Nanosecond isomers in neutron-rich67Cuand64Coand a fast

Mitsuteru Asai

¹

,

T. Ishii

²

,

Akio Makishima

³

et al.

Abstract

Gamma-ray cascades from nanosecond isomers in neutron-rich nuclei 67 Cu and 64 Co have been observed through heavy-ion deep-inelastic collisions of 198 Ptϩ 76 Ge ͑8 MeV/nucleon͒ using an isomer-scope. In 67 Cu, an isomeric state at 3464 keV and its decay scheme have been established. The isomeric transition is a hindered M 1 transition between the 15/2 ϩ and the 13/2 ϩ states with main components of (p 3/2 g 9/2 f 5/2 Ϫ1 ) 15/2 ϩ and (p 3/2 g 9/2 p 1/2 ) 13/2 ϩ, respectively. A fast E3 transition between the g 9/2 and the p 3/2 single-particle states indicates strong particle-octupole vibration coupling in 67 Cu. An isomeric state at 834 keV with T 1/2 ϭ6.4(3) ns has been identified in 64 Co. Proton-neutron configurations of the levels established in 64 Co are discussed.

Core-coupled protons,f7/2intruder states, and competingg9/2proton and neutron structures inChiara1, Stefanescu2, Walters3 et al. 2012Phys. Rev. C

“…With these spectra, all gamma rays observed in Ref. [18] were confirmed. Additionally, the level scheme has been extended above the known 3463-keV, ∼1-ns isomer.…”

“…The 833-, 861-and 100-keV gamma rays from Ref. [18] are observed, and several new transitions have been identified. The spectrum double gated on two of these, the 524-and 775-keV transitions, is shown in Fig.…”

Spectroscopy of odd-mass cobalt isotopes toward theN=40subshell closure and shell-model description of spherical and deformed states

“…Beside the two isomeric ones, that, as expected, escape detection in CLARA, and the 329-keV transition that is reported to be very weak in Ref. [32], all the other transitions previously reported are clearly observed. Three transitions are new, among them the two most intense ones (274 and 738 keV) are also in mutual coincidence.…”

“…We see all the transitions de-exciting those states. Four new low-energy transitions are also in coincidence with 62 Co recoils: they are marked with asterisks in Table II. A (5 + ) isomer with a half-life of 6.4 ns was reported [32] γ transitions. Beside the two isomeric ones, that, as expected, escape detection in CLARA, and the 329-keV transition that is reported to be very weak in Ref.…”

Nuclear physics experiments with in-beam fast-timing and plunger techniques

“…It corroborates the hypothesis that the nature of this state originates from the coupling of a proton with a superfluid core, the neutron playing a spectator role in this scenario. From the deep inelastic experimental study [26], the half-life of the 9/2 + state was assigned with a higher limit of 300 ps. This would imply a B(E3) higher than 11 W.u.…”