RF Calibration
Overview
TI-Time Uniformity
- As detailed in GlueX Doc 2686, blah blah
TI-TIME UNIFORMITY CHECK: 1) Confirm that the copies of the global system clock present on each ROC are consistent with each other: "ROCTIs" directory
TDC->TIME CHECK: 1) Confirm that the tdc->time conversion is accurate for each system: "DeltaT_RF_FirstTime" directory - TOF & TAGH RF signals read out 1/128 times: expect first delta-t peak at 128*1000/499 ns - PSC & FDC RF signals read out 1/64 times: expect first delta-t peak at 64*1000/499 ns
RF TIME CALIBRATION: 1) Confirm that the RF signal is arriving at approximately 499 MHz: "RF_SignalPeriod" directory 2) Study the resolution of each source of the RF signal: "DeltaT_RF_Itself" directory. Check in these constants. 3) Do a rough alignment of each RF system with respect to the TOF signal: "AbsoluteDeltaT_RF_OtherRFs" directory & FitMacro_RF_CoarseOffsets.C Macro. Check in these constants. - This is important in case the RF signal period is not exactly 499 MHz. If it's slightly wrong, add the time offsets are huge, then propagating across several micro-s will result in a many-ps error in the time. 4) Study the resolution when taking the difference between RF times at different sources: "DeltaT_RF_OtherRFs" directory. - If these resolutions are much larger than the individual system uncertainties, then do not average the system times together. - This is the default behavior of the DRFTime factory (for the signals in the data stream, only uses the system with the best time resolution) 5) Do a detailed alignment of each RF system with respect to the TOF signal: "AverageDeltaT_RF_OtherRFs" directory. Update these constants (and the uncertainties).
CONFIRM ALIGNMENT TO TAGGER HODOSCOPE: 1) Once the tagger hodoscope has been aligned to the RF, confirm the alignment: "DeltaT_RF_TAGH" directory.
- If it is out-of-line, realign the tagger to the RF (outside the scope of this plugin)