PAC07 - List of Authors (Wu, X.)

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Wu, X.

Paper	Title	Page
TUPAS050	Determination of Component Activation and Radiation Environment in the Second Stripping Region of a High-Power Heavy-Ion Linear Accelerator	1760
	I. Baek, R. M. Ronningen, X. Wu, A. Zeller NSCL, East Lansing, Michigan R. Remec ORNL, Oak Ridge, Tennessee
	Funding: U. S. Department of Energy under Grant No. DE-FG02-04ER41313 In supporting pre-conceptual research and development of the Rare-Isotope Accelerator facility or similar next-generation exotic beam facilities, one critical focus area is to estimate the level of activation and radiation in the linear accelerator second stripping region and to determine if remote handling is necessary in this area. A basic geometric layout of the second stripping region having beamline magnets, beam pipes and boxes, a stripper foil, beam slits, and surrounding concrete shielding was constructed for Monte Carlo simulations. Beam characteristics were provided within the stripping region based on this layout. Radiation fields, radioactive inventories, levels of activation, heat loads on surrounding components, and prompt and delayed radiation dose rates were simulated using Monte-Carlo radiation transport code PHITS. Preliminary results from simulations using a simplified geometry show that remote handling of foils and slits will be necessary. Simulations using a realistic geometry are underway and the results will be presented.
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.
TUPAS054	Design Studies of the Reaccelerator RFQ at NSCL	1772
	Q. Zhao, V. Andreev, F. Marti, S. O. Schriber, X. Wu, R. C. York NSCL, East Lansing, Michigan
	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 a reacceleration that will provide opportunities for an experimental program ranging from low-energy Coulomb excitation and 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 planned RFQ will operate in the cw mode at a frequency of 80.5MHz to accelerate ion beams from ~12 keV/u to ≥ 300keV/u. An external multi-harmonic buncher will be used to produce a small longitudinal emittance beam out of the RFQ. In this paper, we will describe the design of the RFQ, present the beam dynamics simulation results, and also discuss the impact of the external buncher harmonics on the output beam properties.
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.
THPAS039	Status Report on the NSCL RF Fragment Separator	3585
	M. Doleans, V. Andreev, B. Arend, D. Bazin, A. Becerril Reyes, R. Fontus, P. Glennon, D. Gorelov, P. F. Mantica, J. Ottarson, H. Schatz, B. Sherrill, J. Stoker, O. Tarasov, J. J. Vincent, J. Wagner, X. Wu, A. Zeller NSCL, East Lansing, Michigan
	The RF Fragment Separator (RFFS) proposed in* is now under construction and should be operational by May 2007. The RFFS is an additional purification system for secondary beams at the National Superconducting Cyclotron Laboratory after the existing A1900 fragment separator and will primarily be used to purify beams of rare neutron deficient isotopes. The RFFS uses a transverse electric field of an rf kicker to separate unwanted particles from the desired ion beam, a pi/2 phase advance cell to rotate the beam in phase space before the beam reaches a collimating aperture for purification and a final pi phase advance cell to transport the desired beam to the experiment. The final design for the rf kicker and the focusing system is presented and a status report on the building and commissioning effort is given. * D. Gorelov, V. Andreev, D. Bazin, M. Doleans, T. Grimm, F. Marti, J. Vincent and X. Wu, "RF-Kicker System for Secondary Beams at NSCL/MSU" PAC2005, Knoxville, Tennessee, 16th-20th, May 2005
THPAS051	The RIAPMTQ/IMPACT Beam-Dynamics Simulation Package	3606
	T. P. Wangler, J. H. Billen, R. W. Garnett LANL, Los Alamos, New Mexico V. N. Aseev, B. Mustapha, P. N. Ostroumov ANL, Argonne, Illinois K. R. Crandall TechSource, Santa Fe, New Mexico M. Doleans, D. Gorelov, X. Wu, R. C. York, Q. Zhao NSCL, East Lansing, Michigan J. Qiang, R. D. Ryne LBNL, Berkeley, California
	Funding: This work is supported by the U. S. Department of Energy, DOE contract number:W-7405-ENG-36 RIAPMTQ/IMPACT is a pair of linked beam-dynamics simulation codes that have been developed for end-to-end computer simulations of multiple-charge state heavy-ion linacs for future exotic-beam facilities. The simulations can extend from the low-energy beam transport after the ECR source to the end of the linac. The work has been performed by a collaboration including LANL, LBNL, ANL, MSU, and TechSource. The code RIAPMTQ simulates the linac front end including the LEBT, RFQ, and MEBT, and the code IMPACT simulates the main superconducting linac. The codes have been benchmarked for rms beam properties against previously existing codes at ANL and MSU. The codes allow high-statistics runs on parallel supercomputing platforms, such as NERSC at LBNL, as well as runs on desktop PC computers for low-statistics design work. We will show results from 10-million-particle simulations of RIA designs by ANL and MSU, carried out at the NERSC facility. These simulation codes will allow evaluations of candidate designs with respect to beam-dynamics performance including beam losses.
FRXAB03	Design, Construction and Commissioning of the SuSI ECR	3766
	P. A. Zavodszky, B. Arend, D. Cole, J. DeKamp, G. Machicoane, F. Marti, P. S. Miller, J. Moskalik, W. Nurnberger, J. Ottarson, J. J. Vincent, X. Wu, A. Zeller NSCL, East Lansing, Michigan
	Funding: This work was supported by the National Science Foundation under grant PHY-0110253. An ECR ion source was constructed at the NSCL/MSU to replace the existing SC-ECRIS. This ECRIS operates at 18+14.5 GHz microwave frequencies and it is planned an upgrade to 24-28 GHz in the second phase of commissioning. A superconducting hexapole coil produces the radial magnetic field; the axial trapping is produced with six superconducting solenoids enclosed in an iron yoke to allow tuning the distance between the plasma electrode and resonant zone in the plasma. The plasma chamber of the ion source can be biased at +30 kV, the beam line at -30 kV. The voltage of the beam line vacuum pipe must be kept constant from the ECRIS to the point of full separation of the beam charge states near the image plane of the analyzing magnet. At this point, an insulator is used to increase the voltage up to zero value. The kinetic energy of the beam is decreased to 30 kV per unit charge after this point, as required for the injection in the Coupled Cyclotron Facility. To decrease the beam divergence, a focusing solenoid is installed after the vacuum pipe break. We report the details of the design, construction and initial commissioning results of this new ECIS.
	Slides