During the 1993 AGS heavy ion run, experiment E886 conducted a strangelet search in Au + Pt reactions, with beam momentum of 10.8 GeV/c per nucleon. Presented here are the upper limit for strangelet production, invariant cross sections for p, t, d, 3He, 4He, 6He, 8He, 6Li, 7Li, 8Li and 7Be, along with a demonstration of their agreement with a coalescence model fit to data collected by E886 during the 1992 engineering run, and upper limits for production cross sections for other rare objects, such as (H dibaryon)-nucleus systems. All results reported are preliminary.

We have searched for strangelets in a triggered sample of 61 million central (top 4percent) Au+Au collisions at sqrt sNN = 200 GeV near beam rapidities at the STAR solenoidal tracker detector at the BNL Relativistic Heavy Ion Collider. We have sensitivity to metastable strangelets with lifetimes of order>_0.1 ns, in contrast to limits over ten times longer in BNL Alternating Gradient Synchrotron (AGS) studies and longer still at the CERN Super Proton Synchrotron (SPS). Upper limits of a few 10-6 to 10-7 per central Au+Au collision are set for strangelets with mass>~;;30 GeV/c2.

Central collisions between nuclei at relativistic energies form a hot and dense hadronic system over a large volume. Phenomenological models, as well as QCD calculations on the lattice, predict a phase transition in nuclear matter leading to deconfinement, a state of matter in which quarks and gluons are free to move inside the entire volume of the deconfined region. This new state was given the name of Quark Gluon Plasma (QGP). Based on the conjecture that collisions of heavy nuclei at high energies can create the necessary condition of a high energy density thermalized system, a series of experiments were built to search for possible signals of QGP creation. The NA35 collaboration uses a wide acceptance apparatus at the CERN SPS which detects the majority of charged hadrons (h{sup {+-}}), and neutral strange particles produced in reactions of p, 16O and 32S projectiles at 60 and 200 GeV/nucleon lab momentum on different targets. It consists of two major tracking devices which provide the momentum measurement of the charged particles: a 2 m long streamer chamber (SC) which is placed inside a 1.5 T vertex magnet, viewed by three cameras, and a 2.5x1.5x1.0 m3 Time Projection Chamber (TPC). A set of calorimeters was used as the basic trigger device of the experiment, to select central (small impact parameter) collisions. In the data presented here, a calorimeter placed in the beam path selects near head-on collisions, i.e. events where only a small amount of energy (mostly spectator nucleon energy) was detected in an angular acceptance of less than 0.3 degrees around the beam axis. The data sample consists of three systems: S+S, S+Ag and S+Au at 200 GeV/c with trigger cross section of 3, 3.2 and 6% of the total inelastic cross section, respectively.