Towards a Precision Measurement of the Nuclear Schiff Moment in 205TlF molecules with CeNTREX

The Cold molecule Nuclear Time-Reversal EXperiment (CeNTREX) searches for time-reversal (T) symmetry violation—equivalently CP violation—in the hadronic sector. While T-violation exists in the Standard Model, it is too small to explain the observed baryon asymmetry of the universe. Extensions to the Standard Model often predict additional sources of T-violation, and observables such as Schiff moments and electric dipole moments (EDMs) offer clean, background-free probes of this new physics.

CeNTREX uses polarized thallium fluoride (205TlF) molecules to search for T-violating interactions by detecting shifts in nuclear magnetic resonance frequencies of the 205Tl nucleus. With the expected sensitivity, CeNTREX can set competitive limits on quark chromo-EDMs and the proton EDM.

We use rotational cooling to concentrate population in a single hyperfine level of the J=0 ground state. Electrostatic focusing requires a weak-field-seeking J=2 state, while the Schiff moment measurement uses J=1. Multiple quantum state transfer steps using adiabatic microwave passage connect these states.

Magnetic fields in the interaction region are suppressed below 10 μG using passive shielding and active shimming. This talk presents recent progress toward a Schiff moment measurement in 205TlF with CeNTREX.