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arXiv · 1408.2221

Quenching of N = 28 shell gap and a low-lying quadrupole mode in the vicinity of neutron-rich N = 28 isotones

Shuichiro Ebata·Masaaki Kimura
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Abstract

We investigate the low-lying 2$^+$ states of $N=28$ isotones ($^{48}$Ca, $^{46}$Ar, $^{44}$S and $^{42}$Si) with using the canonical-basis time-dependent Hartree-Fock-Bogoliubov theory in which the pairing is taken into account self-consistently. The quadrupole mode with very small excitation energies emerges in $^{46}$Ar, $^{44}$S and $^{42}$Si due to the strong quadrupole correlations triggered by the quenching of the $N=28$ shell gap. The importance of the quadrupole correlations between the protons and neutrons, and the role of the pairing correlation to reinforce the lowest 2$^+$ mode are discussed. It is also shown that the $B$(E2$\uparrow$) values of $^{48}$Ca and $^{46}$Ar are plausibly explained by our calculations.

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Shuichiro Ebata, Masaaki Kimura. 2015-01-21. Quenching of N = 28 shell gap and a low-lying quadrupole mode in the vicinity of neutron-rich N = 28 isotones. https://arxiv.org/abs/1408.2221

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