Experiments in relativistic kinematics: the universal speed limit and time dilation. The existence of an absolute limit, c, on the speed of particles is demonstrated by a measurement of the times of flight of cosmic-ray muons between scintillation counters in the laboratory. The mean life of muons at rest is then determined from a measurement of the distribution of radioactive decay times of muons that stop in a large plastic scintillator.
Given their measured short mean life, the measured speed limit, and the large distance they travel from their places of production high in the atmosphere, it is apparent that the muons in flight live much longer relative to an observer in the laboratory than muons at rest, in conformance with the predictions of relativistic kinematics.
Lab Guide (PDF)
A large plastic scintillator. (Image courtesy of Junior Lab staff.)
References
Rossi, Bruno. High-Energy Particles. New York, NY: Prentice-Hall, 1952, chapter 1, pp. 1-9.
———. "Interpretation of Cosmic-Ray Phenomena." Reviews of Modern Physics 20, no. 3 (1948): 537-583.
———. "Theory of Electromagnetic Interactions." Chapter 2 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 10-89.
———. "Experimental Methods." Chapter 3 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 90-145.
———. "Elementary Particles." Chapter 4 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 146-213.
———. "Cosmic Showers." Chapter 5 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 214-297.
———. "Experimental Results on the Electromagnetic Interactions of High-Energy Particles in Cosmic Rays and from Artificial Sources." Chapter 6 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 299-341.
———. "Nuclear Interactions of High-Energy Particles from Artificial Sources." Chapter 7 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 342-387.
———. "Nuclear Interactions of Cosmic-Rays (Part I)." Chapter 8 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 388-465.
———. "Nuclear Interactions of Cosmic-Rays (Part II)." Chapter 8 in High-Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 466-525.
———. "Appendices, Bibliography and Index." In High Energy Particles. New York, NY: Prentice-Hall, 1952, pp. 527-569.
———. Cosmic Rays. New York, NY: McGraw-Hill, 1964.
Griffiths, David. Introduction to Elementary Particles. New York, NY: Wiley, 1987, chapter 1, pp. 1-51. ISBN: 9780471603863.
———. "Theory of Weak Interactions and Muon Decay." Chapter 10 in Introduction to Elementary Particles. New York, NY: Wiley, 1987, pp. 301-309. ISBN: 9780471603863.
Perkins, Donald H. Introduction to High Energy Physics. Cambridge, UK: Cambridge University Press, 2000, p. 213. ISBN: 9780521621960.
A nice comparison positon spectra from muon (three body) and pion (two body decays).
Frisch, D. H., and J. H. Smith. "Measurement of the Relativistic Time Dilation Using mu-Mesons." American Journal of Physics 31 (1963): 342-355.
Hall, R. E., D. A. Lind, and R. A. Ristinen. "A Simplified Muon Lifetime Experiment for the Instructional Laboratory." American Journal of Physics 38 (1970): 1196-1200.
Selected Resources
Standford Linear Accelerator High Energy Cosmic Rays: A very nice overview of current cosmic ray research.