View
30
Download
0
Category
Preview:
DESCRIPTION
Will Size Define a New Generation of Light Sources ?. David E. Moncton. Future Light Sources Conference JLab March 5, 2012. The most substantial societal impact of x-rays has come from small scale sources—x-ray tubes (14 Nobel prizes) - PowerPoint PPT Presentation
Citation preview
1March 2012
Will Size Define a New Generation of Light Sources?
David E. Moncton
Future Light Sources Conference
JLab
March 5, 2012
2March 2012
Summary
• The most substantial societal impact of x-rays has come from small scale sources—x-ray tubes (14 Nobel prizes)
• Synchrotron radiation has made enormous impact in two ways– Science accomplished (4 Nobel prizes)
– Development of extremely powerful methods based on high brilliance
made possible by incoherent emission from relativistic beams
• X-ray free-electron lasers will also have enormous impact– Access the fs timescale for the first time with significant flux
– Enable the development of methods exploiting the high peak brilliance made possible by coherent electron emission from relativistic beams
• Future machine beyond the ultimate single-mode FELs will combine the features of these three generations of sources– Small scale, relativistic e-beams, and coherent emission.
3March 2012
X-ray Science Driven by Beam Brilliance
X-ray Lasers
SynchrotronRadiation
X-ray Tubes
Re
lati
vit
yC
oh
ere
nt
Em
iss
ion
4March 2012
Roentgen’s X-ray Tubes circa 1895
5March 2012
The Modern X-ray Tube
Rigaku FR-E flux on crystal ~ 4 x 109 ph/sec
6March 2012
Spiral CT (Computed Tomography) Imaging
Note: We now know that much better images can be obtained by phase contrast methods, but are not possible with the cathode ray tube
7March 2012
Nobel Prizes for X-ray Research
8March 2012
First Reference Proposing Use of Synchrotron X-rays
9March 2012
Radiation from Charged Particles (1952)
10March 2012
X-ray Science Driven by Beam Brilliance
X-ray Lasers
SynchrotronRadiation
X-ray Tubes
Re
lati
vit
yC
oh
ere
nt
Em
iss
ion
11March 2012
APS
Kappa Goniostat, ROBAC,Q315 detector
10 Tb NSF
Storage
Thousands of Protein Structures from One APS Beamline
The Structural Biology Center
12March 2012
Nobel Prizes for Synchrotron X-ray Research
1997 ATP-synthase structure (Boyer, Walker)
2003 Ion channels (Agre, MacKinnon)
2006 Eukaryotic transcription (Kornberg)
2009 Ribosime structure (Ramakrishnan, Steitz, Yonath)
13March 2012
X-ray Science Driven by Beam Brilliance
X-ray Lasers
SynchrotronRadiation
X-ray Tubes
Re
lati
vit
yC
oh
ere
nt
Em
iss
ion
14March 2012
New Facilities Based on SASE Radiation
SLAC Stanford
15March 2012
A Tutorial on Peak Brilliance
Peak Brilliance = # photons/xxyy t E
2.3 x 1021/ (nm)
•New scientific frontiers require access to the spatial and temporal regimes where new properties emerge that are out of reach with 3rd gen sources
•This challenge requires the highest collimation, the smallest beam size, the shortest pulses and the best energy resolution—often simultaneously
•The denominator is the phase space volume of the source which can be as small as the uncertainty principle allows—one photon mode
•Therefore peak brilliance is a direct measure of the # photons in the most highly occupied mode—aka photon degeneracy
•To convert from peak brilliance to photon degeneracy divide by
16March 2012
Peak Brilliance
Example—The Advanced Photon Source with peak brilliance about 1023 at0.1 nm
2.3 x 1021/ (nm)Degeneracy =
In other words the most highly occupied mode has, on average, a 4 percent chance of having one photon in it.
17March 2012
Peak Brilliance
Example—The LCLSwith peak brilliance about 1034 at0.1 nm
2.3 x 1021/ (nm)Degeneracy =
x
What is the difference between sources with degeneracy of 109 and those sources with degeneracy from .01—100?
It is the fundamentally different process producing the radiation– coherent vs incoherent emission, laser vs. light bulb
Ring sources produce photons one electron at a time, proportional to the number N of electrons
Lasing is a coherent electron process proportional to N2
18March 2012
19March 2012
Two Key Questions
Are SASE sources the ultimate in x-ray technology?
