Experimental studies of the resonance at Ec.m.=19.7 MeV in the C12 + O16 system

D. Shapira, R. G. Stokstad, M. W. Sachs, A. Gobbi, D. A. Bromley

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40 Scopus citations


A resonance appearing in the C12+O16 system at a center-of-mass incident energy of 19.7 MeV has been studied experimentally. Excitation functions for the C12+O16 inelastic scattering and the C12(O16, α)Mg*24 and C12(O16, p)Al*27 reaction channels were measured. The width of the resonance was shown to be more than double the average level width in Si28 at excitation energies around 36.5 MeV where this resonance appears. The resonance is enhanced at large angles in the elastic and inelastic channels and it is found to be equally strong at θc.m.=3° and 177° for the C12(O16, p)Al27 reaction. The yield of 6.13 MeV γ radiation has been measured and is observed to resonate at Ec.m.=19.7 MeV. High resolution measurements of the particle yield at Ec.m.=19.7 MeV, θlab=7.5° for the reaction C12(O16, C12)O16* (6.05, 6.13 MeV) show that the 3- (6.13 MeV) state is populated much more strongly than the 0+ (6.05 MeV) state. These results do not support the suggestion that the resonance has a C12-α-C12 molecular structure. Measurements of inelastic scattering at higher energies suggest the existence of additional correlated structures. A statistical analysis of the α-particle yields indicates that both compound and direct mechanisms contribute to the reaction. A discussion of the properties of the resonance in terms of intermediate structure and the statistical theory of Moldauer is given. NUCLEAR REACTIONS C12(O16, C12)O16*, C12(O16, α)Mg24, and C12(O16, p)Al27 18≤Ec.m.≤21 MeV, θc.m.=3°, 177°. Resonance in Si28 at 36.5 MeV excitation energy. Decay channels studied. Measured γ ray excitation functions [NaI(Tl)] and charged particle yield with magnetic spectrograph. Fluctuation and Hauser-Feshbach analysis of C12(O16, α)Mg*24 data.

Original languageEnglish
Pages (from-to)1907-1917
Number of pages11
JournalPhysical Review C - Nuclear Physics
Issue number6
StatePublished - 1 Jan 1975
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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