A Multi-Accelerator System for Heavy Ions

The accelerators for the new National Heavy-Ion Laboratory (NHL) being planned at Oak Ridge will provide beams of all ions from helium to uranium with energies ranging from 100 MeV/u for light ions to 10 MeV/u for the heaviest ions accelerated. The heart of the proposed accelerator system is a large 4 sector isochronous cyclotron of the separated sector type with an energy rating of 440 q2/A MeV. Ions are to be injected into the large cyclotron from either a large tandem electrostatic acclerator or from the Oak Ridge Isochronous Cyclotron (ORIC). The ORIC will generally suffice as the injector up to the mass 160-180 range, beyond which use of the tandem is necessary. Beam intensities will range from 1013 ions/sec for 100 MeV/u oxygen to ~2 × 1012/sec for 10 MeV/u uranium ions. The beam emittance is expected to be less than 10 mm-mrad and the energy spread less than 0.1%. The large cyclotron uses auxiliary RF accelerating cavities operating at twice the main RF frequency to flattop the effective accelerating voltage waveform to thus increase the phase acceptance and reduce the energy spread of the beams.