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Nucleosynthesis, Cosmic Radiation, and the Universe
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
The net balance of the first step in stellar nucleosynthesis is the merging of four protons into a helium nucleus. However, this cannot occur in one step. Even at enormous pressure which prevails inside the Sun’s core, the probability that four protons collide simultaneously is insignificant. The formation of a helium nucleus thus has to proceed stepwise. First, two protons must combine to give a deuterium nucleus (with release of a positron). The next step is reaction of deuterium with another proton, producing 3He. The combination of two 3He nuclei gives one stable nucleus of 4He and two protons, 3He+3He→4He+21H in addition to a considerable amount of energy. This energy (26.7 megaelectronvolts for each nucleus of helium formed) contributes to the maintenance of a high temperature in the Sun’s core.
Minerals of base metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Beryllium which can be extracted from bertrandite (Be4Si2O7(OH)2), beryl (Al2Be3Si6O18), chrysoberyl (Al2BeO4) and phenakite (Be2SiO4) is a brittle alkaline earth metal which has its genesis from stellar nucleosynthesis and occurring only in combination with other elements in 100 gemstone minerals notably beryl (aquamarine, emerald) and chrysoberyl. It has a high melting point and is resistant to attacks by acids.
New Energy Sources
Published in Fang Lin Luo, Hong Ye, Renewable Energy Systems, 2013
The most important fusion process in nature is the one that powers stars The net result is the fusion of four protons into one alpha particle, with the release of two positrons, two neutrinos (which changes two of the protons into neutrons), and energy, but several individual reactions are involved, depending on the mass of the star. For stars the size of the Sun or smaller, the proton–proton chain dominates. In heavier stars, the CNO cycle is more important. Both types of processes are responsible for the creation of new elements as part of stellar nucleosynthesis (Figure 2.3).
Japanese evaluated nuclear data library version 5: JENDL-5
Published in Journal of Nuclear Science and Technology, 2023
Osamu Iwamoto, Nobuyuki Iwamoto, Satoshi Kunieda, Futoshi Minato, Shinsuke Nakayama, Yutaka Abe, Kohsuke Tsubakihara, Shin Okumura, Chikako Ishizuka, Tadashi Yoshida, Satoshi Chiba, Naohiko Otuka, Jean-Christophe Sublet, Hiroki Iwamoto, Kazuyoshi Yamamoto, Yasunobu Nagaya, Kenichi Tada, Chikara Konno, Norihiro Matsuda, Kenji Yokoyama, Hiroshi Taninaka, Akito Oizumi, Masahiro Fukushima, Shoichiro Okita, Go Chiba, Satoshi Sato, Masayuki Ohta, Saerom Kwon
Nuclear data of the light nuclei are important not only for nuclear engineering but also for scientific/fundamental researches, e.g. on the stellar nucleosynthesis. Although new experimental and theoretical knowledge had been accumulated over the decades, the neutron cross sections had not been revised in the previous library, JENDL-4.0, for most of the light nuclei. For the present library, neutron cross sections were re-evaluated through the R-matrix [184,185] analysis with the AMUR code [20,21] in the resolved resonance region for 16O, 12,13C, 15N and 19F. The level structure information of the compound nuclei (such as excitation energy, spin and parity for each level) was taken from ENSDF [186], but those data are re-examined for a number of cases so as to give a best fit to the measured cross sections listed in Table 2. We also estimated the covariance data of cross sections in the same energy region with a deterministic approach [17].
Cross Sections for Neutron Production from 6- and 10-MeV Neutrons Incident on 10B and 11B
Published in Nuclear Science and Engineering, 2021
P. W. Lisowski, M. Drosg, D. M. Drake, B. Hoop
Neutron spectra produced from the interaction of neutrons with light nuclei are a characteristic feature in primordial and stellar nucleosynthesis and are essential to applications of nuclear fusion and fusion reactor design. Reliable measurements of nonelastic cross sections are particularly difficult in the range between 8 and 14 MeV because a monoenergetic, high-intensity neutron source is required. Measurements of double-differential neutron cross sections of neutron interactions with beryllium, lithium, boron, and carbon have been reported elsewhere.1–3 The present work describes fast-neutron time-of-flight measurements of neutron emission spectra from 6- and 10-MeV neutron-induced reactions on 10B and 11B using neutrons from the 1H(t,n)3He reaction, corrected for finite target geometry, multiple scattering, and elastic scattering from water contaminants (in the case of 10B), by means of the MCNP 6.2 Monte Carlo code,4 and experimentally from the background of triton interactions with the target structure.