Monte Carlo Calculations of Neutron Pentration through Graphite and Polyethylene at Energies of 30 and 45 MeV

A new Monte Carlo code was developed to calculate neutron penetration through graphite and hydrocarbon. The accuracy of the code was checked with the experimental values. Attenuation profiles of 30 and 45 MeV monoenergetic neutrons through graphite and polyethylene slabs were obtained by the Monte Carlo calculation. Macroscopic removal cross sections were calculated from the profiles

Measurements of Total Neutron Cross Sections of C, Fe, Pb, O, Mo, Si, Zn, Ni, Sn, Ti and W at Energies 20-60 MeV

Measurements of total neutron cross sections of C, Fe, Pb, O, Mo, Si, Zn, Ni, Sn, Ti and W were made, using white neutrons from a thick Cu target bombarded by 65- and 75-MeV protons. The cross sections were obtained in the energy range 20-60 MeV. The obtained data agree well with others in the case where other data were already existing. The present work added several new data points for Ni, Mo, Sn, Zn, Ti and W, for which the number of existing data was not enough

Absolute measurements of the response function of an NE213 organic liquid scintillator for the neutron energy range up to 206 MeV. Nuclear Instruments and Methods in Physics Research

Abstract The absolute values of the neutron response functions of a 12:7 cm diameter by 12:7 cm long NE213 organic liquid scintillator were measured using a quasi-monoenergetic neutron field in the energy range of 66-206 MeV via the 7 Liðp; nÞ 7 Be reaction in the ring cyclotron facility at RIKEN. The measured response functions were compared with calculations using a Monte Carlo code developed by Cecil et al. The measurements clarified that protons escaping through the scintillator wall induced by high-energy neutrons increase from 6% for 66 MeV neutrons to 35% for 206 MeV neutrons, and that this wall effect causes a difficult problem for nÀg discrimination. Measured response functions without the wall-effect events were also obtained by eliminating the escaping-proton events in the analysis, and compared with calculations using a modified Monte Carlo code. Comparisons between the measurements and calculations both with and without any wall-effect events gave a good agreement, but some discrepancy in the light output distribution could be found, mainly because the deuteron generation process was not taken into account in the calculation. The calculated efficiencies for 10 MeVee threshold, however, also gave good agreement within about 10% with the measurements.

INDUCED RADIOACTIVITY IN CU TARGETS PRODUCED BY HIGH-ENERGY HEAVY IONS AND THE CORRESPONDING ESTIMATED PHOTON DOSE RATES

Irradiation experiments were performed at the Heavy Ion Medical Accelerator in Chiba (HIMAC) facility, National Institute of Radiological Sciences. The radioactive spallation products in a thick Cu target were obtained for Ar(230, 400 MeV per nucleon), Si(800 MeV per nucleon), Ne(100, 230, 400 MeV per nucleon), C(100, 230, 400 MeV per nucleon), He(100, 230 MeV per nucleon), p(100, 230 MeV) ions. The gamma-ray spectra from irradiated Cu samples inserted into the composite Cu target were measured with a high-purity germanium (HPGe) detector. From the gamma-ray spectra, we obtained the spatial distribution of radioactive yields of spallation products of 40 nuclides in the Cu sample in the Cu target. From the spatial distribution of radioactive yields, we estimated the residual activity and photon dose induced in the Cu target. The residual activity and photon dose become larger with the increase in projectile energy per nucleon and the range of the projectile beam for the same projectile energy per nucleon