Alpha, Beta, and Gamma Rays More than 99.9% of the atoms in our everyday environment are stable. The nuclei in those atoms will likely not change over the lifetime of the universe. But some kinds of atoms are not stable. All elements having an atomic number greater than 82 (lead) are radioactive. These elements, and others, emit three distinct types of radiation, named by the first three letters of the Greek alphabet, α , β , γ ---- alpha ,beta, and gamma. --->Alpha rays have a positive electrical charge, ---->Beta rays have a negative charge, and ----->Gamma rays have no charge at all. The three rays can be separated by placing a magnetic field across their paths . Further investigation has shown that an ----> Alpha ray is a stream of helium nuclei, and -----> Beta ray is a stream of electrons. Hence, we often call these alpha particles and beta particles. ------> Gamma ray is electromagnetic radiation (a stream of photons) whose frequency is even higher than that of X-rays. -----> X-rays originate in the electron cloud outside the atomic nucleus, -----> Gamma rays originate in the nucleus. Gamma photons provide information about nuclear structure, much as visible and X-ray photons provide information about atomic electron structure. ----> Alpha particles are the least penetrating and can be stopped by a few sheets of paper. -----> Beta particles will readily pass through paper, but not through a sheet of aluminum. ------> Gamma rays penetrate several centimeters into solid lead.
Posted on: Sat, 15 Mar 2014 08:24:07 +0000