Are billion dollar central facilities the only option?
While SASE sources benefit from exponential gain, the resulting beam has poor quality compared to a single mode optical laser.
No
NoAdvances in accelerator, laser, and nano technology offer opportunities to build high performance x-ray sources of the scale of a university laboratory
20March 2012
t (fs) (%)
The SASE radiation is powerful, but noisy!
Solution: Impose a strong coherent modulation with an external laser source
SASE Amplifies Random Electron Density Modulations
21March 2012
A Transform-Limited X-ray Pulse
Transverse phase space
x , y ~ 50 microns
kx , ky ~ 10-5 nm-1
Longitudinal phase space
t ~ 1fs - 1ps ~ 2eV - 2meV
A 1 milli-Joule pulse contains 5.0 x 1011 12 keV photons
x kx = ½
y ky = ½
t = ½
Peak brilliance = 1036 3rd Gen: 1025
• Satisfies the Uncertainty Principle in all dimensions
22March 2012
Brookhaven Laser Seeding Demonstration
Buncher
e-
Laser
800 nm
Modulator
266 nm
output
Radiator
•Suppressed SASE noise
•Amplified coherent signal
•Narrowed bandwidth
•Shifted wavelength
High Gain Harmonic Generation (HGHG)
SASE x105
HGHG
L.H. Yu et al., Phys. Rev. Lett. 91, 74801 (2003).
23March 2012
X-ray Science Driven by Beam Brilliance
X-ray Lasers
SynchrotronRadiation
X-ray Tubes
Re
lati
vit
yC
oh
ere
nt
Em
iss
ion
24March 2012
Compact X-ray Sources
?
• There is a growing and urgent need to fill the large gap between laboratory x-ray tubes, and large central facilities.
• At nano-centers such as EMSL that are not at synchrotron sources, advanced x-ray capability is the most important missing probe of matter.
• Advances in accelerator and laser technology make high-brilliance, short pulses sources possible and affordable.
25March 2012
The Technical Opportunity
e-
L
X
• Normal Compton Scattering the photon has higher energy than the electron
• The inverse process has the Thomson cross-section when X e
• The scattered photon satisfies the undulator equation with period L/2 for head-on collisions
energy = e= me
X = L(1+22)
42
• Therefore, the x-ray energy decreases by a factor of 2 at an angle of 1/
Ee
• Head-on collision between a relativistic electron and a photon
Inverse Compton Scattering
26March 2012
Lyncean Technologies Compact Source Concept
Parameters of SourceAverage flux 109 photons/secSource size 50 microns
Courtesy of Ron Ruth
27March 2012
MIT Inverse Compton Scattering Concept
28March 2012
(mrad)
Ph
oto
n E
ne
rgy
(k
eV
)
-40 -20 0 20 40
2
4
6
8
10
12
10
0.1
0.01
100photons/mrad2/eV
1
Note: Plane Perpendicular to Laser Polarization
Normalized emittance = 0.3 m
photons/mrad2/eV
(mrad)
Ph
oto
n E
ner
gy
(keV
)
-40 -20 0 20 40
2
4
6
8
10
1210
0.1
0.01
1
Normalized emittance = 1.0 m
Full Calculations of the Photon Spectrum
29March 2012
dx/dz (mrad)
dy/
dz
(mra
d)
-8 -6 -4 -2 0 2 4 6 8
-8
-6
-4
-2
0
2
4
6
8
1000
2000
3000
4000
5000
6000
7000
8000
Intensity Profile of 12 keV X-rays with 0.1% bw
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
-9 -7 -5 -3 -1 1 3 5 7 9
y (mrad)In
ten
sit
y (
ke
V/m
rad
^2
)
~1012 photons/sec @ 100 MHz in 0.1% BW
Calculations by Winthrop Brown, MIT LL
30March 2012
Conceptual Multi-User Facility based on ICS
Coherent enhancement cavity with Q=1000 giving 1 MW cavity power
1 kW cryo-cooled Yb:YAG drive laser
Superconducting RF photoinjector
X-ray beamline 2
Inverse Compton scattering
X-ray beamline 3
X-ray beamline 4
X-ray beamline 1
Electron beam of 1-100 mA average current at 10-30 MeV
10 kW beam dump
6 m
8 m
Superconducting RF Linac
31March 2012
ParameterHigh average
