Nuclear Emulsions as Characterized in Overview of Photographic Emulsions

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Nuclear Emulsions as Characterized in Overview of Photographic Emulsions. Tadaaki Tani (Frontier Res. Labs, FUJIFILM) Introduction Large grains for color negative films Small grains for OPERA Very small grains for Dark Matter Detection - PowerPoint PPT Presentation

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  • Nuclear Emulsions as Characterized in Overview of Photographic EmulsionsTadaaki Tani (Frontier Res. Labs, FUJIFILM)

    IntroductionLarge grains for color negative filmsSmall grains for OPERAVery small grains for Dark Matter Detection

    3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

  • AgNO3 + KX AgX + KNO3 in an aqueous gelatin solution

  • Competition2 L. i. centersSens AbsEffAbs Vol d3

  • Efficiency of latent image formation

  • Nuclear Emulsions as Characterized in Overview of Photographic EmulsionsTadaaki Tani (Frontier Res. Labs, FUJIFILM)

    IntroductionLarge grains for color negative filmsSmall grains for OPERAVery small grains for Dark Matter Detection

    3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

  • Nuclear Emulsions as Characterized in Overview of Photographic EmulsionsTadaaki Tani (Frontier Res. Labs, FUJIFILM)

    IntroductionLarge grains for color negative filmsSmall grains for OPERAVery small grains for Dark Matter Detection

    3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

  • Babcock & James (1976)Cubic AgBr (0.15m, S + Au)

  • Sulfur-sensitization centers decorated with silver atoms

  • (Ag2; Reduction sensitization center)121

  • Microwave photoconductivity measuremente- traptrappingrecombination

  • (Carriers; positive holes) (Carriers; electrons)

  • By hole-trapping Ag2By electron-trapping Ag2T. Tani et al. (1999)Hole-trappingElectron-trapping

  • Characterization of detectors

  • Nuclear Emulsions as Characterized in Overview of Photographic EmulsionsTadaaki Tani (Frontier Res. Labs, FUJIFILM)

    IntroductionLarge grains for color negative filmsSmall grains for OPERAVery small grains for Dark Matter Detection

    3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

  • X-ray diffraction pattern ofCubic AgBr grainsA150 nmC 96 nmE 62 nmH 50 nmScherrers equationDhkl = K/cos

    Miyake, Tani & Nittono (2000)

  • Miyake, Tani & Nittono (2000)

  • ABAB

  • Indirect transitionDirect transition

  • Mean free pass 50 nm

  • Microwave photoconductivity measuremente- trap

  • Microwave photoconductivity measuremente- traptrappingrecombinationrecombinationRRecomb = [e-][h+] should increase with decreasing grain size E = ItE = Iton 0.2m AgBron 0.2m AgBr

  • Sulfur-sensitization centers decorated with silver atoms

  • Challenging and interesting subjects on very small grains (VSG) of silver halideFormation & stabilization of VSGPrecise size measurement of VSGQuantum size effect of light absorptionBallistic carrier transport in VSGEnhanced recombination in VSGVery small number of sensitization centers and impurity ions in each VSGVery small fraction of fogged grains in VSGSize dependence of sensitivity of VSG

  • Efficiency of latent image formation

  • Efficiency of latent image formation

  • This transparency shows the scanning electron micrograph of the section of the photosensitive layer in the above-stated color negative film. White lines and spots are silver halide grains.

    As seen in this transparency, a color negative film is a three-dimensional sensor with many functional layers in pile. There are three major layers, which are sensitive to three primary colors, i.e., blue, green, and red. In each major layer, there are two or three sub-layers with high, medium, and low sensitivities. A color film is thus designed to capture an image with full color and large dynamic range by taking advantage of its three-dimensional structure. Another way to depress the recombination is to introduce dislocations along the edges of a thin tabular silver halide grain, as shown in this electron micrograph and illustration. Electrons are localized by dislocations along the edges, and separated from positive holes trapped by sensitizing dyes on the main surfaces of the grain.A sulfur sensitization center is a typical electron-trapping sites suitable for latent image formation. According to our recent investigation, a sulfur sensitization center is composed of a dimer of two substitutional sulfur ions associated with two interstitial silver ions for the compensation of excess negative charges on sulfur ions. Each interstitial silver ion has a hydrogen-like orbital, to which an electron is loosely bound. An electron is captured at the bonding orbital formed owing to the interaction between the two hydrogen-like orbitals associated with the interstitial silver ions in the sensitization center. This compares the cross sections of the photosensitive layers in a color negative film and a newly developed nuclear emulsion film.This shows the scanning electron micrograph of the section of a color negative film having a photosensitive layer with about 20 m thick on a TAC film base with about 100 m thick. In addition to photosensitive layers, TAC film bases have been also refined for many years. As you know, silver halide photography was born in 1889 when Daguerre invented the daguerreotype with thin silver iodide layer as a photosensitive material.