Beta particles, or electrons, also

Beta particles, or electrons, also interact mainly with the orbital electrons of the atoms along their path. Because they are very light, they travel faster than alpha particles with equivalent energy. Because they are faster and have only half the charge of an alpha particle, they interactless frequently. Because they have little mass compared to the atoms, the path of the electrons is very tortuous or zigzagged with many reversals in direction. Thin layers of metal or about 0.1 m (several inches) of air are sufficient to absorb or stop beta particles. Ionization and excitation are the major interactions with the production of X-rays likely for high energy beta particles. If the beta particle is positively charged, it will annihilate with an electron at the end of its path as it loses its kinetic energy. The annihilation will result in two gamma rays moving apart at 180 degrees and each having an energy of 0.51 MeV (the energy equivalent to the rest mass of an electron).