Storage Ring Compton Light Sources

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1 Storage Ring Compton Light Sources Acknowledgment: M. Busch, M. Emanian, J. Faircloth, S. Hartman, J. Li, S. Mikhailov, V. Popov, G. Swift, P. Wang, P. Wallace (DFELL) M. Ahmed, T. Clegg, H. Gao, C. Howell, H. Karwowski, J. Kelley, A. Tonchev, W. Tornow, H. Weller (TUNL) HIGS Collaborators DFELL, Triangle Universities Nuclear Laboratory Department of Physics, Duke University March 2, 2010 Work supported by U.S. Grant and Contract: DOE DE-FG02-01ER41175 and AFOSR MFELFA

2 Outline Compton Gamma-ray Sources A brief historical overview Major Compton gamma-ray facilities New projects High Intensity Gamma-ray Source (HIGS) Accelerator facility Operation modes Beam diagnostics Optical resonator issues High flux operation Issues with Compton Light Sources: focus on Gamma-ray Source Accelerators Laser beams Energy range Impacts on LS operation due to Compton gamma-ray source

3 History of Compton Light Sources Early History Early 1920's, Arthur Compton, Discovery of Compton Effect A. H. Compton, Bulletin Nat. Res. Council (U.S.) 20, 19 (1922); Phys. Rev. 21, 483 (1923) 1963, Milburn, and Arutyunian and Tumanian, first proposed γ-beam production via Compton backscattering of photon with accelerator based high-energy electron beam R. H. Milburn, Phys. Rev. Lett. 10, 75 (1963). F. R. Arutyunian and V. A. Tumanian, Phys. Lett. 4, 176 (1963) , the first Compton γ-ray beam experimental demonstrations, Kulikov et al.with a 600 MeV synchrotron Bemporad et al. with the 6.0 GeV Cambridge Electron Acclerator O. F. Kulikov et al., Phys. Lett. 13, 344 (1964); C. Bemporad et al., Phys. Rev. B 138, 1546 (1965) , Ballam et al. with the 20 GeV Stanford linear Acclerator, first physics measurements using Compton γ-ray beam to study the photo-production cross section (~GeVs) with a hydrogen bubble chamber J. J. Murray and P. R. Klein, SLAC Report No. SLAC-TN-67-19, unpublished (1967). J. Ballam et al., Phys. Rev. Lett. 23, 498 (1969).

4 History of Compton Light Sources Major Compton Gamma Source Facilities (1970's 1990's) , LADON, ADONE storage ring, Frascati, Italy The first γ-ray Compton light source facility for nuclear physics research, by colliding electron beam (1.5 GeV) inside a laser cavity. It produced polarized γ-ray beams up to 80 MeV with an on-target flux of up to 5x10^5 s 1 for nuclear experiments. L. Casano et al., Laser and Unconv. Opt. J. 55, 3 (1975). G. Matone et al., Lect. Notes Phys. 62, 3 (1977). L. Federici et al., Nuovo Cimento Lett. 27, 339 (1980). L. Federici et al., Nuovo Cimento B 59, 247 (1980). D. Babusci et al., Nucl. Instrum. Methods A 305, 19 (1991) , LEGS, NSLS x-ray ring, Brookhaven National Lab, US A. M. Sandorfi et al., IEEE Trans.NS-30, 3083 (1984) persent, ROKK-1/ROKK-2/ROKK-1M, Budker Institute of Nuclear Physics, Russia G. Ya. Kezerashvili et al., Nucl. Instrum. Methods A. 328, 506 (1993). G. Ya. Kezerashvili et al., AIP Conference Proceedings 343, 260 (1995). G. Ya. Kezerashvili et al., Nucl. Instrum. Methods B. 145, 40 (1998) , GRAAL, ESRF storage ring, ESRF, Grenoble, France A. A. Kazakov et al., JETP Lett. 40, 445 (1984) present, HIγS, Duke FEL storage ring, Duke University, US V. N. Litvinenko et al., Phys. Lett. 78, 4569 (1997) present, LEPS, Spring-8 storage ring, Spring-8, Japan T. Nakano et al., Nucl. Phys. A 629, 559c (1998). T. Nakano et al., Nucl. Phys. A 684, 71c (2001).

