Open Thesis Topics

The aim of this thesis is to study the sensitivity the new experiment INSIGHT at ELSA will have on the rare η-decay: η → Bγ → π0γγ. If a peak in the corresponding decay Dalitz plot would be observed this would be rather exciting since it may indicate the observation of a dark photon (B) at the corresponding mass.

To determine differential cross sections from the data the efficiencies of the detector systems need to be known. Since the efficiency of a specific detector system may change, it needs to be determined from the actual data taken. The subject of the thesis is to determine the detection efficiency of the scintillators placed in front of the calorimeter crystals from the experimental data taken end of last year.

Although the CB experiment is designed for the measurement of neutral mesons decaying into photons, it is possible to reconstruct a limited number of charged final state particles with the help of a kinematic fit. How well are the mixed-charged decay modes of the η and ω mesons reconstructed with the limited angular resolution for charged particles in the current setup?

For the new INSIGHT-experiment at ELSA an efficient suppression of the dominating electromagnetic rates is of large importance. In the thesis e+e− will be simulated and mixed with existing real data or simulated data based on the rates expected for the INSIGHT-experiment. The aim of the thesis is to find methods to efficiently identify and suppress not only e+e−-events but also e+e− within the hadronic events.

The control of a detector system is an important task. Of course e.g. all high voltages and low voltages must be set to the right values at any time, temperatures need to be controlled, and the well functioning of electronic components (e.g. the HV-adjustment boards of the forward calorimeter) need to be made sure. The aim of the thesis to start by putting existing EPICs control software into operation (existing Docker system) and to implement the control of temperature sensors, HV’s and LV’s. (Programming and Linux skills would be of advantage)

With the CBELSA/TAPS experiment a large data set has been taken using a liquid hydrogen target. This data set will be used to select events of the type γp → pηη, studying a reaction which has on the one hand a quite low cross section but is on the other hand of interest to investigate cascading decays such as N ∗ → N (1535)1/2⁻η → pηη. As in the mesonic sector one might expect exotic hybrid baryons to decay into states with orbital angular momentum in their wave function.

This thesis aims at a momentum dependent study of the neutron interaction in the CsI(Tl) crystals of the Crystal Barrel electromagnetic calorimeter. Based on data taken using a liquid deuterium target and selecting γn(p) → nπ0(p)-events, the shape of the neutron clusters will be studied and compared with simulations

To design the readout and the data acquisition of the new INSIGHT-experiment at ELSA a detailed knowledge of the dominating electromagnetic background rates is necessary. In the thesis the production of electromagnetic background will be simulated and a position- and energy-dependent study will be performed, determining the rates in the different detector systems. First methods to suppress the e⁺e⁻-pairs without deteriorating the efficiency for the detection of hadronic events will be developed.

Crystal Barrel calorimeter will be studied in detail. Depending on the impinging photon energy, electromagnetic showers have different penetration depths and the number of crystals involved in the developing electromagnetic shower also increases with increasing energy. As soon as the photons hitting the calorimeter are not produced in the center of the detector system or the calorimeter crystals are not pointing towards this point, the penetration depth becomes of large importance to determine of the angles involved correctly. This becomes relevant as soon as the primary vertex along an extended target or secondary vertices (e.g. K⁰ → π⁰π⁰ → 4γ) need to be considered in the data analysis. Here, to determine the proper angles and therefore the correct four-vector of a photon, its penetration depth needs to be known. The studies performed in this thesis will be valuable for presently ongoing analyses (γp → K⁰Σ⁺ → π⁰π⁰pπ⁰) as well as for the future INSIGHT experiment at ELSA.

This thesis aims at a detailed investigation of oscilloscope measurements performed in a test-beamtime at the end of 2025. In the E3-ELSA testbeam area electrons have been shot on scintillator bars at different positions. Can the observed pulses be understood in terms of light reflections in the 1.7m long bars?

In this thesis the software to control and monitor the data acquisition of the new INSIGHT-experiment at ELSA is developed. Its tasks include the coordination of the DAQ processes running on different hosts, sending configuration to the front-end electronics, collecting and displaying statistics about data throughput and event rates in the various subdetectors.

Any large-scale experiment such as INSIGHT is built up of numerous subsystems responsible for taking data. Each of these devices records a small puzzle piece of information. Synchronization of these components is vital to assemble the different pieces of information into a full event. Real-time, fixed-latency communication among all detector subsystems is required for this task. The DOGLINK protocol, developed at GSI, could be a promising solution for synchronizing the INSIGHT experiment.
The goal of this thesis is to conduct systematic studies of the synchronization protocol, including the determination of the timing resolution — the precision of the synchronization — and the behavior of the system at scale. To this end, the existing test setup will be expanded, measurement procedures automated, and the resulting data analyzed.

The Crystal Barrel calorimeter is read out using custom Sampling Analog-to-Digital Converter (SADC) boards. To support their operation, a dedicated controller board is required, which is responsible for power management tasks and the distribution of timing and synchronization signals. Such a controller board is currently being developed for the PANDA-SADC which is similar to the CB-SADC. Communication to the data acquisition (DAQ) system should be provided through the CAN-bus interface.
The scope of this thesis is the design and development of a microcontroller-based printed circuit board (PCB) for the controller board, including schematic design, component selection, and PCB layout. In addition, the work comprises the implementation of firmware to monitor system parameters (such as voltages and currents) and communication with the DAQ system.