Shell model calculations on natural parity states in 10≦ A≦14 nuclei

Abstract

Shell model calculations of natural parity states in the 10N AN 14 mass region have been performed by assuming an inert 4He core with the residual interaction in the lp shell only. The modified surface delta interaction (MSDI) has been used as an effective two-body interaction. The MSDI parameters as well as the single-particle binding energies have been deduced from a least-squares fit to experimentally known levels in, firstly, the seperate l~ 11B--C, 12C, laC--N and 14N nuclei, and secondly, the whole mass region 10-<A_< 14. Multipole moments for ground states and M1 and E2 radiative widths for excited states have been calculated with the resultant wave functions.

Shell model treatment of the structure of light neutron-rich nuclei

“…This situation differs from the standard cases, where one usually finds for the MSDI, the parameters A 1 A 0 . As an example, the values A 1 = 2.6 Mev and A 0 = 1.2 MeV were used in [17] to describe nuclei in the region A = 8-16. As a consequence, in our case the two-proton configuration (π 1p 3/2 ) 2 is polarized to coupled angular momentum J (2p) = 2 (J (π1p 2 3/2 ) = 2(22%) and J (π1p 1 3/2 , 1p 1 1/2 ) = 2(11.3%)) due to the strong n-p residual interaction.…”

The calculation of logft values and spectroscopic factors for nuclei in the mass range 10?15

“…The shell-model calculations leading to the wave functions used in the present study were fully dealt with in two previous papers [1,2]. In these calculations the modified surface delta interaction (MSDI) has been used as the residual two-particle interaction.…”

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Wave functions obtained in previous shell-model calculations [1,2] for states of nuclei with masses A=10-15 are used to calculate logft values and spectroscopic factors. These wave functions, which were based on a modified surface delta two-body interaction, comprise the following active shell-model spaces: the lp3/2 and lp~/2 orbitals for mass 10 14 nuclei and restricted combinations of the lpl/2, 2Sl/2, lds/2 and ld3/2 orbitals for mass 15 nuclei, leading to four different calculations in the latter case.

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