25 research outputs found
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Study of the characteristics of high-energy proton-induced gamma ray and neutron emission from materials that imitate surface of planets.
A proposed ISTC Project is discussed in the present paper. The proposal is aimed at experiments to determine the space-energy characteristics of the neutron and gamma ray emission fields generated by 0.2-0.8 GeV proton irradiation of thick targets composed of various elements. At present, reliable data on physical properties of secondary radiation from materials irradiated by intennediate- and high-energy protons for some fundamental and applied researches in astrophysics, space physics, atomic and nuclear physics, as well as for designing and operating the latest accelerators are lacking
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Complex particle and light fragment emission in the cascade-excitation model of nuclear reactions
A brief description of our improvements and refinements that led from the CEM95 version of the Cascade-Exciton Model (CEM) code to CEM97 and to CEM2k is given. The increased accuracy and predictive power of the code CEM2k are shown by several examples. To describe fission and light-fragment (heavier than {sup 4}He) production, the CEM2k code has been merged with the GEM2 code of Furihata. We present some results on proton-induced fragmentation and fission reactios predicted by this extended version of CEM2k. We show that merging CEM2k with GEM2 allows us to describe many fission and fragmentation reactions in addition to the spallation reactions which are already relatively well described
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Recent developments of the CEM2K and LAQGSM codes.
Recent developments of the Cascade-Exciton Model (CEM) of nuclear reactions are briefly described. The improved cascade-exciton model as implemented in the code CEM97 [l] differs from the CEM95 version [4] by incorporating new approximations for the elementary cross sections used in the cascade, using more precise {approx} values for nuclear masses and pairing energies, using corrected systematics for the I level-density parameters, and several other refinements. Algorithms used in many i subroutines have been improved, decreasing the computing time by up to a factor of 6 for heavy targets. A number of further recent improvements and changes to CEM97, motivated by new data on isotope production measured at GSI will be presented. This leads us to CEM2k [2], a new version of the CEM code. CEM2k has a longer cascade stage, less preequilibrium emission, and evaporation from more highly excited compound nuclei compared to earlier versions. CEM2k also has other improvements and allows us to better model neutron, radionuclide, and gas production in Accelerator Transmutation of nuclear Wastes (ATW) spallation targets. The improved CEM97 code was recently used both to study fundamental nuclear physics problems like the role of nuclear medium effects in transport of 7r mesons in nuclei [5] and fission processes at intermediate energies [6], and was incorporated in the well known transport code MCNPX (LANL) to solve applied problems. The CEM95 version [4] of the CEM was incorporated in the MARS (FNAL) and CALOR95 (ORNL) transport codes, and its preequilibrium part was incorporated in many other transport codes like GEANT4 (CERN, see, e.g., [7]), HETC-3STEP (JAERI), HADRON (IHEP, Protvino), CASCADE (JINR, Dubna), SONET (RPCPI, Minsk), etc. The latest version of the CEM code, CEM2k, is still under development. The increased accuracy and predictive power of the code CEM2k will be shown by several examples. Further necessary work will be outlined
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DEVELOPMENT AND VALIDATION OF THE 7LI(P,N) NUCLEAR DATA LIBRARY AND ITS APPLICATION IN MONITORING OF INTERMEDIATE ENERGY NEUTRONS
Systematics have been created for neutron spectra from the 7Li(p,n) reaction at 0 degrees in the 50-200 MeV proton energy region. The available experimental data in the continuum part of the spectra show satisfactory overall agreement with a representation based on the phase-space distribution corresponding to the three-body breakup process 7Li(p,n 3He){alpha}, with empirical correction factors, which depend regularly on incident energy. Validation of the systematics included folding of the predicted neutron spectra with standard 238U neutron fission cross section. Modeled in this way distributions of neutron-induced fission events agree reasonably with experimental data. KEYWORDS: quasi-monoenergetic neutron beam, monitoring, nuclear data library, MCNPX code