5 History of Compton Light Sources H.R. Weller et al. Progress in Particle and Nuclear Physics 62, p (2009).

6 New Compton Source Projects A Few New Compton Source Projects in Planning and Development Shanghai Laser Electron Gamma Source (SLEGS), Shanghai Synchrotron Radiation Facility (SSRF) 3.5 GeV electron beam and a 500 W CO 2 polarized laser An energy up to 22 MeV and a flux of γ/s Q. Y. Pan et al., Synchrotron Radiation News, Volume 22, Issue 3, p. 11 (2009). Compton Gamma Source Project at MAX-lab 3 GeV electron beam from the MAX IV storage ring to be built, up to 500 ma An ultraviolet (UV) laser beam The maximum gamma-ray energy around 500 MeV A tagged flux as high as a few times 10 7 γ/s L. Isaksson, MAX-lab, Lund, Sweden, private communication (2009). Laser-Electron Photon 2 (LEPS2), Spring-8 For conducting research in the quark-nuclear physics Higher intensity and higher maximum energy compared with LEPS Expanded detector acceptance for a 4π γ-detector. The LEPS2 website, and the 2006 RCNP Annual Report, for example,

7 Major Compton Gamma Source Facilities Around the World MAX-Lab GRAAL ROKK HIGS LEGS LADON LEPS SLEGS

8 A Storage Ring Compton Gamma Source High Intensity Gamma-ray Source (HIGS) at Duke University

9 HIGS Accelerators High Intensity Gamma-ray Source (HIGS) Accelerators Recent Accelerator Upgrades New lattice for OK-5 FEL New HOM-damped RF cavity New OK-5 FEL with circular polarization A New Booster synchrotron for top-off injection Typical User Operation Modes FEL: single-bunch, up to 95 ma HIGS: two-bunch, ma

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11 OK-5 and OK-4 FELs (Since Aug. 2005) HIGS Accelerators OK-5 wigglers e-beam OK-5 helical wiggler, OK-5A OK-4 Planar wigglers OK-5 helical wiggler, OK-5B OK-4 wigglers m

12 Operation Principle of HIGS HIGS Research 52.8 m

13 Operation Modes of HIGS Operation Modes of HIGS Qusi-CW operation vs Pulsed High-flux vs high energy resolution HIGS Research FWHM

14 High Energy-Resolution Operation HIGS Research Asymmetric Bunch Pattern: one large (lasing) and one small (non-lasing) Improving stability of gamma energy resolution and increase flux Develop a reliable way to measure bunch pattern, and An automatic injection scheme to maintain charge distribution

15 Beam Diagnostics/Feedback Electron/Photon Collision Angle Monitor

16 Beam Diagnostics/Feedback Bunch Length and FEL Spectrum Monitors Beam Diagnostics Live Spectrum Monitor Live bunch length monitors 349 MeV, 27 ma

17 Beam Diagnostics/Feedback Bunch-by-bunch Longitudinal Feedback Providing bunch-by-bunch damping of longitudinal instabilities LFB BPM igp-64f Digital signal processing system MILMEGA 200 W Power amplifier Feed through With. Nose cone Commissioned for User Operation (Oct., 2008) Pill-box cavity Beam pipe Part of Ph.D. thesis work of Wenzhong Wu

18 Beam Diagnostics/Feedback LFB Stabilizing Longitudinal Motion Synchrotron sidebands Synchrotron sidebands? LFB LFB ONOFF MeV, MeV, 4-bunch, 4-bunch, ma ma Part of Ph.D. thesis work of Wenzhong Wu

19 Beam Diagnostics/Feedback In-cavity Aperture System for High Current Operation Electron Beam Mirror Aperture WIG01 WIG02 WIG03 WIG03 Mirror Lw = 4 m 6.72 m 6.72 m Collision Point 6.72 m m m 4.58 m Part of Ph.D. thesis work of Senlin Huang NIM A 606, p. 762 (2009).

20 Correcting Mirror Deformation Beam Diagnostics/Feedback 45 MeV Setup with OK-5 FEL

21 HIGS Summary Stability of Gamma Operation in Electron Loss Mode Current Current Gamma flux Gamma flux with closed apertures

22 High Reflectivity FEL Mirrors High-Finesse FEL Resonator 780 nm Mirrors Minimal round-trip loss: ~ 0.107% Low power ~ 3,000 Effective: R ~ 99.95% Kicker firing 761 nm, Loss ~

23 High-Finesse FEL Resonator High Reflectivity FEL Mirrors Mirror degradation Carbon deposition on the surface Vertical Horizontal 780 nm, CCV020, downstream cavity mirror, D=50 mm

