Radioactive source

A radioactive source is a known quantity of a <a href="/facts/Radionuclide/5WpCfbdq">radionuclide</a> which emits <a href="/facts/Ionizing_radiation/vw0d9GaT">ionizing radiation</a>, typically one or more of the radiation types <a href="/facts/Gamma_ray/5Drf913J">gamma rays</a>, <a href="/facts/Alpha_particle/dzNMs9WP">alpha particles</a>, <a href="/facts/Beta_particle/x8b3ttLn">beta particles</a>, and <a href="/facts/Neutron_radiation/LVJhCcwL">neutron radiation</a>.
Sources can be used for <a href="/facts/Irradiation/fHW0QNAa">irradiation</a>, where the radiation performs a significant ionising function on a target material, or as a radiation <a href="/facts/Metrology/HC0MmLdb">metrology</a> source, which is used for the calibration of radiometric process and <a href="/facts/Radiation_protection/5LaNNgXe">radiation protection</a> 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 <a href="/facts/Radiation_therapy/j60q5EC6">radiation therapy</a> and in industry for such as <a href="/facts/Industrial_radiography/q9cEdMFP">industrial radiography</a>, <a href="/facts/Food_irradiation/CNS4ooTG">food irradiation</a>, <a href="/facts/Sterilization_(microbiology)/ajVXFl7a">sterilization</a>, <a href="/facts/Vermin/S9G9NPdy">vermin</a> disinfestation, and <a href="/facts/Cross-linked_polyethylene/ayxYuITl">irradiation crosslinking</a> of PVC.
Radionuclides are chosen according to the type and character of the radiation they emit, intensity of emission, and the <a href="/facts/Half-life/kGVH8BAB">half-life</a> of their decay. Common source radionuclides include <a href="/facts/Cobalt-60/hjDPVA8M">cobalt-60</a>, <a href="/facts/Iridium-192/F1zVVPRq">iridium-192</a>, and <a href="/facts/Strontium-90/VJNoC5eR">strontium-90</a>. The <a href="/facts/SI/NShmfzlD">SI</a> measurement quantity of source <a href="/facts/Radioactive_decay/Ya6FVjt4">activity</a> is the <a href="/facts/Becquerel/4C3yrsqp">Becquerel</a>, though the historical unit <a href="/facts/Curie_(unit)/LeS60aVv">Curies</a> is still in partial use, such as in the US, despite their <a href="/facts/National_Institute_of_Standards_and_Technology/gr9Fnh85">NIST</a> strongly advising the use of the SI unit. The SI unit for health purposes is mandatory in the <a href="/facts/EU/6GYcR8qM">EU</a>.
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 utilised as calibration sources can be used for much longer.

Radioactive source open-in-new

Radioactive source