High-sensitivity approach searching for new force-carrying particles beyond the Standard Model

Abstract

The axion is a hypothetical particle proposed to resolve the strong CP problem of particle physics. Axions can mediate long-range spin-dependent interactions between two fermions, which can be detected by high-sensitivity magnetometry. Axion Resonant InterAction DetectioN Experiment (ARIADNE) provides a collaboration to search for the axions by probing the nuclear spin-dependent interaction using the nuclear magnetic resonance technique. ARIADNE is a methodological approach particularly sensitive to a high axion mass range from 0.1 meV to 10 meV. In order to reach experimentally allowed sensitivity, the experiment should be placed in an environment with very low background noise. Besides, the readout system should have high sensitivity to NMR signal from a $^{3}$He sample and also have the lowest possible noise around the nuclear spin-precession frequency of 100 Hz. The background field could be suppressed below the spin quantum noise level using a superconducting shield consisting of Nb thin film deposited on a quartz substrate. It was shown that a few micrometers thick Niobium film deposited on quartz can reduce the ambient noise by 7 orders of magnitude. We propose to replace the read-out SQUID-based magnetometer with the second-order axial planar gradiometer that will be significantly immune to microphonic noise and vibrations. In addition, we propose a new source mass design to increase sensitivity by one order of magnitude than the current design for axion mass near 0.1 meV. We found that a combination of the background shielding effect, the vibration noise reduction, and new source mass design will enable the experiment to reach the desired sensitivity.