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1. Sensor noise in LISA Pathfinder : An extensive in-flight review of the angular and longitudinal interferometric measurement system

Author

M. Armano, H. Audley, J. Baird, P. Binetruy, M. Born, D. Bortoluzzi, N. Brandt, E. Castelli, A. Cavalleri, A. Cesarini, A. M. Cruise, K. Danzmann, M. de Deus Silva, I. Diepholz, G. 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, F. Guzman, I. Harrison, M-S Hartig, G. Hechenblaikner, G. Heinzel, M. Hewitson, D. Hollington, D. Hoyland, M. Hueller, H. Inchauspé, O. Jennrich, P. Jetzer, U. Johann, B. Johlander, N. Karnesis, B. Kaune, C. J. Killow, N. Korsakova, J. A. Lobo, J. P. López-Zaragoza, R. Maarschalkerweerd, D. Mance, V. Martín, L. Martin-Polo, F. Martin-Porqueras, J. Martino, P. W. McNamara, J. Mendes, L. Mendes, N. Meshksar, A. Monsky, M. Nofrarias, S. Paczkowski, M. Perreur-Lloyd, A. Petiteau, E. Plagnol, J. Ramos-Castro, J. Reiche, F. Rivas, D. I. Robertson, G. Russano, J. Sanjuan, J. Slutsky, C. F. Sopuerta, F. Steier, T. Sumner, D. Texier, J. I. Thorpe, D. Vetrugno, S. Vitale, V. Wand, G. Wanner, H. Ward, P. J. Wass, W. J. Weber, L. Wissel, A. Wittchen, and P. Zweifel

Published
2022
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2. Sensor Noise in LISA Pathfinder: In-Flight Performance of the Optical Test Mass Readout

Author

M. Armano, H. Audley, J. Baird, P. Binetruy, M. Born, D. Bortoluzzi, N. Brandt, E. Castelli, A. Cavalleri, A. Cesarini, A. M. Cruise, K. Danzmann, M. de Deus Silva, I. Diepholz, G. 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, F. Guzman, I. Harrison, M.-S. Hartig, G. Heinzel, J. Slutsky, and J. I. Thorpe

Subjects
Spacecraft Instrumentation And Astrionics, Earth Resources And Remote Sensing
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 (+2.4, −1.7) fm/(√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.

Published
2021
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3. Capacitive sensing of test mass motion with nanometer precision over millimeter-wide sensing gaps for space-borne gravitational reference sensors

Author

M. Armano, H. Audley, G. Auger, J. Baird, M. Bassan, P. Binetruy, 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, 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, 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, P. Pivato, E. Plagnol, P. Prat, 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, and P. Zweifel

Published
2017
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4. Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder

Author

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

Published
2017
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5. Sub-Femto-gFree Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

Author

M. Armano, H. Audley, G. Auger, J. T. Baird, M. Bassan, P. Binetruy, M. Born, D. Bortoluzzi, N. Brandt, M. Caleno, L. Carbone, A. Cavalleri, A. Cesarini, G. Ciani, G. Congedo, A. M. Cruise, K. Danzmann, M. de Deus Silva, R. De Rosa, M. Diaz-Aguiló, L. Di Fiore, I. Diepholz, G. Dixon, R. Dolesi, N. Dunbar, L. Ferraioli, V. Ferroni, W. Fichter, E. D. Fitzsimons, R. Flatscher, M. Freschi, A. F. García Marín, C. García Marirrodriga, R. Gerndt, L. Gesa, F. Gibert, D. Giardini, R. Giusteri, F. Guzmán, A. Grado, C. Grimani, A. Grynagier, J. Grzymisch, I. Harrison, G. Heinzel, M. Hewitson, D. Hollington, D. Hoyland, M. Hueller, H. Inchauspé, O. Jennrich, P. Jetzer, U. Johann, 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, F. Martin-Porqueras, S. Madden, I. Mateos, P. W. McNamara, J. Mendes, L. Mendes, A. Monsky, D. Nicolodi, M. Nofrarias, S. Paczkowski, M. Perreur-Lloyd, A. Petiteau, P. Pivato, E. Plagnol, P. Prat, U. Ragnit, B. Raïs, J. Ramos-Castro, J. Reiche, D. I. Robertson, H. Rozemeijer, F. Rivas, G. Russano, J. Sanjuán, P. Sarra, A. Schleicher, D. Shaul, J. Slutsky, C. F. Sopuerta, R. Stanga, F. Steier, T. Sumner, D. Texier, J. I. Thorpe, C. Trenkel, M. Tröbs, H. B. Tu, D. Vetrugno, S. Vitale, V. Wand, G. Wanner, H. Ward, C. Warren, P. J. Wass, D. Wealthy, W. J. Weber, L. Wissel, A. Wittchen, A. Zambotti, C. Zanoni, T. Ziegler, and P. Zweifel

Published
2016
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6. In-Orbit Performance of the GRACE Follow-on Laser Ranging Interferometer

Author

Jehhal Liu, Henry Wegener, Joseph Trinh, David C Barr, James Howell, Andrew J. Sutton, Daniel A. Shaddock, C. Bogan, Bernd Zender, Mike A Davis, Gerhard Heinzel, Micah Kruger, Duo Wang, Frank Gilles, Martin S. Gilbert, R. Flatscher, M Herding, Christopher Woodruff, Anton Lebeda, Mark Katsumura, Benjamin Sheard, Carl Christian Liebe, S. Dubovitsky, Katrin Dahl, Rabi T. Wang, Christoph Mahrdt, Daniel Schütze, Frank Heine, Marcus Zimmermann, Kenneth Clark, Steve Windisch, Nicolas Grossard, Philipp Hager, Michelle Stephens, Brian Bachman Okihiro, Jerome Hauden, Kameron Larsen, Karsten Danzmann, William M. Folkner, Christian Dahl, Brent Ware, Burghardt Guenther, Glenn de Vine, Robert Spero, Andreas Eckardt, Malte Misfeldt, Joshua Ravich, Claus Braxmaier, Gary D. Spiers, Arnold Lebeda, J. Reiche, Gretchen Reavis, Thomas Ester, Frank Flechtner, Martin Hinz, Alexander Koch, Alexander Abramovici, Jeffrey Dickson, Andreas Baatzsch, Christoph Seiter, Robert Pierce, Kai Voss, Marina Kaufer, K. Nicklaus, Kirk McKenzie, Michael J Burke, Klaus Abich, Maxime P Bize, Phillip R Morton, Alex Murray, Vitali Müller, T. Mangoldt, Lynette Lobmeyer, William Klipstein, Michael Sileo, Martin Gohlke, Germán Fernández Barranco, Don J Nguyen, Bengie Amparan, Thomas Leikert, G. Stede, Samuel Francis, and Josep Sanjuan

Subjects
heterodyne interferometry, Wavefronts, Orbits, FOS: Physical sciences, General Physics and Astronomy, 01 natural sciences, Degrees of freedom (mechanics), satelitte laser ranging, law.invention, Physics - Geophysics, Optics, law, Laser frequency, 0103 physical sciences, Astronomical interferometer, ddc:530, Spacecraft attitude, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, Wavefront, Spacecraft, Interferometers, business.industry, Wave-front sensing, Ranging, Laser, Autonomous control, Gravity recovery and climate experiments, Geophysics (physics.geo-ph), Interferometry, Range measurements, Remote spacecraft, Laser interferometry, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Astrophysics - Instrumentation and Methods for Astrophysics, business, Laser interferometric, Noise (radio), Microwave
Abstract

The Laser Ranging Interferometer (LRI) instrument on the Gravity Recovery and Climate Experiment (GRACE) Follow-On mission has provided the first laser interferometric range measurements between remote spacecraft, separated by approximately 220 km. Autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degrees of freedom two-way laser link between remote spacecraft succeeded on the first attempt. Active beam pointing based on differential wave front sensing compensates spacecraft attitude fluctuations. The LRI has operated continuously without breaks in phase tracking for more than 50 days, and has shown biased range measurements similar to the primary ranging instrument based on microwaves, but with much less noise at a level of 1 nm/Hz at Fourier frequencies above 100 mHz. © 2019 authors. Published by the American Physical Society.

