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arXiv · 1610.04000

Inversion doublets of reflection-asymmetric clustering in 28Si and their isoscalar monopole and dipole transitions

Y. Chiba·Y. Taniguchi·M. Kimura
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Abstract

[Background] Various cluster states of astrophysical interest are expected to exist in the excited states of $^{28}{\rm Si}$. However, they have not been identified firmly, because of the experimental and theoretical difficulties. [Purpose] To establish the $^{24}$Mg+$α$, $^{16}$O+$^{12}$C and $^{20}$Ne+2$α$ cluster bands, we theoretically search for the negative-parity cluster bands that are paired with the positive-parity bands to constitute the inversion doublets. We also offer the isoscalar monopole and dipole transitions as a promising probe for the clustering. We numerically show that these transition strengths from the ground state to the cluster states are very enhanced. [Method] The antisymmetrized molecular dynamics with Gogny D1S effective interaction is employed to calculate the excited states of $^{28}{\rm Si}$. The isoscalar monopole and dipole transition strengths are directly evaluated from wave functions of the ground and excited states. [Results] Negative-parity bands having $^{24}$Mg+$α$ and $^{16}$O+$^{12}$C cluster configurations are obtained in addition to the newly calculated $^{20}$Ne+2$α$ cluster bands. All of them are paired with the corresponding positive-parity bands to constitute the inversion doublets with various cluster configurations. The calculation show that the band-head of the $^{24}$Mg+$α$ and $^{20}$Ne+2$α$ cluster bands are strongly excited by the isoscalar monopole and dipole transitions. [Conclusions] The present calculation suggests the existence of the inversion doublets with the $^{24}$Mg+$α$, $^{16}$O+$^{12}$C and $^{20}$Ne+2$α$ configurations.Because of the enhanced transition strengths, we offer the isoscalar monopole and dipole transitions as good probe for the $^{24}$Mg+$α$ and $^{20}$Ne+2$α$ cluster bands.

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Y. Chiba, Y. Taniguchi, M. Kimura. 2016-10-14. Inversion doublets of reflection-asymmetric clustering in 28Si and their isoscalar monopole and dipole transitions. https://doi.org/10.1103/physrevc.95.044328

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