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SYKO: Komplexität

SYKO 1: Complexity

SYKO 1.2: Plenarvortrag

Montag, 9. März 2009, 13:35–14:10, A140

The LHC-Project: Complexity in High Energy Physics — •Thomas Lohse — Humboldt University, Dept. of Physics, Newtonstr. 15, 12489 Berlin

What is the nature of mass? What happened just after the big bang? Why is the Universe not made of anti-matter? What is the structure of space-time?

These are some of the problems, which will be attacked at the Large Hadron Collider at CERN, the largest particle accelerator ever built. Four particles detectors (ATLAS, CMS, LHCb, ALICE), constructed and operated by collaborations of thousands of physicists and engineers are ready for data taking and waiting for first colliding beams.

Complexity is an unavoidable phenomenon occurring in many aspects of such a large-scale project, some of which will be exemplified in the talk. The protons (or ions) accelerated in the LHC are complex objects by themselves and exhibit complex behavior in their interactions. The particle beams in an accelerator are subject to highly non-linear dynamics which can lead to structure formation, chaos and instability. When protons collide, the proton constituents (quarks and gluons) undergo hard scattering processes which involve an infinite hierarchy of self-similar quantum-fluctuations. These can be theoretically quantified by Feynman diagrams which become factorially more numerous from level to level and rapidly more difficult to evaluate. The particle detectors are divided into a number of different sub-detectors, each with a special task. The large particle density produced in the collisions requires all detectors to have high granularity, in total feeding millions of electronic channels which have to be processed and read out at the bunch crossing rate of 40 MHz. A worldwide network of computing centers serves for data processing and dissemination and is used as a platform for the coordinated data analysis of thousands of physicists.