Automated one-loop calculations with GoSam

We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the?loop.     

A HF Loaded Lewis-Acidic Aluminium Chlorofluoride for Hydrofluorination Reactions

The very strong Lewis acid aluminium chlorofluoride (ACF) was loaded with anhydrous HF. The interaction between the surface of the catalyst and HF was investigated using a variety of characterization methods, which revealed the formation of polyfluorides. Moreover, the reactivity of the HF-loaded ACF towards the hydrofluorination of alkynes was studied.     

The compton spectrometer

This is the story about how knowledge of the Compton profile led to the technical development of a useful apparatus. It is also the story of interdisciplinary collaboration between condensed matter theorists and medical physicists.     

Reactive-ion-etch damage in GaAs processing evaluated by a microwave absorption technique

Through determination of magnetic field-dependent resistivity by electric microwave absorption (EMA), both mobility and carrier concentration of conducting layers in a semiconducting substrate may be evaluated. We have employed this method to study the extent of electric damage produced during standard GaAs plasma processing; various typical heterostructures were subjected to realistic reactive ion etch treatments and the changes in transport properties were examined by EMA. It was seen that predominantly chemical etch processes result in little substrate damage, whereas physical milling produces considerable degradation. Oxynitride etching was noted to be benign only at low voltages, whereas photoresist stripping was not seen to produce any measurable substrate damage.     

Relatively Bounded Rank One Perturbations of Non-Analytic Semigroups Can Generate Large Point Spectrum

It is known that relatively bounded compact perturbations of analytic semigroups yield again generators of analytic semigroups. On the other hand, for each non-analytic semigroup there is a relatively bounded rank one perturbation which is no longer a generator. In this note we show that in fact any non-analytic semigroup admits a relatively bounded rank one perturbation with a sequence of eigenvalues z_j such that the real parts R(z_j) converge to infinity.     

The photoelectric aerosol sensor as a fast-responding and sensitive detection system for cigarette smoke analysis

Summary The combination of the photoelectric aerosol sensor (PAS) and the time programmed sampling of small aerosol volumes within a cigarette puff allows the quantitative time-resolved determination of photoemitting substances in the aerosol. All photoemitting substances contribute to the measured photoelectric (PE) signal. In this comparative study it is shown that the PAS signal correlates well (r=0.94, n=20) with the BaP content. The benzo-a-pyrene (BaP) amounts of the cigarette smoke aerosol were separately determined by in situ synchronous fluorimetry on TLC plates. The absolute detection limit is about 50 pg.

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Photoelektrischer Aerosolsensor als schnell ansprechendes und empfindliches Detektionssystem zur Analyse von Zigarettenrauch

     

Speciation of nitrogen - [N(3-)] and [N(2)(2-)] - in binary compounds

The nitrogen content of the binary compounds SrN = Sr(4)[N](2)[N(2)], Sr[N(2)], and Ba[N(2)] (prepared by high-pressure syntheses) was determined analytically by using the carrier gas hot extraction method. For handling of the air- and moisture-sensitive samples, a transfer chamber was constructed to protect the compounds against decomposition before being analyzed. Additionally, it was necessary to develop a method allowing controlled and variable heating of the electrode furnace to get analytical results with high precision and accuracy. By means of a suitable temperature program it was possible not only to verify the existence but also to quantify the two different nitrogen species ([N(3-)] and [N(2)(2-)]), and thus confirm the results of recent neutron diffraction studies.     

Analytical Study of Extracts of St John’s Wort (Hypericum perforatum), Evaluation of HPTLC Plates by Multivariate Data Analysis

JPC – Journal of Planar Chromatography – Modern TLC - HPTLC with multivariate data analysis has been used as a new means of evaluating the quality of herbal extracts. Spectral data from...