Thu·Dec 31, 2020Thursday·December 31, 2020

1. 01*

   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

   T. A. Hain🇺🇸 · S. J. Pendleton🇺🇸 · J. A. Silano🇺🇸 · A. Banu🇺🇸

   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.

   nucl-exJ.Radioanal.Nucl.Chem.(2021)·1 citation
2. 02*

   A novel experimental system for the KDK measurement of the ${}^{40}$K decay scheme relevant for rare event searches

   M. Stukel🇨🇦 · B. C. Rasco · N. T. Brewer · P. C. F. Di Stefano🇨🇦 · K. P. Rykaczewski · H. Davis🇺🇸 · E. D. Lukosi🇺🇸 · L. Hariasz🇨🇦 · M. Constable · P. Davis · K. Dering · A. Fijałkowska🇵🇱 and 17 other authors

   Potassium-40 (${}^{40}$K) is a long-lived, naturally occurring radioactive isotope. The decay products are prominent backgrounds for many rare event searches, including those involving NaI-based scintillators. ${}^{40}$K also plays a role in geochronological dating techniques. The branching ratio of the electron capture directly to the ground state of argon-40 has never been measured, which can cause difficulty in interpreting certain results or can lead to lack of precision depending on the field and analysis technique. The KDK (Potassium (K) Decay (DK)) collaboration is measuring this decay. A composite method has a silicon drift detector with an enriched, thermally deposited ${}^{40}$K source inside the Modular Total Absorption Spectrometer. This setup has been characterized in terms of energy calibration, gamma tagging efficiency, live time and false negatives and positives. A complementary, homogeneous, method is also discussed; it employs a KSr${}_2$I${}_5$:Eu scintillator as source and detector.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2021)·4 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.