Perhaps you should try some spelling variations:
"particle acceleration" » "particle accelerators"
"particle accelerator" » "particle accelerators"
"particle acceleraton" » "particles acceleration", "particle accelerations", "pareticle acceleration"
"particle accelerate" » "particles accelerated", "particle accelerators", "practice accelerate"

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 acceleration"))) OR ((("particle accelerate") OR ("particle acceleraton")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"particle accelerator\") OR (\"particle acceleration\"))) or (((\"particle accelerate\") or (\"particle acceleraton\"))))".
• Removing quotes may allow a broader search: (((( particle accelerator ) OR ( particle acceleration ))) or ((( particle accelerate ) or ( particle acceleraton )))).
• Adding a wildcard symbol may retrieve word variants: (((("particle accelerator") OR ("particle acceleration"))) or ((("particle accelerate") or ("particle acceleraton"))))*.