1976 Volume 25 Issue 6 Pages 315-322
To find out the possibility producing practical amount of 123I for medical use, comparative studies on α and 3He bombardment on natural antimony up to 40 MeV were carried out by stacked foil technique.
The excitation curves and thick-target yield curves were determined for the formation of 123I, and other by-produced nuclides such as 121I, 124I and 125I. In the case of the 3He bombardment, the maximum cross section for the formation of 123I was found to be 475 mb at 30 MeV 3He particles. After 21 hr cooling, the yield of 123I was 180μCi/μAh and the 121I/123I ratio was found to be 4.1%, which was fairly large impurity for medical use. In the case of a bombardment, the maximum cross sections for the formation of 123I, 124I and 125I were found to be 410 mb at 24.5 MeV, 370 mb at 35 MeV and 300 mb at 24 MeV α particles, respectively. These three nuclides were produced with yield of 174, 1.2 and 1.4μCi/μAh at 24.5 MeV a particles. The 124I/123I ratio was found to be 0.69%, which was much improved with those reported in literature.
123I can be separated by distillation from dissolved solution of bombarded antimony target with radiochemical yield of 81.1%. It may be said that 24.5 MeV α particles bombardment on natural antimony was superior in giving useful quantities of 123I with reasonable high yield of 174μCi/μAh and only accompanied with smallest quantities of 124I at the end of bombardment.