1. Synchrotron Radiation Sources Past, Present and Future
By Vic Suller
Synchrotron Radiation Storage Rings
Vic Suller: CAMD Louisiana & SRS Daresbury

2. The Origins of Synchrotron Radiation
Contents
The Origins of Synchrotron Radiation
Synchrotron Radiation Characteristics
Storage Rings as Sources
Insertion Devices
The Future with 4th Generation Sources
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3. Crab Nebula - the first Synchrotron source observed??
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4. Center for Advanced Microstructures and Devices
CAMD in Baton Rouge, LA
Center for Advanced Microstructures and Devices
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5. Accelerator Synchrotron Radiation
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6. Accelerated Charge Radiation Lienard July 1898
Discovery of Electron
JJ Thompson
October 1897
Accelerated Charge Radiation
Lienard
July 1898
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7. ELECTROMAGNETIC RADIATION
Field lines from a stationary charge
Field lines from an accelerated charge
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8. Spatial distribution of radiation from a charge accelerated z
Spatial distribution of radiation
from a charge accelerated
along the z axis x y
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9. Acceleration by Induction - The Betatron
Principle of Betatron Acceleration
Coil
Steel
Vacuum chamber
Cross section of a Betatron
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10. Prediction of Energy loss by radiation in an accelerator
Iwanenko & Pomeranchuk June 1944
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11. GEC(USA) electron accelerators 1946
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12. First attempt to Detect Synchrotron Radiation
John Blewett 1947 – used a microwave receiver expecting
Harmonics of the orbit frequency (100 MHz) - nothing found!
First correct theory of Synchrotron Radiation
Julian Schwinger 1947 – showed the importance of relativistic effects
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13. Light from the GE Synchrotron 1947
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14. Betatron - CERAMIC Synchrotron - GLASS
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15. Relativistic effects in Synchrotron Radiation
Contraction of the orbit in the electron frame
Result:- Orbit frequency increases by factor g
Relativistic Doppler shift from the electron frame to the lab
Result:- Frequency further increases by factor 2g
Relativistic forward focusing of the emission
Result:- Frequency further increases by factor 2pg
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16. Relativistic focusing of Synchrotron Radiation
acceleration
Electron frame
acceleration q
Lab frame
velocity b
Transformation between frames:-
tan q = g-1 sin f (1+b cos f )-1
If f = then q = g-1
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17. ~g3 Relativistic effects in Synchrotron Radiation (cont)
The effect of 3 relativistic processes upshifts the orbit frequency by
~g3
For example 2 GeV electrons in a 100m orbit
orbit frequency 3 MHz
g = g3 = m Þ 1.7 nm (0.7 keV)
For protons to radiate equivalently in a 100m orbit
Energy = 3.7 TeV and magnetic field = 10 kT
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18. Synchrotron Radiation Features
Continuum source from IR to X-rays
Source in a clean UHV environment
High Intensity and Brightness
4. Highly Polarized
5. Stable & controllable pulsed characteristics
…highly attractive for research applications!!!
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19. Synchrotron Radiation Features
The synchrotron radiation spectrum is described with reference to a characteristic (often called 'critical') wavelength lc, or photon energy ec
where B is the bending magnetic field.
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20. Synchrotron Radiation Spectral Flux Intensity
When the radiation at a given wavelength is integrated over all angles of vertical emission the resultant Spectral Flux Intensity is given by
photons/sec/mr/0.1% bandwidth
is a numerical factor which essentially governs the shape of the spectrum.
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21. Synchrotron Radiation Spectra
Examples of spectra produced by electron storage rings:-
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22. Typical Synchrotron Radiation Spectra
CAMD
APS
NSLS-VUV
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23. Typical Synchrotron Radiation Spectra 2
APS
CAMD
VUV
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24. 1st Generation Synchrotron Radiation Sources
Originally built for some other purpose (1965 – 1975)
SOURCE
COUNTRY
TYPE
ENERGY (GeV)
TANTALUS
USA
Storage Ring
0.24
SPEAR-1
3.0
NINA UK
Synchrotron
5.0
DESY
Germany
6.0
BONN
0.5
ACO
France
0.54
VEPP-2m
Russia
0.7
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25. 2nd Generation Synchrotron Radiation Sources
Dedicated, purpose designed (1975 – 1985)
Some examples:-
SOURCE
COUNTRY
ENERGY (GeV)
Emittance nm rads
SOR-ring
Japan
0.38
320
SRS UK
2.0
110
NSLS-VUV
USA
0.744 88
NSLS-XR
2.5 80
BESSY-1
Germany
0.8 20
Photon Factory
130
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26. Synchrotron Radiation Brightness
Notice that Brightness, as here defined, is often referred to as Brilliance, with an accompanying incorrect use of the term brightness for the Spectral Flux Density. It is best to avoid confusion by using the well established radiometric definitions as given here.
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27. Average Spectral Brightness =
Note that source Brightness as defined is anisotropic, the value depends on the source density distribution and on the observation angle. It is often more convenient to use, as a figure of merit, an average brightness which for dipole sources is defined
Average Spectral Brightness =
is the vertically integrated flux, 2.36sx is the fwhm of the horizontal electron beam size, 2.36sz is the fwhm of the vertical electron beam size, and 2.36sg/ is the fwhm of the photon emission angle in the vertical plane. The latter is a combination of the electron beam vertical divergence and the photon emission angle thus
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28. Radiation excitation and damping of oscillations
Dispersion
Betatron oscillation
Radiation excitation
Initial momentum
Final momentum
RF restores
Radiation loss
Radiation damping
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29. The equilibrium of the excitation and the damping of the betatron oscillations determines the emittance of the stored beam with the result:
The emittance is determined by the behaviour of the dispersion - and the horizontal betatron function within the bending magnets. The emittance is given by the lattice of the machine.
