Argon Crystals for the Electron Electric Dipole Moment (eEDM) Search with the EDM^3 Collaboration

点击翻译按钮获取中文摘要

The proposed research is toward the search for the permanent electron (e-) electric dipole moment (EDM). The e- is a point particle in the classical physics picture but physics predicts an asymmetry in the charge near it. Detecting the precession or wobble of the eEDM in an electric field, in polar molecules for example, will confirm the expected, yet elusive, eEDM. To probe for this effect, many e- (improved statistics) observed for long periods (characterized by precession time) are required. Measurements by the ACME II collaboration indicate an eEDM below 1.1*10^--29 e-cm. The challenge is that the physical size of the e EDM is tiny and its measurement will require development of new techniques. The projected sensitivity of our recently established EDM^3 (Electric Dipole Measurements using Molecules within a Matrix) collaboration will find the eEDM or limit it at a level of <10^-34 ecm, a 10^5 times improvement. My independent research contribution to the EDM^3 will provide the ideal substrate for Argon (Ar) crystal growth in which the polar molecules are fixed. Specifically, the short-term objectives of this Discovery application are to: (1) produce highly pure cryogenic Ar solids from liquified Ar in a crystal form; (2) make crystallographic measurements to confirm it is a monolithic crystal with the required low defect and impurity content; and (3) manipulate this cryogenic crystal transporting it into separate apparatus where the polar molecules are deposited during additional crystal growth on this idea substrate for EDM^3 goals. These objectives are toward EDM^3 goals where an apparatus is under development to observe the first polar molecules frozen in an Ar solid. Here argon is frozen on a sapphire substrate and freezes in an unknown, random orientation due to the sapphire surface potentials. A cylindrical, cm diameter, flawless, Ar crystal with embedded polar molecules is to be needed for EDM^3 objectives. Finding an asymmetry in the charge near the e would lead to a permanent eEDM, the discovery of which would be ground-breaking, narrowing the range of possible physics models describing the universe, and providing evidence of new particles or interactions that lead to the observed matter--antimatter asymmetry in the universe. Our new approach will increase the e number observed and the duration of time they are observed by fixing the molecules in a crystal of frozen Ar. Our small laboratory apparatus is novel: measurements that detect this tiny size probe energy scales beyond the reach of high energy accelerators, making our research competitive with LHC experiments at CERN but at a tiny fraction of the cost and housed at a Canadian University. This project will enable 10 undergraduates and 7 graduates to receive training in high tech fields ideal for careers in today's industries. The success of our research will cement the way to achieve the most sensitive measurement yet of the eEDM.