Reaction Mechanisms In Intermediate Energy Heavy Ion Collisions

This volume comprises select peer-reviewed papers from the Indo-French Workshop on Multifragmentation, Collective Flow, and Sub-Threshold Particle Production in Heavy-Ion Reactions held at the Department of Physics, Panjab University, Chandigarh, India in February, 2019. The contents highlight latest research trends in intermediate energy nuclear physics and emphasize on the various reaction mechanisms which take place in heavy-ion collisions. The chapters contribute to the understanding of interactions that govern the dynamics at sub-nucleonic level. The book includes contributions from global experts hailing from major research facilities of nuclear physics, and provides a good balance between experimental and theoretical model based studies. Given the range of topics covered, this book can be a useful reference for students and researchers interested in the field of heavy-ion reactions.

Ions are atoms or molecules stripped of their electrons, so they can be accelerated by electric fields. They can be made to hit each other with low energy, intermediate energy, high energy, or very high energy; each energy range seeks to investigate different aspects of hadronic physics. Intermediate-energy heavy ion collisions explore the nuclei far from stability valley, the incompressibility of nuclear matter, the liquid-gas phase transition in nuclear environment, the symmetry energy far from the normal density, and other phenomena. This has been an active field of research for last four decades.This is a book for entrants in the field. It is suitable as a companion book in a graduate course. For practitioners in the field it will be useful as a reference.

In this volume, the following topics are discussed: study of intermediate and low energy heavy ion collisions, nuclear structure at high spin, nuclei far from stability, radioactive ion beam physics and development of experimental facilities.

A systematic study of reaction mechanisms at intermediate energies (50--100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components--intermediate mass fragments (IMF), fission fragments (FF) and heavy residues (HR). Major observed features are: the reaction yields are similar in the 50 to 100 MeV/A range, central collisions have high multiplicity of IMF's with broad angular correlations consistent with a large participant region, effects of final state Coulomb interactions are observed and give information on the size and temporal behavior of the source, true fission yields are dependent on target fissility and correlated with relatively peripheral collisions. Analysis of fission and evaporation yields implies limiting conditions for which fission decay remains a viable deexcitation channel. 15 refs., 7 figs.

Three main experimental results from CERN concerning reaction mechanisms in high energy heavy ion collisions are discussed: (1) the striking validity of the single particle picture, (2) the nuclear stopping power and (3) the attained energy densities.