void plot2(const char *filename = "occ2.root") 
{
  gStyle->SetOptStat(0);
  TFile *f = TFile::Open(filename);
  /*
  f->ls();
  tree->Print();
  */
  TCanvas *c = new TCanvas("c","c",10, 10, 700, 600);
  c->Divide(3,2);
  c_1->SetLogy();
  c_2->SetLogy();
  c_3->SetLogy();
  c_4->SetLogy();
  c_5->SetLogy();
  c_6->SetLogy();

  TCanvas *c2 = new TCanvas("c2","c2",10, 10, 700, 600);
  c2->Divide(3,2);
  c2_1->SetLogy();
  c2_2->SetLogy();
  c2_3->SetLogy();
  c2_4->SetLogy();
  c2_5->SetLogy();
  //  c2_6->SetLogy(); //not the last one

  TText *text = new TText;
  text->SetTextSize(0.05) ;
  char h1str[32];

  const int NPANELS = 6;
  const int NPLANES = 5;
  int ipanel, iplane;

  int nV[NPANELS] = {64,26,64,64,26,64};
  int nH[NPANELS] = {59,45,59,59,45,59}; 
  int ntot[2] = {308, 326};//{2*(2*64+26),2*(2*59+45)};

  int canvasOrder[NPANELS] = {1,2,3,6,5,4};
  int histcolor[NPLANES] = {1,2,3,4,6};

  char id[32], title[32], plotstr[32];

  // one arm, and orientation; or fem at a time
  for (int ifem = 0; ifem<4; ifem++) {
    int iarm = ifem/2;
    int iorient = ifem%2;

    for (ipanel = 0; ipanel < NPANELS; ipanel++) {
      c->cd(canvasOrder[ipanel]);
      int nbins;
      if (iorient == 0) { nbins = nH[ipanel]; }
      else { nbins = nV[ipanel]; }

      sprintf(title,"Arm %d Orient %d Panel %d",iarm,iorient,ipanel);
      TH1F *h1[NPLANES];
      Stat_t maxval = 0;
      int maxplane = 0;
      for (iplane = 0; iplane < NPLANES; iplane++) {
	// book histos
	sprintf(id,"h1[%d]",iplane);
	h1[iplane] = new TH1F(id,title,nbins+1,-0.5,nbins+0.5);
	h1[iplane]->SetLineColor(histcolor[iplane]);
	// and fill them
	sprintf(plotstr,"nchan_plane_panel[%d][%d][%d]>>%s",ifem,iplane,ipanel,id);
	//	cout << " plotstr " << plotstr << endl;
	tree->Draw(plotstr);
	//	h1[iplane]->Print();
	if (h1[iplane]->GetMaximum() > maxval ) {
	  maxval  =  h1[iplane]->GetMaximum();
	  maxplane = iplane;
	}
      } // iplane
      //      cout << " maxval " << maxval << endl;
      Stat_t logmaxval = log10(maxval);
      // Replot
      h1[maxplane]->DrawCopy("hist"); 
      for (iplane = 0; iplane < NPLANES; iplane++) {
	h1[iplane]->DrawCopy("hist same");
	// insert some text here too
	text->SetTextColor(histcolor[iplane]);
	sprintf(h1str,"Plane %d: Mean %3.2f",
		iplane, h1[iplane]->GetMean());
	text->DrawText(0.35*nbins,logmaxval*0.9 - 0.5*iplane,h1str);  
      }
      c->Update();
      for (iplane = 0; iplane < NPLANES; iplane++) {
	delete h1[iplane];
      }
    } // ipanel
    c->cd();
    c->Update();
    sprintf(plotstr,"plot2_arm%d_orient%d.gif",iarm,iorient);
    c->SaveAs(plotstr);

    TH1F *h2[NPLANES];
    // also do the plot showing the total hits per gap; 2nd canvas
    int nsumbins = NPLANES;
    sprintf(title,"Arm %d Orient %d Summary",iarm,iorient);
    TH1F *hsummary = new TH1F("hsummary",title,nsumbins,-0.5,nsumbins-0.5);
    for (iplane = 0; iplane < NPLANES; iplane++) {
      sprintf(title,"Arm %d Orient %d Plane %d",iarm,iorient,iplane);
      // book histos
      sprintf(id,"h2[%d]",iplane);
      h2[iplane] = new TH1F(id,title,nbins+1,-0.5,nbins+0.5);
      h2[iplane]->SetLineColor(histcolor[iplane]);
      // and fill them
      sprintf(plotstr,"nchan_plane[%d][%d]>>%s",ifem,iplane,id);
      //	cout << " plotstr " << plotstr << endl;
      tree->Draw(plotstr);
      //	h2[iplane]->Print();
      int ibin = iplane+1;
      hsummary->SetBinContent(ibin,h2[iplane]->GetMean());
      hsummary->SetBinError(ibin,h2[iplane]->GetRMS());
    } // iplane

    // do the plotting
    for (iplane = 0; iplane < NPLANES; iplane++) {
      c2->cd(iplane+1);
      h2[iplane]->DrawCopy("hist");
      // insert some text here too
      text->SetTextColor(histcolor[iplane]);
      sprintf(h1str,"Plane %d: Mean %3.2f",
	      iplane, h2[iplane]->GetMean());
      text->DrawText(20,2,h1str);  
    }
    c2->cd(6);
    hsummary->DrawCopy();
    c2->Update();
    for (iplane = 0; iplane < NPLANES; iplane++) {
      delete h2[iplane];
    }
    delete hsummary;

    sprintf(plotstr,"plot2_arm%d_orient%d_allpanels.gif",iarm,iorient);
    c2->SaveAs(plotstr);
  } // ifem

  return;
}