FRIB, East Lansing, Michigan, USA
BNL, Upton, Long Island, New York, USA
ANL, Argonne, Illinois, USA
The Facility for Rare Isotope Beams (FRIB) at Michigan State University is building a heavy ion linac to produce rare isotopes by the fragmentation method. The linac will accelerate ions up to U to energies above 200 MeV/u with beam powers up to 400 kW. At energies between 16 and 20 MeV/u the ions will be stripped to higher charge states to increase the energy gain downstream in the linac. The main challenges in the stripper design are due to the high power deposited by the ions in the stripping media (~ 30 MW/cm3) and radiation damage if solids are used. For that reason self-recovering stripper media must be used. The baseline stripper choice is a high-velocity, thin film of liquid lithium with an alternative option of a helium gas stripper. We present in this paper the status of the R&D and construction of the final stripper. Extensive experimental work has been performed on both options.
BNL, Upton, Long Island, New York, USA
The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.
BNL, Upton, Long Island, New York, USA
Since 2012 gold and all other ions for the RHIC injector chain have been provided by an Electron Beam Ion Source (EBIS). The source is followed by an RFQ, a short Linac, and a 30 m transport line. These components replace the Tandem van de Graaff and associated 840 m transfer line. They provide ions at 2 MeV per nucleon (kinetic energy) for injection into the AGS Booster. The setup and operation of Booster and AGS with various ions from the new source are reviewed.
BNL, Upton, Long Island, New York, USA
ESRF, Grenoble, France
In the Relativistic Heavy Ion Collider (RHIC) 100 GeV polarized proton run in 2015[1], two electron lenses [2] were used for the first time to partially compensate for the head-on beam-beam effect. Here, we describe the design of the current electron lens, detailing the hardware modifications made after the 2014 commissioning run with heavy ions. A new electron gun with 15-mm diameter cathode is characterized. The electron beam transverse profile was measured using a YAG screen and fitted with a Gaussian distribution. During operation, the overlap of the electron and proton beams was achieved using the electron backscattering detector in conjunction with an automated orbit control program.