Detection of high-frequency gravitational waves using SRF cavities

TL;DR

This paper discusses the development of superconducting radiofrequency cavities for detecting high-frequency gravitational waves in the 10 kHz to 100 MHz range, highlighting technical challenges and initial experimental results.

Contribution

It presents the design, environmental requirements, and initial testing of SRF cavities aimed at high-frequency GW detection, advancing experimental capabilities beyond current state-of-the-art.

Findings

Successful commissioning of a prototype cavity

Achievement of low-level RF system accuracy

First measurements demonstrating feasibility

Abstract

Today, apart from some isolated R&D efforts, there are no gravitational wave (GW) experiments, yet which explore a large part of the vast frequency range above the LIGO/Virgo band. It is planned to establish an experiment at Deutsches Elektronen-Synchrotron (DESY) and at the Superconducting Quantum Materials and Systems (SQMS) Center at Fermi National Accelerator Laboratory (Fermilab) to search for high-frequency GWs in the frequency range of 10 kHz to 100 MHz. The basic idea is to use superconducting radiofrequency (SRF) cavities to detect tiny harmonic deformations induced by GWs which change the boundary conditions of the oscillating electromagnetic field. This paper summarizes the challenging environmental boundary requirements, and the R&D to operate a cavity using a low level RF (LLRF) system which pushes beyond state-of-the-art accuracy and resolutions and a seismic noise mitigated cryostat at 1.8 K. The focus of this paper is the warm and cold commissioning of a prototype cavity, built 20 years ago during the MAGO collaboration, and its first measurement in our collaborative research project.