Dedicated readout electronics and data preprocessing for a granular electromagnetic calorimeter

A dedicated readout electronics and Data Acquisition (DAQ) system has been designed for the testbeam of the ECALp compact electromagnetic calorimeter prototype. The readout is comprised of a System on Chip (SoC) Application-Specific Integrated Circuit (ASIC), called FLAME, a dedicated DAQ system based on Field Programmable Gate Arrays (FPGAs), and software working within the EUDAQ environment, extended by the web-based online control and monitoring. The FLAME ASIC is equipped with 32 analogue channels with a Charge Sensitive Preamplifier (CSA) and a CR-RC shaper, followed by a 10-bit Analog-to-Digital Converter (ADC) in each channel. The ASIC works as a waveform digitizer, streaming out all samples taken by the ADCs at a 20 MSps sampling rate, resulting in two 5.2 Gbps serial data links per each ASIC. The readout is supplemented by a DAQ system based on a multiple FPGAs array to manage nearly 1 Tbsp of the incoming data stream from the readout electronics. Apart from acquiring the data, the FPGAs perform also real-time signal processing with shaper pulse amplitude reconstruction, which enables the backend software to construct and present physics plots, allowing for online data quality assurance during the testbeam. The design of the ASIC and architecture of firmware and software DAQ components are presented and discussed.