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The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a Chinese – French satellite mission due to be launched in the summer of 2022. It is composed of four instruments: ECLAIRs, for detecting X-ray and gamma-ray transients (4-250 keV); GRM, a gamma-ray spectrometer (15 keV-5 MeV); VT, a visible telescope and the Microchannel X-ray Telescope (MXT). The MXT’s main goal is to precisely localize, and spectrally characterize X-ray afterglows of Gamma-Ray Bursts. The MXT is a narrow-field-optimised lobster eye X-ray focusing telescope comprising an array of 25 square Micro Pore Optics (MPOs), with a detectorlimited field of view of ∼1 square degree, working in the energy band 0.2-10 keV. The SVOM qualification model (QM) MXT optic (MOP) was designed and built at the University of Leicester, and is the first complete, lobster eye optic to be X-ray tested. We present results from the PANTER facility (MPE), where a full calibration of the QM MOP was carried out. The response of the optic was studied at seven energies from C-K to Cu-K, and the effective area at multiple off-axis angles at each energy was measured. The focal length of the MOP was confirmed and the PSF was studied on and off-axis. In addition, we present details of the modelling and analysis, which was used to calculate the results from the test campaign. The effective area and PSF are in good agreement with the modelling, indicating that the optic is performing as expected.

The Microchannel X-ray Telescope (MXT) is a soft X-rays instrument on board SVOM, a Sino French mission. The launch is planned in 2021 by a LM-2C rocket. The main SVOM general objective is the survey of Gamma Ray Bursts, in coordination with ground telescopes. The other main on board instruments are ECLAIR (gamma, french), GRM (gamma, Chinese) and VT (visible, chinese).

This research used the SPECTRE High Performance Computing Facility at the University of Leicester.

ECLAIRs, a 2D coded-mask imaging telescope on the Sino-French SVOM space mission, will detect and locate gamma-ray bursts (GRBs) between 4 and 150 keV. The detector array is an assembly of 6400 Schottky CdTe detectors of size 4×4×1 mm3, biased from −100 V to −600 V and operated at −20 °C to minimize the leakage current and maximize the polarization time. The remarkable low-energy threshold is achieved through various steps: an extensive detectors selection, a low-noise 32 channels ASIC study, and the design of an innovative detection module called XRDPIX formed by a thick film ceramic holding 32 detectors, a high voltage grid and an HTCC substrate housing the ASIC within a hermetic cavity. In this paper, we describe the XRDPIX module and explain the results of first tests to measure the linearity and compare the sources of noise, such as leakage currents and the Equivalent Noise Charge (ENC) measured on ASIC Ceramics. We confront these values with the energy threshold and spectral resolution made with dedicated test benches. Finally, we present the superposition of 32 calibrated spectra of one XRDPIX module, showing the excellent homogeneity of the 32 detectors and the achievement of a detection threshold at 4 keV over the entire module.

ECLAIRs, a 2-D coded-mask imaging camera on-board the Sino-French SVOM space missi on, will detect and locate gamma-ray bursts in near real time in the 4 - 150 keV energy band in a large field of view. The design of ECLAIRs has been driven by the objective to reach an unprecedented low-energy threshold of 4 keV. The detection plane is an assembly of 6400 Schottky CdTe detectors of size 4x4x1 mm 3 , biased from -200V to -500V and operated at -20°C. The low-energy threshold is achieved thanks to an innovative hybrid module composed of a thick film ceramic holding 32 CdTe detectors ("Detectors Ceramics"), associated to an HTCC ceramic housing a low-noise 32-channel ASIC ("ASIC Ceramics"). We manage the coupling between Detectors Ceramics and ASIC Ceramics in order to achieve the best performance and ensure the unifor mity of the detection plane. In this paper, we describe the complete hybrid XRDPIX, of which 50 flight models have been manufactured by the SAGEM company. Afterwards, we show test results obtained on Detectors Ceramics, on ASIC Ceramics and on the modules once assembled. Then, we compare and confront detectors leakage currents and ASIC ENC with the energy threshold values and FWHM measured on XRDPIX modules at the temperature of -20°C by using a calibrated radioactive source of 241Am. Finally, we study the homogeneity of the spectral properties of the 32-detector hybrid matrices and we conclude on general performance of more than 1000 detection channels which may reach the low-energy threshold of 4 keV required for the future ECLAIRs space camera.

