Cold atom gravity gradiometer for field applications

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Lamb, Andrew Anuerin (2019). Cold atom gravity gradiometer for field applications. University of Birmingham. Ph.D.

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Abstract

This thesis presents the first efficient implementation of a 87Rb prism MOT gravity gradiometer. The resulting portable system (weight <50 kg and volume <0.1 m3) is capable of producing atom numbers up to 5 × 107 with typical cloud temperatures of 7.8 µK. Combining with a robust control system and a 5 m delivery umbilical the effectiveness has been demonstrated in a non-laboratory environment. A measurement campaign to detect a buried maintenance tunnel, with an expected signal size of 230 E, was performed during March 2018. An ambient temperature range of -0.5 to 10.2 ◦C and wind speeds in excess of 10 m/s provided adverse operating conditions that imposed no loss of functionality on the sensor. Resulting data shows a trend indicative of the tunnel with long term drift limiting fit error to 140 E. A second campaign was performed to detect a signal of 280 E generated by a lead mass of 450 kg in a laboratory environment, with ambient temperature fluctuations of 0.5 ◦C recorded. Sensor drift of ∼220 E/hour was seen making it impossible to discern the expected signal. Correlation between the Raman sideband-to-carrier amplitude ratio and measured gradient signal was identified and linked to ambient temperature fluctuations.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):