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1			What tool enabled scientists to observe hundreds of different hadrons in the latter half of the twentieth century?
2			How many different hadrons are stable (as far as we know)?
3			A neutral pion (mass 0.135 GeV/c2) decays via the electromagnetic interaction into two photons: π0→γ + γ. What is the energy of each photon, assuming the pion was at rest?
4			The energy at which the fundamental forces are expected to unify is about 1019 GeV. Find the mass (in kg) of a particle with rest energy 1019 GeV.
5			What is the de Broglie wavelength of a proton with kinetic energy 7.0 TeV?