Alpha

Alpha particles are particles released by radionuclides, consisting of two protons and two neutrons which is the same as a Helium atom. They’re released from the nucleus during nuclear decay, specifically alpha-decay. Alpha particles move very fast, but compared to other forms of nuclear radiation they move quite slow, at only 5-7% of the speed of light or 20 000 000 meters per second. Ernest Rutherford receives the most credit for the discovery of the alpha particle/ray, but there were other contributors.

Alpha radiation occurs most often in the decay of heavier elements, specifically elements heavier than lead. This doesn’t mean it only occurs here, but it is in these elements that it is most common. An alpha particle is incredibly ionizing for a multitude of reasons, mainly that they have a double positive charge and their slow speed. The speed at which they move means that they can cause multiple ionizations within a small distance. What’s good about all of this is that, because they’re highly ionizing, they aren’t capable o passing through very much. They’re stopped by a few centimeters of air or a thin piece of paper.