Prior-form DWBA analysis of (3He,pd) elastic breakup at 90 MeV

Proton-deuteron coincident cross sections in ¹²C,⁵¹V,⁹⁰Zr(³He,pd) elastic breakup at 90 MeV have been calculated within the framework of the prior-form distorted-wave Born approximation (DWBA). Sufficient convergence of the calculations was obtained by including the pd relative angular momenta up to l = 4. The calculations reproduced the general trend of the coincident energy spectra and the angular correlation data, though deficiencies of the calculations were seen at some angles. The peripheral feature of the (³He, pd) elastic breakup is discussed from the angular momentum dependence of the transition amplitude.     

Elastic and inelastic scattering of 185 MeV protons from 12C

The polarization of 185 MeV protons in elastic scattering and in the excitation of the 2⁺ state at 4.44 MeV and the 0⁺ state at 7.65 MeV in ¹²C has been measured in the angular region 2°–60°. Optical model calculations are performed for the elastic scattering. Angular distributions for the inelastic scattering from the 2⁺ state at 4.44 MeV and the 3^? state at 9.64 MeV are calculated in the distorted-wave impulse approximation (DWIA) as well as in the distorted-wave Born approximation (DWBA).     

Coupling effects of resonant and discretized non-resonant continuum states in 4He + 6Li scattering at 10 MeV/A

Alpha-particle scattering from the resonant (3 ₁ ⁺ ) and non-resonant continuum states of ⁶Li is studied at incident energy 10 MeV/A. The α + d breakup continuum part within the excitation energy E _ex = 1.475–2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states.     

Coupling effects of resonant and discretized non-resonant continuum states in4He +6Li scattering at 10 MeV/A

Alpha- particle scattering from the resonant (3 ₁ ⁺ ) and non-resonant continuum states of⁶Li is studied at incident energy 10 MeV/A. Theα+d breakup continuum part within the excitation energyE _ex=1.475–2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states.     

Search for isovector giant monopole resonances via the Pb(3He,tp) reaction

The (nat)Pb(3He,tp) reaction at E(3He) = 177 MeV was studied to identify 2Planck's over 2piomega isovector monopole strength in Bi isotopes. Monopole strength was found in the region -45相似文献   

Analysis of <Emphasis Type="Italic">p</Emphasis><Superscript>10</Superscript>B scattering within Glauber theory

The differential cross sections for p ¹⁰B 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 (1s, 1p) 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 ¹⁰B scattering are adequately described in the region forward scattering angles.     

Electron impact ionization cross sections of beryllium and beryllium hydrides

We report calculated electron impact ionization cross sections (EICSs) for beryllium (Be) and some of its hydrides from the ionization threshold to 1 keV using the Deutsch-Märk (DM) and the Binary-Encounter-Bethe (BEB) formalisms. The positions of the maxima of the DM and BEB cross sections are very close in each case while the DM cross section values at the maxima are consistently higher. Our calculations for Be are in qualitative agreement with results from earlier calculations (convergent close-coupling, R matrix, distorted-wave and plane-wave Born approximation) in the low energy region. For the various beryllium hydrides, we know of no other available data. The maximum cross section values for the various compounds range from 4.0 × 10^?16 to 9.4 × 10^?16 cm² at energies of 44 to 56 eV for the DM cross sections and 3.0 × 10^?16 to 5.4 × 10^?16 cm² at energies of 40.5 to 60 eV for the BEB cross sections.     

Tagged-photon events in polarized deep inelastic scattering

Deep inelastic scattering events of a longitudinally polarized electron by a polarized proton with a tagged collinear photon radiated from the initial-state electron are considered. The corresponding cross section is derived in the Born approximation. The model-independent radiative corrections to the Born cross section are also calculated. The obtained result is applied to the elastic scattering.     

Adiabatic treatment of inelastic deuteron-nucleus scattering

Inelastic scattering of 80 MeV deuterons from ⁵⁸Ni and ¹²⁰Sn is analyzed in terms of an adiabatic coupled-channels Born approximation (ACCBA) method. The ACCBA method is a practical means to treat deuteron plus nucleus as a three-body system. Inclusion of the breakup modes significantly reduces the inelastic cross section. The significance of considering both the s-wave and d-wave breakup modes is pointed out.     

Neutron hole states in 138La and 140Pr

Protons accelerated to 30 MeV were used to investigate low-lying states in the odd-odd nuclei ¹³⁸La and ¹⁴⁰Pr with (p, d) reactions. The elastic scattering of 30 MeV protons and 23 MeV deuterons was also studied to determine optical potentials. Experimental angular distributions are compared with distorted-wave Born approximation calculations to extract spin, parity, and spectroscopic factors for levels up to 432 keV of excitation in ¹⁴⁰Pr and 530 keV in ¹³⁸La. Comparisons with the simple shell-model predictions and extended shell-model calculations are presented. The ¹⁴⁰Pr levels appear experimentally to have an almost pure particle-hole structure whereas the ¹³⁸La levels exhibit substantial mixing.     

