IOPP Seminar- Dr.Yifei Niu ,,10:30am,Nov.11,Wednesday,2015

Time: 10:30am, Wednesday,Nov.11,
Location: Room 9409
Title: Nuclear Collective Vibrations: From Labs to Stars
Speaker: Yifei Niu (INFN, Milan, Italy)

The nucleus is composed of two kinds of fermions, namely the protons and
neutrons, which introduce an additional degree of freedom called
isospin. This unique feature of a nucleus system gives rise to various
interesting phenomena, among which are the nuclear collective
vibrations, modes involving coherent motions of many particles in the
nucleus. The study of nuclear collective vibrations itself provides
insight to the basic questions like “What is the equation of state (EOS)
of nuclear matter?” and “What is the interaction between nucleons in
nuclear medium that governs the properties of nuclei?”. Furthermore, the
nuclear collective vibrations govern the nuclear weak interaction
processes such as beta-decay, electron capture, and neutrino-nucleus
reaction, and these are essential in the pursuit of answers to bigger
questions such as “How were the heavy elements from iron to uranium
made?” and “How do stars explode?” Therefore, the nuclear collective
vibrations play a crucial role in phenomena both on the earth and in the
universe. In this seminar, I would like to explain our advanced study on
nuclear collective vibrations within the density functional theory
(DFT). Several examples will be presented, such as pygmy dipole
resonances, Gamow-Teller resonances, beta-decay half-lives, electron
capture rates in stellar environment, etc., and their connections to the
above-mentioned questions will be emphasized.