Towards a measurement of the electric dipole moment of the electron with YbF molecules
File(s)
Author(s)
Ho, Christopher Junhong
Type
Thesis
Abstract
The search for electric dipole moments (EDMs) of particles has been an active field of research for the past 70 years. Scientific interest in EDMs stems from the fact that these are direct signals of parity symmetry (P) violation, and time-reversal symmetry (T) violation. In most extensions to the Standard Model, new CP-violating interactions that can help explain the origin of the observed matter-antimatter asymmetry in the universe also predict particle EDMs with sizes that current and near-future experiments are sensitive to. The current best measurements of the electron EDM (eEDM) have already constrained the energy scale of a broad class of CP-violating interactions to energies above 3 TeV.
I describe progress towards a measurement of the eEDM using a beam of YbF molecules. I implement a method that distills the molecular population into the required quantum state, and a new method for detecting the molecules with higher efficiency. I characterise the imperfections in this detection scheme. By minimising the impact of these imperfections and various sources of technical noise, I demonstrate an improvement in the shot-noise limited sensitivity by a factor of 14.5 since the last published measurement. The actual noise is limited by magnetic noise to 2.1 times this shot-noise limit. A measurement of the eEDM at this shot-noise-limited sensitivity would improve constraints of new CP-violating interactions by a factor of 3.2, and I present an outlook for such a measurement.
I describe progress towards a measurement of the eEDM using a beam of YbF molecules. I implement a method that distills the molecular population into the required quantum state, and a new method for detecting the molecules with higher efficiency. I characterise the imperfections in this detection scheme. By minimising the impact of these imperfections and various sources of technical noise, I demonstrate an improvement in the shot-noise limited sensitivity by a factor of 14.5 since the last published measurement. The actual noise is limited by magnetic noise to 2.1 times this shot-noise limit. A measurement of the eEDM at this shot-noise-limited sensitivity would improve constraints of new CP-violating interactions by a factor of 3.2, and I present an outlook for such a measurement.
Version
Open Access
Date Issued
2020-06
Date Awarded
2020-11
Copyright Statement
Creative Commons Attribution-Non Commercial 4.0 International License
License URL
Advisor
Sauer, Benjamin
Tarbutt, Michael
Hinds, Edward
Sponsor
Engineering and Physical Sciences Research Council (CDT)
Grant Number
EP/G037043/1
EP/L016524/1
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)