The μeV axion is a well-motivated extension to the standard model. The Axion Dark Matter eXperiment (ADMX) collaboration seeks to discover this particle by looking for the resonant conversion of ...dark-matter axions to microwave photons in a strong magnetic field. In this Letter, we report results from a pathfinder experiment, the ADMX "Sidecar," which is designed to pave the way for future, higher mass, searches. This testbed experiment lives inside of and operates in tandem with the main ADMX experiment. The Sidecar experiment excludes masses in three widely spaced frequency ranges (4202-4249, 5086-5799, and 7173-7203 MHz). In addition, Sidecar demonstrates the successful use of a piezoelectric actuator for cavity tuning. Finally, this publication is the first to report data measured using both the TM_{010} and TM_{020} modes.
This Letter reports the results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 μeV. The search excludes the range of axion-photon couplings predicted by plausible ...models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume haloscope at subkelvin temperatures, thereby reducing thermal noise as well as the excess noise from the ultralow-noise superconducting quantum interference device amplifier used for the signal power readout. Ongoing searches will provide nearly definitive tests of the invisible axion model over a wide range of axion masses.
This Letter reports on a cavity haloscope search for dark matter axions in the Galactic halo in the mass range 2.81-3.31 μeV. This search utilizes the combination of a low-noise Josephson parametric ...amplifier and a large-cavity haloscope to achieve unprecedented sensitivity across this mass range. This search excludes the full range of axion-photon coupling values predicted in benchmark models of the invisible axion that solve the strong CP problem of quantum chromodynamics.
We report the results from a haloscope search for axion dark matter in the 3.3-4.2 μeV mass range. This search excludes the axion-photon coupling predicted by one of the benchmark models of ..."invisible" axion dark matter, the Kim-Shifman-Vainshtein-Zakharov model. This sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise Josephson parametric amplifier, and sub-Kelvin temperatures. The validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals.
Axions are a promising cold dark matter candidate. Haloscopes, which use the conversion of axions to photons in the presence of a magnetic field to detect axions, are the basis of microwave cavity ...searches such as the Axion Dark Matter eXperiment (ADMX). To search for lighter, low frequency axions in the sub- 2 × 10 − 7 eV (50 MHz) range, a tunable lumped-element LC circuit has been proposed. For the first time, through ADMX SLIC (Superconducting LC Circuit Investigating Cold Axions), a resonant LC circuit was used to probe this region of axion mass-coupling space. The detector used a superconducting LC circuit with piezoelectric driven capacitive tuning. The axion mass and corresponding frequency ranges 1.7498 – 1.7519 × 10 − 7 eV (42.31–42.36 MHz), 1.7734 – 1.7738 × 10 − 7 eV (42.88–42.89 MHz), and 1.8007 – 1.8015 × 10 − 7 eV (43.54–43.56 MHz) were covered at magnetic fields of 4.5 T, 5.0 T, and 7.0 T, respectively. Exclusion results from the search data, for coupling below 10 − 12 GeV − 1 , are presented.
Searching for axion dark matter, the ADMX Collaboration acquired data from January to October 2018, over the mass range 2.81–3.31 μeV, corresponding to the frequency range 680–790 MHz. Using an ...axion haloscope consisting of a microwave cavity in a strong magnetic field, the ADMX experiment excluded Dine-Fischler-Srednicki-Zhitnisky (DFSZ) axions at 90% confidence level and 100% dark matter density over this entire frequency range, except for a few gaps due to mode crossings. This paper explains the full ADMX analysis for run 1B, motivating analysis choices informed by details specific to this run.
We report the direct observation of an electrically-induced magnetic susceptibility in the molecular nano- magnet Fe
O(O
CPh)
(py)
ClO
·py, an Fe
trimer. This magnetoelectric effect results from the ...breaking of spatial inversion symmetry due to the spin configurations of the antiferromagnetic trimer. Both static and very low frequency electric fields were used. Fractional changes of the magnetic susceptibility of 11 ppbFormula: see text per kVm
for the temperature range 8.5 < T < 13.5 K were observed for applied electric fields up to 62 kV m
. The changes in susceptibility were measured using a tunnel diode oscillator operating at liquid helium temperatures while the sample is held at a higher regulated temperature.
At a very low-temperature of 9 mK, electrons in the second Landau level of an extremely high-mobility two-dimensional electron system exhibit a very complex electronic behavior. With a varying ...filling factor, quantum liquids of different origins compete with several insulating phases leading to an irregular pattern in the transport parameters. We observe a fully developed nu=2+2/5 state separated from the even-denominator nu=2+1/2 state by an insulating phase and a nu=2+2/7 and nu=2+1/5 state surrounded by such phases. A developing plateau at nu=2+3/8 points to the existence of other even-denominator states.
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