Protonh 2 11/2 and octupole excitations in148 66Dy82 and149 66Dy83

Abstract

The yrast states of 148Dy and 149Dy have been studied by ?-ray and conversion electron measurements in (c~,xn) and (160, xn) reactions on enriched ~S2Gd and ~36Ce targets. Level schemes to above 4MeV for the two nuclei are reported. The ~h~/2 spectrum identified in 148Dy and the ~haa/2 effective charge eeff=l.52_+0.05e, derived from the measured E2 transition rate between the (rch~/2) 10 + and 8 + states, are discussed and compared with results for other two-particle nuclei. The yrast cascades in a48Dy and a49Dy continue above the (Tzh2a/2) 10 + and (zchZ~/2vfT/2) 27/2-states by --~1 MeV E1 transitions de-exciting the lowest members of octupole multiplets built on these states.The energy shifts for the observed members of the 7zh21/2 • 3-multiplet are analyzed in terms of twoparticle-phonon exchange coupling using an empirical coupling strength extracted from the one valence particle nucleus 14VTb. The dominant vf7/2 x 3-character of low-lying 13/2 + isomers in 149Dy and other N = 83 nuclei is emphasized.

Level structure above the 17+ isomeric state in Tm8369152

“…[4], calculations were performed with empirical two-body matrix elements (TBMEs) for protons in the π 0h 11/2 orbital. The TBMEs were obtained from the experimental levels of 148 Dy, which has two valence protons outside the 146 Gd core, assuming a Z = 64 subshell closure [19]. No empirical TBMEs were available at that time (1986) for a proton in the π 0h 11/2 orbital and a neutron in the ν1f 7/2 orbital.…”

“…(1.23(4) from BRICC [18]) and α 158 = 3.8 ± 0.9. (12) for E3 and 0.689 (19) for M2] did not allow a determination of the nature of these transitions. We note that the conversion coefficient analysis does not exclude an exchange of first 21 + and 22 − assignments (as predicted by our calculations below) in Fig.…”

Shell-model states with seniorityν=3, 5, and 7 in odd-Aneutron-rich Sn isotopes

“…Amplitudes of the reduced transition probabilities for E2 isomeric decays observed in Sn isotopes, calculated from the B(E2) values listed in Table V. In the upper part, the B(E2) amplitudes associated with the 23/2 + (squares) and 19/2 + (circles) isomeric decays are displayed. These E2 transition amplitudes are compared with those determined previously [3][4][5][6][7][8] for the 10 + and 27/2 − (h 11/2 ) n isomer decays (lower part of the figure). The details are discussed in the text.…”

“…For neutrons, at Z = 50, the single-particle levels are distributed more evenly and no trace of an N = 64 subshell closure has been found. Nevertheless, in the Sn isotopes heavier than A = 120, isomers arising from ν(h 11/2 ) n neutron configurations have been observed in all the even (I π = 10 + ) and odd (I π = 27/2 − ) nuclei [3][4][5][6][7][8]. The corresponding B(E2) reduced transition probabilities exhibit a regular, systematic change with A with the lowest value occurring in 123 Sn, herewith defining N = 73 as the half-filling of the neutron h 11/2 subshell [6,7].…”

Erratum: Seniority isomerism in proton-richN=82isotones and its indication to stiffness of theZ=64core [Phys. Rev. C62, 054304 (2000)]

“…relatively high excitation energy of 2 + 1 ) [2]. In the Z > 64, N = 82 isotones, high-spin isomers with J π = 10 + (for even-Z nuclei) and 27/2 − (for odd-Z nuclei) have systematically been observed [3][4][5][6]. In connection to these isomers, the single-j shell model with the π0h 11/2 orbit was successfully applied to the Z > 64, N = 82 isotones [7].…”