Results are presented concerning a calibration experiment of the CsI(Tl) cr
ystals of the GARFIELD apparatus. Experimental data were collected in a wid
e range of energy and charge (40 less than or equal to E(MeV) less than or
equal to 230, 3 less than or equal to Z less than or equal to 28) with part
icular care to the region of low energies and light ions. Analytical expres
sions in recent publications, linking the output response of CsI(Tl) crysta
ls to the energy and charge of the detected ion, are revised. An improved f
ormula is suggested, which takes into account new physical constraints.