This requires moving the existing Linac up . The option of a LINAC is currently preferred. Both beams are then further accelerated to 9 GeV in a common booster linac. The electron is readmitted to the linac after each revolution. This would require upgrades to the entire linac/pre-injector/injector chain, including the SPS. The bunching process is done at the start of the linac, using several 'bunching' cavities. Beta radiation from linac accelerators is far more energetic and penetrating than natural beta radiation. The linac can accelerate a beam once every second. With a Linac the gantry moves in space to change the delivery angle. Today, both Gamma Knife and Linac radiosurgery programs are commercially available worldwide. The longest linac in the world is the Stanford Linear Accelerator, SLAC, which is long. December 1, 1968, saw the breaking of ground for the linear accelerator (linac). In a linac, the target is simply fitted to the end of the accelerator. The versatility of LINAC is a potential advantage over cobalt therapy as a treatment tool. The LINAC produces a reliable, flexible and accurate radiation beam.