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We present in this work a theoretical study of the triple differential cross sections for electron-impact single ionization of 12a′ and 9b orbitals of a tetrahydrofuran molecule. The calculations are performed by the multicenter distorted-wave (MCDW) method in coplanar asymmetric kinematics with an incident electron energy of 250 eV, where previous (e, 2e) experiments and theories are available for comparison. The present calculations reproduce the experimental measurements satisfactorily, indicating that the MCDW method can be easily extended to study biomolecules with sufficiently high calculation efficiency. [ABSTRACT FROM AUTHOR]

Energy levels, lifetimes, oscillator strengths, radiative decay rates, line strengths, electron-impact collision strengths and effective collision strengths are presented for aluminium-like Ar VI. New radiative data for forbidden lines are presented for the first time. We used the following 12 configurations in our work: 3s ²3p, 3s3p², 3s ²3d, 3p³, 3s3p3d, 3s²4s, 3s²4p, 3p²3d, 3s²4d, 3s3p4s, 3s3p4p and 3s3p4d yielding to 121 fine structure levels. The calculations have been carried out using the AUTOSTRUCTURE code. It included the one-body and the two-body (fine and non-fine structure) interactions of the Breit-Pauli Hamiltonian. No results for forbidden transitions have been found in the literature. For the collisional problem, the distorted wave approximation has been assumed. Collision strengths have been calculated at six electron energies: 10, 50, 100, 200, 400 and 800 Ry. Convergence of collision strengths with total angular momentum has been studied at each electron energy. For some lines, we make use also of the codes SUPERSTRUCTURE/DISTORTED WAVE/JAJOM to compare with the AUTOSTRUCTURE results. Effective collision strengths have been calculated for a wide range of temperatures up to 3.6 × 105 K, and are compared to those from the Breit-Pauli R-matrix method. [ABSTRACT FROM AUTHOR]

Highlights • Reproducible growth method of FePd with high PMA and parallely aligned magnetic domains. • Pseudo-reversible manipulation of the domain pattern after applying a saturating magnetic field. • Simulation of the Q y - Q z -map of a GISANS measurement using the Distorted Wave Born Approximation. Abstract L1 0 -ordered FePd thin films with strong perpendicular magnetic anisotropy and self-organized domain patterns have been prepared using molecular beam epitaxy. We demonstrate reproducible growth methods for controlling the strength of the anisotropy and the lateral domain patterns. Neutron scattering experiments have been used to probe the FePd domain structure and were compared with simulations in the framework of the Distorted Wave Born Approximation. [ABSTRACT FROM AUTHOR]

Abstract Spontaneous superlattice structure in few monolayer length scale has been observed very recently in Al x Ga 1-x As epilayer on (001) GaAs substrate grown by Metal Organic Chemical Vapor Deposition. Here we have reported a detailed study of this structure using high resolution x-ray reflectivity (XRR) and rocking curve (XRC) analysis and tried to extract composition modulation in the superlattice. A model-independent Distorted Wave Born Approximation (DWBA) has been applied to the XRR results to successfully obtain the electron density profile of the structure from which the compositional information could be extracted. The XRR profile of the Al x Ga 1-x As sample (x = 0.17) showed sharp equidistant peaks giving clear evidence of superlattice ordering in the epilayer. Simulation of the XRR results showed a bilayer segregation with alternating Al composition of 0.1 and 0.4 of thickness 20 and 8 Å, respectively with interfacial thicknesses of 12 Å on both sides, giving a periodicity of 52 Å. The cross-sectional transmission electron microscopic (XTEM) image also showed similar length scale. A kinematical model was then used successfully to fit the sharp peaks observed in the XRC using the characteristic length and compositional parameters obtained from the XRR simulation. These results also showed that the individual bilayers were of single crystalline zinc blende structures. Both the simulation techniques were first applied to a test structure of AlAs/GaAs multilayer of known thickness before applying the same to the spontaneous superlattice to validate the model. Graphical abstract Image 1 Highlights • A combinational x-ray simulation of Al x Ga 1-x As/GaAs (100) spontaneous superlattice. • Distorted Wave Born approximation implemented to fit the x-ray reflectivity curve. • Kinematical theory of x-ray diffraction applied to simulate x-ray rocking curve. • The simulation gave 52 Å periodicity with Al composition varying from 0.1-0.4. [ABSTRACT FROM AUTHOR]

