資料來源 : Webster's Revised Unabridged Dictionary (1913)

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 particles (perhaps particles of helium)
   having enormous velocities but small masses. They are
   slightly deflected by a strong magnetic or electric field.