry energy coefficient at saturation, and for the stiffness of the neutron-matter equation of state. For comparison, we have also considered the very accurate but more phenomenological model of Duflo and Zuker. Although the equilibrium composition of the crust of a magnetar and the onset of neutron emission are found to be model dependent, the quantum oscillations of the threshold density are essentially universal.

  16. Landau quantization and neutron emissions by nuclei in the crust of a magnetar

    CERN Document Server

    Chamel, N; Stoyanov, Zh K; Mihailov, L M; Pavlov, R L

    2016-01-01

    Magnetars are neutron stars endowed with surface magnetic fields of the order of $10^{14}-10^{15}$~G, and with presumably much stronger fields in their interior. As a result of Landau quantization of electron motion, the neutron-drip transition in the crust of a magnetar is shifted to either higher or lower densities depending on the magnetic field strength. The impact of nuclear uncertainties is explored considering the recent series of Brussels-Montreal microscopic nuclear mass models. All these models are based on the Hartree-Fock-Bogoliubov method with generalized Skyrme functionals. They differ in their predictions for the symmetry energy coefficient at saturation, and for the stiffness of the neutron-matter equation of state. For comparison, we have also considered the very accurate but more phenomenological model of Duflo and Zuker. Although the equilibrium composition of the crust of a magnetar and the onset of neutron emission are found to be model dependent, the quantum oscillations of the threshold...

  17. Production and characterization of 228Th calibration sources with low neutron emission for GERDA

    Science.gov (United States)

    Baudis, L.; Benato, G.; Carconi, P.; Cattadori, C.; De Felice, P.; Eberhardt, K.; Eichler, R.; Petrucci, A.; Tarka, M.; Walter, M.

    2015-12-01

    The GERDA experiment at the Laboratori Nazionali del Gran Sasso (LNGS) searches for the neutrinoless double beta decay of 76Ge. In view of the GERDA Phase II data collection, four new 228Th radioactive sources for the calibration of the germanium detectors enriched in 76Ge have been produced with a new technique, leading to a reduced neutron emission rate from (α, n) reactions. The gamma activities of the sources were determined with a total uncertainty of ~4% using an ultra-low background HPGe detector operated underground at LNGS. The neutron emission rate was determined using a low background LiI(Eu) detector and a 3He counter at LNGS. In both cases, the measured neutron activity is ~10-6 n/(sṡBq), with a reduction of about one order of magnitude with respect to commercially available 228Th sources. Additionally, a specific leak test with a sensitivity to leaks down to ~10 mBq was developed to investigate the tightness of the stainless steel capsules housing the sources after their use in cryogenic environment.

  18. Production and characterization of 228Th calibration sources with low neutron emission for GERDA

    International Nuclear Information System (INIS)

    The GERDA experiment at the Laboratori Nazionali del Gran Sasso (LNGS) searches for the neutrinoless double beta decay of 76Ge. In view of the GERDA Phase II data collection, four new 228Th radioactive sources for the calibration of the germanium detectors enriched in 76Ge have been produced with a new technique, leading to a reduced neutron emission rate from (α, n) reactions. The gamma activities of the sources were determined with a total uncertainty of ∼4% using an ultra-low background HPGe detector operated underground at LNGS. The neutron emission rate was determined using a low background LiI(Eu) detector and a 3He counter at LNGS. In both cases, the measured neutron activity is ∼10−6 n/(s⋅Bq), with a reduction of about one order of magnitude with respect to commercially available 228Th sources. Additionally, a specific leak test with a sensitivity to leaks down to ∼10 mBq was developed to investigate the tightness of the stainless steel capsules housing the sources after their use in cryogenic environment

  19. Effect of pre-equilibrium emission on probing postsaddle nuclear dissipation with neutrons

    Science.gov (United States)

    Tian, Jian; Ye, Wei

    2016-09-01

    Using the stochastic Langevin model coupled with a statistical decay model, we study the influence of pre-equilibrium (PE) emission on probing postsaddle friction (β) with neutrons. A postsaddle friction value of (14 - 16.5) × 1021 s-1 and (11 - 13) × 1021 s-1 is obtained from comparing calculated and measured prescission neutron multiplicities of heavy fissioning systems 248Fm and 256Fm in the absence and presence of the deformation factor. Moreover, it is found that a larger β is required to fit multiplicity data after the PE effect is accounted for, and that the effect becomes stronger when more energy is removed by PE particles. Our findings suggest that, to more accurately determine the postsaddle friction strength through the measurement of prescission neutrons, in addition to incorporating the contribution of PE evaporation source into the experimental multi-source analysis for particle energy spectra in coincidence with fission fragments, on the theoretical side, it is very important to make a precise evaluation of the energy that PE emission carries away from excited compound systems produced in heavy-ion fusion reactions. Supported by National Nature Science Foundation of China (11575044)

  20. Low mass binary neutron star mergers : gravitational waves and neutrino emission

    CERN Document Server

    Foucart, Francois; Duez, Matthew D; O'Connor, Evan; Ott, Christian D; Roberts, Luke; Kidder, Lawrence E; Lippuner, Jonas; Pfeiffer, Harald P; Scheel, Mark A

    2015-01-01

    Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients, and radio emission. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and post-merger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the SpEC code to simulate the merger of low-mass neutron star binaries (two $1.2M_\\odot$ neutron stars) for a set of three nuclear-theory based, finite temperature equations of state. We show that the frequency peaks of the post-merger gravitational wave signal are in good agreement with predictions obtained from simulations using a simpler treatment of gravity. We find, however, that only the fundamental mode of the remnant is excited for long periods of time: emission at the secondary peaks is damped on a milli...

  1. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    International Nuclear Information System (INIS)

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (

  2. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Science.gov (United States)

    Spinella, William M.; Weber, Fridolin; Contrera, Gustavo A.; Orsaria, Milva G.

    2016-03-01

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (lesssim10^9 K) and quark fractions (lesssim 30% , and that contributions due to lattice vibrations are insignificant compared to static-lattice contributions.

  3. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Spinella, William M. [Computational Science Research Center San Diego State University, San Diego, CA (United States); San Diego State University, Department of Physics, San Diego, CA (United States); Weber, Fridolin [San Diego State University, Department of Physics, San Diego, CA (United States); University of California San Diego, Center for Astrophysics and Space Sciences, La Jolla, CA (United States); Contrera, Gustavo A. [CONICET, Buenos Aires (Argentina); CONICET - Dept. de Fisica, UNLP, IFLP, La Plata (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina); Orsaria, Milva G. [CONICET, Buenos Aires (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina)

    2016-03-15

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (

  4. Diabaticity in heavy-ion collisions and its role in non-equilibrium neutron emission

    International Nuclear Information System (INIS)

    Slow collective nuclear motions such as heavy-ion collision slightly above the Coulomb barrier and induced nuclear fission imply collective velocities. In the vicinity of quasi-crossings of adiabatic levels the nuclear single-particle motion changes completely. A nucleon in the lower level before the crossing will find itself in the upper level if this has been unoccupied before and the nucleon will stay in the diabatic level. The diabatic potential now corresponds to the extra energy pumped into the system due to the diabatic production of particle-hole state. An interesting aspect of diabatic s.p. states is their connection with non-equilibrium neutron or proton emission in heavy-ion collisions. Several neutrons could be emitted of the s.p. states to the collective motion which produces highly excited s.p. states

  5. Neutron star population in the Galactic center region as a potential source of polarized X-ray emission

    Science.gov (United States)

    Zajacek, Michal; Karas, Vladimir; Eckart, Andreas

    2016-06-01

    We analyse the emission properties of neutron stars that are predicted to exist in large numbers of the order of 10000 in the innermost parts of the Galactic center. A part of the population of isolated neutron stars propagates supersonically through denser ionized streams of the Minispiral (Sgr A West), forming bow shocks where particles are accelerated and are expected to produce polarized X-ray synchrotron signal. Another source of the synchrotron emission is an elongated magnetosphere and tail. We investigate whether the polarized X-ray emission from Galactic center neutron stars will be potentially detectable in the framework of future X-ray polarimeters. A special case is a detected young neutron star - magnetar SGRJ1745-2900 - that has undergone a series of outbursts with a peak X-ray luminosity of the order of 10^{35} erg s^{-1} (1-10 keV). Apart from an intrinsic X-ray emission, the X-ray emission from neutron star outbursts may be scattered by molecular clouds in the Central Molecular Zone by Thomson scattering, which is another potential source of polarized X-ray emission.

  6. Neutron yields and emission rates in the forward direction for 50MeV/u 18O—ion on thick Be,Cu,Au targets

    Institute of Scientific and Technical Information of China (English)

    LiGui-Sheng; ZhangTian-Mei; 等

    1997-01-01

    Total neutron yields and neutron emission rates in the forward direction for 50MeV/u 18O-ion on thick Be,Cu,Au targets have been measured using an activation technique.The results indicate that neutron yields and emission rates in the forward direction depend on the atomic number of target nuclei,i.e.the lighter target the greater neurtron yield and neutron emission rate.Meanwhile,the neutron yield of 18O-ion is greater than that of 12C-ion when target nucleus and incident energy per nucleon are identical.

  7. Gamma Emission Spectra from Neutron Resonances in 234,236,238U Measured Using the Dance Detector at Lansce

    Science.gov (United States)

    Ullmann, J. L.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wouters, J. M.; Wilhelmy, J. B.; Wu, C. Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

    2013-03-01

    An accurate knowledge of the radiative strength function and level density is needed to calculate of neutron-capture cross sections. An additional constraint on these quantities is provided by measurements of γ-ray emission spectra following capture. We present γ-emission spectra from several neutron resonances in 234,236,238U, measured using the DANCE detector at LANSCE. The measurements are compared to preliminary calculations of the cascade. It is observed that the generalized Lorentzian form of the E1 strength function cannot reproduce the shape of the emission spectra, but a better description is made by adding low-lying M1 Lorentzian strength.

  8. Determination of the elemental distribution in a sample using neutron induced gamma-ray emission tomography

    International Nuclear Information System (INIS)

    The factors that affect accurate, quantitative results to be obtained by neutron induced gamma-ray emission tomography are stated. The technique, which is a combination of neutron activation analysis with computerised gamma-ray emission tomography, would be enhanced by the use of multiple detector assemblies, in geometrical configurations, which simultaneously record the gamma-rays emitted and improve detection efficiency. Developments in the past few years in positron emission tomography (PET) where scanners made of single scintillation block detectors, cut into smaller segments, to form individual crystal detector elements and packed in ring around the radioactive object, are discussed. The coincident detection efficiency for annihilation photons and cascade gamma-rays for such systems are considered and the possibilities of carrying out NIGET with coincident gamma-ray tomography are explored whilst indicating some of the limitations. This is an area which requires further, intense investigation and has an impact on a wide range of applications, particularly in the biomedical field. (author)

  9. A search for neutron single-particle states populated via proton emission from 146Tm

    International Nuclear Information System (INIS)

    We studied the proton emission from 69145Tm77 and observed three new transitions. New transitions at 0.89 and 0.93 MeV have half-lives similar to that of the previously observed transition at 1.19 MeV, while a new transition at 1.02 MeV has a half-life similar to that of the previously observed transition at 1.12 MeV. These new transitions indicate the population of excited neutron single-particle states in 68145Er77

  10. Neutron-stimulated emission computed tomography of a multi-element phantom

    Energy Technology Data Exchange (ETDEWEB)

    Floyed, Carey E Jr; Kapadia, Anuj J; Sharma, Amy C; Xia, Jessie Q; Harrawood, Brian P; Tourassi, Georgia D; Lo, Joseph Y [Department of Radiology, Duke Advanced Imaging Laboratories, Durham, NC 27705 (United States); Bender, Janelle E [Department of Biomedical Engineering, Duke University, Durham, NC 27708 (United States); Crowell, Alexander S; Kiser, Mathew R; Howell, Calvin R [Department of Physics, Duke University, Durham, NC 27706 (United States)], E-mail: anuj.kapadia@duke.edu

    2008-05-07

    This paper describes the implementation of neutron-stimulated emission computed tomography (NSECT) for non-invasive imaging and reconstruction of a multi-element phantom. The experimental apparatus and process for acquisition of multi-spectral projection data are described along with the reconstruction algorithm and images of the two elements in the phantom. Independent tomographic reconstruction of each element of the multi-element phantom was performed successfully. This reconstruction result is the first of its kind and provides encouraging proof of concept for proposed subsequent spectroscopic tomography of biological samples using NSECT.

  11. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Danilyan, G. V. [Institute for Theoretical and Experimental Physics (Russian Federation); Klenke, J. [Forschungs-Neutronenquelle Heinz Meier-Leibnitz (FRM II) (Germany); Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B. [Institute for Theoretical and Experimental Physics (Russian Federation)

    2011-05-15

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -5}. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt {gamma}-rays.

  12. Probing Shell Correction at High Spin by Neutron Emission of Doubly Magic Nuclei 208pb and 132Sn

    Institute of Scientific and Technical Information of China (English)

    YE Wei

    2005-01-01

    Shell effects in particle emission for two doubly magic nuclei 132 Sn and 208 Pb were studied in the framework of Smoluchowski equation taking into account temperature and spin-dependent shell correction. It is shown that the shell effects in the enission of pre-scission neutrons are sensitive to the spin dependence of the shell correction at a moderate excitation energy. Therefore, we propose to use neutron multiplicity as an observable to probe the shell correction at high spins.

  13. Neutron and gamma emission in the fusion reaction 86Kr + 76Ge at 3,8 MeV/u

    International Nuclear Information System (INIS)

    In the present thesis the neutron and gamma emission of Compound nuclei with high excitation energy and large maximal angular momenta was studied, which are formed in fusion reactions with heavy ions. Thereby the system 86Kr + 76Ge was studied at a beam energy of 3.8 MeV/u, because here intermediate mass product nuclei arise for which the neutron emission is the dominant particle channel. For the neutron detection a detector arrangement was developed, which consistent of several NE213 liquid scintillators constructed in the Institute for Nuclear Physics. A separation of neutrons and gamma quanta is possible by pulse shape discrimination. For the determination of energy and angular distribution of the emitted neutrons 8 of these detectors were put under angles from 00 to 1050 in distances between 30 and 50 cm from the target. A further NE 213 detector of larger volume was put at -900 in 6 cm distance from the target and applied for the detection of neutrons and gamma quanta in coincidence. By this preferently events with high neutron respectively gamma multiplicity corresponding to low and high angular momentum ranges of the compound nucleus can be filtered out. For monitoring purposes the energy spectrum of the gamma quanta was registrated by a Ge(Li) detector under 1350. Additionally by three Ge(Li) detectors at 00, 900, and 1350 the angular distribution of discrete gamma lines was registrated. Here also the additional NE213 detector at -900 served as multiplicity filter. (orig.)

  14. Poisson random process for the explanation of neutron emission channels in heavy ion reactions

    International Nuclear Information System (INIS)

    Recently, in view of the proposed accelerator driven sub-critical (ADS) technology, there is increasing demand of the accurate cross-section data for almost all the projectile-target combinations over a wide range of energies. As a matter of fact, it is not possible to measure all the cross-section data needed for such applications. As an alternative the theoretical models, with suitable set of parameters, may be used to fill the gaps in experimental data. At moderate excitation energies the most common approach employs the compound nucleus (CN) model. In the compound nucleus approach it is assumed that the incident energy of the projectile is shared among all the nucleons of the composite system in statistical way, which may then decay. Here, the formation and decay are assumed to be independent of each other. The compound nucleus formed after the absorption of incident ion may decay via neutron/proton etc. emission channels. Poisson random process for the explanation of neutron emission channels in heavy ion reactions is discussed here

  15. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    CERN Document Server

    Spinella, William M; Contrera, Gustavo A; Orsaria, Milva G

    2015-01-01

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron m...

  16. Experimental detection of iron overload in liver through neutron stimulated emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kapadia, A J; Tourassi, G D; Sharma, A C [Department of Radiology, Duke Advanced Imaging Laboratories, Durham, NC 27705 (United States); Crowell, A S; Kiser, M R; Howell, C R [Department of Physics, Duke University, Durham, NC 27706 (United States)], E-mail: anuj.kapadia@duke.edu

    2008-05-21

    Iron overload disorders have been the focus of several quantification studies involving non-invasive imaging modalities. Neutron spectroscopic techniques have demonstrated great potential in detecting iron concentrations within biological tissue. We are developing a neutron spectroscopic technique called neutron stimulated emission computed tomography (NSECT), which has the potential to diagnose iron overload in the liver at clinically acceptable patient dose levels through a non-invasive scan. The technique uses inelastic scatter interactions between atomic nuclei in the sample and incoming fast neutrons to non-invasively determine the concentration of elements in the sample. This paper discusses a non-tomographic application of NSECT investigating the feasibility of detecting elevated iron concentrations in the liver. A model of iron overload in the human body was created using bovine liver tissue housed inside a human torso phantom and was scanned with a 5 MeV pulsed beam using single-position spectroscopy. Spectra were reconstructed and analyzed with algorithms designed specifically for NSECT. Results from spectroscopic quantification indicate that NSECT can currently detect liver iron concentrations of 6 mg g{sup -1} or higher and has the potential to detect lower concentrations by optimizing the acquisition geometry to scan a larger volume of tissue. The experiment described in this paper has two important outcomes: (i) it demonstrates that NSECT has the potential to detect clinically relevant concentrations of iron in the human body through a non-invasive scan and (ii) it provides a comparative standard to guide the design of iron overload phantoms for future NSECT liver iron quantification studies.

  17. Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

    Directory of Open Access Journals (Sweden)

    Hambsch F.-J.

    2016-01-01

    Full Text Available In recent years JRC-IRMM has been investigating fission cross-sections of 240,242Pu in the fast-neutron energy range relevant for innovative reactor systems and requested in the High Priority Request List (HPRL of the OECD/Nuclear Energy Agency (NEA. In addition to that, prompt neutron multiplicities are being investigated for the major isotopes 235U, 239Pu in the neutron-resonance region using a newly developed scintillation detector array (SCINTIA and an innovative modification of the Frisch-grid ionisation chamber for fission-fragment detection. These data are highly relevant for improved neutron data evaluation and requested by the OECD/Working Party on Evaluation Cooperation (WPEC. Thirdly, also prompt fission γ-ray emission is investigated using highly efficient lanthanide-halide detectors with superior timing resolution. Again, those data are requested in the HPRL for major actinides to solve open questions on an under-prediction of decay heat in nuclear reactors. The information on prompt fission neutron and γ-ray emission is crucial for benchmarking nuclear models to study the de-excitation process of neutron-rich fission fragments. Information on γ-ray emission probabilities is also useful in decommissioning exercises on damaged nuclear power plants like Fukushima Daiichi to which JRC-IRMM is contributing. The results on the 240,242Pu fission cross section, 235U prompt neutron multiplicity in the resonance region and correlations with fission fragments and prompt γ-ray emission for several isotopes will be presented and put into perspective.

  18. Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

    Science.gov (United States)

    Hambsch, F.-J.; Salvador-Castiñeira, P.; Oberstedt, S.; Göök, A.; Billnert, R.

    2016-06-01

    In recent years JRC-IRMM has been investigating fission cross-sections of 240,242Pu in the fast-neutron energy range relevant for innovative reactor systems and requested in the High Priority Request List (HPRL) of the OECD/Nuclear Energy Agency (NEA). In addition to that, prompt neutron multiplicities are being investigated for the major isotopes 235U, 239Pu in the neutron-resonance region using a newly developed scintillation detector array (SCINTIA) and an innovative modification of the Frisch-grid ionisation chamber for fission-fragment detection. These data are highly relevant for improved neutron data evaluation and requested by the OECD/Working Party on Evaluation Cooperation (WPEC). Thirdly, also prompt fission γ-ray emission is investigated using highly efficient lanthanide-halide detectors with superior timing resolution. Again, those data are requested in the HPRL for major actinides to solve open questions on an under-prediction of decay heat in nuclear reactors. The information on prompt fission neutron and γ-ray emission is crucial for benchmarking nuclear models to study the de-excitation process of neutron-rich fission fragments. Information on γ-ray emission probabilities is also useful in decommissioning exercises on damaged nuclear power plants like Fukushima Daiichi to which JRC-IRMM is contributing. The results on the 240,242Pu fission cross section, 235U prompt neutron multiplicity in the resonance region and correlations with fission fragments and prompt γ-ray emission for several isotopes will be presented and put into perspective.

  19. Electromagnetic Emission from Long-lived Binary Neutron Star Merger Remnants. II. Lightcurves and Spectra

    Science.gov (United States)

    Siegel, Daniel M.; Ciolfi, Riccardo

    2016-03-01

    Recent observations indicate that in a large fraction of binary neutron star (BNS) mergers a long-lived neutron star (NS) may be formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of such a scenario would strongly impact our knowledge on how short gamma-ray bursts (SGRBs) and their afterglow radiation are generated. Furthermore, such EM signals would have profound implications for multimessenger astronomy with joint EM and gravitational-wave (GW) observations of BNS mergers, which will soon become reality thanks to the ground-based advanced LIGO/Virgo GW detector network. Here we explore such EM signatures based on the model presented in a companion paper, which provides a self-consistent evolution of the post-merger system and its EM emission up to ˜107 s. Light curves and spectra are computed for a wide range of post-merger physical properties. We present X-ray afterglow light curves corresponding to the “standard” and the “time-reversal” scenario for SGRBs (prompt emission associated with the merger or with the collapse of the long-lived NS). The light curve morphologies include single and two-plateau features with timescales and luminosities that are in good agreement with Swift observations. Furthermore, we compute the X-ray signal that should precede the SGRB in the time-reversal scenario, the detection of which would represent smoking-gun evidence for this scenario. Finally, we find a bright, highly isotropic EM transient peaking in the X-ray band at ˜102-104 s after the BNS merger with luminosities of LX ˜ 1046-1048 erg s-1. This signal represents a very promising EM counterpart to the GW emission from BNS mergers.

  20. Electromagnetic Emission from Long-lived Binary Neutron Star Merger Remnants. I. Formulation of the Problem

    Science.gov (United States)

    Siegel, Daniel M.; Ciolfi, Riccardo

    2016-03-01

    Binary neutron star (BNS) mergers are the leading model to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations of long-lasting X-ray afterglows of SGRBs challenge standard paradigms and indicate that in a large fraction of events a long-lived neutron star (NS) may be formed rather than a black hole. Understanding the mechanisms underlying these afterglows is necessary in order to address the open questions concerning the nature of SGRB central engines. However, recent theoretical progress has been hampered by the fact that the timescales of interest for the afterglow emission are inaccessible to numerical relativity simulations. Here we present a detailed model to bridge the gap between numerical simulations of the merger process and the relevant timescales for the afterglows, assuming that the merger results in a long-lived NS. This model is formulated in terms of a set of coupled differential equations that follow the evolution of the post-merger system and predict its electromagnetic (EM) emission in a self-consistent way, starting from initial data that can be extracted from BNS merger simulations. The model presented here also allows us to search for suitable EM counterparts for multimessenger astronomy, which is expected to become reality within the next few years thanks to ground-based GW detectors such as advanced LIGO and Virgo. This paper discusses the formulation and implementation of the model. In a companion paper, we employ this model to predict the EM emission from ∼ {10}-2 to ∼ {10}7 {{s}} after a BNS merger and discuss the implications in the context of SGRBs and multimessenger astronomy.

  1. ELECTROMAGNETIC EMISSION FROM LONG-LIVED BINARY NEUTRON STAR MERGER REMNANTS. II. LIGHT CURVES AND SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Daniel M. [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany); Ciolfi, Riccardo, E-mail: daniel.siegel@aei.mpg.de, E-mail: riccardo.ciolfi@unitn.it [Physics Department, University of Trento, Via Sommarive 14, I-38123 Trento (Italy)

    2016-03-01

    Recent observations indicate that in a large fraction of binary neutron star (BNS) mergers a long-lived neutron star (NS) may be formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of such a scenario would strongly impact our knowledge on how short gamma-ray bursts (SGRBs) and their afterglow radiation are generated. Furthermore, such EM signals would have profound implications for multimessenger astronomy with joint EM and gravitational-wave (GW) observations of BNS mergers, which will soon become reality thanks to the ground-based advanced LIGO/Virgo GW detector network. Here we explore such EM signatures based on the model presented in a companion paper, which provides a self-consistent evolution of the post-merger system and its EM emission up to ∼10{sup 7} s. Light curves and spectra are computed for a wide range of post-merger physical properties. We present X-ray afterglow light curves corresponding to the “standard” and the “time-reversal” scenario for SGRBs (prompt emission associated with the merger or with the collapse of the long-lived NS). The light curve morphologies include single and two-plateau features with timescales and luminosities that are in good agreement with Swift observations. Furthermore, we compute the X-ray signal that should precede the SGRB in the time-reversal scenario, the detection of which would represent smoking-gun evidence for this scenario. Finally, we find a bright, highly isotropic EM transient peaking in the X-ray band at ∼10{sup 2}–10{sup 4} s after the BNS merger with luminosities of L{sub X} ∼ 10{sup 46}–10{sup 48} erg s{sup −1}. This signal represents a very promising EM counterpart to the GW emission from BNS mergers.

  2. Impact of the layout of the ITER Radial Neutron Camera in-port system on the measurement of the neutron emissivity profile

    International Nuclear Information System (INIS)

    Highlights: ► MCNP ITER model ‘Alite-4′ has been updated with the new Port Plug structure (three vertical drawers). ► Two different layouts for the Radial Neutron Camera (RNC) in-vessel system have been considered. ► The impact of both layouts on the RNC diagnostic performance has been assessed. ► The analysis provides useful information for a proper integration of the RNC in the EPP1. -- Abstract: The Radial Neutron Camera (RNC), located in the ITER Equatorial Port Plug 1 (EPP1), is designed to provide the neutron emissivity profile through the measurement of the neutron flux along several collimated channels. The present design of the RNC is based on collimating structures: an ex-port system viewing the plasma core and an in-port system composed by two detector cassettes viewing the upper and lower plasma edges. A design of the EPP1 in which the diagnostics are installed in three completely independent vertical drawers is under study. In this frame, space optimization and integration issues suggest two possible solutions for the layout of the in-port RNC cassettes: the first one in which both cassettes are located in a side drawer; the second one in which the two cassettes lie in the central drawer, on opposite sides of the ex-port RNC cut-out. This paper describes the work performed to assess the impact of the two different in-port system layouts on the capability of the RNC to measure the neutron emissivity profile by means of MCNP and diagnostic performance calculations. The results of the analysis provide guidelines for the integration of the RNC into the EPP1 showing that the proximity of the in-port cassettes to the ex-port cut-out strongly increases the amount of uncollimated and scattered neutrons at the detector positions, thus reducing the diagnostic measurement capability

  3. Impact of the layout of the ITER Radial Neutron Camera in-port system on the measurement of the neutron emissivity profile

    Energy Technology Data Exchange (ETDEWEB)

    Marocco, D. [Associazione EURATOM-ENEA sulla Fusione ENEA C.R. Frascati, Via E. Fermi, 45, 00044 Frascati (Roma) (Italy); Moro, F., E-mail: fabio.moro@enea.it [Associazione EURATOM-ENEA sulla Fusione ENEA C.R. Frascati, Via E. Fermi, 45, 00044 Frascati (Roma) (Italy); Esposito, B.; Brolatti, G.; Villari, R. [Associazione EURATOM-ENEA sulla Fusione ENEA C.R. Frascati, Via E. Fermi, 45, 00044 Frascati (Roma) (Italy); Salasca, S.; Cantone, B. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

    2013-10-15

    Highlights: ► MCNP ITER model ‘Alite-4′ has been updated with the new Port Plug structure (three vertical drawers). ► Two different layouts for the Radial Neutron Camera (RNC) in-vessel system have been considered. ► The impact of both layouts on the RNC diagnostic performance has been assessed. ► The analysis provides useful information for a proper integration of the RNC in the EPP1. -- Abstract: The Radial Neutron Camera (RNC), located in the ITER Equatorial Port Plug 1 (EPP1), is designed to provide the neutron emissivity profile through the measurement of the neutron flux along several collimated channels. The present design of the RNC is based on collimating structures: an ex-port system viewing the plasma core and an in-port system composed by two detector cassettes viewing the upper and lower plasma edges. A design of the EPP1 in which the diagnostics are installed in three completely independent vertical drawers is under study. In this frame, space optimization and integration issues suggest two possible solutions for the layout of the in-port RNC cassettes: the first one in which both cassettes are located in a side drawer; the second one in which the two cassettes lie in the central drawer, on opposite sides of the ex-port RNC cut-out. This paper describes the work performed to assess the impact of the two different in-port system layouts on the capability of the RNC to measure the neutron emissivity profile by means of MCNP and diagnostic performance calculations. The results of the analysis provide guidelines for the integration of the RNC into the EPP1 showing that the proximity of the in-port cassettes to the ex-port cut-out strongly increases the amount of uncollimated and scattered neutrons at the detector positions, thus reducing the diagnostic measurement capability.

  4. Testing JEFF-3.1.1 and ENDF/B-VII.1 Decay and Fission Yield Nuclear Data Libraries with Fission Pulse Neutron Emission and Decay Heat Experiments

    Science.gov (United States)

    Cabellos, O.; de Fusco, V.; Diez de la Obra, C. J.; Martinez, J. S.; Gonzalez, E.; Cano-Ott, D.; Alvarez-Velarde, F.

    2014-04-01

    The aim of this work is to test the present status of Evaluated Nuclear Decay and Fission Yield Data Libraries to predict decay heat and delayed neutron emission rate, average neutron energy and neutron delayed spectra after a neutron fission pulse. Calculations are performed with JEFF-3.1.1 and ENDF/B-VII.1, and these are compared with experimental values. An uncertainty propagation assessment of the current nuclear data uncertainties is performed.

  5. Calibration experiments of 3He neutron detectors for analyzing neutron emissivity in the hot-ion mode on the GAMMA 10 tandem mirror

    Science.gov (United States)

    Kohagura, J.; Cho, T.; Hirata, M.; Watanabe, H.; Minami, R.; Numakura, T.; Yoshida, M.; Ito, H.; Tatematsu, Y.; Yatsu, K.; Miyoshi, S.; Ogura, K.; Kondoh, T.; Nishitani, T.; Kwon, M.; England, A. C.

    2003-03-01

    Under the international fusion cooperating research, 3He neutron detectors in the GAMMA 10 tandem mirror are calibrated by the use of a 252Cf spontaneous fission neutron source (8.96×104 n/s). The calibration experiments are carried out with a "rail system" placed along the magnetic axis of the GAMMA 10 central-cell region, where hot ions in the plasma experiments with the bulk temperatures of ˜10 keV are produced. As compared to a previous neutron monitoring system with a BF3 detector in GAMMA 10, the present 3He systems are designed with about two orders-of-magnitude higher neutron-counting efficiency for analyzing a neutron emissivity from the plasmas in a single plasma discharge alone. Two 3He systems are installed near the middle and the end of the central cell so as to identify the central-cell hot-ion axial profile. The filling pressure of 3He, the effective length, and the diameter of the detector are designed as 5 bar, 300 mm, and 50 mm, respectively. The detector output spectra are carefully analyzed by the use of a preamplifier, a shaping amplifier, as well as a multichannel analyzer for each 3He detector. In the present article, the neutron-counting data from the two 3He detectors due to the on-axis 252Cf scan are interpreted in terms of the d-2 intensity dependence (d being the distance between the detector and the neutron source) as well as the effects of the central-cell magnetic coils and the other machine structural components.

  6. High energy neutron and pion-decay gamma-ray emissions from solar flares

    Institute of Scientific and Technical Information of China (English)

    Edward L. Chupp; James M. Ryan

    2009-01-01

    Solar flare gamma-ray emissions from energetic ions and electrons have been detected and measured to GeV energies since 1980. In addition, neutrons produced in solar flares with 100 MeV to GeV energies have been observed at the Earth. These emis-sions are produced by the highest energy ions and electrons accelerated at the Sun and they provide our only direct (albeit secondary) knowledge about the properties of the acceler-ator(s) acting in a solar flare. The solar flares, which have direct evidence for pion-decaygamma-rays, are unique and are the focus of this paper. We review our current knowl-edge of the highest energy solar emissions, and how the characteristics of the acceleration process are deduced from the observations. Results from the RHESSI, INTEGRAL and CORONAS missions will also be covered. The review will also cover the solar flare ca-pabilities of the new mission, FERMI GAMMA RAY SPACE TELESCOPE, launched on 2008 June 11. Finally, we discuss the requirements for future missions to advance this vital area of solar flare physics.

  7. 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...

  8. Double differential neutron emission cross sections, numerical tables and figures (1983)

    International Nuclear Information System (INIS)

    Numerical data tables for experimental double differential neutron emission cross sections with a 14 MeV neutron source are given. The experimental method is explained in Ref. 1. The data on Li, Be, C, O, Al, Cr, Fe, Ni, Mo, Cu, Nb and Pb correspond to the presentation by the authors at the 1982 Antwerp Conference (Ref. 1). Additional data for D (Ref. 2), F and Si (Ref. 3) are given. The figures showing the experimental data in comparison with the calculated double differential cross sections using ENDF/B-4 data are attached. In the comparison on carbon, the ENDF/B-5 data were used. In the figures, the corrected experimental data with a multiple scattering code are given together with the raw data. The multiple scattering correction (Ref. 4) was performed by using the calculated double differential cross sections from the ENDF/B-4 data. In the data tables, the experimental data without the multiple scattering correction are given. The numerical data tables were made by using the EXFOR format of the NEA Data Bank. (Kako, I.)

  9. Electromagnetic emission from long-lived binary neutron star merger remnants I: formulation of the problem

    CERN Document Server

    Siegel, Daniel M

    2015-01-01

    Binary neutron star (BNS) mergers are the leading model to explain the phenomenology of short gamma-ray bursts (SGRBs), which are among the most luminous explosions in the universe. Recent observations of long-lasting X-ray afterglows of SGRBs challenge standard paradigms and indicate that in a large fraction of events a long-lived neutron star (NS) may be formed rather than a black hole. Understanding the mechanisms underlying these afterglows is necessary in order to address the open questions concerning the nature of SGRB central engines. However, recent theoretical progress has been hampered by the fact that the timescales of interest for the afterglow emission are inaccessible to numerical relativity simulations. Here we present a detailed model to bridge the gap between numerical simulations of the merger process and the relevant timescales for the afterglows, assuming that the merger results in a long-lived NS. This model is formulated in terms of a set of coupled differential equations that follow the...

  10. Electromagnetic emission from long-lived binary neutron star merger remnants II: lightcurves and spectra

    CERN Document Server

    Siegel, Daniel M

    2015-01-01

    Recent observations indicate that in a large fraction of binary neutron star (BNS) mergers a long-lived neutron star (NS) may be formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of such a scenario would strongly impact our knowledge on how short gamma-ray bursts (SGRBs) and their afterglow radiation are generated. Furthermore, such EM signals would have profound implications for multimessenger astronomy with joint EM and gravitational-wave (GW) observations of BNS mergers, which will soon become reality with the ground-based advanced LIGO/Virgo GW detector network starting its first science run this year. Here we explore such EM signatures based on the model presented in a companion paper, which provides a self-consistent evolution of the post-merger system and its EM emission starting from an early baryonic wind phase and resulting in a final pulsar wind nebula that is confined by the previously ejected material. Lightcurves and spectra are computed for a wide range of post-merger...

  11. Thermal-neutron-capture prompt-gamma emission spectra of representative coals. [1. 5 to 11 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Herzenberg, C L; Olson, I K

    1981-12-01

    Prompt gamma ray emission spectra have been calculated from 1.5 to 11 MeV for a wide range of coal compositions exposed to a thermal neutron flux. These include contributions to the spectra from all of the major and minor elements present in the coals. Characteristics of the spectra are discussed and correlated with the coal compositions.

