New Facilities—Colliding Beams

Well before the construction of SLAC was completed, there was interest in constructing facilities in addition to those planned for in the initial complement of research equipment. Specifically, the interest in colliding beam facilities at SLAC had already started in 1961 in discussions involving Burt Richter, David Ritson from the physics department, and others. As noted previously, the electron–electron colliding beam facility at HEPL did not start generating results until SLAC construction was well under way. It was well understood at that time that the research program which an electron–electron collider could support was much more limited than what an electron–positron ring could do, but at the same time it was recognized that electron–positron rings required additional development and of course, a positron source. In the meantime, interest in electron–positron rings arose in Europe. A small electron–positron ring called ADA was completed in Italy in 1961. It functioned as designed but operated at too low an energy to support research. A larger ring, ADONE, was completed in 1967 at 1.5 GEV per beam and rings of similar energy were constructed in Orsay, France, and in Novosibirsk.