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. Beta delayed alpha emission from the neutron deficient rare earth isotopes 152Tm and 150Ho

    International Nuclear Information System (INIS)

    The study of beta-delayed proton emission is a well known method to aid the determination of the beta strength distribution in nuclei far from the stability line. At the neutron deficient side of the nuclear chart the process of proton or alpha emission from excited states is energetically allowed when one goes far enough from stability. However, beta-delayed alphas have seldom been measured for nuclei heavier than A = 20. Here we present a study of the beta-delayed alpha-particle emission from 152Tm and 150Ho and their importance in the full B(GT) distribution.

  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}-delayed neutron emission measurements around the third r-process abundance peak

    Energy Technology Data Exchange (ETDEWEB)

    Caballero-Folch, R.; Cortes, G.; Calvino, F.; Gomez-Hornillos, M. B.; Riego, A. [INTE-DFEN, Universitat Politecnica de Catalunya, Barcelona (Spain); Domingo-Pardo, C.; Tain, J. L.; Agramunt, J.; Rubio, B. [IFIC, CSIC-University of Valencia, Valencia (Spain); Algora, A. [IFIC, CSIC-University of Valencia, Valencia (Spain) and Inst. Nucl. Research, Debrecen (Hungary); Ameil, F.; Farinon, F.; Heil, M.; Knoebel, R.; Kojouharov, I.; Kurcewicz, J.; Kurz, N.; Litvinov, Y.; Mukha, I.; Nociforo, C. [GSI, Darmstadt (Germany); and others

    2013-06-10

    This contribution summarizes an experiment performed at GSI (Germany) in the neutron-rich region beyond N=126. The aim of this measurement is to provide the nuclear physics input of relevance for r-process model calculations, aiming at a better understanding of the third r-process abundance peak. Many exotic nuclei were measured around {sup 211}Hg and {sup 215}Tl. Final ion identification diagrams are given in this contribution. For most of them, we expect to derive halflives and and {beta}-delayed neutron emission probabilities. The detectors used in this experiment were the Silicon IMplantation and Beta Absorber (SIMBA) detector, based on an array of highly segmented silicon detectors, and the BEta deLayEd Neutron (BELEN) detector, which consisted of 30 3He counters embedded in a polyethylene matrix.

  5. 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

  6. Summary Report of 1st Research Coordination Meeting on Development of Reference Database for Beta-delayed Neutron Emission

    International Nuclear Information System (INIS)

    A summary is given of the 1st Research Coordination Meeting of the new IAEA Coordinated Research Project (CRP) on Development of a Reference Database for Beta-delayed neutron emission data. Participants presented their work, reviewed the current status of the field with regards to individual precursors and aggregate data, and discussed the scope of the work to be undertaken. A list of priorities and task assignments was produced. (author)

  7. 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.

  8. 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.

  9. 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 ...

  10. 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.)

  11. 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.

  12. Statistical effects in beta-delayed neutron emission from fission product nuclides

    International Nuclear Information System (INIS)

    The delayed neutron spectra for the precursors Rb-93, 94, 95, 96, 97 and Cs-145 were measured by use of the on-line isotope separator facility TRISTAN and a time-of-flight (TOF) spectrometer. Flight paths were used that provided, for energies below 70 keV, a FWHM energy resolution between 2 and 4 percent. Each spectrum showed discrete neutron peaks below 156 keV, with as many as 26 in the Rb-95 spectra. Level densities near the neutron binding energy in the neutron-emitting nuclide were deduced using a missing-level indicator based on a Porter-Thomas distribution of neutron peak intensities. The resulting level density data were compared to the predictions of the Gilbert and Cameron formulism and to those of Dilg, Schantl, Vonach and Uhl. Comparisons were made between the empirically-based level parameter a and the values predicted by each model for Sr-93, 94, 95, 97 and Ba-145. The two models appear, within the uncertainties, to be equally capable of describing these neutron-rich nuclides and equally as capable for them as they are for nuclides in the valley of beta stability. Measurements of the neutron strength function are sometimes possible with the present TOF system for neutron decays with competing neutron branches to levels in the grandchild nucleus. A value for the d-wave strength function of Sr-96 is found to be (4.2 +- 1.1)/104. Improvements in the TOF system, allowing the measurement of the neutron strength function for the more general case, are discussed. 72 refs., 56 figs., 16 tabs

  13. 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

  14. 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.

  15. $\\beta$-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.

  16. 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...

  17. Beta-decay half-lives and beta-delayed neutron emission probabilities of nuclei in the region below A=110, relevant for the r-process

    CERN Document Server

    Pereira, J; Aprahamian, A; Arndt, O; Becerril, A; Elliot, T; Estrade, A; Galaviz, D; Kessler, R; Kratz, K -L; Lorusso, G; Mantica, P F; Matos, M; Møller, P; Montes, F; Pfeiffer, B; Schatz, H; Schertz, F; Schnorrenberger, L; Smith, E; Stolz, A; Quinn, M; Walters, W B; Wöhr, A

    2009-01-01

    Measurements of the beta-decay properties of r-process nuclei below A=110 have been completed at the National Superconducting Cyclotron Laboratory, at Michigan State University. Beta-decay half-lives for Y-105, Zr-106,107 and Mo-111, along with beta-delayed neutron emission probabilities of Y-104, Mo-109,110 and upper limits for Y-105, Zr-103,104,105,106,107 and Mo-108,111 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.

  18. Half-lives and branchings for {\\beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process

    CERN Document Server

    Hosmer, P; Aprahamian, A; Arndt, O; Clement, R R C; Estrade, A; Farouqi, K; Kratz, K -L; Liddick, S N; Lisetskiy, A F; Mantica, P F; Möller, P; Mueller, W F; Montes, F; Morton, A C; Ouellette, M; Pellegrini, E; Pereira, J; Pfeiffer, B; Reeder, P; Santi, P; Steiner, M; Stolz, A; Tomlin, B E; Walters, W B; Wöhr, A; 10.1103/PhysRevC.82.025806

    2010-01-01

    The {\\beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {\\beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {\\beta}-delayed neutron emission (Pn values) for 74Co (18 +/- 15%) and 75-77Ni (10 +/- 2.8%, 14 +/- 3.6%, and 30 +/- 24%, respectively) for the first time, and remeasured the Pn values of 77-79Cu, 79,81Zn, and 82Ga. For 77-79Cu and for 81Zn we obtain significantly larger Pn values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of 75Co (30 +/- 11 ms) and 80Cu (170+110 -50 ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is bet...

  19. Beta-delayed neutron decay of $^{33}$Na

    CERN Document Server

    Radivojevic, Z; Caurier, E; Cederkäll, J; Courtin, S; Dessagne, P; Jokinen, A; Knipper, A; Le Scornet, G; Lyapin, V G; Miehé, C; Nowacki, F; Nummela, S; Oinonen, M; Poirier, E; Ramdhane, M; Trzaska, W H; Walter, G; Äystö, J

    2002-01-01

    Beta-delayed neutron decay of /sup 33/Na has been studied using the on-line mass separator ISOLDE. The delayed neutron spectra were measured by time-of-flight technique using fast scintillators. Two main neutron groups at 800(60) and 1020(80) keV were assigned to the /sup 33/Na decay, showing evidence for strong feeding of states at about 4 MeV in /sup 33/Mg. By simultaneous beta - gamma -n counting the delayed neutron emission probabilities P/sub 1n/ = 47(6)% and P /sub 2n/ = 13(3)% were determined. The half-life value for /sup 33 /Na, T/sub 1/2/ = 8.0(3) ms, was measured by three different techniques, one employing identifying gamma transitions and two employing beta and neutron counting. (21 refs).

  20. Evaluation of Beta-Delayed Neutron Emission Probabilities and Half-Lives for Z = 2–28

    Energy Technology Data Exchange (ETDEWEB)

    Birch, M. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Singh, B., E-mail: ndgroup@mcmaster.ca [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Dillmann, I. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Abriola, D. [Department of Physics, TANDAR Laboratory, C.N.E.A., Buenos Aires (Argentina); Johnson, T.D.; McCutchan, E.A.; Sonzogni, A.A. [National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2015-09-15

    We present an evaluation and compilation of β-delayed neutron probabilities and half-lives for nuclei in the region Z = 2–28 ({sup 8}He–{sup 80}Ni). This article includes the recommended values of these quantities as well as a compiled list of experimental measurements for each nucleus in the region for which β-delayed neutron emission is possible. The literature cut-off for this work is August 15{sup th}, 2015. Some notable cases as well as new standards for β-delayed neutron measurements in this mass region are also discussed.

  1. Evaluation of Beta-Delayed Neutron Emission Probabilities and Half-Lives for Z = 2–28

    International Nuclear Information System (INIS)

    We present an evaluation and compilation of β-delayed neutron probabilities and half-lives for nuclei in the region Z = 2–28 (8He–80Ni). This article includes the recommended values of these quantities as well as a compiled list of experimental measurements for each nucleus in the region for which β-delayed neutron emission is possible. The literature cut-off for this work is August 15th, 2015. Some notable cases as well as new standards for β-delayed neutron measurements in this mass region are also discussed

  2. 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...

  3. 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

  4. 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.

  5. Beta-Delayed Neutron Spectroscopy Using VANDLE at CARIBU

    Science.gov (United States)

    Taylor, S.; Kolos, K.; Grzywacz, R.; Paulauskas, S. V.; Madurga, M.; Savard, G.; Brewer, N. T.; Vandle Collaboration

    2015-10-01

    Measurement of spectroscopic information on beta-delayed neutrons of neutron rich fission fragments is of interest to the areas of astrophysics, reactor design, nuclear structure and stockpile stewardship. Using the Time of Flight (TOF) method, the Versatile Array of Neutron Detectors at Low Energy(VANDLE)[1,2,3] measured fission fragments of 252Cf provided by CARIBU at Argonne National Lab. 135,136Sb and 85As isotopes were measured to explore the nuclear structure around doubly magic nuclei 132Sn and 78Ni. A new TOF start detector was developed for this experiment using new Silicon Photo-Multipliers from SensL to allow for a lower beta particle energy detection threshold and better timing resolution compared to previous VANDLE experiments. This work is funded by the U.S. Department of Energy NNSA under the Stewardship Science Academic Alliance program through DOE Cooperative Agreement No. DE-FG52-08NA28552.

  6. Beta-delayed proton emission from 21Mg

    International Nuclear Information System (INIS)

    Beta-delayed proton emission from 21Mg 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 21Mg 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 21Na. An improved interpretation of the decay scheme in accordance with the results obtained in reaction studies is presented. (orig.)

  7. 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.)

  8. 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.

  9. Study of Beta-delayed Neutrons near 78Ni using VANDLE

    Science.gov (United States)

    Paulauskas, S.; Madurga, M.; Grzywacz, R.; Peters, W.; Vandle Collaboration

    2015-10-01

    As nuclei become more neutron rich, the nuclear structure changes their properties. For example, beta decays will access increasingly more neutron unbound states. The measurement of neutrons emitted from these states is critical, as beta-delayed neutron emission becomes a dominating decay mode. To this end, the Versatile Array of Neutron Detectors at Low Energy (VANDLE) measures the energy of neutrons emitted from excited states above the neutron separation energy populated through beta decay or transfer reactions. The time-of-flight technique determines the energy, which requires a time resolution on the order of 1 ns. In addition, the detector requires a low detection threshold to measure neutron energies of 100 keV or lower. A successful experimental campaign at the Holifield Radioactive Ion Beam Facility, using ions produced via proton induced fission on 238U, has yielded results on beta-delayed neutrons emitted from isotopes near 78Ni. Of particular interest, is the observation of low-energy neutrons emitted from states well above the neutron separation energy. Results from this experiment will be presented. This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552 and the Office of Nuclear Physics.

  10. News on $\\beta$-delayed particle emission from $^{14}$Be

    CERN Document Server

    Jeppesen, H; Borge, M J G; Cederkäll, J; Fynbo, H O U; Fedoseyev, V N; Hansper, V Y; Jonson, B; Markenroth, K; Mishin, V I; Nilsson, T; Nyman, G; Riisager, K; Tengblad, O; Wilhelmsen Rolander, K

    2002-01-01

    $\\beta$-delayed charged particles from $^{14}$Be have been measured and give an upper limit on $\\beta$-delayed $\\alpha$-particles of B($\\beta\\alpha$) < $\\,6.7\\times\\!10^{-5}$ and a tentative branching ratio on $\\beta$-delayed tritons of $7.5\\times\\!10^{-5}$ < B($\\beta$t) < $\\,3.9\\times\\!10^{-4}$. We combine the knowledge on $\\beta$-delayed particles from $^{14}$Be to deduce information on the $\\beta$-strength distribution.

  11. $\\beta$-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 [M. Hannawald et al., Phys. Rev. C62, 054301 (2000)] 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 spectrocopic 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.

  12. A Further Measurement of the beta-Delayed alpha-Particle Emission of 16N

    CERN Document Server

    III, R H F; McDonald, J E; Wilds, E L

    2007-01-01

    We measured the beta-delayed alpha-particle emission spectrum of 16N with a sensitivity for beta-decay branching ratios of the order of 10-10. The 16N nuclei were produced using the d(15N,16N)p reaction with 70 MeV 15N beams and a deuterium gas target 7.5 cm long at a pressure of 1250 torr. The 16N nuclei were collected (over 10 s) using a thin aluminum foil with an areal density of 180 mu g/cm2 tilted at 7 Deg with respect to the beam. The activity was transferred to the counting area by means of a stepping motor in less than 3 s with the counting carried out over 8 s. The beta-delayed alpha-particles were measured using a time of flight method to achieve a sufficiently low background. Standard calibration sources (148Gd, 241Am, 208,209Po, and 227Ac) as well as alpha-particles and 7Li from the 10B(n,alpha)7Li reaction were used for an accurate energy calibration. The energy resolution of the catcher foil (180-220 keV) was calculated and the time of flight resolution (3-10 nsec) was measured using the beta-de...

  13. 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.

  14. Search for {beta}-delayed fission of the heavy neutron-rich isotope {sup 230}Ac

    Energy Technology Data Exchange (ETDEWEB)

    Shuanggui Yuan; Weifan Yang; Yanbing Xu; Qiangyan Pan; Bing Xiong; Jianjun He; Dong Wang; Yingjun Li; Taotao Ma; Zhenguo Yang [Academia Sinica, Lanzhou, GS (China). Inst. of Modern Physics

    2001-01-01

    The {sup 230}Ra has been produced via multinucleon transfer reaction and dissipative fragmentation by 60 MeV/u {sup 18}O ion irradiation of {sup 232}Th targets. The radium was radiochemically separated from the mixture of thorium and reaction products. Thin Ra sources were prepared and exposed to the mica fission track detectors, and measured by a HPGe gamma detector. It is likely that the {beta}-delayed fission of {sup 230}Ac was observed for the first time and the {beta}-delayed fission probability of {sup 230}Ac was tentatively found to be (1.19{+-}0.40) x 10{sup -8}. (orig.)

  15. 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.

  16. $\\beta$-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...

  17. $\\beta$-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...

  18. 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.

  19. 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.

  20. Competition of $\\beta$-delayed protons and $\\beta$-delayed $\\gamma$ rays in $^{56}$Zn and the exotic $\\beta$-delayed $\\gamma$-proton decay

    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; 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

    2016-01-01

    Remarkable results have been published recently on the $\\beta$ decay of $^{56}$Zn. In particular, the rare and exotic $\\beta$-delayed $\\gamma$-proton emission has been detected for the first time in the $fp$ shell. Here we focus the discussion on this exotic decay mode and on the observed competition between $\\beta$-delayed protons and $\\beta$-delayed $\\gamma$ rays from the Isobaric Analogue State.

  1. 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.

  2. 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.

  3. The statistical properties of the angular distribution of beta delayed protons from oriented nuclei

    CERN Document Server

    Stone, N J; Wöhr, A

    2000-01-01

    Statistical model of beta -delayed proton emission is briefly reviewed. Theory of angular distribution of beta -delayed proton emission from nuclear states oriented at low temperatures is discussed and the design of the first trial experiment using /sup 118 /Cs oriented at low temperature at the ISOLDE/NICOLE facility at CERN is described. (14 refs).

  4. 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...

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. $\\beta$-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.

  14. Delayed neutron emission probability measurements

    International Nuclear Information System (INIS)

    Some neutrons are emitted from fission fragments several seconds to several minutes after fission occurs. These delayed neutrons play a key role for the conduct and in safety aspects of nuclear reactors [1]. But the probabilities to emit such neutrons (Pn) are not well known. A summary of different database and compilation of Pn values is presented to show these discrepancies and uncertainties. Experiments are carried out at the Lohengrin mass spectrometer (at Inst. Laue Langevin in Grenoble) and at the ISOLDE facility (CERN) in order to measure some Pn values. Two different techniques are used: either by using gamma-rays detection or neutron emission detection. These two techniques and some preliminary results are presented. (authors)

  15. 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)

  16. On the mechanism of fission neutron emission

    International Nuclear Information System (INIS)

    This review represents the present knowledge of the mechanism of prompt fission neutron emission. Starting with a brief fission process characterization related with neutron emission, possible emission mechanisms are discussed. It is emphasized that the experimental study of special mechanisms, i.e. scission neutron emission processes, requires a sufficiently correct description of emission probabilities on the base of the main mechanism, i.e. the evaporation from fully accelerated fragments. Adequate statistical-model approaches have to account for the complexity of nuclear fission reflected by an intricate fragment distribution. The present picture of scission neutron emission is not clarified neither experimentally nor theoretically. Deduced data are contradictory and depend on the used analysis procedures often involving rough discriptions of evaporated-neutron distributions. The contribution of two secondary mechanisms of fission neutron emission, i.e. the neutron evaporation during fragment acceleration and neutron emission due to the decay of 5He after ternary fission, is estimated. We summarize the recent progress of the theoretical description of fission neutron spectra in the framework of statistical models considering the standard spectrum of 252Cf(sf) neutrons especially. The main experimental basis for the study of fission neutron emission is the accurate measurement of emission probabilities as a function of emission energy and angle (at least) as well as fragment parameters (mass number ratio and kinetic energy). The present status is evaluated. (author)

  17. 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.

  18. 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 ...

  19. Scission neutron emission and prompt fission neutron spectrum

    International Nuclear Information System (INIS)

    The mass, energy and angular integrated spectra of prompt fission neutrons for 235U induced fission in the energy range from thermal to 5 MeV were analyzed. It allows assume that about 0.362±0.025 neutrons per fission are emitted due to another mechanism then neutron emission from excited fragments after full acceleration. The spectrum of scission neutrons consists of two components with average energy 0.98 MeV and 2.74 MeV. The share of scission neutrons and their spectrum shape estimated in this work does not contradict to results of differential experiments analyzed in previous papers. (author)

  20. Neutron emission time measurements for ICF targets

    International Nuclear Information System (INIS)

    The neutron emission time for laser-driven inertial confinement fusion targets is determined from data recorded with fast neutron and optical detector systems. Two types of neutron detectors are used. Radiation-induced conductivity devices have a 130-ps FWHM response and are sensitive to targets with yields greater than 5 x 10/sup 10/ DT neutrons. They measure the average neutron emission time with a precision of +- 50 ps and are fast enough to measure the neutron production rate within a target core as a function of time. Plastic scintillators coupled to microchannel-plate photomultiplier tubes have a 1.2-ns FWHM response and measure the average neutron emission time with a precision of +- 75 ps for targets with yields greater than 106 neutrons. Streak cameras record the incident laser power. Optical fiducial signals that are injected into each detector are used to cross time between the detector systems. Measurements made on 1-mm-diam spherical targets irradiated with 23 kJ of 0.35-μm light delivered in a temporally square 1.1-ns pulse and yielding 10/sup 13/ neutrons show a burn duration greater than 300 ps and an average neutron emission time of about 850 ps

  1. 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

  2. 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.

  3. Beta-decay properties of Zr and Mo neutron-rich isotopes

    OpenAIRE

    Sarriguren, P.; Pereira, J

    2010-01-01

    Gamow-Teller strength distributions, beta-decay half-lives, and beta-delayed neutron emission are investigated in neutron-rich Zr and Mo isotopes within a deformed quasiparticle random-phase approximation. The approach is based on a self-consistent Skyrme Hartree-Fock mean field with pairing correlations and residual separable particle-hole and particle-particle forces. Comparison with recent measurements of half-lives stresses the important role that nuclear deformation plays in the descript...

  4. Neutron emission spectroscopy for magnetic confinement experiments

    International Nuclear Information System (INIS)

    Neutron diagnostics for plasmas of tokamaks in measurements of flux and energy distribution (spectrum) of the neutron emission are discussed. Neutron emission spectroscopy (NES) is the most exacting of these diagnostics and the one least developed relative to its potential, instrumentally and functionally. The use and results of NES are reviewed to illustrate NES diagnostic functions from the beginning of fusion research in the 50's to the latest achievements in the sub-ignited plasmas at JET 1997. The advancement of NES diagnostics are projected to the next step experiments planned to be conducted close to ignition at ITER. The potential role of NES to handle several essential diagnostic functions on ITER are compared with the present plans for a neutron diagnostics complement without employment of state-of-the-art spectrometry methods

  5. Prompt neutron emission in nuclear fission

    International Nuclear Information System (INIS)

    Experimental results obtained in recent fragment-neutron correlation measurements are the basis for a detailed analysis of neutron emission characteristics in conjunction with several statistical-model approaches: (i) temperature distribution model (applied calculations), (ii) standard evaporation theory I (Weisskopf-Ewing approach extended by a rough angular momentum correction term), (iii) standard evaporation theory II (Hauser-Feshbach type calculations including angular momentum effects), (iv) statistical multistep compound theory (closed-form description including equilibrium as well as non-equilibrium emissions). All emission models account for an intricate fragment occurrence probability distribution in nucleon numbers, excitation energy, kinetic energy, and (except models (i) and (iv)) angular momentum. They have been used to predict yields, energy and angular distributions as well as representative c.m.s. spectrum shape parameters in the case of 252-Cf spontaneous fission in order to study the mechanisms of prompt fission neutron emission and several features of statistical emission. Model (iv) describes the development of the fragment compound system as a stochastic process starting at scission point and, hence, considering emission processes during fragment acceleration. The results of all model calculations indicate a clear predominance of the evaporation mechanism. The possible role of secondary mechanisms and difficulties in deducing information about them are discussed. The present paper gives a review on all four models. Results obtained within standard evaporation theory II (full-scale Hauser-Feshbach calculation) are discussed in more detail. (author). 27 refs, 4 figs

  6. 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

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

    Science.gov (United States)

    Rusev, G.; Baramsai, B.; Bond, E. M.; Jandel, M.

    2016-05-01

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

  8. 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.

  9. Theoretical descriptions of neutron emission in fission

    International Nuclear Information System (INIS)

    Brief descriptions are given of the observables in neutron emission in fission together with early theoretical representations of two of these observables, namely, the prompt fission neutron spectrum N(E) and the average prompt neutron multiplicity bar νp. This is followed by summaries, together with examples, of modern approaches to the calculation of these two quantities. Here, emphasis is placed upon the predictability and accuracy of the new approaches. In particular, the dependencies of N(E) and bar νp upon the fissioning nucleus and its excitation energy are discussed. Then, recent work in multiple-chance fission and other recent work involving new measurements are presented and discussed. Following this, some properties of fission fragments are mentioned that must be better known and better understood in order to calculate N(E) and bar νp with higher accuracy than is currently possible. In conclusion, some measurements are recommended for the purpose of benchmarking simultaneous calculations of neutron emission and gamma emission in fission. 32 refs., 26 figs

  10. 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

  11. 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

  12. 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.

  13. 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...

  14. Prompt fission neutron emission: Problems and challenges

    Directory of Open Access Journals (Sweden)

    Hambsch F.-J.

    2013-12-01

    Full Text Available This paper presents some of the challenges ahead of us even after 75 years of the discovery of the fission process and large progress made since then. The focus is on application orientation, which requires improved measurements on fission cross-sections and neutron and γ-ray multiplicities. Experimental possibilities have vastly improved the past decade leading to developments of highly sophisticated detector systems and the use of digital data acquisition and signal processing. The development of innovative fast nuclear reactor technology needs improved respective nuclear data. Advancements in theoretical modelling also require better experimental data. Theory has made progress in calculating fission fragment distributions (i.e. GEF code as well as prompt neutron and γ-ray emission to catch up with the improved experiments.

