Deep underground laboratory measurement of ¹³C(a,n)¹⁶O in the Gamow windows of the s- and i-processes

Prof. Xiaodong Tang and JUNA collaboration
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
Joint Department for Nuclear Physics, Lanzhou University and Institute of Modern Physics, Lanzhou, China

The ¹³C(a,n)¹⁶O reaction is the main neutron source for the slow-neutron-capture (s-) process in Asymptotic Giant Branch stars and for the intermediate (i-) process. Direct measurements at astrophysical energies in above-ground laboratories are hindered by the extremely small cross sections and vast cosmic-ray induced background. We performed the first consistent direct measurement in the range of E_c.m. =0.24 MeV to 1.9 MeV using the accelerators at the China JinPing underground Laboratory (CJPL) and Sichuan University. Our measurement covers almost the entire i-process Gamow window in which the large uncertainty of the previous experiments has been reduced from 60% down to 15%, eliminates the large systematic uncertainty in the extrapolation arising from the inconsistency of existing data sets, and provides a more reliable reaction rate for the studies of the s- and i-processes along with the first direct determination of the a-strength for the near-threshold state.

Hosted by Prof. Wiescher