  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.
