234U excited states fed in the beta decay of 234Pa.

Abstract

The decay of radiochemically separated $^{234}\mathrm{Pa}$ (UZ) sources has been reinvestigated by means of single and \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectrometry using planar and high efficiency coaxial HPGe detectors. Of the 330 \ensuremath{\gamma} rays observed in the 40--2100 keV energy range, of which 140 are new, more than 310 \ensuremath{\gamma} rays are accommodated in an improved $^{234}\mathrm{U}$ level scheme, accounting for 98% of the $^{234}\mathrm{Pa}$ \ensuremath{\beta} decay; of the 77 excited states observed here, 37 had not been previously found in this decay. Within the framework of the collective model of strongly deformed nuclei, couplings between the collective positive parity ${K}^{\ensuremath{\pi}}$${=0}_{1}^{+}$ (g.s. band), ${0}_{2}^{+}$, ${2}_{1}^{+}$, ${0}_{3}^{+}$, and ${2}_{2}^{+}$ bands are estimated from the perturbed transition probabilities and the distortions to the adiabatic energy systematics. The Coriolis interaction weakly coupling the ${K}^{\ensuremath{\pi}}$${=0}^{\mathrm{\ensuremath{-}}}$, ${1}^{\mathrm{\ensuremath{-}}}$, and ${2}^{\mathrm{\ensuremath{-}}}$ octupole bands was evaluated consistently by a fit to the experimental energy levels. Several new levels and a tentative ${K}^{\ensuremath{\pi}}$${=3}^{+}$ band (at 1770 keV) are discussed in terms of Nilsson orbitals assignments.