Positron emission intensity in the decay of I-120g

The beta(+)/EC ratio in the decay of I-120g (T-1/2 = 1.35 h), i.e. the beta (+) emission intensity, was measured for the first time using a high purity I-120g source, which was produced by irradiation of 99.0% enriched Te-120 with 15 MeV protons, followed by a chemical separation of radioiodine. Both gamma-ray and X-ray spectroscopy were applied. In the former case a compar ison of the intensity of the annihilation radiation with that of the 1523 k eV gamma-ray of I-120g was done and in the latter case with that of the K-a lpha or K-beta X-ray of the daughter tellurium. Corrections for very small contributions of I-121 and I-120m impurities were evaluated. The literature values for the Ibeta+ of I-120g range between 39 and 81%. Our measurements lead to a value of 56 +/- 3 %.