particle accelerator

NOUN /pɑrtɪkəl_æk'sɛlə,reɪtər/
20 LETTERS · STARTS WITH P

particle accelerator is a valid 20-letter word worth 27 points in Scrabble and 33 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
P3A1R1T1I1C3L1E1A1C3C3E1L1E1R1A1T1O1R1
3 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 0 + 1 + 3 + 3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 =27 PTS
DOUBLE WORD → 54TRIPLE WORD → 81
MEANING

What does particle accelerator mean?