First proof-of-principle experiment with the post-accelerated isotope separator on-line beam at BRIF:measurement of the angular distribution of ^(23)Na+^(40)Ca elastic scattering

The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest.Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei.The development of rare isotope accelerators offers opportunities for such studies.To date,many relevant measurements have been performed at accelerators using the projectile fragmentation technique,while the measurements at accelerators using isotope separator on-line(ISOL)systems are still quite scarce.In this work,we present the first proof-of-principle experiment with a post-accelerated ISOL beam at the Beijing Radioactive Ion Beam Facility(BRIF)by measuring the angular distribution of elastic scattering for the stable nucleus^(23)Na from the doubly magic nucleus^(40)Ca at energies above the Coulomb barrier.The angular distribution measured by a silicon strip detector array in a scattering chamber using the ISOL beam at BRIF is in good agreement with that measured by the high-precision Q3 D magnetic spectrograph using the nonISOL beam at nearly the same energy.This work provides useful background for making BRIF a powerful tool for the investigation of the reaction dynamics of exotic nuclei.

The effects of beam drifts on elastic scattering measured by the large solid-angle covered detector array

A new detector array characterized by compact structure and large solid-angle coverage was designed for radioactive ion beam(RIB)experiments and measuring multi-particle correlations.A Monte Carlo simulation was performed to explore the effects of beam drifts in different directions and distances on the angular distribution of the Rutherford scattering,as measured by the detector array.The results indicate that when the beam drift distance is less than 2.0 mm,the symmetry of the detector array can maintain a count error of less than 5%.This confirms the property of the detector array for RIB experiments.Furthermore,the simulation was validated through the elastic scattering angular distributions of 6;7 Li measured by the detector array in 6;7Li t209 Bi experiments at different energies.

B3Y-FETAL effective interaction in the folding analysis of elastic scattering of ^(16)O+^(16)O

In this paper,a new M3Y-type effective nucleon–nucleon interaction,derived based on the lowest order constrained variational approach(LOCV)and termed B3Y-Fetal,has been used in DDM3Y1,BDM3Y1,BDM3Y2,and BDM3Y3 density-dependent versions in a heavy ion(HI)optical potential based on four types of a real folded potential and a phenomenological Woods–Saxon imaginary potential to study the elastic scattering of the^(16)O+^(16)O nuclear system within the framework of the optical model(OM)by computing the associated differential cross sections at various incident energies.The results of the folding analyses have shown the DDB3Y1-Fetal and BDB3Y1-Fetal,out of the four folded potentials,give a reasonably better description of the elastic data of the nuclear system.These best-fit folded potentials are followed,in performance,by the BDB3Y2-Fetal,with the BDB3Y3-Fetal potential coming last.This performance trend was also demonstrated by the optical potentials based on the M3Y-Reid interaction.Furthermore,the best-fit folded potentials,renormalized by a factor NRof approximately 0.9,have been shown to reproduce the energy dependence of the real optical potential for^(16)O scattering found in previous optical model analyses creditably well.In excellent agreement with previous works,they have also been identified in this work to belong to the family of deep refractive potentials because they have been able to reproduce and consistently describe the evolution of Airylike structures,at large scattering angles,observed in the^(16)O scattering data at different energies.Finally,a comparison of the performances of B3Y-Fetal and M3Y-Reid effective interactions undertaken in this work has shown impressive agreement between them.

Elastic scattering of ^(13)C and ^(14)C isotopes on a ^(208)Pb target at energies of approximately five times the Coulomb barriers

The elastic scattering angular distributions of ^(13)C at 340 MeV and ^(14)C at 294 MeV and 342 MeV on a ^(208)Pb target,which correspond to approximately five times the Coulomb barriers,were measured at the Radioactive Ion Beam Line in Lanzhou.The data were analyzed within the optical model and continuum-discretized coupled-channels(CDCC)framework,and the results of both calculations could effectively account for the experimental data.The differential cross sections of elastic scattering revealed no particular suppression at the Coulomb nuclear interference peak angles,suggesting that the breakup coupling effects on the elastic scattering angular distributions were negligibly small in this incident energy region.The contributions from the couplings with inelastic states to the elastic cross sections were of minor importance within the angular range covered by these experiments.

Elastic scattering and total reaction cross sections of^(6)Li examined via a microscopic continuum discretized coupled-channels model

We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is treated in anα+d two-body model.Collisions with 27Al,64Zn,138Ba,and 208Pa are analyzed.The microscopic optical potentials(MOP)based on Skyrme nucleon-nucleon interaction forαand d are adopted in CDCC calculations and satisfactory agreement with the experimental data is obtained without any adjustment on MOPs.For comparison,αand d global phenomenological optical potentials(GOP)are also used in CDCC analysis and a reduction of no less than 50%on the surface imaginary part of deuteron GOP is required for describing the data.In all cases,the 6Li breakup effect is significant and provides repulsive correction to the folding model potential.The reduction on the surface imaginary part of GOP of deuteron reveals a strong suppression of the reaction probability of deuteron as a component of 6Li when compared with that of a free deuteron.Further investigation is performed by considering the d breakup process equivalently within the dynamic polarization potential approach,and the results show that d behaves in a manner similar to a tightly bound nucleus in 6Li induced reactions.

