The First Precision Measurement of the Electron Electric Dipole Moment in Trapped Molecular Ions

Gresh, Daniel

Graduate Thesis Or Dissertation

The First Precision Measurement of the Electron Electric Dipole Moment in Trapped Molecular Ions Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/8w32r5641

Abstract

A measurement of the permanent electric dipole moment of the electron (eEDM, d_e) is a direct probe of physics beyond the Standard Model. Our experiment makes a measurement of the eEDM in Hafnium Fluoride ions (HfF⁺) using a novel radiofrequency ion trap where we routinely achieve measurement coherence times of > 1 s. This thesis presents the result of our first generation eEDM measurement, where we measure d_e = (0.9±7.7_stat±1.7_syst) ✕ 10^-29e⋅cm, a value consistent with zero, which corresponds to a 90% confidence upper bound of |d_e|< 1.3 ✕ 10^-28 e ⋅ cm. This result was extracted from 313.8 hours of data. Our final eEDM measurement is limited by statistical sensitivity as opposed to systematic error.

This thesis additionally presents the results of broadband frequency comb velocity modulation spectroscopy of a candidate molecular ion for a future generation eEDM experiment, the Thorium Fluoride ion (ThF⁺). ThF⁺ is a promising candidate due to its larger effective electric field and its ³Δ₁ ground state; the ground state assignment was determined in this work. By extending a titanium-doped-sapphire frequency comb source to cover the 696 - 900 nm spectral region we measure a total of 3,260 cm^-1 (98 THz) of continuous spectra with 150 MHz resolution. We additionally acquire 400 cm^-1 of spectra in the 900 - 1000 nm region with targeted continuous-wave laser scans. We have measured and fit twenty-seven vibrational bands connecting fourteen distinct electronic states. We will discuss the assignment of the electronic ground state and the assignment of intermediate electronic states that can be used for state preparation and readout.

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