Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Muons
Name: Ty W.
Status:  student
Age: $6
Location: N/A
Country: N/A
Date: 5/5/2004

What is a muon?

Ty W.

A muon is a particle very much like an electron. The biggest difference is that a muon is much heavier than an electron. Other than that, muons and electrons are essentially the same. In fact, a muon can become a much lighter electron. The change of mass becomes energy, released as neutrinos and photons of light. An electron can last forever. A muon will only last a few seconds before becoming an electron.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College

A muon is a lepton. There are three leptons (called electron, muon, and tau) which have identical properties and interactions, except that their masses are quite different.. For example, they all have the same built in angular momentum (spin) and magnetic moment. The muon has about 200 times the mass of the electron and the tau has a mass about 3500 times the mass of the electron. Because of their large masses and short lifetimes (the muon has a half life of about two millionths of a second), the muon and tau are very rare compared to the electron, though muons are produced quite often by cosmic ray interactions in the atmosphere.

If you would like more information, I would strongly recommend the web site

Best, Dick Plano, Professor of Physics emeritus, Rutgers University

Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory