Electron Diffraction and Frank-Hertz Experiments: Experiment 1, Ionization Energies.
Spectroscopy Experiments: Experiment 2, Hydrogen Spectrum, Helium Spectrum.
Geiger Counter Experiments: Experiment 3, mn66.txt,
Gamma Experiments: Experiment 4, bax.txt, hox.txt, i129x.txt, leadx.txt.