RUI: high-precision atomic structure measurements and tests of fundamental physics in multi-valence atoms

Williams College received a $409,897 Project Grant from the National Science Foundation (NSF) Division of Physics under the Mathematical and Physical Sciences program (CFDA 47.049), effective September 1, 2025 through August 31, 2028. The award supports high-precision atomic structure measurements and fundamental physics research conducted at the undergraduate institution's laboratory in Williamstown, Massachusetts. The research program delivers experimental results through table-top laser spectroscopy and atomic measurements of multi-valence atoms, with findings compared against theoretical models to advance understanding of complex atomic systems and test predictions from particle physics and cosmology.

The project's educational component constitutes a significant deliverable, as undergraduate researchers participate in all aspects of the experimental work, including apparatus construction, experimental design, data collection, and sophisticated data analysis procedures. The research aims to generate insights applicable to profound scientific questions, including the nature of dark matter and the potential discovery of new elementary particles. By pairing precise experimental measurements with equally precise theoretical atomic wavefunctions, the program contributes to low-energy physics tests that complement accelerator-based experiments and observational astronomy searches within the broader scientific enterprise supported by NSF's Mathematical and Physical Sciences program.

Abstract

This research program, located at an undergraduate institution, features hands-on, table-top experiments using lasers and heated atomic samples to measure with great accuracy certain properties of complex atomic systems. These experimental results can then be compared to state-of-the-art models with which theoretical physicists can predict these same properties. With better understanding of the workings of these particular atoms, IT is possible for future laboratory experiments to use such atoms as tools to provide insights to some of the most profound questions facing science today ? Including the nature of dark matter in the universe and the possible presence of new elementary particles not yet discovered. In the PI?s laboratory, experiments proceed with the aid of talented undergraduate researchers, many getting their first taste of science research. Students become involved in all aspects of the experimental work, building and testing apparatus, designing new experiments, and carrying out data collection and sophisticated data analysis procedures. Over recent decades, highly precise atomic physics experiments using laser spectroscopy have contributed important insights into the physics of the standard model of particle physics. Such low-energy physics tests complement accelerator-based experimental work as well as observational astronomy searches. The tiny size of these effects demands very high precision, extensive study of potential errors, and careful experimental design. Therefore, the precise experiments must be paired with equally precise theoretical models of the atomic wavefunctions, which are required to distinguish the ?ordinary? Quantum mechanical behavior from the ?exotic? Physics phenomena being targeted. In the PI?s research laboratory, the group is pursuing an ongoing series of diode laser spectroscopy measurements of the atomic properties of group III and group IV multi-valence atoms (thallium, indium, lead, tin) which can be compared to state-of-the-art atomic theory calculations. Atoms are studied both in heated vapor cells and in an atomic-beam apparatus housed in a large, evacuated chamber. These atoms contain three or four valence electrons, challenging the approximation techniques required to accurately compute wavefunctions. This experiment-theory interplay has resulted in significantly improved accuracy in recent years and has impacted the importance of these atomic-physics-based experiments. With funding from the current grant, the PI will collaborate with a junior faculty colleague to demonstrate laser cooling in lead atoms ? An experimental technique that has long facilitated high-precision measurements in many atomic systems, but which has never been applied to the lead atom. 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.- subawards are not planned for this award.