Detector software

The PANDA experiment at FAIR offers unique possibilities for performing hyperon physics.
The detector will enable the reconstruction of both hyperon and antihyperon, which will
be created together in proton-antiproton collisions. This enables investigations of the strong
interaction in the non-perturbative regime. Due to their relatively long-lived nature, the hyperons
impose a particular challenge on the track reconstruction and event building. In order to
exploit the large expected reaction rates to the fullest, PANDA will utilize a fully software-based
event filtering. Therefore, reconstructing hyperons for such a filter requires online track
reconstruction that can handle particles created a measurable distance away from the interaction
point and, at the same time, operate on free streaming data is needed. Until antiprotons are
available at PANDA, a part of the hyperon program can be carried out with the predecessor,
PANDA@HADES using a proton beam.
In this thesis, investigations of the detector signatures from the decay channels Λ → pπ-, Ξ- →
Λπ- and Ω- → Λ K- produced in YbarY reactions are presented. The detector signatures guide
the subsequent track reconstruction algorithms. A candidate for online track reconstruction
algorithms on free streaming data based on a 4D Cellular Automaton has been developed and is
benchmarked. It utilizes information from the PANDA straw tube tracker and is agnostic to the
point of origin of the particle. The track reconstruction quality assurance procedure and results
from the tracking at different event rates are also presented. Finally, extrapolation algorithms
for including hit information from additional detectors in the tracks are outlined.
In order to maximize the potential of the predecessor experiment PANDA@HADES, a
kinematic fitting procedure has been developed for HADES that combines geometric the decay
vertex information of neutral particles and track parameters such as momentum. Benchmark
studies on simulated data from the channel p(3.5 GeV)p → ΛK+p are presented as well as tests
of the kinematic fit on experimental data from 2007.

PANDA Management Quarterly Report 21Q3

PANDA Management Quarterly Report 21Q2

This thesis presents work focused on three topics related to hyperon physics.
The first part presents a track finding algorithm for the future PANDA experiment forward tracker using the state-of-art graph neural networks. The detection of forward emitted particles plays a significant role in the reconstruction and analysis of the ground state and excited hyperons (e.g., $\Sigma^{0}$ , $\Sigma(1385)$, $\Lambda(1405)$ and $\Lambda(1520)$). The network accepts an image of the forward tracker as an input, where the detector hits are the graph vertices, and all possible connections between two hits in adjacent layers are the graph edges. It was trained as a binary classifier to classify the graph edges.
The second part of the thesis presents a study of the production mechanism of the $\Sigma^{0}$ hyperon via the exclusive reaction $pp \rightarrow pK^{+}#Sigma^{0}$ at beam energy 3.5 GeV with the HADES detector setup. In total, 2613 events were reconstructed 58\% are within the main HADES acceptance and 42\% within the forward wall acceptance. Furthermore, the dynamics of the reaction \Ssignal were investigated by studying the angular distributions in the CMS, Gottfried-Jackson and helicity frames. The total production cross section of the \Szero hyperon was obtained by integrating the yield for the different angular distributions and found to be $\sigma = 18.74 \pm 1.01 (stat) \pm 1.71 (syst)$ $\mu b$.
The last part of the thesis presents a feasibility study to investigate excited hyperons radiative decays using the upgraded HADES setup and the new forward detector as part of the FAIR Phase-0 physics program.

Next-generation DIRC detectors, like the PANDA Barrel DIRC, with improved optical designs and better spatial and timing resolution, require correspondingly advanced reconstruction and PID methods. The investigation of the PID performance of two DIRC counters and the evaluation of the reconstruction and PID algorithms form the core of this thesis. Several reconstruction and PID approaches were developed, optimized, and tested using hadronic beam particles, experimental physics events, and Geant simulations. The near-final design of the PANDA Barrel DIRC was evaluated with a prototype in the T9 beamline at CERN in 2018. The analysis finds excellent agreement between the experimental data and the Geant simulations for all reconstruction algorithms. The best PID performance of up to $5.2 \pm 0.2$ s.d. $\pi$/K separation at 3.5 GeV/c, was obtained with a time imaging PID method. The PANDA Barrel DIRC simulation, as well as the reconstruction and PID algorithms, were evaluated using experimental data from the GlueX DIRC as part of the FAIR Phase-0 program. The performance validation was carried out using physics events of the GlueX experiment and simulations. The initial analysis results of the commissioning dataset show a $\pi$/K separation power of up to 3 s.d. at a momentum of 3.0-3.5 GeV/c, obtained using a geometric reconstruction algorithm.

PANDA Management Quarterly Report 21Q1

PANDA Management Quarterly Report 20Q4