We have tested prototypes with radiators of 240 x 65 x 1mmt and also 2mmt using energy-degraded Ar & Kr beams between 170 ? 400 MeV/A.
From the study on position & angle dependences, we decided to put PMT’s on both side of the radiator.
From the energy dependence of the Cherenkov light yield, energy dependence of the velocity resolution is estimated. Effect of the TIR threshold is clearly seen. Velocity resolution of about 0.2% (rms), which is factor of 2 worse than necessary, was obtained.
We also decided to use 2mm-thick radiator to cover the wider energy range.
Using rigidity-analyzed (Δp/p~0.1%) secondary beams at ~270 MeV/A, we have studied the mass separation. Isotopes around mass 70 could be separated with about 4σseparation for rigidity-analyzed secondary beams.
Due to the thickness of the radiator (~1.2 g/cm2), reaction loss in the radiator is estimated to be about 5%.
Prototype study shows that TIRC has enough mass resolving power below mass 80 around 270 MeV/A. But we have also noticed the radiation-damage effect.
