[en] In the vicinity of neutron drip line, due to loosely bound neutron/s a large fraction of dipole strength is expected at low excitation energies. Thus a measurement of the dipole response could be an important tool to investigate the intricacies of the structure of exotic nuclei. In this presentation the new experimental results are reported on the dipole response of light neutron-rich nuclei in the mass region around A = 20

No abstract available

[en] The dipole response of stable and unstable neutron-rich oxygen nuclei of masses A=17 to A=22 has been investigated experimentally utilizing electromagnetic excitation in heavy-ion collisions at beam energies about 600 MeV/nucleon . A kinematically complete measurement of the neutron decay channel in inelastic scattering of the secondary beam projectiles from a Pb target was performed. Differential electromagnetic excitation cross sections dσ/dE were derived up to 30MeV excitation energy. In contrast to stable nuclei, the deduced dipole strength distribution appears to be strongly fragmented and systematically exhibits a considerable fraction of low-lying strength

[en] One-nucleon removal reactions at relativistic energies have been used as a spectroscopic tool to characterise the ground state properties of several neutron-rich isotopes in the sd-shell. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after one-nucleon removal were measured. The relative contributions of the remaining fragments in their ground and excited states have been determined from measurements of γ rays in coincidence with the longitudinal momentum distributions. In particular the breakup of ²³O has been investigated. The interpretation of our measurements, in the framework of a simple theoretical model, favours a spin and parity assignment of 1/2⁺ for the ²³O ground state in agreement with shell model predictions

No abstract available

[en] Electromagnetic and nuclear inelastic scattering of the halo nucleus ¹¹Be have been investigated by a measurement of the one-neutron removal channel, utilizing a secondary ¹¹Be beam with an energy of 520 MeV/nucleon impinging on lead and carbon targets. All decay products, i.e. ¹⁰Be fragments, neutrons, and gamma-rays have been detected in coincidence. Partial cross sections for the population of ground and excited states in ¹⁰Be were determined for nuclear diffractive breakup as well as for electromagnetically induced breakup. The partial cross sections for ground-state transitions have been differentiated further with respect to excitation energy, and the dipole-strength function associated solely with transitions of the halo 2s_1/2 neutron to the continuum has been derived. The extracted dipole strength integrated from the neutron threshold up to 6.1 MeV excitation energy amounts to 0.90(6) e²fm². A spectroscopic factor for the ν2s_1/2 x ¹⁰Be(0⁺) single-particle configuration of 0.61(5) and a root-mean-square radius of the 2s_1/2 neutron wave function of 5.7(4) fm have been deduced. (orig.)

[en] Experimental data on energy loss and energy-loss straggling of fully ionized relativistic heavy ions agree well with the theory of Lindhard and Soerensen (LS). However, when heavy ions penetrate matter with many fluctuating ionic charge states the theoretical description is more complicate and less accurate. A novel exploratory step to contribute to a better understanding of the slowing down of heavy ions has been done with the present experiment in an energy region where the atomic interaction is still dominated by bare and few-electron projectiles. In the energy range of 100-1000 MeV/u we measured with the high-resolution magnetic spectrometer FRS the stopping powers, the energy-loss straggling and the charge-state distributions of ¹⁹⁷Au, ²⁰⁸Pb and ²⁰⁹Bi projectiles in charge-state equilibrium interacting with solids ranging from beryllium to lead targets. Additionally, charge exchange cross-sections have been measured to support a better analysis and interpretation of the energy-loss data. The experimental results on stopping power and energy-loss straggling clearly demonstrate the contribution of ions in different charge states. A novel application of the slowing down of relativistic exotic heavy ions is presented

[en] Coulomb breakup of unstable neutron-rich carbon isotopes ^15,17C has been studied at energies around ∼500-600 MeV/nucleon. Non-resonant low-lying dipole strength is observed in these isotopes which can be explained by a direct breakup mechanism. In addition to the decay neutron from excited projectile, γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence, giving access to quantitative spectroscopic information. The spectroscopic factor deduced for a valence neutron occupying the s_1/2 level in the ¹⁵C ground state is consistent with that obtained earlier from (d,p) transfer reactions. The analysis for Coulomb breakup of ¹⁷C shows that most of the cross section yields the ¹⁶C core in excited states. The predominant ground-state configuration of ¹⁷C is found to be ¹⁶C(2⁺) x ν_sd

[en] A magnetic microwire is a continuous filament of total diameter less than 100 μm consisting of an inner metallic magnetic nuclei covered by a glassy outer shell, usually obtained by Taylor's technique, with interesting magnetic properties connected with its high axial magnetic anisotropy. Magnetic sensors based on microwires used, as operating principle, the strong connection between the composition and the uniaxial anisotropy through a magnetostriction constant such as the large Barkhausen effect, Mateucci effect and giant magneto-impedance effect. The study of the microwave properties is also very promising technologically. In the microwave region (approaching GHz range), the ferromagnetic resonance (FMR) occurs and it is connected with the spin precession of the magnetisation vector due to the effect of the high-frequency electromagnetic field applied such that the magnetic component is perpendicular to the magnetisation vector. The natural ferromagnetic resonance (NFMR) has been also observed. The frequency depends upon the value of magnetic anisotropy and it is characterised by the single well-distinguished line in the 2-10 GHz range. Tags detector based on the microwires FMR and a new kind of electromagnetic radiation absorbers based on the microwires NFMR have been developed

[en] Dipole excitations of unstable short-lived nuclei has been investigated experimentally by utilizing the electromagnetic-excitation process with high-energy secondary beams. From an exclusive measurement of the neutron-decay channels, differential cross sections with respect to excitation energy, which are directly related to the photo-absorption cross section and accordingly to the dipole-strength function, have been derived. Light neutron-rich nuclei in the mass range from A = 11 to A = 23 with mass-over-charge ratios up to ((A)/(Z)) ∼ 2.8 have been investigated systematically. Much in contrast to stable nuclei, low-lying dipole excitations well below the giant dipole resonance region have been observed as a general phenomenon for these neutron-proton asymmetric nuclei. For the neutron-rich oxygen isotopes, for instance, low-lying E1 strength has been observed exhausting about 10% of the classical dipole sum rule below 15 MeV excitation energy. A quantitative analysis of low-lying threshold strength for loosely bound nuclei indicates that the characteristics of the dipole strength is directly related to the ground-state single-particle structure of the valence nucleon in the projectile