Experimental Studies of Nuclear Interactions in Few-Nucleon Systems

E Stephan,A Kozela,N Kalantar-Nayestanaki,St Kistryn

doi:10.1007/s00601-017-1248-8

Abstract

Systems of three nucleons (3N) can be treated as a testing ground for modern approaches to describe nuclear interactions. At intermediate energies, observables for 3N systems are sensitive to subtle effects of the dynamics beyond the pairwise nucleon–nucleon force, so-called 3N-force (3NF). For years the search for 3NF has been motivating precise measurements of observables of elastic nucleon–deuteron scattering and for the deuteron breakup reaction. Breakup of a deuteron in collision with a proton leads to the final state of three free nucleons, with variety of possible kinematic configurations, revealing locally enhanced sensitivity to particular aspects of the interaction dynamics, like 3NF, Coulomb force between protons, or relativistic effects. This feature makes the breakup reaction a very versatile tool for validation of the theoretical description. Reactions involving four nucleons pose immense challenges with regard to exact theoretical calculations for such systems. Nonetheless, they attract attention due to expected enhanced sensitivity to certain aspects of the nuclear dynamics, manifesting themselves in various channels and configurations. The most important results of recent experimental studies of 3N and 4N systems at intermediate energies are discussed. A brief survey of the ongoing projects is given.

Highlights

Understanding the structure and dynamics of nuclei as systems of interacting nucleons is one of the central goals of nuclear physics
Conclusions on the role of 3NF for the description of the cross section for the breakup reaction are to a large extent similar to the observations for the elastic scattering
Coulomb effects turned out to be surprisingly large at specific kinematics [20,27,33] and correctly described by the calculations combining 3NF and Coulomb interactions [34], see example in Fig. 2, left panel

Summary

Introduction

Understanding the structure and dynamics of nuclei as systems of interacting nucleons is one of the central goals of nuclear physics. State-of-the-art models of 3NF’s, like TM99 [1], Urbana IX [2], or Illinois [3], combined with the so-called realistic nucleon–nucleon (2N) potentials, constitute the basis for calculations of binding energies and scattering observables. Ab-initio calculations show that contributions of 3NF’s are important for correct description of shell structure of neutron-rich nuclei, stability close to the neutron drip line, saturation in nuclear matter Observables for three-nucleon systems, as a subject of accurate ab-initio calculations, represent an excellent testing ground for 2N + 3NF interactions, constructed in any of the ways mentioned above

Experimental Studies of 3N Systems

Experimental Studies of 4N Systems

Summary

75 Page 6 of 6