EGAS41 - Swansea University

41 st EGAS CP 127 Gdańsk 2009
Cold atoms gravimeter
Q. Bodart ∗ , S. Merlet, N. Malossi, A. Landragin, F. Pereira Dos Santos,
LNE-SYRTE, UMR 8630 CNRS, Observatoire de Paris, UPMC, 61 avenue de l’Observatoire,
75014 Paris, FRANCE
∗ Corresponding author: quentin.bodart@obspm.fr
In the frame of the watt balance project led by Laboratoire National de Metrologie et
d ′ Essais (LNE) and aiming at a new definition of the mass unit (the kilogram), SYRTE
develops an absolute gravimeter. It will enable to obtain an extremely precise measurement
of the gravity acceleration g. The principle of operation of this apparatus is based
on techniques of atomic interferometry using cooled atoms. In a first step, about hundred
millions atoms are captured in a magneto-optical trap. The atoms are cooled down to
a temperature close to 2.5 micro Kelvin, before being released. During their free fall,
they are submitted to a sequence of three laser pulses which split and recombine the
atomic wave packets. Finally, the phase shift between the two arms of the interferometer,
proportional to g, is deduced from the atomic state measurement at the output of
the interferometer. The instrument sensitivity is currently 2 10-8g for a 1s measurement
time, at the same level as the current State of the Art in classical absolute gravimeters.
The evaluation of systematic effects is in progress and should enable to reach a relative
accuracy of 10 − 9.
References
[1] S. Merlet, J. Le Gouët, Q. Bodart, A. Clairon, A. Landragin, P. Rouchon, F. Pereira
Dos Santos, Metrologia, 46, 87-94 (2009)
[2] J. Le Gouët, T. Mehlstubler, J. Kim, S. Merlet, A. Clairon, A. Landragin, F. Pereira
Dos Santos, Applied Physics B, 92 (2), 133-144 (2008)
[3] P. Cheinet, F. Pereira Dos Santos, T. Petelski, J. Le Gouët, J. Kim, K.T. Therkildsen,
A. Clairon, A. Landragin, Applied Physics B 84 (4), 643-646 (2006)
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