Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 13: Semiconductor Detectors:Radiation Hardness, new Materials and Concepts

T 13.2: Vortrag

Montag, 21. März 2022, 16:30–16:45, T-H26

Voltage scans on germanium detectors — •Felix Hagemann for the GeDet collaboration — Max-Planck-Institut für Physik, München

Germanium detectors are used in fundamental research to search for neutrinoless double-beta decay or dark matter. In many of these experiments, a perfect understanding of the working principle and characteristics of these detectors is essential.

The electric field inside a germanium detector consists of two main components: one resulting from the potentials applied to the contacts to bias the detector, and one from the ionized impurities in the germanium crystal. While the overall number of ionized impurities can be estimated from Hall measurements on the surface of the detector, the spatial distribution of the impurities inside the germanium crystal is not well known. This results in large uncertainties on the resulting electric field.

One way to probe the impurity density profile is through voltage scans. In voltage scans, the pulses resulting from the same volumes of the detectors are recorded with different bias voltages applied to the detector. This way, the contribution from the bias voltage is varied and the constant contribution from the impurities can be separated and determined. This also requires reliable pulse shape simulation.

In my talk, I will present first data from voltage scans on a p-type segmented point-contact germanium detector and compare them to simulation results obtained from the open-source Julia software package SolidStateDetectors.jl to give an estimate of the impurity density profile.