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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2405.02742 |
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Table of Contents:
- We have measured the isospin mixing of the I$^π$= 1/2$^+$ E$_x$=2.599 MeV state in nearly-doubly-magic $^{47}$Ca with the isobaric analog 1/2$^+$ state of $^{47}$K. Using the TRIUMF atom trap for $β$ decay, we have measured a nonzero asymmetry of the progeny $^{47}$Ca with respect to the initial $^{47}$K spin polarization, which together with the $β$ asymmetry implies a nonzero ratio of Fermi to Gamow-Teller matrix elements $y$= 0.098$\pm$0.037 for the $1/2^+ \rightarrow 1/2^+$ transition. Interpreting $y$ as mixing between this state and the isobaric analog state implies a Coulomb matrix element magnitude 101 $\pm$ 37 keV. This relatively large matrix element supports a model from the literature of analog-antianalog isospin mixing, which predicts large matrix elements in cases involving excess neutrons over protons occupying more than one major shell. The result supports pursuing a search for time-reversal odd, parity-even, isovector interactions using a correlation in $^{47}$K $β$ decay.