Two-nucleon transfer reactions between complex ions

doi:10.1016/0375-9474(72)90789-0

Nuclear Physics A

Volume 196, Issue 3, 4 December 1972, Pages 465-497

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Abstract

A general expression is derived within the framework of DWBA for the amplitude for two-nucleon transfer between heavy ions at sub-Coulombic energies. The eifects of two-nucleon configuration mixing and two-nucleon correlations on this amplitude are discussed, and it is suggested that there are ambiguities in the asymptotic form of the two-nucleon wave function which must be resolved before unambiguous spectroscopic information can be extracted from this type of reaction. The extension of the theory to include optical-model potentials is considered and it is shown that these potentials can lead to some understanding of the available data. Finally, the question of the validity of DWBA in describing the reaction mechanism for these reactions is considered.

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Cited by (26)

The (α, 6He) reaction and other two-neutron transfer reactions leading to 24Mg and 152Sm
1980, Nuclear Physics A
We have analysed the only three (α, ⁶He) experiments we have been able to find in the literature, two on ²⁶Mg and one on ¹⁵⁴Sm. In the ²⁶Mg case, we have further looked at alternative two-neutron transfer reactions, such as (p, t) and (¹⁶O, ¹⁸O), by using a deformed nuclear model and including direct and multistep inelastic processes in the reaction description for both ground and gamma bands. For the ground-state transition, and for some other specific cases, we have also taken into account the sequential two one-neutron transfer mechanism. We conclude that the sequential processes play an important role for the ground-state transition of the Mg reaction, and they have angular distributions substantially different from those of the corresponding direct transitions. We further provide a reasonably consistent picture of the population of the unnatural parity 3⁺ state in the gamma band, which is not affected by the direct transfer process, but can be reached mainly by multistep inelastic processes and in a modest way by the sequential process.
Formfactors for one- and two-nucleon transfer reactions induced by light and heavy ions
1977, Physics Reports
Formfactors and overlaps for light and heavy ion transfer reactions are evaluated including finite range and recoil effects. The treatment of the recoil is based on a separation into a transversal effect, responsible for a modification of the selection rules, and a longitudinal effect related to a scaling of the radial motion. The formfactors for multinucleon transfer can in this formulation be obtained either as products of single-particle overlaps and formfactors or, after transformation to center of mass and relative motion, in terms of cluster type representation. The extension of the nuclear field theory to include transfer reactions is indicated. Some examples of the application of the formfactors to calculations of cross sections by means of distorted wave Born approximation are given with the main emphasis on heavy ion reactions.
Sequential transfer mechanism in the elastic scattering of nearly identical heavy ions
1976, Physics Letters B
In the elastic scattering of two heavy ions, which differ by two particles, the direct optical model scattering interferes with both the simultaneous and the sequential transfer of the two nucleons. We treat this case by coupling the channels A + (A + 2N) and (A + N) + (A + N) and we study the relative importance of the two transfer mechanisms. The model is applied to the ²⁸Si + ³⁰Si system. Simultaneous and sequential processes are found to be equally important in this case and the interference structure in the experimental data is explained qualitatively.
Rotational nuclei: overlap functions and heavy-ion transfer form factors
1976, Nuclear Physics, Section A
A method for calculating overlap functions 〈A, A+2〉 for rotational nuclei is presented where single particle radial multipole functions enter as numerical input. The calculation of the radial multipole functions using a Sturmian expansion procedure is briefly reviewed. As an application of these mathematical techniques, finite-range heavy-ion two-nucleon transfer form factors are calculated for nuclei at both ends of the rare-earth region and the connection between the form factors and the understanding of recent heavy-ion induced two-neutron transfer reactions on deformed rare-earth nuclei is discussed.
One-neutron and two-neutron transfer in the scattering of 18O by 16O
1975, Nuclear Physics, Section A
Angular distributions have been measured for one- and two-neutron transfer reactions induced by ¹⁸O beams on ¹⁶O targets at lab bombarding energies of 42 and 52 MeV. The reactions populating the ground and first excited states of ¹⁷O and ¹⁸O are analyzed in terms of single-step finite range plus recoil DWBA theory taking into account antisymmetrization effects. Special attention is paid to an internally consistent description of the observed absolute magnitudes of all the reactions and to the theoretically expected interferences between various backward-forward scattering mechanisms. The importance of neutron transfer in accounting for different absorbing properties of the ¹⁶O-¹⁹O system as compared to the ¹⁶O-¹⁶O system is shown.
Extended basis shell-model study of two-neutron transfer reactions
1975, Nuclear Physics, Section A
A method to calculate two-nucleon overlaps is presented. The approach is based on shell-model techniques and the effect of one and two nucleons in the continuum are included implicitly. The reactions ¹⁸O(p, t)¹⁶O and ¹⁶O(t, p)¹⁸O (ground and excited 0⁺ states) are analysed within the zero-range and finite-range DWBA framework. The differential cross sections calculated using the overlaps obtained by the present method are compared with the ones obtained by the standard well depth (WD) and Jaffe-Gerace (JG) techniques. It is shown that the WD approach yields cross sections smaller than the experimental values by an order of magnitude while the JG method predicts undue energy dependence in the cross section. Our approach removes these difficulties and is shown to be consistent with the one-nucleon transfer calculation.

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Nuclear Physics A

Abstract

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Cited by (26)

The (α, <sup>6</sup>He) reaction and other two-neutron transfer reactions leading to <sup>24</sup>Mg and <sup>152</sup>Sm

Formfactors for one- and two-nucleon transfer reactions induced by light and heavy ions

Sequential transfer mechanism in the elastic scattering of nearly identical heavy ions

Rotational nuclei: overlap functions and heavy-ion transfer form factors

One-neutron and two-neutron transfer in the scattering of <sup>18</sup>O by <sup>16</sup>O

Extended basis shell-model study of two-neutron transfer reactions