Detector hardware

In order to fulfill the goal of producing high rates of doubly strange hyperons the ¯PANDA
collaboration will use the antiproton ring HESR at the future facility FAIR. The low energy
hyperon production by an antiproton beam requires to insert a solid target inside the ring.
Unwanted side effects of such an insertion are the overwelming amount of annihilations, which
would make the detectors blind, and the fast depletion of the bunch, which circulates inside the
ring. The use of a very thin target and the technique of beam steering seem to be a satisfactory
solution to the above problems and will be described here.

In the future hadron facility FAIR the HESR ring will supply antiprotons in the
momentum range 1.5-15 GeV/c as projectiles for charm, strangeness and Form Factor physics.
For all the reactions it will be necessary to use internal targets and in particular, for the
double strangeness production, a solid 12C target will be used. Inserting a solid target inside
an antiproton ring creates two main problems: a large background on the detectors due to the
overwhelming amount of annihilations and a strong depletion of the beam due to all the hadronic
and Coulomb interactions of the antiprotons with the 12C nuclei. The width of the target plays
a crucial role in minimizing these unwanted eects. Two wire-shaped prototypes have been
already realized, starting from a thin diamond disk. The wire shape has been obtained by using
a femto-edge laser. One prototype has been submitted to irradiation by protons of 1.5 MeV and
to simultaneous Back-Scattering control to test the impurity level, the surface 12C density, the
radiation hardness and eventual phase modications during irradiation. Both the prototypes
have been submitted to Micro-Raman spectroscopy in order to scan the carbon phases along
the width. The results show performances which satisfy the experimental requirements.

The $\overline{\text{P}}\text{ANDA}$-experiment will be one of the main
experiments at the upcoming Facility for Antiproton and Ion Research
(FAIR) at the GSI in Darmstadt. The fixed target experiment will explore
$\overline{\text{p}}$p annihilations in the charm mass region with intense,
phase space cooled beams with momenta between 1.5 and 15 GeV/c.

The innermost subdetector of $\overline{\text{P}}\text{ANDA}$ will be
the Micro Vertex Detector (MVD) and consists of silicon strip and pixel
detectors.
The MVD can be further divided into two sub-structures. A
barrel-structure around the vertex and a
disc-structure in beam direction with six disks of different size.
The last two disks are hybrid disks with trapezoidal strip sensors in the outer layer surrounding a smaller
ring of pixel sensors in the inner part. The other disks are made only out of pixel detectors.

The first trapezoidal prototype sensors were produced by
CiS\footnote{Forschungsinstitut f\"ur Mikrosensorik und Photovoltaik GmbH}
and have a stereo angle of $15^{\circ}$ with 512 strips per sensor side
and a strip pitch of $67.5\,\mu\text{m}$.

In order to operate and test the prototype sensors, they were
chracterized with a probestation as well as with a dedicated testboard.
A first beam test was done at COSY\footnote{Cooler Synchrotron at
Forschungszentrum J\"ulich GmbH} with protons of $2.95\,\text{GeV/c}$ and
$800\,\text{MeV/c}$ in December 2013 and January 2014.

Overview of the MVD integration

Instrumentation 2014 - The PANDA experiment will be build at the antiproton storage ring HESR, a part of
the new accelerator facility FAIR in Darmstadt, Germany. PANDA aims amongst others for high
precision measurements in hadron spectroscopy and search for exotic matter. To guarantee the high
resolution of the different components a detector control system (DCS) monitoring temperatures,
humidity, pressure, and controlling chillers and power supplies is needed. The DCS of PANDA is
build using the open-source software package EPICS (Experimental Physics and Industrial Control
System) with a PANDA specific version of Control-System Studio.
In this document the general conecepts of the PANDA DCS will be discussed.

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.

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.

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.

The objectice of this thesis was the construction and investigation of a cluster jet target which meet the requirements of modern storage ring experiments concerning the geometry and the target thickness. At first the cluster jet target MCT1 was built up and commissioned successfully. By optimizing this target a target thickness was achieved at a distance of two meters between the cluster source and the interaction point that was previously only achieved at a third of this distance. Thereafter a second cluster source, the MCT2, was designed, constructed and operated which is the prototype for the cluster jet target of the future experiment PANDA at the accelerator complex FAIR in Darmstadt. With this cluster source a target thickness close to 1015 atoms/cm3 was reached at a distance of 2 m behind the nozzle of the cluster source.
In addition to the construction and operation of the two cluster jet targets the properties of the generated clusters were investigated. In this work the measurement of distribution of the cluster velocity is of particular interest. A quasi-one-dimensional model of the flow through the nozzle using the van der Waals equation of state was established which reproduces the mean cluster velocity with a good accuracy. The comparison between this model and the experimental data lead to important information concerning the cluster production process.