Synchrotron Radiation (SR) - Aarhus Universitet · 2015-11-12 · Synchrotron radiation Wigglers,...

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12-11-2015 1 Accelerator Physics: Synchrotron radiation Wigglers, Undulators Monochromators Lecture 4a Søren Pape Møller ISA Synchrotron Radiation (SR) Acceleration of charged particles Emission of EM radiation In accelerators: Synchrotron Radiation Significance Effect on particle/accelerator Characterization and use of SR Literature – Chap. 2 + 8 in “Wille

Transcript of Synchrotron Radiation (SR) - Aarhus Universitet · 2015-11-12 · Synchrotron radiation Wigglers,...

Page 1: Synchrotron Radiation (SR) - Aarhus Universitet · 2015-11-12 · Synchrotron radiation Wigglers, Undulators Monochromators Lecture 4a Søren Pape Møller – ISA Synchrotron Radiation

12-11-2015

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Accelerator Physics:

Synchrotron radiation

Wigglers, Undulators

Monochromators

Lecture 4a

Søren Pape Møller – ISA

Synchrotron Radiation (SR)

• Acceleration of charged particles

– Emission of EM radiation

– In accelerators: Synchrotron Radiation

• Significance

– Effect on particle/accelerator

– Characterization and use of SR

• Literature

– Chap. 2 + 8 in “Wille”

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General Electric synchrotron accelerator built in 1946,

the origin of the discovery of synchrotron radiation from

70 MeV electrons.

The arrow indicates the evidence of “arcing”.

SR fra ASTRID

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Udsendelse af synkrotron

stråling

Synkrotronstråling fra ASTRID

Fotonenergi (eV)

Bølgelængde (nm)

Synkrotronstråling fra ASTRID

Sollys

Synligt lys

0.1 10 1000 100000

0.01 1 100 10000

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Emission of Synchrotron Radiation

• Present lecture, see “Wille” – Details, see Jackson – “Classical Electrodynamics”

– Here: Mainly key physical elements

• Acceleration of charged particles EM radiation

• Lamor: Total power v<<c

• Angular distribution (Hertz dipole)

Relativistic particles

cv

2

0m

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Linear acceleration

• Accelerator energy gain: dE/dx ≈ 15 MeV/m

– Ratio between energy lost and gain:

– h = 5 * 10-14 (for v ≈ c)

– Negligible

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Angular distribution of synchrotron

radiation

Spectrum of SR

• Spectrum: Harmonics of frev

• Characteristic/critical frequency

• Divide power in ½

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Synkrotronstråling

GeVT

864.1nm GeVT665.0keV

2

2

EBEB cc

0.01 0.1 1 101E10

1E11

1E12

1E13

c

=358 eV

ved 580 MeV

og 1.6 T

Universelt

synkrotronstrålings

spektrum

ph

oto

ns/s

/mra

d/0

.1%

BW

/Ge

V

Energy/c

ASTRID og synkrotronstråling

Fotonenergi (eV)

Bølgelængde (nm)

Inte

nsi

tet

Synkrotronstrålingfra ASTRID

Sollys

Synligtlys

0.1101000100000

0.01 1 100 10000

c

𝜀𝑐[𝑒𝑉] = 665𝐸2 𝐺𝑒𝑉 𝐵[𝑇]

𝜃 ≈ 1/𝛾 ≈ 1𝑚𝑟𝑎𝑑

𝛾 = 1/ 1 − 𝛽2

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E.g. ASTRID (580 MeV)

Vertical angular distribution

Polarization

_____ og -----

GeVT665.0keV 2EBc

Spectral Brightness

1E+11

1E+12

1E+13

1E+14

1E+15

1E+16

1E+17

0.001 0.01 0.1 1 10Photon Energy (keV)

Ph

/s*m

m^

2*m

rad

^2

*0.1

BW

Undulator, ASTRID2

Undulator

2T 12 pol wiggler, ASTRID2

Bend, ASTRID1

Bend ASTRID2

ASTRID2

• Horizontal

emittance [nm]

– ASTRID2:12.1

– ASTRID: 140

• Diffraction limit:

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ASTRID/2 beamstørrelse

2mm

0.1mm

ASTRID (140 nm)

0.2mm

0.01mm

ASTRID2 (10 nm)

Diffraktionsbegrænset i V og delvist i H

4' RR

Synkrotron stråling : Effekt

Energitab/omgang : U[keV] = 88.5*E4[GeV4]/r[m]

Udstrålet effekt: P[kW] = U[keV]*I[A]

E [GeV] B [T] c [keV] U [keV] P [kW]

ASTRID 0.100 0.276 0.002 0.007 0.001

ASTRID 0.580 1.6 0.36 8.3 1.7

ESRF 6 0.86 20.7 4922 1000

LEP 100 0.1 665 2950000 29000

I praksis, max 100 GeV for elektron synkrotron -> linear accelerator

200 mA

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Light sources in Europe Name Country Website

