A. Wittchen
A5071619215- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Advanced Frequency and Time Standards
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Cosmology and Gravitation Theories
- Particle Accelerators and Free-Electron Lasers
- Scientific Measurement and Uncertainty Evaluation
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Geophysics and Sensor Technology
- Computational Physics and Python Applications
- Soil Moisture and Remote Sensing
- Neutrino Physics Research
- Superconducting Materials and Applications
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Superconducting and THz Device Technology
- Advanced Electrical Measurement Techniques
- Geomagnetism and Paleomagnetism Studies
- Advanced MEMS and NEMS Technologies
Leibniz University Hannover
2016-2025
Max Planck Institute for Gravitational Physics
2016-2025
In the months since publication of first results, noise performance LISA Pathfinder has improved because reduced Brownian due to continued decrease in pressure around test masses, from a better correction noninertial effects, and calibration electrostatic force actuation. addition, availability numerous long measurement runs, during which no perturbation is purposely applied allowed with good statistics down 20 μHz. The Letter presents measured differential acceleration figure, at...
Measurements of electrostatic forces on free-falling test masses--2 kg metal cubes--are carried out for the first time in an environment constructed space-based gravitational wave detectors (a spacecraft 1.5 million km away from Earth).
We present an in-depth analysis of the LISA Pathfinder differential acceleration performance over entire course its science operations, spanning approximately 500 days. find: (1) The evolution Brownian noise that dominates amplitude spectral density (ASD), for frequencies f≳1 mHz, is consistent with decaying pressure due to outgassing a single gaseous species. (2) Between f=36 μHz and 1 ASD shows 1/f tail in excess almost constant amplitude, ≃20% fluctuations period few days, no particular...
LISA Pathfinder was a mission designed to test key technologies required for gravitational wave detection in space. Magnetically driven forces play role the instrument sensitivity low-frequency regime, which corresponds measurement band of interest future space-borne observatories. Magnetic-induced couple mass motion, introducing contribution relative acceleration noise between free falling masses. In this Letter we present first complete estimate term performance model. Our results set...
The science operations of the LISA Pathfinder mission have demonstrated feasibility sub-femto-g free fall macroscopic test masses necessary to build a gravitational wave observatory in space such as LISA. While main focus interest, i.e., optical axis or $x$-axis, has been extensively studied, it is also great importance evaluate stability spacecraft with respect all other degrees freedom (d.o.f.). current paper dedicated study: exhaustive and quantitative evaluation imperfections dynamical...
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 fundamental measurement positional angular motion two free-falling test masses. The worked immediately, stably, reliably from switch until end with exceptionally low residual noise ${32.0}_{\ensuremath{-}1.7}^{+2.4}\text{ }\text{ }\mathrm{fm}/\sqrt{\mathrm{Hz}}$, significantly better than required. present an upper limit for sensor...
The (LPF) mission successfully demonstrated the feasibility of technology needed for future space borne gravitational wave observatory LISA. A key subsystem under study was laser interferometer, which measured changes in relative distance between two test masses (TMs). It achieved a sensitivity <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"...
Electrostatic force actuation is a key component of the system geodesic reference test masses (TM) for LISA orbiting gravitational wave observatory and in particular performance at low frequencies, below 1 mHz, where sensitivity limited by stray noise. The needs to apply forces order 10−9 N while limiting fluctuations measurement band levels approaching 10−15 N/Hz1/2. We present here design, based on audio-frequency voltage carrier signals, results its in-flight with Pathfinder mission. In...
We report on the performance of capacitive gap-sensing system Gravitational Reference Sensor board LISA Pathfinder spacecraft. From in-flight measurements, has demonstrated a performance, down to 1 mHz, that is ranging between 0.7 and $1.8\text{ }\text{ }\mathrm{aF}\text{ }{\mathrm{Hz}}^{\ensuremath{-}1/2}$. That translates into sensing noise test mass motion within 1.2 $2.4\text{ }\mathrm{nm}\text{ }{\mathrm{Hz}}^{\ensuremath{-}1/2}$ in displacement 83 $170\text{ }\mathrm{nrad}\text{...
In a previous article [1], we have reported on the first subpicometer interferometer flown in space as part of ESA's LISA Pathfinder mission, and shown residual sensor noise to be level ${32.0}_{\ensuremath{-}1.7}^{+2.4}\text{ }\text{ }\mathrm{fm}/\sqrt{\mathrm{Hz}}$. This review provides deeper more complete overview full system its interferometric mission performance under varying operational conditions, allowing much detailed view model. We also include optical measurements rotations...
We present an in depth analysis of the transient events, or glitches, detected at a rate about one per day differential acceleration data LISA Pathfinder. show that these glitches fall two rather distinct categories: fast transients interferometric motion readout on side, and true force events other. The former are rare ordinary conditions. second may last from seconds to hours constitute majority glitches. physical statistical properties both categories, including cross-analysis with other...
