Probing particle-phonon-coupled states in the neutron-rich nucleusCu65by lifetime measurements with fast-timing techniques

Abstract

The 65 Cu nucleus was populated by the 64 Ni(7 Li,α2n) 65 Cu reaction and the lifetime of the 9/2 + state at 2.5 MeV was measured by electronic fast-timing technique, providing the value τ = 37(3) ps. The reduced transition probability B(E3) = 8.82(165) W.u. is deduced and compared to theoretical predictions in the framework of a particle-vibration (weak) coupling model. The results indicate that the 9/2 + state is a member of the 3 − ⊗ πp3/2 multiplet, built by coupling the octupole 3 − phonon of 64 Ni to an unpaired proton in the p 3/2 level, confirming the robustness of core excitations in the medium mass nucleus 64 Ni.

Approaching complete low-spin spectroscopy ofBi210with a cold-neutron capture reaction

“…Indeed, within a weak-coupling approach one may expect several states arising from the coupling of the 3 − phonon to the lowest excitations in 210 Bi, i.e., 1 − , 0 − , 9 − , 2 − , and 3 − . This coupling would give a number of positive-parity states characterized by spin values between 2 and 12 and located around 2.6 MeV, although splitting of the order of hundreds of keV or more can be expected [22][23][24][25][26]. The 12 unassigned states, mentioned above, could be of this origin.…”

Study of Low-spin States in Ca Isotopes via Neutron Capture Reactions

“…From the experimental point of view, indications of particle-phonon coupled states have been found mostly in medium-heavy nuclei [1], while scarce information exists for medium-light systems [2][3][4][5] and moving away from the stability valley. In the latter case, particle-phonon coupled states would also provide complementary information on the robustness or softness of the nuclear collectivity far from stability.…”

Particle-core Couplings Close to Neutron-rich Doubly-magic Nuclei

“…Such calculations, for the specific case of 133 Sb, are under development within a microscopic framework using consistently Skyrme ef-fective interactions [22]. This will represent a significant step forward with respect to paticle-phonon calculations, performed, for many decades, by using the phenomenological model of Bohr and Mottelson [1], based on a weak-coupling approach and on purely phenomenological inputs [11][12][13][14].…”

“…The examples include 206−209 Pb, 206,207 Tl and 206 Hg [4,5]. Several indications of states of particle-phonon nature have also been found around other doubly-magic and semi-magic nuclei lying near the stability valley [6][7][8][9][10][11][12][13][14], while searches for particle-phonon coupled states away from the stability valley, as, for example, in neutron-rich nuclei, are expected to provide information on the robustness or softness of nuclear collectivity which can be measured with the purity of single-nucleon excitations on top of core vibrations.…”