Advancements in Compton Sources for X-ray Applications

1. Alessandro Variola (LNF INFN) alessandro.variola@lnf.infn.it Compton sources for g and x ray applicationsWork supported by the EQUIPEX program, the Ile de

2. Compton backscattering sources • Compton Back Scattering (CBS) • Counter propagating electron and lasers beams. • Photon backscattering • Why CBS sources ? • CBS is by far the most efficient photon energy amplifier : wdiff=4g2wlaser, for example => g~100 => it is possible to have at one’s disposal hard X rays with a relatively low energy electron machine. • But for a light source: s ~ 6.6524 10-25 cm2 , it is low!!!!! • Need of a lot of photons and electrons, depending form the considered configuration for instantaneous or average brillance. • CBS attractiveness : • 1) Directivity (relativistic boost) = > f= 1/g around the electron direction • 2) Energy angle dependence => monochromatic by diaphragm • 3) Polarized if needed • 4) Backscattered spectrum cut off => Energy dependence on collision angle

3. 1rst interest: the energy boost • (no polar. are observed) Energy distribution ~flat with w2,max=4g2wlaser with g~100 (Eelectron=50MeV) w2,max=45000eV if wlaser~ 1eV Compton scattering is the most powerful mechanism to boost photon energies The cut off is dependent on the incidence angle !! (factor two up to p/2) • Sprangle et al. JAP72(1992)5032

4. collimator wf(keV) q(mrad) • 2nd interest: the angular energy correlation • Compton scattering • Photon_laser+e photon+e’2 body process  wf = f(q) • Sprangle et al. JAP72(1992)5032 •  ~monoenergétic beam by selecting Backscattered photons at wf,max • Eelectron=50MeV

5. RMS bandwidth, due to collection angle, laser phase space distribution and electron beam phase space distribution • laser • electron beam • Diaphragm • L.Serafini

6. ►So : What we can do with this?

7. Applications of Compton scattering: quasi monochromatic X/g ray beam • Compact sources for high energy gammas g~100 MeV g ~1MeV • Elec.~20-100MeV • Elec. 1GeV • Elec.~100-750MeV wf,max MeV • X ray ~10-100keV • High energy applications • Compton polarimeterLEP energy measurement • Laser wire • gg collider • Polarised positron source • Low energy applications • Medical: radiography &radiotherapy • Museology • Material science • crystallography • Nuclear fluorescence applications • Nuclear survey • Nuclear waste management • Nuclear science

8. ►In many scientific domains synchrotron sources are currently the only machines in term of brightness to perform and carry out the most ambitious analyses and searches requiring ~ 10-100 KeV X-rays. ► Synchrotron sources : - very powerful, but, - not very “pratical” for some applications, - limited access time. ► With Compact sources : Methods currently used at synchrotrons (diffraction, absorption, diffusion, imaging, spectroscopy…) could be largely developed in a laboratory size environment (hospitals, labs, museums). ‘compact’ source for nuclear physics photons (MeV range) -Nuclear safety -Nuclear waste management -Radioisotopes detection

9. Compton and other sources, X rays • ►X-ray tubes • - The most efficient are rotating anodes • - Rigaku ~ 1010 ph/sec , polychromatic • ►Plasma sources • Ultra-short pulses ~ fs , • but very low fluxes. • CCS •  These sources does not allow to carry out • many of the techniques used at synchrotrons • ► Compact Compton Sources (CCS) •  Compactness ( surface ~ 100 m2 ) • (Integration in hospitals, labs, museums) •  Relative high intensity (1012 – 1014 ph/sec) •  Tunable beam (Linac configuration) •  High quality beam (brightness 1011 – 1015 ph/sec/ mm2 / 0.1% bw / mrad2) • 10-100 KeV • M.Jacquet

10. For example: medical science and cultural heritage • K-edge imaging (Pbwhite, Hg vermilion…) of a Van-Gogh’s painting • J. Dik et al., Analytical Chemistry, 2008, 80, 6436 • Painting analysis • Physiopathology and Contrast agents, • Dynamic Contrast Enhancement SRCT • Convection Enhanced Delivery =>Stereotactic Synchrotron RT • Paleontology • Non-destructive analysis • Biston et al, Cancer Res 2004, 64, 2317-23 • Imaging, • Mammography • Microtomography • J Cereb Blood Flow and Metab, 2007. 27 (2):292-303. • Journal of Radiology 53, 226-237 (2005) • Acknowledgments to G.Le Duc, P.Walter

11. Potential of applications of X-ray CCS • 1. Using the 2D divergent beam • (biomedical and cultural heritage • applications) • - Conventional radiography • - K-edge substraction imaging • - Phase contrast imaging • - Magnification • - Radiotherapy •  Measure large sample with • no more need to move it • (patient, materiel …) • IMAGING • Pink beam (3-30% bw) • 2. Using the central part of the beam • (cultural heritage / material science applications) • Quasi-monochromatic beam (~ 0.1% - 0.01 % bw) • - Fluorescence Spectroscopy • - XANES Spectroscopy • - Diffraction •  Structural analyses •  Pump-probe experiments • Toward sample • + Optics : mono, … • Focus device • IP

12. K Edge • 1. Using the 2D divergent beam • (biomedical and cultural heritage applications) • ` • absorption • After threshold • «opaque» • - Tunable energy • - bw 2-3% • - Conventional radiography (30%) • - K-edge substraction imaging • - Phase contrast imaging • - Magnification • - Radiotherapy • energy • Before threshold « transparent » • K-edge at ESRF (using a contrast agent) •  The difference of both increase the contrast

