Bachelor’s Thesis in Physics

The DEAP dark matter detector has been taking physics data for 3 years, searching for interactions between galactic dark matter particles and the argon target material. This unique dataset spanning hundreds of TB offers many opportunities to study liquid argon scintillation physics, optical processes, and background suppression techniques. MSc and BSc topics related to background suppression through pulse shape analysis, Dark Matter signal modelling, and the study of rare coincidences, are available. Students work within an international collaboration of over 100 physicists and might have the opportunity to visit the detector site at SNOLAB in Canada. Students will acquire skills in data analysis and statistics, C++ and/or python programming, Linux/Unix command line operation, Monte Carlo simulation, and in working with large datasets on high performance computing systems. Students have the chance to practice communicating physics results to other students and experts from many different institutions by presenting their work in bi-weekly project-wide analysis phone-conferences.

Our group at the Technische Universität München (TUM) (https://www.denseandstrange.ph.tum.de/) studies the properties of hadronic interactions and their implications for astro-particle physics by means of accelerator experiments. The studies are connected to indirect searches for Dark Matter annihilation or decay products, such as stable Standard Model (anti-)particles in final state: p, anti-p, e+, e-, d, anti-d and others. These searches are currently being performed by several satellite- or balloon-based experiments. In particular, low-energy anti-deuterons are very promising probe for such searches, since cosmic ray-induced background is expected to be low. However, these studies suffer from the lack of our poor current knowledge of inelastic interaction cross-sections of anti-deuterons with matter, which are needed for precise calculation of primary and secondary anti-deuteron fluxes expected near the Earth.

The goal of the here advertised project is to study the inelastic interaction of (anti-)deuterons with matter using the ALICE detector at the CERN LHC. In ultra-relativistic collisions at the LHC, (anti-)deuterons are produced in large amounts, which, together with unique ALICE tracking and PID capabilities, allows one to investigate the inelastic interaction of (anti-)deuterons with the detector material. The idea of the project is to use the ALICE TPC and TOF sub-detectors for (anti-)deuteron identification and the material of the TRD sub-detector located between them as a passive absorption target. As a result, an effective anti-d + A inelastic interaction cross-section can be calculated, where A represents the properties of an averaged TRD material element.

Outline, calculation and design of a purification cryostat to produce isotopically pure He-4 out of natural helium in a continuous manner based on the superfluid heat flush principle.

The FRM II is presently testing and will subsequently install a source to produce ultra-cold neutrons (UCN) in the reactor. In the central section of this UCN source, helium is used for cooling. By passing through, the cooling agent helium will be irradiated by neutrons, which create radioactive tritium out of the He-3 portion. This negative side effect can be avoided respectively reduced to a permissible level if isotopically purified He-4 with no traceable He-3 content is used.

Sources for isotopically pure He-4 are scarce and availability varies with market demand. In order to ensure continuous operation of the UCN source the availability must be secured. For this reason such an isotopic purifier shall be build.

In this thesis a small illustrator shall be build up, and its cool down characteristics shall be measured.

Contact / Supervisor:

Dr. Andreas Frei, Tel. 089 289 14260, andreas.frei@tum.de

Design and setup of an f-2f interferometer for the CEP stabilization of ultrashort laser pulses. By the use of fundamental and non-linear optics, you will design and build an interferometric measurement device.

Im Rahmen des Grundpraktikums Physik am WZW soll ein neues Experiment entwickelt werden. Hierbei sollen Minicomputer mit entsprechenden Sensoren eingesetzt werden. Hierzu sind Vorschläge zu erarbeiten und mindestens an einem Beispielexperiment praktisch umzusetzen. Die Arbeit kann auch als Gruppenarbeit mit bis zu 2 Studierenden bearbeitet werden.

Das Projektlastenheft wird gemeinsam erarbeitet. Das Thema wird in bewertbare einzelne Arbeitspakete aufgeteilt sein.

