Excitation functions of 125Te(p, xn)-reactions from their respective thresholds up to 100 MeV with special reference to the production of 124I.

Excitation functions of the nuclear reactions 125Te(p, xn) (119,120m, 120g, 121,122,123,124,125)I were measured for the first time from their respective thresholds up to 100 MeV using the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 98.3% enriched 125Te on Ti-backing. In addition to experimental studies, excitation functions were calculated by the modified hybrid model code ALICE-IPPE. The experimental and theoretical data generally showed good agreement. From the measured cross section data, integral yields of (123,124,125)I were calculated. The energy range Ep 21 --> 15 MeV appears to be very suitable for the production of the medically interesting radionuclide 124I (T(1/2) = 4.18 d; I(beta)+ = 25%). The thick target yield of 124I amounts to 81 MBq/microA h and the level of 125I-impurity to 0.9%. The 125Te(p,2n)124I reaction gives 124I yield about four times higher than the commonly used 124Te(p,n)124I and 124Te(d,2n)124I reactions. The proposed production energy range is too high for small cyclotrons but large quantities of 124I can be produced with medium-sized commercial machines.