Ab initio description of collectivity for sd shell nuclei

Abstract

In the present work, we have reported shell model results for open shell nuclei Ne, Mg and Si isotopes with 10 ≤ N ≤ 20 in sd-shell model space. We have performed calculations in sd shell with two ab initio approaches: in-medium similarity renormalization group (IM-SRG) and coupledcluster (CC) theory. We have also performed calculations with phenomenological USDB interaction and chiral effective field theory based CEFT interaction. The results for rotational spectra and B(E2; 2 + 1 → 0 + 1 ) transitions are reported for even-mass isotopes. The IM-SRG and CC results are in reasonable agreement with the experimental data except at N =20. This demonstrates a validity of ab initio description of deformation for doubly open-shell nuclei for sd shell. To see the importance of pf orbitals, we have also compared our results with SDPF-MU interaction by taking account of 2p − 2h and 4p − 4h configurations in sd-pf -shell model space.

Ab initio description of Si, P, S, Cl and Ar isotopes in sd-shell

“…[50], experimental spectroscopic factor strength for ground state (g.s.) of 24 Si from 23 Al(p, γ) 24 Si reaction was obtained. Recently, an experiment has been performed with a transfer reaction 23 Al(d, n) 24 Si at National Superconducting Cyclotron Laboratory [51] to measure excited states and their spectroscopic factor strengths that might be of astrophysical interest.…”

“…of 24 Si from 23 Al(p, γ) 24 Si reaction was obtained. Recently, an experiment has been performed with a transfer reaction 23 Al(d, n) 24 Si at National Superconducting Cyclotron Laboratory [51] to measure excited states and their spectroscopic factor strengths that might be of astrophysical interest. In the present work, we have calculated theoretical spectroscopic factor strengths for g.s.…”

“…Electromagnetic properties, spectroscopic factor strengths and Gamow-Teller (GT) strengths of sd-shell nuclei have been calculated using former two of the aforementioned ab initio approaches in Refs. [22][23][24][25][26][27]. Another ab initio approach, known as the ab initio shell model with a core, has also been developed for heaviermass nuclei in Refs.…”

“…Prolate-oblate shape coexistence in some iso-topes of Si, S and Ar isotopic chains have also been observed. In [23], it has been reported that excitation of nucleons from sd-to pf -shell plays an important role for "island of inversion" nuclei at N = 20. Inclusion of pfshell was found to improve the B(E2) values for 30 Ne and 32 Mg. Ab initio results with IMSRG and CC methods were seen to be in reasonable agreement with the experimental data for the sd-shell nuclei Ne, Mg and Si except for N = 20.…”

“…In the present work, we have calculated theoretical spectroscopic factor strengths for g.s. as well as excited states of 24 Si for one proton capture reaction 23 Al(d, n) 24 Si using microscopic N3LO, JISP16 and DJ16A interactions, and have also carried out a comparison with the USDB results.…”