B. Winter

University College London, Londinium, England, United Kingdom

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Publications (23)22.71 Total impact

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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.
    08/2014;
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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.
    08/2014;
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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.
    08/2014;
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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). · 2.97 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.
    09/2012;
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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.
    Proc SPIE 09/2012;
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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;
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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.
    09/2011;
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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. Comment: Accepted for publication in Astronomy & Astrophyics (Herschel first results special issue)
    Astronomy and Astrophysics 05/2010; 518(L3). · 5.08 Impact Factor
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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 01/2010; · 1.17 Impact Factor
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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-alpha 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.
    Marsch, E.; Tsinganos, K.; Marsden, R.; Conroy, L.: The Second Solar Orbiter Workshop, 16-20 October 2006, Athens, Greece, ESA Publ. Div. (2007). 01/2007;
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    ABSTRACT: The ESI instrument (European SPICA Instrument) is a proposed imaging spectrometer for the 30-210μm band for the JAXA SPICA mission. The instrument will have unprecedented spatial resolution and sensitivity due to the large 03.5m telescope aperture, cold fore-optics (~5K) and high sensitivity detectors (NEP~10-19W/√Hz). One of the key technical challenges of the design of the instrument is the thermal architecture due to the mass and cryogenic heat load constraints and the need for very low temperatures. Two candidate detector technologies have been pre-selected for inclusion in the instrument Phase-A study; Photoconductors and TES Bolometers. An overview of thermal architecture of the SPICA spacecraft is presented in order to explain the thermal interface constraints imposed on the instrument. Proposed thermal architectures for the instrument for both the TES and the Photoconductor options will be outlined including a novel design for a lightweight hybrid cooler for achieving sub 100-mK detector temperatures. This novel cooler architecture utilizes a combination of ADR and sorption coolers. Several design solutions for achieving high thermal isolation generic to both detector options are presented.
    Proc SPIE 07/2006;
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    ABSTRACT: The design of the 300 mK system for Herschel-SPIRE is complex, with many difficult, sometimes conflicting, requirements and constraints placed upon it. Five detector arrays, mounted from a 2 K box, are linked to a single 3He sorption-cooler tip by a high-conductance copper strap network. This strap retains high thermal conductance, even though it incorporates an electrical break to comply with the SPIRE grounding scheme. It requires stiffness to withstand launch vibrations, but needs compliance to avoid transmission of loads to the detector arrays. The strap is stiffly supported by novel, compact cryogenic stand-offs which provide a high degree of thermal isolation from the 2 K stage. An additional complication is that the detectors reside in a 2 K environment, whilst the cooler tip is in a 4 K environment. Two of the cryogenic stand-offs also act as light-tight feed-throughs to pass the strap from the 4 K environment to the inside of the 2 K detector boxes. Active thermal control is provided on the 300 mK system to address the detector stability requirements. This paper describes the system, and gives results of the performance in SPIRE flight model ground tests.
    Proc SPIE 01/2006;
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    ABSTRACT: We have systematically investigated the thermal and particle stability of several state-of-the-art EUV multilayer coatings suitable for use in high-performance solar instrumentation. Our research has been motivated principally by the performance requirements for extreme solar missions such as Solar Orbiter, an approved ESA mission with an expected launch date of 2013. The goal of this particular mission is to explore the solar atmosphere with both in situ and remote sensing instrumentation at a close encounter. At perihelion the mission will reach 0.2 A.U. providing a unique viewpoint where the instruments can both 'see' and 'feel' the dynamic atmosphere. But the orbit is technically challenging- no remote sensing instrument has been put in such close proximity to the Sun before. Furthermore, the thermal and particle environment will not only be severe but will suffer huge fluctuations as the elliptical orbit changes from 0.2 A.U. to 1.1 A.U. Several of the remote sensing packages on the strawman payload of the mission contain multilayer coatings, thus the stability of these coatings to the expected thermal and particle environment must be established. In this paper, we investigate the impact on the integrity of several candidate EUV multilayer coatings after long-term thermal annealing, and upon exposure to energetic protons and neutrons. In summary, we find no significant degradation in any of the multilayer samples tested. These results suggest that the multilayers we have studied can be safely used for Solar Orbiter or other extreme solar missions.
