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SISSI. Linear and Pump-Probe applications of THz Spectroscopy: The case of Elettra, Bessy-II, and SPARC S . Lupi Dipartimento di Fisica, INFN-University of Rome La Sapienza, and SISSI@ELETTRA, Italy. Synchrotron Infrared Source for Spectroscopy and Imaging. Outline.
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SISSI Linear and Pump-Probe applications of THz Spectroscopy: The case of Elettra, Bessy-II, and SPARC S. Lupi Dipartimento di Fisica, INFN-University of Rome La Sapienza, and SISSI@ELETTRA, Italy Synchrotron Infrared Source for Spectroscopy and Imaging
Outline • THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; • THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; • Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; • High-Power/Sub-ps THz Pulses @SPARC;
Outline • THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; • THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; • Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; • High-Power/Sub-ps THz Pulses @SPARC;
reference orbit:L = 240 m DL bunch, Dp momentum compaction factor: Dp/pa = DL/L Emission in the FIR/THz range is drastically enhanced. THz Coherent radiation production from III Generation Machines: Bessy-II and Elettra ELETTRA SISSI Beamline Bessy-II IRIS Beamline Take Home Message III Generation Machines High Rep Rate: 500 MHz Low-Energy per pulse: pJ Several ps bunch length Needed to compress the bunch Special Operation Mode Linear THz Spectroscopy CSR Gl U. Schade et al, PRL 2003 A. Perucchi et al,IP&T 2007
Outline • THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; • THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; • Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; • High-Power/Sub-ps THz Pulses @SPARC;
Superconductivity today: THz spectroscopy plays a fundamental role
... because Superconductivity is ruled by low-energy electrodynamics: • Superconducting gap : THz range • Spectral weight of condensate and penetration depth: THz • Mediators of pairing (phonons, etc.): THz • Range of sum rules: THz, Mid, or Near Infrared • Free-carrier conductivity above Tc: Infrared
Basic optics of Superconductors Superconducting gap observed if: -sample in the dirty-limit (2D < G) -Cooper pairs in s-wave symmetry Minimum excitation energy: Cooper-pair breaking 2D Drude absorption G Drude reflectance 2D ∫ [, T>Tc) - , T<Tc)] dps/8 = nse2/m*--> l=c/ps Ferrel-Glover-Tinkham Rule
Superconductivity in Boron doped Diamond Takenouchi-Kawarada-Takano Diamond 0.7 carats Oppenheimer Diamond 254.7 carats
B-Diamond: a text book example of BCS superconductivity ≤ (T) : Rn () = 1 - [8(T)/ p2]1/2 ≤ 2(T) : Rs() = 1 Peak at 2 in Rs/Rn s-wave Dirty-Limit Regime; 2D(0)=12±1 cm-1 2D(0)/kBTC=3.2 ± 0.5 M. Ortolani et al, PRL, 2006
Mott-Hubbard Insulator to Metal Transitions • Filling-Controlled MIT: • static (doping) U Coulomb repulsion t Bandwidth • Bandwidth-Controlled MIT: • static (pressure)
Mott-Hubbard Insulator to Metal Transition Pressure (Bandwidth) controlled MIT VO2 V2O3 E. Arcangeletti et al, PRL (2007)
Outline • THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; • THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; • Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; • High-Power/Sub-ps THz Pulses @SPARC;
Breaking Cooper Pairs Dynamically • Photoionization • For hω>2Δ light breaks Cooper pairs • Optical Pump - Optical Probe (THz Probe) hω>>2Δ • Recombination Dynamics affected by excess phonons 2) THz Pump – THz Probe hωTHz≥2Δ Intrinsic dynamics • Alternative processes if hω<2Δ • Δ=Δ(J, B) at fixed T<Tc • The high E (~MV) THz field may induce currents exceeding the critical current • (breaking the Superconducting State with an Electric Field) • The high B (~1 T) THz field may be larger that Bc • (breaking the Superconducting State with a magnetic Field)
THz controlled Mott-Hubbard MIT • Filling-Controlled MIT: • static (Doping) • Dynamic (Phoexcitation) U Coulomb repulsion t Bandwidth • Bandwidth-Controlled MIT: • static (Pressure) • dynamic (Radiation) Dynamical modulation of U through intramolecular pumping THz pulses in the MV/cm range can drive lattice displacements in the pm range
Outline • THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; • THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; • Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; • High-Power/Sub-ps THz Pulses @SPARC;
Free Electron Laser SPARC@INFN Acceleration section Beam energy 155–200 MeV Bunch charge 1 nC Rep. rate 10 Hz Peak current 100 A en 2 mm-mrad en(slice) 1 mm-mrad sg 0.2% Bunch length (FWHM) 10 ps-100 fs THz Section Ondulator Section Laser
CTR-THz Radiation Transition Radiation occurs when an electron crosses the boundary between two different media Intensity is 0 on axis and peaked at Q~1/g Polarization is radial
Velocity Bunching: Bunch length versus injection phase If the beam injected in a long accelerating structure at the crossing field phase and it is slightly slower than the phase velocity of the RF wave , it will slip back to phases where the field is accelerating, but at the same time it will be chirped and compressed. Velocity Bunching 0.876 ps/mm st = 160 fs Time 1.389 ps/mm st = 2.586 ps
CTR-THz emission 300 fs, 500 pC 500 fs, 250 pC 2 ps E. Chiadroni et al., J.Phys. 2012 E. Chiadroni et al. APL 2012 S Lupi et al ., J. Phys 2012 M. Ferrario et al., NIM A 2011
CTR measured emission from LINACs (1) Y. Shen et al., Phys. Rev. Lett. 99, 043901 (2007) (2) E. Chiadroni, et al., APL 2012 (3) M.C. Hoffmann et al., Optics Letters 36, 4473 (2011) (4) D. Daranciang et al., Appl. Phys. Lett. 99, 141117 (2011)
Perspectives • Increase machine energyincrease of bunch-charge (1 nC); • Tailoring the electronic bunch shapeextended spectral coverage (20 THz); • Narrow band THz radiationSmith-Purcell Radiation:
Acknowledgments • A. Perucchi (SISSI@ELETTRA) • E. Karanzoulis (ELETTRA) • U. Schade (IRIS@BESSY-II) • E.Chiadroni and M. Ferrario (LFN-INFN): TERASPARC project • Thank for your attention