First identification of excited states in the Tz_z = 1/2 nucleus 93^{93}Pd

The first experimental information about excited states in the N = Z + 1 nucleus 93Pd is presented. The experiment was performed using a 205 MeV 58Ni beam from the Vivitron accelerator at IReS, Strasbourg, impinging on a bismuth-backed 40Ca target. Gamma-rays, neutrons and charged particles emitted in the reactions were detected using the Ge detector array Euroball, the Neutron Wall liquid-scintillator array and the Euclides Si charged-particle detector system. The experimental level scheme is compared with the results of new shell model calculations which predict a coupling scheme with aligned neutron-proton pairs to greatly influence the level structure of $N\approx Z$ nuclei at low excitation energies

Shape evolution in the superdeformed A ≈ 80-90 mass region

Superdeformed bands in 88Mo, 89Tc, and 91Tc were populated using a 40Ca beam with an energy of 185 MeV, impinging on a backed 58Ni target, γ rays and charged particles emitted in the reactions were detected using the Gammasphere Ge detector array and the CsI(Tl) array Microball. Average transition quadrupole moments Qt, with significantly improved accuracy compared to earlier work, were deduced for the bands using the residual doppler shift technique. The experimental results were included into a systematic study of the Q t values throughout the superdeformed mass 80-90 region. The superdeformed shell gaps are predicted to move towards larger deformations with increasing Z and N in this mass region. This trend is confirmed by the experimental Qt values

Isospectral superdeformed bands in the N = 46 nuclei

Superdeformed bands in 88Mo and 89Tc were populated using 40Ca-induced fusion-evaporation reactions on 58Ni at a beam energy of 185MeV. Gamma-rays emitted in the reactions were detected using the Gammasphere spectrometer, in coincidence with charged particles detected by the Microball array. A new superdeformed band was assigned to the nucleus 88Mo, leading to a revisit of earlier configuration assignments for superdeformed structures in this nucleus. In particular, the theoretical interpretation of a pair of identical (isospectral) superdeformed bands in 88Mo/89Tc is discussed. The configurations that are assigned to the four SD bands belonging to 88Mo have properties that are predicted to be significantly affected by pair correlations

Observation of 54Ni: Cross-Conjugate Symmetry in f7/2 Mirror Energy Differences

Gamma decays from excited states up to J(pi)=6(+) in the N=Z-2 nucleus Ni-54 have been identified for the first time. Level energies are compared with those of the isobars Co-54 and Fe-54 and of the cross-conjugate nuclei of mass A=42. The good but puzzling f(7/2) cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials

Evidence for excited states in \chem{^{95}Ag}

The first evidence for excited states in \chem{^{95}{Ag}} is presented. \chem{^{95}{Ag}} is the heaviest $T_z=1/2$ nucleus for which gamma-rays have been identified. The reaction \chem{^{40}{Ca}}(\chem{^{58}{Ni}}, 1p2n)\chem{^{95}{Ag}} was used in the experiment, which resulted in the assignment of three gamma-rays to \chem{^{95}{Ag}}. A detector system consisting of the detector arrays Euroball, Neutron Wall and Euclides was used to detect gamma-rays, neutrons and charged particles, respectively

gamma-ray spectroscopy with a ⁸He beam

Matière Nucléair

Observation of 54Ni: Cross-Conjugate Symmetry in f7/2 Mirror Energy Differences

Gamma decays from excited states up to J\u3c0=6+ in the N=Z-2 nucleus 54Ni have been identified for the first time. Level energies are compared with those of the isobars 54Co and 54Fe and of the cross-conjugate nuclei of mass A=42. The good but puzzling f7/2 cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials

Observation of Ni-54 : Cross-Conjugate Symmetry in f(7/2) Mirror Energy Differences

Gamma decays from excited states up to J(pi)=6() in the N=Z-2 nucleus Ni-54 have been identified for the first time. Level energies are compared with those of the isobars Co-54 and Fe-54 and of the cross-conjugate nuclei of mass A=42. The good but puzzling f(7/2) cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.</p