München 2019 – wissenschaftliches Programm
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SYMD: Symposium SMuK Dissertationspreis 2019
SYMD 1: SMuK Dissertationspreis 2019
SYMD 1.3: Hauptvortrag
Montag, 18. März 2019, 15:00–15:30, Plenarsaal
Search for solar chameleons with an InGrid based X-ray detector at the CAST experiment — •Christoph Krieger — Universität Bonn, Physikalisches Institut — Universität Hamburg, Institut für Experimentalphysik
The chameleon arises from a possible explanation for dark energy through modification of General Relativity. It features an effective mass depending on the local energy density, caused by the chameleon screening mechanism which is used to avoid unnatural effects.
As chameleons feature an effective coupling to photons, they can be produced by converting photons inside strong electromagnetic fields through the Primakoff effect similar to axions. This makes the Sun a chameleon source and allows us to use an axion helioscope like the CERN Axion Solar Telescope (CAST) to search for solar chameleons given X-ray detectors sensitive in the energy range below 2 keV.
Such an X-ray detector was build based on the InGrid technology, a Micromegas stage created on top of a pixelized readout ASIC through photolithographic postprocessing techniques. It reaches sensitivity down to the carbon Kα line at 277 eV and features a background rate of less than 10−4 /keV/cm2/s below 2 keV. This was achieved through application of a topological background suppression method.
In October 2014 the detector was mounted at CAST behind an X-ray telescope and took data until the end of 2015. The search led to the world-best limit on the chameleon-photon coupling βγ< 5.7×1010.