  Visible Cherenkov radiation can offers a method of the measurement of the
velocity of a charged particles. The angular width of the radiation is
important since it determines the resolution of the velocity measurement. In
this article, the angular width of Cherenkov radiation with inclusion of
multiple scattering is calculated through the path-integral method, and and the
analytical expressions are presented. The condition that multiple scattering
process dominates the angular distribution is obtained.
