Evidence for radiative coupling of the pygmy dipole resonance to excited states

アイソベクトルとアイソスカーラーピグミー双極共鳴間の放射結合の証拠

Angell, C.; Hammond, S. L.*; Karwowski, H.*; Kelley, J.*; Krtika, M.*; Kwan, E.*; 牧永 あや乃*; Rusev, G.*

Angell, C.; Hammond, S. L.*; Karwowski, H.*; Kelley, J.*; Krtika, M.*; Kwan, E.*; Makinaga, Ayano*; Rusev, G.*

The photoabsorption cross section and ground state branching ratio of Nd were measured using quasi-monoenergetic -ray beams at several beam energies. Two peaks corresponding to the isovector pygmy dipole resonance (PDR) were identified. The branching ratios were compared to statistical-model calculations. We found that the Brink hypothesis is violated, and that the branching ratios are only reproduced by assuming that the observed isovector PDR selectively decays to the isoscalar PDR.