Spectroscopic and reaction mechanism information derived fromGd160(d,t)Gd159andGy162(d,t)Gy161reaction measurements

Angular distributions have been measured for transitions populating residual states of ${}_{}{}^{159}{}_{}{}^{}\mathrm{Gd}$ and ${}_{}{}^{161}{}_{}{}^{}\mathrm{Dy}$ through the ($d,t$) reaction at $E_d=17\mathrm{}$ MeV. Many of these angular distributions have shapes which are well reproduced by distorted-wave Born-approximation calculations which assume orbital angular momentum transfers $l$ which are compatible with the previously assigned spin-parities of the states. But a significant number of angular distributions are anomalous; i.e., either they cannot be fitted by any reasonable distorted-wave Born-approximation calculation or they can only be fitted with a calculation which assumes an $l$ value incompatible with the previous Nilsson model assignment of the state. While the summed spectroscopic factors are in good agreement with Nilsson model expectations, the spectroscopic factors for many levels deviate significantly from Nilsson model predictions—even though Coriolis coupling has been included in the model calculation. The observation of several strongly anomalous angular distributions along with some anomalous oscillatory large-angle structure in many additional angular distributions and large discrepancies between observed and model-predicted spectroscopic factors almost certainly indicates that the assumption of a simple one-step direct reaction mechanism breaks down for these reactions.