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Large scale beam dynamics simulations are important to support the design and operations of an accelerator. The beam dynamics code TRACK, originally developed at Argonne National Laboratory (ANL) has become a general beam dynamics code for hadron linacs and has found wide applications worldwide. In order to combine the unique features of TRACK with large scale and fast parallel computing we have recently developed parallel version of the code: PTRACK It has been successfully benchmarked on different platforms: BG/L and Jazz at ANL, Iceberg at ARSC and Seaborg at NERSC. Large scale end-to- end simulations of the FNAL proton driver has been performed, where 100 millions particles were tracked. The actual parallel version has the potential of simulating 109 particles on 10 racks with 20,480 processors of BG/L at ANL, which will be available in 2008. This paper focus on efficient parallelization method been used in PTRACK.

A suite of nuclear and atomic physics codes for computing a variety of quantities relevant for heavy-ions over a wide energy range passing through material were implemented in the DA-based beam optics code COSY Infinity. As extensions to COSY we also developed a limited fission model, map computation for beam-material interactions, and a hybrid map-Monte-Carlo mode that allows relatively fast and accurate fragment separator design, end-to-end modeling and simulations, and performance optimization. Some results are briefly mentioned; details will be published elsewhere.

The Office of Science of the Department of Energy is currently considering options for an advanced radioactive beam facility in the U.S which is a reduced scale version of the Rare Isotope Accelerator (RIA) project [1,2]. This facility will have unique capabilities compared with others both existing and planned elsewhere. As envisioned at ANL, the facility, called the Advanced Exotic Beam Laboratory (AEBL), would consist of a heavy-ion driver linac, a post-accelerator and experimental areas. Secondary beams of rare isotopes will be available as high quality reaccelerated or stopped beams from a gas catcher and high power ISOL targets, as well as, high energy beams following in-flight fragmentation or fission of heavy ions. The proposed design of the AEBL driver linac is a cw, fully superconducting, 833 MV linac capable of accelerating uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. An extensive research and development effort has resolved many technical issues related to the construction of the driver linac and other systems required for AEBL. This paper presents the status of planning, some options for such a facility, as well as, progress in related R&D.

The Advanced Exotic Beam Laboratory (AEBL) being developed at ANL consists of an 833 MV heavy-ion driver linac capable of producing uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. We have designed all accelerator components including a two charge state LEBT, an RFQ, a MEBT, a superconducting linac, a stripper station and chicane. We present the results of an optimized linac design and end-to-end simulations including machine errors and detailed beam loss analysis.

Next-generation facilities for the production of exotic beams require large acceptance fragment separators to separate and transmit rare isotopes. Fragment separators require energy degraders in order to achieve high purity separation of these rare species. The introduction of the degrader into an aberration-free optical design of a separator induces aberrations at the achromatic image. These may be completely eliminated by shaping the degrader appropriately. We have shown that, in order to eliminate these aberrations, some aberrations must be nonzero at the dispersive image, where the degrader is placed. A second order design with robust optics is presented.

The development of high-power beam dumps and catchers, and pre-separator layouts for proposed fragment separators of the Rare-Isotope Accelerator (RIA) Facility are important in realizing how to handle the 400 kW in the primary beam. Examples of pre-conceptual designs of the pre-separator area and components, along with examples of ongoing radiation simulations with results characterizing the secondary radiation are given. These initial studies will yield insight into the impact of the high-power dissipation on fragment separator design, remote handling concepts, nuclear safety and potential facility hazard classification, shielding design, civil construction design, component design, and material choices. Furthermore, they will provide guidance on detailed radiation analyses as designs mature.

The Positive-Ion Injector (PII) for ATLAS is complete. First beams from the new injector have been accelerated and used for experiments at ATLAS. The POI consists of an ECR ion source on a 350-kV platform and a low-velocity superconducting linac. The first acceleration of uranium for the experimental program has demonstrated that the design goals of the project have been met, Since the summer of 1992, the new injector has been used for the research program approximately 50% of the time. Longitudinal beam quality from the new injector has been measured to be significantly better than comparable beams from the tandem injector. Changes to the mix of resonators in the main ATLAS accelerator to match better the velocity profile for heavy beams such as uranium are nearly complete and uranium energies up to 6.45 MeV per nucleon have been achieved. The operating experience of the new ATLAS facility will be discussed with emphasis on the measured beam quality as well as achieved beam energies and currents. >

