[en] Published in summary form only

[en] The Xe 5s,5p photoelectron satellite spectrum has been studied in the photon-energy range from 28 to 75 eV with the aid of synchrotron radiation. This range includes the Xe 5s Cooper minimum, and the cross sections and angular distribution data demonstrate the importance of the strong two-electron channels in the region where the 5s cross section is small. Although the behavior of the satellites was not recorded over the 4d maximum, the data near 75 eV show an enhancement in the cross section in that region. The data underline the need of including the two-electron channels explicitly in the theory over a wide photon-energy range

No abstract available

[en] Partial cross sections sigma and angular distribution parameters β were measured for the 5d subshell of atomic lead between 25 and 110 eV, and for the major components of the 6s and 6p subshells between 25 and 55 eV. Data are compared with Dirac-Slater (DS) calculations. Good agreement is found for the β values of both the 5d and 6p subshells. However, as characteristic for single-particle models, the 5d delayed cross-section maximum is seen to be too high. The theoretical DS cross section sigma(6p/sub 1/2/) follows our data satisfactorily, but the DS sigma(6s) and the DS β(6s) do not. Earlier experimental data for Pb are in satisfactory agreement with the present 5d and 6p data. A comparison of our Pb data with experimental data for Hg and relativistic random-phase approximation results for the 5d and 6s subshells of Hg shows a generally satisfactory accord

[en] An ionizing detector for on-line registration and representation of the geometric SR beam parameters was developed in RRC KI. The detector analyses the products of the residual gas ionization, which was done by the investigated beam. Special electrostatic optics and open image converter tube (ICT) form optical image of the real beam on the screen of ICT. The detector was checked on SR beams of the next storage rings: DCI (LURE, Orsey, France), KSRS (RRC KI, Moscow, Russia) and MAX-2 (MAX-lab, Lund, Sweden). The codes for TV image processing give a possibility for numeric estimation of the beam size, the width of its horizontal and vertical profiles and position of the beam gravity. Statistic processing of the beam gravity center using big amount of TV frames gives uncertainty in the beam position of about 2 μm while the width of the beam is about 2 mm. Summation of big amount of TV frames was used. This method significantly increases signal-to-noise ratio

[en] We have performed an experimental study of the electron transfer processes in Li⁺-Na(3s) collisions leading to Li(2s) and Li(2p), using ⁶Li⁺ beam at a collision energy of 1 keV. Neutral particles scattered in a narrow forward cone were detected in coincidence with polarization-analysed photons emitted from the Li(2p) state. This technique enabled determination of the complete Li(2p) transition matrix as a function of scattering angle, which is typically a fraction of a degree. The experimental results for the complete set of differential cross sections and coherence parameters are in excellent agreement with the predictions of recent molecular basis coupled-channel calculations of Machholm and Courbin. (author)

[en] Purpose: To evaluate and compare the diagnostic accuracy of duplex ultrasound (US) and MR angiography (MRA) at 1.0 T in aorto-iliac arterial disease using digital subtraction angiography (DSA) as the reference standard. In addition, a comparison of the 2D time-of-flight (TOF) and 3D contrast-enhanced MRA (CE MRA) techniques was performed. Material and methods: Prospectively, 39 patients with symptoms of lower-extremity arterial occlusive disease were examined using US, TOF MRA, CE MRA and DSA. Significant lesions (stenosis > or = 50%) and occlusions were evaluated blindly for each method. Results: For all segments, the sensitivity for US, TOF MRA and CE MRA with regard to significant lesions was 0.72, 0.81 and 0.81, respectively, and the specificity for each was 0.97, 0.91 and 0.92, respectively. For significant lesions above the inguinal ligament the corresponding sensitivity was 0.84, 0.89 and 0.94 and the specificity 0.93, 0.82 and 0.73, respectively. The specificity was higher when the two MRA methods were combined. TOF MRA overgraded 7 segments as occluded. In most cases, the length of the occlusions was correctly determined on CE MRA, overestimated on TOF MRA and uncertain on US. Conclusion: Neither US nor MRA were sufficiently accurate to fully replace angiography. MRA was preferable to US as a non-invasive test when vascular intervention was contemplated. Although CE MRA was superior to TOF MRA, the most accurate results were achieved when the two methods were combined

[en] Autoionization resonances of the type (n-1) d->np, where n pertains to the outermost shell of Ga, In and Pb, were studied with the use of electron spectrometry in combination with synchrotron radiation. The relative strengths of the exit channels for the various resonance states were measured. In the case of Ga and In, a complete partitioning of the total absorption cross section into the s²¹S, sp ¹P, and sp ³P components (exit channels) was achieved, and in the case of Pb the decay of the resonance states into the major exit channels 6s²6p ²Psub(1/2), 6s²6p ²Psub(3/2), 6s6p²⁴Psub(1/2)3, 6s6p²³Dsub(3/2) and 6s6p²²Psub(1/2) was determined. In Ga, strong coupling was observed for those states of the 4p² manifold that have the same symmetries as the final ionic states, e.g. 4p²³P proportional 4s4p ³P and 4p²¹Sproportional4s²¹S. In In, there is a similar, but weaker correlation, which also includes two-electron excitation channels. Comparison between Ga and In shows that the sp ³P channel is much stronger in In (52% vs 40% in Ga) while the sp ¹P channel is correspondingly weaker (28% vs 37%), with the s²¹S channel remaining practically unchanged (20 vs 23%). In Pb, the 6s²6p ²Psub(1/2) channel displays interference patterns due to strong, competing direct transition, whereas the other channels do not, indicating population predominantly via the resonance states. (orig.)

[en] The spin polarisation components of photoelectrons from atomic ytterbium have been measured over the photon energy range from 15.5 to 22.5 eV. The measurements were performed by making use of circularly polarised synchrotron radiation from the storage ring BESSY in conjunction with an angle-resolved electron spectrometer. Theoretical predictions based on the relativistic random-phase approximation are in fair agreement with the experimental data even though a certain offset between theory and experiment exists. (author)

[en] Full text: A number of biological processes, for instance muscular contraction and intracellular transport, are based on a fascinating physical principle: In periodic, asymmetric potentials, so-called ratchets, the random motion of Brownian particles can be put to use by extracting energy from nonequilibrium fluctuations. These findings have recently revived interest in physics to explore the general principles of ratchet effects. So far, most ratchet systems studied assumed or used classical systems. In extension of this previous work, highly interesting and new physics can also be expected from ratchet mechanisms that rely on quantum processes. In this contribution, the requirements for experimental studies of quantum ratchet effects will be discussed, and it will be pointed out that these prerequisites are ideally fulfilled in semiconductor- and metal-nanostructures. As an example, experimental and theoretical results will be presented showing that phase-coherent, asymmetric (triangular) electron cavities can partially rectify an applied AC voltage. Using this effect, which is related to electron wave interference, an electron current can be generated without applied net field