Capacitive sensing of test mass motion with nanometer precision over millimeter-wide sensing gaps for space-borne gravitational reference sensors

M. Armano , H. Audley , G. Auger (1) , J. Baird , M. Bassan , P. Binetruy (1) , M. Born , D. Bortoluzzi , N. Brandt , M. Caleno , A. Cavalleri , A. Cesarini , A.M. Cruise , K. Danzmann , M. de Deus Silva , R. de Rosa , L. Di Fiore , I. Diepholz , G. Dixon , R. Dolesi , N. Dunbar , L. Ferraioli , V. Ferroni , E.D. Fitzsimons , R. Flatscher , M. Freschi , C. García Marirrodriga , R. Gerndt , L. Gesa , F. Gibert , D. Giardini , R. Giusteri , A. Grado , C. Grimani , J. Grzymisch , I. Harrison , G. Heinzel , M. Hewitson , D. Hollington , D. Hoyland , M. Hueller , H. Inchauspé (1) , O. Jennrich , P. Jetzer , B. Johlander , N. Karnesis , B. Kaune , N. Korsakova , C.J. Killow , J.A. Lobo , I. Lloro , L. Liu , J.P. López-Zaragoza , R. Maarschalkerweerd , D. Mance , V. Martín , L. Martin-Polo , J. Martino (1) , F. Martin-Porqueras , S. Madden , I. Mateos , P.W. Mcnamara , J. Mendes , L. Mendes , N. Meshksar , M. Nofrarias , S. Paczkowski , M. Perreur-Lloyd , A. Petiteau (1) , P. Pivato , E. Plagnol (1) , P. Prat (1) , U. Ragnit , J. Ramos-Castro , J. Reiche , D.I. Robertson , H. Rozemeijer , F. Rivas , G. Russano , P. Sarra , A. Schleicher , J. Slutsky , C.F. Sopuerta , R. Stanga , T.J. Sumner , D. Texier , J.I. Thorpe , C. Trenkel , M. Tröbs , D. Vetrugno , S. Vitale , G. Wanner , H. Ward , P.J. Wass , D. Wealthy , W.J. Weber , L. Wissel , A. Wittchen , A. Zambotti , C. Zanoni , T. Ziegler , P. Zweifel

1 APC (UMR_7164) - AstroParticule et Cosmologie

We report on the performance of the capacitive gap-sensing system of the Gravitational Reference Sensor on board the LISA Pathfinder spacecraft. From in-flight measurements, the system has demonstrated a performance, down to 1 mHz, that is ranging between 0.7 and 1.8  aF Hz-1/2. That translates into a sensing noise of the test mass motion within 1.2 and 2.4  nm Hz-1/2 in displacement and within 83 and 170  nrad Hz-1/2 in rotation. This matches the performance goals for LISA Pathfinder, and it allows the successful implementation of the gravitational waves observatory LISA. A 1/f tail has been observed for frequencies below 1 mHz, the tail has been investigated in detail with dedicated in-flight measurements, and a model is presented in the paper. A projection of such noise to frequencies below 0.1 mHz shows that an improvement of performance at those frequencies is desirable for the next generation of gravitational reference sensors for space-borne gravitational waves observation.

Keywords: detector: performance; LISA; gravitational radiation detector; gravitational radiation; gravitational radiation: direct detection; gravitation; noise; observatory; rotation; gap

Domains: Instrumentation and Detectors [physics.ins-det]; General Relativity and Quantum Cosmology [gr-qc]

M. Armano, H. Audley, G. Auger, J. Baird, M. Bassan, et al.. Capacitive sensing of test mass motion with nanometer precision over millimeter-wide sensing gaps for space-borne gravitational reference sensors. Physical Review D, 2017, 96 (6), pp.062004. ⟨10.1103/PhysRevD.96.062004⟩. ⟨hal-01646020⟩