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

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

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

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

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

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

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

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

Gun Spectrometer Mode1: No quadrupole on Bending magnet  = 84.46 degrees  = 26.4 degrees Resolving power xo atYAG1 = 1.78 mm (for nominal case, 1nC) xoR11<  R16   > 2.3.10-3  E > 12 keV Technical Review, November 3, 2003 Cécile Limborg, SLAC

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

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

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

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

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

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

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

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

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

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

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

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

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