Yucal Ne'eman and Murray Gell-Mann

Physicists welcomed the news last month of and symmetric arrangement of many of the nearly the discovery of a subatomic particle which may 100 fundamental particles known today. It also bring some order out of the apparent chaos among provides a logical base for a naming system for nuclear particles. The omega-minus, discovered particles to replace the current colloquial names. by scientists working with the particle accelerator Though the names are still primarily Greek letters, at Brookhaven National Laboratory in New York, they now have more meaning. confirms a theory proposed independently, three As proposed, the eightfold way had a gap - an years ago, by Murray Gell-Mann, professor of unknown particle, conspicuous by its absence. To theoretical physics at Caltech; and Yuval Ne'eman fill this gap, a new particle, the omega-minus, was of Israel, now research fellow in theoretical phys- hypothesized. If the particle were to be discov- ics at Caltech. The theory relates nuclear particles ered, the gap would be filled and the Gell-Mann- to each other in a manner reminiscent of Mende- Ne'eman theory would be verified in one im- lyeev's periodic table of the elements. It sets up portant respect. "family relationships" between many of the strong- It was felt, moreover, that this verification ly interacting particles now known. (Strongly in- would make the eightfold way a certainty, since teracting particles are those subject to the force the properties prophesied for the omega-minus known, appropriately enough, as strong interac- were so unusual that they could not be predicted tion. This is one of the four known fundamental by extrapolation alone. forces, the other three being weak interaction, The omega-minus was discovered using the 33 electromagnetism, and gravitation. ) BEV alternating gradient synchrotron at Brook- Called the eightfold way, after Buddha's list haven to accelerate protons for the production of of eight virtues that lead to the cessation of pain, K-minus mesons. These were separated from the the theory is based on eight quantum numbers, beam by a 400-foot array of magnetic and electro- assignable to almost any particle, which evaluate static devices. The K-minus mesons were then certain characteristics of a particle. These quan- directed into the 80-inch bubble chamber and tum numbers, especially formulated for the ma- photographs taken of the trails left in the cham- nipulations of the eightfold way, are such novel ber, Out of 100,000 photographs, one omega-minus concepts that several of them do not yet have trail was found and confirmed by analysis with names. From the values for these quantum num- an IBM 7094. bers, which can be predicted via the eightfold The omega-minus has a mass of 1676 million way, many of the particle's properties (such as electron volts or about 3400 times the mass of an mass, decay time, or decay products) can be pre- electron. It decays into a xi particle and a pi- dicted to a high degree of accuracy. meson. The xi particle eventually decays into a Just as MendelyeevYsperiodic scheme brought proton, with the production of two more pi- some order into the elements known in 1870, so mesons, one at each decay step. It has a spin does the eightfold way bring about an orderly angular momentum of 312, and a positive parity.

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