Speaker
Description
We study the shape coexistence in the nucleus $^{28}$Si with the nuclear shell model using numerical diagonalizations complemented with variational calculations based on the projected generator-coordinate method. The calculated electric quadrupole transitions and moments and an analysis of the collective wavefunctions indicate that the standard USDB interaction in the $sd$ shell describes well the ground-state oblate rotational band, but misses the experimental prolate rotational band.
Guided by the quasi-SU(3) model, we show that the prolate band can be reproduced either in the $sd$ shell, but by reducing the energy of the $0d_{3/2}$ orbital, or in the extended $sdpf$ configuration space, by using the SDPF-NR interaction which also describes well other Si isotopes. Finally, we address the possibility of superdeformation in $^{28}$Si within the $sdpf$ space. Our results disfavour the appearance of superdeformed states with excitation energy below 20 MeV.
| session | I. Nuclear Structure and Reactions |
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