Electron-impact single- and double-ionization cross sections and Maxwellian rate coefficients are presented for the carbon atom. Scaling factors are introduced for the electron-impact excitation and ionization cross sections obtained in the distorted wave (DW) approximation. It is shown that the scaled DW cross sections provide good agreement with measurements for the single ionization of the C atom and C1+ ion. The direct double-ionization (DDI) process is studied using a multi-step approach. Ionization–ionization, excitation–ionization–ionization, and ionization–excitation–ionization branches are analyzed. It is demonstrated that the three-step processes contribute ≼40% of the total DDI cross sections for the case where one of the electrons takes all of the excess energy after the first ionization process. [ABSTRACT FROM AUTHOR]

Abstract The formal theories of breakup reactions are reviewed. The direct breakup mechanism that is formulated within the framework of the post-form distorted-wave Born approximation, is discussed in detail. In this theory, which requires the information about only the ground state wave function of the projectile, the fragment–target interactions are included to all orders while fragment–fragment interaction is treated only in the first order. We put special emphasis on the breakup reactions of the near neutron drip line nuclei on heavy nuclear targets, which are dominated by the pure Coulomb breakup mechanism. The applicability of this theory to describe such reactions involving both spherical as well as deformed projectiles, is demonstrated by comparing the calculations with breakup data for total, energy and angle integrated cross sections and momentum distributions of fragments emitted in such reactions. Roles played by the pure Coulomb, pure nuclear and the Coulomb–nuclear interference terms in describing the breakup observables are discussed. Postacceleration effects in the Coulomb breakup of neutron halo nuclei are elaborated. The function of the pure Coulomb breakup mechanism in the one-neutron removal reactions of the type A (a , b γ) X on heavy target nuclei is underlined. The relationship between the parallel momentum distribution of the fragments and the break down of the magic numbers as the neutron drip line is approached, is highlighted. [ABSTRACT FROM AUTHOR]

The process of excitation of highly charged Fe XXIV ion embedded in weakly coupled plasmas by electron impact is studied, together with the subsequent radiative decay. For the target structure, the calculation is performed using the multiconfiguration Dirac-Hartree-Fock method incorporating the Debye-Hückel potential for the electron-nucleus interaction. Fine-structure levels of the 1s22p and 1s2s2p configurations and the transition properties among these levels are presented over a wide range of screening parameters. For the collision dynamics, the distorted-wave method in the relativistic frame is adopted to include the effect of plasma background, in which the interparticle interactions in the system are described by screened interactions of the Debye-Hückel type. The continuum wave function of the projectile electron is obtained by solving the modified Dirac equations. The influence of plasma strength on the cross section, the linear polarization, and the angular distribution of x-ray photon emission are investigated in detail. Comparison of the present results with experimental data and other theoretical predictions, when available, is made. [ABSTRACT FROM AUTHOR]

The momentum distribution of 11 Be fragments produced by the breakup of 12 Be interacting with a proton target at 700.5 MeV/ u energy has been measured at GSI Darmstadt. To obtain the structure information on the anomaly of the N = 8 neutron shell, the momentum distribution of 11 Be fragments from the one-neutron knockout Be 12 ( p , p n ) reaction, measured in inverse kinematics, has been analysed in the distorted wave impulse approximation (DWIA) based on a quasi-free scattering scenario. The DWIA analysis shows a surprisingly strong contribution of the neutron 0 d 5 / 2 orbital in 12 Be to the transverse momentum distribution of the 11 Be fragments. The single-neutron 0 d 5 / 2 spectroscopic factor deduced from the present knock-out data is 1.39(10), which is significantly larger than that deduced recently from data of 12 Be breakup on a carbon target. This result provides a strong experimental evidence for the dominance of the neutron ν ( 0 d 5 / 2 ) 2 configuration in the ground state of 12 Be. [ABSTRACT FROM AUTHOR]

