Decays of Photoreaction Products of Selenium

Abstract

The decay properties of Se^73m, Se⁸¹ and As⁷⁹ 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 Se⁸¹. The decay scheme of Se⁸¹ was proposed with the aid of single and coincidence measurements of radiations. The mass difference between the ground states of Se⁸¹ and Br⁸¹ is represented by the 1.56–MeV beta ray. In As⁷⁹, 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.