Published
2019

7. Micrometeoroid Events in LISA Pathfinder

Author

Ignacio Mateos, St Drs Operations Team, J. Grzymisch, H. Ward, D. Wealthy, H. Rozemeijer, J. A. Lobo, Gerhard Heinzel, Nicole Pagane, A. Zambotti, S. Paczkowski, Ivan Lloro, Ph. Jetzer, Antoine Petiteau, Paul McNamara, P. Prat, José F. F. Mendes, Daniele Bortoluzzi, N. Brandt, Nikolaos Karnesis, James Ira Thorpe, R. De Rosa, Michael Tröbs, Carlos F. Sopuerta, Michele Armano, L. Mendes, C. Zanoni, Davor Mance, J. O’Donnell, Daniele Vetrugno, B. Johlander, Lluis Gesa, G. Auger, Curt Cutler, John Ziemer, M. Freschi, Henri Inchauspe, A. Schleicher, F. Martin-Porqueras, M. Girard, M. Hewitson, D. Shaul, R. Maarschalkerweerd, Karsten Danzmann, T. J. Sumner, D. Texier, E. D. Fitzsimons, F. Rivas, Daniel Hollington, L. Liu, Oliver Jennrich, Miquel Nofrarías, P. Pivato, A. M. Cruise, W. J. Weber, R. Giusteri, Michael Perreur-Lloyd, John G. Baker, P. Sarra, Tobias Ziegler, N. Korsakova, Aniello Grado, Heather Audley, Peter Wass, Tyson Littenberg, Gudrun Wanner, Sophie Hourihane, Pierre Binétruy, Antonella Cavalleri, L. Di Fiore, R. Gerndt, Jacob Slutsky, Valerio Ferroni, S. Vitale, Christian J. Killow, B. Kaune, C. Trenkel, S. Madden, Diego Janches, Juan Ramos-Castro, D. Hoyland, C. Marrese-Reading, J. Reiche, Rita Dolesi, N. Dunbar, Catia Grimani, P. Barela, C. Dunn, C. García Marirrodriga, A. Wittchen, R. Flatscher, P. Maghami, U. Ragnit, I. Li, Ruggero Stanga, Mauro Hueller, Nate Demmons, S. Javidnia, Petr Pokorny, G. Dixon, J. P. López-Zaragoza, M. Born, A. Cesarini, G. Russano, Ferran Gibert, J. Martino, J. Baird, Massimo Bassan, O. Hsu, Andrew Romero-Wolf, L. Wissel, Ingo Diepholz, M. de Deus Silva, Luigi Ferraioli, Eric Plagnol, V. Martín, Domenico Giardini, M. Caleno, D. I. Robertson, Peter Zweifel, J. Mehta, L. Martin-Polo, I. Harrison, Thorpe, J. I., Slutsky, J., Baker, J. G., Littenberg, T. B., Hourihane, S., Pagane, N., Pokorny, P., Janches, D., Armano, M., Audley, H., Auger, G., Baird, J., Bassan, M., Binetruy, P., Born, M., Bortoluzzi, D., Brandt, N., Caleno, M., Cavalleri, A., Cesarini, A., Cruise, A. M., Danzmann, K., De Deus Silva, M., DE ROSA, Rosario, Di Fiore, L., Diepholz, I., Dixon, G., Dolesi, R., Dunbar, N., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Flatscher, R., Freschi, M., Garcia Marirrodriga, C., Gerndt, R., Gesa, L., Gibert, F., Giardini, D., Giusteri, R., Grado, A., Grimani, C., Grzymisch, J., Harrison, I., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspe, H., Jennrich, O., Jetzer, P., Johlander, B., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Lloro, I., Liu, L., Lopez-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martin, V., Martin-Polo, L., Martino, J., Martin-Porqueras, F., Madden, S., Mateos, I., Mcnamara, P. W., Mendes, J., Mendes, L., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Pivato, P., Plagnol, E., Prat, P., Ragnit, U., Ramos-Castro, J., Reiche, J., Robertson, D. I., Rozemeijer, H., Rivas, F., Russano, G., Sarra, P., Schleicher, A., Shaul, D., Sopuerta, C. F., Stanga, R., Sumner, T., Texier, D., Trenkel, C., Trobs, M., Vetrugno, D., Vitale, S., Wanner, G., Ward, H., Wass, P., Wealthy, D., Weber, W. J., Wissel, L., Wittchen, A., Zambotti, A., Zanoni, C., Ziegler, T., Zweifel, P., Barela, P., Cutler, C., Demmons, N., Dunn, C., Girard, M., Hsu, O., Javidnia, S., Li, I., Maghami, P., Marrese-Reading, C., Mehta, J., Romero-Wolf, A., Ziemer, J., AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, and Science and Technology Facilities Council (STFC)

Subjects
Astrofísica, Solar System, 010504 meteorology & atmospheric sciences, Meteors, Astrophysics, 01 natural sciences, Planet, meteoroids, 010303 astronomy & astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), 0306 Physical Chemistry (incl. Structural), Settore FIS/01, Physics, Sistema solar, education.field_of_study, Micrometeoroid, Astrophysics::Instrumentation and Methods for Astrophysics, Meteoroids, instrumentation: miscellaneous, meteorites, meteors, meteoroids, Asteroid, Physical Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, miscellaneous [Instrumentation], Solar system, Population, FOS: Physical sciences, Astronomy & Astrophysics, meteorites, 0201 Astronomical and Space Sciences, 0103 physical sciences, meteors, education, 0105 earth and related environmental sciences, Science & Technology, Zodiacal light, Meteoroid, instrumentation: miscellaneou, Astronomy, Astronomy and Astrophysics, miscellaneous, meteorites, meteors, meteoroids [instrumentation], Pathfinder, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], Enginyeria electrònica::Instrumentació i mesura [Àrees temàtiques de la UPC], ORBITS, Astrophysics - Earth and Planetary Astrophysics, Meteorites
Abstract

The zodiacal dust complex, a population of dust and small particles that pervades the Solar System, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. Here we present a new set of data obtained using a novel technique: direct measurements of momentum transfer to a spacecraft from individual particle impacts. This technique is made possible by the extreme precision of the instruments flown on the LISA Pathfinder spacecraft, a technology demonstrator for a future space-based gravitational wave observatory that operated near the first Sun-Earth Lagrange point from early 2016 through Summer of 2017. Using a simple model of the impacts and knowledge of the control system, we show that it is possible to detect impacts and measure properties such as the transferred momentum (related to the particle's mass and velocity), direction of travel, and location of impact on the spacecraft. In this paper, we present the results of a systematic search for impacts during 4348 hours of Pathfinder data. We report a total of 54 candidates with momenta ranging from 0.2$\,\mu\textrm{Ns}$ to 230$\,\mu\textrm{Ns}$. We furthermore make a comparison of these candidates with models of micrometeoroid populations in the inner solar system including those resulting from Jupiter-family comets, Oort-cloud comets, Hailey-type comets, and Asteroids. We find that our measured population is consistent with a population dominated by Jupiter-family comets with some evidence for a smaller contribution from Hailey-type comets. This is in agreement with consensus models of the zodiacal dust complex in the momentum range sampled by LISA Pathfinder., Comment: 22 pages, 14 figures, accepted in ApJ

