NEW METHOD FOR MEASURING THE FINE STRUCTURE CONSTANT USING STARK SPECTROSCOPY.

An experiment to determine a value for alpha , the fine structure constant, is proposed. The detemination is to be based on a measurement of the Stark effect of hydrogen Rydberg states. Hydrogen atoms in a uniform field of known strength will be excited to Rydberg levels using intense tunable lasers. The presence of excited atoms is detected using the sensitive technique of field ionization. A precise measurement of the linear energy shift of an extreme Stark state is to be made, and from this measurement, in conjunction with reported values of R// infinity , the Rydberg constant, and 2e/h, the Josephson frequency-voltage ratio, a value of alpha are determined. The estimated accuracy of the determination is expected to be competitive with or better than the 0. 11 ppm accuracy of the current best non-QED determination of alpha .