Definition of "neutron" []

• An electrically neutral subatomic particle in the baryon family, having a mass 1,839 times that of the electron, stable when bound in an atomic nucleus, and having a mean lifetime of approximately 1.0 × 103 seconds as a free particle. It and the proton form nearly the entire mass of atomic nuclei. See Table at subatomic particle. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Cosmo – A long-term neutron measurement project, under the tutelage of the late Dr. Jack Lockwood and Dr. Jim Ryan of UNH's Physics Department, Institute for the Study of Earth, Oceans, and Space."
• "Apart from any surface contamination of the plant, the remaining radioactivity comes from "activation products" such as steel components that have been exposed to long-term neutron irradiation."
• "There were many problems in neutron diffusion such as finding the critical mass that required more careful formulations than had been carried out in the earliest projections."