Neutron productions in the fragmentation of relativistic heavy nuclei and formation of a beam of high-energy neutrons
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EMENTARY PARTICLES AND FIELDS Theory
Neutron Productions in the Fragmentation of Relativistic Heavy Nuclei and Formation of a Beam of High-Energy Neutrons V. I. Yurevich* Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow oblast, 141980 Russia Received April 27, 2015; in final form, September 3, 2015
Abstract—The production of quasimonoenergetic high-energy neutrons at zero angle (0◦ ) in the spallation of relativistic heavy nuclei is discussed by considering the example of the interaction of lead nuclei with light target nuclei. It is shown that this process can be used to generate a beam of high-energy neutrons at existing heavy ion accelerators. At the same time, it may lead to the appearance of a parasitic neutron beam because of the interaction of the heavy-ion beam used with beam line and experimental setup materials. DOI: 10.1134/S1063778816020216
1. INTRODUCTION Energy and angular distributions of neutrons originating from the spallation of relativistic nuclei in nuclear interactions are of great interest for a broad class of fundamental investigations, for radiation physics, and for methodological and applied problems. At the present time, however, it is rather difficult to reproduce these distributions via simulations, since existing theoretical models and computer codes based on them call for a further development and verification. A phenomenological analysis of available experimental data on neutron production in nuclear reactions at high energies is an alternative approach that is employed in the present study. The results obtained in this way can be used both to estimate neutron distributions and to test theoretical codes. Yet another possible field of application of the results obtained from an analysis of multiple neutron production in such reactions is associated with the creation of a beam of relativistic neutrons on the basis of heavy ion accelerators. In contrast to what we have for protons, beams of monoenergetic neutrons in the region of energies above 20 MeV cannot be obtained at accelerators. With the aid of special reactions, however, it is possible to produce beams of quasimonoenergetic neutrons with a rather good energy resolution. For this purpose, one usually uses the interaction of accelerated protons or deuterons with targets where a major part of neutrons emitted at zero angle (0◦ ) have energies close to the kinetic energy of projectile nucleons. In the range of neutron energies from several tens to several hundred MeV units, the reaction 7 Li(p, n) is most frequently applied. On *
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the basis of this reaction, quasimonoenergetic neutron beams are produced in many laboratories worldwide, such as iThemba LABS (South African Republic); TSL (Sweden); TIARA, CYRIC, and RCNP (Japan); NPI (Czech Republic); and NFS/GANIL (France) [1]. As was shown in [2], the use of this reaction in inverse kinematics makes it possible to increase many times the neutron beam intensity. In the region of higher energies between a few hundred MeV and a few GeV, quasimonoe
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