DOE HEP Review, LBNL, Feb' 1819, 2004 M' Furman, CBP Theory, p' 1

1
The Center for Beam PhysicsTheory Group
Miguel Furman Theory Group Leader DOE HEP
Program Review LBNL, 18-19 February, 2004
2
CBP Theory Group

• Carry out original research in accelerator design
  and beam dynamics.
• Provide accelerator physics support for existing
  or future accelerators.
• Explore new mechanisms for particle acceleration
  and related issues.

Our research is strongly customer-driven by
present or future machine performance issues at
LBNL and elsewhere
3
Staff and Funding

• Post doc
• M. S. Hur (Wurtele)
• Grad students (Wurtele)
• A. Charman
• V. Gorgadze
• R. Lindberg
• F. Peinetti (U. Turin)
• Undergrads (UCB)
• J. Rembaum (Wurtele)
• D. Bates (Wolski)
• Researcher (Wurtele)
• M. Reinsch
• Guest scientists (sporadic)
• M. Pivi (SLAC)
• R. Palmer (BNL)

• Staff
• M. Furman (group leader)
• W. Fawley
• G. Penn
• M. Venturini
• A. Sessler (emeritus)
• A. Wolski
• J. Wurtele (UCB faculty)
• M. Xie
• A. Zholents
• M. Zolotorev
• funding from HEP base 4 FTEs
• funding from NLC 2 FTEs
• balance LDRDs, DARPA, IPP, LARP, DAHRT, LCLS

4
HEP-Related Activities

• Lattice design and beam dynamics for NLC damping
  rings.
• Support PEP-II performance improvement.
• Electron-cloud effect.
• Beam-beam interaction (with AMAC group).
• Optical stochastic cooling (test at BNL).
• Novel acceleration mechanisms.
• Laser-pulse amplification.

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NLC Damping Rings

• LBNL has responsibility for design NLC DRs.
• work in collaboration with SLAC and KEK.
• Basic requirement low emittance beams and fast
  rep rate.
• lattice design provide dynamical stability in
  the presence of
• strongly nonlinear fields (wigglers)
• ground motion
• magnet alignment
• correction of coupling and vertical dispersion
• Collective effects.
• improved wiggler magnet modeling and analysis
• electron cloud effect
• intra-beam scattering
• impedance effects
• fast beam-ion instability

(details in Andy Wolskis talk)
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Improvement of PEP-II Performance

• Goal increase L to 2x1034 cm2s1 by summer 2006
  (i.e., factor 3 from now)
• Modeling techniques (measure closed-orbit
  response to parameter changes)
• developed at SSRL and successfully applied at ALS
• Improved model of the interaction region
• Proposals to reduce momentum compaction factor a
• goal decrease bunch length
• work in collaboration with C. Steier (ALS)

(details in Andy Wolskis talk)
7
Electron Cloud Effect (ECE)

• Unwanted electrons perturb the beam.
• surface physics effect compounded by beam
  structure and intensity
• first manifestation beam-induced multipacting
  (ISR, 1977)
• seen at PF, PEP-II, KEKB, BEPC, PS, SPS, APS(e),
  PSR, RHIC
• expected at LHC, SNS, NLC DRs
• possible consequences instability, emittance
  dilution, vacuum pressure rise, interference with
  diagnostic instrumentation, excessive power
  deposition
• we are an early pioneer in the field of ECE
  simulations and analysis
• Our main focus
• simulations for LHC, SPS, and NLC damping rings
• identify important ingredients mitigating
  mechanisms
• code calibration APS, PSR and SPS (lots of
  dedicated measurements)
• LBNL is the main organizer of the ECLOUD04 ICFA
  workshop
• Napa, April 19-23, 2004
• co-sponsored by ICFA, LBNL, CERN, ORNL and SNS
• http//www.cern.ch/icfa-ecloud04

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Electron Cloud Simulations for LHC

• Main issue power deposition on vacuum chamber.
• could overwhelm the cryogenics system if not
  mitigated
• main goal detailed understanding of effects from
  the secondary electron emission process off the
  vacuum chamber surfaces
• work in close contact with LHC personnel (LHC
  Vacuum Group and AP)
• simulation benchmarking against measurements at
  SPS
• the ECE is a possible performance-limiting issue
• Current conclusion
• power deposition is sensitive to details of the
  secondary e emission process
• not completely understood
• more work is critically needed
• improved simulations
• better input data for the simulations

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Example Sensitivity to Details of Secondary
Emission
Simulated power deposition (W/m) vs. time in an
LHC arc dipole (for peak SEY2.05, on the
pessimistic side)
Detailed view for 1.02 lt t lt 1.06 ms
beam current (A.U.)
dedr 43
dedr 0
dedr 10
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Example Code Calibration at the PSR
simulation
data Macek Browman PAC03 paper RPPB035
electron line density
beam line density
slope 200 ns
conclusion d(0)0.4-0.5, consistent with bench
measurements
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ECE Collaborations and Knowledge Transfer

• Collaboration with HIF group at LBNL
• combine strengths of two simulation codes
• lead to self-consistent simulations
• LDRD supported (FY04 is 2nd year out of 3)
• improved tools will be valuable to all HEP and
  non-HEP intense beams (such as HIF drivers)
• in partnership with LLNL
• experimental part, also LDRD-supported
• Collaboration with Tech-X Corp.
• supported by an SBIR phase 2
• wrapped Python code around main secondary
  emission modules we developed
• modular, easy to plug into your own code
• state of the art simulations
• will prove valuable for RF multipactor
  simulations
• ready for general distribution!

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Other Activities

• Beam-beam interaction simulations (LHC, Tevatron,
  PEP-II).
• applied early on to PEP-II design (issues
  asymmetry, parasitic collisions)
• LHC performance (LBNL sweeping luminosity
  detector) (Rob Rynes talk)
• Optical stochastic cooling.
• higher bandwidth than microwave stochastic
  cooling, hence faster cooling rate
• Invention and design of longitudinal beam profile
  monitor (John Byrds talk)
• will be installed in LHC
• tested at the ALS
• Novel acceleration mechanisms
• plasma inverse transition acceleration (inverse
  of EM transition radiation)
• rigorous, general theory relating radiation and
  acceleration
• Laser-pulse amplification (Raman backscatter
  amplifier).
• increase laser pulse peak field without
  large-scale optics by means of plasmas
• potential applications to laser-particle
  acceleration
• Applications of quantum computers.
• if a QC is built, can one use it for classical
  physics calculations (e.g., fast particle
  tracking)?

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Conclusions

• Accelerator physics theory is essential to
  understand performance limitations in present and
  future intense-beam accelerators
• machine must perform at the level desired by
  experimentalists
• in particular, HEP colliders
• issues beam-beam effect, electron-cloud,
  collective instabilities,
• Our group is dedicated to solving these problems.
• We have strong collaborations with other
  labs/projects.
• However
• our HEP work is leveraged by other funding (e.g.,
  LDRDs)
• to maintain our productivity, we need to
• increase student participation
• increase post-docs from 1 to 2, and maintain this
  level