LHC Accelerator Research at SLAC

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LHC Accelerator Research at SLAC

• T. Markiewicz
• SLAC Department Head (9/2008)
• LARP Accelerator Systems Division Leader (9/2008)
• LARP Collimation Leader (9/2005)
• LARP Rotatable Collimator Manager (9/2004)

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LARPLHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC

• Mission Statement
• Make more LHC luminosity earlier
• Use, develop and preserve unique US resources and
  capabilities in accelerator science and technology

• Accelerator Systems
• Instrumentation
• Collimation
• Accelerator Physics
• Nb3Sn Magnet Systems
• Program Management
• Beam and Hardware Commissioning
• Long Term Visitors to CERN
• Toohig Fellowships

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History of SLAC as member of LARP
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LHC AR at SLAC begins FY 2008

• LHC AR at SLAC Advisory Committee
• Alex Chao
• TWM
• Nan Phinney
• Tor Raubenheimer
• Uli Wienands

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LHC Accelerator Research at SLAC Department
Concept

• Participate in the LHC accelerator physics
  program
• by contributing in areas where SLAC has expertise
  experience
• enhance SLACs areas of core excellence
• collective effects, RF cavity design, collimation
  systems,
• educate SLAC staff on HEPs only energy frontier
  machine
• develop contact with next generation of
  accelerator physicists
• Use US LARP to coordinate validate RD plans
  and performance
• NOT independent bi-lateral SLAC/CERN planning
• Use US LARP funding when possible, especially to
  leverage SLAC labor through MS Travel
• Use SLAC ARD funds as available for programs LARP
  cannot fund
• ARD plan calls for 8 FTEs for last half of FY08

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LHC-AR Tasks People Funded by LARP in FY08
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LHC AR Tasks Proposed to LARP in FY08 Accepted
in LARP FY09 PlanFY08 Travel Funded by LARPFY08
Labor Funded by SLAC
LARP budget allocation in FY09 still TBD!!
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SLAC Concept for LHC Phase II Secondary
Collimators Improve LHC Impedance and Collimation
Efficiency
20 facets

• beam spacing geometrical constraint
• Length available 1.47 m flange - flange
• Jaw translation mechanism and collimator support
  base LHC Phase I
• 12 kW per jaw Steady State heat dissipation

Glidcop Cu Mo
Cu coolant supply tubes twist to allow jaw
rotation
Helical cooling channels 25mm below surface
Hub area
Cantilever Mo shaft _at_ both ends
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Cu Jaw-Cu Hub-Mo Shaft Design
2mm shaft-jaw gap gives x5 improvement in thermal
deformation over solid shaft-jaw design 1260 um ?
236 um (60kW/jaw, t12min) 426 um ? 84 um
(12kW/jaw, t60min) Rather than Cu, Moly shaft
improves Gravity sag x3 200 um ? 67
um Thermal bulge 30 339 um ? 236 um
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Status of RC Program

• Jaw support rotation mechanism COMPLETE (June
  2007)
• First full single jaw-hub-shaft unit COMPLETE
• Preliminary tests indicate performance in accord
  with FEA to 10

Final Jaw Braze 22 April 2008
Test Stand with External Heaters
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RC Program Plans

• FY2008-FY2009 Plan Complete RC1
• Finalize RF design
• Test a few new concepts to simplify machining
  brazing process
• Order parts for 2-3 new jaws copper mandrels, Mo
  shafts, Glidcop jaws
• Fab braze 2-jaws, 4-supports, RF features in
  new vacuum tank
• Metrology vacuum tests
• Mechanical motion tests on existing CERN system
• Ship to CERN in late 2009 for
• SPS Transfer Line Robustness Test
• LHC Beam Dynamics Test
• FY2010 and beyond
• If production decision made, provide engineering
  commissioning support

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Beam-Beam SimulationsAndreas Kabel (ACD)

• Goal
• Benchmark beam-beam simulations codes with RHIC
  experimental data and evaluate the LHC beam-beam
  performance with long-range and head-on beam-beam
  compensation
• PLIBB code
• PIC code, with MAD-X lattice input Intra-beam
  scattering
• for RHIC wire experiments and Electron lens

Example Beam Transfer Function for RHIC wire
compensator vs. simulation
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LHC LLRFJohn Fox , Claudio Rivetta, Themis
Mastorides, Dan van Winkle

