Upgrade of ASACUSA's Antihydrogen Detector

• Viktoria Kraxberger

Abstract: The goal of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) experiment at CERN’s Antiproton Decelerator is to measure the difference of the ground state hyperfine splitting of antihydrogen and hydrogen in order to test CPT symmetry. The ASACUSA hodoscope is an octagonal barrel-type detector consisting of plastic scintillators and read out by silicon photo multipliers (SiPMs). If the antiproton of antihydrogen annihilates in the center of the hodoscope, particles (mostly pions) are produced and travel through the various layers of the detector and produce signals. The hodoscope was successfully used during the last data taking period at CERN. The necessary time resolution to discriminate between cosmic particles and annihilation products was previously achieved using waveform digitisers. The disadvantage of this readout scheme with digitisers is the slow readout speed, which was now improved by two orders of magnitude. This was achieved by replacing the wave form digitisers by TDCs reading out a digital time-over-threshold signal produced by the SiPM amplifier boards.

Optimisation of the energy resolution of Low- (LED) and High (HED) Energy Cadmium-Zinc-Telluride (CdZnTe) detectors

• Jasmina Besic

The aim of this master thesis is to investigate and characterise newly developed cadmium-zinc-telluride (CdZnTe) semiconductor detectors as part of the STRONG 2020 project. The work package to which this master thesis belongs is called JRA8-ASTRA (Advanced ultra-fast solid STate detectors for high precision RAdiation spectroscopy). The main goal of ASTRA is to develop advanced radiation detector systems, e.g. two types of solid-state detectors based on CdTe or CdZnTe (CZT) materials, which can perform high-precision measurements of photons in a wide energy range: Low Energy Detection (LED) 10-100 keV and High Energy Detection (HED) 10-1000 keV. The CdZnTe semiconductor detectors are highly sensitive to X-rays and γ-rays in a broad energy range starting at 10 keV and extending up to 1 MeV. Due to the high atomic numbers of the elements used, Cd-48, Zn-30 and Te-52, and the higher energy gap (~1.6 eV) between the valence and conduction bands, CdZnTe detectors have shown good performance when operating at room temperature, good energy resolution and imaging capabilities. Measurements of the different detector configurations will be performed at different temperatures to determine the energy and time resolution.

Beam Loss Monitoring at MedAustron Synchrotron with available Measurement Methods

• Raphael Neugebauer

Abstract: As MedAustron has no active Beam Loss Monitoring System no live information about loss points around the synchrotron are available. The aim of this project is to use available methods to gain better knowledge about the quality and quantity of the radiation fields of the secondary radiation which is produced during the acceleration process. The main challange emerging during the thesis was to process the measurement results such that they are comparable and meaningful conclusions for further projects can be drawn. Detailed knowledge on the secondary radiation fields emerging in the synchrotron hall is required for running efficiency of the facility as well as for preventing from the misplacement of beam diagnostics equipment in case changes in eqiupment are required. The thesis should provide a basis from where further investigations and exclusion procedures can be started.