WP1.2 Review Beam Transport Simulations and Backgrounds

1
WP1.2 Review(Beam Transport Simulations and
Backgrounds)

• Glen White, QMUL.
• Oxford University, 24th Oct. 2005

2

• Design www-accessible code management/archive
  facility.
• G. White, G. Christian (QMUL).

• Codes database set-up to provide information and
  downloads of commonly used Beam Dynamics codes.
• Also provides examples of code and links to work
  done.
• Currently undergoing work to make the web-site
  user-updatable.

• Web-accessible database containing data from
  multi-bunch ILC LINAC -gt IP simulations.
• Is being widely used, e.g. Snowmass presentations
  on IR Beamstrahlung studies and Lumi
  Reconstruction (S. Boogert/UCL).

3

• Improve ground-motion models and develop models
  of facilities noise.
• G. White (QMUL), J. Jones (DL).

• Have generic ground motion model created by A.
  Seryi, SLAC.
• Written into a Matlab function by to provide GM
  misalignment of accelerator elements for a given
  set of GM parameters.
• Current benchmarks for ILC simulations used are
  the A,B,C,K-models- K and C represent noisy sites
  and provides a worse-case scenario.
• Need to come to Global agreement on benchmark
  noise models of GM magnet, detector noise etc.
  and write a common package for all to use.
• We should also aim to use measurements from
  proposed ILC sites when they are generated to
  compare machine performance at each site.

4

• Generate benchmark beam-beam interaction results
  for different ground-motion models, parameter
  sets, and machine designs store results in
  database.
• G. White (QMUL).

• A GRID-based beam-dynamics simulation has been
  set-up of the ILC from the exit of the Damping
  Rings through the LINAC and BDS to the IP
  including IP collisions. The simulation was
  constructed using PLACET, MatMERLIN and
  GUINEA-PIG simulation codes with help from D.
  Schulte (CERN) and N. Walker (DESY).
• The Luminosity performance of the ILC has been
  modeled in the presence of ground motion on
  intra-pulse timescales. This incorporates a
  detailed model of the fast beam and luminosity
  feedback systems.
• Work is ongoing to improve the details of the
  design of feedback systems based on the
  simulation results and to extend the work to
  include new accelerator design parameters as they
  are released.
• The future goals of this research will involve
  the extension of this model to include
  simulations of beam alignment and tuning as well
  as an integrated model of slower timescale
  feedbacks to provide a full time-evolved
  simulation of the ILC beam-dynamics.
• Work presented this year at PAC, BDIR, Snowmass
  and Nanobeam.

5
Multi-Seed Luminosity Studies with the ILC
Simulation Model
LUMI Feedback Optimisation (Position Angle)
350 GeV CME
ANG IP Fast Feedback
500 GeV CME
6

• Develop BDSIM into a user-friendly package with
  improved documentation and code-management that
  is used widely in UK BDS studies.
• G. Blair, J. Carter, I. Agapov (RHUL).

• BDSIM is a powerful new beam-dynamics code that
  merges the power of GEANT4 geometry-tracking with
  standard accelerator tracking tools.
• Since Jan 2005, BDSIM has been under public
  release and put under CVS code management
  control.
• It has been used within the UK to model both the
  ILC and CLIC Interaction Regions as well as to
  model the generation of PETRA laserwire signals.
• Work has been shown recently at both BDIR and
  Snowmass.
• Others are now applying it to
• CLIC IR (Uppsala)
• ILC 20 mrad extraction line (Oregon)
• ILC 2 mrad IR (CCLRC, Orsay, RHUL)
• ILC Energy spectrometer (Oregon RHUL)
• ILC neutrons, beam dumps, (RHUL, DESY,
  collab. With FNAL/SLAC)
• Energy Recovery linac (Daresbury)

7
BDSIM
Beamlines are built of modular accelerator
components
Full simulation of em showers
All secondaries tracked
Screenshot of an IR Design in BDSIM
8

• Develop simulation of beam halo, and its
  production.
• J. Carter (RHUL), F. Jackson (DL), G. Kourevlev,
  Adam Mercer (Man Uni).

• Work is underway to develop tracking of Halo
  particles through the final focus systems of the
  different BDS design configurations with BDSIM
  and other simulation tools (DBLT, STRUCT).
• In conjunction with work carried out in WP1.1,
  collimation depths for different BDS designs have
  been evaluated
• 20 mrad crossing angle
• 2 mrad crossing angle, long and short final
  doublet
• Work presented recently at BDIR and Snowmass.

