[email protected] gwyn p. williams filling the thz...
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Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Filling the THz Gap
GWYN P. WILLIAMS
Jefferson Lab12000 Jefferson Avenue - MS 7A
Newport News, VA [email protected]
CASA Seminar, Novemer 14, 2003
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
1960 1970 1980 1990 2000107
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x1023
200 mA Diff. Limit
3rd. Gen.original design
2nd. Gen.
1st. Gen. Synch. Rad.
CDC 6600
Cray 1
Cray T90
GROWTH IN LEADING EDGECOMPUTING SPEED(Millions of operations/sec)
GROWTH IN SYNCHROTRON X-RAY SOURCE BRIGHTNESS(Photons/sec/0.1%bw/sq.mm/mrad2)
Calendar Year
10-1
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What’s new?
Short pulses/Multiparticle coherence
Near-field
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Thomas Jefferson National Accelerator Facility
The THz Gap
Many important dynamical processes occur in the THz region (5 meV). Superconducting band-gaps, protein conformational modes, phonons….
With high coherent power the key niche areas are non-linear dynamics and imaging.
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Thomas Jefferson National Accelerator Facility
THz – Brief History
After Nichols left Berlin, Rubens continued the work, and in 1900 he isolated wavelengths of 6THz (50 microns) and made careful measurements which he gave to Max Planck who derived the Radiation Law. Planck wrote in 1922 “Without the intervention of Rubens the formulation of the radiation law, and consequently the formulation of quantum theory would have taken place in a totally different manner, and perhaps even not at all in Germany”.
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The Paper That Started it all.
1981
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Thomas Jefferson National Accelerator Facility
1 micron
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Thomas Jefferson National Accelerator Facility
Backing up….Auston Switch for producing THz light
Auston, D.H., Cheung, K.P., Valdmanis, J.A. and Kleinman, D.A., Phys. Rev.Letters 53 1555-1558 (1984).
2 2
3
2Larmor's Formula: Power (cgs units)3e ac
=
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Thomas Jefferson National Accelerator Facility
Radiation from Accelerated Electron
electron
acceleration
But units of power are:
2 2 3
c
MLT L ML TT
Force Distan eTimePower
− −× =
×
=
=field
Electric field goes linearly in the electric charge and the acceleration- so intensity (power) goes like e2a2
2 22
e MLTL
−=
Now for an electric charge, force ise2/L2, so we can derive units for e thus:
So e2a2 has units of :ML3 T-2×L2T-4 = ML5T-6
And if we divide by c3, or L3T-3, we get ML2T-3.
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Thomas Jefferson National Accelerator Facility
Larmor’s Formula2 2
323e ac
Power=
Also we note that radiation is emitted in only 2 out of 3 directions, so we have a 2/3 factor, yielding:
Noting that the units of power are ML2T-3, and noting thatM goes like gamma, L goes like 1/gamma and T goes likegamma in the moving frame, in the rest frame the relativistic version is :
42 23
23e ac
Power γ=
Radiation from Accelerated Electron
N.B. Radiated energy and elapsed time transform in the same manner under Lorentz transforms
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
~100 V
fseclaserpulseGaAs
THz
64
6 6 8 2
2 6
172
100V VE 10 m10 mF 10 V 10 ( 3 10 )am .5MeV / c 0.5 10
m10 sec
−= =
×= = =×
≅
2 8 217
2c ( 3 10 ) ma 10 secρ 1
if ρ 1 m
×= = ≅
=
fseclaserpulse
e- -> 40 MeV
GaAsTHz
ρ
Comparing Coherent THz Synchrotron and Conventional THz Sources
2 24
3
2Larmor's Formula: Power (cgs units)3e a γc
=
4 780 80 10 !!!!andγ = =
a=accelerationc=vel. of lightγ=mass/rest mass
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Thomas Jefferson National Accelerator Facility
e-e-e-e-e-e-e-e-e-e-e-e-e-
e-e-
e-
Synchrotron Radiation Generation
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Thomas Jefferson National Accelerator Facility
E lec
t ric
fi eld
time freq. (1/time)
electron(s)
super-radiantenhancement
N
E/N
Inte
nsity
E2
Synchrotron Radiation Generation
W.D. Duncan and G.P. Williams,”Infra-red Synchrotron Radiation From Electron Storage Rings”, Applied Optics 22, 29l4 (1983).
