NEUTRON YIELD DATA DUE TO BOMBARDMENT OF THICK TARGETS OF Be, C, Ta AND Au BY 40 TO 80 MeV ALPHA PARTICLESHealth Physics Unit Variable Energy Cyclotron Centre I/AF Bidhan Nagar, Calcutta-700 084, India Sudip Ghosh Saha Institute of Nuclear Physics I/AF Bidhan Nagar, Calcutta-700 064, India A.S. Divatia Senior Scientist, INSA Nuclear Physics Division B.A.R.C. Bombay-400 085, India A knowledge of the energy distribution of the neutrons, from bombardment of thick targets by charged particles is necessary for accurate estimation of shield thicknesses. With increasing cost of shield materials and with the possibility of increasing the quality factor by a factor of about two resulting in the reduction of the values of the maximum permissible fluxes of neutrons, a knowledge of neutron energy distribution is very essential. Data on neutron production from thick targets is sparse. To generate such data, we have measured neutron energy distribution due to the bombardment of alpha particles in the energy range of 40-60 MeV on thick targets of Be, C, Ta and Au. NE-213 liquid scintillator system with the associated n-γ discriminator circuit was used for this purpose. The data have been analysed in the framework of the exciton model incorporating both multistep direct and multistep compound processes and the compound nuclear evaporation process. KEYWORDS: neutron spectrum, thick target, (α,xn) reactions, exiton model |