Toward High-Resolution Detection of Target Fragmentation: TEA-Sensitized NIT for Proton Therapy Applications

Nano Imaging Trackers (NIT) are fine-grained nuclear emulsions capable of tracking charged particles with sub-micrometric spatial resolution. The DAMON (Direct Measurement of Target Fragmentation) experiment recently employed NIT to detect target-fragmentation events relevant to proton therapy in direct kinematics. These measurements showed that the small crystal size, while providing high spatial resolution, limits the reconstruction efficiency for primary proton tracks and high-energy secondary protons. This work reports an enhancement of NIT sensitivity achieved through alternative chemical sensitization methods, namely gold-plus-sulfur (Au-S) and triethanolamine (TEA), together with the use of the GR-1 developer. The detector response was evaluated with gamma-ray, carbon-ion and proton exposures, including clinically relevant proton energies.