Measurement of the low energy resonances in $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction
ORAL
Abstract
${^{13}\rmC(a,n)^{16}\rmO}$ and $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ are considered the two important neutron sources for the s-process, but there is still uncertainty about the total available neutron flux for the s-process. ${^{13}\rmC(a,n)^{16}\rmO}$ determines the neutron production in AGB stars while $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$, which occurs during core helium and carbon shell burning, acts as the primary neutron source in massive stars. But the $\Nean$ reaction has a negative Q-value $= -478\pm 0.05$ keV and hence operates only at high temperatures, e.g., the peak of helium burning, and during C-shell burning (if sufficient $^{22}\rm{Ne}$ is available). Moreover, the neutron-producing role of $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ is complicated by the competing $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction, which has a positive Q-value $=10614.74\pm 0.03$ keV and therefore starts operating at relatively lower temperatures, before $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ can kick in. Hence it is important to investigate the reaction rate of $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ in order to put quantitative constraints on the neutron production for the weak s-process. It was experimentally observed by the direct measurements that the reaction rate for $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ is strongly impacted by the low energy resonance at $\rmE_{\alpha}$(lab) = 828 keV, but the recent indirect measurements show that the resonance at $\rmE_{\alpha}$(lab) = 653 keV can appreciably impact the $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction rate. The measurement of both these resonances was performed at Sanford Underground Research facility (SURF), CASPAR. Preliminary analysis of the resonance strengths for these two resonances will be presented.
*This work was funded by the NSF under contract Numbers PHY-2011890 (NSL), PHY-1913746 (CASPAR) and the Joint Institute for Nuclear Astrophysics PHY-1430152,
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Presenters
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Shahina Shahina
- University of Notre Dame