The Role of Surface Entropy in Statistical Emission of Massive Fragments from Equilibrated Nuclear Systems

Abstract

Statistical fragment emission from excited nuclear systems is studied within the framework of a schematic Fermi-gas model combined with Weisskopf's detailed balance approach. The formalism considers thermal expansion of finite nuclear systems and pays special attention to the role of the diffuse surface region in the decay of hot equilibrated systems. It is found that with increasing excitation energy, effects of surface entropy lead to a systematic and significant reduction of effective emission barriers for fragments and, eventually, to the vanishing of these barriers. The formalism provides a natural explanation for the occurrence of negative nuclear heat capacities reported in the literature. It also accounts for the observed linearity of pseudo-Arrhenius plots of the logarithm of the fragment emission probability {\it versus} the inverse square-root of the excitation energy, but does not predict true Arrhenius behavior of these emission probabilities.

References in corpus (4)

• Caloric curves and critical behavior in nuclei
• The liquid to vapor phase transition in excited nuclei
• Limiting temperatures and the Equation of State of Nuclear Matter
• Caloric Curves and Nuclear Expansion

Cited by in corpus (13)

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• Heavy Residue Isoscaling as a Probe of the Symmetry Energy of Hot Fragments
• Emission of charged particles from excited compound nuclei
• The Caloric Curve for Mononuclear Configurations
• Comparison of mid-velocity fragment formation with projectile-like decay
• Short timescale behavior of colliding heavy nuclei at intermediate energies
• Retardation of Particle Evaporation from Excited Nuclear Systems Due to Thermal Expansion
• Liquid-Gas Coexistence and Critical Behavior in Boxed Pseudo-Fermi Matter
• Evaluation of the curvature-correction term from the equation of state of nuclear matter
• Isoscaling in statistical fragment emission in an extended compound nucleus model
• Common Signatures of Statistical Coulomb Fragmentation of Highly Excited Nuclei and Phase Transitions in Confined Microcanonical Systems
• On a variational principle model for the Nuclear Caloric curve
• Common Approaches in Description of Ordinary Liquids and Hadronic Matter