We measured neutron angular and energy distributions from 710-MeV alphas stopping in targets of water, carbon, steel, and lead for neutron energies from 3 MeV to above 300 MeV. We also measured neutron spectra from 640-MeV alphas stopping in lead. These spectra are similar to the 710-MeV spectra but are reduced in magnitude by about 20 percent. The angular distributions are forward peaked and have a broad bump at about 120 MeV in the 0- and 6-degree spectra. The 710-MeV integrated yields above 10 MeV are about 0.5 neutron per incident alpha, independent of the target. The measured spectra from the water target are consistent with the calculations of an intranuclear cascade model at the forward angles, but are larger than the calculations at the backward angles.

NUCLEAR REACTIONS ${\mathrm{H}}_2$O, C, steel, Pb($\alpha$,$\mathrm{xn}$), $E=710\mathrm{}$ MeV; Pb($\alpha$,$\mathrm{xn}$), $E=640\mathrm{}$ MeV. Measured unidirectional spectra and yields from thick targets. Deduced total integrated neutron yields above 10 MeV. Compared spectra with intranuclear-cascade model.

• Received 22 October 1979

DOI:https://doi.org/10.1103/PhysRevC.21.2471