Gwyn P. Williams, Mike Klopf & the JLab Team Jefferson Lab - PowerPoint PPT Presentation

Applications of Intense CSR from a cw cw Linac Linac at Jefferson Lab at Jefferson Lab Applications of Intense CSR from a Gwyn P. Williams, Mike Klopf & the JLab Team Jefferson Lab 12000 Jefferson Avenue Newport News, Virgnia 23606 UVSOR Workshop on Terahertz Coherent Synchrotron Radiation September 23-25, 2007

Introduction to the Jefferson Lab CSR THz Source Source Characteristics • 1 microJoule per pulse, 75 MHz, 180 fs FWHM 10 MW peak, 100 Watt average power • Achieved using superconducting linac with cw rf

Overview of the CSR THz Programs at Jefferson Lab • Tissue interactions and safety limits. • Imaging. • Spectroscopy development – signal to noise etc.. ⇒ magnetism, dynamics of quasiparticles, spin ⇒ localization effects Future • Electro-optical detection • Quantum coherence and control. • Coherent Half- and Few-Cycle Sources for Nonlinear and Non-Equilibrium Studies.

Jefferson Lab - where are we? Brookhaven Lab Jefferson Lab

Jefferson Lab, Newport News, VA Home of 2 accelerators: each with superconducting linacs, photo-cathode guns FEL sc linacs photo-guns

JLab Free Electron Laser facility 135 pC per bunch = 1 µ J Pulse FWHM 200fs – 2 ps 75 MHz All sources are simultaneously produced for pump-probe studies 75 MHz – achievable using superconducting linac in energy recovery mode

RGA, extractor gauge RGA, extractor gauge and leak valve and leak valve Electrodes Electrodes Corona shield Corona shield Vacuum chamber Vacuum chamber Ceramic stand -offs Ceramic stand -offs Photocathode Photocathode Solenoid retractor retractor mechanism mechanism Superconducting linac cavity Photocathode Photocathode High voltage feed High voltage feed NEG pumps NEG pumps 33 inches 33 inches Gun

Jefferson Lab Facility Spectroscopic Range and Power Energy (meV) 1 10 100 1000 10000 1000 JLab FEL 100 JLab THz 10 1 -1 ) FEL proof of principle: 0.1 Flux (Watts/cm Table-top sub-ps Neil et al. Phys. 0.01 Rev.Letts 84 , 662 lasers 1E-3 (2000) 1E-4 s 1E-5 n o r t o r h c n y S 1E-6 1E-7 r a 1E-8 b o l G 1E-9 THz proof of principle: 1E-10 Carr, Martin, McKinney, Neil, Jordan & Williams 1E-11 Nature 420 , 153 (2002) 1E-12 1 10 100 1000 10000 -1 ) Wavenumbers (cm

Coherent Synchrotron Radiation Generation - theory Near-field term not normally Jackson, Classical Electrodynamics, Wiley, NY 1975 considered for synchrotron calculations Electric field for single particle:- r r r r r r & +∞ r − − × − β × β + γ − β n n cR n 1 2 [( ) ] ( ) τ = − ω + τ ∫ e e e E ec i R c d 1 r ( exp[ / )] r ω − β n R 2 (1 ) −∞ e REFERENCES R.A. Bosch, Nuclear Instr. & Methods A431 320 (1999). O. Chubar, P. Elleaume, "Accurate And Efficient Computation Of Synchrotron Radiation In The Near Field Region", proc. of the EPAC98 Conference, 22-26 June 1998, p.1177-1179.

Coherent Synchrotron Radiation Generation - theory 2 d I ⎡ ⎤ = − ω + ω × ⎡ ⎤ 2 N[1 f ( )] N f ( ) single particle in tens ity ⎢ ⎥ ⎢ ⎥ ω Ω d d ⎢ ⎥ ⎣ ⎦ ⎣ ⎦ f ( ω ) is the form factor – the Fourier transform of the normalized longitudinal particle distribution within the bunch, S(z) 2 ∞ Larry Carr r ω = ∫ ω ⋅ i n z c f e S z dz ⎛ ⎞ ⎛ ⎞ / ˆ ⎜ ⎟ ⎜ ⎟ −∞ dE ⎜ ⎟ ⎜ ⎟ − ⎝ ⎠ ⎝ ⎠ ≈ × 25 2 10 J/ cm -1 / electron ν d REFERENCES S.L. Hulbert and G.P. Williams, Handbook of Optics: Classical, Vision, and X-Ray Optics, 2nd ed., vol. III. Bass, Michael, Enoch, Jay M., Van Stryland, Eric W. and Wolfe William L. (eds.). New York: McGraw-Hill, 32.1-32.20 (2001). S. Nodvick and D.S. Saxon, Suppression of coherent radiation by electrons in a synchrotron. Physical Review 96 , 180-184 (1954). Carol J. Hirschmugl, Michael Sagurton and Gwyn P. Williams, Multiparticle Coherence Calculations for Synchrotron Radiation Emission, Physical Review A44 , 1316, (1991).