We present the Micro-channel X-ray Telescope (MXT), a new narrow-field (about 1{\deg}) telescope that will be flying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science, scheduled for launch in 2021. MXT is based on square micro pore optics (MPOs), coupled with a low noise CCD. The optics are based on a "Lobster Eye" design, while the CCD is a focal plane detector similar to the type developed for the seven eROSITA telescopes. MXT is a compact and light (, Comment: 6 pages, 6 figures, proceedings of the conference "Swift: 10 years of Discovery", Rome, December 2-5, 2014. To be published by PoS

Ohmic CdZnTe and CdTe detectors have been successfully used in high-energy missions such as IBIS on-board INTEGRAL and the Swift-BAT in the past two decades. Such detectors provide very good quantum efficiency in the hard X-ray band. For the future generation of hard X-ray coded mask detectors, a higher sensitivity will be required. A way to achieve this is to increase the effective area of the pixilated detection plane, to change the mask pattern and/or the properties of the semi-conductors paving the detection plane. For the future Chinese-French Gamma-ray burst mission SVOM, the GRB trigger camera ECLAIRs will make use of a new type of high-energy detectors, the Schottky CdTe detectors. Such detectors, when reversely biased, are known to present very low leakage current, resulting in lower values of the low-energy threshold (down to 4 keV or less) than for previous missions (i.e. > 10 keV for the Swift-BAT and INTEGRAL/IBIS). Such low values will enable ECLAIRs with a moderate geometrical area of 1024 cm2 and a low-energy threshold of 4 keV to be more sensitive to high-redshift GRBs (emitting mainly in X-rays) than the Swift-BAT with a higher effective area and low-energy threshold. However, the spectral performance of such detectors are known to degrade over time, once polarized, due to the polarization effect that strongly depends on the temperature and the bias voltage applied to the detectors. In this paper, we present an intensive study of the properties of Schottky CdTe detectors as used on SVOM/ECLAIRs such as I-V characteristics, polarization effect, activation energy and low temperature annealing effects. We discuss the implications of these measurements on the use of this type of detectors in future high-energy instruments.

ECLAIRs, a 2-D coded-mask imaging camera on-board the Sino-French SVOM space mission, will detect and locate Gamma-ray bursts (GRBs) in near real time in the 4-150 keV energy band. The design of ECLAIRs has been mainly driven by the objective of achieving a low-energy threshold of 4 keV, unprecedented for this type of instrument. The detection plane is an assembly of 6400 Schottky CdTe semiconductor detectors of size 4x4x1 mm 3 organized on elementary hybrid matrices of 4x8 detectors. The detectors will be polarized from -300V to -500V and operated at -20°C to reduce both the leakage current and the polarization effect induced by the Schottky contact. The remarkable low-energy threshold homogeneity required for the detection plane has been achieved thanks to: i) an extensive characterization and selection of the detectors, ii) the development of a specific low-noise 32-channel ASIC, iii) the realization of an innovative hybrid module composed of a thick film ceramic (holding 32 CdTe detectors with their high voltage grid), associated to an HTCC ceramic (housing the ASIC chip within an hermetic enclosure). In this paper, we start describing a complete hybrid matrix, and then the manufacturing of a first set of 50 matrices (representing 1600 detectors, i.e. a quarter of ECLAIRs detector’s array). We show how this manufacturing allowed to validate the different technologies used for this hybridization, as well as the industrialization processes. During this phase, we systematically measured the leakage current on Detector Ceramics after an outgassing, and the Equivalent Noise Charge (ENC) for each of the 32 channels on ASIC Ceramics, in order to optimize the coupling of the two ceramics. Finally, we performed on each hybrid module, spectral measurements at -20°C in our vacuum chamber, using several calibrated radioactive sources ( 241 Am and 55 Fe), to check the performance homogeneity of the 50 modules. The results demonstrated that the 32-detector hybrid matrices presented homogeneous spectral properties and that a lowenergy threshold of 4 keV for each detector could be reached. In conclusion, our hybrid module has obtained the performance required at the SVOM mission level and successfully withstood the space environment tests (TRL 6/7). This development phase has given us the opportunity to build a detector’s array prototype (Engineering Model) equipped with 50 hybrid modules. Thanks to this prototype we are in the process of validating a complete detection chain (from the detectors to the backend electronics) and checking the performance. In addition it enables us to consolidate the instrument’s mechanical and thermal design, and to write preliminary versions of the quality procedures required for integration, functional tests and calibration steps. At the end of this prototype development and testing, we will be ready to start the detailed design of the detection plane Flight Model.

The Microchannel X-Ray Telescope will be implemented on board the SVOM space mission to observe the afterglow of gamma-ray bursts and localize them with 2 arcmin precision. The optical system is based on microchannel plates assembling in Wolter-I configuration to focus the X-rays in the focal plane, like done for the MIXS telescope of the BepiColombo ESA mission. The sensor part is a 256 × 256 pixel pnCCD from the Max-Planck Institute for Extraterrestrial Physics for high resolution spectroscopy and high quantum efficiency over 0.2 – 10 keV energy range, based on the same technology and design as the eROSITA telescopes for the Russian-German SRG mission. CEA-Irfu (Saclay) is in charge of the design and the realization of the camera, including the focal plane, the calibration wheel, the front-end electronics, the structure housing for background shielding and the active cooling system. A prototype of the full detection chain and the acquisition system was set up. The paper presents the preliminary design of the electrical, mechanical and thermal architectures of the camera. It focuses on the fabrication and testing of the critical elements of the design and concludes on the on-going developments.

