A gravitation laboratory experiment invariably consists of one or more field masses interacting with a test mass, usually suspended on a torsion pendulum. Due to the physical dimensions of the interacting masses, comparable to their mutual distance, an important element of the experiment is a careful characterization and modeling of the interaction.
The LAG (Liquid Actuated Gravity) experiment aims to develop and test a new kind of field mass for a laboratory gravity experiment based on a varying amount a liquid in a container near the test mass. The change of the liquid level modulates the force and allows a reduction of low frequency noises. The LAG’s liquid actuator should introduce less systematic errors than the solid field masses used so far in similar experiments. Within LAG experiment duration,  we aim to build a prototype of a liquid field mass to be tested on  PETER, a unique instrument based on a double torsion.