Collision strengths for all 1326 transitions among lowest 52 fine-structure levels of Br XXVII have been computed using Dirac atomic R-matrix code (DARC). Resonances in the threshold region have been completely resolved and the contributions of these resonances to allowed and forbidden transitions have been presented. The partial collision strength for each angular momentum has been studied graphically. Effective collision strengths have also been determined within the temperature range for all 1326 transitions among the lowest 52 levels. Target state energies of the lowest 52 fine-structure levels have been computed from the multi-configuration Dirac-Fock method (MCDF). Additionally, similar calculations with the relativistic distorted wave method and flexible atomic code (FAC) have also been performed to check the accuracy of our results. The present work represents a new and significant work with improvement in the field. We believe that our presented data of collision and effective collision strengths may be useful in the future for benchmark calculations and for plasma diagnostics. [ABSTRACT FROM AUTHOR]

The differential cross sections for p B scattering are calculated at the energies of 197, 600, and 1000 MeV within Glauber theory. The contributions of single and double collisions are taken into account in the multiple-scattering operator. The contributions of proton collisions with nucleons belonging to various (1 s, 1 p) shells are estimated in the single-scattering cross sections. A comparison with experimental data and with the result of calculations in the distorted-wave Born approximation (DWBA) at 197 MeV showed that the differential cross sections for p B scattering are adequately described in the region forward scattering angles. [ABSTRACT FROM AUTHOR]

The reaction on at incident proton energy of 300MeV is examined in the formalism of finite-range relativistic distorted-wave impulse approximation (FR-RDWIA). In comparison to conventional t-matrix model of Love-Franey, a new form of nucleon-nucleon t-matrix effective interaction is derived at 300MeV using Reid soft core potentials for isotopic spin one and taking into account the finite-range effects in the interaction at knockout vertex. In comparison to the conventional finite range nonrelativistic and relativistic formalism, the present formalism with a new version of t-matrix is effectively reproducing the shape of cross-section energy distributions for , and states for asymmetric angle pair of -. Discrepancies between the experimental cross-section data and finite range theoretical calculations at MeV are reasonably resolved in the present approach. Without any adjustable parameter of bound state, the obtained spectroscopic factors are in reasonably good agreement with the relativistic and nonrelativistic theoretical predictions by , and analysis. [ABSTRACT FROM AUTHOR]

Recent data on the differential angular distribution for the transfer reaction 11 Li( p , d ) 10 Li at E / A = 5.7 MeV in inverse kinematics are analyzed within the DWBA reaction framework, using the overlap functions calculated within a three-body model of 11 Li. The weight of the different 10 Li configurations in the system's ground state is obtained from the structure calculations unambiguously. The effect of the 9 Li spin in the calculated observables is also investigated. We find that, although all the considered models succeed in reproducing the shape of the data, the magnitude is very sensitive to the content of p 1 / 2 wave in the 11 Li ground-state wave function. Among the considered models, the best agreement with the data is obtained when the 11 Li ground state contains a ∼31% of p 1 / 2 wave in the n – 9 Li subsystem. Although this model takes into account explicitly the splitting of the 1 + and 2 + resonances due to the coupling of the p 1 / 2 wave to the 3 / 2 − spin of the core, a similar degree of agreement can be achieved with a model in which the 9 Li spin is ignored, provided that it contains a similar p -wave content. [ABSTRACT FROM AUTHOR]