Institute for Storage Ring Facilities Denmark http://www.isa.au.dk/

European Synchrotron Radiation

Facility France http://www.esrf.eu

SOLEIL France http://www.synchrotron-soleil.fr/

Angstromquelle Karlsruhe - ANKA Germany http://anka.kit.edu

BESSY II - Helmholtz-Zentrum Berlin Germany http://www.helmholtz-berlin.de/

Dortmund Electron Storage Ring

Facility Germany http://www.delta.tu-dortmund.de/

ELSA - Electron Stretcher Accelerator Germany http://www-elsa.physik.uni-

bonn.de/elsa-facility_en.html

Metrology Light Source Germany http://www.ptb.de/mls/

PETRA III at DESY Germany http://photon-science.desy.de

DAFNE Italy http://web.infn.it/Dafne_Light/

Elettra Synchrotron Light Laboratory Italy http://www.elettra.eu

Dubna Electron Synchrotron Russia http://wwwinfo.jinr.ru/delsy/

Kurchatov Synchrotron Radiation

Source Russia http://www.nrcki.ru/e/engl.html

TNK Russia http://www.niifp.ru/page/sinhrotron

ALBA Spain http://www.cells.es/

MAX IV Laboratory Sweden http://www.maxlab.lu.se/

Swiss Light Source Switzerland http://www.psi.ch/sls/

Diamond Light Source United Kingdom http://www.diamond.ac.uk/

ESRF – MAX IV

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Storage rings for SR

• SR – unique broad spectrum!

• 0th generation: Paracitic use

• 1st generation: Dedicated rings for SR

• 2nd generation: Smaller beams – ASTRID?

• 3rd generation: Insertion devices (straight sections), small beam – ASTRID2

• 4th generation: FEL

Insertion devices

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Multi-pole wiggler (MPW)

• Insertion device in straight section of storage ring

• Shift SR spectrum towards higher energies by larger

magnetic fields

• Gain multiplied by number of periods

• W/MPW made up to 10 T

K>>1Wiggler

”wavelength shifter

Wiggler/undulator parameter

K=ΘW /(1/γ)=eBλu/(2πmec)

ASTRID2 Wiggler

ASTRID2 – MPW – 2 T

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Example (ASTRID2):

Multi-pole wiggler (MPW)

• B0 = 2.0 T

• = 11.6 cm

• Number of periods = 6

• K = 21.7

• Critical energy = 447 eV

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Undulator radiation

If K <~1 : Line-spectrum with harmonics

anglen observatio

21

2

0

2

0

22

2,

K

n

unw

Undulator/wiggler spektrum

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ASTRID Undulator

Construction a) Electromagnet; b) permanent magnets; c) hybrid

magnets

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0 50 100 150 2000.0

2.0x1014

4.0x1014

6.0x1014

8.0x1014

1.0x1015

Pho

ton

flux

Photon energy (eV)

K = 2.3 (25 mm gap) Integrated flux

2.02 mrad

2

1.02 mrad

2

0.52 mrad

2

0.252 mrad

2

Spectral Brightness

1E+11

1E+12

1E+13

1E+14

1E+15

1E+16

1E+17

0.001 0.01 0.1 1 10Photon Energy (keV)

Ph

/s*m

m^

2*m

rad

^2

*0.1

BW

Undulator, ASTRID2

Undulator

2T 12 pol wiggler, ASTRID2

Bend, ASTRID1

Bend ASTRID2

Brightness

• Horizontal

emittance [nm]

– ASTRID2: 10

– ASTRID: 140

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SR fra ASTRID2

2mm

0.1mm

ASTRID (140 nm)

0.2mm

0.01mm

ASTRID2 (10 nm)

Diffraktionsbegrænset

i V og delvist i H

4' RR

Diffraktionsgrænse

Insertion devices: Summary

• Wiggler (K > 1, > 1/) – Broad broom of radiation

– Broad spectrum

– Stronger mag. field: Wavelength shifter (higher energies!)

– Several periods: Intensity increase

• Undulator (K < 1, < 1/) – Narrow cone of radiation: Very high brightness

• Brightness ~ N2

– Peaked spectrum (adjustable) • Harmonics if not K<<1

– Ideal source!

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Optical systems for SR I

• Purpose

– Select wavelength: E/E ~ 1000 – 10000

– Focus: Spot size of 0.1∙0.1 mm2

Optical systems for SR II

• Photon energy: few eV’s to 10’s of keV

– Conventional optics cannot be used

• Always absorption

– UV, VUV, XUV (ASTRID/ASTRID2)

• Optical systems based on mirrors

– X-rays

• Crystal monochromators based on diffraction

Page 20: Synchrotron Radiation (SR) - Aarhus Universitet · 2015-11-12 · Synchrotron radiation Wigglers, Undulators Monochromators Lecture 4a Søren Pape Møller – ISA Synchrotron Radiation

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Mirrors & Gratings

• Curved mirrors for

focusing

• Gratings for selection

of wavelength

• Normally q ~ 80 – 90º

– Reflectivity!

Focusing by mirrors: Example

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Gratings

• kN = sin(a)+sin(b)

– NB: b < 0

– N < 2500 lines/mm

• Optimization

– Max eff. for k = (-)1

– Min eff. for k = 2, 3

• Typical max. eff. ≈ 0.2

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Useful equations

• Bending radius

• Critical energy

• Total power radiated by ring

• Total power radiated by wiggler

• Undulator/wiggler parameter

• Undulator radiation

• Grating equation

2

0

22

2,2

12

K

n

unw

eVnm 1240 E

[m]

[GeV]21.2

4

3]keV[

33

R

E

R

hcc