TERAFERMIA THz Beamline at the Fermi-FEL
A. Perucchi
TERAFERMI - Timeline
One-day meeting on New THz Sources in TriesteFinal decision on TeraFermi project
October 2012
Official start of the FIRB project: 36 months durationMarch 2012
FIRB project approval: 1.007.786 €September 2011
Submission of the FIRB - Futuro in Ricerca project:TERAFERMI - A Terahertz Beamline at the Fermi FEL
December 2010
2nd letter of intent: TERAFERMI - The Terahertz Beamline at the Fermi FELSAC executive summary report“The SAC considers the scientific case strong enough […][…] The Terahertz beamline will require human and financial resources from FERMI thatare unlikely to be available”
June 2008
1st letter of intent: A letter of intent for Coherent Terahertz Spectroscopy at FERMIJune 2007
Program funded by Italian Ministry of Education and Research inorder to support emerging scientific excellence.The TERAFERMI project is among the 105 selected projects out of3792 proposals in the various fields of science and humanities: success rate of 2.7 %2nd largest financing awarded to one single research unit
Non-linear THz optics at MV/cm
THz light couples to both electronic and lattice excitations
Tudosa, 2004
From L. CarrDienst, 2011
Ec critical field
Rini, 2007
Ultra-fast structuralUltra-fast structuraldistortions and latticedistortions and lattice
controlcontrol
From L. Carr
Populating low-energyPopulating low-energyexcited statesexcited states
Electronic response underElectronic response undergiant quasi-static fieldsgiant quasi-static fields
Ultra-fast magneticUltra-fast magneticswitching (B~switching (B~0.3 T)0.3 T)
The TeraFermi concept
Exploiting the properties of the FERMI-FEL electron beam to produce:•Short (sub-ps)
•Powerful (MV/cm)•Broadband (0.1-10 THz)
THz pulses to be used as a Pump beam for ultrafast nonlinear spectroscopies
Leveraging over the already existing FERMI LINACReduced construction and operation costs
Working in parasitic modeTeraFermi will not affect overall FEL available beamtime
THz light always available
Accelerator-Based Coherent THz emission
!
N 1+ Nf (")[ ]
!
f (") = #(t)exp($i"t)dt$%
+%
&
N ~ 6.24*107 @ 1pC Storage-RingsN ~ 6.24*1010 @ 1nC Single-pass accelerators
Coherent Synchrotron Radiation (CSR)
Coherent Transition Radiation (CTR)
Extending the FEL’s advantages into the THz region
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
µJ/
GH
z
12 3 4 5 6
102 3 4 5 6
1002 3 4 5 6
1000
Wavenumber (cm-1
)
4 5 610
11
2 3 4 5 610
12
2 3 4 5 610
13
2 3
Frequency (Hz)
CSR (! = 1.91 m)
CTR (r = 6 cm)
Far-field approximationE=1.2 GeVN=6.25 E+16 (Q=1nC)"t = 700 fs2"# = 100 mrad
Expected Performance
• Energy ≥ 100 µJ / pulse• Peak Power ~ MW• Electric Fields ≥ 1MV/cm• Magnetic Fields ~ 0.3 T
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
104
Energ
y p
er
puls
e (µJ)
0.001 0.01 0.1 1
Energy (eV)
0.1 1 10 100
Frequency (THz)
IR FEL's / Undulators
CSR Storage-Rings
J-Lab
FERMI
TERAFERMI scheme
FEL 1
FEL 2
CTR Source
Beam Dump
SeedingLaser
sample
Table-TopTHz source
Mid-IRfs source
Pump Beam
THz
Probe
UV / soft X-rays
Near-IR
FERMI experimental hallFERMI LINAC
Resources - 3 years
1008 k€786 k€222 k€
Charged to MIURCharged to INSTM
Total228 k€General Costs
30 k€220 k€150 k€400 k€
Source ChamberBeamline
Experimental StationSub-total
Equipment
110 k€
Accelerator GroupMechanics/Vacuum/Technical Drawings
Controls/SoftwareLaser Group
Sub-total
Human ResourcesAlready hired staff~26 months/person
150 k€120 k€270 k€
A.P. (Principal Investigator)ScientistSub-total
Human Resources
TeraFermi - Layout
TERAFERMIEnd-station
Optical scheme
500 4300 9300 9600 5000f1=520 f2=5000 f3=5000 f4=5000
600
P f2
f3
P P
f4
f1
P T
T4000
3001300
8000 5000
1300 1300
7000
f5=600
LINAC tunnel Safety Hutch Experimental Hall
Low-VacuumUHV
Beam Transport Efficiency
f1=520 f2=5000 f3=5000 f4=5000 f5=600
ABCD optics (Gaussian beams)
THz Transport (CTR source)
1.0
0.8
0.6
0.4
0.2
0.0
Tra
nsm
itta
nce
30x103
2520151050
Length (mm)
f1
f2f3
f4 f5
200 GHz500 GHz2 THz
λ = 1 mm
Performance under FEL operation
250
200
150
100
50
010008006004002000
bunch-length (fs)
3000
2500
2000
1500
1000
µJo
ule
q=500 pC
Standard FERMI-FEL
parameter range
LiNbO3 data from Yeh et al. APL (2007) - 10 µJ/pulseDAST data from Hauri et al., APL (2011) - 20 µJ/pulse
0.001
0.01
0.1
1
10
100
1000
µJ/
puls
e/1
0%
bw
0.12 3 4 5 6 7 8 9
12 3 4 5 6 7 8 9
102
THz
LiNbO3
DAST
500 pC, 1 ps500 pC, 400 fs
500 pC, 100fs1 nC, 100 fs
FERMI-FELelectron bunch structure can be
shorter than expected !!!from 1 ps to the 200-800 fs range
WEAKNESSES• Performances at the foreseen location of the source are still to be
evaluated, based on realistic electron beam properties andmodeling of the distribution of electrons after lasing
STRENGTHS• Low construction costs / easy operation• Present FEL operating condition allow emission up to 5 THz• Energy per pulse can range from 100 µJ to several mJ per pulse
OPPORTUNITIES• Optimizing e- beam for THz emission• Quasi-monochromatic tunable emission
(modulating cathode/seeding laser)• Self synchronized THz pulse/UV probe
THREATS• FERMI operating conditions can drastically affect THz beamline
performances both in terms of maximum frequency and pulseenergy. Is parasitic mode the best choice ?
Conclusion
A unique playground for THz accelerator-basedemission in a seeded FEL-facility
A very competitive facility under FEL working conditions
Optimized beam forTHz operation
THz pump / UV probe
Acknowlegments
Stefano Lupi (coproposer) - University of Rome “La Sapienza”
ELETTRA staffE. Allaria, S. Di Mitri, G. Penco, M. Veronese, …
A. Cavalleri, D. Nicoletti (C-FEL)B. Schmidt (DESY)D. Fausti (University of Trieste)
And many others…
Proposed Flow-ChartProject Approval from ELETTRA management
SAC/MAC
Beamline DesignFeasibility Study
Construction
Commissioning
FEL User FacilityTHz pump / THz probe
Expanding toTHz pump / FEL probeR&D Facility
Seeking additional fundings
New SAC/MAC advice
2013
2014
2015