Neutron supermirrors (SMs), the major components of neutron optical devices, are depth-graded d-spacing multilayers of several hundreds to several thousands of bilayers. The interface roughness is a major factor in the reflectivity of multilayers. This influence is especially significant if the number of bilayers is large. In this work, the interface roughness and its correlations were studied in DC-sputtered Ni-Ti neutron supermirrors. Detector scans were carried out to observe off-specular neutron scattering in selected regions of the q space from (increasing bilayer thickness) normal- and (decreasing bilayer thickness) reverse-layer-sequence SMs. In-plane and out-of-plane roughness correlations are manifested in diffuse scatter plateaus and peaks which are interpreted in terms of resonant diffuse scattering. Distorted wave Born approximation simulations quantitatively reproduce the characteristic features of the measured detector scans with reasonable roughness correlation parameters, i.e. in-plane and out-of-plane correlation lengths, common interface roughness, and Hurst parameters. The different character of resonant diffuse scattering from normal- and reverse-layer-sequence SMs is qualitatively explained and systematized using quasi-kinematical considerations in terms of material and SM parameters. The total off-specular intensity of the supermirrors was found to be non-monotonic with respect to the specular reflectivity at the corresponding angle of incidence. [ABSTRACT FROM AUTHOR]

The four body Born distorted wave (BDW-4B) approximation with correct boundary condition is used for single electron transfer in He-He collision. The post and prior total cross sections are obtained in the energy range 10-1000 keV/amu and the post-prior discrepancy is estimated. The sensitivity of the results with respect to the choice of the final helium-like ground state wave function is evaluated through two different wave functions. The importance of the dynamic electron correlations is tested as a function of impact energy. Additional experimental data at higher impact energies is needed for a better assessment of the validity of the present theory. Graphical abstract: [ABSTRACT FROM AUTHOR]

Grazing-incidence small-angle X-ray scattering (GISAXS) is an important technique in the characterization of samples at the nanometre scale. A key aspect of GISAXS data analysis is the accurate simulation of samples to match the measurement. The distorted-wave Born approximation (DWBA) is a widely used model for the simulation of GISAXS patterns. For certain classes of sample such as nanostructures embedded in thin films, where the electric field intensity variation is significant relative to the size of the structures, a multi-slice DWBA theory is more accurate than the conventional DWBA method. However, simulating complex structures in the multi-slice setting is challenging and the algorithms typically used are designed on a case-by-case basis depending on the structure to be simulated. In this paper, an accurate algorithm for GISAXS simulations based on the multi-slice DWBA theory is presented. In particular, fundamental properties of the Fourier transform have been utilized to develop an algorithm that accurately computes the average refractive index profile as a function of depth and the Fourier transform of the portion of the sample within a given slice, which are key quantities required for the multi-slice DWBA simulation. The results from this method are compared with the traditionally used approximations, demonstrating that the proposed algorithm can produce more accurate results. Furthermore, this algorithm is general with respect to the sample structure, and does not require any sample-specific approximations to perform the simulations. [ABSTRACT FROM AUTHOR]

This paper evaluates the accuracy of the single-event (SE) and condensed-history (CH) models of electron transport in MCNP6.1 when simulating characteristic K α , total K (=K α + K β ) and L α X-ray emission from thick targets bombarded by electrons with energies from 5 keV to 30 keV. It is shown that the MCNP6.1 implementation of the CH model for the K-shell impact ionization leads to underestimation of the K yield by 40% or more for the elements with atomic numbers Z < 15 and overestimation of the K α yield by more than 40% for the elements with Z > 25. The L α yields are underestimated by more than an order of magnitude in CH mode, because MCNP6.1 neglects X-ray emission caused by electron-impact ionization of L, M and higher shells in CH mode (the L α yields calculated in CH mode reflect only X-ray fluorescence, which is mainly caused by photoelectric absorption of bremsstrahlung photons). The X-ray yields calculated by MCNP6.1 in SE mode (using ENDF/B-VII.1 library data) are more accurate: the differences of the calculated and experimental K yields are within the experimental uncertainties for the elements C, Al and Si, and the calculated K α yields are typically underestimated by (20–30)% for the elements with Z > 25, whereas the L α yields are underestimated by (60–70)% for the elements with Z > 49. It is also shown that agreement of the experimental X-ray yields with those calculated in SE mode is additionally improved by replacing the ENDF/B inner-shell electron-impact ionization cross sections with the set of cross sections obtained from the distorted-wave Born approximation (DWBA), which are also used in the PENELOPE code system. The latter replacement causes a decrease of the average relative difference of the experimental X-ray yields and the simulation results obtained in SE mode to approximately 10%, which is similar to accuracy achieved with PENELOPE. This confirms that the DWBA inner-shell impact ionization cross sections are significantly more accurate than the corresponding ENDF/B cross sections when energy of incident electrons is of the order of the binding energy. [ABSTRACT FROM AUTHOR]

