18,207 research outputs found
Inclusive breakup calculations in angular momentum basis: application to Li+Ni
The angular momentum basis method is introduced to solve the inclusive
breakup within the model proposed by Ichimura, Austern, and Vincent [Phys. Rev.
C 32, 431 (1985)]. This method is based on the geometric transformation between
Jacobi coordinates, thus it is easy to corporate with particle spins. To test
the validity of this partial wave expansion method, a benchmark calculation is
done comparing with the one given in [Phys. Rev. C 92, 044616 (2015)]. Using
the distorted-wave Born approximation (DWBA) version of IAV model, some
applications to Li reactions are presented and compared with available
data
Comprehensive analysis of large yields observed in Li induced reactions
Background: Large yields have been reported over the years in
reactions with Li and Li projectiles. Previous theoretical analyses
have shown that the elastic breakup (EBU) mechanism (i.e., projectile breakup
leaving the target in its ground state) is able to account only for a small
fraction of the total inclusive breakup cross sections, pointing
toward the dominance of non-elastic breakup (NEB) mechanisms.
Purpose: We aim to provide a systematic study of the inclusive cross
sections observed in nuclear reactions induced by Li projectiles. In
addition to estimating the total singles cross sections, it is our
goal to evaluate angular and energy distributions of these particles
and compare with experimental data, when available.
Method: We compute separately the EBU and NEB components of the inclusive
breakup cross sections. For the former, we use the continuum-discretized
coupled-channels (CDCC) method, which treats this mechanism to all orders. For
the NEB part, we employ the the model proposed in the eighties by Ichimura,
Austern and Vincent [Phys. Rev. C32, 432 (1982)], within the DWBA
approximation.
Results: Overall, the sum of the computed EBU and NEB cross sections is found
to reproduce very well the measured singles cross sections. In all cases
analyzed, we find that the inclusive breakup cross section is largely dominated
by the NEB component.
Conclusions: The presented method provides a global and systematic
description of inclusive breakup reactions induced by Li projectiles. It
provides also a natural explanation of the previously observed underestimation
of the measured yields by CDCC calculations. The method used here can
be extended to other weakly-bound projectiles, including halo nuclei.Comment: 11 pages, 16 figures, fig. 12 updated; some typos correcte
The puzzle of complete fusion suppression in weakly-bound nuclei: a Trojan Horse effect?
Experimental studies of nuclear collisions involving light weakly-bound
nuclei show a systematic suppression of the complete fusion cross section by
30\% with respect to the expectation for tightly bound nuclei, at
energies above the Coulomb barrier. Although it is widely accepted that the
phenomenon is related to the weak binding of these nuclei, the origin of this
suppression is not fully understood. In here, we present a novel approach that
provides the complete fusion for weakly bound nuclei and relates its
suppression to the competition between the different mechanisms contributing to
the reaction cross section. The method is applied to the Li+Bi
reactions, where we find that the suppression of complete fusion is mostly
caused by the flux associated with non-elastic breakup modes, such as the
partial capture of the projectile (incomplete fusion), whereas the elastic
breakup mode is found to play a minor role. Finally, we demonstrate that the
large yields observed in these reactions can be naturally explained as
a consequence of a {\it Trojan Horse} mechanism.Comment: 6 pages, 4 figures. Accepted for publication in Phys. Rev. Letter
The Minimum Spectral Radius of Graphs with the Independence Number
In this paper, we investigate some properties of the Perron vector of
connected graphs. These results are used to characterize that all extremal
connected graphs with having the minimum (maximum) spectra radius among all
connected graphs of order with the independence number ,
respectively.Comment: 28 pages, 3 figure
Puzzle of Complete Fusion Suppression in Weakly Bound Nuclei: A Trojan Horse Effect?
Experimental studies of nuclear collisions involving light weakly bound nuclei show a systematic suppression of the complete fusion cross section by ∼30% with respect to the expectation for tightly bound nuclei, at energies above the Coulomb barrier. Although it is widely accepted that the phenomenon is related to the weak binding of these nuclei, the origin of this suppression is not fully understood. Here, we present a novel approach that provides the complete fusion for weakly bound nuclei and relates its suppression to the competition between the different mechanisms contributing to the reaction cross section. The method is applied to the 6,7Li+209Bi reactions, where we find that the suppression of complete fusion is mostly caused by the flux associated with nonelastic breakup modes, such as the partial capture of the projectile (incomplete fusion), whereas the elastic breakup mode is found to play a minor role. Finally, we demonstrate that the large α yields observed in these reactions can be naturally explained as a consequence of a Trojan Horse mechanism.National Science Foundation under Contract No. NSF-PHY-1520972 with Ohio UniversityMinisterio de Ciencia,Innovación y Universidades (Projects No. FIS2014-53448-C2-1-P and No. FIS2017-88410-P)European Union’s Horizon 2020 (Grant Agreement No. 654002
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