1st LHC Emittance Workshop

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1st LHC Emittance Workshop

• 3rd and 4th of July 2000
• CERN

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• The transparencies of the Workshop presentations
  can be found at
• http//emittanceworkshop.web.cern.ch/EmittanceWork
  shop/Prog.work.htm

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Motivation of the workshop

• The reference instrument considered is the LEP
  type Wire scanner
• The main operational instrument considered is a
  Synchrotron Radiation monitor of BEUV type BUT
  there is not enough light available below 2 TeV
  so thoughts were given to all kinds of monitors
  and an extensive RD program was started with
  tests on the SPS
• This RD program has to be reviewed now and
  confronted to outside experience as
• it is not conceivable to install all these
  instruments on LHC
• the available effort will not permit to bring all
  the instruments to an operational level

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Purpose of the E workshop

• Get the user needs and wishes expressed in a open
  forum with instrumentation specialists
• Make the status of the RD carried out in the
  past years at CERN
• Get the catalog of the E instrumentation used in
  the other major proton labs
• Get the real performance of the E instrumentation
  in the other labs
• Confront the results and potential of the
  detectors with the demands
• Select the detectors to be developed further and
  to be proposed for LHC
• Identify the areas where a collaboration with
  other laboratories or institutions should be
  encouraged

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Program of 1st day

• Morning session
• Purpose of the workshop R. Jung
• Developments undertaken for LHC instrumentation
• Synchrotron Radiation monitors L. Cadet
• Rest Gas Profile monitors/IPM C. Fischer
• Luminescence monitors A. Variola
• Beam Gaz Ionisation monitor A. Arauzo
• Pencil Ion Beam Scanner J. Bosser

• Afternoon session
• PS quadrupolar pick-up A. Jansson
• Moving BPMs for E B. Dehning
• PS luminescence monitor tests M. Plum
• Emittance instrumentation in major proton
  laboratories
• LANL E instrumentation J.D. Gilpatrick
• RHIC IPM R. Conolly
• DESY E instrumentation K. Wittenburg
• Fermilab E instrumentation (A. Hahn)

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Program of 2nd day

• Morning session
• Needs seen by Operations and Accelerator Physics
• Needs Specs seen from OP G. Arduini
• Needs Specs seen from AP W. Herr
  
• 1st Discussion session J.P.
  Koutchouk

• Afternoon session
• Final discussion and Conclusions from the
  workshop
• 2nd Discussion session J. Bosser
• Conclusions H. Schmickler

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OP Needs and Specs G. Arduini

• Transfer 2 dimensional
• batch and bunch modes
• few precision
• 5 monitors
• Ring 2 dimensional for coupling
• batch and bunch modes
• single turn and multi turn (1-20ms)
• precision 1
• at least 2 monitors at D 0 and D ? 0
• Transfer - Ring overlap OTRs
• General reliable, available in good and bad
  days, robust, user-friendly,
• good interface to the user on-line DB,
  consistency PS-LHC

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AP Needs and Specs W. Herr
Transfer 1 on beam size, beginning and end of
line 5 10 9 to 5 10 13, single bunch or
batch Injection 1-2 on beam size, turn-by-turn
over some turns, can be interceptive Circulating
set up small blow-up acceptable filling
non intercepting ramp continuous, real time
and precise but not both simultaneously bunch
to bunch selected representative bunches (for
pacman) High energy non intercepting,
continuous absolute calibrated better
than 5 on beam size, relative and absolute
single bunches but not turn by turn, all bunches
if feasible Instabilities bunch to bunch turn
by turn of large beam size variations 1 to
10 dipole and quadrupole modes to be
distinguished TV display and processed
data Lifetime Tails measurement can be
destructive, sensitive to less than 10- 4 of a
bunch
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Reviewed Profile Monitoring RD at CERN

• Matching Monitors
• PS quadrupolar BPM
• SPS OTR screen (not reviewed)
• Monitors producing a beam profile
• SR monitors D2 in IP5 and wiggler in IP4 2 D
  images
• Rest Gas IPM 1D images Top and Side
• N2 Luminescence 1D images
• Monitors producing indirectly a profile or a
  quantity related to beam size
• Ion Beam Scanner deflection of pencil
  beam/curtain or shadow induce profile
• Beam Gas Ionisation Profile monitor cut-off
  gives ellipticity/sizeround beam
• Quadrupolar BPM
• Movable BPM

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Slides from the workshop presentationshttp//emit
tanceworkshop.web.cern.ch/EmittanceWorkshop/Prog.w
ork.htm

