Dependence of the sensitivity on the orientation for a free-fall atom gravimeter.

The cold atom absolute gravimeters are intrinsically sensitive to its orientation due to the Coriolis effect, which should be understood clearly and compensated for field applications. The sensitivity on the orientation for a free-fall atom gravimeter is investigated in this paper. The apparatus is simplified and improved a lot such that fast adjustment and measurement could be carried out within 20 minutes. From the experimental results, it is found that the orientation angle has a dominant influence on the absolute gravity measurement, especially when the horizontal velocity of atoms is non-negligible. Besides, the magnitude and direction of average horizontal velocity of the detected atoms are obtained in this experiment. In particular, the direction of East-West has been measured by the atom gravimeter itself, such that gravity bias arising from Coriolis effect is estimated precisely.