  15. Neutron emissivity profile camera diagnostics considering present and future tokamaks

    International Nuclear Information System (INIS)

    This thesis describes the neutron profile camera situated at JET. The profile camera is one of the most important neutron emission diagnostic devices operating at JET. It gives useful information of the total neutron yield rate but also about the neutron emissivity distribution. Data analysis was performed in order to compare three different calibration methods. The data was collected from the deuterium campaign, C4, in the beginning of 2001. The thesis also includes a section about the implication of a neutron profile camera for ITER, where the issue regarding interface difficulties is in focus. The ITER JCT (Joint Central Team) proposal of a neutron camera for ITER is studied in some detail

  16. 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...

  17. 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 $v_F$ ...

  18. 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.

  19. Fine structure in the beta-delayed proton decay of 33Ar

    International Nuclear Information System (INIS)

    Low-energy beta-delayed protons from 33Ar have been measured for the first time. The data reveal states, which, despite unfavourable barrier penetrability values, strongly decay to the first excited 2+ state in 32S. The observation is discussed in terms of the standard shell model. A natural explanation is provided by the large spectroscopic amplitudes, involving s1/2 and d3/2 orbitals, as well as the l=0 barrier penetrability, favouring the decay to the 2+ state. (orig.)

  20. 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)

  1. 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)

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

    OpenAIRE

    Ghys, Lars; Andreyev, A.N.; Antalic, S; Huyse, Mark; Van Duppen, Piet

    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 de...

  3. 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.

  4. 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.

  5. 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...

  6. 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

  7. 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 ...

  8. Neutron emission profiles and energy spectra measurements at JET

    Energy Technology Data Exchange (ETDEWEB)

    Giacomelli, L. [JET-EFDA, Culham Science Centre, Abingdon, 0X14 3DB, United Kingdom and Department of Physics, Università degli Studi di Milano-Bicocca, Milano (Italy); Conroy, S. [JET-EFDA, Culham Science Centre, Abingdon, 0X14 3DB, United Kingdom and Department of Physics and Astronomy, Uppsala University, Uppsala (Sweden); Belli, F.; Riva, M. [Associazione EURATOM-ENEA sulla Fusione, Roma (Italy); Gorini, G. [Department of Physics, Università degli Studi di Milano-Bicocca, Milano, Italy and Istituto di Física del Plasma Piero Caldirola, Milan (Italy); Horton, L.; Joffrin, E.; Lerche, E.; Murari, A.; Popovichev, S.; Syme, B. [JET-EFDA, Culham Science Centre, Abingdon, 0X14 3DB (United Kingdom); Collaboration: JET EFDA Contributors

    2014-08-21

    The Joint European Toras (JET, Culham, UK) is the largest tokamak in the world. It is devoted to nuclear fusion experiments of magnetic confined Deuterium (D) or Deuterium-Tritium (DT) plasmas. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). JET makes use of many different diagnostics to measure the physical quantities of interest in plasma experiments. Concerning D or DT plasmas neutron production, various types of detectors are implemented to provide information upon the neutron total yield, emission profile and energy spectrum. The neutron emission profile emitted from the JET plasma poloidal section is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system capable of high rate neutron measurements (<0.5 MCps). A similar instrument will be implemented on ITER and it is currently in its design phase. Various types of neutron spectrometers with different view lines are also operational on JET. One of them is a new compact spectrometer (KM12) based on organic liquid scintillating material which was installed in 2010 and implements a similar digital data acquisition system as for KN3. This article illustrates the measurement results of KN3 neutron emission profiles and KM 12 neutron energy spectra from the latest JET D experimental campaign C31.

  9. Neutron emission profiles and energy spectra measurements at JET

    Science.gov (United States)

    Giacomelli, L.; Conroy, S.; Belli, F.; Gorini, G.; Horton, L.; Joffrin, E.; Lerche, E.; Murari, A.; Popovichev, S.; Riva, M.; Syme, B.; JET EFDA Contributors

    2014-08-01

    The Joint European Toras (JET, Culham, UK) is the largest tokamak in the world. It is devoted to nuclear fusion experiments of magnetic confined Deuterium (D) or Deuterium-Tritium (DT) plasmas. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). JET makes use of many different diagnostics to measure the physical quantities of interest in plasma experiments. Concerning D or DT plasmas neutron production, various types of detectors are implemented to provide information upon the neutron total yield, emission profile and energy spectrum. The neutron emission profile emitted from the JET plasma poloidal section is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system capable of high rate neutron measurements (<0.5 MCps). A similar instrument will be implemented on ITER and it is currently in its design phase. Various types of neutron spectrometers with different view lines are also operational on JET. One of them is a new compact spectrometer (KM12) based on organic liquid scintillating material which was installed in 2010 and implements a similar digital data acquisition system as for KN3. This article illustrates the measurement results of KN3 neutron emission profiles and KM 12 neutron energy spectra from the latest JET D experimental campaign C31.

  10. $^{11}$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.

  11. Beta-decay properties of Zr and Mo neutron-rich isotopes

    CERN Document Server

    Sarriguren, P

    2010-01-01

    Gamow-Teller strength distributions, beta-decay half-lives, and beta-delayed neutron emission are investigated in neutron-rich Zr and Mo isotopes within a deformed quasiparticle random-phase approximation. The approach is based on a self-consistent Skyrme Hartree-Fock mean field with pairing correlations and residual separable particle-hole and particle-particle forces. Comparison with recent measurements of half-lives stresses the important role that nuclear deformation plays in the description of beta-decay properties in this mass region.

  12. 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

  13. Prompt-Neutron Emission from U235 Fission Fragments

    International Nuclear Information System (INIS)

    A gadolinium-loaded large liquid scintillation counter is being used in conjunction with a neutron beam from the HERALD reactor at the Atomic Weapons Research Establishment, Aldermaston, to study neutron emission in the fission process. In particular, the neutron emission from individual fission fragments is observed. A fission-fragment detector comprising two gold-silicon suríace barrier counters operating in coincidence is situated at the edge of a 1-m-diam. spherical scintillation tank. The solid-state counters are placed on opposite sides of an evaporated fissile deposit on a thin nickel backing. A system of collimators selects for measurement only those fission events that have fragments travelling in the direction along the incident neutron beam and along the axis of the scintillator. Numbers of neutrons detected within 10 ps of a fission event are recorded. The angular correlation of neutron emission with fragment direction is used to associate the neutrons with the particular fission fragment that emitted them. Energies of both fragments are available from the solid-state counters, and identification of fragment mass and of the total kinetic energy of the fragment pair is made. The number of neutrons emitted by each fragment of the pair has been measured as a function of both the fragment mass and the total kinetic energy of the pair for thermal neutrons incident on U2'35. The usual asymmetry in the distribution of excitation energy between the heavy and light fragments is observed. The variation of the number of neutrons from the pair as a function of mass ratio is also determined. (author)

  14. Prompt Fission Neutron Emission in Resonance Fission of 239Pu

    Science.gov (United States)

    Hambsch, Franz-Josef; Varapai, Natallia; Zeinalov, Shakir; Oberstedt, Stephan; Serot, Olivier

    2005-05-01

    The prompt neutron emission probability from neutron-induced fission in the resonance region is being investigated at the time-of-flight facility GELINA of the IRMM. A double Frisch-gridded ionization chamber is used as a fission-fragment detector. For the data acquisition of both the fission-fragment signals as well as the neutron detector signals the fast digitization technique has been applied. For the neutron detection, large-volume liquid scintillation detectors from the DEMON collaboration are used. A specialized data analysis program taking advantage of the digital filtering technique has been developed to treat the acquired data. Neutron multiplicity investigations for actinides, especially in resonance neutron-induced fission, are rather scarce. They are, however, important for reactor control and safety issues as well as for understanding the basic physics of the fission process. Fission yield measurements on both 235U and 239Pu without prompt neutron emission coincidence have shown that fluctuation of the fission-fragment mass distribution exists from resonance to resonance, larger in the case of 235U. To possibly explain these observations, the question now is whether the prompt neutron multiplicity shows similar fluctuations with resonance energy.

  15. Measurement of the branching ratio for beta-delayed alpha decay of 16N

    CERN Document Server

    Refsgaard, J; Dijck, E A; Fynbo, H O U; Lund, M V; Portela, M N; Raabe, R; Randisi, G; Renzi, F; Sambi, S; Sytema, A; Willmann, L; Wilschut, H W

    2015-01-01

    While the 12C(a,g)16O reaction plays a central role in nuclear astrophysics, the cross section at energies relevant to hydrostatic helium burning is too small to be directly measured in the laboratory. The beta-delayed alpha spectrum of 16N can be used to constrain the extrapolation of the E1 component of the S-factor; however, with this approach the resulting S-factor becomes strongly correlated with the assumed beta-alpha branching ratio. We have remeasured the beta-alpha branching ratio by implanting 16N ions in a segmented Si detector and counting the number of beta-alpha decays relative to the number of implantations. Our result, 1.49(5)e-5, represents a 25% increase compared to the accepted value and implies an increase of 14% in the extrapolated S-factor.

  16. Neutron emission from primary fragments and mass determination

    International Nuclear Information System (INIS)

    In the frame of statistical model with preequilibrium contribution a probability of prompt neutron emission from primary fission fragments has been calculated. The calculation of yields of primary f.f. from experimental values of relevant yields has been performed using these probabilities. An influence of using post-neutron experimental yield of f.f.'s on the determination of mass distribution of primary f.f.'s has been discussed. (orig.)

  17. 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.

  18. Imaging special nuclear material with muon-induced neutron emission.

    Science.gov (United States)

    Durham, J. Matthew

    2015-10-01

    Cosmic ray muons are a ubiquitous source of energetic charged particles that can be used to image high-Z material through significant amounts of shielding. Negative muons which come to rest inside fissile material can be captured into atomic orbitals and induce fission, which may lead to detectable neutron emission. Muon tracks that are correlated with neutron emission can therefore serve as a signal for the presence of fissile material, and laminography with the tagged muon tracks can be performed to produce an image of the neutron emission source. In this presentation, we will discuss results of imaging tests using this technique at Los Alamos National Laboratory, and possible applications in treaty verification.

  19. 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 ...

  20. Prompt fission neutron emission in resonance fission of 239Pu

    International Nuclear Information System (INIS)

    The prompt fission neutron emission probability was investigated at the time-of-flight facility GELINA at the IRMM. A double Frisch-gridded ionization chamber was used as a fission fragment detector. For the data acquisition of both fission fragment signals as well as the neutron detector signals the fast digitization technique has been applied. For the neutron detection large volume liquid scintillation detectors from the DEMON collaboration were used. A specialized data analysis program taking advantage of the digital filtering technique has been developed to treat the acquired data

  1. 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

  2. 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.

  3. 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)

  4. Neutron and x-ray emission time measurements

    International Nuclear Information System (INIS)

    Laser fusion targets can produce implosions with a delay between the peak compression (neutron emission) and the laser pulse on the order of 0.2 to 2.5 ns. We use a fast detector system to measure x-ray and D-T neutron emission times with a resolution of 100 to 200 ps. An NE111 fluor (quenched with 2% benzophenone) coupled to a microchannel plate photomultiplier tube detects the arrival of neutrons and x rays. A separate biplanar vacuum photodiode detects the arrival of unabsorbed laser light scattered from the target. These signals are mixed, then recorded on a 500 MHz transient digitizer. The discussion includes a description of the time interval system, experimental data, data analysis techniques, and system calibration

  5. 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.

  6. Development of the new trigger for VANDLE neutron detector

    Science.gov (United States)

    Hasse, Adam; Taylor, Steven; Daugherty, Hadyn; Grzywacz, Robert

    2014-09-01

    Beta-delayed neutron emission (βn) is the dominant decay channel for the majority of very neutron-rich nuclei. In order to study these decays a new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed. A critical part of this neutron time of flight detector is a trigger unit. This trigger is sensitive to electron from beta decay down to very low energies, insensitive to gamma rays and have a good timing performance, better than 1 ns. In order to satisfy these condition, we have developed a new system, which utilizes plastic scintillator but uses recently developed light readout technique, based on the so called Silicon Photomultiplier, manufactured by Sensl. New system has been developed and performance tested using digital data acquisition system at the University of Tennessee and will be utilized in future experiments involving VANDLE. Beta-delayed neutron emission (βn) is the dominant decay channel for the majority of very neutron-rich nuclei. In order to study these decays a new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed. A critical part of this neutron time of flight detector is a trigger unit. This trigger is sensitive to electron from beta decay down to very low energies, insensitive to gamma rays and have a good timing performance, better than 1 ns. In order to satisfy these condition, we have developed a new system, which utilizes plastic scintillator but uses recently developed light readout technique, based on the so called Silicon Photomultiplier, manufactured by Sensl. New system has been developed and performance tested using digital data acquisition system at the University of Tennessee and will be utilized in future experiments involving VANDLE. Department of Physics and Astronomy, University of Tennessee, Knoxville, USA.

  7. 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).

  8. 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.

  9. $\\beta$-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...

  10. 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...

  11. The Beta-Delayed Proton and Gamma Decay of 27P for Nuclear Astrophysics

    Science.gov (United States)

    Simmons, E.; Trache, L.; Banu, A.; McCleskey, M.; Roeder, B.; Spiridon, A.; Tribble, R. E.; Davinson, T.; Woods, P. J.; Lotay, G. J.; Wallace, J.; Doherty, D.; Saastamoinen, A.

    2013-03-01

    The creation site of 26Al is still under debate. It is thought to be produced in hydrogen burning and in explosive helium burning in novae and supernovae, and possibly also in the H-burning in outer shells of red giant stars. Also, the reactions for its creation or destruction are not completely known. When 26Al is created in novae, the reaction chain is: 24Mg(p,γ)25AI(β+v)25 Mg(p,γ)26Al, but this chain can be by-passed by another chain, 25Al(p, γ)26Si(p, γ)27P and it can also be destroyed directly. The reaction 26m Al (p, γ)27 Si* is another avenue to bypass the production of 26Al and it is dominated by resonant capture. We find and study these resonances by an indirect method, through the beta-decay of 27P. A clean and abundant source of 27P was produced for the first time and separated with MARS. A new implantation-decay station which allows increased efficiency for low energy protons and for high-energy gamma-rays was used. We measured gamma-rays and beta-delayed protons emitted from states above the proton threshold in the daughter nucleus 27Si to identify and characterize the resonances. The lifetime of 27P was also measured with accuracy under 2%.

  12. 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

  13. 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.

  14. The rp-process and new measurements of $\\beta$-delayed proton decay of light Ag and Cd isotopes

    CERN Document Server

    Raimann, G; Boyd, R N; Cano-Ott, D; Collatz, R; Guglielmetti, A; Hellström, M; Hencheck, M; Hu, Z; Janas, Z; Karny, M; Kirchner, R; Morford, L J; Morrissey, D J; Roeckl, E; Schmidt, K; Szerypo, J; Weber, A

    1996-01-01

    Recent network calculations suggest that a high temperature rp-process could explain the abundances of light Mo and Ru isotopes, which have long challenged models of p-process nuclide production. Important ingredients to network calculations involving unstable nuclei near and at the proton drip line are \\beta-halflives and decay modes, i.e., whether or not \\beta-delayed proton decay takes place. Of particular importance to these network calculation are the proton-rich isotopes ^{96}Ag, ^{98}Ag, ^{96}Cd and ^{98}Cd. We report on recent measurements of \\beta-delayed proton branching ratios for ^{96}Ag, ^{98}Ag, and ^{98}Cd at the on-line mass separator at GSI.

  15. $\\beta$-delayed $\\gamma$-proton decay in $^{56}$Zn: analysis of the charged-particle spectrum

    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; 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 study of the $\\beta$ decay of the proton-rich $T_{z}$ = -2 nucleus $^{56}$Zn has been reported in a recent publication. A rare and exotic decay mode, $\\beta$-delayed $\\gamma$-proton decay, has been observed there for the first time in the $fp$ shell. Here we expand on some of the details of the data analysis, focussing on the charged particle spectrum.

  16. 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...

  17. Prompt Neutron Emission in 252CF Spontaneous Fission

    Science.gov (United States)

    Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

    2011-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  18. Neutron emission in fission of 252Cf(sf)

    Science.gov (United States)

    Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.; Fabry, I.

    2009-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results of this digital data acquisition and digital signal processing analysis to the results of the pioneering work of Budtz-Jo/rgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213 equivalent neutron detector in total about 10 neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution have been investigated using a 10 bit waveform digitizer. Neutron time- of- flight and pulse shape have been measured using analogue CAMAC modules, a 1 ns TDC and a pair of 12 bit charge-to-digital-converters. The fission fragment signals have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of neutrons as a function of total kinetic energy (TKE) of the fragments does not drop at low TKE.

  19. 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.

  20. 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.

  1. Neutron emission from impacted solid LiD samples

    International Nuclear Information System (INIS)

    Nylon projectiles with 0.1 g to 0.3 g mass, accelerated to velocities of 0.2-1 km/s using a 60 cm long electromagnetic accelerator (railgun), have been impacted upon solid lithium deuteride (LiD) samples of 3 proportional counters. The output from the BF3 set-up is monitored in several ways to characterize the possible neutron emission from the target. This includes a simple technique of counting the single channel analyser (SCA) output through a dead-time unit to identify bursts of < 100 μs duration. Counting is started after a delay of ∼ 1 ms to avoid the initial interference from the capacitor bank discharge. The signal is also recorded in a storage oscilloscope from the start of projectile acceleration along with a time marker just before the impact. From a number of shots taken with and without the samples, a significant evidence of neutron emission from the LiD samples appears to emerge. The experiments suggest that approximately 100 neutrons might be generated during every such impact in a duration of < 4 ms. (author). 7 refs., 3 figs

  2. 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

  3. 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.

  4. Importance of 5He emission in neutron induced reactions

    International Nuclear Information System (INIS)

    An important particle emission of 5He has never been included in the widely used statistical model codes as the evaluation tool. The threshold energies from light nuclei to heavy nuclei are given, which indicate that in general the compound nucleus induced by incident neutron would emit 5He rather than 3He. Being 5He unstable and separated into n + α spontaneously, the formulation of the double-differential cross section of the neutron from the 5He two-body breakup process is given. Because of stronger recoil effect than the other outgoing particles, the energy balance is strictly taken into account. The further improvement for the model calculation on this respect is proposed

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

    CERN Document Server

    Taverna, Roberto; Caniulef, Denis Gonzalez; Zane, Silvia; Muleri, Fabio; Soffitta, Paolo

    2015-01-01

    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 appear particularly suited for polarization measurements. Radiation from the (cooling) surface of a neutron star is expected to exhibit a large intrinsic polarization degree due to the star strong magnetic field ($\\approx 10^{12}-10^{15}$ G), which influences the plasma opacity in the outermost stellar layers. The polarization fraction and polarization angle as measured by an instrument, however, do not necessary coincide with the intrinsic ones derived from models of surface emission. This is due to the effects of quantum electrodynamics in the highly magnetized vacuum around the star (the vacuum polarization) coupled with the rotation of the Stokes parameters in the plane perpendicular to the line of sight induced by the non-uniform magnetic field. Here we revisit the problem and present an efficient method for computing the observed polariza...

  6. Post-irradiation neutron emissions from CANDU fuels and their nuclear forensics applications

    International Nuclear Information System (INIS)

    Fissile materials within a fuel pellet can be discerned rapidly and non-destructively via the analysis of post-irradiation delayed neutron emissions. The delayed neutron counting technique is well established within the Canadian nuclear industry, and uses include the detection of defective CANDU fuel. This work discusses these neutron emissions from CANDU fuel in the context of detection and attribution. Monte Carlo simulations of these emissions from current and proposed CANDU fuels (thoria and mix oxide based) have been performed. These simulations are compared to measurements of delayed neutron emissions from 233U and 235U, and the feasibility of CANDU fuel characterization is discussed. (author)

  7. 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...

  8. Quiescent thermal emission from neutron stars in LMXBs

    CERN Document Server

    Turlione, Anabela; Pons, José A

    2013-01-01

    The quiescent thermal emission from neutron stars in low mass X-ray binaries after active periods of intense activity in x-rays (outbursts) has been monitored. The theoretical modeling of the thermal relaxation of the neutron star crust may be used to establish constraints on the crust and envelope composition and transport properties, depending on the astrophysical scenarios assumed. We perform numerical simulations of the neutron star crust thermal evolution and compare them with inferred surface temperatures for five sources: MXB 1659-29, KS 1731-260, EXO 0748-676, XTE J1701-462 and IGR J17480-2446. We also present stationary envelope models to be used as a boundary condition for the crustal cooling models. We obtain a relation between the mass accretion rate and the temperature reached at the crust-envelope interface at the end of the active phase that accounts for early observations and reduces the number of free parameters of the problem. With this relation we are also able to set constraints to the env...

  9. Beamed neutron emission driven by laser accelerated light ions

    Science.gov (United States)

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

    2016-05-01

    Highly anisotropic, beam-like neutron emission with peak flux of the order of 109 n/sr was obtained from light nuclei reactions in a pitcher–catcher scenario, by employing MeV ions driven by a sub-petawatt 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^\\circ , 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 is most likely related to the directionality and high energy of the projectile ions.

  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. Emission of delayed neutrons: calculation of the energy spectra and emission probabilities of the precursors

    International Nuclear Information System (INIS)

    The calculations given in the paper are intended to explain the delayed neutron emission (energy spectra and emission probabilities Pn) which follows the β- disintegration of the precursors produced by fission. The probability of β- transition, the level density ω (E, J) of the emitter and the competition (β-, γ) and (β-, n) de-energizations are analysed for each precursor studied. All the possible channels open to the process of neutron emission on grounds of energy considerations (Qβ-, Bn) are taken into account through the introduction of the spin and parity selection rules at each stage of the sequence: precursor, emitter, final nucleus. The results of the calculations are compared with the known experimental measurements of the neutron energy spectra and probabilities Pn. The precursors 87Br, 88Br, 137I and 93-97Rb were selected for this examination. This comparison shows in particular that the structure of experimental energy spectra can be well reproduced by the calculations given in the paper. Moreover, it emerges that the spectra calculated are very sensitive to the choice of the spins of the precursor and the final nucleus. (author)

  12. Neutron Capture Cross Sections for Radioactive Nuclei

    Science.gov (United States)

    Tonchev, Anton; Bedrossian, Peter; Escher, Jutta; Scielzo, Nicholas

    2015-10-01

    Accurate neutron-capture cross sections for radioactive nuclei near or far away from the line of beta stability are crucial for understanding the nucleosynthesis of heavy elements. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining observables that can constrain Hauser-Feshbach statistical model calculations of capture cross sections. Specifically, we will consider photon scattering, transfer reactions, and beta-delayed neutron emission. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes far from stability will be discussed. This work was performed under the auspices of US DOE by LLNL under contract DE-AC52-07NA27344. Funding was provided via the LDRD-ERD-069 project.

  13. Application of nuclear emulsion to neutron emission profile diagnostics in the national spherical torus experiment

    International Nuclear Information System (INIS)

    The technology for OPERA experiments in neutrino physics was applied to neutral-beam-heated deuterium discharges of NSTX in order to measure d-d neutron emission profile. The diagnostic system consisted of nuclear emulsions named OPERA films and the automatic track scanning system S-UTS developed in Nagoya University. A neutron collimator having three channels was temporarily built for this purpose. The nuclear emulsion indicated peaked neutron emission profiles at the plasma center in NSTX as expected. (author)

  14. 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.

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

    OpenAIRE

    Göök Alf; Hambsch Franz-Josef; Oberstedt Stephan

    2016-01-01

    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 ...

  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. Library of prompt neutron and γ-emission spectra from fission fragments

    International Nuclear Information System (INIS)

    The statistical model of nuclear reactions is applied to describe the fission fragment neutron and gamma emission characteristics for spontaneous fission of 252Cf and for fission of 233,235U, 239Pu by thermal neutrons. The calculations of neutron and gamma-spectra are carried out for the fragments with A=70-160, excited up to 100 MeV. After testing of the model and input data library, calculations of neutron and γ-emission spectra for nuclei with A=70-170 excited up to 100 MeV were done to produce the Fission Fragments Emission Spectra Library (FFESL). FFESL contains the data of 1000 nuclei and will be used in calculations of neutron and γ-spectra for fission of heavy nuclei by intermediate energy nucleons. (author)

  19. 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.

