
U.S. Nuclear Regulatory Commission

Home

Who We Are

What We Do

Nuclear Reactors

Nuclear Materials

Radioactive Waste

Facility Info Finder

Public Involvement

Electronic Reading Room

Roentgen (R)

A unit of exposure to ionizing radiation. It is the amount of gamma or x-rays required to produce ions resulting in a charge of 0.000258 coulombs/kilogram of air under standard conditions. Named after Wilhelm Roentgen, the German scientist who discovered x-rays in 1895.