void effPlot(void){ 
  gROOT->Reset();//Reset session memory
  gROOT->SetStyle("Plain");//Make style plain
  gStyle->SetOptStat(0);//Remove the statistics box from histogram

  //Make a canvas
  TCanvas * myCanvas = new TCanvas("myCanvas","Me canvas title");

  //For this example, I will plot 5 points
  const Int_t nPoints = 10;
  //Create vectors that have the x and y coordinates 
  Double_t xVec[nPoints] = {7.2,7.6,8.0,8.4,8.8,9.2,9.6,10.0,10.4,10.8};
  Double_t yVec[nPoints] = {5.41e-4, 6.37e-4, 6.10e-4, 7.30e-4, 7.05e-4,
			    7.35e-4, 7.00e-4, 7.27e-4, 8.73e-4, 6.67e-4};
  //Create vectors that have the x and y errors
  Double_t xErrVec[nPoints] = {0,0,0,0,0}; //Common for x-error = 0
  Double_t yErrVec[nPoints] = {2.3e-5, 2.5e-5, 5.5e-5, 6.0e-5, 5.9e-5,
			       6.1e-5, 5.9e-5, 7.0e-5, 7.6e-5, 6.7e-5};
  //Create the TGraphErrors object
  TGraphErrors * myGraph = new TGraphErrors(nPoints-1,xVec,yVec,xErrVec,yErrVec);
  //Remove the title box 
  myGraph->SetTitle("");
  //Set the marker style and color. 
  //See: https://root.cern.ch/doc/master/classTAttMarker.html
  myGraph->SetMarkerStyle(21);
  myGraph->SetMarkerColor(2);
  //Set the marker size
  myGraph->SetMarkerSize(1.0);
  //Draw the graph
  myGraph->Draw("AP");//A->Draw axis, L->Polyline, P->Draw marker

  myGraph->GetXaxis()->SetTitle("E_{#gamma} (GeV)");
  myGraph->GetYaxis()->SetTitle("Efficiency");
  myGraph->GetYaxis()->SetTitleOffset(1.3);
  myGraph->SetMinimum(0);
  return;
}