title: Precision measurement of the three 2(3)P(J) helium fine structure intervals.
abstract: The three 2(3)P fine structure intervals of 4H are measured at an improved accuracy that is sufficient to test two-electron QED theory and to determine the fine structure constant alpha to 14 parts in 10(9). The more accurate determination of alpha, to a precision higher than attained with the quantum Hall and Josephson effects, awaits the reconciliation of two inconsistent theoretical calculations now being compared term by term. A low pressure helium discharge presents experimental uncertainties quite different than for earlier measurements and allows direct measurements of light pressure shifts.
authors.affiliation: Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: T
authors.initials: T
authors.lastname: Zelevinsky
authors.forename: D
authors.initials: D
authors.lastname: Farkas
authors.forename: G
authors.initials: G
authors.lastname: Gabrielse