Designing large pixelated CdTe detection planes for hard X-ray transients detection

In this paper, we discuss the need for very large detection planes for the detection of hard X-ray transients in the multi-messenger era, started with the quasi-simultaneous detection of GRB 170817A by Fermi /GBM and INTEGRAL /SPI and the gravitational waves event GW 170817, detected by the LVC collaboration. After pointing that current and future instruments gain in the number of GRBs thanks to their larger field of view rather than to their larger effective area, we address various problems associated with the realization of very large detection planes (≥ 1m 2 ). Based on our experience with SVOM /ECLAIRs, we demonstrate that CdTe detectors are well suited for this task. We conclude with a discussion of some key parameters that must be taken into account in the realization of instruments based on these detectors. We hope that this paper will contribute to promote the construction of large area wide-field hard X-ray monitors that will be crucially needed in the next decade.