Surface and volume effects in the photoabsorption of nuclei

Recent experimental results for meson photoproduction from nuclei obtained with TAPS at MAMI are analyzed in view of the suppression of the second nucleon resonance region in total photoabsorption. The cross sections can be split into a component from the low density surface region of nuclei and a component which scales more like the nuclear volume. The energy dependence of the surface component is similar to the deuteron cross section, it shows a clear signal for the second resonance peak assigned to the excitation of the P11(1440), D13(1520), and S11(1535). The volume component behaves differently, it is lacking the second resonance peak and shows an enhancement at intermediate photon energies.Comment: accepted for publication in Eur. J. Phys.

Extraction of the Ratio of the N^*(1535) Electromagnetic Helicity Amplitudes from Eta Photoproduction off Neutrons and Protons

Using the recent precise measurements of eta photopro- duction in proton and deuteron targets, we extract the ratio of the helicity amplitudes A^n_1/2 / A^p_1/2, for the excitation of N^*(1535), in the effective Lagrangian approach, It is fairly model-independent, free from the final-state interaction effects, and negative as predicted by the quark models. We stress the importance of polarization observables in further elucidation of the N^*(1520) photoexcitation amplitudes.Comment: 4 figures. It will be published in Phys. Lett.

The new low frequency accelerating systems for the CERN PS booster

A set of four, ferrite-loaded, low-frequency RF cavities equipped with local RF feedback has been built and installed in the CERN PS Booster rings. Together with the modified existing RF systems they now serve for acceleration as well as RF gymnastics of protons and heavy ions up to the highest beam intensities. The systems specifications with a frequency range of about 0.6 to 1.8 MHz and a nomina l RF peak voltage of 8 kV satisfy specifically the requirements of acceleration on harmonic 1 of the future proton beam for the LHC. The system design has been guided by the request for safety margins for high beam intensity operation and ease of maintenance and repair. Some design aspects are presented as well as the performance achieved

Photoproduction of the Etas near Threshold

We extract a parameter $\xi$, a characteristic product of the strong and electromagnetic amplitudes for the N^*(1535), to be (2.20+-0.15) in unit of 10^(-4)MeV^(-1) from the new data on photoproduction of etas off proton.Comment: will be published in Phys. Rev. Let

Photoproduction of pi0-mesons from nuclei

Photoproduction of neutral pions from nuclei (carbon, calcium, niobium, lead) has been studied for incident photon energies from 200 MeV to 800 MeV with the TAPS detector using the Glasgow photon tagging spectrometer at the Mainz MAMI accelerator. Data were obtained for the inclusive photoproduction of neutral pions and the partial channels of quasifree single pi0, double pi0, and pi0pi+/- photoproduction. They have been analyzed in terms of the in-medium behavior of nucleon resonances and the pion - nucleus interaction. They are compared to earlier measurements from the deuteron and to the predictions of a Boltzmann-Uehling-Uhlenbeck (BUU) transport model for photon induced pion production from nuclei.Comment: 15 pages, 22 figures, accepted for publication in EPJ

Perikarditis im Rahmen rheumatologischer Erkrankungen – Was der Rheumatologe wissen sollte

Pericarditis is the term for inflammatory involvement of the pericardium, which can be associated with pericardial effusion and myocardial involvement (perimyocarditis). Pericarditis can be present in the context of systemic inflammatory rheumatic diseases but can also constitute a distinct disease entity. Idiopathic recurrent pericarditis (IRP) describes relapsing conditions of pericarditis with an unknown cause, which show essential common features with autoinflammatory diseases. This article gives an overview of the frequency of pericarditis in systemic rheumatic diseases. Moreover, the clinical manifestations and pathophysiology of IRP are discussed. Finally, the therapeutic algorithms for acute and idiopathic pericarditis are explained.Als Perikarditis wird eine Entzündung des Herzbeutels bezeichnet, die mit einem Perikarderguss oder einer entzündlichen Reaktion des Myokards (Perimyokarditis) einhergehen kann. Die Perikarditis kann im Rahmen von entzündlich rheumatischen Systemerkrankungen oder als eigenständige Erkrankung vorkommen. Rezidivierende Perikarditisepisoden ohne fassbare Ursache werden als idiopathische rekurrierende Perikarditis (IRP) bezeichnet, welche wesentliche Gemeinsamkeiten mit autoinflammatorischen Erkrankungen aufweist. Der Artikel gibt einen Überblick über die Häufigkeit des Auftretens einer Perikarditis bei rheumatologischen Erkrankungen. Weiterhin werden Klinik und Pathophysiologie der IRP diskutiert. Abschließend wird die Therapie der akuten und idiopathischen Perikarditis erläutert

On the Extraction of Cross Sections for pi0 and eta Photoproduction off Neutrons from Deuteron Data

We discuss the procedure of extracting the photoproduction cross section for neutral pseudoscalar mesons off neutrons from deuteron data. The main statement is that the final-state interaction (FSI) corrections for the proton and neutron target are in general not equal, but for pi0 production there are special cases were they have to be identical and there are large regions in the parameter space of incident photon energy and pion polar angle, \theta^*, where they happen to be quite similar. The corrections for both target nucleons are practically identical for $\pi_0$ production in the energy range of the Delta(1232)3/2+ resonance due to the specific isospin structure of this excitation. Also above the $\Delta$-isobar range large differences between proton and neutron correction factors are only predicted for extreme forward angles ($\theta^*$ < 20 deg), but the results are similar for larger angles. Numerical results for the gp-->pi0p and gn-->pi0n correction factors are discussed. Also the model description for the available data on the differential gd-->pi0pn cross sections are given.Comment: 16 pages, 5 figures; v2 fixed several minor typo

Photoproduction of pions and etas in nuclei

We calculate the cross sections for inclusive one-pion, two-pion and eta photoproduction in nuclei in the photon energy range from 300 MeV to 900 MeV within the framework of a semi-classical BUU transport model. Our results are compared with existing experimental data and discussed with respect to a calculation of the total photoabsorption cross section.Comment: 30 pages LaTeX including 13 postscript figure