Dr David Evans: "From conception to design and building this, it's taken about 20 years."
The Large Hadron Collider has successfully created a "mini-Big Bang" by smashing together lead ions instead of protons.
The scientists working at the enormous machine achieved the unique conditions on 7 November.
The experiment created temperatures a million times hotter than at the centre of the Sun.
The LHC is housed in a 27km-long circular tunnel under the French-Swiss border near Geneva.
Up until now, the world's highest-energy particle accelerator - which is run by the European Organization for Nuclear Research (Cern) - has been colliding protons, in a bid to uncover mysteries of the Universe's formation.
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