Published
2019

8. LISA Pathfinder closed-loop analysis: a model breakdown of the in-loop observables

Author

Ph. Jetzer, W. J. Weber, Lluis Gesa, Karsten Danzmann, Alexander Schleicher, F. Rivas, R. Maarschalkerweerd, A. Wittchen, J. Grzymisch, Antoine Petiteau, Paul McNamara, D. Wealthy, Gudrun Wanner, Juan Ramos-Castro, H. Rozemeijer, D. Shaul, H. Ward, Eric Plagnol, Catia Grimani, Ian Harrison, Henri Inchauspe, Ignacio Mateos, Carlos F. Sopuerta, Domenico Giardini, A. Zambotti, Michael Troebs, C. Zanoni, P. Prat, R. De Rosa, Michele Armano, B. Kaune, A. Lobo, S. Madden, Antonella Cavalleri, M. Freschi, C. Garcia Marrirodriga, N. Dunbar, M. de Deus Silva, R. Gerndt, J. Baird, M. Bassan, J. Martino, L. Mendel, Daniele Vetrugno, L. Wissel, Pierre Binétruy, L. Di Fiore, J. P. López-Zaragoza, J. Reiche, Martin Hewitson, E. D. Fitzsimons, Oliver Jennrich, Daniel Hollington, Víctor S. Martín, Daniele Bortoluzzi, A. Cesarini, Michael Perreur-Lloyd, G. Russano, Ferran Gibert, Tobias Ziegler, P. Pivato, Gerard Auger, R. Giusteri, M. Caleno, N. Korsakova, Ingo Diepholz, Miquel Nofrarías, Ivan Lloro, M. Cruise, D. I. Robertson, Peter Zweifel, M. Hueller, Luigi Ferraioli, Ruggero Stanga, Tamara Sumner, R. Flatscher, Aniello Grado, Heather Audley, U. Ragnit, N. Karnesis, Rita Dolesi, José F. F. Mendes, Davor Mance, B. Johlander, D. Texier, Jacob Slutsky, Valerio Ferroni, M. Born, D. Hoyland, Peter Wass, James Ira Thorpe, L. Martin-Polo, F. Martin-Porqueras, C. Trenke, S. Paczkowski, P. Sarra, S. Vitale, N. Brandt, L. Liu, Christian J. Killow, Gerhard Heinzel, and LISA Pathfinder Collaboration

Subjects
Physics, History, Science & Technology, 02 Physical Sciences, Observable, Astronomy & Astrophysics, 01 natural sciences, 09 Engineering, Computer Science Applications, Education, Loop (topology), Pathfinder, Control theory, 0103 physical sciences, Physical Sciences, 010306 general physics, Closed loop analysis
Abstract

This paper describes a methodology to analyze, in the frequency domain, the steady-state control performances of the LISA Pathfinder mission. In particular, it provides a technical framework to give a comprehensive understanding of the spectra of all the degrees of freedom by breaking them down into their various physical origins, hence bringing out the major contributions of the control residuals. A reconstruction of the measured in-loop output, extracted from a model of the closed-loop system, is shown as an instance to illustrate the potential of such a model breakdown of the data.

Published
2017

9. LISA Pathfinder: First steps to observing gravitational waves from space

Author

N. Karnesis, C. Garca Marrirodriga, Michele Armano, Ian Harrison, Jacob Slutsky, Valerio Ferroni, D. Hoyland, M. Freschi, Henri Inchauspe, M. Cruise, Daniele Vetrugno, Michael Perreur-Lloyd, Gerhard Heinzel, F. Rivas, Lluis Gesa, Ignacio Mateos, P. Pivato, Ph. Jetzer, Gudrun Wanner, Juan Ramos-Castro, R. Maarschalkerweerd, A. Wittchen, R. Gerndt, Peter Wass, Karsten Danzmann, Antoine Petiteau, Paul McNamara, S. Paczkowski, L. Liu, Carlos F. Sopuerta, R. Giusteri, P. Prat, N. Dunbar, Antonella Cavalleri, S. Vitale, L. Martin-Polo, J. Baird, U. Ragnit, Christian J. Killow, Domenico Giardini, M. de Deus Silva, Rita Dolesi, P. Sarra, H. Rozemeijer, Tobias Ziegler, R. De Rosa, J. Reiche, A. Zambotti, W. J. Weber, D. Shaul, A. Cesarini, G. Russano, M. Bassan, M. Hueller, J. Martino, E. D. Fitzsimons, Alexander Schleicher, R. Flatscher, Catia Grimani, F. Martin-Porqueras, Michael Troebs, Peter Zweifel, J. Grzymisch, M. Born, N. Korsakova, Aniello Grado, Heather Audley, H. Ward, Pierre Binétruy, James Ira Thorpe, L. Wissel, Daniele Bortoluzzi, L. Mendes, B. Johlander, Miquel Nofrarías, C. Zanoni, Eric Plagnol, Ruggero Stanga, Ingo Diepholz, A. Lobo, Martin Hewitson, Daniel Hollington, L. Di Fiore, Oliver Jennrich, M. Caleno, D. Wealthy, D. I. Robertson, C. Trenkel, Luigi Ferraioli, Tamara Sumner, Davor Mance, D. Texier, B. Kaune, S. Madden, Ivan Lloro, José F. F. Mendes, Víctor S. Martín, N. Brandt, J. P. López-Zaragoza, Ferran Gibert, Gerard Auger, and LISA Pathfinder Collaboration

Subjects
Physics, History, Science & Technology, 02 Physical Sciences, Gravitational wave, Settore FIS/01 - Fisica Sperimentale, Astronomy, Astronomy & Astrophysics, Space (mathematics), 09 Engineering, Computer Science Applications, Education, Pathfinder, Physical Sciences
Abstract

LISA Pathfinder, the European Space Agency's technology demonstrator mission for future spaceborne gravitational wave observatories, was launched on 3 December 2015, from the European space port of Kourou, French Guiana. After a short duration transfer to the final science orbit, the mission has been gathering science data since. This data has allowed the science community to validate the critical technologies and measurement principle for low frequency gravitational wave detection and thereby confirming the readiness to start the next generation gravitational wave observatories, such as LISA. This paper will briefly describe the mission, followed by a description of the science operations highlighting the performance achieved. Details of the various experiments performed during the nominal science operations phase can be found in accompanying papers in this volume.

Published
2017

10. Charge-induced force noise on free-falling test masses: results from LISA Pathfinder

Author

B. Johlander, Heather Audley, Gerhard Heinzel, M. Cruise, Ph. Jetzer, José F. F. Mendes, R. Giusteri, M. Hewitson, Lluis Gesa, G. Auger, Antoine Petiteau, Jacob Slutsky, Valerio Ferroni, Paul McNamara, R. Gerndt, Rita Dolesi, N. Korsakova, R. Maarschalkerweerd, A. Wittchen, Karsten Danzmann, Michele Armano, J. Baird, Carlos F. Sopuerta, S. Paczkowski, M. Freschi, Oliver Jennrich, P. Prat, E. D. Fitzsimons, Henri Inchauspe, Daniele Vetrugno, W. J. Weber, Christian J. Killow, B. Kaune, P. Sarra, S. Madden, Daniele Bortoluzzi, Peter Wass, L. Mendes, A. Bursi, C. García Marirrodriga, P. Pivato, Miquel Nofrarías, J. Huesler, F. Martin-Porqueras, Mauro Hueller, H. Rozemeijer, Antonella Cavalleri, R. Flatscher, Pierre Binétruy, N. Brandt, Nikolaos Karnesis, C. Trenkel, C. Zanoni, J. Martino, S. Vitale, Ignacio Mateos, A. Schleicher, J. Gallegos, Daniel Hollington, T. J. Sumner, L. Liu, J. P. López-Zaragoza, Ferran Gibert, M. de Deus Silva, Luigi Ferraioli, N. Dunbar, Catia Grimani, Domenico Giardini, J. A. Romera Perez, Eric Plagnol, V. Martín, M. Caleno, D. I. Robertson, Tobias Ziegler, James Ira Thorpe, A. Moroni, D. Wealthy, U. Ragnit, Ivan Lloro, Davor Mance, D. Texier, J. Reiche, A. Cesarini, G. Russano, Peter Zweifel, I. Harrison, L. Martin-Polo, Michael Perreur-Lloyd, J. Grzymisch, H. Ward, M. Born, Ingo Diepholz, F. Rivas, Gudrun Wanner, Juan Ramos-Castro, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), LISA Pathfinder, LISA Pathfinder Collaboration, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), AstroParticule et Cosmologie ( APC - UMR 7164 ), and Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )

