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abstract: Seeking an upper limit of the Neutron Electric Dipole Moment (nEDM) is a test of charge-parity (CP) violation beyond the Standard Model. The present experimentally tested nEDM upper limit is 3x10^(26) e cm. An experiment to be performed at the Oak Ridge National Lab Spallation Neutron Source (SNS) facility seeks to reach the 3x10^(28) e cm limit. The experiment is designed to probe for a dependence of the neutron's Larmor precession frequency on an applied electric eld. The experiment will use polarized helium-3 (3He) as a comagnetometer, polarization analyzer, and detector. Systematic influences on the nEDM measurement investigated in this thesis include (a) room temperature measurements on polarized 3He in a measurement cell made from the same materials as the nEDM experiment, (b) research and development of the Superconducting QUantum Interference Devices (SQUID) which will be used in the nEDM experiment, (c) design contributions for an experiment with nearly all the same conditions as will be present in the nEDM experiment, and (d) scintillation studies in superfluid helium II generated from alpha particles which are fundamentally similar to the nEDM scintillation process. The result of this work are steps toward achievement of a new upper limit for the nEDM experiment at the SNS facility. / Dissertation/Thesis / Doctoral Dissertation Physics 2019

Charge-Conjugation (C) and Charge-Conjugation-Parity (CP) Violation is one of the three Sakharov conditions to explain via baryogenesis the observed baryon asymmetry of the universe (BAU). The Standard Model of particle physics (SM) contains sources of CP violation, but cannot explain the BAU. This motivates searches for new physics beyond the standard model (BSM) which address the Sakharov criteria, including high-precision searches for new sources of CPV in systems for which the SM contribution is small, but larger effects may be present in BSM theories. A promising example is the search for the electric dipole moment of the neutron (nEDM), which is a novel system to observe CPV due to the initial and final state being identical. A non-zero measurement necessarily requires violation of P and T discrete symmetries; invoking CPT invariance requires that CP is violated. There are BSM theories which predict a magnitude for the nEDM larger than SM predictions, so that such studies are beneficial at setting constraints on new physics. The current experimental limit of dn < 3.0 x 10-26 e cm at 90% CL as set by the Institut Laue-Langevin (ILL) [1] was largely limited by systematic effects related to the magnetic field. The research presented here supported technical progress toward a new measurement of the nEDM, with the goal of improving the result by an order of magnitude. A novel approach to the problem of limiting systematics is proposed, studied in Monte Carlo simulations, and an optimized prototype was constructed for use in a magnetic resonance experiment.

This thesis describes the physics, design, and construction of an experiment to measure the electric dipole moment (EDM) of the electron. In the experiment, laser-cooled Cs atoms will be held in an optical dipole force trap in the presence of applied electric and magnetic fields. The signature of an electron EDM is a first-order electric field shift of the Zeeman resonance frequency of the Cs ground state. We present an analysis of the systematic and statistical errors of this experiment, which shows that the experiment should have a sensitivity of the order of 10⁻²⁹ e-cm. We pay particular attention to potential light-shift induced errors and to magnetic field noise. We also present the design and experimental results for a cold Cs atom source, high voltage field plates, optical trapping field in a resonant build-up cavity, noval titanim ultrahigh vacuum system, and magnetic sheilding system. These results show that a measurement of the electron edm at the level of 10⁻²⁹ e-cm. should be feasible. / text

The ACME collaboration has completed a measurement setting a new upper limit on the size of the electron's permanent electric dipole moment (EDM). The existence of the EDM is well motivated by theories extending the standard model of particle physics, with predicted sizes very close to the current experimental limit. The new limit was set by measuring spin precession within the metastable H state of the polar molecule thorium monoxide (ThO). A particular focus here is on the automated data acquisition system developed to search for a precession phase odd under internal and external reversal of the electric field. Automated switching of many different experimental controls allowed a rapid diagnosis of major systematics, including the dominant systematic caused by non-reversing electric fields and laser polarization gradients. Polarimetry measurements made it possible to quantify and minimize the polarization gradients in our state preparation and probe lasers. Three separate measurements were used to determine the electric field that did not reverse when we tried to switch the field direction. The new bound of |de|< 8.7 &times; 10^-29 e cm is over an order of magnitude smaller than previous limits, and strongly limits T-violating physics at TeV energy scales. / Physics

