Roentgen (unit) Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. In 1928 it was the first international measurement quantity for ionising radiation to be defined for radiation protection, and was an easily replicated method of measuring air ionization directly by using an ion chamber. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays. Although relatively easy to measure, it had
David Roentgen David Roentgen David Roentgen (1743 in HerrnhaagFebruary 12, 1807), was a famous German cabinetmaker of the eighteenth century, famed throughout Europe for his marquetry and his secret drawers and mechanical fittings. His work embraces the late Rococo and the Neoclassical styles. In 1753 his father Abraham Roentgen, who had trained in London in the workshop of William Gomm, migrated to the Moravian settlement at Neuwied, near Coblenz, where he established a furniture factory. David learned his trade in his father's workshop, inherited the paternal business in 1772, and entered into partnership with the clockmaker Kintzing. By that time, the name