Linked from
The 34 pages that link to Alpha particle, each with the reason it gives.
Alpha decayBroader topic: It is the particle emitted when an unstable nucleus undergoes alpha decay.
Ionizing radiationBroader topic: Its charge and mass make it strongly ionizing over a short range.
Helium-4Broader topic: Helium-4 nuclei released by radioactive decay are called alpha particles.
Geiger–Nuttall lawBroader topic: Its kinetic energy is the measurable quantity used in the law.