Fri·Apr 19, 2024Friday·April 19, 2024

1. 01*

   Systematic shell-model analysis of $2\nu \beta \beta$ decay of ${}^{76}$Ge and ${}^{96}$Zr to the ground and excited states of ${}^{76}$Se and ${}^{96}$Mo

   Deepak Patel🇮🇳 · Praveen C. Srivastava🇮🇳 · Jouni Suhonen🇫🇮

   In this work, we have studied the $2\nu \beta \beta$ decay of ${}^{76}$Ge and ${}^{96}$Zr isotopes utilizing large-scale shell-model calculations. The GWBXG effective interaction has been employed in the calculation of $2\nu \beta \beta$-decay nuclear matrix elements (NMEs). We have tested the effective interaction by comparing the predicted spectroscopic properties, such as energy spectra and transition probabilities, with the available experimental data. The variation of cumulative NMEs with respect to the $1^{+}$ state energies of the intermediate nucleus is also studied, corresponding to $0_{g.s.}^{+}\to 0_{g.s.}^{+}$, $0_{g.s.}^{+}\to 0_2^{+}$, and $0_{g.s.}^{+}\to 2_1^{+}$ transitions between the parent and grand-daughter nuclei. The effective values of axial-vector coupling strength ($g_A^{\mathrm{eff}}$) are calculated using the predicted NMEs and experimental half-lives for $0_{g.s.}^{+}\to 0_{g.s.}^{+}$ transitions. The extracted half-lives for $0_{g.s.}^{+}\to 0_2^{+}$, and $0_{g.s.}^{+}\to 2_1^{+}$ transitions using the shell-model predicted NMEs are consistent with the recent experimental data. The comparison of the shell-model predicted NMEs with previous NMEs available in the literature is discussed. Also, the computed branching ratios for the $2\nu \beta \beta$ decay of ${}^{76}$Ge and both the $2\nu \beta \beta$ and single-$\beta$ decay of ${}^{96}$Zr are reported corresponding to the calculated $g_A^{\mathrm{eff}}$ values.

   ↳ nucl-thnucl-exPRC(2024)·5 citations
2. 02*

   Laser excitation of the ${}^{229}$Th nuclear isomeric transition in a solid-state host

   R. Elwell🇺🇸 · Christian Schneider🇦🇹 · Justin Jeet · J. E. S. Terhune🇺🇸 · H. W. T. Morgan🇺🇸 · A. N. Alexandrova🇺🇸 · H. B. Tran Tan🇺🇸 · Andrei Derevianko🇺🇸 · Eric R. Hudson🇺🇸

   LiSrAlF${}_6$ crystals doped with ${}^{229}$Th are used in a laser-based search for the nuclear isomeric transition. Two spectroscopic features near the nuclear transition energy are observed. The first is a broad excitation feature that produces red-shifted fluorescence that decays with a timescale of a few seconds. The second is a narrow, laser-linewidth-limited spectral feature at $148.38219(4{)}_{\text{stat}}(20{)}_{\text{sys}}$ nm ($2020407.3(5{)}_{\text{stat}}(30{)}_{\text{sys}}$ GHz) that decays with a lifetime of $568(13{)}_{\text{stat}}(20{)}_{\text{sys}}$ s. This feature is assigned to the excitation of the ${}^{229}$Th nuclear isomeric state, whose energy is found to be $8.355733(2{)}_{\text{stat}}(10{)}_{\text{sys}}$ eV in ${}^{229}$Th:\thor:LiSrAlF${}_6$.

   ↳ physics.atom-phnucl-exPRL(2024)·94 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.