B. Winter

University College London, Londinium, England, United Kingdom

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Publications (30)24.58 Total impact

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    ABSTRACT: One of the main challenges for current and near future space experiments is the increase of focal plane complexity in terms of amount of pixels. In the frame work of the ESA Euclid mission to be launched in 2020, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. CEA has developed the thermomechanical architecture of that Focal Plane taking into account all the very stringent performance and mission related requirements. The VIS Focal Plane Assembly integrates 36 CCDs (operated at 150K) connected to their front end electronics (operated at 280K) as to obtain one of the largest focal plane (∼0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD273 type specially designed and provided by the e2v company under ESA contract, front end electronics is studied and provided by MSSL. In this paper we first recall the specific requirements that have driven the overall architecture of the VIS-FPA and especially the solutions proposed to cope with the scientific needs of an extremely stable focal plane, both mechanically and thermally. The mechanical structure based on SiC material used for the cold sub assembly supporting the CCDs is detailed. We describe also the modular architecture concept that we have selected taking into account AIT-AIV and programmatic constraints.
    SPIE Astronomical Telescopes + Instrumentation; 08/2014
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    ABSTRACT: The Exoplanet Characterisation Observatory (EChO) is a space project currently under study by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The EChO main scientific objectives are based on spectroscopy of transiting exoplanets over a wide range of wavelengths, from visible to mid-infrared. The high sensitivity requirements of the mission need an extremely stable thermo-mechanical platform. In this paper we describe the thermal architecture of the payload and discuss the main requirements that drive the design. The instrument is passively cooled to a temperature close to 45K, together with the telescope, to achieve the required sensitivity and photometric stability. Passive cooling is achieved by a V-Groove based design that exploits the L2 orbit favorable thermal conditions. The Visible and short-IR wavelength detectors are maintained at the operating temperature of 40K by a dedicated radiator coupled to cold space. The mid-IR channels require lower temperature references for both the detectors and part of the optical units. These colder stages are provided by an active cooling system based on a Neon Joule-Thomson cold end, fed by a mechanical compressor, able to reach temperatures <30K. The design has to be compliant with the severe requirements on thermal stability of the optical and detector units. The periodical perturbations due to orbital changes, to the cooling chain or to other internal instabilities make the temperature control one of the most critical issues of the whole architecture. The thermal control system design, based on a combination of passive and active solutions needed to maintain the required stability at the detector stages level is described. We report here about the baseline thermal architecture at the end of the Study Phase, together with the main trade-offs needed to enable the EChO exciting science in a technically feasible payload design. Thermal modeling results and preliminary performance predictions in terms of steady state and transient behavior are also discussed. This paper is presented on behalf of the EChO Consortium.
    SPIE Astronomical Telescopes + Instrumentation; 08/2014
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    ABSTRACT: The Large Observatory for X-ray Timing (LOFT) was one of the M3 missions selected for the phase A study in the ESA's Cosmic Vision program. LOFT is designed to perform high-time-resolution X-ray observations of black holes and neutron stars. The main instrument on the LOFT payload is the Large Area Detector (LAD), a collimated experiment with a nominal effective area of ~10 m 2 @ 8 keV, and a spectral resolution of ~240 eV in the energy band 2-30 keV. These performances are achieved covering a large collecting area with more than 2000 large-area Silicon Drift Detectors (SDDs) each one coupled to a collimator based on lead-glass micro-channel plates. In order to reduce the thermal load onto the detectors, which are open to Sky, and to protect them from out of band radiation, optical-thermal filter will be mounted in front of the SDDs. Different options have been considered for the LAD filters for best compromise between high quantum efficiency and high mechanical robustness. We present the baseline design of the optical-thermal filters, show the nominal performances, and present preliminary test results performed during the phase A study.
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    ABSTRACT: LOFT (Large Observatory for X-ray Timing) is one of the five candidates that were considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. Its pointed instrument is the Large Area Detector (LAD), a 10 m 2 -class instrument operating in the 2-30keV range, which holds the capability to revolutionise studies of variability from X-ray sources on the millisecond time scales. The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most of the trade-offs have been closed leading to a robust and well documented design that will be re- proposed in future ESA calls. In this talk, we will summarize the characteristics of the LAD design and give an overview of the expectations for the instrument capabilities.
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    ABSTRACT: LOFT (Large Observatory for X-ray Timing) is an X-ray timing observatory that, with four other candidates, was considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. Its pointed instrument is the Large Area Detector (LAD), a 10 m 2 -class instrument operating in the 2-30 keV range, which is designed to perform X-ray timing of compact objects with unprecedented resolution down to millisecond time scales. Although LOFT was not downselected for launch, during the assessment most of the trade-offs have been closed, leading to a robust and well documented design that will be reproposed in future ESA calls. The building block of the LAD instrument is the Module, and in this paper we summarize the rationale for the module concept, the characteristics of the module and the trade-offs/optimisations which have led to the current design.
