Neutron production in the interaction of 2-GeV protons with nuclei
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EMENTARY PARTICLES AND FIELDS Experiment
Neutron Production in the Interaction of 2-GeV Protons with Nuclei V. I. Yurevich* , R. M. Yakovlev1), and V. G. Lyapin1) Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia Received April 1, 2010; in final form, July 16, 2010
Abstract—The double-differential cross sections for neutron production in the interactions of 2-GeV protons with Be, Al, Cu, Cd, and Pb nuclei were measured by the time-of-flight method in the region of angles larger than 30◦ . The respective experimental data are analyzed within the phenomenological model of four moving sources, including those associated with neutron emission in primary nucleon–nucleon collisions, the decay of a hot source (fireball), the multifragmentation process, and the deexcitation of nuclear fragments via neutron evaporation. Temperature-parameter values are universal for all sources and are virtually independent of the target nucleus and of the projectile energy in the region above 0.5 GeV. It is found that, for all of the above reactions, the relative contribution to the mean neutron multiplicity from the decay of a hot source and multifragmentation is about 41%. DOI: 10.1134/S1063778811020219
1. INTRODUCTION Interest in data on neutron emission in collisions of hadrons and extremely light nuclei with nuclei at relativistic energies has been motivated by the importance of this process in the evolution of the nuclear system formed in the respective reaction. In view of this, experimental double-differential cross sections for the production of neutrons and other, charged, particles are of great value for testing the predictive power of theoretical models and codes and for refining them. Moreover, there is an ever increasing need for neutron data in the region of high energies for various investigations at accelerators and for cosmicray studies because of a considerable role of neutrons in the formation of radiation fields. Double-differential cross sections for neutron production by protons in the region of energies above 500 MeV were measured by the time-of-flight method at the Paul Scherrer Institute (PSI) [1], Los Alamos National Laboratory (LANL) [2, 3], and KEK [4, 5]; in Saclay [6, 7]; and at the Institute of Theoretical and Experimental Physics (ITEP, Moscow) [8– 11] and the Joint Institute for Nuclear Research (JINR, Dubna) [12, 13]. In beams of light nuclei, similar data were recently obtained in the energy range 135–600 MeV per nucleon [14–16] and in the energy range from 1 to 2 GeV per nucleon [12]. In this article, we present results obtained by a collaboration of research groups from JINR and 1)
Khlopin Radium Institute, Vtoroi Murinskii pr. 28b, St. Petersburg, 194021 Russia * E-mail: [email protected]
the Khlopin Radium Institute by measuring doubledifferential cross sections for neutron production in reactions induced by 2-GeV protons in the angular region θ 30◦ . The measurements were performed for Be, Al, Cu, Cd, and Pb targets by the time-offlight method in a beam extracted from the JINR
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