Structure of excited states in100Mo and102Mo from spectroscopy using18O induced reactions

Abstract

Abstract. The lifetimes have been determined for the 2 +, 0 +' and 4 + states in l~176 and lOZMo using the recoil-distance Doppler-shift method. The states have been excited in l~176 by Coulomb excitation and in 1~ by the two-neutron transfer reaction induced by 180 ions on a l~176 target. The study of the excitation function for the elastic and inelastic scattering on the ground and first excited 2 + state in a~176 at beam energies between 20 and 61 MeV shows that 40 MeV is the highest incident energy for pure Coulomb excitation. Above this energy nuclear absorption sets in and nuclear scattering contributes to the excitation of the 2 + state of l~176 From the lifetimes of the 2 + and 4 + states deformation parameters of [/3] =0.21 and 1//1 =0.31 for ~~176 and ~~ respectively were deduced. The 0 +' levels are not shape isomeric states, as suggested earlier, but they decay by enhanced E2 transitions to the first 2 + states. From a comparison with similar states in other transitional nuclei it is suggested that they are band heads for /3 vibrational bands.

Lifetime measurement of neutron-rich even-even molybdenum isotopes

“…We note that the 4 + to 2 + transition in 102 Mo is just in agreement with the literature value from Ref. [46]. A possible reason could be the existence of a feeder state that cannot be determined in this experiment.…”

The?-decay of100Y: Discovery of a very low lying 0+ state in100Zr

“…Moreover the E0 transition should be very strongly enhanced over the E2 transition contrary to observation in the present case. It has been proposed that the second excited levels of J~ =0 + in the transitional molybdenium isotopes are the band heads of/?-vibrations [31]. Such an explanation in the present case would be consistent with the fact that the 0~-state is below the pairing gap and that the E2 transition from it to the 2[ state is fairly strong.…”

“…A number of explanations for the occurence of low lying 0 + states in transitional nuclei in general [20] and in even Zr and Mo isotopes in particular [29,24,30,31] have been proposed. Among these are pairing vibrations [29], band heads of fi-vibrations [31], states orthogonal to the ground state [30] and band heads of rotational and vibrational bands caused by a coexistence of spherical and deformed nuclear shapes [7] (see Fig. 1).…”

The decay scheme of the 3-s Isomer of100Nb and the properties of levels in100Mo

“…Spins and parities of several levels had been determined or suggested before, and they are sup- in the 2~ -, 2f transition of 528 keV is in agreement with the vibrational model if differences in the behaviour of the protons and neutrons are taken into consideration. Indeed, a value of a=2.1 results from the formalism of [18] with the ratio of the pairing forces of protons and neutrons of Ge/GN = 30/20 and an average deformation [19] of/7o=0.21. In the frame of the vibrational model, the levels with P= 2 +, 0 § and (3 +) at 1,464, 1,505 at 1,607 keV might be 3 of the 5 members of the three-phonon quintet 9 Here, the agreement between the data and the vibrational model is not so good: the 1,464 keV level decays strongly into the 0~--state at 695 keV.…”