The AWAKE experiment at CERN is a proof-of-principle experiment to demonstrate electron acceleration in a plasma wakefield generated by a proton bunch.  The main diagnostic of the experiment is a streak camera, which provides time resolved images of the proton and electron bunches.  The student will investigate the limits of resolution achievable with the streak camera using Fourier Transform and other techniques.

One of the goals of the Belle II experiment is the study of the CP asymmetries in the

time evolution of the neutral B mesons. A clean laboratory to study the two-state system

of B0 and anti-B0 mesons is provided by the (4S) resonance which can be produced in

e+ e􀀀 annihilation at the center of mass energy of 10.58 GeV. In SuperKEKB, the beam

energies to form the (4S) are chosen asymmetrically in order to translate the decay time

difference into a length: t = l=c, where l is the boost direction. The B0 and anti-B0

produced by the decay of the (4S) cannot oscillate independently before they decay but

are locked in a quantum-entangled state. Thus the identification of one of the B mesons

as a B0 (anti-B0) yields the flavor of the other B meson as anti-B0 (B0) at the same

time. If the anti-B0 (B0) is fully reconstructed to a CP eigenstate, the difference between

the particle and the antiparticle can be studied using the shape of the distribution of

the difference of their decay times. The goal is to determine the experimental resolution

function of the distance (translated to the difference of the decay times) between the

vertices of the two B mesons as a function of the different decay vertex qualities and

vertex detector running conditions.

In proton exchange membrane fuel cells hydrogen is electrochemically oxidized at the negative electrode, while oxygen is reduced at the positive electrode. The oxygen reduction reaction (ORR) is a very sluggish reaction. Therefore rather large overpotentials are associated with this reaction that lower the usable voltage of the cell at a given current and thus the energy conversion efficiency. Large amounts of expensive Pt catalyst are used in commercially available fuel cell vehicles in order to minimize these losses and to increase the power output of the fuel cell. In order to lower the costs and to improve the conversion efficiency, alternative catalysts compared to pure Pt are needed. One extremely attractive group of materials are Pt rare earth alloys [1]. Such alloys have been shown to be several times more active than pure Pt. Also nanoparticles generated in a cluster source have demonstrated very high activities (activity usually is expressed as the oxygen reduction reaction current measured at a certain potential normalized to the total mass of the catalyst in the electrode or to its true surface area) for the oxygen reduction reaction, and do show an excellent stability [2, 3]. However, scalable synthesis methods are required for making these nanoparticles, and this is not that simple as the rare earth elements are very reactive towards moisture and air.

Recently, within two European Projects (see also http://www.inspire-fuelcell.eu/) we have aimed at making Pt-rare earth alloys via electroreduction from ionic liquids [4]. Ionic liquids are basically salts with a melting point below 100°C. Many ionic liquids are even liquid at room temperature. They show a wide electrochemical window permitting the deposition of very reactive metals, have a low vapour pressure and often low toxicity [5]. The electrodeposition of platinum has been successful from some ionic liquids. The electrodeposition of rare earth metal also has been successful from different ionic liquids. First tests on the electrodeposition of Pt in these latter liquids have been carried out.

The task of the current thesis is two-fold: First the electrodeposition of Pt shall be studied in a three component system: Pt chloride salt, an organic chloride as a complexing agent, and the ionic liquid from which the deposition of the rare earth metal was successful. Techniques like the electrochemical quartz crystal microbalance and scanning tunneling microscopy shall be employed to learn more about the electrodeposition mechanisms. The catalytic properties for the ORR shall be determined in aqueous solutions with the rotating disc electrode technique (procedure available). Second, Pt and the rare earth metal shall be deposited in parallel from a mixed electrolyte. The best mixture ratio and the deposition potential need to be chosen carefully to enable alloy deposition and control of its composition.

[1] M. Escudero-Escribano, P. Malacrida, M.H. Hansen, U.G. Vej-Hansen, A. Velázquez-Palenzuela, V. Tripkovic, J. Schiøtz, J. Rossmeisl, I.E.L. Stephens, I. Chorkendorff, Science, 352 (2016) 73-76.

[2] A. Velázquez-Palenzuela, F. Masini, A.F. Pedersen, M. Escudero-Escribano, D. Deiana, P. Malacrida, T.W. Hansen, D. Friebel, A. Nilsson, I.E.L. Stephens, I. Chorkendorff, J. Catal., 328 (2015) 297-307.

