Radiation Environment on the International Space Station During the Solar Particle Events in March 2012

Abstract

The Liulin-5 charged particle telescope observes the radiation characteristics in the spherical tissue-equivalent phantom of MATROSHKA-R international project on the International Space Station (ISS) since June 2007. In this paper attention is drawn to the results from the measurements of dose rate and particle flux increase during the Solar Energetic Particles Events (SPE) occurred in March 2012. During that SPE the solar particles penetrated at high geographic latitudes in the regions of the south and north Earth magnetic poles and at 3 < L they caused particle flux and dose rates increase in all three detectors of Liulin-5, located at 40, 60 and 165 mm depths along the phantom’s radius. The maximum flux at 40 mm depth observed outside the South Atlantic Anomaly (SAA) during that SPE reached 7.2 part/cm2.s and the dose rate reached 107.8 μGy/h on 07.03.2012, 13:06 UT at L=4. The additional absorbed dose received from SPE is approximately 180 μGy and additional dose equivalent- approximately 448 μSv. These additional exposures are comparable to the averaged daily absorbed dose and dose equivalent measured in the spherical phantom in ISS during quite radiation conditions. Discussed are the linear energy transfer spectra measured and quality factors obtained during and after the SPE. Compared are data from Liulin-5 and other particle detectors in space during the SPE.