MADMAX: A Dielectric Haloscope Experiment

Xiaoyue Li

doi:10.1088/1742-6596/1468/1/012062

Abstract

Axions emerge naturally from the Peccei-Quinn mechanism, which addresses the absence of CP violation in the strong interaction, and they can make up the cold dark matter (CDM) in the universe. If PQ symmetry was broken after inflation, the CDM axion mass would likely be in the range of ˜ 26 μeV to ˜ 1 meV, which is yet to be explored experimentally. We present a new dielectric haloscope experiment dedicated to the direct detection of QCD axion dark matter in the mass range of 40 to 400 μeV – the MAgnetized Disc and Mirror Axion eXperiment (MADMAX). Multiple dielectric discs and a mirror are placed in a strong magnetic field to utilize the axion-induced coherent electromagnetic wave emitted from each disc surface and the resonance effect therein, such that the axion-induced signal can be boosted to a level detectable by state-of-the-art low noise amplifiers. We will discuss the motivation, design and sensitivity of MADMAX; ongoing R&D studies and the project roadmap will also be presented.

Highlights

The axion arises from the Peccei-Quinn (PQ) mechanism [1], whereby a new global chiral U(1)symmetry is introduced, and is broken spontaneously at the PQ scale fa; the axion emerges as a pseudo Goldstone boson
Axions emerge naturally from the Peccei-Quinn mechanism, which addresses the absence of CP violation in the strong interaction, and they can make up the cold dark matter (CDM) in the universe
If PQ symmetry was broken after inflation, the CDM axion mass would likely be in the range of ∼ 26 μeV to ∼ 1 meV, which is yet to be explored experimentally

Summary

Introduction

The axion arises from the Peccei-Quinn (PQ) mechanism [1], whereby a new global chiral U(1). If the PQ symmetry breaking happened after inflation, the prediction of ma is much more difficult as the relic axion CDM density is given by the averaged vacuum realignment mechanism, and affected by cosmic strings and domain walls associated with the patchy structure of the axion field. In the case of a single metallic mirror with area A placed in a vacuum with a magnetic field parallel to the mirror surface, the power emitted at the boundary is. Booster simulation Simulations have been performed to factor in 3D effects including moding, disc tilting, surface roughness and antenna coupling loss [9]. It is estimated that for the configuration shown, the disc tilting should be limited to 0.1 milliradian, surface roughness < 10 μm, and dielectric loss tan δ < a few×10−5

Proof-of-principle setup and measurements

Findings

Receiver