Measurement of Induced Radioactivity in Copper Exposed to High Energy Heavy Ion Beam

Abstract

The residual radioactivities produced by high energy heavy ions have been measured using the 290MeV/u and 400MeV/u 12C ions and 400MeV/u 20Ne ion beams ofthe Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radio log ical Sciences. During the irradiation experiment, the beam intensities were measured with a transmission-type ionization chamber, We used the natural copper target of IOOmm x IOOmm size and 5mm thickness which had total thickness of3.5cm, 5.5cm and IOcm to stop the projectile heavy ion beams, 290 and 400MeV/u-C ion beams and 400MeV/u-Ne ion beam, respectively. Additional activation foils of copper, aluminum, iron and stainless steel were inserted at every 5mm to 20mm interval in the copper target to measure the spatial distribution of residual nuclei in the copper target. The spatial distribution of residual nuclei was obtained by measuring the gamma-ray activities of 0.5mm thick copper, aluminum, iron and stainless steel foils inserted in the target with a high purity Ge detector after about Ihr to 6 hrs irradiation. From the irradiation experiments, we identified the residual nuclei induced in these activation foils and obtained the spatial distributions of 61 Cu, 60CU, 62mco, 61CO, 56Mn, 49Cr, 44SC and 38Cl in the copper target.