Breakup Reaction Research Articles

The Breakup Cross Section of the D+D Reaction at 6.94 MeV

The D+D reactions are well known and widely used for a variety of purposes, mainly because of the use of the D(d , n )3 He reaction as a mono-energetic neutron source. The least studied of the D+D reactions is the D(d , n )pD reaction known as the deuteron breakup reaction, which produces a continuum of neutrons at energies below the monoenergetic peak. The neutron energy distribution as a function of angle for the cross section, , of the D(d ,n )pD reaction has been measured using a 6.94-MeV pulsed deuteron beam incident upon a D2 gas target. The time-of-flight technique was used to determine the energy of the neutrons detected in an array of two lithium glass scintillators and one NE-213 scintillator. The breakup cross section was determined as low as 225-keV neutron energy in the lithium glass detectors.

Experimental study of three-nucleon dynamics in the dp breakup collisions using the WASA detector

Until recently, all calculations of breakup observables were carried out in a non-relativistic regime. The relativistic treatment of the breakup reaction in 3 N system is quite a new achievement. The detailed study of various aspects of few-nucleon system dynamics in medium energy region, with a particular emphasis on investigation of relativistic effects and their interplay with three nucleon force (3NF) becomes feasible with increasing available energy in the three nucleon system. Therefore an experiment to investigate the \(^1\)H(d, pp)n breakup cross section using a deuteron beam of 300, 340, 380 and 400 MeV and the WASA detector has been performed at COSY-Julich. The almost 4\(\pi \) geometry of the WASA detector gives an unique possibility to study variety of kinematic configurations, which reveal different sensitivity to aspects of dynamics of the three nucleon system. The main steps of the analysis, including energy calibration, PID, normalization and efficiency studies, and their impact on the final accuracy of the result, are discussed.

Study of the 12C (8B, 7Be)X knockout reaction at intermediate energies

The breakup reactions of 8B on a 12C target at 142, 285, 790, and 936MeV/nucleon have been studied. One-proton-removal cross sections, leading to the production of 7Be fragments in the ground and first excited states (at 0.429MeV), and the longitudinal momentum distributions of the 7Be fragments are obtained in the Eikonal approximation of the Glauber Model. The results of the calculations including the contribution of the 7Be to the ground and first excited states of 8B are compared with the available experimental data. One-proton-removal cross section for the 12C(8B, 7Be)X knockout reaction at 142, 285, 790, and 936 MeV/nucleon energy has been calculated. 8B and 7Be cross sections and momentum distribution are in a good agreement with available data.

Spectra for theA= 6 reactions calculated from a three-body resonance model

We develop a resonance model of the transition matrix for three-body breakup reactions of the A = 6 system and present calculations for the nucleon observed spectra, which are important for inertial confinement fusion and Big Bang nucleosynthesis (BBN). The model is motivated by the Faddeev approach where the form of the T matrix is written as a sum of the distinct Jacobi coordinate systems corresponding to particle configurations (α , n -n ) and (n ; n -α) to describe the final state. The structure in the spectra comes from the resonances of the two-body subsystems of the three-body final state, namely the singlet (T = 1) nucleon-nucleon (NN ) anti-bound resonance, and the N α resonances designated the ground state (Jπ = ) and first excited state (Jπ = ) of the A = 5 systems 5 He and 5 Li. These resonances are described in terms of single-level, single-channel R -matrix parameters that are taken from analyses of NN and Nα scattering data. While the resonance parameters are approximately charge symmetric, external charge-dependent effects are included in the penetrabilities, shifts, and hard-sphere phases, and in the level energies to account for internal Coulomb differences. The shapes of the resonance contributions to the spectrum are fixed by other, two-body data and the only adjustable parameters in the model are the combinatorial amplitudes for the compound system. These are adjusted to reproduce the observed nucleon spectra from measurements at the Omega and NIF facilities. We perform a simultaneous, least-squares fit of the tt neutron spectra and the 3 He3 He proton spectra. Using these amplitudes we make a prediction of the α spectra for both reactions at low energies. Significant differences in the tt and 3 He3 He spectra are due to Coulomb effects.