  20. 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.

  1. $\\beta$-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.

  2. Monte Carlo Simulation of Prompt Neutron Emission During Acceleration of Fission Fragments

    International Nuclear Information System (INIS)

    Possible reasons for apparent discrepancy in the prompt fission neutron spectra (PFNS) in the low-energy region, say <0.5 MeV, have been discussed. There are five possibilities: (1) uncertainty in the measured data in the low energy region, (2) neutron emission during acceleration (NEDA), instead of after full acceleration, (3) angular anisotropy in neutron emission in the CM-system of fission fragments (FF), (4) possible effect of 'yrast levels', and (5) possible existence of scission neutrons. In this report we examined the possibility (2) and (3) as well. It has been considered that the most of the prompt fission neutrons are emitted after full acceleration of fission fragments due to rapid acceleration by strong Coulomb repulsion working between them. On the other hand, however, there has also been a discussion on a possibility of neutron emission during acceleration. This phenomenon is interesting from physics point of view, as it provides knowledge on the timescale of de-excitation of excited nuclei and on possible competition with the Coulomb acceleration of FFs. It is also interesting from application point of view, since neutron emission from FFs before full acceleration implies an enhancement of low-energy component of the PFNS, because the NEDA neutrons receive smaller linear momentum from the FF. This possibility was examined by using Monte Carlo simulation

  3. 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.)

  4. Effects of Neutron Emission on Fragment Mass and Kinetic Energy Distribution from Thermal Neutron-Induced Fission of 235U

    International Nuclear Information System (INIS)

    The mass and kinetic energy distribution of nuclear fragments from thermal neutron-induced fission of 235U(nth,f) have been studied using a Monte-Carlo simulation. Besides reproducing the pronounced broadening in the standard deviation of the kinetic energy at the final fragment mass number around m = 109, our simulation also produces a second broadening around m = 125. These results are in good agreement with the experimental data obtained by Belhafaf et al. and other results on yield of mass. We conclude that the obtained results are a consequence of the characteristics of the neutron emission, the sharp variation in the primary fragment kinetic energy and mass yield curves. We show that because neutron emission is hazardous to make any conclusion on primary quantities distribution of fragments from experimental results on final quantities distributions

  5. 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...

  6. 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.

  7. 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

  8. 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 ...

  9. Beta-delayed proton emission: a new series of precursors and the measurement of 10-16 s nuclear lifetimes

    International Nuclear Information System (INIS)

    We have now obtained results on a new series of even-Z precursors with Tsub(z) = +1/2. Like all known heavy precursors, the nuclei so far identified - 65Ge, 69Se, 73Kr, 77Sr, 81Zr and provisionally 85Mo - exhibit broad proton continua. However, the availability of such a series of nuclei makes it possible to extract a systematic picture of the beta-decay strength function as well as level densities, widths and decay energies from the observed spectra. By the addition of a new experimental technique we have also been able to determine the absolute values of the widths through direct measurement of the average lifetime of states populated in the emitter. These data all provide stringent tests of model calculations and mass formulae in a region of nuclei with N approximately Z, far removed from the valley of stability. (author)

  10. Absolute measurement of neutron source emission rate with manganese bath method

    International Nuclear Information System (INIS)

    The manganese bath method is one of the most widespread and exact method to measure neutron source emission rate (neutron source intensity) absolutely at present. Pouring some 56Mn solution with known activity into the bath, the system efficiency can be obtained from γ counts of 56Mn, which is measured by two NaI(Tl) detectors. From saturated counts of a 241Am-Be(α, n) neutron source in the bath, the source emission rate can be obtained. An standard 241Am-Be(α, n) source which is the transfer source of the CCRI(Ⅲ)-K9. AmBe international key comparison organized by the Comite Consultatif des Rayonnements Ionisants, was measured absolutely with the neutron source emission rate standard equipment (manganese bath method). The result is coincident with the average value of the comparison within the uncertainties, therefore the reliability of the standard equipment is verified. (authors)

  11. 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.

  12. Studies of photonuclear neutron emission during the start-up phase of the Alcator C tokamak

    International Nuclear Information System (INIS)

    Alcator C operations commenced with discharge cleaning and tokamak operation using hydrogen filling gas. Prior to and during these experiments no deuterium gas was allowed into the device. The earliest operation resulted in dosimeter readings of a few Roentgen per shot in the vicinity of the limiter and a localized source of neutron emission of up to 109 neutrons/shot. A strong correlation of the neutron emissions with hard x-ray emissions from the limiter and nonthermal features on the synchrotron emissions was observed during these discharges. Gamma energy spectroscopy of the activated limiter after removal from Alcator allowed identification of 16 radioisotopes which were consistent with photonuclear processes (γ,n , γ,p , γ,α reactions) arising in the limiter. After seven months of hydrogen operation conditions were achieved that resulted in substantially less non-thermal activity. Typical neutron emission rates of equal to or less than 106 n/sec were observed, i.e., about four orders of magnitude less than the expected D-D thermonuclear neutron emission rates for the same type of discharge if D2 was used as the filling gas

  13. Neutron emission profile measurements during the first tritium experiments at JET

    International Nuclear Information System (INIS)

    During a series of experiments with tritium (T) in deuterium (D) plasmas in the Joint European Torus (JET), the temporal evolution and the two dimensional (2-D) spatial profiles of the 2.5 and 14 MeV neutron emissivities from D-D and D-T fusion reactions were inferred from measurements with the JET neutron emission profile monitor. These experiments, involving triton production from D-D fusion, beam deposition and diffusion, D-T fusion, and tritium removed from wall tiles, were investigated in four plasma scenarios: (i) In high performance deuterium plasmas with deuterium neutral beam injection, the 14 MeV neutron emissivity due to triton burnup was observed. (ii) In discharges with 1% tritium beam injection, neutron emissivity ratios showed that approximately the same deposition profiles resulted from tritium as from deuterium beams. A thermalized tritium diffusion experiment was performed in which the T-D density ratio was found to be spatially constant across the plasma; in conjunction with similar particle source profiles, this indicates that deuterium and tritium have similar particle transport properties. (iii) In two high performance discharges for which two of the sixteen neutral beam sources operated with 100% tritium, the production rate of 14 MeV neutrons reached 6 x 1017 n·s-1. The α particle 2-D birth profile was directly inferred from the measured 14 MeV neutron emissivity profile. Both the axial 14 MeV neutron emissivity and the axial ion temperature saturated before the maximum global emission was reached. (iv) During the tritium cleanup phase, residual tritium entering the plasma produced a spatially constant ratio of tritium to deuterium, confirming the similarity of their particle transport properties. (author). 27 refs, 13 figs, 3 tabs

  14. Neutron emission from the ''UTRO'' pulsed thermonuclear device

    International Nuclear Information System (INIS)

    Technique of investigations into neutron radiation in experiments on low-compression heating of dense plasma in the UTRO linear theta-pinch with a strong (B7 neutr/pulse. Dependence of neutron pulse duration on initial deuterium pressure in a discharge chamber in the range of 0.1-1 torr is given as well. It is concluded that there is a possibility for increasing plasma neutron radiation power of the fast linear theta-pinch when increasing magnetic field in the solenoid and initial pressure in the discharge chamber

  15. Calculation and Measurement of the Neutron Emission Spectrum due to Thermonuclear and Higher-Order Reactions in Tokamak Plasmas

    OpenAIRE

    Ballabio, Luigi

    2003-01-01

    A series of analytic and numerical models have been developed for the prediction and interpretation of the energy spectrum of the neutron emission from thermonuclear deuteriumtritium (DT) plasmas. The main component of the neutron emission, due to reactions between thermal fuel ions, has been modeled as well as minority components due to the presence of fast (supra-thermal) ions. In particular, the so-called alpha-particle knock-on neutron (AKN) emission has been analyzed and found to carry i...

  16. Use of prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent

    International Nuclear Information System (INIS)

    The possibility of using measured prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent is explored theoretically. Monte Carlo simulations have been carried out using the FLUKA code to calculate the response of a high density polyethylene cylinder to emit prompt gammas from interaction of neutrons with the nuclei of hydrogen and carbon present in polyethylene. The neutron energy dependent responses of hydrogen and carbon nuclei are combined appropriately to match the energy dependent neutron fluence to ambient dose equivalent conversion coefficients. The proposed method is tested initially with simulated spectra and then validated using experimental measurements with an Am–Be neutron source. Experimental measurements and theoretical simulations have established the feasibility of estimating neutron ambient dose equivalent using measured neutron induced prompt gammas emitted from polyethylene with an overestimation of neutron dose at very low energies. - Highlights: • A new method for estimating H⁎(10) using prompt gamma emissions from HDPE. • Linear combination of 2.2 MeV and 4.4 MeV gamma intensities approximates DCC (ICRP). • Feasibility of the method was established theoretically and experimentally. • The response of the present technique is very similar to that of the rem meters

  17. Use of prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent

    Energy Technology Data Exchange (ETDEWEB)

    Priyada, P.; Sarkar, P.K., E-mail: pradip.sarkar@manipal.edu

    2015-06-11

    The possibility of using measured prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent is explored theoretically. Monte Carlo simulations have been carried out using the FLUKA code to calculate the response of a high density polyethylene cylinder to emit prompt gammas from interaction of neutrons with the nuclei of hydrogen and carbon present in polyethylene. The neutron energy dependent responses of hydrogen and carbon nuclei are combined appropriately to match the energy dependent neutron fluence to ambient dose equivalent conversion coefficients. The proposed method is tested initially with simulated spectra and then validated using experimental measurements with an Am–Be neutron source. Experimental measurements and theoretical simulations have established the feasibility of estimating neutron ambient dose equivalent using measured neutron induced prompt gammas emitted from polyethylene with an overestimation of neutron dose at very low energies. - Highlights: • A new method for estimating H{sup ⁎}(10) using prompt gamma emissions from HDPE. • Linear combination of 2.2 MeV and 4.4 MeV gamma intensities approximates DCC (ICRP). • Feasibility of the method was established theoretically and experimentally. • The response of the present technique is very similar to that of the rem meters.

  18. Detecting Special Nuclear Material Using Muon-Induced Neutron Emission

    OpenAIRE

    Guardincerri, E.; Bacon, J. D.; Borodzin, K.; Durham, J. M.; Fabritius II, J. M.; Hecht, A; Milner, E C; Miyadera, H.; Morris, C. L.; Perry, J. O.; Poulson, D.

    2014-01-01

    The penetrating ability of cosmic ray muons makes them an attractive probe for imaging dense materials. Here, we describe experimental results from a new technique that uses neutrons generated by cosmic-ray muons to identify the presence of special nuclear material (SNM). Neutrons emitted from SNM are used to tag muon-induced fission events in actinides and laminography is used to form images of the stopping material. This technique allows the imaging of SNM-bearing objects tagged using muon ...

  19. 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.

  20. 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

  1. Study of neutron and X-ray emission from stainless steel anode plasma focus

    International Nuclear Information System (INIS)

    In a low energy (2.3 kJ) Mather-type plasma focus with stainless steel anode, neutron and X-ray emission is investigated by employing time integrated and time resolved detectors. The neutron yield of 3.5x 10/sup 8/ is observed, which is almost double the yield when copper anode is used. It is speculated that low sputtering yield of the anode material lowers the impurity concentration in the plasma and thus enhances the neutron yield. One may therefore conclude that a proper choice of the electrode material is essential to achieve enhanced radiation yield from plasma focus devices. At pressure of 2.0 mbar, neutron yield is found to be the lightest and almost isotropic, Further, multiple foci are also observed. The neutron fluence isotropy and the high yield are attributed to trapping of magnetic flux lines and of the energetic deuterons between the two current sheaths. (author)

  2. 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...

  3. Hydrogen content in Zircaloy-IV by neutron emissions

    International Nuclear Information System (INIS)

    The feasibility of using thermal neutron transmission techniques to determine the initial hydrogen content in Zry-IV is discussed in this work. The usual conditions of very low H concentration (∼ 10-20 ppm in weight) in the alloy, require a high degree of accuracy in the relevant cross sections in order to obtain reliable values of that concentration from the measured transmission spectra. Total cross sections corresponding to the metallic alloy and to hydrogen in that matrix were evaluated using interaction models developed in this Laboratory, for neutrons covering the range from subthermal up to epithermal energies. The sensitivity of this method as a function of neutron energy is discussed, and an optimized and self consistent procedure for data analysis after a transmission experiment is proposed. (Author)

  4. Progress in the KAERI high energy nuclear data library : proton-induced neutron emission spectra

    International Nuclear Information System (INIS)

    Proton-induced neutron yields and emission spectra up to a few hundreds MeV are important nuclear data in the particle transport of the accelerator-driven system (ADS) and in the space shielding for trapped protons and solar energetic particle events. Within the framework of KAERI high energy nuclear data library evaluation, energy-angle spectra of secondary neutrons produced from the proton-induced neutron production reaction, (p, xn), of C-12, Al-27, Fe-56, and Pb-208 for energies below 400 MeV are evaluated based upon model calculations, guided and benchmarked by existing experimental data. Theoretical calculations were performed with the optical model analysis for the direct reactions and transmission coefficients, Hauser-Feshbach model for the equilibrium emission, and the exciton model for the preequilibrium emission, using the ECIS-GNASH code system. (author)

  5. 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

  6. A device for quantitative plutonium testing in mixed fuel by its neutron emission

    International Nuclear Information System (INIS)

    A device for quantitative plutonium testing in mixed fuel by its neutron emission is described. The method of ''assigned dead time'' for isolation of neutrons of spontaneous fission is used in the device. The main characteristics of the registrating equipment specifying the regime of measuring and affecting testing errors are presented. The results of spontaneous fission neutrons detection in the range up to 100 g of plutonium linearly depend on 240Pu. Sensitivity of testing makes up about 28 pul./s per 1 g of 240Pu

  7. Variability in the Thermal Emission from Accreting Neutron Star Transients

    OpenAIRE

    Brown, Edward F.; Bildsten, Lars; Chang, Philip

    2002-01-01

    The composition of the outer 100 m of a neutron star sets the heat flux that flows outwards from the core. For an accreting neutron star in an X-ray transient, the thermal quiescent flux depends sensitively on the amount of hydrogen and helium remaining on the surface after an accretion outburst and on the composition of the underlying ashes of previous H/He burning. Because H/He has a higher thermal conductivity, a larger mass of H/He implies a shallower thermal gradient through the low dens...

  8. 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)

  9. Enhanced γ -Ray Emission from Neutron Unbound States Populated in β Decay

    Science.gov (United States)

    Tain, J. L.; 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.; ńystö, 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.; Martínez, T.; Mendoza, E.; Moore, I.; Penttilä, H.; Podolyák, Zs.; Reponen, M.; Sonnenschein, V.; Sonzogni, A. A.

    2015-08-01

    Total absorption spectroscopy is used to investigate the β -decay intensity to states above the neutron separation energy followed by γ -ray emission in Br,8887 and 94Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy is compared to Hauser-Feshbach model calculations. For 87Br and 88Br the γ branching reaches 57% and 20%, respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich 94Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled by introducing an enhancement of 1 order of magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proves to be correct, leads to a similar increase in the (n ,γ ) cross section that would have an impact on r process abundance calculations.

  10. 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

  11. Measurement of neutron-induced charged-particle-emission reaction cross section using gridded ionization chamber

    International Nuclear Information System (INIS)

    A gridded ionization chamber (GIC) having large geometrical efficiency, ∼2π, has been developed for measurements of neutron-induced charged-particle emission cross sections. Test experiments proved the proper operation of GIC with complete charge collection even if the gas pressure was over 10 atm.. GIC was applied successfully to proton and α emission cross section measurements for nickel at the several MeV and 15 MeV incident neutron energies with the results in good agreement with the previous data and evaluations. The construction of GIC and the experimental technique are presented in this paper. (author)

  12. The estimation of β-delayed two-neutron emission probability in the A>=50 region

    International Nuclear Information System (INIS)

    The probability of recently discovered β-delayed two-neutron emission is calculated using the microscopic model based on the finite Fermi systems theory. For nuclei of sup(50,51,52)K, 86As, 92Br, 91Se, sup(98,99,100)Rb, 132In, 136Sb with measured half-lives predictions are made. The effect of the β-strength function structure on β-delayed two-neutron emission probability in the continuous part of the spectrum is discussed. (orig.)

  13. Detecting special nuclear material using muon-induced neutron emission

    Energy Technology Data Exchange (ETDEWEB)

    Guardincerri, Elena; Bacon, Jeffrey; Borozdin, Konstantin; Matthew Durham, J.; Fabritius II, Joseph [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hecht, Adam [University of New Mexico, Albuquerque, NM 87131 (United States); Milner, Edward C. [Southern Methodist University, Dallas, TX 75205 (United States); Miyadera, Haruo; Morris, Christopher L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Perry, John [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); University of New Mexico, Albuquerque, NM 87131 (United States); Poulson, Daniel [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2015-07-21

    The penetrating ability of cosmic ray muons makes them an attractive probe for imaging dense materials. Here, we describe experimental results from a new technique that uses neutrons generated by cosmic-ray muons to identify the presence of special nuclear material (SNM). Neutrons emitted from SNM are used to tag muon-induced fission events in actinides and laminography is used to form images of the stopping material. This technique allows the imaging of SNM-bearing objects tagged using muon tracking detectors located above or to the side of the objects, and may have potential applications in warhead verification scenarios. During the experiment described here we did not attempt to distinguish the type or grade of the SNM.

  14. Detecting special nuclear material using muon-induced neutron emission

    Science.gov (United States)

    Guardincerri, Elena; Bacon, Jeffrey; Borozdin, Konstantin; Matthew Durham, J.; Fabritius, Joseph, II; Hecht, Adam; Milner, Edward C.; Miyadera, Haruo; Morris, Christopher L.; Perry, John; Poulson, Daniel

    2015-07-01

    The penetrating ability of cosmic ray muons makes them an attractive probe for imaging dense materials. Here, we describe experimental results from a new technique that uses neutrons generated by cosmic-ray muons to identify the presence of special nuclear material (SNM). Neutrons emitted from SNM are used to tag muon-induced fission events in actinides and laminography is used to form images of the stopping material. This technique allows the imaging of SNM-bearing objects tagged using muon tracking detectors located above or to the side of the objects, and may have potential applications in warhead verification scenarios. During the experiment described here we did not attempt to distinguish the type or grade of the SNM.

  15. Detecting special nuclear material using muon-induced neutron emission

    International Nuclear Information System (INIS)

    The penetrating ability of cosmic ray muons makes them an attractive probe for imaging dense materials. Here, we describe experimental results from a new technique that uses neutrons generated by cosmic-ray muons to identify the presence of special nuclear material (SNM). Neutrons emitted from SNM are used to tag muon-induced fission events in actinides and laminography is used to form images of the stopping material. This technique allows the imaging of SNM-bearing objects tagged using muon tracking detectors located above or to the side of the objects, and may have potential applications in warhead verification scenarios. During the experiment described here we did not attempt to distinguish the type or grade of the SNM

  16. Neutron emission during Pd-D2O electrolysis

    International Nuclear Information System (INIS)

    A clear correlation has been found between neutron counting and the pulsation of an electrolysis current obtained with different Pd cathodes (rolled and wire) in D2O. Different spectra as a function of time synchronized with the electrolysis current of Pd-D2O and Pd-H2O are presented, all in identical conditions. Measurements in Pd-D2O lack the (statistically significant) synchronic increments in counting which are observed when the electrolite used is D2O. On the hypothesis that the observed neutrons are originated in Deuteron fusion with a branching ratio 0.5, the obtained countings correspond to a fusion rate of approximately 0.5 fusions/second. (Author)

  17. 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

  18. 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...

  19. 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.)

  20. 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.)

  1. A Programme for a Systematic Experimental Study of Delayed Neutron Emission in Fission

    International Nuclear Information System (INIS)

    The programme of the Soreq-On-Line Isotope Separator (SOLIS) aimed at the study of very short-lived nuclides produced in thermal and 14 MeV neutron-induced fission is outlined. The use of appropriate chemical separation methods in conjunction with the isotopic separation facilitates the observation, at steady state conditions, of individual rapidly decaying nuclides. This system will be used for a systematic investigation of delayed neutron emission, viz. identification and characterization of precursors followed by a detailed study of nuclear structure and independent yields. At present, techniques for the rapid separation of rare gas and halogen fission products, suitable for on-line isotopic separation, are being developed. For rare gas studies, a uranium-barium stearate emanation source swept by a stream of nitrogen gas is being used. The decontamination factor with respect to halogen is ≈ 105 , and higher for other activities. Separation time of ∼2 seconds is routine. With this system (without isotopic separation), it was possible to establish delayed neutron emission from both 93Kr (T0.5 = 1.19 t 0.05 sec, Pn = 3.9%) and 93Rb (T0.5 = 5.60 ±0.05 sec, Pn = 2.6%). The half-life of 94Kr is estimated as 0.4 ± 0.1 sec. For bromine and iodine, selective recoil labelling is used (for extraction of independently produced species while the same nuclides produced by beta decay are discriminated against) followed by fast gas chromatography. Using empirical Pn-values and fission yields for 14 known precursors, good fits to experimental total delayed neutron yields of groups 1-4 were obtained for a series of fission reactions. Systematic deviations indicate unidentified precursors. The inconsistencies between expected and reported results on delayed neutron yield variations with the energy of the fission-inducing neutrons are being checked by high resolution γ-ray spectometry in conjunction with neutron counting, with the aim of determining these relations with

  2. A programme for a systematic experimental study of delayed neutron emission in fission

    International Nuclear Information System (INIS)

    The programme of the Soreq-On-Line Isotope Separator (SOLIS) aimed at the study of very short-lived nuclides produced in thermal and 14 MeV neutron-induced fission is outlined. The use of appropriate chemical separation methods in conjunction with the isotopic separation facilitates the observation, at steady state conditions, of individual rapidly decaying nuclides. This system will be used for a systematic investigation of delayed neutron emission, viz. identification and characterization of precursors followed by a detailed study of nuclear structure and independent yields. At present, techniques for the rapid separation of rare gas and halogen fission products, suitable for on-line isotopic separation, are being developed. For rare gas studies, a uranium-barium stearate emanation source swept by a stream of nitrogen gas is being used. The decontamination factor with respect to halogen is ∼105, and higher for other activities. Separation time of ∼2 seconds is routine. With this system (without isotopic separation), it was possible to establish delayed neutron emission from both 93Kr (T1/2 = 1.19 t 0.05 sec, Pn = 3.9%) and 93Rb(T1/2 = 5.60 ± 0.05 sec, Pn = 2.6%). The half-life of 94Kr is estimated as 0.4 ± 0.1 sec. For bromine and iodine, selective recoil labelling is used (for extraction of independently produced species while the same nuclides produced by beta decay are discriminated against) followed by fast gas chromatography. Using empirical Pn-values and fission yields for 14 known precursors, good fits to experimental total delayed neutron yields of groups 1-4 were obtained for a series of fission reactions. Systematic deviations indicate unidentified precursors. The inconsistencies between expected and reported results on delayed neutron yield variations with the energy of the fission-inducing neutrons are being checked by high resolution γ-ray spectrometry in conjunction with neutron counting, with the aim of determining these relations with

  3. Monte Carlo simulation of prompt neutron emission during acceleration in fission

    International Nuclear Information System (INIS)

    The possibility of prompt neutron emission during acceleration of fission fragments (FFs) was examined by means of Monte Carlo method and statistical neutron emission model. Multimodal random neck-rapture model was used to describe the initial distribution of mass, charge, and total kinetic energy of the primary fragments. Statistical model was used to simulate the de-excitation process of the fragments from the moment of scission until full acceleration. By random number sampling, the fission process was simulated in order to obtain the basic physical quantities, and their correlations were analyzed to verify the adequacy of the model. It was found that, on the average, ∼10% and ∼16% of prompt neutrons for 235U(n th,f) and 252Cf(sf), respectively, were emitted before reaching 90% of the final fragment kinetic energy. (author)

  4. Slow-neutron-induced charged-particle emission-channeling-measurements with Medipix detectors

    Czech Academy of Sciences Publication Activity Database

    Koster, U.; Granja, C.; Jakubek, J.; Uher, J.; Vacík, Jiří

    2011-01-01

    Roč. 633, č. 1 (2011), S267-S269. ISSN 0168-9002. [11th International Workshop on Radiation Imaging Detector s. Praha, 28.06.2009-02.07.2009] Institutional research plan: CEZ:AV0Z10480505 Keywords : Emission channeling * Neutron induced reaction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.207, year: 2011

  5. 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.

