1. 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

2. AgNO 3 + KX → AgX + KNO 3 in an aqueous gelatin solution ｾﾞﾗﾁﾝ水溶液

10. Competition→ ＞ 2 L. i. centers Sens ∝ Abs×Eff Abs ∝ Vol ∝ d 3 ⅠⅡⅢ

11. ⅠⅡⅢ ←Efficiency of latent imageformation

12. 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

18. 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

22. Babcock & James (1976) Cubic AgBr (0.15μm, S + Au)

25. Sulfur- sensitization centers decorated with silver atoms

26. (Ag2; Reduction sensitization center) →1 →2 1

27. Microwave photoconductivity measurement e - trap trapping recombination

28. (Carriers; positive holes) (Carriers; electrons)

29. By hole-trapping Ag 2 By electron-trapping Ag 2 T. Tani et al. (1999) Hole- trapping Electron-trapping

32. Characterization of detectors StructureReset function (Refreshment) Color negative films Three dimension No CCD & CMOS for DSC Two dimensionYes OPERA emulsions Three dimension Yes

33. 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

36. 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)

38. A B A B

39. Indirect transition Direct transition

40. Mean free pass ～ 50 nm

41. Microwave photoconductivity measurement e - trap

42. Microwave photoconductivity measurement e - trap trapping recombination R Recomb = [e - ]×[h + ] should increase with decreasing grain size E = I×t on 0.2μm AgBr

43. Sulfur-sensitization centers decorated with silver atoms

45. ？

46. 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

61. ⅠⅡⅢ ←Efficiency of latent imageformation

62. ⅠⅡⅢ