  12. Long-Range Alpha Particle Emission in the Fission of U235 by 3-MeV Neutrons

    International Nuclear Information System (INIS)

    The energy and angular distribution of long-range alpha particles emitted in the fission of U235 induced by 3-MeV neutrons have been measured. The alpha panicles were detected by solid-state detector and the fission fragments were detected by a gas scintillation counter. The neutrons were produced by the T (p, n) He3 reaction using a 5.5- MeV Van de Graaff accelerator. About 3000 fission events accompanied by the emission of a high-energy alpha panicle were recorded. The most probable energy of the alpha particles is between 15-16 MeV. and the energy distribution has a full width at half maximum of about D MeV, which is the same as observed in tliermal- neutron fission. The angular distribution of the long-range alpha panicles with respect to the incident neutron direction was found to be forward-peaked, in agreement with previous work on alpha emission in 14-MeV neutron-induced fission of LP. At angles of 0° and 90° with respect to the incident neutron direction the alpha panicles were detected with an angular spread of about ± 25°. The anisotropy [Nα(0°)/ Nα(90°)] was found to be 1.320 ± 0.12. This value is in agreement with the anisotropy calculated on the basis of statistical evaporation of panicles. The results of the present investigation are consistent with the hypothesis that the emission of long-range alpha panicles in fission is an evaporation process. The implications of the results of this work and of other recent investigations on long-range alpha emission are discussed. (author)

  13. Measurement by FIB on the ISS: Two Emissions of Solar Neutrons Detected?

    OpenAIRE

    Muraki, Y.; Koga, K.; T. Goka; Matsumoto, H.; Obara, T.; Okudaira, O.; Shibata, S.; Yamamoto, T.

    2012-01-01

    A new type of solar neutron detector (FIB) was launched on board the Space Shuttle Endeavour on July 16, 2009, and began collecting data at the International Space Station (ISS) on August 25, 2009. This paper summarizes the three years of observations obtained by the solar neutron detector FIB until the end of July 2012. The solar neutron detector FIB can determine both the energy and arrival direction of neutrons. We measured the energy spectra of background neutrons over the South Atlantic ...

  14. Characterization of neutron emission from mega-ampere deuterium gas puff Z-pinch at microsecond implosion times

    Science.gov (United States)

    Klir, D.; Shishlov, A. V.; Kokshenev, V. A.; Kubes, P.; Labetsky, A. Yu; Rezac, K.; Cikhardt, J.; Fursov, F. I.; Kovalchuk, B. M.; Kravarik, J.; Kurmaev, N. E.; Ratakhin, N. A.; Sila, O.; Stodulka, J.

    2013-08-01

    Experiments with deuterium (D2) triple shell gas puffs were carried out on the GIT-12 generator at a 3 MA current level and microsecond implosion times. The outer, middle and inner nozzle diameters were 160 mm, 80 mm and 30 mm, respectively. The influence of the mass of deuterium shells on neutron emission times, neutron yields and neutron energy spectra was studied. The injected linear mass of deuterium varied between 50 and 255 µg cm-1. Gas puffs imploded onto the axis before the peak of generator current at 700-1100 ns. Most of the neutrons were emitted during the second neutron pulse after the development of instabilities. Despite higher currents, heavier gas puffs produced lower neutron yields. Optimal mass and a short time delay between the valve opening and the generator triggering were more important than the better coincidence of stagnation with peak current. The peak neutron yield from D(d, n)3He reactions reached 3 × 1011 at 2.8 MA current, 90 µg cm-1 injected linear mass and 37 mm anode-cathode gap. In the case of lower mass shots, a large number of 10 MeV neutrons were produced either by secondary DT reactions or by DD reactions of deuterons with energies above 7 MeV. The average neutron yield ratio Y>10 MeV/Y2.5 MeV reached (6 ± 3) × 10-4. Such a result can be explained by a power law distribution for deuterons as \\rmd N_d/\\rmd E_d\\propto E_d^{-3} . The optimization of a D2 gas puff Z-pinch and similarities to a plasma focus and its drive parameter are described.

  15. Colliding neutron stars Gravitational waves, neutrino emission, and $\\gamma$-ray bursts

    CERN Document Server

    Ruffert, M; Ruffert, Maximilian

    1998-01-01

    Three-dimensional hydrodynamical simulations are presented for the direct head-on or off-center collision of two neutron stars, employing a basically Newtonian PPM code but including the emission of gravitational waves and their back-reaction on the hydrodynamical flow. A physical nuclear equation of state is used that allows us to follow the thermodynamical evolution of the stellar matter and to compute the emission of neutrinos. Predicted gravitational wave signals, luminosities and waveforms, are presented. The models are evaluated for their implications for gamma-ray burst scenarios. We find an extremely luminous outburst of neutrinos with a peak luminosity of more than 4E54 erg/s for several milliseconds. This leads to an efficiency of about 1% for the annihilation of neutrinos with antineutrinos, corresponding to an average energy deposition rate of more than 1E52 erg/s and a total energy of about 1E50 erg deposited in electron-positron pairs around the collision site within 10ms. Although these numbers...

  16. Nuclear correlations and neutrino emissivity from the neutron branch of the modified Urca process

    Science.gov (United States)

    Dehghan Niri, A.; Moshfegh, H. R.; Haensel, P.

    2016-04-01

    The neutrino emissivity from the neutron branch of the modified Urca process is calculated. The nuclear correlation effects are taken into account by employing the correlation functions extracted from the lowest-order constrained variational (LOCV) method applied to asymmetric nuclear matter. Two-body nucleon interaction is modeled by a realistic Argonne AV18 potential. In order to get consistency with semiempirical saturation parameters of nuclear matter and the existence of 2 M⊙ pulsars, we add a phenomenological Urbana UIX three-body potential to the nucleon Hamiltonian and apply a newly formulated version of the LOCV method that allows for three-body nucleon interactions. We find that at fixed temperature neutrino emissivity is a (weakly) decreasing function of density, due to quenching of the contribution from tensor correlations with increasing density. This is in variance with all previous works. We also find that three-body forces allow for the opening of the direct Urca process at nucleon density 0.3 fm-3 .

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

    Science.gov (United States)

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

    2016-06-01

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

  18. Detection of Special Nuclear Material from Delayed Neutron Emission Induced by a Dual-Particle Monoenergetic Source

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Michael F.; Nattress, J.; Jovanovic , I

    2016-06-30

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

  19. Langevin study of neutron emission in the reactions 16O+181Ta and 19F+178Hf

    Institute of Scientific and Technical Information of China (English)

    YE Wei; WU Feng; YANG Hong-Wei

    2008-01-01

    The pre-scission neutrons measured in the reactions 16O+181Ta and 19F+178Hf are studied via a Langevin equation coupled with a statistical decay model.We find that because of the mass asymmetry of different entrance channels,the spin distributions of compound nuclei would be different,consequently,the measured neutrons in these two reactions would also different.This means that the entrance channel will affect the particle emission in the fission process of hot nuclei.

  20. Cooling of neutron stars and emissivity of neutrinos by the direct Urca process under influence of a strong magnetic field

    Science.gov (United States)

    Coelho, E. L.; Chiapparini, M.; Negreiros, R. P.

    2016-04-01

    Neutron stars are born with high temperatures and during a few seconds suffer rapid cooling by emission of neutrinos. The direct Urca process is the main mechanism to explain this loss of energy. In this work we study the influence of a strong magnetic field on the composition of nuclear matter at high densities and zero temperature. We describe the matter through a relativistic mean-field model with eight light baryons (baryon octet), electrons, muons magnetic field. As output of the numerical calculations, we obtain the relative population for a parametrized magnetic field. We calculate the cooling of neutron stars with different mass and magnetic fields due to direct Urca process.

  1. Introducing single-crystal scattering and optical potentials into MCNPX: Predicting neutron emission from a convoluted moderator

    Science.gov (United States)

    Gallmeier, F. X.; Iverson, E. B.; Lu, W.; Baxter, D. V.; Muhrer, G.; Ansell, S.

    2016-04-01

    Neutron transport simulation codes are indispensable tools for the design and construction of modern neutron scattering facilities and instrumentation. Recently, it has become increasingly clear that some neutron instrumentation has started to exploit physics that is not well-modeled by the existing codes. In particular, the transport of neutrons through single crystals and across interfaces in MCNP(X), Geant4, and other codes ignores scattering from oriented crystals and refractive effects, and yet these are essential phenomena for the performance of monochromators and ultra-cold neutron transport respectively (to mention but two examples). In light of these developments, we have extended the MCNPX code to include a single-crystal neutron scattering model and neutron reflection/refraction physics. We have also generated silicon scattering kernels for single crystals of definable orientation. As a first test of these new tools, we have chosen to model the recently developed convoluted moderator concept, in which a moderating material is interleaved with layers of perfect crystals to provide an exit path for neutrons moderated to energies below the crystal's Bragg cut-off from locations deep within the moderator. Studies of simple cylindrical convoluted moderator systems of 100 mm diameter and composed of polyethylene and single crystal silicon were performed with the upgraded MCNPX code and reproduced the magnitude of effects seen in experiments compared to homogeneous moderator systems. Applying different material properties for refraction and reflection, and by replacing the silicon in the models with voids, we show that the emission enhancements seen in recent experiments are primarily caused by the transparency of the silicon and void layers. Finally we simulated the convoluted moderator experiments described by Iverson et al. and found satisfactory agreement between the measurements and the simulations performed with the tools we have developed.

  2. Development of a low neutron emission 228Th source for the calibration of GERDA

    International Nuclear Information System (INIS)

    GERDA (GERmanium Detector Array) is a very-low background experiment under construction at LNGS (Laboratori Nazionali del Gran Sasso, 3400 m.w.e.) in Italy. It is designed to search for the neutrinoless double-β decay using an array of enriched 76Ge detectors. A limit of T1/2=15.1025 y in Phase II of GERDA can be achieved by limiting the background rate to B ≤ 1.10-3 cts/(keV.kg.y). This requires a good understanding and suppression of the background produced by cosmic rays and natural radioactivity. Furthermore neutrons from spontaneous fission and (α,n) reactions in adjacent materials can contribute considerably to the background rate. 228Th has been established as a good calibration source candidate for GERDA due to its γ-emission in the region of interest around Qββ=2.04 MeV. The calibration setup requires that the 228Th source is permanently installed in the setup during data taking in a parking position at 3.5 m above the germanium detector array. Monte Carlo simulations have shown that the γ-background from the calibration source located in its parking position can be suppressed by a Ta absorber. This work investigates the significance of the neutron background induced by (α,n) reactions within the intrinsic components of a commercialy available 228Th calibration source. Furthermore a new type of a 228Th source has been developed in order to reduce the n-rate approximately by two orders of magnitude compared to a commercial 228Th source.

  3. Models of Kilonova/Macronova Emission from Black Hole–Neutron Star Mergers

    Science.gov (United States)

    Kawaguchi, Kyohei; Kyutoku, Koutarou; Shibata, Masaru; Tanaka, Masaomi

    2016-07-01

    Black hole–neutron star (BH–NS) mergers are among the most promising gravitational-wave sources for ground-based detectors, and gravitational waves from BH–NS mergers are expected to be detected in the next few years. The simultaneous detection of electromagnetic counterparts with gravitational waves would provide rich information about merger events. Among the possible electromagnetic counterparts from BH–NS mergers is the so-called kilonova/macronova, emission powered by the decay of radioactive r-process nuclei, which is one of the best targets for follow-up observations. We derive fitting formulas for the mass and the velocity of ejecta from a generic BH–NS merger based on recently performed numerical-relativity simulations. We combine these fitting formulas with a new semi-analytic model for a BH–NS kilonova/macronova lightcurve, which reproduces the results of radiation-transfer simulations. Specifically, the semi-analytic model reproduces the results of each band magnitude obtained by the previous radiation-transfer simulations within ∼1 mag. By using this semi-analytic model we found that, at 400 Mpc, the kilonova/macronova is as bright as 22–24 mag for cases with a small chirp mass and a high black hole spin, and >28 mag for a large chirp mass and a low black hole spin. We also apply our model to GRB 130603B as an illustration, and show that a BH–NS merger with a rapidly spinning black hole and a large neutron star radius is favored.

  4. Prompt neutron emission multiplicity distributions and average values, ν-bar, at 2200 meter per second for the fissile nuclides

    International Nuclear Information System (INIS)

    The prompt neutron emission multiplicity distribution, Pν, is of interest for methods of self-calibration and for auto-correlation to assay fissionable material for nuclear safeguards. ν-bar, the average value of Pν, is of interest at neutron thermal energies since it is related to the neutron multiplication factor and it is used as a normalizing point for energy dependent values of ν-bar. Values of Pν and ν-bar have been determined at the standard neutron energy of 0.0253 ev for the neutron induced fission of the four fissile nuclides, 233,235U, and 239,241Pu. Revised ν-bar values have been obtained by re-evaluating ν-bar experiments measured at 2200 meter/second relative to the ν-bar from the spontaneous fission of 252Cf. These revised values of ν-bar have been used to renormalize the measured Pν values. The revised values of ν-bar are all about 1/4 % to 1/2 % smaller than the corresponding values of ENDF/B-V. (author)

  5. Delayed Particle Study of Neutron Rich Lithium Isotopes

    CERN Multimedia

    Marechal, F; Perrot, F

    2002-01-01

    We propose to make a systematic complete coincidence study of $\\beta$-delayed particles from the decay of neutron-rich lithium isotopes. The lithium isotopes with A=9,10,11 have proven to contain a vast information on nuclear structure and especially on the formation of halo nuclei. A mapping of the $\\beta$-strength at high energies in the daughter nucleus will make possible a detailed test of our understanding of their structure. An essential step is the comparison of $\\beta$-strength patterns in $^{11}$Li and the core nucleus $^{9}$Li, another is the full characterization of the break-up processes following the $\\beta$-decay. To enable such a measurement of the full decay process we will use a highly segmented detection system where energy and emission angles of both charged and neutral particles are detected in coincidence and with high efficiency and accuracy. We ask for a total of 30 shifts (21 shifts for $^{11}$Li, 9 shifts $^{9}$Li adding 5 shifts for setting up with stable beam) using a Ta-foil target...

  6. Spectrometry and emission tomographic image reconstruction stimulated by neutrons via EM algorithm and Monte Carlo Method

    International Nuclear Information System (INIS)

    The NSECT (Neutron Stimulated Emission Computed Tomography) figures as a new spectrographic technique able to evaluate in vivo the concentration of elements using the inelastic scattering reaction (n,n'). Since its introduction, several improvements have been proposed with the aim of investigating applications for clinical diagnosis and reduction of absorbed dose associated with CT acquisition. In this context, two new diagnostic applications are presented using spectroscopic and tomographic approaches from NSECT. A new methodology has also been proposed to optimize the sinogram sampling that is directly related to the quality of the reconstruction by the irradiation protocol. The studies were developed based on simulations with MCNP5 code. Diagnosis of Renal Cell Carcinoma (RCC) and the detection of breast microcalcifications were evaluated in studies conducted using a human phantom. The obtained results demonstrate the ability of the NSECT technique to detect changes in the composition of the modeled tissues as a function of the development of evaluated pathologies. The proposed method for optimizing sinograms was able to analytically simulate the composition of the irradiated medium allowing the assessment of quality of reconstruction and effective dose in terms of the sampling rate. However, future research must be conducted to quantify the sensitivity of detection according to the selected elements. (author)

  7. Excited States of 71Ge above the Neutron Emission Threshold and Solar Neutrino Capture rates for Ga Detectors

    OpenAIRE

    Kar, Kamales; Sarkar, Sukhendusekhar; Goswami, Srubabati; Raychaudhuri, Amitava

    1997-01-01

    In Gallium detectors for solar neutrinos, the capture rate due to Gamow-Teller transitions to excited states of 71Ge beyond the neutron emission threshold is usually neglected. We make a model calculation to estimate its effect and find that this yields an additional contribution which may be as much as 0.4 SNU, even larger than that from the Isobaric Analog State in 71Ge reached by Fermi transitions, which is normally included in the standard predictions.

  8. Elemental analysis using instrumental neutron activation analysis and inductively coupled plasma atomic emission spectrometry: a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Yong Sam; Choi, Kwang Soon; Moon, Jong Hwa; Kim, Sun Ha; Lim, Jong Myoung; Kim, Young Jin [KAERI, Taejon (Korea, Republic of); Quraishi, Shamshad Begum [Bangladesh Atomic Energy Commission, Dhaka (Bangladesh)

    2003-05-01

    Elemental analyses for certified reference materials were carried out using instrumental neutron activation analysis and inductively coupled plasma-atomic emission spectrometry. Five Certified Reference Materials (CRM) were selected for the study on comparative analysis of environmental samples. The CRM are Soil (NIST SRM 2709), Coal fly ash (NIST SRM 1633a), urban dust (NIST SRM 1649a) and air particulate on filter media (NIST SRM 2783 and human hair (GBW 09101)

  9. Reevaluation of the average prompt neutron emission multiplicity (nubar) values from fission of uranium and transuranium nuclides

    International Nuclear Information System (INIS)

    In response to a need of the safeguards community, we have begun an evaluation effort to upgrade the recommended values of the prompt neutron emission multiplicity distribution, P/sub nu/ and its average value, nubar. This paper will report on progress achieved thus far. The evaluation of the uranium, plutonium, americium and curium nuclide's nubar values will be presented. The recommended values will be given and discussed. 61 references

  10. Elemental analysis using instrumental neutron activation analysis and inductively coupled plasma atomic emission spectrometry: a comparative study

    International Nuclear Information System (INIS)

    Elemental analyses for certified reference materials were carried out using instrumental neutron activation analysis and inductively coupled plasma-atomic emission spectrometry. Five Certified Reference Materials (CRM) were selected for the study on comparative analysis of environmental samples. The CRM are Soil (NIST SRM 2709), Coal fly ash (NIST SRM 1633a), urban dust (NIST SRM 1649a) and air particulate on filter media (NIST SRM 2783 and human hair (GBW 09101)

  11. Polarized thermal emission from X-ray dim isolated neutron stars: the case of RX J1856.5-3754

    Science.gov (United States)

    González Caniulef, D.; Zane, S.; Taverna, R.; Turolla, R.; Wu, K.

    2016-07-01

    The observed polarization properties of thermal radiation from isolated, cooling neutron stars depend on both the emission processes at the surface and the effects of the magnetized vacuum which surrounds the star. Here, we investigate the polarized thermal emission from X-ray dim isolated neutron stars, taking RX J1856.5-3754 as a representative case. The physical conditions of the star outermost layers in these sources is still debated, and so we consider emission from a magnetized atmosphere and a condensed surface, accounting for the effects of vacuum polarization as the radiation propagates in the star magnetosphere. We have found that, for a significant range of viewing geometries, measurement of the phase-averaged polarization fraction and phase-averaged polarization angle at both optical and X-ray wavelengths allow us to determine whether this neutron star has an atmosphere or a condensed surface. Our results may therefore be relevant in view of future developments of soft X-ray polarimeters.

  12. Polarized thermal emission from X-ray Dim Isolated Neutron Stars: the case of RX J1856.5-3754

    CERN Document Server

    Caniulef, Denis Gonzalez; Taverna, Roberto; Turolla, Roberto; Wu, Kinwah

    2016-01-01

    The observed polarization properties of thermal radiation from isolated, cooling neutron stars depend on both the emission processes at the surface and the effects of the magnetized vacuum which surrounds the star. Here we investigate the polarized thermal emission from X-ray Dim Isolated Neutron Stars, taking RX J1856.5-3754 as a representative case. The physical conditions of the star outermost layers in these sources is still debated, and so we consider emission from a magnetized atmosphere and a condensed surface, accounting for the effects of vacuum polarization as the radiation propagates in the star magnetosphere. We have found that, for a significant range of viewing geometries, measurement of the phase-averaged polarization fraction and phase-averaged polarization angle at both optical and X-ray wavelengths allow us to determine whether this neutron star has an atmosphere or a condensed surface. Our results may therefore be relevant in view of future developments of soft X-ray polarimeters.

  13. Study of pre-equilibrium emission of light complex particles from Fe and Bi induced by intermediate energy neutrons

    Science.gov (United States)

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

    2011-09-01

    We have measured double differential cross sections (DDX) for emission of hydrogen- and helium-isotopes in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi using the Medley setup at the The Svedberg Laboratory (Uppsala, Sweden). We compared experimental DDX with calculations with the TALYS code, which includes exciton model and Kalbach systematics; the code fails to reproduce the emission of complex light ions, generally overestimating it. We propose an correction for the application of the Kalbach phenomenological model in the TALYS code by introducing a new energy dependence for the nucleon transfer mechanism in the pre-equilibrium emission region. Our results suggest also evidence for multiple pre-equilibrium emission of composite particles at 175 MeV.

  14. Isotope identification capabilities using time resolved prompt gamma emission from epithermal neutrons

    International Nuclear Information System (INIS)

    We present a concept of integrated measurements for isotope identification which takes advantage of the time structure of spallation neutron sources for time resolved γ spectroscopy. Time resolved Prompt Gamma Activation Analysis (T-PGAA) consists in the measurement of gamma energy spectrum induced by the radioactive capture as a function of incident neutron Time Of Flight (TOF), directly related with the energy of incident neutrons. The potential of the proposed concept was explored on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (U.K.). Through this new technique we show an increase in the sensitivity to specific elements of archaeometric relevance, through incident neutron energy selection in prompt γ spectra for multicomponent samples. Results on a standard bronze sample are presented

  15. Neutron emission spectroscopy of DT plasmas at enhanced energy resolution with diamond detectors

    Science.gov (United States)

    Giacomelli, L.; Nocente, M.; Rebai, M.; Rigamonti, D.; Milocco, A.; Tardocchi, M.; Chen, Z. J.; Du, T. F.; Fan, T. S.; Hu, Z. M.; Peng, X. Y.; Hjalmarsson, A.; Gorini, G.

    2016-11-01

    This work presents measurements done at the Peking University Van de Graaff neutron source of the response of single crystal synthetic diamond (SD) detectors to quasi-monoenergetic neutrons of 14-20 MeV. The results show an energy resolution of 1% for incoming 20 MeV neutrons, which, together with 1% detection efficiency, opens up to new prospects for fast ion physics studies in high performance nuclear fusion devices such as SD neutron spectrometry of deuterium-tritium plasmas heated by neutral beam injection.

  16. Neutron emission as a function of fragment energy in the spontaneous fission of 260Md

    International Nuclear Information System (INIS)

    The authors have made the first measurement of the number of neutrons emitted in the spontaneous fission of a nuclide in which very high fragment energies dominate the fission process. In bombardments of 254Es, they produced 28-d 260Md, which was neutron-counted in a 1-m-diam spherical tank containing a Gd-doped scintillator solution. The average number of neutrons emitted per fission is only 2.58 ± 0.11, substantially less than for other actinides. A direct correlation of neutron multiplicity with fragment excitation energy is clearly demonstrated

  17. Assessment of the neutron emission anisotropy factor of a sealed AmBe source by means of measurements and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Loreti, S.; Pietropaolo, A., E-mail: antonino.pietropaolo@enea.it

    2015-10-11

    The neutron emission anisotropy factor of a sealed Americium–Beryllium source is experimentally determined and compared to Monte Carlo simulations. The measurements were done at the Italian Institute for Metrology of Ionizing Radiations using a long counter neutron detector and a “X.3” type AmBe sealed neutron source. Experimental data are compared to simulations performed with the MCNP code where the precise structure of the source is taken into account starting from its technical design. The contributions of the single structural parts are described to point out the effective sources of the emission anisotropy.

  18. Dispersion of the Neutron Emission in U{sup 235} Fission

    Science.gov (United States)

    Feynman, R. P.; de Hoffmann, F.; Serber, R.

    1955-01-01

    Equations are developed which allow the calculation of the average number of neutrons per U{sup235} fission from experimental measurements. Experimental methods are described, the results of which give a value of (7.8 + 0.6){sup ½} neutrons per U{sup 235} thermal fission.

  19. Measurement by FIB on the ISS: Two Emissions of Solar Neutrons Detected?

    Directory of Open Access Journals (Sweden)

    Y. Muraki

    2012-01-01

    Full Text Available A new type of solar neutron detector (FIB was launched on board the Space Shuttle Endeavour on July 16, 2009, and began collecting data at the International Space Station (ISS on August 25, 2009. This paper summarizes the three years of observations obtained by the solar neutron detector FIB until the end of July 2012. The solar neutron detector FIB can determine both the energy and arrival direction of neutrons. We measured the energy spectra of background neutrons over the South Atlantic Anomaly (SAA region and elsewhere and found the typical trigger rates to be 20 and 0.22 counts/sec, respectively. It is possible to identify solar neutrons to within a level of 0.028 counts/sec, provided that directional information is applied. Solar neutrons were possibly observed in association with the M-class solar flares that occurred on March 7 (M3.7 and June 7 (M2.5 of 2011. This marked the first time that neutrons had been observed in M-class solar flares. A possible interpretation of the production process is provided.

  20. Effect of insulator sleeve material on neutron emission from a plasma focus

    International Nuclear Information System (INIS)

    Neutron yield from a small (2 kJ) plasma focus using insulator sleeves of different materials is investigated. Experimental results indicate that the neutron yield from plasma foci may be enhanced several times if an insulator sleeve of higher dielectric constant is employed. (orig.)

  1. Gamma-Ray Emission Spectra as a Constraint on Calculations of 234 , 236 , 238U Neutron-Capture Cross Sections

    Science.gov (United States)

    Ullmann, J. L.; Krticka, M.; Kawano, T.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Wu, C. Y.; Chyzh, A.

    2015-10-01

    Calculations of the neutron-capture cross section at low neutron energies (10 eV through 100's of keV) are very sensitive to the nuclear level density and radiative strength function. These quantities are often poorly known, especially for radioactive targets, and actual measurements of the capture cross section are usually required. An additional constraint on the calculation of the capture cross section is provided by measurements of the cascade gamma spectrum following neutron capture. Recent measurements of 234 , 236 , 238U(n, γ) emission spectra made using the DANCE 4 π BaF2 array at the Los Alamos Neutron Science Center will be presented. Calculations of gamma-ray spectra made using the DICEBOX code and of the capture cross section made using the CoH3 code will also be presented. These techniques may be also useful for calculations of more unstable nuclides. This work was performed with the support of the U.S. Department of Energy, National Nuclear Security Administration by Los Alamos National Security, LLC (Contract DE-AC52-06NA25396) and Lawrence Livermore National Security, LLC (Contract DE-AC52-07NA2734).

  2. The relationship between boron neutron capture therapy (BNCT) and positron emission tomography (PET) for malignant brain tumors

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a particle irradiation therapy that is theoretically available for selective radiation of tumor cells. Boronophenylalanine-positron emission tomography (18F-BPA-PET) was used in this study. Boron is used as a tracer compound for the neutron capture reaction and has been particularly useful for the recent noncraniotomy BNCT. In this report, we introduce this type of PET as a principal axis in BNCT and relationship with PET. We calculated the drug accumulation to the tumor before neutron irradiation to individualize the treatment. We decided the indication for BNCT on the basis of a PET study and are now expanding the indications to other systemic cancers, including head and neck, lung, and liver cancers. In addition, other irradiation modalities have developed a radiation plan on the basis of a PET study, and several studies attempted improving the results; however, the lesion is exposed to high radiation doses and appear as high accumulation on BPA-PET during BNCT. We determined the neutron exposure time from the dosage for normal tissue in the actual treatment, but the lesion/normal tissue ratio obtained from BPA-PET is for evaluating the tumor dose and following the treatment plan. We also found that a PET study was useful in the follow-up stage to aid in diagnosis of pathologic conditions such as increase in tumor volume, recurrence, or radiation necrosis and for patients who had already been treated for malignant brain tumor. (author)

  3. Prospects for measuring the fuel ion ratio in burning ITER plasmas using a DT neutron emission spectrometer

    Science.gov (United States)

    Hellesen, C.; Skiba, M.; Dzysiuk, N.; Weiszflog, M.; Hjalmarsson, A.; Ericsson, G.; Conroy, S.; Andersson-Sundén, E.; Eriksson, J.; Binda, F.

    2014-11-01

    The fuel ion ratio nt/nd is an essential parameter for plasma control in fusion reactor relevant applications, since maximum fusion power is attained when equal amounts of tritium (T) and deuterium (D) are present in the plasma, i.e., nt/nd = 1.0. For neutral beam heated plasmas, this parameter can be measured using a single neutron spectrometer, as has been shown for tritium concentrations up to 90%, using data obtained with the MPR (Magnetic Proton Recoil) spectrometer during a DT experimental campaign at the Joint European Torus in 1997. In this paper, we evaluate the demands that a DT spectrometer has to fulfill to be able to determine nt/nd with a relative error below 20%, as is required for such measurements at ITER. The assessment shows that a back-scattering time-of-flight design is a promising concept for spectroscopy of 14 MeV DT emission neutrons.

  4. Emission of neutron-proton and proton-proton pairs in electron scattering induced by meson-exchange currents

    CERN Document Server

    Simo, I Ruiz; Barbaro, M B; De Pace, A; Caballero, J A; Megias, G D; Donnelly, T W

    2016-01-01

    We use a relativistic model of meson-exchange currents to compute the proton-neutron and proton-proton yields in $(e,e')$ scattering from $^{12}$C in the 2p-2h channel. We compute the response functions and cross section with the relativistic Fermi gas model for a range of kinematics from intermediate to high momentum transfers. We find a large contribution of neutron-proton configurations in the initial state, as compared to proton-proton pairs. The different emission probabilities of distinct species of nucleon pairs are produced in our model only by meson-exchange currents, mainly by the $\\Delta$ isobar current. We also analyze the effect of the exchange contribution and show that the direct/exchange interference strongly affects the determination of the np/pp ratio.

  5. Experimental study of delayed neutron emission from photo-fission of actinides

    International Nuclear Information System (INIS)

    Recently there has been a strong interest in a number of applications using the detection of delayed neutrons. Some ongoing projects, as non-destructive characterization of nuclear waste, have shown an urgent need of associated nuclear data. In this context, an experimental program has been launched to measure the delayed neutron yields and their time spectra from photo-fission of actinides. The very first measurements had been performed earlier in our laboratory with the uranium-238 and thorium-232 targets. In this thesis work the follow-up experiments, data analysis and results are reported for uranium-235 and neptunium-237. The high efficiency delayed neutron detector was designed, optimised, constructed and employed for these experiments with the endpoint Bremsstrahlung photons from 15 to 18 MeV. The photo-fission delayed neutron group parameters (ai, λi) were obtained and compared both with earlier work found in the literature and our own modelling results. The energy dependence of the total delayed neutron yield (νd) was also experimentally studied with the endpoint Bremsstrahlung photons in the energy range from 12 to 18 MeV for the uranium-235, 238, thorium-232, and neptunium-237 targets. Finally, some feasibility experiments were successfully performed with mixed samples in order to quantify the different actinide presence in the target. In parallel, the energy dependence of the total delayed neutron yield (νd) was also experimentally studied for thorium-232 but from neutron induced fission. (author)

  6. The neutron emission method for determination of fissile materials within the spent fuel equipment optimization

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Zaid, A. [Nuclear Research Center, Atomic Energy Authority, 13759- Cairo (Ethiopia); Pytel, K. [Atomic Energy Institute, Research Reactor Center, 05-400 Otwock-Swierk (Poland)

    1998-07-01

    A nondestructive assay method using neutron technique for determination of the fissile isotopes content along the irradiated fuel rods of MARIA reactor is presented. This method is based on detection of the fission neutrons emitted from external neutron source and multiplied by the fissile isotopes U-235, Pu-239, and Pu-241 within the fuel rod. Neutrons emitted from the spent fuel originate mainly from induced fission in the fissile material and source neutrons penetrating the fuel rod without interaction. Additionally, the neutrons from ({alpha}, n) reaction and spontaneous fission of actinide isotopes contribute in the total population of emitted ones. The method gives a chance to perform an experimental calibration of the equipment using two points: fresh fuel rod (maximum signal plus background) and its mock-up (background). The Monte Carlo code has been used for the geometrical simulation and optimization of the measuring equipment: neutron source, moderating container, collimator, and the neutron detector. The results of the calculation show that the moderating container of 30 cm length and 32 cm diameter and a collimator of 26 cm length, 6.8 cm width, and 2 cm height are the optimal configuration. With respect to the fission chamber position, the number of neutrons has been calculated as a function of distance from the fuel rod surface in the case of fresh fuel and its mock-up. The distance, at which the ratio of the signal to background has its maximum, has been found at 4.5 cm far from the outer surface of the fuel. (author)

  7. Production of actinide isotopes in simulated PWR fuel and their influence on inherent neutron emission

    International Nuclear Information System (INIS)

    This report describes calculations that examine the sensitivity of actinide isotopes to various reactor parameters. The impact of actinide isotope build-up, depletion, and decay on the neutron source rate in a spent-fuel assembly is determined, and correlations between neutron source rates and spent-fuel characteristics such as exposure, fissile content, and plutonium content are established. The application of calculations for evaluating experimental results is discussed

  8. Neutron emission characteristics of a high-current plasma focus: Initial studies

    International Nuclear Information System (INIS)

    The Texas A and M University plasma focus machine is operational and is beginning to provide good experimental data. It has its origins in several earlier machines and is located in a former service station building with a shield wall that provides a good geometry for neutron measurements. We are operating in the high pressure mode for a plasma focus, similar to previous efforts in the US. Early neutron measurements are providing some insight for the machine's operation

  9. The behavior of neutron emissions during ICRF minority heating of plasma at EAST

    Science.gov (United States)

    Zhong, Guoqiang; Cao, Hongrui; Hu, Liqun; Zhou, Ruijie; Xiao, Min; Li, Kai; Pu, Neng; Huang, Juan; Liu, Guangzhu; Lin, Shiyao; Lyu, Bo; Liu, Haiqing; Zhang, Xinjun; EAST Team

    2016-07-01

    Ion cyclotron radio frequency (ICRF) wave heating is a primary method to heat ions in the Experimental Advanced Superconducting Tokamak (EAST). Through neutron diagnostics, effective ion heating was observed in hydrogenminority heating (MH) scenarios. At present, investigation of deuterium-deuterium (DD) fusion neutrons is mostly based on time-resolved flux monitor and spectrometer measurements. When the ICRF was applied, the neutron intensity became one order higher. The H/H  +  D ratio was in the range of 5-10%, corresponding to the hydrogen MH dominated scenario, and a strong high energy tail was not displayed on the neutron spectrum that was measured by a liquid scintillator. Moreover, ion temperature in the plasma center (T i) was inversely calculated by the use of neutron source strength (S n) and the plasma density based on classical fusion reaction equations. This result indicates that T i increases by approximately 30% in L-mode plasma, and by more than 50% in H-mode plasma during ICRF heating, which shows good agreement with x-ray crystal spectrometer (XCS) diagnostics. Finally, the DD neutron source strength scaling law, with regard to plasma current (I P) and ICRF coupling power (P RF) on the typical minority heating condition, was obtained by statistical analysis.

  10. Neutron Capture Cross Sections and Gamma Emission Spectra from Neutron Capture on 234,236,238U Measured with DANCE

    Science.gov (United States)

    Ullmann, J. L.; Mosby, S.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Wu, C.-Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

    2014-05-01

    A new measurement of the 238U(n, γ) cross section using a thin 48 mg/cm2 target was made using the DANCE detector at LANSCE over the energy range from 10 eV to 500 keV. The results confirm earlier measurements. Measurements of the gamma-ray emission spectra were also made for 238U(n, γ) as well as 234,236U(n, γ). These measurements help to constrain the radiative strength function used in the cross-section calculations.

  11. Shock breakout driven by the remnant of a neutron star binary merger: An X-ray precursor of mergernova emission

    CERN Document Server

    Li, Shao-Ze

    2015-01-01

    A supra-massive neutron star (NS) spinning extremely rapidly could survive from a merger of NS-NS binary. The spin-down of this remnant NS that is highly magnetized would power the isotropic merger ejecta to produce a bright mergernova emission in ultraviolet/optical bands. Before the mergernova, the early interaction between the NS wind and the ejecta can drive a forward shock to propagate outwards into the ejecta. As a result, a remarkable amount of heat can be accumulated to be deposited behind the shock front, the final escaping of which can produce a shock breakout emission. We describe the dynamics and thermal emission of this shock with a semi-analytical model. It is found that a sharp and luminous breakout emission, which is mainly in soft X-rays with a luminosity of $\\sim10^{45}~\\rm erg~s^{-1}$, appears at a few hours after the merger, by leading the mergernova emission as a precursor. Therefore, detections of such X-ray precursors would provide a smoking-gun evidence for identifying NS-powered merge...