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    ABSTRACT: The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission will provide full-sun and high-resolution image sequences of the solar atmosphere at selected spectral emission lines in the extreme and vacuum ultraviolet. After the breadboarding and prototyping activities that focused on key technologies, the EUI project has completed the design phase and has started the final manufacturing of the instrument and its validation. The EUI instrument has successfully passed its Critical Design Review (CDR). The process validated the detailed design of the Optical Bench unit and of its sub-units (entrance baffles, doors, mirrors, camera, and filter wheel mechanisms), and of the Electronic Box unit. In the same timeframe, the Structural and Thermal Model (STM) test campaign of the two units have been achieved, and allowed to correlate the associated mathematical models. The lessons learned from STM and the detailed design served as input to release the manufacturing of the Qualification Model (QM) and of the Flight Model (FM). The QM will serve to qualify the instrument units and sub-units, in advance of the FM acceptance tests and final on-ground calibration.
    SPIE Astronomical Telescopes + Instrumentation; 07/2014
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    ABSTRACT: The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1′′ and 0.3′′), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280′′ on the Sun with 0.14′′ per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s − 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission.
    Experimental Astronomy 10/2012; 34(2). DOI:10.1007/s10686-011-9274-x · 2.66 Impact Factor
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    ABSTRACT: The Large Observatory for X-ray Timing (LOFT) is one of the four candidate ESA M3 missions considered for launch in the 2022 time-frame. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. The LOFT scientific payload is composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a 10 m2-class pointed instrument with 20 times the collecting area of the best past timing missions (such as RXTE) over the 2-30 keV range, which holds the capability to revolutionize studies of X-ray variability down to the millisecond time scales. Its ground-breaking characteristic is a low mass per unit surface, enabling an effective area of ~10 m^2 (@10 keV) at a reasonable weight. The development of such large but light experiment, with low mass and power per unit area, is now made possible by the recent advancements in the field of large-area silicon detectors - able to time tag an X-ray photon with an accuracy <10 {\mu}s and an energy resolution of ~260 eV at 6 keV - and capillary-plate X-ray collimators. In this paper, we will summarize the characteristics of the LAD instrument and give an overview of its capabilities.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2012; DOI:10.1117/12.925156 · 0.20 Impact Factor
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    ABSTRACT: The LOFT mission concept is one of four candidates selected by ESA for the M3 launch opportunity as Medium Size missions of the Cosmic Vision programme. The launch window is currently planned for between 2022 and 2024. LOFT is designed to exploit the diagnostics of rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars, as well as the physical state of ultra-dense matter. These primary science goals will be addressed by a payload composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a collimated (<1 degree field of view) experiment operating in the energy range 2-50 keV, with a 10 m^2 peak effective area and an energy resolution of 260 eV at 6 keV. The WFM will operate in the same energy range as the LAD, enabling simultaneous monitoring of a few-steradian wide field of view, with an angular resolution of <5 arcmin. The LAD and WFM experiments will allow us to investigate variability from submillisecond QPO's to year-long transient outbursts. In this paper we report the current status of the project.
