Keyword: focusing
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MOPOB35 Design of the LBNF Beamline Target Station ion, target, shielding, radiation 146
  • S. Tariq, K. Ammigan, K. Anderson, S.A. Buccellato, C.F. Crowley, B.D. Hartsell, P. Hurh, J. Hylen, P.H. Kasper, G.E. Krafczyk, A. Lee, B.G. Lundberg, A. Marchionni, N.V. Mokhov, C.D. Moore, V. Papadimitriou, D. Pushka, I.L. Rakhno, S.D. Reitzner, V.I. Sidorov, A.M. Stefanik, I.S. Tropin, K. Vaziri, K.E. Williams, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  • C.J. Densham
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Long Baseline Neutrino Facility (LBNF) project will build a beamline located at Fermilab to create and aim an intense neutrino beam of appropriate energy range toward the DUNE detectors at the SURF facility in Lead, South Dakota. Neutrino production starts in the Target Station, which consists of a solid target, magnetic focusing horns, and the associated sub-systems and shielding infrastructure. Protons hit the target producing mesons which are then focused by the horns into a helium-filled decay pipe where they decay into muons and neutrinos. The target and horns are encased in actively cooled steel and concrete shielding in a chamber called the target chase. The reference design chase is filled with air, but nitrogen and helium are being evaluated as alternatives. A replaceable beam window separates the decay pipe from the target chase. The facility is designed for initial operation at 1.2 MW, with the ability to upgrade to 2.4 MW, and is taking advantage of the experience gained by operating Fermilab's NuMI facility. We discuss here the design status, associated challenges, and ongoing R&D and physics-driven component optimization of the Target Station.
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TUA1CO04 Simulation of Beam Dynamics in a Strong Focusing Cyclotron ion, cyclotron, cavity, space-charge 251
  • P.M. McIntyre, J. Gerity, A. Sattarov
    Texas A&M University, College Station, USA
  • S. Assadi
    HiTek ESE LLC, Madison, USA
  • K.E. Badgley
    Fermilab, Batavia, Illinois, USA
  • N. Pogue
    LLNL, Livermore, California, USA
  Funding: This work is supported by the US Dept. of Energy Accelerator Stewardship Program.
The strong-focusing cyclotron is an isochronous sector cyclotron in which slot-geometry superconducting half-cell cavities are used to provide sufficient energy gain per turn to fully separate orbits and superconducting quadrupoles are located in the aperture of each sector dipole to provide strong focusing and control betatron tune. The SFC offers the possibility to address the several effects that most limit beam current in a CW cyclotron: space charge, bunch-bunch interactions, resonance-crossing, and wake fields. Simulation of optical transport and beam dynamics entails several new challenges: the combined-function fields in the sectors must be properly treated in a strongly curving geometry, and the strong energy gain induces continuous mixing of horizontal betatron and synchrotron phase space. We present a systematic simulation of optical transport using modified versions of MAD-X and SYNERGIA. We report progress in introducing further elements that will set the stage for studying dynamics of high-current bunches.
slides icon Slides TUA1CO04 [15.462 MB]  
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TUPOB12 Experimental Plans for Single-Channel Strong Octupole Fields at the University of Maryland Electron Ring ion, lattice, octupole, quadrupole 507
  • K.J. Ruisard, H. Baumgartner, B. Beaudoin, I. Haber, T.W. Koeth, M.R. Teperman
    UMD, College Park, Maryland, USA
  Funding: Funding for this project and travel is provided by DOE-HEP, NSF GRFP and NSF Accelerator Science Program
Nonlinear quasi-integrable optics is a promising development on the horizon of high-intensity ring design. Large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, lead to decoupling from incoherent tune resonances. This reduces intensity-driven beam loss while quasi-integrability ensures a well-contained beam. In this paper we discuss on-going work to install and interrogate a long-octupole channel at the University of Maryland Electron Ring (UMER). This is a discrete insert that occupies 20 degrees of the ring, consisting of independently powered printed circuit octupole magnets. Transverse confinement is obtained with quadrupoles external to this insert. Operating UMER as a non-FODO lattice, in order to meet the beam-envelope requirements of the quasi-integrable lattice, is a challenge. We discuss efforts to match the beam and optimize steering solutions. We also discuss our experiences operating a distributed strong octupole lattice.
