The ultraviolet free electron laser (FEL) at Duke University is being stretched technically in two directions: An upgrade to the laser-based High Intensity Gamma-ray Source (HIγS, pronounced “higgs”) promises to deliver more flux, higher energy, and circular polarization; and, at lower energies, a team of Duke physicists has coaxed the laser to produce soft x rays.
In the HIγS, lased light from one bunch of electrons in the FEL is back-scattered from the next bunch. The facility’s breakthrough “is the use of intracavity power to boost the HIγS intensity by up to three orders of magnitude,” says Vladimir Litvinenko, associate director for light sources at the Duke Free Electron Laser Laboratory (DFELL). Even without the upgrade, adds Norbert Pietralla of the University of Cologne in Germany, the HIγS is unique. “There is no other facility in the world with the intensity, plus...
