gamma rays may be used to kill pathogens in ground beef. one irradiation facility uses a 60co source that has an activity of 1.0×106ci. 60co undergoes beta decay and then gives off two gamma rays, at 1.17 and 1.33 mev; typically 30% of this gamma-ray energy is absorbed by the meat. the dose required to kill all pathogens present in the beef is 4000 gy.