Detector control system (DCS)
The NA61/SHINE Detector Control System (DCS) is responsible for online monitoring and controlling of the working conditions of the detectors. The system monitors parameters of the gas mixture in the TPCs (temperatures, pressure, ﬂow, water and oxygen content, drift velocity, ampliﬁcation, etc.). It also sets and monitors parameters of the high voltage in the sub-detectors: LMPD, TPCs, BPDs and the beam counters. The system also controls low voltage power supplies of the front-end electronics and enables its cooling.
Although the system logically consists of the following subsystems:
- Gas subsystem,
- High Voltage subsystem,
- Low Voltage subsystem,
- PSD subsystem,
the main part of the system is a single EPICS-based measurement server distributed over a few PCs. It communicates with various hardware (CAMAC, VME, PLC, etc.) via various interfaces (RS232, Caenet, TCP/IP, GPIB, etc.), performs all the measurements and makes the results accessible for the clients via the Channel Access protocol. The server runs constantly regardless of the presence of the clients or the database availability. All measured data is stored in the relational database (PostgreSQL) by one of the EPICS clients. It can be accessed only via the Database Access Server by issuing ASCII commands. There are two GUIs available. One of them, which controls the Measurement Server and monitors its performance, is an EPICS client and can be run only in the experimental area. The other one can be run anywhere and is graphically presenting results of measurements retrieved from the database.