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Title: Structure of light neutron-rich nuclei probing separation energies

Abstract

Using Radioactive Ion Beams (RIB) new properties of neutron-rich nuclei near the border of stability have been investigated. Properties of these exotic nuclei near the drip line with Z up to 20 have been studied using the direct measurement of the mass of 31 radioactive nuclei at GANIL. The derivation of two-neutron separation energies have enabled to establish new neutron magic number N=6 and 16 in neutron-rich region for the first time instead of normal 8 and 20 and to support the non-existence of doubly magic nuclei 10He and 28O. Immense changes in basic properties of nuclear matter have been confirmed by novel two step fragmentation in-beam gamma ray spectroscopy that has established the 24O nucleus as a new doubly magic nucleus.

Authors:
; ;  [1]
  1. Nuclear Physics Institute, ASCR, CZ-250 68, Rez (Czech Republic)
Publication Date:
OSTI Identifier:
20798587
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 831; Journal Issue: 1; Conference: International conference on frontiers in nuclear structure, astrophysics, and reactions - FINUSTAR, Isle of Kos (Greece), 12-17 Sep 2005; Other Information: DOI: 10.1063/1.2200976; (c) 2006 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; GAMMA SPECTROSCOPY; GANIL CYCLOTRON; HELIUM 10; MAGIC NUCLEI; MASS NUMBER; NEUTRON SEPARATION ENERGY; NEUTRON-RICH ISOTOPES; NUCLEAR FRAGMENTATION; NUCLEAR MATTER; NUCLEAR STRUCTURE; OXYGEN 24; OXYGEN 28; RADIOACTIVE ION BEAMS

Citation Formats

Dlouhy, Z., Bayborodin, D., and Mrazek, J. Structure of light neutron-rich nuclei probing separation energies. United States: N. p., 2006. Web. doi:10.1063/1.2200976.
Dlouhy, Z., Bayborodin, D., & Mrazek, J. Structure of light neutron-rich nuclei probing separation energies. United States. doi:10.1063/1.2200976.
Dlouhy, Z., Bayborodin, D., and Mrazek, J. Wed . "Structure of light neutron-rich nuclei probing separation energies". United States. doi:10.1063/1.2200976.
@article{osti_20798587,
title = {Structure of light neutron-rich nuclei probing separation energies},
author = {Dlouhy, Z. and Bayborodin, D. and Mrazek, J.},
abstractNote = {Using Radioactive Ion Beams (RIB) new properties of neutron-rich nuclei near the border of stability have been investigated. Properties of these exotic nuclei near the drip line with Z up to 20 have been studied using the direct measurement of the mass of 31 radioactive nuclei at GANIL. The derivation of two-neutron separation energies have enabled to establish new neutron magic number N=6 and 16 in neutron-rich region for the first time instead of normal 8 and 20 and to support the non-existence of doubly magic nuclei 10He and 28O. Immense changes in basic properties of nuclear matter have been confirmed by novel two step fragmentation in-beam gamma ray spectroscopy that has established the 24O nucleus as a new doubly magic nucleus.},
doi = {10.1063/1.2200976},
journal = {AIP Conference Proceedings},
number = 1,
volume = 831,
place = {United States},
year = {Wed Apr 26 00:00:00 EDT 2006},
month = {Wed Apr 26 00:00:00 EDT 2006}
}
  • The variation of the two-neutron separation energy (S2N), as a function of N, is studied using a microscopic model that includes the pairing effects rigorously within the Fixed-Sharp-BCS method. The model has been tested for ''ordinary'' nuclei and has correctly reproduced the experimental data. The study has then been extended to the neutron-rich nuclei and has shown a relatively important variation of S2N when N= 100 which may be attributed to the existence of a new magic number.
  • No abstract prepared.
  • One-neutron knockout reactions from neutron-rich nuclei, with Z=6-13 and N=8-22, were studied at the Fragment Separator (GSI) at high beam energies, around 700 MeV/nucleon. Structural phenomena such as the formation of one-neutron halos in odd-mass carbon isotopes ({sup 15,17,19}C) will be discussed. In addition, one-neutron knockout measurements from {sup 22}N were carried out for the first time and demonstrate clearly the change from a 0d{sub 5/2} to a 1s{sub 1/2} orbital for the valence neutron, an effect that is expected above N=14 and that was also observed in {sup 23}O and {sup 24}F. The possibility of an anomalous structure ofmore » {sup 26}F, due to a significant 1s{sub 1/2} neutron admixture, will also be discussed in the light of the experimental data obtained in this work. Finally, the ground-state configuration of neutron-rich neon isotopes ({sup 24-28}Ne) was studied, providing new information in a region that is relatively close to the island of inversion.« less
  • A new method for calculating the low-lying states of light nuclei is proposed: Antisymmetrized Molecular Dynamics (AMD) - Superposition of Selected Snapshots (AMD triple-S). In addition to the cluster features of the core nucleus, the properties of the wave of valence nucleons are well expressed in terms of a superposition of selected AMD wave functions. For 6He, the binding energy and the halo nature are reproduced using effective interactions determined from a phase-shift analysis. For the deformed core cases, in 12Be, the newly observed J = 0 state at 2.24 MeV is analyzed to be the second 0+ state.
  • We systematically investigate the possibility that the s{sup 2} configuration of the two neutrons in the middle of the nucleus is a characteristic bond of {alpha}-clusters in light neutron-rich nuclei. The series of cluster states seen in {sup 10}Be(2{alpha}+2n) and {sup 14}C(3{alpha}+2n) is extended to the cases of heavier nuclei, {sup 18}O(4{alpha}+2n) and {sup 22}Ne(5{alpha}+2n), and we show the appearance of cluster structure with the s{sup 2} bond in the excited states by using a microscopic N{alpha}+2n model, in which the coupling with low-lying states is included.