sPHENIX HCal discussion

[Stefan Bathe <stefan.bathe AT baruch.cuny.edu>]

Dear All,

Here the minutes from today’s meeting.  If you read nothing else, read the discussion of the two sector groups as for average sector gain, potentially related to a problem with voltage drop for some sectors as summarized in the discussion of Shuhang’s presentation.

Regards,

Stefan

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attendance:  Bill, Stefan, Dan Lis, Ejiro, Evan, Hanpu, John Lajoie, Megan, Murad, Saif, Shuhang, Veronica, Zhiyan, Dan Richford, Justin

Dan Lis—cuts on data quality (see slides)

————————————————————————————

- will start working on simulation today

- slide 2

  - plots of waveform:  ADC minus pedestal vs time sample

  - 20-30 means 200 - 300

  -  200 - 210 means 2000 - 2100

- multi-peak structure in sample distribution leads to overflow peak in ADC distribution

  - comment:  cut on multi-peak structure does not seem to work perfectly since overflow peak persists

  - suggestion:  plot w/o pedestal subtraction

    - had been done by now:  then overflow peak is in single bin, confirming that smearing out of overflow peak comes from pedestal subtraction

- several cuts were developed to clean up ADC distribution

- ACTION ITEM (those involved):  absorb these cuts (if not already) into Veronica’s/Shuhang’s/Hanpu’s analysis

Ejiro—Géant simulation (see slides)

———————————————————————

- still working on sampling of muon distributions

- reminder (Stefan):  goal is to sample position: z, x; and direction:  phi, cos^(theta) (all flat) of muon gun at y = just above sector in question for z, x intervals large enough to also allow non-perpendicular incidence on sector and then look at tower-by-tower energy distributions (distinguishing upper vs lower and different tile shapes (i.e. eta); this should mimic what’s happening in real life in 912.

Saif—Géant simulation (see slides)

———————————————————————

- starting to work on simulation

Hanpu—fitting analysis (see slides)

————————————————————————

- distribution of tower-by-tower PR is consistent with GSU’s results (shift for some tile shapes caused by different quality fibers used by Uniplast)

- Megan:  can’t compare across shapes b/c shape-specific reference tiles picked independently

- correcting for PR should reduce dispersion within given shape

- Stefan:  renormalize PR so that average PR = unity; then correcting for PR should also reduce dispersion across shapes

- temperature dependence not obvious

- Stefan:  compare runs from different seasons to allow great heat sink (sector) to equilibrate

- average gain per sector:  two sector groups (see also Shuhang’s slides)

Shuhang—fitting analysis (see slides)

————————————————————————

- average gain per sector:  two sector groups (see also Shuhang’s slides)

  - Veronica:  some runs have wrong sector number; ACTION ITEM (Veronica):  point these out to Dan via Slack

  - one sector (#6) has one run in either group

- about a dozen sectors have gain 1/3 lower than other sectors

- Dan Richford confirmed in real time for an example of two sectors, #1 and #2, where #1 has mean ADC = 1100 and #2 has mean ADC = 750, and both have exclusively “production” SiPMs (Vop = 67.48 V) that voltage is set correctly for calibration runs

- Stefan suggested that observation could be explained by actual voltage being lower than set voltage (akin to (but less extreme then) faulty SiPMs or preamps bringing down voltage entirely for whole sector, half sector, or individual tower, as observed in assembly and testing)

- Dan Richford confirmed that actual voltage was not recorded in data stream (after initial checks had not found a discrepancy to set voltage)

- Dan Richford started a run in real time and found that voltage read by interface board was in fact about 1 V less than set voltage

- Dan Richford, John Haggerty, and Stefan will meet in 912 tomorrow to investigate

- after meeting:  John L, Stefan:  make same plot for half sectors (since electronics is per half sector (N/S)

  - Shuhang made plot:  problem is not on the half sector level, but on the sector level

Veronica—fitting analysis (Landau)

———————————————————————

- also sees MPV, width correlation (like Hanpu/Shuhang)

- analyzed 5 h run for sector 6:  two peaks in tower by tower mean distribution

  - Shuhang does not see two peaks

  - ACTION ITEM (Veronica):  post tower-by-tower fits

- Veronica also sees the two sector groups just like Hanpu and Shuhang

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Stefan Bathe

Professor of Physics
Baruch College, CUNY

Baruch:                                     BNL:
17 Lexington Ave                      Bldg. 510
office 940                                  office 2-229
phone 646-660-6272                phone 631-344-8490
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On Jun 14, 2021, at 11:59 PM, Stefan Bathe <stefan.bathe AT baruch.cuny.edu> wrote:

Dear All,

We’ll have another HCal muon calibration meeting tomorrow, Tuesday, June 14, at 11:00am:

https://indico.bnl.gov/event/12188/

(Zoom info below)

We expect updates on Geant simulations and peak fitting.  Meeting goals are to:

- have a realistic simulation of the distribution of muons entering the detector in 912 so we can actually use that for calibration

- identify any anomalies in the calibration data taken, correcting for knows effects (wrong voltage settings, temperature (also using LED data), PR)

  - and then get to the bottom of them to make sure there are no hardware problems

- identify any problems with and fully understand raw ADC data

Regards,

Stefan

ZOOM INFO:

Stefan Bathe is inviting you to a scheduled Zoom meeting.

Topic: HCal Calibration
Time: This is a recurring meeting Meet anytime

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---------------------------------------------------------------------------------
Stefan Bathe

Professor of Physics
Baruch College, CUNY

Baruch:                                     BNL:
17 Lexington Ave                      Bldg. 510
office 940                                  office 2-229
phone 646-660-6272                phone 631-344-8490
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