  It is demonstrated that a pair can be characterized under which mechanism it
was created according to its conversion energy, a quantity defined as the sum
of electron and its conjugate positron's mass-energy, in the study of
electron-positron pair creation. The value of this quantity is checked with
quantum field theoretical simulations for several field configurations and
found that it can describe the creation process with rich physical picture,
showing all the creation channels and giving the yields of each channel
specifically. Evenly as a very convenient and powerful detection quantity it
can be applicable to some complicated pair creation processes such as that
triggered by cooperation of two different photons as well as the dynamically
assisted Schwinger mechanism.
