The search for 0nbb decay with the GERDA experiment: status and prospects

TL;DR

The GERDA experiment searches for neutrinoless double beta decay in germanium-76, achieving significant background reduction and setting new limits, with ongoing improvements to enhance sensitivity and detection capabilities.

Contribution

This paper reports the current status, background modeling, and initial results of the GERDA experiment, including the implementation of a liquid argon veto for background suppression.

Findings

Half-life limit of > 2.1×10^25 years for 0νββ decay

Effective background reduction with liquid argon veto

First calibration spectra demonstrating veto performance

Abstract

The GERDA experiment is designed to search for neutrinoless double beta decay of 76Ge using HPGe detectors directly immersed into liquid argon. In its first phase the GERDA experiment has yielded a half life limit on this decay of T_1/2 > 2.1*10^25 yr. A background model has been developed. It explains the measured spectrum well, taking into account only components with distances to the detectors less then 2 cm. Competitive limits on Majoron accompanied double beta decay have been derived. Phase II of the experiment, now with additional liquid argon veto installed, is presently starting its commissioning phase. First commissioning spectra from calibration measurements are shown, proving that the liquid argon veto leads to a significant reduction of background events.