void lowTime() {
  gROOT->SetStyle("Plain");

  TCanvas *c1=new TCanvas("c1","Canvas",800,600);
  gStyle->SetOptStat(0);
  gStyle->SetPalette(1);

  TFile *f[4];
  f[0]=TFile::Open("S44_030mV.root");
  f[1]=TFile::Open("S36_030mV.root");
  f[2]=TFile::Open("S42_030mV.root");
  f[3]=TFile::Open("S23_030mV.root");

  for(unsigned i(0);i<4;i++) {
    f[i]->cd();

    QT->SetTitle(";Peak signal (mV);Signal rise time (ns)");
    QT->GetXaxis()->SetRangeUser(50,149);
    QT->GetYaxis()->SetRangeUser(0,199);
    //PeakSignal->GetYaxis()->SetTitleOffset(1.2);
    QT->Draw("colz");
    
    c1->Update();
    if(i==0) c1->Print("../lowTime0.png");
    if(i==1) c1->Print("../lowTime1.png");
    if(i==2) c1->Print("../lowTime2.png");
    if(i==3) c1->Print("../lowTime3.png");
  }
}