RWS Sept. 2006

Robert W. Schoenlein

Materials Sciences DivisionLawrence Berkeley National Laboratory

Generation of Femtosecond XGeneration of Femtosecond X--ray Pulsesray Pulsesfrom the Advanced Light Sourcefrom the Advanced Light Source

LBNL Instrumentation Colloquium SeriesSept. 6, 2006

RWS Sept. 2006

Outline

Scientific Motivation• Structural dynamics in condensed matter on femtosecond time scale• X-ray source requirements and experimental considerations

Generation of Femtosecond X-rays from 3rd Generation Synchrotrons• Manipulation of the stored electron beam with femtosecond laser pulses• Diagnostics (optical gain measurements, coherent THZ generation)• Results from proof-of-principle experiments at the ALS• Future prospects, limitations, practical issues – experimental applications

New Femtosecond X-ray Facility at the Advanced Light Source• Small-gap, in-vacuum undulator• Soft x-ray and hard x-ray branchlines• High average power (high repetition rate) femtosecond laser system

Future Femtosecond X-ray Sources

RWS Sept. 2006

fundamental time scale for atomic motionvibrational period: Tvib ~ 100 fs

Atomic Structural Dynamics

• ultrafast chemical reactions

• ultrafast phase transitions

• surface dynamics

• ultrafast biological processes

Ultrafast X-ray ScienceRapidly emerging field of research - Physics, Chemistry and Biology

N

N

Fe

O

Fundamental Time Scales in Condensed Matter

fundamental time scales for electron dynamicselectron-phonon interaction times ~ 1 ps

e-e scattering times ~10 fscorrelation time ~100 attoseconds (a/VFermi)

Electronic Structural Dynamics

• charge transfer

• correlated electron systemscharge/orbital orderingCMRhigh Tc superconductivity

Understanding the interplay between atomic and electronic structure- beyond single-electron band structure model – correlated systems (charge, spin, orbit, lattice) - beyond simple adiabatic potential energy surfaces

• electronic phase transitions

Fundamental Scientific Challenge in Condensed Matter:

(femto – 10-15)

(atto – 10-18)

RWS Sept. 2006

Femtosecond Spectroscopy

delay ∆∆∆∆t

samplepump

probe

spectrometer

CCD computer

femtosecondlaser system

∆t

- transmission- reflection- photoemission

~Iprobe(∆t)

- non-linear (probe) ~[Iprobe(∆t)]n

∆t

n-Wave Mixing

harmonic ω1±ω2

- transient four-wave mixing- photon echo

RWS Sept. 2006

Rhodopsin - photoreceptor for vision• cis-trans isomerization complete in 200 fs

Structural Dynamics of Ultrafast Biological Processes

• vibrationally coherent

wavelength (nm)

500 550 600 650

-150

33

100

150

200

300

400

3000

6000

dela

y (fs

)

T/T=2%−∆

Schoenlein et al. Science (1991)Wang et al. Science (1994)

RWS Sept. 2006

diffraction angle

time delay

time delay

x-ray probe

visible pum

patomic structure in systems with long-range order/periodicityphase transitions, coherent phonons

detector

time-resolved x-ray diffraction

delay

x-ray probe

visible pumpr

energy

time

Kedge

abso

rptio

n

Femtosecond X-ray Science

�

ω

element specificmolecular systems and reactionscomplex/disordered materials

EXAFS – local atomic structure and coordination

NEXAFS – local electronic structure, bonding geometry, magnetization/dichroism

(near-edge x-ray absorption fine structure)

time-resolved x-ray spectroscopy

(extended x-ray absorption fine structure)

surface EXAFS, µµµµEXAFS ….( )( )

2

2sin~)(

krkkr

rfφ+

RWS Sept. 2006

FeII Spin-Crossover Molecules

hν

low spin high spin

• ~10-15% increase in metal-ligand bond distances

• trigonal cage distortion?

