sentences:  In 1971, Jentschke accepted the post as Director General of CERN Laboratory I (the Meyrin site); John Adams was Director General of the neighboring CERN Laboratory II (Prévessin), where the new SPS proton synchrotron was being constructed.They shared the directorship of CERN until the two laboratories were united in 1976.While Director General, Jentschke oversaw the exploitation of the new research tool, the Intersecting Storage Rings, which began operation in 1971.