sPHENIX HCal discussion

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

Dear All,

Here the minutes from last week’s meeting:

Shuhang:  peak finder and gamma distribution fitting (see slides)
—————————————————————--------
- look at 16 subsamples
  - fluctuations larger than statistical error bars
  - suggestions
    - look at signal to noise (Edward)
    - look at width/MPV (Stefan)
- sector QA:  mean, width
  - looks like two different distributions
  - suggestions
    - break down into “production" and "non-production” sectors (“production” 
referring to sectors with SiPMs with Vop=67.48 V where V was accidentally set 
to 67.84 V)
    - look at distribution of normalized width
    - look at same quantity in simulations (Ejiro, Dan Lis)
  - plan to correct for PR 

Hanpu:  peak finder and gamma distribution fitting (see slides)
—————————————————————--------
- attempted fit for all available “regular” data
  - 100 % success rate (defined as chi^2/ndf < 2 and Delta MPV (peak 
finder-fitting) < 100)
  - sector 15 shows low peak
    - was later found by Dan Richford and Stefan to be mistake in voltage 
setting
    - several sectors show similar problem:  14, 15, 21, 25
    - these are sectors with a variety of SiPMs with different Vops, where 
tower-by-tower voltage has to be adjusted with offset (via DAC value)
    - DAC offset was applied to LED and TP, but mistakenly not to cosmics data
    - new data with corrected offset will be taken during burn-in
- Edward suspects overflow peak comes from problem with pedestal subtraction 
in raw ADC data and suggests to talk to John H
  - Stefan reached out to John H (Cc Edward, Dan R), but no response yet
  - Edward asks about offline cuts to data
  - Dan R and Shuhang confirm that two-tower vertical condition and neighbor 
veto cut are tower-by-tower cuts (as opposed to event-by-event)
- error (MPV) vs MPV shows two groups of towers
  - not clear why

Veronica:  fitting with Landau + Gaussian background (please post slides or 
send to Stefan)
———————————————————————————————————
- switched from Landau with convoluted Gaussian to just Landau (plus Gaussian 
background) a few weeks ago
- question for gain variation as function of voltage and temperature
  - Edward:  1 %  per degree C
  - John H (earlier private email):  2.5 %/degree C, 2.5 % per 50 mV
- suggestion (Edward):  take temperature dependence into account when 
comparing different runs
- sector 12:  large width distribution
  - suggestion:  compare to Gamma distribution fit (Shuhang, Hanpu)

Dan Lis—Geant simulation (see slides)
——————————————————
- still working on cosmic spray class
- still working on implementation of half-absorber plate
- showed various low-level data correlations between peak, integral, and 
pedestal
- various anomalies—unclear if they constitute problems
- suggestions (Edward):  
  - reject entire event if any peculiarities in event
  - anomalies caused by double hits or catastrophic energy loss of muon:  
calculate rate

Regards,
Stefan
-- 
---------------------------------------------------------------------------------
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 Jun 7, 2021, at 9:47 PM, Stefan Bathe via sPHENIX-HCal-l 
> <sphenix-hcal-l AT lists.bnl.gov> wrote:
> 
> Dear All,
> 
> As usual, we’ll check in with each other at the end of the regular HCal 
> meeting to talk about any progress on the calibration effort.  If you let 
> me know that you are presenting something, I’ll make an agenda entry so you 
> can post your slides.  It’s probably easiest if we just stay on the HCal 
> Zoom line.
> 
> Regards,
> Stefan
> 
> -- 
> ---------------------------------------------------------------------------------
> 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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