Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 58: Plenar

HK 58.3: Group Report

Thursday, March 19, 1998, 12:30–13:00, P

Meson Physics at CELSIUS — •T. Johansson — Dept. of Radiation Sciences, Uppsala University, Box 535, S-75121 Uppsala, Sweden

The CELSIUS storage ring at the The Svedberg Laboratory, Uppsala, has been operational for a few years and a many physics results are starting to emerge from the experiments. The main focus has been on meson production in p+p, p+d, d+d and p+A collisions, where both charged and neutral mesons have been detected. Continous excitation functions have been measured for inclusive pion production in p+A collisions and threshold measurements of the p+p →p+p+π⁰ rection confirm the results from IUCF. The theoretical understanding of the latter is still an open question. Specific reaction channels which have been measured for the first time include the p+n→d+η and p+n→p+n+η processes. The measurements of these, and similar reactions very near threshold, exhibit effects from the strong and attractive eta-nucleon interaction. There have been many speculations upon the possible existence of quasi-bound eta-nuclear systems and the recent CELSIUS results are shedding additional light on this question. The ensemble of results has yielded extra constraints on the theoretical understanding of both the basic reaction mechanism and final state interactions in meson production.