Jobs and Theses

We are constantly looking for talented and motivated students and physicists to join our team, either for your Bachelor's or Master's thesis, as a technical or a PhD student. Sometimes there are also positions for Postdocs. Here is a non-exhaustive list of possible thesis topics. In case you already have your own idea, which fits in our research, do not hesitate to ask! Contact either Prof. Bernhard Ketzer or the contact person listed for the specific research topic.

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Thesis topics

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

In October 2021 we take data for the pilot run of the proton radius measurement5.
There will be several analyses, focusing on subsets of the experiment.
We search for students, who can help with one of those analyses.

If interested, the analysis may be compared to simulations (using an existing framework based on Geant4).

Responsible: Martin Hoffmann

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