Investigation of the response of a CALIFA demonstrator and development of an APD test stand

The R3B experiment is a part of the future FAIR project at GSI. It will be used to study reactions with relativistic radioactive beams (R3B). The setup will be placed in the high-energy branch of the Super-FRS. It aims to cover various physics programs. The CALIFA is a spectrometer and a calorimeter. It will surround the central target and detect high-energetic gamma-rays and light charged particles. The CALIFA group made a DEMONSTRATOR to do a systematic study before a mounting together a complete detection system. It is a first step of the set-up and has been used at the first experiment in CAVE C of GSI. The main parts of the DEMONSTRATOR are called PETAL, which is a group of 64 crystals in a holding carbon fiber structure. For the first part of this thesis, I have tested a PETAL in the laboratory of the institute of nuclear physics (IKP), TU Darmstadt and also gone over the analysis framework (R3BRoot) by comparing the results of previous studies and my simulation. The basic properties of the detection unit, the event reconstruction and particle identification have been checked. In addition, the measurement programs have been simulated to be compared to the data. R3BRoot, which is an analysis and simulation toolkit of the R3B experiment, was used. Several measurements were done, for which different sources were used: an AmBe source (gamma-rays, fast neutrons), thermalized neutrons (high-energy gamma-rays via capture process) and muons from cosmic-rays. The second part of this thesis is devoted to the development of a quality assurance test stand for the CALIFA APDs. A part of CALIFA employs CsI(Tl) crystals coupled with APDs as a detection unit. Every single APD has to be tested before it is assembled with the CsI(Tl) crystal. I have designed and tested the Q.A. test stand for the APDs. The main idea of the test stand is to provide controlled conditions and a testing signal for the APDs and to measure the variance of the output. As a result, it will provide information to characterize the individual units. This data will be used to compensate temperature-related gain shifts during the measurement