(SμS) and an X-ray free-electron laser (SwissFEL). This makes PSI currently (2020) the only institute in the world to provide the four most important probes for researching the structure and dynamics of condensed matter (neutrons, muons and synchrotron radiation) on a campus for the international user community. In addition, HIPA's target facilities also produce pions that feed the muon source and the Ultracold Neutron source UCN produces very slow, ultracold neutrons. All these particle types are used for research in particle physics. Research at PSI is conducted with the help of these facilities. Its focus areas include: Matter and Material All the materials humans work with are made up of atoms. The interaction of atoms and their arrangement determine the properties of a material. Most of the researchers in the field of matter and materials at PSI want to find out more about how the internal structure of different materials relates to their observable properties. Fundamental research in this area contributes to the development of new materials with a wide range of applications, for example in electrical engineering, medicine, telecommunications, mobility, new energy storage systems, quantum computers and spintronics. The phenomena investigated include superconductivity, ferro- and antiferromagnetism, spin fluids and topological insulators. Neutrons are intensively used for materials research at PSI because they enable unique and non-destructive access to the interior of materials on a scale ranging from the size of atoms to objects a centimetre long. They therefore serve as ideal probes for investigating fundamental and applied research topics, such as quantum spin systems and their potential for application in future computer technologies, the functionalities of complex lipid membranes and their use for the transport and targeted release of drug substances, as well as the structure of novel materials for energy storage as key components in intelligent energy networks. In particle physics, PSI researchers are investigating the structure and properties of the innermost layers of matter and what holds them together. Muons, pions and ultra-cold neutrons are used to test the Standard Model of elementary particles, to determine fundamental natural constants and to test theories that go beyond the Standard Model. Particle physics at PSI holds many records, including the most precise determination of the coupling constants of the weak interaction and the most accurate measurement of the charge radius of the proton. Some experiments aim to find effects that are not foreseen in the Standard Model, but which