Radiation Sign

The international radiation sign (trefoil) first appeared in 1946, at the University of California, Berkeley Radiation Laboratory. At the time, it was rendered as magenta, and was set on a blue background. The modern adaptation is black against a yellow background, and it is drawn with a central circle of radiuss R, an centralized radius of 1.5R and an external radius of 5R for the blades, which are afar from each other by 60В°.