eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian/German Spektrum-Roentgen-Gamma (SRG) mission which is now officially scheduled for launch on March 26, 2016. eROSITA will perform a deep survey of the entire X-ray sky. In the soft band (0.5-2 keV), it will be about 30 times more sensitive than ROSAT, while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the sky. The design driving science is the detection of large samples of galaxy clusters to redshifts z < 1 in order to study the large scale structure in the universe and test cosmological models including Dark Energy. In addition, eROSITA is expected to yield a sample of a few million AGN, including obscured objects, revolutionizing our view of the evolution of supermassive black holes. The survey will also provide new insights into a wide range of astrophysical phenomena, including X-ray binaries, active stars and diffuse emission within the Galaxy. eROSITA is currently (June 2014) in its flight model and calibration phase. All seven flight mirror modules (+ 1 spare) have been delivered and measured in X-rays. The first camera including the complete electronics has been extensively tested (vacuum + X-rays). A pre-test of the final end-toend test has been performed already. So far, all subsystems and components are well within their expected performances.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is fully approved and funded by the German Space Agency DLR and the Max-Planck-Society. The instrument development is in phase C/D since fall 2009. The design driving science is the detection 100.000 Clusters of Galaxies up to redshift z ~1.3 in order to study the large scale structure in the Universe and test cosmological models, especially Dark Energy. This will be accomplished by an all-sky survey lasting for four years plus a phase of pointed observations. eROSITA consists of seven Wolter-I telescope modules, each equipped with 54 Wolter-I shells having an outer diameter of 360 mm. This would provide an effective area of ~1500 cm<sup>2</sup> at 1.5 keV and an on axis PSF HEW of 15 arcsec resulting in an effective angular resolution of 28 - 30 arcsec, averaged over the field of view. In the focus of each mirror module, a fast frame-store pn-CCD provides a field of view of 1° in diameter.
The Spectrum-Roentgen-Gamma mission will be launched in the 2012 year into a L2 orbit with Soyuz launcher and
Fregat buster from Baikonur. The mission will conduct all-sky survey with X-ray mirror telescopes eROSITA and
ART-XC up to 11 keV. It will allow detection of about 100 thousand clusters of galaxies and discovery large scale
Universe structure. It will also discover all obscured accreting Black Holes in nearby galaxies and many (about
3 millions) new distant AGN. Then it is planned to observe dedicated sky regions with high sensitivity and thereafter to
perform follow-up pointed observations of selected sources.
Simbol-X is a French-Italian-German hard energy X-ray mission with a projected launch in 2014. Being sensitive in the
energy range from 500 eV to 80 keV it will cover the sensitivity gap beyond the energy interval of today's telescopes
XMM-Newton and Chandra. Simbol-X will use an imaging telescope of nested Wolter-I mirrors. To provide a focal
length of 20 m it will be the first mission of two independent mirror and detector spacecrafts in autonomous formation
The detector spacecraft's payload is composed of an imaging silicon low energy detector in front of a pixelated
cadmium-telluride hard energy detector. Both have a sensitive area of 8 × 8 cm<sup>2</sup> to cover a 12 arcmin field of view and a pixel size of 625 × 625 μm<sup>2</sup> adapted to the telescope's resolution of 20 arcsec. The additional LED specifications are:
high energy resolution, high quantum efficiency, fast readout and optional window mode, monolithic device with 100 %
fill factor and suspension mounting, and operation at warm temperature.
To match these requirements the low energy detector is composed of 'active macro pixels', combining the large, scalable
area of a Silicon Drift Detector and the low-noise, on-demand readout of an integrated DEPFET amplifier. Flight
representative prototypes have been processed at the MPI semiconductor laboratory, and the prototype's measured
performance demonstrates the technology readiness.
The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration
optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be
launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The
optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four
modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the
adjacent eROSITA telescope detector) will allow the detection of
X-ray photons up to 15 keV. The field of view of the
individual mirror module is about 18×18 arcminutes<sup>2</sup> and the sensitivity of the ART-XC system for 4 years of survey
will be better than 10<sup>-12</sup> erg s<sup>-1</sup> cm<sup>-2</sup> over the 4-12 keV energy band. This will allow the ART-XC instrument to discover
several thousands new AGNs.
The German X-ray observatory eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the prime
instrument of the new Spectrum-RG mission. Launch of the Russian satellite is planned for the year 2011. The scientific
goal of eROSITA is primarily the detection and analysis of 100 thousand clusters of galaxies in order to study the large
scale structures in the Universe and to test cosmological models. The therefore required large effective area is obtained
by an array of seven identical and parallel aligned Wolter-I telescopes. In the focus of each mirror module, there is a
large frame store pnCCD detector, providing a field of view of 1° in diameter. The same X-ray detector type will also be
applied for ART-XC, another grazing-incidence telescope system aboard Spectrum-RG, which permits the detection of
heavily obscured X-ray sources. These scientific instruments allow the exploration of the X-ray Universe in the energy
band from 0.3 keV to 11 keV. During a mission time of at least five years, an all-sky survey, wide as well as deep
surveys and pointed observations will be performed. Approval and funding for eROSITA were granted by the German
space agency DLR in April 2007.
