Conclusion

The HERA-B experiment located at the HERA collider at DESY, was designed and built to measure CP violation in the system of neutral B mesons. HERA-B has the typical setup of a forward magnet spectrometer with a fixed multi-wire target. The experiment is designed to cope with large particle fluxes up to $10^{7}s^{-1}cm^{-2}$.

Based on the data taken in the running period 2000 it was concluded that the performance of the default pattern recognition package RANGER is not at the sufficient level, especially for the Inner Tracker system. This motivated the development of an alternative track reconstruction package OTR/ITR-CATS for the Pattern Tracker of the HERA-B experiment. This package employs a combined approach for track reconstruction based on the use of a cellular automaton for track searching and the Kalman filter technique for track fitting. Comprehensive tests of the package have shown high reconstruction efficiency, good accuracy of track parameter estimates, a reasonable behavior of CPU time consumption. Based on the demonstrated performance CATS has been chosen as the new default pattern recognition package. The algorithm was successfully used during online data taking and offline reprocessing of the collected data in the years 2002 and 2003.

During the running period 2002/03 the performance of the Inner Tracking system was estimated. A method was developed to measure the hit efficiency for the Inner Tracker system. The applied procedure was based on the developed pattern recognition algorithm. During running in 2002-2003 several chambers of the Inner Tracker system demonstrated rather low efficiency, due to a low resistance between neighboring strips on the Kapton FanIn. For chambers which were not affected by the above mentioned problem, the efficiency varies between 90% and 95%. Affected chambers showed efficiencies between 50% and 90%.

In the second part of this thesis, the results of a measurement of the inclusive production cross section of $K_S^0$, $\Lambda$ and $\bar \Lambda$ particles using the HERA-B detector were presented. The geometrical acceptance and reconstruction efficiency were estimated by using Monte Carlo simulation. The overall efficiency to reconstruct the $V_0$ was found to be about 10% for $K^0_S$ and 5% for $\Lambda (\bar \Lambda)$. Various sources of systematic uncertainties, such as luminosity determination, MC description of data especially $p_t^2$ and $x_F$ kinematical variables were estimated. The $V_0$ cross sections were measured for three types of target material, carbon , titanium and tungsten. Dependence of the total cross section $\sigma_{pA}$ on the target atomic mass is measured. Obtained inclusive production cross sections were compared with results of other experiments.

The obtained measurements in the negative $x_F$ region will provide important input to the theories which are needed for the study of fragmentation processes.