Experimental determination of gravitomagnetic effects by means of ring lasers

NEB 15 – Recent Developments in Gravity

Tartaglia, Angelo^1

Politecnico, INFN, corso Duca degli Abruzzi 24, 10129 Torino, Italy^1

关键词: Experimental determination;    Gran Sasso National Laboratory;    Gravitomagnetic effects;    International collaborations;    Lense-thirring effect;    Propagation of lights;    Three dimensional arrays;    University of Canterbury;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/453/1/012019/pdf
DOI  :  10.1088/1742-6596/453/1/012019

来源: IOP

【 摘 要 】

A new experiment aimed to the detection of the gravito-magnetic Lense-Thirring effect at the surface of the Earth will be presented; the name of the experiment is GINGER. The proposed technique is based on the behavior of light beams in ring-lasers, also known as gyrolasers. A three-dimensional array of ringlasers will be attached to a rigid "monument"; each ring will have a different orientation in space. Within the space-time of a rotating mass the propagation of light is indeed anisotropic; part of the anisotropy is purely kinematical (Sagnac effect), part is due to the interaction between the gravito-electric field of the source and the kinematical motion of the observer (de Sitter effect), finally there is a contribution from the gravito-magnetic component of the Earth (gravito-magnetic frame dragging or Lense-Thirring effect). In a ring-laser a light beam traveling counterclockwise is superposed to another beam traveling in the opposite sense. The anisotropy in the propagation leads to standing waves with slightly different frequencies in the two directions; the final effect is a beat frequency proportional to the size of the instrument and its effective rotation rate in space, including the gravito-magnetic drag. Current laser techniques and the performances of the best existing ring-lasers allow at the moment a sensitivity within one order of magnitude of the required accuracy for the detection of gravito-magnetic effects, so that the objective of GINGER is in the range of feasibility and aims to improve the sensitivity of a couple of orders of magnitude with respect to present. The experiment will be underground, probably in the Gran Sasso National Laboratories in Italy, and is based on an international collaboration among four Italian groups, the Technische Universitat Munchen and the University of Canterbury in Christchurch (NZ).