Rutherford (unit)

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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 2.703 × 10−5 curie.

The unit was introduced in 1946.[1] It was named after British/New Zealand physicist and Nobel laureate Lord Ernest Rutherford (Nobel Prize in 1908),[2] who was an early leader in the study of atomic nucleus disintegrations. After the becquerel was introduced in 1975[3] as the SI unit for activity, the rutherford became obsolete, and it is no longer commonly used.

Radiation related quantities[edit]

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

Radiation related quantities view  talk  edit
Quantity Name Symbol Unit Year SI Quantity
Activity (A) curie Ci 3.7×1010 s−1 1953 3.7×1010 Bq
becquerel Bq s−1 1974 SI
rutherford Rd 106s−1 1946 1,000,000 Bq
Exposure (X) röntgen R esu / 0.001293g of air 1928 2.58×10−4 C/kg
Fluence (Φ) (reciprocal area) m−2 1962 SI
Absorbed dose (D) Erg erg·g−1 1950 1.0×10−4 Gy
rad rad 100 erg·g−1 1953 0.010 Gy
gray Gy J·kg−1 1974 SI
Dose equivalent (H) röntgen equivalent man rem 100 erg·g−1 1971 0.010 Sv
sievert Sv J·kg−1×WR 1977 SI


  1. ^ Lind, SC (1946), "New units for the measurement of radioactivity", Science, 103 (2687): 761–762, PMID 17836457, doi:10.1126/science.103.2687.761-a. 
  2. ^ "The Nobel Prize in Chemistry 1908". 
  3. ^ Harder, D (1976), "[The new radiologic units of measurement gray and becquerel (author's translation from the German original)]", Röntgen-Blätter, 29 (1): 49–52, PMID 1251122.