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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 Emulsions
Tadaaki Tani (Frontier Res. Labs, FUJIFILM)
1. Introduction2. Large grains for color negative films3. Small grains for OPERA4. Very small grains for Dark Matter Dete
ction
3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
AgNO3 + KX → AgX + KNO3 in an aqueous gelatin solution
ゼラチン水溶液
Competition→
> 2 L. i. centers
Sens Abs×Eff∝
Abs Vol d∝ ∝ 3
ⅠⅡⅢ
ⅠⅡⅢ
←E
fficiency of laten
t image
formation
Nuclear Emulsions as Characterized in Overview of Photographic Emulsions
Tadaaki Tani (Frontier Res. Labs, FUJIFILM)
1. Introduction2. Large grains for color negative films3. Small grains for OPERA4. Very small grains for Dark Matter Dete
ction
3rd 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. Introduction2. Large grains for color negative films3. Small grains for OPERA4. Very small grains for Dark Matter Dete
ction
3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
Babcock & James (1976)
Cubic AgBr (0.15μm, S + Au)
Sulfur-sensitization centers decorated with silver atoms
(Ag2; Reduction sensitization center)
→1
→2
1
Microwave photoconductivity measurement
e- trap
trapping
recombination
(Carriers; positive holes)
(Carriers; electrons)
By hole-trapping Ag2
By electron-trapping Ag2
T. Tani et al. (1999)
Hole-trapping
Electron-trapping
Characterization of detectors
Structure Reset function
(Refreshment)
Color negative films
Three dimension
No
CCD & CMOS for DSC
Two dimension Yes
OPERA emulsions
Three dimension
Yes
Nuclear Emulsions as Characterized in Overview of Photographic Emulsions
Tadaaki Tani (Frontier Res. Labs, FUJIFILM)
1. Introduction2. Large grains for color negative films3. Small grains for OPERA4. Very small grains for Dark Matter Dete
ction
3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya
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)
Miyake, Tani & Nittono (2000)
A
B
A
B
Indirect transition
Direct transition
Mean free pass ~ 50 nm
Microwave photoconductivity measurement
e- trap
Microwave photoconductivity measurement
e- traptrapping
recombination recombination
RRecomb = [e-]×[h+] should increase with decreasing grain size
E = I×t E = I×t
on 0.2μm AgBr on 0.2μm AgBr
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
ⅠⅡⅢ
←E
fficiency of laten
t image
formation
ⅠⅡⅢ
←E
fficiency of laten
t image
formation