[3] P. Hernandez-Fernandez, F. Masini, D.N. McCarthy, C.E. Strebel, D. Friebel, D. Deiana, P. Malacrida, A. Nierhoff, A. Bodin, A.M. Wise, J.H. Nielsen, T.W. Hansen, A. Nilsson, I.E.L. Stephens, I. Chorkendorff, Nat. Chem., 6 (2014) 732–738.

[4] L. Asen, W. Ju, E. Mostafa, S. Martens, U. Heiz, U. Stimming, O. Schneider, ECS Trans., 75 (2016) 323-332.

[5] S. Zein El Abedin, F. Endres, ChemPhysChem, 7 (2006) 58-61.

Zur Verbesserung der Messgenauigkeit des Myonspektrometers des ATLAS-Detektors am Large Hadron Collider (LHC) werden neue hochpraezise Myonspurdetektoren entwickelt, die auf Driftrohren basieren und sehr hohe Untergrundzaehlraten aushalten. Die Eigenschaften dieser Detektoren werden in vorhandenen Testaufbauten und im Teststrahl am CERN systematisch untersucht.

Das R3B – Experiment (Reactions with Relativistic Radioactive Beams) spielt eine herausragende Rolle bei der Untersuchung der starke Wechselwirkung in exotischen Kernen. Ein zentraler Detektor in diesem Projekt ist das, aus mehreren tausend Einzelkristallen bestehende CALIFA Kalorimeter. Das Szintillationslicht aus den bis zu 22 cm langen CsI Kristallen wird mit so genannten Silizium Avalanche Photodioden (APD) ausgelesen bevor die Signale mit einer FPGA basierten digitalen Pulsformanalyse aufbereitet werden. 

Das Kalorimeter wir im Frühjahr 2018 an FAIR in Darmstadt aufgebaut und für die ersten Experimente im Sommer 2018 vorbereitet.  

Im Rahmen einer Bachelor Arbeit soll das digitale Kontrollsystem an unserem Prototyp in München systematisch untersucht und um eine Funktion zur automatische Kalibration erweitert werden. Dabei nutzen wir Hardwarenahe Programmierung auf APU PC-Engines zur Schnittstellenansteuerung, ein PHP Datenbank Interface sowie Dashboards und Widgets um ein übersichtliches „User Interface“ zu erzeugen. Ihre Entwicklungen werden bei einem ersten Experiment mit CALIFA an der Großforschungseinrichtung FAIR im Sommer 2018 genutzt.

McStas neutron ray tracing calculations of the reflectometer REFSANS

A neutron reflectometer can be used to study thin films at interfaces by illuminating the film under a shallow angle with neutrons and counting how many neutrons are reflected specularly. The reflectometer REFSANS at the Heinz Maier-Leibnitz Zentrum (MLZ) is in particular designed to look at the water-air interface. Since this interface cannot be tilted, a complex neutron optic bends the neutron beam onto this horizontal surface in order to realize different shallow angles.

There are currently two separate Monte Carlo McStas simulations of parts of the instrument: The neutron guide from the source to the start of the neutron optics, and the neutron optics itself. The task in this project is to use the output of the neutron guide simulation as input for the neutron optics simulation and to optimize the configuration of the neutron optics in the simulation for bent beams.

The work will be performed together with the German Engineering Materials Science team @ MLZ and offers the unique possibility to work at the MLZ, an internationally leading large scale neutron facility.

Contact: Dr. Sebastian Busch, Sebastian.Busch@hzg.de, 089 289 10764

Prof. Dr. Winfried Petry, winfried.petry@frm2.tum.de, 089 289 14704

A Markov Chain Monte Carlo algorithm (BAT -https://bat.mpp.mpg.de) will be used to study the properties of a neural net model whose properties are defined by analogy to Black Hole physics (arXiv:1711.09079).  The student will investigate the convergence properties and stability of solutions with different algorithms.

When an isolated quantum system is set in motion, what happens? In classical thermodynamics, this problem is exemplified by the irreversible expansion of a gas in an isolated chamber after suddenly doubling the chamber size. Generically, we expect to observe a gradual relaxation to a thermal equilibrium state as the details of the initial state are progressively washed away in collisions. In certain cases, however, strong quantum correlations between the particles can conspire to slow down the relaxation process, resulting in a multi-stage dissolution of the initial information via long detours to intermediate states. In technical terms, these intermediate states are referred to as prethermal states. In this project, we will study signatures of prethermalization in the Bose-Hubbard model using a truncated phase space method.

