Curie

The curie (symbol Ci) is a non-SI unit of radioactivity originally defined in 1910. According to a notice in Nature at the time, it was named in honour of Pierre Curie, but was considered at least by some to be in honour of Marie Curie as well. The curie (symbol Ci) is a non-SI unit of radioactivity originally defined in 1910. According to a notice in Nature at the time, it was named in honour of Pierre Curie, but was considered at least by some to be in honour of Marie Curie as well. It was originally defined as 'the quantity or mass of radium emanation in equilibrium with one gram of radium (element)' but is currently defined as 1 Ci = 3.7×1010 decays per second after more accurate measurements of the activity of 226Ra (which has a specific activity of 3.66×1010 Bq/g). In 1975 the General Conference on Weights and Measures gave the becquerel (Bq), defined as one nuclear decay per second, official status as the SI unit of activity. Therefore: