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README
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README
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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")'