A silicon micro dosimeter for high-altitude measurements of cosmic radiation

The small size and low manufacturing costs of semiconductor dosimeters could make them ideal sensors for realtime measurements of biologically harmful radiation at aviation altitudes. This paper presents the system design, accumulated dose measurements, and dose rate calculation results obtained from the Teledyne UDOS001 total ionizing dose (TID) micro dosimeter as part of the NASA Radiation Dosimetry Experiment (RaD-X) stratospheric balloon mission. A commercial class TID sensor was used for the mission, measuring 35 mm × 25mm × 4.5 mm with a power consumption of 280 mW. The sensor was used to measure accumulated dose for 20 hours, with 18 hours of data at altitudes above 20 km, and it was integrated into the RaD-X payload with a custom interface printed circuit board, which provided power conditioning and signal buffering. An analog-to-digital (ADC) converter was then used to sample the sensors analog output at 15 Hz. To ensure the sensor temperature remained within operating limits (-30°C to 40°C), a thermal control system was used to maintain the temperature of the sensor. Post-flight analysis showed that the TID measured dose rates were in good agreement with an industry standard tissue equivalent proportional counter.