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  • README.md

    r285752e rc1ea422  
    55
    66More details can be found on the Delphes website http://cp3.irmp.ucl.ac.be/projects/delphes
    7 
    8 Quick start with Delphes
    9 ========================
    10 
    11 Commands 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 
    19 Commands to compile the code:
    20 
    21 ```
    22    cd Delphes-3.4.1
    23 
    24    make
    25 ```
    26 
    27 Finally, we can run Delphes:
    28 
    29 ```
    30    ./DelphesHepMC
    31 ```
    32 
    33 Command 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 
    43 Let'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 
    51 or
    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 
    57 For more detailed documentation, please visit https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook
    58 
    59 Configure Delphes on lxplus.cern.ch
    60 ====================================
    61 
    62 ```
    63 git clone git://github.com/delphes/delphes.git Delphes
    64 
    65 cd Delphes
    66 
    67 source  /afs/cern.ch/sw/lcg/external/gcc/4.9.3/x86_64-slc6/setup.sh
    68 
    69 source /afs/cern.ch/sw/lcg/app/releases/ROOT/6.06.00/x86_64-slc6-gcc49-opt/root/bin/thisroot.sh
    70 
    71 make
    72 ```
    73 
    74 Simple analysis using TTree::Draw
    75 =================================
    76 
    77 Now we can start [ROOT](root.cern) and look at the data stored in the output ROOT file.
    78 
    79 Start ROOT and load Delphes shared library:
    80 
    81 ```
    82    root -l
    83    gSystem->Load("libDelphes");
    84 ```
    85 
    86 Open 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 
    94 Notes:
    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 
    98 Complete description of all branches can be found in [doc/RootTreeDescription.html](doc/RootTreeDescription.html).
    99 This information is also available [in the workbook](https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/RootTreeDescription).
    100 
    101 Macro-based analysis
    102 ====================
    103 
    104 Analysis macro consists of histogram booking, event loop (histogram filling),
    105 histogram display.
    106 
    107 Start ROOT and load Delphes shared library:
    108 
    109 ```
    110    root -l
    111    gSystem->Load("libDelphes");
    112 ```
    113 
    114 Basic 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 
    159 More advanced macro-based analysis
    160 ==================================
    161 
    162 The 'examples' directory contains ROOT macros [Example1.C](examples/Example1.C), [Example2.C](examples/Example2.C) and [Example3.C](examples/Example3.C).
    163 
    164 Here are the commands to run these ROOT macros:
    165 
    166 ```
    167    root -l
    168    .X examples/Example1.C("delphes_output.root");
    169 ```
    170 
    171 or
    172 
    173 ```
    174    root -l examples/Example1.C'("delphes_output.root")'
    175 ```
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