Radioactive source
radionuclide which emits ionizing radiation
A radioactive source is a known quantity of a radionuclide which emits ionizing radiation, typically one or more of the radiation types gamma rays, alpha particles, beta particles, and neutron radiation.
Sources can be used for irradiation, where the radiation performs a significant ionising function on a target material, or as a radiation metrology source, which is used for the calibration of radiometric process and radiation protection instrumentation. They are also used for industrial process measurements, such as thickness gauging in the paper and steel industries. Sources can be sealed in a container (highly penetrating radiation) or deposited on a surface (weakly penetrating radiation), or they can be in a fluid.
As an irradiation source they are used in medicine for radiation therapy and in industry for such as industrial radiography, food irradiation, sterilization, vermin disinfestation, and irradiation crosslinking of PVC.
Radionuclides are chosen according to the type and character of the radiation they emit, intensity of emission, and the half-life of their decay. Common source radionuclides include cobalt-60, iridium-192, and strontium-90. The SI measurement quantity of source activity is the Becquerel, though the historical unit Curies is still in partial use, such as in the US, despite their NIST strongly advising the use of the SI unit. The SI unit for health purposes is mandatory in the EU.
An irradiation source typically lasts for between 5 and 15 years before its activity drops below useful levels. However sources with long half-life radionuclides when used as calibration sources can be used for much longer.
Sealed sources
Many radioactive sources are sealed, meaning they are permanently either completely contained in a capsule or firmly bonded solid to a surface.
The public source identifies “Radioactive source” as radionuclide which emits ionizing radiation. This brief keeps that definition visible, then builds a research path around Radioactive, source and radionuclide.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Radioactive source”, the useful work is to connect “radionuclide which emits ionizing radiation” to the records capable of establishing context and consequence.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated May 22, 2026. The linked authority identifier is Q2115507. None of the 0 selected statements returned an explicit reference.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Radioactive source”, its source revision and the description used here.
- Expand the search: follow Radioactive source primary sources, Radioactive source archive and Radioactive research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Radioactive source”?
- Which cited source is closest to the event, object or claim?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Radioactive source” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.