Description of elastic scattering for 7Li-induced reactions on 1p-shell nuclei

The experimental data of elastic scattering angular distributions for 9Be,10B,11B,12C,13C,15N,and 16O targets from 4.5 to 131.8 MeV and 7Li target from 8.0 to 42.0 MeV are fitted to realize the global phenomenological optical potentials(GPOPs)for the 7Li-induced reactions on 1p-shell nuclei.Thus,the 7Li elastic scattering from the 1p-shell nuclei can be systematically described using the established GPOPs.The elastic scattering angular distributions are also reanalyzed using a microscopic method within the framework of the new version of double folding S?o Paulo potential(SPP2).To better describe the elastic scattering at backward angles,the contribution of elastic transfer is further estimated by the distorted wave Born approximation(DWBA)method.Based on the obtained GPOPs,the inelastic scattering angular distributions are also obtained through the coupled channels(CC)method for the different excited states.

Elastic scattering based on energy-dependent relativistic Love-Franey model at energies between 20 and 800 MeV

In order to investigate the elastic scattering,we fit scattering observables of the weighted fits(WF16)with the relativistic Love-Franey(RLF)model.The masses,cutoff parameters,and initial coupling strengths of RLF are assumed to be independent of energy.Because the energy boundary between low energy and high energy is around 200 Me V,the masses,cutoff parameters,and initial coupling strengths of RLF are obtained by fitting scattering observables of WF16 at an incident energy of 200 MeV.With the masses,cutoff parameters,and initial coupling strengths as the input,the energy-dependent RLF model is constructed over the laboratory energy range of 20 to 800MeV within a unified fit.To examine the validity of this fit,we investigate p+^(208)Pbelastic scattering for various energies.Although the scattering observables of pp and pn of 200 MeV best fit the values of WF16,the RLF model of 200 MeV without the Pauli blocking(PB)corrections fails to describe the experimental differential cross sections,analyzing powers,and spinrotation functions.When the PB corrections are taken into account for various energies,the RLF model can well describe the experimental data of p+^(208)Pbelastic scattering.

Elastic and inelastic positron-helium scattering

Elastic and inelastic positron-helium scatterings have been investigated with the coupled-channel optical method (CCO).Ionization continuum and positronium formation channels are included via a complex equivalent-local optical potential.Calculations are reported of cross sections of elastic scattering,total excitation and n=2,3,and 4 excitations of ground-state helium for incident energies from 30 eV to 400 eV.The present calculation shows that the ionization and Ps-formation channels significantly affect the cross sections of elastic and inelastic positron-helium scatterings.

Experimental study of the elastic scattering of 10Be on 208Pb at the energy of around three times the Coulomb barrier

Elastic scattering of 10Be on a 208Pb target was measured at ELab=127 MeV,which corresponds to three times the Coulomb barrier.The secondary 10Be beam was produced at the Radioactive Ion Beam Line in Lanzhou of the Heavy-Ion Research Facility in Lanzhou.The angular distribution of elastic scattering in the 10 Be+208Pb system shows a typical Fresnel diffraction peak.Optical model analysis of the angular distribution was performed using the Woods-Saxon,double-folding and global potentials.With the global potential,different density distributions were used.The results indicate that different density distributions for the projectile induce distinct effects in the angular distribution.

New measurements and reanalysis of^14N elastic scattering on^10B target

The angular distributions of elastic scattering of^14N ions on^10B targets have been measured at incident beam energies of 21.0 and 24.5 MeV.Angular distributions at higher energies 38–94.0 MeV(previously measured)were also included in the analysis.All data were analyzed within the framework of the optical model and the distorted waves Born approximation method.The observed rise in cross sections at large angles was interpreted as a possible contribution of theα-cluster exchange mechanism.Spectroscopic amplitudes SA2 and SA4 for the configuration^14N→^10B+αwere extracted.Their average values are 0.58±0.10 and 0.81±0.12 for SA2 and SA4,respectively,suggesting that the exchange mechanism is a major component of the elastic scattering for this system.The energy dependence of the depths for the real and imaginary potentials was found.

