Study on neutron yield from thick targets bombarded by 22,7 MeV protons

The spectrum and yield of neutrons produced in thick targets bombarded by the 22.7 MeV energy protons were studied. Proton energy in a beam was determined by the path in foils. The targets were made of pure (99.9%) chemical substances of a natural isotope composition. Thickness of targets were 5-10% larger than the path of a bombarding particle in the given substance. Amplitude distributions of neutrons from thick aluminium targets were measured at the angles of THETA=0,45,90 deg and for Nb, Ta target at the angle of THETA=90 deg. It is stated that the spectrum from Al target measured at the angle of THETA=0 deg has a small ''hump'' at the neutron energy of Esub(n)=1.8 MeV. Enerqy distributions of N/En/ of neutrons from thick Nb and Ta targets at THETA=90 deg smoothly drop with the increase of neutron energy up to maximum values. For Al target the angles of THETA=0;45;90 deg the mean energy of escaping electrons < Esub(n) > is equal to 3.6 MeV; 3.0 Mev; 2.8 MeV, and for the Nb, Ta target at the angle of THETA=90 deg it is 2.8 MeV; 1.6 MeV, respectively. Absolute full yields of neutrons in a single solid angle in the direction of THETA=0 deg in relation to beams of bombarding protons for the Al, Nb, Ta targets. It has been determined that the mean value of neutron yield per one inelastic interaction in thick targets increases with the growth of Z; for Al, Nb, Ta, Pb, U targets it is 0.12; 1.06; 1.20; 1.19; 1.5, respectively. The results obtained may be used to calculate protective materials irradiated with charged particles with energies at which secondary irradiation may produce a large contribution into the doze behind the shield