Discovery of new proton emittersRe160andTa156

The heaviest known examples of proton radioactivity, ${}_{}{}^{160}{}_{}{}^{}\mathrm{Re}$ and ${}_{}{}^{156}{}_{}{}^{}\mathrm{Ta}$, have been discvovered. Evaporation residues from fusion reactions of 300 MeV ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ ions with ${}_{}{}^{106}{}_{}{}^{}\mathrm{Cd}$ targets have been mass separated in flight and implanted into a double-sided silicon strip detector. The measured proton energies, total half-lives, and proton branching ratios are 1261±6 keV, 790±160 μs, 91±10%, and 1022±13 keV, ${165}_{\mathrm{-}55}^{+165\mathrm{}}$ ms, ≊100% for ${}_{}{}^{160}{}_{}{}^{}\mathrm{Re}$ and ${}_{}{}^{156}{}_{}{}^{}\mathrm{Ta}$, respectively, indicating that the protons are emitted from a ${\mathit{d}}_{3/2}$ orbital in each case. An energy of 6537±16 keV has been measured for the ${}_{}{}^{160}{}_{}{}^{}\mathrm{Re}$ alpha decay branch.