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30. Minimum emittance of Chasman-Green lattice
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31. Theoretical Minimum Emittance lattice
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32. 3rd Generation Synchrotron Radiation Sources
Dedicated, high brightness, designed to include
Insertion Device Sources (1985 – 2005?)
Some examples:-
SOURCE
COUNTRY
ENERGY (GeV)
Emittance nm rads
SUPER-ACO
France
0.8 37
ALS
USA
1.8
4.9
ESRF
6.0
4.5
APS
7.0
8.0
SPRING-8
Japan
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33. Synchrotron Radiation Storage Rings
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34. APS at Argonne National Laboratory
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35. Trends in 3rd Generation Light Source Performance
Energy( GeV )
Emittance (nm rad)
Circumference(m)
MAX II
1.5 9 90
ALS
1.9
5.6
196.8
BESSY II
6.4
240
ELETTRA 2 7
258
Swiss LS
2.4 5
288
NSLS
2.5 50
170
SESAME
24.4
124.8
SE-ALS
4.7
191
SOLEIL
2.75
3.72
354
Canadian LS
2.9
18.2
170.4
Australian LS 3
6.88
216
DIAMOND
2.74
561.6
ESRF 6 4
844
APS
8.2
1104
Spring-8 8
1436
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36. Proposed South East Advanced Light Source (1)
DOUBLE BEND LATTICE FUNCTIONS
Length (m)
Energy
2.5 GeV
Circumference
170 m
Emittance
7.9 nm rads
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37. Proposed South East Advanced Light Source (2)
Energy
2.5 GeV
Circumference
190 m
Emittance
4.7 nm rads
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38. Wiggler or Wavelength Shifter
Placed in a straight section
Net deflection zero
High magnetic field 5-10T
Large horizontal fan ~200 mr
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39. CAMD Wiggler Central pole 7 Tesla End poles 1.5 Tesla
Made by Budker Institute
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40. SRS Daresbury 6 Tesla Wiggler
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41. Multi Pole Wiggler Multiple alternating poles High magnetic field 2-5T
Small horizontal fan ~20 mr
Superposition of source points
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42. SRS Daresbury 2.4 Tesla Permanent Magnet MPW
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43. Undulator Multiple alternating poles Period lu = 10s of mm
Beam deflection < 1/g
Interference makes line spectrum
Very high brightness
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44. Undulator approximate theory
electron bc
Undulator
magnetic field lu
In the laboratory frame the electron travels towards the undulator magnetic field at relativistic velocity.
In the electron frame the undulator appears as an EM-wave relativistically contracted to 1/g . lu.
There is then a relativistic Doppler shift 1/2g back to the laboratory frame.
Thus the undulator produces monochromatic radiation of
stationary
electron
Undulator
electromagnetic wave
1/g . lu bc
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45. Undulator correct theory
It is essential to account for the transverse motion of the electron in the undulator.
Introduce the deflection parameter k
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46. Undulator constructive interference
photon
electron A B
As an electron moves from A to B the photon moves ahead.
A photon emitted at point A will constructively interfere with one emitted at point B if it gains by a whole number of wavelengths:-
n = 1,3,5,…
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47. Undulator Spectrum (calculated)
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48. ESRF Undulator Synchrotron Radiation Storage Rings
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49. In vacuum Undulators – for small gap / period
SRC
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50. SRC Wisconsin 6 EM Undulator
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51. Elettra – SLS Helical Wiggler/Undulator
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52. SE-ALS Undulator 50 mm Synchrotron Radiation Storage Rings
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53. Synchrotron Radiation Storage Rings
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54. 4th Generation Synchrotron Radiation Sources
What could be their characteristics?
Extremely high brightness
Ultra short electron bunches
Coherent radiation
Conclusion:- It must be based on a Free Electron Laser
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55. Oscillator type Free Electron Laser
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56. SASE type Free Electron Laser
SASE = Self Amplification of Spontaneous Emission
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57. Free Electron Laser- present limitations
Wavelength limited by mirrors
- use SASE
Low rep rate hence low average brightness
- use Energy Recovery Linac
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58. Energy Recovery Linac Superconducting RF High brightness cw e-gun
Low energy beam dump
SASE Free Electron Laser
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59. ERLs Past and Future TJNAL (USA) 160 MeV BINP (Rus) 100 MeV
4GLS (UK) 600 MeV
KEK ERL (J) 2.5GeV
PERL NSLS (USA) 2.7 GeV
LUX LBL (USA) 3 GeV
ERLSYN (D) 3.5 GeV
Cornell-TJNAL (USA) 5 GeV
MARS BINP (Rus) 6GeV
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60. Conclusion for Synchrotron Radiation
The Future is EVEN BRIGHTER than this!
Thank You!
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61. BRIGHTNESS of Undulators
The brightness of an undulator is calculated slightly differently.
The flux in the central cone of an undulator Fn at a specified wavelength is averaged over the emission angle of that cone to give the Average On-axis Brightness.
Because of the usually very small source size and divergence in an undulator diffraction effects must be taken into account.
Average On-axis Brightness =
sgz, sgz are the photon source sizes in both planes and sgz/, sgz/ are the photon source divergence in both planes, taking into account diffraction effects.
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62. fn is a numerical factor, related to k.
L = undulator length
lu = undulator period
Radiation in the nth harmonic in an undulator
deflection parameter k = 93.4 lu(m)Bo(Tesla)
flux in the central cone Fn= I0 Qn(k) photons/sec/0.1% bandwidth
fn is a numerical factor, related to k.
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