Possible Theses at the Time-of-Flight Spectrometer

Setup of the Time-of-Flight spectrometer at Heidelberg Ion Therapy Center 2015 Max Emde

The aim of our group is the measurement of nuclear cross sections which are relevant in radiation therapy with hadrons. With roughly 300 analog signal channels, the ToF spectrometer built for this purpose is a technically ambitious project. Nevertheless, it is operated and constantly upgraded by a small group of two to five students, so there is plenty of work to do in detector construction, simulation and data analysis. As a master student, you will probably have the chance to participate in a beam time carried out in Heidelberg or another ion-beam center.


NIM crate with modules Max Emde Electronics

At the time-of-flight spectrometer, we offer master and bachelor theses on request. Topics include

  • detector development,
  • simulation and
  • electronics.

Most of the theses include parts from more than one of these areas. Specific subjects are presented at the Physics Day.

Detector Development

All detectors of the time-of-flight spectrometer are developed at our institute. They measure the position, time of arrival, specific energy loss and kinetic energy of particles that are relevant in ion therapy. Our detectors usually consist of a scintillator, a photosensor and electronics that are needed to operate the sensor and deliver an electric signal suitable for digitization. Scintillator material, optical properties and sensors as well as their electronics have to be optimized for the variable to be measured. For timing measurements, we use fast plastic scintillators in combination with modern silicon photomultipliers to yield timing resolutions in the order of magnitude of 100ps.


The entire setup of the time-of-flight spectrometer is implemented in Geant4 for Monte-Carlo simulations. Your task can include adapting the simulation the the current physical setup. Also, small stand-alone simulationes can be necessary for single components or laboratory setups. Your simulations will be an important contribution for detector optimizations and understanding of measurement results.

Geant4 is an object-oriented framework written in c++, so you should have some experience in this language when you plan to write a thesis in this topic.


The electronics of the time-if-flight spectrometer consist of commercial parts in NIM and VME modules as well as custom developments. Modular electronics are used mainly for logic circuits and digitization of detector signals. For more specifc tasks like preamplification of sensor signal, custom circuit boards are designed for optimal processing of analog signals in order to measure amounts of light or to measure times. For regulation and control tasks, we often use microprocessors with self-written firmware.

You should have learnt dealing with modular electronics in the lab courses. Basic knowledge in analog circuits and microprocessor programming are taught for instance in the lecture electronics for physicists.


Every thesis in our group involves writing your own programs for data acquistion or data analysis. We use c++ and, increasingly, python. Measurement data is stored in ROOT, so, for simplicity, this is likely used for data analysis as well. To be able to finish a thesis in our group, you need programming skills in at least one of these languages.



Max Emde

ToF Spectrometer


+49 241 80 27327