Double-differential cross sections for the neutron production from heavy-ion reactions at energies E/A=290-600 MeV - art. no. 054609

We have measured the double-differential cross sections for neutron product ion from C, Ne, and Ar projectiles at E/A = 290-600 MeV on C, Cu, and Pb ta rgets. Neutron energies were measured at laboratory angles between 5 degree s and 80 degrees. The measured neutron spectra have three components. At fo rward angles, a prominent peak originating from the projectile-fragmentatio n process was observed. The velocity of neutrons corresponding to the peak was about the same as that of the projectile. In addition to the peak, two components of Maxwellian-shape distributions corresponding to the preequili brium and equilibrium processes were observed. By fitting with a moving-sou rce model having three components, the neutron spectra were fairly well des cribed. The parameters obtained for each component are consistent with a pi cture of the projectile fragmentation, preequilibrium, and equilibrium proc esses. By integrating the fitted functions with respect to the neutron ener gies and solid angles, the angular distributions and total cross sections f or the neutron production were determined. The neutron spectra, angular dis tributions, and total cross sections were compared with those calculated by the quantum molecular dynamics and heavy-ion codes. We found that neither of the codes could reproduce the measured cross sections for all combinatio ns of the projectiles and targets.