The photoproduction of \(\omega\) mesons on LH_2, C and Nb has been studied for incident photon energies from 900 to 1300 MeV using the CB/TAPS detector at ELSA. The \(\omega\) line shape does not ...show any significant difference between the LH_2 and the Nb targets. The data are compared with results of transport calculations that predict a sensitivity of the \(\omega\) line shape to in-medium modifications near the production threshold on a free nucleon of \(E_{\gamma}^{lab}\) = 1109 MeV.}
The model of binding alpha-particles in nuclei is suggested. It is shown good
(with the accuracy of 1-2%) description of the experimental binding energies in
light and medium nuclear systems. Our ...preliminary calculations show enhancement
of the binding energy for super heavy nuclei with Z~120.
Quasi-free photoproduction of \(\eta '\) mesons off nucleons bound in the deuteron has been measured with the combined Crystal Barrel - TAPS detector. The experiment was done at a tagged photon beam ...of the ELSA electron accelerator in Bonn for incident photon energies from the production threshold up to 2.5 GeV. The \(\eta '\)-mesons have been detected in coincidence with recoil protons and recoil neutrons. The quasi-free proton data are in good agreement with the results for free protons, indicating that nuclear effects have no significant impact. The coincidence with recoil neutrons provides the first data for the \(\gamma n \rightarrow n\eta '\) reaction. In addition, also first estimates for coherent \(\eta '\)-production off the deuteron have been obtained. In agreement with model predictions, the total cross section for this channel is found to be very small, at most at the level of a few nb. The data are compared to model calculations taking into account contributions from nucleon resonances and \(t\)-channel exchanges.
Data on the photoproduction of \(\omega\) mesons on nuclei have been re-analyzed in a search for in-medium modifications. The data were taken with the Crystal Barrel(CB)/TAPS detector system at the ...ELSA accelerator facility in Bonn. First results from the analysis of the data set were published by D. Trnka et al. in Phys. Rev. Lett 94 (2005) 192303 \cite{david}, claiming a lowering of the \(\omega\) mass in the nuclear medium by 14\(%\) at normal nuclear matter density. The extracted \(\omega\) line shape was found to be sensitive to the background subtraction. For this reason a re-analysis of the same data set has been initiated and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the re-analysis and of the background determination are described. The \(\omega\) signal on the \(Nb\) target, extracted in the re-analysis, does not show a deviation from the corresponding line shape on a \(LH_2\) target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the \(\omega\) line shape to different in-medium modification scenarios is discussed.
Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector for photon energies between 0.92 and 1.68~GeV at the electron accelerator ELSA. The beam asymmetry~\(\Sigma\) has been ...extracted for \(115^\circ < \theta_{\rm c.m.} < 155^\circ\) of the \(\pi^0\)~meson and for \(\theta_{\rm c.m.} < 60^\circ\). The new beam asymmetry data improve the world database for photon energies above 1.5~GeV and, by covering the very forward region, extend previously published data for the same reaction by our collaboration. The angular dependence of \(\Sigma\) shows overall good agreement with the SAID parameterization.
Int.J.Mod.Phys. E15 (2006) 673-684 Stability with respect to neutron emission is studied for highly
neutron-excessive Oxygen isotopes in the framework of Hartree-Fock-Bogoliubov
approach with Skyrme ...forces Sly4 and Ska. Our calculations show increase of
stability around 40O.
Total and differential cross sections for \(\eta\) and \(\eta ^\prime\) photoproduction off the proton have been determined with the CBELSA/TAPS detector for photon energies between 0.85 and 2.55 ...GeV. The \(\eta\) mesons are detected in their two neutral decay modes, \(\eta\to\gamma\gamma\) and \(\eta\to 3\pi^0\to 6\gamma\), and for the first time, cover the full angular range in \(\rm cos \theta_{cm}\) of the \(\eta\) meson. These new \(\eta\) photoproduction data are consistent with the earlier CB-ELSA results. The \(\eta ^\prime\) mesons are observed in their neutral decay to \(\pi^0\pi^0\eta\to 6\gamma\) and also extend the coverage in angular range.
