K-mixing in the doubly mid-shell nuclide ¹⁷⁰Dy and the role of vibrational degeneracy

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• 作者：P.-A. Sö ; derströ ; m^a ; ^{pasoder@ribf.riken.jp" class="auth_mail" title="E-mail the corresponding author} ; P.M. Walker^b ; J. Wu^a ; ^c ; H.L. Liu^d ; P.H. Regan^b ; ^e ; H. Watanabe^f ; ^g ; P. Doornenbal^a ; Z. Korkulu^h ; ¹ ; P. Leeⁱ ; J.J. Liu^j ; G. Lorusso^a ; ^e ; S. Nishimura^a ; V.H. Phong^a ; ^k ; T. Sumikama^l ; ¹ ; F.R. Xu^c ; A. Yagi^m ; G.X. Zhang^g ; D.S. Ahn^a ; T. Alharbiⁿ ; H. Baba^a ; F. Browne^o ; A.M. Bruce^o ; R.J. Carroll^b ; K.Y. Chae^p ; Zs. Dombradi^h ; A. Estrade^q ; ² ; N. Fukuda^a ; C.J. Griffin^q ; E. Ideguchi^m ; ^r ; N. Inabe^a ; T. Isobe^a ; H. Kanaoka^m ; S. Kanaya^m ; I. Kojouharov^s ; F.G. Kondev^t ; T. Kubo^a ; S. Kubono^a ; N. Kurz^s ; I. Kuti^h ; S. Lalkovski^b ; G.J. Lane^u ; E.J. Lee^p ; C.S. Leeⁱ ; G. Lotay^b ; C.-B. Moon^v ; I. Nishizuka^l ; ³ ; C.R. Niţă^o ; ^w ; A. Odahara^m ; Z. Patel^b ; Zs. Podolyá ; k^b
• 关键词：K isomer ; Dysprosium ; Mid-shell ; γ-Ray spectroscopy
• 刊名：Physics Letters B
• 出版年：2016
• 出版时间：10 November 2016
• 年：2016
• 卷：762
• 期：Complete
• 页码：404-408
• 全文大小：646 K

文摘

A detailed study of the structure of the doubly mid-shell nucleus ${}_{\phantom{1}66}{}^{170}\text{Dy}_{104}$ has been carried out, following isomeric and β   decay. We have measured the yrast band up to the spin-parity J^π=6⁺$J^{\pi }=6^{+}$ state, the K=2$K=2$γ  -vibration band up to the 5⁺$5^{+}$ state, a low-lying negative-parity band based on a 2⁻$2^{-}$ state that could be a candidate for the lowest energy octupole vibration state within this nucleus, and a candidate for the K^π=6⁺$K^{\pi }=6^{+}$ two quasi-particle isomer. This state was determined to have an excitation energy of 1643.91(23) keV and a half life of 0.99(4) μs, with a reduced hindrance for its decay to the ground-state band an order of magnitude lower than predicted by N_pN_n$N_{\mathrm{p}}{N}_{\mathrm{n}}$ systematics. This is interpreted as being due to γ  -vibrational mixing from a near degeneracy of the isomer and the 6⁺$6^{+}$ state of the γ band. Furthermore, the parent nucleus ¹⁷⁰Tb has been determined to have a half-life of $0.91({}_{-13}{}^{+18})$ s with a possible spin-parity of 2⁻$2^{-}$.