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.
	//      old walkcorrections 
	//	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)))";
	//	char *tn9 = "(tn9-(2.848297*exp(-0.010014*n9)+0.762059+(-0.001716*n9)))";
	//	char *ts9 = "(ts9-(2.648966*exp(-0.005678*s9)+0.286492+(-0.000976*s9)))";

	// newest WC
	char *tn7 = "(tn7-(3.318633*exp(-0.007758*n7)+-2.285192+(-0.000754*n7)))";
	char *ts7 = "(ts7-(2.209792*exp(-0.006442*s7)+-2.561431+(-0.000607*s7)))";
	char *tn8 = "(tn8-(2.512104*exp(-0.004475*n8)+-2.579980+(-0.000414*n8)))";
	char *ts8 = "(ts8-(2.396487*exp(-0.005468*s8)+-2.408689+(-0.000530*s8)))";
	char *tn9 = "(tn9-(3.379855*exp(-0.008501*n9)+-2.716681+(-0.001110*n9)))";
	char *ts9 = "(ts9-(3.284677*exp(-0.006599*s9)+-2.976956+(-0.000848*s9)))";


	// Create canvas with 2 pads, top for no timewalk correction, bottom corrected
	TCanvas *c1 = new TCanvas("c1","",600,800);
	c1->Divide(1,4);
	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 8 and tagger (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 8 and tagger (ns)");
	tdiff_vs_Ephoton_corr->SetXTitle("E_{#gamma} from tagger (MeV)");


	// Draw time difference between mean time of cell 7 and tagger
	// vs. photon energy without timewalk correction.
	c1->cd(1);
	bcal->Project("tdiff_vs_Ephoton", "(tn9+ts9)/2.0 + tphoton-531 :Ephoton", "Nphotons==1&&n9>200&&s9>200");
	tdiff_vs_Ephoton->Draw();
	
	// Draw time difference between mean time of cell 7 and tagger
	// vs. photon energy WITH timewalk corrections.
	c1->cd(2);
	char expr[512];
	sprintf(expr, "(%s+%s)/2.0 +tphoton-531:Ephoton", tn9, ts9);
	bcal->Project("tdiff_vs_Ephoton_corr", expr, "Nphotons==1&&n9>200&&s9>200");
	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, 1.0);
	axes->SetStats(0);
	axes->SetYTitle("#sigma of difference in mean times between cell 9 and tagger (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");
	

 
	c1->Update();
	
        c1->cd(4);

	//	TH2F *axes2 = new TH2F("axes2","#sigma_{#Deltat} vs. E_{#gamma}", 100, 150, 650, 100, 0.0, 1.0);
	//	axes2->SetStats(0);
	//	axes2->SetYTitle("#sigma of difference in mean times between cell 7 and tagger (ns)");
	//	axes2->SetXTitle("E_{#gamma} from tagger (MeV)");
	//	axes2->Draw();
	TH1D* tdiff_vs_Ephoton_corr_3 = (TH1D*)gROOT->FindObject("tdiff_vs_Ephoton_corr_2");

        tdiff_vs_Ephoton_corr_3->Draw("");
	TF1 *f1 = new TF1("f1","sqrt(([0]*1/sqrt(x/1000))^2 + ([1])^2)  ",150,650);  
	f1->SetParameters(0.2,0.2);  //initialize fit parameters
	
	tdiff_vs_Ephoton_corr_3->Fit("f1");
        tdiff_vs_Ephoton_corr_3->SetStats(1);
 


        //add resulting fit equation to plot
	double p0 = f1->GetParameter(0);
	double e0 = f1->GetParError(0);
	double p1 = f1->GetParameter(1);
	double e1 = f1->GetParError(1);
	double chi2 = f1->GetChisquare();
	double ndf = f1->GetNDF();
	char pictext[100];
	sprintf(pictext,"#frac{ %.3f #pm %.3f }{#sqrt{E}} #oplus ( %.3f #pm %.3f ) ",p0,e0,p1,e1);
	
	TLatex *l = new TLatex(200,0.3,pictext);
	l->SetTextSize(0.055);
	l->Draw();
	c1->Update();
	
	
	// Save to file
	c1->SaveAs("bcal_time_res_vs_Ephoton_9.gif");
}