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The capability of digital pulse shape technique to acquire data from CHIMERA detection cells (Si-CsI(TI) telescopes) has been evidenced in our previous works. We have now applied this technique to the charge discrimination of the products stopped in the silicon detectors. Large area totally depleted CHIMERA planar silicon detectors (5 cm x 5 cm area, 300/[micro]m thick) in both rear and front side injection have been used. In preliminary tests full charge identification for the reaction products up to Z = 11 have been obtained for products both crossing ([DELTA]E-E technique) and stopping in the silicon detector, using a 21 MeV/u [sup.20]Ne beam at the LNS Superconducting Cyclotron in Catania. The quality of the obtained results clearly indicates that the digital signal processing approach is able to give excellent results in this application, too. Index Terms--Charged particle identification, digital pulse shape processing, multidetector arrays technique, pulse shape analysis.

We have designed, built, and tested an on-line pre-analysis and data-storage unit for the data acquisition system of the 47r-detector CHIMERA. The unit uses special algorithms to perform particle identification and automatic peak detection. It tags in charge each event and stores the results on external unit, together with the raw data. It consists of two commercial 2 GHz workstations connected together through 1 Gb/s Ethernet boards and to the data acquisition system through a 100 Mb/s Ethernet. Index Terms--Data storage unit, multidetector online monitoring, online computational system.

A 100 Msamples/s 14-bit sampling analog-to-digital converter has been used to perform digital pulse-shape acquisition of signals collected from CHIMERA telescopes. Two different kinds of tests have been carried out to check the performances. The signals from a typical CHIMERA detection cell have been collected using both a standard CHIMERA electronic chain up to the amplifier, and a very simple analog front end, basically reduced to the preamplifier. The obtained on-beam and on-line results are presented. Index Terms--Digital pulse shape acquisition, digital signal processing, multidetector arrays, particle identification, simple analog front end.

Effects related to the neutron to proton ratio (N/Z) degree of freedom in 40,48Ca+40,48Ca reactions at 25 MeV/nucleon have been investigated. Isotopic effect and even-odd staggering characterize the emission of light fragments at forward angles. The study of isobaric ratio 7Li/7Be for quasi-projectile source in semi-peripheral event of reactions allows moreover to investigate isospin diffusion effects in heavy ion collisions.

The first results of the ISODEC experiment, performed at the INFN Laboratori Nazionali del Sud (LNS) by using the CHIMERA detector, are presented. The principal aim of this experiment is to explore the isospin dependence of the decay modes of medium mass compound nuclei formed by fusion processes, by studying the competition between the various disintegration modes of 118,134Ba nuclei produced in the reactions 78Kr+40Ca and 86Kr+48Ca at 10 AMeV. The studied systems allow in fact to produce compound nuclei with a large variation of N/Z, and such data will also provide new constraint on sophisticated models attempting to describe statistical and/or dynamical properties of excited nuclei. The experiment complements data already obtained at 5.5 AMeV for 78,82Kr+40Ca reactions, previously realized at GANIL by using the INDRA detector. First results show a strong staggering effects in the Z distributions, as well as different isotopic composition and enrichment for the reaction products in the two systems.

We will discuss results concerning the fate of hot nuclear systems populated in 40,48Ca+40,48Ca reactions at 25 MeV/nucleon. Due to the complexity of events, we used the Chimera 4π device as detection system. By selecting central events of reaction, we found that the interplay between binary-like and evaporation residue emissions is strongly sensitive on the N/Z of the entrance channels. In particular, evaporation residue emission increases at increasing the neutron content of colliding system. By comparing or data with CoMD-II model calculations, we can extract information about the density depend part of Symmetry Potential in the Nuclear Equation of State at near-saturation densities.

Isospin effects on dynamics of semi-central collisions involving 40Ca+40Ca, 40Ca+48Ca and 48Ca+48Ca reactions at 25 MeV/nucleon have been investigated. For the selected class of events, the balance between the emission of evaporation residues and the presence of binary-like phenomena seems to be influenced by the neutron to proton ratio (N/Z) of entrance channels. In particular, for neutron-rich systems, evaporation residue emission is enhanced. Experimental observations confirm the key role played by the N/Z degree of freedom on nuclear dynamics at 25 MeV/nucleon. [ABSTRACT FROM AUTHOR]

Collisions involving 112Sn and 124Sn nuclei have been calculated with the ImQMD transport model in order to place constraints on the density dependences of the nuclear symmetry energy. Consistent constraints on the symmetry energy at sub-saturation density have been obtained by comparing these transport calculations to measurements of isospin diffusion and to the ratios of neutron and proton spectra. New isospin diffusion results from E/A = 35 MeV are also presented. [ABSTRACT FROM AUTHOR]