A bare neutron (i.e. one outside a nucleus) will decay into a
proton plus an electron plus neutrino. Knowing the rest masses of the
proton and electron, and measuring the endpoint of the beta spectrum you
can determine the mass of the neutron.
An interesting question for your students..... given that a
neutron beta decays with a relatively short half life (about 14 minutes),
why are we still here.....
Mark
Dr. Mark H. Shapiro
Physics Department
California State University, Fullerton
P.O. Box 6866
Fullerton, California 92834-6866