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STAR Software Walk-Through

STAR Software Walk-Through. Doing analysis in a large collaboration: Overview. The experiment: Collider runs for many weeks every year. A lot of data to look at! In 2007, ~70M minimum bias events. Need computers to be able to analyze vast dataset. Analysis Software: Find relevant data

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STAR Software Walk-Through

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  1. STAR Software Walk-Through

  2. Doing analysis in a large collaboration: Overview • The experiment: • Collider runs for many weeks every year. • A lot of data to look at! • In 2007, ~70M minimum bias events. • Need computers to be able to analyze vast dataset. • Analysis Software: • Find relevant data • Develop analysis code • Interface to the data • Analysis code: plots and correlations of experimentally measured quantities • Submitting jobs to the batch farm • Plotting results

  3. Computing resources • Facilities available for STAR • PDSF (in Berkeley, part of NERSC) • Parallel Distributed Systems Facility • RCF (in Brookhaven Lab) • RHIC Computing Facility • Log in to PDSF: pdsf.nersc.gov • Web page: • http://www.nersc.gov/nusers/resources/PDSF/ • FAQ • USER accounts • Monitoring of farm conditions • … • Log in to RCF: rssh.rhic.bnl.gov • Web page: • http://www.rhic.bnl.gov/RCF/

  4. Doing Analysis 101 • For real or simulated data that has already been produced into a standard format: Run analysis on data. Tools: MuDST StMcEvent Plot results of analysis. Tools: ROOT classes. Find Data HPSS NFS local. Tools: FileCatalog

  5. Tools: • FileCatalog (get_file_list.pl) • http://www.star.bnl.gov/STAR/comp/sofi/FileCatalog/ • Finding Files (of course) that satisfy certain conditions: • production library used, trigger setup used, run numbers, collision system, … • i.e. it is a database of our data. • Examples of usage found in link above. • Note for PDSF: make sure you have a .chos file. I selected /auto/redhat8 as my environment. • Without an environment properly set, perl won’t work!

  6. Tools: • Scheduler • Used to submit jobs to the RCAS linux farm in batch mode. • RCAS: ~10 interactive nodes, ~150 batch nodes. • How to use it: • XML script that specifies • files to be used (e.g. using a catalog query) • macro to be executed (i.e. analysis to be done) • what to do with the output

  7. Analyzing Example: Real Data, Step I • Find events of interest • e.g. Au Au collisions, 200 GeV. (2004 data) • Many collisions and triggers have been used. • Example: Looking at “Minimum bias” triggers • This trigger is meant to capture almost all interactions. • Every trigger detector introduces a bias, this trigger is meant to reduce the bias introduced as much as possible. • Trigger ID: • Each file can have events that were selected by various trigger conditions • ID picks out a given trigger condition. • 2004 list of triggers: • http://www.star.bnl.gov/protected/common/common2004/trigger2004/triggers2004.html

  8. A file catalog query… pc2606:~ 54> get_file_list.pl -keys 'path,filename' -cond 'storage=NFS,filename~st_physics,collision=auau200,filetype=daq_reco_mudst' -limit 10 /dante3/starprod/reco/productionCentral/FullField/P02ge/2001/321::st_physics_2321030_raw_0102.MuDst.root /dante3/starprod/reco/productionCentral/FullField/P02ge/2001/321::st_physics_2321003_raw_0127.MuDst.root /eliza12/starprod/reco/productionMinBias/FullField/P05ic/2004/030::st_physics_5030114_raw_1010013.MuDst.root /eliza12/starprod/reco/productionMinBias/FullField/P05ic/2004/030::st_physics_5030114_raw_1010022.MuDst.root /eliza12/starprod/reco/productionMinBias/FullField/P05ic/2004/030::st_physics_5030114_raw_1020018.MuDst.root

  9. Define an Analysis Task • Examples: • Multiplicity Distribution • ~Probability to find events with Nch tracks. • Nch: number of charged particles in the event (typically, per unit rapidity at midrapidity). • pT distribution of charged tracks for all events. • ~Probability to find a track with a given pT.

  10. The “Maker” framework • “Makers” are a way to standardize the way we do analysis: • All have to “prepare” or initialize • e.g. book histograms and trees • All do something every event • e.g. calculate or obtain distributions of interest • All have to clean up when the job is done • e.g. write the histograms

  11. Example Maker code: • In PDSF: • /auto/pdsfdv39/starspec/pdsfdv34/starspec/calderon/tutorials/StRoot/StMuDstExampleAnalysisMaker • All Makers live under a directory called StRoot • Compilation of the analysis code is done in same directory where StRoot directory (or link) is found • cons +StMuDstExample • Running is done in same directory where compilation was done. Example in StRoot/macros/examples/ • root4star –b –q ‘RunMuDstExample.C(500)'

  12. Plotting the results • Open the output file (dummyFile00.root) in root. Can issue C++ commands on the root classes interactively. • Set a sensible color scheme • gStyle->SetPalette(1,0); • Create canvases (TCanvas) • TCanvas* cnv1 = new TCanvas(“cnv1”,”multiplicity”,600,600); • For drawing histograms: • TH1::Draw() • mMult->Draw(); • Can change line color, width, style • mMult->SetLineColor(2); • mMult->SetLineWidth(3); • mMult->SetLineStyle(11); • Can draw markers • mMult->SetMarkerStyle(20); • mMult->Draw(“P”); • For reproducibility, can also put all the commands into a macro, and just execute the macro: • .x plotMultExample.C

  13. Analyzing Example: Simulation, Step I • Generate events of interest • e.g. Lambda_c, Upsilon, J/Psi particles according to a distribution • e.g. use event generators • PYTHIA • HERWIG • HIJING • NEXUS • AMPT • MPC • For large datasets, request is done officially to STAR simulation (Maxim Potekhin, simulation leader)

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