Best of 2008 Scientific Discovery

On September 10, 2008, the world stands silent in front of the greatest ever particle physics experiment. The Large Hadron Collider (LHC), built to assist scientists to answer chief unresolved questions in particle physics and alter our understanding of the Universe, is aimed to become the world’s most powerful particle accelerator with the unparalleled energy it can achieve.

Over the past decades, physicists have been able to illustrate in elaborate detail the fundamental constituent parts that make up the Universe and the relations between them. This understanding is summarized in the Standard Model of particle physics, yet the gaps it contains leaves space for experimental data, which can be achieved with the LHC. After nearly 15 years of planning and theory approach, physicists can use the particle accelerator to study the least known constituent parts of our Universe. Regardless of what will be the result of the experiment, a new knowledge in particle physics is about to emerge describing thoroughly the fundamental laws of Nature but also moving beyond the paradigm.

The Large Hadron Collider (LHC) is a complex scientific instrument inaugurated by the European Organization for Nuclear Research (CERN) on the French/Swiss border about 100 m underground. Consisting of a 27 km ring of superconducting magnets with numerous accelerating instruments to increase the energy of the particles in the process, LHC is the newest addition to CERN’s accelerator complex.

Inside the LHC, two beams of subatomic particles (hadrons) travel at 11.245 times a second, almost at the speed of light, in opposite directions, gaining energy with every lap before colliding with one another. Physicists use the LHC to rebuild the conditions right after the Big Bang through actual collisions of the two beams at four locations around the accelerator ring. The beams collide at extremely high energy of 7 TeV (tera-electronvolt), which correspond to head-to-head collisions of 14 TeV, while 600 million collisions take place every second in gigantic devices that measure particles with micron precision. Built on highly sophisticated electronic trigger systems, LHC detectors measure incredibly quickly and responsively the elapsed time of a particle in an accuracy of billionths of a second.

The beams are guided around the particles accelerator ring by a strong magnetic field, attained using a total of 9.300 superconducting electromagnets of diverse varieties and sizes. Built from electric cable that resourcefully carries out electricity without loss of energy, electromagnets are required to be chilled in a -271C, which is colder that outer space.

To avoid colliding with gas molecules inside the LHC, the beams of particles travel in an ultra-high vacuum with an internal pressure of ten times less than the pressure on the Moon making the accelerator the emptiest space in the Solar System.

The six experiments at the LHC are all run by scientists from institutes around the world, but each experiment is unique and characterised by its individual particle detector.

ATLAS and CMS, the two large experiments, are performed on general-purpose detectors and aim to analyze the largest range of physics possible by focusing on the particles produced by the collisions in the accelerator. The experiments have two independently designed accelerators in order to cross-confirm the results of each experiment.

ALICE and LHCb, the two medium-size experiments, are performed on specialized detectors and aim to analyze the LHC collisions in relation to specific phenomena.

TOTEM and LHCf, the two small-size experiments, focus on protons and particles that brush each other through out the collisions.

The LHC can attain an energy that no other particle accelerators have achieved before, but Nature consistently generates higher energies in cosmic-ray collisions. To that end, concerns about the safety of the outcome of such high-energy particle collisions have been addressed to the LHC Safety Assessment Group (LSAG). In the context of new experimental data and theoretical understanding, the LSAG reports that Nature’s collisions are far stronger than LHC’s collisions and therefore there is no reason for concern about the safety of the experiment.

On September 10, 2008, the world stands silent in front of the greatest ever particle physics experiment. The LHC, the immense particle accelerator standing across the French/Swiss border, fails to recreate the conditions after the Bing Bang due to a helium leak that causes the LHC to shut down for a while. Physicists are not yet provided with a new knowledge about the fundamentals of our Universe. Yet, LHC is being repaired and the particles are expected to begin spinning again around 2009. The creation of an artificial black hole that will tell us more about our existence is on its way. Fasten your seat belts and enjoy!