High momentum transfer approach to inelastic electron scattering on nuclei and model-independent description of nuclear transition densities

A method of approximating the DWBA transition amplitude at higher momentum transfers is given. It leads to quantitative agreement with the DWBA values, combined with a considerable saving of computing time. The method permits model-independent analyses of inelastic data at higher momentum transfers. The influence of uncertainties in the ground state charge density on the inelastic cross section is studied and found to be negligible. Regardless of the magnitude of Coulomb distortions, the multipole moments B(τ; L, q) are shown to be model-independent quantities for those values of q which lie in the region of measured momentum transfers.     

Absorption cross sections for antiprotons on carbon, aluminum and copper at 485 and 597 MeV/c

Absorption cross sections for antiprotons on C, Al and Cu have been measured by a transmission method at 485 and 597 MeV/c. Nuclei are shown to be black to antiprotons at these momenta. Using the available data up to 280 GeV/c, the momentum dependence of the absorption cross sections is investigated. Empirically, a simple expression σ_abs = γ(p/p₀)^−β, with β and γ constants and p₀ = 1 GeV/c, gives a good account of the data in a remarkably wide momentum range, 0.5–280 GeV/c.     

Hypernuclear production in the (K, π) reaction

Cross sections for the production of hypernuclei were measured in the reaction A(K⁻, π⁻) _ΛA. on light and heavy nuclear targets, using a separated K⁻ beam at the CERN Proton Synchrotron. The pions were detected in the forward direction. The results are compared with cross sections calculated under the assumption that the reaction took place on a single neutron. The good agreement between the measured and the calculated cross sections justifies the use of the (K⁻, π⁻) reaction in order to obtain spectroscopic information on hypernuclei.     

Coulomb and nuclear excitation effects on 16O scattering from samarium isotopes

Elastic scattering of ¹⁶O on ^{148, 150, 152}Sm isotopes and inelastic scattering leading to the first 2⁺ state for the three isotopes and the 4⁺ state for ¹⁵²Sm have been measured at several energies in the vicinity of the Coulomb barrier. The whole set of data was reproduced at forward angles with an effective potential taking into account Coulomb excitation and in the full angular range by CCBA calculations including separate nuclear and Coulomb deformations.     

Determination of matter densities of Ca isotopes by 600 MeV and 1 GeV proton elastic scattering

The 600 MeV and 1 GeV data of proton elastic scattering on ^40,42,44,48Ca have been analyzed in the framework of the Glauber model. The matter distributions are extracted from the data in an approximately model-independent form based on a Fourier series expansion. A similar method is used to deduce directly the ⁴⁸Ca⁴⁰Ca neutron density difference.     

Transition charge densities of low-lying collective states in even Zn isotopes

The inelastic electron scattering cross sections for the quadrupole transitions to the 2₁⁺ and 2₂⁺ states in the even Zn isotopes ⁶⁴Zn, ⁶⁶Zn and ⁶⁸Zn and for the hexadecapole transition to the 4⁺₁ state in ⁶⁴Zn have been measured in a momentum transfer range up to q = 2.2 fm^?1. In the frame-work of the vibrational model these states are considered as one- and two-quadrupole-phonon states. The measurements are characterized by high statistical accuracy and by an overall resolution of δE/E₀ = 10^?3 which permitted separation of almost all members of the two-phonon triplet. The measured cross sections are analyzed with phenomenological models as well as with a Fourier-Bessel expansion of the transition charge density. The latter analysis yields realistic error bands for the transition charge densities and model-independent values for the reduced transition probabilities and transition radii.     

Measurement of nuclear deformation parameters from elastic and inelastic scattering of α and 3He ions on Te isotopes

Cross sections for the elastic scattering of ⁴He by ^{122, 124, 126, 128}Te and ³He by ¹²⁸Te and for inelastic transitions to the lowest 2⁺ states of Te isotopes were measured for several scattering angles at bombarding energies in the vicinity of the Coulomb barrier. The data were analyzed in the framework of the optical model and the DWBA from which optical potential and deformation parameters were extracted. A detailed study of the fit procedure is presented with emphasis on the significance of the extracted parameters and the correlations among them.     

Scattering of polarized protons by iron and nickel isotopes

Elastic and inelastic scattering of polarized protons (E = 17.2, 20.4, 24.6 MeV) by ^{54, 56}Fe and ^{58, 60, 62} Ni have been investigated. Most data can be readily accommodated by standard optical-model and DWBA procedures, including full Thomas coupling. The 2⁺₁ state (1.41 MeV) in ⁵⁴Fe is peculiar because the inelastic scattering data require deformation parameters for the central and spin-orbit parts of the nuclear potential that differ by a factor 2 to 3; moreover, this anomaly shows a marked energy dependence.     

