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arXiv · 2501.05578

Rotational-hyperfine cooling of $^{205}$TlF in a cryogenic beam

Olivier Grasdijk·David DeMille·Jakob Kastelic·David Kawall·Steve Lamoreaux·Oskari Timgren·Konrad Wenz·Tanya Zelevinsky
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Abstract

The aim of CeNTREX (Cold Molecule Nuclear Time-Reversal Experiment) is to search for time-reversal symmetry violation in the thallium nucleus, by measuring the Schiff moment of $^{205}$Tl in the polar molecule thallium fluoride (TlF). CeNTREX uses a cryogenic beam of TlF with a rotational temperature of 6.3(2) K. This results in population spread over dozens of rotational and hyperfine sublevels of TlF, while only a single level is useful for the Schiff moment measurement. Here we present a protocol for cooling the rotational and hyperfine degrees of freedom in the CeNTREX beam, transferring the majority of the Boltzmann distribution into a single rotational and hyperfine sublevel by using a single ultraviolet laser and a pair of microwave beams. We achieve a factor of $20.1(4)$ gain in the population of the $J=0$, $F=0$ hyperfine sublevel of the TlF ground state.

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Olivier Grasdijk, David DeMille, Jakob Kastelic, David Kawall, Steve Lamoreaux, Oskari Timgren, Konrad Wenz, Tanya Zelevinsky. 2025-06-17. Rotational-hyperfine cooling of $^{205}$TlF in a cryogenic beam. https://arxiv.org/abs/2501.05578

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