The conceptual design of the X-ray focal plane cameras is presented here comprising electrical, thermal, and mechanical
aspects. Key part of the camera is the pnCCD detector chip, which is developed and produced in our semiconductor
laboratory, the MPI Halbleiterlabor. The CCD was designed according to the specifications given by the scientific goals
of eROSITA. The eROSITA CCD differs apparently from all previously produced frame store pnCCDs by its larger
size and format. The CCD image area of the seven eROSITA cameras is in total 58 cm<sup>2</sup> large and their number of pixels
is about seven times higher than that of the XMM-Newton pnCCD camera. First pnCCD devices were recently
produced and tested. Their performance measurements and results are of most importance for eROSITA because the
tested CCDs are the control sample of the flight detector production.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) will be one of three main instruments on the
Russian new Spectrum-RG mission which is planned to be launched in 2011. The other two instruments are the wide
field X-ray monitor Lobster (Leicester University, UK) and ART-XC (IKI, Russia), an X-ray telescope working at
higher energies up to 30 keV. A fourth instrument, a micro-calorimeter built by a Dutch-Japanese-US collaboration is
also in discussion. eROSITA is aiming primarily for the detection of 50-100 thousands Clusters of Galaxies up to
redshifts z > 1 in order to study the large scale structure in the Universe and to test cosmological models including the
Dark Energy. For the detection of clusters, a large effective area is needed at low energies (< 2 keV). Therefore,
eROSITA consists of seven Wolter-I telescope modules. Each mirror module contains 54 Wolter-I shells with an outer
diameter of 360 mm. In the focus of each mirror module, a framestore pn-CCD with a size of 3cm × 3cm provides a field
of view of 1° in diameter. The mission scenario comprises a wide survey of the complete extragalactic area and a deep
survey in the neighborhood of the galactic poles. Both are accomplished by an all-sky survey with an appropriate
orientation of the rotation axis of the satellite in order to achieve the deepest exposures in the neighborhood of the
galactic poles. A critical issue is the cooling of the cameras which need a working temperature of -80°C. This will be
achieved passively by a system of two radiators connected to the cameras by variable conductance heat pipes.
A pnCCD detector fulfils all typical requirement specifications to an X-ray detector optimally: The energy of the X-ray
photon is precisely measured, incidence position is determined even more accurate than the pixel size, and the arrival
time of the photon is very well defined by the high frame rate due to complete parallel signal processing. The
probability for detection of an X-ray photon is from 0.3 keV to 10 keV close to 100% and homogeneous over the image
Such a detector has been developed for application in X-ray astronomy. The XMM-Newton space observatory is already
equipped with a pnCCD camera which performs since commissioning in 2000 till this day excellent measurements. For
the upcoming eROSITA telescope on the Spectrum-Roentgen-Gamma satellite, an advanced pnCCD detector system is
presently developed. Seven pnCCD cameras are placed in the foci of seven X-ray mirror systems researching the X-ray
sky during a mission time of 5 years.
For ground based instrumentation the X-ray fluxes can be extremely high, as it is the case in X-ray free electron lasers
(XFELs). The evolving XFELs will make it possible to capture three-dimensional images of the nanocosmos. Here the
focus is set on the measurement of X-ray intensities instead of spectroscopy, i.e. the number of monochromatic photons
per pixel (up to > 1000 photons) is counted at very high frame rates ( > 100/s).
Both projects have again in common the request for large image areas: in case of eROSITA seven times an image area
of 8 cm<sup>2</sup> and for the XFEL experiment at LCLS we provide in a first step a 59 cm<sup>2</sup> large image area. In a second step it
will be enlarged to even 236 cm<sup>2</sup>. We performed recently promising tests with the prototype detectors. Therefore we
started the production of the final devices for both applications in the MPI semiconductor laboratory.
The PANTER X-ray Test Facility was originally designed to support the development and construction of the
ROSAT mirror system. A large instrument chamber (length 12 m, diameter 3.5m) accommodates the optics
to be analysed. The X-ray sources covering an 0.2 - 50 keV energy range are located at a distance of 123m
from the entrance to the chamber to provide an almost parallel X-ray beam. Both are connected by a vacuum
tube of 1m diameter. In addition to ROSAT a large number of astronomical systems like telescopes for Exosat,
BeppoSAX, JET-X, ABRIXAS, XMM-Newton and Swift - but also gratings (e.g., LETG on Chandra), filters,
and focal plane detectors have been measured at the facility. As a "growing facility" we are currently planning to
apply changes to the facility layout to support measurements of instrumentation for future missions like XEUS.
Currently a parallel beam is set up using a spare CDS mirror ("Coronal Diagnostic Spectrometer", for the SOHO
mission) as condensor. Moreover, extensions to vacuum tube and instrument chamber are under consideration,
both to allow calibration of systems with focal lengths significantly longer than XMM-Newton. A new focal plane
camera using a CCD developed for the eROSITA mission will improve spatial and spectral resolution. Finally,
the energy coverage shall be extended to lower and to higher energies. Already with the present configuration
important issues like performance under low temperatures could be investigated.
Simbol-X is a hard X-ray mission, operating in the ~ 0.5-80 keV range, proposed as a collaboration between the French
and Italian space agencies with participation of German laboratories for a launch in 2013. Relying on two spacecraft in a
formation flying configuration, Simbol-X uses for the first time a 20-30 m focal length X-ray mirror to focus X-rays
with energy above 10 keV, resulting in over two orders of magnitude improvement in angular resolution and sensitivity
in the hard X-ray range with respect to non-focusing techniques. The Simbol-X revolutionary instrumental capabilities
will allow us to elucidate outstanding questions in high energy astrophysics such as those related to black-holes accretion
physics and census, and to particle acceleration mechanisms, which are the prime science objectives of the mission.
After having undergone a thorough assessment study performed by CNES in the context of a selection of a formation
flight scientific mission, Simbol-X has been selected for a phase A study to be jointly conducted by CNES and ASI. The
mission science objectives, the current status of the instrumentation and mission design are presented in this paper.
