Search

A novel analytical model is proposed for establishing design criteria based on the decomposition of the in-plane deformation and out-of-plane stability states. First part of this study considered the in-plane buckling resistance of beam–columns. This study uses the results from Gizejowski et al. [42] to develop an analytical model for the inelastic out-of-plane buckling resistance of beam–columns subjected to a moment gradient. The elastic flexural–torsional buckling solution is combined with the in-plane solution via the generalised Ayrton–Perry model. In order to unify the recommendations for the resistance evaluation of beams, columns, and beam–columns, the model is customised to conform to the standard Eurocode technique of modelling buckling resistance of steel elements in compression or bending about the cross-sectional axis with the greater moment of inertia. As a result, the out-of-plane resistance interaction curves, expressed in dimensionless coordinates, which describe the beam–column flexural–torsional buckling resistance and consider lateral–torsional buckling effects, are obtained. The results of finite element simulations are used for the verification of the developed analytical formulation. Two numerical techniques of imperfection modelling are used: an equivalent geometric imperfection approach with the Maquoi–Rondal generalised initial imperfection and an approach that individually considers geometric and material imperfections. The results obtained from the proposed analytical model and those obtained using the Eurocode design criteria and other recent analytical proposals are compared. Finally, concluding remarks and directions of future studies are also presented.

Buckling resistance predictions resulting from flexural and flexural–torsional buckling of double tee section members subjected to compression and bending are considered. A novel analytical model is developed for establishing design criteria based on decomposition of the member buckling behaviour into in-plane and out-of-plane resistance. The former is based on second-order bending relationships of load effects of structural members with in-plane equivalent imperfections, while the latter is based on the stability theory of thin-walled open sections. First part of this study presents an analytical formulation of the in-plane buckling resistance of beam–columns. In this regard, further decomposition is postulated for the in-plane first-order bending moment diagram that results in the loading state to be the superposition of two components. The first component is related to symmetrical loading and the second to antisymmetric loading. To consider the second-order effects, prebuckling displacements generated by the abovementioned loading components are amplified with regard to the inversion of the residuum of the buckling force utilisation ratio in order to obtain approximate values of second-order displacements and internal moments. As a result, the in-plane interaction curve, expressed in dimensionless coordinates, that describes the beam–column in-plane flexural buckling resistance without considering lateral–torsional buckling effects, is obtained. The results of nonlinear finite element simulations are used for the verification of the developed analytical formulation. It is concluded that this proposal yields less conservative predictions than those based on the interaction relationships of clause 6.3.3 of Eurocode 3, Part 1–1.

Laterally and torsionally unrestrained steel I-section beams are susceptible to torsional deformations between supports; therefore, according to Part 1-1 of Eurocode 3, they need to be designed to resist lateral-torsional buckling. Eurocode’s steelwork design criteria require safety checking based on two stability interaction formulae utilizing the so-called equivalent uniform moment factors and the cross-section resistance formula that, in the case of moment gradient, refer to the beam end section. Uncoupling the beam stability resistance criterion and the cross-section resistance criterion may result in a nonuniform safety assessment of I-section beams. Finite element simulations of the beam resistance for different moment gradient ratios are performed. Verification of the buckling resistance is conducted by varying the following parameters: the slenderness ratio, the location of maximum end moments about both axes and the section depth-to-width ratio (i.e., considering rolled I- and H-sections). The variation in the accuracy of the current Eurocode resistance evaluation method is identified, and an approach for a better equalization of the safety predictions is suggested by considering different values of the most important factors influencing the stability performance of steel I-section beams.

Steel I-section members subjected to compression a monoaxial bending about the major axis are dealt with in this paper. The current Eurocode’s design procedure of such members is based on a set of two interpolation equations. In this paper a simple and yet consistent Ayrton-Perry methodology is presented that for beam-columns yields the Ayrton-Perry design strategy similar to that utilized in the steel Eurocodes for design of beams and columns but not used so far for the beam-column design. The results from developed design criterion are compared with those of Method 1 of Eurocode 3 and the Ayrton-Perry formulation of a different format that has been recently published.

