Breakup Effects Research Articles

Breakup dynamics in 6Li elastic scattering with four-body and three-body CDCC

We have investigated projectile breakup effects on 6Li + 209Bi elastic scattering near the Coulomb barrier with the four-body and three-body continuum-discretized coupled- channels methods. In the analysis, the elastic scattering is well described by the p + n + 4He + 209Bi four-body model. Four-body dynamics of the elastic scattering is precisely investigated and we then found that d (p + n) in 6Li may hardly break up during the scattering.

Viscous Drop Breakage in Liquid–Liquid Stirred Dispersions: Population Balance Modeling

The breakup of viscous drops in a turbulent regime is a challenging area of research. In this study, the population balance equation is used for modeling of the drop size distribution of emulsification systems in stirred tank. The suitability of various fluid particle breakage closures in the literature is investigated for the prediction of experimental data obtained from emulsification of silicone oils with four different viscosities. Systems with breakup of dispersed-phase drops of high viscous grades call for an improved model framework that allows the breakage closures to adjust correctly for the effect of viscosity. This is particularly required for systems of higher viscosities where the complex effects of viscous breakup are more pronounced.

Antihalo effects on reaction cross sections forC14,15,16isotopes

We study anti-halo effects on reaction cross sections $\sigma_{\rm R}$ for $^{14,15,16}$C scattering from a $^{12}$C target at 83~MeV/nucleon, using the $g$-matrix double-folding model. $^{15}$C is described by the $^{14}$C~+~$n$ two-body model that reproduces the measured large s-wave spectroscopic factor, i.e., the shell inversion that the 1s$_{1/2}$ orbital is lower than the 0d$_{5/2}$ orbital in energy. $^{16}$C is described by the $^{14}$C~+~$n$~+~$n$ three-body model with the phenomenological three-body force (3BF) that explains the measured small s-wave spectroscopic factor. The 3BF allows the single-particle energies of the $^{14}$C + $n$ subsystem to depend on the position $r$ of the second neutron from the center of mass of the subsystem. The 1s$_{1/2}$ orbital is lower than the 0d$_{5/2}$ orbital for large $r$, but the shell inversion is restored for small $r$. Anti-halo effects due to the "partial shell inversion" make $\sigma_{\rm R}$ for $^{16}$C smaller than that for $^{15}$C. We also investigate projectile breakup effects on the mass-number dependence of $\sigma_{\rm R}$ with the continuum discretized coupled-channels method.

Systematic study of breakup effects on complete fusion at energies above the Coulomb barrier

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 function which is used as a uniform standard reference. The complete fusion cross sections at energies above the Coulomb barrier are suppressed by the breakup of projectiles. This suppression effect for reactions induced by the same projectile is independent of the target and mainly determined by the lowest energy breakup channel of the projectile. A good exponential relation between the suppression factor and the energy corresponding to the lowest breakup threshold is held.

Fusion, breakup and scattering of weakly bound nuclei

We discuss the systematic results reached in the investigation of the breakup of weakly bound nuclei, at near barrier energies, and its effects on fusion cross sections, elastic scattering and reaction cross sections. Particularly we show that the complete fusion of weakly bound systems are suppressed by dynamic breakup effects at energies above the Coulomb barrier and enhanced at sub-barrier energies. We also show that the energy dependence of the optical potential obtained in the elastic scattering of weakly bound projectiles corresponds to the so-called Breakup Threshold Anomaly (BTA).

The fate of the weakly-bound ψ(2s) in nuclear matter

We present new results of a completed PHENIX analysis of $\psi(2s)$ modification at midrapidity in 200 GeV $d+$Au collisions. Strong suppression of the $\psi(2s)$ relative to the $J/\psi$ is observed. This difference in suppression is too strong to be explained by breakup effects in the nucleus, due to the short nuclear crossing times at RHIC. Given the observation of long range correlations in $p(d)+$A collisions at LHC and RHIC, consistent with hydrodynamics, these observations raise interesting questions about the mechanism of $\psi(2s)$ suppression when it is produced in a nuclear target. In 2012, the PHENIX Collaboration installed the FVTX, a silicon tracker that precisely measures muon pair opening angles prior to any multiple scattering in the muon arm absorber, and thus provides an improved dimuon mass resolution. The FVTX allows the $\psi(2s)$ to be separated from the $J/\psi$ at forward and backward rapidity for the first time at RHIC. We present new results on $\psi(2s)$ production in $p+p$ collisions at $\sqrt{s} = 510$ GeV from the 2013 data set.

