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User name Markowitz

Log entry time 07:10:56 on January 26, 2008

Entry number 149779

keyword=Beam: Owl shift summary

Started shift with beam in hall, looking at rates (C1 and C2, DAQ, and ion chamber rates in particular but also singles rates).

With calorimeter thresholds of 700 mV, did not understand spectra of BCAL energy going down to 250 MeV. Tried adjusting thresholds, playing with beam current to get rid of low energy events. Not possible. Eventually, phone call with Pentchev clears it up -- the spectra was incremented multiple times for each event, meaning that although our discriminator thresholds demanded a trigger of energy> 1.4GeV, other low energy clusters were also reconstructed for the same event.

Looked at ion chamber rates vs. luminosity (ion chamber rates all < 20% of allowed maximum). Pedestals did increase by 250% at highest luminosity.

At end of shift, DAQ hung (ROC12 mostly, but a few ROC11 hangs as well). Called MCC for access to turn on BigBite magnet at 7 am.

See entry by David Hamilton for details about rates and luminosity.