Thesis

The proton electromagnetic form factors (FF) in the space-like region (q2 < 0) have
been measured for multiple decades using electron{proton scattering and Rosenbluth separation
method. Recently developed polarization transfer technique resulted in a dierent
value of extracted FF. It was suggested that the previously unaccounted hard two-photon
exchange (TPE) eect, can be responsible for the discrepancy. The OLYMPUS experiment
performed a high precision measurement of the TPE contribution via measurement
of the positron to electron elastic scattering cross section ratio. It was performed
at DESY using 2 GeV electron and positron beams and the BLAST spectrometer. A crucial part
of the experiment was precise measurement of the integrated luminosity. The symmetric
Moeller/Bhabha luminosity monitors, which were designed and built in Mainz, used Mller
and Bhabha processes for luminosity measurements. The analysis of the collected SYMB
data is presented in this work.

In the time-like region, where q2 > 0, form factor data is scarce and only the ratio of
electric to magnetic form factor have been measured so far. The PANDA experiment will
be able to measure individual electric and magnetic time-like FF. Extensive feasibility
studies of the proton form factor measurement have been performed using PandaRoot
simulation framework. This include the signal pbar p -> e+e- selection, the main background
pbar p -> pi+ pi- suppression, and investigation of possible sources of systematic uncertainties
in the q2 range between 5.4 GeV^2 and 13.9 GeV^2. The estimated statistical and systematic
accuracy of the proton FF extraction at PANDA is 2%-57%.

Beim PANDA-Experiment können Hadronen aller Quantenzahlen erzeugt werden, in-
dem Antiprotonen auf ein Target innerhalb des PANDA-Detektors geschossen werden.
Schwerpunkte der Forschung sind die starke Wechselwirkung, die Spektroskopie von D-,
D s -Mesonen und Charmonium, sowie die Erforschung von Hadronen mit gluonischer An-
regung und Glueballs. Alle Messdaten des Detektors werden kontinuierlich erfasst und in
Echtzeit nach physikalisch interessanten Werten durchsucht (online event filtering). Um
die Datenmenge von bis zu 200 GBit/s zu verarbeiten, ist ein umfangreiches Computer-
netzwerk erforderlich.
Ein solches Netzwerk, das zahlreichen Nutzern zur Verfügung steht und teilweise mit
dem Internet verbunden ist, birgt immer auch die Gefahr der Manipulation. Die vorlie-
gende Arbeit widmet sich der Frage, wie sich die Übertragungswege der Messdaten des
PANDA-Experiments schützen lassen. Es wird beschrieben, wie das Protokoll TLS und
verschiedene Verschlüsselungs- bzw. Signaturalgorithmen den Schutzbedarf des PANDA-
Experiments erfüllen. Da es in der Vergangenheit jedoch mit Hilfe zeitbasierter Seiten-
kanalangriffe gelungen ist, die Sicherheitsfunktionen von TLS zu überwinden, wird die
Messgenauigkeit von Antwortzeiten in einem Computernetzwerk unter Optimalbedin-
gungen und darüber hinaus in realitätsnahen Szenarien untersucht.

The PANDA experiment will study a wide range of physics topics with beams of antiprotons incident on fixed proton or complex nuclear targets. One issue is the Ds semileptonic decay, which is governed by the weak and strong forces. The interaction can be parameterized by a transition form factor. The performance of PANDA to measure the decay form factor of Ds + → νe η e+ is evaluated via Monte Carlo simulation. This thesis concentrates on describing the software development and the evaluation of the expected precision. A preliminary estimate of the expected count rate is obtained. In this measurement, it is essential to reconstruct the Ds semileptonic decay with high efficiency and purity in order to overcome the many orders of magnitude higher background. The Micro-Vertex-Detector plays an import role in the whole tracking system. The rate capability and tracking performance of the recent ASIC prototype for the readout of the MVD is tested using a beam of high-energy protons.

