Charge exchange (6Li, 6He) and the two-step pickup-stripping (6Li, 7Li) (7Li, 6He) excitation mode

doi:10.1016/0370-2693(74)90441-9

Physics Letters B

Volume 48, Issue 1, 7 January 1974, Pages 1-5

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Abstract

The single-step forbidden analog 0⁺→0⁺ transition has been observed in (⁶Li, ⁶He) on ¹⁸O and ²⁶Mg. The cross section and the observed L=1 shape of the angular distribution for the $^{26} Mg →^{26} Al_{0}^{+}, T=1$ transition is analysed in terms of a single-nucleon pickup-stripping two-step process in the second order DWBA. There are indications that the single step allowed (⁶Li, ⁶He) charge exchange transitions contain large two step contributions as well.

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Angular distributions for the transitions to the ground and excited states of ¹²B from the ¹²C(⁷Li, ⁷Be)¹²B reaction at 82 MeV were measured. The data were analyzed in the framework of distorted wave born approximation for the direct charge-exchange and coupled reaction channels method for the two-step sequential nucleon transfers. It was shown that the two-step sequential nucleon transfer is the dominant mechanism in the investigated angular range and the direct mechanism becomes important only for small angles ( $θ_{cm} < 10 °$ ).
Direct charge-exchange versus sequential nucleon transfers in the 14C(6Li,6He)14N reaction at 93 MeV
1998, Nuclear Physics A
The ¹⁴C(⁶Li,⁶He)¹⁴N reaction was investigated at a ⁶Li ion energy of 93 MeV. The angular distributions for several natural and unnatural parity states of the ¹⁴N nucleus were compared with the DWBA and Coupled Reaction Channels (CRC) calculations assuming direct charge exchange and two-step sequential nucleon transfers. It was shown that the direct charge-exchange mechanism dominates for the transitions to the ground and excited (E_x = 3.95 MeV) 1⁴ states of the ¹⁴N nucleus up to angles of 50°–70°. The sequential nucleon transfers must be taken into account at larger angles for these states and in the full angular range for the other states (2.31 MeV (0⁺, T = 1), 5.11 MeV (2⁻), 5.69 MeV (1⁻) + 5.83 MeV (3⁻), 7.03 MeV (2⁺) and 8.49 MeV (4⁻)).
One- and two-step processes in 6Li(7Li,7Be) 6He reaction at E(7Li) = 78 MeV
1995, Nuclear Physics, Section A
The angular distributions of the ⁶Li(⁷Li,⁷Be)⁶He reaction were measured at 78 MeV projectile energy for the transitions to the ground and first excited states of ⁶He and ⁷Be nuclei. The experimental data were analyzed with the one-step charge-exchange and two-step nucleon transfer mechanisms using DWBA and coupled reaction channels methods. A satisfactory description of the experimental data was obtained with direct charge-exchange processes at small angles and with two-step nucleon transfers at large angles.
A study of the 90Zr(6Li, 6He)90Nb reaction at E<inf>6<inf>Li</inf> = 93 MeV</inf>
1985, Nuclear Physics, Section A
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A DWBA formalism for knockout-exchange reactions of composite nuclei
1983, Nuclear Physics, Section A
A DWBA formulation of the knockout-exchange scattering of composite projectiles having zero internal orbital angular momentum is presented. The model problem assumes a target nucleus heavy enough to allow the neglect of its recoil. The formalism accommodates any form of nucleon-nucleon potential containing central, tensor and spin-orbit terms which are treated on the same footing, with no multipole expansions. The nonlocal radial integrals assume transition nucleon exchange density matrices characteristic of finite potential well shell-model target and cluster model projectile wave functions. The usefulness of the formalism is demonstrated with a PWBA numerical application to the ²⁶Mg(⁶Li, ⁶He)²⁶Al reaction.
A study of the 26Mg(12C, 12B)26Al charge-exchange reaction
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^∗: On leave of absence from Comision Nacional de Energia Atomica, Argentina.

^∗∗: On leave of absence from Institute for Nuclear Study, University of Tokyo, Tanashi, Tokyo, Japan.

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Physics Letters B

Abstract

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Mechanisms of charge-exchange in the <sup>12</sup>C(<sup>7</sup>Li, <sup>7</sup>Be)<sup>12</sup>B reaction at the beam energy of 82 MeV

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One- and two-step processes in <sup>6</sup>Li(<sup>7</sup>Li,<sup>7</sup>Be) <sup>6</sup>He reaction at E(<sup>7</sup>Li) = 78 MeV

A study of the <sup>90</sup>Zr(<sup>6</sup>Li, <sup>6</sup>He)<sup>90</sup>Nb reaction at E<inf>6<inf>Li</inf> = 93 MeV</inf>

A DWBA formalism for knockout-exchange reactions of composite nuclei

A study of the <sup>26</sup>Mg(<sup>12</sup>C, <sup>12</sup>B)<sup>26</sup>Al charge-exchange reaction