SommarioThe charmonium mass spectrum Outline The November revolution The discovery of the J/y The discovery of the J/y What is this resonance made of? Why y? Experimental techniques Electron-Positron annihilations Crystal Ball Proton-antiproton annihilations E760/E835 at Fermilab Two photon collisions Resonance scan Beam energy measurement The charmonium spectrum The fundamental state The fundamental state The state The state The resonance The resonance The P wave singlet state hc The resonance The state The state The state The state The D wave states The D wave states Conclusions |