Dr. Guillaume Pignol

Date and Location:

Tuesday, October 24, 2017 3:30 PM
Presentation at 3:45 PM, NPL 178 Coffee and cookies starting at 3:30 PM


Search for the electric dipole moment of the neutron


Why is there so little antimatter in the Universe? How the matter/antimatter asymmetry
was generated? New physics, beyond the Standard Model, was certainly at play in a
hypothetical phase of the early Universe called baryogenesis. Since this new physics
must induce a violation of CP symmetry, it could be revealed in the laboratory by
measuring a nonzero electric dipole moment of a spin 1/2 particle such as the neutron.
A collaboration of 15 institutions is searching for the neutron electric dipole moment
(nEDM) using the ultracold neutron source at the Paul Scherrer Institute (PSI) in
Switzerland. The most precise measurement of the nEDM has been produced by the
Sussex/RAL/ILL spectrometer at the ILL research reactor in Grenoble, it is compatible
with zero, with the upper limit 𝑑" < 3×10()* 𝑒 cm @ 90% C. L. [J.M. Pendlebury et al. PRD
92, 092003 (2015)]. We have operated an upgraded version of this apparatus to take data
at PSI in the period 2015-2017 and we are now building the next generation spectrometer,
In my talk I will present the current status of the measurement and discuss the statistical
and systematical uncertainties. Also, I will present a search for an oscillating nEDM in our
data. Such an oscillation could be induced in a scenario where Dark Matter is formed by
an oscillating Axion-like field.