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).     

Inelastic scattering of 185 MeV protons from Mg and Al

A magnetic spectrometer was used for the energy analysis of protons scattered from targets of magnesium (natural isotopic composition) and aluminium. The mean energy of the incident protons in the targets was 185 MeV. A total energy resolution of 350 keV (FWHM) was achieved, which made possible the observation of the excitation of a large number of discrete levels. Energy spectra were measured in the angular region of 4° to 40° (lab system).

The results are presented partly in the form of tables giving measured excitation energies and maximum cross sections for resolved levels and partly in the form of graphs of angular distributions of the differential cross sections.

A qualitative discussion of the results is given in terms of the multipolarities of the transitions involved and comparisons are made with similar results from other experiments in inelastic scattering and in a few cases with theoretical predictions.     

Polarization in the inelastic scattering of 185 MeV protons

The polarizations produced in the inelastic scattering of 185 MeV protons exciting the lowest octupole states in ¹²C and ²⁰⁸Pb are measured. The data together with earlier similar measurements for ⁴⁰Ca and ⁹⁰Zr are compared with existing theoretical models. The inclusion of a deformed spin-dependent interaction of the full Thomas form in the DWBA amplitude is found to considerably improve the theoretical fits to the data. For ¹²C, however, the DWBA fit is found to be inferior to that obtained using DWIA. The strong absorption model is found to give qualitatively good fits to the data for the heavier nuclei but again fails in the ¹²C case.     

Optical-model analysis of the elastic scattering of 100 MeV protons from Mg and Si

Elastic scattering differential cross sections for the interaction of 100 MeV protons with ²⁴Mg and ²⁸Si have been measured using a high-resolution Ge(Li) spectrometer to resolve the inelastic scattering contribution to the elastic peak. The results have been analysed using the conventional optical model, and the experimental differential cross sections and total reaction cross section are excellently reproduced. The results agree with previous analyses of the elastic scattering of 100 MeV protons on 1p shell nuclei in that no set of geometric parameters can provide a quantitative fit to both nuclei. It is observed, however, that the fluctuations of the optical-model parameters for optimum fits are decreased over the fluctuations observed for the 1p shell nuclei. The present results combined with previous optical-model analyses on ²⁴Mg and ²⁸Si at 50 MeV and 40 MeV respectively, are found to be consistent with an energy dependence of dV/dE ≈ −0.3 for the depth of the real central potential in agreement with other, more extensive, investigations of the energy dependence for protons elastically scattered from ¹⁶O and ⁴⁰Ca.     

Elastic and inelastic scattering of protons from Li between 25 and 45 MeV

The elastic and inelastic scattering of protons from ⁶Li has been studied at incident energies of 25.9, 29.9, 35.0, 40.1 and 45.4 MeV. The 2.18 MeV (3⁺, T = 0) first excited state of ⁶Li was found to be strongly excited, but the 3.56 MeV (0⁺, T = 1) second excited state was quite weakly excited. Angular distributions for excitation of the 2.18 MeV level were measured at all five energies, while angular distributions for excitation of the 3.56 MeV level were extracted only at 25.9 and 45.4 MeV. To test the applicability of the optical model for the scattering of protons from such a light nucleus the elastic scattering angular distributions have been analyzed using the eleven-parameter search code SEEK. Available polarization angular distributions were included in the analysis. Reasonable fits to the data have been obtained with an average geometry potential. Theoretical estimates of the real part of the optical potential and the inelastic scattering differential cross sections have been made using the microscopic model for proton-nucleus scattering. Both phenomenological and realistic forces have been considered and the necessary nuclear transition densities have been extracted from experimental elastic and inelastic electron scattering data. An estimate of a possible spin-spin term in the optical potential has also been made.     

Elastic scattering of 100 MeV protons and systematic optical model analysis

Using a Ge(Li) total energy detector the elastic scattering of 100 MeV protons from ⁵⁸Ni, ⁹⁰Zr, ¹²⁰Sn and ²⁰⁸Pb has been measured. Optical model fits with $\text{x}{}^2\text{N}$ of order unity have been made. The parameters of these fits varied systematically with A enabling the isospin dependence of the real part of the potential and its volume integral to be deduced. The limitations of the conventional optical model analysis in the case of ⁵⁸Ni are illustrated and discussed.     

Proton polarization observables for the elastic and inelastic scattering of 500 MeV protons from Ca and Pb

Measurements for the elastic and inelastic scattering of 500 MeV protons from ⁴⁰Ca and ²⁰⁸Pb at small momentum transfers are reported. The induced proton polarization P and the spin rotation parameter Q were measured for the elastic scattering. The spin rotation parameters D_SS′, D_SL′, D_LL′, d_LS′ and the induced polarization P were measured for transitions to the 3⁻(3.37 MeV) and 5⁻(4.48 MeV) states in ⁴⁰Ca and the 3⁻(2.61 MeV) state in ²⁰⁸Pb. Comparisons of the data with the theoretical calculations were carried out in the framework of nonrelativistic and relativistic approaches. We extracted the spin-up and spin-down channels for the elastic scattering cross sections and found that predictions of the relativistic and nonrelativistic approaches agree well with the spin-up channel data and differ considerably in the spin-down channel.     

Reaction cross sections for 65 MeV protons on targets from 9Be to 208Pb

Reaction cross sections for 65.5 MeV protons have been measured for ⁹Be, ¹²C, ¹⁶O, ²⁸Si, ⁴⁰Ca, ^58,60Ni, ^{112.116.118.120.124}Sn, and ²⁰⁸Pb. The results are compared with optical model predictions using relativistic global potentials.     

