High-K Bands at High Spin in ^174Hf

A multi-faceted experiment utilizing the excellent beam pulsing conditions of the Argonne ATLAS facility with the power of Gammasphere was performed to identify high-K states and the rotational bands based upon them in ^174Hf. The ^130Te(^48Ca,4n) reaction was used to populate high-spin states in ^174Hf with a backed target and a beam pulsing condition of 10:1. This operating mode allowed for the identification of both prompt radiation and delayed γ transitions emitted by the high-K isomers. Rotational sequences above the 14^+ four-quasiparticle isomer (T_1/2 = 3.7 μs) in ^174Hf [1] were confirmed for the first time. In addition, a thin, self-supporting target was used with the ATLAS accelerator operating in a standard mode such that these sequences could be observed to very high spin after Doppler shift corrections were applied. A total of six separate bands were observed above the 14^+ state that reach spins of I≈ 40hbar. The band found at the highest excitation energy may be based on an eight- or possibly ten-quasiparticle state. Discussion of the configurations for these bands will be addressed along with evidence for the persistence of pairing in multi-quasiparticle structures at high frequency. [1] N. L. Gjorup et al., Nucl. Phys. A 582, 369 (1995).