Changes in README.md [fe6bd24:21f3c04] in git

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• README.md (modified) (1 diff)

README.md

@@ -1 @@
-delphes
-=======
+Quick start with Delphes
+========================
 
-A framework for fast simulation of a generic collider experiment
+Commands to get the code:
+
+```
+wget http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.1.2.tar.gz
+
+tar -zxf Delphes-3.1.2.tar.gz
+```
+
+Commands to compile the code:
+
+```
+cd Delphes-3.1.2
+
+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 examples/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 examples/delphes_card_CMS.tcl delphes_output.root
+```
+
+For more detailed documentation, please visit 
+
+https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook
+
+
+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")'
+```