sPHENIX HCal discussion

[John Lajoie <lajoie AT iastate.edu>]

Hi Dennis,

    I'd like to have some additional statistics of your ">50 GeV, R=0.4 jet in |eta|<0.6" jet sample to have a look at high-z fragmentation.  Would it be possible for you to generate some additional hepmc files?  A factor of 2-4 would be good, 10 would be great.   I don't need the G4 simulations as I will run them through my analysis code, just the hepmc files.

John

On 9/11/2017 6:07 PM, Perepelitsa, Dennis wrote:

Dear sPHENIX Jet Structure and HCal teams (and in particular John L., Aaron, Songkyo, Raghav),

As we agreed at the HCal meeting last week, we have begun coordinating the production of simulation jobs to investigate the sensitivity of the jet response (especially as a function of fragmentation pattern) to different Inner HCal scenarios.

I have run a set of 10k Pythia QCD hard scattering events with the requirement of a >50 GeV, R=0.4 jet in |eta|<0.6. A full G4 simulation and then standard (pp) jet reconstruction were performed under three scenarios: (1) the default IHCal description, (2) an Al-material IHCal, and (3) an Al-material IHCal which is not read out (this is implemented as tower reco jets not being given the HCALIN_TOWER container as an input to jet reconstruction in G4_Jets.C ).

The input Pythia8 HepMC files are here: /sphenix/user/dvp/gen/QCD35/

My G4 setup is here: /phenix/upgrades/decadal/dvp/production-IHCal/macros/macros/g4simulations/ 

At this point, I have not kept the resulting G4 hits files, but have rather “tree-ified” the results using a simple TreeMaker class you can find here: /direct/phenix+upgrades/decadal/dvp/production-IHCal/src/ . The trees store the (pt/eta/phi) for truth and tower-reco jets for R=0.2,0.3,0.4,0.5 cone sizes, as well as the pt/eta/phi/particle-ID of all final-state truth particles. A few comments here:

1. R=0.5 is a somewhat larger cone size than we normally look at, but I included it for completeness so analyzers can study the jet R-dependence of these different scenarios.
2. The final-state truth particles are included so that analyzers can also study the fragmentation pattern (for example, max-z) dependence. 
3. I think we have been wanting a “standard” tree-maker AKA ntuple-dumper like this for a while — we should flesh this out and formally add it to git soon.

Anyway, I have compiled the resulting output trees, which should have 10k events each, here: 

/sphenix/user/dvp/sims/sPHENIX-Sep17-QCD35-10k-DefaultIHCal.root
/sphenix/user/dvp/sims/sPHENIX-Sep17-QCD35-10k-AlIHCal.root           
/sphenix/user/dvp/sims/sPHENIX-Sep17-QCD35-10k-AlIHCalNoReadout.root

I would strongly and warmly encourage Aaron, Songkyo, Raghav and any other interested parties to please take a look at the setup and the resulting output trees. (I know that the Colorado group is planning to have a look at these outputs and try to produce some initial plots for the simulations meeting tomorrow, but it is highly preferable that this is not the only group doing so.)

Actually, I know that Raghav has taken the lead and run some initial simulations of his own — I attach some slides from him here which briefly summarize those studies. In the near future, it would be great to check that we are getting consistent answers in the region where our simulations overlap.

Depending on how the first studies turn out, we are happy to coordinate an additional production (including “tree-ification”) with HIJING embedding and a more extensive pT range, also in the near future.

All are welcome and encouraged to take a look,

Dennis

Dennis V. Perepelitsa
Assistant Professor, Physics Department
University of Colorado Boulder

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John Lajoie

Professor of Physics

Iowa State University

 

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