• electron transfer mechanistic role in biochemical processes (cytochrome P450)

• magnetic and optical storage material

Motivation:• relationship between structure, electronic, and magnetic properties

Do the structural distortions facilitate the spin-crossover reaction?

hν

high-spin state

MLCT(charge-transfer state)

low-spin state

τ~300 fs

1A1g5T2g

∆∆∆∆S=2

(t2g)6 (t2g)4 (eg)2

Fe[tren(py)3]2+

Fe Fe

N

N

N

N

N

NN

N

RWS Sept. 2006

Fe

N

N

N

N

N

N

Fe(II) Spin-Crossover X-ray Spectroscopy

M. Khalil et al., J. Phys. Chem. (2006)

flowing jet0.5 mm, ~30 mM

Ge crystal mono

chopper(2 kHz)

APDdetector

synchrotron(70 ps, 7.1 keV)

laser75 fs, 400 nm

delay

Time-resolved XAS - ALS Beamline 5.3.1)

∆µ

∆µ

∆µ

∆µ x

10-3

energy (eV)

330 ps delay

1s→→→→3d

1s→→→→4p

0.009

2.15 ±0.03

6.5 ±1

Photoexcited 5T2 (τ = 330 ps)

0.001σ (Å2)

1.94 ± 0.01R (Å)

6 ±0.5N

Reactant1A1 (τ = 0)

k (Å-1)

∆µ

∆µ

∆µ

∆µ x

10-3

τdelay = 330 ps

RWS Sept. 2006

Characteristics for Ideal Source

(1) temporal resolution ~ 100 fs

• synchronization to laser trigger

(2) high average flux 108-1013 photons/sec/0.1% BW

(3) tunable 0.3 keV - 10 keV

(4) rep. rate: 100 Hz - 10 kHz

• high average brightness

RWS Sept. 2006

MicroprobeMicroprobe

CrystallographyCrystallography

InterferometryInterferometry

MicrofabricationMicrofabrication

MicroscopyMicroscopy

3rd Generation Synchrotrons - Advanced Light Source

RWS Sept. 2006

3rd Generation Synchrotrons

electron storage ring:1.9 GeV500 MHz, 400 mA70 ps bunch length

12 straight sections for insertion devices

36 bend magnets

high-brightness sourceof soft x-rays 1-100 Å

wiggler

undulator

bend-magnete-

Line

ar

Acc

eler

ator

booster ring

Advanced Light Source

γθK

horiz ~∆γθ

1~vert∆

NnK 211

~2+∆

γθ

mceB

K Woπ

λ2

=

nNnn 1~

λλ∆

RWS Sept. 2006

laser wiggler

bendmagnet

mirrorbeamline x-rays

wiggler

femtosecond electron bunch

bend magnet beamline

70 ps electronbunch

femtosecondlaser pulse

spatial separationdispersive bend

λλλλW

electron-photon interaction in wiggler

femtosecond x-rays

e-beam

Generation of Femtosecond X-rays from the ALS

A. Zholents and M. Zolotorev, Phys. Rev. Lett., 76, 916,1996.

slit

RWS Sept. 2006

φωωωωω cos2),(),(~

2

R

LRLRLRL AAAAdSdrErEA ∆

∆++=+

� � ��

N

S

S

NS

SN

Nwiggler - permanent magnets

wiggler radiation

e-λw

laser

laserw

radiated K λγλλ =+= )2/1(2

22

)2/1(2/

2

2

KK

A RR +≅ ωπα

�

Energy Modulation in the Wiggler

total field energy:

wiggler radiated energy:∆E (energy mod)

Elaser

�

ωL = 1.55 eV

∆ωL = 27 period wiggler

� 36 fs laser pulse

AL = 610 µJ

ALS beam energy spread σΕ ~1.9 MeV Eo =1.9 GeVLaser requirements:

mceB

K Woπ

λ2

=0 π/2 π

optical phase

electron beam

∆E

ρ(E)

∆E

accelerated electrons

decelerated electrons

σE – rms energy spread

since σE ~ Eo2 and we want ∆Ε ∼ σEthen the required laser pulse energy

scales as: AL ~ Eo4

∆E ≅ 17 MeV9σE(72 fs)

(780 µJ)

RWS Sept. 2006

Dynamics of Modulated Electron Beam

x,E ~100 fs laser pulse~70 ps electron bunch

z,t

x,E

z,t

x,E

z,t

Torbit = 656 ns

tdamp = 6 ms

x,E

z,t

300 fs (BL6.3.2)100 fs (BL5.3.1)

tx-ray

ALS Storage Ring Dispersion

σσσσdispersion ~ 85 fs per full arc(200 fs FWHM)

