The TAO program

1
The TAO program

• Presenter
• Jeffrey C. Smith
• L. Fields, R. Patterson, D. Rubin, D. Sagan, J.
  Urban
• Cornell University

2
Outline

• Quick summary of TAO
• List of future plans for Linear Collider modeling

3
The Tool for Accelerator Optimization

• TAO is an easily extensible accelerator design
  and analysis environment
• Many simulation problems fall into three main
  categories
• Design a lattice subject to various constraints
• Simulate what happens to beam parameters when
  conditions have changed in the machine
• A measurement has been taken in the machine and
  sources of optics errors need to be found and
  corrected.
• These types of problems have common elements you
  have variables to vary (such as quadrupole
  strength or kicker strength) and data to view
  (such as particle orbit or beta function) while
  fitting the model to the data.
• TAO was written with this commonality of design
  in mind.
• BMAD library makes TAO easily customizable, many
  times with just a few lines of code.

4
The Power of TAO

• Command line or graphical user interface (GUI in
  development)
• Can handle multiple lattice configurations
  simultaneously
• Same machine at different energies, tunes,
  steering configurations etc and then analyze
  difference between models
• Optimizer will minimize difference between model
  and data
• Two optimizers to choose from
• Levenberg - Marquardt
• Differential Evolution
• More to come
• Handles both storage rings and linacs.
• Can inject from one lattice into another
  (example DR gt LINAC)
• Intended to also interact with control system to
  diagnose and correct machine errors
• Take measurement, run optimizer and load
  corrections by only typing a few commands

5
The Graphing Window

• Easily configured
• Example to right is for an ERL
• lattice element layout on top
• Low energy transport through linac in top two
  graphs
• High energy transport through linac in bottom two
  graphs
• Plotting Eta and Beta
• The two curves in each graph are for two
  different lattice configurations
• Key Table on bottom
• Provides list of commonly used variables
• Shows their difference from the design value and
  if they are being used by the optimizer

6
Future LC modeling

• The father of TAO (called CESRV) has been used
  for quite some time with CESR.
• Used in designing the CESR-C optics
• Actively used in the control room to quickly
  correct orbits, phase, etc
• Tried and True as a useful tool for commissioning
  and operation
• TAO is just getting set up for future Linear
  Collider modeling

7
NLC DR gt IP

• Heres an example where a 1 micron RMS error was
  placed on the vertical alignment of the NLC
  damping ring quadrupoles.
• TAO then
• Finds new storage ring equalibrium beam
  parameters
• Generates macroparticle distribution
• Tracks macroparticles through the BC and LINAC
  to IP.

8
TESLA DR gt IP

• Same type of analysis can be performed on TESLA.
• Here a 1 micron RMS error distribution on the
  vertical alignment of the TESLA DR quadrupoles
  and the obit was tracked to the IP

9
Example NLC Emittance Growth

• Rotation (tilt) errors were introduced on the NLC
  damping ring qaudrupoles
• Macroparticle beam was tracked to the IP.
• Ready to do low emittance optimization

10
Future Plans for LC modeling

• TAO as a tool for LC Design and Optimization
• Track both beams from particle source to IP
• Include beam-beam and space charge (Guinea Pig?)
• Explore beam size and trajectory due to wakes,
  guide field and RF errors
• Low emittance optimization
• Explore generation and propagation of Beam Halo
• TAO as a tool for LC Commissioning and Operation
• Explore commissioning strategies
• Beam based alignment
• BPM errors
• Simulate effectiveness of feedback to compensate
  ground motion
• Simulate measurement of trajectories, phases and
  coupling and develop algorithms for finding and
  correcting errors
• Parallelize TAO on a Linux cluster

11
Thank You

• More information on BMAD and TAO
• www.lepp.cornell.edu/dcs/bmad

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LC tracking from source to IP

• Track macroparticles from injector to damping
  rings
• Track a few turns in damping ring to look at
  injection aperture
• Track Beam Halo in DR
• Find equilibrium damping ring parameters
• Track macroparticles from DR to IP
• Track Beam Halo from DR to IP
• Both beams
• Include beam-beam simulation (Guinea Pig?)