Work on Precision Helium Spectroscopy: Some Experimental Details with Regard to Laser Alignment and B Field Measurement and Modeling.

In laser spectroscopy of an atomic beam, laser beam retroreflection to minimize first order Doppler shifts can introduce unwanted power dependence in the atomic resonant frequencies. In our experiment, we work to reduce these effects (related to laser cooling) while keeping the advantages of retroreflection. We do this through coupled fiber to free space beams, fiber optic switches, automated pico-motor control and good passive and active stability. Additionally in our experiment, magnetic fields required for the source and optical pumping regions can interfere with each other and with other regions, exacerbated by compactness goals. Physical intuition often leads to adequate designs of magnetic sources and materials, but the use of standard finite element analysis software tools is useful to verify and quantify expectations in combination with measurements. These and other ongoing experimental details will be discussed.