Precision measurement of $^{23}$Al beta-decay

The beta-decay of $^{23}$Al (See [1]) was re-measured with higher statistics and better accuracy at Texas A{\&}M University. Using MARS we produced and separated pure $^{23}$Al at 4000 pps, with a 48 MeV/u $^{24}$Mg beam via the $^{24}$Mg (p, 2n)$^{ 23}$Al reaction on a H$_{2}$ cryogenic target. New $\beta $ and $\beta -\gamma $ coincidence measurements were made with a scintillator, an HPGe detector with BGO shielding and the fast tape transport system. The BGO Compton shield very much improved the quality of the $\gamma $ spectra around the transition from the IAS state at 7803 keV. From the measured $\beta $ singles and $\beta -\gamma $ coincidence decay spectra we obtained an improved $\beta $-decay scheme and a more precise lifetime: t=447(4) ms. We use the method of detailed balance to obtain absolute $\beta $-branching ratios and absolute log\textit{ft} values for transitions to final states in $^{23}$Mg. For this method, precise efficiency calibration of the HPGe detector up to about 8 MeV is needed. We extended our previous efficiency calibration to the range E$_{\gamma }$=3.5-8 MeV using the $\beta $-decay of $^{24}$Al. \newline [1] V.E. Iacob, Y. Zhai et al., Phys. Rev. C 74, 045810 (2006).