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

    International Nuclear Information System (INIS)

    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

  7. 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.

  8. 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.

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

    International Nuclear Information System (INIS)

    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

  10. 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

  11. Neutron pre-emission at the fusion of 11 Li halo nuclei with Si targets

    International Nuclear Information System (INIS)

    In this contribution, the first experiment on fusion of 11 Li halo nuclei with Si targets is reported. A novel effect consisting of a large neutron pre-emission probability in the fusion process was observed. The neutron halo nuclei are characterized by very large matter radii, small separation energy and small internal momentum of the valence neutrons. Until now, the halo nuclei were investigated mostly by elastic, inelastic scattering and breakup processes. It was recently predicted that due to the very large dimension of 11 Li, one may expect, that in a fusion experiment on a light target, the valence neutrons will not be absorbed together with the 9 Li core, but will be emitted in the early stage of the reaction process. The experiment aiming to check this expectation, performed at RIKEN-RIPS facility, is described. In the experimental arrangement, three main parts are present: the first part contains the detectors used for the control, identification and determination of the beam characteristics; the second part consists of a Multiple Sampling Ionisation Chamber (MUSIC), used for identification of the inclusive evaporation residue spectra produced in the detector-target; the third part consists of two wall neutron detectors, each made up of 15 plastic scintillators. This detector was used for the energy and position determination of the neutrons originating from the target. The projectile energy range was 11.2 - 15.2 AMeV, centered at 13 AMeV. The neutrons resulting from the reaction were measured by time-of-light technique. The position on the 'wall' of the detected neutrons could be also determined. The measured neutron spectra from 11 Li and 9 Li are shown. A marked different between the two spectra was found and it is explained by the contribution of a large amount of pre-emission (breakup) processes, in case of 11 Li projectiles. The position spectra point out the evaporation origin of the neutrons in case of 9 Li projectiles while for 11 Li only the

  12. 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.

  13. Characterization of the volcanic eruption emissions using neutron activation analysis

    International Nuclear Information System (INIS)

    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

  14. 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...

  15. 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...

  16. Neutron emissions from a lunar-based reactor: Excavation siting

    International Nuclear Information System (INIS)

    Lunar surface operations, such as deep space observatories, mineral extraction facilities, and oxygen production factories, will require large amounts of electrical power. Compact nuclear reactor power sources are possible for such applications where the demand exceeds 25 kW(electric) and will be required above 500 kW(electric). One scenario for the siting of a lunar reactor power system is to place the reactor at the bottom of an excavation and locate the power conversion and heat rejection systems on the lunar surface. The lunar soil provides the necessary radiation shielding for equipment and personnel, and this configuration minimizes the amount of shielding material that must be transported from Earth. Such a configuration, however, allows neutrons to be scattered around the primary instrument shields and to be emitted from the top of the hole. A parametric study of excavation configurations has been completed using MCNP. Variations of the excavation design include increasing the depth and the diameter of the excavation and the inclusion of neutron absorbing materials in the bulkheads, which support the reactor power system and restrain the lunar soil

  17. 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)

  18. 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

  19. 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)

  20. Study of the fission dynamics of hot atomic nuclei by means of the neutron emission

    International Nuclear Information System (INIS)

    In the framework of the present thesis fusion processes with subsequent fission are studied in the heavy ion reactions 141Pr+40Ar and 175Lu+12C. The aim of the studies is the determination of the hitherto not precisely known lifetimes of excited composite systems before these separate into two fission fragments. In order to study such effects the reactions 141Pr+40Ar at 316 MeV argon as well as 175Lu+12C at 192 MeV carbon projectile energy were measured. The evaluation of the measured angular distribution of the fission fragments and the evaporation residual nuclei yielded the angular momentum ranges which lead to the fusion with subsequent fission respectively to evaporation residual nuclei. A large critical angular momentum of 109± ℎ in the reaction Pr+Ar and an essentially smaller value of 62±6 ℎ for the system Lu+C result regarding the uncomplete fusion. The analysis of the neutron emission measured in coincidence with fission fragments allowed the determination of the neutron multiplicities for the composite system before the scission as well as for each single fission fragment. Large multiplicities before the scission of 3.6±0.6 and 6.3±0.8 in the reactions Pr+Ar and Lu+C were observed. In the study of the pre-equilibrium neutron emission in the incompletely fusioning system Lu+C for the first time a strong concentration of the emitted neutrons in the plane defined by the direction of flight of the fission fragments and the ion beam was shown. This anisotropy can be interpreted as anisotrope neutron emission relative to the angular momentum direction of the composite system. A corresponding anisotropy was not observed for the neutron evaporation from the completely equilibrated system. (orig./HSI)

  1. Measurement of secondary neutron emission double-differential cross sections for 9Be induced by 21.65 ± 0.07 MeV neutrons

    Science.gov (United States)

    Lan, Changlin; Ruan, Xichao; Chen, Guochang; Nie, Yangbo; Huang, Hanxiong; Bao, Jie; Zhou, Zuying; Tang, Hongqing; Kong, Xiangzhong; Peng, Meng

    2016-05-01

    The neutron emission double-differential cross sections (DDX) of 9Be was measured at an incident neutron energy of 21.65 MeV, using the multi-detector fast neutron time-of-flight (TOF) spectrometer on HI-13 Tandem Accelerator at the China Institute of Atomic Energy (CIAE). The data were deduced by comparing the measured TOF spectra with the calculated ones using a realistic Monte-Carlo simulation. The DDX were normalized to n-p scattering cross sections which are a neutron scattering standard. The results of the elastic scattering angular distributions (DX) and the secondary neutron emission DDX at 25 different angles from 15 deg to 145 deg were presented. Meanwhile, a theoretical model based on the unified Hauser-Feshbach and exciton model for light nuclei was used to describe the double-differential cross sections of n+9Be, and the theoretical calculation results were compared with the measured cross sections.

  2. MMAPDNG: A new, fast code backed by a memory-mapped database for simulating delayed γ-ray emission with MCNPX package

    Science.gov (United States)

    Lou, Tak Pui; Ludewigt, Bernhard

    2015-09-01

    The simulation of the emission of beta-delayed gamma rays following nuclear fission and the calculation of time-dependent energy spectra is a computational challenge. The widely used radiation transport code MCNPX includes a delayed gamma-ray routine that is inefficient and not suitable for simulating complex problems. This paper describes the code "MMAPDNG" (Memory-Mapped Delayed Neutron and Gamma), an optimized delayed gamma module written in C, discusses usage and merits of the code, and presents results. The approach is based on storing required Fission Product Yield (FPY) data, decay data, and delayed particle data in a memory-mapped file. When compared to the original delayed gamma-ray code in MCNPX, memory utilization is reduced by two orders of magnitude and the ray sampling is sped up by three orders of magnitude. Other delayed particles such as neutrons and electrons can be implemented in future versions of MMAPDNG code using its existing framework.

  3. Spatial distribution of DD-fusion neutron emission from a plasma focus measured with thermoluminescent dosimeters

    Czech Academy of Sciences Publication Activity Database

    Velyhan, Andriy; Bienkowska, B.; Ivanova-Stanik, I.M.; Juha, Libor; Karpinski, L.; Klír, D.; Králík, M.; Krása, Josef; Kravárik, J.; Kubeš, P.; Miklaszewski, R.; Paduch, M.; Schmidt, H.; Scholz, M.; Šolc, J.; Tomaszewski, K.

    Mulhouse : European Physical Society, 2007 - (Gasior, P.; Wolowski, J.), P5.083/1-P5.083/4 ISBN 978-83-926290-0-9. - (Europhysics Conference Abstracts. 31F). [EPS Conference on Plasma Physics /34./. Warsaw (PL), 02.07.2007-06.07.2007] R&D Projects: GA MŠk 1P04LA235 Institutional research plan: CEZ:AV0Z10100523 Keywords : plasma focus * DD-fusion neutrons * emission anisotropy * neutron dosimetry Subject RIV: BL - Plasma and Gas Discharge Physics

  4. Neutron and photon dosimetry at an installed high emission 252Cf source

    International Nuclear Information System (INIS)

    The irradiation hazard was studied in work with the 252Cf fission spectrum neutron source (with a total amount of 1 mg) with a total neutron emission of 2.3x109 s-1. Gamma radiation and neutrons were measured using film dosemeters and track detectors in association with fissionable material (U enriched to 6.5% of 235U and an alloy of Th + 0.5% of natural U). Radiation doses and dose equivalents were assessed by methods developed at the UVVVR Personnel Dosimetry Laboratory. Relations were determined of fast and slow neutrons, this with shielding the staircase with moulded NEUTROSTOP 3B bricks and with the staircase unshielded. It was found that in the control room the dose equivalent did not exceed 1.5x105 Sv.h-1, i.e., 1.5 mrem/h. With the staircase shielded the dose equivalent decreased by about 1/3. Delayed neutron fluence only increased near the shielding; their low biological efficiency, however, does not affect the total dose and dose equivalent values. Also studied were changes in spectra and the respective spectral part proportions. It was found that the slow neutron contribution increased with distance and the presence of a moderating medium up to the equilibrium state when only an even decrease started of the dosimetric values of all spectral components. (B.S.)

  5. 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...

  6. 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

  7. 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

  8. Examination of cathodically charged palladium electrodes for excess heat, neutron emission, or tritium production

    International Nuclear Information System (INIS)

    This paper presents a search for steady-state excess heat, neutron emission, or tritium production carried out for palladium electrodes electrolytically charged with deuterium. No substantial deviation in cell temperatures was observed, and the upper limit to excess heat production was 320 mW/cm3 for the largest palladium cathode. No increase in neutron production above background levels was observed, and the sensitivity of the neutron detection system yielded an upper limit of 2.18 x 10-22 (3-σ) fusion/s · atom-1 pair. The tritium levels in the cells increased by 50%, but the cells were run in the open configuration and the tritium increases were consistent with electrolytic enrichment. An approximate upper limit for tritium production was 2 x 102 tritium/ml · C-1. The cell temperatures were recorded once daily and monitored intermittently, but no transient excess heat excursions were observed throughout the experiment

  9. Expert (exotic Particle Emission and Radioactivity by Tracking) Studies at the Super-Frs Spectrometer

    Science.gov (United States)

    Geissel, H.; Kiselev, O.; Mukha, I.; Simon, H.; Scheidenberger, C.; Weick, H.; Winkler, M.; Fomichev, A.; Belogurov, S.; Bezbakh, A.; Chudoba, V.; Golovkov, M.; Gorshkov, A.; Itkis, Y.; Kaminski, G.; Knyazev, A.; Knyazheva, G.; Kozulin, E.; Krupko, S.; Mianowski, S.; Rymzhanova, S.; Sidorchuk, S.; Sharov, P.; Slepnev, R.; Ter-Akopian, G.; Zagrebaev, V.; Pfützner, M.; Dominik, W.; Janas, Z.; Mazzocchi, Ch.; Mianowski, S.; Korsheninnikov, A. A.; Kuzmin, E. A.; Nikolskii, E. Yu.; Eremin, I.; Eremin, V.; Fadeeva, N.; Terukov, E.; Tuboltsev, Yu.; Verbitskaya, E.; Ershov, S. N.; Egorova, I. A.; Nasirov, A. K.; Dunin, V. B.; Alkhazov, G. D.; Dobrovolsky, A. V.; Khanzadeev, A. V.; Parfenova, Yu. L.; Xu, X.; Kaminski, G.; Kopatch, Y.

    2015-06-01

    The proposal EXPERT is suggested for the Super-FRS Collaboration physics program [1] in the NUSTAR Collaboration of the project FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. It is aimed at studies of the nuclear landscape beyond the proton and neutron drip-lines and intends to push researches up to limits of nuclear existence. By combining the EXPERT instrumentation (two tracking techniques applied for radioactivity and nuclear decays in-flight), the phenomena of multi-nucleon radioactivity, resonance decays in continuum, beta-delayed exotic decays and exotic excitation modes can be studied via observations of particle emissions, including the 2p, 4p, 6p, n, 2n, 4n, 6n channels.

  10. Actinide isotopes compositions and neutrons emission rate calculations for irradiated research reactors fuel

    International Nuclear Information System (INIS)

    the availability of burn-up data is an essential first step in any systematic approach to the enhancement of safety, economics and performance of research reactors. A computer program has been designed to solve the system of equations describing the depletion, decay and production of uranium, plutonium and transplutonium nuclides. monte Carlo code was used to calculate the effective one group microscopic cross sections averaged over ETRR-1 fuel cell. the compositions of actinide isotopes, burn-up and neutrons emission rate have been calculated as a function of irradiation time and cooling time. results indicate that the amount of plutonium produced and neutrons emission rate are strongly dependent on the fuel burn-up

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. Survey on neutron pre-emission at the fusion of 11 Li halo nuclei with light targets

    International Nuclear Information System (INIS)

    The neutron halo nuclei characterized by very large matter radii, small separation energy and small internal momentum of the valence neutrons, were discovered by Tanihata and co-workers. Until now, the halo nuclei were investigated mostly by elastic, inelastic scattering and breakup processes. It was recently predicted, that due to the very large dimension of 11 Li, one may expect, that in a fusion experiment on a light target, the valence neutrons will not be absorbed together with the 9 Li core, but will be emitted in the early stage of the reaction process. The first experiment aiming to check this expectation, was performed at the RIKEN-RIPS facility. In the experimental setup, the MUSIC chamber, achieved in the frame of IFIN-HH - RIKEN cooperation, played an important role. The obtained results confirm the prediction, indicating to a novel pre-emission effect (near 40 %, for one or two neutrons). The pre-emission of neutron pairs was investigated by time-position coincidences. It is considered that the pre-emission of neutron pairs is responsible for the experimentally observed strong neutron focusing effect. An experiment aiming to a large number of n-n coincidences, based on a new neutron array detector built in the frame of IFIN-HH - RIKEN cooperation, is in preparation. A model for the pre-emission probabilities calculations has been also worked out. Good agreement with the experimental data has been obtained. (author)

  18. Neutron resonance study of a delayed neutron emitter, /sup 87/Kr

    CERN Document Server

    Fogelberg, B; Macklin, R L; Raman, S; Stelson, P H

    1981-01-01

    The unbound levels in /sup 87/Kr have been studied as neutron resonances up to 400 keV neutron energy at the ORELA linear electron accelerator. The observed p-wave resonances, with I/sup pi /=1/2/sup - / and 3/2/sup -/ can also be populated in the beta -decay of the 3/2 /sup -/ ground state of /sup 87/Br. When comparing the present results with previous studies of beta -delayed neutron spectra, the authors find that almost all observed p-wave resonances can be identified with peaks in the delayed neutron spectra. (0 refs).

  19. 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.

  20. 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.

  1. Reactivity and neutron emission measurements of burnt PWR fuel rod samples in LWR-PROTEUS phase II

    International Nuclear Information System (INIS)

    Measurements have been made of the reactivity effects and the neutron emission rates of uranium oxide and mixed oxide burnt fuel samples having a wide range of burnup values and coming from a Pressurised Water Reactor (PWR). The reactivity measurements have been made in a PWR lattice moderated in turn with: water, a water and heavy water mixture, and water containing boron. An interesting relationship has been found between the neutron emission rate and the measured reactivity. (authors)

  2. 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.

  3. 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

  4. 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

  5. Measurement and analysis of the neutron emission from ICRH and NB heated JET D plasmas using the TOFOR spectrometer

    International Nuclear Information System (INIS)

    A new time-of-flight (tTOF) neutron spectrometer has been installed at JET and used in its first dedicated experiment to observe neutron emission from deuterium plasmas subjected to NB and NB+RF heating. The heating scenarios such as the NB energy and the RF resonance position were changed to create different neutron emission conditions to test the diagnostic performance of the spectrometer. The instrument is described as well as the analysis employed to extract information on the energy distribution of the incoming neutron flux. Data in the form of measured tTOF spectra are presented as well as the results of the neutron spectral analysis involving bulk and high-energy components of the deuteron population

  6. 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.

  7. 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 (

  8. 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 (

  9. 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.

  10. 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

  11. 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...

  12. Possible use of a BGO array for neutron stimulated emission computed tomography by summing adjacent signals

    International Nuclear Information System (INIS)

    Neutron stimulated emission computed tomography (NSECT) is a new approach for biological spectroscopy and imaging. Since the gamma-ray photons emitted from stimulated element have energies from 100 keV to about 6 MeV, previous reports have proposed that the projection path can be defined by the neutron beam. In this paper, another possible method has been applied and the performance presented through simulations. When using signals from a single BGO crystal it is impossible to achieve good energy resolution for such high-energy photons. When summing additional signals from adjacent crystals, the energy spectrum becomes much better. Using an energy window with energy resolution of 90 keV, an average intrinsic spatial resolution of 3.938 mm FWHM is obtained

  13. 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

  14. 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.

  15. 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)

  16. 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.

  17. 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

  18. Single photon emission tomography approach for online patient dose assessment in boron neutron capture therapy

    International Nuclear Information System (INIS)

    A tomographic imaging system for the measurement of the spatial distribution of the absorbed dose during a Boron Neutron Capture Therapy (BNCT) session is presented. The 10B(n,α)7Li boron neutron capture reaction produces a 478 keV gamma ray in 94% of the cases. Therefore its detection can serve as a basis for a non-invasive online absorbed dose determination since the dose absorbed by the tumor and healthy tissue strongly depends on the boron uptake and the neutron flux. For this purpose, a dedicated tomographic imaging system based on Single Photon Emission Computed Tomography is proposed. Monte Carlo numerical simulations are used for the system design aimed to have a spatial resolution of 1 cm. Prototypes based on CdZnTe semiconductor detectors and LaBr3(Ce) scintillators with optimized shielding were designed with Monte Carlo simulations. They were built and tested in reactor and accelerator based BNCT facilities. A projection of a phantom with two tumors with 400 ppm of 10B was successfully measured at the accelerator facility of the University of Birmingham. (author)

  19. Characteristics of the array detector built for neutron pre-emission investigations

    International Nuclear Information System (INIS)

    Evidence for neutron pair pre-emission in the fusion of 11 Li halo nuclei with Si targets was reported by us for the first time in 1996. For further testing of this effect, an array detector covering (36x36) cm2, has been built. To have also good position resolution a 4 x 4 cm2 area of a single scintillation element was chosen. As concerns the thickness of the scintillation element, a compromise between efficiency, cross-talk between adjacent detectors and cost was established. For example, for 6 cm thickness of the plastic crystal, the detection efficiency for 13 MeV neutrons is only 20% and the cross-talk 1.7%. For 12 cm thickness the detection efficiency significantly raises to 35% and the cross-talk becomes 2.8%. For larger thickness the efficiency only slightly increases. For 18 cm thickness the efficiency is expected to be 41%, and the cross-talk 3.3%. Therefore, by choosing the 12 cm thickness, one expects good efficiency with a reasonable increase of the cross-talk. The above mentioned efficiency and cross-talk values were obtained by Monte-Carlo calculations. The 81 BC400 plastic scintillation elements were cut from two 1000 x 300 x 40 mm3 pieces. After polishing, the quality of the surfaces was tested by optical methods. The BC400 crystal detects charged particles, γ rays, and neutrons. The γ-ray and neutron separation will be done at RIKEN by the time of flight technique. The Philips XP2972 photomultiplier was selected for building the array detector. This selection was based on the following considerations: 1.the diameter is suited to the granularity of the detector; 2. the phototube sensitivity matches the plastic crystal emission; 3. the output pulse has very good characteristics (pulse height close to 1 volt and a rise time of 2.1 ns). The voltage divider has been designed for large multiplication and stability, in conditions of counting rates up to 104 pulses/s. The total resistance is 2.6 MΩ. The following testings on the new array detector have

  20. 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.

  1. Neutron emission from the strongly damped reaction 165Ho + 56Fe at 8.5 MeV

    International Nuclear Information System (INIS)

    Neutron and α-particle emission from the 165Ho + 56Fe reaction at 8.5 MeV/A has been studied for damped and fusion-fission events. It is shown, that the measured multiplicities, energy spectra and angular distributions of neutrons are consistent with a full equilibration of the excitation energy and the N/Z degree of freedom during the reaction time. (orig.)

  2. Statistical and evaporation models for the neutron emission energy spectrum in the center-of-mass system from fission fragments

    International Nuclear Information System (INIS)

    The neutron emission energy spectra in the CMS (center-of-mass) frame from two compound nuclei produced by fission are studied. The neutron spectra calculated with the Hauser–Feshbach statistical model are compared with the evaporation theory, and the definition of the temperature is revisited. Using the Monte Carlo technique we average the CMS neutron spectra from many fission fragments to construct the representative CMS spectrum from both the light and heavy fragments. The CMS spectra for each fission fragment pair are also converted into the laboratory frame to calculate the total prompt fission neutron spectrum that can be observed experimentally. This is compared to measured laboratory data for thermal neutron induced fission on 235U. We show that the Hauser–Feshbach calculation gives a different spectrum shape than the Madland–Nix model calculation

  3. 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...

  4. 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

  5. Neutron emission as a probe of fusion-fission and quasi-fission dynamics

    International Nuclear Information System (INIS)

    Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of 16,18O, 40Ar and 64Ni. A new method of interpretation of experimental pre-scission neutron multiplicities ν-pre and mean kinetic energies εν allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35±15) x 10-21s for symmetric fission. All reactions show that ν-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of ν-pre on TKE, whilst for 64Ni-induced quasi-fission reactions, a strong increase of ν-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs

  6. Actinide content and associated neutron emission of WWER-440 spent fuel - calculation and validation for safeguards purposes

    International Nuclear Information System (INIS)

    A major task of international nuclear material safeguards consists in the experimental determination of the characteristics of spent nuclear fuel. In this respect, passive neutron techniques take a prominent place. The paper describes both the actinide content and the passive neutron emission of spent WWER-440 fuel for a number of operational conditions. For validation purposes the results have been compared with those independently gained by other authors for the same type of fuel. The calculations are the basis for a true to fact interpretation of the primary measurement signal, i.e. for the inference from recorded neutron radiation regarding the properties of the spent nuclear fuel. (author)

  7. 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.)

  8. Measurement and analysis of 14 MeV neutron-induced double-differential neutron emission cross sections needed for fission and fusion reactor technology

    International Nuclear Information System (INIS)

    The main objectives of this IAEA Co-ordinated Research Programme are to improve the current status of data for 14 MeV neutron-induced double-differential neutron emission cross sections for V, Cr, Fe, Nb, Ta and 238U. The principal objectives of this first meeting were to report on the status of participants' work, to exchange experience in experimental work and to establish the future work. Considering the unsatisfactory status of the data for 6Li, 7Li, 9Be, Mo, W and Bi and their importance in fusion reactor technology participants agreed to include these isotopes in the programme

  9. Equilibrium amd direct mechanism contribution to neutron emission spectra from 56Fe nuclei at 14 MeV initial energy

    International Nuclear Information System (INIS)

    Neutron emission spectra from Fe(n, xn) reaction at 14 MeV have been analyzed, taking into account direct and equilibrium interaction mechanisms. The direct contribution to the neutron emission spectra have been calculated using the DWBA method and strong channel couplings the equilibrium contribution was described in the framework of the Hauser-Feshbach approach using the generalized model of superfluid nucleus for the level density with fitted to experiment parameters. Comparison of the calculation with experimental data shows a good agreement and sufficiency of only these two processes

  10. 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.

