Characterization of silicon detectors for studies of deep sub-barrier heavy-ion fusion by coincidences with the AGATA gamma-spectrometer

by Alexcobo Zarzuelo, 1st year PhD student at GANIL

This Master Thesis aims to provide better understanding of deep sub-barrier heavy ion fusion by proposing a combined set-up of Agata gamma-spectrometer and silicon detectors. The fusion events will be identified by coincidences between the prompt γ-rays and the light charged particles (p, α) evaporated from the compound nucleus. This is motivated by recent experiments involving the fusion of 12C + 24Mg where the measured excitation function clearly showed evidence of the “hindrance” phenomenon. Discriminating between the various models interpreting the observed S-factor maximum, at lower energies than the ones already available, would imply the measurement of cross sections below the microbarn level. The silicon detectors employed in this thesis were: two double-sided annular detectors and one strip detector. They were characterised by means of correlations between the the applied voltage and the leakage current , alpha particle energy resolution and spatial resolution. The detectors fulfilled the required condition for a wide range of nuclear physics experiments. The annular detectors were used in the measurement of light particles produced by a proton beam impinging on a cryogenic helium target. Overall, this work has offered a better understanding of the new set of silicon detectors and it showed their viability to perform measurements of light charged particles on in-beam fusion experiments.