High-spin states and lifetimes in ${}^{33}\mathrm{S}$ and shell-model interpretation in the $sd-fp$ space

The structure of the ${}^{33}\mathrm{S}$ nucleus was investigated in the ${}^{24}\mathrm{Mg}({}^{14}\mathrm{N},\alpha p)$ fusion-evaporation reaction using a 40-MeV ${}^{14}\mathrm{N}$ beam. The level scheme was extended up to an excitation energy of 11.7 MeV and spin $19/2^{+}$. Lifetimes of the intermediate- and high-spin states have been investigated by the Doppler shift attenuation method. Data were compared with different shell-model calculations where effective interactions involving two main shells, the sd and the fp, are used.

Figure 1

Level scheme of ${}^{33}\mathrm{S}$ established in the present work. The transitions between states of the same parity are shown as vertical arrows, while the transitions connecting states of different parities are shown as tilted arrows. The widths of the arrows correspond to the relative intensities of the observed $\gamma$-ray transitions.

Figure 2

Background-subtracted coincidence spectra registered by the detectors at ${90}^{\circ }$, obtained from the asymmetric $\gamma -\gamma$ matrix with gates on $\gamma$-ray transitions of (a) 968, (b) 2935, (c) 2969, and (d) 1064 keV on the axis with all the detectors. The new transitions are marked with a star ($★$).

Figure 3

Experimental and calculated lineshapes for transitions in ${}^{33}\mathrm{S}$. The coincidence spectra were created with narrow gates on lower-lying transitions emitted from stopped nuclei. The fitted DSAM spectra are shown in red dashed lines.

Figure 4

Comparison between experimental positive parity states in ${}^{33}\mathrm{S}$ and shell-model calculated states using different model spaces and interactions. In the figure is not included the $19/2^{+}$ state calculated using the USD and PSDPF interactions, predicted at 17 224- and 16 784-keV excitation energy, respectively.

Figure 5

Comparison between negative parity experimental and shell-model predicted levels in ${}^{33}\mathrm{S}$.