Team

Cold molecules

Scientific activity

The experiment, started in 2013, focuses on cooling the internal and external degrees of freedom of a supersonic jet of BaF molecules, and on optimizing molecule production. In the medium and long term, we aim to make precision measurements of P and CP violation effects, for which the BaF molecule is notoriously sensitive (electron dipole or parity violation effects in the nucleus).

Recently, optical pumping has made it possible to cool down rotation and vibration. The aim now is to slow down and then trap BaF using an ionic intermediate. An electrostatic decelerator is now capable of stopping ionized molecules (BaF+). We are now working on neutralization, i.e. electron capture by BaF+ ions. To achieve this, a jet of cesium atoms promoted to a Rydberg state (Cs* ) will provide a source of cold electrons. The aim is to understand the mechanism and efficiency of charge transfer, and to identify the final states in which BaF neutralizes. Finally, we also intend to use a negative ionic intermediate BaF-, more precisely a dipolar anion, for which the formation and neutralization will require specific studies.

© Hans Lignier, 2018.

Figure: Ultra-high vacuum chamber where the molecule jet propagates. Visible optical accesses are used for the production of BaF molecules by ablation of a target and for the photoionization of BaF, which are detected by microchannel wafers.