The moment of impact of two lead ions, quarks in red, blue green, hadrons in white © CERN 2010
Geneva, Switzerland (GenevaLunch) – The high-energy collisions at Cern’s Large Hadron Collider (LHC) are creating conditions that allow scientists to observe the resulting jets, or streams of quarks and gluons, careening away from the point of collision. The collisions recreate the conditions just instants after the Big Bang, particle physicists’ term for the creation of the Universe. One of the things they are seeing is small quantities of a primordial soup known as quark gluon plasma (QMP) in which conditions are too hot for quarks and gluons to combine into protons and neutrons.
“With nuclear collisions, the LHC has become a fantastic ‘Big Bang’ machine,” said Alice spokesperson Jürgen Schukraft. “In some respects, the quark-gluon matter looks familiar,” he notes, adding that “we’re also starting to see glimpses of something new.”
In the lighter proton collisions, particles appear in pairs. The jets that appear in the heavy lead ion collisions are affected by the QMP and lose their energies rapidly, a process known as quenching: “This leads to a very characteristic signal, known as jet quenching, in which the energy of the jets can be severely degraded, signalling interactions with the medium more intense than ever seen before. Jet quenching is a powerful tool for studying the behaviour of the plasma in detail,” according to Cern.
Geneva, Switzerland (GenevaLunch) - “Ready for collision” said the screen at Cern (European Nuclear Research Organization) shortly after 08:30. The first attempt at 7 TeV collisions of two 3.5 TeV beams, about three to four times the collisions currently done at the Fermilab in the US, is expected to occur around 10:30 this morning.
A beam was lost around 06:00 this morning, but was recovered fairly quickly. The beams are now circulating in their pipes but a collision in advance of the planned schedule is avoided by keeping them magnetically separated. The mood in the control centre is upbeat and excited although given the complexity of the task, it could be hours before a collision occurs.
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- Background, GenevaLunch
- Cern LHC pages
Updated 24 November 08:00 Geneva, Switzerland (GenevaLunch) – The LHC (Large Hadron Collider) began to run over the weekend after a year-long delay, but Monday was the real day of excitement at its home at Cern (European Organization for Nuclear Research). The LHC is designed to study the world’s smallest known particles, the building blocks of the universe. Two beams have been circulating in opposite directions since the 20 November startup, alternating, but today they began to circulate at the same time, crossing at two points.