JLab THz Beam Schematic with Optical Beam Ray-tracing 3 1.0 2 1 0.5 M4 F3 Vertical Position 0 Vertical Position 0.0 -1 -2 -0.5 -2 m -3x10 60x60mm -30mm -20 -10 0 10 20 30 Horizontal Position 3 -1 m -1.0x10 -100mm -50 0 50 100 200x200mm 2 Horizontal Position F2 1 Vertical Position 1.0 0 -1 0.5 -2 Vertical Position 60x60mm 3x10 -2 m - 0.0 -30mm -20 -10 0 10 20 30 Horizontal Position M2 -0.5 -1.0x10 -1 m -100mm -50 0 50 100 200x200mm 200x200mm Horizontal Position 4 M1 2 Vertical Position 0 -2 -2 m - 4x10 -40mm -20 0 20 40 Horizontal Position

JLab THz Beam Pattern on Mirror 1 4 4 4 2 2 2 Vertical Position Vertical Position Vertical Position 0 0 0 -2 -2 -2 -4x10 -2 m -2 m -2 m -4x10 -4x10 -40mm -20 0 20 40 -40mm -20 0 20 40 -40mm -20 0 20 40 Horizontal Position Horizontal Position Horizontal Position 1 THz 10 THz 0.1 THz 33 cm -1 330 cm -1 3.3 cm -1 2.0x10 9 140x10 6 6 800x10 120 2 2 2 Phot/s/0.1%bw/mm Phot/s/0.1%bw/mm 1.5 Phot/s/0.1%bw/mm 600 100 80 1.0 400 60 40 0.5 200 20 -40mm -20 0 20 40 Horizontal Position -40mm -20 0 20 40 -40mm -20 0 20 40 Horizontal Position Horizontal Position

Jefferson Lab THz spectra and total power Frequency (THz) 0.1 1 10 100000 10000 1000 100 10 1 -1 0.1 540 W 840 W 54 W Watts/cm 0.01 1E-3 100 MHz 100 pC 1E-4 150 x 150 mr 0.1 ps 1E-5 0.3 ps 1E-6 1.0 ps 1E-7 1E-8 1E-9 1E-10 1 10 100 1000 -1 ) Frequency (cm

JLab Terahertz Beam Extraction and Transport M2 M3 diamond Shutter/viewer & window camera M1 V1 M1

Mirror 1 - courtesy of Richard Wylde, (Thomas Keating) Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U.S. Department of Energy

JLab power permits large area imaging ~ m 2 10mm 2 Ray trace Optical transport output in User Lab Real time image Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U.S. Department of Energy

Challenges of Stand-off THz Imaging • Providing sufficient THz power to illuminate a large field of view and to image in real time • Properly collecting the scattered THz radiation from the target region (transmission mode generally not useful) • Filtering of the THz induced thermal IR • Properly imaging onto a detector array • Creating imaging arrays designed specifically for THz imaging

Imaging / bio-medical cancer screening Basal cell carcinoma shows malignancy in red. Teraview Ltd. 1 mW source images 1 cm 2 in 1 minute 100 W source images whole body (50 x 200cm) in few seconds

Imaging / security screening at portals Clery, Science 297 763 (2002) Spectra of explosives courtesy of Teraview

Jefferson Lab & U. of Delaware Team

THz Imaging Schematic beamline visible mirror 2 camera mirror 1 THz filter/lens THz filter/lens THz camera mirror 3 2 Watts of broadband light onto 75mm x 75mm field. object ~10 4 camera elements, so 200 microWatts per pixel. moves/rotates Scattering ~ 0.1%, so 0.2 microWatts per pixel. Noise level, 1 nanoWatt, so S/N is ~200.

The Camera http://www.corebyindigo.com/PDF/TVMicron.pdf

THz Imaging Layout

THz Induced Thermal IR Beam ON Beam OFF Processed Data Raw Data paper target imaging target paper target imaging target • Images taken using the stock Ge lens • THz passes through paper target and is reflected off of the imaging target • Heating due to absorption of THz heats the paper and the imaging target, producing the thermal IR seen above

Test Pattern Imaging Target

Test of Imaging Resolution Processed Data Raw Data 26 mm 26 mm 35 mm 35 mm • Raw THz images are processed to reduce the background and improve contrast • Current configuration resolved down to the 1mm wide contact pads • Polyethylene lens filtered the thermal IR, but does not image well

THz Imaging Covered Target Processed Data Raw Data CD mailer covering cloth covering

4. THz effects Duke U. - tune to intramolecular bonds to eliminate collateral damage

Human Effects, contd. - Jill McQuade • Many applications for THz sources • High-power sources and detectors are being developed • Bioeffects need to be understood for the health and safety of personnel • Bioeffects efforts need to catch up to or even lead technology development • Bioeffects data pertaining to the health effects of high- powered THz exposure are non-existent

Brooks Air Force Base – Human Effects Division, Terahertz Team Dr. Jill McQuade HEDR Physiologist: Project Lead Dr. Bob Thomas HEDO Physicist: Modeling Mr. Jason Payne HEDR Biomedical Scientist: Modeling Ms. Nichole Jindra HEDO Biologist: Expt, pilot lead Dr. Semih Kumru HEDO Physicist: Expt Mr. Victor Villavicencio HEDO-NG Cont Physicist: Expt Dr. Ron Seaman HEDR–GD-AIES Cont Physiologist: Expt, protocol Mr. Alex Salazar HEDR–GD-AIES Cont Physiologist: Expt Dr. Walter Hubert HEDR Molecular Biologist: Biotechnology