Development of Silica Aerogel Cerenkov Detectors

Recently silica aerogel has been employed as a Cerenkov radiator. This solid material can be produced with a refractive index of 1.01-1.10, thus complementing the refractive indices easily obtained with gases and liquids. It is very well suited for identification of particles having momenta of about one or a few GeV/c. Examples of efficient detectors with active surfaces of about 0.1 m2 using light collection system constructed from mirrors and diffusing walls are given. With a refractive index of 1.03 and an aerogel thickness of 9 cm, signals of about 6 photoelectrons have been obtained for ß = 1 particles.