1. Specifications for beam diagnostics Cécile Limborg, SLAC November 3, 2003
Thermal emittance measurement
Gun Spectrometer
Straight-Ahead Spectrometer
Direct measurements
With transverse deflecting cavity
Conclusions
Technical Review, November 3, 2003
Cécile Limborg, SLAC

2. Cécile Limborg, SLAC Cathode Load Lock RF Photocathode Gun
Low Energy Diagnostics
SLAC 3-m Accelerator Sections
EO Diagnostic (Bunch Shape & Timing)
Transverse RF Cavity (Emittance & Energy)
Wire Scanner, typ.
Laser Heater Undulator
Straight Ahead Spectrometer & Diagnostics
DL1 Bend
Shield Wall
Technical Review, November 3, 2003
Cécile Limborg, SLAC

3. Gun Spectrometer Cécile Limborg, SLAC
Technical Review, November 3, 2003
Cécile Limborg, SLAC

4. Imaging on first screen
Uniformity of emission
Thermal emittance measurement: Solenoid scan
Optimal screen position ( z > 50 cm)
Solenoid scan (operating range) : linear up to 3.4kG
Technical Review, November 3, 2003
Cécile Limborg, SLAC

5. Thermal emittance measurement
Example of SDL Data
Method
Technical Review, November 3, 2003
Cécile Limborg, SLAC

6. Gun Spectrometer Cécile Limborg, SLAC
Technical Review, November 3, 2003
Cécile Limborg, SLAC

7. 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
Technical Review, November 3, 2003
Cécile Limborg, SLAC

8. 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
Technical Review, November 3, 2003
Cécile Limborg, SLAC

9. Gun Spectrometer Mode1: No quadrupole on
Bending magnet
 = degrees
 = 26.4 degrees
Resolving power
xo atYAG1 = 1.78 mm (for nominal case, 1nC)
xoR11<  R16   >
 E > 12 keV
Technical Review, November 3, 2003
Cécile Limborg, SLAC

10. Gun Spectrometer Mode1: No quadrupole on
At IMAGE
(view screen 1, 1.5” diameter)
Gun Spectrometer Mode1: No quadrupole on
At SOURCE:
Nominal 1nC,
150keV Correlated energy spread
Technical Review, November 3, 2003
Cécile Limborg, SLAC

11. Gun Spectrometer- Mode1: No quadrupole on
Low charge
No correlated energy spread
(by adjusting inj or Field balance)
Resolution about 10 keV
Technical Review, November 3, 2003
Cécile Limborg, SLAC

12. Gun Spectrometer- Mode 2: quadrupoles on – Screen 1
Resolution of 10 keV +smaller beam size
Technical Review, November 3, 2003
Cécile Limborg, SLAC

13. Gun Spectrometer- Mode 3: quadrupoles on – Screen 2
Resolution of 3 keV
+ small beam size
Technical Review, November 3, 2003
Cécile Limborg, SLAC

14. Gun Spectrometer Can Measure Uniformity of Line Charge Density
can resolve a minimum of 5% modulation at gun exit
Technical Review, November 3, 2003
Cécile Limborg, SLAC

15. End Spectrometer 35  bending angle dipole magnet
Point-to-point imaging of the 75 m waist (OTR5) at 4.6 m from entrance spectrometer
Technical Review, November 3, 2003
Cécile Limborg, SLAC

16. End Spectrometer Point-to-point imaging of the 75 m waist (OTR5)
Technical Review, November 3, 2003
Cécile Limborg, SLAC

17. 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, xoR11<  R16
Technical Review, November 3, 2003
Cécile Limborg, SLAC

18. End-Spectrometer Used with Transverse Cavity
SOURCE
Waist
IMAGE
Direct representation of Longitudinal Phase Space
Technical Review, November 3, 2003
Cécile Limborg, SLAC

19. Resolve less than 10 keV Cécile Limborg, SLAC
Technical Review, November 3, 2003
Cécile Limborg, SLAC

20. Standard 3 screen emittance available
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
Technical Review, November 3, 2003
Cécile Limborg, SLAC

21. 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
Technical Review, November 3, 2003
Cécile Limborg, SLAC

22. BACK- UP SLIDES Cécile Limborg, SLAC
Technical Review, November 3, 2003
Cécile Limborg, SLAC