TY  - GEN
A1  - Britsch, Markward
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/3584/
N2  - The subject of this thesis is a measurement of hyperon production ratios which is of special interest as a reference on Quark Gluon Plasma search. The data used in this analysis have been taken with a minimum bias trigger at the fixed target experiment HERA-B, which uses the 920 GeV proton beam of the HERA storage ring at DESY. $\Lambda$, $\Xi$ and $\Omega$ hyperons produced in collisions using carbon and tungsten wires as targets were reconstructed. Hyperon ratios are presented for the rapidity range $-1.5 < y < 0.5$ (where they  where measured), extrapolated to the whole phase space and to $y = 0$. The main  results at $y = 0$ are $\frac{\overline{\Lambda}}{\Lambda} = 0.88 \pm 0.07$ (error including systematic error) and $\frac{\overline{\Xi}}{\Xi} = 0.69 \pm 0.12$ (statistical uncertainty only) for the carbon target. These values are compared to proton--nucleus and nucleus--nucleus data above and below HERA-B energies and are comparable with both. In the rapidity range $-1.5 < y < 0.5$ the ratio $\frac{\overline{\Lambda}}{\Lambda}$ is significantly different for the two target materials, whereas extrapolated to the whole phase space it is not. A possible explanation in terms of multiple scatterings in the nucleus is given. The distribution of the $\Lambda$ particle--anti-particle asymmetry versus Feynman's scaling variable $x_f$ using the carbon target is  found to be in good agreement with measurements from pion--nucleus reactions at  500 GeV $\pi$-beam energy.
AV  - public
TI  - Hyperon Production in Proton-Nucleus Collisions at 42 GeV Center of Mass Energy
Y1  - 2003///
ID  - heidok3584
KW  - HERA-B 
KW  -  Target-Abhängigkeit 
KW  -  Omega-HyperonTarget-Dependence 
KW  -  Proton-Nucleus-Reaction
ER  -