Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 11: Gaseous Detectors

T 11.8: Vortrag

Montag, 21. März 2022, 18:00–18:15, T-H24

A GridPix detector for IAXO — •Tobias Schiffer, Klaus Desch, Jochen Kaminski, Sebastian Schmidt, and Markus Gruber — Physikalisches Institut der Universität Bonn

In the scope of the search for axions with helioscopes, like the International Axion Observatory (IAXO) and its precursor BabyIAXO, detectors capable of measuring low energy X-rays down to the 200 eV range are necessary. For this purpose the GridPix detector, which was already successfully used at CAST, is an appropriate and constantly evolving solution.

The GridPix is a MicroMegas like readout consisting of a pixelized readout ASIC (Timepix/Timepix3) with a perfectly aligned gas amplification stage on top. Due to the very high granularity this detector is capable of detecting single electrons allowing the measurement of low energy X-rays. To convert these X-rays into electrons a gas volume is built above the readout sealed with a vacuum tight X-ray entrance window.

For the goals of IAXO and BabyIAXO a very low detector background needs to be achieved, therefore only a few radiopure materials are contemplable. Also a good offline separation of signal and background events is to be achieved, here the insights from the CAST detector are used. Further, to get more signal the X-ray entrance window needs to be as transparent as possible for the low energy X-rays. This is achieved with an ultra thin (<200 nm) silicon nitride membrane.

The challenges of the design process and some first results of the detector will be presented.