Electromigration Induced Break-up Phenomena in Liquid Metal Printed Thin Films

Room temperature liquid metal (RTLM)-related electronics has recently been found increasingly important in a wide variety of emerging areas. In particular, printable liquid metal ink opens the way for direct writing of electronics spanning form microscale to even nanoscale. However, such fluid-like circuits also raised important fundamental as well as practical issues for solving. A big issue facing its future large-scale application is that the failure features of the conductive wires under electrical current densities are not clear. Here, we discovered for the first time that a liquid metal thin film would be broken by the so-called electromigration effect as the applied current increases to a critical magnitude. A theoretical model was established to preliminarily interpret the phenomena and the related effects. The break-up effect in the liquid metal-based circuits could be one of the major hurdles that must be tackled with caution in the research and application of future liquid metal technologies, especially for the printed microelectronics thus enabled.

Fission fragment angular distributions inLi6,7+U235,238reactions

Fission fragment (FF) angular distributions for ${}^{6,7}\mathrm{Li}+^{235,238}\mathrm{U}$ reactions have been measured at energies near and above the Coulomb barrier. The angle integrated fission cross sections for $^{6}\mathrm{Li}$ induced reactions at sub-barrier energies are found to be higher than $^{7}\mathrm{Li}$ induced reactions possibly due to a larger contribution of breakup or transfer induced fission in cases of the former compared to the latter. The FF anisotropies for $^{6,7}\mathrm{Li}+^{235}\mathrm{U}$ are found to be slightly smaller than $^{6,7}\mathrm{Li}+^{238}\mathrm{U}$, manifesting the effect of target spin. The statistical saddle point model predictions underestimate the measured FF anisotropy for all four systems at measured energies. Anisotropy calculation by entrance channel dependent $K$-state distribution model and determination of $\ensuremath{\langle}{\ensuremath{\ell}}^{2}\ensuremath{\rangle}$ from continuum discretized coupled channels calculations suggest that the above enhancement in experimental anisotropy is due to a combined effect of entrance channel dependent pre-equilibrium fission and projectile breakup induced fission.

Elastic scattering andαproduction in theBe9+Y89system

Elastic scattering measurement for the $^{9}\mathrm{Be}+^{89}\mathrm{Y}$ system has been carried out at near-barrier energies with the aim of investigating the effect of breakup on the elastic channel. The energy dependence of the optical model potential for the system gives an indication of the breakup threshold anomaly (BTA) for the system. An overall repulsive real part of the dynamic polarization potential (DPP) generated due to continuum couplings using the $\ensuremath{\alpha}+^{5}\mathrm{He}$ cluster structure for $^{9}\mathrm{Be}$ is consistent with the BTA behavior observed for the system. In contrast, an attractive real part of the DPP, at all energies, is observed for similar calculations carried out using the $^{8}\mathrm{Be}+n$ cluster structure. Coupling of the 1$n$ transfer channel in addition to continuum couplings does not have a significant effect on the elastic scattering angular distributions. The experimental 1$n$ transfer cross sections show better agreement with the corresponding values obtained using the $^{8}\mathrm{Be}+n$ cluster structure calculations. Inclusive breakup-$\ensuremath{\alpha}$ cross sections are observed to form a large fraction of the reaction cross sections, especially at below-barrier energies, suggesting the dominance of the breakup channel at these energies. This also supports the BTA behavior observed for the system, reflected as the presence of a reaction channel and thus the persistence of the imaginary potential at below-barrier energies.

Influence of carbonate content of marls used in dams: Geotechnical and statistical characterization

The relationships between geotechnical parameters identified from tests of slake durability, swelling behavior, soil dispersion, and consolidation, using samples of marls utilized to build impervious cores of Spanish dams, were analyzed. The analyses have determined the incidence of the processes of internal erosion and piping, self-stability, strength, durability (behavior during dry–wet cycles) and their variation with the carbonate content of marls.A total of 118 samples were selected from marl quarries used for the construction of three impervious cores of dams. The carbonate content of the samples varied from less than 10% to more than 70%. The type and amount of clay also varied. The results show that the carbonate content alters the short-term to medium-term cohesion of soils by the effect of possible cementation and break-up. The medium–low correlation indexes found in this work (although acceptable) are due to the complex mechanics of the durability and dispersibility phenomenons.

