Positron emission intensities in the decay of⁶⁴Cu,⁷⁶Br and¹²⁴I

Abstract

The relatively long-lived positron emitters 64 Cu ( t 1/2 = 12.7 h), 76 Br ( t 1/2 = 16.2 h) and 124 I ( t 1/2 = 4.18 d) are finding increasing applications in positron emission tomography (PET). For precise determination of their positron emission intensities, each radionuclide was prepared via a charged particle induced reaction in a “no-carrier-added” form and with high radionuclidic purity. It was then subjected to γ -ray and X-ray spectroscopy as well as to anticoincidence beta and γγ -coincidence counting. The positron emission intensities measured were: 64 Cu (17.8 ± 0.4)%, 76 Br (58.2 ± 1.9)% and 124 I (22.0 ± 0.5)%. The intensity of the weak 1346 keV γ -ray emitted in the decay of 64 Cu was determined as (0.54 ± 0.03)%. Some implications of the precisely determined nuclear data are discussed.