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Étude des performances d'un gravimètre atomique absolu : sensibilité limite et exactitude préliminaire

Abstract : Atom interferometry is applied to absolute measurement of gravity acceleration $g$, to provide an accurate value for the realization of the LNE watt balance. The atomic source is obtained from a cloud of cold 87 Rubidium atoms. Two vertical counter-propagating are used to generate stimulated Raman transitions, that separate the wave-packets and make them interfere. During the transitions, the phase difference between the beams is printed on the phase of the free-falling atoms. Then the atomic phase shift between the two vertical paths becomes sensitive to the atom acceleration and allows obtaining an accurate value of $g$. A part of this manuscript is dedicated to the study of noise sources which deteriorate the measurement sensitivity. In particular, we detail the vibrations contribution, which we are able to reduce by a factor of 3 to 10, depending on the configurations, thanks to the measurement of a seismometer and to its analog processing. The best reported sensitivity, in optimal environment, is $1,4~10^{-8}$~g/Hz$^{1/2}$. The study of the measurement accuracy also represents an important part of this work. Although the vacuum chamber was only temporary, we started to list the systematic shifts. According to two comparisons with well-known absolute gravimeters based on optical interferometry, our measurement shows a residual bias of $16~10^{-9}$~g.
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Submitted on : Thursday, August 28, 2008 - 11:34:58 PM
Last modification on : Wednesday, November 17, 2021 - 12:29:48 PM
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  • HAL Id : tel-00311422, version 4


Julien Le Gouët. Étude des performances d'un gravimètre atomique absolu : sensibilité limite et exactitude préliminaire. Physique Atomique [physics.atom-ph]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00311422v4⟩



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