Perhaps you should try some spelling variations:
particles acceleration » particle acceleration, particle accelerators, parallel acceleration
particle accelerator » particle accelerators, particle acceleration
particle penetration » particle generation, particle concentration, particle separation

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 penetration ) OR ( particles acceleration )))).
• Adding a wildcard symbol may retrieve word variants: (( particle accelerator ) or ((( particle penetration ) or ( particles acceleration ))))*.