The Cerenkov detector is positioned between
the Drift Chamber
Region 3 ( DC-3) and the Time Of Flight
Scintillator
( SC) system (see Fig. 1).
It covers the region of polar
angles 
in the forward
direction.
Each of the 6 sectors of CLAS consists of 18 segments.
A simplified scheme of ray-tracing inside
the Cerenkov segments
is presented in Fig. 2
The segments are symmetric with respect to the middle plane, and consist of two elliptical and two hyperbolic mirrors, and Winston cones ( WC), and two PhotoMultiplier tubes ( PMT).
A fast particle with velocity
where n is the gas refraction index, produces Cerenkov light in a narrow cone in forward direction. This light is focused by the elliptical and hyperbolic mirrors and the WC onto the PMT cathode window.
The goal of the CC package, as part of the GEANT-based description of CLAS, is to simulate the response of the Cerenkov detector.