No abstract

Excited low-spin states of 92 Zr have been studied with the (n,n γ ) reaction. Comprehensive data on the electromagnetic decay of states with excitation energies up to about 3.8 MeV in particular, lifetimes, γ -ray branching ratios, multipole mixing ratios, and absolute transition strengths have been obtained. The detailed spectroscopic information about the low-spin level scheme enables us to address the predominant proton-neutron symmetry for low-spin states of 92 Zr. These data are compared to those of corresponding states in the N = 52 isotone 94 Mo and to a shell model calculation using 88 Sr as an inert core. However, neither a purely collective picture nor the restricted shell model calculation yields a fully satisfactory description of the observed structures. [1][2][3][4]. In neighboring 96 Ru 52 , the 2 + 1,ms state was found [5,6], and candidates for two-phonon MS states were assigned from E2/M1 mixing ratios, branching ratios, and lifetime limits [6].In vibrational nuclei, signatures of MS states, accessible through γ -ray spectroscopy at rather low excitation energies, are strong M1 transitions to symmetric states with the same phonon number with matrix elements of about | J f sym M1 J i ms | ≈ 1µ N , and weakly collective E2 transitions to symmetric states, since the latter transitions stem from the annihilation of a MS phonon Q ms . In contrast, we expect collective E2 transitions with transition strengths of several Weisskopf units between states with the same proton-neutron symmetry, e.g., from the MS two-phonon states to the 2 + 1,ms state from the annihilation of a symmetric phonon Q s . 0556-2813/2005/71(5)/054304(15)/$23.00 054304-1

No abstract

No abstract

Properties of low-spin states in 114 Cd have been studied with the (n, n γ ) reaction. Gamma-ray angular distributions and excitation functions have been used to characterize the decays of the excited levels. Level lifetimes have been obtained with the Doppler-shift attenuation method. Sixteen new levels and many new transitions have been suggested below 3.5 MeV in excitation energy. Levels belonging to the phonon multiplets have been proposed based on their decay patterns and collectivity, and the existing intruder structure has been extended. A two-phonon 1 + ms state has been suggested. Excitation of the hexadecapole moment has been considered. Data have been compared with the theoretical calculations of the interacting boson model.