Subjects
Gravitational-wave observatory, Capacitive sensing, General Physics and Astronomy, Interplanetary flight, Astrophysics, 01 natural sciences, 09 Engineering, Laser interferometers, Gravitational wave detectors, Cosmic ray measurement, Dedicated measurements, force: electrostatic, [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], MISSION, Physics, 02 Physical Sciences, Stochastic systems, Astrophysics::Instrumentation and Methods for Astrophysics, Interferometria làser, Electrostatics, Cosmology, electric field, observatory, cosmic radiation, frequency, Physical Sciences, Electrostàtica, Astrophysics - Instrumentation and Methods for Astrophysics, European Space Agency, electrostatic, Noise (radio), Gravitation, Laser interferometer space antenna, General Physics, Electric fields, Physics, Multidisciplinary, Capacitive sensors, FOS: Physical sciences, Gravity waves, LISA Pathfinder Collaboration, Electrostatic measurements, Gravitational waves, Physics and Astronomy (all), Acceleration, Ones gravitacionals, Gravitational reference sensors, Electric field, 0103 physical sciences, Frequency bands, stochastic, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], noise: acceleration, coupling, 010306 general physics, Electrostatic modeling, Instrumentation and Methods for Astrophysics (astro-ph.IM), 01 Mathematical Sciences, LISA, Science & Technology, Interferometers, 010308 nuclear & particles physics, Gravitational wave, Electrostatic force, FIELDS, gravitational radiation detector, Computational physics, Pathfinder, gravitation, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], mass, Laser interferometry, Differential accelerations, SYSTEM, astro-ph.IM
Abstract

We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0 fm/s^2/sqrt(Hz) across the 0.1-100 mHz frequency band that is crucial to an observatory such as LISA. Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge build up due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument., Comment: 9 Pages, 3 figures

Published
2017

11. Sub-Femto- g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

Author

R. Gerndt, F. Rivas, Daniele Bortoluzzi, L. Carbone, L. Mendes, Ph. Jetzer, Walter Fichter, Jacob Slutsky, Valerio Ferroni, D. Hoyland, Ulrich Johann, Gudrun Wanner, Miquel Nofrarías, Peter Wass, Juan Ramos-Castro, Pierre Binétruy, Ivan Lloro, Lluis Gesa, G. Auger, C. Trenkel, Stefano Vitale, James Ira Thorpe, Antoine Petiteau, A. Grynagier, Paul McNamara, A. F. García Marín, G. Congedo, Luigi Ferraioli, M. Born, R. Maarschalkerweerd, Karsten Danzmann, V Wand, C. Zanoni, A. Monsky, Ruggero Stanga, Ingo Diepholz, Carlos F. Sopuerta, F. Steier, A. Cesarini, José F. F. Mendes, Tobias Ziegler, N. Korsakova, G. Russano, F. Guzmán, H. Rozemeijer, M. Hewitson, A. Schleicher, B. Johlander, J. P. López-Zaragoza, Michael Perreur-Lloyd, Michele Armano, Daniel Hollington, Daniele Vetrugno, D. Wealthy, B. Kaune, S. Madden, P. Sarra, A. Zambotti, M. Diaz-Aguilo, Christian J. Killow, Peter Zweifel, Davor Mance, D. Shaul, T. J. Sumner, L. Liu, J. Grzymisch, H. Ward, M. Freschi, L. Di Fiore, Oliver Jennrich, Michael Tröbs, H. B. Tu, R. Flatscher, M. Caleno, D. I. Robertson, J. A. Lobo, S. Paczkowski, Ferran Gibert, L. Martin-Polo, P. Prat, I. Harrison, P. Pivato, Ignacio Mateos, C. García Marirrodriga, Mauro Hueller, D. Texier, A. Wittchen, U. Ragnit, Aniello Grado, Heather Audley, J Sanjuán, C. Warren, J. Reiche, B. Rais, Henri Inchauspe, G. Dixon, Eric Plagnol, V. Martín, Domenico Giardini, Daniele Nicolodi, N. Brandt, Nikolaos Karnesis, Giacomo Ciani, Antonella Cavalleri, J. Martino, R. Giusteri, L. Wissel, Rita Dolesi, J. Baird, Massimo Bassan, R. De Rosa, E. D. Fitzsimons, Gerhard Heinzel, W. J. Weber, A. M. Cruise, F. Martin-Porqueras, M. de Deus Silva, N. Dunbar, Catia Grimani, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, UK Space Agency, Science and Technology Facilities Council (STFC), Armano, M., Audley, H., Auger, G., Baird, J. T., Bassan, M., Binetruy, P., Born, M., Bortoluzzi, D., Brandt, N., Caleno, M., Carbone, L., Cavalleri, A., Cesarini, A., Ciani, G., Congedo, G., Cruise, A. M., Danzmann, K., De Deus Silva, M., DE ROSA, Rosario, Diaz Aguiló, M., Di Fiore, L., Diepholz, I., Dixon, G., Dolesi, R., Dunbar, N., Ferraioli, L., Ferroni, V., Fichter, W., Fitzsimons, E. D., Flatscher, R., Freschi, M., García Marín, A. F., García Marirrodriga, C., Gerndt, R., Gesa, L., Gibert, F., Giardini, D., Giusteri, R., Guzmán, F., Grado, A., Grimani, C., Grynagier, A., Grzymisch, J., Harrison, I., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Johann, U., Johlander, B., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Lloro, I., Liu, L., López Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martín, V., Martin Polo, L., Martino, J., Martin Porqueras, F., Madden, S., Mateos, I., Mcnamara, P. W., Mendes, J., Mendes, L., Monsky, A., Nicolodi, D., Nofrarias, M., Paczkowski, S., Perreur Lloyd, M., Petiteau, A., Pivato, P., Plagnol, E., Prat, P., Ragnit, U., Raïs, B., Ramos Castro, J., Reiche, J., Robertson, D. I., Rozemeijer, H., Rivas, F., Russano, G., Sanjuán, J., Sarra, P., Schleicher, A., Shaul, D., Slutsky, J., Sopuerta, C. F., Stanga, R., Steier, F., Sumner, T., Texier, D., Thorpe, J. I., Trenkel, C., Tröbs, M., Tu, H. B., Vetrugno, D., Vitale, S., Wand, V., Wanner, G., Ward, H., Warren, C., Wass, P. J., Wealthy, D., Weber, W. J., Wissel, L., Wittchen, A., Zambotti, A., Zanoni, C., Ziegler, T., Zweifel, P., Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
General Physics, Gravitational-wave observatory, detector: performance, Physics, Multidisciplinary, General Physics and Astronomy, Astrophysics, 01 natural sciences, 7. Clean energy, Noise (electronics), 09 Engineering, LISA Pathfinder, Gravitational waves, Acceleration, Physics and Astronomy (all), Square root, Ones gravitacionals, gas, 0103 physical sciences, Orders of magnitude (speed), interferometer: satellite, noise: acceleration, 010303 astronomy & astrophysics, 01 Mathematical Sciences, MISSION, Physics, LISA, Science & Technology, 02 Physical Sciences, density: spectral, 010308 nuclear & particles physics, Gravitational wave, Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, gravitational radiation, Spectral density, gravitational radiation detector: satellite, detector: sensitivity, gravitation, Physical Sciences, viscosity, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Brownian noise, readout, INTERFEROMETER
Abstract

