DMRadio-m$^3$ is an experiment that is designed to be sensitive to KSVZ and
DFSZ QCD axion models in the 10-200 MHz (41 neV$/c^2$ - 0.83 $\mu$eV/$c^2$)
range. The experiment uses a solenoidal dc ...magnetic field to convert an axion
dark-matter signal to an ac electromagnetic response in a coaxial copper
pickup. The current induced by this axion signal is measured by dc SQUIDs. In
this work, we present the electromagnetic modeling of the response of the
experiment to an axion signal over the full frequency range of DMRadio-m$^3$,
which extends from the low-frequency, lumped-element limit to a regime where
the axion Compton wavelength is only a factor of two larger than the detector
size. With these results, we determine the live time and sensitivity of the
experiment. The primary science goal of sensitivity to DFSZ axions across
30-200 MHz can be achieved with a $3\sigma$ live scan time of 3.7 years.
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).
The QCD axion is a leading dark matter candidate that emerges as part of the solution to the strong CP problem in the Standard Model. The coupling of the axion to photons is the most common ...experimental probe, but much parameter space remains unexplored. The coupling of the QCD axion to the Standard Model scales linearly with the axion mass; therefore, the highly-motivated region 0.4-120 neV, corresponding to a GUT-scale axion, is particularly difficult to reach. This paper presents the design requirements for a definitive search for GUT-scale axions and reviews the technological advances needed to enable this program.
The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with the design of numerous new detection strategies. Transformative advances in quantum ...technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies for ultralight (\(<10\,\)eV) bosonic dark matter that can be described by an oscillating classical, largely coherent field. This white paper focuses on searches for wavelike scalar and vector dark matter candidates.
In experiments searching for axionic dark matter, the use of the standard threshold-based data analysis discards valuable information. We present a Bayesian analysis framework that builds on an ...existing processing protocol to extract more information from the data of coherent axion detectors such as operating haloscopes. The analysis avoids logical subtleties that accompany the standard analysis framework and enables greater experimental flexibility on future data runs. Performing this analysis on the existing data from the HAYSTAC experiment, we find improved constraints on the axion-photon coupling \(g_\gamma\) while also identifying the most promising regions of parameter space within the \(23.15\)--\(24.0\) \(\mu\)eV mass range. A comparison with the standard threshold analysis suggests a \(36\%\) improvement in scan rate from our analysis, demonstrating the utility of this framework for future axion haloscope analyses.
In dark matter axion searches, quantum uncertainty manifests as a fundamental noise source, limiting the measurement of the quadrature observables used for detection. We use vacuum squeezing to ...circumvent the quantum limit in a search for a new particle. By preparing a microwave-frequency electromagnetic field in a squeezed state and near-noiselessly reading out only the squeezed quadrature, we double the search rate for axions over a mass range favored by recent theoretical projections. We observe no signature of dark matter axions in the combined \(16.96-17.12\) and \(17.14-17.28\space\mu\text{eV}/c^2\) mass window for axion-photon couplings above \(g_{\gamma} = 1.38\times g_{\gamma}^\text{KSVZ}\), reporting exclusion at the 90% level.
DMRadio-m\(^3\) is an experiment that is designed to be sensitive to KSVZ and DFSZ QCD axion models in the 10-200 MHz (41 neV\(/c^2\) - 0.83 \(\mu\)eV/\(c^2\)) range. The experiment uses a solenoidal ...dc magnetic field to convert an axion dark-matter signal to an ac electromagnetic response in a coaxial copper pickup. The current induced by this axion signal is measured by dc SQUIDs. In this work, we present the electromagnetic modeling of the response of the experiment to an axion signal over the full frequency range of DMRadio-m\(^3\), which extends from the low-frequency, lumped-element limit to a regime where the axion Compton wavelength is only a factor of two larger than the detector size. With these results, we determine the live time and sensitivity of the experiment. The primary science goal of sensitivity to DFSZ axions across 30-200 MHz can be achieved with a \(3\sigma\) live scan time of 3.7 years.
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).
We report on the results from a search for dark matter axions with the HAYSTAC experiment using a microwave cavity detector at frequencies between 5.6-5.8\(\, \rm Ghz\). We exclude axion models with ...two photon coupling \(g_{a\gamma\gamma}\,\gtrsim\,2\times10^{-14}\,\rm GeV^{-1}\), a factor of 2.7 above the benchmark KSVZ model over the mass range 23.15$\,<\,$$m_a \,\(<\)\,\(24.0\)\,\mu\rm eV\(. This doubles the range reported in our previous paper. We achieve a near-quantum-limited sensitivity by operating at a temperature \)T<h\nu/2k_B$ and incorporating a Josephson parametric amplifier (JPA), with improvements in the cooling of the cavity further reducing the experiment's system noise temperature to only twice the Standard Quantum Limit at its operational frequency, an order of magnitude better than any other dark matter microwave cavity experiment to date. This result concludes the first phase of the HAYSTAC program utilizing a conventional copper cavity and a single JPA.
We describe a dark matter axion detector designed, constructed, and operated both as an innovation platform for new cavity and amplifier technologies and as a data pathfinder in the \(5 - 25\) GHz ...range (\(\sim20-100\: \mu\)eV). The platform is small but flexible to facilitate the development of new microwave cavity and amplifier concepts in an operational environment. The experiment has recently completed its first data production; it is the first microwave cavity axion search to deploy a Josephson parametric amplifier and a dilution refrigerator to achieve near-quantum limited performance.
