"Fine Structure Constant Measurement Using Helium Spectroscopy"
Tanya Zelevinsky
Harvard University
Wednesday, February 4, 2004 --11 AM -12:00 Noon in 375 LeConte Hall
Abstract
The fine structure constant, alpha, is one of the most fundamental
constants in physics. Currently, the most precise measurement of alpha comes from the
electron g-factor experiments. However, it is vital to determine alpha using other physics,
including atomic systems. Helium fine structure happens to be a very suitable
system, due to the large splitting and long lifetime of the sublevels. It can
yield a precise value of alpha, and can be used to test the internal consistency of QED
as well as 3-body QED calculations. The Harvard helium experiment features
precision spectroscopy with diode lasers at 1083 nm. Helium-4 atoms are at room
temperature in a rf discharge, pressure-regulated vapor cell. The talk will
discuss our experimental approach to measuring alpha as well as the results to date and
critical systematic effects.
