Production and Flow of Neutral Strange Particles in Ni+Ni Collisions at 1.93 AGeV

This thesis presents results on the production and the flow of K⁰ and \Lambda⁰ in Ni+Ni collisions at an energy of 1.93 AGeV. The analyzed data sample of 10⁸ central events has been recorded during 12 days using an upgraded data acquisition with a fast online data reduction algorithm. Part of this work was the implementation of this algorithm on a digital signal processor. The slope parameter and yield distributions of the K⁰ are found to agree with those of previously measured K⁺. Comparisons to transport model calculations (UrQMD, IQMD) show that none of the models is able to consistently describe those distributions for both, K⁰ and \Lambda⁰. The integral and the differential directed flow of the K⁰ are found to agree with that of the K⁺, supporting the evidence for a repulsive K⁺N potential. Comparing the directed flow of \Lambda⁰ and protons, no significant difference is found between both for the integral as well as the differential flow. This brings up the issue of the strength of the in-medium $\Lambda$N potential and its relation to the magnitude of the observed flow. A method to reconstruct \Xi^- and \Sigma^-(1385) baryons has been developed and candidates of both particles have been identified. The very small reconstruction efficiency requires confirmation through an experiment with a significantly larger statistics, though.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2004

Author dc:creator

• Merschmeyer, Markus

Contributors dc:contributor

• Herrmann, Norbert

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/5061

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:5061