Strange quark
The first strange particle (a particle containing a strange quark) was discovered in 1947 (kaons), but the existence of the strange quark itself (and that of the up and down quarks) was only postulated in 1964 by Murray Gell-Mann and George Zweig to explain the Eightfold Way classification scheme of hadrons. The first evidence for the existence of quarks came in 1968, in deep inelastic scattering experiments at the Stanford Linear Accelerator Center. These experiments confirmed the existence of up and down quarks, and by extension, strange quarks, as they were required to explain the Eightfold Way.
Franz N. D. Kurie
Franz Newell Devereux Kurie (February 6, 1907 in Victor, Colorado – June 12, 1972) was an American physicist who, while working at Yale in 1933, showed that the neutron was neither a dumbbell-shaped combination of proton and electron, nor an onion-shaped combination of an electron embracing the proton. Consequently, and until the discovery of the quark structure of hadrons, the neutron was assumed to be an elementary particle.