An axion dark matter search with the CAPP-8TB haloscope is reported. Our results are sensitive to axion-photon coupling g_{aγγ} down to the QCD axion band over the axion mass range between 6.62 and ...6.82 μeV at a 90% confidence level, which is the most sensitive result in the mass range to date.
We first report an axion haloscope search with toroidal geometry. In this pioneering search, we exclude the axion-photon coupling gaγγ down to about 5×10−8 GeV−1 over the axion mass range from 24.7 ...to 29.1 μeV at a 95% confidence level. The prospects for axion dark matter searches with larger scale toroidal geometry are also considered.
A
bstract
The signal to noise ratio efficiency
ϵ
SNR
in axion dark matter searches has been estimated using large-statistic simulation data reflecting the background information and the expected ...axion signal power obtained from a real experiment. This usually requires a lot of computing time even with the assistance of powerful computing resources. Employing a Savitzky-Golay filter for background subtraction, in this work, we estimated a fully analytical
ϵ
SNR
without relying on large-statistic simulation data, but only with an arbitrary axion mass and the relevant signal shape information. Hence, our work can provide
ϵ
SNR
using minimal computing time and resources prior to the acquisition of experimental data, without the detailed information that has to be obtained from real experiments. Axion haloscope searches have been observing the coincidence that the frequency independent scale factor
ξ
is approximately consistent with the
ϵ
SNR
. This was confirmed analytically in this work, when the window length of the Savitzky-Golay filter is reasonably wide enough, i.e., at least 5 times the signal window.
A
bstract
One of the most significant and practical figures of merit in axion haloscope searches is the scanning rate, because of the unknown axion mass. Under the best experimental parameters, the ...only way to improve the figure of merit is to increase the experimentally designed signal to noise ratio in the axion haloscope search analysis procedure. In this paper, we report an improved axion haloscope search analysis using the data taken by the CAPP-8TB haloscope. By correcting for the background biased by the background parametrizations in the presence of axion signals, we realized a signal to noise ratio efficiency of about 100%. Given the axion haloscope search analyses to date, the scanning rate can be improved by 21%, with about a 10% improvement in the signal to noise ratio. This improvement is another low cost innovation in axion haloscope searches, where all the experimental parameters are currently at their best.
A new highly sensitive method of looking for electric dipole moments of charged particles in storage rings is described. The major systematic errors inherent in the method are addressed and ways to ...minimize them are suggested. It seems possible to measure the muon EDM to levels that test speculative theories beyond the standard model.
A new, hybrid design is proposed to eliminate the main systematic errors in the frozen spin, storage ring measurement of the proton electric dipole moment. In this design, electric bending plates ...steer the particles, and magnetic focusing replaces electric. The magnetic focusing should permit simultaneous clockwise and counterclockwise storage to cancel systematic errors related to the out-of-plane dipole electric field. Errors related to the quadrupole electric fields can be eliminated by successive runs of magnetic focusing with different strengths.
Hypothetical low-mass particles, such as axions, provide a compelling explanation for the dark matter in the universe. Such particles are expected to emerge abundantly from the hot interior of stars. ...To test this prediction, the CERN Axion Solar Telescope (CAST) uses a 9 T refurbished Large Hadron Collider test magnet directed towards the Sun. In the strong magnetic field, solar axions can be converted to X-ray photons which can be recorded by X-ray detectors. In the 2013-2015 run, thanks to low-background detectors and a new X-ray telescope, the signal-to-noise ratio was increased by about a factor of three. Here, we report the best limit on the axion-photon coupling strength (0.66 × 10-10 GeV-1 at 95% confidence level) set by CAST, which now reaches similar levels to the most restrictive astrophysical bounds.
CAPP-8TB: Axion dark matter search experiment around 6.7 μev Choi, J.; Ahn, S.; Ko, B.R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2021, Letnik:
1013
Journal Article
Recenzirano
Odprti dostop
CAPP-8TB is an axion dark matter search experiment dedicated to an axion mass search near 6.7μeV. The experiment uses a microwave resonant cavity under a strong magnetic field of 8T produced by a ...superconducting solenoid magnet in a dilution refrigerator. We describe the experimental configuration used to search for a mass range of 6.62 to 6.82μeV in the first phase of the experiment. We also discuss the next phase of the experiment and its prospects.
Abstract
A fast data acquisition (DAQ) system for axion dark matter
searches utilizing a microwave resonant cavity, also known as axion
haloscope searches, has been developed with a two-channel ...digitizer
that can sample 16-bit amplitudes at rates up to 180
MSamples/s. First, we realized a practical DAQ efficiency of greater
than 99% for a single DAQ channel, where the DAQ process includes
the online fast Fourier transforms (FFTs). Using an IQ mixer and two
parallel DAQ channels, we then also implemented a software-based
image rejection without losing the DAQ efficiency. This work extends
our continuing effort to improve the figure of merit in axion
haloscope searches, the scanning rate.
We review the electro-magnetic energy at axion haloscopes and find that the electric and the corresponding magnetic energy stored in the cavity modes or, equivalently, the mode dependent electric and ...magnetic form factors are the same regardless of the position of the cavity inside the solenoid. Furthermore, we extend our argument to the cases satisfying ∇→×B→external=0, where B→external is a static magnetic field provided by a magnet at an axion haloscope. Two typical magnets, solenoidal and toroidal, satisfy ∇→×B→external=0; thus, the electric and the corresponding magnetic energy stored in the cavity modes are always the same in both cases. The energy, however, is independent of the position of the cavity in axion haloscopes with a solenoid, and depends on those with a toroidal magnet.
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