Wednesday 19 April 2017, 2.00PM to 4.00pm
Speaker(s): Dr Carlo Bruno
Asymptotic Giant Branch (AGB) stars are the site of several mixing and recirculating processes, some of which are still not completely understood. Constraining them would improve our understanding of stars that are in or will enter the AGB phase, including our own Sun. An ideal way to trace these poorly-understood mixing processes are the rare, stable 17,18O isotopes. Their abundances are strongly sensitive to the rate of the 17O(p,a)14N and 18O(p,a)15N reactions.
An experimental campaign aimed at measuring these two reactions was recently completed at the underground LUNA accelerator at Gran Sasso Laboratories, Italy. A proton beam was accelerated on a solid Ta2O5 target and the alpha particles produced by the reactions were detected at backward angles.
I will introduce the underground LUNA accelerator and describe the results of the experimental campaign aimed at measuring the 17,18O(p,a)14,15N reactions. These results can solve a long-standing puzzle on the isotopic abundances observed in some pre-solar grains.