A detailed spectroscopic analysis using fusion evaporation reactions to study the high-spin structures in ^179,180W and an analysis of nuclear structure in rapidly rotating Er, Yb, Hf and W nuclei

High-spin states in ¹⁷⁹;¹⁸⁰W (Z = 74) were produced via fusion evaporation reactions. To produce the nuclei of interest, a ¹⁴C beam was impinged on a 1mg/cm^{2 170}Er target, at beam energies of 75MeV and 68MeV respectively. The emitted γ-rays were detected using three escaped-suppressed clover detectors and seven single element escape-suppressed high-purity germanium detectors. As a result of this analysis, new decay transitions and new energy levels have been observed in both nuclei building on previously known structures [1, 2]. The analysis of this data using γ-γ and γ-γ-γ coincidences was done using the Radware analysis package [3]. Additionally, new systematic data in the A ≈ 180 region is also discussed, with an emphasis on the role that pair-blocking effects play during the rotation of the nucleus. This systematic investigation builds upon the classic findings of Garrett et al. [4] who investigated the critical band crossing frequencies of the first pair of i_13/2 neutrons (AB) in rare-earth nuclei. The present work carries out a similar investigation for the second pair of aligning i13=2 neutrons (BC) at higher rotational frequencies [5].

[1] P. M. Walker et al., Phys. Rev. Lett. 67, 4 (1991). [2] P. M. Walker et al., Phys. Lett. B 309, 17 (1993). [3] D. C. Radford, Nucl. Instrum. Methods Phys. Res. A361, 297 (1995). [4] J. D. Garrett et al., Phys. Rev. Lett. 47, 75 (1981). [5] S. L. Miller, K. A. Villafana et al., To be published.