Bericht über praktische Anwendungen autoradiographischer Verfahren im Institut für angewandte Radioaktivität Leipzig: Zusammenfassender Bericht

In der Arbeit wird untersucht, unter welchen analytischen Bedingungen eine quantitative Sticksoffbestimmung mit dem ¹⁵ N-Analysator NA-5A mittels Isotopenverdünnung durchzuführen ist. Es wird auf die Berechnung der N-Menge, die Abschätzung des maximalen Fehlers unter den speziellen Verhāltnissen der ¹⁵N-Analysator-Anwendung und die Auswertungsverfahren näher eingegangen. Testanalysen an unterschiedlich markierten Modell-Lösungen, bestehendaus Ammonium-, Harnstoff- und Aminosäurestickstoff, ergaben gute Übereinstimmung mit den vorgegebenen Werten. Das Verfahren wurde zur N-Bestimmung von biologish-medizinischem Material eingesetzt. Ein Arbeitsschema zur quantitativan Bestimmung von Ammonium-N, Harnstoff-N und Gesamt-N direkt in Harn wird mitgeteilt.     

Muon diffusion in nanocrystalline copper

A systematic μSR study on nano‐Cu has demonstrated that the diffusion of μ⁺ in nanocrystalline metals is influenced by both features of the nanostructure, i.e., by the very small grain size and by the comparatively large fraction of grain boundaries. The former feature yields a size effect of the phonon‐assisted muon tunneling, but only at particle diameters below 20 nm. The latter feature, in samples with crystallite sizes above 20 nm diameter, i.e., with bulk diffusional behaviour, establishes a connection between μ⁺ diffusion coefficient and particle size: if one of these quantities is known, the other could be evaluated. This revised version was published online in August 2006 with corrections to the Cover Date.     

An experiment for the measurement of the bound- β-decay of the free neutron

The hyperfine-state population of hydrogen after the bound-β-decay of the neutron directly yields the neutrino left-handedness or a possible right-handed admixture and possible small scalar and tensor contributions to the weak force. Using the through-going beam tube of a high-flux reactor, a background free hydrogen rate of ca. 3s^-1 can be obtained. The detection of the neutral hydrogen atoms and the analysis of the hyperfine states is accomplished by Lamb shift source type quenching and subsequent ionization. The constraints on the neutrino helicity and the scalar and tensor coupling constants of the weak interaction can be improved by a factor of ten.     

Measurement of the spectral flux density of negative muons at very low energies

The spectral flux density of negative muons has been measured down to 5 eV.     

Spectroscopy of two coincident charged particles emitted following bound pion absorption in 12C, 59Co and 197Au

Energy spectra and angular distributions of two coincident charged particles emitted following stopped negative pion absorption in ¹²C, ⁵⁹Co and ¹⁹⁷Au were measured. Most of the data can be understood within the framework of a pair absorption model including final-state interactions. Ground-state transitions in the missing mass spectra of ⁴H and ⁴He deduced from the αα and tα spectra of ¹²C, respectively, show that reactions involving a large part of the nucleus also occur.     

Anomalous large angle alpha scattering

Forα-nucleus potentials which contain a pocket, the scattering matrix may be split into ‘barrier’ and ‘internal’ components. Using simple parametrizations for these components, analytic expressions are derived for the corresponding ‘barrier’ and ‘internal’ cross sections. The oscillations present in these cross sections are interpreted as arising from interference between various terms in the Poisson summation formula for the scattering amplitudes. At backward angles the ‘internal’ cross section and the cross sections resulting from various Regge pole models are shown to have the same angular dependence. A method is given to locate roughly the position of the dominant Regge pole of the scattering matrix. At more foreward angles the ‘internal’ cross section, unlike those from the Regge pole models, describes the nuclear refraction undergone byα-particles that are transmitted through the target. Such refraction effects have previously been invoked to explain intermediate energyα-nucleus scattering.     

Synthesis of distillation trains with heat integration by a combined fuzzy and graphical approach

After passing some results of fuzzy synthesis of heat exchanger networks in review the application of this approach to the synthesis of distillation trains for the separation of multicomponent mixtures is demonstrated. The available heuristic rules are transformed into fuzzy implications dependent on different criteria and that competing rule, which is to be applied, is selected by the fuzzy algorithm.The theoretically possible amount of heat recovery within the networks generated in this way is estimated by a graphical method and included in the final cost evaluation. Regarding operating parameters like column pressure and reflux ratio, according to the mathematical effort at least qualitative statements can be made in result of the estimation of possible heat recovery.As already in the case of heat exchanger networks a following learning algorithm can serve to overcome the disadvantages of this sequential approach, representing at the same time the first step of a further evolutionary improvement of the initial distillation train.