    Experimental Astronomy 09/2012; 34(2). DOI:10.1007/s10686-011-9237-2 · 2.66 Impact Factor
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    ABSTRACT: The ORIGIN concept is a space mission with a gamma ray, an X-ray and an optical telescope to observe the gamma ray bursts at large Z to determine the composition and density of the intergalactic matter in the line of sight. It was an answer to the ESA M3 call for proposal. The optical telescope is a 0.7-m F/1 with a very small instrument box containing 3 instruments: a slitless spectrograph with a resolution of 20, a multi-imager giving images of a field in 4 bands simultaneously, and a cross-dispersed Échelle spectrograph giving a resolution of 1000. The wavelength range is 0.5 μm to 1.7 μm. All instruments fit together in a box of 80 mm x 80 mm x 200 mm. The low resolution spectrograph uses a very compact design including a special triplet. It contains only spherical surfaces except for one tilted cylindrical surface to disperse the light. To reduce the need for a high precision pointing, an Advanced Image Slicer was added in front of the high resolution spectrograph. This spectrograph uses a simple design with only one mirror for the collimator and another for the camera. The Imager contains dichroics to separate the bandwidths and glass thicknesses to compensate the differences in path length. All 3 instruments use the same 2k x 2k detector simultaneously so that telescope pointing and tip-tilt control of a fold mirror permit to place the gamma ray burst on the desired instrument without any other mechanism.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2012; DOI:10.1117/12.926656 · 0.20 Impact Factor
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    ABSTRACT: The Exoplanet Characterisation Observatory (EChO) is a space mission dedicated to undertaking spectroscopy of transiting exoplanets over the widest wavelength range possible. It is based around a highly stable space platform with a 1.2 m class telescope. The mission is currently being studied by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The payload instrument is required to provide simultaneous coverage from the visible to the mid-infrared and must be highly stable and effectively operate as a single instrument. This paper presents the architectural design for the highly interlinked mechanical and thermal aspects of our instrument design. The instrument will be passively cooled to approximately 40K along with the telescope in order to maintain the necessary sensitivity and photometric stability out to mid-infrared wavelengths. Furthermore other temperature stages will be required within the instrument, some of which will implement active temperature control to achieve the necessary thermal stability. We discuss the major design drivers of this complex system such as the need for multiple detector system temperatures of approximately 160K, 40K and 7K all operating within the same instrument. The sizing cases for the cryogenic system will be discussed and the options for providing the cooling of detectors to approximately 7K will be examined. We discuss the trade-offs that we are undertaking to produce a technically feasible payload design which will enable EChO’s exciting science.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2012; DOI:10.1117/12.925922 · 0.20 Impact Factor
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    ABSTRACT: The Exoplanet Characterisation Observatory (EChO) is a space mission dedicated to undertaking spectroscopy of transiting exoplanets over the widest wavelength range possible. It is based around a highly stable space platform with a 1.2 m class telescope. The mission is currently being studied by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The payload suite is required to provide simultaneous coverage from the visible to the mid-infrared and must be highly stable and effectively operate as a single instrument. In this paper we describe the integrated spectrometer payload design for EChO which will cover the 0.4 to 16 micron wavelength band. The instrumentation is subdivided into 5 channels (Visible/Near Infrared, Short Wave InfraRed, 2 x Mid Wave InfraRed; Long Wave InfraRed) with a common set of optics spectrally dividing the input beam via dichroics. We discuss the significant design issues for the payload and the detailed technical trade-offs that we are undertaking to produce a payload for EChO that can be built within the mission and programme constraints and yet which will meet the exacting scientific performance required to undertake transit spectroscopy.
    SPIE Proceedings of Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave; 07/2012
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    ABSTRACT: High-time-resolution X-ray observations of compact objects provide direct access to strong field gravity, black hole masses and spins, and the equation of state of ultra-dense matter. LOFT, the large observatory for X-ray timing, is specifically designed to study the very rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars. A 10 m^2-class instrument in combination with good spectral resolution (<260 eV @ 6 keV) is required to exploit the relevant diagnostics and holds the potential to revolutionise the study of collapsed objects in our Galaxy and of the brightest supermassive black holes in active galactic nuclei. LOFT will carry two main instruments: a Large Area Detector (LAD), to be built at MSSL/UCL with the collaboration of the Leicester Space Research Centre for the collimator) and a Wide Field Monitor (WFM). The ground-breaking characteristic of the LAD (that will work in the energy range 2-30 keV) is a mass per unit surface in the range of ~10 kg/m^2, enabling an effective area of ~10 m^2 (@10 keV) at a reasonable weight and improving by a factor of ~20 over all predecessors. This will allow timing measurements of unprecedented sensitivity, allowing the capability to measure the mass and radius of neutron stars with ~5% accuracy, or to reveal blobs orbiting close to the marginally stable orbit in active galactic nuclei. In this contribution we summarise the characteristics of the LOFT instruments and give an overview of the expectations for its capabilities.
    Proceedings of the International Astronomical Union 01/2012; 7(S285). DOI:10.1017/S1743921312001111
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    ABSTRACT: Understanding the solar outer atmosphere requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1" and 0.3"), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 17 and 127 nm. The LEMUR slit covers 280" on the Sun with 0.14" per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km/s or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission.
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    ABSTRACT: This paper describes the design, development and performance of the engineering model double adiabatic demagnetization refrigerator (dADR) built and tested under contract to the European Space Agency for its former mission XEUS (now IXO). The dADR operates from a 4 K bath and has a measured recycle and hold time (with a parasitic load of 2.34 μW) at 50 mK of 15 h and 10 h, respectively. It is shown that the performance can be significantly improved by operating from a lower bath temperature and replacing the current heat switches with tungsten magnetoresistive (MR) heat switches, which significantly reduce the parasitic heat load. Performing the latter gives an anticipated recycle and hold time of 2 and 29 h (with a 1 μW applied heat load in addition to the parasitic load), respectively. Such improved performance allows for a reduction in mass of the dADR from 32 kg to 10 kg by operating from a 2.5 K bath (which could be reduced further by optimising the magnet design). Ultimately, continuous operation could be achieved by linking two dADRs to a common detector stage and operating them alternately. Based on this design the mass of the continuous ADR is estimated to be about 4.5 kg.
