High-spin yrast isomers in the odd-odd, N = 85, 152Ho nucleus

Abstract The level structure of the 152 Ho nucleus below the 47 ns isomer has been established studying, by the catcher recoil method, the delayed γ-rays following the 120 Sn( 37 Cl, 5n) reaction. The conversion-electron measurements, carried out from the 141 Pr( 16 O, 5n) reaction (also by a recoil method) lead to reliable spin and parity assignments for the yrast levels. Three yrast isomers have been located at 3.02 MeV ( I π = 19 − , T 1 2 = 8.4 μs) , 4.88 MeV (24 + , 5 ns) and 6.00 MeV (28 − , 47 ns). The B (E3) value 0.92 ± 0.03 W.u., obtained for the 734 keV, E3 transition deexciting the 19 − isomer, is typical of a single-particle transition. Its interpretation involves the j − 1 state ( 9 2 − ) of the (π h 3 11 2 ) multiplet coupled to the aligned state of the three valence neutrons. The 47 ns isomer appears as the expected fully aligned state of the six valence particles. Configurations are proposed for most of the observed structures.