Stock Photo - 22 August 2020, Saxony, Leipzig: Helpers from the hygiene team follow a concert during a large-scale trial of the University Medicine Halle/Saale in the Arena Leipzig. Around 2200 visitors take part in the experiment entitled ""Restart-19"", in which pop singer Tim Bendzko will perform. The scientists want to use sensors and other aids to monitor their walking paths and fluorescent disinfectant is to make visible which surfaces are touched particularly often. The flight of aerosols - the smallest mixtures of particles that can carry the virus - will also be tracked. The aim is to develop a mathematical model that can be used to assess the risk of corona outbreak after a major event in a hall. Photo: Hendrik Schmidt/dpa-Zentralbild/ZB. - Leipzig/Saxony/Germany