In this paper, the reactions are revisited, with the goal of obtaining spectroscopic factors (SF) for the transition to the ground state of some residual nuclei, applying the distorted wave Born approximation (DWBA). The double-folding São Paulo Potential (SPP) was used to derive the distorted wave function in the entrance and exit channels. The derived SF are compared with the results of extensive shell model calculations showing a rather good agreement. [ABSTRACT FROM AUTHOR]

A novel microwave imaging approach to reconstruct the dielectric properties of targets hosted in partially known, noncanonical, scenarios is proposed and assessed. The method takes joint advantage of the recently introduced virtual experiments paradigm and exploits a new linear approximation developed within such a framework. Such an approximation implicitly depends on the unknown targets and, therefore, has a broader applicability as compared with the traditional distorted Born approximation. Being noniterative, the resulting distorted-wave inversion method is capable of quasi-real-time imaging and successfully images nonweak perturbations. The performances of the novel imaging method have been assessed with simulated data and validated experimentally against some of Fresnel data sets. [ABSTRACT FROM PUBLISHER]

Full finite-range (FFR) distorted-wave Born approximation (DWBA) method has been applied to analyse the angular distributions of cross-sections of the Ca(Li, d) Ti reaction at 28 MeV incident energy for the 22 transitions involving both the bound and unbound states of Ti by using the normal optical, Michel and molecular potentials. The extracted spectroscopic factors for the three optical potentials are compared with those of some previous studies of zero-range (ZR) calculations of the Ca(Li, d) Ti reaction using the normal optical potential. The χ values of all the levels are obtained for the three optical potentials to estimate the quality of the fits. Molecular and Michel potentials have been used for the first time to analyse the four-nucleon transfer reaction and it seems that the molecular potential fits the experimental data more satisfactorily for some of the states than the normal optical and Michel potentials. [ABSTRACT FROM AUTHOR]

Electron impact single ionization cross sections are theoretically investigated from the ionization threshold to 1000 eV for the levels belonging to the ground and two lowest excited configurations of ([ Ni ])4 s 2 4 p , 4 s 4 p 2 , and 4 s 2 4 d of Se 3+ using a detailed level-to-level distorted-wave formalism. The ionization cross sections of the two levels belonging to the configuration of 4 s 2 4 p are nearly equivalent and so are 4 s 2 4 d , whereas large difference is found for the eight levels of 4 s 4 p 2 . The theoretical results are utilized to analyze and interpret a recent experimental measurement for the single-ionization cross section of Se 3+ (Alna’washi et al., 2014). The population distributions existed in this experiment are deduced. Except for the levels of the ground configuration, there exist populations from levels of the excited configuration of 4 s 2 4 d . [ABSTRACT FROM AUTHOR]

We report an (e, 2e) study on interference effects in the spherically-averaged electron momentum density distributions of the five outermost molecular orbitals (MOs) of SF 6 , which are each constructed from the 2p atomic orbitals (AOs) on the F atoms. The (e, 2e) experiment was performed in the symmetric noncoplanar geometry and at an incident electron energy of 1.2 keV. Interference patterns for each MO have then been obtained by dividing the experimental data by distorted-wave-Born-approximation cross section for an isolated F 2p AO. A detailed analysis of the results shows that the interference patterns afford a rare opportunity to experimentally clarify symmetries of the MOs. Furthermore, it is demonstrated that they provide information about not only the molecular geometry but also the spatial orientation of the constituent AOs even for this relatively complicated molecule. [ABSTRACT FROM AUTHOR]

