Operational performance of the Hall A mirror aerogel Cherenkov counter

We report the results of an operational test of the efficiency and position sensitivity of a silica-aerogel Cherenkov detector installed in the HRS-E spectrometer in Hall A at Jefferson Lab. The calibration was performed with data from elastic electron scattering from polarized 3He. The response of the photo-multiplier tubes was linearized with a quadratic correction, allowing a unique number of photo-electrons (PEs) to be extracted. The result obtained (∼7.3 PEs) is consistent with the performance of the prototype detector tested earlier under ideal conditions.