#include <vector>
#include <string>
#include <TFile.h>
#include <TTree.h>
#include <TObject.h>
#include <TClonesArray.h>

class Hit : public TObject {
  public:
    char const *id;   //Particle identity, i.e. alpha, proton ...
    double e;         //Reconstructed kinetic energy of particle.
    vector<std::string> det;  //List of detectors that were hit.
    std::vector<double> edep; //Energy deposited in the individual detectors.

  ClassDef(Hit,1);
};

void Minimal()
{
  TFile *f = new TFile("test.root","RECREATE");
  TTree *outTree = new TTree("data","Identified particle hits.");
  TClonesArray hits("Hit",10);
  outTree->Branch("hits", &hits,32000,0);

  //Hit 1:
  Hit *hit1 = (Hit*)hits.ConstructedAt(0);
  hit1->id = "alpha";
  hit1->e = 12.;
  hit1->det.push_back("D1");
  hit1->det.push_back("D2");
  hit1->edep.push_back(3.); //Energy deposited by alpha in D1
  hit1->edep.push_back(9.); //Energy deposited by alpha in D2

  //Hit 2:
  Hit *hit2 = (Hit*)hits.ConstructedAt(1);
  hit2->id = "proton";
  hit2->e = 25.;
  hit2->det.push_back("D2");
  hit2->det.push_back("D3");
  hit2->edep.push_back(8.);  //Energy dep. by proton in D2.
  hit2->edep.push_back(13.); //Energy dep. by proton in D3.

  outTree->Fill();
  outTree->Write();
  f->Close();
}