Extended Axion Dark Matter Search Using the CAPP18T Haloscope

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We report an extended search for the axion dark matter using the CAPP18T haloscope.

• The CAPP18T experiment adopts innovative technologies of a high-temperature superconducting magnet and a Josephson parametric converter.
• The CAPP18T detector was reconstructed after an unexpected incident of the high-temperature superconducting magnet quenching.
• The system reconstruction includes rebuilding the magnet, improving the impedance matching in the microwave chain, and mechanically readjusting the tuning rod to the cavity for improved thermal contact.