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. He proposed and completed the construction of the electron-positron collider PETRA which led to the discovery and study of the gluon. During his mandate, DESY, a national laboratory became as far as science was concerned an international particle physics laboratory. This included the start of the first collaboration with China.