[en] Numerical Runge-Kutta's method applied to a system of differential equations describing the isothermal decay kinetics of 15600 cm^-1 band in irradiated lilac spodumene, led to the conclusions which can be summarised as follows. The untrapping parameters α₁ and α₂ obey Arrhenius law with activation energies E₁ = 0.043ev and E₂ = 1.05 ev and pre-exponential factors α₁ = 30.6s^-1 and α₂ = 5.3x10¹²s^-1. The recombination parameter β and the retrapping parameters γ₁ and γ₂ were found to fit a function proportional to (T^1/2-T₀^1/2) with cutoff energy T₀ =346K. (author)