Standardization of ⁶⁷Cu and calibration of the ionization chamber. Impurities and decay scheme problems

This paper describes the standardization of ⁶⁷Cu by the 4πβ(PC)-γ coincidence method, and the calibration of ionization chamber. The difficulties were. (i) One of the excited levels of ⁶⁷Zn has a half life of 9.10μs. (ii) A recent publication reconsiders the decay scheme parameters. (iii) The solution had a significant content of impurities. The conclusions were that the result of absolute standardization is less influenced by the decay scheme parameters and impurities than the measurements by ionization chamber.