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THz Planning 2010

THz Planning 2010. Enrica Chiadroni LNF-INFN 20 aprile 2010. Characterization of TERASPARC. Pyro -electric or Golay cell detectors. Operating spectral range: 0.1 – 3 THz Active element: 2 mm x 3 mm Sensitivity: NEP@20 Hz ~ 10 -8 W/Hz 0.5 Fast time response: tens of us.

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THz Planning 2010

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  1. THz Planning 2010 EnricaChiadroni LNF-INFN 20 aprile 2010

  2. Characterization of TERASPARC Pyro-electric or Golay cell detectors • Operating spectral range:0.1 – 3 THz • Active element: 2 mm x 3 mm • Sensitivity: NEP@20 Hz ~ 10-8 W/Hz0.5 • Fast time response: tens of us • Operating spectral range:> 40 GHz • Active element: ø 6 mm (diamond window) • Sensitivity: NEP@20 Hz ~ 10-10W/Hz0.5 • Slow time response: few tens of ms

  3. Optical Components Detector y-Dy z Filters/ polarizer x, y 70 mm electrons z CTR (30x30 mm, 300 mm SiO2, 80 nm Al) y 90° off-axis parabolic mirrors: Ø 50.8 mm EFL 152.4 mm z-cut quartz window: Ø 60 mm, 4.8 mm thick Enrica Chiadroni (INFN-LNF)

  4. Optical Components Detector y-Dy z Filters/ polarizer x, y 70 mm electrons z CTR (30x30 mm, 300 mm SiO2, 80 nm Al) Pyrodetector black polyethylene window y Enrica Chiadroni (INFN-LNF)

  5. I Step: THz Radiation from HB Velocity Bunched EB Two working points have been investigated On crest operation Q = 500 pC Energy= 167 MeV energy spread = 0.1% ex= 3.5 mm mrad bx = 17.73 m ax = -1.17 ey = 4.1 mm mrad by = 25 m ay = -2.78 st = 2.0 ps Compression Factor 4 Q = 500 pC Energy= 94 MeV energy spread = 1% ex= 6.4 mm mrad bx = 28.4 m ax = -2.774 ey = 3.3 mm mrad by = 33.83 m ay = -2.539 st = 0.5 ps Enrica Chiadroni (INFN-LNF)

  6. On crest Beam F(w) Charge (a.u.) Frequency (Hz) Time(ps) RFD Flag On crest operation Position on the screen (mm) Enrica Chiadroni (INFN-LNF)

  7. Compressed Beam F(w) Charge (a.u.) Frequency (Hz) Time(ps) RFD VB Flag The steepest rising front of the experimental profile allows a greater extension of the spectrum to higher frequencies with respect to an ideal Gaussian profile. Position on the screen (mm)

  8. Measurements and Results-Pyro-detector- • Detector signal analysis • No compression and compression factor 4 • with filters: 0.3 THz, 1.5 THz • Statistical analysis to evaluate fluctuations • Dependence of CTR intensity on N2f(w) Enrica Chiadroni (INFN-LNF)

  9. Effect of Bunch Compression A gain of a factor 25 in intensity with respect to the on crest operation has been detected in the RF compression mode --- Compressed bunch (st = 0.5 ps) --- Non Compressed bunch (st = 2.0 ps) Time (s)

  10. Investigating the Spectral Emission -On Crest Operation- C1 with 0.3 THz filter Enrica Chiadroni (INFN-LNF)

  11. Investigating the Spectral Emission -C4- red curve:CTR energy at 350 GHz with a BW of nearly 50 GHz green curve:broad band CTR energy (up to 3 THz)

  12. Investigating the Spectral Emission -C4- red curve:CTR energy at 1.5 THz with a BW of nearly 0.3 THz blue curve:broad band CTR energy (up to 3 THz) Enrica Chiadroni (INFN-LNF)

  13. Investigating the Spectral Stability No filter Emean = 12.20 mJ sE = 0.73 mJ No filter Emean = 9.5 mJ sE = 1.0 mJ Filter 1.5 THz Emean = 1.60 mJ sE = 0.23 mJ Filter 0.3 THz Emean = 0.80 mJ sE = 0.1 mJ

  14. Shot-to-Shot e-beam fluctuations affect the THz pulse stability; • Typical fluctuations of THz around 10 % due mostly to charge (particle number) instability Charge fluctuations 5% fluctuations Enrica Chiadroni (INFN-LNF)

  15. Investigating the N2 Dependency Enrica Chiadroni (INFN-LNF)

  16. Measurements and Results-Golay cell detector- • Detector signal analysis • No compression and compression factor 8 • with filters: 1.5-2.5-3.4-4.3-4.8 THz On crest operation Q = 260 pC Energy= 140 MeV energy spread = 0.1% ex= 2.26 mm mrad bx = 18.8 m ax = -1.8680 ey = 1.95 mm mrad by = 17.9 m ay = -1.3085 st = 2.0 ps Compression Factor 8 Q = 260 pC Energy= 102 MeV energy spread = 1% ex= 4.00 mm mrad bx = 21.4 m ax = -1.8479 ey = 2.96 mm mrad by = 28.6 m ay = -0.7578 st = 0.25 ps Enrica Chiadroni (INFN-LNF)

  17. Measurements and Results-Golay cell detector- Enrica Chiadroni (INFN-LNF)

  18. Measurements and Results-Golay cell detector- Enrica Chiadroni (INFN-LNF)

  19. THz Planning 2010 • Week I-II • Characterization of THz source for different wavelengths with Golay cell detector • Week III • Optimization of THz source for different LINAC settings • Week IV • Setting interferometers (both Martin-Puplett and Michelson) up for frequency measurements and electron bunch characterization • Week V-VI • Upgrade of the experimental layout (i.e. diamond viewport, optical components for pump and probe experiments, N2 flushing, etc.) • Week VII-VIII-IX • Pump and probe experiments to measure the lifetime of an excited level in quantum wells Ge/Si-Ge

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