  Semi-empirical method of calculation of quenching factors for scintillators
is described. It is based on classical Birks formula with the total stopping
powers for electrons and ions which are calculated with the ESTAR and SRIM
codes, respectively. Method has only one fitting parameter (the Birks factor
kB) which can have different values for the same material in different
conditions of measurements and data treatment. A hypothesis is used that, once
the kB value is obtained by fitting data for particles of one kind and in some
energy region (e.g. for a few MeV alpha particles from internal contamination
of a detector), it can be applied to calculate quenching factors for particles
of another kind and for another energies (e.g. for low energy nuclear recoils)
if all data are measured in the same experimental conditions and are treated in
the same way. Applicability of the method is demonstrated on many examples
including materials with different mechanisms of scintillation: organic
scintillators (solid C8H8, and liquid C16H18, C9H12); crystal scintillators
(pure CdWO4, PbWO4, ZnWO4, CaWO4, CeF3, and doped CaF2(Eu), CsI(Tl), CsI(Na),
NaI(Tl)); liquid noble gases (LXe). Estimations of quenching factors for
nuclear recoils are also given for some scintillators where experimental data
are absent (CdWO4, PbWO4, CeF3, Bi4Ge3O12, LiF, ZnSe).
