KEK Linac Operation (Some Experiences)

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KEK Linac Operation(Some Experiences)

• Kazuro Furukawa
• July 17, 2006
• Mini Workshop on BEPCII Linac

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Contents

• In KEK Linac Commissioning
• Tools to Test Ones Assumption/Hypothesis
• Correlation Study
• Tolerance Study, and How, Dependency on
  Parameters
• Time-series Multi-parameter Analysis
• Stability Feedback System as a Anomaly Detector
• Resolving one Instability makes easy to Find
  Another
• rf System
• rf Monitoring
• BPM Reading
• Air-Conditioner On/off Operation and Direct
  Air-flow
• Timing Jitter for Gun Against Sub-harmonic
  Bunchers
• Direction of Gun Relative to Solenoids
• Achromatic (Dispersion) and Isochronous (R56)
  Correction at J-ARC, Understanding Dispersion
• Energy Spread Monitor, SOR, 8-Electrode,
  Wire-scanner
• Archiving
• Beam-switching and Virtual-machine Archiving
• Achieved Energy/Orbit/Angle Stabilities
• Cabling

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Documents

• Unofficial Incomplete Report on Linac
  Commissioning
• In Japanese (sorry)
• http//www-linac.kek.jp/linac-com/report/comrep97.
  pdf
• Slightly More Official Report
• In NIM A 499., p167
• http//www-linac.kek.jp/linac-com/report/nim-kekb-
  linac.pdf

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Items

• Tools to Test Ones Assumption/Hypothesis
• Simple Programming Tool is Necessary
• Has Links to Machine Controls, Database, Archive,
  etc
• Has GUI Capability
• We cannot Handle Large Machine without a Help
  from Computer
• Basic Tools
• Save/Load Basic Parameter Sets
• Active and Passive Correlation Plots
• Calibration Tools for Instrumentations
• Simple Stabilization Tools
• etc.
• SADscript, Python/Tk and Tcl/Tk are Used at
  KEKB/Linac

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• Correlation Study
• Plotting Between Multiple Parameters
• by Changing Certain Parameter Actively
• by Observing Values During Beam Operation
• Synchronous Data Acquisition Preferable
• Fitting is Also Nice
• May Find Correlation
• May Optimize Parameters

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• Tolerance Study, and How, Dependency on
  Parameters
• For example, (Single-) Parameter Tolerance to
  Keep 90 of Optimal Beam at Positron Target
• By Scanning Parameters One by one
• With Multi-Parameter Drifts, Much Tighter Limits
• If a Certain Parameter is not at Optimal Value,
  The Tolerance of Another Parameter can be Much
  Smaller
• Good Reference to Consider the Beam Stability

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• Time-series Multi-parameter Analysis
• Often FFT or Correlation Analysis are not
  Powerful Enough to Represent
• Time-series Data with Changing Frequency
• Multi-parameter Dependencies
• There Seem to be Several Methods
• At Least It was Useful to Analyze Dependencies at
  Spring-8 between Power-line, Air- and
  Cooling-water Temperature, and Beam
• Singular Value Decomposition (SVD) Analysis
• Can be Used to Find Correlation
• For Example
• If we Find 5 Good Singular Values For 10 BPM
  Values Starting from Gun, The Source of
  Fluctuation may be at the 6th BPM
• Down-hill Simplex
• Somewhat Brute-force, but

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• Stability Feedback System as an Anomaly Detector,
  etc
• Feedback Tool is a Source of Valuable Information
• Feedback Signal can be an Anomaly Detector
• If We scan a Certain Parameter, we want Another
  Parameter Stable to Continue the Beam Study
• Even If We are satisfied with a Certain
  Parameter, It is Still Good to have Feedback for
  Above Purpose
• Resolving one Instability May often Reveals
  Another
• Step-by-step Resolution !!!

