J.L. Flowers

The NPL Rydberg Constant Experiment

We describe the characterization of the apparatus that has been constructed at the National Physical Laboratory for absolute optical frequency measurements of a number of two-photon 2S-nS,D transitions in the hydrogen atom. The use of a femtosecond optical frequency comb will enable many transitions to be studied under near-identical conditions, whereas the use of optical excitation for efficient production of the metastable 2S state will reduce ac Stark shifts. These improvements are expected to lead to significantly reduced uncertainty in the measured transition frequencies. Together with results from other experiments worldwide, this paper will contribute to an improved determination of the Rydberg constant

Progress towards a precision measurement of the helion magnetic moment in Bohr magnetons

We describe progress on a measurement of the magnetic moment of the helion in units of the Bohr magneton. An apparatus has been constructed which allows the exchange of helium-3 for atomic hydrogen in situ. Both helium-3 NMR and hydrogen atom ESR have been observed at a flux density of 0.6 T.

Optically pumped /sup 3/He NMR and atomic hydrogen ESR at 0.6 T

We report the successful observation of high-fields optically pumped nuclear magnetic resonance (NMR) of helium-3 and electron spin resonance (ESR) of atomic hydrogen, both at 0.6 T. Also described are our findings on the relative optical pumping efficiencies of the various components of the 1083 nm line in helium-3. These are a precursor to a measurement of the magnetic moment of the helion in Bohr magnetons. For this measurement the two signal frequencies must be measured sucessively in the same apparatus. This work is aimed at overcoming the limitations for high-accuracy magnetometry of using water as an NMR substance.

Precision spectroscopy of atomic hydrogen for an improved Rydberg constant determination

The 2S1/2-8D5/2 transition in atomic hydrogen has been observed as part of the preparation for a Rydberg constant determination at the National Physical Laboratory, UK. We describe this observation and the ongoing improvements to the experimental apparatus.

Precision Spectroscopy of Metastable Atomic Hydrogen: Towards an Improved Determination of the Rydberg Constant

We describe progress on a new experiment that is underway at NPL to measure the 2S-nS,D transitions in atomic hydrogen using a metastable atomic beam. This work will contribute to an improved value of the Rydberg constant

The magnetic moment of the helion in Bohr magnetons

We have previously described an experiment to measure the magnetic moment of the helion in Bohr magnetons. We now have preliminary results using the first of two proposed methods, an irreversible seal-breaking method. Improvements obtainable with the second method are discussed.

Progress towards a measurement of the bound electron to proton g-factor ratio at 0.6 tesla

We describe an experiment to measure the ratio of the bound electron to proton g-factor in atomic hydrogen. This is performed in in a magnetic flux density of 0.6 tesla. The electron and proton spin flip frequencies are determined by a least squares fit of the theoretical form of the modulated hydrogen electron spin resonance signal to the data.

Optical pumping of helium-3 at 0.6 T [for proton moment measurement]

We report on details of the successful high field optical pumping of helium-3 at 0.6 T. This is part of the progress on an ongoing experiment to measure /spl mu//sub h/(/sup 3/He)//spl mu/B. This work is aimed at overcoming the limitations of water as an NMR substance for high accuracy magnetometry.