Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Alpha Rays

Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_55-2

Synonyms

Definition

An alpha ray is a stream of alpha particles. An alpha particle consists of two protons and two neutrons bound together into a particle identical to a helium nucleus; it is produced in the radioactive process called alpha decay. Alpha particles, like helium nuclei, have a net spin of zero. The energy of alpha particles varies, depending upon the specific decay reaction, with higher-energy alpha particles being emitted from larger nuclei, but most alpha particles have energies of between 3 and 7 MeV, corresponding to extremely long to extremely short half-lives of alpha-emitting nuclides. They are a highly ionizing form of particle radiation that when resulting from radioactive alpha decay have low penetration depth. Helium nuclei, which form 10–12 % of cosmic rays, are usually of much higher energy than those produced by radioactive decay.

See Also

Keywords

Penetration Depth Alpha Particle Radioactive Decay Large Nucleus Particle Radiation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.NTT Microsystem Integration LaboratoriesAtsugiJapan