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• Understanding of Our Own System
• rf System
• Still Most Important to Our System
• rf Monitoring
• Monitors Down to 0.05 Degree in Phase, 0.02
  Percent in Amplitude
• Keeps 0.1degree and 0.1 Percent
• BPM Reading
• Every Beam Pulse, Synchronous Reading, Resolution
• Air-Conditioner On/off Operation and Direct
  Air-flow
• Timing Jitter for Gun Against Sub-harmonic
  Bunchers
• Direction of Gun Relative to Solenoids

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• Achromatic (Dispersion) and Isochronous
  Correction at J-ARC
• Synchronous Measurement with Many BPM and Streak
  Camera
• Dispersion (R16, R36) and Second Order (R166,
  R366) Correction
• Then Isochronicity (R56) Correction
• Understanding Dispersion Effect to Beam Stability

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• Achieved Energy/Orbit/Angle Stabilities
• Energy 0.03 (rms),
• Energy Spread Monitor, SOR, 8-Electrode,
  Wire-scanner
• Archiving
• Beam-switching and Virtual-machine Archiving
• Cabling
• Database Handling
• Linac Tends to have Less Priority in Machine
  Studies

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Increase of the Luminosity
KEKB and Linac Accelerator
Feb.2005 Continuous Injections
May.2000
Apr.2003 Dual Bunch e
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For BEPCII Linac Commissioning

• Multi-bunch Operation
• Sub-harmonic bunchers
• Sinchronization
• Difficulty of Asynchronous Multi-bunch Beam

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KEKB Commissioning Groups
KEKB and Linac Operation

• Formation of Commissioning Group (KCG)
• Linac Commissioning (LCG)
• 7 from Linac
• 10 from Ring
• KEKB Ring Commissioning Group (KCG)
• All LCG
• 20 from Ring
• Several from Detector (BCG)
• Commissioning softwarebase was formed during
  Linac Commissioning (1997)
• Tcl/Tk, SAD/Tk , Python/Tk

KEKB Commissioning Group

Linac Commissioning Group
Linac
KEKB Ring
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SADScript
KEKB and Linac Operation

• Mathematica-like Language
• Not Real Symbolic Manipulation (Fast)
• EPICS CA (Synchronous and Asynchronous)
• CaRead/CaWrite , CaMonitor , etc.
• (Oracle Database)
• Tk Widget
• Canvas Draw and Plot
• KBFrame on top of Tk
• Data Processing (Fit, FFT, )
• Inter-Process Communication (Exec, Pipe, etc)
• System , OpenRead/Write , BidirectionalPipe
  , etc.
• Greek Letter
• Full Accelerator Modeling Capability
• Also Used for non-Accelerator Applications

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SADScript
KEKB and Linac Operation

• Example
• FFS
• wKBMainFrame"w1",fm,Title-gt"t1"
• DisplayFunctionCanvasDrawer
• W1Framefm
• c1Canvasw1,Width-gt600,Height-gt400,
• Side-gt"top"
• CanvasWidgetc1
• data 0,0, 1,1, 2,5, 3,8, 4,10,
  5,7, 6,4, 7,2, 8,0, 9,2
• fit FitPlotdata,a Sinx b c d, x,
  a,5,b,1,c,1,d,5,
• FrameLabel-gt"X","Y"
• phase StringJoin"Phase ", (c/.fit1)
  180/Pi, " Deg."
• f1KBFComponentFramew1,Add-gtKBFTextText-gtphase
  
• TkWait
• Exit

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KEKB Alarm Panel
KEKB and Linac Operation

• KEKB Alarm Main Panel covers Linac Alarms as
  well. 10,000 Records are Monitored in One
  Panel. Detailed alarm information/history is
  available in a separate panel

Linac
Ring
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Beam Optics Panels in SAD
KEKB and Linac Operation

• Beam Optics Matching and Optimization
  Panels in SADscript

• Some Parameters goesthru EPICS Gateways, others
  directly to Linac

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KEKB Operation Panel Examples
KEKB and Linac Operation

• Tune Measurement
• and Tune Changer

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Virtual Accelerator in KEKB
KEKB and Linac Operation

• Tune/Optics Server
• Keep A Model of Real Accelerator
• Can Change Tune, Chromaticity, etc, on Request
• by Other Panels
• Act as a Virtual Accelerator

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Example Virtual Accelerator
KEKB and Linac Operation

• Virtual Accelerator may Provide
• the Both Fake Steerings and Fake BPMs
• Maybe with Simulated Errors/Noises
• Orbit Correction Application may Work
• On Those Fake Information

Operation Panel Orbit Correction
Real Acc. Optics Steerings BPMs Noises
Virtual Acc. Optics Steerings BPMs Errors
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Thank you
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