Prize Recipient

S. Charles Doret
Williams College

"A Precise Measurement of the Stark Shift in the 6P1/2 —> 7S1/2 378 nm Transition in Atomic Thallium."

Doret spent nearly two and a half years working in the atomic physics laboratory at Williams College, culminating in his senior honors project on the measurement of the Stark shift of an electric dipole transition in thallium. This work helps provide the atomic structure information required to relate the observed parity violations in atoms to the underlying parity-violating weak interaction. He constructed, tested, redesigned and optimized important pieces of the optical system, the atomic beam system, the high-voltage system, and the data acquisition system. His significant improvements to the experimental apparatus enabled him to collect and analyze an enormous amount of high-precision Stark shift data. Much of the experimental challenge for Doret was to identify and eliminate systematic errors. He performed extensive computer simulations, and completed many paper-and-pencil estimates of potential effects; proposed various experimental "checks" and some redesign of the data collection method and, based on this, has completed a thorough experimental exploration of potential errors. His result was a measurement of the Stark shift with 0.4% accuracy, and experimental precision now far exceeds the precision of calculated thallium wave functions, presenting a challenge for future theoretical improvement.