Speaker
Mr
Nicolas Hubbard
(University of York)
Description
Within the C/Ne convective shell of a massive star the 23Na(α,p)26Mg reaction is an important source of protons for 26Al production[1]. This shell is also the main source of Na ejected by core-collapse supernovae. A new experimentally determined reaction rate has been calculated across the relevant temperature range based on 3 new cross-section measurements [2-4] and angular distributions measured at the Aarhus University 5 MV Van de Graaff.
A recent measurement by Almaraz-Calderon et al. [2] found cross-sections 40 times greater than statistical-model cross-sections. Two additional experiments were performed by Howard et al. [3] and Tomlinson et al. [4], who both found results more consistent with statistical cross-sections. A follow up study by Almaraz-Calderon et al. identified a scaling problem in their original data, and after correcting this [5], it is more consistent with the others.
Combining these data, a full reaction rate study incorporating newly measured angular distributions has been performed. Experimental data is particularly important for this reaction, as the statistical models are not expected to have good predictive power because of the low density of states [1]. The data from [3] include measured angular distributions which have been extended and are used to reduce the systematic uncertainties in [4] and [5]. A combined reaction rate is calculated to a low uncertainty, improving the reliability of theoretical predictions of 23Na and 26Al in massive stars.
Primary author
Mr
Nicolas Hubbard
(University of York)