Simulation of 3He(d,p) 4He reaction and recent results of the experimental investigation of dp breakup reaction

The feasibility study for the measurements of the polarization observables in the 3He(d,p) 4He reaction for DSS project using a part of the BM@N setup have been performed. Deuteron beam with energy of 1.5 GeV, magnet, 12 stations GEM tracker and TOF wall were used in simulations in order to obtain momentum resolution and to prove the separation of the secondary protons and deuterons. Summarized results of the dp breakup reactions with detection of two protons in coincidence for some kinematic configurations at energies from 300 to 500 MeV obtained in Nuclotron are presented.

Numerical assessment of post-prior equivalence for inclusive breakup reactions

We address the problem of the post-prior equivalence in inclusive breakup reactions induced by weakly-bound nuclei. The problem is studied within the DWBA model of Ichimura, Austern, Vincent [Phys. Rev. C32, 431 (1985)]. The post and prior formulas obtained in this model are briefly recalled, and applied to several breakup reactions induced by deuterons and $^6$Li projectiles, to test their actual numerical equivalence. The different contributions of the prior-form formula are also discussed. A critical comparison with the prior-form distorted-wave Born approximation (DWBA) model of Udagawa and Tamura [Phys. Rev. C24, 1348 (1981)] is also provided.

Dynamic Isovector Reorientation of Deuteron as a Probe to Nuclear Symmetry Energy.

We present the calculations on a novel reorientation effect of deuteron attributed to isovector interaction in the nuclear field of heavy target nuclei. The correlation angle determined by the relative momentum vector of the proton and the neutron originating from the breakup deuteron, which is experimentally detectable, exhibits significant dependence on the isovector nuclear potential but is robust against the variation of the isoscaler sector. In terms of sensitivity and cleanness, the breakup reactions induced by the polarized deuteron beam at about 100 MeV/u provide a more stringent constraint to the symmetry energy at subsaturation densities.

Design of experimental setup for elastic scattering and breakup reaction of 17F+58Ni

Design of experimental setup for elastic scattering and breakup reaction of 17F+58Ni

Role of breakup and direct processes in deuteron-induced reactions at low energies

Background: Recent studies of deuteron-induced reactions around the Coulomb barrier $B$ pointed out that numerical calculations for deuteron-induced reactions are beyond current capabilities. The statistical model of nuclear reactions was used in this respect since the compound-nucleus (CN) mechanism was considered to be responsible for most of the total-reaction cross section ${\ensuremath{\sigma}}_{R}$ in this energy range. However, specific noncompound processes such as the breakup (BU) and direct reactions (DR) should be also considered for the deuteron-induced reactions, making them different from reactions with other incident particles.Purpose: The unitary and consistent BU and DR consideration in deuteron-induced reactions is proved to yield results at variance with the assumption of negligible noncompound components.Method: The CN fractions of ${\ensuremath{\sigma}}_{R}$ obtained by analysis of measured neutron angular distributions in deuteron-induced reactions on $^{27}\mathrm{Al}$, $^{56}\mathrm{Fe}$, $^{63,65}\mathrm{Cu}$, and $^{89}\mathrm{Y}$ target nuclei, around $B$, are compared with the results of an unitary analysis of every reaction mechanism. The latter values have been supported by the previously established agreement with all available deuteron data for $^{27}\mathrm{Al}$, $^{54,56\ensuremath{-}58,\mathrm{nat}}\mathrm{Fe}$, $^{63,65,\mathrm{nat}}\mathrm{Cu}$, and $^{93}\mathrm{Nb}$.Results: There is a significant difference between the larger CN contributions obtained from measured neutron angular distributions and calculated results of an unitary analysis of every deuteron-interaction mechanism. The decrease of the latter values is mainly due to the BU component.Conclusions: The above-mentioned differences underline the key role of the breakup and direct reactions that should be considered explicitly in the case of deuteron-induced reactions.