The PANDA experiment is one of the future experiments at FAIR, it will pursue a broad
physics program with high quality antiproton beam in the momentum region from 1.5 to
15 GeV/c. The goal of the PANDA luminosity detector is to determine the absolute in-
tegrated luminosity with precision of
∆L/L ≤ 3%. The antiproton-proton elastic scattering
differential parameters, σ tot , ρ and b are needed for the PANDA luminosity calibration
in order to achieve this high precision of absolute normalization. However, the existing
data of σ tot , ρ and b in the PANDA beam momentum range are not sufficient by precise
for the PANDA luminosity calibration.
The HESR Day-One experiment is dedicated to determine the differential param-
eters by measuring antiproton-proton elastic scattering in a large range of squared 4-
momentum transfer, |t|. The HESR Day-One experiment will measure the elastically
scattered antiprotons and recoil protons with the PANDA luminosity detector and a
recoil detector, respectively. One recoil detector consists of two silicon and two germa-
nium sensors by covering the polar angle range from θ = 71 ◦ to 91.5 ◦ . The silicon and
germanium detectors are single-sided strip structure. Both silicon detectors have the di-
mensions 76.8 mm × 50 mm × 1 mm. The two germanium detectors have the same ac-
tive area of 80.4 mm × 50 mm, but with thickness of 5 mm and 11 mm, respectively. The
silicon detectors will measure the recoil protons below 12 MeV, and the germanium de-
tector will measure the recoil protons up to 60 MeV.
A dedicated recoil detector for tests with proton beam at COSY has been built. After
assembly, the silicon and germanium detectors have been tested in the laboratory with
the radioactive source 244 Cm. The optimal operation temperature, 125 K, of the germa-
nium has been determined. The energy resolutions of the silicon and germanium detec-
tors at 125 K are better than 20 keV and 30 keV, respectively.
Energy calibration for the silicon and germanium detectors has been studied. The
uncertainty of ADC’s nonlinearity is about 0.31%. The silicon detectors have been
calibrated with several standard sources and the uncertainty of the energy calibration of
the silicon detectors has been estimated to be around 0.33%. The germanium detectors
have been calibrated with the radioactive sources 60 Co, 137 Cs and 244 Cm. Based on the
α particle’s energy deposited in the sensitive area of the germanium detectors, the dead-
layer thickness of the Ge #1 and Ge #2 sensors have been determined to be 0.72 μm
and 0.82 μm of equivalent silicon, respectively. The uncertainty of energy calibration of
the germanium detector is about 0.31%.
Simulation studies of proton-proton elastic scattering at 3.2 GeV/c has been per-
formed. The detector’s acceptance has been obtained. The differential counts as a func-
tion of |t| has been reconstructed with acceptance correction. The proton-proton elastic
scattering differential parameters σ tot , ρ and b have been determined by analyzing the
characteristic shape of the |t| distribution with optical theory and parameterized expres-
sions.
Due to the recoil particle and kinematics to be measured in pp→pp are the same
as that in pp →pp at a certain beam momentum, it is reasonable to learn about pp →pp
from pp→pp. Therefore, the recoil detector was installed at the ANKE cluster target sta-
tion at COSY and commissioned by measuring proton-proton elastic scattering in 2013.
Data were taken at beam momenta of 1.7, 2.5, 2.8 and 3.2 GeV/c. For 2.8 GeV/c and 3.2
GeV/c, the differential counts as a function of |t| distributions have been reconstructed
based on the centroid energy and elastic events in the identical strips. After analysing
the characteristic shape of the |t| distribution, the elastic scattering differential parame-
ters and integrated luminosity have been determined. The uncertainty of σ tot and b were
better than 1% and of ρ was about 2%. The absolute integrated luminosity within preci-
sion of ∆L/L ≤ 3% was achieved. Comparing the measured σ tot and ρ with the predicted
values based on existing data, the differences between our results and the predicted
values are less than 1.5%, but the measured b values are about 20% greater than the
predicted ones. The differential cross section
obtained. The dσ/dt at 2.8 GeV/c and 3.2 GeV/c have been
distribution of our results in the range of |t| ∈ [0.02, 0.095] (GeV/c) 2
are in good consistent with the existing data at 3.0 GeV/c. These results demonstrate
that the HESR Day-One experiment is feasible and the data analysis method is reliable.

The forward tracking system (FTS) is a straw-tube based detector in
the forward-part of the PANDA-detector. It is specializing in reconstruc-
tion of particle trajectories. The FTS consists of six stations. Each station
consists of four doublelayer straw-tubes. The second doublelayer is skewed
5 to the right and the third doublelayer is skewed 5 to the left. The first
and the fourth doublelayer are not skewed. The stations are numbered
with FTS1-FTS6. Between FTS2 and FTS5 is a magnetic field located so
charged particles will be distracted to the left or to the right. If a particle
fly through the FTS there will be FTS-hits at the position of the taken
straw-tubes created. It is necessary to reconstruct the trajectories of the
particles which are crossing the FTS. In this thesis an algorithm has been
developed which gets FTS-hits and creates PndTracks for the trajectory
in the FTS.

