Charge spectra of cosmic ray nuclei measured with CR-39 detectors in low earth orbit

Galactic Cosmic Rays (GCR) nuclei play an important role in the radiation exposure of humans in Low Earth Orbit (LEO). CR-39 nuclear track detectors have been successfully used to measure the charge spectrum of cosmic rays and related radiation dose in LEO. The method for measuring charge spectrum is based on the analysis of the etch rate gradient and effective etch rate ratio, along with calibration by high-energy heavy ions at particle accelerators. Here we report our results obtained in the interior of spacecraft for the STS-108, STS-112 and ISS-7S missions. Comparisons have been made between experimental and theoretical predictions and show good agreement.