RAMSES stands guard over the accelerator chain

RAMSES, the system that is used to monitor radiation at the LHC, CNGS, CTF3 and n-TOF facilities, will soon be installed at strategic points in the accelerator chain, replacing the older monitoring system ARCON. The replacement programme has already begun.


RAMSES (which stands for “Radiation Monitoring System for the Environment and Safety”) is designed to protect workers, the general public and the environment, both on the Organization’s site and in the surrounding areas.

It is currently operational on all the LHC sites and at CTF3, CNGS and n-TOF, while the remaining sites are still equipped with the ARCON (Area CONtroller) system. Daniel Perrin, head of the Instrumentation and Logistics Section of the HSE Unit's Radiation Protection Group, explains: “ARCON was designed for the old LEP accelerator and dates back to the early 1980s, while RAMSES is a much more recent design intended specifically for the LHC. With 389 detectors distributed across 124 measuring points, it provides constant, reliable monitoring."

RAMSES is an exacting monitoring system, and among the largest currently in use at a research centre. Its reliability is crucial for accelerator operations, as Daniel Perrin explains: "A malfunction in the radiation monitoring system can bring the entire accelerator complex to a standstill". The data measured by RAMSES is continuously collected and transferred to a database for immediate distribution and long-term archiving. In zones that can be accessed during LHC operation, some detectors are connected directly to local alarms, which are triggered as soon as the radiation level exceeds a given threshold. These alarms are immediately relayed to the various control rooms and, of course, logged in the database.
"All the measurements are recorded, so we can mine the database and perform real-time monitoring or historical analysis for all the detectors,” says Perrin.

For the machines and experiment areas other than the LHC, CNGS and CTF3, radiation monitoring continues to be provided by ARCON. “As far as the detectors are concerned, there is not much difference between the two systems: both are very capable,” notes Perrin. "The biggest difference between the old and the new systems lies in the actual design of the detection network. The connectivity and exploitation of the data supplied by the detectors is much more efficient in RAMSES, providing better intrinsic security, which is why we are phasing out ARCON."

RAMSES is based on a set of independent monitoring units that directly manage the information supplied by the detectors. "The architecture and design of RAMSES offer the necessary flexibility and scalability allowing the system to be integrated into the existing accelerators as well as CERN's future projects", adds Daniel Perrin.

In close collaboration with their colleagues working on operational radiation protection, public safety and environmental protection, Daniel Perrin’s team has already identified 50 priority sites where the old ARCON instrumentation will be replaced or supplemented with newer RAMSES hardware this year. Replacement of the remaining instrumentation and the final phase-out of ARCON in favour of RAMSES will essentially be done during the long technical shutdown of the LHC scheduled for 2012.

For further information about this topic, visit the Environment website.




by CERN Bulletin