Nuclear Emulsions as Characterized in Overview of Photographic Emulsions

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

ｾﾞﾗﾁﾝ水溶液

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