Exploring the Merits and Challenges of Hyperon Physics
by
Walter Ikegami Andersson(Uppsala University)
→
Europe/Stockholm
Beurlingrummet (Ångström )
Beurlingrummet
Ångström
Description
(Final PhD seminar)
Binary hyperon production in antiproton-proton annihilations will be carried out with the PANDA experiment at FAIR, and probes the strong interaction in the non-perturbative regime where the relevant degrees of freedom are unclear. The self-analysing decays of hyperons provide a straightforward way to study reaction dynamics via the measurement of spin observables. However, since weakly decaying hyperons can travel several centimeters before decaying, they are challenging to reconstruct. This is because conventional track reconstruction algorithms assume that charge particles originate in the experiment interaction point.
In this thesis, software tools are developed for the reconstruction and fitting of charged particles in the collaboration-wide software package PandaRoot. Pattern recognition algorithms are developed for the reconstruction of charged particle tracks with displaced vertices. Three algorithms that reconstruct the longitudinal momentum in the Straw Tube Tracker (STT) of PANDA are developed. They are based on a combinatorial approach, a Hough Transform, and a recursive annealing fit. The implementation and performance of these algorithms will be presented. The track fitting scheme of PandaRoot is overhauled to treat the five particle species that PANDA is expected to measure, namely electrons, muons, pions, kaons and protons. The new track fitting scheme will be outlined.
When the PANDA experiment is taken into operation, beam time will be allocated to many different measurements. For this reason, feasibility studies are performed in this thesis. The production of Lambda-hyperon pairs is simulated at 1.642 GeV/c and the production of charged Cascade-hyperons is simulated at 7.0 and 4.6 GeV/c beam momenta. The feasibility of reconstructing the reactions exclusively as well as the spin observables in the reactions will be presented.