RWS Sept. 2006

Laser Synchrotron Beam Slicing - Layout

WIGGLER (W11)

BACK TANGENT PORT

BEAMLINE 5.3..1

LASER SYSTEM

BL 5.3.1X-RAY HUTCH

LASER TRANSPORT TUBE

SR05 SR04

SR06

PHOTON STOP

ALIGNMENT AND TIMING DIAGNOSTICS

RWS Sept. 2006

Laser Gain through Wiggler (FEL Gain)

)()()( field optical total ωωω εε slasertotal e+=)()(2)()()( 222 ωωωωω εεε slaserslasertotal ee ++=

⋅⋅⋅⋅+∆∂

∂+= ωωωωω )()()( ososs

eee

22γλ

λ wigglerradiated = EEdd

r

r

r

r ∆==− 2ωω

λλ

laserε∝∆Ε

( ) ηπγπ ���

�

��

�

= 222 )(sin

22

xx

dxd

I

IMgain

A

peak

o

oMx ωωωπ )( −=

gain

I(t)

time

I(ω)

ω−ωο

laserosss

lasertotal eee εεε ωωξω

ωω

)(2)(2)(

21 22 ++���

���

�

���

�

���

�

Ε∂∂+=2

RWS Sept. 2006

Measurement of Laser Gain through Wigglerga

in

λλο λ1λ2

laser spectrumgain function

wiggler

laser

e-beam

IF λ1

IF λ2 +-

( ) laserWradiated K λγλλ =+= 2/12

22

λW

-60 -40 -20 0 20 40 60 80

0

1

2

3

4

5

gain

(x10

-3)

delay (ps)

electron bunch laser pulse

σ = 16.6 ps

720 760 800 840 880

-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

central wiggler emission λe (nm)

gain

(%

)

RWS Sept. 2006

CalculatedElectron Density

Distribution

-3σx to +3σx +3σx to +8σx +4σx to +8σx

-1200-1000 -800 -600 -400 -200 0 200

60

80

100

120

140

160

delay (fs)-1200 -1000 -800 -600 -400 -200 0 200

80100120140160180200220240260

delay (fs)-1000 -500 0 500 1000

18001900200021002200

2300240025002600

coun

ts

delay (fs)

-1000 -500 0 500 1000 0

.2

.4

.6

.8

1.0

0

1

2

3

4

-4

-3

-2

-1

time (fs)

x/σσ σσ x

Schoenlein et al., Science, 287, 2237 (2000)

Femtosecond Pulses of Synchrotron Radiation

wiggler

bendmagnet

mirrorbeamline

e-beam

modulated electron bunch

visible synchrotron radiation

Laser System

BBO

�

ωωωω2 = ~2 eV

�

ωωωω1 = 1.55 eV �

ωωωω1+

�

ωωωω2

delay

slit

RWS Sept. 2006

CalculatedElectron Density

Distribution

-1000 -500 0 500 1000 0

.2

.4

.6

.8

1.0

0

1

2

3

4

-4

-3

-2

-1

time (fs)

x/σσ σσ x

Femtosecond Pulses of Synchrotron Radiation

195 fs(FWHM)

delay (fs)-800 -600 -400 -200 0 200 400 600 800

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

wigglerbend

magnet mirror

beamlinee-beam

modulated electron bunch

visible synchrotron radiation

Laser System

BBO

�

ωωωω2 = ~2 eV

�

ωωωω1 = 1.55 eV �

ωωωω1+

�

ωωωω2

delay

slit

RWS Sept. 2006

Coherent Infrared Radiation from Modulated Electron Bunch

( )2/sin2 θρ=photonAB

ρθ=eAB

24

3θρλ ≈=− Rphotone ABAB

R

oRformation ZL λ

πωρθ2

=≅=

• longitudinal modulation of electron density ~λIR• vacuum chamber aperture must accommodate source divergence (formation length)

2/30

2/1 ωρλ −≤R θ

A B

ωo

ρ

zo zo+λIR

θ

Coherent Synchrotron Radiation

λR ≤ 1.4 mm (ρ = 4 m, ωo = 2 cm)

