Results from phase 1 of the HAYSTAC microwave cavity axion experiment

Abstract

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 and 5.8 GHz. We exclude axion models with two photon coupling g aγγ ≳ 2 × 10 −14 GeV −1 , a factor of 2.7 above the benchmark KSVZ model over the mass range 23.15 < m a < 24.0 μeV. This doubles the range reported in our previous paper. We achieve a nearquantum-limited sensitivity by operating at a temperature T < hν=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.

Several Problems in Particle Physics and Cosmology Solved in One SMASH

“…The continuing dashed lines show plausible uncertainties. We also show, in grey, the current bounds on axion DM (ADMX [106,107],BRF) and, in green, prospects for next generation axion dark matter experiments, such as ADMX [106,107], CAPP [108], HAYSTAC [109], MADMAX [111,112], ORPHEUS [113,114], and the helioscope IAXO [115] (fiducial, extended+ sensitivities to the axion-photon channel and IAXOeγ for the electron-photon channel). Adapted from Ref.…”

“…Most importantly, this axion dark matter mass window will be probed in the upcoming decade by axion dark matter direct detection experiments such as ADMX [106,107], CAPP [108], HAYSTAC [109], RADES [110], MADMAX [111,112], ORPHEUS [113,114] and others, cf. Fig.…”

Tunable Axion Plasma Haloscopes

“…Such a detection scheme is more easily reached at low masses, where Josephson parametric amplifiers operating with a dilution refrigerator have been shown to achieve near quantum limited detection [44]. With a more modest detection system, such as a commercially available high electron mobility transistor operating in liquid helium (T sys ∼ 5 K) the higher mass range 100 − 160 µeV could be explored in a similar time frame (4 years).…”

Exploiting higher-order resonant modes for axion haloscopes

“…A conventional way to tune the resonant frequency of a cylindrical cavity is to break the transverse symmetry by translating a (pair of) dielectric or conducting rod(s) in the radial direction [7,8]. For a cylindrical dielectric cavity, such symmetry breaking can be achieved by splitting the dielectric hollow vertically into pieces and moving them apart along the radial direction.…”