The eXTP (enhanced X-ray Timing and Polarimetry) mission is a major project of the Chinese Academy of Sciences (CAS) and China National Space Administration (CNSA) currently performing an extended phase A study and proposed for a launch by 2025 in a low-earth orbit. The eXTP scientific payload envisages a suite of instruments (Spectroscopy Focusing Array, Polarimetry Focusing Array, Large Area Detector and Wide Field Monitor) offering unprecedented simultaneous wide-band X-ray spectral, timing and polarimetry sensitivity. A large European consortium is contributing to the eXTP study and it is expected to provide key hardware elements, including a Large Area Detector (LAD). The LAD instrument for eXTP is based on the design originally proposed for the LOFT mission within the ESA context. The eXTP/LAD envisages a deployed 3.4 m2 effective area in the 2-30 keV energy range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to 200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper we provide an overview of the LAD instrument design, including new elements with respect to the earlier LOFT configuration.
We report on the design, development and measured performance of the Microchannel plate X-ray optics for the Mercury imaging X-ray spectrometer instrument, due to fly to Mercury on the ESA/JAXA BepiColombo mission in 2018. This paper serves as a progress update, identifying further work to finish the analysis of data from the flight model.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a French-Chinese space mission to be launched in 2021 with the goal of studying gamma-ray bursts, the most powerful stellar explosions in the Universe. The Microchannel X-ray Telescope (MXT) on-board SVOM, is an X-ray focusing telescope with a detector-limited field of view of ∼1 square° , working in the 0.2-10 keV energy band. The MXT is a narrow-field-optimised lobster eye telescope, designed to promptly detect and accurately locate gamma-ray bursts afterglows. The breadboard MXT optic comprises of an array of square pore micro pore optics (MPOs) which are slumped to a spherical radius of 2 m giving a focal length of 1 m and an intrinsic field of view of ∼6° . We present details of the baseline design and results from the ongoing X-ray tests of the breadboard and structural thermal model MPOs performed at the University of Leicester and at Panter. In addition, we present details of modelling and analysis which reveals the factors that limit the angular resolution, characteristics of the point spread function and the efficiency and collecting area of the currently available MPOs.
eXTP is a science mission designed to study the state of matter under extreme conditions of density, gravity and magnetism. Primary goals are the determination of the equation of state of matter at supra-nuclear density, the measurement of QED effects in highly magnetized star, and the study of accretion in the strong-field regime of gravity. Primary targets include isolated and binary neutron stars, strong magnetic field systems like magnetars, and stellar-mass and supermassive black holes. The mission carries a unique and unprecedented suite of state-of-the-art scientific instruments enabling for the first time ever the simultaneous spectral-timing-polarimetry studies of cosmic sources in the energy range from 0.5-30 keV (and beyond). Key elements of the payload are: the Spectroscopic Focusing Array (SFA) - a set of 11 X-ray optics for a total effective area of ∼0.9 m2 and 0.6 m2 at 2 keV and 6 keV respectively, equipped with Silicon Drift Detectors offering <180 eV spectral resolution; the Large Area Detector (LAD) - a deployable set of 640 Silicon Drift Detectors, for a total effective area of ∼3.4 m2, between 6 and 10 keV, and spectral resolution better than 250 eV; the Polarimetry Focusing Array (PFA) – a set of 2 X-ray telescope, for a total effective area of 250 cm2 at 2 keV, equipped with imaging gas pixel photoelectric polarimeters; the Wide Field Monitor (WFM) - a set of 3 coded mask wide field units, equipped with position-sensitive Silicon Drift Detectors, each covering a 90 degrees x 90 degrees field of view. The eXTP international consortium includes major institutions of the Chinese Academy of Sciences and Universities in China, as well as major institutions in several European countries and the United States. The predecessor of eXTP, the XTP mission concept, has been selected and funded as one of the so-called background missions in the Strategic Priority Space Science Program of the Chinese Academy of Sciences since 2011. The strong European participation has significantly enhanced the scientific capabilities of eXTP. The planned launch date of the mission is earlier than 2025.
