9 pages, 6 figures; To be published in J. Phys. Soc. Jpn. Vol.78, No.8. More detailed discussion on the vanishment of the nuclear-Coulomb interference at 0 degrees, new typeset using JPSJ style file
The dependence of breakup cross sections of 8B at 65 MeV/nucleon on the target mass number A_T is investigated by means of the continuum-discretized coupled-channels method (CDCC) with more reliable distorting potentials than those in the preceding study. The A_T^(1/3) scaling law of the nuclear breakup cross section is found to be satisfied only in the middle A_T region of 40 < A_T < 150. The interference between nuclear and Coulomb breakup amplitudes vanishes in very forward angle scattering, independently of the target nucleus. The truncation of the relative energy between the p and 7Be fragments slightly reduces the contribution of nuclear breakup at very forward angles, while the angular region in which the first-order perturbation theory works well does not change essentially.
A detailed study of total, Coulomb and nuclear breakup cross sections dependence on the projectile ground-state binding energy $\varepsilon_b$ is presented, by considering the $^8$Li+$^{12}$C and $^8$Li+$^{208}$Pb breakup reactions. To this end, apart from the experimental one-neutron separation energy of $^8$Li nucleus ($\varepsilon_b=2.03$~MeV), lower values of $\varepsilon_b$ down to $\varepsilon_b=0.01$~MeV, are also being considered. It is shown that all breakup processes become peripheral as $\varepsilon_b\to 0.01$ MeV, which is understood as due to the well-known large spacial extension…
The breakup of $^8$B on $^{58}$Ni below the Coulomb barrier was measured recently with the aim of determining the Coulomb breakup components. We reexamine this reaction, and perform one step quantum-mechanical calculations that include E1, E2 and nuclear contributions. We show that the nuclear contribution is by no means negligible at the intermediate angular range where data was taken. Our results indicate that, for an accurate description of this reaction, Coulomb E1, E2 and nuclear processes all have to be taken into account.
A new method for calculating the Coulomb breakup of unstable neutron-rich isotopes at high energies is presented. The calculations employ the eikonal approximation and use a new Coulomb dynamical polarization potential (CDPP), calculated by solving the Schrödinger equation for the entire motion of the exotic projectile as a two-body cluster structure using the adiabatic approximation and incorporating excitations to the continuum. Calculations for some exotic isotopes are compared with Coulomb dissociation cross section data and found to be in good agreement.
The breakup of the $^{9}$Be projectile on the $^{209}$Bi target at bombarding energies above and near the Coulomb barrier is studied in the adiabatic two-center shell model approach. The effect of $^{9}$Be$% \to $n$+2α$ breakup channel on complete fusion, elastic and inelastic cross sections is investigated. Results show that the breakup of the projectile $^{9}$Be could be due to a molecular single-particle effect shortly before the colliding nuclei reach the Coulomb barrier.
Within the post-form distorted wave Born approximation wherein pure Coulomb, pure nuclear and their interference terms are treated consistently in a single setup we study the beam energy dependence of the Coulomb-nuclear interference terms in the breakup of 11Be on a medium mass 44Ti target. Our results suggest that the Coulomb-nuclear interference terms are dependent on the incident beam energy and can be as big as that of the individual Coulomb or nuclear terms depending on the angle and energy of the breakup fragments. We also calculate the relative energy spectra and one-neutron removal cr…
We extend our approach to incorporate the proton-proton (pp) Coulomb force into the three-nucleon (3N) Faddeev calculations from elastic proton-deuteron (pd) scattering to the breakup process. The main new ingredient is a 3-dimensional screened pp Coulomb t-matrix obtained by a numerical solution of the 3-dimensional Lippmann-Schwinger equation. We demonstrate numerically that the proton-deuteron breakup observables can be determined from the resulting on-shell 3N amplitudes increasing the screening radius. However, contrary to the pd elastic scattering, the screening limit exists only after r…
The mechanism of the Coulomb breakup reactions of the nuclei with neutron-halo structure is investigated in detail. A time-dependent Schrödinger equation for the halo neutron is numerically solved by treating the Coulomb field of a target as an external field. The momentum distribution and the post-acceleration effect of the final fragments are discussed in a fully quantum mechanical way to clarify the limitation of the intuitive picture based on the classical mechanics. The theory is applied to the Coulomb breakup reaction of $^{11}$Be + $^{208}$Pb. The breakup mechanism is found to be differ…
The Coulomb-nuclear interference is studied as a function of the projectile ground-state binding energy in the 8Li + 12C and 8Li + 208Pb breakup reactions, by considering an arbitrary range for the 8Li ground-state binding energies εb, varying from the experimental one 2.03 MeV down to 0.01 MeV. Regardless the target mass, we first show that the Coulomb breakup cross section is stronger dependent on εb than the nuclear breakup cross section, due to the long-range nature of the Coulomb forces and to the electromagnetic transition matrix elements. For example, in case of 8Li + 208Pb reaction at …
An accurate treatment of Coulomb breakup reactions is presented by using both the Gaussian expansion method and the method of continuum discretized coupled channels. As $L^2$-type basis functions for describing bound- and continuum-states of a projectile, we take complex-range Gaussian functions, which form in good approximation a complete set in a large configuration space being important for Coulomb-breakup processes. Accuracy of the method is tested quantitatively for $^{8}{\rm B}+^{58}$Ni scattering at 25.8 MeV.
