出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The cross section of the 13C(a,n)16O reaction is a key ingredient for the comprehension of the
s-process (slow neutron captures) in stars. This reaction is considered as the main neutron source
for the s-process in low-mass Asymptotic Giant Branch (AGB) stars (1-3 solar mass) [1, 2, 3].
At the a-13C energies of astrophysical interest (Ecm around 190 keV, corresponding to a temperature
of 108 K) the contribution of the 17O a-decay subthreshold resonance at 6.356 MeV
to the 13C(a,n)16O cross section should be taken into account. The effect of this resonance is
controversial after the different analyses of the Kubono et al. measurement [4] of the 6.356 MeV
a-spectroscopic factor (Sa ) via the transfer reaction 13C(6Li,d)17O .
In order to further investigate the contribution of the 6.356 MeV resonance to the 13C(a,n)16O
cross section, we performed a new measurement of its Sa factor via a different a-transfer reaction,
namely the 13C(7Li,t)17O reaction. The experiment was performed at the Orsay Tandem by
using a 7Li beam of 28 and 34 MeV on a 13C target. The angular distribution for the transfer differential
cross section was measured by detecting the tritons at the focal plane of the SPLITPOLE
spectrometer. The analysis procedure used in order to extract the yield of the 6.356 MeV level
will be described. Preliminary results of the angular distribution will be shown.