The SVOM (Space-based multi-band astronomical Variable Objects Monitor) French-Chinese mission is dedicated to the detection, localization and study of Gamma Ray Bursts (GRBs) and other high-energy transient phenomena. We first present the major principles of the SVOM system including the alert system providing near-real-time GRB localizations to large ground-based telescopes. Then the paper describes the definition of the SVOM payload and more particularly the French payload composed of the ECLAIRs instrument, dedicated to GRB detection and positioning, and the MXT instrument, dedicated to GRB followup observation in soft X-ray band.

We present ECLAIRs, the Gamma-ray burst (GRB) trigger camera to fly on-board the Chinese-French mission SVOM. ECLAIRs is a wide-field ($\sim 2$\,sr) coded mask camera with a mask transparency of 40\% and a 1024 $\mathrm{cm}^2$ detection plane coupled to a data processing unit, so-called UGTS, which is in charge of locating GRBs in near real time thanks to image and rate triggers. We present the instrument science requirements and how the design of ECLAIRs has been optimized to increase its sensitivity to high-redshift GRBs and low-luminosity GRBs in the local Universe, by having a low-energy threshold of 4 keV. The total spectral coverage ranges from 4 to 150 keV. ECLAIRs is expected to detect $\sim 200$ GRBs of all types during the nominal 3 year mission lifetime. To reach a 4 keV low-energy threshold, the ECLAIRs detection plane is paved with 6400 $4\times 4~\mathrm{mm}^2$ and 1 mm-thick Schottky CdTe detectors. The detectors are grouped by 32, in 8x4 matrices read by a low-noise ASIC, forming elementary modules called XRDPIX. In this paper, we also present our current efforts to investigate the performance of these modules with their front-end electronics when illuminated by charged particles and/or photons using radioactive sources. All measurements are made in different instrument configurations in vacuum and with a nominal in-flight detector temperature of $-20^\circ$C. This work will enable us to choose the in-flight configuration that will make the best compromise between the science performance and the in-flight operability of ECLAIRs. We will show some highlights of this work., 15 pages, 12 figures, Proceeding SPIE - Montreal 2014

We present the Microchannel X-ray Telescope, a new light and compact focussing telescope that will be flying 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 cmsq, 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., Comment: 12 pages, 8 figures, to be published in SPIE Astronomical Telescopes + Instrumentation, Montreal, June 2014

In order to demonstrate the feasibility of a compact telescope with both wide field of view and high resolution, a demonstration model has been built and tested at CNES. This 1.08-m focal length, f/6 three-mirror anastigmat telescope has excellent image quality over its whole 8.4 ° × 1.4 ° field of view: modulation transfer function is about 0.54 @ 77 1p.mm −1 (detector Nyquist frequency). The focal plane comprises two channels, one panchromatic with 24 000 pixels and one multispectral with 12 000 pixels in each of its 3 spectral bands. The whole telescope (mirrors, structure, baffles and focal plane) weighs less than 45 kg. The conception has been done in order to favor structure simplicity and short alignment time while retaining high stability and good image quality. The first part of this paper will focus on the instrument design, and the second part on the manufacturing and test results.

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)

Radiation therapy accelerators require highly accurate dose deposition and the output must be monitored frequently and regularly. Ionization chambers are the primary tool for this control, but their size and fragility make them unsuitable for use during patient treatment. In collaboration with a French center for cancer treatment in Caen, we describe the development and testing of a low-cost radiotherapy dosimeter (SDM) based on scintillating fibers and signal processing to reduce the effect of Cerenkov radiation background. The employment of photodiodes for light collection reduces the cost relative to systems using photomultipliers (PMTs). However, we have also developed a highly sensitive system that uses PMTs for very low-dose deposition for Brachytherapy. Comparison with standard ionization chambers shows about a 1% difference over a range of 6- to 25-MV photons. This dosimeter is 1 mm in diameter and can be placed where ever required including inside the body. Its small size and flexibility make it useful for delimiting critical regions, where organs may be very radiation sensitive.

With the 3S program (the French acronym for SPOT System Follow-on), CNES intends to continue the SPOT Earth Observation mission with the purpose of achieving severe costs reduction. This increases the need for new, lighter, more compact technologies for the payload. Therefore, CNES has launched preliminary studies in some critical payload domains. The paper deals with the work done in order to demonstrate the feasibility of a small telescope that can be used onboard a mini-satellite. A Three-Mirror Anastigmat (TMA) telescope breadboard has been manufactured using the same technologies that would be required to provide in-orbit stability. The TMA has excellent image quality over its whole 8.4 X 1.4 degree FOV and an intrinsic compactness that makes it much smaller than its focal length: as a result, the whole telescope weighs about 40 kg. The paper particularly focuses on the telescope design, the alignment method and the optical performance under stable laboratory environment. The behavior of the telescope under space environment is described, as well as the tests conducted to validate the computed optical performance under thermal variations and vibrations conditions.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.