A silicon wafer (NA​=10¹⁴ cm⁻³,τn​=1μsec) is first illuminated for a time t≫τn​ with light which generates GLO​=10¹⁶ electron-hole pairs per cm3−sec uniformLly throughout the volume of silicon. At time t=0, the light intensity is reduced, making GL​=GLo​/2 for t≥0.