The article describes an X-ray microbeam standalone facility dedicated for irradiation of living cultured cells. The article can serve as an advice for such facilities construction, as it begins from engineering details, through mathematical modeling and experimental procedures, ending up with preliminary experimental results and conclusions. The presented system consists of an open type X-ray tube with microfocusing down to about 2 μm, an X-ray focusing system with optical elements arranged in the nested Kirckpatrick-Baez (or Montel) geometry, a sample stand and an optical microscope with a scientific digital CCD camera. For the beam visualisation an X-ray sensitive CCD camera and a spectral detector are used, as well as a scintillator screen combined with the microscope. A method of precise one by one irradiation of previously chosen cells is presented, as well as a fast method of uniform irradiation of a chosen sample area. Mathematical models of beam and cell with calculations of kerma and dose are presented. The experiments on dose-effect relationship, kinetics of DNA double strand breaks repair, as well as micronuclei observation were performed on PC-3 (Prostate Cancer) cultured cells. The cells were seeded and irradiated on Mylar foil, which covered a hole drilled in the Petri dish. DNA lesions were visualised with γ-H2AX marker combined with Alexa Fluor 488 fluorescent dye.

The authors focused on buckling resistance assessment of steel-I-section perfect beam-columns of the cross-section class 1 and 2, not susceptible to LT-buckling and subjected to compression and one directional bending about the section principal axes y–y or z–z. These assumptions lead to the case of elements considered as only sensitive to the flexural failure including second order in-plane bending and compression. The stability behaviour of elements subjected to different bending configurations and different static schemes was investigated through comprehensive numerical study with use of the finite element method. Geometrically and materially nonlinear analyses GMNA in case of perfect beam-columns and GMNIA fo the imperfect ones were carried out in reference to shell and beam element models. Static equilibrium paths accounting for pre- and post-limit behaviour were determined with use of the incremental-iterative algorithm taking into consideration displacement-control parameters. An analytical formulation for a quick verification of the perfect I-section beam-column resistance is proposed. Finally, the global effect of imperfections is also investigated using GMNIA. The verification method developed for perfect elements is extrapolated for imperfect beam-columns. The good agreement of the proposed analytical formulation is shown through an extensive comparison with more than 3500 results of finite element numerical simulations conducted with use of ABAQUS/Standard program.

The critical moment analytical expressions used in engineering design are based on the thin-walled beam model of warping torsion and the linear eigenvalue analysis (LEA) while the analytical formulation of the buckling curve equation follows the Ayrton-Perry model with the Maquoi-Rondal initial imperfection parameter. Using the equivalent geometric imperfection concept for the resistance prediction, the Maquoi-Rondal initial imperfection amplitude for lateral-torsional buckling is usually related to the equivalent minor axis bow amplitude or the twist rotation amplitude for the lowest eigenmode imperfection profile. Such concept is also used in this paper for the evaluation of the buckling resistance of beams in bi-axial bending. Recent investigations based on the so-called GMNA+ large displacements analysis have shown that the LTB critical moment evaluated with use of LEA needs to be modified in order to account for the fact that H-section slender beams may fail by developing large inelastic twist rotations, the effect that is not included in the elastic linear buckling theory. In the present study, the influence of critical moment predictions on the LTB resistance evaluation is dealt with and the analytical formulation is proposed. Comparisons of the buckling curve formulations are presented.

Assessment of the flexural buckling resistance of bisymmetrical I-section beam-columns using FEM is widely discussed in the paper with regard to their imperfect model. The concept of equivalent geometric imperfections is applied in compliance with the so-called Eurocode’s general method. Various imperfection profiles are considered. The global effect of imperfections on the real compression members behaviour is illustrated by the comparison of imperfect beam-columns resistance and the resistance of their perfect counterparts. Numerous FEM simulations with regard to the stability behaviour of laterally and torsionally restrained steel structural elements of hot-rolled wide flange HEB section subjected to both compression and bending about the major or minor principal axes were performed. Geometrically and materially nonlinear analyses, GMNA for perfect structural elements and GMNIA for imperfect ones, preceded by LBA for the initial curvature evaluation of imperfect member configuration prior to loading were carried out. Numerical modelling and simulations were conducted with use of ABAQUS/Standard program. FEM results are compared with those obtained using the Eurocode’s interaction criteria of Method 1 and 2. Concluding remarks with regard to a necessity of equivalent imperfection profiles inclusion in modelling of the in-plane resistance of compression members are presented.