Kontakt: Rainer Stoepler 089/ 28914272 oder 0162 2944773

rstoepler@tum.de

Pattern formation in cell layers is experimentally studied in both biological and synthetic systems. For instance, in developmental biology, the correct relative positioning of different cell types is essential to ensure that the organism functions correctly. This project will explore some of the underlying physical concepts with a theoretical approach. Whilst many models for pattern formation exist, the focus here is on cellularized systems with interactions only between neighboring cells. This form of communication has previously received less attention from theoretical research than e.g. long-range diffusible signals as a means of communication. Our goal is to explore fundamental limits and patterning concepts with a simple top-down model based on cellular automata. Building on previous work, the project will concentrate on exploring mechanisms of pattern formation with the goal of investigating how cell division and cell death can influence pattern formation in tissues and how tissue regeneration following damage can be achieved. Successful work on this project requires some background in the concepts and methods of statistical physics, as well as skills in computational problem solving.

Hybrid solar cells have promising potential for playing a major role in renewable energy transition. They provide the possibility of flexible and light weighted photovoltaic in a large scale roll-to-roll fabrication, by combining the advantages of organic and inorganic semiconductors. For improved device performance, the morphological structure of the system has a crucial influence. This experimental bachelor thesis aims for a novel approach in templating desired hierarchical structure of the inorganic part, using environmentally friendly, non-toxic biopolymers such as proteins. Thin films of protein/semiconductor composites will be fabricated by spray coating for further structural investigations with the help of scanning electron and atomic force microscopy. Besides the laboratory work, the project also involves a literature review.

Ein vorhandenes Experiment soll charakterisiert und gegebenenfalls verbessert werden.

Das Projektlastenheft wird gemeinsam erarbeitet.

Kontakt: Rainer Stoepler 089/ 28914272 oder 0162 2944773

rstoepler@tum.de

Unlike  normal matter, dark matter  does not interact  with  the electromagnetic  force.
This  means it  does  not absorb, reflect  or emit light, making  it extremely hard to  spot. In
fact, researchers have been able to infer the existence of dark matter
only  from  the gravitational  effect  it  seems  to have  on  visible
matter. Dark  matter seems to  outweigh visible matter roughly  six to
one, making up about 27% of the universe, but  it cannot  be explained
inside  the Standard  model of  particle physics.
A lot of contemporary research goes into the search and characterization
of dark matter candidates. In such framework it is very important to
be able to account for bound states interactions that can modify
dark matter production and annihilation cross sections for some
order of magnitudes.
Scope of the thesis  is to analyze some simple models for nonrelativistic
dark matter bound state effects using nonrelativistic effective field theories
and solving appropriate Schroedinger equations.

Outline, calculation and design of an Ion time-of-flight spectrometer for the time-resolved measurement of different ionization channels in Xe. For this thesis, you will use basic skills of electrostatic, vacuum technology and computer-aided design.

Our group is developing nuclear magnetic resonance imaging scanners, reminiscent of the MRI machines found in hospitals. In contrast to clinical machines our devices can access much smaller samples, down to single molecules. Imaging of these tiny objects requires strong magnetic field gradients, which we typically create by nano-fabricated conductors serving as electro-magnets. 

One important issue in these devices is heating and thermal expansion of the conductors, which degrades the quality of the MRI imaging. So far we have been relying on trial-and-error to assess the impact of this effect. 

Your task will be to put this research on a more solid foundation, by developing numerical models for current and thermal flows in nanoscale conductors. If things work out well, you might also be able to validate the results of your models by measurements on a real chip-scale MRI device. 

The COMPTEL instrument measured the 0.7-30 MeV emission of the sky for nearly 10 years in the 90ies. This energy range includes interesting nuclear lines from elements which are produced in the winds of massive stars, or in supernova explosions. In addition, the instrument is a perfect polarimeter - and X-/gamma-ray polarimetry is still considered the holy grail of astrophysics. Even now, 20 years later, its data are unique, and no future mission is on the horizon for the next 20 years. However, our computational tools have drastically improved, allowing analysis types which were completely impractical at the time COMPTEL was operated.

