K0-Sigma+ Photoproduction with SAPHIR

Preliminary results of the analysis of the reaction p(gamma,K0)Sigma+ are presented. We show the first measurement of the differential cross section and much improved data for the total cross section than previous data. The data are compared with model predictions from different isobar and quark models that give a good description of p(gamma,K+)Lambda and p(gamma,K+)Sigma0 data in the same energy range. Results of ChPT describe the data adequately at threshold while isobar models that include hadronic form factors reproduce the data at intermediate energies.Comment: 4 pages, Latex2e, 4 postscript figures. Talk given at the International Conference on Hypernuclear and Strange Particle Physics (HYP97), Brookhaven National Laboratory, USA, October 13-18, 1997. To be published in Nucl. Phys. A. Revised version due to changes in experimental dat

Aufbau, Test und Eichung des hochaufloesenden Tagging-Systems TOPAS II am Bonner SAPHIR-Detektor

The new high-resolution tagging-system TOPAS II has been installed at the SAPHIR-detector at the ELSA facility at Bonn. A tagged photon beam within the energy range of 0.298 and 0.941 E_0 divided into 703 energy-channels is now available. The results of detailed measurements show that the system is working well and is in good agreement with the design. A calibration of the system with two different methods was done and is presented here. From this a first estimation of the energy-resolution could be derived. In addition a model to determine the amplication factor (gain) of gas-detectors in the proportional region has been successfully tested and could be used to describe the variation of the gain in the central drift chamber (CDC) as a function of the density fluctuations. hence by measuring the air pressure and the temperature the necessary modification of the chamber high voltage to stabilize the gain can be maintained. (orig.)Available from TIB Hannover: RN 4852(96-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Aufbau und Test der Proportional-Drahtkammern fuer TOPAS II

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman