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Dissipative 12C + 12C reactions at 95 MeV are fully detected in charge with the GARFIELD and RCo apparatuses at Laboratori Nazionali di Legnaro. A comparison to a dedicated Hauser-Feshbach calculation allows us to select events which correspond, to a large extent, to the statistical evaporation of highly excited 24Mg, as well as to extract information on the isotopic distribution of the evaporation residues in coincidence with their complete evaporation chain. Residual deviations from statistical behavior are observed in ɑ yields and attributed to the persistence of cluster correlations well above the 24Mg threshold for six-a decay. [ABSTRACT FROM AUTHOR]

Odd-even staggering effects on charge distributions are investigated for fragments produced in semiperipheral and central collisions of 112Sn + 58Ni at 35 MeV/nucleon. For fragments with Z ⩽ 16 one observes a clear overproduction of even charges, which decreases for heavier fragments. Staggering persists up to Z ∼ 30. The staggering appears to be substantially independent of the centrality of the collisions, suggesting that it is mainly related to the last few steps in the decay of hot nuclei. [ABSTRACT FROM AUTHOR]

Experimental data concerning binary events in peripheral collisions for the systems 93Nb + 93Nb and 93Nb + 116Sn at 38 MeV/nucleon, collected with the FIASCO setup, are compared with calculations performed with the dynamic code AMD, coupled with the statistical code Gemini used as an afterburner. The comparison focuses on the properties of the quasiprojectile (QP) and on the total multiplicities of the emitted light charged particles. A good reproduction of the average mass ratio, charge Z, and center-of-mass angle of the QP is obtained in the examined impact parameter range (b ≈ 7 - 12 fm). Concerning the light charged particles, a general agreement is found for the total emitted charge, while some discrepancy remains for the multiplicities of the various species, especially for the protons, which are always overestimated by the calculations. [ABSTRACT FROM AUTHOR]

The decay of an excited 24Mg nucleus into six α particles is studied, from a selection of central 12C+12C reactions at 95 MeV beam energy, measured with the GARFIELD-RCo apparatus. Kinematic correlations among the detected α particles allow investigating the decay mechanism leading to the full disassembly of 24Mg into α particles. Experimental data indicate that the decay proceeds through intermediate doorway states involving excited states of 12C and 8Be, with an important branching ratio estimated to be of the order of 40%. The possibility of a simultaneous breakup of the hot source in three bodies (α, 8Be, 12C) is excluded in favor of a sequential emission. This is confirmed by comparison with statistical model predictions, where the emission of 8Be in both its ground state and first excited state is considered. Residual differences with respect to the statistical model are observed, particularly in the branching ratio of the Hoyle state with respect to higher excitation energy 12C states. [ABSTRACT FROM AUTHOR]

The correlations between mass distributions of the binary fragments, total kinetic energy (TKE), and neutron multiplicity have been investigated for the reaction 50Ti+208Pb at 294 MeV bombarding energy. Although this reaction has been used to synthesize the Rf (Z=104) superheavy element, a complete study of its fragmentation dynamics is still not available in the literature. In this work, average neutron multiplicities were extracted as a function of different fragment mass splits and TKE windows. A weak increase of the prescission neutron multiplicity is observed going from asymmetric to symmetric mass splits. A fission delay time of 4.5×10-20 s has been extracted for the symmetric fission. The neutron multiplicity extracted for the symmetric mass split was used to derive the average number of neutrons emitted in the spontaneous fission of 258Rf. The extrapolated value of 4.7±1.4 is found to be consistent with systematics of spontaneous and neutron-induced fission in heavy nuclei and with the results of previous works for superheavy nuclei with Z=116 and Z=124. [ABSTRACT FROM AUTHOR]

Peripheral and semiperipheral collisions have been studied in the system 93Nb+93Nb at 38A MeV. The evaporative and midvelocity components of the light charged particle and intermediate mass fragment emissions have been carefully disentangled. In this way it was possible to obtain the average amount not only of charge and mass, but also of energy, pertaining to the midvelocity emission, as a function of an impact parameter estimator. This emission has a very important role in the overall balance of the reaction, as it accounts for a large fraction of the emitted mass and for more than half of the dissipated energy. As such, it may give precious clues on the microscopic mechanism of energy transport from the interaction zone toward the target and projectile remnants.

The emission pattern in the v(perp)-v(par) plane of intermediate mass fragments with Z = 3--7 (IMF) has been studied in the collision 116Sn+ 93Nb at 29.5A MeV as a function of the total kinetic energy loss of the reaction. This pattern shows that for peripheral reactions most IMF's are emitted at velocities intermediate between those of the projectile- and target-like products. Coulomb trajectory calculations show that these IMF's are produced in the interaction zone in a short time interval at the end of the target-projectile interaction.