Proton Spectra with Low-Energy-Threshold from 40- and 70-MeV Proton-Induced Reactions
- Mr. Yuji YAMAGUCHI
- Mr. Yuji YAMAGUCHI (Kyushu University)
Energy and angular distributions of secondary particles from energetic proton-nucleus reactions are required to estimate the spatial distributions of energy deposition and radiation damage for the engineering design of an accelerator driven system and a particle radiation therapy. Because the estimation is performed using a Monte Carlo simulation code such as PHITS, the nuclear reaction models must have high predictive power for energy and angular distributions. A two-stage model comprising the intra-nuclear cascade (INC) model and the generalized evaporation model (GEM) generally well describes proton production for intermediate energy proton-nucleus reactions, except for low-energy proton production from a heavy target. The emission of low-energy proton from an excited nucleus is calculated by the GEM after INC stage with considering Coulomb barrier. To improve the GEM, new experimental data covering the low-energy range down to 2 MeV are required for various targets and angles from forward to backward because systematic data are not available in this energy range because of threshold energy of conventional detector with dE-E particle identification. To obtain the data, we develop a low-energy-threshold detector consisting of a Bragg curve counter (BCC) and two silicon-surface barrier detectors (SSDs), and a bismuth germanate (BGO) scintillator. The experiment was performed at cyclotron facility of National Institute of Radiological Sciences for 40- and 70-MeV incident protons on C, Al, Cu, Au targets. Secondary particle spectra were measured at 60, 120, and 150 degrees in the laboratory system using the low-energy-threshold detector. The resultant spectra are compared with results of nuclear data library of JENDL-4.0/HE and prediction from the two-stage models.