  12. Electromagnetic emission from long-lived binary neutron star merger remnants I: formulation of the problem

    OpenAIRE

    Siegel, Daniel M.; Ciolfi, Riccardo

    2015-01-01

    Binary neutron star (BNS) mergers are the leading model to explain the phenomenology of short gamma-ray bursts (SGRBs), which are among the most luminous explosions in the universe. Recent observations of long-lasting X-ray afterglows of SGRBs challenge standard paradigms and indicate that in a large fraction of events a long-lived neutron star (NS) may be formed rather than a black hole. Understanding the mechanisms underlying these afterglows is necessary in order to address the open questi...

  13. Initiation of the emission of chemical gas lasers by neutron fluxes

    Science.gov (United States)

    Basov, N. G.; Molchanov, A. G.; Oraevskii, A. N.

    The possibility of initiating chemical lasers through a nuclear reaction is examined, and the required threshold density of a neutron flux is determined. In particular, attention is given to the conditions of lasing using UF6-H2, UF6-H2-F2, and UF6-D2-F2-CO2 mixtures in the case of a branched chain reaction. The possibility of chemical laser initiation using UF-containing mixtures, without any external neutron source, is demonstrated for the case where the total mass of the UF6 gas containing enriched uranium exceeds the critical mass.

  14. Calculation of neutron and gamma-ray emission spectra produced by p + 27Al reactions

    International Nuclear Information System (INIS)

    Preliminary calculations of neutron and gamma-ray spectra induced by proton reactions on aluminum have been made to provide data required for shielding design for a proposed proton linear accelerator. The nuclear models used in this study were the preequilibrium and Hauser-Feshbach models as embodied in the GNASH program. This nuclear model code has been used in the past to successfully investigate higher energy (E less than or equal to 50 MeV) neutron and proton interactions with nuclei in the structural materials region. Because this study was of an exploratory nature, we did not attempt to optimize input parameters but instead relied upon global sets, especially for optical parameters. In particular, for neutrons we chose the Wilmore-Hodgson parameter set after confirmation of its suitability through comparison to n+27Al total cross-section data between 0.5 and 60 MeV. Agreement with the data on the level of 5-10% occurred. Comparisons were also made to measured nonelastic data for incident energies between 10 and 60 MeV. Again, there was generally good agreement although there was some tendency to overpredict such data for incident neutron energies below several MeV. For protons we found the Becchetti-Greenlees parameter set reproduced nonelastic data recently measured by McGill et al

  15. Study of proton and 2 protons emission from light neutron deficient nuclei around A=20; Etude de l'emission proton et de deux protons dans les noyaux legers deficients en neutrons de la region A=20

    Energy Technology Data Exchange (ETDEWEB)

    Zerguerras, T

    2001-09-01

    Proton and two proton emission from light neutron deficient nuclei around A=20 have been studied. A radioactive beam of {sup 18}Ne, {sup 17}F and {sup 20}Mg, produced at the Grand Accelerateur National d'Ions Lourds by fragmentation of a {sup 24}Mg primary beam at 95 MeV/A, bombarded a {sup 9}Be target to form unbound states. Proton(s) and nuclei from the decay were detected respectively in the MUST array and the SPEG spectrometer. From energy and angle measurements, the invariant mass of the decaying nucleus could be reconstructed. Double coincidence events between a proton and {sup 17}F, {sup 16}O, {sup 15}O, {sup 14}O and {sup 18}Ne were registered to obtain excitation energy spectra of {sup 18}Ne, {sup 17}F, {sup 16}F, {sup 15}F et {sup 19}Na. Generally, the masses measures are in agreement with previous experiments. In the case of {sup 18}Ne, excitation energy and angular distributions agree well with the predictions of a break up model calculation. From {sup 17}Ne proton coincidences, a first experimental measurement of the ground state mass excess of {sup 18}Na has been obtained and yields 24,19(0,15)MeV. Two proton emission from {sup 17}Ne and {sup 18}Ne excited states and the {sup 19}Mg ground state was studied through triple coincidences between two proton and {sup 15}O, {sup 16}O and {sup 17}Ne respectively. In the first case, the proton-proton relative angle distribution in the center of mass has been compared with model calculation. Sequential emission from excited states of {sup 17}Ne, above the proton emission threshold, through {sup 16}F is dominant but a {sup 2}He decay channel could not be excluded. No {sup 2}He emission from the 1.288 MeV {sup 17}Ne state, or from the 6.15 MeV {sup 18}Ne state has been observed. Only one coincidence event between {sup 17}Ne and two proton was registered, the value of the one neutron stripping reaction cross section of {sup 20}Mg being much lower than predicted. (author)

  16. Investigation of thick-target neutron emission from Be-9(d,n)B-10 at E/sub d/ = 7 MeV for angles other than zero degrees

    International Nuclear Information System (INIS)

    Double-differential measurements of neutron emission from a thick beryllium target bombarded with 7-MeV deuterons are made for neutrons above 800 keV, over the angular range of 0 to 1550. The angular dependence of the neutron yield is found to be quite anisotropic. The importance of this anisotropy in integral neutron-induced reaction cross-section investigations is illustrated. 7 refs.,

  17. Positron emission tomography-guided conformal fast neutron therapy for glioblastoma multiforme

    OpenAIRE

    Stelzer, Keith J.; Douglas, James G.; Mankoff, David A.; Silbergeld, Daniel L.; Krohn, Kenneth A.; Laramore, George E.; Spence, Alexander M.

    2008-01-01

    Glioblastoma multiforme (GBM) continues to be a difficult therapeutic challenge. Our study was conducted to determine whether improved survival and tumor control could be achieved with modern delivery of fast neutron radiation using three-dimensional treatment planning. Ten patients were enrolled. Eligibility criteria included pathologic diagnosis of GBM, age ≥ 18 years, and KPS ≥60. Patients underwent MRI and 18F-fluorodeoxyglucose PET (FDG PET) as part of initial three-dimensional treatment...

  18. Measurement of the Cross Section for Electromagnetic Dissociation with Neutron Emission in Pb-Pb Collisions at √sNN = 2.76 TeV

    CERN Document Server

    Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Arend, Andreas; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Bock, Nicolas; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Bottger, Stefan; Boyer, Bruno Alexandre; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Bugaiev, Kyrylo; Busch, Oliver; Buthelezi, Edith Zinhle; Caballero Orduna, Diego; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Sukalyan; Chattopadhyay, Subhasis; Chawla, Isha; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Colella, Domenico; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; D'Erasmo, Ginevra; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Kushal; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; de Rooij, Raoul Stefan; Del Castillo Sanchez, Eduardo; Delagrange, Hugues; Deloff, Andrzej; Demanov, Vyacheslav; Denes, Ervin; Deppman, Airton; Di Bari, Domenico; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fearick, Roger Worsley; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Fenton-Olsen, Bo; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Alessandro; Ferretti, Roberta; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Fragkiadakis, Michail; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Andrey; Ivanov, Marian; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacholkowski, Adam Wlodzimierz; Jacobs, Peter; Jancurova, Lucia; Jangal, Swensy Gwladys; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jha, Deeptanshu Manu; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jusko, Anton; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalisky, Matus; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kanaki, Kalliopi; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Mohisin Mohammed; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Dong Jo; Kim, Do Won; Kim, Jonghyun; Kim, Jin Sook; Kim, Minwoo; Kim, Se Yong; Kim, Seon Hee; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kliemant, Michael; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Koch, Kathrin; Kohler, Markus; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kuhn, Christian Claude; Kuijer, Paul; Kurashvili, Podist; Kurepin, A; Kurepin, AB; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasily; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; Lazzeroni, Cristina; Le Bornec, Yves; Lea, Ramona; Lechman, Mateusz; Lee, Ki Sang; Lee, Sung Chul; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lemmon, Roy Crawford; Lenhardt, Matthieu Laurent; Lenti, Vito; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Leoncino, Marco; Levai, Peter; Lien, Jorgen; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loenne, Per-Ivar; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Rongrong; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Mal'Kevich, Dmitry; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Marin Tobon, Cesar Augusto; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Mastromarco, Mario; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayani, Daniel; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Ajit Kumar; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Oleniacz, Janusz; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, S; Pal, Susanta Kumar; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pocheptsov, Timur; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pujol Teixido, Jordi; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Radomski, Sylwester; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodrigues Fernandes Rabacal, Bartolomeu; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roukoutakis, Filimon; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Sano, Satoshi; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selioujenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Sgura, Irene; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, catherine; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinbeck, Timm Morten; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szostak, Artur Krzysztof; Tagridis, Christos; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Tlusty, David; Toia, Alberica; Torii, Hisayuki; Tosello, Flavio; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; van Leeuwen, Marco; Vande Vyvre, Pierre; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; vrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Alexander; Wilk, Grzegorz Andrzej; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yaldo, Chris G; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo

    2012-01-01

    The first measurement of neutron emission in electromagnetic dissociation of 208Pb nuclei at the LHC is presented. The measurement is performed using the neutron Zero Degree Calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √sNN = 2.76 TeV with neutron emission are σ_single EMD = 187.2±0.2 (stat.) +13.8−12.0 (syst.) b and σ_mutual EMD = 6.2 ± 0.1 (stat.) ±0.4 (syst.) b respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.

  19. Neutron stimulated emission computed tomography applied to the assessment of calcium deposition due to the presence of microcalcifications associated with breast cancer

    International Nuclear Information System (INIS)

    In this paper we presented an application of the Neutron Stimulated Emission Computed Tomography (NSECT), which uses a thin beam of fast neutrons to stimulate stable nuclei in a sample, emitting characteristic gamma radiation. The photon energy is unique and it is used to identify the emitting nuclei. This technique was applied for evaluating the calcium isotopic composition changing due to the development of breast microcalcifications. A particular situation was simulated in which clustered microcalcifications were modeled with diameters less than 1.40 mm. In this case, neutron beam breast spectroscopy was successful in detecting the counting changes in the photon emission spectra for energies, which are characteristics of 40Ca isotope in a low deposited dose rate. (author)

  20. X-ray emission from the double neutron star binary B1534+12: Powered by the pulsar wind?

    CERN Document Server

    Kargaltsev, O; Garmire, G P

    2006-01-01

    We report the detection of the double neutron star binary (DNSB) B1534+12 (= J1537+1155) with the Chandra X-ray Observatory. This DNSB (orbital period 10.1 hr) consists of the millisecond (recycled) pulsar J1537+1155A (P_A=37.9 ms) and a neutron star not detected in the radio. After the remarkable double pulsar binary J0737-3039, it is the only other DNSB detected in X-rays. We measured the flux of (2.2\\pm 0.6)\\times10^{-15} ergs s^{-1} cm^{-2} in the 0.3-6 keV band. The small number of collected counts allows only crude estimates of spectral parameters. The power-law fit yields the photon index of 3.2\\pm 0.5 and the unabsorbed 0.2-10 keV luminosity L_X=6\\times10^{29} ergs s^{-1} = 3\\times 10^{-4}Edot_A, where Edot_A is the spin-down power of J1537+1155A. Alternatively, the spectrum can be fitted by a blackbody model with T = 2.2 MK and the projected emitting area of ~ 5\\times 10^3 m^2. The distribution of photon arrival times over binary orbital phase shows a deficit of X-ray emission around apastron, which ...

  1. 90 deg.Neutron emission from high energy protons and lead ions on a thin lead target

    CERN Document Server

    Agosteo, S; Foglio-Para, A; Mitaroff, W A; Silari, Marco; Ulrici, L

    2002-01-01

    The neutron emission from a relatively thin lead target bombarded by beams of high energy protons/pions and lead ions was measured at CERN in one of the secondary beam lines of the Super Proton Synchrotron for radiation protection and shielding calculations. Measurements were performed with three different beams: sup 2 sup 0 sup 8 Pb sup 8 sup 2 sup + lead ions at 40 GeV/c per nucleon and 158 GeV/c per nucleon, and 40 GeV/c mixed protons/pions. The neutron yield and spectral fluence per incident ion on target were measured at 90 deg.with respect to beam direction. Monte-Carlo simulations with the FLUKA code were performed for the case of protons and pions and the results found in good agreement with the experimental data. A comparison between simulations and experiment for protons, pions and lead ions have shown that--for such high energy heavy ion beams--a reasonable estimate can be carried out by scaling the result of a Monte-Carlo calculation for protons by the projectile mass number to the power of 0.80-0...

  2. Assessment of Atmospheric heavy metal deposition in North Egypt aerosols using neutron activation analysis and optical emission inductively coupled plasma

    International Nuclear Information System (INIS)

    The aim of the present study is to assess the current level of atmospheric heavy metal pollution of aerosols in different cities of North Egypt using the neutron activation analysis and optical emission inductively coupled plasma techniques. The results revealed that the highest concentrations of particulate matter PM10 and total suspended particulate matter were close to industrial areas. From the results of the enrichment factor calculations, the most significant elements of anthropogenic origin are Ba, Sb, Ce and Zn. - Highlights: → Average concentration of Cd using OE-ICP is below detection limit for all the samples. → Maximum average concentration of Pb in PM10 and TSP is 5425 and 570.3, respectively. → Concentration of 20 elements in PM10 and TSP aerosols are determined using the NAA. → EF revealed that Pb, Ba, Br, Ce, Hf, La Sb and Zn are of anthropogenic origin.

  3. Assessment of Atmospheric heavy metal deposition in North Egypt aerosols using neutron activation analysis and optical emission inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    El-Araby, E.H., E-mail: elaraby_20032000@yahoo.com [Faculty of Science, Physics Department, Jezan University, KSA (Saudi Arabia); Abd El-Wahab, M., E-mail: wahab_magda@yahoo.com [Faculty of women for Arts, Science and Education, Physics Department, Ain Shams University, PO11757 Cairo (Egypt); Diab, H.M., E-mail: hnndiab@yahoo.co.uk [National Center of Nuclear Safety and Radiation Control, Atomic Energy Authority Cairo (Egypt); El-Desouky, T.M., E-mail: trkhegazy@yahoo.com [Faculty of women for Arts, Science and Education, Physics Department, Ain Shams University, PO11757 Cairo (Egypt); Mohsen, M., E-mail: m1mohsen@yahoo.com [Faculty of Science. Physics Department, Ain-Shams University, PO 11566 Cairo (Egypt)

    2011-10-15

    The aim of the present study is to assess the current level of atmospheric heavy metal pollution of aerosols in different cities of North Egypt using the neutron activation analysis and optical emission inductively coupled plasma techniques. The results revealed that the highest concentrations of particulate matter PM{sub 10} and total suspended particulate matter were close to industrial areas. From the results of the enrichment factor calculations, the most significant elements of anthropogenic origin are Ba, Sb, Ce and Zn. - Highlights: > Average concentration of Cd using OE-ICP is below detection limit for all the samples. > Maximum average concentration of Pb in PM10 and TSP is 5425 and 570.3, respectively. > Concentration of 20 elements in PM{sub 10} and TSP aerosols are determined using the NAA. > EF revealed that Pb, Ba, Br, Ce, Hf, La Sb and Zn are of anthropogenic origin.

  4. Non-Quiescent X-ray Emission from Neutron Stars and Black Holes

    International Nuclear Information System (INIS)

    X-ray astronomy began with the detection of the persistent source Scorpius X-1. Shortly afterwards, sources were detected that were variable. Centaurus X-2, was determined to be an X-ray transient, having a quiescent state, and a state that was much brighter. As X-ray astronomy progressed, classifications of transient sources developed. One class of sources, believed to be neutron stars, undergo extreme luminosity transitions lasting a few seconds. These outbursts are believed to be thermonuclear explosions occurring on the surface of neutron stars (type I X-ray bursts). Other sources undergo luminosity changes that cannot be explained by thermonuclear burning and last for days to months. These sources are soft X-ray transients (SXTs) and are believed to be the result of instabilities in the accretion of matter onto either a neutron star or black hole. Type I X-ray bursts provide a tool for probing the surfaces of neutron stars. Requiring a surface for the burning has led authors to use the presence of X-ray bursts to rule out the existence of a black hole (where an event horizon exists not a surface) for systems which exhibit type I X-ray bursts. Distinguishing between neutron stars and black holes has been a problem for decades. Narayan and Heyl have developed a theoretical framework to convert suitable upper limits on type I X-ray bursts from accreting black hole candidates (BHCs) into evidence for an event horizon. We survey 2101.2 ks of data from the USA X-ray timing experiment and 5142 ks of data from the Rossi X-ray Timing Explorer (RXTE) experiment to obtain the first formal constraint of this type. 1122 ks of neutron star data yield a population averaged mean burst rate of 1.7 ± 0.4 x 10-5 bursts s-1, while 6081 ks of BHC data yield a 95% confidence level upper limit of 4.9 x 10-7 bursts s-1. Applying the framework of Narayan and Heyl we calculate regions of luminosity where the neutron stars are expected to burst and the BHCs would be expected to burst

  5. Gravitational waves, neutrino emissions, and effects of hyperons in binary neutron star mergers

    CERN Document Server

    Kiuchi, Kenta; Kyutoku, Koutarou; Shibata, Masaru

    2012-01-01

    Numerical simulations for the merger of binary neutron stars are performed in full general relativity incorporating both nucleonic and hyperonic finite-temperature equations of state (EOS) and neutrino cooling. It is found that for the nucleonic and hyperonic EOS, a hyper massive neutron star (HMNS) with a long lifetime $(t_{\\rm life}\\gtrsim 10 {\\rm ms})$ is the outcome for the total mass $\\approx 2.7 M_\\odot$. For the total mass $\\approx 3 M_\\odot$, a long-lived (short-lived with $t_{\\rm life}\\approx 3 {\\rm ms}$) HMNS is the outcome for the nucleonic (hyperonic) EOS. It is shown that the typical total neutrino luminosity of the HMNS is $\\sim 3$ -- $6 \\times 10^{53} {\\rm erg /s}$ and the effective amplitude of gravitational waves from the HMNS is 1 -- $4\\times 10^{-22}$ at $f\\approx 2$ -- $3.2 {\\rm kHz}$ for a source of distance of 100 Mpc. During the HMNS phase, characteristic frequencies of gravitational waves shift to a higher frequency for the hyperonic EOS in contrast to the nucleonic EOS in which they r...

  6. Model atmospheres and radiation of magnetic neutron stars: Anisotropic thermal emission

    Science.gov (United States)

    Pavlov, G. G.; Shibanov, Yu. A.; Ventura, J.; Zavlin, V. E.

    1994-01-01

    We investigate the anisotropy of the thermal radiation emitted by a surface element of a neutron star atmosphere (e.g., by a polar cap of a radio pulsar). Angular dependences of the partial fluxes at various photon energies, and spectra at various angles are obtained for different values of the effective temperature T(sub eff) and magnetic field strength B, and for different directions of the magnetic field. It is shown that the local radiation of the magnetized neutron star atmospheres is highly anisotropic, with the maximum flux emitted in the magnetic field direction. At high B the angular dependences in the soft X-ray range have two maxima, a high narrow peak along B and a lower and broader maximum at intermediate angles. The radiation is strongly polarized, the modulation of the degree of polarization due to the rotation of the neurtron star may be much higher than that for the radiative flux. The results obtained are compared with recent ROSAT observations of the thermal-like radiation from the radio pulsars PSR 1929+10 and PSR J0437-4715.

  7. 3D MHD Simulations of accreting neutron stars: evidence of QPO emission from the surface

    CERN Document Server

    Bachetti, Matteo; Kulkarni, Akshay; Burderi, Luciano; di Salvo, Tiziana; .,

    2009-01-01

    3D Magnetohydrodynamic simulations show that when matter accretes onto neutron stars, in particular if the misalignment angle is small, it does not constantly fall at a fixed spot. Instead, the location at which matter reaches the star moves. These moving hot spots can be produced both during stable accretion, where matter falls near the magnetic poles of the star, and unstable accretion, characterized by the presence of several tongues of matter which fall on the star near the equator, due to Rayleigh-Taylor instabilities. Precise modeling with Monte Carlo simulations shows that those movements could be observed as high frequency Quasi Periodic Oscillations. We performed a number of new simulation runs with a much wider set of parameters, focusing on neutron stars with a small misalignment angle. In most cases we observe oscillations whose frequency is correlated with the mass accretion rate $\\dot{M}$. Moreover, in some cases double QPOs appear, each of them showing the same correlation with $\\dot{M}$.

  8. Production and Characterization of 228Th Calibration Sources with Low Neutron Emission for GERDA

    CERN Document Server

    Baudis, Laura; Carconi, Pierluigi; Cattadori, Carla Maria; De Felice, Pierino; Eberhardt, Klaus; Eichler, Robert; Petrucci, Andrea; Tarka, Michal; Walter, Manuel

    2015-01-01

    The GERDA experiment at the Laboratori Nazionali del Gran Sasso (LNGS) searches for the neutrinoless double beta decay of 76-Ge. In view of the GERDA Phase II data collection, four new 228-Th radioactive sources for the calibration of the germanium detectors enriched in 76-Ge have been produced with a new technique, leading to a reduced neutron flux from ( alpha; n ) reactions. The gamma activities of the sources were determined with a total uncertainty of 4 percent using an ultra-low background HPGe detector operated underground at LNGS. The emitted neutron flux was determined using a low background LiI(Eu) detector and a 3-He counter at LNGS. In both cases, a reduction of about one order of magnitude with respect to commercially available 228-Th sources was obtained. Additionally, a specific leak test with a sensitivity to leaks down to 10 mBq was developed to investigate the tightness of the stainless steel capsules housing the sources after their use in cryogenic environment.

  9. Research on pinches driven by SPPED 2 generator hard X-ray and neutron emission in plasma focus configuration

    CERN Document Server

    Sánchez-Soto, L L; Silva, P; Sylvester, G S; Zambra, M; Pavez, C; Raspa, V; Castillo, F; Kies, W; Soto, Leopoldo; Moreno, Jose; Silva, Patricio; Sylvester, Gustavo; Zambra, Marcelo; Pavez, Cristian; Raspa, Veronica; Castillo, Fermin; Kies, Walter

    2004-01-01

    SPEED2 is a generator based on Marx technology and was designed in the University of Dusseldorf. SPEED2 consists on 40 +/- Marx modules connected in parallel (4.1 mF equivalent Marx generator capacity, 300 kV, 4 MA in short circuit, 187 kJ, 400 ns rise time, dI/dt~1013 A/s). Currently the SPEED2 is operating at the Comision Chilena de Energia Nuclear, CCHEN, Chile, being the most powerful and energetic device for dense transient plasma in the Southern Hemisphere. Most of the previous works developed in SPEED2 at Dusseldorf were done in a plasma focus configuration for soft X-ray emission and the neutron emission from SPEED2 was not completely studied. The research program at CCHEN considers experiments in different pinch configurations (plasma focus, gas puffed plasma focus, gas embedded Z-pinch, wire arrays) at current of hundred of kiloamperes to mega-amperes, using the SPEED2 generator. The Chilean operation has begun implementing and developing diagnostics in a conventional plasma focus configuration oper...

  10. Neutrino emissivity and bulk viscosity of iso-CSL quark matter in neutron stars

    OpenAIRE

    Blaschke, D.; Berdermann, J.

    2007-01-01

    We present results for neutrino emissivities and bulk viscosities of a two-flavor color superconducting quark matter phase with isotropic color-spin-locked (iso-CSL) single-flavor pairing which fulfill the constraints on quark matter derived from cooling and rotational evolution of compact stars. We compare with results for the phenomenologically successful, but yet heuristic 2SC+X phase.

  11. Observation of a large β -delayed neutron emission component in 102Rb decay and identification of excited states in 102Sr

    Science.gov (United States)

    Wang, Z. M.; Garnsworthy, A. B.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Bildstein, V.; Cross, D. S.; Demand, G.; Dunlop, R.; Evitts, L. J.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Ketelhut, S.; Krücken, R.; Leach, K. G.; Laffoley, A. T.; Miller, D.; Moukaddam, M.; Pore, J.; Radich, A. J.; Rajabali, M. M.; Svensson, C. E.; Tan, A.; Tardiff, E.; Unsworth, C.; Voss, A.; Voss, P.

    2016-05-01

    The β decay and β -delayed neutron emission of 102Rb have been studied using the 8 π spectrometer at TRIUMF-ISAC. The level scheme of 102Sr has been expanded from results of a γ -γ coincidence analysis, including the identification of the (4+ ) member of the ground-state band. The β -delayed neutron branching ratio of 102Rb was found to be significantly larger than previously reported. This larger value has the potential to modify the results of r -process calculations and motivates further measurements as well as refinements of theoretical models.

  12. Piezonuclear Neutrons

    CERN Document Server

    Cardone, Fabio; Petrucci, Andrea

    2008-01-01

    We report the results of neutron measurements carried out during the application of ultrasounds to a solution containing only stable elements like Iron and Chlorine, without any other radioactive source of any kind. These measurements, carried out by CR39 detectors and a Boron TriFouride electronic detector, evidenced the emission of neutron pulses. These pulses stand well above the electronic noise and the background of the laboratory where the measurements were carried out.

  13. Neutron tomography

    International Nuclear Information System (INIS)

    In this paper a survey is given of recent developments in selected areas of neutron tomography, within the context of several applications Argonne is involved in, including high penetration of reactor-fuel bundles in thick containers (involving TREAT and NRAD facilities), dual-energy hydrogen imaging (performed at IPNS), dynamic coarse-resolution emission tomography of rector fuel under test (a proposed modification to the TREAT hodoscope), and an associated-particle system that uses neutron flight-time to electronically collimate transmitted neutrons and to tomographically image nuclides identified by reaction gamma-rays

  14. Measurement of Secondary Neutron Emission Double-Differential Cross Section for Deuteron Induced by 8.22 MeV Neutrons

    Institute of Scientific and Technical Information of China (English)

    LIN; Meng-na; RUAN; Xi-chao; HUANG; Han-xiong; REN; Jie; LI; Yong-ming; LI; Xia; NIE; Yang-bo; ZHANG; Qi-wei; HE; Guo-zhu; ZHOU; Zu-ying

    2012-01-01

    <正>This experiment is performed to measure the time-of-flight spectra of secondary neutrons for deuteron induced by 8.22 MeV neutrons in the range of 15o-155o for CD2 and C samples, and 15o -65o for a polyethylene sample, by using the multi-detector fast neutron TOF spectrometer at the China institute of Atomic Energy (CIAE). The D(d, n)3He reaction source was used. The influence of the C in the CD2

  15. The Work Function Associated with Ultra-relativistic Electron Emission from Strongly Magnetized Neutron Star Surface

    Indian Academy of Sciences (India)

    Arpita Ghosh; Somenath Chakrabarty

    2011-09-01

    Following an extremely interesting idea (Schieber 1984), published long ago, the work function associated with the emission of ultra-relativistic electrons from magnetically deformed metallic crystal (mainly iron) at the outer crust of a magnetar is obtained using relativistic version of Thomas–Fermi type model for electron distribution around the nuclei in this region. In the present scenario, surprisingly, the work function becomes anisotropic; the longitudinal part is an increasing function of magnetic field strength, whereas the transverse part diverges.

  16. QPO emission from moving hot spots on the surface of neutron stars: a model

    CERN Document Server

    Bachetti, Matteo; Kulkarni, Akshay; Burderi, Luciano; di Salvo, Tiziana

    2009-01-01

    We present recent results of 3D magnetohydrodynamic simulations of neutron stars with small misalignment angles, as regards the features in light curves produced by regular movements of the hot spots during accretion onto the star. In particular, we show that the variation of position of the hot spot created by the infalling matter, as observed in 3D simulations, can produce high frequency Quasi Periodic Oscillations with frequencies associated with the inner zone of the disk. Simulations show that the usual assumption of a fixed hot spot near the polar region is valid only for misalignment angles relatively large. Otherwise, two phenomena challenge the assumption: one is the presence of Rayleigh-Taylor instabilities at the disk-magnetospheric boundary (e.g. Kulkarni & Romanova 2008), which produce tongues of accreting matter that can reach the star almost anywhere between the equator and the polar region; the other one is the motion of the hot spot around the magnetic pole during stable accretion (e.g. R...

  17. Radioactive decay products in neutron star merger ejecta: heating efficiency and $\\gamma$-ray emission

    CERN Document Server

    Hotokezaka, Kenta; Tanaka, Masaomi; Bamba, Aya; Terada, Yukikatsu; Piran, Tsvi

    2015-01-01

    The radioactive decay of the freshly synthesized $r$-process nuclei ejected in compact binary mergers power optical/infrared macronovae (kilonovae) that follow these events. The light curves depend critically on the energy partition among the different products of the radioactive decay and this plays an important role in estimates of the amount of ejected $r$-process elements from a given observed signal. We study the energy partition and $\\gamma$-ray emission of the radioactive decay. We show that $20$-$50\\%$ of the total radioactive energy is released in $\\gamma$-rays on timescales from hours to a month. The number of emitted $\\gamma$-rays per unit energy interval has roughly a flat spectrum between a few dozen keV and $1$ MeV so that most of this energy is carried by $\\sim 1$ MeV $\\gamma$-rays. However at the peak of macronova emission the optical depth of the $\\gamma$-rays is $\\sim 0.02$ and most of the $\\gamma$-rays escape. The loss of these $\\gamma$-rays reduces the heat deposition into the ejecta and h...

  18. Constraints on Thermal X-ray Radiation from SAX J1808.4-3658 and Implications for Neutron Star Neutrino Emission

    CERN Document Server

    Heinke, C O; Wijnands, R; Taam, R E

    2006-01-01

    Thermal X-ray radiation from neutron star soft X-ray transients in quiescence provides the strongest constraints on the cooling rates of neutron stars, and thus on the interior composition and properties of matter in the cores of neutron stars. We analyze new (2006) and archival (2001) XMM-Newton observations of the accreting millisecond pulsar SAX J1808.4-3658 in quiescence, which provide the most stringent constraints to date. The X-ray spectrum of SAX J1808.4-3658 in the 2006 observation is consistent with a power-law of photon index 1.83\\pm0.16, without requiring the presence of a blackbody-like component from a neutron star atmosphere. Our 2006 observation shows a slightly lower 0.5-10 keV X-ray luminosity, at a level of 68^{+15}_{-13}% that inferred from the 2001 observation. Simultaneous fitting of all available XMM data allows a constraint on the quiescent bolometric (0.01-10 keV) neutron star luminosity of L_{q,bol}<1.1*10^{31} erg/s. This limit excludes some current models of neutrino emission me...

  19. A relativistic iron emission line from the neutron star low-mass X-ray binary GX 3+1

    CERN Document Server

    Piraino, S; Kaaret, P; Mück, B; DÁi', A; DI Salvo, T; Iaria, R; Robba, N; Burderi, L; Egron, E

    2012-01-01

    We present the results of a spectroscopic study of the Fe K{\\alpha} emission of the persistent neutron-star atoll low-mass X-ray binary and type I X-ray burster GX 3+1 with the EPIC-PN on board XMM-Newton. The source shows a flux modulation over several years and we observed it during its fainter phase, which corresponds to an X-ray luminosity of Lx~10^37 ergs/s. When fitted with a two-component model, the X-ray spectrum shows broad residuals at \\sim6-7 keV that can be ascribed to an iron K{\\alpha} fluorescence line. In addition, lower energy features are observed at \\sim3.3 keV, \\sim3.9 keV and might originate from Ar XVIII and Ca XIX. The broad iron line feature is well fitted with a relativistically smeared profile. This result is robust against possible systematics caused by instrumental pile-up effects. Assuming that the line is produced by reflection from the inner accretion disk, we infer an inner disk radius of \\sim25 Rg and a disk inclination of 35{\\deg} < i < 44{\\deg}.

  20. Optical and X-ray emission from stable millisecond magnetars formed from the merger of binary neutron stars

    CERN Document Server

    Metzger, Brian D

    2013-01-01

    The coalescence of binary neutron stars (NSs) may in some cases produce a stable massive NS remnant rather than a black hole. Due to the substantial angular momentum from the binary, such a remnant is born rapidly rotating and likely acquires a strong magnetic field (a `millisecond magnetar'). Magnetic spin-down deposits a large fraction of the rotational energy from the magnetar behind the small quantity of mass ejected during the merger. This has the potential for creating a bright transient that could be useful for determining whether a NS or black hole was formed in the merger. We investigate the expected signature of such an event, including for the first time the important impact of electron/positron pairs injected by the millisecond magnetar into the surrounding nebula. These pairs cool via synchrotron and inverse Compton emission, producing a pair cascade and hard X-ray spectrum. A fraction of these X-rays are absorbed by the ejecta walls and re-emitted as thermal radiation, leading to an optical/UV t...

  1. Optical and X-ray emission from stable millisecond magnetars formed from the merger of binary neutron stars

    Science.gov (United States)

    Metzger, Brian D.; Piro, Anthony L.

    2014-04-01

    The coalescence of binary neutron stars (NSs) may in some cases produce a stable massive NS remnant rather than a black hole. Due to the substantial angular momentum from the binary, such a remnant is born rapidly rotating and likely acquires a strong magnetic field (a `millisecond magnetar'). Magnetic spin-down deposits a large fraction of the rotational energy from the magnetar behind the small quantity of mass ejected during the merger. If the magnetar outflow is indeed trapped behind the ejecta (instead of placing most of its energy into a collimated jet), this has the potential for creating a bright transient that could be useful for determining whether an NS or black hole was formed in the merger. We investigate the expected signature of such an event, including for the first time the important impact of e± pairs injected by the millisecond magnetar into the surrounding nebula. These pairs cool via synchrotron and inverse Compton emission, producing a pair cascade and hard X-ray spectrum. A fraction of these X-rays are absorbed by the ejecta walls and re-emitted as thermal radiation, leading to an optical/UV transient peaking at a luminosity of ˜1043-1044 erg s-1 on a time-scale of several hours to days. This is dimmer than predicted by simpler analytic models because the large optical depth of e± pairs across the nebula suppresses the efficiency with which the magnetar spin-down luminosity is thermalized. Nevertheless, the optical/UV emission is more than two orders of magnitude brighter than a radioactively powered `kilonova'. In some cases, nebular X-rays are sufficiently luminous to re-ionize the ejecta, in which case non-thermal X-rays escape the ejecta unattenuated with a similar peak luminosity and time-scale as the optical radiation. We discuss the implications of our results for the temporally extended X-ray emission that is observed to follow some short gamma-ray bursts (GRBs), including the kilonova candidates GRB 080503 and GRB 130603B.

  2. Effects of neutrino emissivity on the cooling of neutron stars in the presence of a strong magnetic field

    Science.gov (United States)

    Coelho, Eduardo Lenho; Chiapparini, Marcelo; Negreiros, Rodrigo Picanço

    2015-12-01

    One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars with fields up to 1014 G at the surface. The strength of magnetic field in the center of a neutron star remains unknown. According to the scalar virial theorem, magnetic field in the core could be as large as 1018 G. In this work we study the influence of strong magnetic fields on the cooling of neutron stars coming from direct Urca process. Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. The matter is described using a relativistic mean-field model at zero temperature with eight baryons (baryon octet), electrons and muons. We obtain the relative population of each species of particles as function of baryon density for different magnetic fields. We calculate numerically the cooling of neutron stars for a parametrized magnetic field and compare the results for the case without a magnetic field.

  3. Study of the Beta-delayed multiple particle break-up of the 2.43 MeV state in Be-9

    Science.gov (United States)

    Madurga Flores, Miguel; Borge, M. J. G.; Fynbo, H. O. U.; Jonson, B.; Nyman, G.; Prezado, Y.; Riisager, K.

    The aim of this work is to study the β -delayed multiparticle break-up of the 5/2- state in 9 Be at 2.43 MeV excitation energy. This process is relevant as it has been proposed recently that this level plays a role in the α(αn,γ)9 Be reaction. This state breaks-up in 2α+n, and sequential as well as direct ("democratic") decay have previously been considered. In our work energy and direction of the two emitted α particles has been measured, while those of the neutron have been reconstructed. The sequential decay is considered using the R-matrix formalism. For the democratic decay the hyper-spherical harmonics functions are used. The different decay processes are compared with the data using the Monte-Carlo method. Our preliminary results indicate that the data is better described when democratic decay is assumed.

  4. Radioactive decay products in neutron star merger ejecta: heating efficiency and γ-ray emission

    Science.gov (United States)

    Hotokezaka, K.; Wanajo, S.; Tanaka, M.; Bamba, A.; Terada, Y.; Piran, T.

