2010/11/29 by Dao T. Khoa, Do Cong Cuong, Yoshiko Kanada-En’yo +1 · 21 citations
Physics and Astronomy · #Advanced Chemical Physics Studies #Astronomical and nuclear sciences #Atomic physics #Excitation #Excited state #Inelastic scattering #Isoscalar #Isospin #Nuclear physics #Nuclear physics research studies #Nuclear reaction #Physics #Quantum mechanics #Scattering #Spectral line #nucl-ex #nucl-th
paper · pdf · doi:10.1016/j.physletb.2010.11.061
published in Physics Letters B 695(5), 469-475 (Elsevier BV) · Accepted for publication in Phys. Lett. B
arxiv created 2010/11/29 · openalex publication_date 2010/12/01 · arxiv updated 2011/08/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
While the Hoyle state (the isoscalar 0+2 excitation at 7.65 MeV in 12C) has been observed in almost all the electron and α inelastic scattering experiments, the second 2+ excited state of 12C at E\rm x≈ 10 MeV, believed to be an excitation of the Hoyle state, has not been clearly observed in these measurements excepting the high-precision \aap experiments at Eα=240 and 386 MeV. Given the (spin and isospin zero) α-particle as a good probe for the nuclear isoscalar excitations, it remains a puzzle why the peak of the 2+2 state could not be clearly identified in the measured \aap spectra. To investigate this effect, we have performed a microscopic folding model analysis of the \ac scattering data at 240 and 386 MeV in both the Distorted Wave Born Approximation (DWBA) and coupled-channel (CC) formalism, using the nuclear transition densities given by the antisymmetrized molecular dynamics (AMD) approach and a complex CDM3Y6 density dependent interaction. Although AMD predicts a very weak transition strength for the direct (0+1→ 2+2) excitation, our detailed analysis has shown evidence that a weak ghost of the 2+2 state could be identified in the 240 MeV \aap data for the 0+3 state at 10.3 MeV, when the CC effects by the indirect excitation of the 2+2 state are taken into account. Based on the same AMD structure input and preliminary \aap data at 386 MeV, we have estimated relative contributions from the 2+2 and 0+3 states to the excitation of 12C at E\rm x≈ 10 MeV as well as possible contamination by 3-1 state.