Use of photodiode in microdosimetry and evaluation of effective quality factor

A silicon photodiode in conjunction with a charged particle radiator placed in front of the sensitive layer was employed to construct a microdosimetric detector. Silicon photodiodes of different types (PN, PIN and PNN) and of different sensitive layers (1, 3, 5 and 8 μm) were used to obtain the pulse height spectrum for an AmBe neutron source. The data were analysed to determine the microdosimetric spectra and the effective quality factor overlineQ was estimated. Two types of corrections were needed for the estimate of overlineQ. One is related to the weighting function Q( L) and the other deals with the fractional relative dose d( L). The results were compared with those obtained with Tissue Equivalent Proportional Counter (TEPC) of 1 μm simulated diameter and were found to be in good agreement.