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    User name Jin

    Log entry time 19:00:18 on January 15, 2009

    Entry number 256252

    This entry is a followup to: 256210

    keyword=Beam Energy Logger to run database is disabled

    There are false alarm of kinematics shifting since last night, for run 5168, 5175 and 5184. The reason is that, the beam energy logger (part of run start script), which copy EPICS beam energy reading to run database, happen to log a number of some 4.1GeV, 2GeV below real energy.

    This number is used by online analysis software to calculate preliminary kinematics, which is therefore shifted for those runs. However, during offline analysis, we will probably use more precise way to extract beam energy. So, this problem will not affect our final data quality.

    As a solution, Vince and I disabled the Beam Energy Logger. And starting from run 5191, online analysis will use a fixed beam energy number of 5.89202 GeV (EPICS Reading during run 5190).

    Therefore, we should be free from this problem from now on. And we need to manually change beam energy setting in db_run.dat, in the case that we would have 1 path optics run during February.



    A copy of this log entry has been emailed to: jiang