Perhaps you should try some spelling variations:
"pparticle accelerator" » "particle accelerator", "particle accelerators", "particle acceleraton"
"particle acceleration" » "particle accelerators"
"article accelerators" » "particle accelerators", "particle accelerator", "particle accelerations"

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