Some importance values on Gas Cerenkov:
1, There 10 mirrors to collect the light then focusson 10 PMTs.
2, Filled with CO2: n=1.00041.
3, 1000mm for the GC in R-HRS and 1500mm for the GC in L-HRS.
4, Light emission threshold: for electron ~ 0.017 GeV/c, for pion ~ 4.8 Gev/c.