Why does my Particle Traced image often look much brighter than the same view Ray Traced?
Particle Tracing uses real world lighting values, and it calculates also the light reflected from walls and other objects just as happens in real life. After Particle Tracing, you can adjust the image with the Brightness Multiplier/Adapt to Brightness setting (followed by Display current solution), or interactively with the Brightness slider that is part of the Visualization Stream enhancements.