Four-layer aerogel Cherenkov counter

A 4-layer design of aerogel threshold counters using two refractive indices was suggested for the particle identification in the forward region of the BaBar detector. Three prototypes filled with the high quality aerogel produced in Novosibirsk were tested at T10 beam at CERN. Monte Carlo code was developed for the simulation of the light collection in aerogel counters. Monte Carlo results based on measured PTFE reflection coefficient and aerogel absorption and scattering lengths are in agreement with experiment