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 The
PHOBOS experiment is based on the premise that interesting collisions will be
rare, but that when they do occur, new physics will be readily identified.
Thus the PHOBOS detector is designed to examine and analyze a very
large number of unselected gold ion collisions. For each collision, the detector
gives a global picture of the consequences of the collision and detailed
information about a small subset of the nuclear fragments ejected from the high
energy-density region.
PHOBOS consists of many silicon detectors surrounding the interaction region.
With these detectors, physicists will be able to count the total number of
produced particles and study their angular distribution. With
this array they will be looking for unusual events, such
as fluctuations in the
number of particles or angular distribution. Physicists know from other
branches of science that a characteristic of phase transitions
is a fluctuation in observable events. In order to obtain more detailed information about these
events, the PHOBOS detector will also have two high-quality magnetic
spectrometers which will study one percent of the produced
particles in detail.
The PHOBOS detector is able to measure quantities such as the
temperature, size, and density of the fireball produced in the collision. It
also studies the ratios of the various particles produced. With this information it
should be possible to both detect and study a phase transition that might occur
between quark-gluon plasma and ordinary matter. The PHOBOS
group hopes
to discover the quark-gluon plasma and learn more about the early universe.
Seventy scientists from 12 institutions in three nations are working on
PHOBOS, which is located
at the 10 o'clock position on the RHIC ring. PHOBOS
experimental group home page
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