Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 70: Searches for Dark Matter II

T 70.7: Talk

Wednesday, March 17, 2021, 17:30–17:45, Tt

Characterisation of dielectric materials for the MADMAX booster. — •Dominik Breitmoser for the MADMAX collaboration — Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Deutschland

The axion is a hypothetical low mass particle which is a prominent candidate for cold dark matter. The MAgentized Disc and Mirror Axion eXperiment is an experiment designed for its detection. MADMAX utilizes the axion photon conversion at dielectric surfaces in a strong magnetic field. Through constructive interference and resonance effects, the combination of several dielectric disks can boost the axion photon conversion sufficiently to make it detectable, requiring a material with high dielectric constant ε and low dielectric losses.

One of the favoured materials is Lanthanum Aluminate with ε≈24 available in small wafers. The MADMAX dielectric disks need to have a size of 1.25 m in diameter (0.3 m for the prototype). Thus, the disks need to be glued from hexagonal tiles using a cryo-compatible adhesive like Stycast Blue. Characterisation of these materials is performed by measurements with a Split-Post Dielectric Resonator in a cryostat at 10 GHz.

In this talk, this technique and its limitations are explained. Results of the dielectric loss and ε for these materials at several temperatures will be shown.