Roentgen (R) 9 or röntgen
Roentgen (R) 9 or röntgen :
: A non-metric unit used to measure the ionizing ability of radiation. Radiation often ionizes atoms it strikes, stripping one or more electrons from them. The biological effects of radiation are caused in large part by excessive ionization within living cells, so it is important to measure this ionizing ability of radiation. For x-rays and gamma rays, this is often done by measuring the electric charge released when air is ionized by the radiation. The roentgen is an old unit used for this purpose; one roentgen equals a charge release rate of 258 microcoulombs per kilogram of air. The unit is named for one of the early investigators of radioactivity, the German physicist Wilhelm Konrad Röntgen (1845-1923). In English it is usually pronounced "rent-gen" with a hard g sound; sometimes the soft g ("rent-jen") is used
