The digital data processing concepts of the large area detector and the wide field monitor onboard eXTP

Abstract

The enhanced x-ray timing and polarimetry (eXTP) mission is a large innovative observatory in the field of x-ray astronomy, designed to study the properties of matter under extreme conditions of density, gravity, and magnetic fields. It is developed by an international consortium led by the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) and is currently completing phase-B with a launch foreseen in 2027. Two of the four instruments onboard eXTP will be provided by a European consortium: the large area detector (LAD) and the wide field monitor (WFM). These two instruments use a high number of large area silicon drift detectors (SDDs) that are organized in 40 modules of 16 detectors each for the LAD and in six coded-aperture cameras with four detectors each for the WFM. The high multiplicity and modularity of this concept as well as the high data rates call for a novel, hierarchical data processing scheme. A similar concept is applied in the data acquisition and processing system of the LAD and the WFM. silicon drift detector and front end electronics using ASIC technology constitute the detector assembly. Data processing is performed in an FPGA-based digital circuit using only ITAR-free components in order to facilitate export to the launch site in China. The design of the digital electronics is not yet finally frozen, but the development and manufacturing of demonstrator models have been already completed. The FPGA firmware based on the pipeline data processing concept has been developed in VHDL. This concept allows real-time data processing capabilities and reduces dead time, thus improving the detection capacity for high flux sources.