Large Research Facilities

Magnets are the unsung heroes in particle accelerators because they keep protons or electrons on track. But such magnets have very little in common with the small ones on the domestic fridge door. Quite a few of the magnets at PSI are heavier and bulkier than the fridge itself, yet despite this they are also masterpieces of precision and control.

The source of the proton beam at PSI is a retro-style Cockcroft-Walton linear accelerator. Since 1984 it has been the first acceleration stage for protons which are taken up to around 80 percent of the speed of light by two further ring accelerators. This has resulted in the generation of a significant proton beam over decades, and which has even held the world record as the highest performing beam since 1994 thanks to ongoing retrofitting.

PSI researchers garner experience for SwissFEL experimentsAided by short laser flashes, researchers at the Paul Scherrer Institute have managed to temporarily change a material’s properties to such a degree that they have à to a certain extent àcreated a new material. This was done using the x-ray laser LCLS in California. Once the PSI x-ray laser SwissFEL is up and running, experiments of this kind will also be possible at PSI.

Vergangenen Sonntag luden das Paul Scherrer Institut PSI und die Arbeitsgemeinschaft EquiFEL Suisse die Einwohnerinnen und Einwohner der Umgebung zum Tag der offenen SwissFEL-Baustelle ein. Rund 600 Interessierte informierten sich an mehreren Stationen über den aktuellen Bau- und Projektstand.This news release is only available in German.

The way that algae and plants respond to light has been reinterpreted based on results from recent experiments. Under particular lighting conditions during photosynthesis, the well-ordered stacking and alignment of light-sensitive membranes in the algae are disrupted. There is no significant movement of the membrane embedded light harvesting proteins, which rather become largely inactive. These new findings challenge widely accepted views of how algae respond to light where the light harvesting proteins were thought to move around the membranes.

For the electrons to reach the necessary energy level, their path in the linear accelerator needs to be absolutely straight. Even the slightest bend means a loss of energy, which the comparatively short SwissFEL linear accelerator cannot afford. Consequently, even the earth’s curvature needs to be balanced out while constructing the building, which not only requires state-of-the-art measurement technology, but also continuous monitoring.

Changes to the aggregate state triggered by quantum effects à in physically correct terms, quantum phase transitions à play a role in many astonishing phenomena in solids, such as high-temperature superconductivity. Researchers from Switzerland, Great Britain, France and China have now specifically altered the magnetic structure of the material TlCuCl₃ by exposing it to external pressure and varying this pressure. With the aid of neutrons, they were able to observe what happens during a quantum phase transition, where the magnetic structure melts quantum-physically.

Researchers from ETH Zurich and the Paul Scherrer Institute PSI demonstrate how the magnetic structure can be altered quickly in novel materials. The effect could be used in efficient hard drives of the future.

Materials research, particle physics, molecular biology, archaeology à for the last forty years, the Paul Scherrer Institute’s large-scale proton accelerator has made top-flight research possible in a number of different fields.

Preventing SwissFEL electrons from going astrayCost-effective and with a minimal error rate àPSI-engineers from the power electronics section have set ambitious goals for the SwissFEL magnet power supplies.

The construction work in the woods is well underway: the building for SwissFEL, the Paul Scherrer Institute’s new large research facility, is due for completion by the end of 2014. The demands on the building are high: It needs to ensure that the sensitive equipment can run smoothly.

SwissFEL will create X-ray light with laser-like characteristics. The strong amplification of the light needed is produced by a process known as micro-bunching à electron packets break up in the undulator into thin layers which emit light in phase. At the same time, another process called seeding is being studied, in which one will be able to establish the properties of the light even more precisely.

X-ray light is produced in SwissFEL when electrons accelerated in its linear accelerator are forced to follow a wavy path. This takes place within the undulators à regular arrangements of magnets that bend the electron beam. The whole undulator section will be 60 metres long.

A terahertz laser developed at the Paul Scherrer Institute makes it possible to control a material’s magnetisation precisely at a timescale of picoseconds. In their experiment, the researchers shone extremely short light pulses from the laser onto a magnetic material. The light pulse’s magnetic field was able to deflect the magnetic moments from their idle state in such a way that they exactly followed the change of the laser’s magnetic field with only a minor delay. The terahertz laser used in the experiment is one of the strongest of its kind in the world.

In the linear accelerator, the electron beam receives the kinetic energy it needs in order to generate X-ray light. The linear accelerator is, in total, more than 300 metres long and at its heart there are 11,752 specially shaped copper discs in which the accelerating field is created.

The electron beam for SwissFEL will be generated in an electron source. The demands of this component are very high: in order for the SwissFEL to be operated successfully, the electron beam must be of the highest quality from the very beginning.

At the PSI, the first accelerator structure has been completed for the linear accelerator of SwissFEL. A total of 104 of these structures are needed to accelerate the electrons to the required energy to produce the X-ray pulses in SwissFEL. The component manufactured using high-precision technology is currently undergoing high-performance testing.

The manipulation and examination of irradiated and therefore radioactive objects, be they from nuclear power stations or research facilities, requires strict safety measures. Tests may only be conducted in so-called “hot cells”, where the radioactivity is hermetically enclosed and shielded behind concrete and lead walls up to 1 metre thick. In the hot cells of the PSI hot lab, the burnt-off fuel rods from the Swiss nuclear power stations are studied from a materials science perspective. The insights gained help nuclear power station operators to optimise the efficiency and safety of their plants. Besides this service, the hot lab is involved in several international research projects.

At the ceremony on 3 July 2013, not only did the PSI lay the corner stone for the new large research facility SwissFEL, but it also paved the way for the continuation of twenty-five years of successful research at the institute.

Muons à unstable elementary particles à provide scientists with important insights into the structure of matter. They provide information about processes in modern materials, about the properties of elementary particles and the nature of our physical world. Many muon experiments are only possible at the Paul Scherrer Institute because of the unique intense muon beams available here.