PANDA experiment is one of the main scientific pillars of the fu-
ture Facility for Antiproton and Ion Research, currently under construc-
tion in Darmstadt, Germany. It will investigate hadron physics measur-
ing antipron-proton annihilation reactions. The antiproton beam with mo-
, will allow to explore a broad physics
program including hyperon, open-charm and exotic hadronic states.
The Micro Vertex Detector (MVD) is the innermost sub-detector of the
tracking system of the
PANDA experiment. It is based on silicon sensors
with pixel and micro strip segmentation and its main task is the precise
spatial identification and measurement of primary and secondary decay
This thesis describes the key features of the
PANDA Strip ASIC (PASTA),
a full-custom chip developed to read out the double-sided micro strip sen-
sors of the MVD. PASTA aims at highly resolved time-stamping and charge
information gathering through a time-digital approach. A Time to Digital
Converter (TDC), allowing a time bin width down to
, measures the
Time over Threshold (ToT) of the sensor signals processed by a application
specific, newly developed front-end amplifier. In particular, this thesis re-
ports the theoretical studies yielding to the final implementation showing
the performance of the front-end stage evaluated with professional simula-
This thesis aims to study low-energy strong interaction effects of open-charm mesons. Our studies are based on the chiral Lagrangian supplemented by constraints from the heavy-quark spin symmetry. The pseudoscalar and vector open-charm-meson masses are calculated up to next-to-next-to-next leading order (N^3LO) corrections. Different assumptions on the counting rules are investigated. It is illustrated that a chiral expansion uniformly converges rapidly up to Goldstone boson masses as heavy as the kaon masses if formulated in terms of physical meson masses. First estimates of the relevant low-energy parameters are extracted from lattice QCD data on the quark mass dependence of the D meson masses. Such low-energy parameters are of crucial importance for the low-energy interaction of the Goldstone bosons with the D mesons.
To study rare processes, such as the formation of exotic particles, the PANDA experiment has been set up. To process the large dataflow, the subsystems preprocess the data. One example is the algorithm to search online for clusters in the data of the calorimeter, developed in this thesis. Due to the high interaction rates, the time is important. Optima have been determined to assign the data to (time)bunches (257, 97, and 15 ns) and hits to clusters (282, 122, and 40 ns), for interaction rates of 200 kHz and less, 2 MHz, and 20 MHz, respectively, and each hit must have a minimal energy of 3 MeV. Using these optima, the efficiencies for the investigated two- and seven-photon channels are 70-80% and 9-20%, respectively, depending on the interaction rate. In addition, it was investigated if the algorithm can run on the readout system, making use of the processing power in the data concentrators and the nodes in the data collection network. This was found to be possible, and, furthermore, the processing time using this approach is much lower. An important note to the efficiencies is that there were problems in creating the time stamps for the hits, which may cause the obtained results to deviate from reality. In addition, another step needs to be added to the reconstruction, where the event selection takes place, to determine the final efficiencies. It is recommended to proceed with the development of the cluster finding algorithm, as it delivers good performance at low costs.
Etude des réactions d'annihilation proton-antiproton et contribution expérimentale à la polarimétrie hadronique.Study of antiproton-proton annihilation reactions and experimental contribution to hadron polarimetry
This thesis work, set in the framework of hadron physics, reports on a phenomenological and an experimental study dedicated to nucleon internal structure, both related to hadron electromagnetic form factor measurements in the time-like and in the space-like regions.
At the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, an experimental program aiming to determine the proton electromagnetic form factors in the time-like region is planned benefiting from the PANDA (anti-Proton Annihilation at Darmstadt) large acceptance detector through the annihilation reaction p̄p -> e+ e- and p̄p -> μ+ μ- in the energy range 2.25(1.5) ≤ √s(p L ) ≤ 5.47(15) GeV (GeV/c), where √s(p L ) is the total energy in the center of mass system (the beam momentum in laboratory frame). In such reactions, the difficulty will be to extract the signal of interest from the huge background coming from hadronic channels, mainly pion pair production. Phenomenological studies of meson pair production in p̄p annihilation is one of the subjects of this thesis. The goal is two-fold : to better evaluate the hadronic background and to improve our knowledge on the hadron internal structure as such reaction contains by itself useful information on the hadron quark content. For this purpose, an effective meson model has been developed to evaluate the cross section of p̄p annihilation into light meson pairs, taking into account mesonic and baryonic degrees of freedom, in the energy domain relevant to the PANDA experiment. A logarithmic form factor is introduced to account for the composite nature of the interacting hadrons. A comparison with the existing data for charged pion pair production and predictions for angular distributions and energy dependence are presented in the range 3.362(5) ≤ √s(p L ) ≤ 4.559(10.1) GeV (GeV/c). The model is applied to πp elastic scattering, using crossing symmetry, and to charged kaon pair production, on the basis of SU(3) symmetry. An exponential term is added to reproduce the energy dependence of the total cross section. The model is extended to different neutral channels π0π0, ηη, ηπ0 relying on SU(3) symmetry. The obtained angular distributions and energy dependences are presented and successfully compared to the existing data.
In the space-like region, the experimental effort, started years ago at Jefferson Laboratory (Newport News, VA, USA) and dedicated to precise measurements of the proton electromagnetic form factor ratio based on the recoil polarization method in elastic ep scattering, will be pursued up to higher momentum transfer squared, above 10 GeV2, and will be also applied to neutron. This method requires intense and highly polarized electron beams, as well as an accurate measurement of the polarization of the recoil particle, the proton or the neutron. In order to design and optimize the polarimetry in the GeV region, the determination of the efficiency and the analyzing powers, that combine into the figure of merit, is mandatory to conceive a polarimeter, as polarization experiments are very lengthy. In this context I contributed to the ALPOM2 experiment (JINR Dubna, Russia), the only experiment right now able to measure proton and neutron analyzing powers in the momentum range of interest for Jefferson Lab experiments and allowing considering different types of target. Experimentally, in the framework of ALPOM2, from the Nuclotron polarized deuteron beam (up to 13 GeV energy), polarized proton and neutron beams at 3.0, 3.75 and 4.2 GeV/c were obtained by deuteron break-up and the charged fragments from the collisions with C, CH2, CH and Cu targets were measured. For neutrons, in the beam momentum range from 1 to 6 GeV/c, two processes have been considered to determine the analyzing powers: np -> np (zero charge exchanged) and the charge exchange reaction np -> pn. From the comparison of the figures of merit associated to each of these two processes, the charge exchange reaction appears to be more efficient for polarimetry at high energy. Neutron analyzing powers for the charge exchange reaction on CH, and Cu targets have been measured up to 4.2 GeV/c for the first time. For the proton, more precise analyzing power data have been obtained. Experimental results of preliminary analysis are presented.