  11. Calculations of the main free path on neutron emission cross-section for spallation reaction of target and fuel nuclei

    International Nuclear Information System (INIS)

    There are several new technological application fields of fast neutrons such as accelerator-driven incineration/ transmutation of the long-lived radioactive nuclear wastes (in particular transuranium nuclides) to short-lived or stable isotopes by secondary spallation neutrons produced by high-intensity, intermediate-energy, charged-particle beams, prolonged planetary space missions, shielding for particle accelerators. Especially, accelerator driven subcritical systems (ADS) can be used for fission energy production and /or nuclear waste transmutation as well as in the intermediate-energy accelerator driven neutron sources, ions and neutrons with energies beyond 20 MeV, the upper limit of exiting data files that produced for fusion and fission applications. In these systems, the neutron scattering cross sections and emission differential data are very important for reactor neutronics calculations. The transition rate calculation involves the introduction of the parameter of mean free path determines the mean free path of the nucleon in the nuclear matter. This parameter allows an increase in mean free path, with simulation of effect, which is not considered in the calculations, such as conservation of parity and angular momentum in intra nuclear transitions. In this study, we have investigated the multiple preequilibrium matrix element constant from internal transition for Uranium, Thorium, (n,xn) neutron emission spectra. The neutron-emission spectra produced by (n,xn) reactions on nuclei of some target (for spallation) have been calculated. In the calculations, we have used the geometry dependent hybrid model and the cascade exciton model including the effects of the preequilibrium. The pre-equilibrium direct effects have been examined by using full exciton model. All calculated results have been compared with the experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other

  12. 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.

  13. 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.

  14. Study of proton and 2 protons emission from light neutron deficient nuclei around A=20

    International Nuclear Information System (INIS)

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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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...

  20. 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.)

  1. 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...

  2. 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.

  3. 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)

  4. Preliminary Results of a Full Hauser-feshbach Simulation of the Prompt Neutron and Gamma Emission from Fission Fragments

    Science.gov (United States)

    Regniera, D.; Litaizea, O.; Serota, O.

    The prompt neutron and gamma emission from fission fragments are investigated through the Monte Carlo code FIFRELIN which is developed at the CEA Cadarache research center. In a previous release of the code, the de-excitation of the fragments was treated in a two steps process. First the emission of all the prompt neutrons was simulated using a Weisskopf spectrum for the distribution of their kinetic energy. In a second step, the excitation energy still available was dissipated by the fragments as an electromagnetic decay cascade. This paper presents a new procedure for fragment de-excitation using an Hauser-Feshbach treatment of prompt particles emission. The neutron/gamma competition is then accounted for during the whole cascade. Moreover, the neutron emission is now ruled by the transmission coefficients directly coming from an optical model calculation performed with TALYS-1.4. The implementation of these models in the code FIFRELIN is quickly highlighted. The results in terms of neutrons and gamma multiplicities and spectra for one simulation of a 252Cf spontaneous fission are emphasized. The neutron multiplicity experimental data are used to constraint the parameters of our simulation. The prompt gamma spectrum calculated is then consistent with experimental data and the structures observed experimentally in the low energy range are well reproduced. However, the same simulation performed with several different nuclear models and parameters reveals high variation of these fission observables. For example, the average total gamma energy (Eγ,tot) is shown to vary up to 20% with changes in the level density or radiative strength function model.

  5. 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 ...

  6. 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.

  7. 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...

  8. 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 .

  9. 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...

  10. GeV Emission from neutron-rich internal shocks of some long Gamma-ray Bursts

    CERN Document Server

    Xue, Rongrong; Wei, Daming

    2008-01-01

    In the neutron-rich internal shocks model for gamma-ray bursts (GRBs), the Lorentz factors (LFs) of ion shells are variable, and so are the LFs of accompanying neutron shells. For slow neutron shells with a typical LF of approximate tens, the typical $\\beta$-decay radius is $\\sim 10^{14}-10^{15}$ cm. As GRBs last long enough [$T_{90}>14(1+z)$ s], one earlier but slower ejected neutron shell will be swept successively by later ejected ion shells in the range $\\sim10^{13}-10^{15}$ cm, where slow neutrons have decayed significantly. Part of the thermal energy released in the interaction will be given to the electrons. These accelerated electrons will be mainly cooled by the prompt soft $\\gamma-$rays and give rise to GeV emission. This kind of GeV emission is particularly important for some very long GRBs and is detectable for the upcoming satellite {\\it Gamma-Ray Large Area Space Telescope} (GLAST).

  11. Isotropic and anisotropic components of neutron emissions at the FN-II and PACO dense plasma focus devices

    International Nuclear Information System (INIS)

    The average angular distribution of neutron emissions has been measured in the Fuego Nuevo II (FN-II) dense plasma focus device (5 kJ) by means of CR-39 plastic nuclear track detectors. When pure deuterium is used as the filling gas, the data can be adjusted to a Gaussian function, related to anisotropic emission, superposed on a constant pedestal, related to isotropic emission. When deuterium-argon admixtures are used, the anisotropic contribution is best represented by a parabola. The same analysis is applied to previously reported results, for fewer shots, in pure deuterium from the PACO device, which is similar in size to the FN-II. In both devices the anisotropic component is smaller than the isotropic one, but with different features. In PACO the anisotropic component is concentrated on a large narrow beam around the axis, but its contribution to the total neutron yield is significantly smaller than in the FN-II, where the anisotropic component spreads over a wider range. The neutron flux per shot is monitored in both devices with calibrated silver activation detectors, at 20 deg. and at 90 deg. from the axis. The average values of the neutron flux at these two angles are used, along with the angular distributions obtained form the track detectors, in order to estimate the absolute neutron yield of both the isotropic and the anisotropic contributions. From examining different groups of shots, it is found that the shape of the angular distribution is important in the estimation of anisotropy, and that the value usually reported, as the ratio of neutron counts head-on and side-on, as measured by activation counters, may be misleading

  12. 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.

  13. 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.

  14. The neutron emission induced by the radioactive nuclear beam 17N on targets 9Be and 197Au

    International Nuclear Information System (INIS)

    The neutron energy spectra emitted in the reactions of 33.4MeV/u 17N on 9Be and 197Au targets have been measured at different angles with the time of flight method. The angular distributions were composed of two components: one focused into a narrow angle range around the beam direction and another extended over a large angle region. Integrating the angular distribution, the obtained total cross sections of neutron emission were (15.2 +- 1.7) x 10-28m2 and (120 +- 20) x 10-28m2 barns respectively for 9Be and 197Au targets

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Components of a reference database for β-delayed neutron emission

    International Nuclear Information System (INIS)

    A reference database is a database that is considered the state of the art standard by a user community. Three reference databases are presented as examples, namely the Fukushima Monitoring Database, FMD (https://iec.iaea.org/fmd/), the Reference Input Parameter Library, RIPL-3 (http://www-nds.iaea.org/RIPL-3/) and the Ion Beam Analysis Library IBANDL (http://www-nds.iaea.org/exfor/ibandl.htm). The structure, organization and ways to display and filter data are tailored in each case taking into account the needs and preferences of the user community. On one hand, the FMD has a very diverse user community and had little time to adapt to user needs, which explains its structure and limited display capabilities, on the other hand the RIPL and the IBANDL databases have been around for some time adapting to user needs. In fact, the RIPL database has been the standard for the neutron and light ion-induced nuclear reactions since 1993 (n, p, d, t, He-3,He-4, g up to 100 MeV) , while the IBANDL database is the default standard for the Ion Beam Analysis community since 2002. Both databases present the user the data organized in ''segments'' according to the content of the database. For instance the RIPL database has 7 data segments where data about atomic masses, nuclear levels, nuclear resonances, optical model parameters, nuclear densities, giant dipole resonances and fission are available. The IBANDL database divides the data according to the kind of experimental data such as Elastic Backscattering, Nuclear Reaction Analysis and Particle Induced Gamma-ray Emission. In this CRP we will have to think about the potential user community of the Reference Database for β-delayed Neutron Emission. Possible communities that would be involved are: reactor, decay heat, astrophysics, safeguards and security (antineutrinos), nuclear theory etc. Possibly each community will require not only different kind of data, but also different software to filter and display the relevant

  1. Gravitational waves and neutrino emissions from the binary neutron star mergers

    International Nuclear Information System (INIS)

    Coalescence of binary neutron stars is a main target of the ground-based gravitational observatory such as KAGRA and important target for the multimessenger astronomy. If gravitational waves and neutrinos from mergers of binary neutron star, it would be possible to probe the nuclear matter inside neutron stars. In this report, we would like to overview the discovery of the binary neutron star and the research for the gravitational wave and introduce our latest research based on Numerical Relativity. (author)

  2. Study of the trace tritium content in deuterium plasmas of the JET tokamak based on neutron emission spectroscopy measurements

    International Nuclear Information System (INIS)

    This thesis describes a study of the evolution of the trace tritium content in the JET tokamak. The study is based on measurements of the neutron emission, which were performed with the magnetic proton recoil (MPR) spectrometer. Data analysis procedures used to extract the results are described in some detail. The thesis also describes a simplified theoretical model to calculate the absolute tritium concentration with a comparison to the experimental results. The present study covers the time period 1996-2000 and the evolution of neutron emission spectroscopy (NES) results are compared with information from related diagnostic sources, and used to discuss the important issue of how tritium is retained in the JET tokamak

  3. Investigation of the prompt neutron emission mechanism in low energy fission of 235,233U(nth, f) and 252Cf(sf)

    OpenAIRE

    Val’ski G.V.; Gagarski A.M.; Shcherbakov O.A.; Vorobyev A.S.; Petrov G.A.

    2010-01-01

    A series of experiments has been performed to measure prompt neutron angular and energy distributions from thermal neutron-induced fission of 235,233U in correlation with the fission fragments. These distributions have been analyzed with the assumption of neutron isotropic emission from accelerated fission fragments. The performed analysis demonstrates that all obtained results can be described within 5% accuracy using this assumption. This discrepancy is approximately constant and doesn’t de...

  4. A Study of the Mass Spectra of Fission Fragments after Prompt Neutron Emission

    International Nuclear Information System (INIS)

    The distribution of the masses of fission fragments, following neutron emission, was obtained by simultaneously measuring the velocity and energy of each particle. The special feature of this method is that it is essentially independent of the initial energy of the fragments, so that we were able to use relatively thick targets of fissionable material (0.1 mg/cm2). The energy measurement is made by a gold-silicon surface barrier detector: the velocity measurement was made on a flight path of 130 cm, with a total resolving power of 1.5 ns; The ''starting'' detector consisted of a windowless photomultiplier that detected directly the secondary electrons emitted by a thin metallic sheet during the passage of the fission fragments. The ''stop'' signal is picked up directly, by means of a transformer, on the semi-conductor detector. The results given in the paper relate to the thermal fission of U235, and are compared with the results obtained by the radiochemical method. (author)

  5. 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)

  6. 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.

  7. 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)

  8. 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)

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

    International Nuclear Information System (INIS)

    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.

  11. 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)

  12. Neutron emission in deep inelastic reactions induced by 86Kr on 166Er At 5.7, 7.0, and 7.9 MeV/nucleon

    International Nuclear Information System (INIS)

    Neutron emission associated with deep inelastic collisions of 86Kr with 166Er has been studied as a function of bombarding energy, kinetic energy loss, fragment mass and fragment and neutron scattering angles. These measurements provide information on de-excitation processes involved in the collision, the total excitation energy of the fragments and the sharing of excitation energy between the fragments. (orig.)

  13. Neutron diffraction and acoustic emission study of Mg-Al-Sr alloy reinforced with short Saffil (R) fibers deformed in compression

    Czech Academy of Sciences Publication Activity Database

    Farkas, G.; Máthis, K.; Lukáš, Petr; Pilch, Jan; Vrána, Miroslav; Janeček, M.; Trojanová, Z.

    Vol. 777. Stafa-Zurich : Transt Tech Publications Ltd, 2014, s. 92-98. ISSN 0255-5476. [7th International Conference on Mechanical Stress Evalutaion by Neutrons and Synchrotron Radiation. Sydney (AU), 10.09.2013-12.09.2013] Institutional support: RVO:61389005 Keywords : magnesium composite * neutron diffraction * residual stress * acoustic emission Subject RIV: BM - Solid Matter Physics ; Magnetism

  14. 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.

  15. 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.

  16. 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

  17. Prompt Neutron Emission from Fragments in Spontaneous Fission of 244, 248Cm and 252Cf

    Science.gov (United States)

    Vorobyev, A. S.; Dushin, V. N.; Hambsch, F.-J.; Jakovlev, V. A.; Kalinin, V. A.; Laptev, A. B.; Petrov, B. F.; Shcherbakov, O. A.

    2005-11-01

    Neutrons emitted in fission were measured separately for each complementary fragment in correlation with fission fragment energies. Two high efficient Gd-loaded liquid scintillator tanks were used for neutron registration. Fission fragment energies were measured using a twin Frisch gridded ionization chamber with a pin-hole collimator. The neutron multiplicity distributions were obtained for each value of the fission fragment mass and energy and corrected for neutron registration efficiency, background and pile-up. The dependencies of these distributions on fragment mass and energy for different energy and mass bins, as well as the mass and energy distribution of the fission fragments are presented and discussed.

  18. 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

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

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. Observing Infrared Emission Lines of Neutron-Capture Species in Planetary Nebulae: New Detections with IGRINS

    Science.gov (United States)

    Dinerstein, Harriet L.; Sterling, N. C.; Kaplan, Kyle F.; Bautista, Manuel A.

    2015-08-01

    As the former envelopes of evolved stars, planetary nebulae (PNe) present an opportunity to study slow neutron-capture reactions (the “s-process”) during the AGB. Such studies differ from those of AGB stars in two ways. First, PNe represent the end point of self-enrichment and dredge-up in the star and most of its mass return to the ISM, enabling us to infer the nucleosynthetic yield of a specific element. Second, some s-process products are observable in PNe but difficult or impossible to observe in cool stars. These include some species with nuclear charge Z in the 30’s for which the major synthesis sites are uncertain. Optical emission lines of trans-iron species have been observed in some PNe, but are faint and can suffer from blending with lines of more abundant elements (Péquignot & Baluteau 1994, A&A, 283, 593; Sharpee et al. 2007, ApJ, 659, 1265). Observing infrared transitions from low energy states has proven to be a fruitful alternate approach. We used K-band lines of Se (Z=34) and Kr (Z=36) to study the demographics of their abundances in a large sample of Milky Way PNe (Dinerstein 2001, ApJ, 550, L223; Sterling & Dinerstein 2008, ApJ, 174, 158; Sterling, Porter, & Dinerstein 2015, submitted). An L-band emission line of Zn identified by Dinerstein & Geballe (2001, ApJ, 562, 515) and further observed by Smith, Zijlstra, & Dinerstein 2014 (MNRAS, 441, 3161), can be used as a tracer of the Fe-group, enabling determinations of the key stellar population diagnostic ratio [alpha/Fe] in PNe (see poster by Dinerstein et al., Focus Meeting 4). Using IGRINS, a high spectral resolution H and K band spectrometer (Park & Jaffe et al. 2014, Proc SPIE, 9147), we have discovered several new lines not previously reported in any astronomical object. Our detection of an H-band line of Rb (Z=37) confirms previous claims of optical Rb detections and indicates enrichment by a factor of ~4 in the PN NGC 7027 (Sterling, Dinerstein, Kaplan, & Bautista, in preparation

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  4. 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.

  5. 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.)

  6. 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.

  7. In-situ neutron diffraction and acoustic emission investigation of twinning activity in magnesium

    Czech Academy of Sciences Publication Activity Database

    Máthis, K.; Beran, Přemysl; Čapek, J.; Lukáš, Petr

    2012-01-01

    Roč. 340, 012096 (2012), s. 1-6. ISSN 1742-6588. [5th European Conference on Neutron Scattering. Praha, 17.07.2011-21.07.2011] Institutional support: RVO:61389005 Keywords : magnesium alloys * twinning * compression * tension * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism

  8. Fuel ion ratio determination in NBI heated deuterium tritium fusion plasmas at JET using neutron emission spectrometry

    Science.gov (United States)

    Hellesen, C.; Eriksson, J.; Binda, F.; Conroy, S.; Ericsson, G.; Hjalmarsson, A.; Skiba, M.; Weiszflog, M.; Contributors, JET-EFDA

    2015-02-01

    The fuel ion ratio (nt/nd) is of central importance for the performance and control of a future burning fusion plasma, and reliable measurements of this quantity are essential for ITER. This paper demonstrates a method to derive the core fuel ion ratio by comparing the thermonuclear and beam-thermal neutron emission intensities, using a neutron spectrometer. The method is applied to NBI heated deuterium tritium (DT) plasmas at JET, using data from the magnetic proton recoil spectrometer. The trend in the results is consistent with Penning trap measurements of the fuel ion ratio at the edge of the plasma, but there is a discrepancy in the absolute values, possibly owing to the fact that the two measurements are weighted towards different parts of the plasma. It is suggested to further validate this method by comparing it to the traditionally proposed method to estimate nt/nd from the ratio of the thermal DD and DT neutron emission components. The spectrometer requirements for measuring nt/nd at ITER are also briefly discussed.

  9. Comparative measurement of prompt fission γ -ray emission from fast-neutron-induced fission of 235U and 238U

    Science.gov (United States)

    Lebois, M.; Wilson, J. N.; Halipré, P.; Oberstedt, A.; Oberstedt, S.; Marini, P.; Schmitt, C.; Rose, S. J.; Siem, S.; Fallot, M.; Porta, A.; Zakari, A.-A.

    2015-09-01

    Prompt fission γ -ray (PFG) spectra have been measured in a recent experiment with the novel directional fast-neutron source LICORNE at the ALTO facility of the IPN Orsay. These first results from the facility involve the comparative measurement of prompt γ emission in fast-neutron-induced fission of 235U and 238U . Characteristics such as γ multiplicity and total and average radiation energy are determined in terms of ratios between the two systems. Additionally, the average photon energies were determined and compared with recent data on thermal-neutron-induced fission of 235U . PFG spectra are shown to be similar within the precision of the present measurement, suggesting that the extra incident energy does not significantly impact the energy released by prompt γ rays. The origins of some small differences, depending on either the incident energy or the target mass, are discussed. This study demonstrates the potential of the present approach, combining an innovative neutron source and new-generation detectors, for fundamental and applied research on fission in the near future.

  10. 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).

  11. 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)

  12. 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.

  13. 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.

  14. Emission probabilities of gamma rays from the decay of 233Pa and 238Np, and the thermal neutron capture cross section of 237Np

    International Nuclear Information System (INIS)

    In order to determine the thermal neutron capture cross section of 237Np, the relevant γ emission probabilities of the 312-keV γ-ray from the decay of 233Pa and the 984-keV γ-ray from the decay of 238Np are deduced from the ratio of the emission rate to the activity. The emission rate and activity are measured with a Ge detector and a Si detector, respectively. The measured emission probability for 312-keV γ-ray is 41.6±0.9% and that for 984-keV γ-ray is 25.2±0.5%. The emission probabilities are used to correct the thermal neutron capture cross section of 237Np reported previously, and gives 168±6b. The neutron capture cross section is also determined as 169±6b by α-ray spectroscopic method. The measured emission probabilities and capture cross section are compared with others from references. By averaging these values deduced by different methods, the value of 169±4b is recommended as the thermal neutron capture cross section of 237Np for 2,200 m/s neutrons. (author)

  15. 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)

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

    International Nuclear Information System (INIS)

    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 (α, 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)

  17. Upper limits on emission of neutrons from Ti in pressurized D2 gas cells: A test of evidence for ''cold fusion''

    International Nuclear Information System (INIS)

    We have used a low background detector with high efficiency for detection of bursts to search for emission of neutrons from Ti alloy in pressurized D2 gas cells (cooled to 77 K in liquid nitrogen). Each cell contained between 16 and 67 g of Ti alloy chips and was prepared by methods identical to those used in a recent Los Alamos-Brigham Young University collaboration of Menlove et al. Three to four cells were used in each experimental run, with a total counting time of 103 h, leading to an estimate (based on the early reports of Menlove et al.) of at least four bursts and as many as 12 bursts expected in our experiment. In a later report the burst rate of Menlove et al. is greatly reduced leading to only one or so burst(s) expected in our experiment. The data were analyzed in two modes. In the first mode (singles mode) all detectors were used to search for neutron bursts with an efficiency of 28% for neutron detection and a background of 100 counts per hour (cph). In the second mode (coincidence mode) the neutron time of flight was measured in a search for random emission with an efficiency of 2% and a background of 2 cph. No statistically significant deviations from the background were observed for correlated neutrons emitted in bursts or for neutrons emitted randomly. All events are shown (with 90% confidence) to be consistent with background. For bursts of neutrons we deduce (with 90% confidence) an upper limit on the bursts' size of 50 neutrons. Our upper limit on the random emission of neutrons, 0.008 n/sec (90% confidence), is a factor of 6 to 25 smaller than the range of rates for random emission above background reported by the Los Alamos--Brigham Young University collaboration

  18. 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

  19. 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

  20. Observation of repetitive bursts in emission of fast ions and neutrons in sub-nanosecond laser-solid experiments

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; Klír, D.; Velyhan, Andriy; Margarone, Daniele; Krouský, Eduard; Jungwirth, Karel; Skála, Jiří; Pfeifer, Miroslav; Kravárik, J.; Kubeš, P.; Řezáč, K.; Ullschmied, Jiří

    2013-01-01

    Roč. 31, č. 3 (2013), s. 395-401. ISSN 0263-0346 R&D Projects: GA MŠk EE2.3.20.0279; GA ČR GAP205/12/0454; GA MŠk LM2010014 Grant ostatní: OPVK 3 Laser Zdroj(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : laser-plasma interactions * neutron yield scaling * bursts in ion emission Subject RIV: BH - Optics, Masers, Lasers; BL - Plasma and Gas Discharge Physics (UFP-V) Impact factor: 1.701, year: 2013

  1. 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.

  2. Neutron emission in peripheral heavy ion collisions in the system Ho + Ne

    International Nuclear Information System (INIS)

    In the present thesis peripheral collision processes in the system 165Ho + 20Ne were studied. The measurement of the neutrons in coincidence with projectile-like fragments should answer the central question whether at incident energies of approx.=15 respectively 20 MeV/nucleon a thermal equilibrium is reached yet during the interaction time. The analysis of the neutron spectra resulted that the largest part of the neutrons was evaporated just after reaching the thermal equilibrium from the fragments fully accelerated in the Coulomb field. About 10% of the neutrons however were emitted during the interaction time and showed the same spectral shape as the pre-equilibrium neutrons in central collisions. A further hint for pre-equilibrium effects yielded the result that the temperatures of the projectile-like fragments were larger than those of the target-like. This could be explained for quasi-elastic processes by assuming a fluctuation in the partition of the excitation energy. For deep inelastic processes such explanation wasn't possible. At neon fragment with low energy loss furthermore direct processes could be observed in which the projectile has picked up a neutron from the target nucleus without excitation of it. From the known width of the observed state in 21Ne the reaction time could be fixed to values lower than 6x10-21 s. (HSI)

  3. 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...

  4. Measurement and QRPA-calculation of the β-delayed neutron emission of 21N, 22N and 23O, 24O

    International Nuclear Information System (INIS)

    Neutron-rich isotopes of nitrogen and oxygen have been produced as projectile-like fragments in the reaction of a 44 MeV/u 48Ca beam with a 173 mg/cm2181Ta target. The fragments have been analyzed by the doubly achromatic spectrometer LISE and implanted in a semiconductor identification telescope, surrounded by a 4Π neutron detector in order to observe their radioactive decay. The β-delayed neutron emission has been measured for the isotopes 21N, 22N and 23O, 24O for the first time and the β-half-lives T1/2 and delayed neutron-emission probabilities Pn are determined. These values are discussed within the framework of a QRPA calculation. The influence of the decay energy Qβ used in the calculation is examined, indicating the reliability of predicted matrix elements. Furthermore, Pn-values are calculated and compared to the experimental data

  5. 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...

  6. A STUDY OF THE PARTICULATE AND GASEOUS EMISSIONS OF TRITIUM FROM NEUTRON GENERATOR TARGETS

    Science.gov (United States)

    Neutron generator targets are prepared by adsorption of elemental tritium on titanium or zirconium film on a copper backing. The stability of tritium on the target depends on the ability of Ti or Zr to form stable hydrides (tritides) resulting in chemical compounds rather than a ...

