Radiation measured with passive dosimeters in low Earth orbit

The linear energy transfer (LET) of particles in low Earth orbit (LEO) is extended from ∼0.2 to ∼1000 keV/μm water. The best passive dosimeters for radiation measurement are thermoluminescence dosimeters (TLDs) or optically stimulated luminescence dosimeters (OSLDs) for low LET and CR-39 plastic nuclear track detectors (PNTDs) for high LET. Radiation quantities (fluence, absorbed dose, dose equivalent and quality factor) were measured with passive dosimeters composed of TLDs/OSLDs and CR-39 PNTDs for the STS-114 mission. This paper introduces the operation principles for TLDs/OSLDs and CR-39 PNTDs, describes the method to combine the results measured by TLDs/OSLDs and CR-39 PNTDs, and presents the results measured by different dosimeters for different LET bands and that combined for all LET.