Breakup Effects Research Articles

Elastic scattering of 7Li+58Ni: a phenomenological and microscopic analysis

Motivating by examining the break-up effect of 7Li projectile into t + α cluster structure in the field of 58Ni nucleus, the available experimental angular distributions for 7Li + 58Ni elastic scattering system at energies ranging from 13 and up to 42 MeV are studied utilizing different phenomenological as well as microscopic potentials. Data analysis utilizing the Sao Paulo potential revealed that in order to reproduce the data, the strength of the real folded potential had to be reduced by ~ 36 %. While, data analysis utilizing the double folding CDM3Y6 potential with and without the rearrangement term revealed that the potential strength needed to be reduced by ~ 63 and 62 %, respectively. Cluster folding model based on the t + α cluster structure for 7Li is applied to reproduce the considered data. Similar results were obtained showing the necessity to reduce real cluster folding potential strength by about 49 %. The reported reduction in potential strength from the different implemented potentials supports the strong 7Li break-up impact. Finally, the full microscopic continuum discretized coupled channels approach is applied with a great success in reproducing the considered data. 

Analysis of elastic scattering angular distributions and fusion excitation functions of reactions induced by 9Be on 27Al, 28Si, 144Sm and 208Pb targets at near barrier energies

The elastic scattering angular distributions and the fusion excitation function data for the reactions induced by the loosely bound projectile 9Be on [Formula: see text]Al, [Formula: see text]Si, [Formula: see text]Sm and [Formula: see text]Pb targets at near and above barrier energies have been analyzed with a motive to investigate the importance of breakup couplings within the framework of continuum discretized coupled channels approach. It is found that at energies much higher than Coulomb barrier, the breakup effects are insignificant for light targets while for heavy targets, the breakup effects play a dominant role at these energies. But at energies comparable to the barrier height, the role of breakup becomes crucial for light mass targets also.

Numerical Simulation of Bubble Size Distribution in Single Snorkel Furnace (SSF) with Population Balance Model (PBM)

Single Snorkel Furnace (SSF) vacuum refining furnace is a novel external refining equipment for high clean steel production. RH is a molten steel refining technology developed by Rheinstahl-Heraeus company. Compared with the traditional RH furnace, the SSF furnace has the advantages of a simple structure, high refining efficiency, and low production cost. However, because the upward flow and the downward flow are in a single snorkel, the flow phenomenon is more complex than that in the RH device. Therefore, the gas–liquid two-phase flow law in SSF furnaces plays an important role in improving equipment efficiency and accurate control. In addition, the evolution and movement behavior of bubbles have an important influence on the two-phase flow. In this study, the Population Balance Model (PBM) model is employed to study the bubble properties, taking into account the effect of bubble coalescence and breakup on the flow field. The simulation results with this model are consistent with the experimental values, and the comparison with the results of the model without the PBM is revealed to be closer with less error. The results show that with the PBM model the flow field is more homogeneously distributed, the flow velocity is more stable, and the area distribution of the upward flow and downward flow in the snorkel is more symmetrical. In the case of this study, as the fluid level rises, the bubble diameter will increase due to the decrease in hydrostatic pressure.

Numerical study on liquid ammonia direct injection spray characteristics under engine-relevant conditions

This paper reports on CFD modeling of the fuel/air mixing characteristics of liquid ammonia under direct injection engine-relevant conditions. Several questions are addressed including, whether the widely used Lagrange particle tracking (LPT) spray models developed for traditional fossil fuels are suitable for ammonia spray, whether certain improvement of the current models should be introduced, and under what conditions the improvement of models needs to be considered. It is found that liquid ammonia spray characteristics can be well reproduced by the current Lagrange-based spray models under non-flash boiling conditions. However, there are obvious gaps between measurements and predictions under strong flash boiling conditions. A strong flash boiling region is found near the nozzle while its intensity decreases downstream due to the significant cooling effect of ammonia spray, and initial superheat degree defined as the ratio of ambient pressure to the saturation vapor pressure at initial fuel temperature, can be adopted to determine the boundary of flash boiling model that needs to be employed in the modeling of liquid ammonia spray. Spray included angle is a crucial parameter within the LPT simulation framework to reproduce the collapse effect for multi-plume sprays. The flash model considering only the evaporation promotion effect cannot replicate the ammonia spray characteristics and it does not result in obvious differences compared with the results from the normal evaporation model. Liquid ammonia is a thermal sensitive fuel and has a strong tendency of flash boiling, and a more accurate flash boiling model that considers the thermal breakup effect should be proposed to accurately predict ammonia fuel/air mixing characteristics under wide engine-relevant conditions.

