Sensor Noise in <i>LISA Pathfinder</i>: In-Flight Performance of the Optical Test Mass Readout
M. Armano, H. Audley, J. Baird, Pierre Binétruy, M. Born, D. Bortoluzzi, Nico Brandt, E. Castelli, A. Cavalleri, A. Cesarini, A. M. Cruise, K. Danzmann, M. de Deus Silva, I. Diepholz, George Dixon, R. Dolesi, L. Ferraioli, V. Ferroni, E. D. Fitzsimons, R. Flatscher, M. Freschi, A. García, R. Gerndt, L. Gesa, D. Giardini, F. Gibert, R. Giusteri, C. Grimani, J. Grzymisch, Felipe Guzmán, I. Harrison, Marie-Sophie Hartig, Gerhard Heinzel, M. Hewitson, D. Hollington, D. Hoyland, M. Hueller, H. Inchauspé, O. Jennrich, P. Jetzer, Ulrich Johann, B. Johlander, Nikolaos Karnesis, B. Kaune, C. J. Killow, Natalia Korsakova, J. A. Lobo, L. Liu, J. P. López-Zaragoza, R. Maarschalkerweerd, D. Mance, V. Martín, L. Martin-Polo, F. Martín-Porqueras, J. Martino, P. W. McNamara, José F. G. Mendes, L. Mendes, N. Meshksar, A. Monsky, M. Nofrarías, S. Paczkowski, M. Perreur-Lloyd, Antoine Petiteau, P. Pivato, E. Plagnol, J. Ramos-Castro, J. Reiche, F. Rivas, D. I. Robertson, G. Russano, Jose Sanjuán, J. Slutsky, Carlos F. Sopuerta, Frank Steier, T. J. Sumner, D. Texier, James Ira Thorpe, D. Vetrugno, S. Vitale, Vinzenz Wand, Gudrun Wanner, H. Ward, Peter Wass, W. J. Weber, L. Wissel, A. Wittchen, P. Zweifel
Abstract
We report on the first subpicometer interferometer flown in space. It was part of ESA's Laser Interferometer Space Antenna (LISA) Pathfinder mission and performed the fundamental measurement of the positional and angular motion of two free-falling test masses. The interferometer worked immediately, stably, and reliably from switch on until the end of the mission with exceptionally low residual noise of 32.0_{-1.7}^{+2.4} fm/sqrt[Hz], significantly better than required. We present an upper limit for the sensor performance at millihertz frequencies and a model for the measured sensitivity above 200 mHz.