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Title: Muon Acceleration-RLA and FFAG

Abstract

Various acceleration schemes for muons are presented. The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and 'beam shaping' can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a non-scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. The RLAs offer very efficient usage of high gradient superconducting RF and ability to adjust path-length after each linac pass through individual return arcs with uniformly periodic FODO optics suitable for chromatic compensation of emittace dilution with sextupoles. However, they require spreaders/recombiners switchyards at both linac ends and significant total length of the arcs. The non-scaling Fixed Field Alternating Gradient (FFAG) ring combines compactness with very large chromatic acceptance (twice the injectionmore » energy) and it allows for large number of passes through the RF (at least eight, possibly as high as 15).« less

Authors:
 [1]
  1. Center for Advanced Studies of Accelerators Thomas Jefferson National Accelerator Facility 12000 Jefferson Avenue, Newport News, VA 23606 (United States)
Publication Date:
OSTI Identifier:
21611843
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1382; Journal Issue: 1; Conference: NuFact10: 12. international workshop on neutrino factories, superbeams, and betabeams, Mumbai (India), 20-25 Oct 2010; Other Information: DOI: 10.1063/1.3644312; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCELERATION; BEAM ACCEPTANCE; BEAM OPTICS; BEAM SHAPING; BEAM TRANSPORT; CORRECTIONS; GEV RANGE; LINEAR ACCELERATORS; MUON-NUCLEON INTERACTIONS; MUONS; NEUTRINO BEAMS; NEUTRINO OSCILLATION; OPTIMIZATION; RF SYSTEMS; SOLENOIDS; SYNCHROTRONS; ACCELERATORS; BEAMS; CYCLIC ACCELERATORS; ELECTRIC COILS; ELECTRICAL EQUIPMENT; ELEMENTARY PARTICLES; ENERGY RANGE; EQUIPMENT; FERMIONS; INTERACTIONS; LEPTON BEAMS; LEPTON-BARYON INTERACTIONS; LEPTON-HADRON INTERACTIONS; LEPTON-NUCLEON INTERACTIONS; LEPTONS; PARTICLE BEAMS; PARTICLE INTERACTIONS

Citation Formats

Bogacz, S. Alex. Muon Acceleration-RLA and FFAG. United States: N. p., 2011. Web. doi:10.1063/1.3644312.
Bogacz, S. Alex. Muon Acceleration-RLA and FFAG. United States. doi:10.1063/1.3644312.
Bogacz, S. Alex. 2011. "Muon Acceleration-RLA and FFAG". United States. doi:10.1063/1.3644312.
@article{osti_21611843,
title = {Muon Acceleration-RLA and FFAG},
author = {Bogacz, S. Alex},
abstractNote = {Various acceleration schemes for muons are presented. The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and 'beam shaping' can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a non-scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. The RLAs offer very efficient usage of high gradient superconducting RF and ability to adjust path-length after each linac pass through individual return arcs with uniformly periodic FODO optics suitable for chromatic compensation of emittace dilution with sextupoles. However, they require spreaders/recombiners switchyards at both linac ends and significant total length of the arcs. The non-scaling Fixed Field Alternating Gradient (FFAG) ring combines compactness with very large chromatic acceptance (twice the injection energy) and it allows for large number of passes through the RF (at least eight, possibly as high as 15).},
doi = {10.1063/1.3644312},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1382,
place = {United States},
year = 2011,
month =
}
  • Harmonic number jump acceleration of muon beams in scaling FFAG rings is studied. General considerations about harmonic number jump acceleration lead to the necessity of designing rings with dispersion suppressed insertions, and in which both mu{sup +} and mu{sup -} can be circulated in the same direction. Design principles of such a scaling FFAG ring are described. Example of a 3 to 10 GeV lattice is given, and 4D acceleration tracking is done in it.
  • Recent developments in scaling fixed field alternating gradient (FFAG) accelerators have opened new ways for lattice design, with straight sections, and insertions like dispersion suppressors. Such principles and matching issues are detailed in this paper. An application of these new concepts is presented to overcome problems in the PRISM project.
  • Non-scaling FFAG rings have been proposed for muon acceleration in a neutrino factory. In order to achieve small orbit excursion and small time of flight variation, lattices with a very compact cell structure and short straight sections are required. The resulting geometry places very challenging constraints on the injection/extraction systems. The feasibility of injection/extraction is discussed and various implementations focusing on minimization of kicker/septum strength are presented. The injection and extraction systems in the nonscaling FFAG for muon acceleration in a neutrino factory were studied in the ring based on FODO lattice. The vertical direction was found to be preferentialmore » for both injection and extraction, which allows for lower kicker strengths and facilitates the distribution of kickers due to a lower phase advance per cell in comparison with the horizontal plane. It is possible to design mirror-symmetric schemes in which the kickers can be reused for both signs of muons. The disadvantage of these solutions is a need for special magnets with large aperture in the injection/extraction region due to the large kicked beam oscillations. The strengths of the required kickers are still very challenging and the fields in the septum magnets dictates the need for a superconducting design.« less
  • Finite chromaticity in a nonscaling FFAG makes transverse tunes move during acceleration. Particles have to cross many integer and half-integer resonances although all those tunes are imperfection ones. Plausible argument is that the acceleration is so fast that effects of those resonance crossings are marginal. We did a tracking study in a lattice with alignment and gradient errors to see how the orbit and optics distortion is excited. We found that in a time scale of the muon acceleration, namely total tune changes about one unit per turn, the resonance is not a proper way to describe the beam dynamics.more » Instead, a random walk model, in which we assume that alignment and gradient errors kick a particle randomly in phase space, well explains the tracking results.« less
  • The non-scaling fixed field alternating gradient (NS-FFAG) ring is a candidate muon accelerator in the Neutrino Factory complex according to the present baseline, which is currently being addressed by the International Design Study (IDS-NF). In order to achieve small orbit excursion, motivated by magnet cost reduction, and small time of flight variation, dictated by the need to use high RF frequency, lattices with a very compact cell structure and short straight sections are required. The resulting geometry dictates very difficult constraints on the injection/extraction systems. Beam dynamics in the non-scaling FFAG is studied using codes capable of correctly tracking withmore » large transverse amplitude and momentum spread. The feasibility of injection/extraction is studied and various implementations focusing on minimization of kicker/septum strength are presented. Finally the parameters of the resulting kicker magnets are estimated.« less