Collaborative Research: Axion Resonant InterAction Detection Experiment (ARIADNE) - a renewal proposal

Overview. Axions are CP-odd scalar particles appearing in many extensions of the Standard Model. The well motivated Peccei-Quinn (PQ) axion can explain the smallness of the neutron electric dipole moment, and is also a promising Dark Matter candidate. Axions and axion-like particles also generate macroscopic P-odd and T-odd spin-dependent interactions which can be sought in sensitive laboratory experiments. 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 �eld, and a dense ensemble of laser-polarized 3He nuclei to detect the axion �eld by NMR. The signal from an axion �eld can be resonantly enhanced by properly modulating the axion potential at the nuclear spin precession frequency. The goal of this proposal is to �nalize assembly of the experimental probe, bring the experiment through its commissioning phase during which possible systematics will be evaluated, and start the data taking stage, exploring new paramater space for the PQ axion and axion-like particles. Intellectual Merit. 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 104 in the axion mass range of ma between 10 �eV and 10 meV, probing deep into the traditional \PQ-axion window". This proposal is especially relevant because to date there have been no experiments sensitive in the range 100 �eV < ma < 10 meV. In contrast to cosmic axion searches, since the experiment sources the axion �eld using local matter, this setup is sensitive to the axion even if it does NOT make up most of the dark matter. Furthermore by sensing the axion's coupling to nuclei, an entirely complimentary coupling is probed to that sought by Sikivie-type microwave cavity \haloscope" experiments and their proposed lower- and higher-frequency extensions. Broader Impacts. While participating in the proposed research, a team of postdocs, graduate students, and undergraduate researchers will be broadly trained in the techniques of experimental atomic physics, op- tical 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 scienti�c community. For example, Stanford postdoc Eli Levenson-Falk who was partially supported by this project is now an Assistant Professor at USC. An e�ort will continue to be made to recruit members of under-represented groups as students in the laboratory, including women and minorities. Four of the �ve students and postdocs mentored by Geraci who work on ARIADNE are women. Chen-Yu Liu mentored Los Alamos scientist Young-Jin Kim: she heads the research group of our LANL collaborator Pinghan Chu. M. Snow mentored Rakshya Khatiwada, now an assistant professor in a joint position with IIT/Fermilab and active on ADMX. Opportunities will exist for student involvement in an international collaboration, allowing travel between Korea, C