M. F. Rivet

Ion beam-plasma interaction: A standard model approach

Abstract The interaction of energetic multicharged ion beams with separately produced target plasmas is investigated within a projectile-ion-target-electron bin

Particle identification method in the CsI(Tl) scintillator used for the CHIMERA 4π detector

Abstract The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4 π 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.

Recoil study of transfer reactions: Evidence for α and 8Be transfers in 12C reactions with heavy nuclei (Au, Bi)

Abstract Transfer reactions induced with 12 C ions in Au and Bi targets have been studied. The experimental technique involves the measurement of the cross sections, angular distributions, and recoil range at each recoil angle, of the heavy residual nuclei. The processes leading to the production of At isotopes in the case of a Bi target, and Tl and Bi isotopes in the case of an Au target, have been identified by means of a kinematic analysis of the experimental data. They appear to be 2p, α and 8 Be transfers from the projectile to the target, followed by the evaporation of neutrons. The cross section for 8 Be transfer was derived from experimental data and is significant, of the order of 100 mb. The cross section for α-transfer was estimated to 30 to 80 mb. All the observed characteristics of the residual nuclei produced through α and 8 Be transfers (cross sections, ranges and angular distributions) are in good agreement with the cross sections and angular distributions of the direct α-particles which are the projectile residues of these transfers, and which were observed by other authors.

Mass and charge identification of fragments detected with the Chimera Silicon-CsI(Tl) telescopes

Abstract Mass and charge identification of charged products detected with Silicon–CsI(Tl) telescopes of the Chimera apparatus are presented. An identification function, based on the Bethe–Bloch formula, is used to fit empirical correlations between Δ E and E ADC readings, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products prior to energy calibration.

Bimodal behavior of the heaviest fragment distribution in projectile fragmentation.

The charge distribution of the heaviest fragment detected in the decay of quasiprojectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in nonextensive systems. In this Letter, we present new analyses of experimental data from Au on Au collisions at 60, 80, and 100 MeV/nucleon showing that bimodality is largely independent of the data selection procedure and of entrance channel effects. An estimate of the latent heat of the transition is extracted.

Evidence for α-particle condensation in nuclei from the Hoyle state deexcitation

Abstract The fragmentation of quasi-projectiles from the nuclear reaction 40Ca + 12C at 25 MeV/nucleon was used to produce excited states candidates to α-particle condensation. Complete kinematic characterization of individual decay events, made possible by a high-granularity 4π charged particle multi-detector, reveals that 7.5 ± 4.0 % of the particle decays of the Hoyle state correspond to direct decays in three equal-energy α-particles.

In-medium effects for nuclear matter in the Fermi-energy domain

We study nuclear stopping in central collisions for heavy-ion induced reactions in the Fermi energy domain, between

Energy loss of heavy ions in a hydrogen discharge plasma

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Further experimental evidence for fast fission

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New isospin effects in central heavy-ion collisions at Fermi energies

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