Half-life of44Ti

We present the results of two separate measurements of the half-life of ${}^{44}\mathrm{Ti}$ relative to those of ${}^{22}\mathrm{Na}$ and ${}^{207}\mathrm{Bi},$ respectively. By comparing the numbers of 1157-keV γ rays from ${}^{44}\mathrm{Ti}$ to those of 1274-keV γ rays from ${}^{22}\mathrm{Na}$ observed from a mixed source over a period of approximately 2 yr, we determined the half-life of ${}^{44}\mathrm{Ti}$ to be $61.5\pm 1.0\mathrm{yr}.$ From an approximately 1-yr-long study of another mixed source, where we compared the numbers of 1157-keV γ rays from ${}^{44}\mathrm{Ti}$ to those of 1064-keV γ rays from ${}^{207}\mathrm{Bi},$ we determined the ${}^{44}\mathrm{Ti}$ half-life to be $62\pm 5\mathrm{yr}.$ From these two results, we have obtained a best value of $62\pm 2\mathrm{yr}$ for the half-life of ${}^{44}\mathrm{Ti}.$ The astrophysical implications of this result are discussed.