Projected Sensitivity of DMRadio-m$^3$: A Search for the QCD Axion Below $1\,\mu$eV

TL;DR

DMRadio-m$^3$ is a next-generation experiment designed to detect QCD axion dark matter below 1 microelectronvolt using a high magnetic field and sensitive readout, aiming to explore new parameter space.

Contribution

This paper presents the design and projected sensitivity of DMRadio-m$^3$, a novel experimental setup targeting axion masses below 1 microelectronvolt, extending current search capabilities.

Findings

Designed to cover 20 neV to 800 neV axion mass range.

Aims to reach DFSZ sensitivity above 120 neV.

Secondary goal to probe KSVZ axions down to 40 neV.

Abstract

The QCD axion is one of the most compelling candidates to explain the dark matter abundance of the universe. With its extremely small mass ($\ll 1\,\mathrm{eV}/c^2$), axion dark matter interacts as a classical field rather than a particle. Its coupling to photons leads to a modification of Maxwell's equations that can be measured with extremely sensitive readout circuits. DMRadio-m$^3$ is a next-generation search for axion dark matter below $1\,\mu$eV using a $>4$ T static magnetic field, a coaxial inductive pickup, a tunable LC resonator, and a DC-SQUID readout. It is designed to search for QCD axion dark matter over the range $20\,\mathrm{neV}\lesssim m_ac^2\lesssim 800\,\mathrm{neV}$ ($5\,\mathrm{MHz}<\nu<200\,\mathrm{MHz}$). The primary science goal aims to achieve DFSZ sensitivity above $m_ac^2\approx 120$ neV (30 MHz), with a secondary science goal of probing KSVZ axions down to $m_ac^2\approx40\,\mathrm{neV}$ (10 MHz).