An isomer of ${}^{151}\mathrm{Lu}$ was identified by its direct proton radioactivity. It was produced by bombardment of ${}^{96}\mathrm{Ru}$ with 266-MeV ${}^{58}\mathrm{Ni}$ from the Holifield Radioactive-Ion Beam Facility, mass separated with a recoil separator and implanted in a double-sided silicon strip detector, which provided signals to correlate each proton decay with a particular implant. The proton energy and half-life of ${}^{151}{\mathrm{Lu}}^m$ were measured to be 1310(10) keV and $16\left(1\right)\mathrm{}\hspace{0.5em}\mu \mathrm{s},$ respectively. The half-life of the previously known $h_{11/2}$ ground state was observed to be $80\left(2\right)\mathrm{}\hspace{0.5em}\mathrm{ms}$ in agreement with the previously adopted value of 88(10) ms. Comparison of the half-life of ${}^{151}{\mathrm{Lu}}^m$ with WKB barrier-penetration calculations leads to the conclusion that the isomer is a $d_{3/2}$ proton state. A two-potential approach predicts a half-life of ${5.5}_{-1.1}^{+1.4\mathrm{}}\hspace{0.5em}\mu \mathrm{s}$ which yields an experimental spectroscopic factor of ${0.34}_{-0.08}^{+0.12\mathrm{}}.$

• Received 1 February 1999

DOI:https://doi.org/10.1103/PhysRevC.59.R2984