Liquid argon light collection and veto modeling in GERDA Phase II

Area of Science:

• Nuclear physics
• Particle physics
• Experimental physics

Background:

• The search for neutrinoless double beta decay (0νββ) requires extremely low background rates.
• The Gerda experiment utilized a high-purity germanium detector array immersed in liquid argon.
• Detecting scintillation light in liquid argon is key to background identification and rejection.

Purpose of the Study:

• To develop and validate a model for liquid argon scintillation light propagation in the Gerda experiment.
• To understand the light detection system's efficiency and spatial response.
• To improve the accuracy of background predictions for 0νββ decay searches.

Main Methods:

• Monte Carlo simulations were employed to model light propagation.
• Calibration data from the Gerda experiment were used to constrain the simulation parameters.
• The model was applied to analyze the background decomposition within the detector.

Main Results:

• A robust model of the Gerda liquid argon veto's light propagation was established.
• The model accurately describes light detection from various points within the liquid argon.
• The model provides insights into the background rejection capabilities of the experimental setup.

Conclusions:

• Accurate modeling of scintillation light is essential for precise background analysis in 0νββ decay experiments.
• The developed model enhances the Gerda experiment's ability to interpret background events.
• This work contributes to the ongoing search for neutrinoless double beta decay.