• Why SLAC?
• PEP-II and LHC have same basic LLRF architecture
• SLAC Group has much unique expertise and well
  developed set of software tools developed for
  PEP-II that can be used to configure the LHC
  system, study it and improve it
• Progress in 2008
• Three multi-weeks trips in April, June 2008
• SLAC software model configured for LHC and
  interfaced to control system
• Near Term Plans
• 4 more person-weeks at CERN in FY08 for beam
  commissioning
• Data from closed loop LLRF system with beam
  present will be compared against model and
  changes to LHC hardware configuration suggested
• Expand model to include feedback longitudinal
  emittance dilution
• Eventually, develop theory programs to model
  the long-term (24 hr) behavior

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Sample LLRF Result
Open Loop Xfer Function from time-domain
excitation technique vs. model result (green)
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Transverse RF Feedback in SPS to Control Beam
Instabilities Produced by Electron Cloud
EffectsJohn Fox, Jiajing Xu with LBLCERN

• SPS Ecloud dynamics studies predict
• Horizontal - coupled-bunch behavior
• Vertical - single bunch-like instability
• 2008 Plan
• Measure quantify Ecloud effects on beam
  (instrumentation)
• Compare measurements with E cloud/beam models
• 2009 Plan
• Develop beam-FB simulation, evaluate possible
  feedback implementations.
• Propose a technical implementation develop
  Engineering Specs
• Proof of principle experiments technical RD
• Eventual possible LHC construction project item

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Transverse RF Feedback Measurements HW

• Measurements of x-y bunch structure in SPS will
  be made in August.
• Initial measurements taken parasitically in June
  show a high frequency structure on the beam, but
  have instrumental issues

Example of existing bunch-by-bunch FB (PEP-II,
KEKB,..) SPS and LHC needs may drive new
processing schemes and architectures
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Experimentation to Investigate Possible Use of
Crystals as High Efficiency Primary
CollimatorsAndrei Seryi, Tom Markiewicz , Bob
Noble, Shilun Pei, Jeff Smith, Gennady Stupakov

• Why SLAC
• Traditional expertise in collimation optics
  devices for accelerators with high power density
  beams
• Where
• T980 at FNAL Tevatron - now through 2010(?)
• CRYSTAL at the SPS now through 2009
• Possible future e/e- experiments at SLAC NLCTA
  and FACET
• Collaborators
• RD22 team from CERN-Italy-Russia (1990-2007 SPS
  H8 extracted line)
• Fermilab team (1993-98, 2005-2007 Tevatron)
• BNL Team (2005 RHIC)
• Status Plans
• Engineering plan for contributing Roman Pot
• Data analysis interpretation
• Application to electrons and possible production
  of photon beams

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Grooved Vacuum Insertion Test at the SPS for
Electron Cloud StudiesMauro Pivi, Lanfa Wang
with LBLCERN

• Electron cloud mitigation test chambers for SPS
  in prep
• SLAC is manufacturing two grooved insertions
• Metal folding razor blades techniques for 1mm
  max. height
• Installation Testing planned in summer 2008

Metal Folding Form multiple folds. EMEGA
Company, USA
Brazed-up Assembly Use individual razor type
foil blades
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LHC Crab CavityAndrei Seryi, Cho Ng, Zenghai Li,
Liling Xiao

• Crab Cavities for each beam and each IP are
  needed for any luminosity upgrade requiring a
  larger crossing angle
• SLAC ILC Crab Cavity design experience and ACD
  computational tools immediately applicable
• Crab Cavity collaboration of all LARP labs, CERN
  and others (KEK, RAL, JLAB,)
• SLAC responsibilities in areas of
• RF modeling of cavity coupler design
• HOM damping Multipacting Studies
• Thermal Mechanical studies with TEM3P code and
  and ANSYS cross-check
• Crab and collimation
• Overall coordination

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CERN PS2 (replacement for PS) studiesUli
Wienands et al

• Scope and budget are under discussion
• Synergies with the FNAL MI upgrade
• Interest from all 4 LARP labs
• 3 possible packages
• Intensity effects, instabilities
• RF system
• Tracking, nonlinearities, space charge, halos, H-
  injection

LARPLAUC DOE Review 19-20 June 2008
LARP Accelerator Physics - W. Fischer
Slide n 22
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Summary

• SLAC initially got involved with LHC accelerator
  research through LARP as a by-product of its
  Linear Collider collimator RD
• SLAC expertise and experience is highly relevant
  in many other areas and effort is sought after by
  LARP and by CERN
• These expanded activities are just beginning,
  with good early results, supported both by LARP
  and by SLAC
• SLAC is prepared to participate in a US LHC
  Luminosity Upgrade Project is participating in
  ongoing scope and schedule discussions