13. Biomedical :Phase contrast • imaging human breast tissue at synchrotron ESRF • Mapping of a breast tissue sample • a) Histological section • (used as a standard for interpretation) • Clinical planar screen-film • mammogram taken at the hospital • c) Clinical scanner • ID17 ESRF (Phase contrast imaging) • Same dose as c) • Stronger contrast •  Improvement in the vizualisation of • the morphology and of the overall • architecture of the breast tissues • ( Phys. Med. Biol. 52, 2007, 2197-2211 )

14. Potential of applications of X-ray CCS: Examples - bw 2-3% - Small source size (to have transv. coherence) - Conventional radiography - K-edge substraction imaging - Phase contrast imaging - Magnification - Radiotherapy CS Lyncean Tech. 13.5 KeV , 3% bw 109 ph/sec σ = 165 μm [ Synch. Rad. 16, 2009, 43-47 ] Proof of principle standard absorption phase-contrast Hospital sources (large focal spot size, broad spectrum, low flux)

15. Bio Medical imaging, phase contrats, tomography K.Achterhold

16. Potential of applications of X-ray CCS • 1. Using the 2D divergent beam • (biomedical and cultural heritage applications) • - Conventional radiography • - K-edge substraction imaging • - Phase contrast imaging • - Magnification • - Radiotherapy • - High energy (~ 80KeV) • - bw ~ 10% • • • • ESRF/ID17 ( ~ 6 mGy/sec) • • Hospital sources  broad spectrum, • and continuously operation not possible • Ex. : Human head tumor • (tumor deliver dose ~ 10-20 Gy) • Int J RadiatOncolBiolPhys 68 (2007), no. 3, 943-951. Convection-enhanceddelivery of an iodine tracer into rat brain for synchrotron stereotacticradiotherapy.

17. Cultural Heritage – X rays

18. K Edge imaging, XRF

19. R.Hajima

21. Production of radioisotopes for medical applications • Optimization of the beam and target parameters for achieving high specific activity after irradiation • test case: 100Mo(γ,n) • Specific activities of 0.45 mCi/g can be obtained for 99mTc and 1.2 mCi/g for 187Re considering a beam of 5·1010γ/s

22. High energy physics

24. Gamma-gamma collider for the study of g-g events generation Parameter of the Compton sources Total energy of the g-g system: 2 MeV Electron energy: 250 MeV Electron emittance: 0.4 mm mrad Electron energy spread: 0.7 10-4 Charge: 250 pC Transverse electron width:1 mm Laser wavelength: 1000 nm Laser waist: 10 micron Laser Energy: 1 J Photon energy: 1 MeV Transverse photon beam dimension: 1 mm Transverse photon beam dimension at IP: 10 mm Repetition rate f: 100 Hz Results of a Monte Carlo dedicated code 1 event/h

25. SOURCES

26. Cross section problemMatching the accelerator with the optical systems • High intensity, beams and laser pulses. • J classes lasers @ few Hz. • Optical recirculation to match multibunch patterns • Multipass regenerative cavities • High repetition frequency • Storage rings – SC or ERLS (from few MhZ to 100 MHz) • Fabry Perot cavity (100 kW – to 1 MW – R&D Classes) • High rep rate, high average power fiber lasers (1 kW class)

27. CALA Munich • ELI NP

28. Compton facilities

29. First Compton X Ray light source : LynceanTech

30. Can be integrated …..

31. Nuclear physics . HIGS

32. RF amplifiers • Inverse Compton scattering • 30 kW beam dump • Superconducting RF photoinjector operating at 300 MHz and 4K • Bunch compression chicane • X-ray beamline • 1 MeV • 30 MeV • 5 kW cryo-cooled Yb:YAG drive laser • Electron beam of ~1 mA average current at 10-30 MeV • Coherent enhancement cavity with Q=1000 giving 5 MW cavity power • 8 m • RF amp • RF amp • RF amp SRF Compact Light Sources @ 4K, MIT CUBIX • W.S.Graves

33. ThomX • Cycle Frep = 20 msec • RF pulse length 3 ms • Energy 50 - 70 MeV • Laser and FP cavity • 2 Ips • Easy integration • Frees the straight sections • CSR line

34. UH-FLUX – conceptual layout • Brightest Compton • X-ray Source • A.Seryi

35. ELI NP GBS

36. Optical system: laser beam circulator (LBC)for J-class psec laser pulses focused down to mm spot sizes Circulator principle PARAMETERS = OPTIMIZED ON THE GAMMA-RAY FLUX Laser power = state of the art Angle of incidence (φ = 7.54°) Waist size (ω0 = 28.3μm) Number of passes = 32 passes • 2 high-grade quality parabolic mirrors • Aberration free • Mirror-pair system (MPS) per pass • Synchronization • Optical plan switching • Constant incident angle = small bandwidth • 30 cm • 2.4 m • K. Cassou, F.Zomer

37. UCLA - Radia Beam • Alex Murokh

38. Conclusions and outlook • Compton sources are in rapid development • Energy boost -> low dimensions and costs, directivity, polarization, tunability (gamma, angle, laser frequency…..) • Playing with parameters, tunability, spectrum, bandwidth, schemes, technology, subpicosecond…it’s an open field • Large cone is not always a problem, can be an advantage • Sub ps regime si possible in pi/2 configuration • Many different new ideas can be applied.... • At present 109-1011 , near future 1012-1013...but 1015 are not so far...