The excitation function for the positron decay following the ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}\mathrm{}(p,n)\mathrm{}{}_{}{}^{36}{}_{}{}^{}\mathrm{K}$ reaction has been measured from 15-30 MeV using chopped proton beams from the Triangle Universities Nuclear Laboratory Cyclo-Graaff accelerator. These data were also used to measure the ${}_{}{}^{36}{}_{}{}^{}\mathrm{K}$ half-life, giving a value of 341 ± 6 msec. Examination of the data at proton energies above the predicted ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}\mathrm{}(p,2n)\mathrm{}{}_{}{}^{35}{}_{}{}^{}\mathrm{K}$ reaction threshold revealed no positron activity which could be attributed to the decay of the as yet unobserved nuclide ${}_{}{}^{35}{}_{}{}^{}\mathrm{K}$. An 80-${\mathrm{cm}}^3$ Ge(Li) detector was used to study γ transitions in ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ arising from the decay of ${}_{}{}^{36}{}_{}{}^{}\mathrm{K}$. The relative intensities of nine $\gamma$ rays with energies of 1969.8 ± 0.5, 2171.5 ± 0.9, 2208.3 ± 0.4, 2433.7 ± 0.4, 2472.0 ± 0.8, 4180.4 ± 1.0, 4441.7 ± 0.6, 4643.7 ± 1.4, and 6612.7 ± 0.8 keV were used to deduce positron branching ratios of 46, 11, and 43% to ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ levels located at 1969.9 ± 0.5, 4442.0 ± 0.5, and 6613.3 ± 0.6 keV, respectively.

• Received 29 November 1971

DOI:https://doi.org/10.1103/PhysRevC.6.869