Demonstrator of a combined read-out system of highly granular electromagnetic and hadronic calorimeters.

Highly granular calorimeters at future e+e− colliders will feature up to 100M cells, requiring embedded very-front-end and readout electronics, in the form of dedicated ASICs. Even if the ASICs can handle 𝒪(64) readout channels, millions of them must be properly configured, synchronised, readout and monitored, by the acquisition system (DAQ). This is only possible by a high level of multiplexing. On the other hand, the DAQ must be compact not to compromise the precision of the measurements, and have a limited heat dissipation.
We present the state of the art of compact readout cards, handling up to 10,000 cells, that are connected to data concentrator units implementing already the necessary features for full-detector systems. A calorimetric system consists typically of an electromagnetic section and a hadronic section. These have to be integrated into a common readout system. 
This document reports on the setup and results of a common system of an electromagnetic and a hadronic calorimeter that has been tested recently in large-scale beam tests at CERN and DESY. The compact readout system developed for a silicon tungsten electromagnetic calorimeter (SiW-ECAL) has been part of the common data acquisition system. 
Further, possible spin-offs, the application in the LUXE and EBES experiment are sketched at the end of this report.