Community Research and Development Information Service - CORDIS



Project ID: 231033
Funded under: FP7-PEOPLE
Country: Israel

Accurate measurements of high-energy particle collisions

Immediately after the Big Bang, conditions in the Universe could be likened to a hot, dense 'primordial soup'. Scientists have developed techniques to ensure that similar conditions created in particle accelerators provide an accurate looking glass into the beginnings of time.
Accurate measurements of high-energy particle collisions
The primordial soup consisted of particles moving at near light speed. It had lots of quarks, elementary matter particles and lots of gluons — elementary force particles mediating the strong force that 'glues' quarks together into protons, neutrons and other entities. Powerful particle accelerators have made it possible to recreate conditions similar to those just after the birth of the Universe.

The Large Hadron Collider (LHC) is the largest and most powerful particle accelerator in the world. The 7 000 tonne ATLAS detector, one of two general purpose detectors at the LHC facility, collects collision debris in the form of new particles that fly out in all directions.

The Relativistic Heavy Ion (RHI) programme at the LHC has achieved the highest energy heavy ion collisions in the world, surpassing those at the Relativistic Heavy Ion Collider (RHIC) in the United States. Experiments supported by the programme promise to offer exciting insights into the origins of the Universe.

Scientists initiated the EU-funded project GLOBALHIATLAS to fine-tune metrics associated with such experiments in order to ensure robust and reliable conclusions. In particular, they investigated the dependence of various global characteristics of RHI collisions (including elliptic flow) on centrality, defined by the number of nucleons (protons or neutrons) participating in a collision.

Using their methodology, scientists were able to estimate the number of participating nucleons, the number of collisions between them and other parameters. In addition, researchers compared results obtained at LHC with those from RHIC experiments and with predictions derived from models based on RHIC data. Finally, investigators studied charged hadron production, where hadrons are composite particles made of quarks and provide a window on the birth and evolution of the early Universe.

GLOBALHIATLAS laid the foundations for reliable and accurate measurements regarding high-energy RHI collisions at LHC to ensure that inferences regarding the origins and evolution of the Universe are on target. In addition, enhanced understanding regarding the performance of the ATLAS detector in the dense environment of such collisions will play an important role in future experiments.

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