On the location of the second Jπ = 0 +, T = 1 state in 26Al

Abstract

Gamma-ray branching ratios have been measured for several states near E x = 3.7 MeV in 26A1 with the 24Mg(τ, pγ), 25Mg(τ, dγ) and 27Al(τ, αγ) reactions. Reaction particles were detected at 0° in coincidence with de-excitation γ-rays. Proton angular distributions were measured at E τ = 11 MeV for the 24Mg(τ, p) 26Al reaction to the 3.72 and 3.75 MeV levels. The results yield an assignment of J π = 1 +, T = 0 for the 3.72 MeV state, in disagreement with a recent J π = 0 +, T = 1 assignment, but in agreement with an earlier assignment of J = 1. The 3.75 MeV level is observed to be a close doublet. One member of this doublet is preferentially excited in the 25Mg(τ, dγ) and 27Al(τ, αγ) reactions and is associated with a previous assignment of J π = 2 + or 3 +. The second member of the 3.75 MeV doublet is preferentially excited in the 24Mg(τ, pγ) reaction and is identified as the second 0 +, T = 1 state in 26A1. Branching ratio results for the 3.68 MeV level establish that this level is also a close doublet. Results for the 3.59 MeV state are in agreement with previous work.