Nuclear Emulsions as Characterized in Overview of Photographic

Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1. 2. 3. 4. Introduction Large grains for color negative films Small grains for OPERA Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

ｾﾞﾗﾁﾝ水溶液 Ag. NO 3 + KX → Ag. X + KNO 3 in an aqueous gelatin solution

Sens ∝ Abs×Eff Abs ∝ Vol ∝ d 3 Competition→ ＞ 2 L. i. centers Ⅲ Ⅱ Ⅰ

Ⅰ Ⅱ Ⅲ ←Efficiency of latent image formation

Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1. 2. 3. 4. Introduction Large grains for color negative films Small grains for OPERA Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1. 2. 3. 4. Introduction Large grains for color negative films Small grains for OPERA Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

Cubic Ag. Br (0. 15μm, S + Au) Babcock & James (1976)

Sulfursensitization centers decorated with silver atoms

1 → 1 (Ag 2; Reduction sensitization center) → 2

Microwave photoconductivity measurement recombination e- trapping

(Carriers; positive holes) (Carriers; electrons)

Electron-trapping Holetrapping By electron-trapping Ag 2 By hole-trapping Ag 2 T. Tani et al.

Characterization of detectors Structure Color negative films Three dimension Reset function (Refreshment) No CCD & CMOS Two dimension Yes for DSC OPERA emulsions Three dimension Yes

Nuclear Emulsions as Characterized in Overview of Photographic Emulsions Tadaaki Tani (Frontier Res. Labs, FUJIFILM) 1. 2. 3. 4. Introduction Large grains for color negative films Small grains for OPERA Very small grains for Dark Matter Detection 3 rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

X-ray diffraction pattern of Cubic Ag. Br grains A・・・ 150 nm C・・・ 96 nm E・・・ 62 nm H・・・ 50 nm Scherrer’s equation Dhkl = Kλ/βcosθ Miyake, Tani & Nittono (2000)

Miyake, Tani & Nittono (2000)

B B A A

Indirect transition Direct transition

Mean free pass ～ 50 nm

Microwave photoconductivity measurement e- trap

on 0. 2μm Ag. Br recombination Microwave photoconductivity measurement trapping E = I×t e- trap E = I×t RRecomb = [e-]×[h+] should increase with decreasing grain size

Sulfur-sensitization centers decorated with silver atoms

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

Ⅰ Ⅱ Ⅲ ←Efficiency of latent image formation

Ⅰ Ⅱ Ⅲ ←Efficiency of latent image formation