The angular distributions of elastic scattering of^12,13C+Zr

To obtain the neutron spectroscopic amplitudes for 90-96Zx overlaps experimental data of elastic scatter-ing with small experimental errors and precise optical potentals were anary exin othe hiohpyecision o3D magneticangular distributions of^12,^13C+^AZr(A=90,91,92,94,96)were measured using the high-precision Q3D magnetic spectrometer in the Tandem accelerator.The Sao Paulo potential was used for the optical potential.The optical mod-el and coupled channel calculations were compared with the experimental data.The theoretical results were found tobe very close to the experimental data.In addition,the possible effects of the couplings to the inelastic channels of the^AZr targets and 12,13^C projectiles on the elastic scattering were studied.It was observed that the couplings to the in-elastic channels of the^12,^13C projectiles could improve the agreement with the experimental data,while the inelasticcouplings to the target states are of minor importance.The effect of the one-neutron stripping in the^13C+^AZr elasticscattering was also studied.The one-neutron stripping channel in^13C+^AZr was found to be not relevant and did notaffect the elastic scattering angular distributions.Our results also show that in the reactions with the considered zir-conium isotopes,the presence of the extra neutron in^13C does not influence the reaction mechanism,which is gov-erned by the collective excitation of the^12C core.

Elastic Wave Scattering by Two-Dimensional Periodical Array of Cylinders

We extend the multiple-scattering theory (MST) for elastic wave scattering and propagating in two-dimensional composite. The formalism for the band structure calculation is presented by taking into account the full vector character of the elastic wave. As a demonstration of application of the formalism, we calculate the band structure of elastic wave propagating in a two-dimensional periodic arrangement of cylinders. The results manifest that the MST shows great promise in complementing the plane-wave (PW) approach for the study of elastic wave.

Prospects of detecting the reactor v_(e)-Ar coherent elastic scattering with a low-threshold dual-phase argon time projection chamber at Taishan

Background We propose to measure the coherent elastic neutrino-nucleus scattering(CEvNS)using a dual-phase liquid argon time projection chamber(TPC)with 200 kg fiducial mass.The detector is expected to be adjacent to the JUNOTAO experiment and to be about 35 m from a reactor core with 4.6 GW thermal power at Taishan.The antineutrino flux is approximately 6×10^(12)cm^(−1)s^(−1) at this location,leading to more than 11,000 coherent scattering events per day in the fiducial mass.Motivation The nuclear recoil energies concentrate in the sub-keV region,corresponding to less than ten ionization electrons in the liquid argon.The key question is how to veto and shield the background in the hall where the vertical overburden is about 5 m.w.e.And what is the signal count rate and the background rate.In addition,what physical parameters can be measured what is the sensitivity.Methods We used the Geant4 to simulate the backgrounds from cosmic ray muons and ambient radioactivity decays.And a veto and shielding design is presented.Then a χ^(2) function is constructed and the sensitivity calculate package built to calculate the sensitivity of physical parameters.Results The detection of several ionization electrons can be achieved in the dual-phase TPC due to the large amplification in the gas region.With a feasible detection threshold of four ionization electrons,the signal rate is 955 per day.The detector is designed to be shielded well from cosmogenic backgrounds and ambient radioactivities to reach a 16%background-tosignal ratio in the energy region of interest.With the large CEvNS sample,the expected sensitivity of measuring the weak mixing angle sin^(2)θ_(w),and of limiting the neutrino magnetic moment are discussed.In addition,a synergy between the reactor antineutrino CEvNS experiment and the dark matter experiment is foreseen.

The scattering of plane P1 wave by a 3-D sedimentary basin in a fluid-saturated poroelastic half-space using IBEM

The indirect boundary element method(IBEM)is applied to investigate the scattering of elastic waves around a 3-D sedimentary basin filled with fluid-saturated poroelastic medium.Based on this method,the free field and scattered field can be solved according to the boundary conditions.And the numerical accuracy has been verified.The effects of parameters on elastic wave scattering are studied,such as boundary condition,incident frequency,incident angle and porosity of medium.Numerical results illustrate that the amplification effect of surface displacement near poroelastic sedimentary basin is notable.In addition,for the case of large porosity the drainage condition has a significant impact on the response amplitude.Due to the fluid exchange at the interface under the drained condition,the displacement amplitude can be much larger than that under the undrained condition in present study.The study can provide a theoretical basis for the anti-seismic design of engineering structures located in sedimentary basin.

Elastic Wave Scattering and Dynamic Stress Concentrations around Double Holes in Piezoelectric Media

In this paper, on the basis of Liu’s complex function and conformal mapping methods, supplemented by local coordinate system method, e-type piezoelectric material and elastic wave scattering and dynamic stress concentrations problems with double holes question are studied, and an analytical solution is given to the problems. On the basis of multiple scattering of elastic wave theory, put forward the study about microscopic dynamics model to dynamic stress in the structure of piezoelectric composites as well as dynamic playing field. As an example, the numerical results of the dynamic stress distribution around the hole in case double equal diameter holes are given in the paper, and the influence of incident wave number and hole-spacing parameters on the dynamic stress concentration factor is analyzed.

