Ba in BaF molecules*

This talk will describe progress towards measuring the nuclear anapole moment of ¹³⁷Ba in barium monofluoride (BaF) molecules. First, an outline of our quantum-enabled measurement scheme will be described. A proof of principle for our measurement technique was demonstrated recently using the ¹⁹F nucleus in ¹³⁸Ba¹⁹F; there a sensitivity sufficient to measure the predicted effect in ¹³⁷BaF, at the 10% level, was achieved. Since then several major improvements have been incorporated into the system, such as a cryogenic buffer gas beam source (for lower molecule velocity and higher flux), a home-built, highly stable reference laser locked to a cesium atom line (for improved laser frequency stabilization). We have recently measured details of the hyperfine structure in the A²Π_1/2 state of ¹³⁷BaF, and are performing measurements of hyperfine structure in the D²Σ⁺ state as well. This structure must be known to employ our method for quantum state preparation and detection needed to measure the anapole moment in ¹³⁷Ba.