The X-/Gamma-ray camera ECLAIRs for the Gammay-ray burst mission SVOM

TL;DR

ECLAIRs is a wide-field coded mask gamma-ray camera designed for the SVOM mission, optimized for detecting high-redshift and low-luminosity GRBs with a low-energy threshold of 4 keV, aiming to detect around 200 GRBs over three years.

Contribution

This paper details the design, optimization, and testing of ECLAIRs, including its detector modules and electronics, to enhance gamma-ray burst detection capabilities in space.

Findings

ECLAIRs is expected to detect approximately 200 GRBs during its mission.

The detector modules and electronics have been tested for performance and operability.

The instrument's design optimizes sensitivity to high-redshift and low-luminosity GRBs.

Abstract

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.