2024-03-29T10:24:31Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/614982022-11-17T02:08:08Zhdl_2115_20039hdl_2115_116Isoscalar dipole transition as a probe for asymmetric clusteringChiba, Y.Kimura, M.Taniguchi, Y.420Background: The sharp 1(-) resonances with enhanced isoscalar dipole transition strengths are observed in many light nuclei at relatively small excitation energies, but their nature has been unclear. Purpose: We show those resonances can be attributed to the cluster states with asymmetric configurations such as alpha + O-16. We explain why asymmetric cluster states are strongly excited by the isoscalar dipole transition. We also provide a theoretical prediction of the isoscalar dipole transitions in Ne-20 and Ti-44. Method: The transition matrix is analytically derived to clarify the excitation mechanism. The nuclear model calculations by Brink-Bloch wave function and antisymmetrized molecular dynamics are also performed to provide a theoretical prediction for Ne-20 and Ti-44. Results: It is shown that the transition matrix is as large as the Weisskopf estimate even though the ground state is an ideal shell-model state. Furthermore, it is considerably amplified if the ground state has cluster correlation. The nuclear model calculations predict large transition matrix to the a + O-16 and a + Ca-40 cluster states comparable with or larger than the Weisskopf estimate. Conclusions: We conclude that the asymmetric cluster states are strongly excited by the isoscalar dipole transition. Combined with the isoscalar monopole transition that populates the 0(+) cluster states, the isoscalar transitions are promising probes for asymmetric clusters.American Physical Society (APS)Journal Articleapplication/pdfhttp://hdl.handle.net/2115/61498https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/61498/1/PhysRevC.93.034319.pdf2469-9985Physical review C9330343192016-03-18enginfo:doi/10.1103/PhysRevC.93.034319publisher