Enrica Chiadroni LNF-INFN 20 aprile 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/Hz0.5 Fast time response: tens of us Operating spectral range: > 40 GHz Active element: ø 6 mm (diamond window) Sensitivity: NEP@20 Hz ~ 10-10 W/Hz0.5 Slow time response: few tens of ms

Enrica Chiadroni (INFN-LNF) 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)

Enrica Chiadroni (INFN-LNF) 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)

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)

Enrica Chiadroni (INFN-LNF) 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)

Position on the screen (mm) 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)

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)

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)

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

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

Investigating the Spectral Emission Enrica Chiadroni (INFN-LNF) 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)

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

Enrica Chiadroni (INFN-LNF) 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)

Investigating the N2 Dependency Enrica Chiadroni (INFN-LNF) Charge (pC) Bunch Length (ps) 125 1.81+/-0.019 225 1.96+/-0.018 335 2.22+/-0.021 490 2.49+/-0.034 Enrica Chiadroni (INFN-LNF)

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)

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

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

THz Planning 2010 Week I-II Week III Week IV Week V-VI 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