Diamond detector : characterization of CVD diamond as radiation detector at IFJ-PAN (Cracow)

In this thesis I studied the properties of diamond single crystal detector to different kind of radiations. The detectors I studied are in use at the Radiation Transport Physics Department at IFJ-PAN in Cracow, which research is focused on theoretical and experimental analysis of plasma induced fusion reactions. Diamond is well suitable for use as a solid state radiation detector in future plasma reactors: it has a wide band gap, which reduces the thermally and light excited charge carriers, with low leakage current even at room temperature; electrons and holes have high mobility, that means fast responses and reduced charge carrier loss; its perfect crystal lattice is well suited for spectrometric capabilities of heavy charged particles and neutrons with a reduced gamma noise. It is also chemically inert and radiation hard, which makes it suitable for long term operations in high temperature and high flux environment. In my experiments I used two 50 µm single crystal detectors, irradiated with alpha particles, protons and neutrons. Alpha particles were obtained by a 239Pu-241Am-244Cm source: the detector has a resolution of 1% with a FWHM of 80 keV. CCE has been measured at different biases to fit the Hecht equation: average µτ has been found of 4×10^(−6)±10^(−2)cm^2/V for both electrons and holes. Similar tests have been conducted with 2 MeV protons, extracted at the micro-beam facility at IFJ-PAN, which can give beam of 10 µm with scanning capabilities. Mobility-time parameter has been found to be 9.5×10^(−6)±8.5×10^(−2) cm^2/V for holes and 2.0×10^(−6)±1.1×10^(−1) cm2/V for electrons. Charge collection efficiency resulted to be from 100% to 95% both with high proton current (up to 4000 cps) and long time irradiations (30 min). Two doses in the order of 10^15 p/cm^2 has been delivered in two different spots to induce defects on a previously damaged detector. The charge collection efficiency dropped from 64% to 11%, and from 55% to 30% in the second spot. Fast neutron generator in use at IFJ-PAN has been use to generate fast neutrons from DD and DT reactions. The response of good and damaged detectors has been compared to two 500 µm single crystal and polycrystalline detectors.