Formation of the weakly bound muonic molecule ( He 4 μ t ) 01 2 + in the excited rotational–vibrational state ( J , ν ) = ( 0 , 1 ) due to the three-body collision ( t μ ) 1 s + He 4 + He 4 is considered for the first time. It is assumed that the process occurs in T– 4 He gaseous mixture in thermal equilibrium containing thermalized muonic tritium atoms. The corresponding reaction rate is calculated in the frame of the distorted wave Born approximation (DWBA) method using the dipole approximation for the interaction of t μ + He 4 system with the incoming helium atom. The obtained formation rate (normalized to helium density equal to the liquid hydrogen density) increases with temperature from 7.8 ⋅ 10 6 s − 1 for 1000 K to 4.8 ⋅ 10 7 s − 1 for 3000 K. [ABSTRACT FROM AUTHOR]

We report the measurement of Ag K-shell ionization cross-section by electron impact in the range 50–100 keV and review the experimental data found in the literature. The sample consisted in a thin film of Ag evaporated on a thin C backing. The x-ray spectra generated by electron bombardment in the São Paulo Microtron were observed with a planar HPGe detector. The ratios between characteristic and bremsstrahlung x-ray yields were transformed to ionization cross sections with the help of theoretical atomic-field bremsstrahlung cross sections. The measured cross sections are compared with existing experimental values and calculations based on the semi-relativistic distorted-wave Born approximation. According to our experiment, the ratio of Ag K β to K α x-ray intensities is 0.2018(24). [ABSTRACT FROM AUTHOR]

Background: Traditionally, nucleon-nucleus optical potentials are made local for convenience. In recent work we studied the effects of including nonlocal interactions explicitly in the final state for (d,p) reactions, within the distorted wave Born approximation. Purpose: Our goal in this work is to develop an improved formalism for nonlocal interactions that includes deuteron breakup and to use it to study the effects of including nonlocal interactions in transfer (d,p) reactions, in both the deuteron and the proton channel. Method: We extend the finite-range adiabatic distorted wave approximation to include nonlocal nucleon optical potentials. We apply our method to (d,p) reactions on 16O, 40Ca, 48Ca, 126Sn, 132Sn, and 208Pb at 10, 20, and 50 MeV. Results: We find that nonlocality in the deuteron scattering state reduces the amplitude of the wave function in the nuclear interior, and shifts the wave function outward. In many cases, this has the effect of increasing the transfer cross section at the first peak of the angular distributions. This increase was most significant for heavy targets and for reactions at high energies. Conclusions: Our systematic study shows that, if only local optical potentials are used in the analysis of experimental (d,p) transfer cross sections, the extracted spectroscopic factors may be incorrect by up to 40% due to the local approximation. [ABSTRACT FROM AUTHOR]

We address the problem of the post-prior equivalence in inclusive breakup reactions induced by weakly bound nuclei. The problem is studied within the distorted-wave Born approximation (DWBA) model of Ichimura, Austern, and Vincent (Phys. Rev. C 32, 431 (1985)]. The post and prior formulas obtained in this model are briefly recalled and applied to several breakup reactions induced by deuterons and (,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 DWBA model of Udagawa and Taniura [Phys. Rev. C 24, 1348 (1981)] is also provided. [ABSTRACT FROM AUTHOR]

Energy levels, line strengths, oscillator strengths, radiative decay rates and fine structure collision strengths are presented for eight-time ionized iron (Ar IX). The atomic data are calculated with the AUTOSTRUCTURE code, where relativistic corrections are introduced according to the Breit–Pauli distorted wave approach. The calculations of atomic data for 37 fine-structure levels generated from seven configurations 2s 2 2p 6 , 2s 2 2p 5 (3s, 3p, 3d) and 2s 1 2p 6 (3s, 3p, 3d) of the Ne-like Ar ion are presented. Fine structure collision strengths for transitions from the ground and the first four excited levels are presented at four electron energies 75, 125, 175 and 250 Ryd. These atomic structure data with the available experimental and theoretical results are compared. [ABSTRACT FROM AUTHOR]

