Search results for "Breakup"
showing 10 items of 50 documents
Study of Cluster Structures in Nuclei through the Ratio Method. A Tribute to Mahir Hussein
2020
For one-neutron halo nuclei, the cross sections for elastic scattering and breakup at intermediate energy exhibit similar angular dependences. The Recoil Excitation and Breakup (REB) model of reactions elegantly explains this feature. It also leads to the idea of a new reaction observable to study the structure of loosely-bound nuclear systems: the Ratio. This observable consists of the ratio of angular distributions for different reaction channels, viz. elastic scattering and breakup, which cancels most of the dependence on the reaction mechanism; in particular it is insensitive to the choice of optical potentials that simulate the projectile-target interaction. This new observable is very…
Sensitivity of one-neutron knockout of halo nuclei to their nuclear structure
2019
Halo nuclei are located far from stability and exhibit a very peculiar structure. Due to their very short lifetime, they are often studied through reactions. Breakup reactions are of particular interest since their cross sections are large for these loosely-bound nuclei. Inclusive measurements of breakup--also called knockout reactions--have even higher statistics. In this proceeding, we study which nuclear-structure information can be inferred from the parallel-momentum distribution of the core of one-neutron halo nuclei after the knockout of its halo neutron. In particular, we analyse the influence of the ground-state wavefunction, the presence of excited states within the halo-nucleus sp…
Adolescent Depressive Symptoms and Breakup Distress During Early Emerging Adulthood
2017
Breakups are a normative and frequent part of the romantic experience. In this longitudinal study, we followed 144 adolescents (mean age = 16.57) for a period of 4 years and examined the extent to which level of depressive symptoms predicts the intensity of breakup distress during emerging adulthood and, further, the extent to which breakup distress reported during emerging adulthood is associated with the quality of a current romantic relationship. The findings suggest that higher levels of depressive symptoms during adolescence can lead to more difficulty in recovering from breakup in early emerging adulthood. In addition, experiencing greater breakup distress during emerging adulthood w…
Au nanowire junction breakup through surface atom diffusion.
2018
Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200 degrees C, 400 degrees C, 600 degrees C and 700 degrees C) during a time period of 10 min. We show that nanowires are especially prone to fragmentatio…
Universality for the breakup of invariant tori in Hamiltonian flows
1998
In this article, we describe a new renormalization-group scheme for analyzing the breakup of invariant tori for Hamiltonian systems with two degrees of freedom. The transformation, which acts on Hamiltonians that are quadratic in the action variables, combines a rescaling of phase space and a partial elimination of irrelevant (non-resonant) frequencies. It is implemented numerically for the case applying to golden invariant tori. We find a nontrivial fixed point and compute the corresponding scaling and critical indices. If one compares flows to maps in the canonical way, our results are consistent with existing data on the breakup of golden invariant circles for area-preserving maps.
Formation and Evolution of Nanoscale Metal Structures on ITO Surface by Nanosecond Laser Irradiations of Thin Au and Ag Films
2012
The effect of nanosecond laser irradiations on 5 nm thick sputter-deposited Au and Ag films on Indium-Tin-Oxide surface is investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). After 500, 750, and 1000 mJ/cm 2 fluence irradiations, the breakup of the Au and Ag films into nanoscale islands is observed as a consequence of fast melting and solidification processes. The mean nanoparticles size and surface density are quantified, as a function of the laser fluence, by the AFM and SEM analyses. In particular, the comparison between the Au and Ag islands reveals the formation of larger islands in the case of Ag for each fixed fluence. The mechanism of the nanoscale …
Simulating core excitation in breakup reactions of halo nuclei using an effective three-body force
2022
We extend our previous calculation of the breakup of 11Be using Halo Effective Field Theory and the Dynamical Eikonal Approximation to include an effective 10Be-n-target force. The force is constructed to account for the virtual excitation of 10Be to its low-lying 2+ excited state. In the case of breakup on a 12C target this improves the description of the neutron-energy and angular spectra, especially in the vicinity of the 11Be 5/2+ state. By fine-tuning the range parameters of the three-body force, a reasonable description of data in the region of the 3/2+ 11Be state can also be obtained. This sensitivity to the three-body force's range results from the structure of the overlap integral …
Reliable extraction of the dB(E1)/dE for 11Be from its breakup at 520 MeV/nucleon
2019
We analyze the breakup of the one-neutron halo nucleus 11Be measured at 520 MeV/nucleon at GSI on Pb and C targets within an eikonal description of the reaction including a proper treatment of special relativity. The Coulomb term of the projectile-target interaction is corrected at first order, while its nuclear part is described at the optical limit approximation. Good agreement with the data is obtained using a description of 11Be, which fits the breakup data of RIKEN. This solves the apparent discrepancy between the dB(E1)/dE estimations from GSI and RIKEN for this nucleus.
Final State Three-Body Coulomb Effects in thePb208(B8,Be7p)Pb208Coulomb Breakup Reaction
2003
We present results of the first calculation of the double differential cross section for the 208Pb(8B,(7)Bep)208Pb Coulomb breakup reaction which treats the postdecay acceleration of the ejectiles within a genuine three-body approach. From this we conclude that, in order to minimize postdecay Coulomb acceleration effects, experiments should be performed at as small as possible scattering angles, not too low 7Be-p relative energies, and high incident energy.
Three-Body Coulomb Effects in the Direct Coulomb Breakup of 8B into 7Be + p in the Field of a 208Pb Ion
1999
The amplitude for the Coulomb breakup of a light nucleus in the field of a highly charged ion is considered in the framework of the distorted wave approach, with particular emphasis being laid on correctly taking into account the three-body Coulomb interactions in the final state. Numerical calculations have been performed for the double differential cross section for the reaction 208Pb(8B, 7Be p)208Pb. They clearly demonstrate the importance of long-range three-body Coulomb correlations in the astrophysically interesting regime when the ejectiles have the extremely small relative energies.