The energy levels of the nuclei /sup 159/Tm and /sup 157/Er have been studied up to high spins (/sup 61///sub 2/ and /sup 53///sub 2/, respectively) and rotational frequencies (480 and 417 keV, respectively) by in-beam spectroscopic methods. On the basis of blocking arguments, the results show that the second backbending in the yrast band of even-even nuclei near /b N/=90 is due to pi /b h//sub 11/2/ protons.
Holzmann, R., Kuzminski, J., Loiselet, M., Van Hove, M.-A., & Vervier, J. (1983). Proton nature of the second backbending near /b N/=90. Physical Review Letters, 50(23), 1834-1837. https://hdl.handle.net/2078.5/148972 (Original work published 1983)