Accelerator Physics Steve Peggs, BNL

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Accelerator PhysicsSteve Peggs, BNL

• Recent activities
• CERN LHC Upgrade Task Force
• Phase Locked Loop workshop
• LARP AP topics
• Integration issues
• Beam experiments
• Summary

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Recent ActivitiesCERN LHC Upgrade Task Force
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LHC IR Upgrade Collaboration meeting, CERN, March
2002
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Phase Lock Loop workshop, June 10 11,
CERNCERN(many) BNL(5) DESY(2) GSI(2)

• The size of the LHC stresses the early
  establishment of feed forward and feed back on
  tunes and chromaticities up the energy
  acceleration ramp.
• This requires Phase Lock Loop (PLL)
  instrumentation, similar to the systems now/soon
  functioning in RHIC, HERA-e/p, Tevatron
• Full confidence in PLL based operation is also of
  vital interest to a future US hadron machine
• reduce tight tolerances on magnet performance
• reduce magnet costs.

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• Many accelerators have experimented with PLLs,
  finding it difficult to achieve robust and
  reliable performance
• It is necessary to develop more confidence with
  the mathematical underpinnings, including
  filters, DSP code, and beam dynamics modeling, et
  cetera.
• Conjecture need to develop confidence through a
  joint Instrumentation and Accelerator Physics
  effort.

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• Eg, 4 methods to measure chromaticity up a ramp
• Fast phase modulation (f gtgt fs) Bruning (CERN)
• Slow phase mod ("traditional") Tepikian (BNL)
• Slow PM (vector analyzer) McGinnis (FNAL)
• Head-tail Schmickler(CERN)
• Four efforts led by 2 physicists and 2 engineers
• An apples to apples comparison is possible?
• Note special BNL/CERN relationship (MoU)

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Traditional slow modulation at RHIC (Tepikian)
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LARP AP topicsThe Beam-Beam Interaction

• Coherent modes seen for first time (hadron) at
  RHIC
• Tevatron Run 2 faces fundamental beam-beam issues
• Electron lens compensation (FNAL)
• Wire compensation (CERN)
• RHIC is a flexible test bed

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Electron Cloud

• The electron cloud effect is expected to be very
  important at the LHC
• Currently a hot bed of activity, both hadron and
  electron
• There are indications that electron cloud is
  important at RHIC (as well as APS, SNS, PEPII,
  KEKB, ...)

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Nonlinear dynamics

• Nonlinear dynamics emain, as ever, a fundamental
  limit to storage ring performance
• Analysis tools (such as SUSSIX) have developed
  significantly since SSC/E778 days
• Availibility of AC dipoles promises a new era of
  linear and nonlinear dynamics studies
• LHC considers an AC dipole, RHIC is commissioning
  two (H V)
• Another prime candidate for joint experimentation

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Interaction Region Compensation

• The LHC IR correction scheme is similar to that
  at RHIC
• Ongoing correction studies at RHIC are part of
  machine development time
• These issues are enhanced in LHC IR upgrade
  scenarios

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Energy deposition and Beam Loss Scenarios

• The stored energy of the LHC beam - 350 MJ - is
  in a new parameter regime
• These issues will be even more extreme in any
  VLHC
• Fermilab has unique resources in support of both
  unavoidable energy deposition, and also accident
  scenarios
• Accident scenarios are currently under intense
  scrutiny at LHC
• IR Upgrade scenarios also push stored energy and
  energy deposition issues

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Heavy Ion Operation

• The design goals of the LHC also include heavy
  ion collisions
• Special attention is needed with
• Intra Beam Scattering
• Rest gas ionization
• Collision of different species
• Schottky spectra are much enhanced with heavy ion
  "macroparticles"

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Remote Operations

• Remote Operations is but one overlapping
  component of the Global Accelerator Network (GAN)
• In ICFA, GAN is dominated by the Linear Collider
  enthusiasts
• It is crucial that Remote Operations activities
  resist Linear Collider hegemony! SNS, LHC, ...

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Remote Operations

• Typical (sociological) question what gives the
  remote crew the "authority" to run a shift on the
  local accelerator?
• One answer send the local "crew chief" to the
  remote Virtual Control Room.
• Does this extrapolate to sending Dave McGinnis to
  the SL control room when Oliver Bruning et al
  want to participate in Fermilab PLL studies???

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http//www.agsrhichome.bnl.gov/RemOp
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Integration issues

• Lab to lab
• Physicist to Engineer
• Across LAPAC org chart boxes
• With Accelerator (not Magnet) Physicists outside
  the 3 US labs

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SUMMARY

• LHC IR Upgrade report (almost out!) major long
  term hardware plan, again with a mix of Magnet
  () and Accelerator activities
• Phase Lock Loop activities are non trivial, with
  the potential to integrate labs and personnel in
  a new way. Eg, 4 ways to measure chromaticity.
• The LHC has pushed some topics into the
  limelight
• Energy deposition
• Beam loss scenarios
• Electron cloud

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• Other fundamental topics are still with us
• Beam-beam (now strong effects, compensatio)
• Nonlinear dynamics ( SUSSIX, AC dipole, ..)
• Interaction Region compensation
• Relatively new topics offer exciting challenges
• Phase Lock Loops
• Remote Operations
• LARP Accelerator Physics is more independent of
  hardware development than in Phase I
• Expected Level of Effort is 6 FTEs by 2006