Doubly-magic nature of 56Ni: measurement of the ground state nuclear magnetic dipole moment of 55Ni

Abstract

The nuclear magnetic moment of the ground state of ${}^{55}$Ni ($I^{\pi }=3/2^{-},T_{1/2}=204$ ms) has been deduced to be $|\mu$^{55}Ni)$|=(0.976\pm 0.026)$ ${\mu }_N$ using the $\beta$-NMR technique. Results of a shell model calculation in the full \textit{fp} shell model space with the GXPF1 interaction reproduce the experimental value. Together with the known magnetic moment of the mirror partner ${}^{55}$Co, the isoscalar spin expectation value was extracted as $<\sum {\sigma }_z>=0.91\pm 0.07$. The $<\sum {\sigma }_z>$ shows a similar trend as that established in the \textit{sd} shell. The present theoretical interpretations of both $\mu {(}^{55}$Ni) and $<\sum {\sigma }_z>$ for the $T=1/2$, A=55 mirror partners support the softness of the ${}^{56}$Ni core.

13 pages, 1 figure, accepted for publication in Phys. Rev. C

References in corpus (1)

• Fast switching NMR system for measurements of ground-state quadrupole moments of short-lived nuclei