Response of various LiF thermoluminescent detectors to high energy ions – Results of the ICCHIBAN experiment

Within the ICCHIBAN inter-comparison experiment organized at the HIMAC accelerator in Chiba, Japan, LiF:Mg,Ti (MTS-7, MTS-6 and MTT-7) and LiF:Mg,Cu,P (MCP-7) thermoluminescent detectors were exposed to beams of energetic He, C, Si, Ne, Fe, Ar and Kr ions. Several thousand thermoluminescent (TL) detectors of similar types were recently applied in the MATROSHKA space dosimetry experiment, where a humanoid phantom containing such detectors underwent an 18-month exposure outside the International Space Station. The ICCHIBAN project was designed to provide means of calibrating these detectors in high-LET fields. The energy of the ion beams ranged between 60 MeV/amu and 460 Mev/amu, and the corresponding ion LET values – between 2.2 keV/μm and 595 keV/μm (in water). For each ion specie the relative TL efficiency was evaluated. Interestingly, the measured relationship between relative TL efficiency and LET for these ions was found to follow unique trend lines. The efficiency of all types of LiF:Mg,Ti detectors exposed to energetic He ions was found to exceed efficiency for gamma-rays.