  7. 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

  8. 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)

  9. Measurement of double differential neutron emission cross sections at 14.1 MeV for Ca, Mn, Co and W

    International Nuclear Information System (INIS)

    Using the neutron TOF spectrometer at OKTAVIAN, double differential neutron emission cross sections at 14.1 MeV were measured for Ca, Mn, Co and W which are of interest for shielding and structural material elements of fusion reactors. Data were obtained for 16 angle points from 15 to 160 deg in the LAB system for each element, covering the secondary neutron energy region from 0.5 MeV to 15 MeV. Statistics and energy resolution of obtained data are satisfactory. The double differential cross sections in the LAB system were once converted to those in the center-of-mass system and integrated over scattering angle to obtain neutron emission spectra. Angle-differential cross sections were obtained for the elastic and discrete-inelastic scatterings whose peaks in DDX spectra could be resolved. The measured DDX data are so numerous that only their graphs are shown in this report. However, the graphs and numerical tables are given for the neutron emission spectra and the angle-differential cross sections. In the graphs, preliminary comparisons are made with evaluated data (ENDF/B-IV and JENDL-3T). The ENDF/B-IV data for Ca are satisfactory in the high energy region, but overestimate the experimental values in the low energy region. The JENDL-3T data for Mn reproduce well the angle-integrated neutron emission spectrum, though underestimation is seen in the 6-13 MeV region. It is noted that ENDF/B-IV underestimates the emission spectrum of Co in the 3-13 MeV region. The ENDF/B-IV data for W do not agree at all with the experimental spectral patterns. (author)

  10. A balloon-borne Ge(Li) spectrometer for observation of cyclotron line emissions from neutron stars

    International Nuclear Information System (INIS)

    A balloon-borne high-resolution Ge(Li) spectrometer for observation of electron cyclotron line emissions in the hard X-ray spectra of neutron stars is described. The spectrometer consists of four planar type Ge(Li) crystals and operates in the energy range of 20-200keV. The Ge(Li) crystals are housed in vacuum cryostats and cooled by liquid nitrogen. A total effective area of the spectrometer is 120 cm2 and an energy resolution is 2keV fwhm at 60 keV. A 2 mm thick lead honeycomb collimator provides background rejection and collimation, defining a field of view 200x200 fwhm. The sensitivity of the spectrometer to line emissions from cosmic point sources is 10-3 photons cm-2 s-1 over the energy range. The Ge(Li) spectrometer is scheduled for balloon-flight in September 1979. Electron cyclotron line emissions from Her X-1 and Crab Nebula are to be searched. (orig.)

  11. Upper Bound for Neutron Emission from Sonoluminescing Bubbles in Deuterated Acetone

    International Nuclear Information System (INIS)

    An experimental search for nuclear fusion inside imploding bubbles of degassed deuterated acetone at 0 degree sign C driven by a 15 atm sound field and seeded with a neutron generator reveals an upper bound that is a factor of 10 000 less than the signal reported by Taleyarkhan et al. The strength of our upper bound is limited by the weakness of sonoluminescence, which we ascribe to the relatively high vapor pressure of acetone

  12. 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...

  13. 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.,

  14. 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.

  15. Importance of the wave function tail in computing the pre-emission probability for the halo neutron from 11 Be fusion with light and heavy targets

    International Nuclear Information System (INIS)

    In this work, an improved method for the estimation of the neutron pre-emission probability in a fusion process is given, taking into account a more realistic halo neutron distribution with an extreme long tail. It has been demonstrated that core and halo densities can be separated in: ρ(r) = ρc (r) + ρh (r). 11 Be, the only one neutron halo nucleus has two bound states, both of halo type, with one neutron separation energies 0.5 MeV and 0.2 MeV, respectively. The 2s1/2 state is the main component (77%) of the ground state of 11 Be. The density distribution of the halo neutron was determined by solving Schroedinger equation for a separation energy of Sn = - 0.504 MeV using a Woods-Saxon potential. The halo neutron is considered to be on 2s1/2 state. The root mean square radius of 10 Be is taken as 2.90 fm. All the following steps in our estimation are parameter free for the neutron pre-emission probability method. A sharp cut-off approach for the fusion process was used. After computing the volume distribution, we calculated the superficial distribution of the halo neutron on a surface which is perpendicular on the beam direction. The volume was divided in spherical shells with step equal to 0.1 fm in which we considered the probability distribution to be constant. These shells were projected on that surface. After that, the same method was applied for three energies: E1 near the Coulomb barrier, E2 near the energy of an expected experiment and E3 near that value when the compound nucleus explodes. The results are given in a Table. The pre-emission probability is dependent on target radius. For a smaller size target (12 C, Si), the probability is larger than for a large size target nucleus (209 Bi). All these results are thought as an upper limit for the neutron pre-emission probability, due to the fact that the applied model corresponds to a r.m.s. radius of 5.2 fm for 11 Be neutron halo. We want to thank M. Fukuda, I. Bulboaca and F. Carstoiu for help and

  16. 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.

  17. Determination of isotopic composition of boron in various neutron absorbers by a particle induced gamma-ray emission method

    International Nuclear Information System (INIS)

    A particle induced gamma-ray emission (PIGE) method was utilized for non-destructive determination of isotopic composition of boron (10B/11B atom ratio) in seven natural and two enriched boron based neutron absorber samples. Samples in pellet forms were irradiated with 4 MeV proton beam from FOlded Tandem Ion Accelerator (FOTIA) at BARC, Mumbai. The prompt gamma rays of 429, 718 and 2125 keV from 10B (p, αγ)7Be, 10B(p,p'γ)10B and 11B(p,p' γ)11B, respectively, were measured using high resolution gamma-ray spectrometry. Isotopic composition values were arrived by a relative method using corresponding peak areas of 10B and 11B. (author)

  18. 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.

  19. Quaking neutron star deriving radiative power of oscillating magneto-dipole emission from energy of Alfv\\'en seismic vibrations

    CERN Document Server

    Bastrukov, S I; Xu, R X; Yu, J W

    2010-01-01

    It is shown that depletion of the magnetic field pressure in a quaking neutron star undergoing Lorentz-force-driven torsional seismic vibrations about axis of its dipole magnetic moment is accompanied by the loss of vibration energy of the star that causes its vibration period to lengthen at a rate proportional to the rate of magnetic field decay. Highlighted is the magnetic-field-decay induced conversion of the energy of differentially rotational Alfv\\'en vibrations into the energy of oscillating magneto-dipole radiation. A set of representative examples illustrating the vibration energy powered emission with elongating periods due to magnetic field decay are considered and discussed in the context of theory of magnetars.

  20. Radiochemical studies on the neutron- and proton-induced 7Be emission at energies up to 100 MeV

    International Nuclear Information System (INIS)

    Cross sections for 7Be emission in neutron and proton induced reaction on medium and heavy mass nuclei were measured up to 100 MeV using the activation method, radiochemical separations and γ-ray spectroscopy. For this purpose chemical separations were developed and modified to optain 7Be in a radiochemically pure form. In this work the excitation functions of (p,7Be) reactions on the target nuclei V, Nb, Au and Bi could be measured radiochemically for the first time in the energy range of 35 to 100 MeV. The cross sections for gold amount to a few μb, for vanadium to several tens of μb and for niobium to several hundred μb. (orig./HSI)

  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. Measurement of the cross section for electromagnetic dissociation with neutron emission in Pb-Pb collisions at √SNN=2.76 TeV

    International Nuclear Information System (INIS)

    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 σsingleEMD =187.4 ± 0.2(stat)+13.2-11.2(syst) b and σmutualEMD = 5.7±0.1(stat) ± 0.4(syst) b, respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model. (authors)

  3. Measurement of the cross section for electromagnetic dissociation with neutron emission in Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV.

    Science.gov (United States)

    Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agocs, A G; Agostinelli, A; Aguilar Salazar, S; Ahammed, Z; Ahmad Masoodi, A; Ahmad, N; Ahn, S U; Akindinov, A; Aleksandrov, D; Alessandro, B; Alfaro Molina, R; Alici, A; Alkin, A; Almaráz Aviña, E; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Arend, A; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Augustinus, A; Averbeck, R; Awes, T C; Aystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldini Ferroli, R; Baldisseri, A; Baldit, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Baumann, C; Bearden, I G; Beck, H; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Berzano, D; Betev, L; Bhasin, A; Bhati, A K; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Bjelogrlic, S; Blanco, F; Blanco, F; Blau, D; Blume, C; Bock, N; Bogdanov, A; Bøggild, H; Bogolyubsky, M; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Bose, S; Bossú, F; Botje, M; Böttger, S; Boyer, B; Braidot, E; Braun-Munzinger, P; Bregant, M; Breitner, T; Browning, T A; Broz, M; Brun, R; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Bugaiev, K; Busch, O; Buthelezi, Z; Caballero Orduna, D; Caffarri, D; Cai, X; Caines, H; Calvo Villar, E; Camerini, P; Canoa Roman, V; Cara Romeo, G; Carena, F; Carena, W; Carminati, F; Casanova Díaz, A; Castillo Castellanos, J; Casula, E A R; Catanescu, V; Cavicchioli, C; Ceballos Sanchez, C; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chawla, I; Cherney, M; Cheshkov, C; Cheynis, B; Chiavassa, E; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Coccetti, F; Colamaria, F; Colella, D; Conesa Balbastre, G; Conesa Del Valle, Z; Constantin, P; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortés Maldonado, I; Cortese, P; Cosentino, M R; Costa, F; Cotallo, M E; Crochet, P; Cruz Alaniz, E; Cuautle, E; Cunqueiro, L; Erasmo, G D; Dainese, A; Dalsgaard, H H; Danu, A; Das, D; Das, I; Das, K; Dash, A; Dash, S; De, S; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; De Marco, N; De Pasquale, S; de Rooij, R; Del Castillo Sanchez, E; Delagrange, H; Deloff, A; Demanov, V; Dénes, E; Deppman, A; Di Bari, D; Di Giglio, C; Di Liberto, S; Di Mauro, A; Di Nezza, P; Diaz Corchero, M A; Dietel, T; Divià, R; Djuvsland, O; Dobrin, A; Dobrowolski, T; Domínguez, I; Dönigus, B; Dordic, O; Driga, O; Dubey, A K; Ducroux, L; Dupieux, P; Dutta Majumdar, A K; Dutta Majumdar, M R; Elia, D; Emschermann, D; Engel, H; Erdal, H A; Espagnon, B; Estienne, M; Esumi, S; Evans, D; Eyyubova, G; Fabris, D; Faivre, J; Falchieri, D; Fantoni, A; Fasel, M; Fearick, R; Fedunov, A; Fehlker, D; Feldkamp, L; Felea, D; Fenton-Olsen, B; Feofilov, G; Fernández Téllez, A; Ferretti, A; Ferretti, R; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Fragkiadakis, M; Frankenfeld, U; Fuchs, U; Furget, C; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A; Gallio, M; Gangadharan, D R; Ganoti, P; Garabatos, C; Garcia-Solis, E; Garishvili, I; Gerhard, J; Germain, M; Geuna, C; Gheata, A; Gheata, M; Ghidini, B; Ghosh, P; Gianotti, P; Girard, M R; Giubellino, P; Gladysz-Dziadus, E; Glässel, P; Gomez, R; Ferreiro, E G; González-Trueba, L H; González-Zamora, P; Gorbunov, S; Goswami, A; Gotovac, S; Grabski, V; Graczykowski, L K; Grajcarek, R; Grelli, A; Grigoras, A; Grigoras, C; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grinyov, B; Grion, N; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerra Gutierrez, C; Guerzoni, B; Guilbaud, M; Gulbrandsen, K; Gunji, T; Gupta, A; Gupta, R; Gutbrod, H; Haaland, O; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Hanratty, L D; Hansen, A; Harmanova, Z; Harris, J W; Hartig, M; Hasegan, D; Hatzifotiadou, D; Hayrapetyan, A; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, N; Hess, B A; Hetland, K F; Hicks, B; Hille, P T; Hippolyte, B; Horaguchi, T; Hori, Y; Hristov, P; Hřivnáčová, I; Huang, M; Humanic, T J; Hwang, D S; Ichou, R; Ilkaev, R; Ilkiv, I; Inaba, M; Incani, E; Innocenti, G M; Ippolitov, M; Irfan, M; Ivan, C; Ivanov, A; Ivanov, M; Ivanov, V; Ivanytskyi, O; Jachołkowski, A; Jacobs, P M; Jancurová, L; Jang, H J; Jangal, S; Janik, M A; Janik, R; Jayarathna, P H S Y; Jena, S; Jha, D M; Jimenez Bustamante, R T; Jirden, L; Jones, P G; Jung, H; Jusko, A; Kakoyan, V; Kalcher, S; Kaliňák, P; Kalisky, M; Kalliokoski, T; Kalweit, A; Kanaki, K; Kang, J H; Kaplin, V; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karpechev, E; Kazantsev, A; Kebschull, U; Keidel, R; Khan, M M; Khan, S A; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, B; Kim, D J; Kim, D W; Kim, J H; Kim, J S; Kim, M; Kim, S; Kim, S H; Kim, T; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Klay, J L; Klein, J; Klein-Bösing, C; Kliemant, M; Kluge, A; Knichel, M L; Knospe, A G; Koch, K; Köhler, M K; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Konevskikh, A; Korneev, A; Kour, R; Kowalski, M; Kox, S; Koyithatta Meethaleveedu, G; Kral, J; Králik, I; Kramer, F; Kraus, I; Krawutschke, T; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Krus, M; Kryshen, E; Krzewicki, M; Kucheriaev, Y; Kuhn, C; Kuijer, P G; Kurashvili, P; Kurepin, A; Kurepin, A B; Kuryakin, A; Kushpil, S; Kushpil, V; Kweon, M J; Kwon, Y; La Pointe, S L; La Rocca, P; Ladrón de Guevara, P; Lakomov, I; Langoy, R; Lara, C; Lardeux, A; Lazzeroni, C; Le Bornec, Y; Lea, R; Lechman, M; Lee, K S; Lee, S C; Lefèvre, F; Lehnert, J; Leistam, L; Lemmon, R C; Lenhardt, M; Lenti, V; León Monzón, I; León Vargas, H; Leoncino, M; Lévai, P; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Liu, L; Loenne, P I; Loggins, V R; Loginov, V; Lohn, S; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luquin, L; Luzzi, C; Ma, R; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Mal'kevich, D; Malaev, M; Maldonado Cervantes, I; Malinina, L; Malzacher, P; Mamonov, A; Manceau, L; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; Marin Tobon, C A; Markert, C; Martashvili, I; Martinengo, P; Martínez, M I; Martínez Davalos, A; Martínez García, G; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Mastromarco, M; Mastroserio, A; Matthews, Z L; Matyja, A; Mayani, D; Mayer, C; Mazer, J; Mazzoni, M A; Meddi, F; Menchaca-Rocha, A; Mercado Pérez, J; Meres, M; Miake, Y; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Miśkowiec, D; Mitu, C; Mlynarz, J; Mohanty, A K; Mohanty, B; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Musa, L; Musso, A; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Naumov, N P; Navin, S; Nayak, T K; Nazarenko, S; Nazarov, G; Nedosekin, A; Nicassio, M; Nielsen, B S; Niida, T; Nikolaev, S; Nikolic, V; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Novitzky, N; Nyanin, A; Nyatha, A; Nygaard, C; Nystrand, J; Oeschler, H; Oh, S; Oh, S K; Oleniacz, J; Oppedisano, C; Ortiz Velasquez, A; Ortona, G; Oskarsson, A; Otwinowski, J; Oyama, K; Pachmayer, Y; Pachr, M; Padilla, F; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Patalakha, D I; Paticchio, V; Pavlinov, A; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perez Lezama, E; Perini, D; Perrino, D; Peryt, W; Pesci, A; Peskov, V; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Piccotti, A; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piuz, F; Piyarathna, D B; Płoskoń, M; Pluta, J; Pocheptsov, T; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polichtchouk, B; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puchagin, S; Puddu, G; Pujol Teixido, J; Pulvirenti, A; Punin, V; Putiš, M; Putschke, J; Quercigh, E; Qvigstad, H; Rachevski, A; Rademakers, A; Radomski, S; Räihä, T S; Rak, J; Rakotozafindrabe, A; Ramello, L; Ramírez Reyes, A; Raniwala, R; Raniwala, S; Räsänen, S S; Rascanu, B T; Rathee, D; Read, K F; Real, J S; Redlich, K; Reichelt, P; Reicher, M; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riccati, L; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Rodrigues Fernandes Rabacal, B; Rodríguez Cahuantzi, M; Rodriguez Manso, A; Røed, K; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Rosnet, P; Rossegger, S; Rossi, A; Roukoutakis, F; Roy, C; Roy, P; Rubio Montero, A J; Rui, R; Ryabinkin, E; Rybicki, A; Sadovsky, S; Safařík, K; Sahoo, R; Sahu, P K; Saini, J; Sakaguchi, H; Sakai, S; Sakata, D; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Sanchez Castro, X; Sándor, L; Sandoval, A; Sano, M; Sano, S; Santo, R; Santoro, R; Sarkamo, J; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schreiner, S; Schuchmann, S; Schukraft, J; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, P A; Scott, R; Segato, G; Selyuzhenkov, I; Senyukov, S; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Sgura, I; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, N; Sharma, S; Shigaki, K; Shimomura, M; Shtejer, K; Sibiriak, Y; Siciliano, M; Sicking, E; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Sinha, B C; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Son, H; Song, J; Song, M; Soos, C; Soramel, F; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stefanek, G; Stefanini, G; Steinbeck, T; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strabykin, K; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Sukhorukov, M; Sultanov, R; Sumbera, M; Susa, T; Szanto de Toledo, A; Szarka, I; Szczepankiewicz, A; Szostak, A; Tagridis, C; Takahashi, J; Tapia Takaki, J D; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Tlusty, D; Toia, A; Torii, H; Tosello, F; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urbán, J; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vallero, S; van der Kolk, N; van Leeuwen, M; Vande Vyvre, P; Vannucci, L; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Vikhlyantsev, O; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, L; Vinogradov, Y; Virgili, T; Viyogi, Y P; Vodopyanov, A; Voloshin, K; Voloshin, S; Volpe, G; von Haller, B; Vranic, D; Ovrebekk, G; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, B; Wagner, V; Wan, R; Wang, D; Wang, M; Wang, Y; Wang, Y; Watanabe, K; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, A; Wilk, G; Williams, M C S; Windelband, B; Xaplanteris Karampatsos, L; Yaldo, C G; Yang, H; Yang, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yoon, J; Yu, W; Yuan, X; Yushmanov, I; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, H; Zhang, X; Zhou, D; Zhou, F; Zhou, Y; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M

    2012-12-21

    The first measurement of neutron emission in electromagnetic dissociation of ^{208}Pb 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 sqrt[s(NN)]=2.76 TeV with neutron emission are σ(singleEMD)=187.4 ± 0.2(stat)(-11.2)(+13.2) (syst) b and σ(mutualEMD) = 5.7 ± 0.1(stat) ± 0.4(syst) b, respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model. PMID:23368454

  4. 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)

  5. 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.

  6. Investigation of the prompt neutron emission mechanism in low energy fission of 235,233U(nth, f and 252Cf(sf

    Directory of Open Access Journals (Sweden)

    Val’ski G.V.

    2010-10-01

    Full Text Available A series of experiments has been performed to measure prompt neutron angular and energy distributions from thermal neutron-induced fission of 235,233U in correlation with the fission fragments. These distributions have been analyzed with the assumption of neutron isotropic emission from accelerated fission fragments. The performed analysis demonstrates that all obtained results can be described within 5% accuracy using this assumption. This discrepancy is approximately constant and doesn’t depend on fragment mass and the total kinetic energy (TKE. Some minor peculiarities of angular distribution may be interpreted as a result of anisotropy of the fission neutron angular distribution in the fragment center-of-mass system.

  7. Study of the loading mode dependence of the twinning in random textured cast magnesium by acoustic emission and neutron diffraction methods

    Czech Academy of Sciences Publication Activity Database

    Čapek, J.; Máthis, K.; Clausen, B.; Stráská, J.; Beran, Přemysl; Lukáš, Petr

    2014-01-01

    Roč. 602, APR (2014), s. 25-32. ISSN 0921-5093 R&D Projects: GA ČR(CZ) GAP204/12/1360 Institutional support: RVO:61389005 Keywords : magnesium * acoustic emission * neutron diffraction * deformation twinning Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.567, year: 2014

  8. 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

  9. Search for neutron emission induced by thermal cycling of metal deuterides

    International Nuclear Information System (INIS)

    Experiments attempting to induce fusion of deuterons in several hydride-forming metals by the variation of temperature and pressure have been carried out using sensitive 3He neutron detectors in the time continuous and self-gating modes. The results obtained show no reproducibly significant deviation from the background signal in both modes of detection. Using the background count rate in the continuous mode, an upper limit fusion rate of λf -23 fusions per deuteron pair per second is estimated for the above experiments

  10. Results of intercomparison of primary calibration standards for radionuclide source neutron emission

    International Nuclear Information System (INIS)

    UVVVR possesses a so-called manganese bath, i.e., a primary calibration standard for radionuclide neutron sources. The manganese bath assembly was tested in 1982 and in 1988 and compared with calibration standards of other metrological institutes. In 1982, Am-Be and 252Cf sources were tested in ASMW (DD), UVVVR (CS), VNIIM (SU) and RI (SU), in 1988, the 252Cf comparison involved UVVVR, VNIIM and NLMII (BG). The results of comparisons are tabulated. (E.J.). 3 tabs., 3 refs

  11. Constraints on optical emission from the isolated neutron star candidate RX J0720.4-3125

    CERN Document Server

    Motch, C

    1998-01-01

    Deep optical B band images of the ROSAT HRI error region of RX J0720.4-3125 reveal the presence of two faint stellar-like objects with B = 26.1 +/- 0.25 and B = 26.5 +/- 0.30. Exposures obtained through U, V and I filters are not sensitive enough to detect the two candidates and provide upper limits of U = 24.9, V = 23.2 and I = 21.9. These new observations virtually establish that RX J0720.4-3125 is a slowly rotating, probably completely isolated neutron star. The absence of an optical counterpart brighter than B = 26.1 seems incompatible with a neutron star atmosphere having a chemical composition dominated by Hydrogen or Helium. UBI photometry of field stars shows astonishingly little interstellar reddening in the direction of the X-ray source. Together with the small column density detected by the ROSAT PSPC, this suggests a mean particle density in the range of n = 0.1 - 0.4 cm-3. Such average densities would imply very low velocities relative to interstellar medium (Vrel < 10 km/s) if the source were...

  12. 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.

  13. 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...

  14. 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.

  15. Comparison of fission signatures from β− delayed γ-ray and neutron emissions

    International Nuclear Information System (INIS)

    The delayed γ-ray and neutron fission signals utilized in active inspection techniques were measured simultaneously in order to directly compare their detection sensitivities. Fissionable and non-fissionable targets were irradiated by a 15-Hz pulsed bremsstrahlung beam operating at endpoint energies from 7 to 22 MeV. The fissionable mass detection limits for both these signals decreased approximately three orders of magnitude as the irradiation energy was increased with the delayed γ-ray limits 4.3–8.2 times smaller. The signals from the non-fissionable targets were consistent with the natural passive backgrounds for irradiation energies up to 16 MeV. At higher bremsstrahlung energies, there was a target independent active background in the delayed γ-ray signal that accounted for 35% of the gross yield. In addition, these higher irradiation energies resulted in products from 9Be(γ,p)8Li and 18O(γ,p)17N reactions interfering with the delayed γ-ray and neutron fission signals, respectively

  16. 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...

  17. 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.

  18. Consistent interpretation of neutron-induced charged-particle emission in silicon

    International Nuclear Information System (INIS)

    Users requesting gas production cross sections for Silicon will be confronted with serious discrepancies taking evaluated data as well as experimental ones. To clarify the accuracies achieved at present in experiments and evaluations in this paper an intercomparison of different evaluated nuclear data files has been carried out resulting in recommendations for improvements of these files. The analysis of the experimental data base also shows contradictory measurements or in most cases a lack of data. So an interpretation of reliable measured data in terms of nuclear reaction theories has been done using statistical and direct reaction mechanism models. This study results in a consistent and comprehensive evaluated data set for neutron-induced charged-particle production in Silicon which will be incorporated in file 2015 of the SOKRATOR library. (author)

  19. Experimental studies on the neutron emission spectrum and induced radioactivity of the sup 7 Li(d,n) reaction in the 20-40 MeV region

    CERN Document Server

    Baba, M; Hagiwara, M; Sugimoto, M; Miura, T; Kawata, N; Yamadera, A; Orihara, H

    2002-01-01

    To improve the data accuracy of the neutron emission spectrum of the sup 7 Li(d,n) reaction and the radioactivity ( sup 7 Be, sup 3 H, etc.) accumulated in the sup 7 Li target in IFMIF, we have measured the neutron emission spectrum and the radioactivity of sup 7 Be induced in the lithium target for 25 MeV deuterons at the Tohoku University AVF cyclotron (K=110) facility. Neutron spectra were measured with the time-of-flight (TOF) method at four laboratory angles by using a beam swinger system and a well collimated TOF channel. Induced radioactivity was measured by detecting the gamma-rays from sup 7 Be with a pure Ge detector. Experimental results are compared with other experimental data. The present result of neutron emission spectra are in qualitative agreement with other experimental data but that of sup 7 Be production was much larger than expected by the recent codes. Measurement will be extended to several incident energies up to 40 MeV.

