HiRadMat (High-Radiation to Materials) has been a key European facility for material testing for ten years now. It is designed to provide high-intensity, high-momentum pulsed beams to an irradiation area where accelerator components, high-power targets and various other material samples can be tested.

“HiRadMat was originally conceived in 2009 as a test bench for the Large Hadron Collider (LHC) collimators at a time when ad hoc installations were the baseline for such tests. Management approval and the securing of EU funding in 2010 got the ball rolling for the irradiation facility, and the construction was successfully completed in 2011,” says Ilias Efthymiopoulos, the Project Leader for the HiRadMat construction. “A challenge in the building of HiRadMat was the dismantling of the old T1 target of the West Area and the T9 target of West Area Neutrino Facility. The special tools we developed as part of the dismantling campaign are now used widely at CERN.”

“From the start, strong emphasis was put on offering exceptionally flexible beamline optics,” explains Malika Meddahi, Deputy Director for Accelerators and Technology and former Project Leader for beamline design, construction and commissioning. “The beam is extracted from the Super Proton Synchrotron (SPS) using the same extraction channel as LHC beam 1, then sent down the existing TT60 transfer line, from which the HiRadMat primary beamline (TT66) branches off after about 200 metres, offering spot sizes of 0.2–4 mm to the various experiments in a flexible way.”

Following the first experiments (starting with the test of a tungsten powder target under a high-power pulsed beam), several facilities at CERN based their designs on the data provided by HiRadMat experiments. “In the field of beam interception, we have tested particle-producing target prototypes, conducted R&D on advanced materials and carried out investigations on refractory materials,” explains Marco Calviani, Leader of the Targets, Collimators and Dumps section.

From the beginning, HiRadMat has been part of Transnational Access programmes EuCARD, EuCARD-2 and ARIES, making the facility accessible to users from all over the world. Today, the facility provides up to 2 x 10¹⁶ protons per year. “For the past ten years, HiRadMat experiments have been pushing the frontiers of beam-to-material knowledge, with 42 experiments successfully completed,” says Nikos Charitonidis, from the Experimental Areas group, who is responsible for the facility at CERN and chair of its technical board.

HiRadMat experiments are evaluated according to scientific criteria by a board of external experts. Among these specialists is Bernie Riemer, chair of the board and scientist at Oak Ridge National Laboratory. “Our role allows us to witness exciting developments in technology, materials and fundamental research for the benefit of CERN and worldwide collaborators.” A key member of the board and its first chair was the late Nick Simos from Brookhaven National Laboratory, who passed away in 2020. “We lost a mentor, friend and leader who worked actively to incite members, users and CERN staff,” recalls Bernie.

The legacy of Nick and of the HiRadMat team is already strong, as Verena Kain, Leader of the SPS Operation section, stresses: “HiRadMat has certainly helped to further increase the flexibility and versatility of the CERN LHC injectors.”

The story will continue during Run 3, as it has in 2021 with three CERN experiments: BLM3, for the calibration and verification of the LHC beam loss monitors; Multimat2, a critical benchmark of collimator materials in view of the HL-LHC upgrades; and HED, an important validation of high-energy dump design materials. With the next upgrade coming up, aiming to prepare the facility for more luminous and energetic beams, HiRadMat still has its best days ahead of it. “Studies are ongoing to upgrade the layout and key beam elements in order to allow for maximum beam intensities and brightness thanks to the LHC Injectors Upgrade project, enabling the facility to address a number of new experiments that the community is eagerly awaiting,” says Markus Brugger, Experimental Areas Group Leader.

This article is dedicated to Nick Simos.