Performance characteristics of the CMOS SSPM tissue-equivalent space dosimeter

The complexity of space-flight design requires reliable, fault-tolerant equipment capable of providing real-time dosimetry during a mission, which is not feasible with the existing thermoluminescent dosimeter (TLD) technology, especially during extravehicular activity (EVA). Real-time monitoring is important for low-Earth orbiting spacecraft and interplanetary space flight to alert the crew when Solar Particle Events (SPE) increase the particle flux of the spacecraft environment. A tissue-equivalent, chip-based, personal dosimeter represents an attractive approach to meet the demanding requirements for manned space missions. A dosimeter-on-a-chip for personal dosimetry is comprised of a tissue-equivalent scintillator coupled to a solid-state photomultiplier (SSPM) built using CMOS technology. The radiation sensitive component of the dosimeter is coupled to analog signal processing components and a microprocessor, which can successfully process up to 5 × 10⁵ events per second. The dynamic range of the dosimeter has been verified with 1-GeV protons (0.22 keV/¿m in H₂0) to 300 MeV/n Fe (238 keV/¿m in H₂0). The dosimeter reconstructed does over 6 to 36 ¿Sv from 1-GeV protons to within 3%. We present dose equivalent performance of the device, along with power consumption parameters, expected space flight performance, and design upgrades.