sPHENIX is a new detector at RHIC.

["Huang, Jin" <jhuang AT bnl.gov>]

Minutes also available on agenda pages: https://indico.bnl.gov/conferenceDisplay.py?confId=2683

 

Photon+jet and photon simulations - Joe Osborn

 

Slide 2-4: Investigate photon jet simulations: 

Lower overall photon efficiency in past talk stems from eta acceptance of EMCal

 

Slide 7:

Peter: Suggest match missing photon with conversion probability

Jin: also look into gap between EMCal sectors for the fully projective SPACAL option, which may be improved with new tilting

 

Peter/Chris what is the matching criterial?

Joe: did not required the angular matching yet

 

Slide 9:

Jin: suggest produce dE/E VS E curve as used in the test beam. Note the 1-D projective EMCal has no gap and support structure, which produce much lower constant term than reality

 

Slide 10:

Jin: suggest \Delta phi VS phi plot to show the non-linearity. Trick is to simulate in a small phi (~ few towers) range to increase statistics.

 

Discussion:

 

Jin: As investigating into details of EMCal response, please switch to 2-D projective CEMC, i.e. uncomment line 9 of https://github.com/sPHENIX-Collaboration/macros/blob/master/macros/g4simulations/G4_CEmc_Spacal.C , and comment out line 7

// int Cemc_spacal_configuration = PHG4CylinderGeom_Spacalv1::k2DProjectiveSpacal;

 

Stefan/Jin: the cluster position is energy-linear weighted. Gabor suggested to use a logarithmic weight which need calibration with the \Delta phi VS phi plot

 

 

Cross check with ideal pattern recognition + realistic Kalman fit - Haiwang Yu

 

Pull request for the module, PHG4TruthPatReco, was merged: https://github.com/sPHENIX-Collaboration/coresoftware/pull/250

 

Slide 3-4:

Christof: pion used in fast simulation (LiC)

Haiwang: only pion+ simulation in this talk

Christof: what was the # of TPC layers

Haiwang: used 60 layers.

Tony: note, ladder implementation also complicated by multi-hit/overlapping per layer

Tony/Christof: both resolution are fantastic by considering material budget only. Good to see the agreement.

 

Slide 5: Material change does not introduce much difference in momentum resolution for pion.

Jin: suggest check electron and look for the bremsstrahlung from material thickness changes.

Tony: suggest check Upsilons by running ideal pattern reco + Upsilon generator

 

Slide 6:

Tony: narrow peak in pull distribution is tracked cross two pixels. Wider one is crossing single pixel.

Gaku: Two sources contribute to the weird INTT cluster pull distribution:

1.       INTT cluster pull bias may come from small bug in clustering code.

2.       Strip implementation

Plan to fix it in the week. Has prototype code already.

 

Gaku: also plan to update the next level details in INTT design, for which has reduced the after-overlap per-layer thickness to 0.8%

 

Tony: material thickness may not affect resolution much, although may still affect tails. Next stage should push for pattern recognition.

 

Xin: do you have DCA resolution. Tail is very important for the HF program.

Haiwang: not yet.

Tony: fixing of INTT pull may be very important for DCA measurement.

 

Xin: MAPS pull distribution seems related with naïve digitizer. What was implemented?

Tony: Approximation with smaller pixel size with no-charge sharing.

Xin: LBNL has a fast parametrization for charge sharing.

Christof: trying to get the ALICE MAPS digitizer software parts.

Xin: also require tuning to handle

 

 

Updated fast tracking simulation model - Christof Roland

 

Slide 3-6:

·       TPC 60->40 layers, visible but minor worse in the resolution.

·       Drift parameterization yielded no big effect

 

Slide 7: visible but small change in momentum and DCA resolution for 1% VS 2% material thickness per INTT layer

 

Slide 8: alternative configurations

·       Reducing number of layer improves lower momentum configuration

·       1-layer MAPS has significantly worse resolution/tail

·       Removing MAPS detector dramatically worsen the DCA resolution,

 

Slide 10: No TPC also kills DCA resolution.

Tony: this observation suggest that it is important to control distortion of TPC.

 

 

Tracking software, the next steps - Tony Frawley

 

Christof: propose to fix clustering first (Gaku plan to do so this week), then working on pattern recognition based on GenFit2. Suggest Hough [MAPS + INTT] -> GenFit2 Kalman track propagator to collect TPC hits.

Christof: early APR, may be able to get code/experience for ALICE experts too.

 

Gaku: trying PHENIX silicon tracker pattern reco.

 

Tony: Is there modular progressive patter recognition code we can adopt?

Christof: GenFit2 is modular. Need custom code to get next hit in order to string layers of hits together.

 

 

Conclusion:

A: Good pattern recognition with TPC is the most critical missing step at this moment

B: organizing task force for improving pattern recognition

 

Following people volunteered during the meeting: Christof, Xin Dong, Haiwang, Tony, Gaku, Sourav. Tony to organizing the discussion offline.

 

 

 

 

______________________________

 

Jin HUANG

 

Associate Physicist

Brookhaven National Laboratory

Physics Department, Bldg 510 C

Upton, NY 11973-5000

 

Office: 631-344-5898

Cell:   757-604-9946

______________________________

 

From: Huang, Jin
Sent: Monday, March 6, 2017 1:30 PM
To: 'sphenix-software-l AT lists.bnl.gov' <sphenix-software-l AT lists.bnl.gov>; 'sphenix-l AT lists.bnl.gov' <sphenix-l AT lists.bnl.gov>
Subject: [reminder] sPHENIX simulation and software meeting, Tue Mar 7, 1PM EST @ 2-219

 

Hello everyone,

 

This is a reminder for a regular sPHENIX simulation and software meeting, Tue Mar 7, 1PM EST @ 2-219

 

Currently on agenda is:

•         Photon+jet and photon simulations - Joe Osborn

•         Crosscheck tool for GenFit track fit + ideal pattern recognition   - Haiwang Yu

Further topics will be welcomed too  

 

The agenda page is at https://indico.bnl.gov/conferenceDisplay.py?confId=2683 , for which the common modification password is "1008"

•         For residents at BNL, we will meet at the 2-219 conference room

•         To join the Meeting via phone bridge:  https://bluejeans.com/619960505 

•         To join via Phone:

1) Dial:

        +1.408.740.7256

        +1.888.240.2560(US Toll Free)

        +1.408.317.9253(Alternate number)

        (see all numbers - http://bluejeans.com/numbers)

2) Enter Conference ID: 619960505

 

Cheers,

 

Jin

 

 

______________________________

 

Jin HUANG

 

Associate Physicist

Brookhaven National Laboratory

Physics Department, Bldg 510 C

Upton, NY 11973-5000

 

Office: 631-344-5898

Cell:   757-604-9946

______________________________