CERN's Heavy Ion Program Creates "Little Bang"
Scientists at the European Organization for Nuclear Research (CERN) in Geneva,
Switzerland, recently created a new state of matter called "quark-gluon
plasma," which they believe will lead to further insight into the early
evolution of the universe. According to theory, this state of matter--in
which quarks, the tiniest components from which much of matter is made,
and gluons, the particles associated to the interquark forces, are
unbound and free to roam--existed for about 10 microseconds after the Big
Bang. As the universe expanded and cooled, the plasma condensed into the
composite nuclear particles that we recognize today (e.g., protons
In 1994, researchers at CERN set out to verify this theory, hoping to
re-create the conditions that existed immediately after the Big Bang in an
attempt to "unglue" the quarks and then observe their transition into
complex particles as the system cooled. The experiments involved
bombarding targets with a tightly focused beam of high-energy lead ions.
The ions were first accelerated from rest to intermediate energy in the
CERN Proton Synchrotron (PS) particle accelerator complex, and then
further accelerated in the Super Proton Synchrotron (SPS) to their final energy
before ejection towards the targets inside seven different experimental
detectors. The collisions created temperatures over one hundred thousand
times as hot
as the center of the sun and energy densities twenty times that of
ordinary nuclear matter.
According to Mats Lindroos, the ABS project leader at CERN, Mathematica
was heavily used in the experiments, both for the analytical
part of accelerator control and online as part of the Automated Beam
Steering and Shaping (ABS) software. The ABS designation includes all forms of
algorithms, software packages, and systems that are used as intelligent
tools by operators in the accelerator control rooms for correction of
trajectories, orbits, working points, and other specifications.
In the first stage of the acceleration, the beam trajectories are
controlled online with the ABS system. The ABS system uses precomputed
correction matrices determined with BeamOptics, an application of
Mathematica that contains all the classical functions of the theory of
charged particle optics. "The Mathematica package BeamOptics,
developed here at CERN, has been the workhorse of the ABS project since
the start of the ABS activities in the PS division," says Lindroos.
The ABS system also calls an optimizer that minimizes the errors of
trajectories using an algorithm called MICADO, which is also coded in
Mathematica. Given a correction matrix and function, MICADO
computes values for the correctors that will minimize the error in the function,
with the output graphically displaying how useful each of the correctors
is in minimizing the error. The graphics user-interface communicates with
the algorithm via MathLink.
For more detailed information on the "Little Bang" and CERN's Heavy Ion
program, visit the CERN web site at