Evaluation of the lateral-torsional buckling resistance of bisymmetrical I-section beams using finite element method was widely discussed in the paper. Numerous FEM simulations with regard to the stability behavior of steel structural elements subjected to bending about the major principal axis were performed. The use of different finite element modeling techniques and their influence on obtained results were presented by the authors. The ultimate state of both perfect and imperfect elements was assessed. Considerations were concerned with hot-rolled wide flange HEB and narrow flange IPE section beams. Idealization of boundary conditions of FEM models complies with the assumptions used in the analytical formulation of stability problems of thin-walled beams. Geometrically and materially nonlinear analyses GMNA and GMNIA preceded by LBA analyses were carried out. Numerical simulations were conducted with use of ABAQUS/ Standard program.

Stan graniczny nośności konstrukcji, projektowanej w tradycyjnym podejściu na podstawie efektów oddziaływań jest oceniany z niezawodnościowego modelu szeregowego. Kalibrację współczynników częściowych do nośności przeprowadza się wówczas na podstawie analizy niezawodności pojedynczego elementu konstrukcji (pręta lub węzła). Eurokod stalowy [4] wprowadził zasady projektowania bazujące na bardziej złożonych modelach nośności niż w [8], gdyż stan graniczny można ocenić na podstawie warunku stateczności technicznej podukładu konstrukcji lub w ogólności, jak przedstawia to warunek (2.1) - na podstawie punktu granicznego na ścieżce równowagi wyznaczonej dla nieidealnego modelu całej konstrukcji. Pojawia się pytanie, czy stosowanie do nośności wyznaczonej na podstawie bardziej złożonych modeli mechaniki konstrukcji współczynników częściowych wyspecyfikowanych do oceny nośności pojedynczych elementów prowadzi do bezpiecznych oszacowań. Kalibracja współczynników częściowych w metodzie stanów granicznych może być dokonana przy różnych założeniach wyjściowych. Model niezawodności i ogólne zasady przyjętego w eurokodach rozdziału docelowego wskaźnika niezawodności na składowe odnoszące się do ustalenia obliczeniowych oddziaływań i ich kombinacji oraz do ustalania nośności obliczeniowej zostały podane w eurokodzie [1]. W artykule przedstawiono zagadnienia dotyczące przyjęcia współczynników częściowych do nośności układu lub podukładu konstrukcyjnego. Opisano eurokodową procedurę wykorzystującą wyniki badań doświadczalnych do kalibracji współczynników częściowych do nośności.

Measurement of physical properties of porous geological materials is a crucial issue in oil and gas recovery industry. A conventional experimental way to obtain information on porosity, pore size distribution, specific surface area and permeability are the intrusion porosimetry and permeameter measurement. However, in this approach Washburn's equation is usually used, thus approximation of cylindrical pore shapes is made. However, in recent times the computed microtomography (CMT) technique is more widely used in geoscience ( Appoloni et al., 2007 ). We have already reported preliminary results of investigation of elemental content, microporosity, and specific surface area of porous rocks by means of the CMT technique based on a laboratory source ( Bielecki et al., 2012 ). In this paper, results of complex study of porous rock samples with the use of X-ray CMT (laboratory-source-based facility and synchrotron radiation source) combined with permeability tensor computation by means of the Lattice Boltzmann Method (LBM) are presented. Moreover, the proton induced X-ray emission (PIXE) method was additionally used for elemental content determination of pores-filling substance.

Different aspects of Eurocode 3 General Method (GM) approaches are discussed in this paper. The purpose of present study is to improve the application of GM approach for both beam-columns without intermediate lateral-torsional restraints and with these restraints. The results from the proposed GM are compared with those from Eurocode 3-1-1 interaction equations according to Method 1 and Method 2. A better consistency between the developed GM approach and the Eurocode's interaction equation approach than Eurocode 3 GM approach is observed.

