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Investigations on the influence of the neutron enrichment on the decay channels of excited nuclei are presented. Characteristics of fragments with charge 6 ≤ Z ≤ 28 emitted in 78,82Kr+40Ca at 5.5 MeV/A reactions were measured at the GANIL facility. Data are compatible with an emission process from compound nucleus and are discussed in the framework of the transition state model. [ABSTRACT FROM AUTHOR]

The blocking technique in single crystals has been applied to reaction time measurements for the 238U + Ge system at 6.1 MeV/nucleon. Backed up with a reaction mechanism analysis using the INDRA 4π detector, it provides a direct experimental evidence for Z = 124 compound nuclei living longer than 10-18 s, indicating thus very high fission barriers for this element. [ABSTRACT FROM AUTHOR]

Using the 4π CHIMERA detector system we have observed a dynamical, non-equilibrated fission of projectile-like fragments as well as an equilibrated fission component in collisions 124Sn + 64Ni and 112Sn + 58Ni at 35A MeV. The velocity and angular distributions of projectile-like fission fragments were analyzed. The contribution of the "dynamical fission" component is larger in the neutron rich 124Sn + 64Ni system than in the neutron poor 112Sn + 58Ni one. [ABSTRACT FROM AUTHOR]

The transport properties of the 36Ar + 58Ni system at 95 A. MeV measured with the INDRA array, are studied within the BNV kinetic equation. A general protocol of comparison between the N-body experimental fragment information and the one-body distribution function is developed using global variables, with a special focus on charge density. This procedure avoids any definition of sources and any use of an afterburner in the simulation. We shall discuss the feasibility of such an approach and the distortions induced by the finite detection efficiency and the completeness requirements of the data selection. The sensitivity of the different global observables to the macroscopic parameters of the effective nuclear interaction will be studied in detail. [ABSTRACT FROM AUTHOR]

Abstract: The low-lying spectroscopy of 6He was investigated via the 2-neutron transfer reaction with the 8He beam delivered by the SPIRAL facility at . The light charged particles produced by the direct reactions were measured using the MUST2 Si-strip telescope array. Above the known state, two new resonances were observed: at (width ) and at with . Through the analysis of the angular distributions, they correspond to a state and to an state, respectively. These new states, challenging the nuclear theories, could be used as benchmarks for checking the microscopic inputs of the newly improved structure models, and should trigger development of models including the treatments of both core excitation and continuum coupling effects. [Copyright &y& Elsevier]

Abstract: Fragment properties of hot fragmenting sources of similar sizes produced in central and semi-peripheral collisions are compared in the excitation energy range . For semi-peripheral collisions a method for selecting compact quasi-projectiles sources in velocity space similar to those of fused systems (central collisions) is proposed. The two major results are related to collective energy. The weak radial collective energy observed for quasi-projectile sources is shown to originate from thermal pressure only. The larger fragment multiplicity observed for fused systems and their more symmetric fragmentation are related to the extra radial collective energy due to expansion following a compression phase during central collisions. A first attempt to locate where the different sources break in the phase diagram is proposed. [Copyright &y& Elsevier]

Abstract: We analyzed the 93Nb on natMg reaction at 30 MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. ≃3 MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we reconstruct simulated charge, mass and excitation energy distributions and compare them to the experimental ones. We show that data are better described by SMM than by GEMINI in agreement with the fact that multifragmentation is responsible for fragment production at excitation energies around 3 MeV/nucleon. [Copyright &y& Elsevier]

Abstract: Freeze-out properties of multifragmentation events produced in central 129Xe+ natSn collisions at different beam energies (32, 39, 45 and 50 A MeV) were estimated by means of a simulation based on the experimental data collected by the 4π INDRA multidetector. A rapid increase (between 32 and 45 A MeV) of the fraction of particles emitted at freeze-out is deduced. The existence of a limitation of excitation energy for fragments around 3.0–3.5 A MeV is confirmed. A comparison with the results of a microcanonical statistical model is also performed to verify the overall physical coherence of the present approach. [Copyright &y& Elsevier]

Abstract: Correlation functions, constructed from directional projections of the relative velocities of fragments, are used to determine the shape of the breakup volume in coordinate space. For central collisions of 129Xe+ natSn at 50 MeV per nucleon incident energy, measured with the 4π multidetector INDRA at GSI, a prolate shape aligned along the beam direction with an axis ratio of is deduced. The sensitivity of the method is discussed in comparison with conventional fragment–fragment velocity correlations. [Copyright &y& Elsevier]

Abstract: The spectroscopy of 27Ne has been investigated through the one-neutron transfer reaction 26Ne()27Ne in inverse kinematics at 9.7 MeV/nucleon. The results strongly support the existence of a low-lying negative parity state in 27Ne, which is a signature of a reduced sd–fp shell gap in the neutron-rich region, at variance with stable nuclei. [Copyright &y& Elsevier]

Abstract: Kinetic energy spectra and fragment velocity correlations, simulated by means of stochastic mean-field calculations, are successfully confronted with experimental data for single multifragmenting sources prepared at the same excitation energy per nucleon in 32 A MeV 129Xe+ natSn and 36 A MeV 155Gd+ natU central collisions. Relying thus on simulations, average freeze-out times of 200–240 fm/c are estimated. The corresponding spatial distributions of fragments are more compact for the lighter system ( vs. ). [Copyright &y& Elsevier]

Abstract: Directed and elliptic flow for the 197Au + 197Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4π multi-detector. For semi-central collisions, the elliptic flow of particles switches from in-plane to out-of-plane enhancement at around 100 MeV per nucleon, in good agreement with the result reported by the FOPI Collaboration. The directed flow changes sign at a bombarding energy between 50 and 60 MeV per nucleon and remains negative at lower energies. The conditions for the appearance and possible origins of the observed antiflow are discussed. [Copyright &y& Elsevier]

The nucleus-nucleus Lie`ge intranuclear-cascade+percolation+evaporation model has been applied to the 12C+197Au data measured by the INDRA-ALADIN collaboration at GSI. After the intranuclear cascade stage, the data are better reproduced when using the Statistical Multiframentation Model as afterburner. Further checks of the model are done on data from the EOS and KAOS collaborations. [Copyright &y& Elsevier]

An efficient method of energy scale calibration for the CsI(Tl) modules of the INDRA multidetector (rings 6–12) using elastic and inelastic 12C+1H scattering at E(12C)=30MeV per nucleon is presented. Background-free spectra for the binary channels are generated by requiring the coincident detection of the light and heavy ejectiles. The gain parameter of the calibration curve is obtained by fitting the proton total charge spectra to the spectra predicted with Monte-Carlo simulations using tabulated cross section data. The method has been applied in multifragmentation experiments with INDRA at GSI. [Copyright &y& Elsevier]

The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4π heavy-ion detector is presented. A simple double-gate integration method, with the use of the cyclotron radiofrequency as reference time, results in low thresholds for isotopic particle identification. The dependence of the identification quality on the gate generation timing is discussed. Isotopic identification of light ions up to Beryllium is clearly seen. For the first time also the identification of Z=5 particles is observed. The identification of neutrons interacting with CsI(Tl) by (n,α) and (n,γ) reactions is also discussed. [Copyright &y& Elsevier]