The OPERA film: New nuclear emulsion for large-scale, high-precision experiments

Abstract Industrial mass production of nuclear emulsion film has been realized by the introduction of new photographic technologies. In addition, emulsion-refreshing capability (erasing unwanted tracks before its use) was implemented by controlling the fading characteristics of the gel. The gel properties were optimized in order to satisfy this requirement; rapid track erasing at the erasing condition and minimum fading during the running of experiments. Emulsion films with this capability are crucial for large-scale applications like the long base-line neutrino experiment, OPERA, which intend to detect Tau neutrino appearance at 732 km from the beam source.