The Panda experiment, currently under construction at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, addresses fundamental questions in hadron and nuclear physics via interactions of antiprotons with nucleus / nuclei. The High Energy Storage Ring will provide an antiproton beam with a momentum range of 1.5 – 15 GeV/c and an average collision rate of 20~MHz on a fixed target. Due to a missing hardware trigger and a continuous data acquisition in the \panda experiment, a highly advanced online analysis is needed to achieve an online data reduction of a factor 100 – 1000 before storage. A missing collision time (\t0), high interaction rates and overlapping event data in the sub detector systems further increases the difficulty of the event reconstruction.

The Barrel Time-of-Flight detector (Barrel TOF) for Panda, being developed at the Stefan Meyer Institute, will be one of the key components in Panda to determine the origin time of particle tracks, to ensure a disentanglement of overlapped hits from neighboring collisions and to provide information about \t0. Another important task of the Barrel TOF is to provide particle identification (PID) for charged particles together with the Cherenkov-based PID detectors, which is especially important for particle momenta below 700 MeV. In order to achieve a time resolution of < 100 ps, required for the mentioned disentanglement of the data, while keeping a minimal material budget, the detector will be realized as a barrel-shaped scintillator tile hodoscope. It covers the central region of the detector with a diameter of about 1~m and a length of about 2~ m. The sensitive area of about 6~ m² consists of 1920 scintillating tiles with a dimension of 90 x 30 x 5 mm³ each, readout by 8 Silicon Photomultipliers (SiPMs), with 4 on each end connected in series. The signal transmission lines are embedded in a multilayer PCB backplane. It also serves as the mechanical frame to minimize the material budget. During beam tests a single tile time resolution of about 55 ps in standard deviation has been achieved.

It was a crucial and challenging task to implement the Barrel TOF in the simulation framework, PandaRoot. This allowed the optimization of the detector geometry using Monte Carlo simulations and the investigation of the requirements for the readout electronics and led to the described design. In the second phase the performance of the Barrel TOF was evaluated and optimized for the entire experiment. For this purpose software algorithms based on the Barrel TOF system were developed and implemented in PandaRoot, i.e. triggering, event sorting, start time reconstruction and particle identification. Among other work this allowed the submission of the Technical Design Report for the Barrel TOF in February 2017 to FAIR, which has been accepted. After this the developed and implemented algorithms as well as the acquired knowledge were used to advance the general \panda reconstruction chain. Together with our international collaborators the first steps towards a dynamical tracking and event reconstruction algorithm, which combines the signal of all sub detector systems of Panda, were developed.

In this thesis the prototype system for processing of the signals generated in the
straw tube trackers of the PANDA spectrometer is proposed, built and evaluated. The
full processing chain of signal consists of programmable readout electronics, configware
and analysis methods. The proposed readout is based on the front end electronics,
equipped with the configurable PASTTRECv1 ASIC (PANDA STT REadout Chip
version 1 Application Specific Integrated Circuit) and the readout board (TRBv3 - Trigger
Readout Board version 3) acting as data concentrator and time measurement device.
The readout system performs full chain of data processing consisting of analog
shaping, digital conversion and data transmission. A dedicated analysis methods have
been developed to extract track position and a particle energy deposit in the detectors.
Dedicated tests of the system by means of the cosmic rays and proton beams have
been performed. The results prove that the spatial resolution better than 150 m can
be achieved. Furthermore, particle identification based on time over threshold method
can be successfully applied in the momentum region below 800 MeV/c. The last but
not least goal was to show that it is possible to realize complete readout system based
on the concept presented in this thesis which is capable of cope with the hit rates of the
PANDA spectrometer.

Einer der am wenigsten getesteten Aspekte des Standardmodells der Teilchenphysik ist die Verletzung der Teilchen-Antiteilchen-Symmetrie, welche formal die Invarianz bei sukzessiver Anwendung der Ladungskonjugation C und der Raumspiegelung P bricht. Der im heutigen Universum beobachtete Überschuss an Materie gegenüber Antimaterie legt nahe, dass die CP-Invarianz kurz nach dem Urknall bei hohen Energieskalen in einem Umfang verletzt worden ist, den das Standardmodell quantitativ nicht zu erklären vermag. Ein Test der CP-verletzenden Mechanismen des Standardmodells bietet daher hohes Potential die gängige Theorie zu erweitern.

Experimentell gibt es bislang ausschließlich im Bereich der neutralen Mesonen K0, B0 und Bs0 Evidenz für das Auftreten von CP-Verletzung, im Charm-Quark-Sektor (D0) konnte diese bislang nicht bestätigt werden. Bei den bekannten Mechanismen der CP-Verletzung handelt es sich neben direkter um sogenannte indirekte CP-Verletzung, die auf physikalisch erlaubten Übergängen zwischen Teilchen und Antiteilchen beruht (z. B. D0 -> D0bar) und als solche zeitabhängig ist.

