sentences:  A financial agreement was signed on 18 December 1959, which founded the "Deutsches Elektronen-Synchrotron" (DESY), a 7.5 GeV electron synchrotron.Jentschke was chairman of the DESY Board of Directors from 1959 to 1970, and for many years also the director of the Second Institute of Experimental Physics at the University of Hamburg.While at DESY, Jentschke endorsed the electron-positron storage ring scheme for the DORIS accelerator, and promoted the use of synchrotron radiation for research purposes.