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 +/- 0.1 fm s(exp -2)/square root of Hz, or (0.54 +/- 0.01) x 10(exp -15) g/square root of Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 +/- 0.3) fm square root of Hz, about 2 orders of magnitude better than requirements. At f less than or equal to 0.5 mHz we observe a low-frequency tail that stays below 12 fm s(exp -2)/square root of Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

Published
2016

12. Space-based detectors

Author

J. Reiche, Gerhard Heinzel, Michele Armano, Oliver Gerberding, W. J. Weber, N. Brause, P. McNamara, Anders Enggaard, Peter L. Bender, Martin Hewitson, Zoran Sodnik, T. Akutsu, Torben Rasmussen, Gerald Hechenblaikner, Christian J. Killow, Alberto Sesana, A. M. Cruise, Tamara Sumner, Allan Hornstrup, D. Smith, D. Hoyland, Oliver Jennrich, Martin Suess, Simon Barke, S. Møller-Pedersen, Ewan Fitzsimons, J. Bryant, R. Gerndt, Karsten Danzmann, Bangalore Suryanarayana Sathyaprakash, T. Vendt Hansen, Joachim Kullmann, J. Bogenstahl, G. Dixon, H. Ward, Alberto Gianolio, D. I. Robertson, Michael Perreur-Lloyd, Ioury Bykov, R. Flatscher, and DECIGO working group

Subjects
Physics, Atom interferometer, Physics and Astronomy (miscellaneous), Gravitational wave, Payload, business.industry, Context (language use), Space exploration, Interferometry, Optics, Gravity of Earth, Pathfinder, Aerospace engineering, business
Abstract

The parallel session C5 on Space-Based Detectors gave a broad overview over the planned space missions related to gravitational wave detection. Overviews of the revolutionary science to be expected from LISA was given by Alberto Sesana and Sasha Buchman. The launch of LISA Pathfinder (LPF) is planned for 2015. This mission and its payload “LISA Technology Package” will demonstrate key technologies for LISA. In this context, reference masses in free fall for LISA, and gravitational physics in general, was described by William Weber, laser interferometry at the pico-metre level and the optical bench of LPF was presented by Christian Killow and the performance of the LPF optical metrology system by Paul McNamara. While LPF will not yet be sensitive to gravitational waves, it may nevertheless be used to explore fundamental physics questions, which was discussed by Michele Armano. Some parts of the LISA technology that are not going to be demonstrated by LPF, but under intensive development at the moment, were presented by Oliver Jennrich and Oliver Gerberding. Looking into the future, Japan is studying the design of a mid-frequency detector called DECIGO, which was discussed by Tomotada Akutsu. Using atom interferometry for gravitational wave detection has also been recently proposed, and it was critically reviewed by Peter Bender. In the nearer future, the launch of GRACE Follow-On (for Earth gravity observation) is scheduled for 2017, and it will include a Laser Ranging Interferometer as technology demonstrator. This will be the first inter-spacecraft laser interferometer and has many aspects in common with the LISA long arm, as discussed by Andrew Sutton.

Published
2014

13. Thermo-elastic induced phase noise in the LISA Pathfinder spacecraft

Author

J. Reiche, Gerhard Heinzel, H. Ward, Miquel Nofrarías, Ferran Gibert, R. Flatscher, Ingo Diepholz, Víctor S. Martín, Lluis Gesa, P. McNamara, R. Gerndt, Domenico Gerardi, Felipe Guzman, Ignacio Mateos, Karsten Danzmann, Martin Hewitson, D. I. Robertson, Alberto Lobo, Nikolaos Karnesis, and Johannes Burkhardt

Subjects
Physics, Physics and Astronomy (miscellaneous), Spacecraft, Thermal test, Frequency band, business.industry, Thermo elastic, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Temperature measurement, General Relativity and Quantum Cosmology, Interferometry, Pathfinder, Phase noise, Atomic physics, business, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

During the On-Station Thermal Test campaign of the LISA Pathfinder the data and diagnostics subsystem was tested in nearly space conditions for the first time after integration in the satellite. The results showed the compliance of the temperature measurement system, obtaining temperature noise around $10^{-4}\,{\rm K}\, {\rm Hz}^{-1/2}$ in the frequency band of $1-30\;{\rm mHz}$. In addition, controlled injection of heat signals to the suspension struts anchoring the LISA Technology Package (LTP) Core Assembly to the satellite structure allowed to experimentally estimate for the first time the phase noise contribution through thermo-elastic distortion of the LTP interferometer, the satellite's main instrument. Such contribution was found to be at $10^{-12}\,{\rm m}\, {\rm Hz}^{-1/2}$, a factor of 30 below the measured noise at the lower end of the measurement bandwidth ($1\,{\rm mHz}$)., Comment: Submitted to CQG

Published
2014
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14. Realization of a 10-µm homodyne receiver

Author

Arpad L. Scholtz, Heinz K. Philipp, Walter R. Leeb, and R. Flatscher

Subjects
Physics, business.industry, Preamplifier, Local oscillator, Optical power, Phase detector, Atomic and Molecular Physics, and Optics, Photodiode, law.invention, Phase-locked loop, Optics, Homodyne detection, law, Demodulation, business
Abstract

We have realized a homodyne receiver for phase-modulated laser radiation at \lambda = 10.6 \mu m, based on a dc-coupled optical phase-locked loop (PLL). A control loop maintains the output power of the CO 2 laser local oscillator at 0.7 mW. Fine frequency tuning of this laser is achieved by an acoustooptic frequency shifter whose inherent time delay has been taken into account in the design of both the PLL and the power control loop. The PLL rms phase error is some 3° for a received optical power of 4 nW. The HgCdTe photodiode serving as phase detector and as demodulator, as well as the preamplifier are operated at 80 K by means of a Stirling cooler. Clear domination of shot noise is achieved for the data rate of 140 Mbit/s. A microcomputer performs dc-offset compensation and frequency acquisition. The system is part of a breadboard of an intersatellite data link.

Published
1987

15. Gekühlte Detektor-Vorverstärker-Einheit für einen 10,6 µm Homodyn-Empfänger

Author

R. Flatscher

Abstract

Fur breitbandige Datenubertragung zwischen Satelliten wird im Auftrag der Europaischen Weltraumbehorde ESA das Labormodell einer Sende- Empfangseinheit bei einer Wellenlange von 10,6 µm aufgebaut. Bei einer vorlaufigen Datenrate von 140 Mbit/s soll ein digital phasenmoduliertes Eingangssignal mit einer Leistung von 1 nW detektiert werden /1/. Fur den vorliegenden Anwendungsfall zeigt der Homodyn-Empfanger gegenuber anderen Empfangsverfahren deutliche Vorteile /2/. Ein wesentlicher Teil dieses Empfangers ist eine auf ca. 80 K gekuhlte Detektor-Vorver- starker-Kombination.

Published
1986

16. Mechanisch Gekühlter Vorverstärker für Einen Optischen Empfänger bei 10 µm

Author

R. Flatscher

Abstract

Ein auf ca. 80 K gekuhltes HgCdTe-Detektorelement dient in einem optischen Homodynempfanger als Phasendetektor, an dem das Regelsignal fur die Phasenregelschleife und gleichzeitig das demodulierte Datensignal auftritt. Die Kuhlung des Detektors erfolgt durch einen mechanischen Stirling-Kuhler mit abgesetztem Kaltteil. Um groste Empfindlichkeit zu erreichen mus auch der Breitband-Vorverstarker mitgekuhlt werden. Verschiedene rauscharme Verstarkerkonzepte mit geeigneten aktiven Elementen wurden entwickelt, aufgebaut und miteinander verglichen.

