Following German reunification, DESY expanded to a second site in Zeuthen near Berlin. In 1939, the German Postal Ministry founded a nuclear physics laboratory there. After World War II, the laboratory was first named "Institute X", to become the Institute for High Energy Physics (German : Institut für Hochenergiephysik IfH), the high-energy physics laboratory of the German Democratic Republic belonging to the Academy of Sciences of the GDR. The institute was merged with DESY on 1 January 1992. It focuses on parallel computing for theoretical particle physics, the development and construction of electron sources for X-ray lasers as well as astroparticle physics with a focus on gamma-ray and neutrino astronomy.