LegendSpecFits.jl

LegendSpecFits.jl is a Julia package for fitting spectra and calibrating the energy and pulse-shape parameters of high-purity germanium (HPGe) and silicon photomultiplier (SiPM) detectors of the LEGEND experiment. It is part of the LEGEND Julia analysis software and is called by the production dataflow (Juleana.jl) as well as in interactive analyses.

The package provides binned maximum-likelihood fits of gamma lines and other distributions, calibration curves and energy resolution curves, charge-trapping corrections, A/E and late-charge (LQ) pulse-shape cuts together with their survival fractions, energy filter optimization, and SiPM calibration. Most fit functions return their numerical results together with a report that LegendMakie.jl turns into figures.

Installation

LegendSpecFits.jl is registered in the LEGEND Julia registry. After adding the registry once, the package can be installed with the Julia package manager:

using Pkg
pkg"registry add General https://github.com/legend-exp/LegendJuliaRegistry.git"
Pkg.add("LegendSpecFits")

To work on the package itself, use Pkg.develop("LegendSpecFits").

Overview

The manual pages describe the concepts and the workflow of each part of the package:

• Conventions describes what all fit functions have in common: the (result, report) return pair, units, uncertainties, expression strings and plotting.
• Energy Calibration covers the HPGe calibration chain from the first rough calibration to the calibration curve and the energy resolution curve.
• Charge-Trapping Correction corrects the energy for incomplete charge collection using the drift-time proxy qdrift.
• Peak Shapes and Likelihoods lists the peak models and the likelihood and prior functions used by the fits.
• A/E Pulse-Shape Discrimination, LQ Cut and Cuts and Goodness of Fit cover pulse-shape cuts, survival fractions, simple quality cuts and goodness-of-fit measures.
• Filter Optimization covers the choice of energy filter parameters from the electronic noise and the resolution.
• SiPM Calibration covers the calibration of SiPM spectra.

The tutorials run complete analyses on synthetic data. The API page lists all documented functions and types.

Related Packages

• LegendMakie.jl provides the plot recipes (lplot) that draw the reports returned by the fit functions.
• LegendDataManagement.jl reads LEGEND data and metadata and evaluates the expression strings that the fit functions return (ljl_propfunc).
• RadiationSpectra.jl provides the peak finder used for the first calibration.
• BAT.jl provides the distribution transforms and the optimization interface behind the likelihood fits.
• Juleana.jl is the production dataflow that applies the functions of this package to LEGEND data.