||The electron is discovered,
except electrons are called cathode rays by their
||X rays and other forms of
radioactivity are observed
||Alpha particles are discovered,
and later shown to be helium nuclei consisting of two neutrons and
||Nuclear model of atom with
heavy nucleus in the middle and light electrons orbiting around
it, is proposed, and becomes accepted.
||Electron charge measured
in an oil drop experiment indicates that all electrons carry the
same electric charge.
||The neutron directly observed
in an experiment for first time.
||The positron, predicted by
a theorist in 1928, is discovered.
||Radioactive nuclei produced
in the laboratory.
||The muon, a charged lepton
like the electron only heavier and hence unstable, is discovered.
||Two charged pi mesons, with
positive and negative charge, are discovered.
||The neutral pi meson is discovered.
||The lambda baryon and K
meson are discovered.
||The electron neutrino, predicted
by theory in 1930, is confirmed to exist.
|Lots of baryons and mesons
being discovered, and their properties occur in regular patterns
that look as if baryons and mesons are made of smaller building
blocks. Physicists exhibit a tendency to name new particles after
letters in the Greek alphabet.
||The muon neutrino is discovered
and shown to be a different particle from the electron neutrino..
||Quark theory postulates that
protons are made of smaller particles that carry charges that come
in thirds of the electron charge. The three flavors of quarks are
given names: up, down and strange.
||Deep inelastic scattering and other experiments
reveal more of the quark structure inside protons and other hadrons.
||A fourth flavor of quark, named charm,
is detected in a newly discovered meson called the J
(aka the yor Psi).
||The tau lepton is discovered,
making a triplet of charged leptons with the electron and muon,
leading to predictions of a tau neutrino to accompany
the electron neutrino and the muon neutrino.
||A fifth flavor of quark, named bottom,
is detected in the newly discovered Upsilon meson. This pattern
leads particle physicists to believe they will find a sixth and
final flavor of quark some day. This predicted last flavor of quark
is called top.
||The massive gauge bosons that carry the weak
nuclear force, called the W+,W-
and Z0, are discovered and the Standard
Model of Particle Physics is confirmed.
||The lifetime of the Z0
weak nuclear gauge boson is measured, and agrees precisely with
there being exactly three kinds of neutrinos, and no more.
||The top quark is finally
directly observed and measured, confirming the predictions of theorists
that there are six flavors of quarks, as described in the Standard
||The search goes on for the Higgs boson
(the only particle predicted by the Standard Model that hasn't been
seen yet), for supersymmetric particles predicted
by string theory, for proton decay and for magnetic monopoles
predicted by Grand Unified Theories, and new kinds of exotic
unpredicted particles is ongoing. Perhaps in a few years
there will be some more interesting entries for this page. Come
back later and see.