Rotational Cooling TlF molecules for the CeNTREX nuclear Schiff moment search

The aim of CeNTREX  (Cold molecule Nuclear Time-Reversal Experiment) is to search for time-reversal symmetry violation in the thallium nucleus by exploiting the Schiff moment of ²⁰⁵TlF in the polar molecule thallium fluoride (TlF). A cold beam of TlF with a rotational temperature of 7 K is produced with a cryogenic buffer gas beam source. The CeNTREX beamline will span some 7 meters, and requires rotational cooling and subsequent collimation with an electrostatic quadrupole lens to reach sufficient sensitivity to the Schiff moment. The rotational cooling procedure transfers a majority of the molecular population into a single rotational and hyperfine sublevel of the ground state manifold, using a single ultraviolet laser and a pair of microwave beams. Here we report on the procedure and current status of rotational cooling in CeNTREX.