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Observation of an ultra-low $Q$-value electron-capture channel decaying to $^{75}$As via high-precision mass measurement
- Publication Year :
- 2022
-
Abstract
- A precise determination of the atomic mass of $^{75}$As has been performed utilizing the double Penning trap mass spectrometer, JYFLTRAP. The mass excess is measured to be -73035.519(42) keV/c$^2$, which is a factor of 21 more precise and 1.3(9) keV/c$^2$ lower than the adopted value in the newest Atomic Mass Evaluation (AME2020). This value has been used to determine the ground-state-to-ground-state electron-capture decay $Q$ value of $^{75}$Se and $\beta^-$ decay $Q$ value of $^{75}$Ge, which are derived to be 866.041(81) keV and 1178.561(65) keV, respectively. Using the nuclear energy-level data of 860.00(40) keV, 865.40(50) keV (final states of electron capture) and 1172.00(60) keV (final state of $\beta^-$ decay) for the excited states of $^{75}$As$^*$, we have determined the ground-state-to-excited-state $Q$ values for two transitions of $^{75}$Se $\rightarrow$ $^{75}$As$^*$ and one transition of $^{75}$Ge $\rightarrow$ $^{75}$As$^*$. The ground-state-to-excited-state $Q$ values are determined to be 6.04(41) keV, 0.64(51) keV and 6.56(60) keV, respectively, thus confirming that the three low $Q$-value transitions are all energetically valid and one of them is a possible candidate channel for antineutrino mass determination. Furthermore, the ground-state-to-excited-state $Q$ value of transition $^{75}$Se $\rightarrow$ $^{75}$As$^*$ (865.40(50) keV) is revealed to be ultra-low (< 1 keV) and the first-ever confirmed EC transition possessing an ultra-low $Q$ value from direct measurements.<br />Comment: 7 pages, 3 figures
- Subjects :
- Nuclear Experiment
Subjects
Details
- Database :
- arXiv
- Publication Type :
- Report
- Accession number :
- edsarx.2203.00457
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevC.106.015501