A Differential Accelerometer For Gravitational Gradiometry

In this work we present the preliminary work for developing a prototype of a new class of low frequency accelerometers for geodynamics studies and space applications. The sensor is suitable to be used in a gravity gradiometer (GG) system for land geophysical survey and gravity gradient measurements. A theoretical resolution of 1 Eötvös (1 E = 10–9 s–2) at one sample per second is achievable in a compact, lightweight (less than 2 Kg) portable instrument, operating at room temperature. The basic components of the sensor are two identical rigidly connected accelerometers separated by a 20 cm baseline vector and the useful signal is extracted as the subtraction of the two outputs, by means of an interferometric microwave readout system. The elastic structure will be engraved in a monocrystal of silicon, while the position transducer is a sapphire microwave dielectric resonator.