Sharp resonant structures in the cross section of the atomic electron-ion collision process of dielectronic recombination are exploited to study isotope shifts and hyperfine interaction of heavy highly-charged ions. This novel approach provides a conceptual alternative to existing methods. In this contribution, we present a series of measurements, which we performed at the heavy ion storage ring ESR of the GSI Helmholtzzentrum fur Schwerionenforschung, Darmstadt, Germany. In a first experiment the stable isotopes A = 142 and A = 150 of three-electron neodymium ANd57 + were studied. Isotope shifts of dielectronic resonances associated with 2s − 2pj (j = 1/2, 3/2) transitions were extracted from the measured data. The evaluation of the energy shift was performed within a full QED framework and yielded a change in the mean-square charge radius of \(^{142,150}\delta \langle r^2 \rangle = -1.36(1)(3)\) fm2. At GSI, in addition to the investigation of stable isotopes unstable species can be artificially synthesized and studied. Radioisotopes produced in-flight from fragmentation of a 238U primary beam were injected into the ESR and were subsequently separated by their mass-to-charge ratio. This enabled us to perform first DR experiments with the exotic nuclei 237U89 + (Z = 92 )and 234Pa88 + (Z = 91).

A new, multi-purpose X-ray microprobe has been constructed in Krakow. The Hamamatsu L9191 microfocusing X-ray tube is used as a source of radiation. The microprobe is equipped with three dedicated experimental lines serving for the computed microtomography (CMT), for micro-XRF or TXRF measurements (micro-X-ray induced Fluorescence, Total reflexion XRF) and for mammalian cell irradiations. Details of the construction of the experimental line dedicated to irradiations are presented.

The effect of different radiation qualities on (i) 53BP1 (p53 Binding Protein 1) and p-ATM (phosphorylated ataxia telangiectasia mutated) foci induction, and (ii) on the kinetics of foci disappearance was analysed.Normal human skin fibroblasts were exposed to 240 kV broad-field X-rays or targeted with individually counted helium ((3)He) particles or protons ((1)H) from a Charged Particle Microbeam. Anti-p-ATM and anti-53BP1 antibodies were used for foci visualisation via immunocytochemistry.1 Gy of X-rays yielded approximately 33 53BP1-positive foci/cell. The ratio between the number of delivered particles and yielded tracks was found to be 1:1 and 3:1 after targeted (3)He and (1)H irradiation, respectively. It was determined that approximately 50% of radiation-induced damage was repaired as measured by loss of foci during the first 2, 6, and 10 hours following X-ray, protons, and (3)He irradiation, respectively.There was significant radiation quality dependence for 53BP1- and p-ATM-positive foci induction observed. Foci disappearance was radiation dose-independent in the samples irradiated with X-rays. Our results confirm that kinetics of foci disappearance depends on radiation quality, even when individual ions are targeted to cells.

Przedstawiono zagadnienie sprężystej utraty płaskiej postaci zginania stalowych belek o przekrojach dwuteowych bisymetrycznych, które są poddane jednokierunkowemu zginaniu względem osi większej bezwładności. Zaproponowano alternatywny w stosunku do konwencjonalnego sposób wyznaczenia wartości sprężystego momentu krytycznego zwichrzenia, przy dowolnym rozkładzie momentu zginającego wzdłuż osi pręta, bazujący na interakcji symetrycznej i antysymetrycznej postaci zwichrzenia. Zaproponowane podejście analityczne porównano z wynikami analiz numerycznych MES, na przykładzie swobodnie podpartej belki zginanej dwoma momentami podporowymi o różnym znaku i wartości oraz siłą skupioną w połowie rozpiętości belki.

The use of targeted ion beams has been an important development for understanding the response of biological systems to radiation exposure. Most investigations in this field have been performed with helium ion microbeams; however, irradiations using a beam of protons, covering different LET values, can deliver complementary results and additional information on radiation effect related to radiation quality and low dose exposure. Recently, several experiments have been carried out at the new single ion hit facility in the Institute of Nuclear Physics in Cracow using a focused proton microbeam. In parallel, similar cross-validation experiments have been performed using the well-established particle microbeam situated at the Gray Cancer Institute with the same cell line and proton energy. Pilot studies have compared the yields of double strand breaks (DSBs) in cells uniformly irradiated with 240 kV X-ray with those irradiated with microbeam delivered protons, and in some cases helium ions. The number of DSBs increased with the X-ray dose. In the samples irradiated with individually counted protons, fewer foci were found in comparison to the number of protons delivered per cell. Studies also compared the distribution of foci per cell between the different radiation qualities.

