High-precision measurements of half‐lives for 69Ge, 73Se, 83Sr, 85mSr, and 63Zn radionuclides relevant to the astrophysical p-process via photoactivation at the Madison Accelerator Laboratory


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 γ-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.

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We are indebted to Professor H. J. Karwowski for his thorough reading and editorial comments on manuscript drafts. Additionally, we would like to thank J. E. Mayer for assisting in the initial data reduction and Dr. P. Mohr for reading and insightful commenting on the early manuscript draft. Last but not least, we highly appreciated the thorough reviews by the anonymous reviewers. A. B. and T. A. H. acknowledge support by the National Science Foundation through Grant No. Phys-1913258. J. A. S. acknowledges that this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under the Contract No. DE-AC52-07NA27344.

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Hain, T.A., Pendleton, S.J., Silano, J.A. et al. High-precision measurements of half‐lives for 69Ge, 73Se, 83Sr, 85mSr, and 63Zn radionuclides relevant to the astrophysical p-process via photoactivation at the Madison Accelerator Laboratory. J Radioanal Nucl Chem (2021). https://doi.org/10.1007/s10967-020-07589-5

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  • Nuclear reactions: 70Ge(γ,n)69Ge, 74Se(γ,n)73Se, 84Sr(γ,n)83Sr, 86Sr(γ,n)85mSr, 64Zn(γ,n)63Zn
  • Half‐life
  • Photoactivation
  • Off‐line γ-ray spectrometry