Low- and Medium-Energy Accelerators and Rings


Paper Title Page
FPAE011 8 GeV H- Ions: Transport and Injection 1222
  • W. Chou, A.I. Drozhdin, C. Hill, M.A. Kostin, J.-F. Ostiguy, Z. Tang
    Fermilab, Batavia, Illinois
  • H.C. Bryant
    UNM, Albuquerque, New Mexico
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  • G. Rees
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • P.S. Yoon
    Rochester University, Rochester, New York
  Funding: Work supported by the Universities Research Association, INC. under contract with the U.S. Department of Energy NO. DE-AC02-76CH03000.

Fermilab is working on the design of an 8 GeV superconducting RF H- linac called the Proton Driver. The energy of the H- beam is an order of magnitude higher than any existing H- beams. This brings up a number of new challenges to the transport, stripping and injection into the next machine (the Main Injector), such as blackbody radiation stripping, magnetic field and residual gas stripping, Stark states of hydrogen atoms, foil stripping efficiency, single and multiple Coulomb scattering, energy deposition, foil heating and stress, radiation activation, collimation, jitter correction, etc. This paper will give a summary of these studies.*

*For details the reader is referred to FERMILAB-TM-2285-AD-T.

FPAE066 The IFUSP Microtron New Configuration 3703
  • M.L. Lopes, M.N. Martins, P.B. Rios, J. Takahashi
    USP/LAL, Bairro Butantan
  Funding: Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPq.

In this work we present a new design for the IFUSP main microtron accelerator. The new configuration improves the maximum output energy and eases the operation of the machine. The accelerator will be able to deliver 38 MeV after 43 turns. The input energy was reduced from 4.9 to 2.5 MeV, so that the first microtron stage, the booster, could be eliminated, reducing the number of synchronous stages and easing the operation. We present results for the energy, energy gain and phase slip per turn, and the beam ellipses. We also discuss the design of the insertion and extraction lines.

FPAE067 Present Design and Calculation for the Injection-Dump Line of the RCS at J-PARC 3739
  • P.K. Saha, N. Hayashi, H. Hotchi, Y. Irie, F. Noda, T. Takayanagi
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida, I. Sakai
    KEK, Ibaraki
  The RCS(rapid cycling synchrotron) of J-PARC(Japan proton accelerator research complex) acts as an injector to the main ring as well as a high-power beam for the spallation neutron source at a repetition rate of 25 Hz, where at present the injection and the extraction beam energy are chosen to be 0.181 GeV and 3.0 GeV, respectively. The present work concerns on the present design and calculations for the injection-dump line of the RCS, which includes, 1) an accurate aperture list of all elements taking into account a wide range of the betatron tune, effect of changing injection modes, multiple trajectories of different particles after the charge-exchange foil( like H0 from the H- and H- beam itself)and 2) an accurate estimation of the uncontrolled beam losses especially from the H0-excited states, multiple coulomb scattering at the charge-exchange foil and also the lorentz stripping loss at the septum magnets so as to optimize them concerning mainly the radiation issues as well as for the hands-on maintenance.  
FPAE068 Charge Strippers in the RIKEN RI-Beam Factory 3751
  • H. Ryuto, N. Fukunishi, A. Goto, H. Hasebe, N. Inabe, O. Kamigaito, M. Kase, Y. Yano, S. Yokouchi
    RIKEN/RARF/CC, Saitama
  In the RIKEN RI-Beam Factory, ions from hydrogen to uranium are planned to be accelerated by four cyclotrons and linacs using four stripper sections. The charge stripping schemes for typical ions and the selection of the charge strippers are described. The results of the measurements on charge state fractions are presented.  
FPAE069 DESIREE - A Double Electrostatic Storage Ring for Low Energy Ion-Ion Collisions
  • L. Liljeby, G. Andler, L. Bagge, M. Blom, H. Danared, A. Källberg, S. Leontein, P. Löfgren, A. Paal, K.-G. Rensfelt, A. Simonsson, Ö. Skeppstedt
    MSL, Stockholm
  • H. Cederquist, M. Larsson, H.T. Schmidt, K. Schmidt
    Stockholm University, Department of Physics, Stockholm
  The advantages of storage rings with only electrostatic elements were first demonstrated in ELISA at Aarhus University and later in other places. At MSL and the Physics Department at Stockholm University the ideas have been developed further in the Double Electrostatic Storage Ion Ring ExpEriment, DESIREE. Beams of negative and positive atomic or molecular ions will be merged in a common straight section of two storage rings for studies of low energy collisions. The whole system may be cooled to below 20 K in order to relax internal excitations in stored molecules. This project is now fully financed and the final design work is in progress. A status report will be given in this paper together with a brief review of the planned physics program.  
FPAE070 A Collimation Scheme for Ions Changing Charge State in the LEIR Ring 3816
  • J. Pasternak, C.B. Bal, C. Carli, M. Chanel, E. Mahner
    CERN, Geneva
  Avalanche-like pressure rise and an associated decrease of the beam lifetime, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators operating at low energy. Capture of electrons from the electron cooler is another source of ion losses and thus, of pressure rise. The vacuum system of the LEIR ring has to be upgraded to reach the dynamical vacuum pressure in the low 10-12 Torr range necessary to reach design performance. A collimation system to intercept lost ions by absorber blocksmade of low beam induced outgassing material will be installed. This paper reviews the collimation scheme and simulations of beam loss patterns around the ring.  
FPAE071 Initial Results on Neutralized Drift Compression Experiments (NDCX-IA) for High Intensity Ion Beam 3856
  • P.K. Roy, A. Anders, D. Baca, F.M. Bieniosek, J.E. Coleman, S. Eylon, W.G. Greenway, E. Henestroza, M. Leitner, B. G. Logan, D. Shuman, D.L. Vanecek, W. Waldron, S. Yu
    LBNL, Berkeley, California
  • R.C. Davidson, P. Efthimion, E.P. Gilson, I. Kaganovich, A.B. Sefkow
    PPPL, Princeton, New Jersey
  • D. Rose, C.H. Thoma, D.R. Welch
    ATK-MR, Albuquerque, New Mexico
  • W.M. Sharp
    LLNL, Livermore, California
  Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