Investigation of the Deuteron Breakup on Proton Target in the Forward Angular Region at 130 MeV

A set of differential cross-section data of the 1 H(d, pp)n breakup reaction at 130 MeV deuteron beam energy has been measured in the domain of very forward polar angles with the use of the Germanium Wall detector at the Forschungszentrum Julich. The data obtained for over 1000 kinematical points (112 geometries) are compared with the theoretical predictions based on various models of the three-nucleon (3N) dynamics. They comprise: the realistic nucleon-nucleon potentials alone or combined with the three-nucleon force (3NF), the coupled-channel calculations with the explicit treatment of the Δ-isobar excitation and finally, the potentials derived from chiral perturbation theory. In the part of the phase space studied, the Coulomb interaction between protons has a strong impact on the differential cross section of the breakup reaction. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest. In these regions the data are well reproduced exclusively by calculations which include the electromagnetic repulsion between protons. In spite of the dominance of the Coulomb force in the phase space studied, the contribution of 3NF effects is also observed.

Long-range dynamic polarization potentials forBe11projectiles onZn64

We investigate the effects of the long-range dynamic polarization (LRDP) potential, which consists of the Coulomb dipole excitation (CDE) potential and the long-range nuclear (LRN) potential, for the $^{11}\mathrm{Be}$ projectile on $^{64}\mathrm{Zn}$. To study these effects, we perform a ${\ensuremath{\chi}}^{2}$ analysis of an optical model including the LRDP potential as well as a conventional short-range nuclear (SRN) potential. To take these effects into account, we argue that both the CDE and LRN potentials are essential to explaining the experimental values of ${P}_{E}$, which is the ratio of the elastic scattering cross section to the Rutherford cross section. The Coulomb and nuclear parts of the LRDP potential are found to contribute to a strong absorption effect. Strong absorption occurs because the real part of the CDE and LRN potentials lowers the barrier, and the imaginary part of the CDE and LRN potentials removes the flux from the elastic channel in the $^{11}\mathrm{Be}+^{64}\mathrm{Zn}$ system. Finally, we extract the total reaction cross section ${\ensuremath{\sigma}}_{R}$ including the inelastic, breakup, and fusion cross sections. The contribution of the inelastic scattering by the first excited state at ${\ensuremath{\varepsilon}}_{\mathrm{x}}^{1\mathrm{st}}=0.32\phantom{\rule{4pt}{0ex}}\mathrm{MeV}\phantom{\rule{4pt}{0ex}}(1/{2}^{\ensuremath{-}})$ is found to be relatively large and cannot be ignored. In addition, our results are shown to agree quite well with the experimental breakup reaction cross section by using a fairly large radius parameter.

Transfer induced by core excitation within an extended distorted-wave Born approximation method

Background: Dynamic core-excitation effects have been found to be of importance in breakup reactions and may be of relevance when obtaining spectroscopic information from transfer reactions. Purpose: In this paper we extend the distorted-wave Born approximation (DWBA) formalism in order to allow for noncentral components in the core-core term appearing in the transition operator, which allows for dynamic core-excitation effects. Then we study these effects by applying the formalism to different (d,p) reactions. Methods: The expression of the nonlocal kernels required for the evaluation of the DWBA amplitudes has been extended so as to include noncentral parts in the core-core interaction. The DWBA scattering amplitude is then obtained by solving the corresponding inhomogeneous equation, with the new computed kernels, and the usual outgoing boundary conditions. A new DWBA code has been developed for this purpose. Results: For 10 Be(d,p) 11 Be, core-excitation effects are found to be almost negligible (<3%). The importance of this effect has been found to depend to a large extent on the excitation energy of the core. This has been confirmed in the 30 Ne(d,p) 31 Ne case, for which the excitation energy of the first 2 + state is 0.8 MeV, and the effect of core excitation increases to ≈10%. Conclusions: We find dynamic core-excitation effects in transfer reactions to have small contributions to cross sections, in general. However, they should not be neglected, since they may modify the spectroscopic information obtained from these reactions and may become of importance in reactions with nuclei with a core with high deformation and low excitation energy.

