INTERACTION OF RADIATION WITH MATTER

DOE-HDBK-1019/1-93 Atomic and Nuclear Physics INTERACTION OF RADIATION WITH MATTER INTERACTION OF RADIATION WITH MATTER Different types of radiation interact with matter in widely different ways. A large, massive, charged alpha particle cannot penetrate a piece of paper and even has a limited range in dry air. A neutrino, at the other extreme, has a low probability of interacting with any matter, even if it passed through the diameter of the earth. EO 5.1 DESCRIBE interactions of the following with matter: a. Alpha particle c. Positron b. Beta particle d. Neutron EO 5.2 DESCRIBE the following ways that gamma radiation interacts with matter: a. Photoelectric effect b. Compton scattering c. Pair production Interaction of Radiation With Matter Radiation can be classified into two general groups, charged and uncharged; therefore, it may be expected that interactions with matter fall into two general types. Charged particles directly ionize the media through which they pass, while uncharged particles and photons can cause ionization only indirectly or by secondary radiation. A moving charged particle has an electrical field surrounding it, which interacts with the atomic structure of the medium through which it is passing. This interaction decelerates the particle and accelerates electrons in the atoms of the medium. The accelerated electrons may acquire enough energy to escape from the parent atom. This process, whereby radiation "strips" off orbital electrons, is called ionization. Uncharged moving particles have no electrical field, so they can only lose energy and cause ionization by such means as collisions or scattering. A photon can lose energy by the photoelectric effect, Compton effect, or pair production. Rev. 0 Page 63 NP-01