Latest Results on HXRSS at LCLS

Franz-Josef Decker 4-Feb-2013

1. Seeding with 004, 220 and over-compression

2. Tuned beam with slotted foil cutting horns

3. Energy spread energy jitter undulator acceptance

4. Up to 300,000 counts on FEE spectrometer (0.7 mJ)

with multiple spikes

2Insert Presentation Title in Slide Master

Hard X-Ray Self-Seeding at LCLS (HXRSS)

Bragg 004

Laue 220

3Latest Results on HXRSS at LCLS

Different Mode of Operation

1. Blue: “Background” SASE with delay, crystal out

2. Red: Seeded 220 (tuned)

3. Green: Seeded 004

4. Magenta: Seeded 220

over-compressed

(less SASE?)

Typical:

220: 0.8 eV

004: 0.5 eV

220 o-c: 2.0 eV

SASE: 20.0 eV (Spectrometer cuts to 11.0 eV)

4Latest Results on HXRSS at LCLS

To avoid tuning up on the horns: Cut them with Slotted Foil

Foil out Foil in (tuned)

100 shots

SASE

1 shot

Additional peak

5Latest Results on HXRSS at LCLS

Gas detector: FEL intensity vs time

• Slotted foil: out and in

• 0.2 to 0.70 mJ 0.0 to 0.4 mJ

(SASE) or multiple spikes ?

6Seeding with Slotted Foil in

Correlation Plot Data with Spectrometer Profile (Foil in)

• Peak (= area/sigma*2.5)

vs x (= photon energy)• Peak vs x (= e-beam

energy)

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Three Different Energy “Widths”

• DL2 wire scan: 0.040%• DL2 energy jitter: 0.036%• Undulator acceptance: 0.032%

all about the same

Need to reduce E-jitter or increase acceptance (0.22-0.042% ?)

0.040%

Warning: “smoothed” data

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Gain: Seeded / SASE: 3.4 / 2 / 0.7 = 2.4 (0.7 FEE spectrometer throughput)

Latest Results on HXRSS at LCLS

Seeding vs. SASE with Si(111) in XCS (Aymeric Robert)

Seeded up to 1mJ, 11-Jul-2012

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Summary

• Seeding with 004, 220, and over-compressed beam• Cutting horns with BC2 slotted foil, • Up to 300,000 counts peak on spectrometer single shots • Up to 140,000 counts average (100 shots) • Multiple spikes might be cause for elevated gas detector• Energy spread, energy jitter, undulator acceptance: 0.035%• Laser heater is necessary (or: <10% FEL intensity)

Latest Results on HXRSS at LCLS

10Insert Presentation Title in Slide Master

Backup Slides

• Six double pulses in a row, what causes the shifts?

11Seeding with Slotted Foil in

Spectrometer peak show different picture

• Gaussian peak of fit:• Foil out: 130,000 counts Foil in: 170,000 counts

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SASE plus start of seeding

Latest Results on HXRSS at LCLS

• Seeded light is about one sigma off in x (y here)• There is generally

some offset with

SASE lines too,

looking at the lower

half and trying to

guess the upper

part is flawed

Seeded

13Seeding with Slotted Foil in

BSA Jitter Data, and more

• Gas detector (FEL intensity) versus DL2 e-beam energy

starts to show elevated middle

• Spectrum Energy FWHM versus BC2 peak current

14Latest Results on HXRSS at LCLS

a) “User” energy: here spectrometer: 8.45 keV

b) Beam energy to read 8.45 keV

(and SASE in screen, full power not documented)

c) Crystal Bragg angle scan

Peak at 55.113º or 55.15º,

where to tune up?

Optimize horns or center

of longitudinal distribution?

Getting Three Energies Right

15Seeding with Slotted Foil in

Some Tuning of Spectrum Peak

• Peak on L1S phase• Peak (+FWHM) on beam energy

Beam Energy

16Latest Results on HXRSS at LCLS

Where to start tuning?

• Bragg angle at• 55.113 deg (horn?) 55.150 deg (E more

centered)

DL2 energy DL2 energy

17Latest Results on HXRSS at LCLS

To avoid tuning up on the horns: Cut them

• Slotted foil in to widest place (-10500 um)

18Seeding with Slotted Foil in

Procedures: RF kicks measurements

• “Amount of RF

Foil out Foil in

1 shot

100 shots

SASE