17,319 research outputs found
Fragmentation of exotic oxygen isotopes
Abrasion-ablation models and the empirical EPAX parametrization of projectile fragmentation are described. Their cross section predictions are compared to recent data of the fragmentation of secondary beams of neutron-rich, unstable 19,20,21O isotopes at beam energies near 600 MeV/nucleon as well as data for stable 17,18O beams
Cluster structures in Oxygen isotopes
Cluster structure of 16O,18O and 20O is investigated by the antisymmettrized
molecular dynamics (AMD) plus generator coordinate method (GCM). We have found
the K^{\pi}=0 and 0 rotational bands of 18O that have the prominent
14C+\alpha cluster structure. Clustering systematics becomes richer in 20O. We
suggest the K^{\pi}=0 band that is the mixture of the 12C+\alpha+4n and
14C+6He cluster structures, and the K^{\pi}=0 band that has the 14C+6He
cluster structure. The K^{\pi}=0 and 0 bands that have the
prominent 16C+\alpha cluster structure are also found.Comment: 9pages, 9figure
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Oxygen isotopes in CO3 chondrites
Oxygen isotope analyses were undertaken on seven CO3 chondrites. No correlation was seen between metamorphic grade in CO3s and oxygen isotopic compositions. Results suggest that ALH77307 should be reclassified as a unique chondrite
Quenching of spectroscopic factors for proton removal in oxygen isotopes
We present microscopic coupled-cluster calculations of the spectroscopic
factors for proton removal from the closed-shell oxygen isotopes
O with the chiral nucleon-nucleon interaction at
next-to-next-to-next-to-leading order. We include coupling-to-continuum degrees
of freedom by using a Hartree-Fock basis built from a Woods-Saxon
single-particle basis. This basis treats bound and continuum states on an equal
footing. We find a significant quenching of spectroscopic factors in the
neutron-rich oxygen isotopes, pointing to enhanced many-body correlations
induced by strong coupling to the scattering continuum above the neutron
emission thresholds.Comment: 3 figure
Elastic and total reaction cross sections of oxygen isotopes in Glauber theory
We systematically calculate the total reaction cross sections of oxygen
isotopes, O, on a C target at high energies using the Glauber
theory. The oxygen isotopes are described with Slater determinants generated
from a phenomenological mean-field potential. The agreement between theory and
experiment is generally good, but a sharp increase of the reaction cross
sections from ^{21}O to ^{23}O remains unresolved. To examine the sensitivity
of the diffraction pattern of elastic scattering to the nuclear surface, we
study the differential elastic-scattering cross sections of proton-^{20,21,23}O
at the incident energy of 300 MeV by calculating the full Glauber amplitude.Comment: 9 pages, 8 figure
Radii and binding energies in oxygen isotopes: a puzzle for nuclear forces
We present a systematic study of both nuclear radii and binding energies in
(even) oxygen isotopes from the valley of stability to the neutron drip line.
Both charge and matter radii are compared to state-of-the-art {\it ab initio}
calculations along with binding energy systematics. Experimental matter radii
are obtained through a complete evaluation of the available elastic proton
scattering data of oxygen isotopes. We show that, in spite of a good
reproduction of binding energies, {\it ab initio} calculations with
conventional nuclear interactions derived within chiral effective field theory
fail to provide a realistic description of charge and matter radii. A novel
version of two- and three-nucleon forces leads to considerable improvement of
the simultaneous description of the three observables for stable isotopes, but
shows deficiencies for the most neutron-rich systems. Thus, crucial challenges
related to the development of nuclear interactions remain.Comment: 6 pages, 5 figures, Submitted to Nature Physics, April 12th 2016;
first version (v1 Arxiv) Internal Report Preprint Irfu-18 December 2015. 6
p., 5 fig., Submitted to Physical Review Letters, April 29, May 3rd 2016; 2nd
version. Int. Rep. Irfu-24 May 2016. Published in PRL, 27 July 2016 with the
modified title (Radii and binding energies in oxygen isotopes: a challenge
for nuclear forces
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Insight into the evolution of the Tagish Lake carbonaceous chondrite by analysis of the oxygen isotopic composition of extracted water and Mössbauer spectroscopy
Analysis of oxygen isotopes in water from Tagish Lake together with Mössbauer Spectroscopy suggest some similarities to the CI group of meteorites but also suggest differences in the extent of parent body hydrothermal alteration
Exploring Neutron-Rich Oxygen Isotopes with MoNA
The Modular Neutron Array (MoNA) was used in conjunction with a large-gap
dipole magnet (Sweeper) to measure neutron-unbound states in oxygen isotopes
close to the neutron dripline. While no excited states were observed in 24O, a
resonance at 45(2) keV above the neutron separation energy was observed in 23O.Comment: 6 pages, 4 Figures, submitted to Proc. Int. Conf. on Proton Emitting
Nuclei and Related Topics, PROCON0
On stability of the neutron rich Oxygen isotopes
Stability with respect to neutron emission is studied for highly
neutron-excessive Oxygen isotopes in the framework of Hartree-Fock-Bogoliubov
approach with Skyrme forces Sly4 and Ska. Our calculations show increase of
stability around 40O.Comment: 5 pages, 3 figure
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