The Large Observatory For x-ray Timing (LOFT) is a mission concept which was proposed to ESA as M3 and M4 candidate in the framework of the Cosmic Vision 2015-2025 program. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument and the uniquely large field of view of its wide field monitor, LOFT will be able to study the behaviour of matter in extreme conditions such as the strong gravitational field in the innermost regions close to black holes and neutron stars and the supra-nuclear densities in the interiors of neutron stars. The science payload is based on a Large Area Detector (LAD, >8m2 effective area, 2-30 keV, 240 eV spectral resolution, 1 degree collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g., GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the current technical and programmatic status of the mission.
We identify all the significant aberrations that limit the performance of square pore micro-channel plate optics (MPOs) used as an X-ray lobster eye. These include aberrations intrinsic to the geometry, intrinsic errors associated with the slumping process used to introduce a spherical form to the plates and imperfections associated with the plate manufacturing process. The aberrations are incorporated into a comprehensive software model of the X-ray response of the optics and the predicted imaging response is compared with the measured X-ray performance obtained from a breadboard lobster eye. The results reveal the manufacturing tolerances which limit the current performance of MPOs and enable us to identify particular intrinsic aberrations which will limit the ultimate performance we can expect from MPO-lobster eye telescopes.
The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.
The Large Observatory For X-ray Timing (LOFT) is one of the 5 missions considered by ESA as an M3 candidate. The LOFT scientific payload consists of a collimated Large Area Detector (LAD) and a Wide Field Monitor (WFM).
The scale of the LAD (10 m² effective area) puts it in a new design space for X-ray astronomy, with resulting implications for design trade-offs, modularity, manufacturing, assembly, test and calibration processes. This paper focuses on the LAD module, which is the building block of the instrument. We present the overall module design, discussing these challenges and how they have been addressed.
We present the Microchannel X-ray Telescope, a new light and compact focussing telescope that will be ying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science. The MXT design is based on the coupling of square pore micro-channel plates with a low noise pnCCD. MXT will provide an effective area of about 50 cm2, and its point spread function is expected to be better than 3.7 arc min (FWHM) on axis. The estimated sensitivity is adequate to detect all the afterglows of the SVOM GRBs, and to localize them to better then 60 arc sec after five minutes of observation.
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 m2-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 reproposed 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.
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 ultradense 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 m2 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 yearlong transient outbursts. In this paper we report the current status of the project.
The Large Observatory for X-ray Timing (LOFT) is one of the four candidate ESA M3 missions considered for launch in
the 2022 timeframe. 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 m2 (@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 μs 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.
We report progress in the design, theoretical modeling and experimental characterisation of microchannel plate
(MCP) X-ray optics for the BepiColombo Mercury Imaging X-ray Spectrometer (MIXS). We show that MCP
optics technology allows the design of a highly capable imaging telescope with 1 m focal length, a 1° field of
view and approximately 50 cm2 of on-axis effective area at 1 keV. Of a total instrument mass budget 7.3 kg, less
than 2.3 kg is allocated to the optics assemblies, telescope tubes, support structures and the electron diverters
(used to deflect electrons from the focal plane). The instrument science goals require an imaging resolution of 9
arcminutes, with a design goal of 2 arcminutes. Recent experimental data, taken from individual optic elements
is presented to show that MCP quality is in good agreement with the error budgets assumed in theoretical
calculations of performance.
We report progress in the design of the BepiColombo Mercury Imaging X-ray Spectrometer (MIXS). This instrument
consists of two modules; a Wolter I soft X-ray telescope based on radially packed microchannel plate
optics (MIXS-T) and a profiled collimator which uses a square pore square packed microchannel plate array to
restrict its field of view (MIXS-C). Both instrument modules have identical focal planes (DEPFET macropixel
array) providing an energy resolution of better than 200 eV FWHM throughout the mission.
The primary science goal of MIXS is to perform X-ray fluorescence spectroscopy of the Hermean surface with
unprecedented spatial and energy resolution. This allows discrimination between different regolith types, and
by combining with data from other instruments, between competing models of crustal evolution and planetary
formation. MIXS will also probe the complex coupling between the planet's surface, exosphere and magnetosphere
by observing Particle Induced X-ray Emission (PIXE).
We review past and current attempts to measure X-ray polarization in celestial sources and describe research
activity into a new family of materials which have been shown to exhibit linear dichroism at X-ray wavelengths.
Such materials could add a polarimetry capability to the high energy resolution detectors proposed for future,
high effective area, X-ray astrophysical observatories such as Constellation-X and XEUS. They have the potential
to achieve useful minimum detectable polarization values for a number of sources in a sensible exposure time