Alignments, Shape Changes, And Band Terminations In Tm-157

A high-spin study has been performed on the transitional N=88 nucleus $^{157}\mathrm{Tm}$. Over 80 new transitions have been added to the level scheme and states up to spin 83/${2}^{\mathrm{\ensuremath{-}}}$ observed. At low to medium spins the observed structures and their alignment behavior may be understood in terms of multiquasiparticle excitations within the standard cranked shell model. At higher spins a change from collective to noncollective rotation via the mechanism of band termination is established. Comparisons with cranked Nilsson-Strutinsky calculations including pairing are made. The $^{157}\mathrm{Tm}$ results and their implications for neighboring even-even N=88 nuclei are discussed.