Sum-peak method with two NaI(Tl) crystals: 68(Ge+Ga) standardization

A 68 (Ge+Ga) commercial solution has been standardized in LNMRI in Brazil, by sum-peak method, in which a 3”x3” NaI(Tl) gamma-ray detector is positioned at the top of a well-type 5”x5” NaI(Tl) gamma-ray detector, resulting in a set up approximately  4 p geometry. In this work the known germanium volatility was tested using three dried sources and three liquid sources in the sum-peak method measurements and the activity results showed a standard deviation of 0.41%. The activities were compared with another primary method: 4 pb-g live-timed anti-coincidence counting. The two methods gave activity concentration values with differences from the certified value of +0.8 % (anticoincidence method) and -3.4% (sum-peak method).