sPHENIX EMCal discussion

["Hodges, Anthony" <ahodges4 AT illinois.edu>]

Hi everyone, 

Here are the minutes of today's meeting. If there's anything missing or mischaracterized, please let me know.

Best, 

-Anthony

Virginia Bailey, Year 1 Jet Calibrations 

Also presented during JS-TG meeting on 09/07/2022 

• Calibration avenues:  

• ATLAS-style (primary focus) 

• Bottom-up, jets reconstructed from fully calibrated calorimeters.  

• Number of cross-checks to evaluate
  

• List of uncertainties presented. Some uncertainties apply to both categories (e.g. statistical uncertainties, generator choice) 

• Missing: MC sample with alternative generator and empty trigger event to qantify noise.  

• Calibration task list, still plenty of tasks to be done! 

Q&A

• Calibration efforts are based on calo-jets.
• ATLAS R-track method used to correct for discrepancies between MC and data. 
• Uncertainties on MC tracking must also be understood
• R-track method is similar to but not the same as isolated track calibration
• Uncertainty list presented is not yet complete, but "Amout of material in simulations" is meant to account for MC/data discrepancies
• 
  
• JES investigation will be two dimensional (eta, phi), don't expect huge impact of tile maps on JES, more concerned about chimney sectors

• Discussion about how low-level jet calibration efforts will go. Summary is that Jet-level calibrations depend on pre-calibrated calorimeters. Determining what ADC values correspond to what reconstructed energies should be done beforehand. Effort is already underway via cosmic MIP studies. 

• 
  

Shuhang on sampling fraction: 

• Noticed that Birk's constant for new HCal active material set to zero. 
  

• Even if fixed, won't account for the factor of two change to the sampling fraction. 
  

• Electron density of new material also off by 30%
  

• Major issue seems to be the mismatch of material constants in the simulation (e.g. polystyrene setting in our GEANT matches that of ATLAS and CMS, but we have a different electron density)

• Plan to investigate materials from ground up and determine right electron density by calculation
  

 

Shyam on optimizing minimum energy cuts for pi0 reconstruction

      

• Trying to optimize cuts for maximum precision and minimize number

• of events needed.  

• Looking at minimum photon energy cut of 0.6GeV.  

• Review of estimator functions

                  Discussion on table on slide 4

• Different columns are different esimators functions for the statistical error on the peak amplitude and mean. 

• Relative difference refers to the difference between the error produced by the estimator function and the actual fit, which is a gaussian plus a second orde polynomial

• Different row entries are eta bins, and numbers in parentheses are photon energy cuts. 

• Recommendation to convert table to plot form for easier understanding, especially if nformation from table will be put into analysis note. 

• Minimum in estimator function found at slightly lower minimum photon p_T, but statistical gain is small. Similar results in different eta bins as well

                  Discussion on fitting on slides 8-10

• Possibility of using finer/variable binning near the peak region for better precision
  

                  Signal and background yields on slide 11

• Asymmetry across eta due to decalibration left in code. 

Justin on including energy resolution in estimator functions

• Adding a term that accounts for the energy resolution to the statistical   error estimator function
• New function strengthens conclusion of minimum photon cut from Shyam's  presentation

​Anthony and Tim's presentations moved to next week (09/02/22)

Anthony Hodges, PhD (he/him/his)

Postdoctoral Researcher

High Energy Experimental Nuclear Physics

University of Illinois Urbana-Champaign

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From: sPHENIX-EMCal-l <sphenix-emcal-l-bounces AT lists.bnl.gov> on behalf of Frantz, Justin <frantz AT ohio.edu>
Sent: Tuesday, September 13, 2022 1:11 AM
To: sphenix-emcal-l AT lists.bnl.gov <sphenix-emcal-l AT lists.bnl.gov>; sphenix-calibration-l AT lists.bnl.gov <sphenix-calibration-l AT lists.bnl.gov>; sphenix-hcal-l AT lists.bnl.gov <sphenix-hcal-l AT lists.bnl.gov>
Subject: [Sphenix-emcal-l] Calo Calib Mtg Tomorrow - Tuesday 9/13/22 11am

 

Hi all,

Sorry for the late notice, but we will indeed hold our Calo Calibrations meeting tomorrow (technically today for many since it is after midnight here in EDT)  at 11am.   Please let me know if you would like to make a presentation.   We need to hear an update on the Hcal sampling fraction difference, and Shyam and I will have a short update following up on last weeks presentation.  

-Justin

Meeting info: 

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

indico:

https://indico.bnl.gov/event/17091/

and the zoom info: (same as before--it's a meet anytime)

Topic: sPHENIX Calibrations Meeting

https://bnl.zoomgov.com/j/1617635022?pwd=WmlVME9tcnlTYnlkUC9nU3crNTdRdz09

Meeting ID: 161 763 5022

Passcode: 503420

-Justin

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

Justin Frantz, Ph. D.  he 

RHIC UEC/Diversity Working Group 

Brookhaven National Lab, sPHENIX Experiment 

Associate Professor 

Ohio University Dept. Of Physics and Astronomy    

frantz AT ohio.edu    

646-228-2539