[en] Time-Of-Flight Medium Energy Ion Scattering (TOF-MEIS) experiments were performed to investigate the different energy loss mechanisms for slow Ne ions (a few keV/nucleon) in polycrystalline thin films of Ag and Pt deposited on Si. To disentangle electronic (S_e) and nuclear (S_n) contributions to the stopping power, Monte-Carlo (MC) simulations using the TRBS (TRim for BackScattering) code were conducted. The plateau-width of the experimental signal recorded in backscattering geometry was analyzed in order to extract additional information on the effective nuclear stopping. Electronic stopping powers were found to show the expected velocity dependence while the contribution from nuclear stopping was found low. The implications for experiments performed to study energy loss or related parameters are discussed.

[en] The TDPAD-technique was used to investigate the temperature dependence of the hyperfine magnetic field for ¹⁹F in ferromagnetic Fe, Ni and Gd. Systematic studies of the transient magnetic fields in ferromagnetic Gd and application in nuclear g-factor mesurements have been performed. Nuclear quadrupole moments in Ru-isotopes have been determined using the REPREC-method. A new technique for oxygen content and depth profiling has been developed. (author)

[en] A Monte-Carlo simulation of ion-beam optics in a gas-filled magnetic spectrometer has been conducted for ions at ∼1 MeV/amu corresponding to the energies achievable at the new Uppsala tandem accelerator (NEC 15SDH-2, 5 MV tandem Pelletron). Comprehensive calculations are performed for ³⁶Cl at 33-45 MeV kinetic energy with the following parameters: 1-5 Torr N₂ and 60-100 cm bending radii in a dipole magnetic field. It is shown that the separation between the ³⁶Cl and ³⁶S beams has a broad maximum in the interval 150-180 deg. at optimal gas pressures. A 150 deg. dipole magnet is preferable due to smaller beam extension in the non-deflection plane and larger residual energies. A dipole magnet with 180 deg. bending angle, 60 cm bending radius and 36 mm vacuum chamber height will be installed at the Uppsala Tandem Laboratory in November 2002

[en] The gyromagnetic ratios of the first excited Jsup(π) = 2⁺ states of ⁵⁰⁵⁴Cr, ⁵⁴Fe and ⁷⁰Ge have been determined by the ion-implantation perturbed angular correlation technique (IMPAC) with ferromagnetic Gd as stopping material. The deduced values are 0.52 +- 0.11, 0.49 +- 0.11, 1.24 +- 0.34 and 0.44 +- 0.17, respectively. With the exception of ⁵⁴Fe all g-factors are close to the collective value. A re-evaluation of earlier IMPAC data on ^70727476Ge with Fe as stopping material has been performed. The value obtained for ⁷⁰Ge is in good agreement with the one measured in this work. (Auth.)

[en] We present seasonal results of ¹²⁹I in fresh-water lakes located in central Sweden, an area over which the amount of fallout deposition from the Chernobyl accident varied significantly (2-120 kBq/m² for ¹³⁷Cs). ¹²⁹I concentrations in the lakes ranged from 2.1 to 15.0x10⁸ atoms per liter and did not show elevated concentration in lakes located in regions of high Chernobyl fallout. Apparently, the studied region is strongly influenced by ¹²⁹I releases from the reprocessing facilities through precipitation. Desorption or resuspension of ¹²⁹I from soils and sediments does not seem to be an active process to increase the concentration of ¹²⁹I in the lakes

[en] The ion-implantation perturbed angular correlation technique (IMPAC) was applied to the study of properties of Gd as stopping material. The transient magnetic fields at Fe, Ge, Mo, Ru, Pd, Cd and Te nuclei implanted into ferromagnetic Gd at 80 K were measured. The static magnetic hyperfine fields for Ru and Pd were deduced to be +65 +- 25 kG and -45 +- 23 kG, respectively. The Z₁-dependence could be fitted by the adjusted Lindhard-Winther theory except for the case of implanted Fe-nuclei. The deviating behaviour for the ⁵⁶Fe isotope was investigated in a separate experiment, where the dependence of the transient field was found to be directly proportional to the velocity of the recoiling ion. This result is in contradiction to the Lindhard-Winther model. Further consequences are discussed. (Auth.)

[en] In this study, we present a chemical extraction procedure and an evaluation of storage and pH effects on the ¹²⁹I concentration in water samples from a variety of hydrospheric reservoirs. Our data suggest that storage of samples does not cause a significant change of ¹²⁹I concentration whereas acidification of samples causes increase of ¹²⁹I concentration. A compilation of other AMS published data and ours on ¹²⁹I in the hydrosphere shows a wide range of variability

[en] The quadrupole moments of the first excited 2⁺ states in ¹⁰⁰¹⁰⁴Ru have been measured using the reorientation precession technique. In ¹⁰⁴Ru the sign of the Coulomb interference term P₄=Msub(02₁⁺)Msub(02₂⁺)Msub(2₂⁺2₁⁺)Msub(2₁⁺2₁⁺) was found to be P₄<0. The quadrupole moment in ¹⁰⁴Ru was determined to be -0.76 +- 0.19 eb. In ¹⁰⁰Ru the measurements revealed a quadrupole moment of -0.40 +- 0.12 eb independent of the sign of P₄. The experimentally determined values are compared with theoretical calculations. (Auth.)

[en] Short communication

[en] The thicknesses of the thin native oxygen layers on some metals have been determined by making use of the 3.05 MeV resonance in the elastic scattering reaction ¹⁶O(α,α)¹⁶O. The surfaces of iron have specially been studied for different ways of preparation e.g. evaporation, sputtering, passivation. The properties and possibilities of the method are discussed. Its advantageous application on interfaces is shown with a scanning investigation on an iron-aluminium sample. (Auth.)