Research and development of a super high sensitive nuclear emulsion gel

对核乳液凝胶进行了研究开发，该凝胶历史悠久，长期没有进行新的研发试验。在富士胶片公司的帮助下，我们将目前用于感光乳剂生产的AgBr的可控双射流生产和微晶体的核壳结构的最新技术应用于核乳剂凝胶的生产。研制的核乳化凝胶每100微米的最小电离粒子轨迹可记录65粒。获得的灵敏度比长期使用至今的富士ET7B高约1.8倍，比DONUT实验中使用的凝胶高约1.4倍。同时，我们试图制造出一种直径为0.05微米的精细分辨率凝胶。虽然它对最小电离粒子几乎没有敏感性，但我们可以利用电子显微镜研究核乳液位置分辨的可能性。发育的晶粒通常比微晶的原始尺寸大，这是由于晶粒迅速生长出丝状结构（直径约为25 nm）。需要进一步的研发来抑制长丝的生长，并保持与原始尺寸相同的位置分辨率。

A research and development was performed on the nuclear emulsion gel, which has a long history and no new R&D trial was performed for a long period. With the help of Fuji film co., we applied' the newest technologies, i.e. controlled double jet production of AgBr and core-shell structure of the micro crystal, which were currently used in the photographic emulsion production, to the production of the nuclear emulsion gel.The developed nuclear emulsion gel can record 65 grains per 100 microns long trajectory of a minimum ionizing particle. The achieved sensitivity is about 1.8 times higher than Fuji ET7B used for a long time until today and about 1.4 times higher than the gel used in DONUT experiment.Also, we tried to create a fine resolution gel of 0.05 micron diameter. Though it has almost no sensitivity to a minimum ionizing particle, we can investigate the possibility of position resolution of nuclear emulsion by using electron-microscopes. The developed grains are normally larger than the original size of the micro crystal, because of a rapid growth of a filament like structure (diameter about 25 nm) from the grains. Further R&D is needed to suppress the filament growth and keep the position resolution as fine as the original size.