1. Injector Physics C.Limborg-Deprey Feb.8th 2006
Layout
Some Physics questions
110MV/m instead of 120 MV/m
Residual Magnetic fields in GTL
Commissioning plan

2. Injector Installation
Drive Laser May
Laser Launch July
Gun Region July
Accel Region June
Heater Region June
Wall Region October
Injection Region Aug-Nov 2006
Spect Region Aug-Nov 2006
Gun installation November 2006 Following Hot Test in Klystron Lab
Waveguide through wall and up penetration October 2005
Injector Commissioning Start December 2006

3. Gun to Linac Region (GTL)
Spectrometer
Courtesy J.Langton

4. GTL Design Normal incidence No second Valve in GTL
Low wakefield
two symmetric mirrors
<2% / for a x = 1mm
No second Valve in GTL
Wakefields computed, fine
Diagnostics units finalized
Gun Solenoid as close as possible to cathode
Bucking Coil added
cancels the 55 Gauss Bz field on cathode
Compatibility with gun bake + cathode removal
Mu-Shielding around ion pump under study
Possible remnant quadrupole field issues from QG01, BXS handled
PDR completed , FDR scheduled for February

5. From Accelerators to the wall region
L0b
L0b
L0a
L0a
Laser Heater Region
Courtesy P. Stephens

6. From Accelerators to the wall
L0a moved downstream by 8 cm
New tuning meets emittance requirement
Second Solenoid length reduced to Leff = 20 cm
higher Bfield for same focal length ok
Suppressed one out of 2 BPMs in L0a-L0b drift
4 inch Phase monitor fits in
Valve moved from L0a entrance to L0a-L0b drift
Mu-shield metal wrapped at all possible locations
Unfortunately not possible in GTL
Laser Heater Real Estate Issue
Space issue solved
removed YAG04, moved QE02
Laser Heater Installed in summer 2007

7. DogLeg 1 (DL1) Spectrometer Beamline (SAB)
ē to linac
DL bends
Spectrometer bend

8. Wall region/ DL1 / SAB Conclusion DL1 SAB
No space issues
SAB
YAGS1 (for alignment laser)
BXS accommodate 4 ports (X-Chamber)
Alignment laser line
Wire-Scanner Photo-multiplier port
OTRS1 depth-of-field issue solved (for slice energy spread)
Non-standard layout (see Diagnostics)
Radiation Shielding issue of cameras still pending
BPMS3 moved to high dispersion region (resolves  = )
Conclusion
Engineers can accommodate all required components
All Physics specs. finalized at this point, (no more modifications accepted)

9. If only 110MV/m available instead of 120MV/m? 1nC tuning
fwhm
[ps] r
[mm]
rf
[]
Bsol
[kG]
80
[m.rad]
proj [m.rad] z
110MV/m
10 ps
1.1
29.3
2.3385
0.95
1.05
0.968
10ps
1.2
28.3
1.0
1.12
0.935
12ps
30.3
2.3371
0.92
1.02
1.080
14ps
0.9
2.3308
0.88
0.97
1.157
120MV/m (Nominal)
32.3
2.5198
0.91
0.98
0.948

10. If only 110MV/m available instead of 120MV/m? 0.2nC tuning
fwhm
[ps] r
[mm]
rf
[]
Bsol
[kG]
80
[m.rad]
proj [m.rad] z
110MV/m
6.5ps
0.4
31.3
2.346
0.37
0.44
0.704
0.5
32.3
2.343
0.405
0.660
120MV/m (Nominal)
2.536
0.35
0.445
0.657
NB: those tunings assume a thermal = 0.6 mm-mrad per mm
(whereas the start-to-end simulations assumed a very conservative number of 1.2 mm-mrad per mm)

11. Residual Magnetic fields in GTL
Undesired quadrupole fields along GTL damage emittance compensation
Quadrupole components in solenoids
Remnant quadrupole fields in QG01 and BXG
Solenoid
QG01
QG01
BXG
BXG
Solenoid 2
Gun
L0a
Specifications
Integrated quad. S1
QG01
BXG S2
B/x * Leff [G] 2 3 6

12. Residual Magnetic fields in GTL
Int. Quad. 2.7 G
Example SOL1 :
5% growth in /
with 2.7 Gauss
Mitigation
Solenoid 1: shimming after magnetic measurement
QG01 : degaussing of magnet (procedure already established )
BXG : careful design
Solenoid 2: shimming after magnetic measurement

13. Injector Commissioning
Discussed every 5th week with LCLS physicists/operators group
Incorporated into large MS Project document for links
Discussed weekly inside Injector group
(Bong, Dowell, Limborg, Loos, Schmerge …)
Based on 2 shifts per day
Resource loading still to be refined
2 physicists per shift + 1 control person + 1 operator
guests
List of high level applications
Schedule Outline
Starts with RF Gun cold test (May 06) and hot test (summer 06)
First beam at 135MeV dump ( Dec.06)
7 months of characterization and optimization (through BC1)

14. December 06 
December 06 
Schedule
2006
2007

15. High Level Applications
Cathode characterization (QE, uniformity, Thermal emittance)
Steering in L0a
Longitudinal phase space measurements at BXG
Bunch length measurement with transverse RF deflector(s)
Emittance meas. (multi-wire, multi-OTR, quad-scan, slice)
Power-steering through beamlines, with corrector weights
Difference orbit fitting, including internal kick
Longitudinal phase space measurement at BXS
Tomography (Longitudinal and Transverse) …

16. Example of procedure (1): Steering in L0a
Solenoid mispositioning
250 m, 250 rad
Earth Magnetic field 2mrad/m vert.
No space for mu-metal shielding in GTL
By ~ 0.35 G
Bx ~ 0.12 G
Offset as large as 4mm, 4 mrad, without steering
Solenoid
SC0
SC1
SC2
Gun
BPM2
BPM3
L0a
BPM5

17. Example of procedure (1): Steering in L0a
L0a solenoid off
Orthogonal knobs at SC0
BPM2, BPM3,BPM5
SC0 and SC1 adjusted to steer in L0a to better than
100m
120 rad
Scaling of SC0 orthogonal knobs with solenoid implemented in software
Solenoid
SC0
SC1
SC2
Gun
BPM2
BPM3
L0a
BPM5

18. Example of procedure (2): Longitudinal Phase space measurements
Direct Longitudinal Phase Space measurement
Transverse deflecting cavity  y / time correlation
(with V < 0.5MV/m, 0.5mrad over 10ps )
Spectrometer  x / energy correlation
Longitudinal Phase Space at TCAV
Spectrometer Screen

19. resolution < 5keV
5keV -> 40 keV will be easily measurable

20. Conclusions Physics Requirements have been finalized
Iteration (Physics/ Mechanical Designer) works well
Converged for GTL, L0a-L0b drift, Matching Section
Nearly finalized for SAB, Laser Heater region
Physics issues identified
Importance of Earth magnetic field
Control of residual quadrupole fields
Commissioning schedule under completion
Applications to be written

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