Beta- and Gamma-Ray Spectroscopy of Mn⁵² and Mn^52m

Abstract

Excited levels of Cr⁵² were studied by investigating the decays of Mn⁵²(5.7 days) and Mn^52m(21 min), produced by Cr⁵²(d, 2n)Mn^52,52m. By means of a two-directional focusing beta-ray spectrometer, NaI(TI) scintillation spectrometers and a 20-channel pulse height analyzer, following results were obtained: (1) Energies of the main three gamma-rays from Mn⁵² are 746.8±0.2, 938.1±0.4 and 1434.7±0.8 keV. (2) The maximum energies of the positrons from Mn⁵² and Mn^52m are 0.572±0.006 and 2.61±0.03 MeV, respectively. (3) The spins and parities of the levels of 3120, 2373 and 1435 keV were determined to be 6+, 4+ and 2+, from measurements of conversion electrons and angular correlations. (4) Several weak gamma-rays were found, which could be inferred to belong to these decays. (5) The half-life of Mn^52m is 21±1 min. Its branching ratio IT⁄(β⁺+EC) was determined as 2±1 percent. (6) The energy of isomeric transition is 0.383±0.003 MeV, which was decided as E4 from K⁄L+M and the transition probability.