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Ultracold YbF molecules to measure the electron's electric dipole moment.

Periodic Reporting for period 1 - UCEEDM (Ultracold YbF molecules to measure the electron's electric dipole moment.)

Période du rapport: 2020-06-01 au 2022-05-31

The purpose of this fellowship was to build an instrument for measuring the electron's electric dipole moment (eEDM) with a precision better than 10^30 e cm, with a longer term prospect of reaching below 10^31 e cm. This measurement will test new theories beyond the Standard Model (BSM) of particle physics and search for the undiscovered forces responsible for the observed asymmetry between matter and anti-matter in the Universe. Many BSM theories introducing new CP violating interactions to account for this asymmetry predict an eEDM many order of magnitude larger than in the standard model.
A new instrument was built for measuring the electron's electric dipole moment (eEDM). The instrument is based on a beam of ultracold YbF molecules. A key result was the development of a slow beam of YbF molecules. Another key result was direct laser cooling of YbF molecules to below 100 microkelvin. This produces a bright, highly collimated beam that is well suited for measuring the eEDM. The laser cooling was characterised in detail with respect to all the key control parameters. Highly efficient molecule detectors were built and characterised. A scheme to optically pump the molecules into the quantum state needed for the eEDM measurement was developed and tested. A magnetically-shielded eEDM interaction region was developed and the magnetic noise in this region was characterised in detail.
The YbF molecule has been cooled in two dimensions for the first time. The temperature and number of cold molecules achieved are state of the art.
The machine built has the required characteristics (beam brightness, interaction time, detection noise, magnetic noise) to reach a state of the art sensitivity on the eEDM measurement in a near future.
Mechanical drawing of the new eEDM machine.
The ultracold eEDM experiment, with its electric field plates in the glass tube chamber.