A Set of Minimum Checks
Before A_y Physics Production at One Pass
(Xiaodong Jiang, 22:00, 4/26/2009.)
Here's a set of minimum checks MUST satisfied before any meaningful physics data can be taken for A_y on Monday.
1. Two-arm DAQ synchronization checks.
i. Two arm start, stop at the same time, while Happex DAQ is running. ii. Redundency trigger scalers between two-arm should agree to 10^-4 level. iii. Beam charge scalers, for the same channel (i.e. u3, u10, etc. in each arm) should agree to 10^-4. iv. Fast (100 kHz) and slow (1 kHz) clocks agree to 10^-4 level. v. Gated scalers make sense. vi. Sync error in each arm occour less than 10^-4 (?)
2.Make sure that: !!! Happex DAQ is already running when we start taking each arm DAQ data.!!!
3.Lumi signals make sense, HV settings already adjusted so that Lumi signals are not saturated.
4.Lumi data inserted into each arm-DAQ are consistent. Agree to 10^-4 level. Fast (100 kHz) and slow (1 kHz) clock also in Lumi data stream (?) agree to 10^-4.
5.For Ay production, only take T1 (on right arm) and T3 (on left arm). Pre-sacel away all other "physical triggers", especially, coincidence triggers should not be allowed. Any DAQ bias at 10^-4 level, between target spin-up vs. down, could likely kill the experiment !
6.!!! Attention !!! For A_y physics data taking, BigBite HV should always be be turned OFF. Including wire chamber and scintillator HVs. If special runs are formally requested through spokespersons, one or two dedicated run can be taken daily, while running carbon foil target or reference cell.
7. !!! Watch Out !!! For DAQ bias at 10^-4 level, target up vs. down.
For possible DAQ read-out bias on right arm DAQ, due to neutron detector read-out. Pay attention to:
i. Readout word length differences between target spin-up vs
spin-down directions.
ii. DAQ deadtime differences locally, between target spin-up vs
spin-down directions.
A copy of this log entry has been emailed to: jiang,brads,vasulk,zhaobo,yawei,qiangy,peter,jinhuang,rom