fluxSingle-shot
Tunable monochromatic photon energy [keV] 3 – 12 3 – 12
Pulse length [ps] 0.1 – 2 1 – 10
Flux per shot [photons] 5 x 106 1 x 1010
Repetition rate [Hz] 108 1-10
Average flux [photons/sec] 5 x 1014 1 x 1011
FWHM bandwidth [%] 25 25
On-axis bandwidth [%] 1 2
Source RMS divergence [mrad] 1 5
Source RMS size [mm] 0.002 0.006
Peak brightness [photons/(sec mm2 mrad2 0.1%bw)]
1 x 1020 6 x 1022
Average brightness [photons/(sec mm2 mrad2)] 3 x 1015 6 x 1011
X-ray Source Parameters
32March 2012
X-ray Science Driven by Beam Brilliance
X-ray Lasers
SynchrotronRadiation
X-ray Tubes
Re
lati
vit
yC
oh
ere
nt
Em
iss
ion
Incoherent ICS
Coherent ICS
33March 2012
Coherent ICS
• How can coherent emission be achieved to boost ICS performance?
Answer: Maybe—by structuring the electron beam, not by laser seeding, but by using a structured nanocathode as a electron source, after T. Akinwande, MIT.
34March 2012
Coherent ICS
It appears possible to manipulate these structured bunches in magnet arrays to compress, rotate, and exchange transverse and longitudinal coordinates, resulting in a sub nm periodic structure which will then coherently emit a hard x-ray beam. See talk by Bill Graves on Wednesday
35March 2012
Protein Crystallography
Small Crystals with Fixed Wavelength and MAD
• Goal: Achieve ICS images with 10 m crystals of equal or better quality compared to rotating anode (Rigaku FR-E) with 100 m crystals.
│← 160 mm →│
Multilayer Osmic
Condenser
30 µ
2 mm
Multilayer Osmic
Collimator
10 µ
Asymmetric Ge (111)
or Si (111)
‹ 100 µrad 3.3 mrad
10 mrad
20 cm
60 cm
Fixed Wavelength:MAD:
Ge(111); E = 16 eV; R = 67%
Si (111); E = 7 eV; R = 80%
36March 2012
Medical Applications
• Medical Imaging—Improved Absorption Images– Current radiographs use 5-75 keV Bremstahlung spectrum– Low energy range causes skin dose, no contrast– High portion cause tissue dose with low contrast– Only the range of energies around 30 keV useful– ICS spectrum is ideal at 30 keV with 5-15% bandwidth– Image quality improved and dose reduced– We would establish collaboration with local radiologists to
further study these factors in detail
• Medical Imaging/Therapy—Tuning to specific wavelengths– Iodine contrast agent for blood imaging– Gd or Pt based cancer therapy
37March 2012
Medical Applications
• Medical Imaging—Phase Contrast Method– Few micron circular source is ideal
– Many milli-radian divergence illuminates large objects in short distance
– Few percent bandwidth can be fully utilized and presents no limitation
– Would improve medical imaging for soft tissue while reducing dose
– Could also utilize the single-shot mode for time-resolved images
– Simplest approach requires no optics
– But optics could reduce spot size, increase coherence, and increase illuminated area
38March 2012
Ultrafast Science Opportunities
• Pico-second Science– Synchrotron sources have 50-100 ps pulse lengths
– ICS source may have pulse lengths down to 100 fs
– At 1 ps the single-shot flux could be >109 photons in a 6% bandwidth
– Large bandwidths are appropriate for Laue method as pioneered by Wulff and co-workers at ESRF
– ICS could be run in a kHz mode for repetitive experiments
– Both diffraction and PC imaging modes possible
– Flux exceeds plasma sources by many orders of magnitude
– Flux exceeds storage ring pulse chopping schemes
– Would be a stepping stone to the big FELs
39March 2012
Kirk Clark, Novartis Institutes for Biomedical Research
• Structural Biology is an integral component of many drug discovery programs.