This thesis shall take our mass model and perform GEANT4 simulations for two cases: (i) line emission from stellar gamma-ray sources, and (ii) polarized continuums emission. Based on the simulated data, new cuts in the multi-dimentional data space should be found which separate background photons from source photons. Finally, these cuts should be applied to a test data set of COMPTEL in order to evaluate the improvement in the performance.

Technically, this thesis involves learning about (i) data analysis of Compton gamma-ray detectors, (ii) understanding detector effects, (iii) simulating an observation with different levels of statistics, and (iv) characterizing a multi-dimentional parameter space using e.g. principal component analysis.

Some background in astrophysics is advantegeous, and experience with GEANT4 would be perfect. Some Python knowledge is required. Joy in data analysis is required.

Contact: Jochen Greiner, jcg@mpe.mpg.de, MPE Room 1.3.13, Tel. 30000-3847

The extreme environment in a fusion plasma reactor, especially the heavy load with hydrogen, leads to various unexpected effects. The Plasma Component Interaction research group at the Max Planck Institute for Plasma Physics (IPP) investigates these effects. One material system of interest is the Fe-W system, which exhibits tungsten enrichment on the surface under hydrogen bombardment. In order to separate the underlying mechanisms and their contribution, well-characterised model samples will be prepared and treated (annealed, ion beam bombarded) and their response to these treatments will be analysed by ion beam analyses and scanning electron microscopy. This thesis should contribute to answering the question: Does ion- and/or hydrogen-enhanced segregation exist in the system Fe-W?

Contact: Dr. Martin Balden

Neutronsterne sind die dichteste Objekte in unserem Universum und  keiner weiss noch was drin ist.

Es  könnte  nur Neutronen geben oder andere Hadronen,  wie  Hyperonen  ( Baryonen mit mindest  einem Strange  quark), oder man  könnte  sogar ein  Quark GLuon Plasma  dadrin finden.

Diese sehr untescheidlichen Szenarios kann man nur testen, wenn man die Wechselwirkungen zwischen den verschiedenen Konstituenten bestimmt. Wechselwirkungen zwischen  Hyperonen sind bisher nicht genau bekannt und das Themas diese Arbeit ist die Untersuchung der Korrelationen zwischen Lambda und Xi HYperonen.

Es werden Daten benutzt, die von mit dem ALICE Detektor am LHC aufgenommen worden sind und die Aufgabe besteht eine neue Analyse zu entwickeln, die uns erlauben wird verschiedene theoretische Vorhersage zu testen.

 Die Analyse wird in C++ geschrieben und es werden auch Simulationen durchgeführt werden.

Eine Vorkenntis in C++ is willkommen aber nicht notwendig. Experte im Bereiche der Analyse und Simulationen werden die direkte Betreuung der Arbeit übernehmen.

Die Kandidatin/ der kandidat werden die Möglichkeit haben, in Kontakt mit der internationalen ALICE COllaboration am CERN zu kommen.

Next step fusion devices, such as the currently built major experiment ITER in France, will face a new challenge by exhausting the generated alpha-particle fusion power through the so called diverter target tiles. Two of the key parameters to characterise this divertor heat load in improved confinement modes are the inter-ELM decay length and the ELM induced energy fluency. The heating method of today’s devices and the burning plasma in ITER are different in many respects. For this reason it is envisaged to characterise the two key quantities with different heating mixes in ASDEX Upgrade to investigate to which extent the heating method by itself causes variations. Corresponding discharges are executed in ASDEX Upgrade already, optimised for this kind of analysis, and shall be analysed using infra red measurements.

Contact: Dr. Thomas Eich

de">Dr. Thomas Eich

Für eine Helium Kälteanlage soll ein Reiniger ausgelegt, gebaut und getestet werden.

Das Projektlastenheft wird gemeinsam erarbeitet.

