Spectroscopy of positive parity states in 26Mg and 26Al via the ( alpha,3He) and ( alpha,t) reactions.

The ({alpha},{sup 3}He) and ({alpha},{ital t}) reactions on {sup 25}Mg were measured at {ital E}{sub {alpha}}=50 MeV. Cross sections obtained for 57 positive parity states in {sup 26}Mg and {sup 26}Al were analyzed within the framework of the exact-finite-range distorted-wave Born approximation and compared to the full {ital s}-{ital d} shell model predictions. Reasonable agreement between the experimental strengths and the theory was obtained for the low lying states. Deviations of factors of 2 or more were found for some high lying 2{sup +}, 3{sup +}, and 4{sup +} states in {sup 26}Al and especially for the 1{sub 1}{sup +} state in {sup 26}Mg. The spectroscopic factors for the transitions to the analog states in {sup 26}Mg and {sup 26}Al were compared between these reactions. The same strength was obtained for the 6{sub 1}{sup {minus}}, {ital T}=1 state in {sup 26}Mg and {sup 26}Al, whereas an enhancement of about 30% was observed for the 0{sub 1}{sup +} and 3{sub 1}{sup +}, {ital T}=1 states in {sup 26}Al. Further, 1{sup +} states in {sup 26}Mg proposed around {ital E}{sub {ital x}}=10 MeV through the ({ital p},{ital p}{prime}) reaction were also observed in the {sup 25}Mg({alpha},{sup 3}He) reaction without the special enhancementmore » for the 10.6 MeV 1{sup +} state seen in the ({ital p},{ital p}{prime}) reaction. The total observed strengths for neutron stripping to the positive-parity states in the region of {ital E}{sub {ital x}}=0--11 MeV almost attained the limit of the pure {ital j}-{ital j} coupling scheme. Those for the proton stripping were 70% of the limit in the region of {ital E}{sub {ital x}}=0--8 MeV.« less