rutherford (unit)

{{Short description|Obsolete unit of radioactivity}}

{{Infobox Unit

| name = rutherford

| image =

| caption =

| standard =

| quantity = Activity

| symbol = Rd

| namedafter = Lord Ernest Rutherford

| units1 = curie

| inunits1 = {{val|2.703|e=-5|u=Ci}}

| units2 = SI derived units

| inunits2 = {{val|1|u=MBq}}

| units3 = SI base units

| inunits3 = 10⁶ s⁻¹

}}

The rutherford (symbol Rd) is a non-SI unit of radioactive decay. It is defined as the activity of a quantity of radioactive material in which one million nuclei decay per second. It is therefore equivalent to one megabecquerel, and one becquerel equals one microrutherford. One rutherford is equivalent to {{val|2.|end={{overline|702}}|e=-5}} curie, or {{val|37000}} rutherfords for one curie.

The unit was introduced in 1946.{{Citation |last=Lind |first=SC |year=1946 |title=New units for the measurement of radioactivity |journal=Science |volume=103 |issue=2687 |pages=761–762 |pmid=17836457 |doi= 10.1126/science.103.2687.761-a|postscript=.|bibcode=1946Sci...103..761L |s2cid=5343688 }} It was named after British/New Zealand physicist and Nobel laureate Lord Ernest Rutherford (Nobel Prize in 1908),{{Cite web|url = http://www.nobel.se/chemistry/laureates/1908/|title = The Nobel Prize in Chemistry 1908}} who was an early leader in the study of atomic nucleus disintegrations. After the becquerel was introduced in 1975{{Citation |last=Harder |first=D |year=1976 |title=[The new radiologic units of measurement gray and becquerel (author's translation from the German original)] |journal=Röntgen-Blätter |volume=29 |issue=1 |pages=49–52 |pmid=1251122 |postscript=.}} as the SI unit for activity, the rutherford became obsolete, and it is no longer commonly used.