THz
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Thomas Jefferson National Accelerator Facility
Statistics of an electron bunch in a storage ring
Synchrotron Radiation Generation - actual situation
Hirschmugl, Sagurton and Williams, Physical Review A44, 1316, (1991).
Time Scale 2
Time Scale 1
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Thomas Jefferson National Accelerator Facility
2/ˆi n z cf e S z dzωω
∞ ⋅−∞= ∫
2.n r( t )ˆi t c2 2 22
2d I eN[1 f ( )] N f ( ) n n e dtd d 4 c
ωωω ω βω Ω π
−∞
−∞= − + × × ×
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).
Coherent Synchrotron Radiation Generation - theory
f(ω) is the form factor – the Fourier transform of the normalized longitudinal particle distribution within the bunch, S(z)
REFERENCES
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Thomas Jefferson National Accelerator Facility
Synchrotron Radiation - so what’s new here?
radio-freq.cavity
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Thomas Jefferson National Accelerator Facility
Showstopper…….3 GeV at 100 mA is 300 Megawatts!!!!!
radio-freq.cavity
Solution……..Energy Recovery
Synchrotron Radiation - so what’s new here?
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Thomas Jefferson National Accelerator Facility
FTIR System
e-
FTIR System
We measured the bend-magnet synchrotron radiation right before the FEL, when the beam is maximally compressed.
THz Setup on JLab IR-DEMO FEL
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Thomas Jefferson National Accelerator Facility
Crystal quartz window
Collimating optic
Nicolet Nexus 670 FTIR bench
LHe cooled Si bolometer detector
THz Setup on JLab IR-DEMO FEL
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
October 2002
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
1 10 100 10000.0
0.2
0.4
0.6
Frequency (THz)
Measured Calculated (500fs bunch length)
Wat
ts/c
m-1
Frequency (cm-1)
0.1 1 10
THz Expt and Calculation
Diffraction losses ~ 20 Watts integrated
Carr, Martin, McKinney, Neil, Jordan & WilliamsNature 420, 153 (2002)
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
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In
tens
ity (A
rb. U
nits
)
Wavenumbers (cm-1)
50 µA 80 µA 105 µA 110 µA 170 µA 230 µA
Inte
grat
ed T
Hz
Inte
nsity
(Arb
. Uni
ts)
Beam Current (µA)
Measured Intensity N2 Fit
Coherent THz vs. Current
0 50 100 150 200 2500
20
40
60
80
100
Measured intensity Fit to (Current)2
Current (µA)
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Thomas Jefferson National Accelerator Facility
Polarization of Coherent THz
0 25 50 75 1000
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3500 I = 0.04 mA
Polarizer Vertical
Polarizer Horizontal
Mea
sure
d In
tens
ity (A
rb. U
nits
)
Wavenumbers (cm-1)
Expected polarization ratio for 60mrad port at 30 cm-1 is 6:1.
We observed 5:1. Good agreement.
