Measurements of Thick Target Neutron Yields from 100 to 800 MeV/Nucleon Heavy Ions

Abstract

We have measured angular and energy distributions of neutrons produced by 100 and 180 MeV/u He, 100, 180, 400 MeV/u C, 100, 180, 400MeV/u Ne, 400MeV/u Ar, 400MeV/u Fe, 400MeV/u Xe and 800MeV/u Si ions stopping in thick carbon, aluminum, copper and lead targets using the HIMAC (Heavy-Ion Medical Accelerator in Chiba) of NIRS (National Institute of Radiological Sciences), Japan. The neutron spectra in the forward direction have broad peaks of about 60 to 70 % of the incident particle energy per nucleon due to the break-up process and spread up to almost the twice of the projectile energy per nucleon. The neutron spectra are similar for the same incident energy for different projectile particles. The experimental results are compared with the calculations using the HIC code, and the calculated results agree with the measured results within a factor of 2. This systematic study on neutron production from thick targets by high-energy heavy ions is the first experimental work performed by NIRS and will be useful for designing the shield of the high-energy heavy-ion accelerator facility.