Shell-gap reduced level densities in ${}^{89,90}$Y

Abstract

Particle-$\gamma$ coincidences from the ${}^{89}$Y($p,p^{\prime }\gamma$)${}^{89}$Y and ${}^{89}$Y($d,p\gamma$)${}^{90}$Y reactions were utilized to obtain $\gamma$-ray spectra as function of excitation energy. The Oslo method was used to extract the level density from the particle-$\gamma$ coincidence matrices. The impact of the $N=50$ shell closure on the level densities is discussed within the framework of a combinatorial quasi-particle model.

Comments: 9 pages, 9 figures