High spin states in 175Ta: An acute example of delayed crossing frequency.

High spin states in $^{175}\mathrm{Ta}$ are populated by the $^{160}\mathrm{Gd}$ ${(}^{19}$F,4n) $^{175}\mathrm{Ta}$ reaction. This experiment, carried out at the HI-13 tandem accelerator at the China Institute of Atomic Energy which measured the \ensuremath{\gamma}-\ensuremath{\gamma} coincidences, gives rise to a new level scheme. Two important new features are embedded in this scheme. First, the seven decay sequences built on 1/2 [541], 7/2 [404], 5/2 [402], and 9/2 [514] proton Nilsson configurations are significantly extended to higher spins. For example, for the 1/2 [541] band, the levels have extended from 33/${2}^{\mathrm{\ensuremath{-}}}$ to 61/${2}^{\mathrm{\ensuremath{-}}}$ and, for the 7/2 [404] band, from 21/${2}^{\mathrm{\ensuremath{-}}}$ to 41/${2}^{\mathrm{\ensuremath{-}}}$. Second, compared to the neighboring even-even nuclides, the neutron AB crossing frequency built on the ${\mathit{h}}_{9/2}$ proton Nilsson state 1/2 [541] is significantly larger, which according to the conventional cranking shell model (CSM) is an anomaly. In this paper, this large crossing frequency is also discussed within the framework of the projected shell model. It is shown that this anomaly found in CSM can be satisfactorily explained, thus suggesting an alternative understanding. \textcopyright{} 1996 The American Physical Society.