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
The Invention of the Jewish People The Invention of the Jewish People The Invention of the Jewish People (, literally "When and How Was the Jewish People Invented?") is a study of the historiography of the Jewish people by Shlomo Sand, Professor of History at Tel Aviv University. It has generated a heated controversy. The book was in the best-seller list in Israel for nineteen weeks. An English translation of the book was published by Verso Books in October 2009. The book has also been translated into German, Italian, Spanish, Portuguese, Arabic, French and Russian, and as of late 2009 further translations were underway. "The Invention