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TUPOB26 Dynamics of Intense Beam in Quadrupole-Duodecapole Lattice Near Sixth Order Resonance ion, resonance, quadrupole, lattice 552
  • Y.K. Batygin, T.T. Fronk
    LANL, Los Alamos, New Mexico, USA
  Funding: Work supported by US DOE under contract DE-AC52-06NA25396
The presence of duodecapole components in quadrupole focusing field results in excitation of sixth-order single-particle resonance if the phase advance of the particles transverse oscillation is close to 60 deg. This phenomenon results in intensification of beam losses. We present analytical and numerical treatment of particle dynamics in the vicinity of sixth-order resonance. The topology of resonance in phase space is analyzed. Beam emittance growth due to crossing of resonance islands is determined. Halo formation of intense beams in presence of resonance conditions is examined.
poster icon Poster TUPOB26 [3.523 MB]  
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WEPOA09 Proton Beam Defocusing as a Result of Self-Modulation in Plasma proton, ion, plasma, wakefield 707
  • M. Turner, E. Gschwendtner, A.V. Petrenko
    CERN, Geneva, Switzerland
  • K.V. Lotov, A. Sosedkin
    Budker INP & NSU, Novosibirsk, Russia
  Funding: CERN
The AWAKE experiment will use a 400 GeV/c proton beam with a longitudinal bunch length of sigmqz = 12 cm to create and sustain GV/m plasma wakefields over 10 meters. A 12 cm long bunch can only drive strong wakefields in a plasma with npe = 7 x 1014 electrons/cm3 after the self-modulation instability (SMI) developed and microbunches formed, spaced at the plasma wavelength. The fields present during SMI focus and defocus the protons in the transverse plane. We show that by inserting two imaging screens downstream the plasma, we can measure the maximum defocusing angle of the defocused protons for plasma densities above npe = 5 x1014 electrons/cm3. Measuring maximum defocusing angles around 1 mrad indirectly proves that SMI developed successfully and that GV/m plasma wakefields were created. In this paper we present numerical studies on how and when the wakefields defocus protons in plasma, the expected measurement results of the two screen diagnostics and the physics we can deduce from it.
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WEPOA29 Recent Experiments at NDCX-II: Irradiation of Materials Using Short, Intense Ion Beams ion, experiment, target, plasma 755
  • P.A. Seidl, E. Feinberg, Q. Ji, B.A. Ludewigt, A. Persaud, T. Schenkel, M. Silverman, A.A. Sulyman, W.L. Waldron
    LBNL, Berkeley, California, USA
  • J.J. Barnard, A. Friedman, D.P. Grote
    LLNL, Livermore, California, USA
  • E.P. Gilson, I. Kaganovich, A.D. Stepanov
    PPPL, Princeton, New Jersey, USA
  • F. Treffert, M. Zimmer
    TU Darmstadt, Darmstadt, Germany
  Funding: This work was supported by the Office of Science of the US Department of Energy under contracts DE-AC0205CH11231 (LBNL), DE-AC52- 07NA27344 (LLNL) and DE-AC02-09CH11466 (PPPL).
We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and summarize recent studies of material properties created with nanosecond and millimeter-scale ion beam pulses. The scientific topics being explored include the dynamics of ion induced damage in materials, materials synthesis far from equilibrium, warm dense matter and intense beam-plasma physics. We summarize the improved accelerator performance, diagnostics and results of beam-induced irradiation of thin samples of, e.g., tin and silicon. Bunches with over 3x1010 ions, 1-mm radius, and 2-30 ns FWHM duration have been created. To achieve these short pulse durations and mm-scale focal spot radii, the 1.2 MeV He+ ion beam is neutralized in a drift compression section which removes the space charge defocusing effect during final compression and focusing. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing accelerator performance; these keep pace with the accelerator repetition rate of ~1/minute.
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WEPOA60 Design Considerations for the Fermilab PIP-II 800 MeV Superconducting Linac ion, linac, cavity, operation 826
  • A. Saini
    Fermilab, Batavia, Illinois, USA
  Proton Improvement Plan (PIP)-II is a proposed upgrade of existing proton accelerator complex at Fermilab. It is primarily based on construction of a superconducting (SC) linear accelerator (linac) that would be capable to operate in the continuous wave and pulsed modes. It will accelerate 2 mA H ion beam up to 800 MeV. Among the various technical and beam optics issues associated with high beam power ion linacs, beam mismatch, uncontrolled beam losses, halo formation and potential element's failures are the most critical elements that largely affect performance and reliability of the linac. This paper reviews these issues in the framework of PIP-II SC linac and discusses experience accumulated in the course of this work.  
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THPOA16 Gaseous H2-Filled Helical FOFO Snake for Initial 6D Ionization Cooling of Muons ion, solenoid, emittance, dipole 1129
  • Y.I. Alexahin
    Fermilab, Batavia, Illinois, USA
  Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
H2 gas-filled channel for 6D ionization cooling of muons is described which consists of periodically inclined solenoids of alternating polarity with 325MHz RF cavities inside them. To provide sufficient longitudinal cooling LiH wedge absorbers are placed at the minima of transverse beta-function between the solenoids. An important feature of such channel (called Helical FOFO snake) is that it can cool simultaneously muons of both signs. Theoretical considerations as well as results of simulations with G4beamline are presented.
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