Collectivity in A 鈭?70 nuclei studied via lifetime measurements in ⁷⁰Br and ^68,70Se

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• 作者：A.J. Nichols^a ; ^{an527@york.ac.uk" class="auth_mail} ; R. Wadsworth^a ; H. Iwasaki^b ; K. Kaneko^c ; A. Lemasson^b ; ^d ; G. de Angelis^e ; V.M. Bader^b ; T. Baugher^b ; D. Bazin^b ; M.A. Bentley^a ; J.S. Berryman^b ; T. Braunroth^f ; P.J. Davies^a ; A. Dewald^f ; C. Fransen^f ; A. Gade^b ; M. Hackstein^f ; J. Henderson^a ; D.G. Jenkins^a ; D. Miller^g ; C. Morse^b ; I. Paterson^a ; E.C. Simpson^a ; S.R. Stroberg^b ; D. Weisshaar^b ; K. Whitmore^b ; K. Wimmer^b
• 关键词：Nuclear transition probabilities ; Nucleon knockout reactions ; Lifetimes
• 刊名：Physics Letters B
• 出版年：2 June 2014
• 年：2014
• 卷：733
• 期：Complete
• 页码：52-57
• 全文大小：389 K

文摘

Transition strengths for decays from low-lying states in A ∼ 70 nuclei have been deduced from lifetime measurements using the recoil distance Doppler shift technique. The results confirm the collectivity previously reported for the method=retrieve&_eid=1-s2.0-S0370269314002482&_mathId=si1.gif&_user=111111111&_pii=S0370269314002482&_rdoc=1&_issn=03702693&md5=8b5c806d9bea0eba59fb8358799f17d0">$2_1^{+}\to 0_{\mathit{gs}}^{+}$ decay in ⁶⁸Se and reveal a relative decrease in collectivity in ⁷⁰Br. This trend is reproduced by shell model calculations using the GXPF1A interaction in an fp   model space including the Coulomb, spin-orbit and isospin non-conserving interactions. The method=retrieve&_eid=1-s2.0-S0370269314002482&_mathId=si2.gif&_user=111111111&_pii=S0370269314002482&_rdoc=1&_issn=03702693&md5=9769ec8fa305973085ef96782e2a3875">$3_1^{+}\to 2_1^{+}$ decay in ⁷⁰Br is found to have a very small B(M1) value, which is consistent with the configuration of the state being dominated by the coupling of method=retrieve&_eid=1-s2.0-S0370269314002482&_mathId=si3.gif&_user=111111111&_pii=S0370269314002482&_rdoc=1&_issn=03702693&md5=9d4251d428735fc56d561f09c6684678">$f_{\frac{5}{2}}$ protons and neutrons. The results suggest that the method=retrieve&_eid=1-s2.0-S0370269314002482&_mathId=si4.gif&_user=111111111&_pii=S0370269314002482&_rdoc=1&_issn=03702693&md5=38ffc2d75e547257eb64f83d1b2aee4a">$g_{\frac{9}{2}}$ orbit does not play an important role at low spin in these nuclei. The B(E2) values for the decays of the (T = 1) method=retrieve&_eid=1-s2.0-S0370269314002482&_mathId=si5.gif&_user=111111111&_pii=S0370269314002482&_rdoc=1&_issn=03702693&md5=04e72fbc40af1b71346bd502fb0a834b">$2_1^{+}$ states in ⁷⁰Br and ⁷⁰Se are almost identical, suggesting there is no major shape change between the two nuclei at low spin.