1. LCLS Instrument Development
John Arthur
SLAC

2. from the Charge to the Workshops
In each of the four identified science areas establish a priority list of desired user experiments...
Identify important x-ray beam parameters to address the envisioned science opportunities, such as photons per pulse, pulse length, 120-Hz-based pulse trains, bandwidth and spectral purity, polarization, coherence…

3. this talk
An attempt to enable the discussion of exciting experiments by presenting some basic boundary conditions and ideas that have already been put forward concerning:
LCLS FEL sources
LCLS instrument capability
LCLS facility layout

4. LCLS growth LCLS has a growth plan stretching at least until 2025
LCLS II Project will provide the infrastructure to enable growth
Anticipate that LUSI II will provide several new instruments
Growth beyond LUSI II will occur as opportunities arise
The goal for 2025
4 FEL sources, all or most seeded
At least 10 experimental stations
Ability to run many stations simultaneously

5. LCLS sources

6. Basic LCLS source considerations
LCLS complex can support 4 FEL undulators
One exists at LCLS I
Two will be added with LCLS II
A fourth could be added at LCLS I
LCLS I and LCLS II can both reach >10 GeV electron energy
LCLS I can reach 14.5 GeV (>20 GeV with future upgrade)
LCLS II is limited to 13.5 GeV
Space exists for all undulators to become seeded FEL sources
Undulators generally start as SASE sources and can be upgraded

7. FEL self seeding FEL amplifier (exponential intensity gain)
Intense x-ray source with spiky spectrum
Additional amplification (linear gain)
Monochromator filter creates seed with controlled spectrum
seeded
Intensity
SASE
Photon energy

8. Evolution of an FEL undulator
61.6
66.0
286.0
Full build out, additional tapered undulators:
S.S. Virtual Source Point
Tapered 15-64
220.0m
S.S. 1-14
61.6m
Mono
4.4m
171.6
LCLS-II HXR BASE Line:
SASE 1-26
114.4m
Drift
171.6m
SASE Source Point m
215.6
LCLS-II HXR w/ Self Seeding Mono:
Tapered 12-26
66.0m
167.2
167.2m m
220.0
S.S. 1-11
48.4m
189.2
Add undulators to reach saturation:
Tapered 12-32
92.4m
140.8
140.8m
193.3
250 pC
8 keV 2.1 mJ
0.47% bw
40 pC
8 keV 2.6 mJ
0.05% bw
40 pC
8 keV 4.8 mJ
0.05% bw
40 pC
8 keV 8.3 mJ
0.04% bw
M. Rowen

9. Polarization control can be added
206.8
Drift
206.8m
SASE Source Point m
LCLS-II SXR BASE Line:
SASE 1-15
66.0m
272.8
286.0
13.2m
3 Pol.
13.2m
286.0
Full build out, tapering and Polarization Control:
180.4
Drift
132.0
S.S. 1-9
39.6m
Mono
8.8m
171.6
Tapered 10-30
92.4m
S.S. Virtual Source Point
272.8
M. Rowen

10. LCLS SASE source characteristics
250pC bunch charge
70m SXR undulator
110m HXR undulator
LCLS II SXR
13.5 GeV
LCLS II SXR
8.5 GeV
LCLS II HXR
13.5 GeV
LCLS I
GeV
LCLS I and LCLS II together provide complete coverage from 250eV to nearly 20keV with >1mJ pulses
LCLS II HXR
8.5 GeV

11. LCLS seeded source characteristics
100
Seeded
SXR 10
HXR
Energy per pulse (mJ) 1
SASE
100pC, 110m SXR undulator
50pC, 250m HXR undulator
Large uncertainties in seeded optimization and sensitivity
0.1
0.1 1 10
Photon Energy (keV)

12. Conclusions about FEL sources
Seeded sources are generally better
Generally give more pulse power, much higher peak power
Narrow, predictable bandwidth
But, single-bunch seeding is limited to lower-charge short bunches (a two-bunch seeding scheme might overcome this limitation)
LCLS facility will cover a wide photon energy range
LCLS II baseline spec is 250 eV to 13 keV
Expect actual useful range to extend to near 20 keV or above
Much of the range can be covered with one fixed electron energy

13. LCLS instrument capability

14. Proposed definitions
The term “beamline” can be confusing when used in a context with sources, transport, and optical components serving multiple experimental stations. It may help to focus the discussion on the following:
Beam Transport – transmits X-rays from source to end station
May service more than one end station
Optics elements may be distributed along the beam transport
Optics – redirect and condition the X-rays on the way from source to end station
End Station – includes sample environment and detectors
May be permanent or removable (roll-in/roll-out)

15. LCLS instruments are becoming more complex
LCLS has 6 hutches now, with 1 source
AMO, SXR have multiple, removable end stations
CXI is developing a system of 2 in-line end stations
Could eventually allow simultaneous experiments
LCLS is developing beam-splitting technology
In near future, expect to deliver beam to several end stations simultaneously
Currently the source feeds only 1 end station at a time
but

16. More complexity coming
LCLS II adds 2 new FEL sources
LCLS II adds room for at least 4 new end stations
Could squeeze in additional end stations
LCLS I has room for an additional undulator
More capability for simultaneous operations

17. A fundamental change in LCLS operation
Consequences of LCLS expansion/multiplexing:
LCLS available beam time will dramatically increase
Source flexibility may decrease
Multiple experiments on one source must agree on parameters

18. How to best manage the expansion?
Start with the science
A clear vision of science opportunities
An understanding of the instrumentation that the science requires
Develop concepts of instruments for doing the science, including source parameters, optics and diagnostics, end stations
Optimize the design and layout of the instruments

19. Information to be captured from discussions during and after this workshop
Science
Wavelength range
Band-width
Photons per pulse
Pulse duration
Polarization
Focus size
Sample environ-ment
Detector needs

20. Possible biology instrumentation
High peak power hard X-ray imaging/diffraction instrument
With lasers for pumping, various sample environments, fluorescence spectrometers
With 2 end stations in series for simultaneous operation
High peak power intermediate-energy X-ray imaging instrument
2-6 keV photon energy
With lasers, sample environments, spectrometers

21. Possible materials/chemistry instrumentation
General purpose hard X-ray scattering instrument
With various sample environments, detector resolutions, geometries, monochromator, detectors, focusing, split & delay, optical pump lasers, etc…
For WAXS, SAXS, XAS, XES, coherent scattering, etc…
Soft X-ray instrument with polarization control
With several end stations optimized for diffraction, RIXS, surface science, etc…
With pump laser capability over wide spectral range including THz

22. Possible AMO instrumentation
Seeded source with narrow bandwidth, high power
Branches optimized so user can choose either high energy resolution or high peak power
Multiple end stations accommodating various sample sources and spectrometers
Gas jets, cluster sources ovens, laser ablation sources, ion sources
Ion and electron spectrometers including magnetic bottle, high energy resolution, and angle resolving spectrometers
X-ray spectrometer
Lasers for time-resolved experiments
Diagnostics for spent X-ray beam

23. Layout of the LCLS complex
DOE CD-3a Review of the LCLS-II Project, Dec 6-7, 2011
Slide 23

24. Fitting 4 experiment stations in EH2
Hard X-ray
Soft X-ray

25. Fitting 6 experiment stations in EH2
Hard X-ray
Soft X-ray

26. Summary
LCLS has an ambitious expansion plan and the LCLS II project is a critical enabling step
LCLS should start now to work out the details of the expansion plan in anticipation of funding opportunities
This workshop will help to define the first step, a package of instruments to be installed at LCLS II
The details start with the science, which then defines the source and instrument requirements