Collaborative Research: Axion Resonant InterAction DetectioN Experiment (ARIADNE) - a Continuation Proposal

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Multiple astronomical observations have established that about 85% of the matter in the universe is not made of known particles. Deciphering the nature of this so-called Dark Matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. One of the most exciting quests in particle physics is the search for new particles beyond the Standard Model of particle physics. Extensions of the Standard Model predict not only new particles with large masses but also some with very small masses. Such a candidate is the axion, which has been introduced to explain the smallness of Charge-Parity (CP) violation in Quantum Chromodynamics and which turns out to also be a prime candidate for a constituent of the dark matter in the universe. The Axion Resonant InterAction DetectioN Experiment (ARIADNE) is designed to search for axion-mediated spin-dependent interactions between nuclei at sub-millimeter ranges. The experiment involves a rotating non-magnetic mass to source the axion field, and a dense ensemble of laser-polarized He-3 nuclei to detect the axion field by Nuclear Magnetic Resonance. While participating in this research, a team of postdocs, graduate students, and undergraduate researchers will be broadly trained in the techniques of experimental atomic physics, optical pumping, nuclear magnetic resonance, low-temperature physics, micro-fabrication, magnetic shielding, vacuum systems, and modeling. This will be valuable preparation for work in basic or applied research, either in the U.S. or international work force or scientific community.The signal from an axion field can be resonantly enhanced by properly modulating the axion potential at the nuclear spin precession frequency. The goal of this award is to complete construction of the experiment, bring it through its commissioning phase during which possible systematics will be evaluated, and start the early data taking stage, exploring new parameter space for the PQ axion. The method has the potential to improve previous experimental and astrophysical bounds on axions by several orders of magnitude and probe deep into the theoretically interesting regime for the PQ axion. The experiment is also sensitive to more exotic axion-like particles. The new method can ultimately exceed present laboratory constraints on spin-dependent short-range forces by up to 8 orders of magnitude and can improve on the combined laboratory/astrophysical limits by a factor of 10^4 in the axion mass range of ma between 10 micro-eV and 10 milli-eV, probing deep into the traditional "PQ-axion window".This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.