The authors developed a probe for a K1200 superconducting cyclotron based on a charge coupled device (CCD) TV camera that works in a 6 T magnetic field. The camera looks at the beam spot on a scintillating screen. The TV image is processed by a frame grabber that digitizes and displays the image in pseudocolor in real time. This probe has much better resolution that traditional probes. Beams can be seen with total currents as low as 0.1 pA, with a position resolution of about 0.05 mm. >

A new method is presented that allows the reconstruction of trajectories and the on-line correction of residual aberrations that limit the resolution of particle spectrographs. Using a computed or fitted high order transfer map that describes the uncorrected aberrations of the spectrograph under consideration, it is possible to determine a pseudo transfer map that allows the computation of the corrected data of interest as well as the reconstructed trajectories in terms of position measurements in two planes near the focal plane. The technique is only limited by the accuracy of the position measurements and the accuracy of the transfer map. In practice the method can be expressed as an inversion of a pseudo transfer map and implemented in the differential algebraic framework. The practical application in connection with the S800 spectrograph is discussed. >

A secondary beam of radioactive /sup 17/F was produced at the ATLAS accelerator and delivered to an experimental target station with an intensity of as much as 5.10/sup 5/ ions/s for use in the research program. Beams of /sup 17/F were produced via the p(/sup 17/O,/sup 17/F)n or d(/sup 16/O,/sup 17/F)n reactions by bombarding a gas-filled cell with up to 300 pnA beams of /sup 17/O or /sup 16/O from the ATLAS superconducting linac. The gas target, with HAVAR windows, was maintained at pressures as high as 500 Torr. The beam quality was dominated by small-angle scattering in the gas cell windows, by the reaction kinematics and beamline acceptance. Detailed beam parameters are presented. Plans for relocation of the target to allow improved capture efficiency and acceleration or de-acceleration of the secondary beam will also be discussed.

Numerical simulations indicate that it should be possible to use an electron beam to strip 1/sup +/ DC radioactive ion beams to 2/sup +/ or higher charge states with on the order of 40-80% efficiency. The device, which we call an electron-beam charge-state amplifier, is similar to an electron beam ion source, except that it is not pulsed, the beams are continuous. The 2/sup +/ beams are obtained in a single pass through a magnetic solenoid while higher charge states may be reached via multiple passes. An unexpected result of the ion optics simulations is that the normalized transverse emittance of the ion beam is reduced in proportion to the charge-state gain. Ion beams with realistic emittances and zero angular momentum relative to the optic axis before entering the solenoid will travel though the solenoid on helical orbits which intercept the axis once per cycle. With an ion beam about 2 mm in diameter and an electron beam about 0.2 mm in diameter, the ion stripping only occurs very near the optic axis, resulting in the emittance reduction.

A superconducting quadrupole magnet has been designed for use as the focusing element in a low charge state linac proposed at Argonne. The expected field gradient is 350 T/m at an operating current of 53 A, and the bore diameter is 3 cm. The use of rare earth material holmium for pole tips provides about 10% more gradient than iron pole tips. The design and the status of construction of a prototype singlet magnet is described.

The proposed Rare Isotope Accelerator (RIA) Facility includes a post-accelerator for rare isotopes (RIB linac) which must produce high-quality beams of radioactive ions over the full mass range, including uranium, at energies above the coulomb barrier, and with high transmission and efficiency. The latter requires the RIB linac to accept at injection ions in the 1+ charge state. A concept for such a post accelerator suitable for ions up to mass 132 has been previously presented. This paper presents a modified concept which extends the mass range to uranium. The RIB linac will utilize existing superconducting heavy-ion linac technology for all but a small portion of the accelerator system. The exceptional piece, a very-low-charge-state injector section needed for just the first few MV of the RIB accelerator, consists of a pre-buncher followed by several sections of cw, normally conducting RFQ. Two stages of charge stripping are provided: He gas stripping at energies of a few keV/u, and additional foil stripping at /spl sim/600 keV/u for the heavier ions. In extending the mass range to uranium, however, for best efficiency the helium gas stripping must be performed at different energies for different mass ions. We present numerical simulations of beam dynamics for a design for the complete RIB linac which provides for several stripping options and uses cost-effective solenoid focusing elements in the drift-tube linac.