Calibration of the GERDA experiment

TL;DR

This paper details the calibration process and data analysis methods used in the GERDA experiment to ensure precise energy resolution for detecting neutrinoless double-beta decay in germanium detectors.

Contribution

It presents a comprehensive calibration procedure and data analysis approach that maintains high energy resolution over several years of data collection.

Findings

Energy resolution and stability were effectively monitored over time.

Calibration preserved detector resolution across the full dataset.

Method ensures accurate energy reconstruction for rare decay searches.

Abstract

The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-$\beta$ decay in $^{76}$Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at Q$_{\beta\beta}$ = 2039.061(7)keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double-$\beta$ decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular $^{228}$Th calibrations. In this work, we describe the calibration process and associated data analysis of the full GERDA dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years.