Nuclear astrophysics
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EMENTARY PARTICLES AND FIELDS Experiment
Nuclear Astrophysics Yu. E. Penionzhkevich* Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia Received December 28, 2009
Abstract—The International Year of Astronomy 2009 (IYA2009) was declared by the 62nd General Assembly of the United Nations and was also endorsed by UNESCO. Investigations in the realms of particle and nuclear physics make a large contribution in the development of our ideas of the properties of the Universe. The present article discusses some problems of the evolution of the Universe, nucleosyntheses, and cosmochronology from the point of view of nuclear and particle physics. Processes occurring in the Universe are compared with the mechanisms of the production and decay of nuclei, as well as with the mechanisms of their interaction at high energies. Examples that demonstrate the potential of nuclearphysics methods for studying cosmic objects and the properties of the Universe are given. The results that come from investigations into nuclear reactions induced by beams of radioactive nuclei and which make it possible to take a fresh look at the nucleosynthesis scenario in the range at light nuclei are presented. DOI: 10.1134/S106377881008020X
1. INTRODUCTION In recent years, nuclear-physics investigations into the laws of the microscopic world have contributed to extend significantly our knowledge of phenomena occurring in the macroscopic world (Universe) and have made a formidable contribution to the development of astrophysical and cosmological theories. First of all, this concerns the expandinguniverse model, the evolution of stars, and the abundances of elements, as well as the properties of various stars and cosmic objects, including “cold” and neutron stars, black holes, and pulsars. Without claiming to give a full account of all cosmological problems, we will dwell upon those of them that, in my opinion, have much in common with nuclearmatter properties manifesting themselves in nuclear interactions.
magic numbers of N = 50, 82, and 126, while the second includes proton-rich isotopes, which are less abundant. log N 12 10 1
8
3
6
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4 r s
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r s 0
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2. NUCLEOSYNTHESIS In the course of evolution, the Universe is permanently enriched in ever heavier chemical elements [1]. The abundances of chemical elements in the Universe is determined by various methods: by the spectrum of radiation from stars and by an element analysis of terrestrial and cosmic samples (meteorites and lunar samples). The curve of abundances of elements that was obtained in this way is shown in Fig. 1. The curve has maxima for silicon and iron groups, whereupon it splits into branches: one includes neutronrich isotopes and has three doubled peaks near the *
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1460
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p 0
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Fig. 1. Curve of the relative abundance N of elements versus their mass number A. The upper curve, which features doubled peaks (r and s) corresponds to neutronrich isotopes, while the lower branch (p) corresponds to proton-rich is
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