Linear focal cherenkov camera for the t-ACTS injector

Thermionic RF gun has a potential ability for producing very short electron bunch. However, because space charge effects in the RF gun are not fully understood, an efficient bunch compression scheme has been not well designed so far. In order to measure the distribution in the longitudinal phase space of relatively lower energy electrons extracted from the thermionic RF gun, we have been developing a novel method to observe the energy spectrum employing a velocity dependence of opening angle of Cherenkov radiation. We have performed numerical ray-trace simulations and discuss intrinsic energy and temporal resolution of the system.