Fragmentation in Peripheral Heavy-Ion Collisions: from Neck Emission to Spectator Decays

Abstract

Invariant cross sections of intermediate mass fragments in peripheral collisions of Au on Au at incident energies between 40 and 150 AMeV have been measured with the 4-pi multi-detector INDRA. The maximum of the fragment production is located near mid-rapidity at the lower energies and moves gradually towards the projectile and target rapidities as the energy is increased. Schematic calculations within an extended Goldhaber model suggest that the observed cross-section distributions and their evolution with energy are predominantly the result of the clustering requirement for the emerging fragments and of their Coulomb repulsion from the projectile and target residues. The quantitative comparison with transverse energy spectra and fragment charge distributions emphasizes the role of hard scattered nucleons in the fragmentation process.

arXiv comment5 pages, 5 eps figures, RevTeX4, submitted to Phys. Lett. B

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• Bimodal behavior of the heaviest fragment distribution in projectile fragmentation
• Correlations and Characterization of Emitting Sources
• Thermal and Chemical Freeze-out in Spectator Fragmentation
• Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV
• Statistical Multifragmentation of Non-Spherical Expanding Sources in Central Heavy-Ion Collisions
• Systematic study of multi-fragmentation in asymmetric colliding nuclei
• Isospin effects on two-particle correlation functions in E/A = 61 MeV 36Ar + 112,124Sn reactions
• Fragment properties of fragmenting heavy nuclei produced in central and semi-peripheral collisions
• Estimate of average freeze-out volume in multifragmentation events
• Bimodality - a general feature of heavy ion reactions
• Distinctive features of Coulomb-related emissions in peripheral heavy ion collisions at Fermi energies
• Multiplicity correlations of intermediate-mass fragments with pions and fast protons in 12C + 197Au
• New scalings in nuclear fragmentation
• Analysis of charged particle emission sources and coalescence in E/A = 61 MeV ${}^{36}$Ar + ${}^{27}$Al, ${}^{112}$Sn and ${}^{124}$Sn collisions
• Size and asymmetry of the reaction entrance channel: influence on the probability of neck production
• Dispersion of longitudinal momentum distributions induced in fragmentation reactions