Ion beam neutralization and compression experiments are designed to determine the feasibility of using compressed high intensity ion beams for high energy density physics (HEDP) experiments and for inertial fusion power. To quantitatively ascertain the various mechanisms and methods for beam compression, the Neutralized Drift Compression Experiment (NDCX) facility is being constructed at Lawrence Berkeley National Laboratory (LBNL). In the first compression experiment, a 260 KeV, 25 mA, K+ ion beam of centimeters size is radially compressed to a mm size spot by neutralization in a meter-long plasma column and beam peak current is longitudinally compressed by an induction velocity tilt core. Instrumentation, preliminary results of the experiments, and practical limits of compression are presented. These include parameters such as emittance, degree of neutralization, velocity tilt time profile, and accuracy of measurements (fast and spatially high resolution diagnostic) are discussed.

FPAE072 RF-Kicker System for Secondary Beams at NSCL/MSU 3880
  • D. Gorelov, V. Andreev, D. Bazin, M. Doleans, T.L. Grimm, F. Marti, J. Vincent, X. Wu
    NSCL, East Lansing, Michigan
  The design and construction of a radio frequency (RF) kicker system at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU) has been proposed. This RF kicker system will be used to purify secondary beams of rare isotopes after the existing A1900 Fragment Separator and will open a wide range of possibilities for new experiments at the forefront of nuclear science. The proposed system is studied as an efficient alternative to the traditional approach using Wien Filter. Rare neutron deficient secondary beams are challenging to purify because of the presence of intense contaminants that cannot be removed by the traditional energy loss method. However, velocity differences resulting in time-of-flight differences can be used for the effective separation of the beams transversely using the time-varying electromagnetic fields of the RF kicker. Its technical design will be presented together with the beam dynamics analysis of a secondary beam in realistic 3D electromagnetic fields. The expected purification improvement of the exotic beams for the foreseen nuclear physics experiments will be shown in details.  
FPAE073 A Free Hg Jet System for Use in a High-Power Target Experiment 3895
  • P.T. Spampinato, T.A. Gabriel, V.B. Graves, M.J. Rennich
    ORNL, Oak Ridge, Tennessee
  • A. Fabich, H. Haseroth, J. Lettry
    CERN, Geneva
  • H.G. Kirk, N. Simos, T. Tsang
    BNL, Upton, Long Island, New York
  • K.T. McDonald
    PU, Princeton, New Jersey
  • P. Titus
    MIT/PSFC, Cambridge, Massachusetts
  Funding: Work funded by the U.S. Department Of Energy.

