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Heavy Ion Colliders

Strangelets, if at all stable, are most likely to be produced in relativistic heavy ion collisions, because of the high energies and large numbers of particles involved. In this context they have an additional attraction, in that they may provide a signal of the elusive Quark-Gluon Plasma. (It is sociologically interesting, as RHIC nears completion, to observe the transition in proposals from claiming that there is ``no need to create the QGP'' to create strangelets to calling them ``an important signal of the QGP.'') Many experiments have been run searching for strangelets at both CERN and the AGS at Brookhaven, and more are proposed at RHIC and the LHC using the STAR and ALICE detector systems. There is a detailed scenario common to these searches of strangeness distillation followed by condensation of a strangelet from the Quark-Gluon Plasma. It may also be possible to form strangelets via coalescence of the necessary ingredients, without the need to pass through the plasma phase. This is more likely at the lower energy facilities due to the more limited expansion of the system.

Although the details of each experiment are different, the basic principles are quite similar. All of the relativistic collider experiments rely on the extremely low charge to mass ratio of a strangelet for identification. They each use some form of trajectory reconstruction to establish P/Z. The velocity of the particles is obtained from time of flight measurements, and Z may be determined from energy loss measurements. Overall the experiments place limits on the cross section for production of strangelets which leave sufficient room to be hopeful for the proposals for the new experiments at RHIC and the LHC.

Joshua Holden
Sun May 17 15:37:00 EDT 1998