(comments to: moloney@nextwork.rose-hulman.edu)
(CUPS = Consortium for Upper Level Physics Software, published by John Wiley)

• Rutherford Scattering
• Electron Diffraction
• Special Relativity
• Laser Cavities and Dynamics
• Nuclear Properties and Decays
• Quantum Mechanics
• Hydrogenic Atoms and the H2+ Molecule

Rutherford Scattering

• Geiger and Marsden used 8.1 MeV alpha particles, scattered from a gold foil.
  Calculate the closest approach of such an alpha particle to a gole (Z=79) nucleus.
  Is it within range (10^-15 m) of the nuclear force?
• Calculate the deBroglie wavelength of an 8.1 MeV alpha particle.
  Is this large or small compared to the distance of closest approach?
• Run the simulation of the Geiger-Marsden scintillation experiment.
  If time is available, get enough points to observe a number of backscattered (>150 degrees) alphas.

Electron Diffraction

• Repeat the Davisson-Germer experiment. Use the (111) plane and do runs for accelerating voltages of 40,44,48,54,60, and 64 V. Record the height of the peak at 130 degrees for each run.

Quantum Mechanics

• Beam of particles incident on a barrier. Run the 'barrier' section of the program.
  Observe the qualitative difference when the beam energy is above the 2 eV height of the barrier, and when the incoming beam energy is below the 2 eV barrier height.
  Write down what you see for the wave function in each case, and give an explanation for the difference in behavior.
• Run the 'Uncertainty Principle' part of the program.
  Describe what happens to the spread in momentum as you make the particle 'smaller'.
  Make a sketch of the momentum spread for a 'narrow' and a 'wide' electron wave function.

Nuclear Decays

• In 'Geiger Tube Counting', do a run with the default parameters.
  Press 'Poisson' to bring up a poisson distribution curve which you can drag around on the screen. Since the GMT (geiger-muller tube) is 'dead' for a period after each count, you should be able to explain why the GMT distribution has a peak which is smaller than would be true for an 'ideal' counting tube.
• Predict which way must you move the incoming count rate from its initial value of 250/s so that the ideal and GMT curves will be closer together. Make the change in count rate, do the run, and record the peak values of each distribution.
• Change the incoming count rate to 8000/s. Now the counts are coming in with an average spacing of 125 microseconds. Leave the geiger tube dead time at 200 microseconds. Do a run and record the peak values of each distribution.
• Does the GMT distribution have the same 'width' as the ideal distribution?
• Bring up the poisson distribution and drag it over to the ideal distribution. How does it fit?
• Drag the poission distribution over the GMT distribution. How does it fit?
• Can you predict the peak of the GMT distribution if the count rate were set to an enormous rate, like 1 million per second? [ Every time the tube 'woke up' after being dead, bang! there would be another particle to count.]