THE HALF-LIFE OF CU-62

The half-life of the positron emitter (CU)-C-62 has been measured usin g 4 pi beta liquid scintillation (LS) spectrometry and counting in the National Institute of Standards and Technology (NIST) '4 pi'-gamma re -entrant ionization chamber (IC). A total of 12 independent LS measure ments and two independent IC measurements were made, all of which span ned two to four half-lives. Weighted nonlinear fits of the data result ed in half-lives of 9.68 min +/- 0.04 min and 9.673 min +/- 0.026 min (uncertainties are combined standard uncertainties) for the LS and IC data, respectively (a difference of only 0.07%). The weighted mean of these two values is 9.67 min +/- 0.03 min, which is shorter than the E NSDF-recommended value of 9.74 min +/- 0.02 min by 0.7%. Since this ra dionuclide is being investigated for use in positron emission tomograp hy (PET), this difference in the half-life has an important effect on the estimation of the amount of radioactivity administered to patients when decay corrections must be applied.