Optimised Use of Detector Systems for Relativistic Radioactive Beams

Abstract

Ever since the discovery of the atomic nucleus, the exploration and understanding of its properties has been a frontier of physics research. Such investigations are still ongoing at different research facilities around the world. One of these places is the GSI accelerator laboratory where experiments with unstable heavy ions are performed. To obtain high-quality results from the experiments, it is essential that the detectors used are performing at their maximum. Hence it is important to understand the characteristics of the detectors to be able to find and correct errors. In this thesis, the response of two different detector systems in the LAND-setup at GSI is investigated. The first detector system is called the Crystal Ball, a γ-detector, which is also able to detect high-energy protons. The second detector type is used for detecting ions. It consists of a long plastic scintillator which is very common in nuclear physics experiments and is used in several different detector systems in the LAND-setup. For the Crystal Ball an evaluation of different addback routines were performed. An addback routine is a method to recreate the multiplicity and energy of γ-rays and protons hitting the Crystal Ball detectors. This was done based on simulations of different scenarios. For the scintillator, experimental data were used. The motivation to investigate the behaviour of the scintillator is a feature causing the detector to respond differently depending on the position of a hit in the paddle. The origin of this behaviour was found and different methods for correction are suggested and evaluated. The third and last topic of this thesis is a brief analysis of data collected by a detector system constructed to find a relation between energies deposited by cosmic muons and protons in the Crystal Ball. With this relation it is possible to calibrate the Crystal Ball for a range of proton energies, using cosmic muons. The results from the experiment agree with expectations, however to find the relation, a more thorough analysis is needed.