Lead glass cosmic ray tests
A lead glass block is used with a FEU-84-3 pmt coupled on each end of the block. The same cosmic ray trigger as for the TOF is used to record cosmic rays passing transverse through the lead glass block. The effective light velocity and attenuation length has been extracted. The attenuation length extracted needs to be modified by a factor of about 1.3 in order to take into account that the Cherenkov light is emitted at a certain angle and does not travel on a direct path from the particle location to the PMT. This results in an attenuation length that is close to the 90 cm observed in radphi.