The reaction C()O was investigated through the direct -transfer reaction (7Li,t) at 28 and 34 MeV incident energies. We determined the reduced -widths of the sub-threshold 2 and 1 states of O from the DWBA analysis of the transfer reaction C(7Li,t)O performed at two incident energies. The obtained result for the 2 and 1 sub-threshold resonances as introduced in the -matrix fitting of radiative capture and elastic-scattering data to determine the E2 and E1 -factor from 0.01MeV to 4.2MeV in the center-of-mass energy. After determining the astrophysic factor of C()O S(E) with Pierre Descouvement code, I determined numerically the new reaction rate of this reaction at a different stellar temperature (0.06 Gk-2 GK). The C()O reaction rate at T is [7.21] × 10 cm3 s mol. Some comparisons and discussions about our new C()O reaction rate are presented. The agreements of the reaction rate below T between our results and with those proposed by NACRE indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. [ABSTRACT FROM AUTHOR]

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 l0Be(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 30Ne(d/p)3lNe 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. [ABSTRACT FROM AUTHOR]

We investigate the source of the discrepancy between R-matrix and distorted-wave (DW) collision strengths for J-J' = 0-0 transitions in Mg-like ions, for example 3s2 1S0-3p2 1S0, as reported previously. We find it to be due to the neglect of coupling, for example via 3s3p 1P1, as done by most DW codes. We have implemented an option to account for such coupling as a perturbation within the autostructure DW code. This removes the discrepancy of a factor ~10 and ~100 for Fe14+ and S4+, respectively, for such transitions. The neglect of coupling would have affected (to some degree) the atomic data for a few weak optically forbidden transitions in other isoelectronic sequences if they were calculated with DWcodes such as FAC and HULLAC. In addition, we compare the Fe14+ line intensities predicted with the R-matrix collision strengths against observations of solar active regions and flares; they agree well. For Fe14+, we suggest that the best density diagnostic ratio is 327.0/321.8 Å. [ABSTRACT FROM AUTHOR]

An inelastic excitation experiment was performed with a 12Be beam at 29 MeV/u on a carbon target. New resonances close to the respective cluster separation thresholds were observed in 12Be for the 4He + 8He and 6He + 6He decay channels, confirming the previously proposed molecular rotational bands. Using the model-independent angular correlation analysis, a 0+ spin parity is assigned to the remarkably large peak at 10.3 MeV in the 4He + 8He channel. A distorted wave Born approximation (DWBA) calculation was compared to the experimental differential cross section of this state, resulting in a largely enhanced monopole transition matrix element of 7.0 ± 1.0fm², in good agreement with the generalized two-center cluster model (GTCM) prediction assuming a preformed α-4n-α configuration. Together with the previously reported large cluster spectroscopic factor, the strong clustering in 12Be is well demonstrated. The detection focused on the most forward angles, by using a zero-deg telescope, is essential in the present measurement. [ABSTRACT FROM AUTHOR]

The effect of plasma environment on the 1s → nlm charge transfer, for arbitrary n, l, and m, in proton-hydrogen collisions has been investigated within the framework of a distorted wave approximation. The effect of external plasma has been incorporated using Debye screening model of the interacting charge particles. Making use of a simple variationally determined hydrogenic wave function, it has been possible to obtain the scattering amplitude in closed form. A detailed study has been made to investigate the effect of external plasma environment on the differential and total cross sections for electron capture into different angular momentum states for the incident energy in the range of 20-1000 keV. For the unscreened case, our results are in close agreement with some of the most accurate results available in the literature. [ABSTRACT FROM AUTHOR]

