Low Emittance Transport, Main Linac Optics, Instrumentation WBS 2'7 3'7

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Low Emittance Transport, Main Linac Optics,
Instrumentation(WBS 2.7 3.7)

• Nikolay Solyak
• Fermilab

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Budget FY06 carryover FY05
(all numbers are in k)
Fermilab Budget gt vibration study
Instrumentation and FeedBack
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WBS 2.7.1 Linac Beamline design

• Scope
• Optics and beam dynamics design for the main
  linac
• Define Layout of cryomodules and RF components
  for the main linac
• Finalize cavity, refrigerator spacing, cryogenic
  vacuum segmentation, quad/bpm size
• Collaboration with other institutions
• Optics design - with Cornell and FNAL in the US
  and with CERN and KEK.
• Studying sensitivity to quad spacing and BPM
  resolution Cornell, FNAL,
• CM and RF layout work - FNAL, KEK, INFN and
  DESY.
• Key personnel on Optics
• SLAC P.Tenenbaum 20, S.Seletskiy 10 Cornell
  D. Sagan,
• FNAL S. Nagaitsev, N.Solyak, K.Ranjan,
• KEK K. Kubo, CERN D. Schulte

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Deliverables in FY06

• Complete comparison of simulation codes
• Exersize1 and Exersize2 done
• Complete design of the lattice for the curved
  linac (Baseline configuration)
• Lattice 1Quad /4 CM - ready
• Complete tuning and sensitivity studies for a
  curved Main Linac.
• Finalize design and document it for RDR

• Plans for FY07 (projection)
• Continue work of FY06.
• Dynamic studies, including beam jitter, ground
  motion, feed-back algorithms

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BENCHMARKING / CROSS CHECKING CODES SINGLE
BUNCH EMITTANCE DILUTION WITH STATIC
MISALIGNMENTS

• In the various results presented during SNOWMASS
  and in the recent LET workshop at CERN,
  differences among the various Main Linac
  simulation codes were found.
• Significant differences in the emittance dilution
  predictions and sensitivity of the beam based
  alignments.
• Thus, it is generally felt by LET community to
  understand these subtle differences carefully and
  hence various analyzers have agreed to
  cross-check results

Codes compared BMAD (TAO) -- Jeff Smith
(Cornell) PLACET -- Daniel Schulte
(CERN) MERLIN -- Nick Walker (DESY)
Paul Lebrun (FNAL) separately SLEPT --
Kiyoshi Kubo (KEK) MATLIAR -- Peter
Tenenbaum (SLAC) and Kirti Ranjan (Fermilab) CHEF
-- Leo Michelotti (FNAL) exercise
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BENCHMARKING Exercise 2 (DFS)

• Goal Include all misalignments and the vertical
  correctors setting.
• Misalignments and vertical correctors setting
  files for DFS (for Quads, BPMs and cavities)
  generated by using MATLIAR.
• Differences are found in reference energy
  calculation, integrated quad strengths,
  incorporation of wake effects etc. Different
  groups have been able to find some small
  bugs/differences in their code while doing these
  tests.

Wakes on
BMAD results are different w/ wakes on. No
difference w/o wakes.
10 variation are we close enough?
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2.7.3 Main Linac Accelerator Physics

• Scope
• Developing tools to study the preservation of
  emittance in ML
• Lattice design
• Specification of alignment tolerances of the
  components
• Specifications for Instrumentation and
  diagnostics
• Static tuning and alignment studies.
• Failure analysis
• Dynamic effects and Feedback studies
• Integrated simulations of static and dynamic
  effects across all sub-systems from DR to IP.
• Collaboration Within the Americas region,
  Fermilab is collaborating with SLAC and Cornell,
  outside CERN, DESY and KEK on these ML design.
• Key Personnel Nikolay Solyak, Sergei Nagaitsev,
  Kirti Ranjan, Paul Lebrun, Mike Church, Francois
  Ostiguy, Alex Valishev, Leo Michelotti

