The top quark was discovered in 1995 at
Fermilab, the end result of a few decades of
decidicated hunting by various groups around the world, using ever-more-powerful
accelerators,
detectors, and analytic systems.
The mass of the top quark is about 175 GeV, close to that of an entire
gold atom. This explains the difficulty in producing such quarks; the collision
energies inside the particle accelerators must be
incredible to allow particles of such mass to be born.