Coparenting as a mediator between physical custody arrangements and children's mental health.

The detrimental effects of parental break-up on children's mental health are well-documented. However, research has also shown that children living in joint physical custody (JPC) arrangements often fare better than children living in sole physical custody (SPC) arrangements. Thus, the question arises: What are the differences between JPC and SPC that account for those results? Drawing on data from the Family Models in Germany (FAMOD) study conducted in 2019, structural equation models (SEM) were estimated to deduct the mediating role of coparenting support in children's mental health in 465 JPC and 652 SPC families with children aged 2-14. The findings suggest that the better mental health observed among children in JPC families than among children in SPC families was fully mediated by coparenting support. However, this held true only for internalizing and externalizing behavior, but not for prosocial behavior as no differences between JPC and SPC were found for this dimension. The findings affirm the importance of supportive coparenting for children's well-being after family dissolution in both SPC and JPC arrangements. After breaking up, parents should be supported in their parental engagement through coparenting counseling or psychoeducation classes.

Breakup corrections to the He3 beam polarization measurements at the future BNL Electron Ion Collider

Requirements for hadron polarimetry at the future Electron-Ion Collider (EIC) include measurements of absolute ${}^3\text{He} (h)$ beam polarization with systematic uncertainties better than $\sigma^\text{syst}_P/P\lesssim1\%$. Due to the successful use, since 2005, of the polarized hydrogen jet target polarimeter (HJET) to measure proton beam polarization at the Relativistic Heavy Ion Collider (RHIC), the HJET technique promises to be suitable for the ${}^3\text{He}$ polarimetry at EIC. For that, however, one needs to know the ratio of the $h^\uparrow{p}$ and $p^\uparrow{h}$ analyzing powers. For elastic scattering, this ratio can be evaluated with sufficient accuracy if $p^\uparrow{p}$ analyzing power is precisely known. In this paper, the deuteron beam data acquired at HJET in RHIC Run 16 was used to evaluate corrections to the measured helion beam polarization due to the ${}^3\text{He}$ breakup. The breakup effect was found to be negligible if the ratio of the beam and target (jet) single spin asymmetries are concurrently measured to determine the ${}^3\text{He}$ beam polarization.

Turbulence drag modulation by dispersed droplets in Taylor–Couette flow: the effects of the dispersed phase viscosity

The dispersed phase in turbulence can vary from almost inviscid fluid to highly viscous fluid. By changing the viscosity of the dispersed droplet phase, we experimentally investigate how the deformability of dispersed droplets affects the global transport quantity of the turbulent emulsion. Different kinds of silicone oil are employed to result in the viscosity ratio, $\zeta$ , ranging from $0.53$ to $8.02$ . The droplet volume fraction, $\phi$ , is varied from 0 % to 10 % with a spacing of 2 %. The global transport quantity, quantified by the normalized friction coefficient $c_{f,\phi }/c_{f,\phi =0}$ , shows a weak dependence on the turbulent intensity due to the vanishing finite-size effect of the droplets. The interesting fact is that, with increasing $\zeta$ , $c_{f,\phi }/c_{f,\phi =0}$ first increases and then saturates to a plateau value which is similar to that of the rigid particle suspension. By performing image analysis, this drag modification is interpreted from the point of view of droplet deformability, which is responsible for the breakup and coalescence effect of the droplets. The statistics of the droplet size distribution show that, with increasing $\zeta$ , the stabilizing effect induced by interfacial tension becomes substantial and the pure inertial breakup process becomes dominant. The measurement of the droplet distribution along the radial direction of the system shows a bulk-clustering effect, which can be attributed to the non-negligible coalescence effect of the droplet. It is found that the droplet coalescence effect could be suppressed as $\zeta$ increases, thereby affecting the contribution of interfacial tension to the total stress, and accounting for the observed emulsion rheology.

