Recent European measurements inside Biorack

The dosimetric package used inside Biorack on board STS76, STS81 and STS84 comprises passive detector stacks built from plastic nuclear track detector s (PNTDs), thermoluminescence detectors (TLDs) and one or two active DOSTEL (DOSimetric TELescope) units using planar silicon detectors. Five passive detector stacks were exposed at different places inside the BIORACK incubat ors and in different stowage positions. DOSTEL units were exposed inside th e 22 degrees C incubator in all flights. Mission integrated dose measuremen ts, particle fluence rates and neutron doses are obtained from the passive detector stacks. These results are complemented by time resolved particle c ounts and dose rates and linear energy transfer (LET) spectra separately fo r the contribution of the trapped particles and the galactic cosmic rays (G CR) as a result of the DOSTEL measurements. In addition, it was possible to investigate the anisotropy of the radiation field inside Biorack by the us e of a second DOSTEL unit on STS84. Since all exposures are during a solar minimum period, the total radiation exposure is of a similar extent for all flights, although position differences in dose rate up to a factor of two are observed. Particle fluence rates show lower variations. Mission average d mean quality factors (Q) determined from the LET spectra are 2.0 +/- 0.1; the deduced dose equivalent rates range from 631 to 716 mu Sv/day. (C) 199 9 Elsevier Science B.V. All rights reserved.