The world's first dedicated source of synchrotron radiation, an electron storage ring named Tantalus, has been designated a historic site by the American Physical Society.

The designation recognizes the pioneering use of synchrotron light for scientific research at the University of Wisconsin-Madison. Synchrotron light, which extends from the X-ray to the infrared regions of the electromagnetic spectrum, occurs when electrons, moving at near light speed, are forced to change direction through the influence of a powerful magnetic field.