Experimental study of the 18O(d, p)19O reaction and the ANC Method

Abstract

The neutron capture rate 18O(n, γ)19O is important for analysis of nucleosynthesis in inhomogeneous Big Bang models and also for models of helium burning in massive red giant stars and AGB stars. Angular distributions of the 18O(d, p)19O reaction were measured at a deuteron energy of 16.3 MeV in NPI in Rez, Czech Republic, with the aim to determine Asymptotic Normalization Coefficients which can then be used for indirect determination of the direct contribution to the 18O(n, γ)19O process. In the experiment, the gas target with 18O isotope of high purity 99.9% was used thus eliminating any contaminating reactions. Reaction products were measured by the set of 8 ΔE-E telescopes consisting of thin and thick silicon surface-barrier detectors. Angular distributions of proton transfers corresponding to 6 levels of 19O up to the 4.1093 MeV excitation energy were determined. The analysis of angular distributions in the angular range from 6 to 64 degree including also the angular distribution of elastically scattered deuterons was carried out by means of ECIS and DWUCK codes. From the determined ANCs the direct contribution to the radiative capture 18O(n, γ)19O was deduced.