Measurement Of The O-16(N, Alpha)C-13 Cross-Section Using A Double Frisch Grid Ionization Chamber

The O-16(n,alpha)C-13 reaction was proposed to be measured at the neutron time-of-flight (n_TOF) facility of CERN. To this purpose, a Double Frisch Grid Ionization Chamber (DFGIC) containing the oxygen atoms as a component in the counting gas coupled with a switch device in order to prevent the charge collection from the so-called gamma-flash has been developed at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), in Germany. The first O-16(n, alpha)C-13 measurement without seeing the charge of the gamma-flash at n_TOF has been performed in November 2018. After the electronics did not suffer from the gamma-flash any more, another huge charge collection was discovered. Due to the high instantaneous flux at the n_TOF facility [1] the amount of that induced charge from neutron induced background reactions was piling up so much that the recognition of O-16(n,alpha)C-13 reactions from that background was very difficult. For that reason another O-16(n, alpha)C-13 measurement at the time-of-flight facility nELBE at HZDR which has a low instantaneous flux [2], has been performed in April 2019. Both measurements from n_TOF and nELBE will be presented here.