High Precision Measurement of the Superallowed 0+ to 0+ Beta Decay of 22Mg
Abstract
The half-life, 3.8755(12) s, and superallowed branching ratio, 0.5315(12), for 22Mg beta-decay have been measured with high precision. The latter depended on gamma-ray intensities being measured with an HPGe detector calibrated for relative efficiencies to an unprecedented 0.15%. Previous precise measurements of 0+ to 0+ transitions have been restricted to the nine that populate stable daughter nuclei. No more such cases exist, and any improvement in a critical CKM unitarity test must depend on precise measurements of more exotic nuclei. With this branching-ratio measurement, we show those to be possible for Tz = -1 parents. We obtain a corrected Ft-value of 3071(9) s, in good agreement with expectations.
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