The PHENIX detector records many different particles emerging
from RHIC collisions, including photons, electrons, muons, and
quark-containing particles called hadrons.
Photons (particles of light) and leptons (electrons and muons)
are not affected by the strong force, which binds quarks and
gluons together into hadrons. Because they can emerge unchanged
from the interior of a RHIC collision, photons and leptons carry
unmodified information about processes within the collision. A
good analogy is that PHENIX looks "inside" the hot,
dense matter formed in the collision, much like x-ray or MRI images show medical doctors the "inside" of the human
body. For example, escaping photons can reveal information about
the temperature of the collision.
PHENIX weighs 4,000 tons and has a dozen detector subsystems.
Three large steel magnets produce high magnetic fields to bend
charged particles along curved paths. Tracking chambers record
hits along the flight path to measure the curvature and thus
determine each particle's momentum. Other detectors identify the
particle type and/or measure the particle's energy. Still others
record where the collision occurred and determine whether each
collision was "head-on" (central), a
"near-miss" (peripheral), or something in between.
has over 450 members from 51 institutions in 11 countries. The PHENIX
detector is located at the 8 o'clock position on the RHIC ring.
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