Search for α-decay of 229mTh produced from 229Ac β-decay following 232Th(γ, p2n) reaction

Summary We produced 229Th in the nuclear reaction 232Th(γ, p2n) 229Ac, followed by disintegration to 229m,gTh. The 229mTh α-decay was searched for. Alpha-particle events of energy between 4.93 MeV and 5.05 MeV were observed in the separated thorium sample of β-decay products from an actinium source highly purified from the 232Th + γ reaction products. The energies of the α-particles coincide with those expected for 229mTh.