Problem 3.5: Determine the mass of a particle that decays into two photons

Particle speed v/c =

Please wait for the animation to completely load.

An unknown particle decays into two photons with wavelengths given in the animation.3  You can change the incident speed of the unknown particle. You can use the pink protractor to measure angles:  click-drag on the gray circles to move and adjust the angle of the protractor. (Angles are given in degrees and wavelengths in nm.)  A relationship you may find useful is hc = 1240 eV·nm. Restart.

  1. Develop a relationship for the angle the photons leave as a function of v/c.  Verify your relationship using the animation.
  2. Find the mass (in MeV/c2) of the unknown particle.  (What is it?)

3Based on Problems 2.37 and 2.39, J. Taylor, C. Zafiratos, and M. Dubson, Modern Physics, Prentice Hall (2004).

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