16 research outputs found
Transition Quadrupole Moments at High Spin in 133Nd Rotational Bands
No full textLifetime measurements on the high-spin rotational bands in Nd-133 have been carried out by the Doppler-shift attenuation method using the GASP array. The Nd-133 nuclei were populated in the Pd-104(S-32, 2pn) reaction at a bombarding energy of 135 MeV. The Doppler-broadened line shapes were analyzed for Au-backed and Gd-backed targets. Values of Q(t) = 4.7(5), 5.6(5), and 7.4(4) eb have been determined for the mean transitional quadrupole moments of the ground-state band, the negative-parity band involving the neutron h(9/2)/f(7/2) intruder orbitals, and the band built on the neutron [660]1/2(+) intruder orbital, respectively. The presently determined quadrupole moments are compared with those of the low-spin members of the bands derived elsewhere from recoil distance method measurements. The observed polarizing effects of the neutron intruder orbitals are compared with cranked shell model predictions
Structure of the Odd-Odd-Nucleus 84Nb
No full textThe nucleus Nb-84 has been studied with the Ni-58(Si-28,pn gamma) reaction at 90 MeV. Several rotational structures are established and connected to an irregular low-energy level scheme which includes one isomeric level whose decay was observed before
New Nuclei Around the N=Z Line in the A=80-90 Region
No full textThe first identification of gamma-rays from excited states of the 85Mo and 88Ru nuclei is reported, together with a short discussion of the evolution of the nuclear structure along the N = Z and the N = 43, 44 lines
Yrast isomers in 95Ag, 95Pd, and 94Pd
No full textThe yrast level schemes of three neutron deficient nuclei with mass A≈95 have been studied with the reaction 58Ni+40Ca at 135 MeV, using the GASP γ-ray array, the ISIS silicon ball, and the n-ring neutron detector. Excited levels, including a (23/2+) spin-gap isomer, are reported for the first time in the heaviest N=Z+1 nucleus experimentally investigated, 95Ag. In 95Pd, the yrast line above the ground state has been observed and connected to states above the known isomeric level 21/2+, showing for the first time that this is indeed a spin-gap isomer. In 94Pd, the 95.6-keV isomeric transition was confirmed, and its E2 character was firmly established. The experimental observations are compared with current shell-model calculations
Observation of the N=Z=44 88Ru nucleus
No full textFour γ-ray transitions belonging to the ground state band of the N=Z nucleus 88Ru are reported for the first time. The reaction 58Ni(32S,2nγ) at 105 MeV has been used, and the prompt γ rays were detected with the GASP array. The assignment of γ rays to 88Ru was made by combining information from GASP, the ISIS silicon ball, and the n-Ring neutron detector. The 88Ru nucleus is weakly deformed, with an E(2+) energy of 0.616 MeV and E(4+)/E(2+) ratio of 2.30. The evolution of the nuclear structure along the N=Z, N=44, and Z=44 lines is discussed. Unlike in other nuclei from the region, no sign of backbending is seen in 88Ru at a rotational frequency of ≈0.5 MeV, which might be a signature of the T=0 neutron-proton pairing in the N=Z nuclei
First observation of excited states in the Tz = 1/2 nucleus 85Mo
No full textExcited states in the Tz=1/2 nucleus 85Mo have been observed for the first time with the reaction 58Ni(32S,αnγ) at 105 MeV. γ-ray transitions in this nucleus have been assigned unambiguously by combining the information from the GASP γ-ray array, the ISIS silicon ball, and the n-Ring neutron detector. Two band structures have been observed in this nucleus; they continue the smooth evolution of the known bands from the lighter N=43 isotones and have been tentatively assigned spins and parity on this basis. After reaching a maximum of collectivity at 83Zr, the trend with increasing mass is reversed, showing a smaller collectivity at 85Mo. The rotational behavior of the observed bands is discussed on the basis of the projected shell model calculations
The pih11/2 x nh 11/2 Yrast Band in Odd-Odd 140Tb
No full textThe pi h(11/2) x nu(11/2) yrast band in the odd-odd nucleus Tb-140 has been populated by the Mo-92 (Fe-54, alpha pn) reaction at 240-MeV incident beam energy. No previous spectroscopic information was known in this nucleus. The present data fit nicely in the systematics of the N = 75 isotones of La, Pr, Pm, Eu, and Tb (Z = 57 to 65)
