Grimm T.L.

Paper	Title	Page
MO304	MSU Re-accelerator - the re-acceleration of low energy RIBS at the NSCL	28
	X. Wu, G. Bollen, M. Doleans, T. L. Grimm, W. Hartung, F. Marti, S. Schwarz, R. C. York, Q. Zhao MSU/NSCL
	The in-flight Particle Fragmentation (PF) method for producing Rare Isotope Beams (RIBs) has been used at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) since 1989. The upgraded Coupled Cyclotron Facility (CCF) has been in operation for nuclear physics research since 2001 with the experimental program largely utilizing PF produced RIBs. To provide new research opportunities for an experimental program ranging from low-energy coulomb excitation to transfer reaction studies of astrophysical reactions, a novel system is proposed at the NSCL to first stop the high energy RIBs in a helium filled gas system, then increase their charge state with an Electron Beam Ion Trap (EBIT) charge breeder, and finally re-accelerate them to about 3 MeV/u using a radio frequency quadrupole (RFQ) followed by a superconducting linac. The superconducting linac will use quarter-wave resonators with optimum beta (beta_opt = beta value for which the cavity delivers the maximum accelerating voltage) of 0.041 and 0.085 for acceleration, and superconducting solenoid magnets for transverse focusing. An upgrade option to achieve a beam energy up to ~12 MeV/u with additional accelerating cryomodules is also possible. This paper will discuss the accelerator system design and beam dynamics simulations for the MSU Re-accelerator project.
	Slides(PDF)
WE102	Thermal Design Studies of Niobium SRF Cavities	362
	A. Aizaz, N. T. Wright Michigan State University T. L. Grimm Niowave Inc
	The thermal response of niobium cavities at liquid helium temperatures remains an active area of research in order to increase the accelerating gradients of future accelerators. The effects of plastic deformation on the thermal conductivity in the phonon transmission regime, as well as on the Kapitza conductance, have been studied. The study reveals absence of the phonon peak after deformation beyond the elastic limit of niobium, with an almost 80% reduction in the thermal conductivity of niobium at 2 K. Deformation also reduced the Kapitza conductance. Low temperature annealing did not recover the phonon peak that was measured before plastic deformation. Annealing at the higher temperatures used during titanification, similar to that carried out on SRF cavities, recovered the lost phonon peak and increased the Kapitza conductance by 300%. Thermal conductivity measurements of single and bi-crystal niobium samples are also reported in this ongoing research.
	Slides(PDF)