RWS Sept. 2006

Coherent Infrared – Measurement Schematic

bolometer

vacuum windowfused silica

silicon

FTIRSpectrometer

BL5.3.1

e-

J. Byrd, Z. Hao, M. Martin, D. Robin, F. Sannibale, R. Schoenlein, A. Zholents, M. Zolotorev, PRL, 96, 2006

dP/d

ω(µ

W c

m) c

alc.

freq. (cm-1)

Coherent Synchrotron Radiation

-1000 -500 0 500 1000

elec

tric

field

time (fs)

0

-1000 -500 0 500 1000 0

.2

.4

.6

.8

1.0

01234

-4-3-2-1

time (fs)

x/σσ σσ x

e-

~ 1.5 m ~ 3 m

1 cm

∆L ~ 12 µm∆ν ~ 11 cm-1

vacuum window

Coherent IR Detection

Waveguide Effects

RWS Sept. 2006

bend magnetsource

1:1 focusing toroid

crystalmonochromator

1000 Åcarbon foil slits

selection offs x-ray pulse

hutch0 m 12 m 24 m

visible light (to hutch)for diagnostics

differential pumping

chopperangular slitse-beam

Femtosecond x-ray Beamline 5.3.1

• 1:1 image of bend magnet source250 µm (H) x 50 µm (V)

• white beam, 0.1-12 keV(possibility for Laue diffraction)

• flux ~1013 ph/sec/0.1% BW (30 ps pulse duration)

flux ~105 ph/sec/0.1% BWbrightness ~108 ph/s/mm2/mrad2/0.1% BW

100 fs pulse duration(5 kHz repetition rate)

RWS Sept. 2006

Separation of Femtosecond X-rays

• laser modulation of e-beam energy (∆E)laser power, wiggler matching

• storage ring dispersion (∆E→∆x)emittance and lifetime degradation

• beamline image qualitymirror scattering (non-specular)depth of source effects

Sig (fsec)background > 1

Requirement – gated detectors for isolating individual bunchesavalanche photodiodesgated microchannel plates

laser wiggler

femtosecond electron bunch femtosecond x-rays

e-beam slits

∆E ∆x

L

2 nsec

e-bunch pattern

RWS Sept. 2006

2 4 6 8 10 12 140

0.5

1

1.5

2

2.5

3x 10

-4

∆E/σEdN

x/σE

x 10

-4

∆ρ(E) = ρ(E)laser on - ρ(E)laser offModulation: 3σE to 10σE τlaser/τe = 10-3

-10 -5 0 5 10

-10

-8

-6

-4

-2

0

2

4

∆E/σE

dNx/σ

Ex

10-4

Calculated Electron Density Distribution

-1000

01234

-4-3-2-1

-500 0 500 1000 0

.2

.4

.6

.8

1.0

time (fs)

x/σ x

Differential Beam Profiles

RWS Sept. 2006

5 mrad

∆x

-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.510-4

10-3

10-2

10-1

100

∆x (mm)

coun

ts (n

orm

.)

σx = 100 µmλ = 1.2 Å

APD

Si(111)

- fraction of e-beam that is modulated = 75 fs × 0.1 /75 psec = 10-4

σE/∆E=1/10

Beam Profile Measurements – BL5.3.1 Camshaft Bunch

RWS Sept. 2006

Femtosecond X-ray Profile Measurements – BL5.3.1

0

20

40

60

80

100

120

140

-1000 -500 0 500 1000∆x (µm)

diffe

renc

e co

unts

−∆Emax=6σE (11.4 MeV)−∆Emax=7σE (13.3 MeV)−∆Emax=8σE (15.2 MeV)

Calculated Electron Density Distribution

-1000

01234

-4-3-2-1

-500 0 500 1000 0

.2

.4

.6

.8

1.0

time (fs)

x/σ x

Peak Laser Power ~ 10 GW(0.8 mJ, 75 fs)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

-1000 -500 0 500 1000∆x (µm)

Sig

nal/b

kg r

atio

Differential Beam Profile (Laser On-Laser Off) Femtosecond Flux / Background

σx = 100 µm

RWS Sept. 2006

• mÅ charge displacement – THz phonon-polariton mode in LiTaO3A.Cavalleri et al., Phys. Rev. Lett., 95, 067405, (2005).

