These are two figures from a first look at RICH data. I read events from run 2535. The only condition applied is that a pixel should have an ADC value greater then 300.

The geometry of the photon detector is not included at this early time. The figures below plot the ADC value as a box and the coordinates are pixel numbers assuming each pixel is one square centimeter.

In this picture I drew a circle that overlaps most of the pixels with light. One photoelectron per pixel is a good assumption; 20 or 21 p.e in this event. (Not far from the optimistic expectations of the CDR)

The run I picked has many events with rings in the RICH and they all look equally clean. The picture above has two rings. Once again, the circles are added "by hand".

(Updated 6-Nov-2000)