Session K19: Searches for Low Mass Axion Dark Matter

Live

The particle nature of Dark Matter (DM) is one of the most important open questions in particle physics today. Axions, and axion like particles (ALPs), more generally, have emerged as one of the leading candidates to to explain the DM abundance of the universe. Experimental searches for axion DM (aDM) have traditionally searched in a narrow mass band between 1$\sim$100 $\mu$eV using microwave cavity detectors. However, recent work has demonstrated a powerful new approach to search for aDM with mass <1$\mu$eV using a lumped element detector. DMRadio is a multiphase program to search for aDM with mass below 1 $\mu$eV. The first stage, DMRadio-50L is a toroidal detector with a 0.1-1 T magnetic field that will be able to probe aDM over the range $20\,{\rm peV} < m_a < 20\,{\rm neV}$ down to $g_{a\gamma\gamma}\sim5 \times 10^{-15}\,\mathrm{GeV}$. The second stage, DMRadio-m$^3$, will have a $\sim4$ T field and will be sensitive to aDM in the QCD axion band from $20\,\mathrm{neV} < m_a < 0.8\,\mu\mathrm{eV}$. In this talk, I will give an overview of the DMRadio program, design considerations, and challenges.   

Live

The presence of dark matter provides some of the most tangible evidence for the existence of physics beyond the Standard Model. One compelling dark matter candidate is the axion, a light boson that was originally postulated as a solution to another outstanding issue, the strong CP problem in QCD. ABRACADABRA-10cm is a demonstrator for lumped element searches for sub-$\mu$eV axion and axion-like dark matter, which look for axion-induced modifications to Maxwell’s equations using a strong magnetic field and quantum electronics. This talk presents recent results from this prototype detector, as well as its current status and plans for the future.   

Live

Axions are a well-motivated dark matter candidate, which currently have a wide open and accessible parameter space, with few constraints on their mass and coupling strength to photons. The DM Radio-50L experiment seeks to explore a wide portion of this axion parameter space (between 5 kHz - 5 MHz), taking advantage of lumped element high-Q resonators with optimal out-of-band sensitivity. DM Radio-50L will utilize a torrorial magnet with a field strength of at least 100 mT, with a design sensitivity goal of reaching at least $g_{a\gamma\gamma}\sim 5 \times 10^{-15}\,\mathrm{GeV^{-1}}$ across the entire region of interest. At the same time, the lessons learned from the construction of this experiment will inform the design of the future DM Radio-$m^3$ experiment. In this talk, we will present an overview of the current status of the DM Radio-50L experiment as well as current efforts to optimize the design in order to reach the above science goals.   

Live

DMRadio-50L is a next generation experiment designed to search for axions and dark photons in the kHz - MHz range using high Q ($\sim10^6$) lumped element LC resonators. In this frequency range, resonant cavities used in conventional haloscope experiments are impractical. Lumped element circuits, however, experience the same resonant enhancement and achieve important science reach for axions and axion-like particles. In this talk we focus on the design of the DMRadio-50L LC resonator. We outline the challenges in achieving high Q values, such as accurately measuring loss tangents for capacitor dielectrics, and discuss progress on measurements to understand them. This will include data from the DMRadio Pathfinder, as well as LC oscillator tests in Liquid Helium probes and dilution fridges. We will also discuss the function of the resonator within the overall experiment, i.e. how the coupling between the resonator and the DMRadio-50L superconducting sheath impacts performance and the tuning mechanisms with which we adjust the resonant frequency of the experiment.   

Live

Dark Matter Radio Cubic Meter (DMRadio-m$^3$) is a next-generation axion detector which will achieve sensitivity to the QCD axion over more than 1.5 orders of magnitude in mass, from 20neV to 0.8$\mu$eV. This science range, corresponding to frequencies of 5-200 MHz, includes substantial coverage of the two benchmark QCD axion models (KSVZ and DFSZ). To achieve these results, the DMRadio-m$^3$ detector will have a volume of $\sim$1m$^3$, a magnetic field of $\sim4$T, and a resonator quality factor Q $\sim 10^6$. The large volume and high magnetic field required by this experiment generates unique challenges compared to previous DMRadio detectors. In this talk we will describe plans for the DMRadio-m$^3$ experiment with a focus on the pickup structure geometry. In particular, we will demonstrate that high quality factors for the resonator can be achieved with a physically large coaxial copper structure.   

Live

The DMRadio experiment uses lumped LC oscillators in a magnetic field to resonantly search for axions in the kHz-MHz range. This search relies on the axion-photon coupling which adds an effective current term in Maxwell’s equations. As the frequencies scanned by the experiment will be lower than those of the LC oscillator’s cavity modes, it is instructive to analyze the system through effective circuits governed by the modified Maxwell’s equations. In this talk we will present the methods used to combine all components of the experiment into one effective circuit. By doing so, we can extract analytic formulas for the energy coupled by the axion and an understanding of the noise sources. In particular, this formalism provides a detailed framework for analysis and optimization of the system’s losses and of its two primary noise components, namely backaction and imprecision noise, as well as their correlations.   

Live

We introduce DMRadio-GUT, a future search for electromagnetic coupling to axion dark matter in the 400 peV-125 neV mass range, with sensitivity to GUT-scale QCD axion models. DMRadio-GUT is a challenging, long-term experiment that will build upon the techniques developed from the preceding DMRadio-50L and DMRadio-m$^{\mathrm{3}}$ campaigns. The search will take advantage of emerging and future developments in large, high-field magnets, high-Q superconducting lumped-element resonators, and electromagnetic quantum metrology in the kHz and MHz frequency ranges. In this talk, we overview the technological research and development needed to enable a GUT-scale QCD axion dark matter search with DMRadio-GUT.