Radioactive decay
Videos
Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay
Pierre and Marie Curie in their Paris laboratory, before 1907
Taking an X-ray image with early Crookes tube apparatus in 1896. The Crookes tube is visible in the centre. The standing man is viewing his hand with a fluoroscope screen; this was a common way of setting up the tube. No precautions against radiation exposure are being taken; its hazards were not known at the time.
Background radiation
Videos
Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.
Geiger counter displaying 0.17 μSv/h (1.5 mSv/a) under background radiation.
The weather station outside of the Atomic Testing Museum on a hot summer day. Displayed background gamma radiation level is 9.8 μR/h (0.82 mSv/a) This is very close to the world average background radiation of 0.87 mSv/a from cosmic and terrestrial sources.
Cloud chambers used by early researchers first detected cosmic rays and other background radiation. They can be used to visualize the background radiation
Displays showing ambient radiation fields of 0.120–0.130 μSv/h (1.05–1.14 mSv/a) in a nuclear power plant. This reading includes natural background from cosmic and terrestrial sources.