An advanced pnCCD type has been developed, based on the concept of the XMM-Newton detector, which has been
performing spectroscopy and imaging since 2000. This new detector is designed according to the requirements of
eROSITA, a new X-ray astronomy mission, to be launched in 2010. The focal plane for each of the seven individual
Wolter telescopes will be equipped with one of these new-type X-ray pnCCDs. In addition to the eROSITA chips, we
have developed CCDs for other applications, e.g. for projects which require smaller pixel sizes. The devices that have
been produced in the semiconductor laboratory (MPI Halbleiterlabor) of the Max-Planck-Institut fur extraterrestrische
Physik are currently subject of systematic quality checks and spectroscopic tests. These tests are performed under
standardized conditions on a representative subset of the many devices we have produced. The aim of these tests is to
extract the key performance parameters of the individual CCDs like readout noise, energy resolution and the occurrence
of bad pixels. The analysis includes the CAMEX analog signal processor, which has been developed for the readout of
the CCD signals. After an introduction, we present the motivation for the detector development and give an overview
about our CCD design and production, as well as about the CAMEX ASIC. Then device tests, test setups and data
analysis are described. We report in detail about the performance of the tested devices. Failures that occurred during
device tests are subsequently discussed. Finally, we give a review of the results.
We outline a novel satellite mission concept, DEMON, aimed at
advancing our comprehension of both dark matter and dark energy, taking full advantage of two complementary methods: weak lensing and
the statistics of galaxy clusters. We intend to carry out a 5000 deg<sup>2</sup> combined IR, optical and X-ray survey with galaxies up to a redshift of z~2 in order to determine the shear correlation
function. We will also find ~100000 galaxy clusters, making it
the largest survey of this type to date. The DEMON spacecraft will
comprise one IR/optical and eight X-ray telescopes, coupled to
multiple cameras operating at different frequency bands. To a great
extent, the technology employed has already been partially tested on
ongoing missions, therefore ensuring improved reliability.
We present a satellite mission concept to measure the dark energy equation of state parameter ω with percent-level precision. The Very Ambitious Dark Energy Research satellite (VADER) is a multi-wavelength survey mission joining X-ray, optical, and IR instruments for a simultaneous spectral coverage from 4 <i>μ</i>m (0.3 eV) to 10 keV over a field of view (FoV) of 1 square degree. VADER combines several clean methods for dark energy studies, the baryonic acoustic oscillations in the galaxy and galaxy cluster power spectrum and weak lensing, for a joint analysis over an unrivalled survey volume.
The payload consists of two XMM-like X-ray telescopes with an effective area of 2,800 cm<sup>2</sup> at 1.5 keV and state-of-the-art wide field DEPFET pixel detectors (0.1-10 keV) in a curved focal plane configuration to extend the FoV. The X-ray telescopes are complemented by a 1.5m optical/IR telescope with 8 instruments for simultaneous coverage of the same FoV from 0.3<i>μ</i>m to 4<i>μ</i>m. The 8 dichroic-separated bands (u,g,r,z,J,H,K,L) provide accurate photometric galaxy redshifts, whereas the diffraction-limited resolution of the central z-band allows precise shape measurements for cosmic shear analysis.
The 5 year VADER survey will cover a contiguous sky area of 3,500 square degrees to a depth of <i>z</i>~2 and will yield accurate photometric redshifts and multi-wavelength object parameters for about 175,000 galaxy clusters, one billion galaxies, and 5 million AGN. VADER will not only provide unprecedented constraints on the nature of dark energy, but will additionally extend and trigger a multitude of cosmic evolution studies to very large (>10 Gyrs) look-back times.
A medium size satellite will be launched in the 2010-2011 timeframe into a 600 km equatorial (less than or equal to 5 deg.) orbit from
Kourou or into a less than or equal to 30 deg. orbit from Baikonur as a fallback option. The payload includes eROSITA (extended ROentgen
Survey with an Imaging Telescope Array, MPE, Germany) with 7 Wolter-type telescopes, the wide field X-ray monitor
Lobster (LU, UK), the X-ray concentrator based on Kumakhov optics ART or coded-mask X-ray telescopes as a fallback
(IKI, Russia) and GRB detector (Russian consortium). High particle background on high apogee orbits severely affects
the capabilities of X-ray telescopes to study diffuse emission. For new baseline configuration of the SRG mission a low
earth orbit was selected to circumvent this limitation. The mission will conduct the first all-sky survey with an imaging
telescope in the 2-12 keV band to discover the hidden population of several hundred thousand obscured supermassive
black holes and the first all-sky imaging X-ray time variability survey. In addition to the all-sky surveys it is foreseen to
observe the extragalactic sky with high sensitivity to detect 50 to 100 thousand clusters of galaxies and thereafter to do
follow-up pointed observations of selected sources, in order to investigate the nature of Dark Matter and Dark Energy.
The new SRG mission would thus be a highly significant scientific and technological step beyond Chandra/XMM-Newton
and would provide important and timely inputs for the next generation of giant X-ray observatories like
XEUS/Con-X planned for the 2015-2025 horizon.
