sentences:  In 1973 Schopper became Professor at the University of Hamburg and the Chairman of the Directorate of DESY, serving until end of 1980.He was responsible for the installation of the ARGUS detector at DORIS which later resulted in the first evidence of B – B bar mixing.Also, by establishing HASYLAB at DORIS synchrotron light science became an important branch of research at DESY.