    2016-06-01

    The radioactive decay of the freshly synthesized r-process nuclei ejected in compact binary mergers powers optical/infrared macronovae (kilonovae) that follow these events. The light curves depend critically on the energy partition among the different decay products and it plays an important role in estimates of the amount of ejected r-process elements from a given observed signal. We show that 20-50 per cent of the total radioactive energy is released in γ-rays on time-scales from hours to a month. The number of emitted γ-rays per unit energy interval has roughly a flat spectrum between a few dozen keV and 1 MeV so that most of the energy is carried by ˜1 MeV γ-rays. However, at the peak of macronova emission the optical depth of the γ-rays is ˜0.02 and most of the γ-rays escape. The loss of these γ-rays reduces the heat deposition into the ejecta and hence reduces the expected macronova signals if those are lanthanides dominated. This implies that the ejected mass is larger by a factor of 2-3 than what was previously estimated. Spontaneous fission heats up the ejecta and the heating rate can increase if a sufficient amount of transuranic nuclei are synthesized. Direct measurements of these escaping γ-rays may provide the ultimate proof for the macronova mechanisms and an identification of the r-process nucleosynthesis sites. However, the chances to detect these signals are slim with current X-ray and γ-ray missions. New detectors, more sensitive by at least a factor of 10, are needed for a realistic detection rate.

  5. Hard-tail emission in the soft state of low-mass X-ray binaries and their relation to the neutron star magnetic field

    Science.gov (United States)

    Asai, Kazumi; Mihara, Tatehiro; Mastuoka, Masaru; Sugizaki, Mutsumi

    2016-06-01

    Average hard-tail X-ray emission in the soft state of nine bright Atoll low-mass X-ray binaries containing a neutron star (NS-LMXBs) are investigated by using the light curves of MAXI/GSC (Gas Slit Camera) and Swift/BAT (Burst Alert Telescope). Two sources (4U 1820-30 and 4U 1735-44) exhibit a large hardness ratio (15-50 keV/2-10 keV: HR >0.1), while the other sources distribute at HR ≲ 0.1. In either case, HR does not depend on the 2-10 keV luminosity. Therefore the difference of HR is due to the 15-50 keV luminosity, which is Comptonized emission. The Compton cloud is assumed to be around the neutron star. The size of the Compton cloud would affect the value of HR. Although the magnetic field of an NS-LMXB is weak, we could expect a larger Alfvén radius than the innermost stable circular orbit or the neutron star radius in some sources. In such cases, the accretion inflow is stopped at the Alfvén radius and would create a relatively large Compton cloud. This would result in the observed larger Comptonized emission. By attributing the difference of the size of Compton cloud to the Alfvén radius, we can estimate the magnetic fields of neutron stars. The obtained lower/upper limits are consistent with the previous results.

  6. Hard-tail emission in the soft state of low-mass X-ray binaries and their relation to the neutron star magnetic field

    Science.gov (United States)

    Asai, Kazumi; Mihara, Tatehiro; Mastuoka, Masaru; Sugizaki, Mutsumi

    2016-08-01

    Average hard-tail X-ray emission in the soft state of nine bright Atoll low-mass X-ray binaries containing a neutron star (NS-LMXBs) are investigated by using the light curves of MAXI/GSC (Gas Slit Camera) and Swift/BAT (Burst Alert Telescope). Two sources (4U 1820-30 and 4U 1735-44) exhibit a large hardness ratio (15-50 keV/2-10 keV: HR >0.1), while the other sources distribute at HR ≲ 0.1. In either case, HR does not depend on the 2-10 keV luminosity. Therefore the difference of HR is due to the 15-50 keV luminosity, which is Comptonized emission. The Compton cloud is assumed to be around the neutron star. The size of the Compton cloud would affect the value of HR. Although the magnetic field of an NS-LMXB is weak, we could expect a larger Alfvén radius than the innermost stable circular orbit or the neutron star radius in some sources. In such cases, the accretion inflow is stopped at the Alfvén radius and would create a relatively large Compton cloud. This would result in the observed larger Comptonized emission. By attributing the difference of the size of Compton cloud to the Alfvén radius, we can estimate the magnetic fields of neutron stars. The obtained lower/upper limits are consistent with the previous results.

  7. The DIORAMA Neutron Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Terry, James Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  8. Hard-tail emission in the soft state of low-mass X-ray binaries and their relation to the neutron star magnetic field

    CERN Document Server

    Asai, Kazumi; Mastuoka, Masaru; Sugizaki, Mutsumi

    2016-01-01

    Average hard-tail X-ray emission in the soft state of nine bright Atoll low-mass X-ray binaries containing a neutron star (NS-LMXBs) are investigated by using the light curves of MAXI/GSC and Swift/BAT. Two sources (4U 1820$-$30 and 4U 1735$-$44) exhibit large hardness ratio (15--50 keV$/$2--10 keV: {\\it HR} $>$ 0.1), while the other sources distribute at {\\it HR} $\\ltsim$ 0.1. In either case, {\\it HR} does not depend on the 2--10 keV luminosity. Therefore the difference of {\\it HR} is due to the 15--50 keV luminosity, which is Comptonized emission. The Compton cloud is assumed to be around the neutron star. The size of the Compton cloud would affect the value of {\\it HR}. Although the magnetic field of NS-LMXB is weak, we could expect a larger Alfv\\'{e}n radius than the innermost stable circular orbit or the neutron star radius in some sources. In such cases, the accretion inflow is stopped at the Alfv\\'{e}n radius and would create relatively large Compton cloud. It would result in the observed larger Compto...

  9. Characterization of the energy distribution of neutrons generated by 5 MeV protons on a thick beryllium target at different emission angles

    Energy Technology Data Exchange (ETDEWEB)

    Agosteo, S. [Politecnico di Milano, Dipartimento di Energia, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)] [Istituto Nazionale di Fisica Nucleare, Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Colautti, P., E-mail: paolo.colautti@lnl.infn.it [INFN, Laboratori Nazionali di Legnaro (LNL), Via dell' Universita, 2, I-35020 Legnaro (PD) (Italy); Esposito, J., E-mail: juan.esposito@tin.it [INFN, Laboratori Nazionali di Legnaro (LNL), Via dell' Universita, 2, I-35020 Legnaro (PD) (Italy); Fazzi, A.; Introini, M.V.; Pola, A. [Politecnico di Milano, Dipartimento di Energia, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)] [Istituto Nazionale di Fisica Nucleare, Sezione di Milano, via Celoria 16, 20133 Milano (Italy)

    2011-12-15

    Neutron energy spectra at different emission angles, between 0 Degree-Sign and 120 Degree-Sign from the Be(p,xn) reaction generated by a beryllium thick-target bombarded with 5 MeV protons, have been measured at the Legnaro Laboratories (LNL) of the Italian National Institute for Nuclear Physics research (INFN). A new and quite compact recoil-proton spectrometer, based on a monolithic silicon telescope, coupled to a polyethylene converter, was efficiently used with respect to the traditional Time-of-Flight (TOF) technique. The measured distributions of recoil-protons were processed through an iterative unfolding algorithm in order to determine the neutron energy spectra at all the angles accounted for. The neutron energy spectrum measured at 0 Degree-Sign resulted to be in good agreement with the only one so far available at the requested energy and measured years ago with TOF technique. Moreover, the results obtained at different emission angles resulted to be consistent with detailed past measurements performed at 4 MeV protons at the same angles by TOF techniques.

  10. Searches for T-odd correlations in the emission of prompt neutrons in the polarized-neutron-induced fission of 235U nuclei

    Science.gov (United States)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2010-07-01

    The results of an experiment aimed at searches for formally T-odd correlations in the angular distribution of prompt neutrons from the fission of 235U nuclei are presented. The experiment was performed in the MEPHISTO polarized cold-neutron beam from the Munich FRMII reactor. The correlation coefficient proved to be (-3.5 ± 3.4) × 10-5 for a three-vector correlation (TRI effect) and (-5.0 ± 3.4) × 10-5 for a five-vector correlation (ROT effect). This means that no significant effects were discovered within the measurement errors. A comparison with the analogous effects in the ternary fission of 235U nuclei was performed. The values of the corresponding correlations in the angular distribution of prompt fission gamma rays were refined.

  11. The Milky Way - Pulsars and Isolated Neutron Stars

    OpenAIRE

    Becker, W.; Pavlov, G. G.

    2002-01-01

    CONTENTS The Milky Way -- Pulsars and Isolated Neutron Stars / Introduction: Historical Overview / Physics and Astrophysics of Isolated Neutron Stars / Rotation-powered Pulsars: The Magnetic Braking Model / High-energy Emission Models / Magnetospheric Emission Models / Thermal Evolution of Neutron Stars / Photospheric Emission from Cooling Neutron Stars / The Current Picture of High-Energy Emission Properties of Isolated Neutron Stars / Young Neutron Stars in Supernova Remnants / Crab-like Pu...

  12. Effects of neutrino emissivity on the cooling of neutron stars in the presence of a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Eduardo Lenho, E-mail: eduardo.coelho@uva.br [Universidade Veiga de Almeida, 108 Ibituruna St., 20271-020, Rio de Janeiro (Brazil); Chiapparini, Marcelo [Instituto de Física, Universidade do Estado do Rio de Janeiro, 524 São Francisco Xavier St., 20271-020, Rio de Janeiro (Brazil); Negreiros, Rodrigo Picanço [Instituto de Física, Universidade Federal Fluminense, Gal. Milton Tavares de Souza Ave., 24210-346, Rio de Janeiro (Brazil)

    2015-12-17

    One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars with fields up to 10{sup 14} G at the surface. The strength of magnetic field in the center of a neutron star remains unknown. According to the scalar virial theorem, magnetic field in the core could be as large as 10{sup 18} G. In this work we study the influence of strong magnetic fields on the cooling of neutron stars coming from direct Urca process. Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. The matter is described using a relativistic mean-field model at zero temperature with eight baryons (baryon octet), electrons and muons. We obtain the relative population of each species of particles as function of baryon density for different magnetic fields. We calculate numerically the cooling of neutron stars for a parametrized magnetic field and compare the results for the case without a magnetic field.

  13. Neutron emission from electromagnetic dissociation of Pb nuclei at √sNN = 2.76 TeV measured with the ALICE ZDC

    Directory of Open Access Journals (Sweden)

    Cortese P.

    2014-04-01

    The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √sNN = 2.76 TeV, with neutron emission, are σsingle EMD = 187:4 ± 0.2 (stat.−11.2+13.2 (syst. b and σmutual EMD = 5.7 ± 0.1 (stat. ±0.4 (syst. b, respectively [1]. This is the first measurement of electromagnetic dissociation of 208Pb nuclei at the LHC energies, allowing a test of electromagnetic dissociation theory in a new energy regime. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.

  14. The Equilibrium and Pre-Equilibrium Neutron Emission Spectra of Some Deformed Target Nuclei for (p,xn) Reactions up to 22.4 MeV

    International Nuclear Information System (INIS)

    In this study, by using equilibrium and pre-equilibrium reaction mechanisms, neutron-emission spectra produced by (p,xn) reactions for some deformed target nuclei as 165Ho, 181Ta and 232Th have been calculated the bombarding energies up to 22.4 MeV. In the calculations, pre-equilibrium calculations were calculated by using new evaluated hybrid model and geometry dependent hybrid model, full exciton model and cascade exciton model. The reaction equilibrium component was calculated by Weisskopf-Ewing model. The obtained results have been discussed and compared with the available experimental data and found agreement with each other

  15. Linking Jet Emission, X-ray States and Hard X-ray Tails in the Neutron Star X-ray Binary GX 17+2

    OpenAIRE

    Migliari, S.; Miller-Jones, J. C. A.; Fender, R. P.; Homan, J.; T. Di Salvo; Rothschild, R. E.; Rupen, M P; Tomsick, J. A.; Wijnands, R.; van der Klis, M.

    2007-01-01

    We present the results from simultaneous radio (Very Large Array) and X-ray (Rossi-X-ray Timing Explorer) observations of the Z-type neutron star X-ray binary GX~17+2. The aim is to assess the coupling between X-ray and radio properties throughout its three rapidly variable X-ray states and during the time-resolved transitions. These observations allow us, for the first time, to investigate quantitatively the possible relations between the radio emission and the presence of the hard X-ray tai...

  16. The tokamak as a neutron source

    International Nuclear Information System (INIS)

    This paper describes the tokamak in its role as a neutron source, with emphasis on experimental results for D-D neutron production. The sections summarize tokamak operation, sources of fusion and non-fusion neutrons, principal neutron detection methods and their calibration, neutron energy spectra and fluxes outside the tokamak plasma chamber, history of neutron production in tokamaks, neutron emission and fusion power gain from JET and TFTR (the largest present-day tokamaks), and D-T neutron production from burnup of D-D tritons. This paper also discusses the prospects for future tokamak neutron production and potential applications of tokamak neutron sources. 100 refs., 16 figs., 4 tabs

  17. Neutron emission asymmetries from linearly polarized γ rays on ^natCd, ^natSn, and ^181Ta

    Science.gov (United States)

    Clarke Smith, W.; Feldman, Gerald

    2011-10-01

    Azimuthal asymmetries in neutron yields produced by bombarding targets with linearly polarized photons via (γ,n), (γ,2n), and (γ,f) reactions are being investigated as a possible means of identifying various nuclear isotopes. The High Intensity γ-ray Source (HIγS) at Duke University provides nearly monochromatic, circularly or linearly polarized γ rays with high intensity by Compton backscattering free-electron-laser photons from stored electrons. Linearly polarized γ rays produced by HIγS were incident on ^natCd, ^natSn, and ^181Ta targets at six energies Eγ between 11.0 and 15.5 MeV and emitted neutrons were detected both parallel and perpendicular to the plane of polarization by an array of 18 liquid-scintillator detectors at angles in the range θ=55^o--142^o. Detected neutrons were distinguished from Compton scattered photons by pulse-shape-discrimination and timing cuts, and their energies (En) were determined using time-of-flight information over a 0.5 m flight path. The characteristic plots of Rn, the ratio of neutron counts parallel to neutron counts perpendicular to the plane of the incident γ-ray polarization, against En were constructed for each value of Eγ and θ and then compared to those for other targets studied at HIγS, including fissile nuclei ^235U and ^238U.

  18. FOREWORD: Neutron metrology Neutron metrology

    Science.gov (United States)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    covered, particularly as a compendium of papers on spectrometry for radiation protection has been published relatively recently [1]. The CIPM Mutual Recognition Arrangement (CIPM MRA), whereby national measurement standards and certificates issued by different national metrology institutes (NMIs) can be recognized internationally, is covered only briefly, although the key comparisons which underpin the CIPM MRA are highlighted. The papers included in this issue concentrate on the primary physical quantities—neutron source emission rate and neutron fluence, papers on the latter quantity covering the wide range of neutron energies for which standards are required. Neutron cross sections are fundamental to neutron physics and their importance in neutron metrology is also covered. A large amount of work by acknowledged experts in neutron metrology has gone into the preparation of this special issue and we are indebted to them for their time and effort. The list of contributors begins with the authors of the papers but also includes the referees who provided invisible but invaluable input. We are grateful for the support and encouragement of Professor Georgio Moscati, president of the CCRI when the work was proposed, Dr Kim Carneiro the current president, and Dr Penny Allisy-Roberts the executive secretary of the CCRI. When this work was first proposed a list of potential topics was drawn up by the then chairman of Section (III) Dr Horst Klein. It is a measure of his insight and knowledge of the field that the resulting document matches almost exactly the original plan he drew up. This special issue is thus a tribute to his very extensive contribution to the field. We sincerely hope its contents provide an accurate picture of the present state of neutron metrology in view of Dr Klein's conviction of the importance in metrology of getting things right. Reference [1] Thomas D J and Klein H (ed) 2003 Neutron and photon spectrometry techniques for radiation protection Radiat

  19. Pre-neutron-emission Mass Distributions for Neutron-induced 238U Fission at Low and Intermediate Energies%中低能中子诱发238U裂变的碎片质量分布

    Institute of Scientific and Technical Information of China (English)

    孙小军; 余呈刚; 王宁

    2012-01-01

    乏燃料中238U含量最多(高达95%),研究中子诱发238U裂变产物的分布特性对乏燃料的循环后处理具有非常重要的意义.本文基于微观和唯象方法的裂变势模型理论,研究入射能量从0.9 MeV-60.0 MeV能区的中子诱发238U裂变反应的发射中子前碎片质量分布,结果表明:在中能区,理论计算结果能很好地重现实验数据,甚至比国际著名的TALYS理论计算的结果要好;在低能区,理论计算结果也较为合理,并分析了与实验数据有所偏差的原因.%238Utof which abundance is almost 95% ,is one of the most important isotopes of the spent nuclear fuel. The study of neutron-induced 238U fission is in favor of the cycle processing of the spent fuel. Based on the microscopic and phenomenological approach,the pre-neutron-emission mass distributions of neutron-induced 238U fission at incident energies from 0. 9 to 60 MeV have been studied with the fission potential theory proposed in previous paper. The calculated results could well reproduce the experimental data,and are even better than that of the famous TALYS code at intermediate energies.The results can also reasonably predict the distributions at the vibrational resonances,and the deviation between the experimental and the theoretical data is also analyzed.

  20. Basic neutronics. Neutrons migration

    International Nuclear Information System (INIS)

    This article presents the basic neutronics necessary for the understanding of the operation of the different types of nuclear reactors: 1 - introduction to neutronics: principle of fission chain reactions, fast neutron reactors and thermal neutron reactors, capture, neutron status, variations with the reactor lattices; 2 - Boltzmann equation: neutrons population, neutrons migration, characterization of neutrons population and reactions, integral form of the Boltzmann equation, integral-differential form, equivalence between the two forms; 3 - reactor kinetics: fast neutrons and delayed neutrons, kinetic equations in punctual model, Nordheim equation, reactivity jumps, reactivity ramp; 4 - diffusion equation: local neutron status, Fick's law, diffusion equation, initial, boundary and interface conditions, nuclei in infinite and homogenous medium, some examples of solutions, developments in Eigenmodes; 5 - one-group theory: equation of the 'one-group - diffusion' theory, critical condition of the naked and homogenous reactor, critical condition of a reactor with reflectors, generalizations; 6 - neutrons moderation: different moderation mechanisms, elastic shock laws, moderation equation, some examples of solutions; 7 - resonance absorption of neutrons: advantage of the discontinuous moderation character, advantage of an heterogenous disposition, classical formula of the anti-trap factor in homogenous and heterogenous situation; 8 - neutrons thermalization: notions of thermalization mechanisms, thermalization equation, Maxwell spectrum, real spectrum, classical formula of the thermal utilisation factor, classical formula of the reproduction factor, moderation optimum. (J.S.)

  1. Neutron Scintillators for Downscattered Neutron Imaging

    International Nuclear Information System (INIS)

    Images of neutron emission from Inertial Confinement Fusion (ICF) (D,T) targets reveal the internal structure of the target during the fusion burn. 14-MeV neutrons provide images which show the size and shape of the region where (D,T) fusion is most intense. Images based on ''downscattered'' neutrons with energies from 5 to 10 MeV emphasize the distribution of deuterium and tritium fuel within the compressed target. The downscattered images are difficult to record because the lower energy neutrons are detected with less efficiency than the much more intense pulse of 14-MeV neutrons which precedes them at the detector. The success of downscattered neutron imaging will depend on the scintillation decay times and the sensitivities to lower-energy neutrons of the scintillator materials that are used in the detectors. A time-correlated photon counting system measured the decay of neutron-induced scintillation for times as long as several hundred ns. Accelerators at the University of California, Berkeley, and the Lawrence Livermore National Laboratory provided stable 14-MeV neutron sources for the measurements. Measurements of scintillator decay characteristics indicate that some commercially available scintillators should be suitable for recording both 14-MeV and downscattered neutron images of compressed ICF targets

  2. THE VARIABLE QUIESCENT X-RAY EMISSION OF THE TRANSIENT NEUTRON STAR XTE J1701-462

    International Nuclear Information System (INIS)

    We present the results of continued monitoring of the quiescent neutron star low-mass X-ray binary XTE J1701-462 with Chandra and Swift. A new Chandra observation from 2010 October extends our tracking of the neutron star surface temperature from ≅800 days to ≅1160 days since the end of an exceptionally luminous 19 month outburst. This observation indicates that the neutron star crust may still be slowly cooling toward thermal equilibrium with the core; another observation further into quiescence is needed to verify this. The shape of the overall cooling curve is consistent with that of a broken power law, although an exponential decay to a constant level cannot be excluded with the present data. To investigate possible low-level activity, we conducted a monitoring campaign of XTE J1701-462 with Swift during 2010 April-October. Short-term flares-presumably arising from episodic low-level accretion-were observed up to a luminosity of ∼1 x 1035 erg s-1, ∼20 times higher than the normal quiescent level. We conclude that flares of this magnitude are not likely to have significantly affected the equilibrium temperature of the neutron star and are probably not able to have a measurable impact on the cooling curve. However, it is possible that brighter and longer periods of low-level activity have had an appreciable effect on the equilibrium temperature.

  3. Bibliography of published papers on neutron and photon emission from thick or thin target bombarded by charged particles

    International Nuclear Information System (INIS)

    Papers describing about secondary particles, especially neutrons and photons, produced by a thick or thin target are surveyed. The survey covers twelve kinds of journals mainly from 1965 to 1980, and brief descriptions are listed about type of accelerator, projectile and target used, measurements and calculations, and quantities obtained. (author)

  4. Gravitational Wave transient signal emission via Ekman Pumping in Neutron Stars during post-glitch relaxation phase

    CERN Document Server

    Singh, Avneet

    2016-01-01

    Glitches in the rotational frequency of a spinning neutron star could be promising sources of gravitational wave signals lasting between a few {\\mu}s to a few weeks. The emitted signals and their properties depend upon the internal properties of the neutron star. In stellar models that assume a super-fluid core for the neutron star, the most important physical properties are the viscosity of the super-fluid, the stratification of flow in the equilibrium state and the adiabatic sound speed. Such models were previously studied by van Eysden and Melatos (2008) and Bennett et al. (2010) following simple assumptions on all contributing factors, in which the post-glitch relaxation phase could be driven by the well-known process of 'Ekman pumping'. We explore the hydrodynamic properties of the flow of super-fluid during this phase following more relaxed assumptions on the stratification of flow and/or the pressure-density gradients within the neutron star than previously studied. We calculate the time-scales of dura...

  5. The Variable Quiescent X-Ray Emission of the Neutron Star Transient XTE J1701-462

    NARCIS (Netherlands)

    Fridriksson, Joel K.; Homan, J.; Wijnands, R.; Cackett, E. M.; Degenaar, N.; Mendez, M.; Altamirano, D.; Brown, E. F.; Belloni, T. M.; Lewin, W. H. G.

    2011-01-01

    We have monitored the cooling of the neutron star in the transient low-mass X-ray binary XTE J1701-462 with Chandra and XMM-Newton since the source entered quiescence in 2007 after an exceptionally luminous 19-month outburst. A recent Chandra observation made almost 1200 days into quiescence indicat

  6. The Variable Quiescent X-Ray Emission of the Neutron Star Transient XTE J1701-462

    Science.gov (United States)

    Fridriksson, Joel K.; Homan, J.; Wijnands, R.; Cackett, E. M.; Degenaar, N.; Mendez, M.; Altamirano, D.; Brown, E. F.; Belloni, T. M.; Lewin, W. H. G.

    2011-01-01

    We have monitored the cooling of the neutron star in the transient low-mass X-ray binary XTE J1701-462 with Chandra and XMM-Newton since the source entered quiescence in 2007 after an exceptionally luminous 19-month outburst. A recent Chandra observation made almost 1200 days into quiescence indicates that the neutron star crust is likely still slowly cooling toward thermal equilibrium with the core. The current surface temperature is high compared to other quiescent neutron star transients, with an implied bolometric thermal flux of 5×1033 erg/s. The overall cooling curve seems to have followed a broken power-law shape as predicted by theoretical models, although the observed break is considerably earlier than what is expected from theory. After rapid cooling during the first 200 days of quiescence---strongly indicating a highly conductive neutron star crust---the source unexpectedly showed a large temporary increase in both thermal and non-thermal flux. Prompted by this we conducted a Swift monitoring program of the source during April-October 2010, with short observations taking place once every two weeks. During the program we detected short-term flares up to at least 1×1035 erg/s, a factor of 20 higher than the normal quiescent level. We compare this flaring---presumably arising from episodic low-level accretion---with the behavior observed from faint Galactic transients, and discuss whether flaring in XTE J1701-462 can significantly affect the cooling of the source and whether it can to some extent explain the high temperature of the neutron star core implied by our Chandra observations.

  7. Computer calculation of neutron cross sections with Hauser-Feshbach code STAPRE incorporating the hybrid pre-compound emission model

    International Nuclear Information System (INIS)

    Computer codes incorporating advanced nuclear models (optical, statistical and pre-equilibrium decay nuclear reaction models) were used to calculate neutron cross sections needed for fusion reactor technology. The elastic and inelastic scattering (n,2n), (n,p), (n,n'p), (n,d) and (n,γ) cross sections for stable molybdenum isotopes Mosup(92,94,95,96,97,98,100) and incident neutron energy from about 100 keV or a threshold to 20 MeV were calculated using the consistent set of input parameters. The hydrogen production cross section which determined the radiation damage in structural materials of fusion reactors can be simply deduced from the presented results. The more elaborated microscopic models of nuclear level density are required for high accuracy calculations

  8. Investigation of background in large-area neutron detectors due to alpha emission from impurities in aluminium

    CERN Document Server

    Birch, J; Clergeau, J -F; van Esch, P; Ferraton, M; Guerard, B; Hall-Wilton, R; Hultman, L; Höglund, C; Jensen, J; Khaplanov, A; Piscitelli, F

    2015-01-01

    Thermal neutron detector based on films of $^{10}$B$_4$C have been developed as an alternative to $^3$He detectors. In particular, The Multi-Grid detector concept is considered for future large area detectors for ESS and ILL instruments. An excellent signal-to-background ratio is essential to attain expected scientific results. Aluminium is the most natural material for the mechanical structure of of the Multi-Grid detector and other similar concepts due to its mechanical and neutronic properties. Due to natural concentration of $\\alpha$ emitters, however, the background from $\\alpha$ particles misidentified as neutrons can be unacceptably high. We present our experience operating a detector prototype affected by this issue. Monte Carlo simulations have been used to confirm the background as $\\alpha$ particles. The issues have been addressed in the more recent implementations of the Multi-Grid detector by the use of purified aluminium as well as Ni-plating of standard aluminium. The result is the reduction in...

  9. Gamma-Ray Emission Spectra as a Constraint on Calculations of 234,236,238U Neutron-Capture Cross Sections

    Energy Technology Data Exchange (ETDEWEB)

    Ullmann, John Leonard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kawano, Toshihiko [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bredeweg, Todd Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baramsai, Bayarbadrakh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Couture, Aaron Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haight, Robert Cameron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jandel, Marian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mosby, Shea Morgan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O' Donnell, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vieira, David J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wilhelmy, Jerry B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Becker, John A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wu, Ching-Yen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Krticka, Milan [Charles Univ., Prague (Czech Republic)

    2015-05-28

    Neutron capture cross sections in the “continuum” region (>≈1 keV) and gamma-emission spectra are of importance to basic science and many applied fields. Careful measurements have been made on most common stable nuclides, but physicists must rely on calculations (or “surrogate” reactions) for rare or unstable nuclides. Calculations must be benchmarked against measurements (cross sections, gamma-ray spectra, and <Γγ>). Gamma-ray spectrum measurements from resolved resonances were made with 1 - 2 mg/cm2 thick targets; cross sections at >1 keV were measured using thicker targets. The results show that the shape of capture cross section vs neutron energy is not sensitive to the form of the strength function (although the magnitude is); the generalized Lorentzian E1 strength function is not sufficient to describe the shape of observed gamma-ray spectra; MGLO + “Oslo M1” parameters produces quantitative agreement with the measured 238U(n,γ) cross section; additional strength at low energies (~ 3 MeV) -- likely M1-- is required; and careful study of complementary results on low-lying giant resonance strength is needed to consistently describe observations.

  10. Evidence for Quasi-Periodic Oscillations in the Recurrent Emission from Magnetars and their Implications on the Neutron Star Properties and Equation of State

    CERN Document Server

    El-Mezeini, Ahmed M

    2010-01-01

    We present an analysis of highly magnetized neutron stars "magnetars", in search for high frequency oscillations in the recurrent emission from the soft gamma repeater SGR 1806-20, and we discuss the physical interpretation of these oscillations and its implications on the neutron star properties and structure. We present evidence for Quasi-Periodic Oscillations (QPOs) in the recurrent outburst activity from SGR 1806-20 using RXTE observations. By searching for timing signals at the frequencies of the QPOs discovered in the 2004 December 27 giant flare from the source, we find three QPOs at 84, 103, and 648 Hz in three different bursts. The first two QPOs lie within 8.85% and 11.83%, respectively, from the 92 Hz QPO detected in the giant flare. The third QPO lie within 3.75% from the 625 Hz QPO also detected in the same flare. The detected QPOs are found in bursts with different durations, morphologies, and brightness, and are vindicated by Monte Carlo simulations. We also find evidence for candidate QPOs at ...

  11. Determination of trace elements in Egyptian cane sugar (Deshna Factories) by neutron activation, atomic absorption spectrophotometric and inductively coupled plasma-atomic emission spectrometric analysis

    International Nuclear Information System (INIS)

    Multielement instrumental neutron activation (INAA), inductively coupled plasma-atomic emission spectrometric (ICP-AES) and atomic absorption spectrophotometric (AAS) analyses were utilized for the determination of Ag, Al, As, Au, Ba, Be, Br, Ca, Cd, Ce, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hf, K, La, Li, Lu, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Th, Ti, U, V, W and Zn in sugar cane plant, raw juice, juice in different stages, syrup, deposits, molasses, A, B and C sugar, refinery 1 and 2 sugar, and in soil samples picked up from the immediate vicinity of the cane plant roots at surface, 30 and 60 cm depth, respectively. (author)

  12. Neutron stimulated emission computed tomography applied to the assessment of calcium deposition due to the presence of microcalcifications associated with breast cancer; Tomografia computadorizada de emissao estimulada por neutrons aplicada para avaliar a deposicao de calcio devido a presenca de microcalcificacoes associadas ao cancer de mama

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Rodrigo S.S.; Yoriyaz, Helio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, (SP) (Brazil)

    2011-07-01

    In this paper we presented an application of the Neutron Stimulated Emission Computed Tomography (NSECT), which uses a thin beam of fast neutrons to stimulate stable nuclei in a sample, emitting characteristic gamma radiation. The photon energy is unique and it is used to identify the emitting nuclei. This technique was applied for evaluating the calcium isotopic composition changing due to the development of breast microcalcifications. A particular situation was simulated in which clustered microcalcifications were modeled with diameters less than 1.40 mm. In this case, neutron beam breast spectroscopy was successful in detecting the counting changes in the photon emission spectra for energies, which are characteristics of 4{sup 0C}a isotope in a low deposited dose rate. (author)

  13. Low-energy of neutron-rich nuclei near the N=40 subshell closure studied by beta decay

    International Nuclear Information System (INIS)

    Full text: Advances in radioactive beam technology have opened up new areas of the chart of the nuclides for nuclear structure studies. For instance, the ground state and low energy properties of neutron-rich nuclides from Ca (Z=20) to Ni (Z=28) have remained virtually unstudied. The application of both resonance laser ionization with isotope separation on-line and intermediate energy projectile fragmentation has resulted in a wealth of new data in this region, particularly for nuclei near the neutron subshell closure at N=40. The recent beta decay work in this region will be discussed, with focus put on beta-delayed gamma ray studies of neutron-rich nuclei produced by fragmentation of intermediate-energy Ge-76 and Zn-70 beams at the National Superconducting Cyclotron Lab at Michigan State University. The results will be presented in light of the goodness of the N=40 subshell closure as one moves away from 'doubly-magic' Ni-68

  14. Investigation of the Triton Emission Asymmetry in the $^{6}$Li(n, alpha)$^{3}$H Reaction with Polarized Thermal Neutrons

    CERN Document Server

    Gledenov, Yu M; Nesvizhevsky, V V; Petukhov, A K; Sedyshev, P V; Soldner, T; Shulgina, E V; Zimmer, O

    2002-01-01

    An experiment was carried out at the high-intensity polarized cold neutron beam of the PF1B instrument of the ILL reactor, Grenoble, France. As a detector, the 48-section ionization chamber with the ^{6}LiF targets was used. An integral (current) method of the event detection with compensation of the reactor power fluctuation was applied. Special measurement technique was used for minimization and estimation of the possible false effect contribution. A value of the P-odd (sigma_{\\bf n}, {\\bf P}_{\\bf n}) correlation has been obtained: alpha_{PN}=-(7.1\\pn 3.9)\\cdot 10^{-8}. At the base of the cluster model, the most accurate at present day estimation of the weak neutral current constant has been given: f_n \\leq 1.2\\cdot 10^{-7}.

  15. Spectrometry and emission tomographic image reconstruction stimulated by neutrons via EM algorithm and Monte Carlo Method; Espectrometria e reconstrucao de imagens tomograficas de emissao estimulada por neutrons via algoritmo EM e metodo de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Rodrigo Sartorelo Salemi

    2014-07-01

    The NSECT (Neutron Stimulated Emission Computed Tomography) figures as a new spectrographic technique able to evaluate in vivo the concentration of elements using the inelastic scattering reaction (n,n'). Since its introduction, several improvements have been proposed with the aim of investigating applications for clinical diagnosis and reduction of absorbed dose associated with CT acquisition. In this context, two new diagnostic applications are presented using spectroscopic and tomographic approaches from NSECT. A new methodology has also been proposed to optimize the sinogram sampling that is directly related to the quality of the reconstruction by the irradiation protocol. The studies were developed based on simulations with MCNP5 code. Diagnosis of Renal Cell Carcinoma (RCC) and the detection of breast microcalcifications were evaluated in studies conducted using a human phantom. The obtained results demonstrate the ability of the NSECT technique to detect changes in the composition of the modeled tissues as a function of the development of evaluated pathologies. The proposed method for optimizing sinograms was able to analytically simulate the composition of the irradiated medium allowing the assessment of quality of reconstruction and effective dose in terms of the sampling rate. However, future research must be conducted to quantify the sensitivity of detection according to the selected elements. (author)

  16. Passive neutron assay of irradiated nuclear fuels

    International Nuclear Information System (INIS)

    Passive neutron assay of irradiated nuclear fuel has been investigated by calculations and experiments as a simple, complementary technique to the gamma assay. From the calculations it is found that the neutron emission arises mainly from the curium isotopes, the neutrons exhibit very good penetrability of the assemblies, and the neutron multiplication is not affected by the burnup. From the experiments on BWR and PWR assemblies, it is found that the neutron emission rate is proportional to burnup raised to 3.4 power. Recent investigations indicate that the passive neutron assay is a simple and useful technique to determine the consistency of burnups between assemblies. 10 refs

  17. Passive neutron assay of irradiated nuclear fuels

    International Nuclear Information System (INIS)

    Passive neutron assay of irradiated nuclear fuel has been investigated by calculations and experiments as a simple, complementary technique to the gamma assay. From the calculations it was found that the neutron emission arises mainly from the curium isotopes, the neutrons exhibit very good penetrability of the assemblies, and the neutron multiplication is not affected by the burnup. From the experiments on BWR and PWR assemblies, the neutron emission rate is proportional to burnup raised to 3.4 power. The investigations indicate that the passive neutron assay is a simple and useful technique to determine the consistency of burnups between assemblies

  18. Constraints on Thermal X-Ray Radiation from SAX J1808.4-3658 and Implications for Neutron Star Neutrino Emission

    NARCIS (Netherlands)

    C.O. Heinke; P.G. Jonker; R. Wijnands; R.E. Taam

    2007-01-01

    Thermal X-ray radiation from neutron star soft X-ray transients in quiescence provides the strongest constraints on the cooling rates of neutron stars and thus on the interior composition and properties of matter in the cores of neutron stars. We analyze new (2006) and archival (2001) XMM-Newton obs

  19. Neutrons from Piezonuclear Reactions

    CERN Document Server

    Cardone, F; Mignani, R; Perconti, W; Petrucci, A; Rosetto, F; Spera, G

    2007-01-01

    We report the results obtained by cavitating water solutions of iron salts (iron chloride and iron nitrate) with different concentrations at different ultrasound powers. In all cases we detected a neutron radiation well higher than the background level. The neutron production is perfectly reproducible and can at some extent be controlled. These evidences for neutron emission generated by cavitation support some preliminary clues for the possibility of piezonuclear reactions (namely nuclear reactions induced by pressure and shock waves) obtained in the last ten years. We have been able for the first time to state some basic features of such a neutron emission induced by cavitation, namely: 1) a marked threshold behavior in power, energy and time; 2) its occurring without a concomitant production of gamma radiation.

