2024/01/26 by Z. W. Ge, Ge, Z., T. Eronen +43
Physics and Astronomy · #Advanced Chemical Physics Studies #Atomic and Molecular Physics #FOS: Physical sciences #Nuclear Experiment (nucl-ex) #Nuclear physics research studies
paper · pdf · doi:10.48550/arxiv.2401.15242
openalex publication_date 2024/01/26 · openalex created_date 2024/02/01 · openalex updated_date 2026/07/30
The first direct determination of the ground-state-to-ground-state β--decay Q-value of 77As to 77Se was performed by measuring their atomic mass difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The resulting Q-value is 684.463(70) keV, representing a remarkable 24-fold improvement in precision compared to the value reported in the most recent Atomic Mass Evaluation (AME2020). With the significant reduction of the uncertainty of the ground-state-to-ground-state Q-value and knowledge of the excitation energies in 77Se from γ-ray spectroscopy, the ground-state-to-excited-state Q-value of the transition 77As (3/2-, ground state) → 77Se* (5/2+, 680.1035(17) keV) was refined to be 4.360(70) keV. We confirm that this potential low Q-value β--decay transition for neutrino mass determination is energetically allowed at a confidence level of about 60σ. Nuclear shell-model calculations with two well-established effective Hamiltonians were used to estimate the partial half-life for the low Q-value transition. The half-life was found to be of the order of 109 years for this first-forbidden non-unique transition, which rules out this candidate a potential source for rare-event experiments searching for the electron antineutrino mass.