Elastic scattering of 12C on 13C at the Coulomb barrier

doi:10.1016/0375-9474(76)90240-2

Nuclear Physics A

Volume 274, Issues 1–2, 7–14 December 1976, Pages 253-261

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Abstract

The elastic scattering of ¹²C on ¹³C has been measured between c.m. energies of 4.8 and 9.5 MeV in steps of 48 keV atθ_c.m. = 90°. The absence of resonance-like structures comparable to those observed in ¹²C-¹²C scattering is discussed with respect to the influence of the elastic neutron transfer. The presence of this transfer even below the barrier is demonstrated by the measurement of an angular distribution of the ¹²C-¹³C scattering at E_c.m. = 5.76 MeV.

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Cited by (7)

Molecular orbital formation and Landau-Zener transitions in the 13C+12C collision
1988, Nuclear Physics, Section A
Angular distributions of the elastic and inelastic ¹³C + ¹²C scattering leading to excited states in ¹³C have been measured at eight energies at Coulomb barrier energies. The data are compared with DWBA calculations performed up to second order and with coupled-reaction-channels calculations using a molecular wave function basis. The result of these calculations allows the conclusion that molecular orbital formation takes place in the ¹³C + ¹²C collision. This mechanism is most important at the lowest measured energies, where rapid changes in the angular distributions of the $^{13} C^{∗} (12^{+})$ state are observed at energies just above the barrier. They cannot be described by standard second-order DWBA calculations and are interpreted as being due to Landau-Zener transitions.
Molecular orbitals of nucleons in nucleus-nucleus collisions
1987, Physics Reports
A formalism for the dynamical treatment of the molecular orbitals of valence nucleons in nucleus-nucleus collisions is developed with the use of the coupled-reaction-channel (CRC) method. The Coriolis coupling effects as well as the finite mass effects of the nucleon are taken into account in this model, of rotating molecular orbitals, RMO. First, the validity of the concept is examined from the viewpoint of the multi-step processes in a standard CRC calculation for systems containing two identical [core] nuclei. The calculations show strong CRC effects particularly in the case where the mixing of different l-parity orbitals - called hybridization in atomic physics - occurs. Then, the RMO representation for active nucleons is applied to the same systems and compared to the CRC results. Its validity is investigated with respect to the radial motion (adiabaticity) and the rotation of the molecular axis (radial and rotational coupling). Characteristic molecular orbitals of covalent molecules appear as rotationally stable states ( $K = 12$ ) with good adiabaticity. Using the RMO's we obtain a new interpretation of various scattering phenomena. Dynamically induced changes in the effective Q-values (or scaling of energies), dynamically induced moments of inertia and dynamically induced effective (L·S) interaction are obtained as a result of the molecular orbital formation. An increased subbarier-fusion probability is indicated also by the formation of the molecular orbitals. Various experimental data on transfer are understood in terms of the RMO's and their adiabatic potentials. The transition mechanism between different RMO's is investigated. A specific transition, the Landau-Zener transition definitely predicts the observation of characteristic changes in the cross sections for the inelastic scattering $^{13} C (^{12} C,^{12} C)^{13} C^{∗} (3.086 MeV, 12^{+})$ with the change of the bombarding energy.
Coupled-reaction-channel approach for molecular orbital phenomena of valence nucleons in heavy-ion collisions: The 12c + 13c system
1984, Nuclear Physics, Section A
A complete coupled-reaction-channel method is applied to molecular orbital phenomena of the valence nucleon in the scattering of ¹²C on ¹³C, i.e. in elastic and inelastic transitions to the single-particle states of ¹³C^∗(gr., $12^{−}$ ; 3.086 MeV, $12^{+}$ ; 3.854 MeV, $52^{+}$ ) with consi ¹²C core-exchange process. The system is analyzed with respect to the occurrence of higher-order transitions of the direct (inelastic) and transfer (core-exchange) processes of the valence nucleon in ¹³C. It is found in the states of positive total parity that the transfer and direct processes act additively and lead to extreme higher-order steps of the multi-interactions, if the ground state (1p_$12$) and the excited states (2s_$12$ and 1d_$52$) are taken into account. Transitions between the excited subchannels show strong-coupling effects, which are due to the reorientations of the d_$52$ orbitals. The reoriented system couples to the ground channel (l-parity mixing) so favourably that the multi-interaction series hardly converges. The consequence of these observations are discussed in terms of the formation of molecular nucleon orbitals based on the polarization and the hybridization of the original orbitals.
Energy levels of light nuclei A = 11-12
1980, Nuclear Physics, Section A
Energy levels of A = 21-44 nuclei (VI)
1978, Nuclear Physics, Section A
The experimentally determined properties of the A = 21–44 nuclei are compiled and evaluated, special emphasis being given to nuclear structure.
Separate tables for each of the nuclides reviewed give all available information about the following properties in this order: - excitation energies (E_x),
1. •
  - γ-ray branching ratios,
2. •
  - γ-ray mixing ratios (δ),
3. •
  - lifetimes (τ_m) or widths (Λ),
4. •
  - spin and parity (J^π) and isospin (T) assignments, and
5. •
  - any other data, on single-particle transfer, resonance levels, etc.
The “best” (or adopted) values for E_x, τ_m or Λ, J^π and T are summarized in a master table.
The review of each A-chain concludes with - a discussion of isospin multiplets,
1. •
  - a few remarks about the experimental situation, and
2. •
  - a compilation of references to relevant theoretical papers.
Optical-model analysis of N14+12C and C12+12C elastic scattering in the range Ec.m.=35 to 63 MeV
1990, Physical Review C

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^†: Now at GSI, Darmstadt, Germany.

^††: Supported by the Swiss National Science Foundatio.

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Nuclear Physics A

Abstract

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Cited by (7)

Molecular orbital formation and Landau-Zener transitions in the <sup>13</sup>C+<sup>12</sup>C collision

Molecular orbitals of nucleons in nucleus-nucleus collisions

Coupled-reaction-channel approach for molecular orbital phenomena of valence nucleons in heavy-ion collisions: The <sup>12</sup>c + <sup>13</sup>c system

Energy levels of light nuclei A = 11-12

Energy levels of A = 21-44 nuclei (VI)

Optical-model analysis of N14+12C and C12+12C elastic scattering in the range Ec.m.=35 to 63 MeV