The fabrication of ReBa2Cu3O7-δ (Re: rare earth element) (ReBCO) high temperature superconductor (HTS) based coated conductors requires the development of buffer layers (intermediate layers between a metal tape and a  superconductor). These buffer layers have to fulfill a list of requirements among which are chemical stability and  compatibility with adjacent films. Inclined substrate deposited MgO, developed by THEVA, is used as incident buffer  layer, because it creates a texture on metal substrate for the growth of HTS film and serves as a diffusion barrier for substrate elements. However, MgO is a hygroscopic material and has a high lattice mismatch with HTS, and therefore creates some technical issues for the consecutive deposition process. LaMnO3 is a perspective candidate as a terminal buffer layer due to its compatibility with MgO surfaces and is expected to provide a good template for growing ReBCO.

Depending on your qualification, following tasks will be performed during your work:
• Optimization of LaMnO3 deposition parameters
• Structural and compositional analysis (XRD, SEM, EDS, ICP)
• Deposition of GdBa2Cu3O7-δ HTS films on LaMnO3 buffered substrates
• Analysis of superconducting properties of the HTS films (Ic, Tc)

The experimental work of the master/bachelor thesis will be performed at THEVA GmbH, Ismaning. THEVA GmbH is an international, medium-sized high-tech company in the area of superconducting technology and special-purpose  systems for vacuum coating technology. For more than two decades THEVA has been developing process technologies for the manufacture of high temperature superconductors for power transmission and power  engineering. In our pilot production facility in Ismaning near Munich, we manufacture and distribute superconductors with a high power density.

Please send your application via e-mail with keywords "LMO bachelor" or "LMO master" to:
THEVA Dünnschichttechnik GmbH
Oleksiy Troshyn
Rote-Kreuz-Str. 8, 85737 Ismaning,
Tel.: 089 923346 0, E-Mail: hr@theva.com

Small-angle neutron scattering (SANS) is a powerful technique to study correlations of condensed matter samples in the range of 20–2000 Å. The new small angle scattering instrument SANS-1 is a joint project of TUM and Helmholtz Zentrum Geestacht (HZG). SANS-1 is located at the end of neutron guide NL4a in the Neutron Guide Hall West of Heinz Maier-Leibnitz Zentrum (MLZ).  SANS-1 is a standard pinhole SANS instrument with both 20 m collimation distance and 20 m sample detector distance, respectively.

For magnetic SANS with polarized neutrons a radio-frequency (RF)-Spin-flipper is required. Recently such a RF flipper has been newly built has to be installed within an air chamber.  This new flipper will undergo different optimization procedures to ensure its performance for the wide wavelength range of SANS-1.  Therefore calculations and measurements will be performed to get optimal results for the final setup.  This task requires both mechanical work, knowledge of electronics and simulations of RF magnetic fields.

The work will be performed together with the SANS-1 team @ MLZ and offers the unique possibility to work at an internationally leading large scale neutron facility like the MLZ.

Contact: Dr. André Heinemann, Andre.Heinemann@hzg.de, 089 289 14534

Prof. Dr. Winfried Petry, winfried.petry@frm2.tum.de, 089 289 14704

Der Large Hadron Collider (LHC) bietet eine einzigartige Gelegenheit nach Teilchen der Dunklen Materie zu suchen. Sie zeichnen sich im Detektor durch sogenannte fehlende Energie aus. Zusaetzlich muss jedoch ein bekanntes Teilchen als Signal erzeugt werden. Dafuer kommt auch das Higgs-Boson in Frage, das an massive Teilchen koppelt. Die Auswahlkriterien fuer solche Ereignisse werden mit Hilfe simulierter Daten optimiert. Die Ergebnisse werden auf die neuesten Daten des ATLAS-Experiments angewendet.

Recent conceptional and technical progress makes it possible to prepare and explore strongly-correlated non-equilibrium quantum states of matter. Such states can be very well controlled in synthetic quantum matter, such as ultracold atoms, trapped ions, or quantum dots. However, theoretically many facets of non-equilibrium states are not well understood. Among them are thermalization in closed quantum systems, dynamic phase transitions, and intertwined order far from equilibrium. In this project we will explore state of the art questions of the field of nonequilibrium quantum dynamics that are also of direct relevance to current experiments.

The main task of the tracking is the reconstruction of charged particles originating from

primary and secondary vertices. Due to the present implementation of the tracking algorithms

it is not possible to use the reconstructed hits of the first layer of the Pixel Vertex

Detector when no hits are available in the second layer, because of the impact of the high

machine background on the first layer. The task is the development of an algorithm for

improving the separation power between the clusters coming from interesting tracks and

the ones coming from the machine background.