The (t,3He) and (3He, t) reactions as probes of Gamow-Teller strength

It is shown via a study on a {sup 26}Mg target that the (t,{sup 3}He) reaction at 115 MeV/nucleon reaction is an accurate probe for extracting Gamow-Teller transition strengths. To do so, the data are complemented by results from the {sup 26}Mg({sup 3}He, t) reaction at 140 MeV/nucleon that allows for a comparison of T=2 analog states excited via the mirror reactions. Extracted Gamow-Teller strengths from {sup 26}Mg(t,{sup 3}He) and {sup 26}Mg({sup 3}He, t) are compared with those from {sup 26}Mg(d,{sup 2}He) and {sup 26}Mg(p,n) studies, respectively. A good correspondence is found, indicating probe independence of the strength extraction. Furthermore, we test shell-model calculations using the new USD-05B interaction in the sd-model space and show that it reproduces the experimental Gamow-Teller strength distributions well. In anticipation of further (t,{sup 3}He) experiments on medium-heavy nuclei aimed at determining weak-interaction rates of relevance for stellar evolution, a second goal of this work is to improve the understanding of the (t,{sup 3}He) and ({sup 3}He, t) reaction mechanisms at intermediate energies because detailed studies are scarce. The distorted-wave Born approximation is employed, taking into account the composite structures of the {sup 3}He and triton particles. The reaction model provides the means to explainmore » systematic uncertainties at the 10%-20% level in the extraction of Gamow-Teller strengths as being because of interference between Gamow-Teller {delta}L=0,{delta}S=1 and {delta}L=2,{delta}S=1 amplitudes that both contribute to transitions from 0{sup +} to 1{sup +} states.« less