PhD student Nicolo Borghi, who is responsible for building the measuring instrument, with a sketch of the model for the new instrument. DTU’s cobalt source in the background. Photo: DTU Nutech

DTU to develop yet another instrument for new neutron research facility

Physics Radioactivity
DTU’s expertise in developing high-tech measuring instruments has led to yet another assignment for the neutron research facility ESS—European Spallation Source. The instrument is intended to monitor the very core of the system in which the neutron fission occurs.

ESS—currently under construction in Lund, Sweden, and scheduled for completion in 2023—will become the world’s most powerful and advanced neutron source. Established technology as well as newly developed materials and methods are applied in the design of the neutron source.

“The system is built around a large so-called target wheel. It’s the heart of ESS. Inside the target wheel, particles are fired at high speeds into the heavy metal tungsten, which is what the wheel is made of. The neutrons are thereby released into ESS’ different neutron scattering instruments, which serve as microscopes with the possibility of studying the structure of materials down to atomic level,” explains Bent Lauritzen, Senior Researcher and Head of Division, DTU Nutech.

The target wheel is a huge and heavy, measuring approx. 2.5 m in diameter. When firing particles, excessive heat is produced in the wheel. The wheel is cooled down by means of helium circulating between the tungsten bricks comprising the wheel.

“The technology is brand new, and ESS wants to be able to continuously monitor that the tungsten bricks in the wheel don’t crack and block the cooling channels, which will cause the wheel to overheat. We have therefore been asked to help design and develop an instrument for imaging diagnosis capable of seeing through the tungsten bricks’ steel cover to check whether they are intact,’ explains Bent Lauritzen.

Challenging and risky specialist task
The development of the new monitoring instrument is a task that requires specialist knowledge about radiation as well as instruments, and which is both challenging and risky.

“We’ve been involved in both drawing up the problem definition and developing a solution. Based on DTU’s unique combination of insight into the splitting processes generating the neutrons, and experience with the development of radiation detectors, we’ve been assigned the development task. Initially, we’re conducting a preliminary study, and of course there’s always a risk that we won't succeed. But we truly believe in our design, which is why we’ve chosen to build a prototype here at DTU Nutech to serve as a model for the final instrument,” says Bent Lauritzen.

In the first stage, the measuring instrument will be tested on DTU’s radioactive cobalt source at Risø, but in the long term, we intend to test it on a neutron source.