Micro-IBICC and micro-IL analyses of CVD diamond microdosimeters

Diamond is an ideal material to fabricate dosimeters because it is tissue equivalent, chemically stable, non-toxic, mechanical and radiation hard. Chemical vapour deposition technique (CVD) allows for the fabrication of small diamond detectors, which can be considered for in vivo dose measurements. We have fabricated microdosimeters by depositing thin diamond films (<20 μm thick) on tungsten wires (diameter below 300 μm). Such devices work as solid state ionisation chambers where the electrodes are the W substrate and a thin gold layer evaporated on the diamond surface. The ion beam-induced charge collection (IBICC) and ionoluminescence (IL) techniques turn out to be very suitable to characterise such small and irregularly shaped microdosimeters. The uniformity of the electronic quality of diamond has been evaluated by mapping the charge collection efficiency as obtained by IBICC measurements, whereas IL was used to map radiative recombination centres as well as to study radiation damage effects. Finally, a synergetic combination of PIXE and IL maps allowed us to evaluate the shape of the diamond film covering the W substrate