Tài liệu Developments of si and cdte semiconductor imaging detectors for a compton camera

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Developments of Si and CdTe Semiconductor Imaging Detectors for a Compton Camera Shin Watanabe(ISAS/JAXA) Shin'ichiro Takeda, Shinnosuke Ishikawa, Hirokazu Odaka, Masayoshi Ushio, Takaaki Tanaka, Kazuhiro Nakazawa, Tadayuki Takahashi (ISAS/JAXA), Hiroyasu Tajima (SLAC), Yasushi Fukazawa (Hiroshima Univ.) Sep. 14, 2006, the Sixth International “Hiroshima” Symposium @Carmel Concept of the Si/CdTe Compton Camera Hard X-ray and Gamma-ray (50 keV -- MeV) observation for high energy astrophysics Si -> Scatterer, CdTe->Absorber Si (Z=14) Low Photo Abs. High Compton Scattering CdTe (Z=48, 52 ρ~5.8 g/cm3) High Photo Abs. DSSD(double-sided Silicon strip detector) 20-30 layers 4-5 cm several 10 keV — MeV Gamma-rays CdTe Pixel Detectors High Energy Resolution Symmetrically Placed Low Energy Threshold Good Position Resolution Precise Gamma-ray photon Tracking NeXT mission (JAXA, 201?) Prototype 6 layer DSSDs + 3 CdTe Pixel Detectors DSSD CdTe DSSD: (with Hamamatsu Photonics) 2.6 cm × 2.6 cm, 300µm thickness 64 strips (each side) 400µm pitch CdTe Pixel: (with ACRORAD) Single Crystal CdTe (THM) In/CdTe/Pt (Diode type) 2 mm x 2 mm pixel, 8x8=64 pixels 0.5 mm thickness, Bias 400V Prototype results Compton Images S. Watanabe et al. IEEE Trans. Nucl. Sci., vol. 52, pp.2045-2051, 2005 Prototype results Compton Images 80 keV S. Watanabe et al. IEEE Trans. Nucl. Sci., vol. 52, pp.2045-2051, 2005 Prototype results Compton Images 80 keV 122 keV S. Watanabe et al. IEEE Trans. Nucl. Sci., vol. 52, pp.2045-2051, 2005 Prototype results Compton Images 80 keV 122 keV 270-400 keV S. Watanabe et al. IEEE Trans. Nucl. Sci., vol. 52, pp.2045-2051, 2005 Prototype results Compton Images 80 keV 122 keV 270-400 keV 511 keV S. Watanabe et al. IEEE Trans. Nucl. Sci., vol. 52, pp.2045-2051, 2005 Prototype results Compton Images S. Watanabe et al. IEEE Trans. Nucl. Sci., vol. 52, pp.2045-2051, 2005 80 keV Experimental Result & Estimation Experiment 122 keV Doppler Eff. Position Res. Energy Res. Total 270-400 keV 511 keV Doppler Effect is Dominant What we established From the prototype experiments, we have found that a Si/CdTe Compton Camera  can achieve the theoretical limit (Doppler broadening) • ~a few degree (@ > 500 keV), ~ 10 degrees (@100 keV) • ~ 0.7--1.0 mm, 3.5 mm at 2 cm DSSD(double-sided Silicon strip detector) 20-30 layers 4-5 cm Our Goal 1%(FWHM) Energy resolution Doppler limit angular resolution 10 % efficiency Further performance study by using Monte Carlo see Odaka et al. Poster in this symposium CdTe Pixel Detectors Symmetrically Placed a lot of issues to be done DSSD stack See Takeda et al. Poster in this symposium Stacking More Compactly size: 2.6 cm x 2.6 cm thickness: 0.3 mm stack pitch: 5.4 mm reduce material around DSSD improve Compton efficiency larger size 241Am 4cm x 4cm Nside Channel 4 layers 2 mm pitch 1st layer FWHM 1.5 keV 2nd layer @ 60 keV 3rd layer 4th layer 104 190 180 180 160 170 140 160 3 10 120 150 Gamma-rays 100 140 80 130 60 120 110 20 100 0 102 40 10 20 30 40 50 60 70 80 90 Pside Channel Shadow Image (log scale) 0 10 FWHM 1.5 keV @ 60 keV thicker larger 0.5 mm thick 5 cm x 5 cm 1 0 10 20 30 40 50 60 Energy[keV] stacking more layers High Energy Resolution CdTe Detector ISAS/JAXA and ACRORAD(JAPAN) CdTe (Z=48, 52 ρ~5.8 g/cm3) good for gamma-ray but, low-mobility and short life time of carriers (especially holes)  diode type ( In -> anode, Pt -> cathode) ● Extremely low leakage 10 pA for 2x2x0.5mm2 at 20℃ at 500 V 2 mm x 2 mm x 0.5 mm ● High bias voltage 137Cs 662keV FWHM 2.1 keV ~Fano limit thin CdTe diode device -> high energy resolution and fully active device CdTe Pixel Module CdTe area: 11.2 x 11.2 mm2 thickness: 0.5 mm pixel size: 1.4 x 1.4 mm2 8x8 = 64 pixels ASIC In/Au Stud Bump Al2O3 fanout board wire-bonding In ASIC Pt(pixel) ASIC: VA64TA (ISAS, SLAC and IDEAS) low noise: 50-60 e- RMS low power consumption: 0.2mW/ch 7 mm Performance of the CdTe Pixel Module Sum Spectrum 5ºC, 600V 57Co All spectra from 64 pixels 122 keV FWHM 1.5 keV 2000 1800 1600 1400 1200 1000 14.4 keV FWHM 1.1 keV 800 600 400 200 0 0 20 40 60 80 100 Energy [keV] 120 140 Uniformity is good. ~50 CdTe pixel modules have been constructed. almost same performance Absorber for the next Compton camera 2x2 CdTe pixel modules are stacked in 4 layers 1024 ch stack pitch : 2 mm Absorber for the next Compton camera 2x2 CdTe pixel modules are stacked in 4 layers 1024 ch 133Ba gamma-rays 104 ALL 1st layer 2nd layer 3rd layer 4th layer 103 102 10 1 0 50 100 150 200 250 Energy[keV] 300 350 400 stack pitch : 2 mm Energy Resolution(FWHM) 2.0 keV@122 keV 3.0 keV@356 keV ΔE/E ~ 1 % Plan of the next Compton camera DSSD CdTe Pixel 4 layers DSSD stack + 4 layers CdTe pixel stack + 8 CdTe pixels placed on the side of DSSDs Applications of the CdTe Pixel module Once we establish the module, we can expand it to… stacked detector 5 ~ 10 mm high efficiency and high energy resolution gamma-ray detector Applications of the CdTe Pixel module Once we establish the module, we can expand it to… stacked detector 5 ~ 10 mm Large Area Imager high efficiency and high energy resolution gamma-ray detector 4 ~ 8 cm Large Area CdTe Imager 4x4=16 CdTe pixel modules 5.4 cm x 5.4 cm large area imager Shadow Image 30--150 keV 5.4cm φ3mm M5 Nut 700 35 30 600 25 500 20 400 15 300 10 200 5 100 0 0 5 10 15 20 25 30 35 0
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