Atomic parity violation measurements in the highly forbidden 6S 1/2-7S1/2 caesium transition. - I. Theoretical analysis, procedure and apparatus

Abstract

2014 Cet article est la première partie d'une présentation détaillée des mesures de violation de parité réalisées sur deux composantes hyperfines de la transition très interdite 6S-7S de l'atome de césium. Lors de l'excitation par un faisceau laser polarisé circulairement dans un champ électrique statique il y a interférence entre une amplitude électromagnétique induite par le champ et l'amplitude induite par l'interaction faible. Cette interférence engendre dans la polarisation électronique de l'état 7S une contribution qui se comporte comme un vecteur polaire lorsqu'on inverse la chiralité de l'expérience. En principe seule cette contribution est observée dans la direction d'observation choisie. On la détecte par l'intermédiaire du taux de polarisation circulaire de la fluorescence 7S-6P1/2. Par effet Hanle dans un champ magnétique appliqué périodiquement, on observe de la même manière la contribution conservant la parité, ce qui permet de calibrer l'expérience. Le résultat final est le rapport Im Epv1/03B2 de l'amplitude violant la parité à la polarisabilité vectorielle. Notre valeur est ( 2014 1,56 ± 0,17 (stat.) ± 0,12 (syst.)) mV/cm. Ci-après nous donnons les expressions de tous les signaux atomiques disponibles, puis nous décrivons l'appareillage et les méthodes expérimentales.Abstract. 2014 This paper is the first part of a detailed presentation of parity violation measurements performed in two hfs components of the highly forbidden 6S-7S transition of the Cs atom. Under excitation by a circularly polarized laser in a dc electric field, interference takes place between an electromagnetic amplitude induced by the field and the parity-violating amplitude induced by weak interactions. This interference gives rise in the electronic polarization of the 7S state to a contribution which behaves like a vector when the handedness of the experiment is reversed In principle, only this contribution is observed in the chosen direction of observation. Detection proceeds through the circular polarization ratio of the 7S-6P1/2 fluorescence. By Hanle effect in a magnetic field applied periodically, the parity-conserving contribution is observed in the same way and used to calibrate the experiment. The final result is the ratio Im Epv1/03B2 of the parity-violating amplitude to the vector polarizability. Our value is ( 2014 1.56 ± 0.17 (stat.) ± 0.12 (syst.)) mV/cm. In what follows, we give the formulae for all available atomic signals and describe the apparatus and procedures.

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

“…The best directly measured scalar magnetometer sensitivity is equal 7 fT/Hz 1/2 with a measurement volume of 1.5 cm 3 [12], while estimates of fundamental sensitivity per unit measurement volume for various types of scalar alkali-metal magnetometers range from several fT cm 3/2 /Hz 1/2 [13, 14] to about 1 fT cm 3/2 /Hz 1/2 [12]. Here we describe a new type of scalar atomic magnetometer using multi-pass vapor cells [15,16] and operating in a pulsed pump-probe mode [17] to achieve magnetic field sensitivity of 0.54 fT/Hz 1/2 with a measurement volume of 0.66 cm 3 in each multi-pass cell. The magnetometer sensitivity approaches, for the first time, the fundamental limit set by Rb-Rb collisions.…”

Atomic parity violation measurements in the highly forbidden 6S 1/2 - 7S1/2 caesium transition. - III. Data acquisition and processing. Results and implications

“…Part I [1] presented the theoretical analysis and the experimental procedure and apparatus. Part II [2] presented the analysis and control of systematic effects.…”

“…In the first section, § 4.1 attempts at a complete description of the data acquisition sequences and of the detection chain. The experimental complexity was unavoidable in order to satisfy two requirements : (1) control in real-time of all systematic effects, whose relevance was demonstrated in part II: (2) collection of maximum information, with both redundancy and cross-checks, as protection against possible omitted systematics. The data processing as performed just after the runs is described in § 4.2.…”

The Cs 6S-7S-6P3/2 forbidden three-level system : analytical description of the inhibited fluorescence and optical rotation spectra

“…Starting from equations (23) and (24) we are now going to calculate the total 7S population in order to obtain the 7S --+> 6P,/2 fluorescence in the presence of the probe beam.…”