Search for the 2⁺excitation of the Hoyle state in¹²C using the¹²C(¹²C,3α)¹²C reaction

Abstract

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Candidate for the 2+excited Hoyle state atEx∼10 MeV in12<

“…Muñoz-Britton et al measured the angular correlation for the 3α decay in the 12 C( 12 C, 12 C[3α]) reaction [18]. However, no conclusive result for the 2 12 C is, thus, still controversial and it is highly desired to obtain conclusive evidence for the 2 + 2 state.…”

Folding-model analysis of inelasticα+12C scattering at medium energies, and the isoscalar transition strengths of the cluster states of12C

“…Because of such an interesting structure predicted for the 2 + 2 state of 12 C, numerous experimental studies over the years have been aimed to detect it in the measured spectra of different reactions involving 12 C (see, e.g., Refs. [15][16][17][18][19][20]). The experimental observation of the 2 + 2 state of 12 C would be very important for a deeper understanding of the structure of the Hoyle state.…”

“…ii) there is always a strong population of the narrow 3 − 1 state at 9.64 MeV and broad 0 + 3 resonance at 10.3 MeV that hinder the 2 + 2 peak at about 10 MeV in the excitation spectrum of 12 C [18].…”

Microscopic cluster description of12C

“…12 C is known from theory and experiment (see, e.g., [32] and [33]) to have some very narrow resonances above the three α threshold. One may wonder why a system with several open channels does not decay instantly, but manifests these narrow resonance states.…”