Overview of Lattice Design Work

1
Overview of Lattice Design Work

• Deepa Angal-Kalinin
• Daresbury Laboratory, UK
• 7th July, 2005
• LC-ABD Meeting, Cambridge

2

• Lattice Design Team
• Daresbury
  Laboratory
• R. Appleby
• F. Jackson
• J. Jones
• D. Angal-Kalinin
• Cockcroft Institute
• L. Jenner

3

• Beam Delivery System Lattice Design
• Design Requirements
• Final focus
• Collimation optics
• Beam diagnostics section
• Machine protection
• Provision for two IRs
• Crossing angle issues

• Beam Extraction
• Extract the highly disrupted beams
• Transport to beam dumps
• Beam sizes at beam dumps
• Diagnostics
• Beam dumps

4
First ILC Workshop, November04 WG4
recommendation, Working hypothesis
20 mrad design similar to NLC
2 mrad design Main design effort since KEK
workshop
D. Angal-Kalinins talk BDIR workshop
5
11 mrad NLC-style Big Bends
e-
2 mrad (L 3.51 m) dump lines
e
IR2 2 mrad
NLC BSY dump lines
20 mrad ILC FF9 (x 4)
IR1 20 mrad
IP separation 138 m (Z), 21 m (X)
20 mrad (L 3.51 m) dump lines
M.Woodley
6
Disrupted Beam Parameters at the IP for ILC
parameters (WG1)
Low energy tail extends to 4020 for nominal ILC
parameters and to lt 10 in high luminosity
options.
Total extracted beam power 11.3 MW (500GeV
CM) 18 MW (1 TeV CM)
7
2 mrad Extraction Scheme
warm QF (r 10mm) 140-153 T/m
SC QD (r ? 35mm) 214-228 T/m
1-1.9m
9m
2 mrad
L3.51m
6-7 mrad
1.3-2.3m
? optical transfer
to beam diagnostics
(consistent with ILC parameters group parameter
space)
R. Applebys talk BDIR workshop
8
2 mrad Crossing angle Extraction line design
SLAC-BNL-UK-France task force Several design
iterations since Nov04

• Shared magnets for incoming and outgoing
• Need large magnet apertures to accept both
  electron beams and photons.
• Final doublet optimised for incoming and outgoing
  beam.

SF1
SD0
QF1
QD0
T. Maruyama
9
DIMAD tracking of disrupted beam through the
extraction line
Beam x envelope in doublet
Beam y envelope in doublet
-80 to -60
-60 to -40
-40 to -20
-20 to 0
TURTLE tracking of disrupted beam through the
extraction line
R. Applebys talk BDIR workshop
10
2 mrad Design Issues

• Long and short doublet solutions based on maximum
  possible gradient of QD0 (in the presence of
  detector solenoid field)
• Transverse size including cryostat
• How does the magnet and cryostat size scales with
  the bore radius of the magnet?
• Present design has very large aperture SC
  sextupoles
• Special extraction line magnet designs SC and
  warm
• Losses on magnets
• Dedicated collimators
• Backscattering and background issues
• Collimation depths
• Performance of diagnostics section

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Collimation depth evaluation

• First-Order method of estimating collimation
  depths for a given final doublet
• To achieve SR fan clearance through IR apertures
• DBLT by Olivier Napoly (Saclay) Analytical
  calculation
• Assumes on-energy halo, omits effect of local
  chromaticity correction
• Crucial apertures
• Vertex, masks, and extraction quads
• Crossing angle issues
• SR fan may see non-symmetric apertures
• 
  
• 
  
• 
  
• 
  F. Jacksonss talk BDIR
  workshop

12
Collimation depths
20 mrad
2 mrad
Long doublet
http//www.slac.stanford.edu/xorg/lcd/ipbi/lcws05/
maruyama_backgrounds.ppt
Short doublet
F. Jacksonss talk BDIR workshop
13
20 mrad Collimation Performance (using STRUCT A.
Drozhdin)
?p 1
For the collimation depths found by DBLT ?
Some beam halo escapes to FD. Non-linear
transport and local chromaticity correction needs
closing of the spoiler openings marginally.
?p 0
F. Jacksonss talk BDIR workshop
14
Optics for beam diagnostics

• Collaboration with Laser wire team for ATF/ATF2 ?
  1 mm sy

L.Jenner ATF, May 2005

• Study proposed tuning and emittance section for
  the ILC
• Beam sizes for laser wire estimate increase in
  length of the section
• Requirements of generic beam diagnostics for ILC
  BDS
• Accuracies and resolutions for these devices
• Optimise the BDS lattice including beam
  diagnostics

15
Final focus optimisation
Bandwidth

• Strong demagnification
• High chromatic and geometric aberrations
• Dipoles for non zero dispersion
• Minimisation of chromatic and geometric
  aberrations is principle design challenge
• Optimisation procedure to 2nd order
• Collaborating with Saclay on global optimisation
  procedure

Emittance growth due to SR
Final focus optimisation, D. Angal-Kalinin, ASTeC
report
16
ATF2 optics and tolerances

• Proposed final focus test facility at ATF to test
  the local chromaticity correction.
• Achieve 35 nm vertical spot size at the focal
  point and nanometer control of beam position.
• Two optics solutions were proposed in Nov04.
• Comparison of these versions.
• The scaled down version of NLC has been chosen
  for ATF2.

Chromaticities
xycorrected
xycorrected
xycorrected
xycorrected
NLC like version
Kuroda version
M.Pivi, D.Angal-Kalinin et al ATF2 optics
comparison report in preparation
17
ATF2 Tolerances and Tuning Knobs
Normal

• Simulations of orbit correction and tuning
  procedure to define the estimations of jitter,
  fast and slow errors for magnet position, roll,
  field errors.
• Tolerances defined as an rms error that
  leads to a 2 increase in beam size or a 15
  change in position whichever leads to a tighter
  tolerance.
• J. Joness talk BDIR workshop
• ATF2 proposal Section 3.2

Field Tolerances Individual Quads Multipole
Errors
Field Tolerances All Quads Multipole Errors
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End Station A Optics for collimation wake field
studies

• Requirements on beam spot-size
• 100 ?m (vertical) for the wakefield and BPM
  experiments
• lt 20 ?m (vertical and horizontal) for the
  material damage tests

20 ?m beam waist at collimator wakefield box
100 ?m beam waist at collimator wakefield box
D. Angal-Kalinin, F. Jacksons talk - 2nd
collimation meeting, Daresbury
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Optics codes

• Extraction line design
• Guinea_PIG, MAD, DIMAD
• MATLAB ? MAD, TRANSPORT, TURTLE
• DIMAD comparison with BDSIM (Orsay, RHUL)
• Collimation Studies
• MERLIN, STRUCT,
  DBLT
• (Manchester, RHUL, COLSIM task in
  EuroTeV)
• Final Focus Studies
• MAD, BETA, DIMAD, TRANSPORT, TURTLE
• ATF2 optics and tuning studies
• MAD, TRACY, BETA
• Will start using SAD soon for
  ATF/ATF2 work.

20
Plans

• Contribute to define a baseline configuration
  for the ILC.
• Feedback from detector community ? L, physics
  evaluations for 2 crossing angles
• Design BDS optics for 2 mrad case for different
  final doublets based on discussions with magnet
  experts.
• Optimise collimation optics for better
  collimation efficiency.
• Study the beam diagnostics section after the
  linac for possibility of using laser wires.
• Study US cold option of fast extraction scheme
  and suggest other ideas.
• Participate to ATF/ATF2 and ESA optics studies.