Date of Award


Publication Type

Master Thesis

Degree Name





Dirac, Helium, Hylleraas, Polarizability, relativity, Tune-out


Drake, Gordon




A tune-out wavelength of an atom is a wavelength of radiation such that the atom's polarizability vanishes [1]. It can be used as an alternative to inducing energy shifts for the purpose of testing quantum electrodynamics (QED). This is done by incorporating perturbations to the polarizability and calculating a chosen root, i.e. a tune-out wavelength. Comparison with experiment can determine the e ectiveness of the theory from which these perturbations arise. In this study, the calculated 23S - 33P transition tune-out wavelength for 4He was compared with an interferometry experiment done by Kenneth Baldwin's group at the Australian National University. The calculated result of 413:0858252(4) nm, which takes into account ne-structure e ects and other relativistic corrections of order 1 c2 , di ers from the experimental value of 413:0938(9stat)(20syst) nm [2] by about 1 part in 10, 000. This discrepancy is suspected to be due to QED e ects such as the atom's interaction with the vacuum, which is why QED perturbations should be tested as well in the future. The calculation of the 23S - 33P transition tune-out wavelength basically served as an exercise in studying the perturbative e ects of relativity to the order of 1 c2 .