    Cryogenics 09/2010; DOI:10.1016/j.cryogenics.2010.02.024 · 0.94 Impact Factor
  • L. Van Driel · J. -c. Vial · B. Winter · A. Zhukov
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    ABSTRACT: The scientific objectives of Solar Orbiter rely ubiquitously on EUI, its suite of solar atmosphere imaging telescopes. In the configuration discussed here, EUI includes three co-aligned High Resolution Imagers (HRI) and one Full Sun Imager (FSI). FSI and two HRIs observe in extreme ultraviolet passbands, dominated by coronal emission. Another HRI is designed for the hydrogen Lyman α radiation in the far UV, imaging the Chromosphere and the lower Transition Region. The current EUI design and some of its development challenges are highlighted. EUI profits from co-rotation phases, solar proximity and departure from the ecliptic. In synergy with the other S.O. payload, EUI probes the dynamics of the solar atmosphere, provides context data for all investigations and helps to link in-situ and remote-sensing observations. In short, it serves all four top-level goals of the mission. For these reasons, the EUI suite is keenly anticipated in the European scientific community and beyond. 1.
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    ABSTRACT: The Spectral and Photometric Imaging Receiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 microns, and an imaging Fourier Transform Spectrometer (FTS) which covers simultaneously its whole operating range of 194-671 microns (447-1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4' x 8', observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6'. The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5-2.
    Astronomy and Astrophysics 05/2010; 518(L3). DOI:10.1051/0004-6361/201014519 · 4.48 Impact Factor
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    R Gowen · A Smith · B Winter · C Theobald · K Rees · AJ Ball · A Hagermann · S Sheridan · P Brown · T Oddy · [...] · Y Gao · A Jones · KH Joy · I Crawford · T Pike · S Kumar · T Hopf · N Wells · K Green · K Ryden
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    ABSTRACT: The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona and upper transition region emission lines in the wavelength ranges 170 – 210Å and 250 – 290Å. The line centroid positions and profile widths will allow plasma velocities and turbulent or non-thermal line broadenings to be measured. We will derive local plasma temperatures and densities from the line intensities. The spectra will allow accurate determination of differential emission measure and element abundances within a variety of corona and transition region structures. These powerful spectroscopic diagnostics will allow identification and characterization of magnetic reconnection and wave propagation processes in the upper solar atmosphere. We will also directly study the detailed evolution and heating of coronal loops. The EIS instrument incorporates a unique two element, normal incidence design. The optics are coated with optimized multilayer coatings. We have selected highly efficient, backside-illuminated, thinned CCDs. These design features result in an instrument that has significantly greater effective area than previous orbiting EUV spectrographs with typical active region 2 – 5s exposure times in the brightest lines. EIS can scan a field of 6×8.5arc min with spatial and velocity scales of 1arc sec and 25km s−1 per pixel. The instrument design, its absolute calibration, and performance are described in detail in this paper. EIS will be used along with the Solar Optical Telescope (SOT) and the X-ray Telescope (XRT) for a wide range of studies of the solar atmosphere.
    Solar Physics 09/2007; 243(1):19-61. DOI:10.1007/s01007-007-0293-1 · 3.81 Impact Factor
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    ABSTRACT: Results are described from a high-stability multi-CCD demonstration focal plane assembly developed by MSSL under ESA contract, using new large-format CCD42-C0s from e2v technologies. Space-based planetary-transit hunting and asteroseismology missions such as ESA's Eddington and NASA's Kepler require large multi-CCD focal planes with a stringent requirement on stability, both thermal and electronic. Other significant requirements are wide dynamic range and a moderately high readout rate of ∼1.2 Mpix s−1 per output (in this case using a 16 bit CCD signal processor ASIC from CCLRC RAL). The high digital data rate (Eddington has in total ∼3 focal planes each with 12 output chains) is achieved using SpaceWire links. The demo-FPA is flight-representative in terms of performance, mass, power and component selection. This work provides real-world data for future ESA studies. It is also compatible with the Gaia radial velocity spectrometer (RVS) focal plane, which has many similar requirements.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 04/2007; 573:253-256. DOI:10.1016/j.nima.2006.10.260 · 1.32 Impact Factor