The HIGS2 Concept A Next Generation Compton Gamma-ray Source

Transcription

1 The HIGS2 Concept A Next Generation Compton Gamma-ray Source Y. K. Wu FEL Laboratory, TUNL and Department of Physics, Duke University June 3, 2013 Acknowledgment: M. Busch, M. Emanian, J. Faircloth, G. Swift, P. Wang, P. Wallace; H. Hao, J. Li, S. Mikhailov, V. Popov, W. Z. Wu (DFELL, TUNL) Ph.D. Students: J. Yan, W. Zhou (Duke) Collaborators: Jun Ye, François Labaye (JILA) Work supported by U.S. Grant and Contract: DOE DE-FG02-01ER41175 and AFOSR MFELFA

2 Outline A Brief Overview of High Intensity Gamma-ray Source (HIGS) Worldwide Effort in Developing Compton Gamma-ray Sources The HIGS2 Concept Challenges and Critical Issues in Developing the HIGS2

3 Overview of High Intensity Gamma-ray Source (HIGS) Facility at TUNL

4 HIGS Accelerators High Intensity Gamma-ray Source (HIGS) Accelerators Accelerator Facility 160 MeV Linac pre-injector 160 MeV 1.15 GeV Booster injector 250 MeV 1.15 GeV Storage ring FELs: OK-4 (linear) and OK-5 (circular) Typical User Operation Modes FEL: single-bunch, up to 95 ma HIGS: two-bunch, ma

5 Operation Principle of HIGS HIGS Research Two electron bunches + two FEL pulses New Target Room? Target rooms 52.8 m Compton Gamma-ray Source A Photon and Electron Collider

6 Compton Scattering Photon Energy Relativistic ecircular Polarization max Head-on Collision: E ℏ 4 ℏ C. Sun and Y. K. Wu, Phys. Rev. ST Accel. Beams 14, (2011)

7 Compton Scattering Photon Energy Relativistic ecircular Linear Polarization Polarization max Head-on Collision: E ℏ 4 ℏ C. Sun and Y. K. Wu, Phys. Rev. ST Accel. Beams 14, (2011)

8 HIGS Capabilities: 3.5 ka OK-5 Gamma Energy Tuning Range with OK-5 FEL (3.5 ka) Gamma-ray energy range MeV (FEL: 1060 to 190 nm)

9 HIGS User Flux Capabilities with OK-5 FEL Highest Total Flux (2011): >2x 1010 γ 9 11 MeV HIGS World's Most Intense Compton γ-ray Source New Mirrors in 2010

10 3e. Gamma-ray Beam Pointing Stability Stability of Electron/Photon Collision Angle Pointing stabiliy: 2.5 µrad (peak-to-peak, 36 hr)

11 3-year HIGS Operation Summary HIGS Operation Summary (Aug Jul. 2011) Accelerator Operation Reliability: ~96% (Aug Jul. 2011)

12 3d. Gamma-ray Beam Imaging Gamma-beam Imager Part of Ph.D. thesis work of Changchun Sun

13 Worldwide Effort In Developing Compton Gamma-ray Sources

14 Compton Gamma-ray Facilities and Projects Around the World Past, Present, and Future Past Facilities: LADON, LEGS, GRAAL Operational Facilities and Development Projects: HIGS, LEPS, @SAGA ELI-NP MAX-IV Lab Canadian LS GRAAL MEGa-ray LEGS HIGS ELI-NP LADON ROKK NewSUBARU SAGA ETL-LCP LEPS UVSOR SLEGS Y. K. Wu, Duke University (2012)

15 New Compton Gamma-ray Sources ELI-NP, Extreme Light Infrastructure, Europe Facility/Project: ELI-NP Institution: Extreme Light Infrastructure (up to 4 facilities) Country: Europe Energy (MeV): 1 13 Accelerator: x-band Linac, 600 MeV, 250 pc, 120 Hz, high reprate: 12,000 (100 micro-bunches) Laser: Ring-down cavity (12 khz) 8 13 Total flux: 8x10 ph/pulse, 10 ph/s (an older design) Total flux: 2 orders of magnitude lower (a newer design) Status: Funded Sources: 1. The White Book of ELI Nuclear Physics Bucharest-Magurele, Romania, the ELI-Nuclear Physics working group, 2.

