void timewalk_check_profile(void)
{

	TFile *f = new TFile("hd_root.root");
	
	TTree *tree = (TTree*)gROOT->FindObject("tree");

	TCanvas *c1 = new TCanvas("c1");
	c1->SetTicks();
	c1->SetGrid();
	
	TH2D *axes = new TH2D("axes","", 100, 0.0, 400.0, 100, -15.0, 15.0);
	axes->SetStats(0);
	axes->SetXTitle("fADC");
	axes->SetYTitle("t (ns)");
	
	// Open PDF file for plots
	c1->Print("timewalk_check_profile.ps[");

	// Loop over layers
	int Nlayers=0;
	for(int ilayer=1; ilayer<=10 ; ilayer++, Nlayers++){

		TProfile *hup = new TProfile("hup", "", 100, 0.0, 400.0);
		TProfile *hdn = new TProfile("hdn", "", 100, 0.0, 400.0);

		char cut_up[256];
		char cut_dn[256];
		sprintf(cut_up, "layer==%d && tup>0 && tup<100.0", ilayer);
		sprintf(cut_dn, "layer==%d && tdn>0 && tdn<100.0", ilayer);

		tree->Project("hup", "tup_corrected:fADC_up", cut_up);
		tree->Project("hdn", "tdn_corrected:fADC_dn", cut_dn);
	
		hup->SetLineColor(kCyan);
		hdn->SetLineColor(kMagenta);
		hup->SetLineWidth(2);
		hdn->SetLineWidth(2);

		char title[256];
		sprintf(title, "Timewalk Check for layer %d", ilayer);
		axes->SetTitle(title); 

		axes->Draw();
		tree->Draw("tup_corrected:fADC_up", cut_up, "same");
		tree->Draw("tdn_corrected:fADC_dn", cut_dn, "same");
		
		hup->Draw("same");
		hdn->Draw("same");
		
		c1->Update();
		c1.Print("timewalk_check_profile.ps");		
	}
	
	// Close PDF file 
	c1->Print("timewalk_check_profile.ps]");

	
	cout<<"Plots written to \"timewalk_check_profile.ps\". Convert to PDF with:"<<endl;
	cout<<endl;
	cout<<"  ps2pdf timewalk_check_profile.ps"<<endl;
	cout<<endl;
	cout<<"attempting to run for you ...."<<endl;
	system("ps2pdf timewalk_check_profile.ps");
	cout<<"Done."<<endl;
}