Low-spin collective behavior in the transitional nucleiMo86,88

Abstract

Low-spin structures in 86,88 Mo were populated using the 58 Ni( 36 Ar, xαyp) heavy-ion fusion-evaporation reaction at a beam energy of 111 MeV. Charged particles and γ rays were emitted in the reactions and detected by the DIAMANT CsI ball and the EXOGAM Ge array, respectively. In addition to the previously reported low-to-medium spin states in these nuclei, new low-spin structures were observed. Angular correlation and linear polarization measurements were performed in order to unambiguously determine the spins and parities of intensely populated states in 88 Mo. Quasiparticle Random Phase Approximation (QRPA) calculations were performed for the first and second excited 2 + states in 86 Mo and 88 Mo. The results are in qualitative agreement with the experimental results, supporting a collective interpretation of the low-spin states for these transitional nuclei.

N=Znuclei: a laboratory for neutron–proton collective mode

“…6 we plotted the experimental spectra of three even-A neutron-deficient Pd isotopes. As one would expect, in 96 Pd with four proton holes with respect to 100 Sn, the positions of the energy levels correspond to a (g 9/2 ) 2 λ isovector pairing (or seniority) spectrum. In particular, the yrast 8 + state, which has the largest spin among the v = 2 states, shows a typical pattern for isomeric states as induced by the seniority coupling.…”

“…This is the heaviest N = Z nucleus with measured spectrum so far. It was suggested that in this nucleus, as well as in neighboring nuclei like 96 Cd, the properties of the low-lying states can be classified by a spin-aligned np pair coupling scheme [62,63]. That is, the ground state wave functions do not consist mainly of pairs of neutrons (νν) and protons (ππ) coupled to zero angular momenta, but rather of isoscalar np pairs (νπ) coupled to the maximum angular momentum J, which in the shell 0g 9/2 is J = 9 [62,63].…”

“…The regular pattern was first noticed by J. Blomqvist. He explained that in terms of aligned np pairs in a scheme that is sim- Ex (MeV) 96 Pd,Exp. 96 Pd,Theo.…”

“…He explained that in terms of aligned np pairs in a scheme that is sim- Ex (MeV) 96 Pd,Exp. 96 Pd,Theo. ilar to the stretched scheme as described in Ref.…”

“…For example, in the hole-hole channel, the ground state wave function of 96 Cd is calculated to be [63],…”