Published
1985

17. Thermo-elastic induced phase noise in the LISA Pathfinder spacecraft.

Author

F Gibert, M Nofrarias, N Karnesis, L Gesa, V Martín, I Mateos, A Lobo, R Flatscher, D Gerardi, J Burkhardt, R Gerndt, D I Robertson, H Ward, P W McNamara, F Guzmán, M Hewitson, I Diepholz, J Reiche, G Heinzel, and K Danzmann

Subjects
LISA Pathfinder, QUANTUM gravity, INTERFEROMETERS, SPACE vehicles, PHASE noise
Abstract

During the on-station thermal test campaign of the LISA Pathfinder, the diagnostics subsystem was tested in nearly space conditions for the first time after integration in the satellite. The results showed the compliance of the temperature measurement system, obtaining temperature noise around in the frequency band 1–30 MHz. In addition, controlled injection of heat signals to the suspension struts anchoring the LISA Technology Package (LTP) core assembly to the satellite structure allowed us to experimentally estimate, for the first time, the phase noise contribution through thermo-elastic distortion of the LTP interferometer, the satelliteʼs main instrument. Such contribution was found to be at , a factor of 30 below the measured noise at the lower end of the measurement bandwidth (). [ABSTRACT FROM AUTHOR]

Published
2015
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18.  Thliphthisasapphus (Rubiaceae, Rubieae), a new species from Lefkada (Ionian Islands, Greece) and its ecological position.

Author

Gutermann W, Jang TS, Kästner A, Prehsler D, Reich D, Berger A, Flatscher R, Gilli C, Hofbauer M, Lachmayer M, Sander R, Sonnleitner M, and Mucina L

Abstract

The new species, Thliphthisasapphus sp. nov. (Rubiaceae, Rubieae), a narrow endemic of the white cliffs of Lefkátas on the southwest coast of Lefkada (Greece) is described and illustrated and an IUCN assessment is presented. Vegetation relevés were performed at the single known locality, limestone cliffs facing the sea and revealed a new association, the Thliphthisasapphus - Lomelosietumdallaportae . The chromosome number of Thliphthisasapphus was determined as 2 n = 4 x = 44, being the single tetraploid species in the genus to date. The species also differs markedly morphologically from its morphologically closest relatives, two Greek steno-endemic oreophytes, Th.baenitzii and Th.muscosa by the following characters: densely setose mericarps and corolla, tetraploidy and by its distribution. An identification key for the Greek species of Thliphthisa is provided. Th.sapphus constitutes the westernmost outpost of a group of Greek steno-endemics, highlighting the importance of coastal habitats and their protection as refugia for poorly competitive chamaephytes., Competing Interests: The authors have declared that no competing interests exist., (Walter Gutermann, Tae-Soo Jang, Arndt Kästner, David Prehsler, Dieter Reich, Andreas Berger, Ruth Flatscher, Christian Gilli, Markus Hofbauer, Margarita Lachmayer, Ruth Sander, Michaela Sonnleitner, Ladislav Mucina.)

Published
2024
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19. Sensor Noise in LISA Pathfinder: In-Flight Performance of the Optical Test Mass Readout.

Author

Armano M, Audley H, Baird J, Binetruy P, Born M, Bortoluzzi D, Brandt N, Castelli E, Cavalleri A, Cesarini A, Cruise AM, Danzmann K, de Deus Silva M, Diepholz I, Dixon G, Dolesi R, Ferraioli L, Ferroni V, Fitzsimons ED, Flatscher R, Freschi M, García A, Gerndt R, Gesa L, Giardini D, Gibert F, Giusteri R, Grimani C, Grzymisch J, Guzman F, Harrison I, Hartig MS, Heinzel G, Hewitson M, Hollington D, Hoyland D, Hueller M, Inchauspé H, Jennrich O, Jetzer P, Johann U, Johlander B, Karnesis N, Kaune B, Killow CJ, Korsakova N, Lobo JA, Liu L, López-Zaragoza JP, Maarschalkerweerd R, Mance D, Martín V, Martin-Polo L, Martin-Porqueras F, Martino J, McNamara PW, Mendes J, Mendes L, Meshksar N, Monsky A, Nofrarias M, Paczkowski S, Perreur-Lloyd M, Petiteau A, Pivato P, Plagnol E, Ramos-Castro J, Reiche J, Rivas F, Robertson DI, Russano G, Sanjuan J, Slutsky J, Sopuerta CF, Steier F, Sumner T, Texier D, Thorpe JI, Vetrugno D, Vitale S, Wand V, Wanner G, Ward H, Wass PJ, Weber WJ, Wissel L, Wittchen A, and Zweifel P

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.

Published
2021
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20. In-Orbit Performance of the GRACE Follow-on Laser Ranging Interferometer.

Author

Abich K, Abramovici A, Amparan B, Baatzsch A, Okihiro BB, Barr DC, Bize MP, Bogan C, Braxmaier C, Burke MJ, Clark KC, Dahl C, Dahl K, Danzmann K, Davis MA, de Vine G, Dickson JA, Dubovitsky S, Eckardt A, Ester T, Barranco GF, Flatscher R, Flechtner F, Folkner WM, Francis S, Gilbert MS, Gilles F, Gohlke M, Grossard N, Guenther B, Hager P, Hauden J, Heine F, Heinzel G, Herding M, Hinz M, Howell J, Katsumura M, Kaufer M, Klipstein W, Koch A, Kruger M, Larsen K, Lebeda A, Lebeda A, Leikert T, Liebe CC, Liu J, Lobmeyer L, Mahrdt C, Mangoldt T, McKenzie K, Misfeldt M, Morton PR, Müller V, Murray AT, Nguyen DJ, Nicklaus K, Pierce R, Ravich JA, Reavis G, Reiche J, Sanjuan J, Schütze D, Seiter C, Shaddock D, Sheard B, Sileo M, Spero R, Spiers G, Stede G, Stephens M, Sutton A, Trinh J, Voss K, Wang D, Wang RT, Ware B, Wegener H, Windisch S, Woodruff C, Zender B, and Zimmermann M

Abstract

The Laser Ranging Interferometer (LRI) instrument on the Gravity Recovery and Climate Experiment (GRACE) Follow-On mission has provided the first laser interferometric range measurements between remote spacecraft, separated by approximately 220 km. Autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degrees of freedom two-way laser link between remote spacecraft succeeded on the first attempt. Active beam pointing based on differential wave front sensing compensates spacecraft attitude fluctuations. The LRI has operated continuously without breaks in phase tracking for more than 50 days, and has shown biased range measurements similar to the primary ranging instrument based on microwaves, but with much less noise at a level of 1  nm/sqrt[Hz] at Fourier frequencies above 100 mHz.

Published
2019
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21. Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder.

Author

Armano M, Audley H, Auger G, Baird JT, Binetruy P, Born M, Bortoluzzi D, Brandt N, Bursi A, Caleno M, Cavalleri A, Cesarini A, Cruise M, Danzmann K, de Deus Silva M, Diepholz I, Dolesi R, Dunbar N, Ferraioli L, Ferroni V, Fitzsimons ED, Flatscher R, Freschi M, Gallegos J, García Marirrodriga C, Gerndt R, Gesa L, Gibert F, Giardini D, Giusteri R, Grimani C, Grzymisch J, Harrison I, Heinzel G, Hewitson M, Hollington D, Hueller M, Huesler J, Inchauspé H, Jennrich O, Jetzer P, Johlander B, Karnesis N, Kaune B, Killow CJ, Korsakova N, Lloro I, Liu L, López-Zaragoza JP, Maarschalkerweerd R, Madden S, Mance D, Martín V, Martin-Polo L, Martino J, Martin-Porqueras F, Mateos I, McNamara PW, Mendes J, Mendes L, Moroni A, Nofrarias M, Paczkowski S, Perreur-Lloyd M, Petiteau A, Pivato P, Plagnol E, Prat P, Ragnit U, Ramos-Castro J, Reiche J, Romera Perez JA, Robertson DI, Rozemeijer H, Rivas F, Russano G, Sarra P, Schleicher A, Slutsky J, Sopuerta C, Sumner TJ, Texier D, Thorpe JI, Trenkel C, Vetrugno D, Vitale S, Wanner G, Ward H, Wass PJ, Wealthy D, Weber WJ, Wittchen A, Zanoni C, Ziegler T, and Zweifel P

Abstract

We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0  fm s^{-2} Hz^{-1/2} across the 0.1-100 mHz frequency band that is crucial to an observatory such as the Laser Interferometer Space Antenna (LISA). Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge buildup due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument.

