Alpha-Gamma Angular Correlations in C 12 , Mg </mml:mrow…
1971; American Institute of Physics; Volume: 4; Issue: 4 Linguagem: Inglês
10.1103/physrevc.4.1159
ISSN1538-4497
AutoresN. Baron, R. F. Leonard, W. M. Stewart,
Tópico(s)Atomic and Molecular Physics
ResumoThe angular correlation between inelastically scattered $\ensuremath{\alpha}$ particles and the subsequent deexcitation $\ensuremath{\gamma}$ ray has been measured at an $\ensuremath{\alpha}$ energy of 42 MeV. Measurements have been carried out in the reaction plane for $\ensuremath{\gamma}$ rays resulting from the decay of the first excited (${2}^{+}$) state of $^{12}\mathrm{C}$, $^{24}\mathrm{Mg}$, $^{58}\mathrm{Ni}$, and $^{120}\mathrm{Sn}$. The results are reported in terms of the $\ensuremath{\gamma}$-ray symmetry angle, ${\ensuremath{\theta}}_{0}$, and the ratio $\frac{A}{B}$. Qualitatively the behavior of the symmetry angle is found to be the same for all four isotopes, rotating continuously at forward $\ensuremath{\alpha}$-scattering angles and oscillating about the plane-wave and adiabatic predictions at larger $\ensuremath{\alpha}$-scattering angles. For the three isotopes for which $\frac{A}{B}$ measurements were possible, the ratio was clearly not identically zero. Both the angular-correlation and cross-section data are compared with the results of distorted-wave-Born-approximation calculations using a wide range of optical-model parameters. The optical-model ambiguities encountered here are similar to those found in fitting cross-section data alone.
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