Data Acquisition System of the TPC/MPD Detector for the NICA Project

Abstract

The data acquisition system (DAQ) was designed for data taking from the TPC/MPD detector. The detector contains 95232 registration channels, includes 1488 Front-End Cards (FEC) and other modules grouped into 24 DAQ subsystems. Each FEC has an individual full-duplex few-gigabit communication channel with Readout and Control Unit (RCU). The RCU manages each FEC within the group, collects the data and then transmits them via a high-speed optical channel. Optical lines from each group of four RCUs are connected to the Local Data Concentrator (LDC) computer via a Data Concentrator Unit (DCU) module installed. Each of the six DCUs controls four RCUs, receives data from them and stores them into the LDC computer memory via the PCIe interface. The DAQ system is operating with a raw TPC event of the size up to 37 MB containing information up to 2000 tracks at the central collision and the event trigger rate of up to 7 kHz in zero suppression mode. The article presents the overall structure of the system and the realized functionality of its main components. Section 1 describes the arrangement of DAQ subsystems and modules inside MPD. Section 2 gives the function, structure and connections of DAQ subsystems. Section 3 describes in detail one of the 24 DAQ subsystems. Section 4 presents the scheme of the local storage of TPC data and communication with MPD DAQ. In Section 5, the system throughput is estimated. Section 6 summarizes the main performance indicators and key technologies used in the construction of the system.