Search for Dark Matter Axions with a Dielectric Haloscope: Data Acquisition and first Physics Results on the Road towards the future MADMAX Experiment

• Applicant: Professor Dr. Alexander Schmidt
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields ; Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550641633

The absence of charge-parity (CP) violation in the strong interaction, and the question about the nature of Dark Matter are both among the most important unsolved mysteries of modern physics. Both problems might be answered by the Axion solution which was proposed by Roberto Peccei, Helen Quinn and Frank Wilczek in the 1970s. The experimental concept of Axion haloscopes has been proposed by Pierre Sikivie as the most promising candidate to find Axion Dark Matter in the relevant mass range. Axion haloscopes search for Dark Matter in the galactic halo. The only experiment which was able to probe a relevant parameter space of Axion Dark Matter is the ADMX experiment. However ADMX is limited to a very narrow mass range. To overcome the limitations of ADMX, the concept of dielectric haloscopes has been proposed. The MADMAX collaboration plans to implement and operate a dielectric haloscope for the first time. The MADMAX experiment will consist of several (up to 80) thin dielectric disks, each a few millimeters thick, each covering an area of around 1 square Meter. The disks will be located inside a strong (10 Tesla) magnetic dipole field. The field is parallel to the surfaces of the disks where the interaction of the Axion field with the magnetic field takes place, resulting in the emission of microwave radiation perpendicular to the disk surfaces. By superimposing the emissions from several planes, constructive interference as well as resonant enhancement can be achieved, which leads to an amplification of the Axion signal. The frequency of the enhancement depends on the distances between the disks. The disk positions will be adjustable as desired, using a precision mechanics system. A large frequency range can be scanned by continuously adjusting the disk positions. In the proposed project the first searches for Dark Matter Axion-like particles (ALPs) will be performed with prototypes for dielectric haloscopes. The goal is to obtain the world's best limits in the Axion (ALP) parameter space in the region with an Axion mass around 100 Microelectronvolt. To achieve this goal, two major components of the prototypes will be developed in this project: the receiver / data acquisition system and the disk positioning strategy. The developed components will be integrated in the MADMAX prototypes and several months of data-taking campaigns will be conducted, followed by data analysis and publication. We expect to achieve the world's most stringent limits on Axion Dark Matter in the specified mass range.

• DFG Programme: Research Grants