  20. Two-proton emission in the decay of 31Ar

    International Nuclear Information System (INIS)

    Several beta-delayed two-proton branches were observed in the decay of 31Ar, the most intense ones proceeding through the isobaric analogue state (IAS) in 31Cl. The mechanism of the two-proton emission is studied via the energy and angular distributions of the two protons. Simultaneous emission of the two protons fits the present data well, sequential decays might also describe them. Independent of the decay mechanism, a spin of 5/2 for the IAS is suggested. An improved limit on the direct two-proton emission from the ground state of 31Ar is presented. (orig.)

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. Verification of nuclear data for DT neutron induced charged-particle emission reaction of light nuclei

    International Nuclear Information System (INIS)

    Double-differential cross-section (DDX) for emitted charged particles is necessary to estimate material damage, gas production and nuclear heating in a fusion reactor. Detailed measurements of the cross-sections for beryllium, carbon and fluorine, which are among the composition materials of expected fusion blankets and first walls, were carried out with a charged-particle spectrometer using a pencil-beam DT neutron source. As verification of the cross-sections evaluated in three nuclear libraries (JENDL-3.3, ENDF/B-VI and JEFF-3.1), our measured data were compared with the data evaluated in the libraries. From the comparison, the following problems were pointed out: Beryllium: Remarkable differences in energy and angular distribution for α-particles were observed between the measured data and the libraries. The estimated total cross-section for α-particle production well agreed with the libraries. Carbon: There was a discrepancy of about 20% between JENDL-3.3 and ENDF/B-VI (JEFF-3.1) for α-particle production cross-section, and no DDX for α-particles is given in the libraries. Our obtained total cross-section for α-particle production was rather consistent with ENDF/B-VI (JEFF-3.1), and the value evaluated in JENDL-3.3 seemed too large. Fluorine: The remarkable differences for DDX of protons and α-particles were observed between the obtained result and JENDL-3.3, although detailed DDX was stored only in JENDL. The obtained total cross-sections mostly supported the evaluation of ENDF/B-VI (JEFF-3.1)

  6. 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}.

  7. Broad iron emission line and kilohertz quasi-periodic oscillations in the neutron star system 4U 1636-53

    CERN Document Server

    Sanna, Andrea; Altamirano, Diego; Belloni, Tomaso; Hiemstra, Beike; Linares, Manuel

    2014-01-01

    Both the broad iron (Fe) line and the frequency of the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (LMXBs) can potentially provide independent measures of the inner radius of the accretion disc. We use XMM-Newton and simultaneous Rossi X-ray Timing Explorer observations of the LMXB 4U 1636-53 to test this hypothesis. We study the properties of the Fe-K emission line as a function of the spectral state of the source and the frequency of the kHz QPOs. We find that the inner radius of the accretion disc deduced from the frequency of the upper kHz QPO varies as a function of the position of the source in the colour-colour diagram, in accordance with previous work and with the standard scenario of accretion disc geometry. On the contrary, the inner disc radius deduced from the profile of the Fe line is not correlated with the spectral state of the source. The values of the inner radius inferred from kHz QPOs and Fe lines, in four observations, do not lead to a consisten...

  8. 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...

  9. 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.

  10. Preparation and characterization of a new set of IAEA reference air filters using instrumental neutron activation analysis, proton-induced X-ray emission and Rutherford backscattering

    Czech Academy of Sciences Publication Activity Database

    Kučera, Jan; Havránek, Vladimír; Krausová, Ivana

    2009-01-01

    Roč. 281, č. 1 (2009), s. 123-129. ISSN 0236-5731. [9th International Conference on Nuclear Analytical Methods in the Life Sciences. Lisbon, 07.09.2008-12.09.2008] Institutional research plan: CEZ:AV0Z10480505 Keywords : Reference air filters * instrumental neutron activation analysis * Proton induced X-ray emission Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.631, year: 2009

  11. Neutrons emission study in the 20Ne + 165Ho and 20Ne + 58Ni reactions at 30 MeV per nucleon

    International Nuclear Information System (INIS)

    The neutrons emission in the 20Ne + 165Ho and 20Ne + 58Ni reactions at 30 MeV per nucleon is analyzed in terms of emitter source. A particular attention is given at a source with a speed near half that those of incidental beam at a 8 MeV temperature. A comparative study of low and high energy models describing this source reveals the similitudes between the two approaches

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Distribution of Prompt Neutron Emission Probability for Fission Fragments in Spontaneous Fission of 252Cf and 244,248Cm

    Science.gov (United States)

    Vorobyev, A. S.; Dushin, V. N.; Hambsch, F.-J.; Jakovlev, V. A.; Kalinin, V. A.; Laptev, A. B.; Petrov, B. F.; Shcherbakov, O. A.

    2005-05-01

    Neutrons emitted in fission events were measured separately for each complementary fragment in correlation with fission fragment energies. Two high-efficiency Gd-loaded liquid scintillator tanks were used for neutron registration. Fission fragment energies were measured using a twin Frisch gridded ionization chamber with a pinhole collimator. The neutron multiplicity distributions were obtained for each value of the fission fragment mass and energy and corrected for neutron registration efficiency, background, and pile-up. The dependency of these distributions on fragment mass and energy for different energy and mass bins as well as mass and energy distribution of fission fragments are presented and discussed.

  17. Test of statistical models of the ν-delayed neutron emission by application of the Monte Carlo method

    International Nuclear Information System (INIS)

    Using the example of the delayed neutron spectrum of 24 s- 137I the statistical model is tested in view of its applicability. A computer code was developed which simulates delayed neutron spectra by the Monte Carlo method under the assumption that the transition probabilities of the ν and the neutron decays obey the Porter-Thomas distribution while the distances of the neutron emitting levels are Wigner distribution. Gramow-Teller ν-transitions and simply forbidden ν-transitions from the preceding nucleus to the emitting nucleus were regarded. (orig./HSI)

  18. 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.

  19. 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.

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

    International Nuclear Information System (INIS)

    Neutron energy spectra at different emission angles, between 0° and 120° 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° 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.

  1. 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.

  2. 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...

  3. Emission properties of InGaAs/GaAs heterostructures with quantum wells and dots after irradiation with neutrons

    International Nuclear Information System (INIS)

    The effect of neutron radiation on the luminescence of InGaAs/GaAs heterostructures with quantum wells and quantum dots is studied. It is found that neutron radiation results both in the formation of defects and in the radiation-induced annealing of growth-related defects. Quantum dots are more stable to neutron radiation in comparison with quantum wells. It is shown that the layer of InGaAs/GaAs quantum dots located near the surface is less sensitive to irradiation with neutrons compared with a similar layer located in the bulk. In the first case, one can observe an increase in the photoluminescence and electroluminescence intensities after irradiation with neutrons, which is related to the effects of radiation-induced annealing. The pronounced effect of elastic strains in the InGaAs/GaAs quantum wells on the extent of quenching of the photoluminescence intensity upon irradiation with neutrons is revealed. In heterostructures with quantum wells, the effect of radiation-induced annealing manifests itself in a shift of the photoluminescence peak to longer wavelengths as a result of a decrease in elastic strains upon irradiation with neutrons. Doping of the GaAs buffer layer with silicon also reduces the value of this spectral shift

  4. 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.

  5. Target mass dependence of neutron emission in collisions with 35 MeV/nucleon /sup 14/N ions

    International Nuclear Information System (INIS)

    Energy and angular distributions of neutrons emitted from collisions of 35 MeV/nucleon /sup 14/N ions with carbon, nickel, and holmium nuclei were measured. The neutrons were in coincidence with Li, Be, B, or C fragments at angles from 70 to 230 in the plane of the neutron detectors and at 150 out of this plane. Using fragment velocity bins of width corresponding to E/A = 7 MeV, we find the shapes of the neutron spectra above 15 MeV to be similar for the different targets for a given coincident fragment species, velocity bin, and angle. The cross sections are discussed in terms of moving thermal sources. In all cases the velocity and temperature parameters of the intermediate rapidity source are consistent with E/A = 8.5 +- 2.5 MeV and T = 9 +- 2.5 MeV, respectively. In agreement with a simple stripping-pickup model, the associated neutron multiplicities of this source decrease approximately linearly with the velocity of the coincident light fragments for fragment angles ≤150. Using the model to compute the mass of the source, we find that, with some fluctuations, these multiplicities are proportional to the mass. Also, the linear relationship is approximately the same for the three targets. The temperature parameters of the target-like source are between 1 and 3.5 MeV for all three targets, while the associated neutron multiplicities increase considerably with target mass. For colinear neutron-fragment coincidences for a given projectile-like isotope, the neutron multiplicities associated with the projectile-like source are about the same for all three targets, indicating that the average excitations of the parent fragments are similar

  6. 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.

  7. 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

  8. 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...

  9. 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.

  10. 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...

  11. Source characterization of Purnima Neutron Generator (PNG)

    International Nuclear Information System (INIS)

    The use of 14.1 MeV neutron generators for the applications such as elemental analysis, Accelerated Driven System (ADS) study, fast neutron radiography requires the characterization of neutron source i.e neutron yield (emission rate in n/sec), neutron dose, beam spot size and energy spectrum. In this paper, a series of experiments carried out to characterize this neutron source. The neutron source has been quantified with neutron emission rate, neutron dose at various source strength and beam spot size at target position

  12. β-delayed neutron emission of 15B, 18C, 19N, 20N, 34Al, 35Al and 39P

    International Nuclear Information System (INIS)

    The isotopes 15B, 18C, 19N, 20N, 34Al, 35Al and 39P have been produced as projectile-like fragments from the interaction of a 86Kr beam of 45 MeV/u from GANIL with a 181Ta target. Separated by the 00 magnetic analyser LISE, the nuclei are identified by means of a ΔE - E semiconductor telescope. It is surrounded, in a geometry close to 4π, by a thin plastic scintillator (NE 102) and a large volume liquid scintillator (NE 213) for the detection of betas and neutrons, respectively, from the decay of the implanted nuclei. By observation of the β-delayed neutrons, the half-lives T1/2 and neutron emission probabilities Pn have been measured. The T1/2 of 18C, 20N, 35Al, 39P and Pn of 18C, 19N, 20N, 34Al, 35Al and 39P are determined for the first time. For the isotopes 17C, 36Si, 37Si and 38P upper limits of Pn are deduced

  13. 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.

  14. International key comparison of measurements of neutron source emission rate (1999-2005): CCRI(III)-K9.AmBe

    International Nuclear Information System (INIS)

    Section III (neutron measurements) of the Comite Consultatif des Rayonnements Ionisants, CCRI, conducted a key comparison of primary measurements of the neutron emission rate of an 241Am-Be(α,n) radionuclide source. A single 241Am-Be(α,n) source was circulated to all the participants between 1999 and 2005. Eight laboratories participated - the CIAE (China), CMI (Czech Republic), KRISS (Republic of Korea), LNMRI (Brazil), LNE-LNHB (France), NIST (USA), NPL (UK) and the VNIIM (Russian Federation) - with the NPL making their measurements at the start and repeating them near the end of the exercise to verify the stability of the source. Each laboratory reported the emission rate into 4π sr together with a detailed uncertainty budget. All participants used the manganese bath technique, with the VNIIM also making measurements using an associated particle technique. The CMI, KRISS, VNIIM, and later the NPL, also measured the anisotropy of the source although this was not a formal part of the comparison. The first draft report was released in May 2006 and having been discussed and modified by the participants and subsequently reviewed by the CCRI(III), the present paper is now the final report of the comparison. (authors)

  15. Neutron emission spectroscopy results for internal transport barrier and mode conversion ion cyclotron resonance heating experiments at JET

    International Nuclear Information System (INIS)

    The effect of ion cyclotron resonance heating (ICRH) on (3He)D plasmas at JET was studied with the time of flight optimized rate (TOFOR) spectrometer dedicated to 2.5 MeV dd neutron measurements. In internal transport barrier (ITB) plasma experiments with large 3He concentrations (X(3He)>15%) an increase in neutron yield was observed after the ITB disappeared but with the auxiliary neutral beam injection and ICRH power still applied. The analysis of the TOFOR data revealed the formation of a high energy (fast) D population in this regime. The results were compared to other mode conversion experiments with similar X(3He) but slightly different heating conditions. In this study we report on the high energy neutron tails originating from the fast D ions and their correlation with X(3He) and discuss the light it can shed on ICRH-plasma power coupling mechanisms.

  16. Unique decay process: β-delayed emission of a proton and a neutron by the 11Li halo nucleus

    International Nuclear Information System (INIS)

    The neutron-rich 11Li halo nucleus is unique among nuclei with known separation energies in its ability to emit a proton and a neutron in a β-decay process. The branching ratio toward this rare decay mode is evaluated within a three-body model for the initial bound state and with Coulomb three-body final scattering states. The branching ratio should be comprised between two extreme cases, i.e., a lower bound 6x10-12 obtained with a pure Coulomb wave and an upper bound 5x10-10 obtained with a plane wave. A simple model with modified Coulomb waves provides plausible values between 0.8x10-10 and 2.2x10-10, with most probable total energies of the proton and neutron between 0.15 and 0.3 MeV.

  17. Neutron emission in heavy ion reactions as measure for the excitation energy and the transfer of linear momentum - experiments with a 4π-scintillator tank

    International Nuclear Information System (INIS)

    In the present thesis the measurement parameter 'neutrons multiplicity' is introduced for experiments with heavy ions by a 4π scintillator tank for the first time inclusive multiplicity distributions were measured in coincidence with projectile-like fragments, with light charged particles, and with heavy reaction products from fusion-like processes for 20Ne+197Au and 20Ne+238U at 220 MeV, 290 MeV, and 400 MeV. The inclusive spectra show a characteristic partition for the neutron emission from peripheral and central collision. For the peripheral collisions the components for the transfer and the projectile break-up in the projectile-like spectra can be discriminated. For the more central collisions a new method for the determination of the mean linear momentum transfer is presented. From the inelastic scattering to the complete fusion to each neutron number an impact-parameter range can be assigned. A strong correlation is observed between the mass transferred from the projectile to the target, the momentum, and the energy transfer. With increasing incident energy the mean momentum transfer becomes more incomplete. For the missing momentum transfer preequilibrium particles are responsible the contribution of which in the neutron number spectra for the light evaporated particles can be well separated from the break-up respectively evaporation component. Angular distributions of fission fragments could by this be measured for the first time in dependence on the linear momentum transfer. The slope of the anisotropy also indicates a strong correlation between the momentum and angular momentum transfer. The latter shows a saturation at high spins. The determination of effective moments of inertia of the fissioning nuclei and their comparison with the predictions of the model of a rotating liquid drop becomes possible for differentially posed spin windows. (orig.)

  18. 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

  19. 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

  20. 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.

  1. Preliminary measurements of the 14 MeV neutron emission from Frascati tokamak plasma by activation techniques

    International Nuclear Information System (INIS)

    The 1.01 MeV triton burnup has been investigated in the FT (Frascati tokamak) plasma by means of the activation technique. The 14 MeV neutrons produced by triton burnup have been measured with the activation reaction Cu63(n,2n)Cu62 which has a threshold of 10.9 MeV. (orig.)

  2. 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...

  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. Study of α and triton particles emission in Uranium 235, Uranium 238, Plutonium 239 fast neutron fission

    International Nuclear Information System (INIS)

    Fast neutrons up to 2.5 MeV have been used to induce light particle accompanied fission in 235U, 238U and 239Pu targets. The energy spectra and relative intensities of 3H and 4He have been measured with a ΔE-E telescope. Absolute particle yields were derived from the number of 4He particle per 1000 binary fissions of 235U and 239Pu induced by thermal neutrons measured under the same geometrical conditions. We observe that all the energy distributions are well reproduced by gaussian lineshape, the mean energies of which remain constant while varying the neutron incident energy. (For all nuclei, the 4He mean energies lie close to 16 MeV and the corresponding energies for 3H particle at about 8-9 MeV). The production rates of 3H and 4He show a decrease of about 30% between thermal energy and En = 2 MeV with a small maximum at En = 1 MeV. Conversely the 3H and 4He particle yields obtained in fast neutron fission of 239U remain constant between En = 1.5 MeV and En = 2.5 MeV. Some possible explanation for these observations are briefly and qualitatively explored

  5. 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.

  6. 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

  7. 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...

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

    International Nuclear Information System (INIS)

    Thermal neutron detector based on films of 10B4C have been developed as an alternative to 3He 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 α emitters, however, the background from α 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 α 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 background by two orders of magnitude. A new large-area prototype has been built incorporating these modifications

  9. High-energy particle production in solar flares (SEP, gamma-ray and neutron emissions). [solar energetic particles

    Science.gov (United States)

    Chupp, E. L.

    1987-01-01

    Electrons and ions, over a wide range of energies, are produced in association with solar flares. Solar energetic particles (SEPs), observed in space and near earth, consist of electrons and ions that range in energy from 10 keV to about 100 MeV and from 1 MeV to 20 GeV, respectively. SEPs are directly recorded by charged particle detectors, while X-ray, gamma-ray, and neutron detectors indicate the properties of the accelerated particles (electrons and ions) which have interacted in the solar atmosphere. A major problem of solar physics is to understand the relationship between these two groups of charged particles; in particular whether they are accelerated by the same mechanism. The paper reviews the physics of gamma-rays and neutron production in the solar atmosphere and the method by which properties of the primary charged particles produced in the solar flare can be deduced. Recent observations of energetic photons and neutrons in space and at the earth are used to present a current picture of the properties of impulsively flare accelerated electrons and ions. Some important properties discussed are time scale of production, composition, energy spectra, accelerator geometry. Particular attention is given to energetic particle production in the large flare on June 3, 1982.

  10. 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

  11. Investigation of the dependence of deformation mechanisms on solute content in polycrystalline Mg–Al magnesium alloys by neutron diffraction and acoustic emission

    International Nuclear Information System (INIS)

    Highlights: • The stress necessary for both twin nucleation and growth increases with increasing Al content. • The activity of prismatic 〈a〉 slip increases with the solute content. • The pyramidal 〈c + a〉 slip plays a significant role in the plasticity of Mg–9 wt.% Al alloy. - Abstract: Influence of aluminium content on the deformation mechanisms in Mg–Al binary alloys has been studied using in-situ neutron diffraction and acoustic emission technique. It is shown that the addition of the solute increases the critical resolved shear stress for twinning. Further, the role of aluminium on the solid solution hardening of the basal plane and softening of non-basal planes are discussed using results of the convolutional multiple peak profile analysis of diffraction patterns. The results indicate that the density of both prismatic 〈a〉 and pyramidal 〈c + a〉 dislocations increases with increasing alloying content

  12. 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)

  13. Investigation of the dependence of deformation mechanisms on solute content in polycrystalline Mg–Al magnesium alloys by neutron diffraction and acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    Máthis, K. [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic); Čapek, J., E-mail: jan.capek@centrum.cz [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic); Clausen, B. [Los Alamos National Laboratory, Lujan Neutron Scattering Center, Los Alamos, NM 87545 (United States); Krajňák, T. [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic); Nagarajan, D. [Advanced Forming Research Centre, University of Strathclyde, 85 Inchinnan Drive, Renfrew PA4 9LJ, Glasgow (United Kingdom)

    2015-09-05

    Highlights: • The stress necessary for both twin nucleation and growth increases with increasing Al content. • The activity of prismatic 〈a〉 slip increases with the solute content. • The pyramidal 〈c + a〉 slip plays a significant role in the plasticity of Mg–9 wt.% Al alloy. - Abstract: Influence of aluminium content on the deformation mechanisms in Mg–Al binary alloys has been studied using in-situ neutron diffraction and acoustic emission technique. It is shown that the addition of the solute increases the critical resolved shear stress for twinning. Further, the role of aluminium on the solid solution hardening of the basal plane and softening of non-basal planes are discussed using results of the convolutional multiple peak profile analysis of diffraction patterns. The results indicate that the density of both prismatic 〈a〉 and pyramidal 〈c + a〉 dislocations increases with increasing alloying content.

  14. Study of the delayed neutron emission through the time-of-flight method. Application to 49K, 50K and 51K

    International Nuclear Information System (INIS)

    This work is dedicated to the study of the emission of delayed neutrons observed in the decay of 49K, 50K and 51K. Spectroscopic data are non-existent for these 3 isotopes, so we have had to design a specific detection system based on a large-surface scintillation counter. A series of n-γ coincidence measurement has allowed us to determine the energy levels of the non-bound states of 49Ca, 50Ca and 51Ca and to establish the nature of the beta transitions (K → Ca). We have measured the energy of the delayed neutrons through the time-of-flight method. Our results are consistent with the model of the p-n states based on the Bansac-French's works. This model shows that the non-bound states of the calcium isotopes discovered in the experiment are represented by simple configurations of the (sd)-1 (fp)n type. (A.C.)

  15. 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.

  16. 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 ...

  17. 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

  18. 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

  19. 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.)

  20. Fission barrier, damping of shell correction and neutron emission in the fission of A$\\sim$200

    OpenAIRE

    Mahata, K; Kailas, S; S. S. Kapoor

    2015-01-01

    Decay of $^{210}$Po compound nucleus formed in light and heavy-ion induced fusion reactions has been analyzed simultaneously using a consistent prescription for fission barrier and nuclear level density incorporating shell correction and its damping with excitation energy. Good description of all the excitation functions have been achieved with a fission barrier of 21.9 $\\pm$ 0.2 MeV. For this barrier height, the predicted statistical pre-fission neutrons in heavy-ion fusion-fission are much ...

  1. 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)

  2. On the origin of sub-TeV gamma-ray pulsed emission from rotating neutron stars

    CERN Document Server

    Bednarek, W

    2012-01-01

    Intriguing sub-TeV tails in the pulsed $\\gamma$-ray emission from the Crab pulsar have been recently discovered by the MAGIC and VERITAS Collaborations. They were not clearly predicted by any pulsar model. It is at present argued that this emission is produced by electrons in the Inverse Compton process occurring either in the outer gap of the pulsar magnetosphere or in the pulsar wind region at some distance from the light cylinder. We analyse another scenario which is consistent with the basic features of this enigmatic emission. It is proposed that this emission is caused by electrons accelerated very close to the light cylinder where the $e^\\pm$ plasma can not saturate induced huge electric fields. Electrons reach energies sufficient for production of hard $\\gamma$-ray spectra in the curvature radiation process. Due to different curvature radii of the leading and trailing magnetic field lines, the $\\gamma$-ray spectra from separate pulses should extend to different maximum energies. The scenario can also ...

  3. 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}.

  4. Neutron emission effects on final fragments mass and kinetic energy distribution from low energy fission of 234U

    OpenAIRE

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

    2008-01-01

    Las mediciones sobre la desviación estándar de la distribución de energía cinetica final (σe) en función de la masa final (m) de los fragmentos de la fisión de baja energía del 234U, hechas por Belhafaf et al., presentan un pico alrededor de m = 109 y otro alrededor de m = 122. Los autores atribuyen el primer pico a la evaporación de un elevado número de neutrones alrededor del correspondiente número másico, es decir que no hay un pico en la desviación estándar de la distribución de ener...

