Perhaps you should try some spelling variations:
"particle accelerations" » "particle acceleration", "particle accelerators", "particle concentrations"
"particle concentration" » "particle acceleration"
"particles acceleration" » "particle acceleration", "particle accelerators", "parallel acceleration"
"particle accelerator" » "particle accelerators", "particle acceleration"

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 accelerations") OR ("particle concentration"))) OR ("particles acceleration")))).
• Removing quotes may allow a broader search: (( particle accelerator ) or ((((( particle accelerations ) or ( particle concentration ))) or ( particles acceleration )))).
• Adding a wildcard symbol may retrieve word variants: (("particle accelerator") or ((((("particle accelerations") or ("particle concentration"))) or ("particles acceleration"))))*.