Specifications for beam diagnostics C

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Specifications for beam diagnostics Cécile
Limborg, SLACNovember 3, 2003

• Thermal emittance measurement
• Gun Spectrometer
• Straight-Ahead Spectrometer
• Direct measurements
• With transverse deflecting cavity
• Conclusions

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Gun Spectrometer
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Imaging on first screen

• Uniformity of emission
• Thermal emittance measurement Solenoid scan
• Optimal screen position ( z gt 50 cm)
• Solenoid scan (operating range) linear up to
  3.4kG

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Thermal emittance measurement

Example of SDL Data
Method
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Gun Spectrometer
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Gun Spectrometer measurement

• Measurements
• Energy
• Absolute energy
• alignment using laser (YAG1 to entrance linac)
• spectrometer field calibration
• Correlated Energy Spread for all charges
• Uncorrelated energy spread for low charges
• Introducing a time-energy correlation (injection
  phase or unbalance)
• Slice thermal emittance
• Relay imaging system from YAG1 to spectrometer
  screens
• Point-to-point imaging
• Uniformity of line density

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Gun Spectrometer measurement

• Modes of operation
• Nominal (quads off) point-to-point in both
  planes
• Resolution 10 keV
• Drawback large beam size on screen
• Smaller beam size (quads on)
• Resolution of 10keV
• Good energy resolution and small beam size high
  R16 , low R11, zero R12 on secondary screen
• Resolution of 3 keV
• Small beam sizes

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Gun SpectrometerMode1 No quadrupole on
Bending magnet ? 84.46 degrees ? 26.4 degrees
Resolving power ?xo atYAG1 1.78 mm (for
nominal case, 1nC) ?xoR11lt ?? R16 ? ?? gt
2.3.10-3 ? ?E gt 12 keV
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Gun SpectrometerMode1 No quadrupole on
At IMAGE (view screen 1, 1.5 diameter)
At SOURCE Nominal 1nC, 150keV Correlated energy
spread
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Gun Spectrometer- Mode1 No quadrupole on
Low charge No correlated energy spread (by
adjusting ?inj or Field balance)
Resolution about 10 keV
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Gun Spectrometer- Mode 2 quadrupoles on Screen
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Resolution of 10 keV smaller beam size
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Gun Spectrometer- Mode 3 quadrupoles on Screen
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Resolution of 3 keV small beam size
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Gun Spectrometer Can Measure Uniformity of Line
Charge Density

• can resolve a minimum of 5 modulation at gun
  exit

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End Spectrometer

• 35 ? bending angle dipole magnet
• Point-to-point imaging of the 75 ?m waist (OTR5)
  at 4.6 m from entrance spectrometer

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End Spectrometer

• Point-to-point imaging of the 75 ?m waist (OTR5)

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End Spectrometer - Quadrupoles on

• Various modes of operation with point-to-point
  imaging in both planes
• R34 R12 0 , R16 -3 R11
• Nominal tuning less than 10keV resolution
• Reduced to 5 keV if beam size reduced to 37 ??m
  at waist

good resolving power, ?xoR11lt ?? R16
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End-Spectrometer Used with Transverse Cavity

SOURCE Waist
IMAGE
Direct representation of Longitudinal Phase Space
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Resolve less than 10 keV
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CONCLUSIONS

• Thermal emittance
• Standard 3 screen emittance available
• Gun Spectrometer design finalized
• Absolute energy, energy spread
• Uncorrelated energy spread for low charges
• Slice thermal emittance
• Longitudinal uniformity
• End Spectrometer design finalized
• Absolute energy
• Slice emittance
• Close to 5 keV resolution
• Direct measurement of phase space

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LIST OF REFERNCES

• Diagnostics
• 6 Gun Spectrometer C.Limborg , March 03
  updated October
• 7 Gun Spectrometer, Revision 1, C.Limborg,
  LCLS-InJTech Note
• 8 Gun Spectrometer, Revision 2, C.Limborg,
  LCLS-InJTech Note
• 9 Straight-Ahead Spectrometer, C.Limborg,
  April 03, LCLS-InJTech Note
• 10 Straight-Ahead Spectrometer, Revsion 1,
  C.Limborg, Oct03, LCLS-InJTech Note

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