Observation of the 02+ and γ bands in 98Ru, and shape coexistence in the Ru isotopes

An experimental view on shape coexistence in nuclei

“…The most extensive assignments of the single-particle states are for 99 Nb populated with single-proton transfer reactions on 100 Mo [294], and favour a spherical shape, in agreement with the lack of rotational bands. In 101 Tc, on the other hand, rotational-like bands appear that have been described as arising from its asymmetric rotor character [297], and they display a strong similarity to the ground-state bands of 100 Mo and 102 Ru, both of which have a triaxial nature [23,254].…”

“…The mixing in the crossing region resulted in both states taking on deformed characteristics. A recent study of 98 Ru [254] has revealed the presence of bands built on the 0 + 2 and 2 + 2 states. Shown in Fig.…”

“…It was noted that the 0 + − 2 + − 4 + level spacing of the ground-state band in 98 Ru matched that of the 0 + 2 band in 102 Ru, and the spacing in the 0 + 2 band in 98 Ru matched that of the ground-state band in 102 Ru. Focusing on the behaviour of the bands, rather than only the 0 + band heads, it was suggested [254] that the crossing of the configurations occurs between 98 Ru and 100 Ru. The Q 2 quantities for 100,102,104 Ru for the 0 + 1 and 0 + 2 states, listed in Tab.…”

“…+ 6Figure32: Observed excitation energies in the even-even Ru isotopes from A = 94 to A = 112 of states assigned to 0 + bands, and the 2 + 2 state.Data taken from the National Nuclear Data Center database [39] and Ref [254]…”

Coulomb excitation of Ru102 with C12 and Garrett1, Zielińska2, Bergmaier3 et al. 2022Phys. Rev. CSelf Cite

“…As a result of the mixing near the crossing, both 0 + states take on deformed characteristics. A recent study [21,22] combining the use of γ -ray spectroscopy following the β decay of 98 Rh and the 100 Ru(p, t ) 98 Ru reaction identified the 0 + 2 and "γ " bands in 98 Ru which fit well in the systematics of these excitations in the heavier Ru isotopes. It was noted that the energy spacings of states in the excited 0 + 2 band in 98 Ru bore a strong similarity to those of the ground-state band in 102 Ru, and from a two-band-mixing analysis it was suggested [21] that the configuration crossing occurs between 98 Ru and 100 Ru.…”