Exotic nuclei and astrophysics

Yu Penionzhkevich

doi:10.1051/epjconf/20123814002

Abstract

Recently the academic community has marked several anniversaries connected with discoveries that played a significant role in the development of astrophysical investigations. The year 2009 was proclaimed by the United Nations the International Year of Astronomy. This was associated with the 400th anniversary of Galileo Galilei’s discovery of the optical telescope, which marked the beginning of regular research in the field of astronomy. An important contribution to not only the development of physics of the microcosm, but also to the understanding of processes occurring in the Universe, was the discovery of the atomic nucleus made by E. Rutherford 100 years ago. Since then the investigations in the fields of physics of particles and atomic nuclei have helped to understand many processes in the microcosm. Exactly 80 years ago, K. Yanski used a radio-telescope in order to receive the radiation from cosmic objects for the first time, and at the present time this research area of physics is the most efficient method for studying the properties of the Universe. Finally, the April 12, 1961 (50 years ago) launching of the first sputnik into space with a human being onboard, the Russian cosmonaut Yuri Gagarin, marked the beginning of exploration of the Universe with the direct participation of man. All these achievements considerably extended our ideas about the Universe.

Highlights

In the course of evolution, the Universe is permanently enriched in ever heavier chemical elements [1]
The curve of element abundances has the maxima for silicon and iron groups, whereupon it splits into branches: one includes neutron rich isotopes and has three doubled peaks near the magic numbers of N = 50, 82, and 126, while the second includes proton-rich isotopes, which are less abundant
The (A+x,Z) nucleus decays before it absorbs a neutron. It decays via beta decay, which leads to the formation of a new nucleus, (A + x, Z + 1), or undergoes an entire chain of decays that ends up in a nucleus whose lifetime is sufficiently long for a new radiative capture process to have time to occur

Summary

Nucleosynthesis

In the course of evolution, the Universe is permanently enriched in ever heavier chemical elements [1]. The (A+x,Z) nucleus decays before it absorbs a neutron It decays via beta decay, which leads to the formation of a new nucleus, (A + x, Z + 1), or undergoes an entire chain of decays that ends up in a nucleus whose lifetime is sufficiently long for a new radiative capture process to have time to occur. At high neutron densities [r (rapid) process], the (A +x ,Z) nucleus absorbs neutrons before undergoing decay, and this leads to new radiative capture processes This proceeds until the decay chain reaches an isotope whose half-life is very short, and we arrive at the preceding case. Calculations on the basis of the shell model revealed the possible existence of this superheavy nucleus with a halflife of up to about 108 yr [3]

Nuclear physics experiments and astrophysics

Conclusions