International High-Energy Physics Technical Safety Forum

FPIAA : Finding Persons Inside ATLAS Areas A System for finding and rescuing persons in a very large Physics experiment Gianpaolo Benincasa, CERN-Geneva-Switzerland Carlos Cardeira, IDMEC/IST, Technical University of Lisbon-Portugal David Miguel Batista Claudino, IDMEC/IST, Tech. Univ. Lisbon-Portugal Amelia Maio, LIP-Lisbon-Portugal, CFNUL and FCUL ATLAS is a high energy particle detector of unprecedented size and complexity that is under construction at CERN, in the Geneva area. The detector is housed in a cavern of about 50000 mc at 100 m under ground. The principles of the detection used in ATLAS present a combination of multiple hazards: intense radiation fields, strong magnetic fields, toxic and explosive gases, cryogenic fluids( Argon, Nitrogen and Helium), laser beams etc… During the maintenance periods it is expected that up to 150 people could be present in the cavern at the same time, most of them working inside the intricacies of the detector and completely hidden and invisible from outside. In case of emergency, especially if smoke or fog (leaks of cryogenic fluids) are present, it could be extremely difficult and dangerously long for a rescue team to locate every person who could be in danger. Under these circumstances , a granular system for finding persons is then mandatory. The system must cope with the harsh environment and must be totally passive( no badges or other active equipment should be worn) to avoid voluntary or casual deactivation. FPIAA is based on a large number ( at the present about 400) of PIR( Passive InfraRed) sensors, each one detecting the presence of a person in a relatively small volume ( ~ 40 mc) and distributed to cover the most critical locations in the cavern. These sensors, and all the acquisition system, have been tested, modified and retested to cope with the intense radiation and magnetic fields of the environment. The information is collected by a computer systems and , after an appropriate treatment is sent to the Control Room where the operator can follow on a synoptic screen the movements of the persons in the cavern and inside ATLAS. The system will also give an alarm when a person disappears from a given volume, without re-appearing in one of the adjacent volumes( e.g. unconscious person). For this, a special software has been written that is susceptible to solve dubious cases, so reducing false alarms. A pilot project has already been implemented that has demonstrated the feasibility of the main features of the FPIAA system.