Dominance of the direct reaction process in the 12C(7Li, 7Be)12B reaction at θL=0° and EL⩾21 MeVA

doi:10.1016/0370-2693(90)90611-9

Physics Letters B

Volume 246, Issues 3–4, 30 August 1990, Pages 342-346

https://doi.org/10.1016/0370-2693(90)90611-9 Get rights and content

Abstract

The ¹²C(⁷Li, ⁷Be)¹²B reaction is studied at projectile energies of 14, 21 and 26 MeV/A. Emitted ⁷Be particles are detected at θ_L∼0° with an energy resolution of about 200 keV which is enough to separate transitions leading to the first excited state of ⁷Be (⁷Be₁) from ones leading to the ground state of ⁷Be(⁷Be₀). At incident energies higher than 21 MeV/A, both zero-degree excitation functions for ⁷Be₀ and ⁷Be₁ are well predicted by microscopic distorted-wave Born approximation calculations, but at an incident energy of 14MeV/A there are large contributions from complex reaction processes other than the one-step process.

References (15)

S. Nakayama et al.
Phys. Lett. B
(1987)
Phys. Rev. C
(1986)
A. Etchegoyen et al.
Phys. Rev. C
(1988)
H. Ikegami et al.
Nucl. Instrum. Methods
(1980)
H. Kenske
Nucl. Phys. A
(1988)
H. Lenske
Nucl. Phys. A
(1989)
N. Anantaraman et al.
Nucl. Phys. A
(1982)
H. Lenske et al.
Phys. Rev. Lett.
(1989)
J.S. Winfield et al.
Phys. Rev. C
(1986)

There are more references available in the full text version of this article.

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Physics Letters B

Abstract

References (15)

Phys. Lett. B

Phys. Rev. C

Phys. Rev. C

Nucl. Instrum. Methods

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Phys. Rev. Lett.

Phys. Rev. C

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