LCLS Instrument Development

John ArthurSLAC

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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…

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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

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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

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LCLS sources

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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

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FEL self seeding

Intense x-ray source with spiky spectrum

Monochromator filter creates seed with controlled spectrum

FEL amplifier (exponential intensity gain)

Additional amplification (linear gain)

seeded

SASE

Photon energy

Inte

nsi

ty

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Evolution of an FEL undulator

0 61.6 66.0 286.0

Full build out, additional tapered undulators:

S.S. Virtual Source Point

178-183

Tapered 15-64220.0m

S.S. 1-1461.6m

0 171.6 286.0

LCLS-II HXR BASE Line:

SASE 1-26114.4m

Drift 171.6m

SASE Source Point

246-261m

0215.6

286.0

LCLS-II HXR w/ Self Seeding Mono:

Tapered 12-2666.0m

167.2

Drift167.2m

S.S. Virtual Source Point

251-256m

220.0

S.S. 1-11 48.4m

0

S.S. 1-11 48.4m

189.2 286.0

Add undulators to reach saturation:

Tapered 12-3292.4m

140.8

Drift 140.8m

S.S. Virtual Source Point

232-237

193.3

M. Rowen

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

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Polarization control can be added

3 Pol.13.2m

0 286.0

Full build out, tapering and Polarization Control:

180.4

Drift132.0

S.S. 1-939.6m

171.6132.0

Tapered 10-3092.4m

S.S. Virtual Source Point 222-227

272.8

0206.8

Drift206.8m

SASE Source Point 247-257m

LCLS-II SXR BASE Line:

SASE 1-1566.0m

272.8 286.0

Drift13.2m

M. Rowen

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250pC bunch charge70m SXR undulator110m HXR undulator

LCLS II HXR13.5 GeV

LCLS II HXR8.5 GeV

LCLS II SXR13.5 GeV

LCLS II SXR8.5 GeV

LCLS I and LCLS II together provide complete coverage from 250eV to nearly 20keV with >1mJ pulses

LCLS I3.3-15 GeV

LCLS SASE source characteristics

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LCLS seeded source characteristics

0.1

0.1

1

1

10

10

100

Photon Energy (keV)

Ene

rgy

per

puls

e (m

J)

SASE

Seeded

100pC, 110m SXR undulator 50pC, 250m HXR undulator Large uncertainties in seeded

optimization and sensitivity

HXR

SXR

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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

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LCLS instrument capability

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Proposed definitions

• 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– May service more than one end station

• End Station – includes sample environment and detectors– May be permanent or removable (roll-in/roll-out)

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:

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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

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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

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• LCLS available beam time will dramatically increase

• Source flexibility may decrease–Multiple experiments on one source must agree on parameters

A fundamental change in LCLS operation

Consequences of LCLS expansion/multiplexing:

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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

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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

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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

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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

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• 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

Possible AMO instrumentation

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Layout of the LCLS complex

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

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7 m

10 m

15 m16 m

17 m14 m

17 m

10 m

10 m

Fitting 4 experiment stations in EH2

Soft X-ray

Hard X-ray

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15 m 12 m 10 m

10 m10 m

10 m

9 m9 m

10 m6 m 7 m

9 m

Fitting 6 experiment stations in EH2

Soft X-rayHard X-ray

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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