Isobaric analogue resonances in proton scattering on Ba

Extensive experimental data for the resonance scatttering of protons to the ground state and first excited state in ¹³⁸Ba are presented. A Breit Wigner analysis with a background term of the form Σ_n(a_n/Eⁿ) is performed and the extracted background function is compared with optical-model calculations using the parameters given in a detailed investigation by Perey. Neutron spectroscopic factors calculated in different ways from this data are compared with the corresponding factors from (d, p). An accurate determination of resonance energies for the first two resonances reveals a deviation from a constant Coulomb shift of the order of 10 keV.     

Neutron densities from 1 GeV proton scattering

Neutron densities are obtained from the recent Saclay 1 GeV proton scattering data for the Ca and Ni isotopes. Three parameter Fermi distributions are used for both protons and neutrons. The scattering process is described using the impulse approximation, including the spin-orbit contribution.     

Model dependence of charge densities determined from electron scattering

A new method is used to analyze recent experiments on electron scattering on ³He in the high momentum transfer region. The accuracy of the new measurements is very high so that the charge density can be determined with much higher accuracy than before. We find that further reduction of the error in charge density can only be achieved by a more accurate measurement of the region 3 < q < 6 fm^?1. Continuing the previous work of Hetherington and Borysowicz, a very useful approximate relation is derived between the error of charge density and the error of measurements of form factor. We find that linear expansion methods lead to similar results as the present method. They require, however, stronger asymptotic assumptions about ?(r).     

Intermediate structure in the neutron scattering cross sections of iron

Differential cross sections for the Fe(n, n), (n, n′), (n, n′γ) reactions were measured at incident energies between 1.43 and 2.15 MeV. Structure with intermediate widths was observed. The result was analysed by the doorway-state model, and the widths of the assumed doorway states were obtained. Spin and parity assignment of $\text{3}\text{2}$(⁺) was made to a doorway-state resonance at about 2.0 MeV.     

Inelastic proton scattering on Neutron-Rich sulphur isotopes

The proton scattering on unstable³⁸S nuclei has been measured in inverse kinematics by using a³⁸S secondary beam at 39 MeV/nucleon. The first 2⁺ state is seen at 1.2 MeV excitation energy and its angular distribution is extracted. Optical and folding model calculations are compared with the elastic and the 2 ₁ ⁺ angular distributions and the β₂ value is determined to be 0.35±0.04. This value is compared with the corresponding result from a Coulomb excitation measurement and theM _n/M_p value is extracted.     

Intermediate energy nucleon-deuteron scattering theory

We examine Sloan's conclusion for an S-wave separable model, that terms of the multiple-scattering series beyond single scattering contribute only to S- and P-wave amplitudes. Comparison of experiment with the present calculation at 146 MeV shows that these conclusions are applicable to nucleon-deuteron scattering.     

The maximum entropy determination of nuclear densities of calcium isotopes from elastic scattering of alpha particles

Radial moments of the real part of the optical potential for elastic scattering of 104 MeV α particles are used as constraints, in determining the nuclear density of maximal entropy. The potential is related to the density by the folding model.     

Gamma-gamma energy correlations and moment of inertia in light Xe isotopes

High-spin properties of even ^118–122Xe isotopes have been studied in experiments when a 118 MeV ¹²C beam impinged on ¹¹⁴Cd and ¹¹⁶Cd targets. The γ-rays emitted following the reactions were detected by six NaI(Tl) counters. The coincidence events from the counters were sorted into a two-dimensional matrices, from which the energy-correlation spectra were extracted. From the energy correlation spectra the quantities of the collective moment of inertia $\text{I}$⁽²⁾ are deduced and compared with data obtained for the same nuclei in previous experiments, as well as with results from theoretical studies.     

A systematic semi-microscopic analysis of the scattering of oxygen isotopes

A semi-microscopic theory for the scattering of nuclei near closed shells is discussed in detail and applied to the bulk of the presently available experimental data. The results generally indicate that the single-folding model can be used to extrapolate the effective interactions for heavy-ion scattering away from closed-shell systems. We particularly discuss the importance of the imaginary part of the valence interaction and the effects of higher-order reorientation and two-step transfer processes.