ILC Beam Delivery System Layout and Lattice Design

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ILC Beam Delivery System Layout and Lattice
Design

• 
  Deepa Angal-Kalinin
• ASTeC,
  Cockcroft Institute
• 
  

Cockcroft Institute SAC 23-24th November 2006
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Lattice Design and Simulation Team_at_CI

• Manchester
• Rob Appleby
• Dragan Toprek
• Adina Toader
• Ph.D. Student
• Anthony Scarfe

• ASTeC
• Frank Jackson
• James Jones
• Stephan Tzenov
• Deepa Angal-Kalinin

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Background

• Before the technology decision for the linear
  collider (August 2004) studies were mainly
  focussed on TESLA design
• Problems related to head-on extraction
• Poor collimation performance
• Local chromaticity final focus system was
  designed but was not integrated with rest of the
  BDS
• Alternative solutions to head-on small vertical
  or small horizontal crossing angle
  collaborations with LAL(Orsay), CEA(Saclay)
• The team developed understanding of BDS design
  and requirements, implemented the required
  simulation codes in order to contribute to the
  evolving designs, established good collaborations

• After the technology decision
• Small crossing angle solution and extraction
  line design required urgently
• NLC collimation and final focus design was
  adapted to ILC, performance poor than NLC

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Interaction region - Crossing angle choice
Very small 0 2 mrad Large 14
25 mrad
Incoming and outgoing beams
Shared magnets gt coupled design
Separate magnets

• Challenges in both the schemes
• Large aperture shared magnets or compact magnets
• No/ marginal/complete reliance on crab crossing
• Axial/Non-axial field in the solenoid
• Preserve pre-IP beam or emphasis post-IP beam
• Reflected backgrounds or pre-IP constraints
• Physics prefers head-on with minimum
  background

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2mrad crossing angle extraction line design

• CI team took a lead role in developing the 2
  mrad extraction line design (part of
  SLAC-BNL-UK-France Task Force)
• Due to higher cost of this line and challenges
  in magnet design, this crossing angle solution is
  now an alternative to the baseline with 14 mrad
• CI team is working with LAL to optimise the
  extraction line to minimise the beam losses and
  magnet apertures
• The optimised doublet (Appleby, Bambade, Toprek)
  at 500 GeV CM show significantly less losses in
  the IR region
• Re-designing the rest of the line minimum line
  to start with (Appleby)

• Comparison of number of hits in VXD for the 2
  mrad and 20 mrad (with DID) showed that the pair
  background increases for 20 mrad with DID
• gt 14 mrad anti-DID solution, now adapted for
  the RDR

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Contributions to the ILC collimation optics

• Tools to estimate the collimation depths for
  different crossing angle geometries

• Better collimation efficiency

Halo Tracking to FD entrance
Original Performance
Collimation depth
Optimisations still continuing
F. Jackson
New Performance
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Contributions to the test facilities ATF2
Beam sizes before and after tuning
1mrad QD0 Rotation

• Tuning procedures and tolerances for the ATF2
• Several generic options for tuning of final-focus
  beam at IP Traditional, Rotation Matrix, dumb
• Would like to test these algorithms at ATF2,
  which will present an ideal opportunity to
  provide some limited analysis of the viability of
  these methods.
• Aim to increase our contributions with the help
  of Ph.D. student Anthony Scarfe
• Expertise in tuning area, used to define the
  correction method in the long undulator section
• The techniques developed are applicable to any
  accelerator

Relative luminosity vs tuning knob
J. Jones
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Contributions to the test facilities ESA
vert beam size 83?m for collimator wakefield tests

• Optics design for several experiments at ESA,
  SLAC (January06 and April06 beam tests)
• Require small beam sizes in x and y planes for
  collimator wakefield and BPM experiments
• Optics modelling challenges high dispersion and
  SR in A-line
• Careful emittance and Twiss measurements followed
  by beam tuning
• Achieved goals of ?y?100?m and ?x200?m in
  separate lattice configurations

horz beam size 240?m for BPM studies
F. Jackson
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ILC BDS Layout Changes
First ILC Workshop, KEK, November 2004 Working
hypothesis
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ILC BDS Layout Changes
to Vancouver, July 2006

• Snowmass, August 2005

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ILC BDS Layout Changes

• At Vancouver (July 2006), first cost
  estimates indicated significantly higher costs
  for 2 mrad line gt base line configuration
  changed to 14/14 from 20/2.

