BCAL Reconstruction Meeting 2014-10-16
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Meeting Time: 12:00 p.m. EDT
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Participant Direct Lines
- JLab Phone: in CC F326 is 757-269-6460 (usual room)
- JLab Phone in CC L207 is 757-269-7084
- Phone in the Regina Video-conference Suite is 306-585-4204
- Timing: extracted from F1TDC and compared to fADC; check need for time-walk (Tegan)
- Ask Richard Jones about Truth info from BCAL hadronic showers (Zisis, Will L., Justin)
- Shower curvature tables: compare KLOE to IU codes: check gap in cluster handling between codes (Tegan, Andrei)
- z-coordinate determination from up/down amplitude ratio (Tegan, Andrei)
- Cleanup: (Tegan, Will L.)
- Set variable “failures” to a number other than zero (e.g. -9999 or similar)
- Comb code for constants to be pulled out into a database
- Measure data pedestals using LV=0 setting (Mark)
- Sampling fraction tables (Tegan)
- Action Items
- fADC time-walk code File:FlashTiming.pdf (Tegan)
- Any other business
Attendees: Mark D., Elton, Will M. (JLab), Will L. (CMU), Tegan, Andrei, Noemi, Zisis
- Announcements: none.
- Action Items:
- Timing: see presentation in the Update Section below.
- Truth info: Tegan will look at DBCALIncidentParticles factory and possible compare with DBCALTruthShowers. Will L., Justin and Zisis have spoken with Richard Jones about the latter, as a few things are not clear in what it gives.
- Shower curvature: this is the highest priority after the Tegan's timing code has been checked into svn. The plan is to train the BDT with the shower depositions and compare it to cluster reconstruction of the existing code. Additional variables will be sought, such as energy deposition ratios among layers. If there are delays in implementing the curvature in the BDT we can consider a more standard implementation using lookup tables (or parametrization) to correct for the showers' 'bending'.
- z-coordinate, amplitude ratio, TDC vs timing from fADC will be looked at next.
- Tegan will clean up the code with Will's help.
- LV=0 pedestal data: Mark will take that when time permits, and we will look at the effect that the preamp boards have on the output.
- Sampling fraction: we decided that this has low priority and will be handled after the previous items have been completed.
- The objective of the timing work is to address the incorrect (vs real data) handling of the timeing using threshold crossing in the fADCs. [Of course, the TDCs will still need threshold-crossing, time-walk corrections.] Tegan presented simulation data (photon gun, 0.5-1.5 GeV at 50 degrees) for a sample cell (Module 1, Layer 3, Sector 3). The x-axis is the extracted time from the Hit ADC (unified hit routine) - hitPulseIntegral info. Time is in units of ns. Page 1 has the 'old' method, showing the effect in going from raw (simulated) data in the top panel, to after the correction in the bottom. Page 2 shows the new fADC algorithm processing. Page 3 shows the 2D time vs ADC information (after the algorithm but without any time-walk correction) and the red line shows the time-walk curve. The conclusion is that no time-walk correction is needed. This is expected provided that the pulse shapes do not change drastically during shower energy depositions in cells. This is also what is expected using CFD-TDCs, where only when one is after sub 100-ps resolutions, are second order t-w corrections attempted. Mark also has not seen evidence for t-w correction from the data. The x-scale on page 3 is in GeV, so the code works well all they way down to a few tens of MeV.
- Action: We decided to remove the old/wrong threshold-crossing code and check-in the new code without additional (flat) time-walk correction as a place holder.
- Action: Tegan will use the COSY option in ROOT (or log scale on axis) to zoom in and see if there truly is no t vs ADC bending. Also, look at data for residual t-w effects.
- A.O.B. Mark reported that the collection of all ROOT files with cosmic data amounts to 1 million events. The files have sometimes been split in two, depending on the fADC mode (e.g., firmware mode 7 - integral only). Also, the combined DAQ (44 crates) was tested this morning using high rate MC data (450 MB/sec and 30kHz random triggers) and worked for 1.5 hours without an issue. The standalone BCAL DAQ ran at low rate (cosmics) for three days without issue. DAQ is looking good.