Tissue-equivalent solar particle dosimeter using CMOS SSPMs

A dosimeter-on-a-chip (DoseChip) comprised of a tissue-equivalent scintillator coupled to a solid-state photomultiplier (SSPM) built using CMOS technology represents an ideal technology for a space-worthy, real-time solar-particle monitor for astronauts. It provides a tissue-equivalent response to the relevant energies and types of radiation for low-Earth orbit and interplanetary space flight to the moon or Mars. The DoseChip will complement the existing Crew Passive Dosimeters by providing real-time dosimetry and as an alarming monitor for solar particle events (SPEs). A prototype of the DoseChip was exposed to protons at three incident energies at the NASA space radiation laboratory at Brookhaven National Laboratory. The prototype provides an unambiguous, proportional response for 200, 500, and 1000 MeV protons. The measured response produced a detector response function that was used to model the behavior of an improved instrument. The data presented here indicate that a 3 × 3 × 3 mm3 piece of BC-430 plastic scintillator coupled to a 2000-pixel SSPM can accommodate the needed dynamic range for protons with an incident energy of 20 MeV and greater.