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First Particle Collisions at Record-Shattering Energies in the LHC-Accelerator in Geneva

ALICE continues its research program



With new record-shattering energy for proton collisions, the LHC particle accelerator at the European laboratory for particle physics resumed its research program today in Geneva, Switzerland. At 13:31 local time, the heavy ion experiment ALICE (A Large Ion Collider Experiment) recorded the first collisions. The GSI Helmholz Centre für Schwerionenforschung is a significant contributor to the construction as well as the scientific program of ALICE.

The energy per particle impact achieved today was 7 tera-electron volts – over 3500 times more than the impact partner’s rest mass. Upon conclusion of the current experiment cycle, the energy will be increased to the targeted maximum energy.

ALICE is one of the four large international experiments at the LHC. It is the only LHC experiment that researches collisions of heavy nuclei at extremely high energy. The experiment cycle that was started today mainly explores proton collisions and will continue for around 18 months. Protons are the nuclei of hydrogen and thus the lightest projectiles used in the LHC. The collision of lead nuclei is also schedule with an experiment cycle of four weeks each in the fall of 2010 and 2011. Lead nuclei are around 200 times heavier than protons.

„ALICE is specifically designed for the collision of heavy nuclei. By colliding lead nuclei, we try to recreate the extremely hot and dense plasma state of quarks and gluons – the building blocks of matter – which existed for only fractions of seconds after the Big Bang”, explains professor Peter Braun-Munzinger, director of the ExtreMe Matter Institute EMMI at the GSI Helmholtz Centre. “These experiments will allow us to gain a new and unique insight into yet unexplored fields of particle physics.”

ALICE is composed of a multitude of components. The detector is 25 meters long, 16 meters wide and 16 meters high. The large magnet that is used to create the magnetic field to analyze the paths of the particles weighs 80,000 tons alone. Right from the start, GSI has played a significant role in the construction as well as the scientific program of ALICE, collaborating with the universities of Darmstadt, Frankfurt, Heidelberg and Münster and the universities of applied science in Köln and Worms. Today, more than 1,000 scientists from 30 countries contribute to ALICE. Among them are around 100 scientists from Germany, 30 of which are doctoral candidates. German researchers are involved in three central ALICE projects: the giant time projection chamber, which encloses the collision zone over a length of 5 meters with up to 2.5 meters radial distance; the adjacent transition radiation detector; and the High Level Trigger, a high-performance computer, which evaluates the information content of the events in the space of a few milliseconds.