2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87330I propose the coefficient, $t_h$, and its modification $N_t$ which in a simple way reflect dynamics of scientific activity of an individual researcher. I determine $t_h$ as a time period (from some moment in the past till the present moment) during which papers responsible for 1/2 of the total citation index were published. Parameter $N_t$ represents average of the citation index over this period: $N_t={\mathrm{C.I.}}/2t_h$.4 pages including 2 figures, article stylePhysics and Societytext