We investigate projectile breakup effects on 6Li+209Bi elastic scattering near the Coulomb barrier with the four-body version of the continuum-discretized coupled-channel method (four-body CDCC). This is the first application of four-body CDCC to 6Li elastic scattering. The elastic scattering is well described by the p+n+4He+209Bi four-body model. We propose a reasonable three-body model for describing the four-body scattering, clarifying four-body dynamics of the elastic scattering.
The Coulomb interaction between the two protons is included in the calculation of proton-deuteron breakup and of three-body electromagnetic disintegration of ${}^3\mathrm{He}$. The hadron dynamics is based on the purely nucleonic charge-dependent (CD) Bonn potential and its realistic extension CD Bonn + $Δ$ to a coupled-channel two-baryon potential, allowing for single virtual $Δ$-isobar excitation. Calculations are done using integral equations in momentum space. The screening and renormalization approach is employed for including the Coulomb interaction. Convergence of the procedure is found…
Total (complete + incomplete) fusion excitation functions of $^{6,7}$Li on $^{59}$Co and $^{209}$Bi targets around the Coulomb barrier are obtained using a new continuum discretized coupled channel (CDCC) method of calculating fusion. The relative importance of breakup and bound-state structure effects on total fusion is particularly investigated. The effect of breakup on fusion can be observed in the total fusion excitation function. The breakup enhances the total fusion at energies just around the barrier, whereas it hardly affects the total fusion at energies well above the barrier. The dif…
The eikonal description of breakup reactions diverges because of the Coulomb interaction between the projectile and the target. This divergence is due to the adiabatic, or sudden, approximation usually made, which is incompatible with the infinite range of the Coulomb interaction. A correction for this divergence is analysed by comparison with the Dynamical Eikonal Approximation, which is derived without the adiabatic approximation. The correction consists in replacing the first-order term of the eikonal Coulomb phase by the first-order of the perturbation theory. This allows taking into accou…
Comparing the capture cross sections calculated without the breakup effect and experimental complete fusion cross sections, the breakup was analyzed in reactions with weakly bound projectiles $^{6,7,9}$Li, $^{9,11}$Be, and $^{6,8}$He. A trend of a systematic behavior for the complete fusion suppression as a function of the target charge and bombarding energy is not achieved. The quasielastic backscattering is suggested to be an useful tool to study the behavior of the breakup probability in reactions with weakly bound projectiles.
We accurately analyze the $^6$He+$^{209}$Bi scattering at 19 and 22.5 MeV near the Coulomb barrier energy, using the continuum-discretized coupled-channels method (CDCC) based on the $n$+$n$+$^4$He+$^{209}$Bi four-body model. The three-body breakup continuum of $^6$He is discretized by diagonalizing the internal Hamiltonian of $^6$He in a space spanned by the Gaussian basis functions. The calculated elastic and total reaction cross sections are in good agreement with the experimental data, while the CDCC calculation based on the di-neutron model of $^6$He, i.e., the $^2n$+$^{4}$He+$^{209}$Bi t…
Coulomb breakup strengths of 11Li into a three-body 9Li+n+n system are studied in the complex scaling method. We decompose the transition strengths into the contributions from three-body resonances, two-body ``10Li+n'' and three-body ``9Li+n+n'' continuum states. In the calculated results, we cannot find the dipole resonances with a sharp decay width in 11Li. There is a low energy enhancement in the breakup strength, which is produced by both the two- and three-body continuum states. The enhancement given by the three-body continuum states is found to have a strong connection to the halo struc…
The cross sections for the ($^8$B,$^7$Be-$p$) breakup reaction on $^{58}$Ni and $^{208}$Pb targets at the beam energies of 25.8 MeV and 415 MeV have been calculated within a one-step prior-form distorted-wave Born approximation. The relative contributions of Coulomb and nuclear breakup of dipole and quadrupole multipolarities as well as their interference have been determined. The nuclear breakup contributions are found to be substantial in the angular distributions of the $^7$Be fragment for angles in the range of 30$^\circ$ - 80$^\circ$ at 25.8 MeV beam energy. The Coulomb-nuclear interferen…
The problem of Coulomb breakup in the scattering of a two-body loosely bound projectile by a heavy target is addressed. A basis of transformed harmonic oscillator (THO) wave functions is used to discretize the projectile continuum and to diagonalize the Hamiltonian of the two-body system. Results for the reaction $^{8}$B+$^{58}$Ni at subcoulomb energies are presented. Comparison of different observables with those obtained with the standard Continuum Discretized Coupled-Channels (CDCC) method shows good agreement between both approaches.