ILC GDE
14mrad
14mrad
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ILC BDS Layout Changes

• Valencia, November 2006

1 IR two complementary push-pull detectors
discussed with detector concepts and WWS
ILC GDE
14 mrad
CCR will be submitted this week by the BDS area
leaders
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Present activities and Objectives

• Contributing to several critical decisions on the
  ILC Interaction Region(s)
• The BDS lattice design for the new baseline
  configuration
• Risks vs performance
• Push-pull task force
• Optimisations and tuning studies
• Layout details CFS (shafts/caverns, IR halls)
• Surface assembly for the detectors
• Muon walls
• Contributing to the RDR costing and writing
• Optimisations for 2 mrad and modified head-on
  extraction line designs cost effective, with
  input from magnet designers
• studying the minimum layout design for these
  options without downstream diagnostics

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Future Plan Beam Line Integration

• Continue lattice optimisations for better
  performance, include realistic beam and machine
  errors
• ATF2 skew/emittance LW, final focus, tuning, tail
  folding tests
• Large crossing angle issues
• Beam Line Integration Major involvement of
  CCLRCs engineering expertise
• Lattice design and simulations
• Collimation design
• Vacuum design
• Other CI major activities viz crab system and
  beam dumps integrate naturally with this proposal
• Depends on the outcome of LC-ABD2
  funding request

Background wake fields main concern
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Future Plan Collimation Design

• BDS and extraction lines include 20 different
  types of collimators
• Most critical ones are with the adjustable gaps
  ltmm and long tapers
• CI is a leading contributor (with CCLRC,
  Birmingham and SLAC) on critical collimator
  issues wakefields, survivability
• ESA and simulations (C. Beards talk)
• Future programme builds on this and will
  prototype ILC collimators for
• optimal mitigation of wakefields and component
  damage (and its detection)
• overall engineering design tolerances,
  alignment, movable jaws, cooling, machine
  protection.
• Depends on the outcome of LC-ABD2 funding request

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Future Plan Vacuum Design

• BDS has complex vacuum design
• Spoilers with fraction of millimetres openings to
  beam pipe radius of 200mm in the extraction lines
• Synchrotron radiation at 250-500 GeV is
  significant
• No experimental photon/electron desorption data
  exists at such energies
• The interaction region geometry is most complex
• Backgrounds in the detector are critical
• Push-pull detectors will need special engineering
  solutions
• Real vacuum chamber design (material and detailed
  designs) to estimate the wakes
• Manufacturing and alignment tolerances -
  stringent
• MPS issues
• Depends on the outcome of LC-ABD2 funding request

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ILC BDS Collimation, crab system, beam dumps

• Layout lattice design has a close link with the
  other tasks lead by the CI
• 
  Collimation Carl Beard
• Crab
  system Peter McIntosh
• Beam
  dumps Rob Appleby

Next two talks
ILC GDE
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The ILC beam dumps

• ILC beam dumps and collimators are challenging -
  high power (18MW _at_1TeV CM) and short energy
  deposition showers
• No experience with such beam dumps. Designs have
  been scaled from low power beam dumps
• More simulation and prototypes required
• Using CCLRCs expertise in high power targets
  (ISIS, T2K), a programme lead by CI (Appleby) and
  CCLRC (Densham) has been initiated.
• Definition of UK beam dumps programme, consisting
  of physics (CI) and engineering (CCLRC)
• UK contribution to dumps and collimator costing
• Physics simulation studies

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Future plans Beam Dumps

• The CI (Appleby) will lead physics simulation of
  dumps and collimators throughout the ILC
• Energy depositions
• Shielding and activation of water dump baseline
  and collimators
• Costing and engineering expertise (CCLRCCI)
• Study of only viable alternative to main dump
  the Noble gas dumps (Will seek new funding).
  Crucial if unknown show-stopper for water dump
  and alternative needed.
• Site dependent
• Depends on the outcome of LC-ABD2 funding request

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Summary

• The CI team
• has developed a skill base for optics and
  simulations
• has made significant contributions to the ILC
  baseline and is contributing to the Reference
  Design Report
• is very well integrated with the global design
  effort
• intends to take a bigger role during the
  technical design phase with CCLRCs engineering
  expertise
• Most of the proposed work depends upon the
  outcome of LC-ABD2 funding proposal submitted to
  PPARC