– Guides medicinal chemistry efforts; turn-around time is critical
– Insight into protein function; novel structures benefit from tunable x-rays
– Epitope mapping for antibodies; rapid structures (even low resolution) valuable
• Benefits of bright, local x-ray source
– Time. Quick feedback on quality of small crystals and/or final datasets.
• Small crystals are more readily obtained with less reagents
• Reduced opportunity costs by avoiding needless improvements to good crystals.
– Facilitate expanding structural biology to integral membrane proteins.
– Costs. Reduced travel costs (currently traveling to Chicago/Zurich every 3 to 4 weeks), proprietary fees, access fees.
39
Novartis
40March 2012
Wyeth
41March 2012
National High Magnetic Field Laboratory
42March 2012
NIST Gaithersburg Campus
NCNR
AXF
CNSTSIRCUS
SURF III
Neutron Research
Nanoscale Science & Technology
Ultraviolet Synchrotron
Radiation Laser Spectroscopy
Advanced X-ray Facility
43March 2012
LC2RMF = Laboratory of analytical chemistry and scientific imaging located in the Louvre
Objectives: Research, expertise and support for curators and conservators thanks to physico-chemical analyses.
Ø Necessity of non destructive testing with high sensitivity because the studied materials are very complex
1989: Installation of the accelerator AGLAE in the Louvre = ion beam analysis with an external microbeam (elemental analysis, direct on the artifacts)
1997: Development of synchrotron radiation analysis = structural and molecular analysis but necessity of samples
2009: Project of combination of AGLAE with an ICS in the Louvre for non destructive structural and elemental analysis (XRF, XANES, XRD) as well as for 3D imaging of works of art.
X-ray UV
VIS Louvre Museum
44March 2012
Picosecond Physics at the MIT STC - S. Durbin, Physics Dept.
I. Laser pump deposits energy into the electronic system, and the lattice response can be tracked with an x-ray probe beam.Use high rep rate (>106 Hz), ultrashort pulse length (0.1-5 ps, not available at ANY synchrotron source)) to observe • non-thermal melting, coherent phonons•ferroelectric/complex oxide transitions• porphyrin dynamics
II. X-ray pump, laser probe in semiconductors: Single 1 ps x-ray pulse (1010 x-rays) focused to 10 microns can generate up to 1017 cm-3 instantaneous deep core holes in a semiconductor. Laser monitor of absorption and reflectivity will reveal the quantum kinetic response of plasmons and phonons in this new many-body probe.
Picosecond Physics at the MIT STC - S. Durbin, Physics Dept.
I. Laser pump deposits energy into the electronic system, and the lattice response can be tracked with an x-ray probe beam.Use high rep rate (>106 Hz), ultrashort pulse length (0.1-5 ps, not available at ANY synchrotron source)) to observe • non-thermal melting, coherent phonons•ferroelectric/complex oxide transitions• porphyrin dynamics
II. X-ray pump, laser probe in semiconductors: Single 1 ps x-ray pulse (1010 x-rays) focused to 10 microns can generate up to 1017 cm-3 instantaneous deep core holes in a semiconductor. Laser monitor of absorption and reflectivity will reveal the quantum kinetic response of plasmons and phonons in this new many-body probe.
BacteriophagesFlavivirusesds viruses Alpha viruses
Purdue University
45March 2012
University College London
46March 2012
Robert Feidenhans’l, Niels Bohr Institute, University of Copenhagen
Franz Pfeiffer et al
Lab source setup
Phase shift
CancerousLymph nodeESRF data
Absorption
Aim : Medical Imaging
University of Copenhagen
47March 2012
Conclusions (Predictions)
• Within a decade FEL facilities will achieve single mode laser radiation in the hard x-ray regime with milli-Joule power levels.
• Within two decades superconducting linac-based facilities will have many such beamlines operating across a wide spectral range.
• There is no obvious “next generation” large facility. But….
• Within a decade compact sources less than $10M will offer NSLS I level (2nd generation) x-ray properties.
• Within two decades compact sources will demonstrate coherent emission revolutionizing laboratory-scale capability.
• Large facilities always be the most powerful sources simply due to the physics of electromagnetic radiation from energetic charged particles.
• But the most creative science will most likely come from the laboratory sources, just as with laser sources today, and x-ray sources of the early 20th century.
Recommended