5669748
Four-body DWBA calculations of the Coulomb breakup of 6He
Abstract We investigate the Coulomb breakup of the two-neutron-halo nucleus 6 He by extending the framework of the finite-range postform distorted-wave Born approximation theory introduced earlier for the description of the breakup of one-neutron-halo nuclei. The model can use the realistic three-body wave function for the 6 He ground state. Calculations have been performed for energy, total and parallel momentum distributions of 4 He fragment. The two-body 4 He–neutron and neutron–neutron correlations have also been calculated. Our results are compared with those of an adiabatic model of the Coulomb-breakup reactions. The two theories lead to almost identical results. Comparisons are also made with the available experimental data. It is found that the pure Coulomb breakup can describe the bulk of the data taken at below grazing angles. However, a rigorous description of all the available data requires the consideration of the nuclear-breakup effects.
7640769
Spectroscopy of one-neutron halo nuclei from the Coulomb breakup reactions 1
We review the current status of obtaining the spectroscopic information on the one-neutron halo nuclei from the Coulomb breakup reactions. The theory of these reactions formulated in the framework of the Distorted Wave Born Approximation, allows the use of the realistic wave functions corresponding to any orbital angular momentum structure for the corevalence neutron relative motion in the ground state of the projectile. The energy, angular and parallel momentum distributions of the projectile fragments calculated within this theory are selective about the ground state wave function of the projectile. Therefore, firm conclusions can be drawn about the structure of the projectile ground state by comparing the calculations with the corresponding data.
119331365
Full quantal theory of one-neutron halo breakup reactions
We present a theory of one-neutron halo breakup reactions within the framework of post-form distorted wave Born approximation wherein pure Coulomb, pure nuclear and their interference terms are treated consistently in a single setup. This formalism is used to study the breakup of one-neutron halo nucleus 11Be on several targets of different masses. We investigate the role played by the pure Coulomb, pure nuclear and the Coulomb-nuclear interference terms by calculating several reaction observables. The Coulomb-nuclear interference terms are found to be important for more exclusive observables.
14239070
Electric and magnetic response to the continuum for A = 7 isotopes in a dicluster model
Mirror isotopes 7 Li and 7 Be are investigated in a dicluster model. The magnetic dipole moments and the magnetic dipole response to the continuum are calculated in this framework. The magnetic contribution is found to be small with respect to electric dipole and quadrupole excitations even at astrophysical energies, at a variance with the case of deuteron. Energy weighted molecular sum rules are evaluated and a formula for the molecular magnetic dipole sum rule is found which matches the numerical calculations. Cross-sections for photo-dissociation and radiative capture as well as the S-factor for reactions of astrophysical significance are calculated with good agreement with known experimental data. 1 Dicluster description of 7 Be and 7 Li It is well known that the properties of A = 7 mass nuclei may be effectively described in terms of a dicluster model: two (inert) clusters in interaction with each other (1; 2; 3). A long-standing description of these nuclei with such a di-cluster picture has achieved excellent results and a continued interest because it catches the essential physics within a very simple, yet powerful, model. Such a simple nuclear structure scheme may then used in reaction calculations (4). The need to go beyond this level of description may be justified only with the aim of taking into account more refined considerations on the role of the Pauli principle or on the occurrence of complex phenomena like polarization of the clusters, not because the model itself does not reproduce static and dynamic properties of A = 7 nuclei to a good degree of accuracy. For example ab ini-tio shell model calculations using a computationally heavy Monte Carlo method have successfully reproduced many properties of these and other light nuclei starting from a nucleon-nucleon interaction (5). By computing ground state overlap functions, these calculations have shown that 7 Be have a spectroscopic factor of almost 1 in the α+ 3 He configuration and, similarly, 7 Li has a large spectroscopic factor in the α + t channel. A number of other approaches, that we will not discuss here, such as Resonating Group Methods or Generator Coordinates Methods, are available to various degrees of complication and success. We must mention a very recent study by Canton and Levchuk on the low-energy capture reactions (6) using the Multichan-nel Algebraic Scattering approach that has been applied to the 3 He(α, γ) 7 Be reaction at astrophysical energies achieving …
3170000
Breakup Reactions of Drip Line Nuclei
The formal theory of breakup reactions is reviewed. The direct breakup mechanism which is formulated within the framework of the post form distorted wave Born approximation is discussed in detail. In this theory, which requires the information about only the ground state wave function of the projectile, the fragment-target interactions are included to all orders while fragment-fragment interaction is treated only in the first order. The general applicability of this theory to describe the breakup of halo nuclei is demonstrated by comparing the calculations with data for total, as well as energy and angle integrated cross sections and momentum distributions of fragments in reactions induced by a number of halo nuclei. We investigate the role played by the pure Coulomb, pure nuclear and the Coulomb-nuclear interference terms. Postacceleration effects in the Coulomb breakup of neutron halo nuclei is also studied.
118382420
Role of higher multipole excitations in the electromagnetic dissociation of one-neutron halo nuclei
Abstract.We investigate the role of higher multipole excitations in the electromagnetic dissociation of one-neutron halo nuclei within two different theoretical models --a finite-range distorted-wave Born approximation and another in a more analytical method with a finite-range potential. We also show, within a simple picture, how the presence of a weakly bound state affects the breakup cross-section.
59152734
Probing Supersymmetry using Event Shape variables at 8 TeV LHC
We have revisited the prospects of Supersymmetry(SUSY) searches at the LHC with 7 TeV energy along with the prediction of the discovery potential at 8 TeV energy assuming an integrated luminosity 5 $fb ^{-1}$ and 20 $\invfb$ with mSUGRA/CMSSM as a model framework. We discuss further optimization of our selection strategy which is based on the hadronic event shape variables. Evaluating the standard model backgrounds and signal rates in detail we predict the discovery reach in the $m_0 - m_{1/2}$ plane for 7 TeV with 5$\invfb$ luminosity. We also present the discovery reach for 8 TeV energy with an integrated luminosity 5$\invfb$ and 20 $\invfb$. A comparison is made between our results and the exclusion plots obtained by CMS and ATLAS. Finally, discovery reach in the gluino and squark mass plane at the 7 TeV and 8 TeV energy is also presented.