Beta Decay ofAl29

Abstract

The $\beta$ decay of ${\mathrm{Al}}^{29}$ has been investigated by forming the activity in the ${\mathrm{Al}}^{27}(t, p){\mathrm{Al}}^{29}$ reaction at an incident triton energy of 3.1 MeV. $\beta$ branches were studied by observing the subsequent ${\mathrm{Si}}^{29}$ $\gamma$-ray singles with NaI(Tl) and Ge(Li) detectors and $\gamma -\gamma$ coincidences in two 3×3-in. NaI(Tl) detectors. In addition to the previously reported $\beta$ branches to the 1273-, 2028-, and 2426-keV states in ${\mathrm{Si}}^{29}$, a $\beta$ branch to the 3069-keV level was observed. The ${\mathrm{Al}}^{29}$ $\beta$ branches in percent and the corresponding $log\mathrm{ft}$ values for decays to the 1273-, 2028-, 2426-, and 3069-keV levels in ${\mathrm{Si}}^{29}$ were found to be 90.1±1.0, 5.09±0.01; 3.6±0.4, 5.74±0.05; 6.3±0.5, 4.99±0.04; and 0.027±0.011, 6.16±0.18, respectively. Measurements of the excitation energies of the first three excited states of ${\mathrm{Si}}^{29}$ yielded (in keV) 1273.3±0.2, 2027.8±0.4, and 2425.7±0.4. It was also found that the 2426-keV level has a (0.4±0.1)% $\gamma$ branch to the 2028-keV level in ${\mathrm{Si}}^{29}$.