  20. The optical/UV excess of X-ray dim isolated neutron star:bremsstrahlung emission from a strange star plasma atmosphere

    CERN Document Server

    Wang, Weiyang; Tong, Hao; Ge, Mingyu; Li, Zhaosheng; Men, Yunpeng; Xu, Renxin

    2016-01-01

    X-ray dim isolated neutron stars (XDINSs) are characterized by Planckian spectra in X-ray bands, but show optical/ultraviolet(UV) excesses which are the measured photometry exceeding that extrapolated from X-ray spectra. To solve this problem, a radiative model of bremsstrahlung emission from a plasma atmosphere is constructed in the regime of strange (quark-cluster) star. The plasma atmosphere is supposed to be of two-temperature, formed and maintained by the ISM-accreted matter which is bound on a star's surface because of the so-called strangeness barrier. All the seven XDINS spectra could be well fitted by the radiative model, from optical/UV to X-ray bands. The fitted radiation radii of XDINSs are from 7 to 13 km, while the modelled electron temperatures are between 50 and 250 eV, except RX J0806.4$-$4123 with a radiation radius $\\sim 3$ km, indicating that this source could be a low-mass strange star candidate.

  1. On the origin of the near-infrared emission from the neutron-star low-mass X-ray binary GX 9+1

    CERN Document Server

    Berg, Maureen van den

    2016-01-01

    We have determined an improved position for the luminous persistent neutron-star low-mass X-ray binary and atoll source GX 9+1 from archival Chandra X-ray Observatory data. The new position significantly differs from a previously published Chandra position for this source. Based on the revised X-ray position we have identified a new near-infrared (NIR) counterpart to GX 9+1 in Ks-band images obtained with the PANIC and FourStar cameras on the Magellan Baade Telescope. NIR spectra of this Ks=16.5+-0.1 mag star taken with the FIRE spectrograph on the Baade Telescope show a strong Br-gamma emission line, which is a clear signature that we discovered the true NIR counterpart to GX 9+1. The mass donor in GX 9+1 cannot be a late-type giant, as such a star would be brighter than the estimated absolute Ks magnitude of the NIR counterpart. The slope of the dereddened NIR spectrum is poorly constrained due to uncertainties in the column density N_H and NIR extinction. Considering the source's distance and X-ray luminos...

  2. Study of the emission of a light particle charged during the fission of 235U by thermal neutron

    International Nuclear Information System (INIS)

    In a first part, this research thesis discusses the existing theories of the mechanism of emission of light particles charged of tri-partition (tri-partition is defined as an event involving two big fragments of masses comparable with those obtained in binary fission, and a charged light particle). Then, the author presents and reports an experiment performed by suing nuclear emulsions. Another type of experiment is then presented which allows the measurement of masses and energies of tri-partition fragments. The author then presents theoretical calculations which have been performed in order to find again some characteristics of tri-partition. These calculations are mainly based on Coulomb repulsion between various fragments

  3. The Neutron Star Zoo

    CERN Document Server

    Harding, Alice K

    2013-01-01

    Neutron stars are a very diverse population, both in their observational and their physical properties. They prefer to radiate most of their energy at X-ray and gamma-ray wavelengths. But whether their emission is powered by rotation, accretion, heat, magnetic fields or nuclear reactions, they are all different species of the same animal whose magnetic field evolution and interior composition remain a mystery. This article will broadly review the properties of inhabitants of the neutron star zoo, with emphasis on their high-energy emission.

  4. Nanostructure Neutron Converter Layer Development

    Science.gov (United States)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  5. Neutron Radiography

    OpenAIRE

    Reddy, A. R.; Rao, M. V. N.

    2012-01-01

    The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  6. Chandra Observations of Neutron Stars -- An Overview

    OpenAIRE

    Weisskopf, M. C.

    2002-01-01

    We present a brief review of Chandra observations of neutron stars, with a concentration on neutron stars in supernova remnants. The early Chandra results clearly demonstrate how critical the angular resolution has been in order to separate the neutron star emission from the surrounding nebulosity.

  7. Broad-band X-ray emission and the reality of the broad iron line from the neutron star-white dwarf X-ray binary 4U 1820-30

    Science.gov (United States)

    Mondal, Aditya S.; Dewangan, G. C.; Pahari, M.; Misra, R.; Kembhavi, A. K.; Raychaudhuri, B.

    2016-09-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disc. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here, we investigate the reality of the broad iron line detected earlier from the neutron-star low-mass X-ray binary 4U 1820-30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broad-band spectral study of the atoll source using Suzaku and simultaneous NuSTAR and Swift observations. We have used different continuum models involving accretion disc emission, thermal blackbody and thermal Comptonization of either disc or blackbody photons. The Suzaku data show positive and negative residuals in the region of Fe K band. These features are well described by two absorption edges at 7.67 ± 0.14 keV and 6.93 ± 0.07 keV or partial covering photoionized absorption or by blurred reflection. Though, the simultaneous Swift and NuSTAR data do not clearly reveal the emission or absorption features, the data are consistent with the presence of either absorption or emission features. Thus, the absorption based models provide an alternative to the broad iron line or reflection model. The absorption features may arise in winds from the inner accretion disc. The broad-band spectra appear to disfavour continuum models in which the blackbody emission from the neutron-star surface provides the seed photons for thermal Comptonization. Our results suggest emission from a thin accretion disc (kTdisc ˜ 1 keV), Comptonization of disc photons in a boundary layer most likely covering a large fraction of the neutron-star surface and innermost parts of the accretion disc, and blackbody emission (kTbb ˜ 2 keV) from the polar regions.

  8. Prompt Neutrons from Fission

    International Nuclear Information System (INIS)

    A survey is given of the present state of knowledge of the spectrum, angular distribution and number of prompt fission neutrons, as functions of incident neutron energy and individual fragment mass, for low-energy fission. The energy spectrum of prompt neutrons has been found to be of the same form (nearly Maxwellian) for many different types of fission. It has been shown that this type of spectrum is to be expected on the basis of evaporation from moving fragments, and theoretical predictions of the spectrum agree very accurately with experimental data. Some data are now available on the variation of the neutron spectrum with fragment mass and angle of emission. Only recently has it become possible to take accurate data on the angular distribution of the neutrons. It appears that the neutrons have the angular distribution to be expected if emitted almost isotropically from the moving fragments, with a possibility that some small fraction are not emitted in this way, but directly from the fissioning nuclide. Much work has been done on the variation of fission neutron number v with incident neutron energy for neutron-induced fission. The neutron number increases roughly linearly with energy, with a slope of about 0.15 n/MeV. There is now evidence that this slope changes somewhat with energy. This change must be associated with other changes in the-fission process. The most interesting recent discovery concerning fission neutrons is the strong dependence of neutron number on individual fragment mass. The data are being rapidly improved by means of the newer techniques of determining fragment mass yields from velocity and pulse-height data, and of determining neutron yields from cumulative mass yields. There is evidence of similar dependence of neutron yield on fragment mass in a number of cases. It has been suggested that this property is directly connected with the deformability of the fragments, and in particular with the near-spherical shapes of magic

  9. Neutron Skins and Neutron Stars

    OpenAIRE

    Piekarewicz, J

    2013-01-01

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron be...

  10. Piezonuclear neutrons from fracturing of inert solids

    OpenAIRE

    Cardone, F.; A. Carpinteri; Lacidogna, G.

    2009-01-01

    Neutron emission measurements by means of helium-3 neutron detectors were performed on solid test specimens during crushing failure. The materials used were marble and granite, selected in that they present a different behaviour in compression failure (i.e., a different brittleness index) and a different iron content. All the test specimens were of the same size and shape. Neutron emissions from the granite test specimens were found to be of about one order of magnitude higher than the natura...

  11. Neutron and gamma-ray emission double differential cross sections for the nuclear reaction by 1.5 GeV {pi}{sup +} incidence

    Energy Technology Data Exchange (ETDEWEB)

    Iga, Kiminori; Ishibashi, Kenji; Shigyo, Nobuhiro [Kyushu Univ., Fukuoka (Japan)] [and others

    1998-03-01

    Neutron and gamma-ray production double differential cross sections were measured for iron by the use of 1.5 GeV {pi}{sup +} mesons. The measured cross sections were compared with the calculated values by HETC-KFA2. For the neutrons, the calculated results deviate from the experimental data in the neutron energy region below 30 MeV. The calculated values of gamma-ray production agree with the experimental data at gamma-ray energies from 1 to 7 MeV within a factor of three. (author)

  12. Neutron Radiography

    Directory of Open Access Journals (Sweden)

    A. R. Reddy

    1982-07-01

    Full Text Available The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  13. Development of a photonuclear activation file and measurement of delayed neutron spectra; Creation d'une bibliotheque d'activation photonucleaire et mesures de spectres d'emission de neutrons retardes

    Energy Technology Data Exchange (ETDEWEB)

    Giacri-Mauborgne, M.L

    2005-11-15

    This thesis work consists in two parts. The first part is the description of the creation of a photonuclear activation file which will be used to calculated photonuclear activation. To build this file we have used different data sources: evaluations but also calculations done using several cross sections codes (HMS-ALICE, GNASH, ABLA). This file contains photonuclear activation cross sections for more than 600 nuclides and fission fragments distributions for 30 actinides at tree different Bremsstrahlung energies and the delay neutron spectrum associated. These spectra are not in good agreement with experimental data. That is why we decided to launch measurement of delayed neutrons spectra from photofission. The second part of this thesis consists in demonstrating the possibility to do such measurements at the ELSA accelerator facility. To that purpose, we have developed the detection, the acquisition system and the analysis method of such spectra. These were tested for the measurement of the delayed neutron spectrum of uranium-238 after irradiation in a 2 MeV neutron flux. Finally, we have measured the delayed neutron spectrum of uranium-238 after irradiation in a 15 MeV Bremsstrahlung flux. We compare our results with experimental data. The experiment has allowed us to improve the value of {nu}{sub p}-bar with an absolute uncertainty below 7%, we propose {nu}{sub p}-bar = (3.03 {+-} 0.02) n/100 fissions, and to correct the Nikotin's parameters for the six group representation. Particularly, we have improved the data concerning the sixth group by taking into account results from different irradiation times.

  14. The ITER radial neutron camera: An updated neutronic analysis

    International Nuclear Information System (INIS)

    The radial neutron camera (RNC) will provide the spatial distribution and the total strength of the ITER neutron source (emissivity profile and fusion power) by means of collimated neutron measurements. Line-integrated neutron spectral measurements can also provide information on the ion temperature profile. The present design of the RNC consists of two collimating structures for a full coverage of the plasma: 36 collimated lines of sight (LOS) distributed in three different planes view the plasma core (ex-port system) and nine collimated LOS view the plasma edge (in-port system). The RNC design is based on the combined use of the MCNP Monte Carlo code and a software tool performing asymmetric Abel inversion of simulated measured neutron signals (MSST). Neutron and γ-ray transport calculations are performed with MCNP using a 3D RNC model to determine the signal/noise for each RNC channel and the spectra at the detectors. The MSST code is used to check the RNC compliance with the ITER measurement requirements for the neutron emissivity profile. In the present paper the improvement of the hard variance reduction technique applied to the MCNP neutron source (consisting in sampling neutrons only from plasma regions contributing to the detector signal) is presented and the following issues are analyzed: the possibility of reducing the length of the ex-port collimators (resulting in a significant reduction of the overall RNC dimension and weight); options for the reduction of the dose due to the neutron streaming through the RNC cut-outs in the blanket shielding module; the integration of a γ-ray detection system in the RNC by partially filling the collimators with a neutron absorbing material (LiH).

  15. Neutron Capture and Neutron Halos

    OpenAIRE

    A.Mengoni; Otsuka, T; Nakamura, T.(International Center for Elementary Particle Physics and Department of Physics, The University of Tokyo, Tokyo, Japan); Ishihara, M.

    1996-01-01

    The connection between the neutron halo observed in light neutron rich nuclei and the neutron radiative capture process is outlined. We show how nuclear structure information such as spectroscopic factors and external components of the radial wave function of loosely bound states can be derived from the neutron capture cross section. The link between the direct radiative capture and the Coulomb dissociation process is elucidated.

  16. Experimental study of fusion nuclei formation and deexcitation for mass around 150μ formed by bombardment of heavy ions at 3 to 5 MeV/nucleon energy. Emission of a few neutrons (1, 2 or 3)

    International Nuclear Information System (INIS)

    It has been experimentally pointed out that a nucleus formed, in the rare earth region, at high angular momentum (approximately 40 h) and high excitation energy (approximately 55 MeV), through a rather symetric system (like 65Cu + 87Rb → 152Dy), can deexcite by emitting only 1 or 2 neutrons. To explore the statistical or non-statistical character of a few neutrons emission, γ-n competition has been studied. All the measurements (total γ energy, γ-multiplicity associated with each exit channel, and neutron energy spectra) point out the statistical character, which is related to the unexpectadly strong γ-competition at high J :the γ entry-line constructed in the (E * J) plane for several identified exit channels, diverges from the Yrast line at the highest J. Comparison between various experimental results (including excitation functions (HI, xn) sup(150-x)Gd) and statistical calculations (GROGI-F code) has been used as a crucial test for the choice of the Yrast-line position and of the γ-normalization coefficients. Some experimental results concerning sub-barrier fusion and fission cross-sections are also presented in this thesis

  17. Detection of pulsations and a spectral feature in the X-ray emission of the isolated neutron star 1RXS J214303.7+065419/RBS 1774

    CERN Document Server

    Zane, S; Turolla, R; Zampieri, L; Chieregato, M; Drake, J J; Treves, A

    2005-01-01

    We report on the results of a deep XMM-Newton observation of RBS 1774, the most recent dim isolated neutron star candidate found in the ROSAT archive data. Spectral and timing analysis of the high-quality PN and MOS data confirm the association of this source with an isolated neutron star. The spectrum is thermal and blackbody-like, and there is evidence at a significance level > 4sigma that the source is an X-ray pulsar, with spin period of 9.437 s. Spectral fitting reveils the presence of an absorption feature at ~0.7 keV, but at this level data do not have enough resolution to allow us to discriminate between an absorption line or an edge. We compare the newly measured properties of RBS 1774 with those of other known dim isolated neutron stars, and discuss possible interpretations for the absorption feature.

  18. Broadband X-ray emission and the reality of the broad iron line from the Neutron Star - White Dwarf X-ray binary 4U 1820-30

    CERN Document Server

    Mondal, Aditya S; Pahari, Mayukh; Misra, Ranjeev; Kembhavi, Ajit K; Raychaudhuri, Biplab

    2016-01-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disk. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here we investigate the reality of the broad iron line detected earlier from the neutron star low mass X-ray binary 4U~1820--30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broadband spectral study of the atoll source using \\suzaku{} and simultaneous \

  19. Plasma focus neutron source

    International Nuclear Information System (INIS)

    A neutron source not permanently active is obtained from an electric discharge plasma focus (PF) device. A small PF device, a Mather model device, works in the limit of low energy, 100 to 200 J at charging voltage of 20 to 30 kV with a capacitor bank of 160 nF, and a characteristic inductance of 25 to 50 nH. A theoretical model leads us to estimate the optimum values of capacitance, inductance, initial charging voltage and electrode geometry. In this work is presented the design evolution and construction of a first PF neutron source prototype, preliminary measures of current, voltage and temporal evolution of the current with the end of have an electric characterization. This parameters must be optimized with the objective of geeting an emission of 104 to 105 neutrons per pulse when Deuterium is used like filled gas (C.W)

  20. Neutronic Design and Measured Performance of the Low Energy Neutron Source (LENS) Target Moderator Reflector Assembly

    CERN Document Server

    Lavelle, C M; Bogdanov, A; Derenchuk, V P; Kaiser, H; Leuschner, M B; Lone, M A; Lozowski, W; Nann, H; Von Przewoski, B; Remmes, N; Rinckel, T; Shin, Y; Snow, W M; Sokol, P E

    2008-01-01

    The Low Energy Neutron Source (LENS) is an accelerator-based pulsed cold neutron facility under construction at the Indiana University Cyclotron Facility (IUCF). The idea behind LENS is to produce pulsed cold neutron beams starting with ~MeV neutrons from (p,n) reactions in Be which are moderated to meV energies and extracted from a small solid angle for use in neutron instruments which can operate efficiently with relatively broad (~1 msec) neutron pulse widths. Although the combination of the features and operating parameters of this source is unique at present, the neutronic design possesses several features similar to those envisioned for future neutron facilities such as long-pulsed spallation sources (LPSS) and very cold neutron (VCN) sources. We describe the underlying ideas and design details of the target/moderator/reflector system (TMR) and compare measurements of its brightness, energy spectrum, and emission time distribution under different moderator configurations with MCNP simulations. Brightnes...

  1. MeV Neutron Production from Thermal Neutron Capture in {6}^Li Simulated with Geant4

    CERN Document Server

    Santoro, Valentina; Bentley, Phillip M

    2015-01-01

    Various Li compounds are commonly used at neutron facilities as neutron absorbers. These compounds provide one of the highest ratios of neutron attenuation to $\\gamma$-ray production. Unfortunately, the usage of these compounds can also give rise to fast neutron emission with energies up to almost 16 MeV. Historically, some details in this fast neutron production mechanism can be absent from some modeling packages under some optimization scenarios. In this work, we tested Geant4 to assess the performance of this simulation toolkit for the fast neutron generation mechanism. We compare the results of simulations performed with Geant4 to available measurements. The outcome of our study shows that results of the Geant4 simulations are in good agreement with the available measurements for $^6$Li fast neutron production, and suitable for neutron instrument background evaluation at spallation neutron sources.

  2. Fast neutron instrumentation for beam diagnostic

    OpenAIRE

    Rebai,

    2012-01-01

    This thesis concerns the development of fast neutron instrumentation for beam diagnostic. Two kind of detectors have been developed. The first is a diamond detector for fast neutron measurements at the ChipIr beamline of the ISIS spallation neutron source (Didcot, UK). ISIS is a 50Hz-pulsed source in which neutrons are produced by 800 MeV protons interacting on a heavy metal target. The second is a Gas Electron Multiplier (GEM) detector developed for measurements of the neutron emission map ...

  3. Neutron detector

    Science.gov (United States)

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  4. 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)

  5. Linking Jet Emission, X-Ray States, and Hard X-Ray Tails in the Neutron Star X-Ray Binary GX 17+2

    NARCIS (Netherlands)

    S. Migliari; J.C.A. Miller-Jones; R.P. Fender; J. Homan; T. di Salvo; R.E. Rothschild; M.P. Rupen; J.A. Tomsick; R. Wijnands; M. van der Klis

    2007-01-01

    We present the results of simultaneous radio (VLA) and X-ray (RXTE) observations of the Z-type neutron star X-ray binary GX 17+2. The aim is to assess the coupling between X-ray and radio properties throughout its three rapidly variable X-ray states and during the time-resolved transitions. These ob

  6. Measurement of Secondary Neutron Emission Double-differential Cross Section for ~9Be Induced by 8.19 MeV Neutrons%8.19MeV中子与~9Be作用的次级中子双微分截面测量

    Institute of Scientific and Technical Information of China (English)

    张雅玲; 阮锡超; 姚泽恩; 黄翰雄; 李霞; 周祖英; 唐洪庆; 聂阳波; 鲍杰

    2011-01-01

    The secondary neutron emission double-differential cross section of 9Be induced by 8.19 MeV neutron was measured at 26 different angles from 20° to 150° by using the multi-detector fast neutron TOF spectrometer at the HI-13 Tandem Accelerator at China Institute of Atomic Energy(CIAE).The results were normalized to n-p scattering measurement.A special Monte-Carlo code which was validated with the MCNP-4C code was employed to analyze the measured data for the corrections of neutron flux attenuation,multiple scattering and finite geometry.The measured results were compared with the evaluated data and the other measurements.%用中国原子能科学研究院HI-13串列加速器上的多探测器快中子飞行时间谱仪,测量了8.19 MeV中子与9Be作用时,从20°到160°区间26个角度的次级中子双微分截面。测量截面以n-p散射截面作为标准进行归一。实验结果用Monte-Carlo方法进行了中子注量率衰减、多次散射和有限几何修正,并用MCNP-4C程序对所用的Monte-Carlo程序进行了验证。测量结果与评价数据以及其它实验室的数据进行了比较。

  7. Atmospheric neutrons

    International Nuclear Information System (INIS)

    Additional calibrations of the University of California double-scatter neutron and additional analysis corrections lead to the slightly changed neutron fluxes reported here. The theoretical angular distributions of Merker (1975) are in general agreement with our experimental fluxes but do not give the peaks for vertical upward and downward moving neutrons. The theoretical neutron escape current J2/sub pi/ (Merker, 1972; Armstrong et al., 1973) is in agreement with the experimental values from 10 to 100 MeV. Our experimental fluxes agree with those of the Kanbach et al. (1974) in the overlap region from 70 to 100 MeV

  8. Neutron Albedo

    CERN Document Server

    Ignatovich, V K

    2005-01-01

    A new, algebraic, method is applied to calculation of neutron albedo from substance to check the claim that use of ultradispersive fuel and moderator of an active core can help to gain in size and mass of the reactor. In a model of isotropic distribution of incident and reflected neutrons it is shown that coherent scattering on separate grains in the case of thermal neutrons increases transport cross section negligibly, however it decreases albedo from a wall of finite thickness because of decrease of substance density. A visible increase of albedo takes place only for neutrons with wave length of the order of the size of a single grain.

  9. Neutron Sources for Standard-Based Testing

    Energy Technology Data Exchange (ETDEWEB)

    Radev, Radoslav [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McLean, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-11-10

    The DHS TC Standards and the consensus ANSI Standards use 252Cf as the neutron source for performance testing because its energy spectrum is similar to the 235U and 239Pu fission sources used in nuclear weapons. An emission rate of 20,000 ± 20% neutrons per second is used for testing of the radiological requirements both in the ANSI standards and the TCS. Determination of the accurate neutron emission rate of the test source is important for maintaining consistency and agreement between testing results obtained at different testing facilities. Several characteristics in the manufacture and the decay of the source need to be understood and accounted for in order to make an accurate measurement of the performance of the neutron detection instrument. Additionally, neutron response characteristics of the particular instrument need to be known and taken into account as well as neutron scattering in the testing environment.

  10. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Fratin, Luciano

    1993-12-31

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

  11. Neutron measurements in ITER using the Radial Neutron Camera

    Science.gov (United States)

    Marocco, D.; Esposito, B.; Moro, F.

    2012-03-01

    The Radial Neutron Camera (RNC) is one of the key diagnostic systems of the ITER international fusion experiment. It is designed to measure the uncollided 14 MeV and 2.5 MeV neutrons from deuterium-tritium (DT) and deuterium-deuterium (DD) fusion reactions taking place in the ITER plasma through an array of 45 detectors positioned along collimated lines of sight. Scintillators and diamonds coupled to fast digital acquisition electronics are among the detectors presently considered for the RNC. The RNC will provide spatially resolved measurements of several plasma parameters needed for fusion power estimation, plasma control and plasma physics studies. The line-integrated RNC neutron fluxes are used to evaluate the local profile of the neutron emission (neutron emissivity, s-1m-3) and therefore the total neutron yield and the birth profile of the alpha particles. The temperature profile of the bulk ions can be derived from the Doppler broadened widths of the RNC line-integrated spectra, that also provide insight on the supra-thermal ions produced by the injection in the plasma of electromagnetic waves and neutral particles. The RNC emissivity and temperature measurements can be employed to estimate the composition of the ITER fuel, namely the ratio between the tritium and deuterium densities. Data processing techniques involving spatial inversion and spectra unfolding are necessary to deduce the profile quantities from the line-integrated RNC measurements. The expected performances of the RNC as a diagnostic for the neutron emissivity/ion temperature/fuel ratio profile (measurement range, time resolution, accuracy, precision) have been estimated by means of synthetic data simulating actual RNC measurements. The results of the simulations, together with an overall description of the diagnostic and of the measurement techniques, are presented.

  12. Measurements of double differential charged particle emission cross sections and development of a wide range charged particles spectrometer for ten`s MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Nauchi, Yasushi; Baba, Mamoru; Kiyosumi, Takehide [Tohoku Univ., Sendai (Japan). Faculty of Engineering] [and others

    1997-03-01

    We measured (n,xp), (n,xd) cross sections of C and Al for En=64.3 MeV neutrons at the {sup 7}Li(p,n) neutron sources facility at TIARA (Takasaki Establishment, JAERI) by using a conventional SSD-NaI telescope placed in the air. They show characteristic energy and angular dependence in high energy regions. In order to extend the measurements to low energy protons and {alpha} particles, a new spectrometer consisting of low pressure gas counters and BaF{sub 2} scintillators is now under development. A low threshold for low energy {alpha} particles will be achieved by using the gas counters. The particle identification over a wide energy range will be achieved by combining the {Delta}E-E method for low energy particles with the pulse shape discrimination (PSD) method of BaF{sub 2} for high energy particles. (author)

  13. Neutron tubes

    Science.gov (United States)

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  14. On neutron stars in f(R) theories: small radii, large masses and large energy available for emission in a merger

    CERN Document Server

    Resco, Miguel Aparicio; Estrada, Felipe J Llanes; Castrillo, Victor Zapatero

    2016-01-01

    In the context of f(R) gravity theories, we show that the apparent mass of a neutron star as seen from an observer at infinity is numerically calculable but requires careful matching, first at the star's edge, between interior and exterior solutions, none of them being totally Schwarzschild-like but presenting instead small oscillations of the curvature scalar R; and second at large radii, where the Newtonian potential is used to identify the mass of the neutron star. We find that for the same equation of state, this mass definition is always larger than its general relativistic counterpart. We exemplify this with quadratic R^2 and Hu-Sawicki-like modifications of the standard General Relativity action. Therefore, the finding of two-solar mass neutron stars basically imposes no constraint on stable f(R) theories. However, star radii are in general smaller than in General Relativity, which can give an observational handle on such classes of models at the astrophysical level. Both larger masses and smaller matt...

  15. An investigation into a suitable scintillator for localising neutron capture within a detector

    OpenAIRE

    Balmer, Matthew; Gamage, Kelum; Taylor, Graeme

    2014-01-01

    Using Monte-Carlo modelling, an investigation into a suitable loaded scintillator for localising neutron capture in a novel neutron survey meter has been undertaken. A comparison of estimated neutron capture location in a scintillator with Geant4 and MCNP simulations was undertaken and a good general agreement between the two models was observed. The interactions of γ emissions from neutron capture in the scintillator are investigated. The results show that the γ emission from neutron capture...

  16. Superfluid Neutrons in the Core of the Neutron Star in Cassiopeia A

    CERN Document Server

    Page, Dany; Lattimer, James M; Steiner, Andrew W

    2011-01-01

    The supernova remnant Cassiopeia A contains the youngest known neutron star which is also the first one for which real time cooling has ever been observed. In order to explain the rapid cooling of this neutron star, we first present the fundamental properties of neutron stars that control their thermal evolution with emphasis on the neutrino emission processes and neutron/proton superfluidity/superconductivity. Equipped with these results, we present a scenario in which the observed cooling of the neutron star in Cassiopeia A is interpreted as being due to the recent onset of neutron superfluidity in the core of the star. The manner in which the earlier occurrence of proton superconductivity determines the observed rapidity of this neutron star's cooling is highlighted. This is the first direct evidence that superfluidity and superconductivity occur at supranuclear densities within neutron stars.

  17. Non-destructive compositional analysis of sol-gel synthesized lithium titanate (Li2TiO3) by particle induced gamma-ray emission and instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Lithium titanate, one of the important tritium breeding materials in D-T based fusion reactor under ITER programme, was synthesized through sol-gel route. For chemical quality control of finished product, it was necessary to quantify the lithium and titanium contents. As this ceramic sample is difficult to dissolve, non-destructive analytical methods are preferred for compositional analysis. In the present work, two non-destructive nuclear analytical methods namely particle induced gamma-ray emission (PIGE) using proton beam and instrumental neutron activation analysis (INAA) using reactor neutrons were standardized for the determination of lithium and titanium concentrations, respectively and applied to eleven samples of lithium titanate. To the best of our knowledge, Li quantification in lithium titanate sample is being reported for the first time using PIGE. For quantifications of Li and Ti, 478 keV prompt gamma-ray from 7Li (p, p'γ) 7Li and 320 keV gamma-ray from 50Ti (n,γ) 51Ti were measured, respectively, by high resolution gamma-ray spectrometry. The PIGE and INAA methods were validated using several synthetic samples containing lithium and titanium, respectively. Concentrations of lithium and titanium and Li/Ti mole ratios were evaluated and compared with the stoichiometric concentration of Li2TiO3. (author)

  18. A derivation of bulk-motion insensitive implosion metrics inferred from neutron and high-energy x-ray emission in a series of high yield implosions on the NIF

    Science.gov (United States)

    Springer, P. T.; Macphee, A. G.; Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Cerjan, C. J.; Dewald, E. L.; Dittrich, T. R.; Doeppner, T.; Edgell, D. H.; Edwards, M. J.; Gaffney, J.; Grim, G. P.; Haan, S.; Hammer, J. H.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O.; Kritcher, A. L.; Le Pape, S.; Ma, T.; Milovich, J.; Munro, D. H.; Pak, A.; Park, H. S.

    2015-11-01

    A suite of nuclear and x-ray data is used to deduce key implosion performance metrics at stagnation including the hotspot pressure, energy, and the role of alpha heating on producing the observed yield. Key to this analysis is a determination of the burn-averaged temperature of the hot plasma so that the nuclear reactivity and yield can then be used to deduce the plasma density and pressure. In this presentation we examine the systematics of both neutron and high-energy x-ray emission (22 keV x-ray monochromator) from a series of high yield implosions on the NIF. The advantage of incorporating high energy x-rays into the analysis is their insignificant attenuation and insensitivity to bulk flows, thus providing insight as to whether these effects complicate the interpretation of the nuclear data, and that a precipitous drop in their production is expected as the thermal temperature is reduced. A dynamic model for hotspot assembly is developed that incorporates thermal conduction, radiative losses, and alpha heating, which simultaneously matches both neutron and x-ray data with nearly identical nuclear and x-ray derived thermal temperatures. Work performed under the auspices of the USDoE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  19. Neutron radiography

    International Nuclear Information System (INIS)

    This introduction is addressed to an audience active in diverse forms of neutron source applications but not directly familiar with neutron radiography. Neutron radiography is, of course, similar to, and complementary to, radiography using x-rays. However, neutrons, being sensitive to the nuclear properties of materials, provide information fundamentally different from x-rays. For example, neutrons can penetrate many dense metals such as uranium, lead, bismuth or steel, and can reveal details of internal hydrogenous components: explosives, lubricants and gaskets. For nuclear fuel inspection neutron radiography offers the ability to penetrate dense uranium-238 and contrast the isotopes U-235 or Pu-239 and also offers the ability to discriminate against unwanted interference from gamma radiation. In addition to advantages in industrial applications, there are special situations in fields such as medical diagnostics, dentistry, agriculture and forensic science. Comprehensive accounts of applications in the field can be found in the proceedings of the world conferences on neutron radiography: USA (1981), FRANCE (1986). A third conference in this series is scheduled for May 1989 in Japan

  20. Velocity-space sensitivity of neutron spectrometry measurements

    DEFF Research Database (Denmark)

    Jacobsen, Asger Schou; Salewski, Mirko; Eriksson, J.;

    2015-01-01

    Neutron emission spectrometry (NES) measures the energies of neutrons produced in fusion reactions. Here we present velocity-space weight functions for NES and neutron yield measurements. Weight functions show the sensitivity as well as the accessible regions in velocity space for a given range...

  1. Neutron radiography

    International Nuclear Information System (INIS)

    The digital processing of the neutron radiography images gives the possibility for data quantification. In this case an exact relation between the measured neutron attenuation and the real macroscopic attenuation coefficient for every point of the sample is required. The assumption that the attenuation of the neutron beam through the sample is exponential is valid only in an ideal case where a monochromatic beam, non scattering sample and non background contribution are assumed. In the real case these conditions are not fulfilled and in dependence on the sample material we have more or less deviation from the exponential attenuation law. Because of the high scattering cross-sections of hydrogen (σs=80.26 barn) for thermal neutrons, the problem with the scattered neutrons at quantitative radiography investigations of hydrogenous materials (as PE, Oil, H2O, etc) is not trivial. For these strong scattering materials the neutron beam attenuation is no longer exponential and a dependence of the macroscopic attenuation coefficient on the material thickness and on the distance between the sample and the detector appears. When quantitative radiography (2 D) or tomography investigations (3 D) are performed, some image correction procedures for a description of the scattering effect are required. This thesis presents a method that can be used to enhance the neutron radiography image for objects with high scattering materials like hydrogen, carbon and other light materials. This method uses the Monte Carlo code, MCNP5, to simulate the neutron radiography process and get the flux distribution for each pixel of the image and determine the scattered neutrons distribution that causes the image blur and then subtract it from the initial image to improve its quality.

  2. Characterization of the volcanic eruption emissions using neutron activation analysis; Caracterizacion de las emisiones de una erupcion volcanica mediante analisis por activacion neutronica

    Energy Technology Data Exchange (ETDEWEB)

    Pla, Rita R. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Radioquimica, Tecnicas Analiticas Nucleares; Tafuri, Victoria V. [Servicio Meteorologico Nacional, Buenos Aires (Argentina). Centro de Contaminacion del Aire

    1997-10-01

    Characterization of the volcanic particulate material has been performed by analyzing aerosols and ashes with instrumental neutron activation analysis. Crustal enrichment factors were calculated using the elemental concentration and clustering techniques, and multivariate analysis were done. The analytical and data treatment methodologies allowed the sample differentiation from their geographical origin viewpoint, based on their chemical composition patterns, which are related to the deposit formation processes, which consist of direct deposition from the volcanic cloud, and removal by wind action after the end of the eruption, and and finally the deposition. (author). 8 refs., 5 figs.

  3. Neutron scattering

    International Nuclear Information System (INIS)

    This report contains the text of 16 lectures given at the Summer School and the report on a panel discussion entitled ''the relative merits and complementarities of x-rays, synchrotron radiation, steady- and pulsed neutron sources''. figs., tabs., refs

  4. Theory of neutron star magnetospheres

    CERN Document Server

    Curtis Michel, F

    1990-01-01

    An incomparable reference for astrophysicists studying pulsars and other kinds of neutron stars, "Theory of Neutron Star Magnetospheres" sums up two decades of astrophysical research. It provides in one volume the most important findings to date on this topic, essential to astrophysicists faced with a huge and widely scattered literature. F. Curtis Michel, who was among the first theorists to propose a neutron star model for radio pulsars, analyzes competing models of pulsars, radio emission models, winds and jets from pulsars, pulsating X-ray sources, gamma-ray burst sources, and other neutron-star driven phenomena. Although the book places primary emphasis on theoretical essentials, it also provides a considerable introduction to the observational data and its organization. Michel emphasizes the problems and uncertainties that have arisen in the research as well as the considerable progress that has been made to date.

