[en] The ratio of the quadrupole moment of the 8⁺ isomers in ²⁰²Po and ²⁰⁴Po has been measured in a Pt host using the level mixing spectroscopy method: Q(²⁰²Po)/Q(²⁰⁴Po)=1.06(13). The increase of the Po(8⁺) quadrupole moments with decreasing neutron number can be explained by explicitly taking into account the interaction between the vertical stroke π1h²_9/2 right angle two-proton configuration and the core quadrupole vibrational excitations of the underlying even-even Pb core. A very good quantitative agreement is observed, indicating that core polarization near the Z=82, N=126 closed-shell region can be understood by particle-core coupling. (orig.)

[en] An extension of the time-integrated atomic decoupling technique to measure g-factors of (sub)nanosecond isomers and/or the magnetic hyperfine field induced by highly excited atomic electrons on nuclei recoiling into vacuum is discussed. A high average field B_hf=1080_-175⁺²⁷⁰ T and an average atomic spin J=2.7(2) is deduced using the known magnetic moment of a 4.05(7) μs isomer in ⁶⁹Ge. Such high magnetic fields allow g-factor measurements of (sub)nanosecond states. Ab initio calculations show that the combination of a high average magnetic hyperfine field and a high average atomic spin is only possible if a considerable fraction of the ions is in a metastable excited state

No abstract available

[en] An overview of some recent results on nuclear moment measurements on isomers is being given. Neutron rich isomers have been produced in a fragmentation reaction at GANIL. Using the spin-orientation of the fragment beam, isomeric g-factors around ⁶⁸Ni have been measured by detecting the Larmor precession via the isomeric γ-decay (TDPAD-method). Isomers in the mass A∼180 region were produced in a fusion-evaporation reaction at Louvain-la-Neuve. The quadrupole moment of a 5 quasi-particle isomer in the deformed nucleus ¹⁷⁹W was measured using the Level Mixing Spectroscopy (LEMS) method. Both results show how details on the nuclear structure can be investigated via nuclear moment measurements. (author)

[en] The Level Mixing Spectroscopy (LEMS) method has proven to be a powerful method to determine the quadrupole moment of high spin isomers. There are some limitations on the use of the method which are due to the fact that a non cubic host providing an electric field gradient and a large superconducting magnet are needed. In this contribution we report on the use of cubic host materials as a first expansion of the applicability of the LEMS method towards a wider region on the nuclear chart. In two experiments we have shown that a defect-associated electric field gradient, induced by the nuclear reaction in a cubic host material, is reproducible and can be used to determine quadrupole moments. We also discuss how the use of magnetic host materials cancels the need for a superconducting magnet by taking advantage of the very strong, temperature dependent hyperfine fields near the Curie temperature. (author)

[en] We report the results of recent measurements of the spectroscopic quadrupole moments of high-spin isomers. For the K^π=35^-/2 five-quasiparticle isomer in ¹⁷⁹W we measured Q_s = 4.00((+0.83)(-1.06)) eb. It corresponds to a smaller deformation compared to the ground states of the W isotopes and is in disagreement with the current theoretical predictions. We also measured the quadrupole moment of the I^π=11^- isomer in ¹⁹⁶Pb, Q_s= -3.41(66) eb. It has the same proton ((s_1/2)^-2h_9/2i_13/2) configuration as the one suggested for the I^π =16^(-) magnetic bandhead which allows to deduce the quadrupole moment of the 16^- state as Q_s = -0.316(97) eb. This small value proves the near sphericity of the bandhead. (author)

No abstract available

[en] The Level Mixing Resonance (LMR) technique allows to determine ground-state nuclear moments by measuring the spin-polarization of the beta-decay, and starting from an initially aligned ensemble of nuclei. Using this new technique, the ratio of the quadrupole frequency to the magnetic moment of the neutron rich ¹⁸N ground state has been measured: ν_Q/ν(¹⁸NMg/) = 1328(33) kHz/n.m. In order to measure the nuclear moments independently, the Nuclear Magnetic Resonance (NMR) and LMR techniques will be combined. (author)

No abstract available

[en] A significant reduction of absorption of single gamma photons has been observed using the Moessbauer spectra of ⁵⁷Fe in a FeCO₃ crystal. The absorption deficit can be ascribed to partially destructive interference for absorption because of two indistinguishable absorption paths. The necessary coherence is created by means of level mixing produced by a suitable combination of a magnetic dipole and electric quadrupole interaction.