CAREER: High Precision Spectroscopy of the Beryllium Isotope Chain

Smith College, Northampton MA

Investigators

Abstract

The aim of this project is to advance the understanding of the inner workings of the atom. Specifically, this project investigates how all the components that make up the beryllium atom, the fourth element on the periodic table, come together to give beryllium its atomic and nuclear properties. Our knowledge of atomic systems is driven by both experimental and theoretical results. The lighter elements (hydrogen, helium, and lithium) have been extensively studied both experimentally and theoretically. Because beryllium has more subatomic particles compared to the three lighter elements, it is more complex and difficult to model. As the computations involved in modeling this atom grow more complex, it becomes essential to provide experimental results to both check those calculations and determine which theoretical models correctly describe this multi-electron system. The most precise experimental measurements currently available for beryllium are up to 10,000 times less precise than those for the three lighter elements. This project will greatly improve upon these experimental measurements in order to validate fundamental atomic and nuclear theories as well as provide information about the nuclear and electronic structure of the atom. Understanding beryllium is an important stepping stone to developing a multi-electron theory that successfully describes larger and heavier atoms, which make up the bulk of the periodic table of the elements and are essential components of the materials that we live and work with every day. High precision spectroscopy will be performed on the neutral beryllium isotope chain to significantly improve the experimental accuracy of several key energy levels. The results will delineate various theoretical models, test quantum electrodynamics, and help determine the nuclear charge radius of beryllium. Spectroscopy will be performed on both singlet states (2s2p, 2s3d, and 2snp Rydberg states) and triplet states (2s2p, 2s3s, 2s4s, and 2snp Rydberg states) as well as the ionization threshold. An oven operating at 1200 degrees Celsius will produce a beam of neutral atomic beryllium. Transverse spectroscopy will be performed on this atomic beam using a variety of laser sources including a frequency quadrupled Ti-Sapphire laser and external cavity diode lasers. Photon energy calibration is provided by a calibrated ultra low expansion cavity and the atom-light interaction is detected by absorption, fluorescence, or ion detection depending on the state being studied.