By stretching the energy limits of the DORIS storage ring to its fullest, experimenters at DESY in Hamburg have observed the upsilon and upsilon prime at roughly the masses reported in 1977 by Leon Lederman and his collaborators (PHYSICS TODAY, October 1977, page 17)—9.46 and 10.02 GeV/c2. But the new experiments have 20 times better energy resolution, primarily because they are done in an e+e storage ring.

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