5 results found
Ho C, Devlin JA, Rabey I, et al., 2020, New techniques for a measurement of the electron's electric dipole moment, New Journal of Physics, Vol: 22, ISSN: 1367-2630
The electric dipole moment of the electron (eEDM) can be measured with high precision using heavy polar molecules. In this paper, we report on a series of new techniques that have improved the statistical sensitivity of the YbF eEDM experiment. We increase the number of molecules participating in the experiment by an order of magnitude using a carefully designed optical pumping scheme. We also increase the detection efficiency of these molecules by another order of magnitude using an optical cycling scheme. In addition, we show how to destabilise dark states and reduce backgrounds that otherwise limit the efficiency of these techniques. Together, these improvements allow us to demonstrate a statistical sensitivity of 1.8 x 10⁻²⁸ e cm after one day of measurement, which is 1.2 times the shot-noise limit. The techniques presented here are applicable to other high-precision measurements using molecules.
Sauer BE, Devlin JA, Rabey IM, 2017, A big measurement of a small moment, New Journal of Physics, Vol: 19, ISSN: 1367-2630
A beam of ThO molecules has been used to make the most precise measurement of the electron's electric dipole moment (EDM) to date. In their recent paper, the ACME collaboration set out in detail their experimental and data analysis techniques. In a tour-de-force, they explain the many ways in which their apparatus can produce a signal which mimics the EDM and show how these systematic effects are measured and controlled.
Rabey IM, 2017, Improved shot noise of the YbF EDM experiment
Rabey IM, Devlin JA, Hinds EA, et al., 2016, Low magnetic Johnson noise electric field plates for precision measurement, Review of Scientific Instruments, Vol: 87, ISSN: 1089-7623
We describe a parallel pair of high voltage electric field plates designed and constructed to minimise magnetic Johnson noise. They are formed by laminating glass substrates with commercially available polyimide (Kapton) tape, covered with a thin gold film. Tested in vacuum, the outgassing rate is less than 5 x 10 exp(-5) mbar.l/s. The plates have been operated at electric fields up to 8.3 kV/cm, when the leakage current is at most a few hundred pA. The design is discussed in the context of a molecular spin precession experiment to measure the permanent electric dipole moment of the electron.
Cotter JP, McGilligan JP, Griffin PF, et al., 2016, Design and fabrication of diffractive atom chips for laser cooling and trapping, Applied Physics B, Vol: 122, ISSN: 0946-2171
It has recently been shown that optical reflection gratings fabricated directly into an atom chip provide a simple and effective way to trap and cool substantial clouds of atoms (Nshii et al. in Nat Nanotechnol 8:321–324, 2013; McGilligan et al. in Opt Express 23(7):8948–8959, 2015). In this article, we describe how the gratings are designed and microfabricated and we characterise their optical properties, which determine their effectiveness as a cold atom source. We use simple scalar diffraction theory to understand how the morphology of the gratings determines the power in the diffracted beams.
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