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.
Antimatter trapped and stored - Photo Cern
Geneva, Switzerland (GenevaLunch) – One of the universe’s open questions may be a step closer to being answered thanks to over 30 atoms of antihydrogen that have been trapped and stored by scientists at the European Organization for Nuclear Research, Cern.
This opens the path to new ways of making detailed measurements of antihydrogen, Cern notes in a written statement 18 November. It will allow scientists to compare matter and antimatter, the latter being what annihilates ordinary matter in a single explosive flash of energy.
The finding is related to the re-creation of the mini Big Bang at Cern in early November.
“At the Big Bang, matter and antimatter should have been produced in equal amounts. However, we know that our world is made up of matter: antimatter seems to have disappeared,” says Cern. Investigating a “tiny difference in the properties of matter and antimatter could point towards an explanation of what happened.”
Image of lead ion collision captured by ALICE experiment. ©2010 CERN
Geneva, Switzerland (GenevaLunch) – The Large Hadron Collider (LHC) has successfully made the transition to collisions using lead ions, instead of lighter protons, the European Organization for Nuclear Research, Cern, announced 8 November. The collision of the much heavier lead ion particles resulted in temperatures a million times hotter than those at the centre of the sun, and tiny quantities of matter called quark-gluon plasma which is believed to have existed micro-moments after the Big Bang 13.7 billion years ago.
The LHC collides beams of particles going in opposite directions in a 27km-long circular tunnel straddling the Geneva-France border. Until 4 November the beams of particles were of protons. It took only four days to make the transition to lead ion beams, Cern said.
Lead ions are lead atoms stripped of their electrons. The collision of lead ion beams will allow scientists to study the origins of the strong nuclear force which binds particles together.
Links to other sites: BBC, Cern, New Scientist
© Chappatte, distributed by Globe Cartoon. More cartoons on Chappatte’s web site. Geneva-based Patrick Chappatte works for the International Herald Tribune, for Geneva newspaper Le Temps, and for NZZ am Sonntag. All cartoons reproduced with permission.
Control room for the LHC at Cern, Geneva
Geneva, Switzerland (GenevaLunch) – The LHC (Large Hadron Collider) was put back into action Friday 20 November at 22:00, slightly ahead of schedule, announced Cern. The machine started up, but was quickly shut down after a problem a year ago. “The LHC is a far better understood machine than it was a year ago,” said Cern’s director for accelerators, Steve Myers. “We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.” The LHC, the world’s most expensive machine, smashes atoms into each other at very high energies in order to recreate the conditions at the very beginning of the universe.
Background story, 20 November 2009
