The K1200 Cyclotron

One of the high-voltage accelerating electrodes—dee— before its installation in the K1200 cyclotron. more

The K1200 cyclotron is the larger of the NSCL's two superconducting cyclotrons and provides a higher-energy beam. Like the K500, it accelerates ions of any element in the periodic table—through uranium—to more than half the speed of light. The K1200 was used for nuclear science research at the NSCL from its completion in 1989 until 1999, the beginning of the construction to couple the two cyclotrons. The K1200 is now the high-energy half of the two coupled cyclotrons; acceleration begins in the K500, and the beam from the K500 is injected into the K1200 for further acceleration.

The K1200 is 14 feet, 7 inches in diameter, and the magnet is 9 feet, 7 inches tall. Its beam energy can be selected within the range from 20 MeV per nucleon to 200 MeV per nucleon (about 38,000 miles per second to 105,000 miles per second). The K1200 can run independently, but it is usually coupled to the K500 cyclotron. Coupling the two cyclotrons allows them to accelerate more intense beams of all the elements, and it also allows them to accelerate higher-energy beams of the heavier elements. For example, uranium can be accelerated to 90 MeV/nucleon, while the limit with the K1200 alone is about 25 MeV/nucleon.

In the coupled system, the K500 cyclotron accelerates ions of low charge state (the ion source can provide high intensities of low-charge ions) to an energy suitable for injection into the K1200 (less than 20 MeV/nucleon). When injected into the K1200, the ions pass through a thin foil and lose many electrons, typically emerging with a charge 2.5 times larger. The accelerating high voltage, acting on this higher charge, can boost the ions to a higher energy. The coupling of the two cyclotrons greatly increases the beam intensity and makes it possible to explore very rare exotic isotopes.

In stand-alone operation, ions from the ion source are injected directly into the K1200 for normal acceleration.