1 |
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2 |
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3 | Quick start with Delphes
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4 | ========================
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5 |
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6 | Commands to get the code:
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7 |
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8 | wget http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.4.1.tar.gz
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9 |
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10 | tar -zxf Delphes-3.4.1.tar.gz
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11 |
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12 | Commands to compile the code:
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13 |
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14 | cd Delphes-3.4.1
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15 |
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16 | make
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17 |
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18 | Finally, we can run Delphes:
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19 |
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20 | ./DelphesHepMC
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21 |
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22 | Command line parameters:
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23 |
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24 | ./DelphesHepMC config_file output_file [input_file(s)]
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25 | config_file - configuration file in Tcl format
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26 | output_file - output file in ROOT format,
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27 | input_file(s) - input file(s) in HepMC format,
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28 | with no input_file, or when input_file is -, read standard input.
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29 |
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30 | Let's simulate some Z->ee events:
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31 |
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32 | wget http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz
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33 | gunzip z_ee.hep.gz
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34 | ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root z_ee.hep
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35 |
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36 | or
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37 |
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38 | curl -s http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz | gunzip | ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root
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39 |
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40 | For more detailed documentation, please visit
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41 |
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42 | https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook
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43 |
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44 | Configure Delphes on lxplus.cern.ch
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45 | ====================================
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46 |
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47 | git clone git://github.com/delphes/delphes.git Delphes
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48 |
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49 | cd Delphes
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50 |
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51 | source /afs/cern.ch/sw/lcg/external/gcc/4.9.3/x86_64-slc6/setup.sh
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52 |
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53 | source /afs/cern.ch/sw/lcg/app/releases/ROOT/6.06.00/x86_64-slc6-gcc49-opt/root/bin/thisroot.sh
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54 |
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55 | make
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56 |
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57 |
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58 | Simple analysis using TTree::Draw
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59 | =================================
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60 |
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61 | Now we can start ROOT and look at the data stored in the output ROOT file.
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62 |
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63 | Start ROOT and load Delphes shared library:
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64 |
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65 | root -l
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66 | gSystem->Load("libDelphes");
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67 |
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68 | Open ROOT file and do some basic analysis using Draw or TBrowser:
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69 |
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70 | TFile::Open("delphes_output.root");
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71 | Delphes->Draw("Electron.PT");
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72 | TBrowser browser;
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73 |
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74 | Note 1: Delphes - tree name, it can be learned e.g. from TBrowser
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75 |
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76 | Note 2: Electron - branch name; PT - variable (leaf) of this branch
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77 |
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78 | Complete description of all branches can be found in
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79 |
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80 | doc/RootTreeDescription.html
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81 |
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82 | This information is also available at
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83 |
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84 | https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/RootTreeDescription
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85 |
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86 | Macro-based analysis
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87 | ====================
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88 |
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89 | Analysis macro consists of histogram booking, event loop (histogram filling),
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90 | histogram display.
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91 |
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92 | Start ROOT and load Delphes shared library:
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93 |
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94 | root -l
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95 | gSystem->Load("libDelphes");
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96 |
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97 | Basic analysis macro:
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98 |
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99 | {
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100 | // Create chain of root trees
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101 | TChain chain("Delphes");
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102 | chain.Add("delphes_output.root");
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103 |
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104 | // Create object of class ExRootTreeReader
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105 | ExRootTreeReader *treeReader = new ExRootTreeReader(&chain);
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106 | Long64_t numberOfEntries = treeReader->GetEntries();
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107 |
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108 | // Get pointers to branches used in this analysis
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109 | TClonesArray *branchElectron = treeReader->UseBranch("Electron");
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110 |
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111 | // Book histograms
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112 | TH1 *histElectronPT = new TH1F("electron pt", "electron P_{T}", 50, 0.0, 100.0);
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113 |
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114 | // Loop over all events
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115 | for(Int_t entry = 0; entry < numberOfEntries; ++entry)
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116 | {
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117 |
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118 | // Load selected branches with data from specified event
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119 | treeReader->ReadEntry(entry);
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120 |
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121 | // If event contains at least 1 electron
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122 | if(branchElectron->GetEntries() > 0)
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123 | {
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124 | // Take first electron
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125 | Electron *electron = (Electron*) branchElectron->At(0);
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126 |
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127 | // Plot electron transverse momentum
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128 | histElectronPT->Fill(electron->PT);
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129 |
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130 | // Print electron transverse momentum
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131 | cout << electron->PT << endl;
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132 | }
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133 |
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134 | }
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135 |
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136 | // Show resulting histograms
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137 | histElectronPT->Draw();
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138 | }
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139 |
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140 |
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141 | More advanced macro-based analysis
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142 | ==================================
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143 |
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144 | The 'examples' directory contains ROOT macros Example1.C, Example2.C and Example3.C.
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145 |
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146 | Here are the commands to run these ROOT macros:
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147 |
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148 | root -l
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149 | .X examples/Example1.C("delphes_output.root");
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150 |
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151 | or
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152 |
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153 | root -l examples/Example1.C'("delphes_output.root")'
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