The elastic scattering of protons by 16O in the energy range 16–30 MeV

doi:10.1016/0375-9474(69)90717-9

Nuclear Physics A

Volume 132, Issue 3, 4 August 1969, Pages 548-560

https://doi.org/10.1016/0375-9474(69)90717-9 Get rights and content

Abstract

For proton-oxygen elastic scattering measurements are presented of differential cross sections at eight energies between 19.8 and 30.5 MeV, polarization at 19.8, 20.4, 20.8, 21.4, 22.1 and 30.3 MeV and the integrated excitation function at backward angles from 16.0 MeV to 30.6 MeV. The latter shows anomalies at E_p = 17.6, 20.4, 21.8, 23.3, 26.7 and 28.4 MeV. The data are analysed in terms of optical-model plus compound-nucleus-scattering amplitudes. A fit to experimental results is presented assuming contributions from four resonances at energies 17.6, 20.4, 26.7 and 28.4 MeV with J^π assignment $52^{t-}$ , $32^{−} (32^{+})$ , and $32^{−}$ and $52^{−}$ , respectively.

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On the energy dependence of the real central optical potential for proton-nucleus scattering
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The energy dependence of the real central optical potential in the energy range 25–1000 MeV has been determined from optical model analyses of p+¹²C, p+¹⁶O, p+²⁷Al, p+⁴⁰Ca and p+²⁰⁸Pb elastic scattering data. The volume integral and the strength can be represented by a relation linear in the incident energy only if a limited energy range is chosen. When the energy range 25–1000 MeV is considered a logarithmic energy dependence gives a better representation of the phenomenological results, especially for the light nuclei.
Proton scattering from 9Be between 6 and 30 MeV and the structure of 9Be
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Differential cross-section excitation functions at lab scattering angles 86.9°, 120.0°, 140.0° and 160.0° were measured for ⁹Be(p, p_o)⁹Be, ⁹Be(p, p₂)⁹Be and ⁹Be(p, d₀)⁸Be at proton lab energies from 6 to 15 MeV in 100 keV steps. A broad anomaly was observed in the ⁹Be(p, p₀)⁹Be excitation functions. Differential cross-section angular distributions were measured for ⁹Be(p, p₀)⁹Be and ⁹Be(p, p₂)⁹Be at lab energies of 13.0, 14.0, 15.0, 21.35 and 30.3 MeV and for ⁹Be(p, d₀)⁸Be at 13.0, 14.0, 15.0 and 21.35 MeV. Angular distributions of polarization analysing powers for ⁹Be( $p$ ,p₀)⁹Be, ⁹Be(p, p₂)⁹Be and ⁹Be( $p$ , d₀)⁸Be were measured at 8.0, 11.0, 12.0, 13.0 and 15.0 MeV. A spherical optical-model (SOM) analysis of the elastic scattering angular distribution data from 13.0 to 30.3 MeV showed that an energy dependence of only V_R and W_s (volume real and surface imaginary depths) is sufficient to reproduce the measurements. Coupled-channels (CC) analyses were made with a quadrupole-deformed optical-model potential and strong coupling of $32^{−}$ , $52^{−}$ and $72^{−}$ levels of a $K = 32$ ground-state rotational band of ⁹Be. The ⁹Be(p, p₀)⁹Be and ⁹Be(p, p₂)⁹Be data from 13.0 to 30.3 MeV were analyzed simultaneously at each energy, varying only V_R and W_s with energy, for a potential deformation of β = 1.1. Both SOM and CC analyses indicated the same energy dependence in V_R, while W_s averaged 3.5 MeV lower in CC than in SOM, with both energy dependences consistent with previous analyses of nucleon scattering from 1p shell nuclei.
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Cross sections, polarisations and analysing powers are presented for the elastic and inelastic scattering of 30.4 MeV polarised protons by ¹²C(Q = 0.0, − 4.44, −7.65, −9.64 MeV), ¹³C(Q = 0.0, −3.09 MeV), ¹⁶O (Q = 0.0, −8.87 MeV) and ⁵⁴Fe (Q = 0.0, −1.41 MeV). Conventional optical model analyses of the elastic scattering are presented. The inelastic scattering data are analysed using a microscopic model employing shell-model wave functions, together with an effective interaction; also, a macroscopic collective model is applied where appropriate.
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^†: On leave from Institute of Nuclear Research, Řež, Czechoslovakia.

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Nuclear Physics A

Abstract

References (19)

Nucl. Phys.

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Bull. Am. Phys. Soc.

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Compilation of phenomenological optical-model parameters 1969-1970