Production of ¹²³I by Bombarding a Antimony Target with α and ³He Particles

Abstract

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.