Decay ofIn114mandIn114

Abstract

Scintillation counter experiments have been performed on the 72-second activity of ${\mathrm{In}}^{114}$ produced by ($p, n$) and ($d, 2n$) cyclotron bombardment of enriched ${\mathrm{Cd}}^{114}$ and on the 49-day activity of ${\mathrm{In}}^{114m}$ produced by neutron activation. The well-known 556-722-kev cascade radiation of ${\mathrm{Cd}}^{114}$ is shown to be excited by a $K$-capture transition from the 49-day isomeric level. The weak 1300-kev gamma ray previously assigned to ${\mathrm{Cd}}^{114}$ is shown to come from the first excited state of ${\mathrm{Sn}}^{114}$ and is in coincidence with a low-energy beta spectrum having an end point of 675±40 kev. No gamma rays in ${\mathrm{Cd}}^{114}$ other than the 556- and 722-kev lines have been observed from the decay of ${\mathrm{In}}^{114m}$ or ${\mathrm{In}}^{114}$. A 1.9% $K$-capture branch from ${\mathrm{In}}^{114}$ to the ground state of ${\mathrm{Cd}}^{114}$ has been found. A positron branch of ∼0.004% between these two states is shown to have an end point of 400±25 kev.