24 Intracavity FEL Power Measurement Experimental Layout Ebeam: 514 MeV, about 88 ma in two equally populated bunches FEL beam λ = 545 nm; Gamma-beam collimator: d = 0.75 Collimated (d=3/4 ), γ-beam image Collimated flux: 3.68% 12m

25 Intracavity FEL Power Measurement Intracavity FEL Power Measurements: γ-spectrum Ebeam: 514 MeV, about 88 ma in two equally populated bunches FEL beam λ = 545 nm; Gamma-beam collimator: d = 0.75 C. Sun et al. NIMA 605, p 312(2009) Avg Flux Density from 11 B at MeV True γ-spectrum 11 B data: P b = 800 (+/-100) W, P FEL = 1.6 kw (+/- 0.2 kw)

26 Intracavity FEL Power Measurement Intracavity FEL Power Measurements Ebeam: 514 MeV; FEL beam λ = 545 nm; Collimator: d = 0.75 HPGe data Preliminary Results: HPGe data

27 Gamma Energy Tuning Range with OK-5 FEL (3.5 ka)

28 Highest Total Flux (2009): > MeV H. R. Weller et al., Research Opportunities at the Upgraded HIγS Facility, Prog. Part. Nucl. Phys. Vol 62, Issue 1, p (2009).

29 Nuclear Physics and Astrophysics Nuclear Physics and Astrophysics Research at HIGS Nuclear Structure Few-Nucleon Physics Astro-physics Gerasimov-Drell-Hearn (GDH) Sum Rule Compton Scattering from Nucleons Photon-Pion Physics HIGS H. R. Weller et al., Research Opportunities at the Upgraded HIγS Facility, Prog. Part. Nucl. Phys. Vol 62, Issue 1, p (2009).

30 Accelerators for Compton Light Sources Advantages of storage rings High repetition rate Orbit stability and beam stability (at higher energies) Adequate ebeam emittance and energy spread Known technologies Powering a high average flux Compton source Other Accelerators Warm temperature Linacs: Low rep-rate pulsed operation Expensive laser Less stable Powering a high peak flux source Super-conducting linac (e.g. ERL) High rep-rate Costly Less mature technology A potential driver for very high average flux source

31 Tuneable wavelength => a large Compton photon energy range Self-synchronization and self alignment Complex and Expensive High intracavity power Driver for a versatile, high-flux Compton source for a wide range of research programs External Lasers Ti:sapphire m TW lasers, low reprate, time syn, low stability, costly CW lasers Laser Cavities Used in LADON project (low finesse) High finesse Fabry-Perot cavity DC laser with high finesse JLAB, Compton polarimeter, 1064 nm, finesse 30,000, 1.6 kw CW pulsed laser V. Brisson, e t al. Nucl. Instrum. Meth. A 608(2009)S75 S77 Laboratoire de l Acce le rateur Line aire, C.N.R.S./IN2P3, 48 th ICFA Future Orsay, Light Sources FranceWorkshop (FLS2010), SLAC Ti:sapph, 76 MHz, 1 ps, finesse 30,000

32 0.1 ev photons, kev x-rays, e-beam: MeV; 1eV photons, kev x-rays, e-beam: MeV; E-beam, 2 GeV, 0.1 ev photons, γ-ray: 6 MeV E-beam, 2 GeV, 1 ev photons, γ-ray: 60 MeV E-beam, 3 GeV, 0.1 ev photons, γ-ray: 14 MeV E-beam, 3 GeV, 1 ev photons, γ-ray: 140 MeV Figure of Merits for Gamma-ray Beams: Brightness is no longer a good figure of merit for gamma-ray beam New merits: flux (γ/s), spectral flux (γ/s/ev, avg, peak), relative energy spread (FWHM) Compton X-ray Source Driven by a Storage Ring Don Ruth, SLAC, Next talk: Experience with the Compact light source

33 Critical Issues for Storage Ring Compton Gamma Sources Impact On the Storage Ring Light Source when Operating Compton Gamma Source as an Optical Insertion Device (OID) Effect of Electron Loss When Compton scattered electron loses more energy than allowed by the energy aperture (smaller of energy dynamic aperture and energy acceptance limited by RF/vacuum chambers). Two strategies: Hide loss among beam lifetime Electron-loss mode operation (Energy loss > Aperture) Good for higher energy gamma operation Limited flux: 10^6 few 10^7 γ/s Gamma-ray energy determination: Tagging of electrons Prevent electron loss No-loss mode (Energy loss < Aperture) Good for lower energy gamma operation High flux possible (greater than 10^9 γ/s) Gamma-ray energy selection: Collimation of gamma-beam Impact on Electron Beam Parameters An issue with extremely high flux operation Impact on e-beam energy and longitudinal distributions (estimates using damping wiggler model; need real simulation) Impact on transverse beam distribution (emittance)