  5. β - γ and β-neutron- γ emission in mass A=137 Decay Chain Studied with the Modular Total Absorption Spectrometer (MTAS)

    Science.gov (United States)

    Rasco, Charles; Fijałkowska, Aleksandra; Karny, Marek; Rykaczewski, Krzysztof; Wolińska-Cichocka, Marzena; Grzywacz, Robert

    2013-10-01

    The Modular Total Absorption Spectrometer (MTAS) is a detector made up of 19 separate hexagon modules of NaI which results in over a ton of NaI in the MTAS detector. MTAS was designed to capture as much of the electromagnetic energy release in β-decays as possible. MTAS was constructed at the Holifield Radioactive Ion Beam Facility and measured over 20 decay products of 238U fission products in its inaugural measurement campaign in January 2012. The measurements were focused on nuclei identified as important for decay heat analysis of the nuclear fuel cycle. Silicon detectors placed at the center of MTAS to provide β triggers, make for extremely clean signals in MTAS. Preliminary results on the average electromagnetic energy release in the β decay of 137Xe and 137I isotopes will be presented. These isotopes are among the priority 1 cases listed by the NEA. The 137I also has a beta -neutron decay branch that is detected in MTAS. Neutron detection in a large NaI detector will also be discussed. This work was supported by the US DOE by award no. DE-FG02-96ER40978 and by US DOE, Office of Nuclear Physics.

  6. An evaluation of the environmental implications of petroleum refinery emissions by multielemental neutron activation analysis of rumen fluid ash of buffaloes

    International Nuclear Information System (INIS)

    In order to study environmental pollution in and around a petroleum refinery complex, a multielemental instrumental neutron activation analysis (INAA) method was used to assay concentrations of As, Ba, Br, Cl, Co, Cr, Cs, Cu, Fe, Hg, La, Mn, Mo, K, Na, P, Sc, Rb, Se, Sr, W and Zn in the rumen fluid ash sample of buffaloes from the vicinity of the refinery. Corresponding samples from a control area 300 km away from the refinery were analysed. Standard Reference Materials, Bovine liver (SRM 1577a), Oyster tissue (SRM 1566a) and Animal bone (CRM H-5) were also analysed for quality control. Samples were irradiated with thermal neutrons at 1012-1013n cm-2 s-1 and counted by high-resolution γ spectrometry. Mean elemental concentrations of As, Ba, Br, Cr, Hg and Fe were found to be enhanced, whereas those of Na, K, Cl, Cu, Mn and P were depleted in samples from the vicinity of the refinery complex compared to controls. The environmental implications of anomalous elemental concentrations are discussed. (Author)

  7. Li2Se as a Neutron Scintillator

    International Nuclear Information System (INIS)

    We show that Li2Se:Te is a potential neutron scintillator material based on density functional calculations. Li2Se exhibits a number of properties favorable for efficient neutron detection, such as a high Li concentration for neutron absorption, a small effective atomic mass and a low density for reduced sensitivity to background gamma rays, and a small band gap for a high light yield. Our calculations show that Te doping should lead to the formation of deep acceptor complex VLi-TeSe, which can facilitate efficient light emission, similar to the emission activation in Te doped ZnSe

  8. Piezonuclear neutrons from fracturing of inert solids

    CERN Document Server

    Cardone, F; Lacidogna, G

    2009-01-01

    Neutron emission measurements by means of helium-3 neutron detectors were performed on solid test specimens during crushing failure. The materials used were marble and granite, selected in that they present a different behaviour in compression failure (i.e., a different brittleness index) and a different iron content. All the test specimens were of the same size and shape. Neutron emissions from the granite test specimens were found to be of about one order of magnitude higher than the natural background level at the time of failure.

  9. Gamma/neutron competition above the neutron separation energy in delayed neutron emitters

    International Nuclear Information System (INIS)

    To study the β-decay properties of some well known delayed neutron emitters an experiment was performed in 2009 at the IGISOL facility (University of Jyvaeskylae in Finland) using Total Absorption γ-ray Spectroscopy (TAGS) technique. The aim of these measurements is to obtain the full β-strength distribution below the neutron separation energy (Sn) and above the γ/neutron competition. This piece of information is a key parameter in nuclear technology applications as well as in nuclear astrophysics and nuclear structure. Preliminary results of the analysis show a significant γ-branching ratio above Sn and this surprising result is in contradiction with the general assumption of neutron emission domination above Sn

  10. Neutronic design of the ITER radial neutron camera

    Energy Technology Data Exchange (ETDEWEB)

    Petrizzi, L. [Associazione EURATOM-ENEA sulla Fusione, ENEA Centro Ricerche, C.P. 65, 00044 Frascati, Rome (Italy)], E-mail: petrizzi@frascati.enea.it; Barnsley, R. [EFDA CSU-Garching (Germany); Bertalot, L.; Esposito, B. [Associazione EURATOM-ENEA sulla Fusione, ENEA Centro Ricerche, C.P. 65, 00044 Frascati, Rome (Italy); Haskell, H. [ITER International Team, Garching (Germany); Mainardi, E.; Marocco, D.; Podda, S. [Associazione EURATOM-ENEA sulla Fusione, ENEA Centro Ricerche, C.P. 65, 00044 Frascati, Rome (Italy); Walker, C. [ITER International Team, Garching (Germany); Villari, S. [Associazione EURATOM-ENEA sulla Fusione, ENEA Centro Ricerche, C.P. 65, 00044 Frascati, Rome (Italy)

    2007-10-15

    This paper summarizes the work, performed in the frame of various EFDA contracts during 2004-2005, on the design review and upgrade of the ITER radial neutron camera (RNC). The RNC, which should provide information on the spatial distribution and energy spectrum of the neutron emission, consists of an ex-vessel system (fan-like collimator with 12 x 3 lines of sights) and an in-vessel system with further 9 lines for a full coverage of the plasma. A Monte Carlo code (MCNP) has been used for the neutronic calculations. The basic ITER model has been developed from the CATIA drawings to include the RNC with all details relevant for the neutronic analysis. In the model the collimator diameters have been set to 2 and 4 cm, respectively, for the ex-vessel and in-vessel systems. A detailed space dependent fusion neutron source (DD and DT phases in various plasma scenarios) has been used with a consistent ion temperature radial profile. A special variance reduction treatment has been developed so that neutrons reach the far regions in the high collimated neutron beam and score with a satisfying statistical error. Neutron and photon fluxes and spectra have been calculated. Approximately, one neutron out of 10{sup 11} emitted in all the plasma reaches a single ex-vessel detector. Therefore, for an emission rate of 1.8 x 10{sup 20} n/s (corresponding to 500 MW fusion power) the flux on the detectors is in the range (1-5) x 10{sup 8} n/(cm{sup 2} s) depending on the poloidal orientation. The fraction of scattered neutrons (>1 MeV) is lower than few % of the total. A measurement simulation software tool (MSST) performing asymmetric Abel inversion of simulated measured neutron signals has also been developed for line of sight and design optimization. Combining information from MCNP calculations and MSST, it has been possible to evaluate the performance of the RNC, check whether the present design of the RNC meets the measurement requirements and optimize the RNC design.

  11. Investigation of the triton emission asymmetry in the sup 6 Li(n, alpha) sup 3 H reaction with polarized thermal neutrons

    CERN Document Server

    Gledenov, Yu M; Petukhov, A K; Sedyshev, P V; Shulgina, E V; Soldner, T; Vesna, V A; Zimmer, O

    2002-01-01

    An experiment was carried out at the high-intensity polarized cold neutron beam of the PF1B instrument of the ILL reactor, Grenoble, France. As a detector, the 48-section ionization chamber with the sup 6 LiF targets was used. An integral (current) method of the event detection with compensation of the reactor power fluctuation was applied. Special measurement technique was used for minimization and estimation of the possible false effect contribution. A value of the P-odd (sigma sub n , P sub t) correlation has been obtained: alpha sub P sub N = -(7.1 +- 3.9) centre dot 10 sup - sup 8. On the basis of the cluster model, the most accurate at present day estimation of the weak neutral current constant has been given: f subpi <= 1.2 centre dot 10 sup - sup 7.

  12. The Radio Emission, X-ray Emission, and Hydrodynamics of G328.4+0.2: A Comprehensive Analysis of a Luminous Pulsar Wind Nebula, its Neutron Star, and the Progenitor Supernova Explosion

    CERN Document Server

    Gelfand, Joseph D; Slane, Patrick O; Patnaude, Daniel J; Hughes, John P; Camilo, Fernando

    2007-01-01

    We present new observational results obtained for the Galactic non-thermal radio source G328.4+0.2 to determine both if this source is a pulsar wind nebula or supernova remnant, and in either case, the physical properties of this source. Using X-ray data obtained by XMM, we confirm that the X-ray emission from this source is heavily absorbed and has a spectrum best fit by a power law model of photon index=2 with no evidence for a thermal component, the X-ray emission from G328.4+0.2 comes from a region significantly smaller than the radio emission, and that the X-ray and radio emission are significantly offset from each other. We also present the results of a new high resolution (7 arcseconds) 1.4 GHz image of G328.4+0.2 obtained using the Australia Telescope Compact Array, and a deep search for radio pulsations using the Parkes Radio Telescope. We find that the radio emission has a flat spectrum, though some areas along the eastern edge of G328.4+0.2 have a steeper radio spectral index of ~-0.3. Additionally...

  13. Tutorial on Neutron Physics in Dosimetry

    CERN Document Server

    Pomp, S

    2009-01-01

    Almost since the time of the discovery of the neutron more than 70 years ago, efforts have been made to understand the effects of neutron radiation on tissue and, eventually, to use neutrons for cancer treatment. In contrast to charged particle or photon radiations which directly lead to release of electrons, neutrons interact with the nucleus and induce emission of several different types of charged particles such as protons, alpha particles or heavier ions. Therefore, a fundamental understanding of the neutron-nucleus interaction is necessary for dose calculations and treatment planning with the needed accuracy. We will discuss the concepts of dose and kerma, neutron-nucleus interactions and have a brief look at nuclear data needs and experimental facilities and set-ups where such data are measured.

  14. Neutron Repulsion

    CERN Document Server

    Manuel, Oliver K

    2011-01-01

    Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding...

  15. neutron radiography

    International Nuclear Information System (INIS)

    Neutron radiography (or radiology) is a diverse filed that uses neutrons of various energies, subthermal, thermal, epithermal or fast in either steady state or pulsed mode to examine objects for industrial, medical, or other purposes, both microscopic and macroscopic. The applications include engineering design, biological studies, nondestructive inspection and materials evaluation. In the past decade, over 100 different centers in some 30 countries have published reports of pioneering activities using reactors, accelerators and isotopic neutron sources. While film transparency and electronic video are most common imaging methods for static or in motion objects respectively, there are other important data gathering techniques, including track etch, digital gauging and computed tomography. A survey of the world-wide progress shows the field to be gaining steadily in its diversity, its sophistication and its importance. (author)

  16. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  17. Major and trace elemental analysis in milk powder by inductively coupled plasma-optical emission spectrometry (ICP-OES) and instrumental neutron activation analysis(INAA)

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Major and trace element in seven different kinds of milk powder were studied. The concentration of 24 elements were determined byICP-OES method, from these elements 9 elements determined by INAA. The determination of trace element contents of foodstuffs, especiallymilk as daily drink for all peoples age which being a complex food has great importance. The elemental analysis of milk is important both as anindicator of environmental contamination and because milk is a significant pathway for toxic metal intake and a source of essential nutrients forhumans. The major elements are Ca, K, Mg, Na, P and S. While trace element are B, Ba, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Sb, Se,Sn, Sr, V, W and Zn.ICP-OES technique is shown to be a powerful tool for trace determinations in powder samples. This is shown by its use for analysis of aseries of the milk powders mentioned and comparative results of other direct technique such as instrumental neutron activation analysis.Analysis of both standard reference material A-11 milk powder and NBS Orchard leaves for quality accurance had been completed, andused for a relative method calculate. The importance of the major and trace elements to human health was discussed.

  18. Conceptual design of a camera system for neutron imaging in low fusion power tokamaks

    International Nuclear Information System (INIS)

    The basic principles for designing a camera system for neutron imaging in low fusion power tokamaks are illustrated for the case of the HL-2A tokamak device. HL-2A has an approximately circular cross section, with total neutron yields of about 1012 n/s under 1 MW neutral beam injection (NBI) heating. The accuracy in determining the width of the neutron emission profile and the plasma vertical position are chosen as relevant parameters for design optimization. Typical neutron emission profiles and neutron energy spectra are calculated by Monte Carlo method. A reference design is assumed, for which the direct and scattered neutron fluences are assessed and the neutron count profile of the neutron camera is obtained. Three other designs are presented for comparison. The reference design is found to have the best performance for assessing the width of peaked to broadened neutron emission profiles. It also performs well for the assessment of the vertical position

  19. Study of the RP-10 reactor neutron beam applied to the neutron radiography

    International Nuclear Information System (INIS)

    We have studied the RP-10 reactor radial neutron beam No. 3, which is used for neutron radiographies, by comparing radiograph's with and without the inner duct, and neutron flux determination with in flakes along the external duct, being the presence of photons creating signals at comparable levels of neutron effects, which reduce the quality of the analysis, values around 106 and 104 n/cm2s for thermal and epithermal flux were obtained respectively. It is recommended evaluate the design of the internal duct which presents strong photon emission. (authors).

  20. Methods for absorbing neutrons

    Science.gov (United States)

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  1. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  2. Determination of hafnium at the 10−4% level (relative to zirconium content) using neutron activation analysis, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •We worked out ICP-MS method of Hf determination in Zr and Zr compounds. •We used NAA method as reference one. •We obtained pure zirconium matrix by ion exchange (Diphonix® resin). •These permit to determine ≥1 × 10−4% Hf in Zr sample by ICP MS with good precision and accuracy. -- Abstract: Hafnium at the very low level of 1–8 ppm (in relation to zirconium) was determined in zirconium sulfate solutions (originating from investigations of the separation of ca. 44 ppm Hf from zirconium by means of the ion exchange method) by using three independent methods: inductively coupled plasma mass spectrometry (ICP MS), neutron activation analysis (NAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results of NAA and ICP MS determinations were consistent with each other across the entire investigated range (the RSD of both methods did not exceed 38%). The results of ICP-AES determination were more diverse, particularly at less than 5 ppm Hf (RSD was significantly higher: 29–253%). The ion exchange method exploiting Diphonix® resin proved sufficient efficiency in Zr–Hf separation when the initial concentration ratio of the elements ([Zr]0/[Hf]0) ranged from 1200 to ca. 143,000

  3. Peninsulas of the neutron stability of nuclei in the vicinity of neutron magic numbers

    International Nuclear Information System (INIS)

    On the basis of the Hartree-Fock method as implemented with Skyrme forces (Ska, SkM*, Sly4, and SkI2) and with allowance for an axial deformation and nucleon pairing in the Bardeen-Cooper-Schrieffer approximation, the properties of extremely neutron-rich even-even nuclei were calculated beyond the neutron drip line known earlier from theoretical calculations. It was shown that the chains of isotopes beyond the neutron drip line that contain N = 32, 58, 82, 126, and 184 neutrons form peninsulas of nuclei stable against the emission of one neutron and, in some cases, peninsulas of nuclei stable against the emission of two neutrons. The neutron- and proton-density distributions in nuclei forming stability peninsulas were found to be spherically symmetric. A mechanism via which the stability of nuclei might be restored beyond the neutron drip line was discussed. A comparison with the results of calculations by the Hartree-Fock-Bogolyubov method was performed for long chains of sulfur and gadolinium isotopes up to the neutron drip line.

  4. Neutron rich nuclei and neutron stars

    OpenAIRE

    Horowitz, C. J.

    2013-01-01

    The PREX experiment at Jefferson Laboratory measures the neutron radius of 208Pb with parity violating electron scattering in a way that is free from most strong interaction uncertainties. The 208Pb radius has important implications for neutron rich matter and the structure of neutron stars. We present first PREX results, describe future plans, and discuss a follow on measurement of the neutron radius of 48Ca. We review radio and X-ray observations of neutron star masses and radii. These cons...

  5. Cooling neutrons using non-dispersive magnetic excitations

    CERN Document Server

    Zimmer, Oliver

    2014-01-01

    A new method is proposed for cooling neutrons by inelastic magnetic scattering in weakly absorbing, cold paramagnetic systems. Kinetic neutron energy is removed in constant decrements determined by the Zeeman energy of paramagnetic atoms or ions in an external magnetic field, or by zero-field level splittings in magnetic molecules. Analytical solutions of the stationary neutron transport equation are given using inelastic neutron scattering cross sections derived in an appendix. They neglect any inelastic process except the paramagnetic scattering and hence still underestimate very-cold neutron densities. Molecular oxygen with its triplet ground state appears particularly promising, notably as a host in fully deuterated oxygen-clathrate hydrate, or more exotically, in dry oxygen-He4 van der Waals clusters. At a neutron temperature about 6 K, for which neutron conversion to ultra-cold neutrons by single-phonon emission in pure superfluid He4 works best, conversion rates due to paramagnetic scattering in the cl...

  6. Prompt neutron spectrum of the spontaneous fission of californium-252

    International Nuclear Information System (INIS)

    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 252Cf 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 252Cf neutron spectrum in the neutron energy range of less than 0.7 MeV compared to theoretical values is discussed. The mechanism of 252Cf neutron emission is also discussed on the basis of neutron yield angle measurements. 12 references

  7. Anomalous hydrodynamics kicks neutron stars

    Science.gov (United States)

    Kaminski, Matthias; Uhlemann, Christoph F.; Bleicher, Marcus; Schaffner-Bielich, Jürgen

    2016-09-01

    Observations show that, at the beginning of their existence, neutron stars are accelerated briskly to velocities of up to a thousand kilometers per second. We argue that this remarkable effect can be explained as a manifestation of quantum anomalies on astrophysical scales. To theoretically describe the early stage in the life of neutron stars we use hydrodynamics as a systematic effective-field-theory framework. Within this framework, anomalies of the Standard Model of particle physics as underlying microscopic theory imply the presence of a particular set of transport terms, whose form is completely fixed by theoretical consistency. The resulting chiral transport effects in proto-neutron stars enhance neutrino emission along the internal magnetic field, and the recoil can explain the order of magnitude of the observed kick velocities.

  8. Low energy neutron measurements aboard encounter missions

    Science.gov (United States)

    Vilmer, N.; Maksimovic, M.; Trottet, G.

    Neutrons in the MeV to GeV range are produced by interaction of flare accelerated ions with the solar atmosphere. Because of their lifetime, only high energy neutrons (> 100 MeV) have a high probability to be detected at earth's orbit. So far, around fifteen solar neutron events have been observed either by high energy detectors aboard spacecrafts at 1 AU or by ground based neutron monitors. Neutrons between 10 and 100 MeV have also been detected for a few events through their proton decay. Measurements of solar neutrons closer to the Sun aboard encounter missions will allow to probe for the first time the MeV neutrons which are produced by the nuclear reactions of energetic ions with thresholds around 1 MeV/nuc and will provide information on the accelerated ion spectrum in the energy range between ˜ 1 MeV and 100 MeV/nuc in complementarity with what can be deduced from γ -ray line emission. The close proximity of the Sun would allow to measure neutron events for many more flares opening a new field of solar physics. Combined with near in-situ ion measurements and γ -ray observations, neutrons will bring information on the link between interacting and escaping ions while getting rid of most of the transport effects.

  9. Inclusive deuteron-induced reactions and final neutron states

    CERN Document Server

    Potel, Gregory; Thompson, Ian J

    2015-01-01

    We present in this paper a formalism for deuteron-induced inclusive reactions. We disentangle direct elastic breakup contributions from other processes (which we generically call non-elastic breakup) implying a capture of the neutron both above and below the neutron emission threshold. The reaction is described as a two step process, namely the breakup of the deuteron followed by the propagation of the neutron-target system driven by an optical potential. The final state interaction between the neutron and the target can eventually form an excited compound nucleus. Within this context, the direct neutron transfer to a sharp bound state is a limiting case of the present formalism.

  10. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    Neutron (and X-ray) reflectometry constitute complementary interfacially sensitive techniques that open access to studying the structure within thin films of both soft and hard condensed matter. Film thickness starts oxide surfaces on bulk substrates, proceeding to (pauci-)molecular layers and up...... to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...... of new material. Understanding self-assembly of 2D-3D nanostructures at surfaces and the related interfaces in layered films is a precondition for the development of tailored tools with distributed functions, like new clothes (self-cleaning surfaces combined with mechanical resistance, low permeability...

  11. Neutron scattering. Lectures

    International Nuclear Information System (INIS)

    The following topics are dealt with: Neutron scattering in contemporary research, neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  12. Neutron scattering. Lectures

    International Nuclear Information System (INIS)

    The following topics are dealt with: Neutron sources, symmetry of crystals, nanostructures investigated by small-angle neutron scattering, structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic neutron scattering, strongly correlated electrons, polymer dynamics, applications of neutron scattering. (HSI)

  13. Neutron dosimetry

    International Nuclear Information System (INIS)

    It is the object of the present invention to provide a method of measuring neutron radiation which eliminates the use of powders as dosimeter target materials and reduces the requirement for repetitive weighing of dosimeters, for expensive radioisotopes as dosimeter target material, and for dosimeter housings (in many cases). The invention described is a method of measuring neutron radiation within a nuclear reactor consisting of placing one or more extruded sintered oxide wires comprising a dosimeter target oxide within the reactor and measuring the radioactivity induced in the wires by neutron radiation. These oxide wires consist of a dilution containing at least 0.1% by weight of the dosimeter target oxide in a diluent oxide. The diluent oxide is selected from a group consisting of Al2O3 and BeO. Almost any metal oxide may be used as a target oxide. The wires may be encapsulated within a co-extruded housing. These mixed oxide wires have been found to be sufficiently uniform for quantitative analyses. (JTA)

  14. A gated liquid-scintillator-based neutron detector for fast-ignitor experiments and down-scattered neutron measurements

    International Nuclear Information System (INIS)

    The detection of neutrons in fast-ignitor experiments or down-scattered neutrons in inertial fusion experiments is very challenging since it requires the neutron detection system to recover within 10-100 ns from a high background orders of magnitude stronger than the signal of interest. The background is either the hard x-ray emission from short-pulse laser target interactions for the fast-ignitor experiments or the primary neutron signal for the down-scattered neutrons. A liquid-scintillator detector has been developed using a gated photomultiplier that suppresses the background signal and eliminates the afterglow present in conventional plastic scintillators.

  15. β-Decay of Light Neutron-Rich Nuclei

    Institute of Scientific and Technical Information of China (English)

    何超; 华辉; 李湘庆; 汪波

    2012-01-01

    The β-decays of neutron-rich carbon, nitrogen and fluorine isotopes have been systematically studied using the OXBASH shell Model. In the psd, spsd and spsdpf model space, we use the WBP interaction to calculate the half-lives and neutron emission probabilities of neutron- rich carbon and nitrogen isotopes, respectively. With the USD (W) and CW interactions, we calculate the half-lives and neutron emission probabilities of neutron-rich fluorine isotope in the sd model space, respectively. The calculated half-lives and neutron emission probabilities reproduce recent experimental data very well. It seems to show that the particles of the neutron-rich carbon and nitrogen isotopes are mainly excited in the spsd space. The β-decay of 21N to the neutron bound states in 210 is mostly the first forbidden transition which makes the neutron emission probability increase. The theoretical calculation of β-decay of 25F to 25Ne with CW interaction shows that CW interaction is better than USD interaction.

  16. A ctivation measurement of neutron distribution in intermediate energy heavy ion target area

    Institute of Scientific and Technical Information of China (English)

    LiGui-Sheng; WangJing; 等

    1997-01-01

    The distribution of neutrons produced by the reaction of 50MeV/u 12C-ion on a thick Cu target are studied.The neutrons are measured with threshold activation detectors.Al.F,C,Al and In activation samples were used to measure neutrons with energy greater than 7,11,20,50MeV and thermal neutrons,respectively,The fluence rate,energy and angular distributions of neutrons,total neutron yield of 12C-ion and the emission rate in the forward direction of neutrons over 11 and 20MeV were obtained.

  17. Rapidly rotating neutron star progenitors

    Science.gov (United States)

    Postnov, K. A.; Kuranov, A. G.; Kolesnikov, D. A.; Popov, S. B.; Porayko, N. K.

    2016-08-01

    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In the present paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, τc. The validity of this approach is checked by direct MESA calculations of the evolution of a rotating 15 M⊙ star. From comparison of the calculated spin distribution of young neutron stars with the observed one, reported by Popov and Turolla, we infer the value τc ≃ 5 × 105 years. We show that merging of stellar cores in common envelopes can lead to collapses with dynamically unstable proto-neutron stars, with their formation rate being ˜0.1 - 1% of the total core collapses, depending on the common envelope efficiency.

  18. Used Fuel Cask Identification through Neutron Profile

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, Eric Benton [Los Alamos National Laboratory

    2015-11-20

    Currently, most spent fuel is stored near reactors. An interim consolidated fuel storage facility would receive fuel from multiple sites and store it in casks on site for decades. For successful operation of such a facility there is need for a way to restore continuity of knowledge if lost as well as a method that will indicate state of fuel inside the cask. Used nuclear fuel is identifiable by its radiation emission, both gamma and neutron. Neutron emission from fission products, multiplication from remaining fissile material, and the unique distribution of both in each cask produce a unique neutron signature. If two signatures taken at different times do not match, either changes within the fuel content or misidentification of a cask occurred. It was found that identification of cask loadings works well through the profile of emitted neutrons in simulated real casks. Even casks with similar overall neutron emission or average counts around the circumference can be distinguished from each other by analyzing the profile. In conclusion, (1) identification of unaltered casks through neutron signature profile is viable; (2) collecting the profile provides insight to the condition and intactness of the fuel stored inside the cask; and (3) the signature profile is stable over time.

  19. Spallation Neutron Source (SNS)

    Data.gov (United States)

    Federal Laboratory Consortium — The SNS at Oak Ridge National Laboratory is a next-generation spallation neutron source for neutron scattering that is currently the most powerful neutron source in...

  20. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress

    Science.gov (United States)

    Schooneveld, E. M.; Pietropaolo, A.; Andreani, C.; Perelli Cippo, E.; Rhodes, N. J.; Senesi, R.; Tardocchi, M.; Gorini, G.

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources.

  1. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress.

    Science.gov (United States)

    Schooneveld, E M; Pietropaolo, A; Andreani, C; Perelli Cippo, E; Rhodes, N J; Senesi, R; Tardocchi, M; Gorini, G

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources. PMID:27502571

  2. Neutron scattering. Lectures

    International Nuclear Information System (INIS)

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  3. REFRACTIVE NEUTRON LENS

    OpenAIRE

    Petrov, P. V.; Kolchevsky, N.N.

    2013-01-01

    Compound concave refractive lenses are used for focusing neutron beam. Investigations of spectral and focusing properties of a refractive neutron lens are presented. Resolution of the imaging system on the base of refractive neutron lenses depends on material properties and parameters of neutron source. Model of refractive neutron lens are proposed. Results of calculation diffraction resolution and focal depth of refractive neutron lens are discussed.

  4. Neutron Capture Nucleosynthesis

    OpenAIRE

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these resu...

  5. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  6. Neutron Therapy Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Neutron Therapy Facility provides a moderate intensity, broad energy spectrum neutron beam that can be used for short term irradiations for radiobiology (cells)...

  7. Prompt neutron multiplicities for the transplutonium nuclides

    International Nuclear Information System (INIS)

    The direct determination of the average prompt neutron emission values is reviewed, and a method of comparing different sites of neutron emission multiplicity distribution values is described. Measured and recommended values are tabulated for these nuclides: 241Am, 242Am, 242Cm, 243Cm, 244Cm, 246Cm, 247Cm, 248Cm, 250Cm, 245Cm, 249Bk, 246Cf, 249Cf, 250Cf, 252Cf, 254Cf, 251Cf, 253Es, 254Es, 244Fm, 246Fm, 255Fm, 252No, 254Fm, 256Fm, 257Fm. 59 refs., 24 tabs

  8. The Effects of δ Meson on the Neutron Star Cooling

    Institute of Scientific and Technical Information of China (English)

    许妍; 刘广洲; 吴姚睿; 朱明枫; 喻孜; 王红岩; 赵恩广

    2012-01-01

    In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.

  9. Neutron reflectometry on highly absorbing films and its application to (B4C)-B-10-based neutron detectors

    OpenAIRE

    Piscitelli, F.; Khaplanov, A.; Devishvili, A.; Schmidt, Susann; Höglund, Carina; Birch, Jens; Dennison, A.J.C.; Gutfreund, P.; Hall-Wilton, R.; van Esch, P.

    2016-01-01

    Neutron reflectometry is a powerful tool used for studies of surfaces and interfaces. In general the absorption in the typical studied materials can be neglected and this technique is limited to the measurement of the reflectivity only. In the case of strongly absorbing nuclei the number of neutrons is not conserved and the absorption can be directly measured by using the neutron-induced fluorescence technique which exploits the prompt particle emission of absorbing isotopes. This technique i...

  10. Conceptual design of the BRIKEN detector: A hybrid neutron-gamma detection system for nuclear physics at the RIB facility of RIKEN

    CERN Document Server

    Tarifeño-Saldivia, A; Domingo-Pardo, C; Calviño, F; Cortes, G; Phong, V H; Riego, A

    2016-01-01

    BRIKEN is a complex detection system to be installed at the RIB-facility of the RIKEN Nishina Center. It is aimed at the detection of heavy-ion implants, $\\beta$-particles, $\\gamma$-rays and $\\beta$-delayed neutrons. The whole detection setup involves the Advanced Implantation Detection Array (AIDA), two HPGe Clover detectors and a large set of 166 counters of 3He embedded in a high-density polyethylene matrix. This article reports on a novel methodology developed for the conceptual design and optimisation of the 3He-tubes array, aiming at the best possible performance in terms of neutron detection. The algorithm is based on a geometric representation of two selected parameters of merit, namely, average neutron detection efficiency and efficiency flatness, as a function of a reduced number of geometric variables. The response of the detection system itself, for each configuration, is obtained from a systematic MC-simulation implemented realistically in Geant4. This approach has been found to be particularly u...

  11. In-situ soil carbon analysis using inelastic neutron scattering

    Science.gov (United States)

    In situ soil carbon analysis using inelastic neutron scattering (INS) is based on the emission of 4.43 MeV gamma rays from carbon nuclei excited by fast neutrons. This in-situ method has excellent potential for easily measuring soil carbon since it does not require soil core sampling and processing ...

  12. Evaluation of secondary and prompt fission neutron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Porodzinskij, Yu.V.; Sukhovitskij, E.Sh. [Radiation Physics and Chemistry Problems Inst., Minsk-Sosny (Belarus)

    1997-03-01

    A simple model allowing to split neutron emission spectra into reaction partials is suggested. Predicted spectra of (n,n`{gamma}), (n,n`f), etc appear to be much harder than usually evaluated. (author)

  13. Neutron source for Neutron Capture Synovectomy

    International Nuclear Information System (INIS)

    Monte Carlo calculations were performed to obtain a thermal neutron field from a 239PuBe neutron source inside a cylindrical heterogeneous moderators for Neutron Capture Synovectomy. Studied moderators were light water and heavy water, graphite and heavy water, lucite and polyethylene and heavy water. The neutron spectrum of polyethylene and heavy water moderator was used to determine neutron spectra inside a knee model. In this model the elemental composition of synovium and synovial liquid was assumed like blood. Kerma factors for synovium and synovial liquid were calculated to compare with water Kerma factors, in this calculations the synovium was loaded with two different concentrations of Boron

  14. Neutron dosimetry - A review

    International Nuclear Information System (INIS)

    This review summarizes information on the following subjects: (1) physical processes of importance in neutron dosimetry; (2) biological effects of neutrons; (3) neutron sources; and (4) instruments and methods used in neutron dosimetry. Also, possible improvements in dosimetry instrumentation are outlined and discussed. (author)

  15. Borner Ball Neutron Detector

    Science.gov (United States)

    2002-01-01

    The Bonner Ball Neutron Detector measures neutron radiation. Neutrons are uncharged atomic particles that have the ability to penetrate living tissues, harming human beings in space. The Bonner Ball Neutron Detector is one of three radiation experiments during Expedition Two. The others are the Phantom Torso and Dosimetric Mapping.

  16. Superfluid neutron stars

    OpenAIRE

    Langlois, David

    2001-01-01

    Neutron stars are believed to contain (neutron and proton) superfluids. I will give a summary of a macroscopic description of the interior of neutron stars, in a formulation which is general relativistic. I will also present recent results on the oscillations of neutron stars, with superfluidity explicitly taken into account, which leads in particular to the existence of a new class of modes.

  17. Neutron scattering. Lectures

    International Nuclear Information System (INIS)

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  18. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  19. Neutrostriction in Neutron stars

    OpenAIRE

    Ignatovich, V. K.

    2003-01-01

    It is demonstrated that not only gravity, but also neutrostriction forces due to optical potential created by coherent elastic neutron-neutron scattering can hold a neutron star together. The latter forces can be stronger than gravitational ones. The effect of these forces on mass, radius and structure of the neutron star is estimated.

  20. Neutrons produced by 75MeV/u 12C—ion on thick targets

    Institute of Scientific and Technical Information of China (English)

    LiGisheng; ZHANGTianmei; 等

    1999-01-01

    Fluence rates and angular distributions of the neutron emitted by 75MeV/u 12C-ion bombardment on thick Be and Au targets have been measured by means of the threshold detector activation method.Based on that,the neutron yields,emission rates in the forward direction and neutron dose equivalent rate distributions were deduced.

  1. Numerical estimates of multiple reaction corrections in neutron cross-section measurements

    International Nuclear Information System (INIS)

    A method to evaluate the effect of secondary neutrons in 14-15 MeV neutron cross-section measurements is presented. The emission spectra of secondary neutrons are calculated by means of the preequilibrium and statistical models. An expression for the collision probability in a homogenous body has been utilized in the calculations. (author)

  2. Neutron Capture Nucleosynthesis

    CERN Document Server

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these results most of the nuclei can formed at medium neutron capture density environment e.g. in some kind of AGB stars. Besides these observations our model is capable to use educational purpose.

  3. Fast neutron spectrometry using thick threshold detectors

    Directory of Open Access Journals (Sweden)

    Idiri Z.

    2012-04-01

    Full Text Available This paper discusses the use of thick threshold activation detectors for the characterization of low intensity neutron fields. This technique has been applied to the determination of the spectral emission of a low activity (37 GBq Am-Be source. The reaction rates induced by the neutrons emitted by this source in different thick metallic targets (Al, Si, Fe, In have been measured in the following reactions: 27Al(n,p27Mg, 27Al(n,α24Na, 28Si(n,p28Al, 56Fe(n,p56Mn, 115In(n, n′115mIn and 115In(n, γ116mIn. Each measured reaction rate corresponding to a threshold detector response depends on the spectral emission of the source via a correcting factor. This factor, which takes into account the source detector geometry, the neutron attenuation and diffusion by the detectors, has been determined by Monte Carlo simulation using MCNP5 code. The spectral emission of the neutron source has been generated from the response matrix of the threshold detectors by using different neutron spectrum unfolding methods (Stayn'l, Gravel and Maxed. A fairly good agreement with the assumed ISO spectrum has been achieved.

  4. Piezonuclear neutrons from fracturing of inert solids

    Energy Technology Data Exchange (ETDEWEB)

    Cardone, F. [Istituto per lo Studio dei Materiali Nanostrutturati (ISMN-CNR), Via dei Taurini 19, 00185 Roma (Italy)] [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi ' Roma Tre' , Via della Vasca Navale, 84-00146 Roma (Italy); Carpinteri, A., E-mail: alberto.carpinteri@polito.i [Department of Structural Engineering and Geotechnics, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy); Lacidogna, G. [Department of Structural Engineering and Geotechnics, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy)

    2009-11-02

    Neutron emission measurements by means of helium-3 neutron detectors were performed on solid test specimens during crushing failure. The materials used were marble and granite, selected in that they present a different behaviour in compression failure (i.e., a different brittleness index) and a different iron content. All the test specimens were of the same size and shape. Neutron emissions from the granite test specimens were found to be of about one order of magnitude higher than the natural background level at the time of failure. These neutron emissions should be caused by nucleolysis or piezonuclear 'fissions' that occurred in the granite, but did not occur in the marble: Fe{sub 26}{sup 30}->2Al{sub 13}{sup 14}+2 neutrons. The present natural abundance of aluminum (7-8% in the Earth crust), which is less favoured than iron from a nuclear point of view, is possibly due to the above piezonuclear fission reaction. Despite the apparently low statistical relevance of the results presented in this Letter, it is useful to present them in order to give to other teams the possibility to repeat the experiment.

