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Abstract

Liquefied xenon (LXe) is a popular detection medium for experiments searching
for rare interactions proposed by beyond the Standard Model theories. It is
employed in dual-phase time projection chambers (TPCs) used by experiments
such as XENON1T, which attempt to measure particle dark matter interactions
as well as the neutrinoless double-beta decay. A precise understanding of the
processes behind the signals of such detectors is necessary to discriminate between
background and signal events as well as possible.
This work presents analyses regarding LXe TPCs physics. In the first part, the
temporal evolution of electric noise in the XENON1T experiment is examined.
Furthermore, a selection criterion, which has been developed to exclude interactions
happening in the TPC’s gas phase, is extended to higher energy scales.
Finally, it is investigated whether the LXe scintillation pulse shape allows to
discriminate between nuclear recoils and background electronic recoils which
originate from decays in or on TPC reflector panels. The pulse shape is also
the topic of the second and final part. There, its electric field strength dependence
is measured, using the TPC of the HeidelbergXenon (HeXe) system, for
conversion electrons coming from ^83mKr decays as well as for alpha-particles from
decays of ²²²Rn and daughters.