• Status of RD work at CERN
• Matching monitor
• A. Janson Quadrupolar Pick Up
• Imaging monitors
• L. Cadet Synchrotron Radiation monitors BSRT
  and Wiggler
• C. Fischer Rest Gas Ionisation monitor IPM
• A. Variola Luminescence monitor
• Non imaging monitors
• A. Arauzo-Garcia Beam Gas Ionisation Profile
  monitor
• J. Bosser Pencil Ion Beam Scanner

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Results from the SPS OTR Matching Monitor (1998
)(not presented at the E workshop)
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IP4 Wiggler for cst field (6T) and cst bump (1.3
T to 6 T) light extractions(proposal, not
presented at the E workshop)
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Signal Collected in 1 turn
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Signal Collected over 20 msi.e. 1 TV frame or
225 LHC turns
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Matching of demands with tested monitors

• Transfer OTR screens match best the demand
• Injection and Matching
• OTR matching screen à la SPS satisfies the
  precision requested
• IPMe- will be evaluated in the SPS on t-b-t
  mode for the matching monitoring
• Quad PU à la PS will be useful as a watchdog
  during filling to be tested in SPS
• Circulating beam
• All imaging monitors work for 20ms integration of
  nominal beam
• The 6 T Wiggler can give acceptable data for the
  pilot in t-by-t non-interceptively
• The only monitor to give good data t-b-t for the
  Pilot is the OTR screen (Matching)
• Collision optics (7 TeV)
• The D2 SR monitor will provide the data for the
  pilot and the nominal beam
• Instabilities
• The D2 SR monitor will provide data for the pilot
  and the nominal beam
• the quad PU can be useful, but wont give an
  image
• Tails A slow moving Wire Scanner can probably
  match the demand

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Slides from the workshop presentationshttp//emit
tanceworkshop.web.cern.ch/EmittanceWorkshop/Prog.w
ork.htm

• E Instrumentation in other proton labs
• D. Gilpatrick, LANL
• A. Hahn, Fermilab
• R. Conolly, BNL
• K. Wittenburg, DESY

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Lessons from the other Proton Labs

• Nobody is claiming a 1 precision!
• We have not forgotten any obvious and/or
  excellent monitor
• It is important to provide the user with simple
  to understand and operate, day to day reliable
  instruments
• The described monitors have problems and dont
  always perform every day as described (even at
  10!)
• The used scenarios are similar to those
  used/considered at CERN

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Our Conclusions (1)

• The 1 demand has never been achieved and will be
  extremely difficult to satisfy. It has to be
  re-evaluated with the users and also be better
  defined
• An OTR screen can be considered for the t-b-t
  (100 t?) observation of the pilot
• The IPM will be tested in 2000 in the SPS for the
  matching monitoring
• A quadrupolar PU from the PS will be installed
  ASAP in the SPS to gain experience with it and
  evaluate the complementarity with the OTR monitor
• The machine optics will have to be measured to
  better than the absolute precision required on
  Emittance
• The Linear Wire Scanners will be the reference
  monitors to be placed close to the other monitors
  for their calibration at lower than nominal
  intensity (1 1013)

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Our Conclusions (2)

• As the imaging monitors can best fulfill the
  demands of AP and OP, it is decided to stop the
  RD on the other monitors in SL/BI
• RD will be carried on for the SR and IPMe-
  monitors
• It is proposed to study the Wiggler SR monitor
  layout for using both the 6T and the constant
  bump configurations and submit this to the ruling
  committees, if the t-b-t option at 450GeV for the
  nominal/pilot bunch is important for LHC
• The collaboration with DESY where a tail monitor
  system has been under development with the CERN
  Wire Scanners will be intensified on this subject
• The development of a rad-hard next generation
  image detector will have to be launched ASAP with
  industry if no acceptable detector for the LHC
  environment and applications can be found on the
  market within a short time

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Our Conclusions (3)

• It is proposed to install in IP4 a combined
  set-up of IPM/Luminescence monitors as a back-up
  to the SR monitors which will be delicate to
  align and tune, in order to have simple but
  reliable instruments able to operate on Day1.
• The IPMe- will require an acceptable pressure
  bump (5 10-7 torr) to measure with some precision
  a nominal batch on a t-b-t basis. It may have
  space charge problems at the higher densities and
  has its most fragile component (MCP) in the LHC
  vacuum. A proper design will be done in 2001 and
  tested in the SPS.
• The luminescence monitor will only see a pilot
  bunch in TV mode if the pressure bump is limited
  to 5 10-7 torr. It is a comparatively cheap and
  robust monitor as it has no component in the LHC
  vacuum. It should not suffer too much from space
  charge problems, and doesnt need any further
  development.