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  • README.md

    rc1ea422 r285752e  
    55
    66More details can be found on the Delphes website http://cp3.irmp.ucl.ac.be/projects/delphes
     7
     8Quick start with Delphes
     9========================
     10
     11Commands to get the code:
     12
     13```
     14   wget http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.4.1.tar.gz
     15
     16   tar -zxf Delphes-3.4.1.tar.gz
     17```
     18
     19Commands to compile the code:
     20
     21```
     22   cd Delphes-3.4.1
     23
     24   make
     25```
     26
     27Finally, we can run Delphes:
     28
     29```
     30   ./DelphesHepMC
     31```
     32
     33Command line parameters:
     34
     35```
     36   ./DelphesHepMC config_file output_file [input_file(s)]
     37     config_file - configuration file in Tcl format
     38     output_file - output file in ROOT format,
     39     input_file(s) - input file(s) in HepMC format,
     40     with no input_file, or when input_file is -, read standard input.
     41```
     42
     43Let's simulate some Z->ee events:
     44
     45```
     46   wget http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz
     47   gunzip z_ee.hep.gz
     48   ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root z_ee.hep
     49```
     50
     51or
     52
     53```
     54   curl -s http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz | gunzip | ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root
     55```
     56
     57For more detailed documentation, please visit https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook
     58
     59Configure Delphes on lxplus.cern.ch
     60====================================
     61
     62```
     63git clone git://github.com/delphes/delphes.git Delphes
     64
     65cd Delphes
     66
     67source  /afs/cern.ch/sw/lcg/external/gcc/4.9.3/x86_64-slc6/setup.sh
     68
     69source /afs/cern.ch/sw/lcg/app/releases/ROOT/6.06.00/x86_64-slc6-gcc49-opt/root/bin/thisroot.sh
     70
     71make
     72```
     73
     74Simple analysis using TTree::Draw
     75=================================
     76
     77Now we can start [ROOT](root.cern) and look at the data stored in the output ROOT file.
     78
     79Start ROOT and load Delphes shared library:
     80
     81```
     82   root -l
     83   gSystem->Load("libDelphes");
     84```
     85
     86Open ROOT file and do some basic analysis using Draw or TBrowser:
     87
     88```
     89   TFile::Open("delphes_output.root");
     90   Delphes->Draw("Electron.PT");
     91   TBrowser browser;
     92```
     93
     94Notes:
     95* ```Delphes``` is the tree name. It can be learned e.g. from TBrowser.
     96* ```Electron```is the branch name; ```PT``` is a variable (leaf) of this branch.
     97
     98Complete description of all branches can be found in [doc/RootTreeDescription.html](doc/RootTreeDescription.html).
     99This information is also available [in the workbook](https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/RootTreeDescription).
     100
     101Macro-based analysis
     102====================
     103
     104Analysis macro consists of histogram booking, event loop (histogram filling),
     105histogram display.
     106
     107Start ROOT and load Delphes shared library:
     108
     109```
     110   root -l
     111   gSystem->Load("libDelphes");
     112```
     113
     114Basic analysis macro:
     115
     116```
     117{
     118  // Create chain of root trees
     119  TChain chain("Delphes");
     120  chain.Add("delphes_output.root");
     121 
     122  // Create object of class ExRootTreeReader
     123  ExRootTreeReader *treeReader = new ExRootTreeReader(&chain);
     124  Long64_t numberOfEntries = treeReader->GetEntries();
     125 
     126  // Get pointers to branches used in this analysis
     127  TClonesArray *branchElectron = treeReader->UseBranch("Electron");
     128
     129  // Book histograms
     130  TH1 *histElectronPT = new TH1F("electron pt", "electron P_{T}", 50, 0.0, 100.0);
     131
     132  // Loop over all events
     133  for(Int_t entry = 0; entry < numberOfEntries; ++entry)
     134  {
     135
     136    // Load selected branches with data from specified event
     137    treeReader->ReadEntry(entry);
     138 
     139    // If event contains at least 1 electron
     140    if(branchElectron->GetEntries() > 0)
     141    {
     142      // Take first electron
     143      Electron *electron = (Electron*) branchElectron->At(0);
     144     
     145      // Plot electron transverse momentum
     146      histElectronPT->Fill(electron->PT);
     147     
     148      // Print electron transverse momentum
     149      cout << electron->PT << endl;
     150    }
     151
     152  }
     153
     154  // Show resulting histograms
     155  histElectronPT->Draw();
     156}
     157```
     158
     159More advanced macro-based analysis
     160==================================
     161
     162The 'examples' directory contains ROOT macros [Example1.C](examples/Example1.C), [Example2.C](examples/Example2.C) and [Example3.C](examples/Example3.C).
     163
     164Here are the commands to run these ROOT macros:
     165
     166```
     167   root -l
     168   .X examples/Example1.C("delphes_output.root");
     169```
     170
     171or
     172
     173```
     174   root -l examples/Example1.C'("delphes_output.root")'
     175```
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