Axion dark matter experiment ultra-low noise haloscope technology has enabled the successful completion of two science runs (1A and 1B) that looked for dark matter axions in the 2.66–3.1 μeV mass range with Dine–Fischler–Srednicki–Zhitnisky sensitivity [Du et al., Phys. Rev. Lett. 120, 151301 (2018) and Braine et al., Phys. Rev. Lett. 124, 101303 (2020)]. Therefore, it is the most sensitive axion search experiment to date in this mass range. We discuss the technological advances made in the last several years to achieve this sensitivity, which includes the implementation of components, such as the state-of-the-art quantum-noise-limited amplifiers and a dilution refrigerator. Furthermore, we demonstrate the use of a frequency tunable microstrip superconducting quantum interference device amplifier in run 1A, and a Josephson parametric amplifier in run 1B, along with novel analysis tools that characterize the system noise temperature.
The Compton scattering cross section from 4 He has been measured with high statistical accuracy over a scattering angle range of 40 •-159 • using a quasi-monoenergetic 61-MeV photon beam at the High Intensity Gamma Ray Source (HIγS). The data are interpreted using a phenomenological model sensitive to the dipole isoscalar electromagnetic polarizabilities (αs and βs) of the nucleon. These data can be fit with the model using values of αs and βs that are consistent with the currently accepted values. These data will serve as benchmarks of future calculations from Effective Field Theories and Lattice QCD.
We present a new exclusion bound of axion-like particle dark matter with axion-photon couplings above 10 −13 GeV −1 over the frequency range 4796.7-4799.5 MHz, corresponding to a narrow range of axion masses centered around 19.84 µeV. This measurement represents the first implementation of a Josephson Traveling Wave Parametric Amplifier (JTWPA) in a dark matter search. The JTWPA was operated in the insert of the Axion Dark Matter eXperiment (ADMX) as part of an independent receiver chain that was attached to a 0.588liter cavity. The ability of the JTWPA to deliver high gain over a wide (3 GHz) bandwidth has engendered interest from those aiming to perform broadband axion searches, a longstanding goal in this field.
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