We show how to derive nuclear structure information on loosely bound nuclei far from the beta stability line from their Coulomb dissociation into the continuum. The 19C -> 18C + n process is taken as an example and it is shown that basic properties such as ground-state spin and parity and the neutron binding energy of the halo nucleus 19C can be derived from a comparison of theoretical calculations to experimental data.
We investigate dissociation reactions of loosely bound and spatially extended three-body systems. We formulate a practical method for simultaneous treatment of long-range Coulomb and short-range nuclear interactions. We use $^6$He (n+n+$α$) and $^{11}$Li (n+n+$^{9}$Li) as examples and study the two-neutron separation cross sections as functions of target and beam energy. Individual Coulomb and nuclear as well as interference contributions are also extracted.
The Coulomb-breakup method to extract the cross section for neutron radiative capture at astrophysical energies is analyzed in detail. In particular, its sensitivity to the description of the neutron-core continuum is ascertained. We consider the case of 14C(n, $γ$)15C for which both the radiative capture at low energy and the Coulomb breakup of 15C into 14C+n on Pb at 68 MeV/nucleon have been measured with accuracy. We confirm the direct proportionality of the cross section for both reactions to the square of the asymptotic normalization constant of 15C observed by Summers and Nunes [Phys. Re…
We derive closed expressions for the nuclear breakup cross sections in the adiabatic limit using the Austern-Blair theory. These expressions are appropriate for the breakup of weakly bound nuclei. The concept of an exit doorway that mediates the coupling between the entrance channel and the breakup continuum is used. We prove the validity of the scaling law that dictates that the nuclear breakup cross section scales linearly with the radius of the target. We also compare our results for the nuclear breakup cross section of $^{11}$Be, $^8$B on several targets with recent CDCC calculation.
Various measurements of the Coulomb breakup of 8B are analyzed within the dynamical eikonal approximation using a single description of 8B. We obtain a good agreement with experiment for different observables measured between 40 and 80 MeV per nucleon. A simple 7Be-p potential model description of 8B seems sufficient to describe all observables. In particular, the asymmetry in parallel-momentum distributions due to E1-E2 interferences is well reproduced without any scaling. The projectile-target nuclear interactions seem negligible if data are selected at forward angles. On the contrary, like …
We propose a new method to describe three-body breakups of nuclei, in which the Lippmann-Schwinger equation is solved combining with the complex scaling method. The complex-scaled solutions of the Lippmann-Schwinger equation (CSLS) enables us to treat boundary conditions of many-body open channels correctly and to describe a many-body breakup amplitude from the ground state. The Coulomb breakup cross section from the 6He ground state into 4He+n+n three-body decaying states as a function of the total excitation energy is calculated by using CSLS, and the result well reproduces the experimental …
All possible dissociation cross sections for the loosely bound three-body halo nuclei $^6$He (n+n+$α$) and $^{11}$Li (n+n+$^{9}$Li) are computed as functions of target and beam energy. Both Coulomb and nuclear interactions are included in the same theoretical framework. The measurements agree with the calculations for energies above 100 Mev/nucleon. The largest cross sections correspond to final states with zero or three particles for heavy and with two neutrons for light targets.
