SiPM calibration

The threshold and the photoelectron calibration of a SiPM channel, on a random amplitude spectrum of five photoelectron peaks over a background.

using CairoMakie, LegendMakie
using LegendSpecFits, Unitful

Threshold

fit_sipm_threshold fits the noise peak of the amplitudes; the report shows the fit and the threshold derived from it.

result_thres, report_thres = fit_sipm_threshold(randn(100_000), -5.0, 5.0)
lplot(report_thres, title = "SiPM threshold")

Simple calibration

sipm_simple_calibration finds the photoelectron peaks in the amplitude spectrum. The report shows the uncalibrated and the calibrated spectrum with the peaks and the noise cut.

e_uncal = vcat([randn(round(Int, exp10(6 - 0.5 * i))) .* 0.3 .+ i * 1.4 for i in 1:5]..., randn(10_000) .* 1.5 .+ 6)
result_simple, report_simple = sipm_simple_calibration(e_uncal, n_fwhm_noise_cut = 0.0)
lplot(report_simple, title = "SiPM peak search")

Spectrum fit

fit_sipm_spectrum fits the calibrated spectrum with a mixture of Gaussians; the report shows the mixture, its components, the peaks assigned to photoelectron numbers, and the residuals.

result_fit, report_fit = fit_sipm_spectrum(result_simple.pe_simple_cal, 0.5, 4.5, n_mixtures = 8, Δpe_peak_assignment = 0.5)
lplot(report_fit, xerrscaling = 5, title = "SiPM spectrum fit")

Calibration curve

The fitted peak positions against the photoelectron numbers.

result_calib, report_calib = fit_calibration(1, result_fit.positions, collect(result_fit.peaks) * u"eV/V")
lplot(report_calib, xerrscaling = 5, title = "SiPM calibration")

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