Overview

Sometimes, one needs unusually large pieces of equipment to look at the smallest of objects – because only these large machines or facilities can generate the probes that are needed to examine matter in such a way that the information being sought can be obtained. PSI maintains a number of such facilities, making them available as a service for other institutions, but also using them for its own research. These facilities are unique within Switzerland, and PSI is the only location in the world for some of the facilities

Research using large facilities

The large facilities at PSI generate neutrons, muons and synchrotron light. Neutrons and muons are very small particles, while synchrotron light is X-ray radiation at an extremely high level of intensity, with adjustable energy. These three probes can be used to obtain information about the structure of a very wide range of materials, with each probe being especially well-suited to specific experiments.

The latest large research facility at PSI generates very short pulses of X-ray light with laser-like properties. This enables researchers to observe extremely fast processes, such as how new molecules are created in a chemical reaction; to determine the detailed structure of vital proteins; or to determine the exact structure in materials. The insights gained in this way expand our understanding of nature and lead to practical applications, for instance new pharmaceuticals, more efficient processes in the chemical industry, or new materials for electronics.

Synchrotron light is a particularly intense form of light, with characteristics that can be precisely adapted to the requirements of an experiment. Scientists use synchrotron light to determine the detailed structure or the magnetic properties of various materials. Among the materials investigated with synchrotron light are magnetic materials such as those used in modern magnetic memories or protein molecules that play a crucial roles for many processes in living organisms. At PSI, synchrotron light is produced at the Swiss Light Source (SLS), where it is emitted by electrons travelling at almost the speed of light on a circular path of 288m in circumference. Strong magnets are used to keep them on this path.

Neutrons are used to determine the arrangement or motion of atoms in materials. Because neutrons are particles that behave like very tiny magnets, they are also especially suited to the investigation of magnetic materials. In nature, they exist as components of atomic nuclei. At PSI, the SINQ (pronounced: sin-cue) spallation source generates neutrons for experiments.

Muons are mainly used in investigations of magnetic fields within materials. They are elementary particles with properties very similar to those of electrons but being much heavier and unstable. When a muon decays inside a material, it carries information about the magnetic field in a sample. At PSI, muons are generated in the SμS (pronounced: es-myoo-es) muon source .

With the help of CHRISP, researchers are using the internationally most powerful source of ultracold neutrons to investigate how our universe is structured. They determine, for example, fundamental natural constants with the highest precision and search for deviations in the current standard model of particle physics. They also develop and test detectors for experiments at PSI, for space missions and for the European research centre CERN in Geneva.

The neutrons and muons used in experiments at PSI are generated by collision of a beam of very fast protons with a special target – made of lead in the case of the SINQ neutron source and of carbon in the case of the SμS muon source. The protons used have been accelerated to a speed of approximately 80 % of the speed of light by PSI's proton accelerator facility. This facility came into operation in 1974 and was originally used for experiments in the area of elementary particle physics. Nowadays, it generates the most intense beam of protons in the world.