Speaker
Description
Around half the elements heavier than iron originate from the astrophysical slow neutron-capture (s-) process. This mechanism occurs within the stellar environments of asymptotic giant branch and massive stars, where the endothermic 22Ne(α,n)25Mg reaction is one of the main sources of neutrons. This reaction competes with 22Ne(α,γ)26Mg across the astrophysical temperature regime 150 – 300 MK (Ecm = 300 – 750 keV). To constrain both the temperature at which neutron production is activated and how much 22Ne is converted to neutrons, it is essential to understand the contribution of resonances to the reaction rates. Several resonances for these 22Ne+α reactions have been directly measured down to Ecm = 706 keV. However, below 700 keV there remains considerable disagreement between experimental studies on the resonance strengths of crucial states. To confront this weakly-constrained energy region, at the ISAC-II beamline in TRIUMF (Canada) we performed a dedicated study of crucial 26Mg states using the indirect 22Ne(7Li,t)26Mg reaction. A 22Ne beam at 3 MeV/nucleon bombarded a 500 μg/cm2 LiF target, following which the gamma-rays and 26Mg recoils were measured using the TIGRESS and EMMA systems, respectively. The tritons were detected at backward laboratory angles using a Micron S3 silicon detector. We will present the setup and preliminary analysis from this study, the results of which are expected to enhance our understanding of these essential neon-burning reactions in stellar nucleosynthesis.
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