skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nuclear Halos and Borromeans in the Primordial Nucleosynthesis Process and in Astrophysical Nuclear Reactions

Abstract

Nuclear halo structures and Borromean nuclei have been intensely studied almost two decades. They have a cloud of neutrons and protons extended well beyond the surface of tightly bound core of neutrons and protons which is classically forbidden. Since the extended tail of the valance neutron wave-function of the neutron halos the cross-sections are much larger and their sizes become substantially much larger than the ordinary nuclei. Inferred expectations of halo and Borroeman nuclei in astrophysics due to their novel structures have been suggested to influence the astrophysical reactions, especially in the primordial furnace during the Standard Big Bang Nucleosynthesis (SBBN) process. It is seen that the large spatial extension directly implies that both elastic and absorption cross-sections are large for the reactions involving halo nuclei. The Trojan Horse Method (THM) and the Distorted Wave Born Approximation (DWBA) reaction cross-sections calculations are discussed for low energies.

Authors:
;  [1]
  1. Department of Engineering Physics, Faculty of Engineering, University of Gaziantep, 27310 Gaziantep (Turkey)
Publication Date:
OSTI Identifier:
21057205
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 899; Journal Issue: 1; Conference: 6. international conference of the Balkan Physical Union, Istanbul (Turkey), 22-26 Aug 2006; Other Information: DOI: 10.1063/1.2733292; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ABSORPTION; ASTROPHYSICS; COSMOLOGY; CROSS SECTIONS; DWBA; NEUTRONS; NUCLEAR HALOS; NUCLEAR REACTIONS; NUCLEAR STRUCTURE; NUCLEI; NUCLEOSYNTHESIS; PROTONS; WAVE FUNCTIONS

Citation Formats

Yilmaz, M., and Oezer, O.. Nuclear Halos and Borromeans in the Primordial Nucleosynthesis Process and in Astrophysical Nuclear Reactions. United States: N. p., 2007. Web. doi:10.1063/1.2733292.
Yilmaz, M., & Oezer, O.. Nuclear Halos and Borromeans in the Primordial Nucleosynthesis Process and in Astrophysical Nuclear Reactions. United States. doi:10.1063/1.2733292.
Yilmaz, M., and Oezer, O.. Mon . "Nuclear Halos and Borromeans in the Primordial Nucleosynthesis Process and in Astrophysical Nuclear Reactions". United States. doi:10.1063/1.2733292.
@article{osti_21057205,
title = {Nuclear Halos and Borromeans in the Primordial Nucleosynthesis Process and in Astrophysical Nuclear Reactions},
author = {Yilmaz, M. and Oezer, O.},
abstractNote = {Nuclear halo structures and Borromean nuclei have been intensely studied almost two decades. They have a cloud of neutrons and protons extended well beyond the surface of tightly bound core of neutrons and protons which is classically forbidden. Since the extended tail of the valance neutron wave-function of the neutron halos the cross-sections are much larger and their sizes become substantially much larger than the ordinary nuclei. Inferred expectations of halo and Borroeman nuclei in astrophysics due to their novel structures have been suggested to influence the astrophysical reactions, especially in the primordial furnace during the Standard Big Bang Nucleosynthesis (SBBN) process. It is seen that the large spatial extension directly implies that both elastic and absorption cross-sections are large for the reactions involving halo nuclei. The Trojan Horse Method (THM) and the Distorted Wave Born Approximation (DWBA) reaction cross-sections calculations are discussed for low energies.},
doi = {10.1063/1.2733292},
journal = {AIP Conference Proceedings},
number = 1,
volume = 899,
place = {United States},
year = {Mon Apr 23 00:00:00 EDT 2007},
month = {Mon Apr 23 00:00:00 EDT 2007}
}
  • The standard scenario of big bang nucleosynthesis (BBN) is generalized to take into account nonthermal nuclear reactions in the primordial plasma. These reactions are naturally triggered in the BBN epoch by fast particles generated in various exoergic processes. It is found that, although such particles can appreciably enhance the rates of some individual reactions, their influence on the whole process of element production is not significant. The nonthermal corrections to element abundances are obtained to be 0.1% ({sup 3}H), -0.03% ({sup 7}Li), and 0.34 %-0.63% (CNO group).
  • The possibility of describing available experimental data for the total cross sections of neutron radiative capture on {sup 8}Li at thermal and astrophysical energies was considered within the framework of the modified potential cluster model with the state classification of nuclear particles according to the Young tableaux. Our approach allows one to transmit available data in the energy range 0.1–1.0 MeV quite well, and predicts the behavior of the total cross sections at super-low energies, down to 25.3 × 10{sup −9} MeV.
  • Cross sections for the [sup 8]Li([ital d],[ital n])[sup 9]Be (ground state) and [sup 8]Li([ital d],[ital t])[sup 7]Li reactions, both important to primordial nucleosynthesis in the inhomogeneous models, have been measured using a radioactive beam technique. The cross section for the former reaction is found to be small, so it is important only for synthesis of [sup 9]Be. The cross section for the latter reaction, however, is found to be large enough to destroy significant quantities of [sup 8]Li, and thus could affect predictions of primordial nucleosynthesis yields.
  • One of the most prominent success with the Big Bang models is the precise reproduction of mass abundance ratio for {sup 4}He. In spite of the success, abundances of lithium isotopes are still inconsistent between observations and their calculated results, which is known as lithium abundance problem. Since the calculations were based on the experimental reaction data together with theoretical estimations, more precise experimental measurements may improve the knowledge of the Big Bang nucleosynthesis. As one of the destruction process of lithium-7, we have performed measurements for the reaction cross sections of the {sup 7}L({sup 3}He,p){sup 9}Be reaction.