    Proc SPIE 08/2005;
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    ABSTRACT: The Extreme Ultraviolet Imaging Spectrometer (EIS) is a core instrument on the Japanese Solar-B mission and is due for launch in the summer of 2006. EIS is a 3.2 m long telescope employing grating optics and a pair of charge coupled device imaging cameras working in the extreme ultraviolet (EUV) region in two separate wavelength bands between 170-210 and 240-290 Å. To house all the telescope subsystems, a novel carbon fibre reinforced plastic structure was developed in collaboration with McLaren Composites Limited (UK) to meet a set of the demanding performance requirements in terms of dimensional stability, rigidity, and structural cleanliness as well as being able to survive the harsh launch environment of the Japanese M-V rocket. The final design was based on a honeycomb panel structure using stiff carbon fibre laminates. This case study describes some of the design challenges that were overcome for this project to produce the engineering, mechanical, and thermal models. Particular attention is given to the cleanliness control strategy to preserve the EUV optical throughput, the method of attachment to the spacecraft, and of optical subsystems as well as the instrument thermal design.
    Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications 07/2005; 219(3):177-186. · 0.56 Impact Factor
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    ABSTRACT: The definition and optimization studies for the Gaia satellite spectrograph, the ‘radial velocity spectrometer’ (RVS), converged in late 2002 with the adoption of the instrument baseline. This paper reviews the characteristics of the selected configuration and presents its expected performance. The RVS is a 2.0 × 1.6 degree integral field spectrograph, dispersing the light of all sources entering its field of view with a resolving power R=λ/Δλ= 11 500 over the wavelength range [848, 874] nm. The RVS will continuously and repeatedly scan the sky during the 5-yr Gaia mission. On average, each source will be observed 102 times over this period. The RVS will collect the spectra of about 100–150 million stars up to magnitude V≃ 17–18. At the end of the mission, the RVS will provide radial velocities with precisions of ∼2 km s−1 at V= 15 and ∼15–20 km s−1 at V= 17, for a solar-metallicity G5 dwarf. The RVS will also provide rotational velocities, with precisions (at the end of the mission) for late-type stars of σvsin i≃ 5 km s−1 at V≃ 15 as well as atmospheric parameters up to V≃ 14–15. The individual abundances of elements such as silicon and magnesium, vital for the understanding of Galactic evolution, will be obtained up to V≃ 12–13. Finally, the presence of the 862.0-nm diffuse interstellar band (DIB) in the RVS wavelength range will make it possible to derive the three-dimensional structure of the interstellar reddening.
    Monthly Notices of the Royal Astronomical Society 10/2004; 354(4):1223 - 1238. · 5.52 Impact Factor
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    ABSTRACT: The design of an engineering model ADR system to cool cryogenic detectors to 50–30 mK is presented which is designed to be cooled via a 4–5 K space cryocooler. The system will be subjected to vibration qualification suitable for an Ariane 5 launch. The ADR is of a double ADR form comprising a chromic potassium alum (CPA) low temperature stage and dysprosium gallium garnet (DGG) high temperature stage. Details of the 3 Tesla (< 2.5 Amp) magnet system and the magnetic shielding for the detector focal plane and potential spacecraft are given with modelled results.
    Hepburn, I.D. and Brockley-Blatt, C. and Coker, P. and Crofts, E. and Winter, B. and Milward, S. and Stafford-Allen, R. and Hunt, R. and Brownhill, M. and Rando, N. and Linder, M. (2004) Space engineering model cryogen free ADR for future ESA space missions. In: Waynert, J. and Barclay, J. and Breon, S. and Daly, E. and Demko, J. and DiPirro, M. and Hull, J.R. and Kelley, P.J. and Kittel, P. and Klebaner, A. and Lock, J. and Maddocks, J. and Pfotenhauer, J. and Rey, C. and Shu, Q.-S. and Van Sciver, S. and Weisend II, J.G. and Zbasnik, J. and Zeller, A., (eds.) Advances in Cryogenic Engineering: Transactions of the Cryogenic Engineering Conference - CEC: Volume 49A / Volume 49 B. AIP Conference Proceedings (710). American Institute of Physics, Anchorage, US, pp. 1737-1745. ISBN 9780735401860. 06/2004;
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    http://dx.doi.org/10.1051/0004-6361/201014519.
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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 243(1):19-61. · 3.26 Impact Factor