The Alternating Gradient Synchrotron was built on the innovative concept of the alternating gradient, or strong-focusing principle, developed by Brookhaven physicists. This new concept in accelerator design allowed scientists to accelerate protons to energies that were previously unachievable. The AGS became the world's premiere accelerator when it reached its design energy of 33 billion electron volts (GeV) on July 29, 1960.