34 High gamma beam energies <=> User research programs Additional flux limitation due to tagging rate, 10^5 10^6 e - /s per tagging channel High efficincy: tagging a large amount of Compton gamma-rays: 30% - 60% Energy resolution as limited by the absolute energy spread of the e-beam Example: 3 GeV e-beam, 0.1% (sigmae), 150 MeV gamma-ray de (FWHM) = 7.1 MeV; de/e (γ,fwhm) = 5%; Reliability of tagging signal at high rates Collimation Low gamma beam energies <=> User research programs If OID, fixed gamma energy with a fixed e-beam energy; how to vary gamma energy? Potentially very high flux Low efficiency: collimation selects only a few percent Compton gamma-rays Challenge in high precision flux measurement (pileups, scattering, secondary particles, etc) Energy spread issues: collimation effect, e-beam energy spread, emittance effect Long beamline Good e-beam aiming stability Example: 3 GeV e-beam, ~5% γ-beam energy spread (FWHM) Half opening angle: 30 micro-radians If collimator aperture r = 3 mm, beamline length ~ 100 m; Stability of ebeam aiming; a few micro-radians

35 Energy Spread of γ-beam Energy Distribution of Compton Gamma-beam Monochromatic E-beam Collimator Emittance Energy electron Spread Effect and Effect photon (Scaled) (Scaled) beams New Merit: Degree of Collimation Part of Ph.D. thesis work of Changchun Sun Phys. Rev. ST Accel. Beams 12, (2009)

36 Industrial and Medical Applications Compton Gamma-beam Imaging at HIGS Polarization Effect: Linear vs Circular 22.5 MeV Gamma-beam 680 MeV-ebeam, 378 nm FEL, 27 m from collision

37 Industrial and Medical Applications Compton Gamma-beam Imaging at HIGS Imager Resolution Test with a bar phantom test and 2.75 MeV gamma-beam

38 Industrial and Medical Applications Compton Gamma-beam Radiograph

39 The End

40 1 MeV Gamma-beam High Resolution Mode:

41 Switch-yard for OK-4 and OK-5 Wigglers Photon-pion physics MeV operation with the OK-5 FEL lasing around 150 nm

42 Summary High Intensity Gamma-ray Source Development and User Research An Overview of HIGS Accelerator Facility and Development Program: Accelerator Physics and FEL Research An Overview of HIGS User Research Program: Nuclear Physics Program HIGS Capabilities (2009) Energy Tuning: MeV Maximum Total Flux: > γ/s around 9-10 MeV Maximum Spectrum Flux: : ~ 10 3 γ/s/ev around 5-10 MeV High Energy Resolution: 0.8% (< = 5 MeV) Polarization: linear, and switchable left- and right-circular HIGS Near-Term Development Higher Gamma-beam Energy: MeV for photon-pion physics research Higher Flux Operation: γ/s total below 20 MeV

43 HIGS Operation Summary (Aug. 1, 2008 Jul. 31, 2009) HIGS beam-on-target: 1584 hr

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46 Industrial and Medical Applications Compton Gamma-beam Imaging AIST, Tsukaba, Ibaraki, Japan Radiograph TH571A Tetrode tube H. Toyokawa, NIM A545, p. 469 (2005) Sample CT images using 10 MeV LCS photon beam

47 High-Finesse FEL Resonator High Reflectivity FEL Mirrors High Reflectivity Mirrors ( nm) Spec: R > 99.95% Example: transmission nm (Vendor measurement) General Optics, GSI (2008) T min ~ %

48 Intracavity FEL Power Measurement Intracavity Ebeam: 514 FEL MeV; Power FEL beam Measurements λ = 545 nm; Collimator: d = 0.75 HPGe data Preliminary Results: HPGe data

49 Industrial and Medical Applications Radiation Therapy and Diagnostics Radioisotopes Cancer treatment: g/s Diagnostic: g/s 15 MeV Compton g-beam g-beam from 15 MeV Linac K. J. Weeks., NIM A393 (1997) p

50 Industrial and Medical Applications Radiation Therapy and Diagnostics Radiation Dose for Cancer Treatment A solid epithelial tumor ranges: Gy Lymphoma tumor: Gy B Girolami et al. Phys. Med. Biol._v41, p1581(1996).

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