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Thomas Jefferson National Accelerator Facility
Why do this? Terahertz Imaging
Clery, Science 297 763 (2002)
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Thomas Jefferson National Accelerator Facility
IR Spectroscopy & Dynamics is based on Vibrations
Simple molecule
More complicatedmolecule - protein
Slide courtesy Paul Dumas, LURE, Orsay, France
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Protein Structure / Folding Dynamics
Amide I Secondary Structure Assignments:
1620 - 1640 β-sheet1644 extended coil (D2O)1648 - 1657 α-helix1665 310 helix1670 - 1695 anti-parallel β-sheet,
β-turn
1720 1700 1680 1660 1640 1620 1600 1580
0.0
0.1
0.2
Abs
orba
nce
Frequency (cm-1)
α-helix
β-sheetβ-turn
extended coil
Carboxypeptidase
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Thomas Jefferson National Accelerator Facility
1750 1700 1650 1600
0.0
0.5
1.0
random coilbeta sheet10 sec30 sec90 sec180 sec
162516
54
Abs
orba
nce
Frequency
Protein Folding Dynamics - Silk Fiber Formation
SCAN PARAMETERS:
• %T: silk fibroin on BaF2 disk• 32 scans at 200 KHz (2.3 sec)• 4 cm-1 resolution• MCT detector
Lisa Miller, Mark Chance et al.
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Thomas Jefferson National Accelerator Facility
THz Spectroscopy
Anthrax proxy DNA
Globus et al. University of Virginia J. App. Phys. 91 6105 (2002)
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Thomas Jefferson National Accelerator Facility
THz Imaging
A tooth cavity shows up clearly in red. Teraview Ltd.
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Thomas Jefferson National Accelerator Facility
The Promise of THz – novel imaging
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Thomas Jefferson National Accelerator Facility
The Promise of THz – novel imaging
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
THz Imaging
Basal cell carcinoma shows malignancy in red. Teraview Ltd.
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Terahertz computerized tomography
Turkey Bone Test Object
3cm
Ferguson et. al. Phys. Med. Biol. 47 3735 (2002)
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Thomas Jefferson National Accelerator Facility
So – where are we going at JLabwith THz?
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
FEL upgrade, phase 1
Jefferson Lab’s new ERL/FEL/THz sourceTurned-on June 2003!!
THz light port
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Thomas Jefferson National Accelerator Facility
0o
10.2o = 173 milliradians
JFEL THz Port Description Final Rev. 1 Dated 8-13-2003
ρ =1.2 meter
s
M1 (110 x 155) mm
M1 to “dimad”“start of bend” = 667mm
120 mr
0o 3.58o
50 mr
146 mr35 25
85 mr
Beamline Center Line to be: 20 tangent, 35 mrads from zero degrees 7/24/03 GPWThis puts F1=667-(1200×0.035)=625Penetration location
1040 mm from dimad startof bend point.
60
“View from the back of M1 looking at beam”
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Thomas Jefferson National Accelerator Facility
625F1
5810
Floor1000
625
1077
2330
Dimensions in mmnot to scale
2480
Ceiling
M1(ellipsoid)
705
372M2 (plane) M3
ellipsoid
F2
M4(ellipsoid)
2240
2240
e-beam
1000
F3
M1 110 x 155M2 120 x 170 M3 183 x 258M4 183 x 258
Neil/GPW
JFEL THz Port Description Final Rev. 1 Dated 8-13-2003
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Thomas Jefferson National Accelerator Facility
SRW SRW Calculation of Calculation of light on light on screenscreen 3.0 m 3.0 m from from source source by by Paul DumasPaul Dumas
Flux after 1-st Aperture: 2.0479e+13 Photons/s/.1%bw
-0.2m
-0.1
0.0
0.1
0.2
Ver
tical
Pos
ition
-0.2m -0.1 0.0 0.1 0.2Horizontal Position
Spectral Flux / Surface at λ=100 µm 3 m from downstr. BM Edge
1.0x109
0.8
0.6
0.4
0.2
0.0-0.2m 0.0 0.2
Horizontal Position
200x106
150
100
50
0
Phot
/s/0.
1%bw
/mm
2
-0.2m -0.1 0.0 0.1 0.2
Vertical Position
Spectral Flux / Surface vertical cut
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Thomas Jefferson National Accelerator Facility
What is Edge Radiation?
