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Grimm, T. L.

Paper Title Page
TUPAS053 Beam Dynamics Studies for the Reacceleration of Low Energy RIBs at the NSCL 1769
  • X. Wu, G. Bollen, M. Doleans, T. L. Grimm, F. Marti, S. Schwarz, R. C. York, Q. Zhao
    NSCL, East Lansing, Michigan
  Funding: This work is supported by the U. S. Department of Energy

Rare Isotope Beams (RIBs) are created at the National Superconducting Cyclotron Laboratory (NSCL) by the in-flight particle fragmentation method. A novel system is proposed to stop the RIBS in a helium filled gas system followed by reacceleration that will provide opportunities for an experimental program ranging from low-energy Coulomb excitation to transfer reaction studies of astrophysical reactions. The beam from the gas stopper will first be brought into a Electron Beam Ion Trap (EBIT) charge breeder on a high voltage platform to increase its charge state and then accelerated initially up to about 3 MeV/u by a system consisting of an external multi-harmonic buncher and a radio frequency quadrupole (RFQ) followed a superconducting linac. The superconducting linac will use quarter-wave resonators with bopt of 0.047 and 0.085 for acceleration and superconducting solenoid magnets for transverse focusing. The paper will discuss the accelerator system design and present the end-to-end beam dynamics simulations.

TUPAS055 End-to-End Beam Dynamics Simulations of the ISF Driver Linac 1775
  • Q. Zhao, M. Doleans, T. L. Grimm, F. Marti, S. O. Schriber, X. Wu, R. C. York
    NSCL, East Lansing, Michigan
  A proposed Isotope Science Facility (ISF), a major upgrade from the Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory (NSCL), will provide the nuclear science community with world-class beams of rare isotopes. The ISF driver linac will consist of a front-end and three acceleration segments of superconducting cavities separated by two charge-stripping sections, and will be capable of delivering primary beams ranging from protons to uranium with variable energies of ≥200 MeV/nucleon. The results of end-to-end beam simulation studies including physical misalignments, dynamic rf amplitude and phase errors, and variations in the stripping foil thickness, will be performed to evaluate the driver linac overall performances and beam loss, even for the challenging case of the uranium beam with multiple charge states using the newly-developed RIAPMTQ/IMPACT codes. The paper will discuss ISF beam dynamics issues and present the end-to-end beam simulation results.  
WEPMS003 Design of Half-Reentrant SRF Cavities for Heavy Ion Linacs 2328
  • J. Popielarski, T. L. Grimm, W. Hartung, R. C. York
    NSCL, East Lansing, Michigan
  Funding: DOE #DE-FG02-06ER41411

The Spallation Neutron Source (Oak Ridge), the proposed 8 GeV Proton Driver (Fermilab), and the proposed Rare Isotope Accelerator use multicell elliptical SRF cavities to provide much of the accelerating voltage. This makes the elliptical cavity segment the most expensive part of the linac. A new type of accelerating structure called a half-reentrant elliptical cavity can potentially improve upon existing elliptical designs by reducing the cryogenic load by as much as 30% for the same accelerating voltage. Alternatively, with the same peak surface magnetic field as traditional elliptical cavities, it is anticipated that half-reentrant designs could operate at up to 25% higher accelerating gradient. With a half-reentrant shape, liquids can drain easily during chemical etching and high pressure rinsing, which allows standard multicell processing techniques to be used. A half-reentrant cavity for β = v/c = 1, suitable for the proposed ILC, has been designed and fabricated, with RF tests in progress*. In this paper, we present electromagnetic designs for three half-reentrant cell shapes suitable for an ion or proton linac (β = 0.47, 0.61 and 0.81, f = 805 or 1300 MHz).

* M. Meidlinger et al., in Proc. XXIII Int. Linac Conf., Knoxville, TN, Aug 2006