2015/12/11 by Yoshiko Kanada-En’yo, Yoshiko Kanada-En'yo
Physics and Astronomy · #Advanced Chemical Physics Studies #Amplitude #Atomic and Molecular Physics #Atomic physics #Cluster (spacecraft) #Dipole #Energy (signal processing) #Isoscalar #Nuclear physics research studies #Physics #Quantum mechanics #Wave function #nucl-th
paper · pdf · doi:10.1103/physrevc.93.054307
13 pages, 6 figures. arXiv admin note: text overlap with arXiv:1511.08530
arxiv created 2015/12/11 · openalex publication_date 2016/05/05 · arxiv updated 2016/05/25 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The isoscalar monopole (ISM) and dipole (ISD) excitations in 12C are investigated theoretically with the shifted antisymmetrized molecular dynamics (AMD) plus 3\ensuremathα-cluster generator coordinate method (GCM). The small-amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by a small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large-amplitude cluster modes are incorporated by superposing 3\ensuremathα-cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present a calculation that describes the ISM and ISD excitations over a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, although the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the distance motion between \ensuremathα clusters, and they split into a couple of states because of the angular motion of \ensuremathα clusters. The low-energy ISM strengths exhaust 26% of the energy-weighted sum rule, which is consistent with the experimental data for the 12C(02+; 7.65 MeV) and 12C(03+; 10.3 MeV) measured by (e,e^\ensuremath'),\phantom\rule0.16em0ex(\ensuremathα,\ensuremathα^\ensuremath'), and (6Li,\stackrel\ensuremath'6Li) scatterings. In the calculated low-energy ISD strengths, two 1^\ensuremath- states (the 11^\ensuremath- and 12^\ensuremath- states) with the significant strengths are obtained over E=10--15 MeV. The results indicate that the ISD excitations can be a good probe to experimentally search for new cluster states such as the 12C(12^\ensuremath-) obtained in the present calculation.