Nuclear Emulsions as Characterized in Overview of Photographic Emulsions

1. 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 3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

2. ｾﾞﾗﾁﾝ水溶液 AgNO3 + KX → AgX + KNO3 in an aqueous gelatin solution

10. Sens ∝ Abs×Eff Abs ∝ Vol ∝ d3 Competition→ ＞2 L. i. centers Ⅲ Ⅱ Ⅰ

11. Ⅲ Ⅱ Ⅰ ←Efficiency of latent image formation

12. 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 3rd 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) • Introduction • Large grains for color negative films • Small grains for OPERA • Very small grains for Dark Matter Detection 3rd Intern. Workshop on Nuclear Emulsion Techniques, Jan. 2008, Nagoya

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

25. Sulfur-sensitization centers decorated with silver atoms

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

27. Microwave photoconductivity measurement recombination e- trap trapping

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

29. Electron-trapping Hole-trapping By electron-trapping Ag2 By hole-trapping Ag2 T. Tani et al. (1999)

32. Characterization of detectors

33. 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 3rd 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)

37. Miyake, Tani & Nittono (2000)

38. B B A A

39. Indirect transition Direct transition

40. Mean free pass ～50 nm

41. Microwave photoconductivity measurement e- trap

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

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