Behavior of hydrophobic aerogel used as a Cherenkov medium

We report on the optical properties of hydrophobic aerogel blocks measured in the UV and visible part of the spectrum. The compatibility of the material with various polymers and solvents was investigated in order to select the most suitable materials for the construction of Cerenkov counters. The long term stability, mass loss, and outgassing properties along with the effect of intense UV irradiation are presented.