An alpha particle is considered a high ioniser because it has a large mass and a double positive charge. This allows it to interact more strongly with other particles, causing it to transfer a significant amount of energy and ionize atoms it comes into contact with.
The mass of an alpha particle is about 4 times that of a proton. This larger mass means that it has a higher momentum and can penetrate deeper into materials, causing more ionization as it collides with atoms along its path.
The double positive charge of an alpha particle is important because it makes it highly attracted to negatively charged particles, such as electrons. This attraction leads to strong interactions and transfers of energy, resulting in the ionization of atoms.
The speed of an alpha particle is directly related to its kinetic energy, which is transferred to atoms during collisions. As alpha particles travel at high speeds, they can cause more ionization due to the increased energy transferred to the atoms they encounter.
Alpha particles are most effective at ionizing materials that have low densities and are relatively thin, such as gases and thin films. This is because they can easily penetrate these materials and interact with a larger number of atoms, resulting in a higher ionization rate.