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

Status of the 25 T, 100 mm Bore HTS Solenoid for an Axion Dark Matter Search Experiment

This paper presents the design and test results of the pancake coils for the 25 T, 100 mm bore solenoid that Brookhaven National Laboratory (BNL) is building for the Insti-tute for Basic Science (IBS) in Korea for an Axion dark matter search. The design is based on second generation (2G) High Temperature Superconducting (HTS) tape with no-insulation winding. The major challenges in the high field, large aperture solenoid are the large stresses and the quench protection. Moreo-ver, the design should be robust for reliable operation in a user facility environment. The paper will also present the construction and test results of two ∼100 mm bore double pancake coils creat-ing a peak field of up to ∼17 T and similar hoop stresses as will be in the 25 T solenoid. The coils were subject to several severe tests, including the simulations of large defects and extended quench studies at ∼4 K. The most striking part of these studies was the demonstration of how fast (a few hundred milliseconds) these coils can turn from the superconducting state to the normal state (quench or thermal runaway). This removes the past concerns of protecting high field HTS coils because of the low quench propa-gation velocities. © 2019 IEEE