XEUS is the potential successor to ESA's XMM-Newton X-ray observatory and is being proposed in response to the Cosmic Vision 2015-2025 long term plan for ESA's Science Programme. Novel light-weight optics with an effective area of 5 m<sup>2</sup> at 1 keV and 2 m<sup>2</sup> at 7 keV and 2-5" HEW spatial resolution together with advanced detectors will provide much improved imaging, spectroscopic and timing performances and open new vistas in X-ray astronomy in the post 2015 timeframe. XEUS will allow the study of the birth, growth and spin of the super-massive black holes in early AGN, allow the cosmic feedback between galaxies and their environment to be investigated through the study of inflows and outflows and relativistic acceleration and allow the growth of large scale structures and metal synthesis to be probed using the hot X-ray emitting gas in clusters of galaxies and the warm/hot filamentary structures observable with X-ray absorption spectroscopy. High time resolution studies will allow the Equation of State of supra-nuclear material in neutron stars to be constrained. These science goals set very demanding requirements on the mission design which is based on two formation flying spacecraft launched to the second Earth-Sun Lagrangian point by an Ariane V ECA. One spacecraft will contain the novel high performance optics while the other, separated by the 35 m focal length, will contain narrow and wide field imaging spectrometers and other specialized instruments.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) will be one out of three main instruments on
the Russian new Spectrum-RG mission which will be launched in the timeframe 2010-2011 into an equatorial Low Earth
Orbit. The other two instruments are the wide field X-ray monitor Lobster (Leicester University, UK) and ART (IKI,
Russia), an X-ray concentrator based on a Kumakhov optics. eROSITA consists of seven Wolter-I telescope modules
similar to the German mission ABRIXAS which failed in 1999 and ROSITA, a telescope which was planned to be
installed on the International Space Station ISS. Unlike these, the eROSITA telescope modules will be extended by
adding another 27 mirror shells to the already existing ABRIXAS design. This will increase the effective area by a factor
of ~5 at low energies. The additional shells do not contribute to the area at higher energies ( > 5 keV) due to the relative
large grazing angles. Here we stay with the old ABRIXAS/ROSITA effective area. However, the primary scientific goal
has changed since ABRIXAS: we are now aiming primarily for the detection of 50-100 thousands Clusters of Galaxies
up to redshifts z > 1 in order to study the large scale structure in the Universe and test cosmological models including the
Dark Energy, which was not yet known at ABRIXAS times. For the detection of clusters, a large effective area is needed
at low (< 2 kev) energies. The mission scenario comprises a wide survey of the complete extragalactic area and a deep
survey in the neighborhood of the Galactic Poles. Both are accomplished by an all-sky survey with a tilt of the rotation
axis in order to shift the deepest exposures away from the ecliptic poles towards the galactic poles.
XEUS is the potential successor to ESA's XMM-Newton X-ray observatory and is being proposed in response to the
Cosmic Vision 2015-2025 long term plan for ESA's Science Programme. A new mission configuration was developed
in the last year, accommodating the boundary conditions of a European-led mission with a formation-flying mirror and
detector spacecraft in L2 with a focal length of 35m and an effective area of >5 m<sup>2</sup> at 1 keV. Here the new capabilities
are compared with the key scientific questions presented to the Cosmic Vision exercise: the evolution of large scale
structure and nucleosynthesis, the co-evolution of supermassive black holes and their host galaxies, and the study of
matter under extreme conditions.
In our ongoing studies of high precision glass slumping we have successfully formed the first Wolter-I X-ray mirror
segments with parabola and hyperbola in one piece. It could be demonstrated that the excellent surface roughness of the
0.55 mm thick display glass chosen is conserved during the slumping process. The influence of several parameters of the
process, such as maximum temperature, heating and cooling rates etc. have to be measured and controlled with adequate
metrology. Currently, we are optimizing the process to reduce the figure errors down to 1 micrometer what will be the
starting point for further, final figure error corrections. We point out that metrology plays an important role in achieving a
high precision optics, i.e. an angular resolution of a few arcsec. In this paper we report on the results of our studies and
discuss them in the context of the requirements for future X-ray telescopes with large apertures.
Light sources, focusing elements and detectors working at wavelengths from 5nm to 40nm, so called EUV, are of increasing interest for the semiconductor industry, especially for lithography. A metrology has been developed to characterize modified nested Wolter grazing incidence optics which act as the condenser optic. It consists of a monochromatic EUV source and a MCP detector. The EUV source is designed to emit radiation at a wavelength of 13.5nm into a solid angle of up to 1.8sr, which is realized by a silicon-zirconium target used in transmission. Detector and EUV source have been calibrated. In particular, the angular dependences of the source radiation and the detector efficiency have been investigated. The calibrated metrology could be used for measuring the imaging properties of modified nested Wolter optics revealing the point-spread function (psf), the focal length and the effective collecting area. In this paper we will report on experimental setup in the X-ray test facility "PUMA," developing the EUV source, multi-channel plate detector properties, and the results of testing a modified EUV optics.
SIMBOL-X is a hard X-ray mission, operating in the ~ 0.5-70 keV range, which is proposed by a consortium of European laboratories in response to the 2004 call for ideas of CNES for a scientific mission to be flown on a formation flying demonstrator. Relying on two spacecrafts in a formation flying configuration, SIMBOL-X uses for the first time a ~ 30 m focal length X-ray mirror to focus X-rays with energy above 10 keV, resulting in a two orders of magnitude improvement in angular resolution and sensitivity in the hard X-ray range with respect to non focusing techniques. The SIMBOL-X revolutionary instrumental capabilities will allow to elucidate outstanding questions in high energy astrophysics, related in particular to the physics of accretion onto compact objects, to the acceleration of particles to the highest energies, and to the nature of the Cosmic X-Ray background. The mission, which has gone through a thorough assessment study performed by CNES, is expected to start a competitive phase A in autumn 2005, leading to a flight decision at the end of 2006, for a launch in 2012. The mission science objectives, the current status of the instrumentation and mission design, as well as potential trade-offs are presented in this paper.