Phenomenological and microscopic analysis for the 7Li + 12C system

We report the results of an analysis of the 7Li + 12C elastic scattering angular distributions measured at energies between 5.8 and 350 MeV. The analysis is based on various nuclear potentials and approaches. The objective of this study is to analyze the cluster character of the weakly bound 7Li nucleus in order to verify the associated breakup effects on the elastic scattering data and to examine the consistency of the acquired results across the various potentials used. The analysis shows the impact of strong coupling to the breakup channel. The fully microscopic continuum discretized coupled channel (CDCC) method is employed efficiently to elucidate the data under consideration.

Extensive investigation of the 6Li + 27Al and 6He + 27Al systems using different models

In this paper, the angular distributions (ADs) for 6Li + 27Al and 6He + 27Al elastic scattering in the energy range of 7–88 MeV and 9.5–13.4 MeV, respectively, are reanalyzed utilizing various phenomenological and microscopic potentials. The purpose of this work is to investigate the cluster nature of the weakly stable 6Li and the two-neutron halo 6He projectiles to check the associated breakup effects on the scattering data and to examine the consistency of the results obtained across different implemented potentials. A novel semi-microscopic dynamical polarization potential is applied to the 6Li + 27Al system to simulate the coupling effects on the breakup channel. The ADs for the 6He + 27Al system are described using the continuum discretized coupled channels (CDCC) method, which considers the coupling to the resonant (2+, 1.8 MeV) state and twelve continuum bins belonging to L = 0, 1, and 2 states as per the adopted model for truncation and discretization of the continuum.

The role of breakup and coalescence in fine-scale bubble-induced turbulence. I. Dynamics

We study the effect of bubble breakup and coalescence on fine-scale dynamics of bubbly turbulent flows using direct numerical simulations. We perform two different simulations of dilute bubbly flows of void fraction 0.5%: one with bubbles breaking up and coalescing and the other without these physical processes. The volume of the fluid method is used for simulating bubbles undergoing breakup and coalescence while the bubbles are treated as rigid spheres in the immersed boundary method simulation. The energy spectrum in both types of simulation, consistent with previous studies, exhibits a −3 slope. We follow a single infinitesimal fluid element as it evolves to understand velocity gradient dynamics using conditional mean trajectories. We note finite-time divergence when the fluid element evolves under the action of inertial and pressure dynamics. The inertial, pressure, and viscous velocity gradient dynamics, when considered individually, produce the same results for bubble-induced turbulence (BIT) as with the classical homogeneous isotropic turbulence (HIT). Yet when the overall velocity gradient dynamics is considered, BIT results in non-cyclic trajectories moving toward stable node and unstable saddle while classical HIT shows cyclic behavior in their trajectories that move toward the origin. Interestingly, both the volume of fluid and immersed boundary simulations produce similar results. Therefore, there are two main takeaways from this research. First, new velocity gradient models are needed for BIT as their velocity gradients behavior is entirely different from the HIT. Second, we can neglect the bubble topology, breakup, and coalescence while studying or modeling the fine-scale dynamics of BIT.

