Development of Large Crystal Size Nuclear Emulsion for Cosmic-ray Radiography

Abstract

Nuclear emulsion is a kind of photographic film and has sensitivity for ionizing radiation. The film record tracks of charged particle with angular accuracy under several mrad. We are developing nuclear emulsion with crystal size larger than conventional 200nm one. Large crystal size nuclear emulsion has a potential of high sensitivity and contrast, so it is hopeful as future cosmic-ray radiography detector. We succeeded in producing emulsion gels which have silver bromide crystal with diameter 200, 350, 450 and 800 nm using emulsion gel manufacturing equipment in Nagoya University. After applying optimum sensitization and development processing to each crystal size, sensitivity (G.D) and noise (F.D) ware as follows. [200 nm : G.D = 33.6 ± 2.6 FD = 1.1 ± 0.2], [350 nm : G.D = 42.0 ± 2.9 FD = 0.9 ± 0.2], [450 nm : G.D = 46.6 ± 3.1 FD = 0.5 ± 0.1], [800 nm : G.D = (34.1 ± 3.8) FD = 0.7 ± 0.2]