{
  TFile *f = TFile::Open("gate244_Eu.root");
  f->ls();
  TCanvas *c; f->GetObject("Canvas_1", c);
  c->ls();
  TH1D *hist=(TH1D*)c->FindObject("e_t2_1_py");
  
  TF1  *fit = new TF1("fit", "([0]/(2.*[3]))*exp((pow([2],2.))/(2.*pow([3],2.))-(x-[1])/[3])*TMath::Erfc((1./sqrt(2.))*(([2]/[3])-((x-[1])/[2])))", -30000., 30000.);
  fit->SetNpx(TMath::Max(100, 3 * hist->GetNbinsX())); // at least 100 points
  
  fit->SetParameters(2.e5, -5.e3, 5.e2, 2.e3);
  
  c->Draw();
  // gPad->SetLogy(0);
  hist->Fit("fit");
  
  gPad->Modified(); gPad->Update();
}