To plot x y and z distribution from Hepmc file

[Yasir_Ali]

Dear Experts

I have hepmc file can you Please suggest How can i plot x y and z distributions using this file. File can be downloaded from

bremge_1keV_eic.hepmc

I have this code which is suppose to convert hepmc file to root file:

#include <iostream>
#include <fstream>
#include "HepMC/IO_GenEvent.h"
#include "TFile.h"
#include "TTree.h"

int main() {
    // Open the input HepMC file
    HepMC::IO_GenEvent input("input.hepmc", std::ios::in);

    // Create the output ROOT file
    TFile output("output.root", "RECREATE");

    // Create a ROOT tree to store the event information
    TTree tree("Events", "Event data");

    // Define variables for event information
    Int_t nParticles;
    Float_t px[10000], py[10000], pz[10000], E[10000], m[10000], vx[10000], vy[10000], vz[10000];
    Int_t pdgId[10000], status[10000], parentIndex[10000];

    // Set branch addresses for the tree
    tree.Branch("nParticles", &nParticles, "nParticles/I");
    tree.Branch("px", px, "px[nParticles]/F");
    tree.Branch("py", py, "py[nParticles]/F");
    tree.Branch("pz", pz, "pz[nParticles]/F");
    tree.Branch("E", E, "E[nParticles]/F");
    tree.Branch("m", m, "m[nParticles]/F");
    tree.Branch("vx", vx, "vx[nParticles]/F");
    tree.Branch("vy", vy, "vy[nParticles]/F");
    tree.Branch("vz", vz, "vz[nParticles]/F");
    tree.Branch("pdgId", pdgId, "pdgId[nParticles]/I");
    tree.Branch("status", status, "status[nParticles]/I");
    tree.Branch("parentIndex", parentIndex, "parentIndex[nParticles]/I");

    // Loop over each event in the HepMC file
    HepMC::GenEvent* event;
    while ((event = input.read_next_event()) != nullptr) {
        // Clear the event variables
        nParticles = 0;

        // Loop over each particle in the event
        for (auto particle = event->particles_begin(); particle != event->particles_end(); ++particle) {
            // Store particle information in arrays
            px[nParticles] = (*particle)->momentum().px();
            py[nParticles] = (*particle)->momentum().py();
            pz[nParticles] = (*particle)->momentum().pz();
            E[nParticles] = (*particle)->momentum().e();
            m[nParticles] = (*particle)->momentum().m();
            vx[nParticles] = (*particle)->production_vertex()->position().x();
            vy[nParticles] = (*particle)->production_vertex()->position().y();
            vz[nParticles] = (*particle)->production_vertex()->position().z();
            pdgId[nParticles] = (*particle)->pdg_id();
            status[nParticles] = (*particle)->status();
            parentIndex[nParticles] = (*particle)->production_vertex()->particles_in_size();

            // Increment the particle counter
            nParticles++;
        }

        // Fill the tree with event information
        tree.Fill();

        // Delete the current event
        delete event;
    }

    // Write the tree to the ROOT file
    tree.Write();

    // Close the ROOT file
    output.Close();

    std::cout << "Conversion complete." << std::endl;

    return 0;
}

but it gives error of:

/home/yasir/eic/treeReaderExample.C:3:10: fatal error: 'HepMC/IO_GenEvent.h' file not found
#include "HepMC/IO_GenEvent.h"

[Yasir_Ali]

@Danny1 I am trying to convert hepmc file to root and I was trying to use GitHub - hbprosper/hepmc2root: Python program to convert a text file of events in HepMC2 format to a simple ROOT file.

but when i run yasir@yasir-X270:~/Downloads/hepmc2root-master/example$ hepmc2root.py susy200.hepmc it gives error

hepmc2root.py: command not found

[couet]

From the example folder try:

$ ../bin/hepmc2root.py susy200.root

but in my case I get some errors from that python script.