We congratulate Dr. Sebastian Stengel on the successful completion of his dissertation entitled “Design and Development of the MAGIX Trigger Veto System“

In his dissertation, Sebastian Stengel developed, realized and tested a central detector system for the MAGIX experiment at the new electron accelerator MESA in Mainz.

The versatile MAGIX experiment is designed for high-precision investigations in nuclear and hadron physics, but also opens up the possibility of searching for so-called dark photons – hypothetical particles that are closely linked to theories of dark matter. The detection of scattered particles is essentially carried out using two high-resolution magnetic spectrometers.

The work focused on the so-called trigger-veto system of these spectrometers. It provides a fast and reliable trigger decision for data acquisition, captures time coincidences and provides crucial information for particle identification. In addition, it serves as a time reference for the readout of the spectrometer track detectors.

The system consists of a segmented trigger layer of plastic scintillators, which is read out with photomultipliers, and a flexible veto system consisting of additional scintillator layers with silicon photomultipliers and lead layers to suppress background signals. The readout is carried out via fast, rate-stable FPGA-based electronics.

In the course of the work, all components of the system were designed, selected, tested and systematically optimized – including the mechanical design for integration into the spectrometers. Both extensive simulations with Geant4 and comprehensive system tests under realistic experimental conditions were used.
With a beam time at the MAMI accelerator, the trigger system achieved a remarkable detection efficiency of 99.93%, a time resolution of around 180 ps (FWHM) and a spatial resolution of around 25 mm – significantly exceeding the original requirements. This system is now fully operational for the upcoming operation at MAGIX.

The dissertation was written as part of the MAGIX collaboration under the supervision of Prof. Achim Denig and impressively documents Sebastian Stengel’s contribution to the preparation of one of the central experiments at the MESA accelerator.

This work is an outstanding example of comprehensive modern experimental detector development – from the concept phase to the successful realization of a complex and powerful detector system.