The development of super fine-grained nuclear emulsion

A nuclear emulsion with micronized crystals is required for the tracking detection of submicron ionizing particles, which are a target of dark matter detection and other methods. We found that a new production method, named as the PVA-Gelatin Mixing Method (PGMM), could effectively control crystal size from 20 nm to 50 nm. We named two types of an emulsion produced with the new method NIT and UNIT. The composition and spatial resolution of them were measured, and the results indicated that these emulsions detect extremely short tracks.