Spectrum Calibration

The function RadiationSpectra.calibrate_spectrum return a calibrated spectrum of an uncalibrated one. As input it needs the uncalibrated spectrum (StatsBase::Histogram) and a Vector of known peak positions like photon lines.

The calibration is based on the assumption that the calibration function is just $f(x) = c\cdot x$.

using Plots, RadiationSpectra

h_uncal = RadiationSpectra.get_example_spectrum()
photon_lines = [609.312, 911.204, 1120.287, 1460.830, 1764.494] # keV
h_cal, h_deconv, peakPositions, threshold, c, c_precal = RadiationSpectra.calibrate_spectrum(h_uncal, photon_lines)

p_uncal = plot(h_uncal, st=:step, label="Uncalibrated spectrum");
p_deconv = plot(h_deconv, st=:step, label = "Deconvoluted spectrum");
hline!([threshold], label = "threshold", lw = 1.5);
p_cal = plot(h_cal, st=:step, label="Calibrated spectrum", xlabel="E / keV");
vline!(photon_lines, lw=0.5, color=:red, label="Photon lines");
plot(p_uncal, p_deconv, p_cal, size=(800,700), layout=(3, 1));

┌ Warning: Could not find enough peaks in the spectrum.
└ @ RadiationSpectra ~/work/RadiationSpectra.jl/RadiationSpectra.jl/src/AutoCalibration/AutoCalibration.jl:139

Zoom into one of the peaks:

Algorithm

1. Deconvolution -> Peak finding
2. Peak Identification - Which peak corresponds to which photon line?
3. Fit identified peaks
4. Fit determined peak positions vs 'true' positions (photon lines) to get the calibration constant $c$.