Searching for a Muon Electric Dipole Moment with the Straw Trackers at the Fermilab Muon g-2 experiment - PhDData

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Searching for a Muon Electric Dipole Moment with the Straw Trackers at the Fermilab Muon g-2 experiment

The thesis was published by Vasilkova, Dominika, in October 2023, UCL (University College London).

Abstract:

As well as measuring the muon magnetic moment (MDM), the Muon g-2 experiment at Fermilab is aiming to make a new world leading measurement of the muon electric dipole moment (EDM), with a target of 10−21 e·cm, an improvement of two orders of magnitude compared to the previous best limit set at Brookhaven National Laboratory (BNL) [1]. This thesis presents the analysis of the Run 2/3 data, focussing on using the straw tracker detectors to measure an oscillation in the vertical angle of the muon precession plane to search for an EDM.
A standalone simulation is developed to study the experimental EDM sensitivity, enabling fast evaluation of the main systematics. The radial field is found to be the dominant error if not measured to better than 1ppm precision. A new measurement technique is developed to measure this, with the results of the Run 5 radial field scan successfully achieving a 0.46ppm uncertainty, better than the target precision. The EDM limit setting methods themselves are discussed and compared in order to select the optimal one for the analysis. Since the trackers are a vital part of this measurement, characterisation and optimisation of their performance is also considered. Various studies are performed, including an investigation into the optimal operating voltage and an in-depth study of crosstalk. A new time-dependent tracker effect is discovered which directly impacts the EDM analyses, which is evaluated and a correction developed.
Run 2/3 data is analysed to perform a blinded search for a muon EDM, including corrections and systematic uncertainties. The results, if found to be zero when unblinded, will set a new world limit on the muon EDM of 5.9 ×10−20 e·cm. This improves on the previous value by a factor of 3.



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