In any case. The plot of Angels and Demons revolves around a plot to destroy the Vatican with an antimatter bomb, stolen from the CERN laboratory near Geneva. Worn down no doubt by repeated inquiries from Brown readers, the real-life CERN scientists have put up a hilariously snarky debunking page. Highlights:
Do you make antimatter as described in the book?
No. The production and storage of antimatter at CERN is not at all as described in the book: you cannot stand next to the Large Hadron Collider (LHC) and see it come out, especially since the LHC accelerator is not yet in operation.
Does one gram of antimatter contain the energy of a 20 kilotonne nuclear bomb?
. . . you ‘only’ need half a gram of antimatter to be equally destructive as the Hiroshima bomb, since the other half gram of (normal) matter is easy enough to find.
At CERN we make quantities of the order of 10^7 antiprotons per second and there are 6x10^23 of them in a single gram of antihydrogen. You can easily calculate how long it would take to get one gram: we would need 6x10^23/10^7=6x10^16 seconds. There are only 365 (days) x 24 (h) x 60 (min) x 60 (sec) = around 3x10^7 seconds in a year, so it would take roughly 6x10^16 / 3x10^7 = 2x10^9 = two billion years! It is quite unlikely that anyone wants to wait that long.
Hat-tip to All Manner of Thing.