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Capacitance Gauge
The equivalence principle is one of the fundamental postulates of relativity, which in turn defines our understanding of gravity and consequently phenomena such as black holes. POEM is an experiment designed to test the equivalence principle. The capacitance gauge system in POEM, designed to precisely measure the velocity and position of test masses in the experiment, was analysed and sources of error were quantified. Further, design and implementation of a microcontroller was completed to allow communication with embedded electronics in the experiment, which was then tested in a simulation of the full capacitance gauge system. Spurious acceleration of the test masses caused by the drive electrodes in the capacitance gauges was found to be 8.*10-25g, whereas offset of the test mass from the horizontal axis revealed an acceleration of 1.2*10-16 g. Calibration of the capacitance gauge system yielded a sensitivity of 4.982mV V-1 mm-1 .