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Results and schedule

• LET Studying (static and partly dynamic) in
  straight line Linac
• (ILC Snowmass05 and CERN,March06 LET meeting
  presentations )
• Code benchmarking (including MatLiar, CHEF,
  OptiM, Merlin)
• Upgrading tools for curved linac studies
  MatLiar, CHEF, OptiM
• Started Main Linac Lattice studies for curved
  Linac
• Deliverables in FY06
• Finalize the ILC Main Linac Lattice for curved
  Linac (RDR document)
• Complete detailed LET calculations for this
  lattice, including the specifications for the
  alignment, resolution, beam jitter by mid - FY06.
  
• Complete failure analysis
• Complete CHEF and OPTIM accelerator modeling
  codes upgrade for ML Studies.

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OVERVIEW

• ILC Main Linac Simulation
• Before Baseline Configuration Document (BCD)
• Status till Snowmass,05
• After ILC BCD
• Preliminary results for the ILC BCD curved Linac
• Benchmarking among various codes

Performed similar work for NLC

• Study single-bunch emittance dilution in Main
  Linac
• Compare the emittance dilution performance of
  two different beam-based steering algorithms
  11 Dispersion Free Steering under nominal
  conditions of static misalignments of the various
  beamline elements
• Compare the sensitivity of the steering
  algorithms for conditions different from the
  nominal
• Compare the different lattice configurations
  (with different Quad spacing)
• Beam and quad Jitter, Bumps

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ILC BCD Curved vs. Straight Linac

• All nominal misalignments except that all
  errors in 1st 25 CMs are reset to 0 WAKES ON
• Matched initial beam conditions are used 100
  seeds BPMs only at YCOR locations

CURVED
STRAIGHT
Mean 132 nm 90 229 nm
Mean 143 nm 90 274 nm
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11
DFS
Mean 11.9 nm 90 16.3 nm
Mean 2.7 nm 90 4.7 nm
DFS
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LET Simulation Tools development

• Mat-LIAR
• Used since 2002 for LET simulations
• New features for added realism
• Features to support curved Linacs (FNAL)
• Lucretia
• Matlab toolkit for LET simulations
• CHEF
• Interactive program for accelerator Optics
• GUI integrated, Linux, Windows
• Used since 2002 for Accelerator simulations
• OptiM
• Used more than 10 years
• Integrated system for Optics design, support and
  measurement analysis
• Similar to MAD but has integrated GUI

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CHEF AN INTERACTIVE PROGRAM FOR ACCELERATOR
OPTICS
CHEF uses high level graphical user interfaces to
facilitate the exploitation of lower level tools
incorporated into a hierarchy of C class
libraries. Uses for circular machines and
transfer lines, now Upgrading for ILC studies

• Deliverables in FY06
• Arbitrary movement of any element.
• Introduce wakefields into the cavities.
• Complete of all benchmark exercises.
• Implement BBA algorithms (DFS,BA, Kubo).
• Static alignment studies for curved linac
• Start Dynamic and Feedback studies

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OptiM Accelerator Optics Code for ILC

• OptiM GUI based Windows general accelerator
  optics code developed by V. Lebedev.
• Used for optics studies at CEBAF and later at
  many Fermilab accelerators and beam lines,
  including Tevatron, Accumulator, Debuncher,
  Booster, Recycler.
• Among the main features are
• Fully coupled 4D betatron motion treatment
• Macro particle bunch tracking
• Fitting procedures
• Command line version ported to Linux
• No wake fields
• No beam based alignment features

Emittance dilution in MatLIAR and OptiM with 1mm
Quad misalignments in Curved ILC Linac
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3.7.1 Cornell University RD program

