could correct inconsistencies in the theory or solve unexplained phenomena from astrophysics and cosmology. Their results so far agree with the Standard Model. Examples include the upper limit measured in the MEG experiment of the hypothetical decay of positive muons into positrons and photons as well as that of the permanent electric dipole moment for neutrons. Muons are not only useful in particle physics, but also in solid-state physics and materials science. The muon spin spectroscopy method (µSR) is used to investigate the fundamental properties of magnetic and superconducting materials as well as of semiconductors, insulators and semiconductor structures, including technologically relevant applications such as for solar cells. Energy and the Environment PSI researchers are addressing all aspects of energy use with the aim to make energy supplies more sustainable. Focus areas include: new technologies for renewable energies, low-loss energy storage, energy efficiency, low-pollution combustion, fuel cells, experimental and model-based assessment of energy and material cycles, environmental impacts of energy production and consumption, and nuclear energy research, in particular reactor safety and waste management. PSI operates the ESI (Energy System Integration) experimental platform to answer specific questions on seasonal energy storage and sector coupling. The platform can be used in research and industry to test promising approaches to integrating renewable energies into the energy system - for example, storing excess electricity from solar or wind power in the form of hydrogen or methane. At PSI a method for extracting significantly more methane gas from biowaste was developed and successfully tested with the help of the ESI platform together with the Zurich power company Energie 360°. The team was awarded the Watt d'Or 2018 of the Swiss Federal Office of Energy. A platform for catalyst research is also maintained at PSI. Catalysis is a central component in various energy conversion processes, for example in fuel cells, water electrolysis and the methanation of carbon dioxide. To test the pollutant emissions of various energy production processes and the behaviour of the corresponding substances in the atmosphere, PSI also operates a smog chamber. Another area of research at PSI is on the effects of energy production on the atmosphere locally, including in the Alps, in the polar regions of the Earth and in China. The Nuclear Energy and Safety Division is dedicated to maintaining a good level of nuclear expertise and thus to training scientists and engineers in nuclear energy. For example, PSI maintains