The shadow of the pencil is revealed because most light has enough energy to pass through the paper, but the denser pencil stops all the light.
The difference is that x-rays are invisible, so we need photographic film to "see" them for us.
Excess Xenon-135 is a radioactive isotope of xenon, produced as a fission product of uranium.
It has a half-life of about 9.2 hours and is the most powerful known neutron-absorbing nuclear poison (having a neutron absorption cross-section of 2 million barns).
Carbon is found in all living things, and a small percentage of this is carbon-14.
These instruments provide doctors with color images that show the shapes and details of internal organs.Fortunately, the designers had made provisions in the design to increase the reactor's reactivity (the number of neutrons per fission that go on to fission other atoms of nuclear fuel).Relatively high concentrations of radioactive xenon isotopes are also found emanating from nuclear reactors due to the release of this fission gas from cracked fuel rods or fissioning of uranium in cooling water. Because xenon is a tracer for two parent isotopes, Xe isotope ratios in meteorites are a powerful tool for studying the formation of the solar system.For example, just as doctors can label substances inside people's bodies, scientists can label substances that pass through plants, animals, or our world.This allows researchers to study such things as the paths that different types of air and water pollution take through the environment.For additional information, see the following topics on this page: Hospitals, doctors, and dentists use a variety of nuclear materials and procedures to diagnose, monitor, and treat a wide assortment of metabolic processes and medical conditions in humans.