Gamma-ray spectroscopy of87Y

Abstract

The level structure of 87y has been studied using in-beam v-ray spectroscopic methods. Many previously unknown states have been observed. Members of the rc(gg/2)v(g9/2) -2 multiplet are identified. The results are discussed in terms of the weak-coupling model.

Multiplet structure and core-related effects on transition rates in87Y and neighbouringA? 90 nuclei

“…From two experiments, we derive an av- The above mentioned equal shifts are an additional argument that the 247.9 keV transition indeed de-excites the 2675.9 keV state. The corresponding conclusion in [2] is only tentative because the 247.9 keV gamma-ray transition is not resolved from another one belonging to 86y. With an incident energy of E~ = 27 MeV in our experiments the cross section for the 3 n exit channel is rather low and 86y is practically not produced.…”

“…Following the (c~, 2n) studies of Fields et al [2] levels in 8vy were excited in the 2n channel of the reaction aSRb+e(27 MeV) using the Rossendorf cyclotron. The target of SSRbC1 enriched to 98.8% in 85Rb, about 20 mg/cm 2 thick was deposited on a poliester foil.…”

“…It has been pointed out [11] that the presence of neutron holes weakens the Z = 38 subshell closure. In [2], a small quadrupole deformation at higher excitation and spin was suggested for positive-parity seniority-three configurations in 87y. Further, due to the lack of experimental information the predictions of the clusterphonon model concerning transition probabilities [5] have not been checked so far.…”

“…The level scheme of 87y (Z= 39, N=48) has been considerably extended by in-beam investigations in (e, 2n) and (p, n) reactions [2,3]. Some theoretical studies concerning the structure of this nucleus were recently performed within the shell-model [4] and the cluster-phonon model [5].…”

“…At the beginning of our investigations, only an overall upper limit T1/2< 10 ns was known [2] for the excited levels of 87y (except for the 13.2 h 9/2 + isomer). The aim of the present work was to determine nanosecond lifetimes in this nucleus and to draw conclusions on the level structure especially with respect to the underlying core.…”