Submitted by u.kurilla on Wed, 02/04/2014 - 14:49.
The proton is a bound state of quarks which are held together by the strong force, mediated by gluons. The understanding of the proton structure is presently one of the central issues in hadron physics. The present work reports on phenomenological and experimental studies related to the possibilities offered by the future antiproton beam at the FAIR facility at Darmstadt, in the momentum range between 1.5 and 15 GeV/c. After a classification of the reaction channels which are accessible in antiproton-proton annihilation, the main features of the PANDA detector are described. A chapter of this thesis is dedicated to the study of the optical coupling between crystals and photodiodes in the electromagnetic calorimeter, which will be operated at low temperature (-25◦ C). Mechanical, thermal, optical properties and radiation hardness of two commercial glues are quantified. Feasibility studies of the reaction pp → e+ e− for the Time-Like proton form factor measurements at PANDA are presented. The electromagnetic structure of the proton is parametrized in terms of electric GE and magnetic GM form factors. The electromagnetic interaction is well described by the theory of quantum electrodynamics. The traditional tool to determine proton electromagnetic form factors is polarized and unpolarized electron-proton elastic scattering, assuming that the interaction occurs through the exchange of one virtual photon. The crossed symmetry channels pp ↔ e+ e− allow to access the Time-Like region. The background reactions are also studied, in particular the pp → π + π − channel. The results obtained from a realistic Monte Carlo simulation using PANDARoot show that the proton form factor ratio can be measured at PANDA with unprecedented accuracy. The effects of radiative corrections due to real and virtual photon emission are considered. Based on a model independent formalism, the calculation of the experimental observables for the pp → e+ e− reaction is extended to the annihilation into a heavy lepton pair which carries the same physical information on the proton structure as the electrons. In this case, the lepton mass can not be neglected. The same formalism is also applied in Space-Like region to the elastic scattering of protons from electrons at rest (pe-inverse kinematics). We suggest that the elastic pe scattering can be used to polarize and/or to measure the polarization of high energy proton (antiproton) beams, and allows a precise measurement of the proton charge radius.
Submitted by u.kurilla on Wed, 02/04/2014 - 12:06.
The PANDA experiment will be built at the upcoming FAIR facility at GSI in Darmstadt, featuring antiproton-proton reactions hadron physics in a medium energy range. Charm physics will play an important role and therefore secondary decays relatively close to the interaction zone as well. The MVD will be the detector closest to these and will provide high-quality vertex position measurements. Alongside the detector layout and hardware development a detailed detector simulation and reconstruction software is required. This work contains the detailed description and the performance studies of the software developed for the MVD. Furthermore, vertexing tools are introduced and their performance is studied for the MVD.
Submitted by u.kurilla on Wed, 02/04/2014 - 11:57.
PANDA is one of the experiments which will be installed at the FAIR facility in Darmstadt. It will study the collisions of an antiproton beam with different fixed targets. The main focus of the experiment will be on strong interactions at the energy regime corresponding to the charm quark region. Charmonium states, open-charm mesons and charmed baryons will be studied with a high precision experiment. The tracking detectors will play an important role allowing for a precise reconstruction of particles momenta and decay vertices. In particular, in the case of short-lived particles, the contribution of the Micro-Vertex-Detector (MVD), which is the innermost tracker of the experiment, will be crucial. Detailed Monte-Carlo studies based on an implementation of the detector geometry will be presented analyzing the coverage and vertex reconstruction performance of the MVD in different physics scenarios compatible with the PANDA operational modes. Experimental results obtained with MVD prototype sensors at different particle accelerators will be shown comparing the observations with predictions from Monte-Carlo simulations of the setups. An analysis of the potential reconstruction performance of the PANDA experiment for the pp → Λc Λc reaction will be presented together with a study of the signal to background significance for the selected decay pattern.
Submitted by u.kurilla on Wed, 02/04/2014 - 11:50.
Particle physicists have successfully unveiled the fundamental structure of matter with quarks and leptons as elementary constituents. However, it still remains to be explained, how protons and neutrons, the building blocks of atomic nuclei, gain their mass from the interaction between their almost mass-less constituents. An elucidating answer to this problem can be obtained by studying composite systems (in particular “mesons”) containing a heavy “charm” quark or by demonstrating a predicted new exotic type of composite systems with yet unobserved quark combinations. Such systems can be produced in proton-antiproton collisions at the accelerator-complex FAIR in Germany, presently under construction. The particles produced in such powerful collisions will be examined by novel state-of-the-art detection systems. Since the probability to produce rare charm-meson states or even exotic systems is very low, the proton-antiproton collisions need to be performed at extremely high rates. Consequently, subsequent detector signals may overlap which would lead to a dramatic loss of vital information. Instead of well-proven conventional detector-readout systems, we have developed a novel “free-streaming” data readout with “online” event selection and recovery of overlapping signals. The new method was successfully applied in accelerator experiments. We have demonstrated that simple yet powerful algorithms can be developed for the “online” event selection during data transport. The implementation of the studied method in a novel large-scale readout system will allow operating the detector at high collision rates such that a large amount of data can be reliably and precisely processed and rare events can be discovered with high efficiency.
Submitted by u.kurilla on Wed, 02/04/2014 - 10:55.
The PANDA detector at the future FAIR facility in Darmstadt will be a key experiment in the understanding of the strong interaction at medium energies where perturbative models fail to describe the quark-quark interaction. An important feature of the detector system is the ability to reconstruct secondary decay vertices of short-lived intermediate states by means of a powerful particle tracking system with the the Micro-Vertex Detector (MVD) as central element to perform high-resolution charmonium and open-charm spectroscopy. The MVD is conceived with pixel detectors in the inner parts and double-sided silicon strip detectors at the outer half in a very lightweight design. The PANDA detector system shall be operated in a self-triggering broadband acquisition mode. Implications on the read-out electronics and the construction of the front-end assemblies are analyzed and evaluation of prototype DSSD-detectors wrt. signal-to-noise ratio, noise figures, charge sharing behavior, spacial resolution and radiation degradation discussed. Methods of electrical sensor characterization with different measurement setups are investigated which may be useful for future large-scale QA procedures. A novel algorithm for recovering multiple degenerate cluster hit patterns of double-sided strip sensors is introduced and a possible architecture of a Module Data Concentrator ASIC (MDC) aggregating multiple front-end data streams conceived. A first integrative concept for the construction and assembly of DSSD modules for the barrel part of the MVD is introduced as a conclusion of the thesis. Furthermore, a detailed description of a simplified procedure for the calculation of displacement damage in compound materials is given as reference which was found useful for the retrieval of non-ionizing energy loss for materials other than silicon.