(1) I doubt that CERN would be able to produce "pounds" of antimatter, despite what was shown fictionally in the movie "Angels and Demons". In fact, CERN has a web page on antimatter in relation to that movie, in which they claim that...

"Even if CERN used its accelerators only for making antimatter, it could produce no more than about 1 billionth of a gram per year. To make 1 g of antimatter - the amount made by Vetra in the movie - would therefore take about 1 billion years."

But of course, that's what CERN says...

(2) I don't know how effective CERN would be at creating dimensional portals. According to the scientific legends of the 20th Century, as related by Preston Nichols, the most effective device for doing so was the Montauk Project machine, which employed an 8-story-high "octahedral antenna", the conduits of which passed though the floors and ceilings of the multilevel underground facilities at the Montauk base at Camp Hero on Long Island. The portal would appear in a special room at the geometric center of the antenna. The destination of the portal would be determined by a psychic (usually Duncan Cameron) in a special mind-reading chair linked to a computer which modulated the waveform for the antenna. The Montauk Project was supposedly closed down in the 1980s due to the appearance of negative entities on the base. But it was alleged that an updated facility was subsequently built somewhere in Europe, for which the claims of portal openings at CERN might be misdirection to obscure the existence of the actual facility.

(3) A theme of a negative entity seeking to open a dimensional portal to access the "zero matter" or "darkforce" dimension occupied much of the series "Agent Carter" last season. The climactic episodes of the season are still available for free on some on-demand cable services.