Using Refined Theory to Studied Elastic Wave Scattering and Dynamic Stress Concentrations in Plates with Two Cutouts

In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied. Applying the orthogonal function expansion method, the problem to be solved can be reduced into the solution of a set of infinite algebraic equations. According to free boundary conditions, numerical results of dynamic moment concentration factors in thick plates with two circular cutouts analyze that: there will be more complex interaction changes between two-cutout situation than single cutout situation. In the case of low frequency or high frequency and thin plate, the hole-spacing in the absence of coupling interactions was larger or smaller. The numerical results and method can be used to analyze the dynamics and strength of plate-like structures.

Trial application of the envelope method to the potential ambiguity problem

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering data.For a specific collid-ing system,ambiguous potential families can lead to different behaviors in the nearside and farside scattering components.By contrast,the envelope method can decompose the experimental data into two components with negative and positive deflection angles,respectively.Hence,a question arises as to whether the comparison between the calculated nearside(or farside)component and the derived positive-deflection-angle(or negative-deflection-angle)component can help analyze the potential ambiguity problem.In this study,we conducted a trial application of the envelope method to the potential ambiguity problem.The envelope method was improved by including uncertainties in the experimental data.The colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV were considered in the analyses.For each colliding system,the angular distribution experimental data were described nearly equally well by two potential sets,one of which is“surface transpar-ent”and the other is refractive.The calculated angular distributions were decomposed into nearside and farside scattering components.Using the improved envelope method,the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components,which were then compared with the calculated nearside and farside components.The capability of the envelope method to analyze the potential ambiguities was also discussed.

Acoustic radiation force on thin elastic shells in liquid

Based on the coupled acoustic scattering of two neighboring fluid-filled thin elastic shells suspending in an unbounded viscous liquid,an analytical method is developed to calculate the acoustic radiation force(ARF)of the shells.Two physical effects are taken into account:elastic radiation scattering and the multiple interactions of shells.Numerical results reveal that the magnitude of ARF can be enhanced by the sound radiation from the elastic shell undergoing forced vibrations and two resonant peaks can be observed on the ARF function curves.The feature of the lower peak is determined by the interactions and acoustic response of the back shell.The attractive forces can be obtained in the low kR1 band for the case of radius ratio R2/R1>1,while the magnitude of ARF at the lower peak may be influenced to some extent by acoustic shielding phenomenon for the case of radius ratio R2/R1<1.Accordingly,the interactions of particles cannot be ignored.The results may provide a theoretical basis for precisive manipulation of multiple particle systems.

Particles Composition and Interactions Using the Nuon Model

The Standard Model in Particle Physics has been able to make many predictions confirmed later with a flow of experimental results. With the discovery of the Higgs boson at the LHC, one is full of admiration for the people contributing to this model fifty years ago and its predictions that have been confirmed gradually. The original particle quark constituent model has evolved with the deep inelastic experiments to a quark and gluons system, then to a more general system with virtual quarks. This work is the result of observations while working at CERN in Geneva with many different experiments at the ISR, SPS, LEP, LHC colliders. A new model based on nuons is introduced, that allows accurate evaluations of the particle masses (mesons and baryons) and magnetic moment, computes very accurately the kinematics distributions for particles and jets observed in the p-p collisions at the LHC (elastic and inelastic) and at lower energy machines. This new model looks at a first glance in contradiction with the quark model because it can build the elementary particles with nuons only, i.e. electrons and neutrinos. However, all the existing physics involved in electron, positron and neutrino interactions may be used to explain interactions between composite particles such as protons or heavy ions.

A Node-Based Smoothed Finite Element Method with Linear Gradient Fields for Elastic Obstacle Scattering Problems

In this paper,a node-based smoothed finite element method(NS-FEM)with linear gradient fields(NS-FEM-L)is presented to solve elastic wave scattering by a rigid obstacle.By using Helmholtz decomposition,the problem is transformed into a boundary value problem with coupled boundary conditions.In numerical analysis,the perfectly matched layer(PML)and transparent boundary condition(TBC)are introduced to truncate the unbounded domain.Then,a linear gradient is constructed in a node-based smoothing domain(N-SD)by using a complete order of polynomial.The unknown coefficients of the smoothed linear gradient function can be solved by three linearly independent weight functions.Further,based on the weakened weak formulation,a system of linear equation with the smoothed gradient is established for NS-FEM-L with PML or TBC.Some numerical examples also demonstrate that the presented method possesses more stability and high accuracy.It turns out that the modified gradient makes the NS-FEM-L-PML and NS-FEM-L-TBC possess an ideal stiffness matrix,which effectively overcomes the instability of original NS-FEM.Moreover,the convergence rates of L 2 and H1 semi-norm errors for the two NS-FEM-L models are also higher.