9
IR Halo Studies

• Track Halo electrons from the Final Doublet and
  Interaction Region
• Also track associated Synchrotron Radiation
• Check Halo material passes all apertures

Area of Halo SR distribution hitting QF1 for Nx
Vs Ny
Halo Synchrotron distributions at QF1
Nx 9.0, Ny 45
Nx 9.0, Ny 68
Pocket
Units are numbers of sigma for collimation depth

• Next step is to track this material along the
  extraction line. Check for low energy particles
  backscattering back

10

• Develop expertise in the design of the beam
  diagnostics section (modelling realistic
  backgrounds to find optimal placement of
  laserwire system).
• G. Blair, J. Carter (RHUL).

• After the large amount of work developing the
  BDSIM modeling environment, now in an excellent
  position to start this work.
• Experience has already been gained in using BDSIM
  to model the laserwire output signal in PETRA.
• Future work will incluse the full investigation
  into the design of the BDS to incorporate such
  beam diagnostic sections such that the laserwire
  signal can be properly distinguished from machine
  backgrounds.

Work shown at LCWS 05 comparing modeled response
to actual laserwire data
11

• Study backgrounds generated in the ILC IR and the
  effect on the performance of the IP fast-feedback
  system.
• T. Hartin, (QMUL).

• Expanding on internationally developed models of
  the ILC Interaction Region in GEANT3 (SLAC,
  DESY), the expected EM backgrounds encountered at
  the FFB system have been calculated for all the
  various ILC beam parameters and layouts.
• Future work will involve the migration to a
  GEANT4 framework enabling the inclusion of
  neutron background modeling. Also, a 3D EM model
  of the BPM will be developed to study the physics
  of the background interaction with the BPM in
  more detail
• Also, work has now started on investigation into
  additional theoretical sources of ee- pair
  radiation from beamstrahlung.
• This work was presented at BDIR, Snowmass and
  LCWS2005.

12

• Study alignment and tuning strategies for the
  ATF2 extraction line and for the ILC BDS.
• J. Jones (DL), G. White (QMUL).

• J. Jones Development of alignment and tuning
  algorithms for the ATF2 extraction line, and
  tolerance studies of the extraction line magnets.
  This will lead into further studies of the ILC
  BDS. Has developed a generalised method of
  analysing the tolerances on the ATF magnets in
  terms of field or position errors.
• G. White Study and model alignment strategy in
  the ILC BDS and build into time-evolved LET model
  of the ILC.
• Work has been presented at BDIR, Snowmass and
  Nanobeam this year.

13

• Numerical wakefield and collimation studies.
• R. Jones, G. Kourevlev, A. Mercer, A. Bungau,
  (Man. Uni.).

• An updated wakefield calculation model has been
  implemented into Merlin and is starting to be
  used for Halo tracking studies.
• Work is also starting using Ansys to study
  material shocks, thermal expansion etc.
• Information on collimator wakes will provide a
  vital input into the ILC LET tracking
  simulations.
• Future work will provide an important basis for
  study of hardware based collimator wakefield
  experiments.
• Work was presented at PAC this year.

14

• Background tracking simulations for ESA FONT BPM
  tests.
• C. Clarke, G. White (QMUL).

• As preparatory work for FONT ESA BPM tests (WP4),
  a tracking simulation has been set up using
  GEANT3 and MatMerlin. (Beam expected Summer
  2006).
• This work will assist the experimental set-up in
  optimising the design background at the BPM and
  will provide a theoretical calculation to compare
  the data with.
• Work presented at BDIR this year.

15

• Simulations of ILC IP beam parameter
  reconstruction using event shape analysis from
  beamstrahlung hitting forward calorimeters.
• G. White, C. Swinson (QMUL).

• Using a multi-parameter second-order taylor
  expansion fitting method to extract IP beam
  parameters from photon and ee- pairs that come
  from beamstrahlung radiation and hit forward
  calorimeters.
• Work presented on this at BDIR, PAC, Snowmass
  this year.
• Many possible future directions for this work
  e.g. investigation of different multi-parameter
  techniques i.e. neural nets investigation on
  unfolding internal bunch dynamics- measuring y-z
  correlations at the IP etc

16
Summary and Outlook

• Considerable progress has been made on setting up
  simulations to investigate beam dynamics issues
  relating to the ILC BDS.
• These simulations are essential to other aspects
  of the LC-ABD program (e.g. FONT, Laserwire) and
  to the ILC global design effort.
• We are on track to meet our goals for 2007 to be
  in a position to provide detailed simulation
  models for specific ILC sites, including
• Beam-based approaches for luminosity preservation
  in the presence of measured ground motion models.
• Performance descriptions of beam instrumentation,
  diagnostics and machine protection devices
  (collimation).
• On the longer timescale, we will continue to
  provide support in optimising developed
  strategies to increase the Luminosity performance
  of the ILC through the use of the simulation
  environments we have set up.
• All the work here will also be invaluable for
  diagnostic purposes during the running period of
  the ILC.