Talk detail

Participant	Nobili, Anna M.
Institution	Department of Physics "E. Fermi", University of Pisa - Largo Bruno Pontecorvo 3, 56127 Pisa - Pisa - Italy - Italy

Session	PT6	Accepted		Order	Time
Talk	Oral abstract	Title	Testing the Equivalence Principle in Space After MICROSCOPE
Coauthors
Abstract	Tests of the Weak Equivalence Principle (WEP) can reveal a new, composition dependent, force of nature or disprove many models of new physics. For the first time this test is being successfully carried out in space by the MICROSCOPE satellite. Early results show no violation of the WEP sourced by the Earth for Pt and Ti test masses with random errors (after 8.26 d of integration time) of about 1 part in 1e14, and systematic errors of the same magnitude. This result improves by about 10 times over the best ground tests with rotating torsion balances despite 70 times less sensitivity to differential accelerations, thanks to the much stronger driving signal in orbit. Many lessons can be learned from the success and the limiting factors of MICROSCOPE. We analyze random and systematic errors, and discuss the key changes that will lead to higher precision tests.
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Session	PT3	Accepted		Order	Time
Talk	Oral abstract	Title	Tidal Effects in Gravitation Measurements by Light-Pulse Atom Interferometry
Coauthors
Abstract	The acceleration measured by a light-pulse Atom Interferometer (AI) in a non uniform gravitational field systematically deviates from the true acceleration by a term to first order in the gravity gradient. A recent proposal to (ideally) cancel out the gravity gradient by means of an appropriate frequency shift of one laser pulse overcomes the shortcomings of previous proposals based on physical reversal of the instrument axis, and has already been shown to be effective. However, it does not eliminate the deviation. This tidal acceleration error affects the absolute measurement of the local gravitational acceleration at a level that is relevant for the current uncertainty, but it is negligible in drop tests of the Universality of Free Fall with a dual AI as long as they can rely on the same laser frequency to interrogate the different atoms species. In gravity gradiometers based on atom interferometry and used for the measurement of the universal constant of gravity and the detection of gravitational waves the relevance of the deviation needs to be assessed relative to the target of the experiment.
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