A comprehensive summary of the measurements made to characterize test-mass charging due space environment during LISA Pathfinder mission is presented. Measurements residual charge test mass after release by grabbing and positioning mechanism show that initial masses was negative all releases, leaving with a potential in range from $\ensuremath{-}12$ $\ensuremath{-}512$. Variations neutral rate between 21.7 $30.7\text{ }\text{ }e\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ were observed over...
LISA Pathfinder (LPF), the second of European Space Agency's Small Missions for Advanced Research in Technology (SMART), is a dedicated technology validation mission future spaceborne gravitational wave detectors, such as proposed eLISA mission. Pathfinder, and its scientific payload - Package will test, flight, critical technologies required low frequency detection: it put two test masses near-perfect free-fall control measure their motion with unprecedented accuracy. This achieved through...
The LISA Pathfinder charge management device was responsible for neutralising the cosmic ray induced electric that inevitably accumulated on free-falling test masses at heart of experiment. We present measurements made ground and in-flight quantify performance this contactless discharge system which based photo-emission under UV illumination. In addition, a two-part simulation is described developed alongside hardware. Modelling absorbed light within sensor carried out with GEANT4 software...
LISA Pathfinder (LPF) was a technology pioneering mission designed to test key technologies required for gravitational wave detection in space. In the low frequency regime (milli-Hertz and below), where space-based observatories will operate, temperature fluctuations play crucial role since they can couple into interferometric measurement masses' free-fall accuracy many ways. A dedicated subsystem, with noise levels 10$\,\mu$K$\,$Hz$^{-1/2}$ down $1\,$mHz part of diagnostics unit on board...
Abstract Galactic cosmic-ray (GCR) energy spectra observed in the inner heliosphere are modulated by solar activity, polarity and structures of interplanetary origin. A high counting rate particle detector (PD) aboard LISA Pathfinder , meant for subsystems diagnostics, was devoted to measurement GCR energetic integral fluxes above 70 MeV n −1 up 6500 counts s . PD data were gathered with a sampling time 15 s. Characteristics dependence flux recurrent depressions Forbush decrease dated 2016...
The LISA Pathfinder (LPF) mission has demonstrated the ability to limit and measure fluctuations in acceleration between two free falling test masses down sub-femto-g levels. One of key elements achieve such a level residual is drag control. In this scheme spacecraft used as shield against any external disturbances by adjusting its relative position reference mass. actuators move are cold gas micropropulsion thrusters. paper, we report in-flight characterization these thrusters term noise...
Laser interferometers are the core measurement tool in gravitational wave observatories. An important factor that can limit performance is relative power instability of laser, a problem often called intensity noise (RIN). But exactly how this influences interferometer not completely understood. Therefore paper we analyze laser RIN coupling into phase readout balanced and unbalanced heterodyne interferometers. We describe theoretically, then simulate finally measure it. Our results reveal...
LISA Pathfinder (LPF) was a European Space Agency mission with the aim to test key technologies for future space-borne gravitational-wave observatories like LISA. The main scientific goal of LPF demonstrate measurements differential acceleration between free-falling masses at sub-femto-$g$ level, and understand residual in terms physical model stray forces, displacement readout noise. A step toward reaching goals correct calibration dynamics LPF, which three-body system composed by two...
We present a study of the tilt-to-length coupling noise during LISA Pathfinder mission and how it depended on system's alignment. Tilt-to-length is unwanted angular lateral spacecraft or test mass motion into primary interferometric displacement readout. It was one major sources in likewise expected to be source LISA. demonstrate here that recently derived published analytical model describes dependency alignment two freely falling masses. This verified with data taken before after...
LISA Pathfinder (LPF) has been a space-based mission designed to test new technologies that will be required for gravitational wave observatory in space. Magnetically driven forces play key role the instrument sensitivity low-frequency regime (mHz and below), measurement band of interest observatory. The magnetic field can couple susceptibility remanent moment from masses disturb them their geodesic movement. carried on-board dedicated subsystem with noise levels 10 $ \rm nT \ Hz^{-1/2}$ 1...
LISA Pathfinder satellite was launched on 3 December 2015 toward the Sun–Earth first Lagrangian point (L1) where Technology Package (LTP), which is main science payload, will be tested. LTP achieves measurements of differential acceleration free-falling test masses (TMs) with sensitivity below within 1–30 mHz frequency band in one-dimension. The spacecraft itself responsible for dominant gravitational field acting two TMs. Such a force interaction could contribute significant amount noise...
We report on the results of LISA Pathfinder (LPF) free-fall mode experiment, in which control force needed to compensate quasistatic differential acting two test masses is applied intermittently as a series ``impulse'' forces lasting few seconds and separated by roughly 350 s periods true free fall. This represents an alternative normal LPF operation this balancing continuously, with advantage that acceleration noise during fall measured absence actuation force, thus eliminating associated...