[en] In this article the author will present some of the motivations for the study of strangeness production in relativistic heavy ions collisions. Several experimental results have demonstrated that strangeness production is a powerful tool to investigate new phenomena in these collisions. Perspectives are still opened for new and exciting results in these studies. (author)

[en] We report on the first search for neutral strange quark matter in Au+Pb reactions at 11.6 A GeV/c in experiment E864 at the Brookhaven National Laboratory AGS. We have sampled approximately 1.3 billion 10% most central Au+Pb interactions and have observed no evidence for the production of neutral strangelet states with a baryon number in the range 3< A<100. We thus set production limits at the level of 8x10^-8 for these exotic objects in the mass range 15< A<100, and limits between 10^-4 and 10^-7 in the mass range 3< A<15. These limits are rather insensitive to the details of production models thanks to the large acceptance of the E864 spectrometer. The limits for neutral strangelets reported in this work complement other limits reported by our collaboration for positive and negative strangelets (Xu Z 1999 J. Phys. G: Nucl. Part. Phys. 25 403, Van Buren G 1999 J. Phys. G: Nucl. Part. Phys. 25 411). (author)

[en] The STAR (Solenoidal Tracker at RHIC) experiment is a large acceptance collider detector that measures primarily hadronic observables to search for signatures of the quark-gluon plasma phase transition and study strongly interacting matter at high energy density. Operational since June 2000, the new heavy ion collider RHIC has already provided Au+Au collisions at √(σ_NN) = 62, 130 and 200 GeV as well as p+p and d+Au collisions at 200 GeV. The various collision energies and systems allow the systematic study of particle production in heavy ion collisions. In particular, the production of strange (anti-)particles is one of the major topics of STAR. This detector allows the measurement of a variety of particle species at mid-rapidity, like neutral kaons; Λ, Ξ, and Ω. hyperons; and their anti-particles that are reconstructed via their decay topology. The strangeness measurements should provide important information on various phenomenological aspects of ultra-relativistic heavy ion collisions. The goal of this work is to perform the measurement of neutral kaons on Au+Au collisions at 62 GeV. This measurement will bring important information about strangeness production in the energy range between the top RHIC energy and the top SPS energy, where important questions regarding particle production are still open. In this poster, preliminary results of the analysis will be presented, mainly the evaluation of the topological cuts necessary for the neutral kaon reconstruction and the corrections that are necessary to obtain the transverse momentum spectra

[en] Time scales of strongly energy damped and fast processes in light heavy-ion reactions were measured in order to investigate the dynamics involved in the collision. Particle-particle correlation functions at small relative momenta were measured to determine the time scale of sequential particle emission in highly excited light composite systems and the values obtained are compared to the lifetime of the compound nucleus determined by cross section fluctuations measurements. The results indicate that in the case of light nuclear systems, a drastic time scale compression is observed, independent of the inelasticity of the process, in contrast to the case of heavy systems for which the time difference between the fast and slow processes is at least 100-1000 times larger

[en] Systematic studies of fusion barriers for p and light s - d shell nuclei show an increase of the value of their height as the atomic mass number decreases. Two features are observed to be associated to this effect: the low binding energy of a nucleon or cluster and the increase of the nuclear surface diffuseness. The relative competition of these two features is discussed in the present paper

[en] Short communication

[en] Considerable interest has been devoted to fusion reactions between light heavy ions specially between weakly bound ones, due to the anomalous decrease of the fusion cross sections when compared to the total reaction cross section in the energy region around the barrier

[en] Short communication

[en] The investigation of the ^6,7Li + ¹²C, ⁵⁹Co breakup processes (bu) is used to understand the influence of (bu) on the fusion cross section. These measurements help to establish the effect of the projectile breakup on the fusion process at near-barrier energies and contribute to the determination of how the mass of the target affects the process, as well as the influence of the incomplete fusion yield at energies above the barrier. The identification of the breakup products has been achieved measuring the three body final state correlations. Coincidence data are used to determine the process Q-value in order to gate exclusively on the projectile breakup channel. Angular correlations are obtained to identify the several processes. This is complemented by measurements of relative energy of the fragments using different rest frame references (target, projectile, target + fragment) in order to disentangle the contribution of breakup, incomplete fusion and/or transfer-reemission process. These experimental results are compared to three body kinematics calculations. (author)

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