We describe a mercury jet system that is suitable for insertion into the 15cm diameter bore of a high-field solenoid magnet. The device features a hermetically sealed primary containment volume which is enclosed in a secondary containment system to insure isolation of mercury vapors from the remaining experimental environment. The jet diameter is 1-cm while the jet velocity will be up to 20 m/s. Optical diagnostics is incorporated into the target design to allow observation of the dispersal of the mercury as a result of interaction with a 24 GeV proton beam with up to 20 x 1012 ppp.

FPAE074 Beam Parameter Measurement and Control at the SNS Target 3913
  • M.A. Plum, M. Holding, T. McManamy
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The spallation neutron production target at the SNS facility is designed for 1.4 MW beam power. Both beam position and profile must be carefully controlled within narrow margins to avoid damage to the target. The position must be within 2 mm of the target center, and 90% of the beam must be within the nominal 70 mm x 200 mm spot size, without exceeding 0.18 A/m2 peak beam current density. This is a challenging problem, since most of the diagnostics are 9 m upstream of the target, and because the high beam power limits the lifetime of intercepting diagnostics. Our design includes a thermocouple halo monitor approximately 2 m upstream of the target face, and a beam position monitor, an insertable harp profile monitor, and a beam shape monitor approximately 9 m upstream. In this paper we will discuss our strategy to commission the beam delivery system and to meet target requirements during nominal operation.

FPAE075 Radiation Damage to the Elements of the SIS300 Dipoles 3943
  • E. Mustafin, J. Kaugerts, G. Moritz, G. Walter
    GSI, Darmstadt
  • L.N. Latysheva, N. Sobolevskiy
    RAS/INR, Moscow
  Funding: Supported by the grant of the GSI-INTAS Project #03-54-3588.

Radiation damage to various elements of the cosine-theta type dipoles of the SIS300 synchrotron of the FAIR Project was calculated. Among the elements under consideration were the superconducting cable, insulating materials, and high-current by-pass protection diodes. The Monte-Carlo particle transport codes MARS and SHIELD were used to simulate propagation of the lost ions and protons, together with the products of nuclear interactions in the material of the elements. It was found that the lifetime of the protection diodes under irradiation is a more restrictive limit for the tolerable level of beam losses than the occurrence of magnet quenches.

FPAE076 The System of Nanosecond 280-keV-He+ Pulsed Beam 3982
  • P. Junphong, Mr. Ano, Mr. Lekprasert, Dr. Suwannakachorn, N. Thongnopparat, T. Vilaithong
    FNRF, Chiang Mai
  • H. Wiedemann
    SLAC, Menlo Park, California
  Funding: We would like to acknowledge the support of the Thailand Research Fund, the National Research Council of Thailand, the Thai Royal Golden Jubilee Scholarship Program, the Faculty of Science, and the Graduate School of Chiang Mai University.

At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between chopper and buncher have been included in the optimization of the bunch length.

FPAE077 LSP Simulations of the Neutralized Drift Compression Experiment 4006
  • C.H. Thoma, D.R. Welch
    ATK-MR, Albuquerque, New Mexico
  • S. Eylon, E. Henestroza, P.K. Roy, S. Yu
    LBNL, Berkeley, California
  • E.P. Gilson
    PPPL, Princeton, New Jersey
  Funding: Work supported by the VNL for HIF through PPPL and LBNL.

The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory involves the longitudinal compression of a singly-stripped K ion beam with a mean energy of 250 keV in a meter long plasma. We present simulation results of compression of the NDCX beam using the PIC code LSP. The NDCX beam encounters an acceleration gap with a time-dependent voltage that decelerates the front and accelerates the tail of a 500 ns pulse which is to be compressed 110 cm downstream. The simulations model both ideal and experimental voltage waveforms. Results show good longitudinal compression without significant emittance growth.