Time evolution of the ﹩{Y}_{{\rm{e}}}﹩ for the selected tracer particles from B12 ﹩\beta ﹩ 1.00 (prompt-jet) and B11 ﹩\beta ﹩ 0.25 (delayed-jet). Each line begins at the onset of collapse, of which time is measured from the core-bounce. Thick lines are results taking into account all weak reactions between the nucleons and neutrinos, whereas thin lines are results ignoring neutrino absorptions.