Which radiographic source is known to emit the most penetrating radiation?

The choice of cobalt-60 as the source that emits the most penetrating radiation is accurate due to its properties as a radionuclide. Cobalt-60 is a gamma emitter commonly used in radiography because of its high-energy gamma photons, which can penetrate dense materials and provide high-quality imaging.

The gamma radiation produced by cobalt-60 has a maximum energy of about 1.33 MeV, which contributes to its ability to penetrate thick sections of metals and other materials effectively. This makes it particularly useful in industrial settings for non-destructive testing applications, where clarity and depth of penetration of the radiographic images are critical for evaluating the integrity of components.

Additionally, while other radionuclides listed, such as cesium-137 and iridium-192, also emit gamma radiation, their energy levels are generally lower compared to cobalt-60. For instance, cesium-137 has a maximum energy of about 0.66 MeV, and iridium-192 emits gamma rays with energies ranging from 0.3 to 0.5 MeV, making them less penetrating compared to the radiation emitted by cobalt-60.

Thus, cobalt-60 is recognized as one of the most penetrating sources used in radiographic testing, which is