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The experiment:
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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:
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Find relevant data
Develop analysis code
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Interface to the data
Analysis code: plots and correlations of experimentally measured quantities
Submitting jobs to the batch farm
Plotting results

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

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Find Data
HPSS
NFS local.
Tools:
FileCatalog
Run analysis on data.
Tools:
MuDST
StMcEvent
Plot results of analysis.
Tools:
ROOT classes.

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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.
Production Location
– STAR → Computing → Production Location
– http://www.star.bnl.gov/webdata/pub/overall.html#PLOC

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– Used to submit jobs to the RCAS linux farm in batch mode.
– RCAS: ~10 interactive nodes, ~150 batch nodes.
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How to use it:
 XML script that specifies
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– 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
STAR → Computing → Scheduler
 http://www.star.bnl.gov/public/comp/Grid/scheduler/

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Find events of interest
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Au Au collisions, 200 GeV.
p+p collisions, 200 GeV
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:
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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
2009 data:
 http://www.star.bnl.gov/protected/common/common2009/trigger2009/trigidtable.html

output: path and filename of file.
query conditions:
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Production: P10ic, production from 2010, real data, official production (pp2009 data)
Filetype: daq_reco_mudst: came from DAQ (real data), processed through the reconstruction chain, stored into a micro Data Summary Tape.
storage: NFS. Mounted on hard disks accessible through the Networked File
System, as opposed to the files stored on tape drives in HPSS.
~/afsdir/wrk/jpsi/offline/> get_file_list.pl -keys 'path,filename' -cond
'production=P10ic,filetype=daq_reco_mudst,storage=NFS,sanity=1,filename~st
_upsilon' -limit 10
/star/data81/reco/production2009_200Gev_Single/ReversedFullField/P10ic/2009/1
38/10138054::st_upsilon_adc_10138054_raw_8350001.MuDst.root
/star/data76/reco/production2009_200Gev_Single/ReversedFullField/P10ic/2009/1
39/10139015::st_upsilon_adc_10139015_raw_7350001.MuDst.root
/star/data81/reco/production2009_200Gev_Single/ReversedFullField/P10ic/2009/1
38/10138054::st_upsilon_adc_10138054_raw_5350001.MuDst.root

 The result of the reconstruction of an event.
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Trigger information.
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Signal in ZDC, BBC, VPD, EMC, …
Track information.
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Number of points found by tracker and used in fit
Momentum at first point and last point (and helix parameters)
Covariance matrix of track fit dE/dx
– nSigma, PID probability charge id of track in event (unique number for a track in an event) type (0=global, 1=primary) c
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Topology Map: bit pattern of hits in detector
Distance of closest approach to vertex (for global)
Position of first and last points
 TBrowser, check contents of file. ROOT objects can be drawn quickly.

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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.

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All have to “prepare” or initialize
 e.g. book histograms and trees
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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

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In PDSF:
/auto/pdsfdv39/starspec/pdsfdv34/starspec/calderon/tutorial s/ StRoot /StMuDstExampleAnalysisMaker
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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)'

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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)
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TCanvas* cnv1 = new TCanvas(“cnv1”,”multiplicity”,600,600);
For drawing histograms:
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TH1::Draw() mMult->Draw();
Can change line color, width, style
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– mMult->SetLineColor(2); mMult->SetLineWidth(3); mMult->SetLineStyle(11);
Can draw markers
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– 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

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