Radiation field of cosmic rays measured in low Earth orbit by CR-39 detectors

Abstract In low Earth orbit astronauts are exposed to a radiation field composed of galactic cosmic rays, solar particles, particles in the Earth’s radiation belts and albedo neutrons and protons from the Earth’s atmosphere. Linear Energy Transfer (LET) spectra have been measured for the STS-108, STS-112 and ISS-7S missions. Measurement of the radiation fields is based on accurate measurements of recoils and fragments produced in CR-39 detectors by cosmic ray primary and secondary protons and heavier nuclei and by secondary neutrons. The measured LET spectra were used to determine the corresponding absorbed dose and dose equivalent. Total flux of Z  ⩾ 2 was estimated and a charge spectrum was measured for STS-108 and STS-112 missions. Comparisons are made with the predictions of cosmic ray transport models.