Lifetimes and decay of the 2.07 MeV triplet in ²⁶Al

Abstract

Gamma rays from resonances at E p = 956, 1199, 1287, and 1701 keV in the reaction 25 Mg(p,γ) 26 Al have been studied using 40 cm 3 and 25 cm 3 Ge(Li) detectors. Accurate γ-ray energy determinations and Doppler shift measurements indicate the existence of three levels at excitation energies of 2068.7, 2069.5, and 2071.7 keV. The level at 2068.7 keV has a mean lifetime of [Formula: see text] and decays 29% to the ground state, and 71% to the 416.6 keV level. The 2069.5 keV level has a mean lifetime of (1.3 ± 0.5) × 10 −14 s and decays 5% to the 228.2, 22% to the 416.6, and 73% to the 1057.7 keV levels. The level at 2071.7 keV has a lifetime of [Formula: see text] and decays to the 228.2 keV (> 65%) and the 1057.7 keV (< 35%) levels. An upper limit of τ < 10 −14 s has been placed on the lifetime of the 3159.4 keV level and the mean lifetime of the 1850.8 keV level has been measured to be (1.6 ± 0.7) × 10 −14 s.