Coulomb barrier penetrability in the 11Be + 208Pb breakup reaction

We use the continuum discretized coupled channels method to study the 11Be+208Pb breakup reaction. We investigate the effects of the continuum–continuum couplings (ccc) on the breakup cross sections. We find that high partial waves strengthen the ccc. Using the breakup cross sections of this reaction, we analyze the penetrability of the Coulomb barrier and show that this penetrability is reduced when the ccc are included.

Experimental Investigation of Few-Nucleon Dynamics at Medium Energies

An experiment, with unpolarized deuteron beam of 160 MeV impinging on liquid hydrogen and liquid deuterium targets, was carried out using BINA detector at KVI, in Groningen, the Netherlands. Data were collected for the purpose of obtaining high precision differential cross-section for the deuteron break-up reaction. The elastic scattering data were also collected alongside. We present here the methods applied in analysis of data collected in the backward part of the detector.

Coulomb and nuclear components of the breakup, their interference and effect on the fusion process

We discuss reaction mechanisms involving weakly bound nuclei, at near barrier energies, and the couplings between different reaction channels. This paper may be thought as a brief description of state of the art of this field, particularly on breakup reactions and their influence on the fusion cross section. Recent experimental and theoretical results are presented, including the interference between Coulomb and nuclear components of the breakup and the systematics so far reached on the static effects due to the characteristic of weakly bound nuclei, especially halo-nuclei and the dynamic effects of the breakup coupling on the fusion cross section.

Analysis of orbital occupancy of valence neutron in 15C through Coulomb breakup reactions

The Coulomb breakup reactions 208Pb(15C, 14C + n)208Pb and 181Ta(15C, 14C + n)181Ta have been studied at 68 and 85 A MeV beam energies, respectively, within the framework of the eikonal approximation to investigate the orbital occupancy of valence neutron in the 15C nucleus. The outcomes of the present work favor 0+ ⊗ 2s1/2 as the core-neutron coupling for the ground-state structure with 0.91 as a spectroscopic factor.

Production and separation of astatine isotopes in the 7Li + natPb reaction

Production cross sections of astatine isotopes 207−211At in the 29–57 MeV 7Li + natPb reaction have been measured by α- and γ-ray spectrometry. Excitation functions of production cross sections have been compared with a statistical calculation to study the reaction mechanism of the 7Li + natPb reaction. Production reactions of 207−211At in the 7Li + natPb have been derived. Considerably small experimental cross sections of 210At and 209At compared with the statistical calculation were clearly observed at incident energies higher than 44 MeV, indicating that the effects of breakup reaction play a role. A chemical separation of astatine from an irradiated lead target has been studied with a dry-distillation method. A complementary way to produce astatine isotopes has been developed.

Coulomb Force Effects in Deuteron--Proton Breakup Reaction

A large set of cross-section data for the H-1 (d,pp)n breakup reaction was measured at 130 MeV deuteron beam energy with the Germanium Wall setup covering the range of very forward polar angles. In the investigated part of the phase-space, the dynamics is dominated by the Coulomb force influence. The data are compared with results of theoretical calculations based on the realistic Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The cross-section data reveal seizable Coulomb force effects.

Analysis of Orbital Occupancy of Valence Neutron in15C through Coulomb Breakup Reactions

Analysis of Orbital Occupancy of Valence Neutron in¹⁵C through Coulomb Breakup Reactions

Study of clustering structures through breakup reactions

Models for the description of breakup reactions used to study the structure of exotic cluster structures like halos are reviewed. The sensitivity of these models to the projectile description is presented. Calculations are sensitive to the projectile ground state mostly through its asymptotic normalisation coefficient (ANC). They also probe the continuum of the projectile. This enables studying not only resonant states of the projectile but also its non-resonant continuum both resonant and non-resonant. This opens the possibility to study correlations between both halo neutrons in two-neutron halo nuclei.