Identification and simulation of surface alpha events on passivated surfaces of germanium detectors and the influence of metalisation

Events from alpha interactions on the surfaces of germanium detectors are a major contribution to the background in germanium-based searches for neutrinoless double-beta decay. Surface events are subject to charge trapping, affecting their pulse shape and reconstructed energy. A study of alpha event...

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Bibliographic Details
Published in:arXiv.org 2022-06
Main Authors: Abt, Iris, Gooch, Christopher, Hagemann, Felix, Hauertmann, Lukas, Liu, Xiang, Schulz, Oliver, Schuster, Martin, Zsigmond, Anna Julia
Format: Article
Language:English
Subjects:
Beta decay
Detectors
End plates
Germanium
Pulse shape
Trapping
Online Access:Get full text
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Summary:Events from alpha interactions on the surfaces of germanium detectors are a major contribution to the background in germanium-based searches for neutrinoless double-beta decay. Surface events are subject to charge trapping, affecting their pulse shape and reconstructed energy. A study of alpha events on the passivated end-plate of a segmented true-coaxial n-type high-purity germanium detector is presented. Charge trapping is analysed in detail and an existing pulse-shape analysis technique to identify alpha events is verified with mirror pulses observed in the non-collecting channels of the segmented test detector. The observed radial dependence of charge trapping confirms previous results. A dependence of the probability of charge trapping on the crystal axes is observed for the first time. A first model to describe charge trapping effects within the framework of the simulation software SolidStateDetectors.jl is introduced. The influence of metalisation on events from low-energy gamma interactions close to the passivated surface is also presented.
ISSN:2331-8422
DOI:10.48550/arxiv.2206.15265