Theory and Simulation Jonathan Wurtele, UCBLBNL Presentation to MUTAG June 16, 2000 BNL

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Theory and SimulationJonathan Wurtele,
UCB/LBNLPresentation to MUTAGJune 16, 2000BNL

• Overview
• The challenges of muon capture, bunching
  and cooling
• Future Plans

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Theory and Simulation Overview

• Proton Driver (site-specific)
• Target (specialized MARS (Mokhov) FLUKA)
• Frontend
• Acceleration
• Storage

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Front End Target to start of acceleration
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Progress since last MUTAG meeting

• Systematic simulations--single code (ICOOL,
  DPGEANT, PATH) target to end of cooling (and up
  to 1GeV)
• Implementation of engineering constraints on rf
  gradients, cavity windows, aluminum windows for
  LH absorber, peak magnetic field on conductors,
• Development of theoretical models for particle
  transport and cooling in solenoidal
  channels--greatly increased understanding
• Implementation of single code for comparison for
  post-processing simulation results

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Progress (II)

• Coordination--
• LBL 1 month workshop
• Simulation working group (2 from LBL, FNAL, BNL,
  CERN)
• weekly international conference calls
• Development of different frontend concepts--and
  means to evaluate them

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Frontend Design Effort Status

• Rules
• Simulate with engineering constraints B, J,
  absorber windows, rf windows,
• Front end design should be full
  simulation--target to end of cooling
• Common figure of merit (muons/proton in
  acceptance of downstream system)
• Accomplishments
• Integrated simulations for a variety of frontend
  designs (Monroe, Palmer talks)
• Advances in theoretical understanding (Kim Talk)
• Code development and benchmarking
• Much stronger national and international
  collaboration

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SLIDES FROM OTHER PRESENTATIONS--this is a place
holder for slides prepared primarily by Gregg on
physics of cooling and simulation results
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Feasibility Study I Results
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Enhancing Frontend Performance Beyond
Feasibility Study 1

• Optimize system, especially matching sections
• Early Phase Rotation
• Compensation of nonlinearity in longitudinal
  kinematics
• Longer Drift
• Improved induction linac waveform
• Increase bunching efficiency
• Improve cooling channel designs

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Tools ICOOL (R. Fernow)

• Main Features
• 3D tracking code with interactions in matter
• Since last MUTAG meeting v1.90 --------gt v2.06
• Agrees well with DPGeant
• Used for Frontend simulations
• Feasibility I FOFO channel (Kim)
• Feasibility II SuperFOFO channel (Palmer)
• Recent developments
• New induction linac models
• Improved spin tracking and new spin
  depolarization model
• Hemispherical absorber end region

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Tools DPGeant (based on Geant3, a general HEP
simulation tool)

• Main Features
• 3D tracking code
• includes interactions in matter
• core code library stable
• Applications to Feasibility Study I (and
  beyond)
• single flip channel
• induction linac
• Starting to think about transition to
  Geant4
• C, double precision
• better visualization
• more complete set of EM and hadronic physics

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Limiting factors on performance

• Magnets--limit beta-functions
• RF gradient limits cooling rate (prefer high
  frequency)
• Aperture limits from scraping at entrance to RF
  cavities (prefer low frequency)

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Emittance Exchange

• HARD
• Needs better theoretical capabilities
• Better ways to visualize results and understand
  why things may not work
• There are lots of ideas, not enough time to try
  them
• Workshop in September.

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Theory Plans

• Beam Dynamics
• 4D axicentered DONE
• 6D
• Errors
• Nonlinearities
• Correlations
• Violation of paraxial approximation
• Develop fast design tool using standard ICOOL
  input specifications
• Instabilities

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Code Development Plans

• Improve diagnostics and visualization
• Implement optimization and parallelization
• Common input specifications (minimize tweaking
  to compare results)
• Computational issues (runtime, statistics,..)
• New physics (polarization, induction linac model,
  

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Experimental Support

• Specification of required component performance
• Development of instrumentation and diagnostics
• Precision of measurements

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Macroscopic Studies Plans

• Continue looking at both low complexity and high
  performance frontend concepts
• Target optimization (Carbon/Mercury,horns)
• Simplified frontend designs-- if polarization is
  not required.
• eliminate rf near target, replace cooling with
  drift
• bunch and phase rotate at the same time
• Improve frontend performance
• Longer drift region
• Initial phase rotation
• Emittance exchange
• Gain understanding of components and how to
  effieciently match between them
• Study error sensitivities of a particular design
• Optimize wherever possible
• Accelerate into the recirculator
• Continue to collaborate effectively and
  coordinate with CERN group

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The challenge

• Maximize of muons/p-GeV
• Total production of useful pions is roughly .
  pion/proton-GeV
• Choice of energy influences yield and phase space
  density.
• ?, ?- phase spaces not the same at at 2GeV
• Number of pions in 6D phase space acceptance
• Phase rotation fixes a significant fraction of
  the problem
• Cooling must handle the rest.

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Significant progress has been made

• Benchmarked DPGEANT, ICOOL and PATH
• Theoretical understanding of transverse cooling
  dynamics
• Improved ICOOL
• Significant engineering concerns included in the
  simulations
• Started integrated front end simulations
• Learned to work together in a more coherent way
  (weekly phone calls, extended visits)
• Established working interactions with CERN group