Shape Coexistence in 67Co, 66,68,70,72Ni, and 71Cu

Analyses of data from both deep inelastic reactions at Argonne National Laboratory and single- and multiple-particle knockout reactions at Michigan State University revealed new γ-ray transitions in even-even 66,68,70,72Ni38,40,42,44 and in 67Co40 that provide strong evidence for multiple shape coexistence at N = 38 and 40 and deep prolate minima in 70Ni42 and isotonic 71Cu42. A new transition at 642 keV is proposed for 66Ni as the prolate 2+ to 0+ transition. Two new transitions in 72Ni at 915 and 1225 keV were identified in the knock-out reaction study and could represent de-population of prolate states. Taken together with recent theoretical work using the Monte Carlo shell model, a well defined region of shape coexistence can be seen existing precisely between 38 ≤ N ≤44 for Co, Ni, and Cu nuclei.

[1]  M. Carpenter,et al.  Analogous intruder behavior near Ni, Sn, and Pb isotopes , 2015 .

[2]  A. Macchiavelli,et al.  Identification of deformed intruder states in semi-magic Ni 70 , 2015 .

[3]  P. Mantica,et al.  decay of 72Co and microsecond isomers in even-mass neutron-rich nickel isotopes , 2014 .

[4]  R. Clark,et al.  Quadrupole transition strength in the (74)Ni nucleus and core polarization effects in the neutron-rich Ni isotopes. , 2014, Physical review letters.

[5]  B. A. Brown,et al.  Configuration mixing and relative transition rates between low-spin states in 68 Ni , 2013 .

[6]  T. Otsuka,et al.  Novel shape evolution in exotic Ni isotopes and configuration-dependent shell structure , 2013, 1309.5851.

[7]  R. Clark,et al.  Quadrupole collectivity in neutron-rich Fe and Cr isotopes. , 2013, Physical review letters.

[8]  M. Carpenter,et al.  Search for Intruder States in 68 Ni and 67 Co , 2013 .

[9]  M. Carpenter,et al.  Low-spin states and the non-observation of a proposed 2202-keV, 0+ isomer in 68Ni , 2012 .

[10]  D. Bazzacco,et al.  Spectroscopy of odd-mass cobalt isotopes toward the N=40 subshell closure and shell-model description of spherical and deformed states , 2012 .

[11]  M. Carpenter,et al.  Core-coupled protons, $f_{7/2}$ intruder states, and competing $g_{9/2}$ proton and neutron structures in $^{65,67}$Cu , 2012 .

[12]  J. Wood,et al.  Shape coexistence in atomic nuclei , 2011 .

[13]  K. Sieja,et al.  Shell quenching in Ni-78: A hint from the structure of neutron-rich copper isotopes , 2010 .

[14]  I. Stefanescu,et al.  Shape Isomerism at N = 40: Discovery of a Proton Intruder in 67Co , 2008, 0807.2595.

[15]  Girod,et al.  Spectroscopy of neutron-rich nickel isotopes: Experimental results and microscopic interpretation. , 1988, Physical review. C, Nuclear physics.

[16]  T. Otsuka.  Exotic nuclei and nuclear forces , 2013 .