High-spin states in89Nb,88Zr and88Nb with a shell-model description of theN=48 andN=47 nuclei

Abstract

The reactions 89y(~, 4n7), 89y(c~, p4nT) and 89y(~, 5ny) were used to populate high-spin states in, respectively, 89Nb, 8SZr and the previously unstudied nucleus SSNb. These states were deduced via in-beam gamma-ray spectroscopy. The results of a shell-model study of N=48 SSZr, 9~STy, 89Nb and N=47 87Zr, SSNb nuclei are compared to experiment.

Electromagnetic decay strengths in the isobars89Nb,89Mo and89Tc

“…The flux pattern and time evolution in 89Nb are dominated by the lifetime of the 3806 keV 25/2-state which feeds both the negative and the positive parity cascades. Taking into account its rather long lifetime -established as 50 (2) ps in the present work -this will cause large uncertainties in the determination of the shorter lifetimes of the states fed by it. The fit of the R(d) functions gives even larger errors for the positive parity states below 3403 keV because of the presence of both very short and very long feedings in similar proportions.…”

“…Relative to this core, the large number of protons and neutron holes in the 99/2 orbit provides high spins without the need of including collective excitations. However, the existence of quadrupole vibrations has been suggested to be essential in the low-spin region [2]. In calculations by Gross and Frenkel for N = 48 nuclei [1], the energies of the U = 0~, 2~,0~, 2~ and 4~ states were predicted too high as compared to the experimental observation when the level schemes were normalized to their 8 + states.…”

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

“…2 and 3, respectively. The corresponding multi-qnasiparticle configurations responsible for the formation of both ((/) and (f)) levels involved are given in col. 4 …”

“…Some theoretical studies concerning the structure of this nucleus were recently performed within the shell-model [4] and the cluster-phonon model [5].…”

Identification and structure of high spin particle-hole states in89Mo

“…Especially for x = 2, 3, a separation of the 4p-and the 5p-evaporation channel is possible. Furthermore, the 5pn-evaporation channel is SSNb which is known [17]. In this way, a number of rather strong radiations were identified as prompt transitions in 89Mo" Figure 1 illustrates projections of the y7 coincidence matrix (top) and of particle-gated yy-matrices in which the prominent lines in various evaporation residues are marked.…”