Coupling to the elastic channel in electron impact spectroscopy: A simple second born model and its application to excitation of the 61P1 state of mercury and to the excitation of molecules

The matrix element in the infinite channel close coupling approximation responsible for coupling to the elastic channel in electron impact inelastic encounters is investigated. The contribution from the imaginary part of the energy denominator in the elastic coupling matrix element for dipole allowed transitions is shown to yield large angle differential cross sections in good agreement with experiment. This coupling mechanism predicts that the shape of the inelastic differential cross section will be dominated by the shape of the elastic cross section in the large angle high energy limit. In fact the coupling matrix element exhibits a dependence on incident energy, k², and momentum transfer, K, of the form 1/kK² which is in agreement with the theoretical predictions of Huo and means that in the limit of high incident energy the non-first-Born elastic coupling will dominate the angular dependence of the inelastic differential cross section at large scattering angles. In the case of molecular electron impact spectra it is shown that the analog of the Massey—Moore coherence features depending on the symmetry of the states involved in the excitation process will also occur in the coupling contribution. It is suggested that this new mechanism for producing coherent features in inelastic differential cross sections may be the explanation of the coherent features observed experimentally by Karle and Swick.It can be concluded on the basis of the results obtained here that the coupling to the elastic cross section provided by the imaginary contribution from the second Born energy denominator is sufficient to explain presently available experimental data on the large angle differential cross section and spin polarization. The simple coupling model was found to be inadequate to explain the small angle differential cross section in the range 10° < θ < 30° even at incident energies as high as 400 eV. The calculations also showed significant differences between first and second Born calculations at zero scattering angle. No conclusion can be drawn about this observation as all the omitted terms should make significant contributions in the small angle region. It is important to again emphasize that the large angle scattering even in the limit of high incident electron energy will be completely dominated by the coupling to the elastic channel^{7, 11}. On the basis of this work it appears that the coherent structure in the large angle inelastic differential cross section observed by Swick and Karle^{12, 13} at incident electron energies in the keV region may well be due to coupling to the elastic channel.     

Sub-barrier interaction between deuterons and 58, 62Ni nuclei

The interaction between deuterons and ^{58, 62}Ni nuclei at energies of E _d = 3.5, 4.5 and 5.16 MeV is investigated. The discrepancy between measured scattering elastic cross section and the Rutherford ones is higher than the value calculated theoretically by considering deuterons polarization and Coulomb breakup. Analysis of measured cross section of ^{58, 62}Ni(d, p) reaction and the results of calculation of Coulomb breakup cross section integrated over neutron emission angles shows that that the dominant mechanism of proton formation is the reaction of neutron transfer to the target nucleus.     

Energy dependence of11Li dissociation cross section

The Coulomb breakup cross section of¹¹Li is calculated as a function of its bombarding energy. Comparison is made to cross sections at 790 MeV/nucleon and 30 MeV/nucleon. Low energy reactions on a high-Z target show a greatly enhanced Coulomb breakup cross section that is more sensitive to the distribution of dipole response strength than high energy reactions thus providing more structure information.     

Deconstructing <Superscript>1</Superscript>S<Subscript>0</Subscript> nucleon-nucleon scattering

A distorted-wave method is used to analyse nucleon-nucleon scattering in the ¹ S ₀ channel. Effects of one-pion exchange are removed from the empirical phase shift to all orders by using a modified effective-range expansion. Two-pion exchange is then subtracted in the distorted-wave Born approximation, with matrix elements taken between scattering waves for the one-pion exchange potential. The residual short-range interaction shows a very rapid energy dependence for kinetic energies above about 100MeV, suggesting that the breakdown scale of the corresponding effective theory is only 270MeV. This may signal the need to include the D \Delta -resonance as an explicit degree of freedom in order to describe scattering at these energies. An alternative strategy of keeping the cutoff finite to reduce large, but finite, contributions from the long-range forces is also discussed.     

Final-state interaction between nucleons in elastic deuteron breakup within the three-body potential model

The diffraction deuteron breakup has been investigated within the three-body potential model, where the final-state interaction between nucleons is described nonperturbatively with respect to the pn potential. The triple differential cross section of the (d, pn) reaction on ⁴⁰Ca at deuteron energies of 140, 200, and 270 MeV and small emission angles of nucleons have been calculated for two schemes of the kinematically complete experiment. Noneikonal and nonadiabatic corrections to the cross section are small and do not change the shape of the peak in the proton energy spectra.     

Scattemng of 14.1 MeV neutrons from 209Bi

Differential cross sections for the elastic and inelastic scattering of 14.1 MeV neutrons from ²⁰⁹Bi have been measured with a time-of-flight system which had an energy resolution of 650 keV. For elastic scattering from ²⁰⁹Bi, an optical-model analysis gave the best-fit potential parameters. The absolute cross sections for excitation of collective (2.66 and 4.36 MeV) states are reproduced by the results of distorted-wave calculations under the assumption of a core (²⁰⁸Pb) excitation model using deformation parameters obtained from (p, p') reactions.     

CDCC Approaches and Roles of Closed Channels in d-Nucleus Reactions

The effect of deuteron breakup in d-nucleus reaction is treated with the continuum discretized coupled channels (CDCC) approach, and the effects on the total reaction cross sections and elastic scattering angular distributions are studied by comparing the calculations of CDCC and spherical optical model with our global deuteron optical potential [Phys. Rev. C 73 (2006) 054605] below 200 MeV, for target nuclei ranging from ¹²C to ²⁰⁸Pb. The contributions from the closed channels to the total reaction and breakup cross sections, and angular distributions of elastic scattering are also seriously discussed.     

Cross Section Enhancement in pd Reactions at Higher Energy

Cross sections of pd breakup reaction at E _p = 250 MeV were measured systematically in single-proton detection and in two-proton coincidence detection. Measured cross section is up to two times higher than calculated ones. The enhancement of breakup cross section is similar to reported enhancement in pd elastic scattering cross section. Origins of this enhancement are discussed.