Showing papers by "Ulrich Johann published in 2014"
TL;DR: In this paper, the authors discuss disturbance reduction requirements for LISA and beyond, describe four different payload concepts, compare expected strain sensitivities in the “low-frequency” region of the frequency spectrum, dominated by acceleration noise, and ultimately discuss advantages and disadvantages of each of those concepts in achieving disturbance reduction for space-based detectors beyond LISA.
Abstract: Future drag-free missions for space-based experiments in gravitational physics require a Gravitational Reference Sensor with extremely demanding sensing and disturbance reduction requirements. A configuration with two cubical sensors is the current baseline for the Laser Interferometer Space Antenna (LISA) and has reached a high level of maturity. Nevertheless, several promising concepts have been proposed with potential applications beyond LISA and are currently investigated at HEPL, Stanford, and EADS Astrium, Germany. The general motivation is to exploit the possibility of achieving improved disturbance reduction, and ultimately understand how low acceleration noise can be pushed with a realistic design for future mission. In this paper, we discuss disturbance reduction requirements for LISA and beyond, describe four different payload concepts, compare expected strain sensitivities in the “low-frequency” region of the frequency spectrum, dominated by acceleration noise, and ultimately discuss advantages and disadvantages of each of those concepts in achieving disturbance reduction for space-based detectors beyond LISA.
34 citations
German Aerospace Center1, Leibniz University of Hanover2, University of Bordeaux3, Ferdinand-Braun-Institut4, University of Zurich5, University of Birmingham6, University of Bremen7, European Space Agency8, Dornier Flugzeugwerke9, Institut de Ciències de l'Espai10, Humboldt University of Berlin11, University of Hamburg12, Centre National D'Etudes Spatiales13, University of Ulm14, University of Florence15, National Technical University of Athens16, Foundation for Research & Technology – Hellas17, Technische Universität Darmstadt18, Office National d'Études et de Recherches Aérospatiales19
TL;DR: The spacetime explorer and quantum equivalence principle space test satellite mission, proposed as a medium-size mission within the Cosmic Vision program of the European Space Agency (ESA), aims for testing general relativity with high precision in two experiments by performing a measurement of the gravitational redshift of the Sun and the Moon by comparing terrestrial clocks, and by performing the universality of free fall of matter waves in the gravitational field of Earth comparing the trajectory of two Bose-Einstein condensates of 85Rb and 87Rb as mentioned in this paper.
Abstract: The theory of general relativity describes macroscopic phenomena driven by the influence of gravity while quantum mechanics brilliantly accounts for microscopic effects. Despite their tremendous individual success, a complete unification of fundamental interactions is missing and remains one of the most challenging and important quests in modern theoretical physics. The spacetime explorer and quantum equivalence principle space test satellite mission, proposed as a medium-size mission within the Cosmic Vision program of the European Space Agency (ESA), aims for testing general relativity with high precision in two experiments by performing a measurement of the gravitational redshift of the Sun and the Moon by comparing terrestrial clocks, and by performing a test of the universality of free fall of matter waves in the gravitational field of Earth comparing the trajectory of two Bose–Einstein condensates of 85Rb and 87Rb. The two ultracold atom clouds are monitored very precisely thanks to techniques of atom interferometry. This allows to reach down to an uncertainty in the Eötvös parameter of at least 2 × 10−15. In this paper, we report about the results of the phase A mission study of the atom interferometer instrument covering the description of the main payload elements, the atomic source concept, and the systematic error sources.
21 citations
05 Nov 2014
TL;DR: In this article, the authors present the status of a new setup to determine coefficients of thermal expansions (CTE) of ultra stable materials at temperatures from 300K down to 100 K. This setup is an advancement of a measurement facility for CTE determination at room temperature with demonstrated measurements of CTE values down to 10ppb/K.
Abstract: In this article we present the status of our new setup to determine coefficients of thermal expansions (CTE) of ultra stable materials at temperatures from 300K down to 100 K. Such low CTE materials are important for dimensionally stable structures in space and terrestrial applications e.g. To enable precise measurements. This setup is an advancement of a measurement facility for CTE determination at room temperature with demonstrated measurements of CTE values down to 10ppb/K -- 1. Due to the high temperature differences of the new setup, the mechanical and thermal setup is very important. The mechanical transfer function between interferometer and the device under test (DUT) has to be high and the thermal transfer function has to be very low to achieve the required accuracy. An overview of the new setup and its subsystems is given in this article with a measurement of the sensitivity of the interferometer.
1 citations
23 Jun 2014
TL;DR: In this paper, the authors developed a compact and ruggedized iodine-based frequency reference on elegant breadboard (EBB) and engineering model (EM) level using modulation transfer spectroscopy near 532 nm.
Abstract: We present the development of compact and ruggedized iodine-based frequency references on elegant breadboard (EBB) and engineering model (EM) level using modulation transfer spectroscopy near 532 nm. A frequency stabilty of 1·10−14 at an integration time of 1 s and below 5·10−15 at integration times between 10s and 100s was achieved. Space applications of such an optical frequency reference can be found in fundamental physics, geoscience, Earth observation, navigation and ranging. One example is the proposed mSTAR (mini SpaceTime Asymmetry Research) mission, dedicated to perform a Kennedy-Thorndike experiment on a satellite in a low-Earth orbit. By comparing an iodine standard to a cavity-based frequency reference and integration over 2 year mission lifetime, the Kennedy-Thorndike coefficient will be determined with up to two orders of magnitude higher accuracy than the current best ground experiment.
1 citations