Kontakt: Rainer Stoepler 089/ 28914272 oder 0162 2944773

rstoepler@tum.de

Porennetzwerk in porösen Medien sind integraler Baustein von Reaktionszellen, die den Kern für Photokatalyse, Gassensorik und Lithium-Ionen-Batterien in Brennstoffzellen bilden. Der Transport durch ungeordneten porösen Medien wird durch die exponentielle Verteilung von Strömungsgeschwindigkeiten grundlegend eingeschränkt, da in großen Bereichen nur geringe Strömungsgeschwindigkeit vorliegt. Mit dem Ziel gezielt Strömung durch poröse Medien zu verbessern soll hier ein geometrisches Mass für die  Unordnung in porösen Medien gefunden werden. Dazu werden Sie laminier Strömungen in porösen Medien mit einfachen Matlab Programmen simulieren und quantifizieren, wie sich Änderungen im Porennetzwerk auf Strömungen auswirken. Einfache analytische Modelle zu Strömungen in Porennetzwerken werden Ihnen dabei helfen ein Mass für die Unordnung in porösen Medien zu finden.

Pore networks in porous media are integral components of reaction cells, which form the core for photocatalysis, gas sensor technology and lithium-ion batteries in fuel cells. The transport through disordered porous media is fundamentally restricted by the exponential distribution of flow velocities, since only low flow velocity is present in large areas. With the aim of improving the flow through porous media, a geometric measure for the disorder in porous media is to be found here. For this purpose you will simulate laminated flows in porous media with simple Matlab programs and quantify how changes in the pore network affect flows. Simple analytical models of flows in pore networks will help you to find a measure for the disorder in porous media.

Pattern formation in cell layers is experimentally studied in both biological and synthetic systems. For instance, in developmental biology, the correct relative positioning of different cell types is essential to ensure that the organism functions correctly. This project will explore some of the underlying physical concepts with a theoretical approach. Whilst many models for pattern formation exist, the focus here is on cellularized systems with interactions only between neighboring cells. This form of communication has previously received less attention from theoretical research than e.g. long-range diffusible signals as a means of communication. Our goal is to explore fundamental limits and patterning concepts with a simple top-down model based on cellular automata. Building on previous work, the project will concentrate on investigating how the interaction range between cells can influence the ability to realiably create typical biological patterns such as a heterogeneous stripe-pattern. Successful work on this project requires some background in the concepts and methods of statistical physics, as well as skills in computational problem solving.

Heavy quarkonia, namely  bound states of a heavy  quark and antiquark,
turn out to be useful systems to  probe the Quark Gluon Plasma (QGP)
the new state of matter originated in heavy ion collision at the LHC
at CERN and at RHIC at BNL. In particular the hot state of  matter can
induce thermal  modifications to  the quarkonium
states.  Experimentally  we  can  see   such  effects  either  in  the
quarkonium suppression  or in  changes in  the bound  state properties
(masses and widths). From a theoretical point of view, effective field
theories give  us the possibility to  study in detail what  happens to
heavy quarkonia  in this extremely  hot state  of matter. The  goal of
this thesis is to obtain  efficient numerical solutions to some
Langevin equations for the quarkonium density  obtained from the
corresponding field theoretical master equation in the classical limit.

The Backbone of state of the art ultrafast metrology measurements is the high-harmonic-generation (HHG).

This process is driven by a few-cycle laser pulse being focused into a gas. In doing so, several harmonic orders

of the used light are generated and can thus be used for a variety of experiments. The maximum (aka. Cut-off)

energy reachable via this process depends on a variety of factors, e.g. the used gas or the chosen focussing.

The main part of the work will be the investigation of these factors in order to reach a higher Cut-off.

In many dark matter models with a heavy dark matter particle and a light
mediator, the so-called Sommerfeld enhancement plays an important role. In
some cases, this non-relativistic effect can modify annihilation cross-
sections by orders of magnitude. Furthermore, zero-energy resonances
associated with bound states are observed for special values of the dark
matter mass. In the vicinity of these resonances, partial-wave unitarity
fails and a special treatment is necessary.

In this thesis, the student will become familiar with the basic theoretical
formalism to calculate the Sommerfeld enhancement and learn how to restore
partial-wave unitarity around the resonances in a self-consistent way. As
part of the project, the student shall write a small code computing the
Sommerfeld enhancement by solving a Schroedinger equation, investigate the
various parametric dependencies and compare the numerical results to known
(semi)-analytic results for several potentials.