The role of breakup and coalescence in fine-scale bubble-induced turbulence. II. Kinematics

This second part of our research explores the kinematic aspect of fine-scale bubble-induced turbulence (BIT) to (i) present the effect of bubble breakup and coalescence and (ii) compare it against the universal kinematic fine-scale turbulence characteristics reported in the literature. To this end, we simulate a dilute bubbly system of 0.5% void fraction using two distinct numerical simulations. In the volume-of-fluid (VoF) simulation, bubbles undergo breakup and coalescence. In the immersed boundary method (IBM) simulation, however, they act as rigid spheres. We also perform a simulation of classical homogeneous isotropic turbulence (HIT). The first important outcome of this study is that BIT is radically different from HIT in terms of its kinematic fine-scale characteristics. In the vorticity-dominating regions, BIT exhibits a weak vortex stretching. This weak vortex stretching is due to (a) the intermediate strain-rate eigenvalues skewed weakly to positive and (b) the extensive strain-rate eigenvector aligning perpendicular to the vorticity vector. The BIT has, on average, not only a weak enstrophy production but also a weak strain production in strain-dominating regions. The weak strain production is due to (a) the presence of vortex stretching in highly strained fluid elements and (b) the absolute magnitude of compressive strain-rate eigenvalue being as close to the extensive strain-rate eigenvalue. Thus, none of the kinematic fine-scale HIT characteristics is noted for BIT. The second important conclusion is that bubble breakup and coalescence play little to no influence on the kinematics of fine-scale BIT as VoF and IBM simulations produce similar results.

Application of R-Matrix and Lagrange-Mesh Methods to Nuclear Transfer Reactions

Background: Nuclear transfer reactions are a useful tool to study the structure of a nucleus. For reactions involving weekly bound nuclei, breakup effects can play significant role and theoretical calculations can be computational expensive in such cases.
 Purpose: To utilize the Lagrange-mesh and R-matrix methods for nuclear transfer reactions.
 Methods: We use the adiabatic distorted wave approximation (ADWA) method which can approximately treats the breakup effects in a simpler manner. In our approach, we apply the R-matrix method combining it with the Lagrange-mesh method, which is known to provide the fast and accurate computations.
 Results: As a test case, we calculate the angular distribution of the cross sections for the 56Fe(d, p)57Fe reaction, where deuteron breakup effects play important role.
 Conclusions: We show that these methods work well in the ADWA framework, and we look forward to applying these methods in coupled channel calculations.

Break-up effect of the weakly bound 6Li nuclei scattered by 208Pb target

Using different potentials based on phenomenological, semi microscopic, and microscopic models, we investigated the reaction dynamics induced by the weakly bound 6Li ions on a heavy mass target 208Pb at sixteen energy sets ranging from 25 MeV to 210 MeV. The 6Li cluster nature and its dissociation into a core (α-particle) and a valence particle (deuteron) orbiting this core was taken into consideration using the cluster folding model (CFM). The new version of Sao Paulo potential (SPP2) is also used to investigate 6Li+208Pb data. In order to reproduce the experimental data, the strength of real part of potential created using SPP and CFM should be reduced by ~ 49 % and 62 %, respectively. The data could be well reproduced using non-renormalized real cluster folding potential, if an additional dynamical polarization potential (DPP) of repulsive real surface form is introduced. The observed reduction in the strength of the real double folded and cluster folding potentials is due to the break-up effect of 6Li.

Comparison of Coulomb breakup effects on the elastic scattering of $$^{6}$$He and $$^{8}$$He using a Coulomb dipole polarization potential

Comparison of Coulomb breakup effects on the elastic scattering of $$^{6}$$He and $$^{8}$$He using a Coulomb dipole polarization potential

Anomaly in weakly bound 7Li nucleus in the field of 208Pb target

We have investigated the threshold anomaly observed in 7Li + [Formula: see text]Pb nuclear system by analyzing the available 7Li+[Formula: see text]Pb experimental angular distribution measurements. The experimental data for the weakly bound 7Li ions elastically scattered from [Formula: see text]Pb target at 13 energy sets ranging from 25.67 and up to 68[Formula: see text]MeV are subjected to detailed analysis using different interaction potentials created either based on phenomenological, semimicroscopic and microscopic models. The loosely bound nucleus 7Li, possessing a predominant [Formula: see text] cluster structure at 2.468[Formula: see text]MeV, is a good candidate as its break-up reaction studies would help to understand the break-up of the weakly bound unstable radioactive isotopes. In order to observe the break-up effect, reaction cross-sections are extracted and compared with the previously reported ones.

