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Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1.Introduction 2.Large grains for color negative films 3.Small grains for OPERA 4.Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
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AgNO 3 + KX → AgX + KNO 3 in an aqueous gelatin solution ゼラチン水溶液
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Competition→ > 2 L. i. centers Sens ∝ Abs×Eff Abs ∝ Vol ∝ d 3 ⅠⅡⅢ
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ⅠⅡⅢ ←Efficiency of latent imageformation
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Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1.Introduction 2.Large grains for color negative films 3.Small grains for OPERA 4.Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
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Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1.Introduction 2.Large grains for color negative films 3.Small grains for OPERA 4.Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
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Babcock & James (1976) Cubic AgBr (0.15μm, S + Au)
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Sulfur- sensitization centers decorated with silver atoms
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(Ag2; Reduction sensitization center) →1 →2 1
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Microwave photoconductivity measurement e - trap trapping recombination
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(Carriers; positive holes) (Carriers; electrons)
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By hole-trapping Ag 2 By electron-trapping Ag 2 T. Tani et al. (1999) Hole- trapping Electron-trapping
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Characterization of detectors StructureReset function (Refreshment) Color negative films Three dimension No CCD & CMOS for DSC Two dimensionYes OPERA emulsions Three dimension Yes
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Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1.Introduction 2.Large grains for color negative films 3.Small grains for OPERA 4.Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
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X-ray diffraction pattern of Cubic AgBr grains A ・・・ 150 nm C ・・・ 96 nm E ・・・ 62 nm H ・・・ 50 nm Scherrer’s equation Dhkl = Kλ/βcosθ Miyake, Tani & Nittono (2000)
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A B A B
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Indirect transition Direct transition
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Mean free pass ~ 50 nm
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Microwave photoconductivity measurement e - trap
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Microwave photoconductivity measurement e - trap trapping recombination R Recomb = [e - ]×[h + ] should increase with decreasing grain size E = I×t on 0.2μm AgBr
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Sulfur-sensitization centers decorated with silver atoms
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?
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Challenging and interesting subjects on very small grains (VSG) of silver halide Formation & stabilization of VSG Precise size measurement of VSG Quantum size effect of light absorption Ballistic carrier transport in VSG Enhanced recombination in VSG Very small number of sensitization centers and impurity ions in each VSG Very small fraction of fogged grains in VSG Size dependence of sensitivity of VSG
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ⅠⅡⅢ ←Efficiency of latent imageformation
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ⅠⅡⅢ
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