  When a given weight dropped onto an explosive charge, explosion or not is
probabilistic for certain impact energy and the frequency of explosion is
always increase with increasing impact energy. Based on experimental results
and recently theoretical work, we propose that the hot spot formation is
attributed to the activated molecules decomposition and the number of molecules
initiation is proportional to the impact energy but not the dropped weight
heating as the previous hot spot theory. A theoretical model based on two
states model has been put forward for this phenomena. It is shown that the
activated molecules to form a hot spot determine the probabilistic nature of
initiation by impact. It is shown a good agreement tested with Hexogen (RDX)
experimental impact data.
