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Communication Dans Un Congrès Année : 2005

The Cs Parity Violation experiment in Paris: E1^{pv} determination within 2x10^{-13} atomic units

Jocelyne Guéna
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Michel Lintz

Résumé

A precise atomic Parity Violation (APV) experiment provides an original test of the electron-nuclear weak interaction mediated by the neutral vector boson Z_{0}, a test complementary to high energy experiments. It consists in measuring a left-right asymmetry of order 10^{-6} in the atomic interaction with a radiation field resonant for the forbidden 6S-7S cesium transition. It involves the transition dipole amplitude E1^{pv} of only 10^{-11} ea_0. Our pulsed pump-probe experiment, carried out in a vapor cell submitted to a longitudinal E-field, provides a novel method of APV measurement by exploiting the amplification of the asymmetry by stimulated emission. After pulsed excitation of the forbidden transition in presence of a parallel electric field E, the probe beam resonant for the 7S-6P_{3/2} transition is transiently amplified. Polarization analysis of the probe allows us to detect selectively a {\it chiral} contribution arising from E1^{pv}. The plane defined by the excitation laser polarization and E is a plane of symmetry of the experiment. If the probe linear polarization is at the input of the vapor {\it inside} the plane of symmetry, at the cell output {\it it deviates from this plane} by a small angle \theta^{pv}=-ImE1^{pv}/beta E (beta: 6S - 7S transition polarizability) which changes sign when the direction of E is reversed. This is a manifestation of the PV linear dichroism, whose eigenaxes are offset by 45° from the symmetry axes. We have increased by a factor of 3.5 both the sensitivity and the accuracy of our initial 9% result {1}, thanks essentially to a polarization-tilt magnifier, upgraded cesium cells (non-reflective windows with a ring-shape metal-coating for better application of E, together with a 1% in-situ determination of E. Latest results {2} yielding a 2.6\% accurate determination of E1^{pv} will be presented (Fig.1). Besides, a new project for APV measurements to the 0.1\% precision level on the 6S-7S Cs transition is proposed {3}. {1} J.~Guéna et al., Phys. Rev. Lett. 90, 143001 (2003). {2} J.~Guéna et al., arXiv:physics/0412017, to appear in Phys. Rev. A (2005). {3} J.~Guéna, M.~Lintz and M.A.~Bouchiat, J. Opt. Soc. Am., B22, 21 (2005). A precise atomic Parity Violation (APV) experiment provides an original test of the electron-nuclear weak interaction mediated by the neutral vector boson Z_{0}, a test complementary to high energy experiments. It consists in measuring a left-right asymmetry of order 10^{-6} in the atomic interaction with a radiation field resonant for the forbidden 6S-7S cesium transition. It involves the transition dipole amplitude E1^{pv} of only 10^{-11} ea_0. Our pulsed pump-probe experiment, carried out in a vapor cell submitted to a longitudinal E-field, provides a novel method of APV measurement by exploiting the amplification of the asymmetry by stimulated emission. After pulsed excitation of the forbidden transition in presence of a parallel electric field E, the probe beam resonant for the 7S-6P_{3/2} transition is transiently amplified. Polarization analysis of the probe allows us to detect selectively a {\it chiral} contribution arising from E1^{pv}. The plane defined by the excitation laser polarization and E is a plane of symmetry of the experiment. If the probe linear polarization is at the input of the vapor {\it inside} the plane of symmetry, at the cell output {\it it deviates from this plane} by a small angle \theta^{pv}=-ImE1^{pv}/beta E (beta: 6S - 7S transition polarizability) which changes sign when the direction of E is reversed. This is a manifestation of the PV linear dichroism, whose eigenaxes are offset by 45° from the symmetry axes. We have increased by a factor of 3.5 both the sensitivity and the accuracy of our initial 9% result {1}, thanks essentially to a polarization-tilt magnifier, upgraded cesium cells (non-reflective windows with a ring-shape metal-coating for better application of E, together with a 1% in-situ determination of E. Latest results {2} yielding a 2.6\% accurate determination of E1^{pv} will be presented (Fig.1). Besides, a new project for APV measurements to the 0.1\% precision level on the 6S-7S Cs transition is proposed {3}. {1} J.~Guéna et al., Phys. Rev. Lett. 90, 143001 (2003). {2} J.~Guéna et al., arXiv:physics/0412017, to appear in Phys. Rev. A (2005). {3} J.~Guéna, M.~Lintz and M.A.~Bouchiat, J. Opt. Soc. Am., B22, 21 (2005).
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hal-00019023 , version 1 (14-02-2006)

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  • HAL Id : hal-00019023 , version 1

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Jocelyne Guéna, Michel Lintz, Marie-Anne Bouchiat. The Cs Parity Violation experiment in Paris: E1^{pv} determination within 2x10^{-13} atomic units. SFP2005 Congrès Général de la SFP et de la BPS, 2005, Lille, France. ⟨hal-00019023⟩
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