Nostradamus made an ominous prediction:
"Leave, leave Geneva every last one of you, Saturn will be converted from gold to iron, RAYPOZ will exterminate all who oppose him, Before the coming the sky will show signs."
You've got to be careful with translations from Old French. The popular English version is not totally correct. Spellings vary in old texts, words change meanings and some become obscure.
The third line in question is one of a mistake in syntax. The translator was guessing here at the meaning. 'Le contre' clearly means 'the opposite'. 'Raypoz' is not a term used anywhere else in French and has no definite meaning. The opposite Raypos will exteriminate all, is the actual statement. 'Ray' is not French, though evidently it's Nostradamus' abbreviation of 'rayon', meaning 'ray.' 'Poz' is curiously written with a Z, a rare letter like in English, which indicates at least the pronunciation. 'Pos' for 'positive' is current in English as an abbreviation, and 'positif' is 'positive', though neither pos or poz would have been used in the Renaisance. Though the Z makes it clear that it isn't the French 'pos' which if so spelt would be pronounced like 'poe'. So 'poz' definately suggests 'positif'. Note that Nostradamus is consistent, using abbreviations to make up Raypos, as we do today. To call Raypoz the PositiveRay is a sound derivation, though it wouldn't have been understood back then, with the only rays being 'rayons de soleil' or sun rays, sunlight.
What is the Opposite of Raypos? A negative ray. In the case of the LHC, since they're using proton rays, the exact counterpart is antiproton rays, antimatter. So a matter/antimatter explosion destroying Geneva?