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arXiv · 2206.15265

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

Iris Abt·Christopher Gooch·Felix Hagemann·Lukas Hauertmann·Xiang Liu·Oliver Schulz·Martin Schuster·Anna Julia Zsigmond
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Abstract

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.

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Iris Abt, Christopher Gooch, Felix Hagemann, Lukas Hauertmann, Xiang Liu, Oliver Schulz, Martin Schuster, Anna Julia Zsigmond. 2022-06-30. Identification and simulation of surface alpha events on passivated surfaces of germanium detectors and the influence of metalisation. https://doi.org/10.1140/epjc%2Fs10052-022-11064-8

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