• Ultrafast insulator-metal transition in VO2 - XANESA.Cavalleri et al., Phys. Rev. Lett., 95, 067405, (2005).

• Time-resolved EXAFS - spin-crossover transition in Fe[tren(py)3]2+M. Khalil et al., J. Phys. Chem. (in press)

• Bonding Properties of Liquid Silicon and Liquid CarbonS. L. Johnson et al., Phys. Rev. Lett., 94, 057407 (2005)S. L. Johnson et al., Phys. Rev. Lett. 91, 157403 (2003)

• X-ray/laser ionization dynamics in atomic systemsM. Hertlein, A. Belkacem et al.

Science at time-resolved x-ray science beamline (ALS BL5.3.1)

Fe

N

N

N

NN

N

RWS Sept. 2006

• pulse duration η2 = τlaser / τsynchrotron = 10-3 (τx-ray ≈ 170 fs)(70 fs) (70 ps)

• repetition rate η3 = flaser / fsynchrotron = 2x10-6(1 kHz) (500 MHz)

• flux ~1013 ph/sec/0.1% BW• brightness ~1016 ph/sec/0.1% BW

• flux ~1015 ph/sec/0.1% BW• brightness ~1019 ph/sec/0.1% BW

Bend Magnet Undulator

Femtosecond X-ray Facility – Scaling the X-ray Flux

flaser / fsynchrotron flimit ≈ 3× =150 kHz(40 kHz) (500 MHz)

number of bunchesτdamping

Average Femtosecond X-ray Flux ~ Average Femtosecond Laser Power

• phase factor η1 = 0.1 (fraction of electrons in optimum phase)

RWS Sept. 2006

Femtosecond Undulator Beamline – Overview

I. Insertion Device

• small-gap undulator/wiggler (1.5 T, 50 x 3cm period)

III. Laser: average power/repetition rate• 30 W (1.5 mJ per pulse, 20 kHz)

sector 6 - proximity to existing wiggler 200 fs x-rays

x102 increase in flux, x103 increase in brightness

x10 increase in flux

• highest possible flux and brightness 0.2-10 keV

II. Beamlines for Femtosecond X-ray Science

IV. Storage Ring Modifications• local vertical dispersion bump – sector 6 and/or 5

• isolation of femtosecond x-ray, 0.2-2 keV, 2-10 keV

wiggler

mirror

beamline

femtosecondx-rayse-beam

undulator

laser

monochroma

torspectro

graph

bend magnet

RWS Sept. 2006

magnetic structurevacuum chamber

In-Vacuum Undulator/Wiggler

SpecificationsMagnetic gap 5.5 mmPeriod 30 mmNo. periods 50Vacuum gap >5 mmBo 1.45 T

S. Marks et al.

RWS Sept. 2006

ALS Femtosecond Undulator Beamline 6.0 Layout

soft x-ray branchline(250 eV – 2 keV)

hard x-ray branchline(2-10 keV)

soft x-ray spectrograph

hard x-ray hutchSeparate M1 mirrors for hard and soft x-rays

sample chamber(dispersive soft x-ray)

slits(intermediate focus)

20 kHz choppers

crystal monochromator20 kHz femtosecond

laser system 2x – 30 W

P. Heimann, D. Plate, H. Padmore, R. Duarte, D. Cambie et al.

RWS Sept. 2006

ALS Femtosecond Undulator BranchlinesP. Heimann, D. Plate, H. Padmore, R. Duarte, D. Cambie et al.

soft x-ray branch (0.2-2 keV)

Focus: 710 µm (H), 72 µm (V)Focus: 60 µm (H), 37 µm (V)

∆E3000

commissionFall 2006

RWS Sept. 2006

X-ray Chopper

• Absorbed x-ray power: ~500 W • Slot dimensions: 3 mm horizontal x 300 mm vertical• Rotating disk, water-cooled, in vacuum – ferro-fluidic feedthroughs• Frequency: 20 kHz matched to laser repetition rate (100 slots at >12,000 RPM)• Synchronization to the laser frequency: allowable phase error 250 ns• LBNL/Rigaku design

RWS Sept. 2006

M203

Gratingmono

SampleChamberand slits

M201(behind wall)