Future X-ray missions are aiming at large mirror collecting areas of the order of several square meters. This is obtained with mirror assemblies composed of a large number of segments. The angular resolution of each one must be measured separately down to 1 arcsec. The mass limits imposed by the launchers require low weight and high stiffness materials. In this context we have focused our recent studies on the manufacturing of thin glass mirror segments. These mirrors are made from sheet glass which can be shaped in a high-precision slumping process to e.g. a Wolter-I figure. The excellent surface roughness of the sheet glass chosen is conserved during the slumping process and the final figure corrections with non-contacting tools. The influence of several parameters of the process, such as glass and mould material, heating and cooling, has been measured and controlled with adequate metrology. In this paper we describe our current efforts which are aiming at the production of a Wolter-I scaled demonstration model - preferentially with parabola and hyperbola in one piece - made of thin sheet glass.
While investigating the feasibility of the accommodation of X-ray instrumentations on the International Space Station (ISS) a major question remained still open, i.e. the unknown extent of degradation of X-ray mirror surfaces and X-ray detector material caused by contamination in the ISS environment. Therefore, a sample expose experiment has been started in 2001 to investigate these effects in detail using the Russian expose facility provided by the Russian space industry company RKK Energia. While Kayser-Threde GmbH was responsible to organize and coordinate the experiment, gold-coated Zerodur and silicon samples have been provided by the Max-Planck-Institute (MPE). In total 5 samples were flown with the expose facility and have been exposed to the ISS environment for a total duration of 756 days. The analyses of 4 of them are presented in this paper. X-ray reflection measurements before and after the experiment at MPE's PANTER X-ray test facility and microscopy inspections revealed a thin structured surface layer which reduced the X-ray reflection of the exposed mirror samples dramatically. In addition, the samples have been analyzed with a scanning electron microscope, an energy dispersive X-ray spectrometer, and electron spectroscopy for chemical analysis. The results of all these measurements revealing the degradation of the X-ray mirrors and polished silicon detector surfaces are presented.
A new generation of pnCCDs has been developed for the proposed X-ray astronomy missions, DUO and ROSITA. The DUO/ROSITA CCD is a frame store pnCCD based on the concept of the XMM-Newton pnCCD and has both, improved performance and new features. This detector permits accurate spectroscopy of X-rays as well as imaging and high time resolution with high quantum efficiency in the energy band from 0.3 keV to 10 keV. Interfering electron-hole pair generation due to optical and UV light is prevented by a deposition of an on-chip filter. We describe the frame store pnCCDs developed and fabricated for the DUO and ROSITA missions in the semiconductor laboratory of the Max-Planck-Institut fuer extraterrestrische Physik. An overview about the CCD concept and design is given along with some details about the fabrication of the devices. In addition, we introduce a new analog signal processor which has been developed specifically for the readout of the frame store pnCCD signals. The main focus of this paper is to present the very first measurements with this CCD type and its analog signal processor. Towards this aim we report the operation of this new sensor and its key performance parameters. Finally we discuss ongoing and future tests with the DUO/ROSITA CCDs.
Gamma ray bursts (GRBs) are the most energetic eruptions known in the Universe. Instruments such as Compton-GRO/BATSE and the GRB monitor on BeppoSAX have detected more than 2700 GRBs and, although observational confirmation is still required, it is now generally accepted that many of these bursts are associated with the collapse of rapidly spinning massive stars to form black holes. Consequently, since first generation stars are expected to be very massive, GRBs are likely to have occurred in significant numbers at early epochs. <i>X-red</i> is a space mission concept designed to detect these extremely high redshifted GRBs, in order to probe the nature of the first generation of stars and hence the time of reionisation of the early Universe. We demonstrate that the gamma and x-ray luminosities of typical GRBs render them detectable up to extremely high redshifts (<i>z</i> ~ 10to30), but that current missions such as HETES and SWIFT operate outside the observational range for detection of high redshift GRB afterglows. Therefore, to redress this, we present a complete mission design from teh science case to the mission architecture and payload, the latter comprising three instruments, namely wide field x-ray cameras to detect high redshift gamma-rays, an x-ray focussing telescope to determine accurate coordinates and extract spectra, and an infrared spectrograph to observe the high redshift optical afterglow. The mission is expected to detect and identify for the first time GRBs with <i>z</i> > 10, thereby providing constraints on properties of the first generation of stars and the history of the early Universe.
XEUS is the potential successor to ESA's XMM-Newton X-ray observatory. Novel light-weight optics with an effective area of 10 m<sup>2</sup> at 1 keV and 2-5" HEW spatial resolution together with advanced imaging detectors will provide a sensitivity around 200 times better than XMM-Newton as well as much improved high-energy coverage, and spectroscopic performance. This enormous improvement in scientific capability will open up new vistas in X-ray astronomy. It will allow the detection of massive black holes in the earliest AGN and estimates of their mass, spin and red-shift through their Fe-K line properties. XEUS will study the first gravitationally bound, Dark Matter dominated, systems small groups of galaxies and trace their evolution into today's massive clusters. High-resolution spectroscopy of the hot intra-cluster gas will be used to investigate the evolution of metal synthesis to the present epoch. The hot filamentary structure will be studied using absorption line spectroscopy allowing the mass, temperature and density of the intergalactic medium to be characterized. As well as these studies of the deep universe, the enormous low-energy collecting area will provide a unique capability to investigate bright nearby objects with dedicated high-throughput, polarimetric and time resolution detectors.
The mission ROSITA (ROentgen Survey with an Imaging Telescope Array) will perform the first imaging all-sky survey in the medium energy X-ray range up to 10 keV with an unprecedented spectral and angular resolution. Thus, ROSITA leads to an improved understanding of obscured black holes in Active Galactic Nuclei. In addition, ROSITA represents an important pathfinder for beyond 2015 space telescopes like XEUS and Constellation X. Targeting for a flight in 2008/2009 on one side ROSITA is considered as technology test bed for later X-ray cornerstone missions, on the other side the measurement data will form a good basis for later detailed surveys with the corresponding high resolution pointing systems.