In this paper we present all-order quantum mechanical calculations of 7Be breakup on heavy (208Pb) and light (12C) targets. We examine the issues concerning the extraction of the astrophysical S-factor from the breakup data. We discuss the interplay between Coulomb and nuclear breakup, and the importance of higher-order couplings on the cross section. We show that nuclear and Coulomb contributions are not separable using the standard angular selection criterion as nuclear breakup remains large for small scattering angles, even for the heavy target. However, by selecting an upper limit on the r…
Coulomb breakup of a projectile in the Coulomb field of a fully stripped heavy nucleus is at present one of the most popular experimental methods to obtain information on reactions of interest in nuclear astrophysics. Its theoretical interpretation presents, however, considerable difficulties, due to the three-body nature and the infinite range of the Coulomb forces involved. Among the uncertainties affecting present analyses, the possible modification of the dissociation cross section by three-body Coulomb final-state interactions plays a major role. Various methods which have been proposed t…
Breakup cross sections are determined for the Borromean nucleus 22C by using a four-body eikonal model, including Coulomb corrections. Bound and continuum states are constructed within a 20C + n + n three-body model in hyperspherical coordinates. We compute continuum states with the correct asymptotic behavior through the R-matrix method. For the n+ n potential, we use the Minnesota interaction. As there is no precise experimental information on 21C, we define different parameter sets for the 20C + n potentials. These parameter sets provide different scattering lengths, and resonance energies …
Based on an approach recently proposed by us, simultaneous $χ^{2}$-analyses are performed for elastic scattering, direct reaction (DR) and fusion cross sections data for the $^{6}$He+$^{209}$Bi system at near-Coulomb-barrier energies to determine the parameters of the polarization potential consisting of DR and fusion parts. We show that the data are well reproduced by the resultant potential, which also satisfies the proper dispersion relation. A discussion is given of the nature of the threshold anomaly seen in the potential.
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 core-valence 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 pr…
The recent experimental data on Coulomb breakup of the nucleus $^{31}$Ne are interpreted in terms of deformation. The measured large one-neutron removal cross-section indicates that the ground state of $^{31}$Ne is either s- or p-halo. The data can be most easily interpreted as the spin of the ground state being 3/2$^-$ coming from either the Nilsson level [330 1/2] or [321 3/2] depending on the neutron separation energy $S_n$. However, the possibility of 1/2$^{+}$ coming from [200 1/2] is not excluded. It is suggested that if the large ambiguity in the measured value of $S_n$ of $^{31}$Ne, 0.…
We calculate the cross sections of the elastic and inelastic breakup modes for the inclusive breakup reaction $^{28}$Si($^8$B,$^7$Be) at beam energies between 10 - 40 MeV/nucleon within a direct fragmentation model formulated in the framework of the post form distorted-wave Born-approximation. In contrast to the case of the stable isotopes, the inelastic breakup mode is found to contribute only upto 30% to the total breakup cross section, which is in agreement with the recently measured experimental data. However, the high energy tail of the energy spectra of $^7$Be fragment is dominated by th…
Purpose : The aim of this paper is to study the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb to give us a core of $^{33}$Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of $^{34}$Na. Method : A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb at 100 MeV/u. The triple differential cross-section calculated fo…
We investigate the Coulomb breakup of neutron rich nuclei 11Be and (19,17,15)C within a theory developed in the framework of Distorted Wave Born Approximation. Finite range effects are included by a local momentum approximation, which allows incorporation of realistic wave functions for these nuclei in our calculations. Energy and angular as well as parallel momentum distributions of the fragments emitted in the breakup of these nuclei on heavy targets have been calculated using several structure models for their ground state. Comparison with the available experimental data shows that the resu…
The elastic and alpha-production channels for the 6He+208Pb reaction are investigated at energies around the Coulomb barrier (E_{lab}=14, 16, 18, 22, and 27 MeV). The effect of the two-neutron transfer channels on the elastic scattering has been studied within the Coupled-Reaction-Channels (CRC) method. We find that the explicit inclusion of these channels allows a simultaneous description of the elastic data and the inclusive alpha cross sections at backward angles. Three-body Continuum-Discretized Coupled-Channels (CDCC) calculations are found to reproduce the elastic data, but not the trans…
The triple differential cross section of $^{208}\rm{Pb}(^6\rm{Li};α,\rm{d})^{208}\rm{Pb}$ elastic Coulomb breakup is calculated using the semiclassical method. We fit the parameters of the Woods-Saxon potential using the experimental $α-\rm{d}$ phase shifts for different states to describe the relative motion of $α$-particle and deuteron. In order to check the validity of the two particle approach for $α-d$ system we apply a potential model to describe the $^2\rm{H}(α,γ)^6\rm{Li}$ radiative capture. Our results for the Coulomb breakup of $^6\rm{Li}$ show large value of the forward-backward asy…
