Decay of 24 min 146Pr

The radiations associated with the β-decay of 24 min 146Pr have been studied with Ge(Li), Si(Li), NaI(Tl) and trans-stilbene detectors. Gamma-gamma and gamma-beta coincidence experiments were performed, and gamma-gamma directional correlations were measured for the 1.525–0.454 MeV cascade. The observation of a 3.6 MeV β-group in coincidence with the 0.454 MeV photopeak establishes the total β-disintegration energy of 146Pr as 4.1±0.1 MeV. The β-ray spectrum is complex with an end-point energy of 4.1±0.2 MeV. The intensity of the 0.454 MeV γ-transition per β-disintegration was found to be 0.49, and the intensities of some 40 other γ-rays were determined. Most of these γ-transitions have been placed in the 146Nd level scheme which includes excited states with energies has high as 3.819 MeV. The present data appear to be consistent with an assignment of either 1− or 2− for the ground state of 146Pr.