학술논문
Interplay of quasiparticle and vibrational excitations: First observation of isomeric states in 168Dy and 169Dy
Document Type
article
Author
G.X. Zhang; H. Watanabe; G.D. Dracoulis; F.G. Kondev; G.J. Lane; P.H. Regan; P.-A. Söderström; P.M. Walker; K. Yoshida; H. Kanaoka; Z. Korkulu; P.S. Lee; J.J. Liu; S. Nishimura; J. Wu; A. Yagi; D.S. Ahn; T. Alharbi; H. Baba; F. Browne; A.M. Bruce; M.P. Carpenter; R.J. Carroll; K.Y. Chae; C.J. Chiara; Zs. Dombradi; P. Doornenbal; A. Estrade; N. Fukuda; C. Griffin; E. Ideguchi; N. Inabe; T. Isobe; S. Kanaya; I. Kojouharov; T. Kubo; S. Kubono; N. Kurz; I. Kuti; S. Lalkovski; T. Lauritsen; C.S. Lee; E.J. Lee; C.J. Lister; G. Lorusso; G. Lotay; E.A. McCutchan; C.-B. Moon; I. Nishizuka; C.R. Nita; A. Odahara; Z. Patel; V.H. Phong; Zs. Podolyák; O.J. Roberts; H. Sakurai; H. Schaffner; D. Seweryniak; C.M. Shand; Y. Shimizu; T. Sumikama; H. Suzuki; H. Takeda; S. Terashima; Zs. Vajta; J.J. Valiente-Dóbon; Z.Y. Xu; S. Zhu
Source
Physics Letters B, Vol 799, Iss , Pp - (2019)
Subject
Language
English
ISSN
0370-2693
Abstract
The neutron-rich dysprosium isotopes 168Dy102 and 169Dy103 have been investigated using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity uranium beam in conjunction with isotope separation through the BigRIPS separator at RIBF in RIKEN Nishina Center. For 168Dy, a previously unreported isomer with a half-life of 0.57(7) μs has been identified at an excitation energy of 1378 keV, and its presence affirmed independently using γ-γ-γ coincidence data taken with Gammasphere via two-proton transfer from an enriched 170Er target performed at Argonne National Laboratory. This isomer is assigned Jπ=Kπ=(4−) based on the measured transition strengths, decay patterns, and the energy systematics for two-quasiparticle states in N=102 isotones. The underlying mechanism of two-quasiparticle excitations in the doubly midshell region is discussed in comparison with the deformed QRPA and multi-quasiparticle calculations. In 169Dy, the B(E2) value for the transition de-exciting the previously unreported Kπ=(1/2−) isomeric state at 166 keV to the Kπ=(5/2−) ground state is approximately two orders of magnitude larger than the E2 strength for the corresponding isomeric-decay transition in the N=103 isotone 173Yb, suggesting the presence of a significant γ-vibrational admixture with a dominant neutron one-quasiparticle component in the isomeric state.