Delphes ======= Delphes is a C++ framework, performing a fast multipurpose detector response simulation. More details can be found on the Delphes website http://cp3.irmp.ucl.ac.be/projects/delphes Quick start with Delphes ======================== Commands to get the code: ``` wget http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.4.1.tar.gz tar -zxf Delphes-3.4.1.tar.gz ``` Commands to compile the code: ``` cd Delphes-3.4.1 make ``` Finally, we can run Delphes: ``` ./DelphesHepMC ``` Command line parameters: ``` ./DelphesHepMC config_file output_file [input_file(s)] config_file - configuration file in Tcl format output_file - output file in ROOT format, input_file(s) - input file(s) in HepMC format, with no input_file, or when input_file is -, read standard input. ``` Let's simulate some Z->ee events: ``` wget http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz gunzip z_ee.hep.gz ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root z_ee.hep ``` or ``` curl -s http://cp3.irmp.ucl.ac.be/downloads/z_ee.hep.gz | gunzip | ./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output.root ``` For more detailed documentation, please visit https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook Configure Delphes on lxplus.cern.ch ==================================== ``` git clone git://github.com/delphes/delphes.git Delphes cd Delphes source /afs/cern.ch/sw/lcg/external/gcc/4.9.3/x86_64-slc6/setup.sh source /afs/cern.ch/sw/lcg/app/releases/ROOT/6.06.00/x86_64-slc6-gcc49-opt/root/bin/thisroot.sh make ``` Simple analysis using TTree::Draw ================================= Now we can start ROOT and look at the data stored in the output ROOT file. Start ROOT and load Delphes shared library: ``` root -l gSystem->Load("libDelphes"); ``` Open ROOT file and do some basic analysis using Draw or TBrowser: ``` TFile::Open("delphes_output.root"); Delphes->Draw("Electron.PT"); TBrowser browser; ``` Note 1: Delphes - tree name, it can be learned e.g. from TBrowser Note 2: Electron - branch name; PT - variable (leaf) of this branch Complete description of all branches can be found in doc/RootTreeDescription.html This information is also available at https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/RootTreeDescription Macro-based analysis ==================== Analysis macro consists of histogram booking, event loop (histogram filling), histogram display. Start ROOT and load Delphes shared library: ``` root -l gSystem->Load("libDelphes"); ``` Basic analysis macro: ``` { // Create chain of root trees TChain chain("Delphes"); chain.Add("delphes_output.root"); // Create object of class ExRootTreeReader ExRootTreeReader *treeReader = new ExRootTreeReader(&chain); Long64_t numberOfEntries = treeReader->GetEntries(); // Get pointers to branches used in this analysis TClonesArray *branchElectron = treeReader->UseBranch("Electron"); // Book histograms TH1 *histElectronPT = new TH1F("electron pt", "electron P_{T}", 50, 0.0, 100.0); // Loop over all events for(Int_t entry = 0; entry < numberOfEntries; ++entry) { // Load selected branches with data from specified event treeReader->ReadEntry(entry); // If event contains at least 1 electron if(branchElectron->GetEntries() > 0) { // Take first electron Electron *electron = (Electron*) branchElectron->At(0); // Plot electron transverse momentum histElectronPT->Fill(electron->PT); // Print electron transverse momentum cout << electron->PT << endl; } } // Show resulting histograms histElectronPT->Draw(); } ``` More advanced macro-based analysis ================================== The 'examples' directory contains ROOT macros Example1.C, Example2.C and Example3.C. Here are the commands to run these ROOT macros: ``` root -l .X examples/Example1.C("delphes_output.root"); ``` or ``` root -l examples/Example1.C'("delphes_output.root")' ```