Das zukünftige PANDA-Experiment am FAIR-Komplex in Darmstadt bietet durch seinen Aufbau mit ruhendem Target sowie hoher Orts- und hierdurch bedingter Zerfallszeitauflösung gute Vorraussetzungen für eine zeitabhängige Analyse von korrelierten D0D0bar-Paaren aus Psi(3770)-Zerfällen.

In der vorliegenden Arbeit wird die Messbarkeit von CP-Verletzung und D0D0bar-Mischung am PANDA-Experiment in einer zeitabhängigen Dalitz-Diagramm-Analyse des Zerfalls D0 -> Ks pi+ p- untersucht.

Der erste Teil der Arbeit entwickelt hierzu ausgehend von der Methode der maximalen Likelihood einen Fitalgorithmus, der es ermöglicht, Parameter der dynamischen Übergangsamplitude, Mischungs- und CP-verletzende Parameter aus der beobachteten Verteilung der Viererimpulse der Endzustandsteilchen zu bestimmen. Durch eine explizite Faltung von Übergangsamplitude und Auflösungsfunktion der Zerfallszeit wird hierbei auch der nicht vernachlässigbare Messfehler der Zerfallszeit berücksichtigt. Eine rein statistische Analyse erlaubt es, die zur Messung notwendige Ereignismenge abzuschätzen und den Einfluss der Zeitmessung auf diese zu quantifizieren.

Im zweiten Teil wird anhand einer detaillierten Simulationsstudie im PANDA-Simulations-Framework PandaRoot die Rekonstruierbarkeit des betrachteten Zerfallskanals untersucht. Neben der Auflösung relevanter invarianter Massen und einer allgemeinen Charakterisierung der Teilchenidentifikation liegt ein besonderer Schwerpunkt auf der Messung der wenige hundert Mikrometer kurzen Zerfallslänge des D0-Mesons innerhalb des Detektors. Hierbei wird auch gezeigt, dass es für die Analyse nicht erforderlich ist, den experimentell schwierig zu bestimmenden primären Antiproton-Proton-Interaktionspunkt direkt zu messen. Zudem wird die Separierbarkeit des Signalkanals von hadronischen Untergrundreaktionen untersucht.

Der abschließende dritte Teil zeigt durch Anwendung des erstellten Fitalgorithmus auf simulierte Stichproben, inwieweit es gelingt, die resonante Dynamik des Dreikörperzerfalls D0 -> Ks pi+ pi- aufzulösen und gibt eine finale Abschätzung der erreichbaren Präzision in der Messung von D0D0bar-Mischung mit der verwendeten Methode am PANDA-Experiment.

The envisaged physics program of the PANDA (antiProton ANnihilation at Darmstadt) experiment at the future Facility for Antiproton and Ion Research (FAIR) requires excellent particle identification over the full solid angle. The Endcap Disc DIRC (EDD) will cover forward polar angles between 5 and 22◦ and is one of three dedicated subdetectors for the identification of charged hadrons and the separation of pions and kaons in particular. DIRC stands for Detection of Internally Reflected Cherenkov light and implies that the emitted Cherenkov photons are trapped inside the radiator by total internal reflection.
The central part of each DIRC detector is its optical system which is responsible for a lowloss and angle-preserving transport of the Cherenkov photons. The work at hand experimentally addresses several objectives in connection with the optical components and the system as a whole. Radiator prototypes were evaluated with high precision and adapted specifications were identified based on the results. The imaging performance of the Focusing Elements (FELs) was verified and different options regarding the coupling of the individual components were evaluated. In addition a radiation hardness study of a new fused silica material provided an insight into the long term behavior of induced defects and confirmed the material to be suitable for high energy physics experiments.
A conceptual design for the mechanical integration was developed featuring a rigid optical system which is mounted into a cross-like structure. In this context the spatial constrains for the holding structure and the FELs were identified and an assembly procedure was developed. The existing prototype was revised and newly developed concepts were integrated and tested.
Furthermore a data analysis of an earlier prototype test at a mixed hadron beam at CERN was carried out. It was the first evaluation of an EDD prototype which consisted of optical components made of fused silica only and had highly segmented MCP-PMTs (Micro-Channel Plate PhotoMultiplier Tubes) for the photon detection. A single photon resolution down to 5.68 mrad could be achieved and a good agreement with Monte-Carlo predictions was reached. At 3 GeV/c a 5σ separation of pions and protons was accomplished using a single MCP-PMT column.