A filter technique for optimizing the photon energy response of a silicon pin diode

Silicon PIN diodes have become popular as radiation detectors in electronic pocket dosimeters (EPD), where they are typically used in a pulse mode. However, current mode operation is also possible, especially at high dose rates. Because silicon is neither air nor tissue equivalent, means must be provided to flatten the dosimeter energy response. The problem is most serious in pulse mode because the count rate below 200keV is not proportional to air dose or kerma rates. Most EPDs use a simple filter to flatten the energy response, but at the cost of sacrificing response below 60keV. We present a new and inexpensive approach, which uses a composite filter, to extend the low-energy response of the diode to 15 keV in current mode and 25 keV in pulse mode while maintaining excellent response accuracy to 1.2 MeV in current mode and 6 MeV in pulse mode