Neutron yields from thick C, Al, Cu, and Pb targets bombarded by 400 MeV/nucleon Ar, Fe, Xe and 800 MeV/nucleon Si ions

Abstract

The angular and energy distributions of neutrons produced by 400 MeV/nucleon Ar, Fe, and Xe, and 800 MeV/nucleon Si ions stopping in thick C, Al, Cu, and Pb targets were measured using the Heavy-Ion Medical Accelerator in Chiba of the National Institute of Radiological Science (NIRS), Japan. The neutron spectra in the forward direction have broad peaks which are located at about 60 to 70 % of the incident particle energy per nucleon due to breakup and knock-on processes, and spread up to almost twice as much as the projectile energy per nucleon. The resultant spectra were integrated over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions, and we could estimate the total yields using a simple formula. The experimental results are compared with the calculations using the heavy-ion collision Monte Carlo code, and the calculated results rather agree with the measured results. The phenomenological hybrid analysis, based on the moving source model and the Gaussian fitting of the breakup and knock-on processes, could also well represent the measured thick target neutron spectra.