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.