Decays of Photoreaction Products of Selenium

Abstract

The decay properties of Se 73m , Se 81 and As 79 have been studied by scintillation methods. Gamma-ray spectra showed lines of energy 170, 275, 335, 410, 480, 550, 650 and 840 KeV belonging to the decay of Se 81 . The decay scheme of Se 81 was proposed with the aid of single and coincidence measurements of radiations. The mass difference between the ground states of Se 81 and Br 81 is represented by the 1.56–MeV beta ray. In As 79 , new gamma rays of 360, 440, 725 and 890 KeV were found. Beta-gamma and gamma-gamma coincidence measurements confirmed that a 44–min activity in selenium is attributed to Se 73m . It is found that the beta-decay energy is 1.86–MeV and that there is no appreciable gamma ray.