  The ground state half-lives of 69Ge, 73Se, 83Sr, 63Zn, and the half-life of
the 1/2- isomer in 85Sr have been measured with high precision using the
photoactivation technique at an unconventional bremsstrahlung facility that
features a repurposed medical electron linear accelerator. The g-ray activity
was counted over about 6 half-lives with a high-purity Germanium detector,
enclosed into an ultra low-background lead shield. The measured half-lives are:
T1/2(69Ge) = 38.82 +/- 0.07 (stat) +/- 0.06 (sys) h; T1/2(73Se) = 7.18 +/- 0.02
(stat) +/- 0.004 (sys) h; T1/2(83Sr) = 31.87 +/- 1.16 (stat) +/- 0.42 (sys) h;
T1/2(85mSr) = 68.24 +/- 0.84 (stat) +/- 0.11 (sys) min; T1/2(63Zn) = 38.71 +/-
0.25 (stat) +/- 0.10 (sys) min. These high-precision half-life measurements
will contribute to a more accurate determination of corresponding ground-state
photoneutron reaction rates, which are part of a broader effort of constraining
statistical nuclear models needed to calculate stellar nuclear reaction rates
relevant for the astrophysical p-process nucleosynthesis.