De nos jours, l'incomplétude du modèle standard des particules est largement reconnue. L'une de ses failles les plus évidentes est le manque d'explication de l'énorme excédent de matière par rapport à l'antimatière dans l'univers, que l'on appelle l'asymétrie baryonique de l'univers. De nouvelles violations de CP (conjugaison de charge et parité spatiale) absentes dans le modèle standard sont supposées être responsables de cette asymétrie. Une telle violation pourrait être observée dans la matière ordinaire à travers un ensemble d'interactions violant les symétries de parité et de renversement du temps (impaires pour P,T) dont les prépondérantes sont les interactions du moment dipolaire électrique de l'électron (eEDM), électron-nucléon scalaire-pseudoscalaire (enSPS) et du moment quadripolaire magnétique nucléaire (nMQM). Ainsi, une preuve expérimentale d'une constante d'interaction impaire pour P,T serait une preuve de cette nouvelle physique au-delà du modèle standard. Le calcul des paramètres moléculaires correspondants est réalisé en utilisant une approche d'interaction de configurations relativiste à quatre composantes dans des molécules diatomiques polaires contenant un actinide, qui sont des systèmes particulièrement appropriés pour les expèriences eEDM, tels que ThO qui a permis d'assigner à l'eEDM la borne supérieure la plus contraignante et ThF+ qui sera utilisé dans une expérience à venir. Ces résultats sont d'une importance cruciale dans l'interprétation des mesures puisque les constantes fondamentales ne peuvent être évaluées que si l'on associe les mesures de décalages énergétiques et les paramètres moléculaires théoriques. / Nowadays, the incompleteness of the Standard Model of particles is largely acknowledged. One of its most obvious shortcomings is the lack of explanation for the huge surplus of matter over antimatter in the universe, the so-called Baryon Asymmetry of the Universe. New CP (Charge conjugation and spatial Parity) violations absent in the SM are assumed to be responsible for this asymmetry. Such a violation could be observed in ordinary matter through a set of interactions violating both parity and time-reversal symmetries (P,T-odd), among which the preponderant ones are the electron Electric Dipole Moment (eEDM), the electron-nucleon scalar-pseudoscalar (enSPS) and the nuclear magnetic quadrupole moment (nMQM) interactions. Hence, an experimental evidence of a non-zero P,T-odd interaction constant would be a probe of this New Physics beyond the Standard Model. The calculation of the corresponding molecular parameters is performed by making use of an elaborate four-component relativistic configuration interaction approach in polar diatomic molecules containing an actinide, that are particularly adequate systems for eEDM experiments, such as ThO that allowed for assigning the most constraining upper bound on the eEDM and ThF+ that will be used in a forthcoming experiment. Those results will be of crucial importance in the interpretation of the measurements since the fundamental constants can only be evaluated if one combines both experimental energy shift measurements and theoretical molecular parameters.

We give a brief introduction to atomic physics and the motivation behind our experiments in the first chapter. The electron’s electric dipole moment is an interesting quantity which is yet to be measured. In the 3rd Chapter, we use the technique of chopped non-linear magneto-optic rotation (NMOR) in a room temperature Cs vapor cell to measure the permanent electric dipole moment (EDM) in the atom. The cell has paraffin coating on the walls to increase the relaxation time. The signature of the EDM is a shift in the Larmor precession frequency correlated with the application of an E field. We analyze errors in the technique, and show that the main source of systematic error is the appearance of a longitudinal magnetic field when an electric field is applied. This error can be eliminated by doing measurements on the two ground hyperfine levels. Using an E field of 2.6 kV/cm, we place an upper limit on the electron EDM of 2.9 × 10−22 e-cm with 95% confidence. This limit can be increased by 7 orders-of-magnitude—and brought below the current best experimental value. We give future directions for how this may be achieved. In chapter 4, we examine the Hanle effect for linear and circularly polarized light for different ground states and we find opposite behavior in the transmission signal. In one case, it shifts from enhanced transmission to enhanced absorption and vice-versa in the other case. In Chapter 5, we study the transmission spectrum at different temperatures and device a way to find the number density. We then verify the Clausius-Clapeyron equation and also find the latent heat of vaporization of Cs. Finally, we wrap up with conclusions and future directions.

A new neutron Electric Dipole Moment (nEDM) experiment was proposed to be commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source (SNS) of the Oak Ridge National Laboratory (ORNL). The underlying theme of this experiment (first conceived by Golub and Lamoreaux in 1994) is the search for new physics beyond the Standard Model of particle physics. The discovery of a non-zero nEDM would be of revolutionary importance to physics, with the discovery of such providing for evidence for new-beyond-the-Standard-Model physics required for a resolution to the unresolved puzzle of why the universe is dominated by matter, as opposed to anti-matter. A first demonstration of a new magnetic field monitoring system for a neutron electric dipole moment experiment is presented. The system is designed to reconstruct the vector components of the magnetic field in the interior measurement region solely from exterior measurements. The results highlight the potential for the implementation of an improved system in an upcoming neutron electric dipole moment experiment to be carried out at the Spallation Neutron Source at Oak Ridge National Laboratory.

The Finite Difference Time Domain (FDTD) Method has been a powerful tool in numerical simulation of electromagnetic (EM) problems for decades. In recent years, it has also been applied to biomedical research to investigate the interaction between EM waves and biological tissues. In Wireless Body Area Networks (WBANs) studies, to better understand the localization problem within the body, an accurate source/receiver model must be investigated. However, the traditional source models in FDTD involve effective volume and may cause error in near field arbitrary direction. This thesis reviews the basic mathematical and numerical foundation of the Finite Difference Time Domain method and the material properties needed when modeling a human body in FDTD. Then Coincident Phase Centers (CPCs) point sources models have been introduced which provide nearly the same accuracy at the distances as small as 3 unit cells from the phase center. Simultaneously, this model outperforms the usual sources in the near field when an arbitrary direction of the electric or magnetic dipole moment is required.