void  fit_gain(int run){
  
  cout << endl;
  cout << "Run number =" << run << endl;
  cout << endl;

  char file_name[20];
  sprintf(file_name,"%d.root",run);

  TFile *file = new TFile(file_name);


  TH1F  *int_led1    = (TH1F *)file->Get("int_led1");
  TH1F  *int_alpha1  = (TH1F *)file->Get("int_alpha1");


  TH1F *ccal_int[144];

  for(Int_t ii = 0; ii < 144; ii++){

      char title[30];
      sprintf(title,"Int_%d",ii); 
      ccal_int[ii]   = (TH1F *)file->Get(title);

  }


  // 1st histogram

  TCanvas *c1 = new TCanvas("c1","New Canvas",200,10,400,300);


  c1->cd();
  
  int peak_bin = 0;
  
  double peak_max = 0;

  int bin_min = 1;
  int bin_max = 500;

  for(int bin = bin_min; bin < bin_max; bin++){ 

    double peak_val = int_led1->GetBinContent(bin);
   
    if(peak_val > peak_max){
      peak_max = peak_val;
      peak_bin = bin;
    }
  }



  Double_t peak_x = int_led1->GetXaxis()->GetBinCenter(peak_bin);

  cout << "Peak X = " << peak_x << endl;

  fit_func = new TF1("fit_func","gaus");

  fit_func->SetParameters(1,peak_x);
  
  int_led1->GetXaxis()->SetRangeUser(0,peak_x*2);

  int_led1->Fit("fit_func","S","",peak_x*0.8 ,peak_x*1.3);


  double fit_amp_led   =  fit_func->GetParameter(1);
  double efit_amp_led  =  fit_func->GetParError(1);


  int_alpha1->Fit("fit_func","S","");

  double fit_amp_alpha   =  fit_func->GetParameter(1);
  double efit_amp_alpha  =  fit_func->GetParError(1);


  //  ccal_int[2]->Draw();

  double fit_cell[150];
  double efit_cell[150];

  for(Int_t ii = 0; ii < 144; ii++){

    int entries=ccal_int[ii]->GetEntries();
    
    if(entries == 0){
      cout << " No enetries " << ii << endl;
      //      getchar();
      continue;
    }

    int binmax = ccal_int[ii]->GetMaximumBin(); 
    double x = ccal_int[ii]->GetXaxis()->GetBinCenter(binmax);

    fit_func->SetParameter(1,x);
    fit_func->SetParameter(2,0.01*x);

    double x_min = x*0.94;
    double x_max = x*1.06;

    cout << " X = " << x << " X_MIN = " << x_min <<  " X_MAX = " << x_max << endl;

    fit_cell[ii]   = 0;
    efit_cell[ii]  = 0;
    ccal_int[ii]->Fit("fit_func","S","",x_min, x_max);
    fit_cell[ii]  = fit_func->GetParameter(1);
    efit_cell[ii] = fit_func->GetParError(1);

    cout << " II = " << ii << " X = " << x << " X_MIN = " << x_min <<  " X_MAX = " << x_max << "  " << fit_cell[ii] << endl;

  }



  FILE *out_file= fopen("my_test.txt","a+");

  fprintf(out_file,"%d     %f     %f     %f     %f ", run, fit_amp_led, efit_amp_led,fit_amp_alpha,efit_amp_alpha);

  for(Int_t ii = 0; ii < 144; ii++) 
    fprintf(out_file, "  %f  %f ", fit_cell[ii],  efit_cell[ii]);

  fprintf(out_file,"\n");

  fclose(out_file);

}