Search for Axion Dark Matter from 1.1 to 1.3 GHz with ADMX

Abstract

Axion dark matter can satisfy the conditions needed to account for all of the dark matter and solve the strong CP problem. The Axion Dark Matter eXperiment (ADMX) is a direct dark matter search using a haloscope to convert axions to photons in an external magnetic field. Key to this conversion is the use of a microwave resonator that enhances the sensitivity at the frequency of interest. The ADMX experiment boosts its sensitivity using a dilution refrigerator and near quantum-limited amplifier to reduce the noise level in the experimental apparatus. In the most recent run, ADMX searched for axions between 1.10-1.31 GHz to extended Kim-Shifman-Vainshtein-Zakharov (KSVZ) sensitivity. This Letter reports on the results of that run, as well as unique aspects of this experimental setup.

Figures (3)

• Figure 1: A: The electric field map of the TM$_{010}$ mode simulated by COMSOL Multiphysics comsol where the direction is marked by the red arrows and the field magnitude by the color corresponding to the adjacent scale bar. B: A mode map of the cavity showing its resonant frequencies as the rod is moved. The heatmap denotes the $S_{21}$ transmission through the resonator, with bright lines indicating the resonant modes of the cavity. The mode used in the search is the fundamental $TM_{010}$ mode, which can tune from $900-1400$ MHz.
• Figure 2: The effective HFET noise, $T_{\rm HFET}/\alpha_{\rm eff}$, over a range of frequencies. Gaps in the frequency data correspond to frequency regions that were not probed for axions. We measured $T_{\rm HFET}/\alpha_{\rm eff}$ using two different methods. The first method uses the direct fit of $T_{\rm HFET}/\alpha_{\rm eff}$ from a Y-factor measurement done with the JPA pump tone powered off (labeled JPA off fit). The second method uses the result from a Y-factor measurement done with the JPA pump tone powered on, which measures the JPA effective noise ($T_{\rm JPA,eff}$). We then use the SNRI and the models described in receivernoiseaxionhaloscopes to calculate what the corresponding $T_{\rm HFET}/\alpha_{\rm eff}$ is for each value of $T_{\rm JPA,eff}$ (labeled JPA on fit). The error bars shown are statistical and systematic errors. Larger error bars are due to systematic errors associated with the fit to the Y-factor measurement.
• Figure 3: A global limit plot putting this work (shown in purple) in context with other experiments, with an inset zooming in on this work's 90% C.L. upper limits on $g_{a\gamma\gamma}$ (as well as limits from Ref. CAPP_prx due to overlapping coverage). The dark matter density is assumed to be 0.45 GeV/$\mathrm{cm^3}$. Gaps in the limits are due to mode crossings, regions where axion search mode of the cavity intersected other static weakly tuning modes. KSVZ and DFSZ sensitivities are shown as dashed lines. Previous limits set by ADMX are shown in teal PhysRevLett.104.041301PhysRevLett.120.151301PhysRevLett.124.101303PhysRevLett.127.261803bartram2024axiondarkmatterexperiment10.1063/5.0122907PhysRevLett.121.261302. Limits from other experiments depicted include those set by University of Florida (UF) uf_limit_1990, Rochester-Brookhaven-Florida (RBF) Wuensch:1989sa, Center for Axion and Precision Physics (CAPP) Lee:2020cfjJeong:2020cwzCAPP:2020utbLee:2022mncKim:2022hmgYi:2022fmnYang:2023yryKim:2023vpoCAPP_prx, Haloscope At Yale Sensitive To Axion Cold dark matter (HAYSTAC) HAYSTAC:2018rwyHAYSTAC:2020kwvHAYSTAC:2023cam, Grenoble Axion Haloscope project (GrAHal) Grenet:2021vbb, Oscillating Resonant Group AxioN experiment (ORGAN) McAllister:2017lkbQuiskamp:2022pksQuiskamp:2023ehr, MAgnetized Disc and Mirror Axion eXperiment (MADMAX) c749-419q, QUaerere AXions experiment (QUAX) Alesini:2019ajtAlesini:2020vnyAlesini:2022lnpQUAX:2023gopQUAX:2024fut, Relic Axion Dark Matter Exploratory Setup (RADES) CAST:2020rlf, Taiwan Axion Search Experiment with Haloscope (TASEH) TASEH:2022vvu, CAST-CAPP Adair:2022rtw, and CERN Axion Solar Telescope (CAST) cast2024.