The rutherford (symbol Rd) is a non-SI unit of

radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

. It is defined as the activity of a quantity of radioactive material in which one million nuclei decay per

second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ea ...

. It is therefore equivalent to one

megabecquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relat ...

, and one becquerel equals one microrutherford. One rutherford is equivalent to 2.703 × 10⁻⁵

curie In computing, a CURIE (or ''Compact URI'') defines a generic, abbreviated syntax for expressing Uniform Resource Identifiers (URIs). It is an abbreviated URI expressed in a compact syntax, and may be found in both XML and non-XML grammars. A CURI ...

. The unit was introduced in 1946. It was named after British/New Zealand physicist and Nobel laureate

Lord Ernest Rutherford Ernest Rutherford, 1st Baron Rutherford of Nelson, (30 August 1871 – 19 October 1937) was a New Zealand physicist who came to be known as the father of nuclear physics. '' Encyclopædia Britannica'' considers him to be the greate ...

(Nobel Prize in 1908), who was an early leader in the study of

atomic nucleus The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron ...

disintegrations. After the becquerel was introduced in 1975 as the SI unit for activity, the rutherford became obsolete, and it is no longer commonly used.

Radiation related quantities

The following table shows radiation quantities in SI and non-SI units:

References

Units of radioactivity {{Measurement-stub