High baryon density heavy ion physics
The regime of heavy ion physics which can be realized at the AGS is that of
near maximal density baryonic matter. A rich variety of physics is available
with these conditions. This is especially true in the light of the high
intensities available with the AGS heavy ion beams. The AGS fixed target
physics program will not have achieved even a majority of the interesting
studies possible by the time RHIC begins operating.
While the physics of RHIC is clearly of primary interest, there are a number
of reasons why it will be scientifically important to continue to explore the
physics regimes of the AGS. The fundamental reason is that a full understanding
of the behaviour of hadronic matter in the new conditions made possible by
high energy heavy ion collisions requires an understanding of the baryon rich
regime as well as the hot (presumably) baryon free central regions made
available at RHIC.
Along with this basic reason there are possible new ``exotic'' states of
nuclear matter which can only be created at the AGS. These include strangelets
and high strangeness hyperfragments involving both 
and 
hyperons. The existence of strangelets is of course not a certainty but if they
did exist, they would be very important both for fundamental and practical
reasons. The existence of the high strangeness hyperfragments is also not
``guaranteed'' by our current understanding but is suggested by the present
state of knowledge of hyperfragments and low baryon number nuclear physics.
Such high strangeness hyperfragments could exist with arbitrarily large
strangeness. They would obey a new nuclear physics in which
there were four hadrons
(
, p,n) instead of two (p,n).
Some specifics on most of these topics are given below in the section on the
``upgrade'' of E-864. Many more are possible.
In addition to the primary scientific drive there are technical and educational
reasons to pursue a active AGS program. The high marginal productivity of the
AGS program (the AGS must be kept in a ``warm'' operating state to serve as an
injector to RHIC) means that fixed target experiments require only incremental
resources associated with the beam line and the detector. The experiments are
by nature smaller than collider experiments and can turn over faster. They
provide flexibility in the program and an invaluable opportunity for younger
physicists to gain leadership experience and to see an experiment from
inception to analysis.
To date one activity has been undertaken under the auspices of the AGS 2000
workshop and this is listed below.
To view the entire high density heavy ion physics document as a single
postscript file, click here .