Jobs and Theses

A fully modular 3D-tracking detector with a readout volume of 10×10×10cm³ and an amplification stage based on gaseous electron multipliers (GEM) has been developed and built for various test purposes. A full setup of such a laboratory-size detector (small Time Projection Chamber, sTPC) already has been set up and tested. There exists an additional set of detector parts in order to assemble a second detector of the same type which is supposed to be used for an advanced laboratory course for future physics students.
In the scope of your work one sub-project could be to assemble and test the detector, partly under clean room conditions. Another task is to revise the readout electronics of the detector. Here, the existing readout chain needs to be replaced and adopted to the scope of a laboratory course. This has to be realized in terms of printed circuit board (PCB) design and the description of FPGA firmware. With this, you also have the opportunity to set the course for upgrades planned for the mid-scale Crystal Barrel Experiment (CBELSA/TAPS) in Bonn.
Last but not least, an external detector arrangement – e.g. consisting of scintillators – needs to be implemented around the detector in order to generate a trigger for cosmic particle track events. Measured tracks need to be visualized in the scope of an event display software. The scope of the project can be accommodated to your personal preferences.

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Responsible: Dimitri Schaab

GEMs are widely used as amplification stage in gaseous detectors.
In most cases, not only one GEM is used but a stack of three or four foils.
Optimal settings for the configuration of the GEM stack have not been found.
This includes the type of GEM but also the high voltage settings of the different electrodes.

In order to optimise these settings, microscopic simulations (Garfield++) are used and compared to measurements with test-detectors in the laboratory.

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Responsible: Philip Hauer, Bernhard Ketzer

For the amplification of electron signals in gaseous detectors, amongst others, systems of Gas Electron Multipliers (GEMs) are utilized whose characterization requires a precise measurement of extremely low currents. For this purpose, we use measurement devices that can precisely measure extremely low currents at high voltage applications. Recently, a former picoampere-meter design has been revised in order to vastly improve its temperature dependence and a non-linearity. In the course of the revision, the current measurement circuitry has also been exchanged enhancing the current measurements from ∼1pA down to ∼20fA.
The work for this project comprises the assembly of an amperemeter prototype as well as its commissioning and characterization.

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Responsible: Philip Hauer, Bernhard Ketzer

GEMs are widely used as amplification stage in gaseous detectors.
In most cases, not only one GEM is used but a stack of three or four foils.
In order to supply GEMs with high voltage, a voltage divider is often used.
This approach, however, is not stable at high rates.
In order to overcome this problem, a stabilised voltage divider has been developed.

For this thesis, the prototype has to be tested and calibrated.
Furthermore, simulations of the electric circuit have to be performed.

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Responsible: Philip Hauer, Bernhard Ketzer

We are performing data analysis on diffractive COMPASS data. The first step after a successfull partial-wave analysis is the resonance model fit. Since the PWA is not completely done yet, we give you the chance to investigate resonance model fits on pseudo data and improve on a c++ based program to perform these fits. You will extract resonce model parameters like resonance positions, widths and more.

Responsible: Mathias Wagner, David Spülbeck, Henri Pekeler

Recently, there was a new data production for diffractive COMPASS data. It features an improved description of the calorimeter and much more. We released three eventselections last year, based on the old production and need to verify that nothing drastically changed within the new production. You have the possibility to perform this cross check and contribute significantly to an update of the releases last year. 

You will work with c++ programs, ROOT and write your analysis in the COMPASS framework PHAST.

Responsible: Henri Pekeler, David Spülbeck

In the coming years, the AMBER experiment plans to take data with kaon beams on proton targets. It is essential to investigate the acceptance of the apperatus for any physics program. in the scope of a Master (Bachelor) thesis, we offer you the chance to simulate, with existing Monte Carlo software, the AMBER detectors and study the acceptance of the upcoming kaon physics.

Within this project, you will gain more advanced knowledge in c++ programming, data analysis with ROOT and much more.

Responsible: Martin Hoffmann, Henri Pekeler

During October 2021 we have performed a pilot run of the proton radius measurement⁵.
A first analysis of the main parts has been performed and we have shown the feasibility of the data set. There are still some open studies regarding resolution effects of the spectrometer and the time projection chamber. We search for students, who can help with one of those analyses.

In the scope of a master thesis, the analyses may be compared to simulations. For this an existing framework based on Geant4 will be used.

Responsible: Martin Hoffmann