Speaker
Description
Heavy element synthesis in explosive stellar environments, such as core-collapse supernovae, is influenced by key nuclear reactions involving unstable nuclei. In neutron-rich conditions, the $\alpha$-process, which involves a sequence of ($\alpha$,xn) reactions, plays a significant part in nucleosynthesis, whereas (p,n) reactions influence element formation during explosive silicon burning and the $\nu$p-process. However, experimental data on these reactions remain scarce, introducing significant uncertainties in astrophysical models.
Although SECAR (SEparator for CApture Reactions) is primarily designed for capture reactions, it can be utilized to measure the heavy recoils from other reactions. A new technique has been developed for direct measurements of both ($\alpha$,n) and (p,n) reactions in inverse kinematics with SECAR. The development of machine learning-assisted ion-optics rendered the study of (p,n) reactions using a separator feasible. The $^{58}$Fe(p,n) reaction measurement served as a validation of the method. Additionally, SECAR’s capabilities have been extended to include ($\alpha$,n) reaction measurements. The first case studied was the $^{86}$Kr($\alpha$,n) reaction, which influences $\alpha$-process nucleosynthesis and metal-poor star abundances.
In this contribution I will present the recent ($\alpha$,n) and (p,n) reaction measurements with SECAR, highlighting their astrophysical significance and the experimental advancements that enable these studies. These results pave the way for future direct measurements of reaction rates on short-lived nuclei, which will significantly improve our understanding of heavy-element nucleosynthesis.
