High-Field Magnets for Axion Dark Matter Detection

The universe is mainly filled with dark matter, which nature remains unknown. A particularly interesting hypothesis is that it is made of new light particles called axions. Their detection requires intense magnetic fields. In this paper, we present the results of measurements at 4.2 K (LHe bath) in self-field of two High-Temperature Superconductors (HTS) REBCO single pancakes of about 800 turns from two different manufacturers. Those prototypes have been fabricated and tested to evaluate the latest present-day performances of HTS tapes suitable for the project. An axial magnetic induction of about 19 T has been reached with an operating current of 1400 A. The magnet survived to a quench at full energy (around 2050 A/mm 2 in the winding pack and 26 T peak field on the tape), which confirmed that the NI single pancake coil are effectively self-protected at such strong working conditions. However, we also confirmed that there are complexities, particularly in the mechanical and cryogenic areas, that have to be considered in the machine design.