Nanocrystalline titanium dioxide (nanoTiO2) has been reported to generate reactive oxygen species (ROS) under UV illumination. In our studies, changes in mechanical properties of human skin fibroblasts, exposed to the oxidative stress induced in the presence of nanoTiO2 and UV light, were studied using atomic force microscopy (AFM). The exposure of cells to the action of ROS was performed at low TiO2 concentration (4 microg/mL) and under illumination with low-intensity UVA (8 and 20 mW/cm2) or UVC (0.1 mW/ cm2). AFM measurements of the cell stiffness were carried out immediately after exposure of cells to the oxidative stress. The data suggest that under illumination with low-intensity UVA nanoTiO2 generates ROS, which, in turn, damage cellular and subcellular structures. This process was detected by AFM as a marked drop in the cellular stiffness of ca. 30-75%, which occurred rapidly, in the time frame of 1 min. The photo-oxidative stress inducing the decrease of cell stiffness was cancelled in the presence of a well-established antioxidant, beta-carotene. The results highlight the sensitivity of AFM to detect early changes in mechanical properties of cells exposed to oxidative stress.

Be-like ions have been investigated employing the resonant electron–ion collision process of dielectronic recombination (DR) as a spectroscopic tool. The experiments were performed at the experimental storage ring in Darmstadt, Germany, using its electron cooler as a target for free electrons. DR Rydberg resonance series for the associated intra-L-shell transitions and were observed with high resolution. In addition to these excitations from the ground state we determined resonances associated with excitations of ions initially in the metastable state. The corresponding excitation energies were determined to be and and . These excitation energies are compared with previous measurements and with recent state-of-the-art atomic structure calculations.

In recent years, a single ion hit facility has been constructed at the IFJ ion microprobe. The setup is used for the precise irradiations of living cells by a controlled number of ions. Investigations of such type have two very important requirements: (1) cells must be examined in their natural state and environment (i.e. without previously being killed, preferentially neither fixed nor stained) and (2) the possibility of automatic irradiation of large number of cells (including computer recognition of cells positions) must be provided. This work presents some of the crucial features of the off-line and on-line optical systems, including self-developed software responsible for automatic cell recognition.

Superheavy quasimolecules are formed transiently during heavy-ion heavy-atom collisions at moderate collision velocities. Using highly charged projectiles, couplings in the inner-most shells of the quasimolecule can be probed. The present investigation of 69 MeV u −1 Bi q + -ions ( q =77, 81 and 82) on thin Au targets was aimed to determine the role of prior-to-collision inner shell vacancy in a superheavy quasiadiabatic collision. The possibility of using very thin solid targets for probing such collisions was investigated and the interaction distances for the inner-shell couplings were calculated.

In this report we show first results on dielectronic recombination (DR) measurements with H-like uranium U 91 + . The experiments were conducted at the heavy ion storage ring ESR of GSI. The electron cooler of the ESR was used as a target for free electrons. Stochastic pre-cooling of the stored ion beam was employed in order to accomplish high-energy resolution at the necessary high electron–ion collision energies of more than 64 keV. For the DR of U 91 + this novel technique enabled us to measure for the first time the KLL-DR process and even to resolve the individual j – j ′ fine structure components of the KL j L j ′ resonances. The experimental data are compared with fully relativistic Multi-Configuration Dirac-Fock (DR-MCDF) calculations.

The Cracow single ion hit facility (SIH) is using the Van de Graaff-based microprobe with current spatial resolution of about 10 μm in vacuum. Living cells are irradiated with the exact number of 2 MeV protons. This work shows the present setup and test measurements optimizing the detection of single protons, beam deflection after registering single proton and the accuracy of cell targeting as well as the description of performance of the whole setup. The article presents also ways of cells visualisation and positioning during a single measurement and reports on first experiments with living cells carried out at the new facility.