The major component of conventional paper are cellulose fibers. With cellulose nanocrystals or microfibrils the manufacturing of thin transparent layers is possible. These layers serve as sustainable substrates in flexible applications. We aim for functional films which reversibly change the color with irradiation of UV-light. Composite films of cellulose and inorganic nanoparticles will be prepared by advanced deposition methods including spray deposition and slot die coating. The project will involve a literature review, sample preparation, x-ray diffraction studies and UVvis spectroscopy.

Nicht-polare Moleküle zeigen in Wasser eine Tendenz zur Assoziation, die über die direkte Anziehung wie sie in Abwesenheit des umgebenden Lösungsmittels auftreten würde, hinausgeht. Dieser (Wasser-vermittelte) hydrophobe Effekt ist die treibende Kraft für eine Vielzahl an Strukturbildungs-prozessen und Assoziationsvorgängen von Biomolekülen. Einige Aspekte des hydrophoben Effekts sind auf molekularer Ebene noch nicht genau verstanden. Entscheidend für den hydrophoben Effekt ist die Ausbildung von Wasserstoffbrücken zwischen den Wassermolekülen, die ein nicht-polares Molekül umgeben. In Computersimulationen kann man die Polarität von Wasser (und damit die Ausbildung von Wasserstoffbrücken) steuern. Die Solvatisierungseigenschaften  von gelösten nicht-polaren Molekülen sollen in Abhängigkeit von der Polarität des umgebenden Wassers durch Simulationsstudien untersucht werden und neue Erkenntnisse zum Verständnis des hydrophoben Effekts gewonnen werden. Die Arbeit erfordert Interesse an statistischer Mechanik und der Verwendung von Simulationsmethoden am Computer.

Perovskite solar cells have dramatically progressed within the last 2 years. Meanwhile championship perovskite solar cells have demonstrated efficiencies above 25%. The general intent of this work is to optimize printed perovskite thin-films for high-quality photovoltaic devices. This will include material and solution preparation, optimizing the printing process and analysis of printed films and/or devices. Analytical methods will focus on film morphology, spectroscopic material properties, crystal structure analysis and current-voltage measurements of self-built solar cells. The thesis also includes a brief literature review.

Amphiphilic block copolymers having a permanently hydrophobic block and a thermo-responsive block form nanoparticles, or rather core-shell micelles, in aqueous solution. The structure of these micelles is controllable by changing the temperature or the ratio between the hydrophobic and the hydrophilic block. These properties enable amphiphilic block copolymers as candidates for a wide variety of applications, such as drug delivery. The main goal of this thesis is to investigate above which polymer concentration micelles form and to characterize the size of the micelles by fluorescence correlation spectroscopy.  For more information, please contact Prof. Christine Papadakis, papadakis@tum.de.

Poly(2-ethyl-2-oxazoline) (PEtOx) in aqueous solution is a responsive polymer which suddenly dehydrates, becomes water-insoluble and collapses, when the sample is heated through the lower critical solution temperature (LCST). We investigate molecular brushes, in which PEtOx chains are densely-grafted on a polymer backbone. The compact architecture has an influence on the dehydration and collapse behavior, and the entire brush changes structure when the side chains collapse.

In the suggested bachelor project, the influence of the architecture on the collapse behavior shall be investigated using Fourier-transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS). After a literature research, samples will be prepared and measured, and data analysis will be carried out. For more information, please contact Prof. Christine Papadakis, papadakis@tum.de.

Das Aussehen einer Pflanze re-organisiert sich selbst unaufhörlich währen ihres Wachstums. Hier ist insbesondere die Spitze des Pflanzenstengels wichtig, dessen Zellen sich unaufhörlich teilen, da alles Blätter und Blüten aus ihm hervorgehen. Wie ist es möglich, dass trotz der kontinuierlichen Wachstums, die Spitze des Pflanzenstengels immer die gleiche Form behält? Hier wird das Wachstum des Pflanzenstengels in C++/Python Code simuliert und visualisiert. Zellteilungsraten werden zunächst so codiert, dass sie der biologischen, räumlichen Anordnung mit ansteigender Teilungsrate von der Stengelspitze hinweg folgen. Es wird dann allgemein untersucht unter welchen räumlichen Zellteilungsmustern der Pflanzenstengel die Form behält.

