[en] Resonance ionization mass spectrometry is an efficient tool for detecting trace amounts of long-lived radio-isotopes in environmental samples. For absolute quantification a tracer with identical atomic properties and chemical behavior is needed to prevent a possible dependency onto the absolute efficiency for the analytical method. For an application in ⁹⁹Tc, the isotope ⁹⁷Tc could serve as a potential tracer. Therefore the optical transitions of an efficient ionization scheme for technetium were investigated for the two odd mass isotopes ⁹⁷Tc,⁹⁹Tc, both with a nuclear spin of I=9/2. Using a pulsed, single mode laser with narrow bandwidth, the hyperfine structures (HFS) of two transitions were fully resolved. The observed isotope shift is small in comparison to the width of the hyperfine structure splitting. This is ideal for the application of ⁹⁷Tc as tracer isotope for ⁹⁹Tc quantification. The evaluation of the observed HFS splitting results in a first experimental value for the magnetic dipole for ⁹⁷Tc of μ = +5.82(9) μ(N). (authors)

[en] We review structure data obtained by decay spectroscopy of neutron-rich nuclei of mass close to 100. Emphasis is put on the contribution of experiments at IGISOL in the nineties. They confirmed the earlier postulated shape coexistence in the fast shape-transition region between N = 58 (spherical ground states and low collectivity) and N = 60 (strong axial deformation). A detailed spectroscopic study of the A = 99 chain established the upper-Z limit of the N = 56 shell closure region with "9"9Nb, owing to striking similarities with "9"7Y. A consequence of the N = 56 closure is that the s_1_/_2 odd-neutron becomes the ground state of the most neutron-rich N = 57 isotones, starting with "9"9Mo, instead of the degenerated d_5_/_2 and g_7_/_2 subshells familiar in the tin region. Consequences on the change of spin on astrophysical r process calculations are briefly discussed. Finally, we say a few words about neutron rich rhodium and palladium isotopes near the neutron mid-shell where regular and intruder states coexist very close to each other. (authors)

[en] Cross-sections for nuclide production in fast-neutron induced fission of natural uranium are part of the input for predictions of yields of neutron-rich nuclides obtainable at Radioactive Ion Beam facilities. We first describe the neutron spectra produced according to the scheme once envisaged for SPES (protons on an enriched "1"3C target) and the one adopted for SPIRAL2 (deuterons on natural carbon), which both have been measured at JYFL. We then present the measurements of Z-splits in isobaric chains performed at IGISOL. When coupled with the fission cross-section and A-splits for the relevant neutron spectrum, they allow estimates of nuclide cross-sections. It looks that calculations, even those based on modern libraries, are too optimistic by about a factor of two. (authors)

[en] The study of β-delayed neutron emission plays a major role in different fields such as nuclear technology, nuclear astrophysics and nuclear structure. However the quality of the existing experimental data nowadays is not sufficient for the various technical and scientific applications and new high precision measurements are necessary to improve the data bases. One key aspect to the success of these high precision measurements is the use of a very pure ion beam that ensures that only the ion of interest is produced. The combination of the IGISOL mass separator with the JYFLTRAP Penning trap is an excellent tool for this type of measurement because of the ability to deliver isobarically and even isomerically clean beams. Another key feature of the installation is the non-chemical selectivity of the IGISOL ion source which allows measurements in the important region of refractory elements. This paper summarises the β-delayed neutron emission studies that have been carried out at the IGISOL facility with two different neutron detectors based on "3He counters in a polyethylene moderator: the Mainz neutron detector and the Beta delayed Neutron detector. (authors)

[en] A measurement of the hyperfine interactions on swift ²⁸Si, ¹¹⁰Pd, and ¹⁹⁴Pt ions recoiling through magnetized iron and nickel foils indicates that for these ions the strength of the transient magnetic field scales with the net magnetization of the ferromagnet. (orig.)

[en] The nuclear hyperfine structure of dilute impurity iron ions in ferroelectric lithium niobate is investigated via ⁵⁷Fe Moessbauer effect (ME). The ME spectra exhibit typical slow electron spin relaxation effects associated with Fe³⁺ ions in the ⁶Ssub(5/2) state, which are analysed using spin-Hamiltonian formalism. For Fe³⁺ ions, the principal axis of EFG tensor is found to be parallel to the crystallographic c-axis. The strong external magnetic field of 47 KOe is used to study magnetic and crystal field effects on the ME hyperfine structure. (orig.)

[en] The hyperfine interaction of the system ¹⁸³Re(70d) Fe has been investigated with the NMR/ON technique. With the hyperfine field value Bsub(h)sub(f)(ReFe) = -76.0(1.5)T the ground state magnetic moment was determined as: μ(5/2⁺, ¹⁸³Re) = + 3.12(6) μsub(N). The field dependent nuclear spin-lattice relaxation time has been measured. The result for the high-field relaxation rate Rsub(e)sub(x)sub(p) = 1.65(5) x 10^-15 T² s K^-1 is explained in terms of indirect spin-wave interaction. (orig.)

[en] The radiation damage effects on the electric quadrupole interaction (QI) for the system SnCd were investigated with the time-differential perturbed angular distribution (TDPAD) method and three nuclear reaction recoil Sn probes, in the temperature range from 80 to 590 K. The obtained results are consistent with a static defect QI strength distribution (delta approx. equal to 10%) around a mean value comparable with the unique QI strength corresponding to the undistorted crystal lattice. (orig.)

[en] The authors present perturbed angular correlation (PAC) measurements on ¹⁰⁰Rh and ¹¹¹Cd in a number of dilute alloys of Cu, Ag and Au. They discuss the electric field gradient (EFG) values derived from these and other experiments in the framework of a theory of the EFG at nearest neighbours of point defects in metals, essentially based on the screening of a point charge in a free electron gas. The EFG due to a neighbour monovacancy for a number of fcc metals is included. (Auth.)

[en] From low-temperature Moessbauer measurements on FeC₂O₄.2D₂O the reported difference in quadrupole splitting from the simple dihydrate is inferred to be due to lattice effects. The Zeeman split spectrum has been analyzed taking into account the 'ambiguity problem' and the hyperfine parameters were determined to be I.S. = 1.22 mm/sec; Q.S. = 1.93 mm/sec; eta = 0.65 to 0.72; theta = 90 to 83.1⁰ and phi = 0 to 11.8⁰. The principal electric field gradient axis lies along the crystal a-axis with Vsub(yy) and H lying along the crystal b-axis. The crystal field parameters 10Dq, Ds and Dt have been determined to be approx. 10500, approx. 185 and approx. 211 cm^-1, respectively. (Auth.)