The Prize Committee for Physics has unanimously decided that the Wolf Prize for 1982 should be equally divided between:
Leon M. Lederman
Fermi National Accelerator Laboratory Chicago and
Columbia University
New York, N.Y., USA
Martin M. Perl
Stanford Linear Accelerator Center
Stanford University California
Stanford, California, USA
for their experimental discovery of unexpected new particles establishing a third generation quarks and leptons.
The discovery of the charmed quark completed the set of eight particles, four quarks and four leptons, required by the 'standard model' of unified electromagnetic and weak interactions of Glashow, Weinberg and Salam. The discovery of a fifth quark and a fifth and sixth lepton came as a complete surprise and opened a new direction in particle physics. The search for a sixth quark required to complete this third family of quarks and leptons and the investigation of their properties are presently active and exciting areas of experimental research. The puzzles of why there are three such similar families, and possibly more, are completely open areas also for theoretical investigation.
Professor Leon M. Lederman and his associates discovered the upsilon particle after a long and sophisticated experimental program devoted to the study of the production of muon pairs, which was of interest in its own right. The upsilon and its two partners discovered in the same experiment were immediately recognized as the ground state and the first two excited states of the spectrum of bound states of a new fifth quark and its antiquark. The spacings between the energy levels provided significant new information for the theories of quantum chromodynamics describing the binding of quarks into hadrons, while the very existence of a fifth quark raised much deeper problems, which are still unresolved.
In addition, Lederman has participated in many other fundamental physics experiments, including the discoveries of the long-lived KO, the non-conservation of parity in muon decay and the existence of two kinds of neutrinos.
Professor Martin L. Perl single -handedly pushed, inspired, and directed the search for a new heavy lepton, which was not wanted by any theory and was not expected by the vast majority of particle physicists. The Perl group designed the apparatus to provide an unambiguous signature of the production and decay of a pair of heavy leptons. After the first events indicating the production of a pair of tau leptons, an intense period of review and criticism was required to verify this hypothesis. Since each candidate tau decayed into a visible electron or muon and a neutrino, which always escaped detection, the unambiguous identification of the tau presented unusual difficulty. Subsequent experiments determined many properties of the tau lepton and proved that the neutrino emitted in its decay is not one of the two known neutrinos and must be a sixth lepton completing the third lepton family. While many people contributed to these experiments, it was Professor Perl who guided the work and it was his careful analysis of the early data, which proved the existence of the new particle.