Published
2017
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22. Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results.

Author

Armano M, Audley H, Auger G, Baird JT, Bassan M, Binetruy P, Born M, Bortoluzzi D, Brandt N, Caleno M, Carbone L, Cavalleri A, Cesarini A, Ciani G, Congedo G, Cruise AM, Danzmann K, de Deus Silva M, De Rosa R, Diaz-Aguiló M, Di Fiore L, Diepholz I, Dixon G, Dolesi R, Dunbar N, Ferraioli L, Ferroni V, Fichter W, Fitzsimons ED, Flatscher R, Freschi M, García Marín AF, García Marirrodriga C, Gerndt R, Gesa L, Gibert F, Giardini D, Giusteri R, Guzmán F, Grado A, Grimani C, Grynagier A, Grzymisch J, Harrison I, Heinzel G, Hewitson M, Hollington D, Hoyland D, Hueller M, Inchauspé H, Jennrich O, Jetzer P, Johann U, Johlander B, Karnesis N, Kaune B, Korsakova N, Killow CJ, Lobo JA, Lloro I, Liu L, López-Zaragoza JP, Maarschalkerweerd R, Mance D, Martín V, Martin-Polo L, Martino J, Martin-Porqueras F, Madden S, Mateos I, McNamara PW, Mendes J, Mendes L, Monsky A, Nicolodi D, Nofrarias M, Paczkowski S, Perreur-Lloyd M, Petiteau A, Pivato P, Plagnol E, Prat P, Ragnit U, Raïs B, Ramos-Castro J, Reiche J, Robertson DI, Rozemeijer H, Rivas F, Russano G, Sanjuán J, Sarra P, Schleicher A, Shaul D, Slutsky J, Sopuerta CF, Stanga R, Steier F, Sumner T, Texier D, Thorpe JI, Trenkel C, Tröbs M, Tu HB, Vetrugno D, Vitale S, Wand V, Wanner G, Ward H, Warren C, Wass PJ, Wealthy D, Weber WJ, Wissel L, Wittchen A, Zambotti A, Zanoni C, Ziegler T, and Zweifel P

Abstract

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2±0.1  fm s^{-2}/sqrt[Hz], or (0.54±0.01)×10^{-15}  g/sqrt[Hz], with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8±0.3)  fm/sqrt[Hz], about 2 orders of magnitude better than requirements. At f≤0.5  mHz we observe a low-frequency tail that stays below 12  fm s^{-2}/sqrt[Hz] down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

Published
2016
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23. Ecological differentiation of diploid and polyploid cytotypes of Senecio carniolicus sensu lato (Asteraceae) is stronger in areas of sympatry.

Author

Sonnleitner M, Hülber K, Flatscher R, Escobar García P, Winkler M, Suda J, Schönswetter P, and Schneeweiss GM

Subjects
Diploidy, Ecosystem, Ecotype, Europe, Models, Genetic, Monte Carlo Method, Senecio genetics, Polyploidy, Senecio physiology, Sympatry
Abstract

Background and Aims: Ecological differentiation is recognized as an important factor for polyploid speciation, but little is known regarding whether the ecological niches of cytotypes differ between areas of sympatry and areas where single cytotypes occur (i.e. niche displacement)., Methods: Ecological niches of four groups of Senecio carniolicus sensu lato (s.l.) (western and eastern diploid lineages, tetraploids and hexaploids) were characterized via Landolt indicator values of the accompanying vascular plant species and tested using multivariate and univariate statistics., Key Results: The four groups of S. carniolicus s.l. were ecologically differentiated mainly with respect to temperature, light and soil (humus content, nutrients, moisture variability). Niche breadths did not differ significantly. In areas of sympatry hexaploids shifted towards sites with higher temperature, less light and higher soil humus content as compared with homoploid sites, whereas diploids and tetraploids shifted in the opposite direction. In heteroploid sites of tetraploids and the western diploid lineage the latter shifted towards sites with lower humus content but higher aeration., Conclusions: Niche displacement can facilitate the formation of stable contact zones upon secondary contact of polyploids and their lower-ploid ancestors and/or lead to convergence of the cytotypes' niches after they have attained non-overlapping ranges. Niche displacement is essential for understanding ecological consequences of polyploidy., (© The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Published
2016
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24. Underestimated diversity in one of the world's best studied mountain ranges: The polyploid complex of Senecio carniolicus (Asteraceae) contains four species in the European Alps.

Author

Flatscher R, García PE, Hülber K, Sonnleitner M, Winkler M, Saukel J, Schneeweiss GM, and Schönswetter P

Abstract

Senecio carniolicus (Asteraceae) is an intricate polyploid complex distributed in the European Alps (di-, tetra- and hexaploids) and Carpathians (hexaploids only). Molecular genetic, ecological, and crossing data allowed four evolutionary groups within S. carniolicus to be identified. Here, we establish that these four groups (two vicariant diploid lineages, tetraploids and hexaploids) are also morphologically differentiated. As a consequence, we draw taxonomic conclusions by characterizing four species, including the more narrowly circumscribed S. carniolicus (lectotypified here), the taxonomically elevated S. insubricus comb. nov. (lectotypified here), and the two newly described species S. disjunctus and S. noricus .

Published
2015
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25. Parental ploidy strongly affects offspring fitness in heteroploid crosses among three cytotypes of autopolyploid Jacobaea carniolica (Asteraceae).

Author

Sonnleitner M, Weis B, Flatscher R, García PE, Suda J, Krejčíková J, Schneeweiss GM, Winkler M, Schönswetter P, and Hülber K

Subjects
Asteraceae physiology, Endosperm genetics, Pollination genetics, Seedlings genetics, Asteraceae genetics, Genetic Fitness, Hybridization, Genetic, Polyploidy
Abstract

Reproductive interactions among cytotypes in their contact zones determine whether these cytotypes can co-exist and form stable contact zones or not. In autopolyploids, heteroploid cross-compatibilities might depend on parental ploidy, but tests of this hypothesis in autopolyploid systems with more than two ploidies are lacking. Here, we study Jacobaea carniolica, which comprises diploid, tetraploid, and hexaploid individuals regularly forming contact zones. Seeds obtained from in situ cross-pollinations within and among cytotypes were subjected to DNA flow cytometry and greenhouse germination experiments. Hybrid fitness and parental effects on hybrid fitness were tested with regression models comparing fitness parameters of early life stages. Irrespective of the direction of crosses, seed viability and seedling survival in diploid-polyploid crosses were substantially lower than in tetraploid-hexaploid crosses. In contrast, seedling growth traits indicated neither transgressive character expression nor any selection against hybrid offspring. Congruent with a model of genome dosage effects, these traits differed between reciprocal crosses, especially of diploids and tetraploids, where trait values resembled those of the maternal parent. The strong effect of parental ploidy on offspring fitness in heteroploid crosses may cause contact zones involving exclusively polyploid cytotypes to be less stable over longer terms than those involving diploids and polyploids.

