void time_res(void)
{
	gROOT->Reset();
	
	// Timewalk corrections. These were obtained by running the 
	// timewalk.C macro and copying the last few lines that
	// printed to stdout.
	char *tn7 = "(tn7-(3.331473*exp(-0.006549*n7)+0.773828+(-0.000631*n7)))";
	char *tn8 = "(tn8-(2.421650*exp(-0.005287*n8)+0.410419+(-0.000499*n8)))";
	char *ts7 = "(ts7-(3.248674*exp(-0.006659*s7)+0.563583+(-0.000647*s7)))";
	char *ts8 = "(ts8-(2.566994*exp(-0.005763*s8)+0.494722+(-0.000601*s8)))";

	// Create canvas with 2 pads, top for no timewalk correction, bottom corrected
	TCanvas *c1 = new TCanvas("c1","",600,800);
	c1->Divide(1,3);
	for(int i=1; i<=3; i++){
		c1->GetPad(i)->SetTickx();
		c1->GetPad(i)->SetTicky();
	}

	// Get pointer to bcal TTree
	TTree *bcal = (TTree*)gROOT->FindObject("bcal");

	// Make histograms to hold time diff vs. photon energy plot
	TH2F *tdiff_vs_Ephoton = new TH2F("tdiff_vs_Ephoton", "#Deltat vs. Ephoton", 100, 150.0, 650.0, 100, -10.0, 10.0);
	TH2F *tdiff_vs_Ephoton_corr = new TH2F("tdiff_vs_Ephoton_corr", "#Deltat vs. Ephoton timewalk corrected", 100, 150.0, 650.0, 100, -10.0, 10.0);

	// Set labels and turn off stats for pretty plotting
	tdiff_vs_Ephoton->SetStats(0);
	tdiff_vs_Ephoton->SetYTitle("Difference in mean times between cell 7 and cell 8 (ns)");
	tdiff_vs_Ephoton->SetXTitle("E_{#gamma} from tagger (MeV)");
	tdiff_vs_Ephoton_corr->SetStats(0);
	tdiff_vs_Ephoton_corr->SetYTitle("Difference in mean times between cell 7 and cell 8 (ns)");
	tdiff_vs_Ephoton_corr->SetXTitle("E_{#gamma} from tagger (MeV)");


	// Draw time difference between mean time of cell 7 and cell 8
	// vs. photon energy without timewalk correction.
	c1->cd(1);
	bcal->Project("tdiff_vs_Ephoton", "(tn8+ts8)/2.0 - (tn7+ts7)/2.0:Ephoton", "Nphotons==1");
	tdiff_vs_Ephoton->Draw();
	
	// Draw time difference between mean time of cell 7 and cell 8
	// vs. photon energy WITH timewalk corrections.
	c1->cd(2);
	char expr[512];
	sprintf(expr, "(%s+%s)/2.0 - (%s+%s)/2.0:Ephoton", tn8, ts8, tn7, ts7);
	bcal->Project("tdiff_vs_Ephoton_corr", expr, "Nphotons==1");
	tdiff_vs_Ephoton_corr->SetMarkerColor(kRed);
	tdiff_vs_Ephoton_corr->Draw();
	
	// Fit slices of both the corrected and uncorrected histograms
	// and plot the sigmas vs. photon energy to see the improvement.
	tdiff_vs_Ephoton->FitSlicesY();
	tdiff_vs_Ephoton_corr->FitSlicesY();
	TH1D* tdiff_vs_Ephoton_2 = (TH1D*)gROOT->FindObject("tdiff_vs_Ephoton_2");
	TH1D* tdiff_vs_Ephoton_corr_2 = (TH1D*)gROOT->FindObject("tdiff_vs_Ephoton_corr_2");

	c1->cd(3);
	TH2F *axes = new TH2F("axes","#sigma_{#Deltat} vs. E_{#gamma}", 100, 150, 650, 100, 0.0, 1.5);
	axes->SetStats(0);
	axes->SetYTitle("#sigma of difference in mean times between cell 7 and cell 8 (ns)");
	axes->SetXTitle("E_{#gamma} from tagger (MeV)");
	axes->Draw();
	tdiff_vs_Ephoton_2->Draw("same");
	tdiff_vs_Ephoton_corr_2->SetMarkerColor(kRed);
	tdiff_vs_Ephoton_corr_2->SetLineColor(kRed);
	tdiff_vs_Ephoton_corr_2->Draw("same");
	
	// Save to file
	c1->SaveAs("bcal_time_res_vs_Ephoton.gif");
}