http://www.sciencedaily.com/releases/2011/09/110919113836.htmScienceDaily (Sep. 19, 2011) — The brightest gamma ray beam ever created -- more than a thousand billion times more brilliant than the sun -- has been produced in research led at the University of Strathclyde, and could open up new possibilities for medicine.
ON EDIT TO ADD:
"In nature, if you accelerate charged particles, such as electrons, they radiate. We trapped particles in a cavity of ions trailing an intense laser pulse and accelerated these to high energies. Electrons in this cavity also interact with the laser and pick up energy from it and oscillate wildly -- much like a child being pushed on a swing. The large swinging motion and the high energy of the electrons allow a huge increase in the photon energy to produce gamma rays. This enabled the gamma ray photons to outshine any other earthbound source.
"The accelerator we use is a new type called a laser-plasma wakefield accelerator which uses high power lasers and ionised gas to accelerate charged particles to very high energies -- thus shrinking a conventional accelerator, which is 100m long, to one which fits in the palm of your hand."
The peak brilliance of the gamma rays was measured to be greater than 1023 photons per second, per square milliradian, per square millimetre, per 0.1% bandwidth.