Dark Energy dominates the mass-energy content of the universe (about 73%) but we do not understand it. Most of the remainder of the Universe consists of Dark Matter (23%), made of an unknown particle. The problem of the origin of Dark Energy has become the biggest problem in astrophysics and one of the biggest problems in all of science. The major extant X-ray observatories, the Chandra X-ray Observatory and XMM-Newton, do not have the ability to perform large-area surveys of the sky. But Dark Energy is smoothly distributed throughout the universe and the whole universe is needed to study it. There are two basic methods to explore the properties of Dark Energy, viz. geometrical tests (supernovae) and studies of the way in which Dark Energy has influenced the large scale structure of the universe and its evolution. DUO will use the latter method, employing the copious X-ray emission from clusters of galaxies. Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales is dominated by the Dark Energy. In order to take the next step in understanding Dark Energy, viz. the measurement of the 'equation of state' parameter 'w', an X-ray telescope following the design of ABRIXAS will be accommodated into a Small Explorer mission in lowearth orbit. The telescope will perform a scan of 6,000 sq. degs. in the area of sky covered by the Sloan Digital Sky Survey (North), together with a deeper, smaller survey in the Southern hemisphere. DUO will detect 10.000 clusters of galaxies, measure the number density of clusters as a function of cosmic time, and the power spectrum of density fluctuations out to a redshift exceeding one. When combined with the spectrum of density fluctuations in the Cosmic Microwave Background from a redshift of 1100, this will provide a powerful lever arm for the crucial measurement of cosmological parameters.
What is the nature of the Dark Energy that is driving the universe apart? Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales which is dominated by the Dark Energy. DUO will measure 10.000 clusters of galaxies, the power spectrum of density fluctuations of clusters and their number density as a function of cosmic time. Although designed long before the existence of Dark Energy was claimed, the ABRIXAS type X-ray telescope turns out to be ideally suited for this task: DUO is, in essence, a re-flight of the ABRIXAS X-ray telescope which some modifications of the focal plane instrumentation. First of all, we will use new CCDs which are improved versions of the pn-CCDs successfully flown on XMM-Newton. A modular concept having seven individual cameras in the foci of the seven mirror systems allows us to design the orientation of the seven telescopes with respect to each other matching the scientific needs of the DUO mission. Details of the concept including mechanical, electrical and thermal aspects are given.
DUO and ROSITA are two future X-ray astronomy missions observing in the energy band from about 0.3 keV to 10 keV. While the NASA satellite DUO will scan selected areas of the X-ray sky with high sensitivity, the German ROSITA mission shall perform an all-sky survey. Both missions apply an array of seven Wolter telescopes with separated field of views and seven dedicated PN-CCD focal plane detectors. The focal plane detectors are a further development of the flight-proven PN-CCD applied for the XMM-Newton observatory. The advanced device, called 'frame store PN-CCD', is designed and fabricated in the semiconductor laboratory of the Max-Planck-Institute for extraterrestrial physics. An introduction into the detector concept and design are presented as well as the promising results which have been achieved with the prototype devices. This includes an overview about the performance of the PN-CCD and in detail the recent measurements with the detector. An example is the low energy response of the optimized photon entrance window with integrated optical light filter. As the CAMEX analog signal processor chip is a main component of the detector module, we describe its development status. Furthermore, we report about the application of the mesh experiment to the PN-CCD which allows for a study of the electric potential characteristics in the detector bulk, in particular in the charge transfer depth. The information is of great importance for an accurate knowledge about the drift of the generated signal electrons into the potential wells of the pixels.
A new type of Active Pixel Sensor is proposed which will be capable to meet the requirements of the wide field imager of ESA's future X-ray mission XEUS: the simultaneous energy and position resolved detection of X-rays at high count rate on a large format sensor. The Active Pixel Sensor is based on the integrated detector-amplifier structure DEpleted P-channel Field Effect Transistor (DEPFET). The device operates on a fully depleted bulk and provides internal signal amplification at the position of the charge generation. A very low value of the overall output capacitance leads to extremely low read noise. In the matrix arrangement of an Active Pixel Sensor the single DEPFET pixels can be randomly accessed for readout, and various flexible readout modes are possible. In contrast to CCDs the DEPFET-based Active Pixel Sensor avoids the transfer of signal charges over long distances within the detector bulk, and related problems of transfer loss or out-of-time-events cannot occur. An interesting feature is the non-destructive nature of the DEPFET readout which can be used for the reduction of the low-frequency noise contribution by repetitive readings of the signal information. The device principle of the DEPFET based pixel sensor is explained. First results of single DEPFET measurements are presented.
The fully depleted PN-CCD detector is meanwhile field-tested in several experiments on ground and in space. Its application as focal plane detector aboard ESA's XMM-Newton observatory can be considered as the most impressive one. The further development of this detector type including its readout chip in the MPI semiconductor laboratory is presented here. The new device, called frame store PN-CCD, shows substantial improvement of performance, in particular concerning the energy resolution and the probability of out of time event occurrence. Moreover, the detector offers features which are of great importance for its application in space. This is, besides the radiation hardness of the CCD, the variety of feasible pixel sizes and the high frame rates in combination with the small power consumption of the detector. Because of the thin radiation entrance window and the full depletion of the chip, the detector provides a high quantum efficiency for soft X-rays as well as for optical light and the near infrared. The frame store PN-CCD detector will be applied for the proposed X-ray astronomy missions DUO and ROSITA.
