Pretty cool box: irradiation facility in Birmingham gets AIDA upgrade
Barbara Warmbein (DESY), 12/07/2018
Cold box in the lab in Sheffield, ready for installation in Birmingham’s cyclotron. (Image: Richard French)
A new cold box for the University of Birmingham’s irradiation facility is ready to move into its new home. Built by the University of Sheffield as part of AIDA-2020 Work Package 15, it features a new robotic scanning system for faster sample irradiation and a new cooling system to cool the silicon sensors under test.
In the High-Luminosity Large Hadron Collider (HL-LHC), sensors in ATLAS and CMS, the LHC detectors, will have to withstand much higher doses of radiation. Higher luminosity, i.e. a higher number of collisions than ever before, means not only the possibility for more interesting particles in the detector, but also more potential radiation damage. To better understand and possibly tweak the performance of all components that will be exposed to the radiation from the LHC, scientists put the materials under a “radiation stress test” in an irradiation facility, which can deliver the same dose of radiation to the samples in just a few hours that they are likely to receive during their lifetime in the LHC detectors. To see how they perform and react can lead scientists to better sensors and more accurate results from the data.
One such irradiation facility is located at the University of Birmingham in the UK. Its particles come from a cyclotron whose day job it is to produce radio isotopes for medical purposes. This day job, however, is really a night job, because the radio isotopes are produced overnight and delivered to hospitals in the morning. During the day, the cyclotron was used for experimental physics. In 2011, high-energy physicists had the idea to use it as an irradiation facility and since then the facility has evolved and improved, working for physics during the day and for medicine at night.
Over the years, upgrades and improvements have been made to the high-intensity irradiation zone for physics uses – for example, a new shielding area was installed five years ago and a prototype cool box set up. This temporary cool box and scanning robot will soon be replaced with the final-design one developed and produced by Richard French’s research group at the University of Sheffield under AIDA-2020 Work Package 15. Installation is foreseen for completion in September 2018.
The volume inside the new cold box has been reduced, which makes for more efficient cooling. The cooling system itself is simpler than the one in the prototype, with evaporated nitrogen blowing cool air over the samples. “Because you don’t want to handle samples in the high-radiation environment, you need a reliable robotics system,” explains Richard French, engineer and robotics expert. “It moves the samples across, so that every bit gets a uniform dose. If we don’t do that, we get stripes of areas with more and less radiation, like bits of skin exposed to the sun. That botches the results, so we need to irradiate very carefully.”
Once the new cold box is installed, users can start irradiating their samples. To find out more about the cyclotron and its possible uses, visit: http://test-static-02.web.cern.ch/content/uob