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T: Fachverband Teilchenphysik

T 53: Dark Matter II

T 53.9: Vortrag

Mittwoch, 1. April 2020, 18:30–18:45, H-HS XIV

Characterization of germanium detectors using positron emission tomography — •Lukas Rauscher, Josef Jochum, Katharina Kilgus, Ann-Kathrin Schütz, and Andreas Zschocke for the GERDA collaboration — Physikalisches Institut Tübingen, Auf der Morgenstelle 14, Tübingen, Deutschland

Pulse shape discrimination (PSD) in germanium detectors is an integral part of background reduction in several 0vbb experiments such as GERDA. The efficiency of the PSD can be cross-checked using positron emission tomography (PET), which is used for medical imaging. A PET detector is a segemented, cylindrical detector for photons originating from the annihilation of electron positron pairs. From the intensity distribution of the coincident photons the spatial distribution of the b+ emitter can be reconstructed. To characterize a germanium detector, it is irradiated with a collimated Ta-208 source generating electron positron pairs in the germanium detector. The free electron generates a pulse in the germanium detector and the positron annihilates with an electron of the bulk material generating a signal in two different pixels of the PET detector. Due to the short mean free path of the positron compared to the spatial resolution of the PET detector, the point of interaction can be fixed as the intersection of the incoming gamma beam with the connecting line of the two pixels. The pulse in the germanium detector can be mapped to the spatial position of its origin inside the germanium detector. In this talk the principle of the technique as well as first measurements regarding the functionality of the PET will be presented. This work is funded by the BMBF.