First Light10/4/05

Femtosecond Soft X-ray Beamline 6.0.1.2

RWS Sept. 2006

Femtosecond Laser System

Electron beam interaction requirements:~1.5 mJ pulse energy, 60 fs FWHM, at ~800 nm20 kHz repetition rate, 30 W average powerdiffraction limited focusing, beam parameter: M2 �1.1

Excitation pump pulses for time-resolved experiments:~1 mJ pulse energy at 800 nm (OPA)60 fs pulse duration, 20 kHz repetition rate~500 ns relative delay

60 fs1.5 mJ

Oscillator Stretcher

Compressor2-Pass Amplifier 0.5 ns

2 mJ 0.5 ns300 µµµµJ

RWS Sept. 2006

Femtosecond Laser System

Electron beam interaction requirements:~1.5 mJ pulse energy, 60 fs FWHM, at ~800 nm20 kHz repetition rate, 30 W average powerdiffraction limited focusing, beam parameter: M2 �1.1

Excitation pump pulses for time-resolved experiments:~1 mJ pulse energy at 800 nm (OPA)60 fs pulse duration, 20 kHz repetition rate~500 ns relative delay

Ti:SAPPHIRE RODFARADAY

ROTATOR

Ti:SAPPHIRE ROD

OUTPUT BEAM

INPUT BEAM

HIGH REFLECTOR

PUMP BEAMNd:YLF (2ωωωω)

~90 W, 10 kHz

PUMP BEAMNd:YLF (2ωωωω)

~90 W, 10 kHz

PUMP BEAMNd:YLF (2ωωωω)

~90 W, 10 kHz

PUMP BEAMNd:YLF (2ωωωω)

~90 W, 10 kHz

λλλλ/2 wave plate 77 K

77 K

cryogenic power amplifier

R. Wilcox, R. Schoenlein

RWS Sept. 2006

Femtosecond Pulse Compression

Diffraction Grating Compressor Transmission Grating Compressor

Power Densities: 10-100 W/cm2

RWS Sept. 2006

Femtosecond X-ray Flux

HHG flux from F. Krausz, laser: 10 fs, 3 mJ/pulse, 30 W

Plasma source flux in mrad2 laser: 40 fs, 1 mJ/pulse, 30 W (continuum includes projected 105 improvement)

103 104

104

105

106

107

108

photon energy (eV)

flux

(ph/

s/0.

1% B

W)

bend magnet flux (150 fs, 1 kHz)

undulator flux (200 fs, 20 kHz)(3 cm period, 1.5 m length, Bmax= 1.5 T)

HHG

plasma Kα

fs plasma continuum

ALS typical average x-ray fluxundulator ~1015 ph/s/0.1% BWbend-magnet ~1013 ph/s/0.1% BW

Cu Kα - 1010 ph/s/4π (proj. 1012 with Hg target)cont. 6x107 ph/s/4π (integ. from 7-8 keV)

300

RWS Sept. 2006

Ultrafast X-ray Facilities

• Femtosecond soft x-ray ‘slicing’ beamline – BESSY (operational)

• Femtosecond hard x-ray ‘slicing’ beamline – Swiss Light Source (commissioning)

• Femtosecond x-ray beamline – SOLEIL (planning)

• VUV free electron laser – DESSY (operational)

• X-ray free-electron laser – LCSL SLAC (under construction)

• X-ray free-electron laser – EURO X-FEL Hamburg (planning)

• FERMI@ELETTRA soft x-ray FEL – Trieste (design/construction)

• Soft x-ray FEL – BESSY (planning)

RWS Sept. 2006

A. Cavalleri – VO2M. Rini

M. Khalil – Fe(II) Materials Sciences Division

LBNL

P.A. HeimannT.E. GloverH. Padmore

ALS - Experimental Systems GroupLBNL

A. PatersonM. Howells

Z. HaoAdvanced Light Source

LBNL

A. ZholentsM. Zolotorev

Accel. and Fusion Res. DivisionLBNL

R.W. FalconeU.C. Berkeley

C. Steier W. Wittmer

W. WanH. Nishimura

D. RobinALS – Accel. Physics Group

LBNL

D. PlateS. MarksR. Wilcox

R. SchlueterR. DuarteD. Cambie

Engineering DivisionLBNL

Femtosecond Undulator Beamline Development

Acknowledgements