Rule-Based Monitoring of Trigger-Rates at ZEUS

Paper: 338
Session: B (talk)
Speaker: Behrens, Ulf, DESY, Hamburg
Keywords: diagnosis, monitoring systems, object-oriented methods, programming languages, expert systems

Rule-Based Monitoring of Trigger-Rates at ZEUS

Ulf Behrens (+), Mariusz Flasinski (*), Lars Hagge (+), Janusz Jurek
Dirk Kahnert (+), Kars Ohrenberg (+), Pjotr Wojtowicz (*)

(+) Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany
(*) Dept. Computer Science, Jagiellonan University, Cracow, Poland

A tool for monitoring and surveilling the first-level trigger rates of
ZEUS experiment has been developed using a rule-based approach.
gained from running the experiment has been used to identify nominal,
luminosity dependend values and spreads for the individual trigger rates.
Current trigger rates are monitored and forwarded to a (rule-based)
engine, which issues warnings or alarms whenever individual triggers are
deviating too much and/or too long from their nominal values.

Trigger rates have been modeled using Harel state machines, which have
been turned into rules. Compared to conventional programming techniques,
have the advantage that they don't introduce an order (ie sequence) to
program. The system was implemented within two months using a commercial
expert system shell. Data transport to/from the inference engine is
in C++. The system was introduced into the ZEUS environment towards the
end of
the 1996 running period.

The tool is a helpful support for the shift crew running the experiment.
talk will discuss the tool's architecture, the rule-based paradigm and
technique of deriving rules, and some running experience. Using
programming has shown to be an easy and efficient way to create simple
helpful tools like this. It is a thing to look at, even more as rule
for C++ are appearing on the market.