IMPACT for Swiss society

PSI’s proton accelerator facility HIPA is world-leading in several parameters. Its protons are fed to three of PSI’s large research facilities, where research in fields such as materials science and particle physics is carried out at around 30 different experimental stations. The protons are also used to produce medical radionuclides. The planned IMPACT upgrade project is set to bring two high-calibre enhancements on line.

The first concerns the production of muons, which are a type of secondary particle produced by the protons. Two muon beamlines are to be remodelled, under the name HIMB, in such a way that the number of muons available for research will increase by a factor of 100.

The second aims for the construction, at a future branch of the proton beam, of a new facility called TATTOOS that will be used to produce important radionuclides. These in turn will enable the production of radiopharmaceuticals that can be used to diagnose and treat cancer.

Using radiopharmaceuticals to combat metastases

With these two improvements, IMPACT has a lot to offer Swiss society. In the case of TATTOOS, this is easy to demonstrate: PSI researchers are already at work developing new radionuclides and combining them with suitable biomolecules to produce new radiopharmaceuticals. Their potential benefits are being investigated in early clinical trials on patients at Swiss hospitals.

“Radionuclides are not in competition with external radiation therapy for cancer,” explains Cristina Müller, a researcher at the Center for Radiopharmaceutical Sciences at the PSI Center for Life Sciences and also an adjunct professor at ETH Zurich. External radiation therapy is an established treatment for a clearly localised tumour, she says. “Our therapy, on the other hand, is needed when the cancer has spread throughout the body. In short, when there are metastases.”

Müller’s work is trailblazing: “At PSI we produce radionuclides that are difficult to obtain elsewhere. However, we are currently limited to a few exotic radionuclides and can only produce them in small quantities.”

The researchers at the Center for Radiopharmaceutical Sciences have also been working for more than a decade with CERN, which has particle accelerators that produce the medically interesting terbium-149 isotope. However, the radioactive decay half-life of this nuclide is so short that the amount of the rare substance decreases significantly just during travel time from Geneva to Villigen. “We always hope the driver won’t encounter any traffic jams on the way – because really every minute counts,” says Müller.

A unique production site for radionuclides

Eliminating travel time will be the first major advantage of TATTOOS: A trip across the PSI campus takes only a few minutes. But that's not all: “To exploit the full range of medically interesting radionuclides, you need high-intensity particle beams that are only available at a few facilities worldwide,” says Nick van der Meulen, head of the Radionuclide Development Group at PSI. “We have the intense proton beam thanks to HIPA, and with TATTOOS we will be able to make ideal use of it.” In this way a unique production site for a broad range of different radionuclides will come into being. “And we will be able to produce larger quantities overall than any other facility in the world,” van der Meulen says.

The PSI researchers plan to use this capability to develop several new types of radiopharmaceuticals. They also want to provide nuclide types with longer half-lives to other research groups in Switzerland and around the world. “The long-term goal for medical applications is personalised therapy: One day we want to have a suitable radiopharmaceutical for every type of cancer and every stage of cancer,” Müller says.

«Long-term» is a significant keyword here. “The radiopharmaceuticals developed using TATTOOS could be of benefit to people in around ten years,” van der Meulen says. “And precisely because we know about this development time, we want to get started now.”

Muons for archaeology, particle physics, and energy research

Zaher Salman and Lea Caminada have a similar long-term perspective. Both are researchers at the PSI Center for Neutron and Muon Sciences, working with particles smaller than atoms. “We use neutrons and muons in various ways,” Salman explains. On the one hand, the particle beams can be used to non-destructively probe and examine archaeological artefacts. “Here we regularly work together with Swiss museums.”

On the other hand, muons are also used in basic research: In particle physics, they can be used to experimentally test mathematical models that describe our universe; and in materials science, they are used to understand the fundamental properties of a material. “The development of hard drives, which today can store terabytes of information, began in exactly the same way,” says Salman. “Accordingly, we need to lay the foundation today for the technologies that will, in turn, be part of our everyday lives a few decades from now.”

This is where HIMB comes into play. “The technological state of the art has advanced to the point where we can achieve much higher muon rates with HIMB,” explains Lea Caminada, head of the High-Energy Physics Group. “With our experiments, we will then be able to penetrate into areas that were previously inaccessible.”

One bottleneck, for example, involves low-energy – that is, slow – muons. These penetrate less deeply into the sample and thus allow researchers to investigate, in a targeted way, physical processes that take place close to the surface or at interfaces between materials. “We are looking at solar cells, for example – there the exciting processes take place where the light hits,” Salman explains. The situation is similar with lithium batteries, where the crucial physical processes take place in very thin films. “Solar cells and lithium batteries are already part of our everyday lives, but our research can help to increase efficiency by a few crucial percentage points.”

Low-energy muons are very difficult to produce – yet they do arise in small quantities at PSI’s muon beamlines. “With HIMB, we will increase the quantity of muons a hundredfold,” says Salman, “and thus also obtain a hundred times more low-energy muons.

Cutting-edge research triggers technological innovation

Caminada, who in addition to her position at PSI is an SNF Eccellenza Professor at the University of Zurich and also conducts research at CERN, emphasises another aspect: “A new research facility is only as good as its components.” Therefore the construction of particle accelerators has always driven the development of many new technologies, Caminada says. She and her team have developed high-quality detectors that are used in CERN's Large Hadron Collider. They are currently working on detectors that will be used for future experiments with muons. “Our detectors are also of interest for applications in archaeology, environmental sciences, and medicine,” the physicist explains. 

Caminada is confident that cutting-edge research will continue to spur developments that benefit society. “With IMPACT, we will actively contribute to this.”

In December 2024, the Swiss Parliament will decide on the financing of the ERI Dispatch 2025-2028, and thus also on financing for the IMPACT project.