Toying with molecules; ammonia molecules in a fountain and synchrotron
Dr. Hendrick L. Bethlem (Vrije Universiteit, Amsterdam, The Netherlands)

We use electric fields to cool and manipulate polar molecules and use these cold molecules to perform precision tests of fundamental physics theories and collisions studies. I will present two experiments; in the first experiment we let beams of argon atoms collide with ammonia molecules that are stored in a synchrotron. Using a synchrotron has the advantage that the collision partners move in the same direction, resulting in a low collision energy. Furthermore, by storing molecules many roundtrips the sensitivity to collisions is greatly enhanced [1]. In the second experiment beams of ammonia molecules are decelerated, trapped, cooled and subsequently launched upwards with a velocity between 1.4 and 1.9 m/s. Molecules with this speed will fly up 60-180 mm before falling back under gravity. We have demonstrated field-free interaction times up to 266 millisecond, two orders of magnitude longer than has been achieved with molecular beams [2]. Finally, I will discuss a new project, conducted in collaboration with the University of Groningen, to cool barium-fluoride molecules and use these to search for the electric dipole moment of the electron which is a sensitive probe for physics beyond the standard model [3].
References
[1] Cold Collisions in a Molecular Synchrotron, A.P.P. van der Poel, P.C. Zieger, S.Y.T. van de Meerakker, J. Loreau, A. van der Avoird, and H.L. Bethlem, Phys. Rev. Lett. 120, 033402 (2018).
[2] Molecular Fountain, C. Cheng, A.P.P. van der Poel, P. Jansen, M. Quintero-Prez, T.E. Wall, W. Ubachs, and H.L. Bethlem, Phys. Rev. Lett. 117, 253201 (2016).
[3] Measuring the electric dipole moment of the electron in BaF, NL-eEDM collaboration, Eur. Phys. J. D. 72, 197 (2018).