Observation of a breakup-inducedα-transfer process for some bound states ofO16populated by theC12(Li6,d)O16*reaction

Background: The ${}^{12}\mathrm{C}{(}^{6}\mathrm{Li},d)$ reaction has been used as an indirect method to calculate the astrophysical $S$ factor for the $^{12}\mathrm{C}$($\ensuremath{\alpha},\ensuremath{\gamma})$ reaction at Gamow energy (300 keV).Purpose: The ${}^{12}\mathrm{C}{(}^{6}\mathrm{Li},d)$ reaction is usually interpreted in terms of direct transfer. In this work we investigate the reaction mechanism and determine the effects of breakup on transfer and therefore on the extracted spectroscopic amplitudes.Method: The deuteron angular distributions for the ${}^{12}\mathrm{C}{{(}^{6}\mathrm{Li},d)}^{16}{\mathrm{O}}^{*}$has been measured at 20 MeV, populating discrete states of $^{16}\mathrm{O}$. continuum discretized coupled channel-coupled reaction channel (CDCC-CRC) calculations have been used to analyze the data.Results: Results show a new reaction mechanism, where transfer occurs after the breakup of the loosely bound $^{6}\mathrm{Li}$ in the population of some bound states of $^{16}\mathrm{O}$. A comparison of the CDCC-CRC calculations with respect to the measured data were used to determine the $\ensuremath{\alpha}$ spectroscopic amplitudes and factors for the different states of $^{16}\mathrm{O}$. Using the spectroscopic amplitudes obtained in this work, the $E2$ $S$ factor for the $^{12}\mathrm{C}$($\ensuremath{\alpha}$,$\ensuremath{\gamma}$) reaction has been calculated in the framework of a two-body potential model and compared to measurements.Conclusions: The present study very clearly shows that the breakup and transfer coupling effects are strong in the ${}^{12}\mathrm{C}{(}^{6}\mathrm{Li},d)$ reaction. The present work extracts, in the framework of a coupled reaction channel theory, the spectroscopic amplitudes of the bound and unbound states of $^{16}\mathrm{O}$. All previous analysis and new measurements should therefore be reexamined from this viewpoint to extract the astrophysical observables correctly.

Four-body effects in the [formula omitted] scattering

We present angular distributions of the He6+Ni58 scattering measured at three bombarding energies above the Coulomb barrier: Elab=12.2 MeV,16.5 MeV,and 21.7 MeV. The angular distributions have been analysed in terms of three- and four-body Continuum-Discretized Coupled-Channels calculations considering the effect of the 6He breakup. A behaviour in the cross section at large angles has been observed which was reproduced only by the four-body Continuum-Discretized Coupled-Channels calculation.

Modeling and CFD‐PBE simulation of an airlift bioreactor for PHB production

ABSTRACTIn the present attempt, a 3D simulation using a commercially available computational fluid dynamics package (FLUENT 6.3.26), and a metabolic model were used to investigate hydrodynamics and production of polyhydroxybutyrate (PHB) in an airlift bioreactor, performed by Tavares et al. (L. Z. Tavares, E. S. da Silva, J. G. C. Pradella. Biochem. Eng. J., 2004; 18, 21–31). An Eulerian approach was applied to model the gas–liquid interactions. In order to account for the combined effect of bubble breakup and coalescence in the bioreactor, a population balance model implemented in the software was used. Biosynthesis of PHB in the bioreactor was examined and maximum forward reaction rate values of thiolase, reductase, and synthase steps were determined as V1(thiolase) = 1.8 mM/min, V1(reductase) = 400 mM/min, and V1(synthase) = 380 mM/min to predict the experimental PHB production rate by Tavares et al. suitably. A simplified reaction was considered for PHB production. Moreover, gas holdup, liquid velocity vectors, shear stress, and volumetric oxygen transfer coefficient were investigated. Also, molar concentration profiles of PHB and glucose within the bioreactor were obtained. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.

