The laboratory realizes and disseminates the national standard of gravitational acceleration by means of a transportable ballistic (rise-and-fall) absolute gravimeter, conceived, designed, developed, and built at INRiM. The instrument is based on the interferometric measurement of the vertical motion of a body in free fall. The measurement principle consists in the extremely accurate determination of the trajectory of the falling object, from which the local value of gravitational acceleration is derived. The system is designed to operate directly in situ, enabling absolute measurements with a relative expanded uncertainty of 1.1 × 10⁻⁹, among the best currently achievable at the international level.
The transportability of the instrument makes it possible to carry out measurement campaigns at metrology laboratories, geophysical observatories, and sites of scientific interest, ensuring the traceability of gravitational acceleration measurements and contributing to the consistency of national and international gravimetric comparison networks. The laboratory's measurement capabilities are of fundamental importance in applications requiring extremely high accuracy, such as the determination of fundamental constants, the characterization of measurement standards and the correction of high-precision mass measurements.
At the research level, the laboratory develops new technologies and methodologies to further improve the accuracy and stability of absolute gravity measurements. Activities include the optimization of interferometric systems, the study and modeling of environmental effects (vibrations, temperature variations, atmospheric pressure), the analysis of tidal perturbations, and the implementation of advanced data processing procedures.
These developments aim to reduce measurement uncertainty, increase the operational reliability of the instrument, and broaden the field of application of gravimetric measurements in metrological and geophysical contexts, including complex environments and non-ideal operating conditions.