Cosmic-ray muon-induced iron 59 in cobalt

Abstract

Fe59 induced by cosmic-ray muons in cobalt was investigated. γ rays that can be assigned to Fe59 were observed in reagents of cobalt that had been exposed both with and without a soil cover to cosmic rays at sea level as well as at a mountain altitude. Both the theoretical calculation and the analysis of the experimental results suggest that the activities observed at sea level are mainly due to Fe59 formed by the nuclear capture of cosmic-ray negative muons with cobalt. The production rates of Fe59 by muons have been evaluated to be 0.35±0.14 (at sea level) and 0.33±0.16 (at sea level with a soil cover of 200 g/cm2) Fe59 atoms/min kg Co.