SIMBOL-X is a hard X-ray mission, operating in the 0.5-70 keV range, which is proposed by a consortium of European laboratories for a launch around 2010. Relying on two spacecraft in a formation flying configuration, SIMBOL-X uses a 30 m focal length X-ray mirror to achieve an unprecedented angular resolution (30 arcsec HEW) and sensitivity (100 times better than INTEGRAL below 50 keV) in the hard X-ray range. SIMBOL-X will allow to elucidate fundamental questions in high energy astrophysics, such as the physics of accretion onto Black Holes, of acceleration in quasar jets and in supernovae remnants, or the nature of the hard X-ray diffuse emission. The scientific objectives and the baseline concepts of the mission and hardware design are presented.
The XEUS mission (X-ray Evolving-Universe Spectroscopy Mission) is a future ESA project currently under study. With a mirror collecting area of up to 30 m<sup>2</sup> @ 1 keV and 3 m<sup>2</sup> @ 8 keV it will outperform the x-ray space observatories like XMM-Newton. In fact it will have a source flux sensitivity and angular resolution respectively 250 times and 7.5 times better if compared to that mission. This huge collecting area is obtained with a 10 m diameter telescope of 50 m focal length. It is foreseen that the whole telescope will be formed by two free flying satellites, one for the mirror assembly and the other for the detectors. The two satellites will be kept aligned by an active tracking/orbit control system. The angular resolution of the optics is set to 5 arcsec with a goal of 2 arcsec. Of course the requirement of high resolution and large diameter of the optics create new technological problems which have to be overcome. First of all the impossibility to create closed Wolter I shells (due to the large diameter) means that the optics will be assembled using rectangular segments of ~1 m x ~0.5 m size. A set of these segments will form a petal. The petals will be assembled to form the whole mirror assembly. Another difficulty arises from the fact that the current design foresees a mass/geometric-area ratio of 0.08 kg/cm<sup>2</sup>, which is very small and much lower compared with XMM-Newton. Hence the use of materials that can offer both low weight and high stiffness is mandatory. The impossibility to have a thermal control for the huge area of the optics means also that the mirrors have to operate at temperatures between -30 and -40°C. This requirement excludes the epoxy-replication method as option for their manufacturing (CTE mismatch between resin and substrate). Considering all these constrains a possible solution for the realization of the XEUS mirrors has been found that foresees the use of glass or ceramics materials. In this paper we will describe an investigation currently on-going aimed at the development of a procedure to produce large mirror segments from thin Borofloat glass and the preliminary results obtained, that corroborate the viability of the proposed approach. A previous article has introduced the basic ideas and concepts behind this investigation.
The Max-Planck-Institut fuer extraterrestrische Physik (MPE), the Astrophysikalisches Institut Potsdam (AIP) and the Institute fuer Astronomie und Astrophysik der Universitat Tubingen (IAAT), together with European cooperation partners, have proposed to install an x-ray telescope on the International Space Station (ISS). The mission ROSITA will perform the first imaging all-sky survey in the medium energy x-ray range up to 10 keV with an unprecedented spectral and angular resolution. The main scientific goals are (1) to detect systematically all obscured accreting Black Holes in nearby galaxies and many new, distant active galactic nuclei, (2) to detect the hot intergalactic medium of several ten thousand galaxy clusters and groups and hot gas in filaments between clusters to map out the large scale structure in the Universe and to find in particular the rare massive distant clusters of galaxies for the study of cosmic structure evolution and (3) to study in detail the physics of galactic x-ray source populations, like pre-main sequence stars, supernova remnants, and x-ray binaries. In the hard x-ray band the ROSITA survey in this band, which was performed about 25 years ago. In the soft band the ROSITA survey will have a hundred times higher sensitivity and a hundred times better angular resolution than the last all-sky in this band, which was perforemd about 25 years ago. In the soft band the ROSITA survey will be more sensitive and have a substantially better energy and also angular resolution than the ROSAT all-sky survey. The telescope will consist of the seven 27-fold nested Wolter-1 mirror systems, the type already flown on ABRIXAS, and an ovel detector system currently being develoepd by MPE on the basis of the successful XMM pn-CCD technoloyg - a potential prototype for the planned ESA mission XEUS. Major improvements of the new camera are a higher time and energy resolution and significantly reduced ghost images. Within an industry study, recently completed, the general feasibility of such an astronomical survey telescope mounted on the ISS was established.
The main scientific objective of the ROSITA mission is to extend the X-ray all-sky survey of ROSAT to higher energies to gain an unbiased sample of all types of celestial X-ray sources in the medium energy band. During this mission the whole sky will be scanned by seven imaging X-ray telescopes. The telescopes have different viewing directions with an offset angle between 4 and 6 deg. The focal plane instrumentation of the telescopes is based on a novel type of pn-CCD with a frame store, an advanced version of the pn-CC operating quite successfully on XMM-Newton. The pixel size is adapted to the
mirror resolution and the fast readout time guaranties the required angular accuracy despite the scan motion. The X-ray camera carries seven separate CCDs arranged on a circle in the foci of the Wolter type I mirror systems of the seven telescopes. The CCDs are mounted on ceramic frames, which carry dedicated front-end electronics for each CCD. The CCDs are operated at a temperature of-80 deg C. Except for the entrance window, the CCDs are covered by graded shielding for suppression of fluorescent X-ray background, generated by cosmic rays in the surrounding materials. Filters in front of the the CCDs, inhibit optical and UV photons. For in-orbit calibration a radioactive
source producing fluorescent X-rays in the desired energy band is provided. We will give an overview of the mechanical, thermal and electrical concept of the camera system.
