sPHENIX HCal discussion

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

Dear All,

Here are the minutes from last week’s meeting:

Regards,
Stefan
—
attendance:  Ejiro, Achim, Dan Lis, Dan Richford, Evan, Hanpu, John Lajoie, 
Megan, Saif, Shuhang, Veronica, Bill, Zhiyan, Stefan

open issues—Stefan (see slides)
- tower/sector QA:  do we understand MIP/PR?
- hardware/data taking:  
   - increase LED peak position? Take runs at different settings?
   - investigate PIN diode
   - investigate HG/LG distribution
- simulation:
   - implement MEPHI light maps
   - compare to test beam
   - convert EM to hadronic scale
- hardware issues:  preamp failures

simulation—Ejiro (see slides)
- sampling fraction (sf) from test beam, calculated from geometry, private 
communication John Haggerty
- shape difference between Ejiro’s and Dan’s earlier simulation:  Dan used 
calibrated energy, Ejiro deposited energy ACTION ITEM (Ejiro, Dan):  compare 
simulation peaks for same tile shape directly
- ACTION ITEM (Ejiro, Dan):  
   - use realistic muon energy distribution (not just 4 GeV) to hopefully 
describe data better
      - Bill:  energy distribution depends on angle
   - plot w/ threshold in lower sector (done in the meantime (Dan Lis):  most 
of the events that are included in the 100-300 ADC count range look like real 
muons with lower energy deposition, not electronics issues)

simulation—Dan Lis (see slides)
- slide 3:  this is calibrated energy, so includes noise
- slide 5:  simulated MIP is narrower than data, which seems to make sense, 
but is opposite of what Ejiro is seeing (see earlier action item)
  - but different run, tile shape
- slide 7: non linear correlation between calibration coefficient and PR
   - Dan expressed Jamie’s concern about using tiles with PR > 1.2
      - we think there’s nothing wrong with those tiles
   - could be explained by fact that PR reference is independently determined 
for each tile shape
- slide 9:  trigger simulation:  using 100 ADC = 2 MeV threshold

cosmics data analysis—Hanpu (see slides)
- differences between pre-production and production sectors:  all 
pre-production sectors have mean MPV less than any production sector
  - could be due to differences in tile production batches
- two ADC channels w/o background
  - tested swapping of meritec cables; background-free channels remain the 
same; conclusion:  this is an artifact of the digitizers
- comparison of ADC distributions btw. those two and other channels for 
various cuts:  some differences found, but inconclusive (at least to me)
- PR-normalized MIP distributions:
   - for some tile shapes PR-normalized MIP distribution widens and/or 
secondary peaks appear compared to unnormalized distributions (but not for 
some other shapes)
     - conclusion:  something must be wrong with PR determination
       - maybe scaled PR was scaled by inverse scale factor?  (ACTION ITEM 
(Hanpu/Shuhang);  plot with inverse scale factor)
       - ACTION ITEM (GSU (Anthony, Saif, Megan)):  investigate
 - temperature dependence of ca. -6 %/C observed; roughly consistent with 
John H.’s measurement of 1.7 %/C at 0 C (but about 3.2 % at 27 C!)



-- 
---------------------------------------------------------------------------------
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
----------------------------------------------------------------------------------

> On Jul 12, 2021, at 10:01 PM, Stefan Bathe <stefan.bathe AT baruch.cuny.edu> 
> wrote:
> 
> Dear All,
> 
> We’ll have another HCal muon calibration meeting tomorrow, Tuesday, July 
> 13, at 11:00am:
> 
> https://indico.bnl.gov/event/12461/
> 
> (Zoom info below)
> 
> If you would like to give an update (and aren’t already on the agenda), 
> please let me know and I’ll put you on.
> 
> We have several action items to follow up on from the past couple meetings. 
>  One item that I think is both important and urgent is the distribution of 
> tower-by-tower MIP positions, normalized by PR averaged over the tiles in a 
> tower, once separately for the 12 different tile shapes, and once more 
> separately by sector.  This will tell us two things:
> 1) outlier towers that potentially have issues so we can investigate
> 2) whether the lower MIP in the preproduction sectors stems from 
> differences in tile badges.
> (Sorry if we have this already and I missed it somehow.) 
> 
> 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
> 
> Join Zoom Meeting
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> 
> Meeting ID: 817 4933 0526
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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
> ----------------------------------------------------------------------------------
>