Re: [BLAST_SHIFTS] missing L0-L7

From: Karen Dow (kdow@mit.edu)
Date: Fri Nov 08 2002 - 11:25:05 EST


        LTOF0-7 look ok for run 2655 (started at 22:50 on the 7th). Run 2656
is marked as garbage. LTOF0-7 are bad in run 2657 (started just before
midnight).

        Adrian, Jason and I just looked at the ADCs and TDCs for LTOF0-7 for
run 2657 with no cuts. Indeed, the ADCs are mostly pedestal and the
TDCs are mostly 0 or overflow. So the missing LTOF0-7 is NOT a bad
cable into the TDC (where you'd then lose the good ADC due to the TDC
cut). Since 8-15 are there, it really couldn't have been a bad cable
anyhow; the cables are in groups of 16.

        Adrian and Jason are taking cosmics, and L0-7 look fine. So there is
nothing fundamentally wrong with those detectors.

        The most likely thing is the trigger required the NC not fire for L0-7;
if there is noise in the NC bit, or if the NC cable is reversed, then
you'd rarely see anything from L0-7. I traced the NC cable to the MLU
this morning, and I thought it looked ok sign-wise. But the best thing
is to put the NC in X for L0-7 and check with beam.

                                Karen



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