Result of the MICROSCOPE weak equivalence principle test
Pierre Touboul, Gilles Métris, Manuel Rodrigues, Joël Bergé, Alain Robert, Quentin Baghi, Yves André, Judicaël Bedouet, Damien Boulanger, Stefanie Bremer, Patrice Carle, Ratana Chhun, Bruno Christophe, Valerio Cipolla, Thibault Damour, Pascale Danto, Louis Demange, H. Dittus, Océane Dhuicque, P. Fayet, Bernard Foulon, Pierre-Yves Guidotti, Daniel Hagedorn, Émilie Hardy, Phuong-Anh Huynh, Patrick Kayser, Stéphanie Lala, Cláus Lämmerzahl, Vincent Lebat, Françoise Liorzou, Meike List, F. Löffler, Isabelle Panet, Martin Pernot-Borràs, Laurent Perraud, S. Pires, Benjamin Pouilloux, Pascal Prieur, Alexandre Rebray, Serge Reynaud, Benny Rievers, Hanns Selig, Laura Serron, T. J. Sumner, Nicolas R. Tanguy, Patrizia Torresi, Pieter Visser
Abstract
Abstract The space mission MICROSCOPE dedicated to the test of the equivalence principle (EP) operated from April 25, 2016 until the deactivation of the satellite on October 16, 2018. In this analysis we compare the free-fall accelerations ( a A and a B ) of two test masses in terms of the Eötvös parameter <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>η</mml:mi> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow> <mml:mtext>A,B</mml:mtext> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mo>=</mml:mo> <mml:mn>2</mml:mn> <mml:mfrac> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> </mml:mrow> </mml:msub> <mml:mo>−</mml:mo> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> </mml:mrow> </mml:msub> <mml:mo>+</mml:mo> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfrac> </mml:math> . No EP violation has been detected for two test masses, made from platinum and titanium alloys, in a sequence of 19 segments lasting from 13 to 198 h down to the limit of the statistical error which is smaller than 10 −14 for η (Ti, Pt). Accumulating data from all segments leads to η (Ti, Pt) = [−1.5 ± 2.3 (stat) ± 1.5 (syst)] × 10 −15 showing no EP violation at the level of 2.7 × 10 −15 if we combine stochastic and systematic errors quadratically. This represents an improvement of almost two orders of magnitude with respect to the previous best such test performed by the Eöt-Wash group. The reliability of this limit has been verified by comparing the free falls of two test masses of the same composition (platinum) leading to a null Eötvös parameter with a statistical uncertainty of 1.1 × 10 −15 .