16 The HIGS2 Concept

17 The HIGS2 Concept Next Generation High Intensity Gamma-ray Source (HIGS2) Version 2012 Research Programs Hadronic Parity Violation Nuclear Astrophysics Dark-matter Search Projected Performance ~2 micron FP cavity: 2 12 MeV Total Flux: few gamma/s Pol: Linear, or Circular (rapid switch) Energy resolution (FWHM): < 0.5% A Prospectus Document for NSAC (Aug. 2012) HIGS2: The Next Generation Compton g-ray Source, M. W. Ahmed, A. E. Champagne, C. R. Howell, W. M. Snow, R. P. Springer, Y. Wu

18 2012/05/23

19 The HIGS2 Concept HIGS2 Layout (Version, 2012) am e b e am e b e Mirrors of FB cavity Lcav = m PFB (avg) > 10 kw, 90 MHz, fiber laser Collaborator: Jun Ye, JILA and U. of Colorado at Boulder

20 The HIGS2 Concept Expected Electron Beam Parameters Expected Electron Beam Parameters Parameter/Item Value Accelerator Duke Storage Ring New Magnetic Optics Interaction Point Design Beam Energy (MeV) Beam Current (ma) In development Bunch Pattern 32 Evenly Spaced Bunch Rep-rate (MHz) Bunch Separation (ns) 11.2 Charge/Bunch (nc) Bunch Duration (ps, FW) Accelerator Development Comments In development Phase I Developing new magnetic optics: design and optimization Realizing high current operation: current limit, stability Developing E-beam diagnostics, and characterizing e-beam Phase II Engineering design, followed by fabricating, testing, and preparing hardware components for the HIGS2 Upgrading injector Upgrading beam feedback and diagnostics Phase III: System integration and commissioning

21 The HIGS2 Concept Projected Laser Beam Parameters Projected Laser Beam Parameters Parameter/Item Value Comments Drive Laser System Fiber Laser What type of fiber laser? Wavelength (nm) TBD Input for HIGS2 Workshop Average Power (W) Pulse Rep-rate (MHz) Pulse Duration (ps, FW) 5 20 Fabry-Perot Cavity 2-mirror resonator Cavity Length (m) In-cavity Power (kw) Goal: λ/λ < 10-3 Laser and FP Cavity Development Phase I Prototype laser Prototype FP cavity Phase II Developing production laser system Developing production FP cavity Developing optical diagnostics for polarization controls and monitoring Phase III: System integration and commissioning

22 The HIGS2 Concept Time Structures of Electron and Laser Beams

23 HIGS2 Projected Performance Summary A Prospectus Document for NSAC (Aug. 2012) HIGS2: The Next Generation Compton g-ray Source, M. W. Ahmed, A. E. Champagne, C. R. Howell, W. M. Snow, R. P. Springer, Y. Wu

24 Challenges and Critical Issues for Developing the HIGS2 Challenges with Developing Electron Source and Accelerators New 32-bunch Operation Mode for Duke Storage Ring (Prelim Results) New, Optimized Magnetic Optics (Prelim Results) Stabilizing Electron Beam Operation Challenges with the Photon Source Drive Laser FP Cavity

25 Development of Electron Source and Accelerators New 32-bunch Operation Mode for Duke Storage Ring: ma (in progress) New, Optimized Magnetic Optics for Storage Ring: Physics Design (in progress) Stability of Electron Beam Operation Orbit stability (fast motion, long-term) Transverse beam size stability Longitudinal beam size stability Beam parameters for various operation parameters Impact of top-off injection

