Magnetic moments of pre-yrast high spin and first-excited levels in neutron-deficient162,163,164Hfisotopes

Abstract

Average magnetic moments of high spin, pre-yrast levels in neutron-deficient ${}^{162,163,164}\mathrm{Hf}$ isotopes were measured by utilizing the transient field technique using a $3.4{\mathrm{m}\mathrm{g}/\mathrm{c}\mathrm{m}}^{2}$ Gd ferromagnetic layer. The reactions ${}^{128,126}\mathrm{Te}{(}^{40}\mathrm{Ca}{,xn)}^{164,163,162}\mathrm{Hf}$ at a Ca beam energy of 175 MeV were used to populate high spin regions. Most of the reaction-product Hf nuclei have sufficient energy to traverse the Gd layer. A considerable fraction of recoils of each isotope stops in the Gd and experiences the static hyperfine field in addition to the transient magnetic field, experienced by the whole ensemble. Comparison of the measured precessions of transitions from the first excited, longer-lived levels with precessions from much shorter-lived, high-spin transitions yields $g$-factor ratios of the first excited states in the three isotopes. The previously unknown lifetimes of the relevant transitions were measured in a recoil-distance experiment. The possibility of measuring $g$-factor ratios in neutron-deficient nuclei by utilizing a combination of transient and static magnetic fields is discussed.