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
Sanford Burnham Prebys Medical Discovery Institute careers in basic and translational research through a curriculum of focused, multi-disciplinary instruction. In 2015, SBP achieved accreditation with the Western Association of Schools and Colleges. SBP also employs postdoctoral fellows; there are typically around 250 postdocs training at SBP at any time. The endowment was recorded at as low as $15.2 million, a 13 percent drop from nearly $17.5 million in February 2008, due largely to losses on investments. Its endowment stood at $22.5 million as of Dec. 31, 2009. Sanford Burnham Prebys Medical Discovery Institute Sanford Burnham Prebys Medical Discovery Institute (SBP) is a non-profit medical research institute