# Characterization of 30 $^{76}$Ge enriched Broad Energy Ge detectors for GERDA Phase II

## TL;DR

This paper details the characterization and performance of 30 new Broad Energy Germanium detectors used in GERDA Phase II, enhancing background discrimination and energy resolution for neutrinoless double beta decay searches.

## Contribution

It provides a comprehensive analysis of the properties and performance of BEGe detectors in a low-background environment, supporting improved experimental results.

## Key findings

- Detectors exhibited improved energy resolution.
- Characterization data informed GERDA Phase II analyses.
- Pulse shape simulations were validated against measurements.

## Abstract

The GERmanium Detector Array (GERDA) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double beta decay of $^{76}$Ge into $^{76}$Se+2e$^-$. GERDA has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new Ge detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the HADES underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for GERDA Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the strength of pulse shape simulation codes.