Published
2013
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26. Extensive range persistence in peripheral and interior refugia characterizes Pleistocene range dynamics in a widespread Alpine plant species (Senecio carniolicus, Asteraceae).

Author

Escobar García P, Winkler M, Flatscher R, Sonnleitner M, Krejčíková J, Suda J, Hülber K, Schneeweiss GM, and Schönswetter P

Subjects
Amplified Fragment Length Polymorphism Analysis, Arctic Regions, Bayes Theorem, DNA, Chloroplast genetics, DNA, Plant genetics, DNA, Ribosomal Spacer genetics, Europe, Geography, Haplotypes, Ice Cover, Senecio classification, Sequence Analysis, DNA, Genetic Variation, Phylogeography, Senecio genetics
Abstract

Recent evidence suggests that survival of arctic-alpine organisms in peripheral or interior glacial refugia are not mutually exclusive and may both be involved in shaping an organism's Pleistocene history, yet potentially at different time levels. Here, we test this hypothesis in a high-mountain plant (diploid lineage of Senecio carniolicus, Asteraceae) from the Eastern European Alps, in which patterns of morphological variation and current habitat requirements suggest survival in both types of refugia. To this end, we used AFLPs, nuclear and plastid DNA sequences and analysed them, among others, within a graph theoretic framework and using novel Bayesian methods of phylogeographic inference. On the basis of patterns of genetic diversity, occurrence of rare markers, distribution of distinct genetic lineages and patterns of range connectivity both interior refugia in the formerly strongly glaciated central Alps and peripheral refugia along the southern margin of the Alps were identified. The presence of refugia congruently inferred by markers resolving at different time levels suggests that these refugia acted as such throughout several glacial cycles. The high degree of range persistence together with gradual range expansion, which contrasts with the extent of range shifts implied for other Alpine species, is likely responsible for incipient lineage differentiation evident from the genetic data. Replacing a simplistic peripheral vs. interior refugia dualism by more complex models involving both types of refugia and considering different time levels will help identifying common phylogeographic patterns with respect to, for instance, location of refugia and colonization routes and elucidating their underlying genetic and/or ecological causes. DNA sequences have been deposited in GenBank under accession nos. FR796701–FR797793 and nos. HE614296–HE614583., (© 2012 Blackwell Publishing Ltd.)

Published
2012
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27. Environmental heterogeneity and phenotypic divergence: can heritable epigenetic variation aid speciation?

Author

Flatscher R, Frajman B, Schönswetter P, and Paun O

Abstract

The dualism of genetic predisposition and environmental influences, their interactions, and respective roles in shaping the phenotype have been a hot topic in biological sciences for more than two centuries. Heritable epigenetic variation mediates between relatively slowly accumulating mutations in the DNA sequence and ephemeral adaptive responses to stress, thereby providing mechanisms for achieving stable, but potentially rapidly evolving phenotypic diversity as a response to environmental stimuli. This suggests that heritable epigenetic signals can play an important role in evolutionary processes, but so far this hypothesis has not been rigorously tested. A promising new area of research focuses on the interaction between the different molecular levels that produce phenotypic variation in wild, closely-related taxa that lack genome-wide genetic differentiation. By pinpointing specific adaptive traits and investigating the mechanisms responsible for phenotypic differentiation, such study systems could allow profound insights into the role of epigenetics in the evolution and stabilization of phenotypic discontinuities, and could add to our understanding of adaptive strategies to diverse environmental conditions and their dynamics.

Published
2012
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28. Distribution and habitat segregation on different spatial scales among diploid, tetraploid and hexaploid cytotypes of Senecio carniolicus (Asteraceae) in the Eastern Alps.

Author

Sonnleitner M, Flatscher R, Escobar García P, Rauchová J, Suda J, Schneeweiss GM, Hülber K, and Schönswetter P

Subjects
Ecosystem, Asteraceae genetics, Asteraceae growth & development, Diploidy, Polyploidy, Tetraploidy
Abstract

Background and Aims: The spatial distribution of cytotypes can provide valuable insights into evolutionary patterns of polyploid complexes. In a previous study the macro-scale distribution of the three main cytotypes in Senecio carniolicus (Asteraceae) within the Eastern Alps was characterized. Employing a roughly 12-fold extended sampling, the present study focuses on unravelling patterns of cytotype distribution on the meso- and microscale and on correlating those with ecological properties of the growing sites., Methods: DAPI flow cytometry of dried samples was used to determine DNA ploidy level in 5033 individuals from 100 populations spread over the entire Eastern Alpine distribution area of S. carniolicus. Descriptors of microhabitats as well as spatial data were recorded in the field, and analysed with a mixed-effects ANOVA., Key Results: Extensive variation in DNA ploidy levels (2x, 3x, 4x, 5x, 6x, 7x, 8x, 9x) was detected. Of the main cytotypes, diploids and hexaploids were widespread and had strongly overlapping distributions resulting in the frequent occurrence of cytotype mixtures (half of the investigated populations), whereas tetraploids were disjunctly distributed and occurred in the south-west and the east of the species' distribution area. In spite of the frequent co-occurrence of cytotypes, only 1 % of the samples belonged to secondary cytotypes (3x, 5x, 7x, 8x, 9x). Diploids, tetraploids and hexaploids were altitudinally segregated, but with broad overlap. Similarly, highly significant differences in vegetation and rock cover as well as microhabitat exposure were found between the main cytotypes., Conclusions: Senecio carniolicus shows a remarkable diversity of cytotypes. The distribution of the three main cytotypes (2x, 4x, 6x) has been shaped by Pleistocene glaciations to different extents. Whereas tetraploids are nearly entirely restricted to refugia, hexaploids colonized areas that were extensively glaciated. Diploid and hexaploid individuals often co-occur in mixed populations, where they are spatially and ecologically segregated at both the meso-scale (altitudinal differentiation, exposure of the growing site) and the micro-scale (cover of vegetation and bare rock). With regard to the ecological parameters investigated, the tetraploid cytotype occupies an intermediate position. The rareness of secondary cytotypes suggests the presence of strong pre- or post-zygotic mating barriers.

Published
2010
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29. Ecological segregation drives fine-scale cytotype distribution of Senecio carniolicus in the Eastern Alps.

Author

Hülber K, Sonnleitner M, Flatscher R, Berger A, Dobrovsky R, Niessner S, Nigl T, Schneeweiss GM, Kubešová M, Rauchová J, Suda J, and Schönswetter P

Abstract

In order to uncover patterns and processes of segregation of co-existing cytotypes, we investigated a zone in the eastern Alps (Austria) where diploid and hexaploid individuals of the alpine herb Senecio carniolicus Willd. (Asteraceae) co-occur. Linking the fine-scale distribution of cytotypes to environmental and spatial factors revealed segregation along an ecological gradient, which was also reflected in the cytotype-associated plant assemblages. Compared to diploids, hexaploids are found in more species-rich and denser communities. This may be due to their better competitive ability and lower tolerance of abiotic stress compared to the diploids. The lack of any intermediate cytotypes suggests the presence of strong reproductive isolation mechanisms, whose nature is, however, elusive.

Published
2009

30. Exo-zodi detection capability of the Ground-Based European Nulling Interferometry Experiment (GENIE) instrument.

Author

Wallner O, Flatscher R, and Ergenzinger K

Abstract

The Ground-Based European Nulling Interferometry Experiment (GENIE) is intended as an Earth-based precursor for the European Darwin mission that will prepare the Darwin science program and demonstrate the required technology at system level. We propose a compact nulling interferometer design consisting of a two-telescope aperture configuration, an optional split-pupil add-on, and only four active control loops for counteracting environmentally induced disturbances. We show by simulation that the proposed instrument is able to detect, within a few minutes of observation time, exo-zodiacal dust clouds around Sunlike stars at 20 parsecs that are 20 times stronger than the local zodiacal dust cloud density.

Published
2006
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