Within a theory of breakup reactions formulated in the framework of the post form distorted wave Born approximation, we calculate contributions of the pure Coulomb and the pure nuclear breakup as well as those of their interference terms to a variety of cross sections in breakup reactions of the one-neutron halo nucleus $^{11}$Be on a number of target nuclei. In contrast to the assumption often made, the Coulomb-nuclear interference terms are found to be non-negligible in case of exclusive cross sections of the fragments emitted in this reaction on medium mass and heavy target nuclei. The cons…
We investigate the three-body Coulomb breakup of a two-neutron halo nucleus $^{11}$Li. We use the coupled-channel $^9$Li + $n$ + $n$ three-body model, which includes the coupling between last neutron states and the various $2p$-$2h$ configurations in $^9$Li due to the tensor and pairing correlations. The three-body scattering states of $^{11}$Li are described by using the combined methods of the complex scaling and the Lippmann-Schwinger equation. The calculated breakup cross section successfully reproduces the experiments. The large mixing of the s-state in the halo ground state of $^{11}$Li …
The breakup of 11Be on carbon and lead targets around 70 MeV/nucleon is investigated within a semiclassical framework. The role of the 5/2+ resonance is analyzed in both cases. It induces a narrow peak in the nuclear-induced breakup cross section, while its effect on Coulomb breakup is small. The nuclear interactions between the projectile and the target is responsible for the transition toward this resonant state. The influence of the parametrization of the 10Be-n potential that simulates 11Be is also addressed. The breakup calculation is found to be dependent on the potential choice. This le…
We investigate the Coulomb breakup of the two-neutron halo nucleus 6He by extending the framework of the finite range post form 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 6He ground state. Calculations have been performed for energy, total and parallel momentum distributions of 4He fragment. The two-body 4He-neutron and neutron-neutron correlations have also been calculated. Our results are compared with those of an adiabatic model of the Coulomb brea…
We have performed CDCC calculations for the $^{6}$Li + $^{59}$Co, $^{144}$Sm and $^{208}$Pb systems, to investigate the dependence of the relative importance of nuclear and Coulomb breakup on the target charge (mass) at near barrier energies. The calculations were in good agreement with the experimental elastic scattering angular distributions for these systems and then, their predictions to the nuclear, Coulomb and total breakup were investigated. Although the relative importance of the nuclear breakup is, as expected, larger for lighter targets, this effect is not very pronounced. We also in…
Within the pure Coulomb breakup mechanism, we investigate the one-neutron removal reaction of the type A(a,b$γ$)X with $^{11}$Be and $^{19}$C projectiles on a heavy target nucleus $^{208}$Pb at the beam energy of 60 MeV/nucleon. Our intention is to examine the prospective of using these reactions to study the structure of neutron rich nuclei. Integrated partial cross sections and momentum distributions for the ground as well as excited bound states of core nuclei are calculated within the finite range distorted wave Born approximation as well as within the adiabatic model of the Coulomb breaku…
A large number of complete fusion excitation functions of reactions including the breakup channel were measured in recent decades, especially in the last few years. It allows us to investigate the systematic behavior of the breakup effects on the complete fusion cross sections. To this end, we perform a systematic study of the breakup effects on the complete fusion cross sections at energies above the Coulomb barrier. The reduced fusion functions F(x) are compared with the universal fusion functions which are used as a uniform standard reference. The complete fusion cross sections at energies …
We use a three-body Continuum Discretized Coupled Channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term, and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation, and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li + 208…
Nuclear and Coulomb breakup of halo nuclei have been treated often as incoherent processes and structure information have been extracted from their study. The aim of this paper is to clarify whether interference effects and Coulomb-nuclear couplings are important and how they could modify the simple picture previously used. We calculate the neutron angular and energy distributions by using first order perturbation theory for the Coulomb amplitude and an eikonal approach for the nuclear breakup. This allows for a simple physical interpretation of the results which are mostly analytical. Our for…
The Coulomb dissociation method to obtain the astrophysical S-factor, $S_{17}(0)$, for the $^7$Be($p,γ)^8$B reaction at solar energies is investigated by analysing the recently measured data on the breakup reaction $^{208}$Pb$(^8$B,$^7$Be$~p)^{208}$Pb at 46.5 MeV/A beam energy. Breakup cross sections corresponding to E1, $E2$ and $M1$ transitions are calculated with a theory of Coulomb excitation that includes the effects of the Coulomb recoil as well as relativistic retardation. The interplay of nuclear and Coulomb contributions to the breakup process is studied by performing a full quantum m…