The elastic scattering of deuterons by9Be from 1.00 to 2.20 MeV

The absolute differential cross section for the elastic scattering of deuterons by beryllium has been investigated for incident energies from 1.0 to 2.2 MeV. An excitation curve measured at 90 ° (lab) showed no sharp resonances. The ratio of the differential cross section to that predicted by Rutherford's formula was found to increase gradually with energy. Angular distributions from 40 ° to 160 ° were measured in 200 keV steps from 1.0 to 2.2 MeV and optical model analysis of these data were made. Good fits were obtained with a volume-absorption potential with a real well depth in the region of 20 MeV.     

Coincident proton emission from the continuum induced by 200 MeV protons on 12C

Spectra of coincident protons resulting from incident protons at 200 MeV on ¹²C are presented. Agreement between the experimental data and calculated distributions supports the expectation that at 200 MeV the reaction mechanism is dominated by an initial nucleon-nucleon interaction, followed by rescattering of the struck nucleon which behaves as an intranuclear projectile.     

Polarization of protons from the Be(d,p)Be reaction at Ed = 12.0 MeV

The polarization of protons from the ⁹Be(d,p)¹⁰Be reaction at E_d = 12.0 MeV was measured for the ground state and first excited state transitions. The results obtained are compared with the predictions of DWBA theory. It was found that better fits to the experimental data can be obtained using volume absorption in the distorting potential of the deuteron elastic channel. A comparison of the present polarization data with the vector analysing power for the same reaction and the same incident deuteron energy has also been made.     

States in Be studied through the reaction B(p, α)Be with 40 MeV protons

Spectroscopy of the α- and τ-particles from 40 MeV proton bombardment of ¹¹B reveals transitions to ⁸Be states up to 19 MeV. The ratio of excitation of the 16.6 MeV state to the 16.9 MeV state is 2.3 ± 0.4. The ⁸Be(4⁺) state is found at 12.5 MeV with a width of 4.0 ± 0.5 MeV.     

Analysis of 185 MeV proton scattering from6Li

The internal bremsstrahlung ofα-particles emmited byα-decaying nuclei is not responsible for the internal pair production inα-decay. The probability of this process is of the order of 10^?20, in strong disagreement with previous resuls. It is suggested that the internal pair production inα-decay is due to excited states in nuclei. For the probability of this process a value of the order of 10^?12 has been obtained.     

Magnetic elastic electron scattering from 3Be and 13C

Elastic scattering through 180° from ⁹Be, ¹²C and ¹³C targets has been observed for electrons of 35 to 90 MeV. Magnetic scattering cross sections for ⁹Be and ¹³C have been obtained by subtracting charge scattering as deduced from the scattering from the spin-zero nucleus ¹²C. Theoretical shell model predictions for the magnetic cross sections are derived for (1s)⁴(1p)^A?4 configurations and various coupling schemes. Both harmonic oscillator and Woods-Saxon radial wave functions are used. A comparison of our results with magnetic cross sections calculated in DWBA yields magnetic rms radii $\text{〈r}{}^2\text{〉}{}_{\mathrm{<mtext>M</mtext>}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 3.2 ± 0.3}\text{fm}$ and $\text{〈r}{}^2\text{〉}{}_{\mathrm{<mtext>M</mtext>}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 3.3 ± 0.3}\text{fm}$ for ⁹Be and ¹³C. For ¹³C a combined flt to our low-q data and to earlier high-q data, yields $\text{〈r}{}^2\text{〉}{}_{\mathrm{<mtext>M</mtext>}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 3.4 ± 0.1}\text{fm}$ and a strong preference for intermediate coupling (IC) wave functions. Magnetic dipole scattering from ⁹Be is also close to the IC prediction, as deduced from a fit to our data and earlier high-q data. The fitted value of the octupole moment $\text{Ω = 5±1 μ}{}_{\mathrm{<mtext>N</mtext><mtext>fm</mtext>}}{}^1$ can only be explained by a deformation of the average nuclear potential. The radial size $\text{〈r}{}^2\text{〉}{}_{\mathrm{<mtext>1</mtext><mtext>p</mtext>}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 2.85 ± 0.05}\text{fm}$ for the 1p radial wave function is in agreement with both the ⁹Be and ¹³C data.     

Elastic scattering of positive pions from 12C at 29 MeV

The elastic scattering cross section of positive pions at 29 MeV scattered from ¹²C has been measured at scattering angles between 15° and 150°. The cross section drops to a sharp minimum at about 40° and then rises to about 4 mb/sr at back angles.     

The elastic and inelastic scattering of 30.5 MeV protons by24Mg

Measurements of the differential cross sections for the elastic scattering of 30.5 MeV protons by ²⁴Mg and for the inelastic scattering to the 1.37, sum of 4.12 and 4.23, 5.22 and 6.0 MeV states are reported. Optical model fits to the elastic data, a distorted wave calculation for the first excited state, and coupled channel calculations are also presented.     

π+ and π− scattering from 12C at 150 MeV

High-resolution elastic and inelastic data were obtained for π⁺ and π^? scattering ¹²C. Spectra were taken with the SIN pion spectrometer at 148 MeV over a wide angular range.     

Spin-orbit deformation in the inelastic scattering of polarized protons from12C and16O

Analyzing powers and cross sections for elastic and inelastic scattering of 20, 30 and 40MeV polarized protons from¹²C and¹⁶O have been analyzed in the coupled-channels collective model using the full Thomas deformed spin-orbit term. It is clear from this analysis that the spin-orbit deformation is energy dependent.