INFN-LNF Laboratori Nazionali di Frascati
A significant milestone in the search for dark matter has been achieved at the INFN Frascati. National Laboratory.
The QUAX experiment, carried out at the COLD laboratory, has successfully completed its first official physics run, paving the way for the search of a hypothetical particle called the axion, which could potentially be a significant component of the dark matter that pervades the Universe and our Galaxy.
Data acquisition took place in December 2023, consisting in 25 hours of integrated signal. The results, obtained after a thorough statistical data analysis to study noise and any potential signal (not yet revealed), have been published in a prominent scientific journal in the field (Phys. Rev. D), following an extensive peer-review process, and are now publicly available at the following link: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.022008
QUAX employs a sophisticated experimental setup, based on the possibility that hypothetical dark matter candidates, interacting with a strong magnetic field, could transform into photons, detectable by sensors in the microwave range. In this case, the research was conducted using an 8 T superconducting magnet, and the resonant cavity (where the conversion into photons would occur) was equipped with two cryogenic piezoelectric motors: one for the insertion of the signal pick-up antenna, and one for the manipulation of an internal metal bar used to change the cavity’s frequency to test different values of the (unknown) axion mass. All this operated smoothly in the dilution refrigerator present in the COLD lab, which maintained the cavity’s temperature steadily at around 38 mK.
QUAX-LNF joins the landscape alongside the twin haloscope of the same collaboration already active at LNL, thus doubling its firepower. The next data-taking period for the local haloscope is scheduled for winter 2024.
Meanwhile, researchers are working to further enhance the sensitivity of the apparatus, aiming to increase the chances of detecting these elusive particles, using superconducting materials to improve the quality factor of the resonant cavity and frontier quantum technologies for photon detection. Qubits are one example, which can serve as single-photon detectors, thus surpassing a limit set by the laws of quantum mechanics.