Plans for electron-proton storage rings in Europe

The plans for electron-proton colliding beam machines in Europe are reviewed. Main drive is towards a large electron positron storage ring (LEP). However, there have been extensive discussions in the past few years covering a number of possibilities. At first, though it is not the purpose of this report to discuss in detail on the physics which can be carried out with a high energy e-p facility, brief summary is given for completeness. There was a 14 + 14 GeV electron positron colliding beam facility plan at Rutherford Laboratory in 1974. In November, 1976, proposal that CERN should investigate e-p collision at the SPS by adding an electron storage ring to the SPS tunnel. At present, it is not the intention in Europe to proceed with this proposal. The main reason for this is the decision to concentrate efforts on LEP. Second possibility in Europe is the construction of an e-p facility at DESY. This would be the development of the e+e- PETRA facility which is due to be completed in 1978. The would-be mode of operation is described. An electron proton option with LEP clearly requires that LEP is so located at CERN that it is possible to design a point of collision between the LEP electrons and 280 GeV protons in an SPS bypass. It should be emphasized that so far only very preliminary theoretical analysis has been made on the e-p option with LEP. (Wakatsuki, Y.)