The appearance of a plant re-organizes itself continuously during its growth. The tip of the plant stem is particularly important here. Its cells divide continuously, as all leaves and flowers originate from it. How is it possible that despite the continuous growth, the tip of the stem always keeps the same shape? Here the growth of the plant stem is simulated and visualized in C++/Python code. Cell division rates are initially coded to follow the biological, spatial arrangement with increasing division rate from the tip of the stem. It is then generally investigated under which spatial cell division patterns the plant stem keeps its shape.

Protein-DNA-Bindung ist ein wichtiger Prozess bei der Genregulierung und für die Verpackung von DNA auf engem Raum in einer Zelle. Die Bindung wird dabei durch die Moleküloberfläche der Partner bestimmt.  Mit Hilfe von Moleküldynamiksimulationen am Computer soll die freie Energie der Bindung von Proteinmolekülen and DNA berechnet werden.  Dazu werden die Proteine während der Simulation voneinander entfernt und die dazu erforderliche Kraft bzw. Arbeit (=freie Energie) wird berechnet. Es sollen Simulationsstudien zur spezifischen (hoch-affinen) Proteinbindung mit Studien zur nicht-spezifischen (niedrig-affinen) Bindung verglichen werden.  Die Simulationen erlauben die Analyse der auftretenden molekularen Kräfte und Energiebeiträge zur Bindung.

Smart hydrogel thin films react with significant changes in their properties towards an altered external stimulus such as temperature, relative humidity or light. This flexible behavior can be exploited as nano-sensors, or artificial pumps and muscles in the field of soft-robotics. Due to the thinness of such materials (~50 – 150 nm), response times are strongly decreased. Mesoscopic parameters such as film thickness and water content upon a changing stimulus are probed with neutron scattering techniques, while polymer – water interactions are followed with Fourier-transform infrared spectroscopy.

Magnetic Weyl semi-metals combine magnetic order and a topological electronic band structure. It is expected that mutual spin-to-charge conversion is particularly efficient in these materials. We will study mutual spin-to-charge conversion using methods of ferromagnetic resonance.

Das COMPASS-Experiment am CERN zeichnet für Reaktionen hochenergetischer Teilchenstrahlen große Mengen komplexer Daten auf. Um den physikalischen Inhalt genau zu verstehen, ist sorgfältige Datenanalyse notwendig, die ein genaues Verständnis des Detektors voraussetzt, das teilweise aus den Daten selbst gewonnen wird. Durch Verfeinerung der Kalibration der Detektorsignale unter Ausnutzung von Korrelationen ziwschen verschiedenen Detektorbereichen lässt sich die Präzision erheblich steigern.

Die Arbeit setzt Programmierkenntnisse (z.B. C++), bzw. zumindest großes Interesse daran voraus.

The improvements of Silicon photo-multipliers (SiPM) over the last years qualify them as promising replacements for classical photo-multiplier tubes (PMT). This is particularly interesting for cases where the high voltages and large dimensions of PMTs are difficult to afford, such as for space applications. For the simplest version of gamma-ray detectors, a scintillator crystal read out by SiPMs, the size of the scintillator determines the sensitivity, and thus should stay large. This suggests an Anger camera principle as the most efficient way for a gamma-ray detector in space: a mosaic of sparsely distributed single-cell SiPMs instead of the coverage of the full scintillator area.

This Master thesis shall test and optimize a 5x5 cm^2 sized CeBr3 scintillator read out with a mosaic of SiPMs. Measurements of the spatial and spectral resolution as well as efficiency (noise) and power consumption are foreseen, and form the basic parameters for the trade-off study. The set-up has two potential applications: (i) in the ComPol Cubesat mission pursued within the Origins Cluster of Excellence, and (ii) the POLAR-2 gamma-ray burst polarisation mission developed within the SFB "Neutrinos and Dark Matter".

