The OPERA Spectrometer Slow Control System

Abstract

OPERA is a long-baseline neutrino experiment at the Gran Sasso underground laboratories (LNGS), to observe appearance in a neutrino beam produced at CERN. The detector is a structure of two super modules, each built-up of a massive lead/nuclear-emulsion target complemented by electronic detectors and a magnetic spectrometer. The two magnets are instrumented by 1000 Resistive Plate Chambers (RPCs) detectors for a total surface of about 3200 m 2 . The slow control system has been designed to monitor and control all the critical parameters for the proper functioning of the spectrometers. The different hardware (Magnet and RPC High Voltage power supplies, RPC current meters, Magnet and RPC temperature sensors, RPC timing boards) is read out via CAN bus connections by several distributed clients. The clients write the data to a relational database (PostgresSQL) which is the heart of the system: it gives persistence to the data and allows to perform correlations useful to debug possible system malfunctioning. Among the various tools (histograms and XML Configuration Managers), a controller process checks for possible failures of the system using data from the database and generates warnings/alarms for people on shift.

The OPERA RPCs front end electronics; a novel application of LVDS line receiver as low cost discriminator

“…6 Results from the OPERA experiment About 450 FEBs are required to read out the whole spectrometer. They are arranged into 26 crates, each one powered by a Compact-PCI switching power supply, remotely controlled and monitored through a CAN bus [13]. The choice of the power supply type (switching versus linear) was carefully pondered for a long time, as in a well-controlled environment the noise contribution of the switching power supply was demonstrated to be negligible, but there was also awareness, and a big fear, that in the experiment the behaviour might be very different.…”

Prospect for Charge Current Neutrino Interactions Measurements at the CERN-PS

“…According to the experience acquired for the OPERA experiment [46] the system is organized in tasks and data structures developed to acquire in short time the status of the detector parameters which are important for a safe and optimal detector running.…”

The slow control system of the GERDA double beta decay experiment at Gran Sasso

“…The main ingredients are: simple and standardized communication protocols between the different components, a modular structure of the applications and maximum use of open source software. Finally, the experience acquired during the development of the OPERA slow control system [4] has been an important key in the design of the whole system.…”