Hi Andrzej,
About the positive drift of the pedestals. During the testbeam we had
very (!) low occupancy and the using a 3 sigma cut also reduces the
signal, so I am a little worried if you already see a shift. I think there
is a way of finding out if it is connected to signals coming from hits or
if it is an artifact of the processing: In the low energy part we also
used the paddle counter (overlapping all Si active area) and the finger
counter (1x1 cm2) in coincidence. So only the area behind the finger
counter should have hits, the rest should have no signals coming from
particle. Select some chips in this "no-trigger" area may answer the
question for the positve going pedestals maybe. Run 63 (285meV/c pion
neg.) is one of these runs (in the log book you maybe find aditional runs)
Cheers
Heinz