A possible mechanism for the injection of particles into a cosmic ray acceleration region

The composition of the nucleonic component of the primary cosmic radiation has been compared with the natural abundance of the elements. A normalized quotient between the abundance of an element in the radiation and in nature was found to be approximately equal toZ , whereZ is the atomic number and is a constant approximately equal to one. The observed excess of the heavy elements can be expected in the radiation if the selection of the cosmic ray particles is performed by ionization through fast electron or proton impacts on neutral matter having normal composition. Such a selection mechanism may act in regions in space where fast moving thin plasma clouds collide with clouds of neutral matter. A source model in which the plasma clouds originate in Type II supernova explosions is discussed.