  5. Imaging with Scattered Neutrons

    CERN Document Server

    Ballhausen, H; Gähler, R; Trapp, M; Van Overberghe, A

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-resolution images by scattered neutron radiography and tomography are presented.

  6. High energy neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Wiegand, C.

    1948-04-27

    It is the purpose of this paper to describe a neutron detector suitable for monitoring a flux of neutrons whose energy is greater than about 50 MeV. Detection of the neutrons is accomplished by their ability to induce fission in heavy elements. Kelly and Wiegand studied the neutron fission of Bi, Pb, Ti, Hg, Au, and Pt at various neutron energies and the presently described counter is an application of this work.

  7. On the Rutherford-Santilli neutron model

    Energy Technology Data Exchange (ETDEWEB)

    Burande, Chandrakant S. [Vilasrao Deshmukh College of Engineering and Technology, Mouda, India-441104, Email: csburande@gmail.com (India)

    2015-03-10

    In 1920 H. Rutherford conjectured that the first particle synthesized in stars is neutron from a proton and an electron after which all known matter is progressively synthesized. However, Pauli objected Rutherford’s version of neutron synthesis because inability to represent spin 1/2 of the neutron. Using this objection E. Fermi proposed emission of massless particle, called “neutrino”. However, Santilli has dismissed the neutrino hypothesis following certain ambiguities such as positive binding energy required in synthesis of neutron. He found that celebrated Schrödinger’s equation of quantum physics is not suitable for obtaining positive binding energy for bound state at the dimension of 10{sup −13}cm. In order to remove these shortcomings, Santilli has developed isomathematics and then hadronic mechanics, which allowed the time invariant representation of Hamiltonian and non-Hamiltonian interactions as needed for the neutron synthesis (see for example: References cited at [1]).Thus the anomalies pertaining to the binding energy, the spin and the magnetic moment got resolved. He successfully calculated missing positive binding energy via isonormalization of the mass for electron when totally immersed within the hyper-dense medium inside the proton. Considering Rutherford’s compression of the isoelectron within the proton in the singlet coupling, he also identified the spin 1/2 for neutron and calculated the magnetic moment of the neutron. In order to verify his logical concept, he repeated the Don Carlo Borghi experiment of synthesis of the neutron from proton and electrons and verified that the said setup indeed produces neutron-type particles called “neutroids” which latter is absorbed by the activated detector substances that produces known nuclear reactions. He dismissed the neutrino hypothesis and replaced it with a longitudinal impulse originating from the ether as a universal substratum, named, “etherino”. He pointed out that all the

  8. Characterization of nuclear sources from neutron-neutron, proton-proton and neutron-proton correlation functions

    Energy Technology Data Exchange (ETDEWEB)

    Ghetti, R. E-mail: roberta.ghetti@kosufy.lu.se; Martensson, J.; Colonna, N.; Helgesson, J.; Jakobsson, B.; De Filippo, E.; Tagliente, G.; Lanzano, G.; Pantaleo, A.; Bellini, V.; Anzalone, A.; Carlen, L.; Cavallaro, S.; Celano, L.; D' Erasmo, G.; Di Santo, D.; Fiore, E.M.; Fokin, A.; Geraci, M.; Giustolisi, F.; Kuznetsov, A.; Mahboub, D.; Palazzolo, F.; Palomba, M.; Paticchio, V.; Riera, G.; Sperduto, M.L.; Sutera, C.; Urrata, M

    2000-07-03

    Two-neutron, two-proton and neutron-proton correlation functions have been measured simultaneously for the E/A=45 MeV {sup 58} Ni + {sup 27} Al reaction. Calculations from a statistical model have been compared to singles energy spectra as well as to total and gated correlation functions. This imposes very strong constraints on the model parameters. The use of directionally gated correlation functions helps to disentangle space and time information. Values of Gaussian radii, emission lifetimes, initial temperatures, source velocities and flow velocities are extracted. Correlation functions gated on total momentum of the nucleon pairs suggest that more energetic particles are emitted on a fast time scale ( < 100 fm / c ) and that the fraction of pre-equilibrium to equilibrium emission is larger for protons than for neutrons.

  9. Characterization of nuclear sources from neutron-neutron, proton-proton and neutron-proton correlation functions

    CERN Document Server

    Ghetti, R; Colonna, N; Helgesson, J; Jakobsson, B; De Filippo, E; Tagliente, G; Lanzanò, G; Pantaleo, A; Bellini, V; Anzalone, A; Carlén, L; Cavallaro, S; Celano, L; D'Erasmo, G; Di Santo, D; Fiore, E M; Fokin, A; Geraci, M; Giustolisi, F; Kuznetsov, A; Mahboub, D; Palazzolo, F; Palomba, M; Paticchio, V; Riera, G; Sperduto, M L; Sutera, C; Urrata, M

    2000-01-01

    Two-neutron, two-proton and neutron-proton correlation functions have been measured simultaneously for the E/A=45 MeV sup 5 sup 8 Ni + sup 2 sup 7 Al reaction. Calculations from a statistical model have been compared to singles energy spectra as well as to total and gated correlation functions. This imposes very strong constraints on the model parameters. The use of directionally gated correlation functions helps to disentangle space and time information. Values of Gaussian radii, emission lifetimes, initial temperatures, source velocities and flow velocities are extracted. Correlation functions gated on total momentum of the nucleon pairs suggest that more energetic particles are emitted on a fast time scale ( < 100 fm / c ) and that the fraction of pre-equilibrium to equilibrium emission is larger for protons than for neutrons.

  10. Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter

    CERN Document Server

    Page, Dany; Lattimer, James M; Steiner, Andrew W

    2010-01-01

    We propose that the recently observed cooling of the neutron star in Cassiopeia A is due to enhanced neutrino emission from the onset of the breaking and formation of neutron Cooper pairs in the 3P2 channel. To account for the observed cooling rate, which is significantly faster than that expected from the modified Urca process, the critical temperature for this superfluid transition is required to be ~ 0.5x10^9 K. Our prediction that this cooling will continue for several decades at an almost constant rate can be tested by continuous monitoring of this neutron star.

  11. Impact of the first-forbidden $\\beta$ decay on the production of $A \\sim 195$ r-process peak

    CERN Document Server

    Nishimura, Nobuya; Fang, Dong-Liang; Suzuki, Toshio

    2016-01-01

    We investigated the effects of first-forbidden transitions in $\\beta$ decays on the production of the r-process $A \\sim 195$ peak. The theoretical calculated $\\beta$-decay rates with $\\beta$-delayed neutron emission were examined using several astrophysical conditions. As the first-borbidden decay is dominant in $N \\sim 126$ neutron-rich nuclei, their inclusion shortens $\\beta$-decay lifetimes and shifts the abundance peak towards higher masses. Additionally, the inclusion of the $\\beta$-delayed neutron emission results in a wider abundance peak, and smoothens the mass distribution by removing the odd-even mass staggering. The effects are commonly seen in the results of all adopted astrophysical models. Nevertheless there are quantitative differences, indicating that remaining uncertainty in the determination of half-lives for $N=126$ nuclei is still significant in order to determine the production of the r-process peak.

  12. 2D Cooling of Magnetized Neutron Stars

    CERN Document Server

    Aguilera, Deborah N; Miralles, Juan A

    2007-01-01

    Context: Many thermally emitting isolated neutron stars have magnetic fields larger than 10^{13}G. A realistic cooling model should be reconsidered including the presence of high magnetic fields. Aims: We investigate the effects of anisotropic temperature distribution and Joule heating on the cooling of magnetized neutron stars. Methods: The 2D heat transfer equation with anisotropic thermal conductivity tensor and including all relevant neutrino emission processes is solved for realistic models of the neutron star interior and crust. Results: The presence of the magnetic field affects significantly the thermal surface distribution and the cooling history during both, the early neutrino cooling era and the late photon cooling era. Conclusions: There is a huge effect of the Joule heating on the thermal evolution of strongly magnetized neutron stars. Magnetic fields and Joule heating play a key role in maintaining magnetars warm for a long time. Moreover, this effect is also important for intermediate field neu...

  13. Weapons Neutron Research Facility (WNR)

    Data.gov (United States)

    Federal Laboratory Consortium — The Weapons Neutron Research Facility (WNR) provides neutron and proton beams for basic, applied, and defense-related research. Neutron beams with energies ranging...

  14. Study of neutron spectrometers for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Kaellne, Jan

    2005-11-15

    A review is presented of the developments in the field of neutron emission spectrometry (NES) which is of relevance for identifying the role of NES diagnostics on ITER and selecting suitable instrumentation. Neutron spectrometers will be part of the ITER neutron diagnostic complement and this study makes a special effort to examine which performance characteristics the spectrometers should possess to provide the best burning plasma diagnostic information together with neutron cameras and neutron yield monitors. The performance of NES diagnostics is coupled to how much interface space can be provided which has lead to an interest to find compact instruments and their NES capabilities. This study assesses all known spectrometer types of potential interest for ITER and makes a ranking of their performance (as demonstrated or projected), which, in turn, are compared with ITER measurement requirements as a reference; the ratio of diagnostic performance to interface cost for different spectrometers is also discussed for different spectrometer types. The overall result of the study is an assessment of which diagnostic functions neutron measurements can provide in burning plasma fusion experiments on ITER and the role that NES can play depending on the category of instrument installed. Of special note is the result that much higher quality diagnostic information can be obtained from neutron measurements with total yield monitors, profile flux cameras and spectrometers when the synergy in the data is considered in the analysis and interpretation.

  15. Pulsed neutron sources for epithermal neutrons

    International Nuclear Information System (INIS)

    It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

  16. Role of nucleonic Fermi surface depletion in neutron star cooling

    CERN Document Server

    Dong, J M; Zhang, H F; Zuo, W

    2015-01-01

    The Fermi surface depletion of beta-stable nuclear matter is calculated to study its effects on several physical properties which determine the neutron star thermal evolution. The neutron and proton Z factors measuring the corresponding Fermi surface depletions, are calculated within the Brueckner-Hartree-Fock approach employing the AV18 two-body force supplemented by a microscopic three body force. Neutrino emissivity, heat capacity and, in particular, neutron 3PF2 superfluidity turn out to be reduced, especially at high baryonic density, to such an extent that the cooling rates of young neutron stars are significantly slowed

  17. Enhancing the detector for advanced neutron capture experiments

    International Nuclear Information System (INIS)

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons

  18. Gravitational waves from accreting neutron stars

    OpenAIRE

    Bonazzola, S.; Gourgoulhon, E.

    1996-01-01

    We show that accreting neutron stars in binary systems or in Landau-Thorne-Zytkow objects are good candidates for continuous gravitational wave emission. Their gravitational radiation is strong enough to be detected by the next generation of detectors having a typical noise of 10^{-23} Hz^{-1/2}.

  19. Neutrino emission from cooling neutron stars

    International Nuclear Information System (INIS)

    Most interpretations of the neutrinos collected from SN 1987A assume the emitted spectrum was in a Fermi-Dirac distribution with zero chemical potential. To investigate this assumption, the authors examine the results of numerical simulations. They also examine models with a power-law atmosphere employing multi-group neutrino transport. They find many of the numerical spectra are best fit by thermal distributions having small positive chemical potentials. Fortunately the effect of such corrections is not appreciable enough to require extensive re-interpretation of the SN 1987A neutrino data

  20. Recent research on nuclear reaction using high-energy proton and neutron

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Tokushi [Tokyo Univ., Tanashi (Japan). Inst. for Nuclear Study

    1997-11-01

    The presently available high-energy neutron beam facilities are introduced. Then some interesting research on nuclear reaction using high-energy protons are reported such as the intermediate mass fragments emission and neutron spectrum measurements on various targets. As the important research using high-energy neutron, the (p,n) reactions on Mn, Fe, and Ni, the elastic scattering of neutrons, and the shielding experiments are discussed. (author)

  1. Ion Acceleration in Solar Flares Determined by Solar Neutron Observations

    Science.gov (United States)

    Watanabe, K.; Solar Neutron Observation Group

    2013-05-01

    Large amounts of particles can be accelerated to relativistic energy in association with solar flares and/or accompanying phenomena (e.g., CME-driven shocks), and they sometimes reach very near the Earth and penetrate the Earth's atmosphere. These particles are observed by ground-based detectors (e.g., neutron monitors) as Ground Level Enhancements (GLEs). Some of the GLEs originate from high energy solar neutrons which are produced in association with solar flares. These neutrons are also observed by ground-based neutron monitors and solar neutron telescopes. Recently, some of the solar neutron detectors have also been operating in space. By observing these solar neutrons, we can obtain information about ion acceleration in solar flares. Such neutrons were observed in association with some X-class flares in solar cycle 23, and sometimes they were observed by two different types of detectors. For example, on 2005 September 7, large solar neutron signals were observed by the neutron monitor at Mt. Chacaltaya in Bolivia and Mexico City, and by the solar neutron telescopes at Chacaltaya and Mt. Sierra Negra in Mexico in association with an X17.0 flare. The neutron signal continued for more than 20 minutes with high statistical significance. Intense gamma-ray emission was also registered by INTEGRAL, and by RHESSI during the decay phase. We analyzed these data using the solar-flare magnetic-loop transport and interaction model of Hua et al. (2002), and found that the model could successfully fit the data with intermediate values of loop magnetic convergence and pitch angle scattering parameters. These results indicate that solar neutrons were produced at the same time as the gamma-ray line emission and that ions were continuously accelerated at the emission site. In this paper, we introduce some of the solar neutron observations in solar cycle 23, and discuss the tendencies of the physical parameters of solar neutron GLEs, and the energy spectrum and population of the

  2. Li2Se:Te as a neutron scintillator

    International Nuclear Information System (INIS)

    We show that Li2Se:Te is a potential neutron scintillator material based on density functional calculations. Li2Se exhibits a number of properties favorable for efficient neutron detection, such as a high Li concentration for neutron absorption, a small effective atomic mass and a low density for reduced sensitivity to background gamma rays, and a small band gap for a high light yield. Our calculations show that Te doping should lead to the formation of deep acceptor complex VLi–TeSe, which can facilitate efficient light emission, similar to the emission activation in Te doped ZnSe. - Highlights: • Te doped Li2Se is proposed as a promising neutron scintillator based on density functional calculations. • Li2Se has a high Li concentration, a low density, and a small band gap, favorable for neutron detection. • Li2Se can be activated by VLi–TeSe

  3. Neutron in biology

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    Neutron in biology can provide an experimental method of directly locating relationship of proteins and DNA. However, there are relatively few experimental study of such objects since it takes a lot of time to collect a sufficient number of Bragg reflections and inelastic spectra due to the low flux of neutron illuminating the sample. Since a next generation neutron source of JAERI will be 5MW spallation neutron source and its effective neutron flux will be 10{sup 2} to 10{sup 3} times higher than the one of JRR-3M, neutron in biology will open a completely new world for structural biology. (author)

  4. Broadband Neutron Interferometer

    CERN Document Server

    Pushin, Dmitry A; Hussey, Dan; Miao, Houxun; Arif, Muhammad; Cory, David G; Huber, Michael G; Jacobson, David; LaManna, Jacob; Parker, Joseph D; Shinohara, Taken; Ueno, Wakana; Wen, Han

    2016-01-01

    We demonstrate a two phase-grating, multi-beam neutron interferometer by using a modified Ronchi setup in a far-field regime. The functionality of the interferometer is based on the universal \\moire effect that was recently implemented for X-ray phase-contrast imaging in the far-field regime. Interference fringes were achieved with monochromatic, bichromatic, and polychromatic neutron beams; for both continuous and pulsed beams. This far-field neutron interferometry allows for the utilization of the full neutron flux for precise measurements of potential gradients, and expands neutron phase-contrast imaging techniques to more intense polycromatic neutron beams.

  5. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  6. Reactor neutron dosimetry

    International Nuclear Information System (INIS)

    An analysis of requirements and possibilities for experimental neutron spectrum determination during the reactor pressure vessel surveil lance programme is given. Fast neutron spectrum and neutron dose rate were measured in the Fast neutron irradiation facility of our TRIGA reactor. It was shown that the facility can be used for calibration of neutron dosimeters and for irradiation of samples sensitive to neutron radiation. The investigation of the unfolding algorithm ITER was continued. Based on this investigations are two specialized unfolding program packages ITERAD and ITERGS written this year. They are able to unfold data from activation detectors and NaI(T1) gamma spectrometer respectively

  7. Neutron streak camera

    Science.gov (United States)

    Wang, Ching L.

    1983-09-13

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  8. Neutron scattering and spallation neutron sources

    International Nuclear Information System (INIS)

    Neutron scattering as a probe of microscopic structure and dynamics is a powerful tool for research in a wide variety of fields, and an accelerator-based spallation neutron source can supply high flux pulses for neutron scattering. The characteristics of neutron scattering, the principle and development of spallation neutron sources, and their advantages in multidisciplinary applications are summarized. In the proposed project of the Chinese Spallation Neutron Source the target station will consist of a piece-stacked tungsten target, a Be/Fe reflector and an Fe/heavy concrete bio-protected shelter. The pulsed neutron flux will be up to 2.4 x 1016 n/cm2/s under a nuclear power of 100 kW. Five neutron scattering instruments--a high flux powder diffractometer, a high resolution powder diffractometer, small angle diffractometer, multi-functional reflectometer and direct geometry inelastic spectrometer, will be constructed as the first step to cover most neutron scattering applications. (authors)

  9. Neutron production with mixture of deuterium and krypton in Sahand Filippov type plasma focus facility

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, M.A., E-mail: mohammadidorbash@yahoo.com [Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Sobhanian, S. [Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Rawat, R.S. [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University (Singapore)

    2011-08-01

    This Letter reports the order of magnitude enhancement in neutron yield from Sahand plasma focus device with krypton seeded deuterium operation. The highest average neutron yield of 2.2x10{sup 9} neutrons per shot was achieved at 1.00 Torr deuterium with 3% krypton which is higher than the best average neutron yield of 3.18x10{sup 8} neutrons per shot for pure deuterium operation. Estimation of average neutron energy showed that the maximum and minimum average energies are 2.98±0.6 MeV at 16 kV in 0.25 Torr deuterium with 3% Kr and 2.07±0.2 MeV at 18 kV operation in 0.5 Torr deuterium with 3% Kr, respectively. The anisotropy of neutron emission from Sahand DPF showed that the neutrons are produced mainly by beam-target mechanisms. -- Highlights: → The highest average neutron yield of 2.2x10{sup 9} neutrons per shot was achieved at mixture of deuterium and krypton. → In the krypton seeding of deuterium also anisotropy of neutron emission deuterium is found. → The krypton seeding of deuterium made the neutron emission more reliable over wider operating pressure ranges.

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

    Science.gov (United States)

    Stetcu, I.; Talou, P.; Kawano, T.

    2016-06-01

    We have applied the Hauser-Feshbach statistical theory, in a Monte-Carlo implementation, to the de-excitation of fission fragments, obtaining a reasonable description of the characteristics of neutrons and gamma rays emitted before beta decays toward stability. Originally implemented for the spontaneous fission of 252Cf and the neutroninduced fission of 235U and 239Pu at thermal neutron energy, in this contribution we discuss the extension of the formalism to incident neutron energies up to 20 MeV. For the emission of pre-fission neutrons, at incident energies beyond second-chance fission, we take into account both the pre-equilibrium and statistical pre-fission components. Phenomenological parameterizations of mass, charge and TKE yields are used to obtain the initial conditions for the fission fragments that subsequently decay via neutron and emissions. We illustrate this approach for 239Pu(n,f).

  11. Progress on the realization of a new GEM based neutron diagnostic concept for high flux neutron beams

    Science.gov (United States)

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

    2014-08-01

    Fusion reactors will need high flux neutron detectors to diagnose the deuterium-deuterium and deuterium-tritium. A candidate detection technique is the Gas Electron Multiplier (GEM). New GEM based detectors are being developed for application to a neutral deuterium beam test facility. The proposed detection system is called Close-contact Neutron Emission Surface Mapping (CNESM). The diagnostic aims at providing the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. This is done by placing a detector in close contact, right behind the dump. CNESM uses nGEM detectors, i.e. GEM detectors equipped with a cathode that also serves as neutron-proton converter foil. After the realization and test of several small area prototypes, a full size prototype has been realized and tested with laboratory sources. Test on neutron beams are foreseen for the next months.

  12. Neutron counter based on beryllium activation

    Energy Technology Data Exchange (ETDEWEB)

    Bienkowska, B.; Prokopowicz, R.; Kaczmarczyk, J.; Paducha, M. [Institute of Plasma Physics and Laser Microfusion (IPPLM), Hery 23, 01-497 Warsaw (Poland); Scholz, M.; Igielski, A. [Institute of Nuclear Physics PAS (IFJPAN), Radzikowskiego 152, 31-342 Krakow (Poland); Karpinski, L. [Faculty of Electrical Engineering, Rzeszow University of Technology, Pola 2, 35-959 Rzeszow (Poland); Pytel, K. [National Centre for Nuclear Research (NCBJ), Soltana 7, 05-400 Otwock - Swierk (Poland)

    2014-08-21

    The fusion reaction occurring in DD plasma is followed by emission of 2.45 MeV neutrons, which carry out information about fusion reaction rate and plasma parameters and properties as well. Neutron activation of beryllium has been chosen for detection of DD fusion neutrons. The cross-section for reaction {sup 9}Be(n, α){sup 6}He has a useful threshold near 1 MeV, which means that undesirable multiple-scattered neutrons do not undergo that reaction and therefore are not recorded. The product of the reaction, {sup 6}He, decays with half-life T{sub 1/2} = 0.807 s emitting β{sup −} particles which are easy to detect. Large area gas sealed proportional detector has been chosen as a counter of β–particles leaving activated beryllium plate. The plate with optimized dimensions adjoins the proportional counter entrance window. Such set-up is also equipped with appropriate electronic components and forms beryllium neutron activation counter. The neutron flux density on beryllium plate can be determined from the number of counts. The proper calibration procedure needs to be performed, therefore, to establish such relation. The measurements with the use of known β–source have been done. In order to determine the detector response function such experiment have been modeled by means of MCNP5–the Monte Carlo transport code. It allowed proper application of the results of transport calculations of β{sup −} particles emitted from radioactive {sup 6}He and reaching proportional detector active volume. In order to test the counter system and measuring procedure a number of experiments have been performed on PF devices. The experimental conditions have been simulated by means of MCNP5. The correctness of simulation outcome have been proved by measurements with known radioactive neutron source. The results of the DD fusion neutron measurements have been compared with other neutron diagnostics.

  13. Neutron counter based on beryllium activation

    Science.gov (United States)

    Bienkowska, B.; Prokopowicz, R.; Scholz, M.; Kaczmarczyk, J.; Igielski, A.; Karpinski, L.; Paducha, M.; Pytel, K.

    2014-08-01

    The fusion reaction occurring in DD plasma is followed by emission of 2.45 MeV neutrons, which carry out information about fusion reaction rate and plasma parameters and properties as well. Neutron activation of beryllium has been chosen for detection of DD fusion neutrons. The cross-section for reaction 9Be(n, α)6He has a useful threshold near 1 MeV, which means that undesirable multiple-scattered neutrons do not undergo that reaction and therefore are not recorded. The product of the reaction, 6He, decays with half-life T1/2 = 0.807 s emitting β- particles which are easy to detect. Large area gas sealed proportional detector has been chosen as a counter of β-particles leaving activated beryllium plate. The plate with optimized dimensions adjoins the proportional counter entrance window. Such set-up is also equipped with appropriate electronic components and forms beryllium neutron activation counter. The neutron flux density on beryllium plate can be determined from the number of counts. The proper calibration procedure needs to be performed, therefore, to establish such relation. The measurements with the use of known β-source have been done. In order to determine the detector response function such experiment have been modeled by means of MCNP5-the Monte Carlo transport code. It allowed proper application of the results of transport calculations of β- particles emitted from radioactive 6He and reaching proportional detector active volume. In order to test the counter system and measuring procedure a number of experiments have been performed on PF devices. The experimental conditions have been simulated by means of MCNP5. The correctness of simulation outcome have been proved by measurements with known radioactive neutron source. The results of the DD fusion neutron measurements have been compared with other neutron diagnostics.

  14. Characterization of short-pulse laser driven neutron source

    Science.gov (United States)

    Falk, Katerina; Jung, Daniel; Guler, Nevzat; Deppert, Oliver; Devlin, Matthew; Fernandez, J. C.; Gautier, D. C.; Geissel, M.; Haight, R. C.; Hegelich, B. M.; Henzlova, Daniela; Ianakiev, K. D.; Iliev, Metodi; Johnson, R. P.; Merrill, F. E.; Schaumann, G.; Schoenberg, K.; Shimada, T.; Taddeucci, T. N.; Tybo, J. L.; Wagner, F.; Wender, S. A.; Wurden, G. A.; Favalli, Andrea; Roth, Markus

    2014-10-01

    We present a full spectral characterization of a novel laser driven neutron source, which employed the Break Out Afterburner ion acceleration mechanism. Neutrons were produced by nuclear reactions of the ions deposited on Be or Cu converters. We observed neutrons at energies up to 150 MeV. The neutron spectra were measured by five neutron time-of-flight detectors at various positions and distances from the source. The nTOF detectors observed that emission of neutrons is a superposition of an isotropic component peaking at 3.5--5 MeV resulting from nuclear reactions in the converter and a directional component at 25--70 MeV, which was a product of break-up reaction of the forward moving deuterons. Energy shifts due to geometrical effects in BOA were also observed.

  15. Neutron anatomy

    International Nuclear Information System (INIS)

    The familiar extremes of crystalline material are single-crystals and random powders. In between these two extremes are polycrystalline aggregates, not randomly arranged but possessing some preferred orientation and this is the form taken by constructional materials, be they steel girders or the bones of a human or animal skeleton. The details of the preferred orientation determine the ability of the material to withstand stress in any direction. In the case of bone the crucial factor is the orientation of the c-axes of the mineral content - the crystals of the hexagonal hydroxyapatite - and this can readily be determined by neutron diffraction. In particular it can be measured over the volume of a piece of bone, utilizing distances ranging from 1mm to 10mm. The major practical problem is to avoid the intense incoherent scattering from the hydrogen in the accompanying collagen; this can best be achieved by heat-treatment and it is demonstrated that this does not affect the underlying apatite. These studies of bone give leading anatomical information on the life and activities of humans and animals - including, for example, the life history of the human femur, the locomotion of sheep, the fracture of the legs of racehorses and the life-styles of Neolithic tribes. We conclude that the material is placed economically in the bone to withstand the expected stresses of life and the environment. The experimental results are presented in terms of the magnitude of the 0002 apatite reflection. It so happens that for a random powder the 0002, 1121 reflections, which are neighboring lines in the powder pattern, are approximately equal in intensity. The latter reflection, being of manifold multiplicity, is scarcely affected by preferred orientation so that the numerical value of the 0002/1121 ratio serves quite accurately as a quantitative measure of the degree of orientation of the c-axes in any chosen direction for a sample of bone

  16. Neutron anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, G.E. [Univ. of Sheffield (United Kingdom)

    1994-12-31

    The familiar extremes of crystalline material are single-crystals and random powders. In between these two extremes are polycrystalline aggregates, not randomly arranged but possessing some preferred orientation and this is the form taken by constructional materials, be they steel girders or the bones of a human or animal skeleton. The details of the preferred orientation determine the ability of the material to withstand stress in any direction. In the case of bone the crucial factor is the orientation of the c-axes of the mineral content - the crystals of the hexagonal hydroxyapatite - and this can readily be determined by neutron diffraction. In particular it can be measured over the volume of a piece of bone, utilizing distances ranging from 1mm to 10mm. The major practical problem is to avoid the intense incoherent scattering from the hydrogen in the accompanying collagen; this can best be achieved by heat-treatment and it is demonstrated that this does not affect the underlying apatite. These studies of bone give leading anatomical information on the life and activities of humans and animals - including, for example, the life history of the human femur, the locomotion of sheep, the fracture of the legs of racehorses and the life-styles of Neolithic tribes. We conclude that the material is placed economically in the bone to withstand the expected stresses of life and the environment. The experimental results are presented in terms of the magnitude of the 0002 apatite reflection. It so happens that for a random powder the 0002, 1121 reflections, which are neighboring lines in the powder pattern, are approximately equal in intensity. The latter reflection, being of manifold multiplicity, is scarcely affected by preferred orientation so that the numerical value of the 0002/1121 ratio serves quite accurately as a quantitative measure of the degree of orientation of the c-axes in any chosen direction for a sample of bone.

  17. Neutrino Processes in Neutron Stars

    Science.gov (United States)

    Kolomeitsev, E. E.; Voskresensky, D. N.

    2010-10-01

    The aim of these lectures is to introduce basic processes responsible for cooling of neutron stars and to show how to calculate the neutrino production rate in dense strongly interacting nuclear medium. The formalism is presented that treats on equal footing one-nucleon and multiple-nucleon processes and reactions with virtual bosonic modes and condensates. We demonstrate that neutrino emission from dense hadronic component in neutron stars is subject of strong modifications due to collective effects in the nuclear matter. With the most important in-medium processes incorporated in the cooling code an overall agreement with available soft X ray data can be easily achieved. With these findings the so-called “standard” and “non-standard” cooling scenarios are replaced by one general “nuclear medium cooling scenario” which relates slow and rapid neutron star coolings to the star masses (interior densities). The lectures are split in four parts. Part I: After short introduction to the neutron star cooling problem we show how to calculate neutrino reaction rates of the most efficient one-nucleon and two-nucleon processes. No medium effects are taken into account in this instance. The effects of a possible nucleon pairing are discussed. We demonstrate that the data on neutron star cooling cannot be described without inclusion of medium effects. It motivates an assumption that masses of the neutron stars are different and that neutrino reaction rates should be strongly density dependent. Part II: We introduce the Green’s function diagram technique for systems in and out of equilibrium and the optical theorem formalism. The latter allows to perform calculations of production rates with full Green’s functions including all off-mass-shell effects. We demonstrate how this formalism works within the quasiparticle approximation. Part III: The basic concepts of the nuclear Fermi liquid approach are introduced. We show how strong interaction effects can be

  18. Neutron color image intensifier

    International Nuclear Information System (INIS)

    Neutron radiography is expanding from the conventional reactor based imaging to the imaging by accelerator based pulsed neutron source. Among them, an expectation for image intensifier technology is increasing especially for video rate dynamic image detection or time dependent imaging in a pulsed neutron source. Based on the X-ray color image intensifier technology, Toshiba has developed neutron color image intensifiers as a powerful imaging tool for dynamic and time dependent neutron radiographics. In this paper, the construction and the feature of the developed neutron color image intensifier and some examples of neutron images are presented. I would be grateful if this paper helps for wide application of neutron color image intensifiers. (author)

  19. Neutron radiation capture

    International Nuclear Information System (INIS)

    For all stable and experimentally studied radionuclides evaluated data are presented on cross sections of thermal neutrons, on resonance integrals and medium neutron cross sections with energy of 30 KeV. Refs, figs and tabs

  20. Neutrons from Antiproton Irradiation

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael; Petersen, Jørgen B.B.

    the volume targeted for irradiation. A major part of this peripheral dose arise from neutrons, which in particular are problematic due to their high RBE for secondary cancer incidence. We have measured the fast and thermal neutron spectrum in different geometrical configurations in order to experimentally...... the neutron spectrum. Additionally, we used a cylindrical polystyrene loaded with several pairs of thermoluminescent detectors containing Lithium-6 and Lithium-7, which effectively detects thermalized neutrons. The obtained results are compared with FLUKA imulations. Results: The results obtained...... the annihilation vertex inside the polystyrene phantom produced a response which corresponds to a neutron fluence of 8000 neutrons/cm2 per 107 antiprotons. This is equivalent to a neutron kerma of 1.4e-9 Gy (adult brain) per 107 antiprotons following ICRU 46. Conclusion: The thermalized part of the neutron...

  1. Installation of a D-D Type Neutron Generator and Its Performance Test

    International Nuclear Information System (INIS)

    This report describes a applicability of neutron generator to the development of neutron counters regarding with research project, 'development of nuclear material accounting and safeguards technologies'. Selection of the generator, installation, radiation shielding and dose evaluation of the operating area, and its basic performance test result are described in detail. The subject neutron generator is GENIE16GT model of EADS SODERN, France, and it is a D-D type generator with the maximum flux of 2E06 n/s of 2.5 MeV neutron and operating range of 80 μA and 110 kV. A neutron generator has several advantages over a radioisotope neutron source for development and performance test of neutron counting equipments. One of the important advantages is that it can control the emission. No emission of the turned-off neutron source is of importance in the view point of radiation safety, as well as its applicability of variable flux. Pulse mode emission is also applicable to develop the non-destructive technology based on delayed gamma rays or delayed neutrons. The experimental results showed larger error for the case of neutron generator as an interrogation source than the case of isotope source, and there should be more efforts to reduce the error. We expect, however, the generator would be highly applicable to basic performance test of neutron counters for nuclear materials, to the situation in which radioisotope neutron source is not preferred, to the active neutron counting system whose measurement uncertainty for acceptance level is reasonably high, or to the situation in which the integrated system of passive/active neutron and gamma counting is needed. And, if we maximize its advantages of control the neutron emission, the safeguards techniques for a spent fuel management process will be expanded and have a high confidence by combining with other conventional non-destructive assay methods

  2. Imaging with Scattered Neutrons

    OpenAIRE

    Ballhausen, H.; Abele, H.; Gaehler, R.; Trapp, M; Van Overberghe, A.

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-re...

  3. Properties of neutron sources

    International Nuclear Information System (INIS)

    The Conference presentations were divided into sessions devoted to the following topics: white neutron sources, primarily pulsed (6 papers); fast neutron fields (5 papers); Californium-252 prompt fission neutron spectra (14 papers); monoenergetic sources and filtered beams (11 papers); 14 MeV neutron sources (10 papers); selected special application (one paper); and a general interest session (4 papers). Individual abstracts were prepared separately for the papers

  4. Proceedings of the specialists' meeting on delayed neutron nuclear data

    International Nuclear Information System (INIS)

    This report is the Proceedings of the Specialists' Meeting on Delayed Neutron Nuclear Data. The meeting was held on January 28-29, 1999, at the Tokai Research Establishment of Japan Atomic Energy Research Institute with the participation of thirty specialists, who are evaluators, theorist, experimentalists. Although the fraction of the delayed neutron is no more than 1% in the total neutrons emitted in the fission process, it plays an important roll in the control of fission reactor. In the meeting, the following topics were reported: the present status of delayed neutron data in the major evaluated data libraries, measurements of effective delayed neutron fraction using FCA (Fast Critical Assembly) and TCA (Tank-type Critical Assembly) and their analyses, sensitivity analysis for fast reactor, measurements of delayed neutron emission from actinides and so on. As another topics, delayed neutron in transmutation system and fission yield data were also presented. Free discussion was held on the future activity of delayed neutron data evaluation. The discussion was helpful for the future activity of the delayed neutron working group of JNDC aiming to the evaluation of delayed neutron data for JENDL-3.3. The 15 of the presented papers are indexed individually. (J.P.N.)

  5. Isotopic neutron sources for neutron activation analysis

    International Nuclear Information System (INIS)

    This User's Manual is an attempt to provide for teaching and training purposes, a series of well thought out demonstrative experiments in neutron activation analysis based on the utilization of an isotopic neutron source. In some cases, these ideas can be applied to solve practical analytical problems. 19 refs, figs and tabs

  6. Neutron pinhole camera investigations on temporal and spatial structures of plasma focus neutron source

    International Nuclear Information System (INIS)

    The neutron emission of the Frascati 1-MJ-plasma focus has been investigated over an energy range of 250 to 500kJ by means of a neutron pinhole camera, using a six-channel detector array. Single-shot neutron streak images, space- and time-resolved, are obtained with an axial resolution of 2 cm and a time resolution of about 5ns. - Results show that over 70% of the neutrons (i.e. more than 1011 neutrons per shot at 490kJ) are emitted from a co-axial cylindrical volume about 4cm long and less than 4cm in diameter at the anode tip. Neither axial nor radial motion of this main source is observed throughout the emission lasting 200ns FWHM typically. Simultaneous independent measurements show, for this zone, an isotropic neutron fluence (A=PHI (axial)/PHI (equat.)=0.97+-0.04), while the energy spectra still are anisotropic as reported previously. (author)

  7. Fundamental neutron physics

    International Nuclear Information System (INIS)

    Fundamental physics experiments of merit can be conducted at the proposed intense neutron sources. Areas of interest include: neutron particle properties, neutron wave properties, and fundamental physics utilizing reactor produced γ-rays. Such experiments require intense, full-time utilization of a beam station for periods ranging from several months to a year or more

  8. International Neutron Radiography Newsletter

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1986-01-01

    At the First World Conference on Neutron Radiography i t was decided to continue the "Neutron Radiography Newsletter", published previously by J.P. Barton, as the "International Neutron Radiography Newsletter" (INRNL), with J.C. Doraanus as editor. The British Journal of Non-Destructive Testing...

