Energy levels in 234U populated in the β-decay of 234Pa(UZ)

Abstract

Intense sources of the 6.7 h 234Pa isomer UZ have been investigated with Ge(Li) counters, a high-resolution 180° beta-ray spectrograph and with coincidence techniques. The Ge(Li) γ-spectrum of the 33 μs isomer of 234U was recorded by means of delayed coincidences. A total of 130 transitions in 234U was observed. The decay scheme includes the following levels, denoted by energy in keV and quantum number KI π for the rotational band heads only: 787(01 −), 810(00 +), 927(22 +), 990(22 −), 1127(22 +), 1421(66 −), 1496(33 +), 1552(55 +), (1693)((55 −)), 1723(33 −) and 1723(44 +). The majority of the levels has been identified in stripping and pick-up experiments (see the preceding paper). The intrinsic states correspond to theoretically predicted two-quasiparticle states and collective quadrupole and octupole excitations. Appreciable mixing of some of the two-quasiparticle configurations occurs and influences the decay pattern in a major way. Unexpectedly, there exists a K π = 2 + configuration with the energy 1127 keV in addition to the 2 + collective state at 927 keV. This level decays by strong transitions to the 2 + state at 927 keV and the 0 + state at 810 keV and only by weak transitions to the 0 + ground state.