Analysis of the (p,t) reaction onDy158

Abstract

The level structure of $^{156}\mathrm{Dy}$ has been investigated with the ($p,t$) reaction at 29.9-MeV incident proton energy. Angular distributions were measured for transitions to 34 levels up to an excitation energy of 2.25 MeV in $^{156}\mathrm{Dy}$. The ground-state $Q$ value for this reaction was determined to be ${Q}_{0}=\ensuremath{-}7.535\ifmmode\pm\else\textpm\fi{}0.015$ MeV. Optical-model parameters were obtained self-consistently in the coupled-channels approach, and reaction calculations using these parameters demonstrated a very large destructive interference between direct and indirect transfer to the ${2}^{+}$ member of the ground-state band. The anomalously strong transition to the ${J}^{\ensuremath{\pi}}={0}^{+}$ state at 674 keV is interpreted in the model of Van Rij and Kahana, leading to suggestions as to the structure of this state. The strong $L=2$ transition to the ${J}^{\ensuremath{\pi}}={2}^{+}$ state at 890 keV is also discussed. Further evidence is given on the structure of the ${J}^{\ensuremath{\pi}}={2}^{+}$ state at 1520 keV, and the ${J}^{\ensuremath{\pi}}={4}^{+}$ state at 1627.3 keV which has been suggested to belong to the "super" band in $^{156}\mathrm{Dy}$.NUCLEAR REACTIONS $^{158}\mathrm{Dy}$($p,t$), ${E}_{L}=29.9$ MeV, measured $\ensuremath{\sigma}(\ensuremath{\theta})$, ${Q}_{0}$; CCBA and DWBA analysis; deduced ${E}_{x}$, $L$, ${J}^{\ensuremath{\pi}}$ of $^{156}\mathrm{Dy}$ levels.NUCLEAR STRUCTURE Model of Van Rij and Kahana applied to anomalous ${0}^{+}$ state; evidence for $\ensuremath{\gamma}$ vibration built on these states, and on nature of "super" band.