Application of superconducting cavity tuner in dark photon dark matter search

Purpose: In order to precisely control the resonant frequency of RF superconducting cavity to detect dark photon dark matter, and to be able to tune within a certain frequency range, it is necessary to design a low-temperature tuner for frequency control on the bare cavity. Methods: Two type mechanical tuners have been designed for the 1.3 GHz single-cell bare cavity and 650 MHz single cell bare cavity. The tuner device tunes the frequency of RF superconducting cavity for the detection of dark photons and dark matter and measures its tuning range and accuracy in both room-temperature and low-temperature environments. Results: The tuner for the 1.3 GHz cavity has a tuning accuracy of 1 Hz per step and a tuning range of 1.37 MHz at low temperature. The tuner for the 650 MHz cavity has a tuning range of 467 kHz at low temperatures, with a tuning accuracy of 1.77 Hz per step. Conclusion: The designed tuner can meet the requirements of RF superconducting cavity tuning for detecting dark photons and dark matter, and its adjustable range, precision and stability ensure that the detection experiment can be carried out smoothly.