Breakup effects in the C16+p and C16+d reactions

We analyze the $^{16}\mathrm{C}+p$ and $^{16}\mathrm{C}+d$ reactions within the four- and five-body continuum discretized coupled channel method. The $^{16}\mathrm{C}$ nucleus is described by a $^{14}\mathrm{C}+n+n$ configuration in hyperspherical coordinates. This description reproduces fairly well several $^{16}\mathrm{C}$ low-lying states. First we analyze the ${2}^{+}\ensuremath{\rightarrow}{0}^{+}\phantom{\rule{4pt}{0ex}}E2$ transition amplitude, which confirms that an effective charge must be introduced to reproduce the experimental value. Then, proton and deuteron elastic and inelastic scattering are investigated by including $^{16}\mathrm{C}$ pseudostates, which simulate the $^{14}\mathrm{C}+n+n$ continuum. In $^{16}\mathrm{C}+d$, the deuteron breakup is taken into account with $p+n$ two-body pseudostates. A fair agreement with experiment is obtained without any fitting parameter. Breakup effects are in general small, but improve the agreement with experiment.

Systematic study of fusion suppression for tightly bound projectiles at above-barrier energies

The present work aims to explore the effects of projectile breakup on fusion cross section at energies near the Coulomb barrier to well above it. The complete fusion cross section for the strongly bound non-$\ensuremath{\alpha}$-cluster projectile $^{14}\mathrm{N}$ in interaction with a $^{181}\mathrm{Ta}$ target was obtained by summing the experimentally measured channel-by-channel cross section data of evaporated residues. The obtained total fusion cross section was compared with the theoretical code ccfull and the results were found to be consistent with each other. Further, the experimental fusion function data on $^{181}\mathrm{Ta}$ target with $^{14}\mathrm{N}$ projectile were deduced and compared with those obtained for other strongly bound projectiles, viz., $^{12,13}\mathrm{C}$, $^{16}\mathrm{O}$, and $^{19}\mathrm{F}$, in order to get some systematics in fusion reactions. The analysis of experimental fusion functions was performed within the framework of a benchmark curve called the universal fusion function (UFF). A suppression of about 5--25% with respect to UFF was observed for the presently studied systems at energies above the Coulomb barrier, indicating that the suppression is essentially due to the prompt breakup of the projectiles and is a strong function of breakup threshold of projectiles. The magnitude of such suppression was found to be lower for $^{14}\mathrm{N}$ projectile as compared to other strongly bound projectiles. Moreover, an interesting exponential relation between the experimentally deduced suppression factor and the breakup threshold of the projectile was obtained.

Breakup, Collision Dynamics and Secondary Effects on Fuel Droplets in a Pressure-Swirl Spray

Breakup, Collision Dynamics and Secondary Effects on Fuel Droplets in a Pressure-Swirl Spray

Synergistic effects of hybrid (HA+Ag) particles and friction stir processing in the design of a high-strength magnesium matrix bio-nano composite with an appropriate texture for biomedical applications