• 2.30. Beam simulation Main beam transport in the
  linacs and beam delivery systems, beam halo
  modeling and transport, and implementation as a
  diagnostic tool for commissioning and operation.
• Contact person Dave Rubin, LEPP, Cornell
  University
• Key Persons G. Dugan, L. Gibbons, B. Heltsley,
  M. Palmer, R. Patterson, D. Rubin, D. Sagan,
  J.Smith.
• SLAC P.Tenenbaum, M. Woodly
• Scope of the project
• Machine commissioning and operation
• Development of the TAO/BMAD as a tool for beam
  simulation and diagnostics in ILC
• Integrated Damping Ring to IP simulation
• Main Beam transport
• Studying of three Static Alignment Algorithms
  (DFS, Balistic Alignment, Quad shunting) in the
  presence of the following
• BPM Resolution and Beam Jitter
• Stray Fields
• Spin polarization transport from the damping ring
  to the IP
• BPM and Steering Magnet Failure
• Stronger Wakefields in Low Loss Cavities

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Progress Report FY05 and Deliverables

• Recent results were presented at Snowmass and
  CERN Low Emittance Transport meeting in Feb,2006.
• Benchmarking BMAD/TAOILCn
• Three BBA algorithms implemented in ILCn and
  studied DFS, Ballistic and Kubo
• Effect of BPM resolution, Stray fields, beam
  jitter, BPM and steering magnet failure for
  straight linac.
• Effect of various cavity shape wakefields
• FY06 Deliverables
• Exploit the capability of ILCv to study the
  effect of ground motion on beam trajectory and
  emittance dilution
• Efficiency of the alignment feedback algorithms
• Calculations to support RDR document
• Plans for FY07
• Halo studying in DR, spin rotator, Main Linac,
  BDS

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Communications, meetings

• LET website off SLAC-ILC site
• LET meeting at FNAL website
• LET forum at forum. linearcollider.org
• Biweekly LET meeting
• weekly MPS meeting

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2.7.2 Linac wakefields

• Motivation
• Cavity long-range wakefields may dilute the small
  vertical beam
• emittances in the ILC linacs (trapped modes and
  mode rotation).
• Short-range wakes are responsible for the single
  bunch emittance dilution.
• Scope of RD
• Compute the long-range wakefields in the
  superconducting cavities using parallel
  processing techniques (3-D modelling).
• Understand their effect on beam transport
• Trapped modes in the 4-8 GHz range due to cavity
  imperfections
• Effect of mode polarization on coupling the
  horizontal and vertical beam motion.
• Milestones and deliverables
• Summer06 Present modeling and beam transport
  simulation results at ILC meetings
• Key personnel (2.55 FTE)
• SLAC Karl Bane 25, Roger Jones 10, Andreas
  Kabel 25, Liling Xiao 100, Zenghai Li 70,
• Gennady Stupakov 25
• FNAL N. Solyak, DESY J. Sekutowicz

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ILC Electromagnetic Simulations _at_ SLAC

• Parallel codes include Omega3P (mode
  damping),T3P (wakefields), and Track3P
  (multipacting and dark current)
• Goal is to use Simulation to improve the
  end-groups in the ILC cavity designs (BCD, ACD)
  so that they can better meet HOM damping
  requirements and also to address associated
  cavity issues,
• FY05 has primarily focused on the ILC cavity HOM
  damping (TDR, LL, Ichiro) in collaboration with
  DESY (Sekutowicz) and KEK (Saito),
• FY06 efforts include understanding the effects
  of mode rotation, trapped modes in single cavity
  (Low-Loss) and multipacting in TTF3 coupler,
• FY07 (1) Cavity deformation effect on HOM
  damping
• (2) Trapped modes in multi-cavity
  cryomodule
• (3) End-group feed-through failure
• (4) Crab cavity design

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Mode Rotation in HOM pairs
The dipole mode degeneracy is split by the 3D
geometry of the asymmetric end groups. When the
line widths of modes due to damping exceeds the
mode frequency separation and overlap each other,
then mode rotation occurs for both modes.
E field of rotating mode seen by beam traveling
down the cavity

• Matlab pdetool 2D Helmholtz Eq. mesh 50,000
  nodes
• Round beam pipe, TM11 mode
• Perfect conductivity Ez 0 on wall except at 6
  deg stretches at ? 0, 45? Ez ?1H? or ?2H?
• Imaginary part (top) / real part (bottom) of Ez
  for first mode is given at right
• Note that Re(Ez) has different phase than Im(Ez),
  which, in general, indicates an elliptically
  polarized force.
• First mode F? traces out ellipse with axes ratio
  b1/b2 0.52, tilted at angle ?0 -41?.
• Second mode the same, except ? -41? 90?