Relativistic distorted-wave collision strengths have been calculated for the 185 Δ n = 0 transitions with n = 2 in the 67 C-like ions with nuclear charge number Z in the range 26 ≤ Z ≤ 92 . The calculations were made for the six final, or scattered, electron energies E ′ = 0.03 , 0.08 , 0.20 , 0.42 , 0.80 , and 1.40 , where E ′ is in units of Z eff 2 Ry with Z eff = Z − 4.17 . In addition, electric dipole oscillator strengths are provided. In the present collision-strength calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in previous work by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 63 (1996) 275]. In that earlier work, collision strengths were also provided for the same 185 Δ n = 0 transitions in C-like ions, but for the more limited list of 46 ions with Z in the range 9 ≤ Z ≤ 54 . The collision strengths covered in the present work, particularly those for optically allowed transitions, should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 63 (1996) 275] and are presented here to replace those earlier results. [ABSTRACT FROM AUTHOR]

Relativistic distorted-wave collision strengths have been calculated for the 16 Δ n = 0 optically allowed transitions with n = 2 in the 67 O-like ions with nuclear charge number Z in the range 26 ≤ Z ≤ 92 . The calculations were made for the four final, or scattered, electron energies E ′ = 0.20 , 0.42 , 0.80 , and 1.40, where E ′ is in units of Z eff 2 Ry with Z eff = Z − 5.83 . In the present calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in previous work by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 82 (2002) 357]. In that earlier work, collision strengths were also provided for O-like ions, but for a more comprehensive data set consisting of all possible 45 Δ n = 0 transitions, six scattered energies, and the 79 ions with Z in the range 14 ≤ Z ≤ 92 . The collision strengths covered in the present work should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 82 (2002) 357] and are presented here to replace those earlier results. [ABSTRACT FROM AUTHOR]

The astrophysical factor of 8B(p,γ)9C at zero energy, S18(0), is determined by a three-body coupled-channels analysis of the transfer reaction 8B(d,n)9C at 14.4 MeV/nucleon. Effects of the breakup channels of d and 9C are investigated with the continuum-discretized coupled-channels method. It is found that, in the initial and final channels, respectively, the transfer process through the breakup states of d and 9C, its interference with that through their ground states in particular, gives a large increase in the transfer cross section. The finite-range effects with respect to the proton-neutron relative coordinate are found to be about 20%. As a result of the present analysis, S18(0) = 22 ± 6 eV b is obtained, which is smaller than the result of the previous distorted-wave Born approximation analysis by about 51%. [ABSTRACT FROM AUTHOR]

The angular distributions of the 12C(11B,11B)12C and 12C(11B,12C)11B reactions have been measured at an incident energy of 50 MeV by using the high resolution Q3D magnetic spectrometer of the HI-13 tandem accelerator at China Institute of Atomic Energy, Beijing. The optical potential parameters of the 11B + 12C system are determined by fitting the angular distribution of the elastic scattering and then used to predict the cross sections of the elastic transfer reaction leading to the ground state in l 2C based on distorted-wave Born approximation (DWBA) analysis. Taking into account the interference between the elastic scattering and the elastic transfer processes, the proton spectroscopic factor of the, 12C ground state is extracted to be 2.15 ± 0.23 by constraining the geometrical parameters r0 and a using the rms radius of the valence proton in the 12C ground state. [ABSTRACT FROM AUTHOR]

Time reversal invariance violating (TRIV) effects in neutron transmission through a nuclear target are discussed. We demonstrate the existence of a class of experiments that are free from false asymmetries. We discuss the enhancement of TRIV effects for neutron energies corresponding to p-wave resonances in the compound nuclear system. We analyze a model experiment and show that such tests can have a discovery potential of 10²-104 compared to current limits. [ABSTRACT FROM AUTHOR]

The 9Be(18O,17O)10Be reaction has been studied at an incident energy of 84 MeV, and the ejectiles have been detected at forward angles. The 10Be excitation energy spectrum has been obtained up to about 18 MeV, and several known bound and resonant states of l0Be have been identified. Calculations that describe the interaction of the neutron removed from the 18O projectile with the 9Be target by means of an optical potential with a semiclassical approximation for the relative motion account for a significant part of the 10Be continuum. Two parametrizations of the optical-model potential for the system n-9Be have been used and compared. [ABSTRACT FROM AUTHOR]