Dr. Ian J. Thompson, Nuclear Physicist, LLNL, 1/14
The Halo at the Center of the Atom
Dr. Ian J. Thompson is currently employed as a Nuclear Physicist in the Nuclear Theory and Modeling Group at the Lawrence Livermore National Laboratory, USA. He was until 2006 a Professor of Physics at the University of Surrey, UK., and remains a Visiting Professor at Surrey. His professional research deals with coupled-channels and few-body models for nuclear structure and reactions, especially concerning halo nuclei. He is a Fellow of the Institute of Physics in the U.K. He has published over 200 articles in refereed journals, supervised 9 Ph.D. research students, written a nuclear physics textbook Nuclear Reactions for Astrophysics, and has contributed the chapter on Coulomb Functions to the new NIST Handbook of Mathematical Functions.
In order to understand how all the chemical elements are produced, we have to understand not just the elements we find on earth now, but also those varieties of elements that appeared fleetingly in stellar explosions. In the last 20 years, physicists have been able to recreate many of these short-lived varieties, and have discovered many new features not seen in their long-lived cousins. Most stable nuclei have approximately equal number of protons and neutrons (the protons have a positive charge, while the neutrons form a neutral glue holding the nucleus together). Now, however, we discover that there was once, and are now again in the laboratory, some exotic nuclear varieties with many more neutrons than protons. Sometimes these extra neutrons form a large halo around the protons, in the nucleus at the center of the atom. We have discovered that the halo is much larger in size than the range of the force which contains it. I will look especially at some this and other strange properties of nuclear halos: how we need to use the wave features of modern quantum physics to see how they can even exist at all, how we measure their properties, and what possible use such atoms may have again.