With the advanced accelerator technologies used at the SIS/ESR heavy ion facility at GSI, the highest charge states (bare, H-like, etc.) even for the heaviest ions can be provided for experiments at moderate collision velocities (vion

This work presents the final development stage and optimization results of the single proton hit facility in Cracow. The setup parameters: proton beam energy 2 MeV, hit resolution 30 μm, intensity ≈ 1000 proton/s, proton registration efficiency 100%, blanking efficiency 99.8%. On-line observation allows targeting cells inside a Petri dish mounted at a 3D precise moving stage. To target a particular cell a semiautomatic cell visualization and recognition system is used.

The X-ray spectra produced by K-shell ionization in collisions of Li-like (U89+) uranium ions at an energy of 397 MeV/u with gaseous N2 target have been measured. The very high level selectivity during such collision has been found. The effect allows us to measure undistorted two-photon energy distribution from a decay of the 1s2s1S0 state in He-like uranium.

The angular distributions of L-REC photons generated in collisions of 216 MeV/u U91+-, U90+- and U89+-ions with N2 – target were measured. X-ray spectra, registered for different observation angles, were used in order to separate, for the first time, the L-REC angular distribution for the 2s1/2 subshell. Experimental data are very well reproduced by relativistic theoretical predictions.

Charge exchange and X-ray emission for 70 MeV/u highly charged ions of Bi q + [77 ⩽ q ⩽ 82] colliding with thin Au targets [21 ⩽ t in μg/cm 2 ⩽ 225] were measured at the heavy ion synchrotron SIS at GSI. For the innermost shells this beam energy implies a quasiadiabatic collision regime. The charge state distribution of the emerging ions was measured by a position sensitive CVD-diamond detector after being analyzed by a magnet spectrometer. Charge exchange cross sections have been deduced from the target thickness dependence of the charge state distribution. Electron capture at distant collision dominates completely over ionization at close collision. The X-ray emission from the collision partners were measured by solid state detectors, Ge(i). The K X-ray emission for closed and open incoming projectile K vacancies gives access to vacancy transfer in the superheavy quasi-molecule transiently formed during collision for the innermost shells.

The lifetime of the 2 3P0 state in He-like uranium has been measured in a beam-foil time-of-flight experiment at the Gesellschaft fur Schwerionenforschung accelerator facility with the result τ(2 3P0) = 58.2(9.5) ps. With the measured lifetime it is possible to derive a value of Δ E 2 s Lamb = 76 . 3 ± 20 . 6 eV for the n = 2 Lamb shift in uranium.

Single ion bombardment of biological cells using an ion microprobe is a promising technique. However, for microprobe investigations of biological processes at a cellular level the precise recognition of a single cell and particularly of its nucleus is required. Moreover, cells must be examined in their natural state and environment (i.e. without previously being killed, preferentially not fixed nor stained) and, also, the use of ultraviolet light for cells observation should be avoided. Additionally, in order to obtain statistically significant results of irradiation, the possibility of fast automatic recognition of thousands of objects must be provided. Because computer recognition strongly depends on the quality of an image, the optical imaging system is of crucial importance. For this purpose one of the best solutions could be the Quantitative Phase microscopy (QPm) technique. QPm is the recent digital technique of phase contrast microscopy, providing quantitative phase and intensity data obtained from a series of defocused images. The following phase contrast modalities may be generated digitally from the computed QPm phase data with a greater degree of flexibility: Pure phase images (intensity-free), standard phase contrast (e.g. Zernike phase contrast), differential interference contrast (DIC), Hoffman modulation contrast, and simulated darkfield.

The Cracow microprobe was applied to determine the age of small detritalmonazite crystals extracted from the uppermost carboniferous sandstone of Upper Silesia Coal Basin (southern Poland). The method applied follows the technique of chemical dating of U–Th minerals: assuming that the monazite crystal is a closed system and all Pb within grain is radiogenic, it is possible to determine the age of a specimen by solving an equilibrium equation which includes as computational factors the elemental contents of U, Th and Pb and decay times of uranium and thorium. Using this approach, thanks to rather fast Pb accumulation in a crystal, monazite older than 100 My may be dated with relative ease. The investigated specimens were clusters of crystals, 30–100 μm in size, polished and mounted in Epoxy resin. Due to different geological history, the age of individual crystals from one sample may differ significantly, therefore the application of a microprobe has been necessary to extract information concerning single monazite grains. Two age groups were identified: small cluster, connected with Cadomian tectonothermal event (579±30 My) and dominating cluster, connected with Variscan tectonothermal event (329±19 My, 353±41 My). After successful preliminary measurements carried out in a provisory experimental chamber, an optimized chamber was constructed and set into operation for regular studies. Together with results of these investigations, the constructional details of the new chamber are presented.

