In the fine-grain thermoluminescence (TL) dating the full alpha dose must be converted into equivalent beta dose. The conversion is accomplished by alpha effectiveness K3.7-value. To obtain K3.7 a collimated alpha beam from source must be used, of which the energy should be just 3.7MeV while it arrive at the irradiated sample. It is very difficult for general laboratory if TL dating. Therefore Aitken proposed the [alpha]-value system. This system has a great advantage that the difficulty of alpha source calibration surmounted by the S. The S is alpha source strength, it is the total trace length of alpha particles per unit volume or quartz sample per unit time, expressed in ([mu]m/[mu]m3)/min or [mu]m-2/min. The alpha effectiveness K3.7 can be obtained directly from the strength S of an alpha source.