Stability

products of mass spectrometry and stability

I wonder about a mass spectrometry problem where they define which m/z that would appear for a molecule and why another m/z value does not appear that has a primary radical and a secondary cation. I know that the primary radical is unstable but the secondary cation is more stable than other products. Could one explain this by rate laws or rate constants mathematically? And in general explain which radicals and cations that are formed for normal alkanes?