Optical Spectroscopy of Tungsten Carbide for Electron Electric Dipole Moment Search.

Searching for a permanent electron electric dipole moment (EDM) is a powerful tool to probe for physics beyond the Standard Model. We identified the X3Delta1 ground state of tungsten carbide (WC) molecule as a candidate system for the electron EDM search. This work focuses on two main parts: one being devoted to the development of various forms of intense molecular beam sources, and the other consisting of the analysis of the EDM sensitive molecular transition. Initially, we developed a supersonic beam of WC molecules in a continuous form; however, this approach had several limitations. To overcome these issues, we designed a second generation beam source in a pulse form. We used laser induced fluorescence (LIF) spectroscopy on a pulse supersonic beam to detect the molecules through the [20.6]Omega=2, v'=4 <- X3Delta1, v"=0 transition. The hyperfine structure and the Omega-doublet of the transition were measured, which were essential for estimating the size of the potential systematic uncertainties for the electron EDM measurement. For further suppression of systematic uncertainty, an EDM measurement scheme utilizing the g-factor crossing point of the Omega-doublet levels was studied. On the other hand, flux and internal temperature of the molecular beam were characterized, setting the limit of the statistical uncertainty of the EDM experiment. With the given results, the prospect of an electron EDM experiment with the X3Delta1 state of WC molecule is discussed.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/95967/1/jeonlee_1.pd