Apr 6, 2017 Calorimeter
From GlueXWiki
Contents
Video Conferencing Information
Meeting Time: 11:00 a.m.
- To join via a Web Browser, go to the page [1] https://bluejeans.com/907185247.
- To join via Polycom room system go to the IP Address: 199.48.152.152 (bjn.vc) and enter the meeting ID: 907185247.
- To join via phone, use one of the following numbers and the Conference ID: 907185247.
- US or Canada: +1 408 740 7256 or
- US or Canada: +1 888 240 2560
- Upon connection all microphones are automatically muted. To unmute your mike on a Polycom or equivalent unit, enter *4. Unmuting on a computer is trivial as there is a microphone button than can be clicked.
- More information on connecting to bluejeans is available.
Participant Direct Lines
- JLab Phone in CC L207 is 757-269-7084 (usual room)
- JLab Phone: in CC F326 is 757-269-6460
- Phone in the Regina Video-conference Suite is 306-585-4204
- Athens Phone: in Christina's office is 011-30-210-727-6947
Action Items
-
Determine number of saturation/underflows that exist in the two LED bias monitoring settings (Ahmed)Working on periods with only one bias -
Understand the nature of the peak in the (Fcal propagated to target -RF) satellite peak of -2 ns (Adesh)Under investigation. Will use LED data to investigate this and 4 ns shift in fADCs - Disable red LED string in dark room to avoid leaving it on in the future. (Adesh)
-
Quantify the LED pulser sector jumps within one run (Ahmed)Investigation of outliers continues under study.
References
- FCAL HDFCAL log book
- BCAL HDBCAL log book
Tentative Agenda
- Announcements
- Collaboration Meeting May 15-17, 2017
- Action Items
- Activities during the down
- FCAL update
- BCAL update
- Calibrations
- Reconstruction and Simulation
- NIM articles
- Any other business
Minutes
Attendees: Elton, Adesh, Mark (JLab); Sean (NW); Will (CMU); Andrei, Zisis, Ahmed (UofR); Matt (IU); Christina (Athens)
- Announcements
- Collaboration Meeting May 15-17, 2017
- Action Items
- Most items are under study.
- Activities during the down
- Adesh will talk to Fernando/Chris/Nick about disabling red light option in Fcal dark room.
- FCAL update (Adesh)
- Pi0 gain calibrations have been completed for spring 2017
- CCDB has been updated with new calibration constants
- See a rate dependence to the gain calibration. The periods with low intensity show a pi0 peak at 130 MeV after calibration. Pedestals for these periods are fine. Will investigate with LED data.
- Non-linearity correction has been determined. A single curve function will do. (2016 data seemed to require a linear and curve function.
- Timing
- Satellite peaks at 2 ns are not understood.
- One also sees a time slewing, but the source is unclear. The slewing seems more pronounced when one uses pi0 calibration showers.
- 4ns shifts in fADC channels have not been established. The plan is to look at LED data. Ahmed: any time shifts are at the percent level, but Sean noted that other systems see a wider issue.
- Pi0 gain calibrations have been completed for spring 2017
- BCAL update
- Calibrations
- ADC timing: 4 ns run-to-run shifts in certain BCAL channels (Mark)
- Extracted 4 ns shifts channel by channel as a function of run number. This is done by comparing ADC and TDC data.
- Some channels actually see shifts in both directions (i.e. 3 peaks)
- The 4 ns shifts affect the extraction of higher level constants, i.e. gain ratio and attenuation lengths.
- Expects to commit code and tables for the 4 ns shifts later today
- The present method does not work for layer 4 because there are no TDCs on layer 4. Need to develop another procedure for layer 4.
- BCAL gain drifts: Spring 2017 all runs (Mark)
- Plot ln(ADC_up/ADC_down) vs z to extract gain ratio and attenuation lengths.
- These constants have been determined before the 4 ns shifts, but they are affected by the timing shits, so need to be redone after the 4 ns shifts are corrected.
- Gain ratios are seen to vary as a function of run number for some channels.
- Stability of LED signal vs rum number for problematic channels (Ahmed)
- Ahmed has confirmed that channels identified by Mark have poor stability. The stability is a problem for one side, usually the channel with lowest gain
- It has not been decided how to handle these problematic channels. So far about a dozen have been identified.
- Will also finds that the problematic channels are showing poor calibrations, which is not surprising since their gain is time dependent.
- Zisis: Could this be due to the summing circuit? Mark: No clear systematics has been found yet.
- Andrei: Do the channels show the same behavior at lower bias? Elton: we have been running at Vover=1.4 for over a year and have not investigated long term stability at other settings.
- BCAL gain calib (Will M.)
- Started with flat gains and gain ratios from Mark
- Found no improvement after 5 iterations. It is unclear why last years matrix inversion procedure is not converging.
- Tried removing the B mass constraint. No improvement
- Looked at pi0 mass vs channel number for channels contribution more than 50% of energy to a given shower.
- Removing the B mass constraint and using tight eigenvalue selections, gain changes seemed to follow pi0 mass, so improvements made sense and helped.
- Further improvements were clearly possible, so use sort(mean/pi0 mean) to move gains toward improved pi0 mass for showers with >50% of shower energy. This improved resolution considerably. However only seems to work for layers 1 and 2, which has substantial statistics.
- Went back to matrix inversion method for other layers, but little improvement is seen.
- Zisis: Could one use Andrei's cosmic-ray calibrations?
- Mark: What fraction of statistics is included in this calibration? Will: About 5%. Mark: Perhaps one can skim events with energies in layers 3 and 4. Will: May still need to relax the fraction of energy required in a given layer to probe layers 3 and 4.
- The final result shows lower pi0 widths than 2016 and the gain constants are more tightly grouped than before. It was always surprising that the 2016 gains had such a large variation.
- Mark: Could the 2016 data benefit from the current set of constants? will: Perhaps and will check that
- Non linear corrections (Will)
- Finally, first look at non-linear corrections in 2017. Shape of correction different than last year.
- Need to consider best fit function. Variations from pi0 mass after corrections are less than 0.5%
- Sean: It would be interesting to study the systematics after all corrections.
- pi0 data extends only up to about 3 GeV. Perhaps can use J/Psi and/or high energy electrons to extend / test corrections to higher energies.
- Discussion: Will should go ahead and put the current version of the gain constants in ccdb so that calibration launches can benefit from them.
- ADC timing: 4 ns run-to-run shifts in certain BCAL channels (Mark)
- Reconstruction and Simulation
- NIM articles
- Bcal: Zisis has updates to the paper. Now needs input from Mark, Will and others for sections that they are working on.
- Any other business