  5. Neutrino and Electron-positron Pair Emission from Phase-induced Collapse of Neutron Stars to Quark Stars

    CERN Document Server

    Cheng, K S

    2010-01-01

    We study the energy released from phase-transition induced collapse of neutron stars, which results in large amplitude stellar oscillations. To model this process we use a Newtonian hydrodynamic code, with a high resolution shock-capturing scheme. The physical process considered is a sudden phase transition from normal nuclear matter to a mixed phase of quark and nuclear matter. We show that both the temperature and the density at the neutrinosphere oscillate with time. However, they are nearly 180 degree out of phase. Consequently, extremely intense, pulsating neutrino/antineutrino and leptonic pair fluxes will be emitted. During this stage several mass ejecta can be ejected from the stellar surface by the neutrinos and antineutrinos. These ejecta can be further accelerated to relativistic speeds by the electron/positron pairs, created by the neutrino and antineutrino annihilation outside the stellar surface. We suggest that this process may be a possible mechanism for short Gamma-Ray Bursts.

  6. 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)

  7. 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

  8. Effects of T-odd asymmetry of the emission of light charged particles and photons during fission of heavy nuclei by polarized neutrons

    International Nuclear Information System (INIS)

    The new physical effects of T-odd asymmetry of the emission of light charged particles (LCPs) during the ternary fission of some heavy nuclei by cold polarized neutrons have been experimentally studied. The coefficients of triple scalar and vector correlation of the pulses of light particles and fission fragments (TRI effect) and the fivefold correlation of the same vectors (ROT effect) have been measured. These effects are believed to be caused by the rotation of polarized fissioning system around its polarization direction. The treatment of the experimental data for LCPs in the framework of this hypothesis leads to a good agreement between the calculation results and experimental data. The calculated value of the angle of rotation of the fission axis in the ternary fission of the polarized fissioning 236U* compound nucleus was used to process the results of measuring the ROT effect for γ photons from binary-fission fragments of the same nucleus. A satisfactory description of these experimental data is obtained which serves a convincing confirmation of the rotation hypothesis.

  9. 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

  10. 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

  11. 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.

  12. Laser isotope and isomer separation of neutron-rich Ag-isotopes

    International Nuclear Information System (INIS)

    In a recent experiment at CERN/ISOLDE, we have used laser isotope separation to isolate heavy Ag nuclides including the N=82 r-process 'waiting-point' isotope 129Ag. A half-life of 46(+5/-9) ms for the πg9/2 ground-state decay of 129Ag could be determined using beta-delayed neutron counting. In the case of 126Ag and 128Ag decays, γ-spectroscopic techniques with time resolving multi-channel-analysers were used to identify the 2+ and 4+ levels in 126Cd and 128Cd, respectively. The hyperfine splitting of the atomic transition in Ag which is used for laser ionization has made possible an isomer selection through which the β- and γ-decay of the high-spin isomer of 122Ag were observed while suppressing the ionization of the low-spin isomer

  13. Study of light neutron-deficient nuclei with the LISE3 spectrometer

    International Nuclear Information System (INIS)

    Neutron-deficient isotopes with Z=21 to 26 are produced among the projectile-like fragments of an intense 58Ni GANIL beam of 69 MeV/nucleon. The nuclei selected by the upgraded LISE3 spectrometer are identified and implanted in a silicon detector telescope where their emitted charged particles are measured. 43Cr, 47Fe and 46Fe isotopes are synthesized for the first time, whereas 45Fe, 45Mn and 42V remain unobserved. The half-lives of 43Cr and 46Mn are measured, and the analysis of their beta-delayed proton spectra leads, through the isobaric multiplet mass equation, to an experimental value for their excess mass. (author) 13 refs., 5 figs., 3 tabs

  14. Neutron-fragment and Neutron-neutron Correlations in Low-energy Fission

    Science.gov (United States)

    Lestone, J. P.

    2016-01-01

    A computational method has been developed to simulate neutron emission from thermal-neutron induced fission of 235U and from spontaneous fission of 252Cf. Measured pre-emission mass-yield curves, average total kinetic energies and their variances, both as functions of mass split, are used to obtain a representation of the distribution of fragment velocities. Measured average neutron multiplicities as a function of mass split and their dependence on total kinetic energy are used. Simulations can be made to reproduce measured factorial moments of neutron-multiplicity distributions with only minor empirical adjustments to some experimental inputs. The neutron-emission spectra in the rest-frame of the fragments are highly constrained by ENDF/B-VII.1 prompt-fission neutron-spectra evaluations. The n-f correlation measurements of Vorobyev et al. (2010) are consistent with predictions where all neutrons are assumed to be evaporated isotropically from the rest frame of fully accelerated fragments. Measured n-f and n-n correlations of others are a little weaker than the predictions presented here. These weaker correlations could be used to infer a weak scission-neutron source. However, the effect of neutron scattering on the experimental results must be studied in detail before moving away from a null hypothesis that all neutrons are evaporated from the fragments.

  15. 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.

  16. The neutron star zoo

    Science.gov (United States)

    Harding, Alice K.

    2013-12-01

    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.

  17. 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.

  18. Half-life and delayed neutron emission probabilities measurement of 44S,45-47Cl spectrometer: their implication in the 48Ca/46Ca ratio understanding in the solar system

    International Nuclear Information System (INIS)

    After a detailed description of the simulation program LISE, experimental measurements of the radioactive decay (half-lives and neutron delayed emission probabilities) of the neutron rich nuclei 44S, 45Cl, 47Cl are presented. The comparison between these results and the theoretical predictions clearly shows that mass and deformation measurements of these nuclei are very important to determine precisely the radioactive decay parameters necessary to astrophysics. Effectively, these ones are used in star evolution models to understand the elements abundance curve of the solar system. Even if the shape of this curve is well reproduced, some anomalies subsist. The experimental results seem to show that, with the constraints they bring, a double r process in low-mass supernovae of type II can explain twice the isotopic anomalies and the shape of the elements abundance curve

  19. 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.

  20. 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)

  1. 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.

  2. Neutron reflectometry

    International Nuclear Information System (INIS)

    Neutron research where reflection, refraction, and interference play an essential role is generally referred to as 'neutron optics'. The neutron wavelength, the scattering length density and the magnetic properties of the material determine the critical angle for total reflection. The theoretical background of neutron reflection, experimental methods and the interpretation of reflection data are presented. (K.A.)

  3. 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

  4. 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...

  5. Neutron star equation of state

    International Nuclear Information System (INIS)

    Experimental information concerning the equation of state in neutron stars is lacking, because of the necessary extrapolations in both density and neutron excess from the nearly symmetric nuclear matter observed in nuclei. However, the combination of new developments in the theory of neutron star structure and in astronomical observations provides important constraints. From a theoretical perspective, it is argued that the extrapolation in neutron excess is more crucial for neutron star structure than is the density extrapolation. For example, the radius of neutron stars is primarily a function of the pressure of matter in the vicinity of nuclear matter density, which is essentially determined by the isospin properties of dense matter. In the absence of extreme softening in the dense matter equation of state, a measurement of the radius of a neutron star more accurate than about 1 km will usefully constrain the equation of state. In addition, the moment of inertial and the binding energy of neutron stars are nearly universal functions of the star's compactness. The potential constraints that can be deduced from observations of thermal emission from young neutron stars, neutrinos from newly born neutron stars, Quasi-Periodic Oscillations from X-ray emitting neutron stars in binaries, and glitches from pulsars are discussed

  6. Experimental studies of nuclides far from stability with the TRISTAN II fission-product separator at the Brookhaven National Laboratory (Yrast bands; delayed-neutron spectra). Final report, January 1, 1980-November 30, 1982

    International Nuclear Information System (INIS)

    The research program under this contract consisted of two projects; one was the study of yrast bands and the other the study of energy spectra of beta-delayed neutrons. Both utilized the TRISTAN mass separaotr at Brookhaven National Laboratory. The nuclides of interest for the yrast band project were ot produced at TRISTAN during the period of the contract, so effort was limited to planning and to presentation of papers. The neutron project required the design, construction, testing, and calibration of apparatus that is not commercially available. Neutron detectors were later made available onloan. The time-of-flight method was used, beta and neutron signals from scintillators detectors providing start and stop signals. He-3 gas and Li-6 glass scintillators were used for neutrons, plastic for betas. The best timing resolution was 2.7 nsec FWHM; including geometrical contributions,neutron FWHM energy resolution as good as 2.7% at 14 keV was obtained at 50 cm flight path. This is sufficient to deduce the natural line width of the 14 keV resonance in Sr-95. Background neutrons and gamma rays limit the system sensitivity at present, but improvements appear feasible that will permit deduction of leveldensities and in some cases widths of a number of neutron-rich nuclides that are inaccessible to study by any other probe. The data bear on optical models and neutron cross sections for such nuclides

  7. Neutron Flux Measurements of a D-T Neutron Generator

    International Nuclear Information System (INIS)

    A new D-T sealed-tube neutron generator model ING-07T (VNIIA, Russia) was installed at Soreq Nuclear Research Center. A deuterium (D) beam (a minimum 15 mm diameter) irradiates a target containing tritium (T) and via the D + T -> n+4He reaction generates neutrons at En ∼ 14.2 MeV. The neutron generator ion source is of a penning ion source type and allows continuous beam operation. The neutron production can be regulated by the acceleration voltage and ion source parameters. The specified neutron emission rate is 1*109 n/sec. Neutrons are emitted almost isotropically in space. The advantage of the sealed-tube is that it eliminates the use of a vacuum pump. The neutron generator is contained in a 44 cm long aluminum cylinder with a diameter of 19 cm. The generator is connected by a 50 m long cable to a control unit (laptop). A known method for calibration of a 14 MeV neutron flux is performed by copper activation, using the fast neutron reaction 63Cu(n,2n)62Cu, having a neutron energy threshold of En = 10.8 MeV. 62Cu decays by p+ emission (7% = 9.67 min; Pp+ = 97.43%), Photons are produced from positron-electron annihilation (511 keV) at 194.86% (2Ppt) of the disintegrations. In this paper we present a series of measurements performed in order to calibrate the neutron emission rate of the D-T generator and investigate the profile distribution of the flux

  8. 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...

  9. 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

  10. 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.

  11. 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 \

  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. The Electromagnetic Spectrum of Neutron Stars

    CERN Document Server

    Baykal, Altan; Inam, Sitki C; Grebenev, Sergei

    2005-01-01

    Neutron stars hold a central place in astrophysics, not only because they are made up of the most extreme states of the condensed matter, but also because they are, along with white dwarfs and black holes, one of the stable configurations that stars reach at the end of stellar evolution. Neutron stars posses the highest rotation rates and strongest magnetic fields among all stars. They radiate prolifically, in high energy electromagnetic radiation and in the radio band. This book is devoted to the selected lectures presented in the 6th NATO-ASI series entitled "The Electromagnetic Spectrum of Neutron Stars" in Marmaris, Turkey, on 7-18 June 2004. This ASI is devoted to the spectral properties of neutron stars. Spectral observations of neutron stars help us to understand the magnetospheric emission processes of isolated radio pulsars and the emission processes of accreting neutron stars. This volume includes spectral information from the neutron stars in broadest sense, namely neutrino and gravitational radiat...

  14. 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

  15. Neutron emission in the spallation reactions of 1 GeV protons on a thick lead target surrounded by uranium blanket

    International Nuclear Information System (INIS)

    A thick lead target surrounded by uranium blanket was irradiated with 1 GeV protons. Measurement of the produced neutron field was performed by means of threshold reactions in activation foils. The experimental results were compared with Monte Carlo calculations performed with the MCNPX 2.6 C code

  16. 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).

  17. 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.

  18. Additional evidence of nuclear emissions during acoustic cavitation.

    Science.gov (United States)

    Taleyarkhan, R P; Cho, J S; West, C D; Lahey, R T; Nigmatulin, R I; Block, R C

    2004-03-01

    Time spectra of neutron and sonoluminescence emissions were measured in cavitation experiments with chilled deuterated acetone. Statistically significant neutron and gamma ray emissions were measured with a calibrated liquid-scintillation detector, and sonoluminescence emissions were measured with a photomultiplier tube. The neutron and sonoluminescence emissions were found to be time correlated over the time of significant bubble cluster dynamics. The neutron emission energy was less than 2.5 MeV and the neutron emission rate was up to approximately 4 x 10(5) n/s. Measurements of tritium production were also performed and these data implied a neutron emission rate due to D-D fusion which agreed with what was measured. In contrast, control experiments using normal acetone did not result in statistically significant tritium activity, or neutron or gamma ray emissions. PMID:15089363

  19. 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。

  20. Detector to measure neutron pulses of low yield from plasma pinch devices

    International Nuclear Information System (INIS)

    Neutron emission from pinch plasma focus devices has been found ranging from 107 neutrons per pulse with 1kJ driver up to 1012 neutrons per pulse with 1000kJ driver. The region corresponding to total neutron yield of less than 106 neutron per pulse, is unexplored. The consequence of this is that measurement of very low levels of fast neutron emission becomes very important to consider. A conventional technique is adapted to measure neutron emission produced by very short, low yield neutron pulses. This method uses a 3He proportional counter surrounded by a paraffin moderator, to measurement neutron yield (≤106 neutron/pulse) generated in a fast and very small plasma focus device designed to operate with energies of tens to hundred joules. Neutron yields as low as 5x104 neutrons per pulse were measured (author)

  1. 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)

  2. Quaking Neutron Stars

    CERN Document Server

    Franco, L M; Epstein, R I; Franco, Lucia M.; Link, Bennett; Epstein, Richard I.

    1999-01-01

    Gravitational, magnetic and superfluid forces can stress the crust of an evolving neutron star. Fracture of the crust under these stresses could affect the star's spin evolution and generate high-energy emission. We study the growth of strain in the crust of a spinning down, magnetized neutron star and examine the initiation of crust cracking (a {\\em starquake}). In preliminary work (Link, Franco & Epstein 1998), we studied a homogeneous model of a neutron star. Here we extend this work by considering a more realistic model of a solid, homogeneous crust afloat on a liquid core. In the limits of astrophysical interest, our new results qualitatively agree with those from the simpler model: the stellar crust fractures under shear stress at the rotational equator, matter moves to higher latitudes and the star's oblateness is reduced. Magnetic stresses favor faults directed toward the magnetic poles. Thus our previous conclusions concerning the star's spin response still hold; namely, asymmetric redistribution...

  3. 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 ...

  4. 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.

  5. 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)

  6. 2-D Spatial Distribution of D-D and D-T Neutron Emission in JET ELMy H-mode Plasmas with Tritium Puff

    Czech Academy of Sciences Publication Activity Database

    Bonheure, G.; Mlynář, Jan; Bertalot, L.; Conroy, S.; Murari, A.; Popovichev, S.; Zabeo, L.

    Tarragona : EPS, 2005, P-1.083. ISBN 2-914771-24-X. - (Europhysics Conference Abstracts ECA Vol. 29C). [EPS Conference on Plasma Physics and Controlled Fusion/32nd./. Tarragona (ES), 27.06.2005-01.07.2005] Institutional research plan: CEZ:AV0Z20430508 Keywords : fusion * JET * tritium transport * neutrons diagnostics * tomography Subject RIV: BL - Plasma and Gas Discharge Physics http://eps2005.ciemat.es/papers/pdf/P1_083.pdf

  7. 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...

  8. 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)

  9. Absolute determination of the neutron source yield using melamine as a neutron detector

    Science.gov (United States)

    Ciechanowski, M.; Bolewski, A., Jr.; Kreft, A.

    2015-01-01

    A new approach to absolute determination of the neutron source yield is presented. It bases on the application of melamine (C3H6N6) to neutron detection combined with Monte Carlo simulations of neutron transport. Melamine has the ability to detect neutrons via 14N(n, p)14C reaction and subsequent determination of 14C content. A cross section for this reaction is relatively high for thermal neutrons (1.827 b) and much lower for fast neutrons. A concentration of 14C nuclei created in the irradiated sample of melamine can be reliably measured with the aid of the accelerator mass spectrometry (AMS). The mass of melamine sufficient for this analysis is only 10 mg. Neutron detection is supported by Monte Carlo simulations of neutron transport carried out with the use of MCNP-4C code. These simulations are aimed at computing the probability of 14C creation in the melamine sample per the source neutron. The result of AMS measurements together with results of MCNP calculations enable us to determine the number of neutrons emitted from the source during the irradiation of melamine. The proposed method was applied for determining the neutron emission from a commercial 252Cf neutron source which was independently calibrated. The measured neutron emission agreed with the certified one within uncertainty limits. The relative expanded uncertainty (k=2) of the absolute neutron source yield determination was estimated at 2.6%. Apart from calibration of radionuclide neutron sources the proposed procedure could facilitate absolute yield measurements for more complex sources. Potential applications of this methodology as it is further developed include diagnostics of inertial confinement fusion and plasma-focus experiments, calibration of neutron measurement systems at tokamaks and accelerator-based neutron sources as well as characterization of neutron fields generated in large particle detectors during collisions of hadron beams.

  10. Neutron Experimental Facilities for Nuclear Data Measurements at IPPE

    International Nuclear Information System (INIS)

    Neutron facilities used for the measurements of nuclear data at Institute of Physics and Power Engineering are presented. These facilities are created on the basis of six accelerators (two cascade generators, two Van-de-Graaff and two tandem Van-de-Graaff accelerators produced the continuous and pulsed beams of protons and deuterons in the energy range from 0.3 MeV to 15 MeV) and allow to obtain neutron sources with energy from 30 keV to 30 MeV. The measurements of neutron - charge particle, differential elastic and inelastic neutron scattering, neutron fission, neutron capture cross-sections, yields of the fission products and delayed neutrons, neutron emission cross-sections in various reactions and neutron leakage spectra from spherical samples for testing of neutron libraries are carried out. The results of the studies carried out are well-known in the leading neutron centers. (author)

  11. Linear stochastic neutron transport theory

    International Nuclear Information System (INIS)

    A new and direct derivation of the Bell-Pal fundamental equation for (low power) neutron stochastic behaviour in the Boltzmann continuum model is given. The development includes correlation of particle emission direction in induced and spontaneous fission. This leads to generalizations of the backward and forward equations for the mean and variance of neutron behaviour. The stochastic importance for neutron transport theory is introduced and related to the conventional deterministic importance. Defining equations and moment equations are derived and shown to be related to the backward fundamental equation with the detector distribution of the operational definition of stochastic importance playing the role of an adjoint source. (author)

  12. Neutron sources

    International Nuclear Information System (INIS)

    As neutron scattering experiments have grown more and more demanding with respect to resolution and quality, it became more and more necessary to include the neutron source itself in the design of an experimental setup. In this sense the generic representation of a neutron scattering arrangement includes the primary neutron source and the associated spectrum shifter (or moderator). In fact, the design of a modern neutron source will start from a set of users requirements and will proceed 'inwards' through a selection of the moderators (spectrum shifters) to the primary source best suited to meet these often conflicting needs. This paper aims at explaining the options source designers have to match the neutron source performance to the users' demands. (author)

  13. 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.

  14. 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)

  15. 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.

  16. 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

  17. Neutron dosimetry

    International Nuclear Information System (INIS)

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq 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-1 and 0,5 μSv s-1. A calibrated 50 nSv s-1 thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the 241 Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold 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,α) 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 kVpp cm-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) 104 tracks cm-2 mSv-1 for thermal neutrons, (9±3) 102 tracks cm-2 mSV-1 for intermediate neutrons and (26±4) tracks cm-2 mSv-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 sufficiently sensitive to thermal and intermediate neutrons but fast neutron monitoring ar radiological protection level

  18. 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.

  19. 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.

  20. 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...

  1. Micromegas neutron beam monitor neutronics.

    Science.gov (United States)

    Stephan, Andrew C; Miller, Laurence F

    2005-01-01

    The Micromegas is a type of ionising radiation detector that consists of a gas chamber sandwiched between two parallel plate electrodes, with the gas chamber divided by a Frisch grid into drift and amplification gaps. Investigators have applied it to a number of different applications, such as charged particle, X-ray and neutron detection. A Micromegas device has been tested as a neutron beam monitor at CERN and is expected to be used for that purpose at the Spallation Neutron Source (SNS) under construction in Oak Ridge, TN. For the Micromegas to function effectively as neutron beam monitor, it should cause minimal disruption to the neutron beam in question. Specifically, it should scatter as few neutrons as possible and avoid neutron absorption when it does not contribute to generating useful information concerning the neutron beam. Here, we present the results of Monte Carlo calculations of the effect of different types of wall materials and detector gases on neutron beams and suggest methods for minimising disruption to the beam. PMID:16381746

  2. 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

  3. 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)

  4. 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.

  5. Neutron gun

    International Nuclear Information System (INIS)

    The neutron gun combines a new core ion source of the cold type based on X-ray ionization and new cold type of neutron source working with core ion generation. The neutrons are formed from the impact of core ions on the negatively charged anode. Based on a new conversion function, the function of the positive anode becomes analogous to the beta-unstable decomposition of a neutron. A core ion and neutron amplifier in the sense of amplifying the number is derived from the beta-unstable neutron decomposition, in order to raise the output of a gun in pulsed operation by using the number amplification in the intervals between the pulses. The method of construction is simple and cheap, the equipment has purely linear acceleration or operation with circular acceleration with linear pre-acceleration as an alternative. Purely linear operation should be sufficient for medical applications, e.g. for neutron photography to replay X-ray photography and particularly for neutron scalpels in the surgical treatment of tumours. (orig./HP)

  6. Neutron transport

    International Nuclear Information System (INIS)

    This bibliographical note presents a reference book which addresses the study of neutron transport in matter, the study of conditions for a chain reaction and the study of modifications of matter composition due to nuclear reactions. This book presents the main nuclear data, their measurement, assessment and processing, and the spallation. It proposes an overview of methods applied for the study of neutron transport: basic equations and their derived forms, deterministic methods and Monte Carlo method of resolution of the Boltzmann equation, methods of resolution of generalized Bateman equations, methods of time resolution of space kinetics coupled equations. It presents the main calculation codes, discusses the qualification and experimental aspects, and gives an overview of neutron transport applications: neutron transport calculation of reactors, neutron transport coupled with other disciplines, physics of fuel cycle, criticality

  7. 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.

  8. 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.

  9. 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...

  10. 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...

  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. 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

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. Neutron Scattering

    International Nuclear Information System (INIS)

    The neutron probe is a standard tool for measuring soil water content. This article provides an overview of the underlying theory, describes the methodology for its calibration and use, discusses example applications, and identifies the safety issues. Soil water makes land-based life possible by satisfying plant water requirements, serving as a medium for nutrient movement to plant roots and nutrient cycling, and controlling the fate and transport of contaminants in the soil environment. Therefore, a successful understanding of the dynamics of plant growth, nutrient cycling, and contaminant behavior in the soil requires knowledge of the soil water content as well as its spatial and temporal variability. After more than 50 years, neutron probes remain the most reliable tool available for field monitoring of soil water content. Neutron probes provide integrated measurements over relatively large volumes of soil and, with proper access, allow for repeated sampling of the subsurface at the same locations. The limitations of neutron probes include costly and time-consuming manual operation, lack of data automation, and costly regulatory requirements. As more non-radioactive systems for soil water monitoring are developed to provide automated profiling capabilities, neutron-probe usage will likely decrease. Until then, neutron probes will continue to be a standard for reliable measurements of field water contents in soils around the globe

  18. 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

  19. 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.

  20. Neutron measurements in search of cold fusion

    International Nuclear Information System (INIS)

    We have conducted a research for neutron emission from cold fusion systems of the electrochemical type and, to a lesser extent, the high-pressure gas cell type. Using a high-efficiency well counter and an NE 213 scintillator, the experiments were conducted on the earth's surface and in a shielded cave approximately 50 ft underground. After approximately 6500 h of counting time, we have obtained no evidence for cold fusion processes leading to neutron production. However, we have observed all three types of neutron data that have been presented as evidence for cold fusion: large positive fluctuations in the neutron counting rate, weak peaks near 2.5 MeV in the neutron energy spectrum, and bursts of up to 145 neutrons in 500-μs intervals. The data were obtained under circumstances that clearly show our results to be data encountered as a part of naturally occurring neutron background, which is due primarily to cosmic rays. Thus, observing these types of data does not, of itself, provide evidence for the existence of cold fusion processes. Artifacts in the data that were due to counter misbehavior were also to lead to long-term ''neutron bursts'' whose time duration varied from several hours to several days. We conclude that any experiments which attempt to observe neutron emission must include strong steps to ensure that the experiments deal adequately with both cosmic-ray processes and counter misbehavior. 13 refs., 14 figs