Active Pixel Sensors (APS) offer high-resolution imaging in combination with a fast and flexible readout. The MPI Halbleiterlabor develops and produces DEPFET (Depleted Field Effect Transistor) based APS devices. They are additionally characterized by enhanced sensitivity for X-ray photons in the range from 0.1 keV to 25 keV, spectroscopic energy resolution (below 1 electron r.m.s.) and radiation hardness. Moreover, the production process on high-ohmic silicon allows incorporating additional high-speed spectrometers based on silicon drift detectors. Such a detector system is proposed as a wide field imager for the XEUS (X-ray Evolving Universe Spectroscopy) mission. XEUS is a planned project within the European Space Agency's Horizon 2000+ program. We will present a focal plane concept for XEUS and measurement results from DEPFET-APS prototypes and high speed drift detectors.
The pn-CCD was developed as focal plane detector for the XMM-Newton mission and operates successfully for more than 30 months in orbit without performance degradation. In order to match the new requirements of the future ROSITA mission which will perform a broad band X-ray all-sky survey, we propose an advanced type of pn-CCD. The concept and the new features of this frame store pn-CCD as part of the imaging X-ray spectrometer of ROSITA are described. First
measurements with prototype devices show the improvement of detector performance in comparison to the pn-CCD on XMM-Newton. We suggest as optical filter for the observations of the X-ray sky, a thin aluminum layer deposited on the photon entrance window of the device.
The pn-CCD camera on EPIC-XMM is the most advanced imaging X-ray spectrometer, as it combines high quantum efficiency, high speed readout and high energy resolution. The camera operates for almost two years as calibrated prior to launch. Future missions, like ESA's XEUS (X-ray Evolving Universe Spectroscopy) mission require higher spatial resolution, higher response at energies above 20 keV and most important a full frame readout rate increased by at least a factor of 20 for the first operational phase. XEUS represents a potential follow-on mission to the cornerstone XMM-Newton, currently in orbit. The XEUS mission is considered as part of ESA's Horizon 2000<SUP>+</SUP> program within the context of the International Space Station (ISS.) In order to match the above requirements for the wide field imager of XEUS, we propose a frame store pn-CCD camera system based on the technology development of the EPIC (European Photon Imaging Camera) camera on XMM-Newton. Our goal is readout rate of 250 complete frames per second for 1024 x 1024 pixels with a pixel size of 75x75micrometers <SUP>2</SUP>, monolithically integrated on a 6 inch wafer. The concept and the new features of the frame store pn-CCD camera will be described. The focal plane layout, the readout concept and the expected scientific performance will be introduced. The implementation of thin aluminum filters, monolithically grown on the pn-CCD entrance window, will be discussed as well as the integration of a very fast spectroscopic detector being able to record 10<SUP>6</SUP> counts per second with a FWHM of about 250 eV.
Based on the operational experience with the EPIC pn-CCD system on board of XMM-Newton, new imaging X-ray spectroscopic detector systems for future X-ray missions will be introduced in terms of energy, position and time resolving detectors. As the readout speed requirement in the case of single photon coating detectors increases drastically with the collecting area and improved angular resolution, but noise figures have to be on the lowest possible level, new detector schemes must be developed: Active pixel sensors (APS) for X-ray detection have the capability to randomly select areas of interest and to operate at noise levels below 1 electron (rms). About 1000 frames per second can be read out with a relatively low level of electric power with the proposed DEPFET arrays. One prominent candidate for the use of an APS is ESA's XEUS 0 the X-ray Evolving Universe Spectroscopy mission. It represents a potential follow-on mission to the cornerstone XMM-Newton, currently in orbit. The XEUS mission is considered as part of ESA's Horizon 2000<SUP>+</SUP> program within the context of the International Space Station (ISS).
XEUS: The X-ray Evolving Universe Spectroscopy mission represents a potential follow-on mission to the ESA XMM cornerstone currently nearing completion. XEUS represents the next logical step forward in x-ray astrophysics after the current set of mission have been launched and completed their operational lives. The development and ultimate success relies heavily on the capability of the International Space Station (ISS). In this paper we describe the key characteristics of the mission including the requirements placed specifically on the ISS and discuss the significant advances in high energy astrophysics expected from such an observatory.
ABRIXAS is a German satellite project - to be launched in spring 1999 - which will perform the first imaging x-ray all-sky survey in the 0.5-10 keV band thus being a complement to the ROSAT all-sky which covered the 0.1-2.4 keV range. Its telescope consists of seven mirrors modules, each with a diameter of 16 cm and a focal length of 160 cm. the mirror modules are tested and calibrated at the MPE X- ray test facility PANTER. Several mirrors from the qualification program and one flight module have been tested and calibrated up to now. The imaging performance of the optics was successively improved until the flight module reached an on-axis resolution of 22 arcseconds. The total scattering level at 8 keV is about 16 percent for two reflections which indicates a microroughness of less than 0.5 nm. The measured on-axis effective area of one flight mirror module is 81 cm<SUP>2</SUP> at 1.5 keV and 25 cm<SUP>2</SUP> at 8 keV. These values indicate that the reflectivities of the mirror surface are on the average about 92 percent of the theoretical expectation.
The microchannel plate-based High Resolution Imager (HRI) is one of the focal plane instruments of the Rosat X-ray telescope that was launched on 1 June 1990. The calibration of the HRI is reported and preliminary results from the in-orbit calibration are presented. The quantum efficiency of the detector has been determined as a function of energy, the spatial variation of quantum efficiency, geometric nonlinearities, background, imaging performance, and UV sensitivity. Results of periodic tests of the temporal stability of the instrument are also reported.