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Effect of Mode Rotation

• Omega3P (black) and data from 8 cavities (color)
  show
• mode rotation in some pairs of degenerate modes
• cavity imperfections causing data scatter around
  ideal cavity

Impedance
1st Band
T3P simulation with beam
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Fermilab CD/AMR/Computational Physics for
Accelerators
FNAL 2006 activities (for linac)

• Electromagnetics
• Model crab cavity (with Tech-X, ongoing), wakes
• Create model of complete linac cavity including
  HOMs
• (second half of '06)
• Beam dynamics
• Single particle optics CHEF modeling of LET,
  enhance CHEF to include beam position. Upgrade
  OPTIM for static and dynamic LET simulations
• Dynamic aperture including realistic wakefields
  (tabulated feedback correction capabilities
  from above modeling)

2007 activities (projected)

• Continue FY'06 activities
• EM full cryomodule wakefield computations
• BD utilize CHEF enhanced capabilities (feedback)
• Start beam-beam _at_ IP studies, add quantum effects
  in beam-beam code

Longitudinal wakefields in Tesla cavity
Key persons Spentzouris, Stern, Amundson,
Dechow, Michelotti
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2.7.4 Alignment, Vibration and Ground motion
studies for the ILC

• Motivation
• Stability of ILC is determined by the stability
  of the site, additional noises of beamline
  components, energy and kicker jitter, and
  performance of train-to-train and intra train
  feedback.
• Goals of Fermilab studies
• Identify types of ground motion both fast and
  slow
• Identify sources and amplitudes of these motions
• Identify effects on ILC components
• Determine ways to eliminate or reduce these
  motions
• Source of motion
• site ground motion and ILC in-tunnel and
  near-tunnel hardware noise
• additional noise of beamline components
  including amplification of floor motion by
  supports

Types of ground motion
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Layout of Minos water level
Depth of floor 100 meters below grade 406 feet
above sea level Maquoketa shale
30 meters
30 meters
30 meters
MINOS detector
MINOS water level sensor, BINP
u direction
Not to scale
Sensors along wall lower level
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Difference between two sensors 90m apart in MINOS
hall
Fast motion in Tevatron tunnel
Tidal forces move the floor of the tunnel 10mm,
period12 hrs.
Sump pump test MINOS hall
FFT of MINOS data
This is a FFTof the data. The tidal peak is
clearly found there. Data is being collected that
will help identify the period and allow us to
understand what these motions are caused by.
During the pumping test the floor of the hall
tilts toward the sump pit 0.04 mr
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Deliverables FY06 and Future Work

• Continue slow motion studies of floor in Aurora
  Mine and MINOS hall
• Measure and identify sources of cultural fast
  cultural noise in Tevatron and MINOS hall
• Develop techniques to reduce eliminate vibration
  of accelerator componets

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Summary

• Progress in Linac design and Low Emittance
  Transport simulation and developing /
  benchmarking tools for the beam dynamics
  studying
• Needs more efforts to finalize Linac design,
  component location and alignment specifications
  and document it for RDR. Develop beam based
  feedback and tuning strategy in the ILC linac
  should be next step of LET studies
• Good progress in simulation of the wakefields for
  ILC cavity and its effect on emittance
  preservation in Main Linacs. Better understanding
  big scattering in HOM in ILC cavity due to mode
  rotations, trapped modes, imperfection is key to
  control emittance
• Ground motion studies, vibration, alignment
  studies are underway at Fermilab site. This is
  important part of site stability issue. Needs
  more efforts to collect and analyze data and
  develop techniques to reduce vibration of
  accelerator components.