Alpha and Beta Radiation:

Alpha particles, being the largest particles of radiation and having a +2 charge, interact along with matter more readily than other categories of radiation. Every interaction outputs in a loss of energy. That  is why  the  alpha  has  the  shortest  range  of  all  the  categories  of  radiation. Alpha particles commonly are stopped through a thin sheet of paper. Since a comparison then a 4 MeV alpha particle will travel about 1 inch in air, while a 4 MeV beta particle will travel about 630 inches in air. Since it deposits all of its energy in an extremely small area, the alpha particle travels just a short distance.