alpha rays

1 definition found

alpha rays - Collaborative International Dictionary of English v.0.48 :

  Alpha rays \Alpha rays\ (Physics & Chem.)
     Rays of relatively low penetrating power emitted by radium
     and other radioactive substances, and shown to consist of
     positively charged alpha particles (helium nuclei) having
     enormous velocities but small masses. They are slightly
     deflected by a strong magnetic or electric field. Compare
     beta ray and gamma ray. Because the rays penetrate only a
     small distance in dense matter such as living tissue, small
     pellets of radioactive substances emitting alpha rays have
     been used to cause local destruction of tissue, as in cancer
     therapy.
     [Webster 1913 Suppl. +PJC]