Analyses of spray break-up mechanisms using the integral form of the conservation equations

We present further uses of a theoretical framework based on the integral form of the conservation equations, to gain insight and predictive capabilities for the spray break-up regimes, turbulence effect on drop size, and secondary break-up processes. Quantitatively and qualitatively, the results indicate that the current analysis method can be useful in understanding and predicting various aspects of spray break-up processes. Correct Weber number boundaries for Rayleigh, wind-induced, and atomisation regimes are calculated using a Weber-Reynolds number relationship obtained from first principles. Good agreements with experimental data for turbulence and secondary break-up effects on the drop size are also achieved. It is projected that small modifications of the source terms within this framework can render possible analyses of other important processes, such as swirl sprays and air-blast atomisation.

Measurement of Li+Sn fusion excitation functions around the Coulomb barrier using an improved activation technique

Fusion excitation functions have been measured for the 6 Li+120 Sn and 7 Li+119 Sn systems at energies around the Coulomb barrier, to investigate the effects of neutron transfer and breakup on the fusion process. At energies above the barrier, a suppression of the complete fusion excitation function with respect to the prediction of the 1D - Barrier Penetration Model has been observed, in both cases. At energies below the Coulomb barrier, no significant difference between the two excitation function, imputable to the different neutron transfer Q-values of the two systems has been observed.

A Unified Model Considering Effects of Droplet Break-Up and Air Entrainment at the Initial Stage of Fuel Spray Penetration

This paper proposes a new unified single model that considers droplet break-up and air entrainment impact on three flow regimes (namely, Stokes, Allen, and Newton) in the initial stage of fuel spray penetration. Homotopy perturbation method was used to obtain semianalytical solutions of unified single model on diesel fuel’s spray penetration when the influence of air entrainment is small (up to 0.1-0.2 ms after the start of injection). It is demonstrated that the applied analytical method is very straightforward in comparison with existing techniques. Furthermore, it is decidedly effectual in terms of accuracy and rapid convergence. The formulation of the problem is presented in the text as well as the analytical and numerical procedures.

Analysis of 6Li Scattering at 600 MeV

The elastic and inelastic scattering of 6 Li on 12 C, 58 Ni, 90 Zr, and 208 Pb targets at 600 MeV are analyzed via double-folding optical model potentials based on the S1Y effective nucleon-nucleon (NN) interaction and tρρ approx- imation. Information is provided, by single- and coupled- channel calculations, on the effect of breakup and its feedback on the elastic scattering of 6 Li ions. Experimental results are successfully reproduced. The in-medium NN cross-section and second-order (double-scattering) correction to the t ρρ potential are taken into account. Reaction cross-sections are computed from exact and approximate solutions.

Deformation effects in the Coulomb breakup of 31Ne

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 the one-neutron separation energy of 31Ne and also argue that if 31Ne is indeed a halo nucleus then it should be a deformed one.

Generation of multicolor vacuum ultraviolet pulses through four-wave sum-frequency mixing in argon

We demonstrate efficient generation of multicolor vacuum ultraviolet pulses with excellent mode quality through ${\ensuremath{\chi}}^{(3)}$-based four-wave sum-frequency mixing and third-order harmonic generation of 400- and 267-nm femtosecond laser pulses in argon gas. The ${\ensuremath{\chi}}^{(3)}$-based nonlinear optical processes were optimized with appropriate control of gas pressure and group velocity delay between the driving pulses. Furthermore, the pulse breakup effects were observed for tightly focused ultraviolet pulses.

Elastic scattering and fusion cross-sections in 7Li + 27Al reaction

With an aim to understand the effects of breakup and transfer channels on elastic scattering and fusion cross-sections in the 7Li + 27Al reaction, simultaneous measurement of elastic scattering angular distributions and fusion cross-sections have been carried out at various energies (E lab = 8.0–16.0 MeV) around the Coulomb barrier. Optical model (OM) analysis of the elastic scattering data does not show any threshold anomaly or breakup threshold anomaly behaviour in the energy dependence of the real and imaginary parts of the OM potential. Fusion cross-section at each bombarding energy is extracted from the measured α-particle evaporation energy spectra at backward angles by comparing with the statistical model prediction. Results on fusion cross-sections from the present measurements along with data from the literature have been compared with the coupled-channels predictions. Detailed coupled-channels calculations have been carried out to study the effect of coupling of breakup, inelastic and transfer, channels on elastic scattering and fusion. The effect of 1n-stripping transfer coupling was found to be significant compared to that of the projectile breakup couplings in the present system.