Chapter 5
Halo Nuclei: Properties
and Experimental Techniques
5.1 Halo Nuclei: A Brief Introduction
What follows in this chapter is a concise report on the elementary aspects of halo
nuclei and their experimental studies at Radioactive Ion Beam (RIB) facilities. The
primary effort has been to chronicle the salient findings of the experimental endeavor
to produce and probe the nuclei near the drip lines. Since the pioneering experiments
of Tanihata and collaborators leading to the discovery of the halo structure of
11 Li
in the mid-eighties, the concerted efforts of both experimentalists and theorists have
generated a very large body of knowledge about the halo nuclei. In this chapter, we
make no efforts to present a detailed review of this vast field of research. Instead,
we would like to provide a brief overview containing the basic motivation for such
studies, the salient features of halo nuclei and the rudiments of experimental techniques. The presentation will be mainly centered around light, neutron-rich, drip line
nuclei so as to lay down the motivation for their theoretical studies in the following
chapter.
Several of the nuclei near the drip lines show exotic halo structures and exhibit
exotic properties, hitherto unobserved and unexpected in stable nuclei away from the
drip lines. The starting point of any serious discussion on drip line nuclei is the Segre
chart of nuclides as shown in Fig. 5.1. The Segre chart is a two-dimensional representation of all possible atomic nuclei in terms of the neutron and proton numbers.
This nuclear landscape can also be presented in three dimensions by adding a third
axis representing the total ground state energy of each nuclide. The black squares
running roughly along the middle of the plot in Fig. 5.1 represent the stable isotopes,
around three hundred or so, and form the so-called line of beta stability.
In a three-dimensional plot, they will form the valley (of beta stability) in the
potential energy surface. For a given proton (or neutron) number moving along the
increasing neutron (or proton) number one reaches the edge of the landscape, the
so-called dripline, where the separation energy of the neutron (or proton) becomes
zero. The total number of nuclides in the entire region bounded by the two drip
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
V. S. Bhasin and I. Mazumdar, Few Body Dynamics, Efimov Effect and Halo Nuclei,
SpringerBriefs in Physics,
https://doi.org/10.1007/978-3-030-56171-0_5
57
Halo Nuclei: Properties
and Experimental Techniques
5.1 Halo Nuclei: A Brief Introduction
What follows in this chapter is a concise report on the elementary aspects of halo
nuclei and their experimental studies at Radioactive Ion Beam (RIB) facilities. The
primary effort has been to chronicle the salient findings of the experimental endeavor
to produce and probe the nuclei near the drip lines. Since the pioneering experiments
of Tanihata and collaborators leading to the discovery of the halo structure of
11 Li
in the mid-eighties, the concerted efforts of both experimentalists and theorists have
generated a very large body of knowledge about the halo nuclei. In this chapter, we
make no efforts to present a detailed review of this vast field of research. Instead,
we would like to provide a brief overview containing the basic motivation for such
studies, the salient features of halo nuclei and the rudiments of experimental techniques. The presentation will be mainly centered around light, neutron-rich, drip line
nuclei so as to lay down the motivation for their theoretical studies in the following
chapter.
Several of the nuclei near the drip lines show exotic halo structures and exhibit
exotic properties, hitherto unobserved and unexpected in stable nuclei away from the
drip lines. The starting point of any serious discussion on drip line nuclei is the Segre
chart of nuclides as shown in Fig. 5.1. The Segre chart is a two-dimensional representation of all possible atomic nuclei in terms of the neutron and proton numbers.
This nuclear landscape can also be presented in three dimensions by adding a third
axis representing the total ground state energy of each nuclide. The black squares
running roughly along the middle of the plot in Fig. 5.1 represent the stable isotopes,
around three hundred or so, and form the so-called line of beta stability.
In a three-dimensional plot, they will form the valley (of beta stability) in the
potential energy surface. For a given proton (or neutron) number moving along the
increasing neutron (or proton) number one reaches the edge of the landscape, the
so-called dripline, where the separation energy of the neutron (or proton) becomes
zero. The total number of nuclides in the entire region bounded by the two drip
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
V. S. Bhasin and I. Mazumdar, Few Body Dynamics, Efimov Effect and Halo Nuclei,
SpringerBriefs in Physics,
https://doi.org/10.1007/978-3-030-56171-0_5
57