Final answer:
Gamma rays or x-rays, which are forms of ionizing radiation, are used for beef patty irradiation to kill bacteria without making the food radioactive.
Step-by-step explanation:
For a beef patty, the type of radiation used is ionizing radiation, specifically gamma rays or x-rays. These forms of radiation can disrupt the DNA-RNA-protein synthesis cycle of bacteria, such as salmonella and campylobacter, that may be present on raw meat. Cobalt-60 and cesium-137 are commonly used as radiation sources for food irradiation, as they emit gamma rays that are effective in killing bacteria without making the food itself radioactive.