A feasibility study of a solid-state microdosimeter

A solid-state silicon detector is a challenging device for microdosimetry, mainly because it can provide sensitive zones of the order of a micrometer. Moreover, these detectors are characterized by a high spatial and a good energy resolution. However, they may present some limitations, such as: (i) the minimum detectable energy which is limited by the electronic noise; (ii) radiation hardness; (iii) the geometry of the sensitive volume; (iv) the field-funnelling effect; (v) the non-tissue-equivalence of silicon. This work discusses a feasibility study of a microdosimeter based on a monolithic silicon telescope, consisting of a ΔE and an E stage-detector, about 1 and 500 μm thick, respectively. Charges are collected separately in the two stage-detectors. The use of the ΔE stage coupled with a tissue-equivalent converter was investigated as a solid-state microdosimeter. Irradiations with monoenergetic neutrons were performed at the INFN-Laboratori Nazionali di Legnaro (Italy). The field-funnelling effect appears to be negligible from the comparison of the experimental data with the results of Monte Carlo simulations, performed with the FLUKA code. The preliminary results of an analytical approach for the correction for geometrical effects and tissue-equivalence are also presented.