High spin states inTl206,204,202observed in (d,α) reactions at 80 MeV

Abstract

The ($d,\ensuremath{\alpha}$) reaction on $^{208,206,204}\mathrm{Pb}$ has been studied at 80 MeV bombarding energy. The experimental angular distributions are structured and the transferred angular momentum $L$ could be determined without ambiguity from a comparison of distorted-wave Born-approximation calculations with the experimental angular distributions. The angular momentum matching conditions greatly favored large values of $L$ and allowed the identification of ${J}^{\ensuremath{\pi}}={12}^{\ensuremath{-}} \mathrm{and} {9}^{+}$ states in $^{206,204,202}\mathrm{Tl}$. Data for the $^{208}\mathrm{Pb}(d,\ensuremath{\alpha})^{206}\mathrm{Tl}$ reaction were compared with shell model calculations. The properties of nine levels could be correlated with very good agreement with those of states predicted in the shell model calculations. Both zero-range and exact finiterange distorted-wave Born-approximation calculations were carried out. Unlike the zero-range distorted-wave Born-approximation results, the exact finite-range angular distributions did not change greatly for different choices of the $\ensuremath{\alpha}$ particle optical potential. Although somewhat better agreement with the relative cross sections was obtained, the exact finite-range calculations underestimated the absolute cross sections by roughly a factor of 50.NUCLEAR REACTIONS $^{208,206,204}\mathrm{Pb}(d,\ensuremath{\alpha})$, ${E}_{d}=80$ MeV. Measured $\ensuremath{\sigma}(\ensuremath{\theta})$; enriched targets; microscopic DWBA analysis; shell model calculations; deduced $J$, $\ensuremath{\pi}$.