Abstract: A method is described for stabilizing the anode sensitivity of a photomultiplier tube having a photocathode, an anode, and a plurality of dynodes including at least one Nichrome dynode adjacent to the anode. The steps include differentially heating the tube so that the temperature of the Nichrome dynodes and the anode is substantially greater than the photocathode. The temperature gradient established by the differential heating redistributes alkali material from the surface of the dynodes in a beneficial manner so as to balance the secondary emission gain of the dynodes so that decrease in Nichrome dynode gain is offset by increases in the gain of the other dynodes. The tube is then bright aged at a first voltage followed by a dark age at a higher voltage. The aging steps rearrange or rebind the remaining loosely bound alkali material to provide an increase in anode sensitivity stability.