A. Zeller

The super-FRS project at GSI

The GSI projectile fragment separator FRS has demonstrated with many pioneering experiments the research potential of in-flight separators at relativistic energies. Although the present facility has contributed much to the progress in the field of nuclear structure physics, major improvements are desirable in the future. The characteristics of the proposed next-generation facility at GSI, the Super-FRS, will be presented and compared to other projects. The Super-FRS is a large-acceptance superconducting fragment separator followed by different experimental branches including a combination with a new storage-cooler ring system. This system consists of a collector ring (CR) and a new experimental storage ring (NESR) which allow precision mass and lifetime measurements as well as in-ring reaction studies. The NESR can be operated in combination with an electron ring to measure electron scattering with exotic nuclei. This electron heavy-ion collider will open up new fields for nuclear structure research.

Medical accelerator projects at Michigan State University

The authors report on three medical accelerator projects at Michigan State University. One involves construction of a 100-MeV superconducting cyclotron for neutron therapy. In the second, a conceptual design has been prepared for a 250-MeV superconducting synchrocyclotron for proton therapy. The third consists of preliminary studies of a compact 1600-MeV superconducting cyclotron system for heavy ion therapy.<<ETX>>

Testing of large aperture superferric quadrupoles

Five different types of superferric quadrupoles are being built for the A1900 Fragment Separator at the NSCL. At least one of each type has been built and tested in an open helium vessel. Quench behavior was recorded and analyzed. Results were compared to calculated quantities such as internal voltages. The measured internal voltages were always less than those calculated with any set of reasonable parameters. All magnets exhibited some training, but every one met or exceeded the required maximum gradients.

An R&D program for targetry and capture at a neutrino factory and muon collider source

The need for intense muon beams for muon colliders and for neutrino factories based on muon storage rings leads to a concept of 1-4 MW proton beams incident on a moving target that is inside a 20-T solenoid magnet, with a mercury jet as a preferred example. Novel technical issues for such a system include disruption of the mercury jet by the proton beam and distortion of the jet on entering the solenoid, as well as more conventional issues of materials lifetime and handling of activated materials in an intense radiation environment. As part of the R&D program of the Neutrino Factory and Muon Collider Collaboration, an R&D eort related to

Design, construction, and first commissioning results of superconducting source for ions at NSCL/MSU.

A new electron cyclotron resonance ion source (ECRIS) was constructed at the NSCL/MSU to replace the existing SC-ECRIS. This ECRIS operates at 18+14.5 GHz microwave frequencies with a planned upgrade to 24-28 GHz in the second phase of commissioning. A superconducting hexapole coil system produce the radial magnetic field; the axial trapping is produced with six superconducting solenoid coils enclosed in an iron yoke to allow the optimization of the distance between the plasma electrode and the resonant zone in the plasma. We report the details of the design, construction, and initial commissioning results of this new ECRIS.

Status report on the design and construction of the Superconducting Source for Ions at the National Superconducting Cyclotron Laboratory/Michigan State University

A status report of the design and fabrication of a new, fully superconducting electron cyclotron resonance ion source will be presented. The Superconducting Source for Ions (SuSI) first will operate at 18+14.5GHz microwave frequencies. A short description of the magnet structure and the injection and extraction hardware will be presented. Several innovative solutions are described, which will allow maximum flexibility in tuning SuSI in order to match the acceptance of the coupled cyclotrons. Details of an ultrahigh temperature inductive oven construction are given as well as a description of the low-energy beam transport line.

Construction and testing of superferric dipoles for the A1900 Fragment Separator

The A1900 Fragment Separator contains four superconducting dipoles. The dipoles produce a field of 2 T at an operating current of 185 A. The changes in effective length have been measured and compared with calculations that predict a longer field boundary than observed. The magnets ran to full field without training. Edge angles were measured and found to be small. All magnets have been installed in the beam line and retested. First beam through the Separator is expected by the end of 2000.

Fabrication and Testing of the Magnet System for SuSI Superconducting Source for Ions

A new superconducting ECR ion source operating at 18 + 14.5 GHz microwave frequencies has been designed and is presently being constructed at the National Superconducting Cyclotron Laboratory at Michigan State University. The magnet system consists of a sextupole magnet assembly surrounded by 6 solenoid coils. Using more solenoid coils gives the ability to adjust the minimum magnetic field as well as vary the position of the axial fields at injection and extraction. The sextupole coils are confined within the solenoid bobbin using the inflated bladder technique. Coil winding and individual coil tests have been completed as well as assembly of the magnetic components. Because the sextupole is the most challenging part of the project, due to the high magnetic fields and large forces, each individual coil was tested to current densities well beyond what are required for actual operation. Testing of the completed magnet system was done in a test Dewar prior to completing the LHe vessel and continuing with cryostat construction. Magnet fabrication, assembly, and testing results will be presented.

Design of SuSI — Superconducting Source for Ions at NSCL/MSU — I. The Magnet System

An ECR ion source is being designed to initially serve as a test bench for development and later will replace the existing 6.4 GHz SC‐ECRIS. This ECRIS will operate at 18+14.5 GHz microwave frequencies. The radial magnetic field will be produced by a superconducting hexapole coil, capable of 1.5 T at the aluminum plasma chamber wall (R=50 mm). The axial trapping will be produced with six superconducting solenoids enclosed in an iron yoke. We will present the Flexible Axial Magnetic Field Concept, introduced for the first time in this design, which will allow tuning the distance between the plasma electrode and resonant zone in the plasma. The distance between the two axial magnetic maxima will be also tunable in the range of 340 to 460 mm.

Status report on the NSCL RF fragment separator

The Radio Frequency Fragment Separator (RFFS) proposed in [1] is now operational at the National Superconducting Cyclotron Laboratory (NSCL). The RFFS is an additional purification system for secondary beams at the NSCL after the existing A1900 fragment separator and will primarily be used to purify beams of rare neutron deficient isotopes. A similar device is already in use at RIKEN [2]. The RFFS uses an rf kicker to angularly 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.