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T: Fachverband Teilchenphysik

T 71: Detectors VI (Gaseous Detectors)

T 71.3: Vortrag

Donnerstag, 3. April 2025, 16:45–17:00, VG 1.101

Effect of Different O₂ and H₂O Concentrations on MicroMegas Detector Performance in Ar-CO₂ Gas Mixtures at Various Drift Volumes — •Burkhard Böhm and Raimund Ströhmer — Universität Würzburg, Germany

In particle physics the MicroMegas detectors (MM), a prominent type of Micro-Pattern Gaseous Detectors (MPGDs), are used in several experiments. They are valued for their simple single-stage amplification and high and stable gain. However, their performance can be significantly affected by the composition of the gas mixture, including the contamination from ambient air. Since processes in multi-component gas mixtures can be highly complex, experimentally investigating the signal behavior at different levels of O₂, H₂O and their combination in an argon-based atmosphere is crucial.

To evaluate the effect of impurities in drift volume and amplification region separately, we performed studies with maximum drift distances from 5 mm to 2.5 mm. The aim is to determine the magnitude of electron attachment, a major factor in signal degradation, in the amplification stage and whether it can be mitigated by using a smaller drift volume.

Precise control of oxygen and water levels was achieved by introducing O₂ and humidified Ar-CO₂ into a resistive MM chamber. The resulting effects on gas gain, primarily due to electron attachment in the drift region, and the amplification of primary electrons were systematically studied. This research provides valuable insights into optimizing MPGDs performance in environments with varying gas impurities.

Keywords: Micro-Pattern Gaseous Detectors (MPGD); Micromegas; Drift Volume; Oxygen; Water