Roentgen (unit)

The X-ray (abbreviated R) is an obsolete unit of measurement for the ion dose. It was named after the German physicist Wilhelm X Conrad.

Demarcation

The unit X was defined as the amount of radiation that is needed to (1 esu, charge unit in the cgs system) ( cc 1) to release positive and negative ions from an electrostatic unit with a volume of one cubic centimeter of air at standard conditions. In dry air, which is about the amount of radiation of 0.01 Gray.

The SI unit of radiation exposure is the coulomb per kilogram ( C kg -1):

Anders described a dose of 1 roentgen per cubic centimeter of air produces some 2 billion ion pairs.

Originally, the unit symbol r has been introduced for the X-ray. The definition has been established in 1928 in Stockholm in the policies of an International Commission and reformulated in 1953 to a meeting of the International Commission on Radiation Units and Measurement in Copenhagen.

Became mandatory in the European Union by Directive 80/181/EEC, the International System of Units ( SI). The sole use of the X-ray unit is in the commerce no longer permitted since 31 December 1985.