We propose a fully quantum-mechanical method of treating four-body nuclear breakup processes in scattering of a projectile consisting of three constituents, by extending the continuum-discretized coupled-channels method. The three-body continuum states of the projectile are discretized by diagonalizing the internal Hamiltonian of the projectile with the Gaussian basis functions. For $^6$He+$^{12}$C scattering at 18 and 229.8 MeV, the validity of the method is tested by convergence of the elastic and breakup cross sections with respect to increasing the number of the basis functions. Effects of…
Absorbing boundary condition approach to nuclear breakup reactions is investigated. A key ingredient of the method is an absorbing potential outside the physical area, which simulates the outgoing boundary condition for scattered waves. After discretizing the radial variables, the problem results in a linear algebraic equation with a sparse coefficient matrix, to which efficient iterative methods can be applicable. No virtual state such as discretized continuum channel needs to be introduced in the method. Basic aspects of the method are discussed by considering a nuclear two-body scattering p…
This paper gives new insight to the study of dynamical effects in proton breakup as compared to neutron breakup from a weakly bound state in an exotic nucleus. Following our recent work [Ravinder Kumar and Angela Bonaccorso, Phys. Rev. C84 014613 (2011)] there has been some discussion in the literature [B. Paes, J. Lubiana, P.R.S. Gomes, V. Guimarães, Nucl. Phys. A890 1 (2012); Y. Kucuk and A. M. Moro, Phys. Rev. C86 034601 (2012)], thus in order to clarify and asses quantitatively which mechanism would dominate measured observables, we study here several reaction mechanisms separately but als…
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.
We study dynamical effects in proton breakup from a weakly bound state in an exotic nucleus on a heavy target. The Coulomb interactions between the proton and the core and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton nuclear and Coulomb breakup is compared to that of an equiva- lent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. A number of experimentally measurable observables such as parallel momentum distributions, p…
We present a fully quantum mechanical theory to study the effects of deformation on various reaction observables in the Coulomb breakup of neutron rich exotic medium mass nuclei on heavy targets within the framework of finite range distorted wave Born approximation by using a deformed Woods-Saxon potential. As an application of this theory, we calculate the one-neutron removal cross section, relative energy spectra, parallel momentum distributions and angular distributions in the breakup of 31Ne on Pb and Au targets at 234 MeV/u. We suggest ways to put constraints on the large uncertainty in t…
We investigate the nuclear and the Coulomb contributions to the breakup cross sections of $^6$Li in collisions with targets in different mass ranges. Comparing cross sections for different targets at collision energies corresponding to the same $E/V_{\mathrm{\scriptscriptstyle B}}$, we obtain interesting scaling laws. First, we derive an approximate linear expression for the nuclear breakup cross section as a function of $A_{\mathrm{% \scriptscriptstyle T}}^{1/3}$. We then confirm the validity of this expression performing CDCC calculations. Scaling laws for the Coulomb breakup cross section a…
The open issues in the development of models for the breakup of exotic nuclei and the link with the extraction of structure information from experimental data are reviewed. The question of the improvement of the description of exotic nuclei within reaction models is approached in the perspective of previous analyses of the sensitivity of these models to that description. Future developments of reaction models are suggested, such as the inclusion of various channels within one model. The search for new reaction observables that can emphasise more details of exotic nuclear structure is also prop…
The optical potential of halo and weakly bound nuclei has a long range part due to the coupling to breakup that damps the elastic scattering angular distributions. In order to describe correctly the breakup channel in the case of scattering on a heavy target, core recoil effects have to be taken into account. We show here that core recoil and nuclear breakup of the valence nucleon can be consistently taken into account. A microscopic absorptive potential is obtained within a semiclassical approach and its characteristics can be understood in terms of the properties of the halo wave function an…
We study the eikonal model for the nuclear-induced breakup of Borromean nuclei, using Li11 and He6 as examples. The full eikonal model is difficult to realize because of six-dimensional integrals, but a number of simplifying approximations are found to be accurate. The integrated diffractive and one-nucleon stripping cross sections are rather insensitive to the neutron-neutron correlation, but the two-nucleon stripping does show some dependence on the correlation. The distribution of excitation energy in the neutron-core final state in one-neutron stripping reactions is quite sensitive to the …
