1. Undulator X-ray Diagnostics P. Ilinski, E. Gluskin and N
Undulator X-ray Diagnostics P. Ilinski, E. Gluskin and N. Vinokurov, Argonne National Laboratory April 24, 2002
Purpose of the LCLS X-ray Diagnostics
Undulator X-ray Diagnostics
Diagnostics setup
On-axis diagnostics
Off-axis diagnostics
Conclusions
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

2. Purpose of undulator x-ray diagnostics
The x-ray diagnostics consists of tools for measurement and analysis of the spectral and spatial characteristics of spontaneous and SASE radiation along the undulator line
The main goal is to measure the absolute flux of x-rays as a function of the distance along the undulator line
Furthermore, the diagnostics permits measurements of the spatial distribution of spontaneous and SASE radiation along the undulator line
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

3. X-ray diagnostics setup
X-ray diagnostics will be located in the last
break of each undulator cell, it includes:
- x-ray diamond-crystal monochromator
- PIN diode detectors and attenuation
filters for absolute flux measurements
- CCD detectors for spatial measurements
CCD
CCD
PIN diode
l = 2.9 Å
Filters
Undulator cell
l = 1.5 Å
Diamond
crystal
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

4. Absolute spectral flux measurements
Si PIN
diode
Filters
l=2d·sinq q q
Diamond (111) crystal,
200 µm thick
Bandwidth of diamond
(111) monochromator is
∆E/E=6·10-5
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

5. Absolute spectral flux measurements
Measurements of the total flux growth rate along the undulator line is valuable for study of the development of the SASE process
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

6. Spectral intensity measurements
dE/E, FWHM
Diamond (111)
6·10-5
Spontaneous,
four undulator cells
5·10-3
SASE
3·10-3
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

7. Spectral intensity measurement setup
CCD
Long distance microscope
(INFINITY K2)
Glass vacuum window
Scintillation crystal
(YAG:Ce, CdWO4)
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

8. Spatial intensity distribution of spontaneous radiation after first undulator cell
CCD
Single electron
Emittance included
l = 1.5 Å
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

9. Spatial intensity distribution of spontaneous radiation after four undulator cells
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

10. Spatial distribution of spontaneous radiation after four undulator cells vs initial trajectory angle missteering
x´ = 0
x´ = 2 µrad
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

11. Spatial distribution of spontaneous radiation after four undulator cells for different initial trajectory angle missteerings
Trajectory kick before undulator #1
Trajectory kick after undulator #10
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

12. Off-axis undulator x-ray diagnostics
Two undulators,10 µrad missteering
l = 2.9 Å
Diamond (111)
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

13. Conclusions
X-ray diagnostics will provide direct measurements of absolute spectral flux and spatial properties of spontaneous and SASE radiation along the undulator line
It will meet the following requirements:
one-shot sensitivity for all types of spectral, flux, and spatial measurements
many orders of magnitude dynamic range
accuracy of the absolute flux measurement better than 10%
few microradian sensitivity for trajectory straightness
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS

14. Computation Spatial/spectral computation were performed using codes:
one cell - SRW (O. Chubar, P. Elleaume, ESRF)
long undulator line - APS/XFD code
Crystal reflectivity: Inpro (C. Vettier, ESRF)
LCLS DOE Review, April 24, 2002
P. Ilinski, et al., ANL, APS