Interest in electronics and ASIC readout is required, and some background in astrophysics is advantegeous. The lab-work will be done at MPP Freimann, shared with Prof. S. Mertens group.
 
Contact: Jochen Greiner, jcg@mpe.mpg.de, MPE Room 1.3.13, Tel. 30000-3847

Thermoresponsive block copolymer thin films can be applied in vapor sensors detecting water and organic cosolvents. As sensitive layers, they exhibit characteristic swelling kinetics steered by cosolvent mediated effective interactions between individual polymer chains. This bachelor thesis will cover the fundamentals of responsive polymers and the cononsolvency effect. The experimental part revolves around thin film preparation and swelling behavior analysis in our vapor chamber. The project will include a brief literature review.

PEN ist ein industriell hergestelltes Plastikmaterial, das das Interesse als Szintillator für Experimente der Teilchenphysik auf sich gezogen hat. PEN szintilliert im blauen Regime, ideal für viele Photosensoren. Zusätzlich hat PEN exzellente mechanische Eigenschaften. Ausserdem konnte eine sehr extrem niedrige Belastung surch natürliche Radiositope nachgewiesen werden. Dies macht PEN als strukturelles, szintillierendes Material für Experimente zur Suche nach extrem seltenen Ereignissen interessant. In diesem Zusammenhang wurden PEN Platten für das LEGEND200 Experiment zur Suche nach neutrinolosem Doppelbetazerfall hergestellt. Im Rahmen dieser Arbeit sollen die optischen Eigenschaften diser Platten vermessen werden. Es sollen verschiedene PEN Samples mit einem existierenden Messaufbau auf Emissions- und Absorbtionsspektrum, sowie Lichtausbeute und Attenuierungslänge untersucht werden.

PEN is an industrial plastic that  has drawn the interest as a new type of plastic scintillator material. PEN scintillates in the blue regime, which is ideal for most photosensor devices. In addition, PEN has excellent mechanical properties and very good radiopurity has been achieved, which makes it an ideal candidate as an active structural scintillator material in low-background physics experiments. In this context, PEN plates have been produced for use in the LEGEND200 experiment for the search of neutrinoless double beta decay. The goal of this thesis will be the measurement of the main optical properties of PEN. The emission and absorption spectrum, attenuation length, and light output will be measured for several PEN samples using existing setups.

The combination of quantum mechanical calculations and machine-learning techniques has led to massive advances in the high-throughput computational screening of materials and molecules. Here, it is frequently stated that training data obtained from quantum mechanical simulations (e.g. using density functional theory) is 'noise-free', because the calculations can be numerically converged to very high precision. However, this assumes that the self-consistent algorithm used to calculate the Kohn-Sham determinant always converges to the correct ground-state solution, which is by no means guaranteed. The goal of this project is to quantify the noise introduced into DFT data by different choices of intital guess and convergence acceleration. To this end, the true ground-state solutions for a representative set of molecules will be determined using wavefunction stability analysis. This benchmark will allow the development of an effective 'black-box' method for obtaining well-converged training data. Furthermore, the effect of noise on quantum mechanical machine-learning applications will be studied.

The candidate should be interested learning the fundamentals of density functional theory and supervised machine learning. The project will require the development of automated workflows for high-throughput electronic structure calculations and data analysis. Experience with a scripting language (e.g. Python) and UNIX operating systems is advantageous but not mandatory.

Questions about the project can be directed to johannes.margraf@ch.tum.de.

Amphiphilic block copolymers having a permanently hydrophobic block and a responsive block form core-shell micelles in aqueous solution. The structure of these micelles is controllable by changing the temperature or pH value. These properties enable amphiphilic block copolymers as candidates for a wide variety of applications, such as drug delivery. The main goal of this thesis is to investigate the effect of the pH value on the transition temperature and the micellar size. At this, differential scanning calorimetry (DSC) and dynamic light scattering will be used. For more information, please contact Prof. Christine Papadakis, papadakis@tum.de.