A new more precise measurement of the ground-state proton decay of ${}^{117}\mathrm{La}$ is presented $[E_p=806\mathrm{}(5)\mathrm{}\hspace{0.5em}\mathrm{keV},$ $t_{1/2,p}=26\mathrm{}\left(3\right)\mathrm{}$ ms]. ${}^{117}\mathrm{La}$ was produced via the $p4n$ fusion-evaporation channel by bombarding a ${}^{64}\mathrm{Zn}$ target with 310 and 295 MeV ${}^{58}\mathrm{Ni}$ beams. The proton decay rate is consistent with emission from a prolate deformed ${3/2}^{+}$ or ${3/2}^{-}$ Nilsson state. No evidence is found for a previously reported proton decay from a high spin isomer in ${}^{117}\mathrm{La}.$ An upper limit for the production cross section for proton decay of ${}^{116}\mathrm{La}$ at a bombarding energy of 325 MeV was established.

• Received 28 March 2001

DOI:https://doi.org/10.1103/PhysRevC.64.031303