In this work, the effects of hybrid (HA + Ag) particles and triple-pass friction stir processing on the microstructure, texture, hardness, and tensile behavior of magnesium matrix bio-nano composite were investigated. The results showed that the mean grain size of samples was in the range of 1–5 μm owing to the occurrence of dynamic recrystallization and suppression of grain growth by second phase particles. All samples exhibited uniform dispersion of particles in the magnesium matrix caused by triple-pass FSP. However, some agglomerations were visible in the microstructure of AZ91/nHA nanocomposite. The average grain size of the AZ91/nHA/smAg sample (1.4 μm) was smaller than that of the AZ91/nHA/mAg sample (2.1 μm), which was attributed to the formation of higher content of MgxAgy precipitates in the AZ91/nHA/smAg composite. By performing the FSP, the content of Mg17Al12 was significantly decreased due to the dissolution of beta into the alpha caused by the breakup effect of mechanical stirring and temperature increase of samples. The AZ91/nHA/smAg sample had the highest texture parameter for the {101‾1} orientation as the high corrosion resistance texture. This was due to the promoting the non-basal slip caused by the dissolution of smAg particles in the magnesium matrix. After the FSP, the microhardness distribution of AZ91, AZ91/nHA, AZ91/nHA/mAg, and AZ91/nHA/smAg samples tended to be uniform and the average hardness was improved owing to the fragmentation of beta particles, grain refinement, and homogeneous dispersion of second phase particles. Compared with the AZ91/nHA/mAg sample, an increase in ultimate tensile strength (291.7 MPa), and a decrease in total elongation (5.6%) and energy absorption (12.3 J/cm3) were observed in the AZ91/nHA/smAg sample due to the formation of a higher content of the silver-rich precipitates in the AZ91/nHA/smAg sample during cooling caused by the higher solubility of silver submicron particles. The fracture surfaces of all processed samples consisted of a large number of fine equiaxed dimples (ductile fracture) owing to the grain refinement and the presence of fine second phase particles.

Fusion and proton transfer in the B10+Al27 system at sub-barrier energies

Background: Significant enhancement in sub-barrier fusion cross sections by several orders of magnitude, in the frame of one-dimensional barrier penetration models, is observed for a variety of nuclear systems. To understand this, one needs to find the fundamental degrees of freedom relevant in the sub-barrier fusion region by incorporating nonelastic channels such as coupling of the excited target and/or projectile nuclei, particle transfer channels, threshold variation of nuclear potential, etc.Purpose: We probe what degrees of freedoms are associated with the $^{10}\mathrm{B}+^{27}\mathrm{Al}$ reaction at energies $\ensuremath{\approx}18%$ below to $\ensuremath{\approx}12%$ above the Coulomb barrier.Method: An online $\ensuremath{\gamma}$-ray spectroscopy technique is used to determine the populated excitation functions in the $^{10}\mathrm{B}+^{27}\mathrm{Al}$ reaction. The reaction cross sections obtained from these $\ensuremath{\gamma}$ rays are compared with the statistical model to explore the mechanism of fusion reactions.Results: At energies near and below the Coulomb barrier, two isotopes of sulfur ($^{34}\mathrm{S}$ and $^{32}\mathrm{S}$) were found to reproduce cross section within the frame of the pace2 model based on Hauser-Feshbach calculations, whereas isotopes of chlorine ($^{35}\mathrm{Cl}$), sulfur ($^{35}\mathrm{S}$), and phosphorous ($^{32}\mathrm{P}$) agree well but at above-barrier energies. Isotopes of Ar, Cl, S, P, and Si show significant enhancement over an entire band of energies. This enhancement (suppression) in the experimental cross section at energies above (below) the barrier points towards the involvement of some nuclear reaction mechanism other than fusion-evaporation. Distorted-wave Born approximation calculations strongly support the population of $^{28}\mathrm{Si}$ residue via the one-proton transfer process. The total fusion cross section is found to follow the theory after the inclusion of coupling of low lying excited states of projectile and target. Calculations concerning the astrophysical $S$ factor and the logarithmic derivative factor support the idea of no fusion hindrance at the studied energies. The universal fusion function benchmark shows consistency with previous data for lithium (or Li isotopes) induced systems.Conclusions: The inclusion of inelastic couplings associated with both target and projectile is important to understand the behavior of total fusion cross section. The formation of $^{28}\mathrm{Si}$ via the one-proton transfer reaction supports the present experimental technique to make inclusive transfer measurements. The calculations with the universal fusion function present a slight suppression in the higher energy region, indicating possible breakup effects in this region. The present calculations show that till $18%$ below the barrier there is no fusion hindrance. On extrapolating the theoretical values we further observed that the present system has no fusion hindrance. No connection of $^{10}\mathrm{B}+^{27}\mathrm{Al}$ fusion with astrophysics has been made, which raises the question to think of cosmic ray reactions and perhaps reactions in the early solar system, but how the fusion reaction would fit into the picture is not clear at all.