I am running into some problems when calibrating raw ADC channel data. Here is the code I use:
TFile *rawhists = new TFile("/not_backed_up/user/paddy/KURF_LBC/scripts/rawhists.root");
TFile *calhists = new TFile("/not_backed_up/user/paddy/KURF_LBC/scripts/calhists.root", "recreate");
rawhists->cd();
TH1F *Sample_hist = (TH1F*)rawhists->Get("Sample_hist");
TH1F *BG_hist = (TH1F*)rawhists->Get("BG_hist");
Int_t numbins = Sample_hist->GetXaxis()->GetNbins();
MAXE = numbins*numbins*A + numbins*B + C;
MAXE_bg = numbins*numbins*A_bg + numbins*B_bg + C_bg;
TH1F *Sample_hist_calib = new TH1F(calib_histname_sample, "Calibrated Sample Spectrum", histbins, 0, MAXE);
TH1F *BG_hist_calib = new TH1F(calib_histname_bg, "Calibrated Background Spectrum", histbins, 0, MAXE_bg);
for (int i=1;i<=numbins;i++) {
Double_t Cts_s = Sample_hist->GetBinContent(i);
Double_t bin_s = Sample_hist->GetXaxis()->GetBinCenter(i);
Double_t bin_bg = BG_hist->GetXaxis()->GetBinCenter(i);
Double_t Cts_bg = BG_hist->GetBinContent(i);
Double_t E_s = A*bin_s*bin_s + B*bin_s + C;
Double_t E_bg = A_bg*bin_bg*bin_bg + B_bg*bin_bg + C_bg;
BG_hist_calib->Fill(E_bg, Cts_bg);
Sample_hist_calib->Fill(E_s,Cts_s);
}
I get the A,B, and C parameters from another function that calibrates the spectrum for me.
THE PROBLEM I am running into is that when I draw the calibrated histogram, it looks like some bins are not getting filled in the calibrated histogram. I think this is a rounding error of some sort, but I’m not sure. If you want to see what it looks like go here:
You can see that there are bins with 0 content in them. It looks like they are spaced evenly, but they are not.
Does anyone know a better way to calibrate a histogram without seeing this?
Thanks!
- Paddy