Martin Lewis Perl

Martin Lewis Perl was an American experimental physicist who discovered the tau lepton, the third charged lepton, and shared the 1995 Nobel Prize in Physics.

Burton Richter: An American physicist who shared the 1976 Nobel Prize for discovering the J/ψ particle. Richter led the Stanford team whose electron–positron collider Perl used to search for new particles.
Electron–positron annihilation: A process in which an electron and positron convert their energy into other particles. The SPEAR collider produced tau pairs through electron–positron collisions.
November Revolution: A rapid transformation in particle physics triggered by the 1974 discovery of the J/ψ particle. Its new accelerator era provided the experimental setting for Perl’s subsequent tau discovery.
Lepton generations: The three families of charged leptons and their associated neutrinos in the Standard Model. The tau’s discovery showed that the electron and muon were not the only charged leptons.
Samuel Ting: A Chinese-American experimental physicist who shared the 1976 Nobel Prize for discovering the J/ψ particle. Ting’s independent discovery illustrates the contemporary experimental search for unexpected particles.
SPEAR: A Stanford electron–positron storage ring that operated from 1972 and enabled major particle discoveries. Perl’s team collected the collision data that revealed tau-pair events at this accelerator.
SPEAR experiments: A series of particle-physics experiments conducted with Stanford’s SPEAR electron–positron collider. These experiments exposed unusual events that led Perl’s group to propose a new lepton.
Neutrino oscillation: The quantum-mechanical transformation of neutrinos from one flavor into another during propagation. The tau neutrino completed the third lepton family later probed through flavor-changing neutrino studies.
Melvin Schwartz: An American physicist who shared the 1988 Nobel Prize for developing neutrino-beam methods. Schwartz’s Nobel-recognized work represents the experimental particle physics tradition in which Perl worked.
Tau lepton: An elementary charged lepton with a mass about 3,500 times that of the electron. This was the new particle Perl identified from its production and decay signatures.

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Stanford Linear Accelerator CenterRelated: His work at SLAC revealed a third charged lepton, expanding the known particle families.