Geneva, Switzerland

CERN, the European Organization for Nuclear Research, is one of the world's largest and most respected centers for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world's largest and most complex scientific instruments are used to study the basic constituents of matter - the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.
The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.
Founded in 1954, the CERN Laboratory sits astride the Franco-Swiss border near Geneva. It was one of Europe's first joint ventures and now has 20 Member States.

RAMSES - RAdiation Monitoring System for the Environment and Safety

RAMSES will provide LHC1, the most recent CERN accelerator commissioned in 2008, with an integrated radiation monitoring system covering acquisition, transmission, logging and display of radiological parameters for the LHC accelerator and experiments. RAMSES shall be extended in the near future to cover all CERN accelerator installations. The CERN Safety Commission will exploit this system to assess radiation risks and to control the release of radioactivity.

RAMSES makes use of different types of detectors and monitoring stations. A large number of over 160 PTW ionization chambers type 32006 of three liters sensitive volume each are integrated and installed inside the LHC accelerator tunnel and LHC experiments. They measure the ambient dose equivalent rate originating from the induced radioactivity produced by lost high energy particles. To evaluate the radiological risk to intervening personnel, the ambient dose equivalent rate is measured by the ion chambers and can be read out in real time at distance by a supervision system. The instantaneous dose rate value and the evolution of the dose rate over time, due to the radioactive decay of the induced isotopes, are used in the optimization and planning process for radiation protection.

The PTW chambers were chosen due to their proven radiation hardness required to stand the operation periods in high dose radiation fields. The operation principle of ionization chambers guarantees reliable and stable measurement results over long periods.  CERN already had good experience with a large number of over 120 PTW ionization chambers of a similar type, which are in use since more than two decades at CERN accelerator installations, such as PS (Proton Synchrotron), SPS (Super Proton Synchrotron), AD (Antiproton Decelerator), ISOLDE facility (On-Line Isotope Mass Separator) and others.

1Large Hadron Collider

See also:


Daniel Perrin (
Markus Widorski-Rettig (

CERN, European Organization for Nuclear Research
SC/RP, Safety Commission/Radiation Protection 

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