Study of $s$- and $d$-wave intruder strengths in ${}^{13}{\mathrm{B}}_{g.s.}$ via a $p{(}^{13}\mathrm{B},d{)}^{12}\mathrm{B}$ reaction

Abstract

Experimental results of the $p{(}^{13}\mathrm{B},d{)}^{12}\mathrm{B}$ transfer reaction to the low-lying states in ${}^{12}$B are reported. The optical potential parameters for the entrance channel are extracted from the elastic scattering $p$(${}^{13}\mathrm{B}$, $p$) measured in the same experiment, while those for the exit channel are global ones. Spectroscopic factors associated with the $p$-, $s$-, and $d$-wave neutron transfer to the known ${}^{12}$B states, are extracted by comparing the deuteron angular distributions with the calculation results. The separated $s$- and $d$-wave intruder strengths in ${}^{13}{\mathrm{B}}_{g.s.}$ were determined to be $10(2)\%$ and $6(1)\%$, respectively, which follow roughly the systematics for the $N$ = 8 neutron-rich isotones. The measured total intruder strength is in good agreement with the shell model calculation, while the individual ones evolve quite differently. Particularly, the sudden change of the $d$-wave intensity between ${}^{13}$B and ${}^{12}$Be needs further theoretical interpretation.

8 pages,8 figures