Beta-Delayed Protons fromSi25

Abstract

Silicon-25 was produced by the ${\mathrm{Mg}}^{24}({\mathrm{He}}^3,2n){\mathrm{Si}}^{25}$ reaction with a 32-MeV ${\mathrm{He}}^3$ beam. The beta-delayed proton spectrum was measured from 0.7 to 6.0 MeV, with a resolution of 85 keV full width at half-maximum above 1.7 MeV. Eighteen proton peaks are identified and assigned to transitions from virtual levels of ${\mathrm{Al}}^{25}$. Three new levels of ${\mathrm{Al}}^{25}$ at 6.92±0.04, 7.25±0.03, and 8.20±0.03-MeV excitation energy are proposed in addition to the $T=\frac{3}{2}$ analog state at 7.90±0.02 MeV and a state at 8.97±0.04 MeV which had been seen in previous delayed-proton work. The ${\mathrm{Si}}^{25}$ half-life was determined to be 218±4 msec.