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

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Crab Nebula - the first Synchrotron source observed?? Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Center for Advanced Microstructures and Devices CAMD in Baton Rouge, LA Center for Advanced Microstructures and Devices Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Accelerator Synchrotron Radiation Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Accelerated Charge Radiation Lienard July 1898 Discovery of Electron JJ Thompson October 1897 Accelerated Charge Radiation Lienard July 1898 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

ELECTROMAGNETIC RADIATION Field lines from a stationary charge Field lines from an accelerated charge Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Spatial distribution of radiation from a charge accelerated z Spatial distribution of radiation from a charge accelerated along the z axis x y Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Acceleration by Induction - The Betatron Principle of Betatron Acceleration Coil Steel Vacuum chamber Cross section of a Betatron Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Prediction of Energy loss by radiation in an accelerator Iwanenko & Pomeranchuk June 1944 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

GEC(USA) electron accelerators 1946 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Light from the GE Synchrotron 1947 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Betatron - CERAMIC Synchrotron - GLASS Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 = 900 then q = g-1 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

~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 = 3914 g3 =6.0 1010 100m 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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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!!! Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Synchrotron Radiation Spectra Examples of spectra produced by electron storage rings:- Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Typical Synchrotron Radiation Spectra CAMD APS NSLS-VUV Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Typical Synchrotron Radiation Spectra 2 APS CAMD VUV Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Radiation excitation and damping of oscillations Dispersion Betatron oscillation Radiation excitation Initial momentum Final momentum RF restores Radiation loss Radiation damping Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Minimum emittance of Chasman-Green lattice Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Theoretical Minimum Emittance lattice Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

APS at Argonne National Laboratory Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Proposed South East Advanced Light Source (2) Energy 2.5 GeV Circumference 190 m Emittance 4.7 nm rads Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Wiggler or Wavelength Shifter Placed in a straight section Net deflection zero High magnetic field 5-10T Large horizontal fan ~200 mr Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

CAMD Wiggler Central pole 7 Tesla End poles 1.5 Tesla Made by Budker Institute Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

SRS Daresbury 6 Tesla Wiggler Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Multi Pole Wiggler Multiple alternating poles High magnetic field 2-5T Small horizontal fan ~20 mr Superposition of source points Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

SRS Daresbury 2.4 Tesla Permanent Magnet MPW Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Undulator Multiple alternating poles Period lu = 10s of mm Beam deflection < 1/g Interference makes line spectrum Very high brightness Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Undulator correct theory It is essential to account for the transverse motion of the electron in the undulator. Introduce the deflection parameter k Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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,… Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Undulator Spectrum (calculated) Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

ESRF Undulator Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

In vacuum Undulators – for small gap / period SRC Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

SRC Wisconsin 6 EM Undulator Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Elettra – SLS Helical Wiggler/Undulator Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

SE-ALS Undulator 50 mm Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Oscillator type Free Electron Laser Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

SASE type Free Electron Laser SASE = Self Amplification of Spontaneous Emission Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Free Electron Laser- present limitations Wavelength limited by mirrors - use SASE Low rep rate hence low average brightness - use Energy Recovery Linac Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Energy Recovery Linac Superconducting RF High brightness cw e-gun Low energy beam dump SASE Free Electron Laser Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

Conclusion for Synchrotron Radiation The Future is EVEN BRIGHTER than this! Thank You! Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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=1.43 1014 I0 Qn(k) photons/sec/0.1% bandwidth fn is a numerical factor, related to k. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury