Phase-matching of multiple-cavity detectors for dark matter axion search

Conventional axion dark matter search experiments employ cylindrical microwave cavities immersed in a solenoidal magnetic field. Exploring higher frequency regions requires smaller size cavities as the TM010 resonant frequencies scale inversely with cavity radius. One intuitive way to make efficient use of a given magnet volume, and thereby to increase the experimental sensitivity, is to bundle multiple cavities together and combine their individual outputs ensuring phase-matching of the coherent axion signal. We perform an extensive study for realistic design of a phase-matching mechanism for multiple-cavity systems and demonstrate its experimental feasibility using a double-cavity system.Comment: 5 pages, 2 figures, 1 tabl

Concept of multiple-cell cavity for axion dark matter search

In cavity-based axion dark matter search experiments exploring high mass regions, multiple-cavity design is considered to increase the detection volume within a given magnet bore. We introduce a new idea, referred to as multiple-cell cavity, which provides various benefits including a larger detection volume, simpler experimental setup, and easier phase-matching mechanism. We present the characteristics of this concept and demonstrate the experimental feasibility with an example of a double-cell cavity.Comment: 8 pages, 11 figure

Search for the Sagittarius Tidal Stream of Axion Dark Matter around 4.55 μ\mueV

We report the first search for the Sagittarius tidal stream of axion dark matter around 4.55 $\mu$eV using CAPP-12TB haloscope data acquired in March of 2022. Our result excluded the Sagittarius tidal stream of Dine-Fischler-Srednicki-Zhitnitskii and Kim-Shifman-Vainshtein-Zakharov axion dark matter densities of $\rho_a\gtrsim0.184$ and $\gtrsim0.025$ GeV/cm$^{3}$, respectively, over a mass range from 4.51 to 4.59 $\mu$eV at a 90% confidence level.Comment: 6 pages, 7 Figures, PRD Letter accepte

Development of an FPGA-based realtime DAQ system for axion haloscope experiments

A real-time Data Acquisition (DAQ) system for the CULTASK axion haloscope experiment was constructed and tested. The CULTASK is an experiment to search for cosmic axions using resonant cavities, to detect photons from axion conversion through the inverse Primakoff effect in a few GHz frequency range in a very high magnetic field and at an ultra low temperature. The constructed DAQ system utilizes a Field Programmable Gate Array (FPGA) for data processing and Fast Fourier Transformation. This design along with a custom Ethernet packet designed for real-time data transfer enables 100% DAQ efficiency, which is the key feature compared with a commercial spectrum analyzer. This DAQ system is optimally designed for RF signal detection in the axion experiment, with 100 Hz frequency resolution and 500 kHz analysis window. The noise level of the DAQ system averaged over 100,000 measurements is around -111.7 dBm. From a pseudo-data analysis, an improvement of the signal-to-noise ratio due to repeating and averaging the measurements using this real-time DAQ system was confirmed.11Nsciescopu

Simulation study on optimization of cavity design for axion search experiments using COMSOL multiphysics

A conventional axion search experiment utilizes microwave resonant cavities, where axions are converted into photons under a strong magnetic field. Optimized cavity dimension is essential to enhance signal power from the axion-to-photon coupling, to broaden the frequency range, to minimize mode crossings, etc. An extensive study has been performed to optimize the dimension of a cavity and frequency tuning system using the COMSOL multiphysics simulation software. We introduce a figure of merit for this purpose, and present the results from the simulation study

CAPP-8TB: Axion dark matter search experiment around 6.7 μev

© 2021 Elsevier B.V.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.11Nsciescopu

Fast DAQ system with image rejection for axion dark matter searches

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.11Nsciescopu

Magnetoresistance in copper at high frequency and high magnetic fields

In halo dark matter axion search experiments, cylindrical microwave cavities are typically employed to detect signals from the axion-photon conversion. To enhance the conversion power and reduce the noise level, cavities are placed in strong solenoid magnetic fields at sufficiently low temperatures. Exploring high mass regions in cavity-based axion search experiments requires high frequency microwave cavities and thus understanding cavity properties at high frequencies in extreme conditions is deemed necessary. We present a study of the magnetoresistance of copper using a cavity with a resonant frequency of 12.9 GHz at the liquid helium temperature in magnetic fields up to 15 T utilizing a second generation high temperature superconducting magnet. The observations are interpreted to be consistent with the anomalous skin effect and size effect. This is the first measurement of magnetoresistance at a high frequency (>10 GHz) in high magnetic fields (>10 T). © 2017 IOP Publishing Ltd and Sissa Medialab2