HiRadMat: materials under scrutiny

CERN's new facility, HiRadMat (High Radiation to Materials), which is designed to test materials for the world's future particle accelerators, should be operational and welcoming its first experiments by the end of the year.


The HiRadMat facility, located in the TNC tunnel.

The materials used in the LHC and its experiments are exposed to very high-energy particles. The LHC machine experts obviously didn't wait for the first collisions in the world's most powerful accelerator to put the materials through their paces - the equipment was validated following a series of stringent tests. And these tests will get even tougher now, with the arrival of HiRadMat.

The tunnel that formerly housed the West Area Neutrino Facility (WANF) has been completely revamped to make way for CERN's latest facility, HiRadMat. Supported by the Radioprotection service, a team from the Engineering (EN) Department handled the dismantling operations from October 2009 to December 2010. "We could only work on dismantling the old WANF machinery at an average rate of one week in six (following the LHC schedule)," explains HiRadMat Deputy Project Leader, Sébastien Evrard. "The radioactive materials were processed, stored and, where possible, reused for HiRadMat, in strict compliance with radiation protection rules." This was the first dismantling operation on such a large scale since the dismantling of LEP, and the extraction of certain items from the WANF took a great deal of organising, using automatic hook devices and video cameras to allow the operators to keep their distance from the radioactive components. This part of the work went off very well, giving EN Department engineers solid experience in remote handling techniques. As Sébastien underlines, "this will stand us in good stead for future dismantling jobs."

If all goes well, and thanks to the sustained efforts of many groups at CERN, operations at HiRadMat should start by the end of the year. "I'd be really pleased if we could start HiRadMat experiments in October. The first project should be the testing of a collimator for the LHC," observes the EN Department's Ilias Efthymiopoulos, who is leading the HiRadMat project. In the HiRadMat hall, beams from the SPS are directed onto the elements to be tested. This enables researchers to test collimators, beam windows and various materials before installation in the accelerators. Because, as Ilias notes: "accelerators are not ideal places to test new equipment."

It would have been unthinkable to wait until the first collision had occurred in the LHC before realising that this or that new part couldn't withstand the impact of a beam or came out severely damaged. That's why it is so vital to "bombard" samples with high energy and answer the following kinds of questions - is the material destroyed? Is it deformed? In what way? Have its mechanical properties been modified? The resulting data will tell engineers much about the resistance of the materials and provide valuable new information that can be fed back into simulations. Ilias adds: "Up until now, people did calculations to evaluate the quality of materials but had no real data to constrain their models. Thanks to HiRadMat, progress can now be made in theoretical areas too."

On top of its innovative characteristics, HiRadMat is also very adaptable: researchers can fine-tune the diameter of the beam which is "shot" at the samples and thereby alter its energy density (the finer the beam, the greater the energy delivered per cm3) and thus get closer to "real" conditions in the accelerator. In this way, items destined for the LHC can be tested somewhere other than in the LHC.

HiRadMat is supported by the European Commission via the EuCARD project (European Coordination for Accelerator Research and Development) of the 7th Framework Programme and includes several European partners. "Like all CERN's facilities, HiRadMat will be open to scientists from CERN's Member States and countries across the world. Anyone wishing to use the SPS beams to test their samples will have to request permission from the members of the HiRadMat committee, who will evaluate the suitability of proposals and draw up an annual schedule." With physicists busy designing the future generation of particle accelerators, a facility like HiRadMat seems more indispensable than ever.

by Anaïs Schaeffer