  9. Thermal neutron beamline monitor

    International Nuclear Information System (INIS)

    A detector has been developed which has characteristics that make it suitable for use as a neutron beamline monitor on the Spallation Neutron Source. Efficiency has been reduced to 10-4, pulse pair resolution is 50 nSecs and it presents minimal obstruction to the neutron beam. (author)

  10. Polarized Neutron Scattering

    OpenAIRE

    Roessli, B.; Böni, P.

    2000-01-01

    The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

  11. DIANE: Advanced system for mobile neutron radiology

    Science.gov (United States)

    Dance, W. E.; Huriet, J. R.; Cluzeau, S.; Mast, H.-U.; Albisu, F.

    1989-04-01

    Development of a new neutron radiology system, DIANE, is underway which will provide a ten-fold improvement in image-acquisition speed over presently operating mobile systems, insuring greater inspection throughput for production applications. Based on a 10 12 n/s sealed-tube (D-T) neutron generator under development by Sodern, on LTV's neutron moderator/collimator and electronic imaging systems and on robotic and safety systems being developed by IABG and Sener, the DIANE concept is that of a complete facility for on-site neutron radiography or radioscopy. The LTV components, which provide film or electronic imaging, including digital processing of 12-bit images, have been demonstrated in three basic systems now operating with Kaman A-711 neutron generators, including one operating in IABG's facilities. Sodern has fabricated a prototype neutron generator tube, the TN 46, for emission of 10 11 n/s over 1000 to 1500 hours, at 250 kV and 2 mA in the ion beam.

  12. Neutron stars probes for high density baryon pairing

    CERN Document Server

    Page, D

    1995-01-01

    We consider, in general terms, the early thermal evolution of an isolated neutron star, i.e., during the first 10^5 years after the supernova explosion when the cooling is driven by neutrino emission from the core. It is shown that, if fast neutrino emission is occuring, the surface temperature is actually determined by the critical temperature T_c at which the core baryons become superfluid, and almost nothing else. In particular, the dependence on the actual neutrino emission process is very weak. In other terms, fast neutrino cooling neutron stars are thermometers for the highest T_c superfluid (superconductor) in the Universe. The observational data are briefly presented.

  13. Comparison between LYRA and SAND code performance for the extrapolation of data from activation detectors used for determining spectra of acceleration neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Birattari, C.; Cesana, P.; Salomone, A.

    1980-08-26

    Mathematical descriptions are given of the LYRA and SAND programs which are then used to evaluate typical acceleration neutron spectra or various energy conditions of incident protons, bombardment materials, and angle of neutron emission. 16 references, 12 figures, 1 table.

  14. Fast neutron spectrometry using thick threshold detectors

    OpenAIRE

    Idiri Z.; Allab M.; Boukeffoussa K.; Medkour Ishak-Boushaki G.

    2012-01-01

    This paper discusses the use of thick threshold activation detectors for the characterization of low intensity neutron fields. This technique has been applied to the determination of the spectral emission of a low activity (37 GBq) Am-Be source. The reaction rates induced by the neutrons emitted by this source in different thick metallic targets (Al, Si, Fe, In) have been measured in the following reactions: 27Al(n,p)27Mg, 27Al(n,α)24Na, 28Si(n,p)28Al, 56Fe(n,p)56Mn, 115In(n, n′)115mIn and 11...

  15. Neutron removal cross section as a measure of neutron skin

    OpenAIRE

    D. Q. Fang; Y. G. Ma; Cai, X. Z.(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800, Shanghai, China); Tian, W.D.; Wang, H. W.

    2010-01-01

    We study the relation between neutron removal cross section ($\\sigma_{-N}$) and neutron skin thickness for finite neutron rich nuclei using the statistical abrasion ablation (SAA) model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is a good linear correlation between $\\sigma_{-N}$ and the neutron skin thickness for neutron rich nuclei. Further analysis suggests that the relative increa...

  16. Neutron scattering. Experiment manuals

    International Nuclear Information System (INIS)

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  17. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2012-07-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, the neutron polarization analyzer DNS, the neutron spin-echo spectrometer J-NSE, the small-angle neutron diffractometers KWS-1/-2, the very-small-angle neutron diffractometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  18. Grazing Incidence Neutron Optics

    Science.gov (United States)

    Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

    2013-01-01

    Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20.ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

  19. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  20. Neutron scattering. Experiment manuals

    International Nuclear Information System (INIS)

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, the neutron polarization analyzer DNS, the neutron spin-echo spectrometer J-NSE, the small-angle neutron diffractometers KWS-1/-2, the very-small-angle neutron diffractometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  1. Neutron scatter camera

    Science.gov (United States)

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  2. Rapidly rotating neutron star progenitors

    CERN Document Server

    Postnov, K A; Kolesnikov, D A; Popov, S B; Porayko, N K

    2016-01-01

    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In the present paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, $\\tau_c$. The validity of this approach is checked by direct MESA calculations ...

  3. Comparing neutron and X-ray images from NIF implosions

    Directory of Open Access Journals (Sweden)

    Wilson D.C.

    2013-11-01

    Full Text Available Directly laser driven and X-radiation driven DT filled capsules differ in the relationship between neutron and X-ray images. Shot N110217, a directly driven DT-filled glass micro-balloon provided the first neutron images at the National Ignition Facility. As seen in implosions on the Omega laser, the neutron image can be enclosed inside time integrated X-ray images. HYDRA simulations show the X-ray image is dominated by emission from the hot glass shell while the neutron image arises from the DT fuel it encloses. In the absence of mix or jetting, X-ray images of a cryogenically layered THD fuel capsule should be dominated by emission from the hydrogen rather than the cooler plastic shell that is separated from the hot core by cold DT fuel. This cool, dense DT, invisible in X-ray emission, shows itself by scattering hot core neutrons. Germanium X-ray emission spectra and Ross pair filtered X-ray energy resolved images suggest that germanium doped plastic emits in the torus shaped hot spot, probably reducing the neutron yield.

  4. Advances in neutron tomography

    Indian Academy of Sciences (India)

    W Treimer

    2008-11-01

    In the last decade neutron radiography (NR) and tomography (NCT) have experienced a number of improvements, due to the well-known properties of neutrons interacting with matter, i.e. the low attenuation by many materials, the strong attenuation by hydrogenous constituent in samples, the wavelength-dependent attenuation in the neighbourhood of Bragg edges and due to better 2D neutron detectors. So NR and NCT were improved by sophisticated techniques that are based on the attenuation of neutrons or on phase changes of the associated neutron waves if they pass through structured materials. Up to now the interaction of the neutron spin with magnetic fields in samples has not been applied to imaging techniques despite the fact that it was proposed many years ago. About ten years ago neutron depolarization as imaging signal for neutron radiography or tomography was demonstrated and in principle it works. Now one can present much improved test experiments using polarized neutrons for radiographic imaging. For this purpose the CONRAD instrument of the HMI was equipped with polarizing and analysing benders very similar to conventional scattering experiments using polarized neutrons. Magnetic fields in different coils and in samples (superconductors) at low temperatures could be visualized. In this lecture a summary about standard signals (attenuation) and the more `sophisticated' imaging signals as refraction, small angle scattering and polarized neutrons will be given.

  5. Theoretical model application to the evaluation of fission neutron data up to 20 MeV incidence energy

    International Nuclear Information System (INIS)

    A complex statistical theory of fission neutron emission combined with a phenomenological fission model has been used to calculate fission neutron data for 238U. Obtained neutron multiplicities and energy spectra as well as average fragment energies for incidence energies from threshold to 20 MeV (including multiple-chance fission) are compared with traditional data representations. (author). 19 refs, 6 figs

  6. Influence of fission modes on prompt neutron characteristics in the neutron-induced fission of 235U

    International Nuclear Information System (INIS)

    The de-excitation of the fission fragments formed in the neutron-induced fission of 235U, for incident energies from 0.5 to 6.0 MeV, is simulated numerically. Neutrons are emitted sequentially from a Weisskopf spectrum with a temperature set by previous neutron emissions. The complete decay chain is followed until a fission product is formed and no further neutron emission is allowed energetically. Detailed results are obtained, such as the average prompt neutron multiplicity as a function of the fragment mass and the total kinetic energy ν(A,TKE) and the multiplicity distribution P(ν). An interpretation in terms of fission modes is proposed. It appears that numerical modeling tools have to be sharpened. The results presented here are very promising and should be improved. The proper Hauser-Feshbach treatment (as opposed to Weisskopf-Ewing) of the evaporation process of the excited fission fragments has to be implemented, in particular to correctly account for the competition between neutron and gamma emission near the neutron binding energy

  7. Neutron structural biology

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Neutron diffraction provides an experimental method of directly locating hydrogen atoms in protein which play important roles in physiological functions. However, there are relatively few examples of neutron crystallography in biology since it takes a lot of time to collect a sufficient number of Bragg reflections due to the low flux of neutrons illuminating the sample. In order to overcome the flux problem, we have successfully developed the neutron IP, where the neutron converter, {sup 6}Li or Gd, was mixed with a photostimulated luminescence material on flexible plastic support. Neutron Laue diffraction 2A data from tetragonal lysozyme were collected for 10 days with neutron imaging plates, and 960 hydrogen atoms in the molecule and 157 bound water molecules were identified. These results explain the proposed hydrolysis mechanism of the sugar by the lysozyme molecule and that lysozyme is less active at pH7.0. (author)

  8. Neutron response study

    International Nuclear Information System (INIS)

    Neutron response of the albedo type dosimeter is strongly dependent on the energy of the incident neutrons as well as the moderating material on the backside of the dosimeter. This study characterizes the response of the Hanford dosimeter for a variety of neutron energies for both a water and Rando phantom (a simulated human body consisting of an actual human skeleton with plastic for body muscles and certain organs). The Hanford dosimeter response to neutrons of different energies is typical of albedo type dosimeters. An approximate two orders of magnitude difference in response is observed between neutron energies of 100 keV and 10 MeV. Methods were described to compensate for the difference in dosimeter response between a laboratory neutron spectrum and the different spectra encountered at various facilities in the field. Generally, substantial field support is necessary for accurate neutron dosimetry

  9. The Neutron Star Zoo

    Science.gov (United States)

    Harding, Alice K.

    2014-01-01

    Neutron stars are a very diverse population, both in their observational and their physical properties. They prefer to radiate most of their energy at X-ray and gamma-ray wavelengths. But whether their emission is powered by rotation, accretion, heat, magnetic fields or nuclear reactions, they are all different species of the same animal whose magnetic field evolution and interior composition remain a mystery. This article will broadly review the properties of inhabitants of the neutron star zoo, with emphasis on their high-energy emission. XXX Neutron stars are found in a wide variety of sources, displaying an amazing array of behavior. They can be isolated or in binary systems, accreting, heating, cooling, spinning down, spinning up, pulsing, flaring and bursting. The one property that seems to determine their behavior most strongly is their magnetic field strength, structure and evolution. The hot polar caps, bursts and flares of magnetars are likely due to the rapid decay and twisting of their superstrong magnetic fields, whose very existence requires some kind of early dynamo activity. The intermediate-strength magnetic fields of RPPs determines their spin-down behavior and radiation properties. However, the overlap of the magnetar and RPP populations is not understood at present. Why don't high-field RPPs burst or flare? Why don't lower-field magnetars sometimes behave more like RPPs? INS may be old magnetars whose high fields have decayed, but they do not account for the existence of younger RPPs with magnetar-strength fields. Not only the strength of the magnetic field but also its configuration may be important in making a NS a magnetar or a RPP. Magnetic field decay is a critical link between other NS populations as well. "Decay" of the magnetic field is necessary for normal RPPs to evolve into MSPs through accretion and spin up in LMXBs. Some kind of accretion-driven field reduction is the most likely mechanism, but it is controversial since it is not

  10. 锰浴法测量中子源发射率中各修正因子的蒙特卡罗计算%Monte Carlo Calculation of Correction Factors for Radionuclide Neutron Source Emission Rate Measurement by Manganese Bath Method

    Institute of Scientific and Technical Information of China (English)

    李春娟; 刘毅娜; 张伟华; 王志强

    2014-01-01

    The manganese bath method for measuring the neutron emission rate of radio-nuclide sources requires corrections to be made for emitted neutrons w hich are not cap-tured by manganese nuclei .The Monte Carlo particle transport code MCNP was used to simulate the manganese bath system of the standards for the measurement of neutron source intensity .The correction factors were calculated and the reliability of the model was demonstrated through the key comparison for the radionuclide neutron source emis-sion rate measurements organized by BIPM .The uncertainties in the calculated values were evaluated by considering the sensitivities to the solution density ,the density of the radioactive material ,the positioning of the source ,the radius of the bath ,and the inter-action cross-sections .A new method for the evaluation of the uncertainties in Monte Carlo calculation was given .%在采用锰浴法对放射性同位素中子源的发射率进行测量时,M nSO4溶液中55 M n仅俘获部分源中子,故需考虑对未被55 Mn俘获部分的修正。用蒙特卡罗粒子输运程序MCNP对中子源强标准装置的锰浴系统进行模拟计算,对实验测量结果进行修正,并通过由国际计量局(BIPM )组织的中子源强度国际比对,验证了计算所建立模型的可靠性。利用MCNP程序的微扰计算功能,通过考虑MnSO4溶液的密度、源及其承托物材料的密度、源的位置、锰浴半径以及反应截面的改变对计算结果的影响,对模拟计算结果的不确定度进行了详细评定,提供了一种蒙特卡罗模拟计算结果不确定度的评定方法。

  11. The Neutron Star Interior Composition Explorer (NICER)

    Science.gov (United States)

    Wilson-Hodge, Colleen A.; Gendreau, K.; Arzoumanian, Z.

    2014-01-01

    The Neutron Star Interior Composition Explorer (NICER) is an approved NASA Explorer Mission of Opportunity dedicated to the study of the extraordinary gravitational, electromagnetic, and nuclear-physics environments embodied by neutron stars. Scheduled to be launched in 2016 as an International Space Station payload, NICER will explore the exotic states of matter, using rotation-resolved spectroscopy of the thermal and non-thermal emissions of neutron stars in the soft (0.2-12 keV) X-ray band. Grazing-incidence "concentrator" optics coupled with silicon drift detectors, actively pointed for a full hemisphere of sky coverage, will provide photon-counting spectroscopy and timing registered to GPS time and position, with high throughput and relatively low background. The NICER project plans to implement a Guest Observer Program, which includes competitively selected user targets after the first year of flight operations. I will describe NICER and discuss ideas for potential Be/X-ray binary science.

  12. Cooling of Hyperonic Neutron Stars with Antikaons

    Institute of Scientific and Technical Information of China (English)

    DING Wen-Bo; YU Zi; LIU Yu-Hui

    2011-01-01

    We discuss the impact of hyperons on the neutrino emitting and the gross cooling features of neutron stars with K(-) and ( ˉ)k0 condensations.The results show that hyperons change the density ranges of the direct Urca process with nucleons and the Urca processes of (K-) and (ˉ)k0 condensations,as well as the values of neutrino emissivity.Moreover,interactions between hyperons and antikaons make the neutrino luminosity complicated.It is found that various hyperons play different roles in neutron stars.For massive stars,∑ hyperons make the cooling slower.However,Λ can hardly change the cooling history but it reduces the mass of neutron stars.

  13. Neutron star cooling: effects of envelope physics

    International Nuclear Information System (INIS)

    Neutron star cooling calculations are reported which employ improved physics in the calculation of the temperature drop through the atmosphere. The atmosphere microphysics is discussed briefly. The predicted neutron star surface temperatures, in the interesting interval 200 less than or equal to t (yr) less than or equal to 105, do not differ appreciably from the earlier results of Van Riper and Lamb (1981) for a non-magnetic star; for a magnetic star, the surface temperature is lower than in the previous work. Comparison with observational limits show that an exotic cooling mechanism, such as neutrino emission from a pion condensate or in the presence of percolating quarks, is not required unless the existence of a neutron star in the Tycho or SN1006 SNRs is established

  14. Nuclear astrophysics with neutrons

    Science.gov (United States)

    Dillmann, I.; Reifarth, R.

    2012-04-01

    Neutrons play a crucial role in astrophysics during the heavy element nucleosynthesis. The largest fraction of isotopes heavier than iron is produced by neutron capture processes on short (r process) and long timescales (s process). During the ``slow neutron capture process'' (s process) heavier elements are produced by successive captures of in-situ produced neutrons from the reactions 13C(α,n)16O and 22Ne(α,n)25Mg (with densities of 106-1010 cm-3) in the interior of stars and following β-decays. With this scenario the reaction path runs along the valley of stability up to 209Bi and produces about 50% of the solar abundances of the heavy elements. Important nuclear physics parameters for s-process nucleosynthesis are neutron capture cross sections (for En = 0.3-300 keV, corresponding to stellar temperatures between kT= 8 and 90 keV) and β-decay half-lives. Neutron capture measurements can be performed via activation in a quasi-stellar neutron spectrum utilizing several (p,n) reactions, or by the time-of-flight technique. The ``rapid neutron capture process'' (r process) is responsible for the remaining 50% of the solar abundances. Here neutrons with densities of 1020-1030 cm-3 are captured on a very fast timescale (ms) during a Core Collapse Supernova in a region close to the forming neutron star. The r-process nuclei are thus very short-lived, neutron-rich isotopes up to the actinides, which can only be produced and investigated at large-scale radioactive-beam facilities. Here the most important nuclear physics parameters are masses, half-lives, and at later stages also β-delayed neutrons. This paper will summarize the role of neutrons in nuclear astrophysics and give a short overview about the related astrophysics programs at the GSI Helmholtz research center and the FRANZ facility in Germany.

  15. Neutrino emissivity under neutral kaon condensation

    OpenAIRE

    Kubis, Sebastian

    2005-01-01

    Neutrino emissivity from neutron star matter with neutral kaon condensate is considered. It is shown that a new cooling channel is opened, and what is more, all previously known channels acquire the greater emissivity reaching the level of the direct URCA cycle in normal matter.

  16. Neutrino emissivity under neutral kaon condensation

    CERN Document Server

    Kubis, S

    2006-01-01

    Neutrino emissivity from neutron star matter with neutral kaon condensate is considered. It is shown that a new cooling channel is opened, and what is more, all previously known channels acquire the greater emissivity reaching the level of the direct URCA cycle in normal matter.

  17. Pulsed neutron porosity logging system

    International Nuclear Information System (INIS)

    An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

  18. Neutrino-pair bremsstrahlung in a neutron star crust

    CERN Document Server

    Ofengeim, D D; Yakovlev, D G

    2014-01-01

    Based on the formalism by Kaminker et al. (Astron. Astrophys. 343 (1999) 1009) we derive an analytic approximation for neutrino-pair bremsstrahlung emissivity due to scattering of electrons by atomic nuclei in the neutron star crust of any realistic composition. The emissivity is expressed through generalized Coulomb logarithm which we fit by introducing an effective potential of electron-nucleus scattering. In addition, we study the conditions at which the neutrino bremsstrahlung in the crust is affected by strong magnetic fields. The results can be applied for modelling of many phenomena in neutron stars, such as thermal relaxation in young isolated neutron stars and in accreting neutron stars with overheated crust in soft X-ray transients.

  19. Neutron chopper development at LANSCE

    International Nuclear Information System (INIS)

    Progress is reported on neutron chopper systems for the Los Alamos Neutron Scattering Center pulsed spallation neutron source. This includes the development of 600+ Hz active magnetic bearing neutron chopper and a high speed control system designed to operate with the Proton Storage Ring to phase the chopper to the neutron source. 5 refs., 3 figs

  20. Status of spallation neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    Existing and planned facilities using proton accelerator driven spallation neutron source are reviewed. These include new project of neutron science proposed from Japan Atomic Energy Research Institute. The present status of facility requirement and accelerator technology leads us to new era of neutron science such as neutron scattering research and nuclear transmutation study using very intense neutron source. (author)

  1. Neutron radiography using neutron imaging plate.

    Science.gov (United States)

    Chankow, Nares; Punnachaiya, Suvit; Wonglee, Sarinrat

    2010-01-01

    The aims of this research are to study properties of a neutron imaging plate (NIP) and to test it for use in nondestructive testing (NDT) of materials. The experiments were carried out by using a BAS-ND 2040 Fuji NIP and a neutron beam from the Thai Research Reactor TRR-1/M1. The neutron intensity and Cd ratio at the specimen position were approximately 9x10(5) ns/cm(2) s and 100 respectively. It was found that the photostimulated luminescence (PSL) readout of the imaging plate was directly proportional to the exposure time and approximately 40 times faster than the conventional NR using Gd converter screen/X-ray film technique. The sensitivities of the imaging plate to slow neutron and to Ir-192 gamma-rays were found to be approximately 4.2x10(-3) PSL/mm(2) per neutron and 6.7x10(-5) PSL/mm(2) per gamma-ray photon respectively. Finally, some specimens containing light elements were selected to be radiographed with neutrons using the NIP and the Gd converter screen/X-ray film technique. The image quality obtained from the two recording media was found to be comparable. PMID:19828321

  2. Prompt neutron multiplicity distribution for 235U(n,f) at incident energies up to 20 MeV

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-Jing; LIU Ting-Jin

    2011-01-01

    For the n+U fission reaction, the total excitation energy partition of the fission fragments, the average neutron kinetic energy (A) and the total average energies E(A) removed by γ rays as a function of fission fragment mass are given at incident energies up to 20 MeV. The prompt neutron multiplicity as a function of the fragment mass, ν(A), for neutron-induced fission of U at different incident neutron energies is calculated. The calculated results are checked with the total average prompt neutron multiplicities ν and compared with the experimental and evaluated data. Some prompt neutron and γ emission mechanisms are discussed.

  3. Thin Film Polymer Composite Scintillators for Thermal Neutron Detection

    Directory of Open Access Journals (Sweden)

    Andrew N. Mabe

    2013-01-01

    Full Text Available Thin film polystyrene composite scintillators containing LiF6 and organic fluors have been fabricated and tested as thermal neutron detectors. Varying fluorescence emission intensities for different compositions are interpreted in terms of the Beer-Lambert law and indicate that the sensitivity of fluorescent sensors can be improved by incorporating transparent particles with refractive index different than that of the polymer matrix. Compositions and thicknesses were varied to optimize the fluorescence and thermal neutron response and to reduce gamma-ray sensitivity. Neutron detection efficiency and neutron/gamma-ray discrimination are reported herein as functions of composition and thickness. Gamma-ray sensitivity is affected largely by changing thickness and unaffected by the amount of LiF6 in the film. The best neutron/gamma-ray discrimination characteristics are obtained for film thicknesses in the range 25–150 μm.

  4. Observational Constraints on Neutron Star Masses and Radii

    CERN Document Server

    Miller, M Coleman

    2016-01-01

    Precise and reliable measurements of the masses and radii of neutron stars with a variety of masses would provide valuable guidance for improving models of the properties of cold matter with densities above the saturation density of nuclear matter. Several different approaches for measuring the masses and radii of neutron stars have been tried or proposed, including analyzing the X-ray fluxes and spectra of the emission from neutron stars in quiescent low-mass X-ray binary systems and thermonuclear burst sources; fitting the energy-dependent X-ray waveforms of rotation-powered millisecond pulsars, burst oscillations with millisecond periods, and accretion-powered millisecond pulsars; and modeling the gravitational radiation waveforms of coalescing double neutron star and neutron star -- black hole binary systems. We describe the strengths and weaknesses of these approaches, most of which currently have substantial systematic errors, and discuss the prospects for decreasing the systematic errors in each method...

  5. Health physics considerations at a neutron therapy facility cyclotron

    International Nuclear Information System (INIS)

    The U.C.L.A. Neutron Therapy Facility (NTF) is one of four such facilities in the United States currently involved in NCI sponsored trials of neutron therapy and reflects the present interest in the use of high energy neutron beams for treating certain types of human cancers. The NTF houses a CP-45 negative ion cyclotron which accelerates a 46 MeV proton beam for production of neutrons from a beryllium target. In addition to patient treatment, the NTF is involved in the production of positron emitting radioisotopes for diagnostic use in Positron Emission Tomography (PET). The activation of therapy treatment collimators, positron and neutron target systems, and a high and rapidly varying external radiation environment in a clinical setting have contributed to the need for a comprehensive radiation control program in which patient care is balanced with the maintenance of occupational exposures to ALARA levels

  6. Observational constraints on neutron star masses and radii

    International Nuclear Information System (INIS)

    Precise and reliable measurements of the masses and radii of neutron stars with a variety of masses would provide valuable guidance for improving models of the properties of cold matter with densities above the saturation density of nuclear matter. Several different approaches for measuring the masses and radii of neutron stars have been tried or proposed, including analyzing the X-ray fluxes and spectra of the emission from neutron stars in quiescent low-mass X-ray binary systems and thermonuclear burst sources; fitting the energy-dependent X-ray waveforms of rotation-powered millisecond pulsars, burst oscillations with millisecond periods, and accretion-powered millisecond pulsars; and modeling the gravitational radiation waveforms of coalescing double neutron star and neutron star - black hole binary systems. We describe the strengths and weaknesses of these approaches, most of which currently have substantial systematic errors, and discuss the prospects for decreasing the systematic errors in each method. (orig.)

  7. Observational constraints on neutron star masses and radii

    Energy Technology Data Exchange (ETDEWEB)

    Coleman Miller, M. [University of Maryland, Department of Astronomy and Joint Space-Science Institute, College Park, MD (United States); Lamb, Frederick K. [University of Illinois at Urbana-Champaign, Center for Theoretical Astrophysics and Department of Physics, Urbana, IL (United States); University of Illinois at Urbana-Champaign, Department of Astronomy, Urbana, IL (United States)

    2016-03-15

    Precise and reliable measurements of the masses and radii of neutron stars with a variety of masses would provide valuable guidance for improving models of the properties of cold matter with densities above the saturation density of nuclear matter. Several different approaches for measuring the masses and radii of neutron stars have been tried or proposed, including analyzing the X-ray fluxes and spectra of the emission from neutron stars in quiescent low-mass X-ray binary systems and thermonuclear burst sources; fitting the energy-dependent X-ray waveforms of rotation-powered millisecond pulsars, burst oscillations with millisecond periods, and accretion-powered millisecond pulsars; and modeling the gravitational radiation waveforms of coalescing double neutron star and neutron star - black hole binary systems. We describe the strengths and weaknesses of these approaches, most of which currently have substantial systematic errors, and discuss the prospects for decreasing the systematic errors in each method. (orig.)

  8. Biological effects of neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ogiu, Toshiaki; Ohmachi, Yasushi; Ishida, Yuka [National Inst. of Radiological Sciences, Chiba (JP)] [and others

    2003-03-01

    Although the occasion to be exposed to neutrons is rare in our life, except for nuclear accidents like in the critical accident at Tokai-mura in 1999, countermeasures against accident should be always prepared. In the Tokai-mura accident, residents received less than 21 mSv of neutrons and gamma rays. The cancer risks and fetal effects of low doses of neutrons were matters of concern among residents. The purpose of this program is to investigate the relative biological effectiveness (RBE) for leukemias, and thereby to assess risks of neutrons. Animal experiments are planed to obtain the following RBEs: (1) RBE for the induction of leukemias in mice and (2) RBE for effects on fetuses. Cyclotron fast neutrons (10 MeV) and electrostatic accelerator-derived neutrons (2 MeV) are used for exposure in this program. Furthermore, cytological and cytogenetic analyses will be performed. (author)

  9. Neutron sources and applications

    Energy Technology Data Exchange (ETDEWEB)

    Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1994-01-01

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

  10. Neutron sources and applications

    International Nuclear Information System (INIS)

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications

  11. Resonance neutron radiography

    International Nuclear Information System (INIS)

    The production of images by the use of neutrons having energies in the resonance region is described. Two-dimensional position-sensitive neutron detectors are used to produce transmission images using neutron time-of-flight techniques at the National Bureau of Standards' electron linac facility. Two types of detectors are described. The first is a crossed-wire proportional counter using 3He as the neutron-sensitive component. The second type utilizes a multichannel plate electron multiplier and a resistive anode readout. A lithium glass scintillator is the neutron-sensitive component in the latter detector. Resonance neutron radiography, using these detectors, has the capability of producing images with isotopic and chemical element discrimination in a complex matrix with a resolution of 1 mm or better. (Auth.)

  12. HERSCHEL AND SPITZER OBSERVATIONS OF SLOWLY ROTATING, NEARBY ISOLATED NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Posselt, B.; Pavlov, G. G. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Popov, S. [Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Wachter, S., E-mail: posselt@psu.edu [Max Planck Institute for Astronomy, Königsstuhl 17, D-69117 Heidelberg (Germany)

    2014-11-01

    Supernova fallback disks around neutron stars have been suspected to influence the evolution of the diverse neutron star populations. Slowly rotating neutron stars are the most promising places to find such disks. Searching for the cold and warm debris of old fallback disks, we carried out Herschel PACS (70 μm, 160 mu m) and Spitzer IRAC (3.6 μm, 4.5 μm) observations of eight slowly rotating (P ≈ 3-11 s) nearby (<1 kpc) isolated neutron stars. Herschel detected 160 μm emission (>5σ) at locations consistent with the positions of the neutron stars RX J0806.4-4123 and RX J2143.0+0654. No other significant infrared emission was detected from the eight neutron stars. We estimate probabilities of 63%, 33%, and 3% that, respectively, none, one, or both Herschel PACS 160 μm detections are unrelated excess sources due to background source confusion or an interstellar cirrus. If the 160 μm emission is indeed related to cold (10-22 K) dust around the neutron stars, this dust is absorbing and re-emitting ∼10% to ∼20% of the neutron stars' X-rays. Such high efficiencies would be at least three orders of magnitude larger than the efficiencies of debris disks around nondegenerate stars. While thin dusty disks around the neutron stars can be excluded as counterparts of the 160 μm emission, dusty asteroid belts constitute a viable option.

  13. Enhancing the Detector for Advanced Neutron Capture Experiments

    OpenAIRE

    Couture A.; Mosby S.; Baramsai B.; Bredeweg T. A.; Jandel M.; Macon K.; O’Donnell J.M.; Rusev G.; Taddeucci T. N; Ullmann J.L.; Walker C.L.

    2015-01-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detec...

  14. Selection of violent collisions by neutron calorimetry for interferometry measurements

    International Nuclear Information System (INIS)

    Heavy collisions at intermediate energy produce a preequilibrium emission and neutron evaporation. Our work focuses on the conditions to choose to observe mainly light particle correlations coming from heavy equilibrated quasi-projectile nuclei and to sort them in several intervals of violence. We want to demonstrate that one can use a high efficiency 4 pi neutron detector as a calorimeter, and gain in the selectivity on the violence of a collision. (D.L.). 15 refs., 2 figs., 1 tab

  15. Linking electromagnetic and gravitational radiation in coalescing binary neutron stars

    OpenAIRE

    Palenzuela, Carlos; Lehner, Luis; Liebling, Steven L.; Ponce, Marcelo; Anderson, Matthew; Neilsen, David; Motl, Patrick

    2013-01-01

    We expand on our study of the gravitational and electromagnetic emissions from the late stage of an inspiraling neutron star binary as presented in Ref. \\cite{Palenzuela:2013hu}. Interactions between the stellar magnetospheres, driven by the extreme dynamics of the merger, can yield considerable outflows. We study the gravitational and electromagnetic waves produced during the inspiral and merger of a binary neutron star system using a full relativistic, resistive MHD evolution code. We show ...

  16. Demonstration of a single-crystal reflector-filter for enhancing slow neutron beams

    Science.gov (United States)

    Muhrer, G.; Schönfeldt, T.; Iverson, E. B.; Mocko, M.; Baxter, D. V.; Hügle, Th.; Gallmeier, F. X.; Klinkby, E. B.

    2016-09-01

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystal reflector-filter at a reflected neutron source and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. This finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.

  17. Characterization of neutron detectors of B + ZnS (Ag); Caracterizacion de detectores de neutrones de B+ZnS(Ag)

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, J. A.; Suarez, M. J.; Pujol, L.; Lorente, A.; Gallego, E.

    2012-07-01

    The objective is to design prototypes of neutron detection, operating performing dynamic measurements when the sample or the detector is moving. BI-detectors ZnS (Ag) were used, along with other gamma detectors NaI (TL) and PVT, with different configurations, it can detect neutrons and analyzing the number of detections and the energy spectrum of the gamma emissions.

  18. Broadband Neutron Interferometer

    OpenAIRE

    Pushin, Dmitry A.; Sarenac, Dusan; Hussey, Dan; Miao, Houxun; Arif, Muhammad; Cory, David G.; Huber, Michael G.; Jacobson, David; LaManna, Jacob; Parker, Joseph D.; Shinohara, Taken; Ueno, Wakana; Wen, Han

    2016-01-01

    We demonstrate a two phase-grating, multi-beam neutron interferometer by using a modified Ronchi setup in a far-field regime. The functionality of the interferometer is based on the universal \\moire effect that was recently implemented for X-ray phase-contrast imaging in the far-field regime. Interference fringes were achieved with monochromatic, bichromatic, and polychromatic neutron beams; for both continuous and pulsed beams. This far-field neutron interferometry allows for the utilization...

  19. Polysiloxane based neutron detectors

    OpenAIRE

    Dalla Palma, Matteo

    2016-01-01

    In the last decade, neutron detection has been attracting the attention of the scientific community for different reasons. On one side, the increase in the price of 3He, employed in the most efficient and the most widely used neutron detectors. On the other side, the harmfulness of traditional xylene based liquid scintillators, used in extremely large volumes for the detection of fast neutrons. Finally, the demand for most compact and rough systems pushed by the increased popularity of neutro...

  20. Neutron conversion and cascaded cooling in paramagnetic systems for a high-flux source of very cold neutrons

    Science.gov (United States)

    Zimmer, Oliver

    2016-03-01

    A new neutron-cooling mechanism is proposed with potential benefits for novel intense sources of very cold neutrons with wavelengths >2 nm, and for enhancing the production of ultracold neutrons. It employs inelastic magnetic scattering in weakly absorbing, cold paramagnetic systems. Kinetic energy is removed from the neutron stepwise in constant decrements determined by the Zeeman energy of paramagnetic atoms or ions in an external magnetic field, or by zero-field level splittings in magnetic molecules. The stationary neutron transport equation is analyzed for an infinite, homogeneous medium with Maxwellian neutron sources, using inelastic scattering cross sections derived in an appendix. Nonmagnetic inelastic scattering processes are neglected. The solution therefore still underestimates very cold neutron densities that should be achievable in a real medium. Molecular oxygen with its triplet ground state appears particularly promising, notably as a host in fully deuterated O2-clathrate hydrate. Other possibilities are dry O2-4He van der Waals clusters and O2 intercalated in fcc-C60. For conversion of cold to ultracold neutrons, where an incident neutron imparts only a single energy quantum to the medium, the paramagnetic scattering in the clathrate system is found to be stronger, by more than an order of magnitude, than the single-phonon emission in superfluid helium, when evaluated for an incident neutron spectrum with the optimum temperature for the respective medium. Moreover, the multistep paramagnetic cooling cascade leads to further strong enhancements of very cold neutron densities, e.g., by a factor 14 (57) for an initial neutron temperature of 30 K (100 K ), for the moderator held at about 1.3 K . Due to a favorable Bragg cutoff of the O2 clathrate, the cascade-cooling can take effect in a moderator with linear extensions smaller than a meter.