Induced radioactivities of spallation products by various projectile ions

Recently, high-energy heavy ions have been used in various fields of nuclear physics, radiotherapy, material physics, and so on. Safety design consideration for heavy ion accelerator facilities requires nuclear reaction cross section data for high-energy ions to estimate the radioactivities induced in the accelerator components and in the shielding materials. We irradiated 230 and 100 MeV/nucleon Ar, Ne, C, He, p ions onto a Cu target to investigate the projectile dependency of induced radioactivities of spallation products. Irradiation experiments were performed at HIMAC (Heavy Ion Medical Accelerator in Chiba), National Institute of Radiological Sciences, Japan. The Cu target was composed of a stack of Cu plates, and C, Al, Cr, Fe, Ni, Cu, Pb samples were inserted between the Cu plates. The samples put on the front surface of Cu target are for measurement of reaction cross sections and the mass-yield distribution of produced nuclides. The samples inserted between the Cu plates are for measurement of the spatial distribution of the residual activities of produced nuclides in the Cu target. The thickness of Cu target is larger than the range of the projectile beam. After irradiation, we measured the gamma-ray spectra from samples with a HPGe detector. We obtained the spatial distribution of the residual activities of nuclides produced in these samples and the mass-yield distribution of nuclides produced on the surface of Cu target. For example, we could find the maximum number of 44 radioactive nuclides from 65 Zn down to 7Be in Cu sample. The results show that the dependence of the mass-yield distribution and the spatial distribution of the residual activities on the projectile mass varies with the mass number difference between the sample nuclide and the produced nuclide. These experimental results were compared with the Monte Carlo calculation