Collectivity in ${}^{41}\mathrm{S}$

Yrast states in the neutron-rich ${}^{41}\mathrm{S}$ nucleus have been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of ${}^{36}\mathrm{S}$ ions with a thin ${}^{208}\mathrm{Pb}$ target. The magnetic spectrometer, PRISMA, and the $\gamma$-ray array, CLARA, were used in the measurements. $\gamma$-ray transitions of energy 449 and 638 keV were observed. Results from published intermediate-energy Coulomb excitation measurements in combination with those from the present work have led to the construction of a new ${}^{41}\mathrm{S}$ level scheme. Proposed $J^{\pi }$ values are based on experimental observation and on model-dependent arguments. The level scheme and published electromagnetic transition probabilities are discussed within the context of state-of-art shell-model calculations using the SDPF-U effective interaction. In contrast with the excellent agreement observed in earlier published work, here there are significant discrepancies between experiment and the results of shell-model calculations.

Figure 1

$\gamma$-ray energy spectrum observed in coincidence with ${}^{41}\mathrm{S}$ ions.

Figure 2

A comparison of the published level scheme, the proposed ${}^{41}\mathrm{S}$ level scheme based on the intermediate-energy Coulomb excitation measurement [34] and the present experiment, and the result of the 0$\hslash \omega$ sd-pf shell-model calculation with the latest SDPF-U effective interaction [42]. See text for details.