Total cross-sections for radiative single- and double-electron capture are measured in collisions of fast highly charged ions with light target atoms. Cross-sections for non-correlated double capture are in accordance with theoretical predictions. No significant line structure at twice the single K-radiative electron capture (K-REC) photon energy was observed. Angular distributions single K-REC photons associated with single- and double-charge exchange exhibit the same pattern. The corresponding REC lines are almost by a factor of two broader for double-charge exchange than in the single capture case.

We studied the angular distribution of the X-ray emission associated with KLL-RTE for H-like U91+ ions colliding with quasi-free electrons from an H2 target. In this resonant transfer and excitation process an intermediate doubly excited He-like U90+** with two electrons in the L-shell is produced by electron–electron interaction; this exotic state decays by the emission of two photons, a Kα-hypersatellite and a Kα-satellite X-ray. According to the different j values (1/2 and 3/2) for the L-shell electrons three different KLL-RTE resonance groups can be distinguished by the corresponding ion energies. At the three resonance energies and one off-resonance energy (116.6, 124.9, 133.1 and 102.0 MeV/u, respectively) X-ray spectra were taken simultaneously at seven different observation angles. The Kα2 satellite lines (j=1/2–j=1/2 transitions) are isotropic, whereas the Kα1 hypersatellite lines (3/2–1/2 transitions) for the second resonance display a pronounced anisotropy pointing to a strong alignment of the involved doubly excited states. Our data agree with full relativistic theory in its general features.

Here we report on X-ray spectra induced by spontaneous capture of free electrons into decelerated bare- and hydrogen-like uranium ions which we measured recently at the cooler section of the ESR storage ring. The most intense lines observed in spectra can be attributed to direct transition of electrons into the K shell of the projectile ions and to characteristic L → K (Lyα) transitions. Radiative recombination lines into the K shell of bare and H-like uranium can be exploited for measuring the two-electron contribution to the ground state binding energy in helium-like uranium. The goal is to probe for high-Z ions bound-state QED corrections which are of the order of α2. Besides the dominant characteristic L → K transitions, the strongly reduced Bremsstrahlung (due to the low cooler voltage applied to the decelerated ions) allowed us to observe for the very first time RR transitions into the L shell as well as the balmer radiation located at the low-energy part of the spectra.

The KαL1 satellite spectrum of 29Cu was measured with a 5 inch Johansson crystal spectrometer after 2 MeV proton impact. The satellite spectrum was simulated by using Voigt profiles with a Lorentzian width which is obtained from the multiconfiguration Dirac–Fock (MCDF) calculations and convoluted with the Gaussian instrumental response function. A unique assignment of the strongest satellite transitions to visible structures in the experimental spectrum was based on a comparison of the predicted linear polarization of the transitions (using in calculations the intermediate coupling scheme) to their measured values. The simulated spectrum of the satellite transitions was fitted to the experiment. The fitted values of energies and relative intensities of the transitions are close to those obtained from the MCDF calculations. The alignment of the (1s2p)−2 double-vacancy state obtained from the measured polarization of the satellite spectrum is given by 20(1P 1) = −0.77(21) and 20 (3P) = −0.53(10) (values are not corrected for the Coster–Kronig transition). This is in agreement with the value reported for the KαL1 peak of Al.

An experimental study for K-shell excitation of helium-like uranium in relativistic collisions with low-Z gaseous target is presented. Within this experiment information about the population of the magnetic sublevels has been obtained via a photon angular differential study of the decay photons associated with the excitation process. The preliminary results presented show, for the particular case of the 3 P 1 level, a surprisingly strong population of the magnetic sublevels with μ = ±1.