Perhaps you should try some spelling variations:
"particle accelerations" » "particles acceleration", "particle concentrations", "particelle acceleratori"
"particle penetration" » "particle generation", "particle concentration", "particle separation"
"particle accelerate" » "particles accelerated", "particle acceleraton", "practice accelerate"
"particle accelerators" » "particle accelerated", "particle accelerating"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("particle accelerator") OR ((((((("particle accelerators") OR ("particle acceleration"))) OR ("particle accelerate"))) OR ((("particle accelerations") OR ("particle penetration")))))).
• Removing quotes may allow a broader search: (( particle accelerator ) or ((((((( particle accelerators ) or ( particle acceleration ))) or ( particle accelerate ))) or ((( particle accelerations ) or ( particle penetration )))))).
• Adding a wildcard symbol may retrieve word variants: (("particle accelerator") or ((((((("particle accelerators") or ("particle acceleration"))) or ("particle accelerate"))) or ((("particle accelerations") or ("particle penetration"))))))*.