Neutron dosimetry on the International Space Station using a routine track etch personal dosemeter: neutron dose assessments within the HAMLET project

Abstract

Standard issue track etch neutron personal dosemeters have been used for measurements on board the International Space Station (ISS), but routine dose reporting is not possible because the radiation environment in the ISS is complex: additional methods are required beyond those used normally, to help identify and discard the signal that is due to charged particles that were not produced by neutron interactions. A different calibration is also required for the neutron-induced component of the signal because the neutron field extends to much higher energies than those encountered routinely in terrestrial workplaces. The analytical methods applied to make the necessary corrections are described in detail in this paper and some of the limitations are discussed. Use of these methods allows an estimate to be made of the neutron component of dose within the ISS environment. Specifically, measurements made during the ESA MATROSHKA contract and its subsequent scientific exploitation during the EC HAMLET project, are presented. Assessed neutron effective dose rates were in the range 58 µSv d⁻¹ to 151 µSv d⁻¹. Original dose estimates from model calculations performed during HAMLET are compared to that obtained by using recent environmental and radiation transport models, but the effect on the dose estimate is shown to be negligible.