Responses of TLD-BeO:Na (UD-170A) to heavy ions and space radiation

Responses of TLD-BeO:Na (UD-170A) to high-LET particles were examined with selected heavy ion beams (He, C, Ne, Ar, and Kr) at NIRS-HIMAC, and compared with TLD-Mg2SiO4:Tb (TLMS) and radiophotoluminescent glass (RPLG). The relative TL efficiency of UD-170A as 137Cs gamma ray equivalent arose notably with increasing LET infinity.H2O for He and C, and decreased for the heavier charged particles. In contrast, the efficiencies of TLMS and RPLG did not increase over the range of LET from 0.5 to 410 keV.micron-1. The three detectors were used for space radiation measurement in the Mir space station for 40 days at 400 km altitude and 51.65 degrees inclination. The values from each detector as gamma ray absorbed dose equivalent showed a large spatial variation by a factor 2 in the same Core module. The detector values were in the order of UD-170A > TLMS > RPLG as expected from the results obtained on the ground, although ratios of these values changed depending on positions. These results indicate that both radiation quality and dose level in a spacecraft change significantly and a measurement at one location cannot accurately represent the individual dose to an astronaut. These small detectors should be useful as supplementary personal dosemeters for astronauts.