ZOMBIES: Towards measuring the parity-violating nuclear anapole moment of ¹³⁷Ba in BaF molecules

The ZOMBIES experiment aims to measure the parity-violating nuclear anapole moment of ¹³⁷Ba in barium monofluoride (BaF) molecules. Our prior work, a proof of principle measurement with the ¹⁹F nucleus in ¹³⁸Ba¹⁹F achieved sensitivity sufficient to measure the predicted effect in ¹³⁷BaF, at the 10% level [1]. We have since incorporated several improvements into our system: a cryogenic buffer gas beam source and an improved laser frequency locking scheme. We discuss two new strategies to increase the flux of the low-abundance isotopologue ¹³⁷BaF in our experiment: magnetic focusing of the molecular beam and rotational and hyperfine cooling in the ground state using optical serrodyne techniques. We also present our study of the hyperfine structure of the A²Π_1/2 state in ¹³⁷BaF and recent work investigating the Zeeman structure of these states, which is essential for our state preparation and detection schemes.

[1] E. Altunta\c{s}, J. Ammon, S. B. Cahn, and D. DeMille, Phys. Rev. Lett. 120, 142501 (2018)