GEANT4 Simulations Response of Cylindrical Silicon-on-Insulator Microdosimeter Array Detector for Neutrons Detection

In the experiment about the radiation protection and radiation biology, microdosimeter is often used as a tool for tissue equivalent microdosimetry measurement. The characteristics of neutron energy response for the cylindrical SOI (Silicon-on-Insulator) microdosimeter arrays detector designed with different technology structures are simulated and compared with GEANT4 toolkit. In this work, the distributions of neutron linear energy spectra which influenced by influence angles of incident particles, types and depth of conversion materials are studied. The characteristics of neutron energy response with different kinds of conversion materials of the SOI microdosimeter arrays are mainly analyzed. Meanwhile, we also calculate dose distributions of linear energy spectra in a kind of novel cylindrical Silicon-on-Insulator microdosimeter arrays detector (with sensitive sizes to 1um and 2um) due to ²⁵²Cf neutron source. Comparisons between simulated data with the SOI microdosimeter measurement and previous reported experimental data with TEPC (tissue-equivalent proportional counter) show a rather good agreement. Differences partly due to different kinds of conversion materials are analyzed. The results show that LDPE (low-density polyethylene) is a better kind of tissue equivalent material for neutron microdosimetry, but the differences in the detection of higher linear energy range 10–100KeV/um between LDPE and other tissue-equivalent materials may be caused by the lack of microelements for LDPE material and the sensitivity to the angle of incidence in the linear energy range 10–100KeV/um also should not be neglected for the distorted spectrum caused by setting angular deviation of more than 45 degree on the detector surface. The main reason of the influence on the linear energy spectra from the larger angular deviation incidence is that the design of cylindrical shell structure of sensitive volume could increase the recorded length of the tracks of secondary particles of larger angular incidence neutron included in the sensitive volume cell. The results of calculations and analyses could provide some important information for the optimization to the SOI microdosimeter measurement.