26 HIGS2 Development New Mode of Operation: 32-bunch Beam (Prelim Results) Test Results with 32-Bunch Beam Operation with Longitudinal Feedback ( 2013) E-beam Energy (MeV) Max Curr (ma) Stability Limitation Comments Long. Stable Inj. Rate Slow damping Long. Stable Inj. Rate Slow damping Long. Stable Inj. Rate Issues: Max current limited by injection Low injection rate (4 6 ma/min, initially) Further stability improvement needed (transverse)

27 HIGS2 Development Accelerator Development Projects Accelerator Development Projects High Current 32-bunch operation (continuing) Developing New Storage Ring Magnetic Optics (continuing) Related to Injector and Injection Scheme Increasing charge injection rate (x5) Improving stability and reliability of linac injector (new klystrons/modulators) Reducing negative impact on the stored beam during injection Related Storage Ring Fast orbit feedback system Transverse feedback system to combat coupled bunch instabilities Fast orbit stability during top-off operation Characterizing beam performance for various operation parameters Related Laser System IP optimization Synchronization with the Drive Laser Infrastructure Modification

28 HIGS2 Development Photon Beam System Development of Drive Laser and Fabry-Perot Cavity Drive Laser What wavelength? What type of fiber laser? Narrow spectrum of the laser beam Stability of the laser beam power, fast and slow time scales Polarization controls and fast switches of helicity Fabre-Perot Cavity Design of the FB cavity Matching with the electron beam Related feedback and stabilization systems, and optical diagnostics Mirror lifetime and radiation damage Stability of the photon beam in FP cavity, fast and slow time scales

29 HIGS2 Development Photon Beam System State-of-the-art Fiber Lasers JILA (Joint institute of U. of Colorado and NIST) Erbium fiber laser (1.5 microns) Ytterbium fiber laser (1 micron) High Power FB Cavity with frequency comb technology, 10 kw (stable beam) Spectral width: how to achieve Higher power: stability? 10-3 or What Wavelength? Thulium fiber laser (2 microns) Challenges Freq. Comb? better? Polarization controls and switch Power stability

30 The HIGS2 Project TEAM (Unfunded Effort as of June 2013) DFELL, TUNL, Led by Ying K. Wu Engineers and Technical Staff: Matthew Busch, Mark Emamian, Joe Faircloth, Gary Swift, Pat Wallac; Marty Johnson, Maurice Pentico, Vern Rathbone Scientists: Hao Hao, Jingyi Li, Stepan Mikhailov, Victor Popov, Wenzhong Wu, Ying K. Wu Graduate Students: Jun Yan, Weizheng Zhou New Hires: Additional scientific, engineering and technical staff JILA (U. of Colorado and NIST), Led by Jun Ye Scientists, graduate students, and other staff Focus on the drive laser system and Fabry-Perot cavity system Other Collaborators (TBD) With Nuclear Physicists, Laser Physicists, and Accelerator Physicists

31 HIGS2 Major Areas of Cost for HIGS2 Source Development Main Areas Photon Source Electron Beam Source HIGS2 Flux Performance and Reliability Subsystems IR Laser Prototype and Production Laser System Fabry-Perot Cavity Prototype and Production Systems and Related Optical Systems Collision Beamline and Magnetic/Vacuum System Accelerator Diagnostics and Controls Accelerator Infrastructure Injector Upgrade (Linac, and other subsystems) Beam Feedback and Advanced Manipulation/Controls Comments JILA JILA and DFELL DFELL DFELL DFELL DFELL DFELL with Collaborators TBD

32 HIGS2 Facility and Scientific Program HIGS2 Facility ===> <=== Scientific Program

33 HIGS2 Development Gamma-ray Parameters From Nuclear Physicists For Each Experiment or a Set of Experiments Name of Experiment Gamma-Beam Parameters Gamma-ray Energy Range (MeV) Energy Resolution (FWHM) (%) Gamma-ray Flux on Target (g/s) Degree of Polarization Linear Circular Helicity Switch (Yes/No) Rate (Hz) Stability of Flux Stability of Polarization More... Min. Requirement Preferred Comments

34 Compton Gamma-beam Radiograph 2

35 Thank You!