We present ECLAIRs, the Gamma-ray burst (GRB) trigger camera to fly on-board the Chinese-French mission SVOM. ECLAIRs is a wide-field (~ 2 sr) coded mask camera with a mask transparency of 40% and a 1024 cm<sup>2</sup> 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 ~ 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 × 4 mm<sup>2</sup> and 1
mm-thick Schottky CdTe detectors. The detectors are grouped by 32, in 8×4 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°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.
ECLAIRs is an X and gamma-rays wide-field coded mask camera onboard the Chinese-French
mission SVOM (Space-based multi-wavelength Variable Objects Monitor) that is dedicated to
study Gamma-ray bursts (GRBs). SVOM is due to be launched in 2015 in a low Earth orbit (630
km circular orbit with 30° inclination) for a three years duration. SVOM is designed to operate
"a la SWIFT" in order to provide fast and accurate GRB positions to ground-based and space
facilities, thanks to the combined use of ECLAIRs and 2 narrow-field instruments covering the Xrays
and the optical.
Within this strategy, ECLAIRs will play a key role since it is the instrument responsible for the
detection and the first localization of GRBs in near real time.
One of the primary goals of the mission is to study high redshift (z>6) GRBs that may appear as
very soft events in Gamma-rays. For this reason, ECLAIRs is designed to have an increased
sensitivity in the X-rays, when compared to previous equivalent instruments, thanks to a low
energy threshold of 4 keV.
In this talk we present the latest developments of the ECLAIRs design along with the expected
The X- and gamma-ray telescope ECLAIRs onboard the future mission for gamma-ray burst studies
SVOM (Space-based multi-band astronomical Variable Objects Monitor) is foreseen to operate in
orbit from 2014 on. ECLAIRs will provide fast and accurate GRB triggers to other onboard telescopes,
as well as to the whole GRB community, in particular ground-based follow-up telescopes. With its
very low energy threshold ECLAIRs is particularly well suited for the detection of highly redshifted
GRB. ECLAIRs consists of a X- and gamma-ray imaging camera (CXG) observing in a field of view
of 2 sr. The CXG is a 2D-coded mask imager with a 1024 cm<sup>2</sup> detection plane made of 80 x 80 CdTe
pixels, sensitive from 4 keV to 250 keV, with imaging capabilities up to about 50 keV and a
localization accuracy better than 10 arcmin.
ECLAIRs includes also a triggering electronics which uses the CXG data and detects GRB as countrate
increases or the appearance of a new source in cyclic sky images. GRB alerts are transmitted to
observers within tens of seconds via a VHF network and all detected photons are available hours later.
In this talk we present the lastest ECLAIRs concepts, with emphasis on the expected performances.