Dipole Radiation
Edge Radiation
Edge Radiation is light emitted as the electrons enter the fringe field of a dipolemagnet. For long wavelengths the fringe field maybe treated as an impulseacceleration. Thus edge radiation has characteristics similar to transition radiation.In the far field approximation for a single edge the angular spectral flux is “white”up to a cutoff determined by the details of the fringe and is given by,
Reference: R.A. Bosch, Nuclear Instr. & Methods A431 320 (1999).
( )222
24
2 1eI
ddF
θγ+θγ
πωω∆α=
Ω- 4 - 2 0 2 4
gq
00.05
0.10.15
0.20.25
FddW
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Thomas Jefferson National Accelerator Facility
1 21
2[( ) ] ( ) exp[ / )]
(1 )(e e e
e
n n cR nE ec i R c dn Rω
β β γ β ω τβ
τ+∞ − −
−
−∞
× − × + −= +−∫
Full formula
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Thomas Jefferson National Accelerator Facility
What does edge Radiation look like?
Daresbury LabAnn Rep 1984/5
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Thomas Jefferson National Accelerator Facility
Two Edges Interfere
Screen
Interference of Two Edges in Far Field
Edge 1 Edge 2
L
( )
( )
θγ+λγπ
Ω≈
θγ+λγπ−
Ω≈
Ω
222
2
1
222
212
12
LSinddF4
1LExp1ddF
ddF
•Spectrum is no longer white
•Opening angle depends on λ
Near Field Calculation of Two Edges using SRW (Chubar& Elleaume, ESRF)
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Thomas Jefferson National Accelerator Facility
JLab’s new THz Beamline
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Thomas Jefferson National Accelerator Facility
1 10 100 10001E-10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0.01
0.1
1
10
100
1000
10000
100000
Integrated Intensity356.6 Watts
Frequency (THz)
Wat
ts/c
m-1
Frequency (cm-1)
Jlab Demo 5mA 100pc 500 fsecs fwhm 60hX60v Synchrotron radiation (NSLS, Brookhaven) 800 mA 90X90 2000K Black Body 10 mm2
JLab Upgrade 135 pc 75 MHz (10mA) 300fs 150x150
0.1 1 10
JLab’s new THz Beamline
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Thomas Jefferson National Accelerator Facility
1 10 100 10001E-10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0.01
0.1
1
10
100
1000
10000
100000
JLab FEL - THz Port
Frequency (THz)
W
atts
/cm
-1
Frequency (cm-1)
75 MHz 135 pc (10 mA) 150 x 150 mr Int. Power
100 fs FWHM 1.1kW 400 fs FWHM .26kW 800 fs FWHM .11kW
0.1 1 10
JLab’s new THz Beamline
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Thomas Jefferson National Accelerator Facility
1 10 100 1000 100001E-121E-111E-101E-91E-81E-71E-61E-51E-41E-30.010.1
110
1001000
10000
Energy (meV)
Flux
(Wat
ts/c
m-1)
Wavenumbers (cm-1)
1 10 100 1000
JLab THz
Synchrotrons
Globar
JLab FEL
Table-top sub-ps lasers
FEL proof of principle:Neil et al. Phys. Rev.Letts 84, 662 (2000)
THz proof of principle:Carr, Martin, McKinney, Neil, Jordan & WilliamsNature 420, 153 (2002)
Brightness of IR Sources
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Thomas Jefferson National Accelerator Facility
Funded byUnited States DOE, DOD
DE-AC05-84-ER40150 TJNAF
George Neil, Fred Dylla and the Jefferson Lab FEL TeamLarry Carr (Brookhaven National Laboratory)Lisa Miller (Brookhaven National Laboratory)Carol Hirschmugl (UW Milwaukee)Paul Dumas (University of Paris, France)Oleg Chubar (Soleil project, Saclay, France)Mike Martin (Berkeley Lab)Wayne McKinney (Berkeley Lab)
Thanks to…………………….