| Summary: | This thesis project is based on the data analysis and interpretation of Cosmic Ray Induced Ionization (CRII) radiation environment measurements acquired during author-designed experiments “Timepix@Space“ and “CRIndIons“ on BEXUS-7 and on BEXUS-9 stratospheric balloon campaigns resp. In the thesis, results of the first two experiments using the semiconductor pixel detectors of the Medipix family for energetic particle imaging in the stratospheric environment are presented. The original detecting device was based on the hybrid pixel detectors of Medipix-2 and Timepix developed at CERN with USB interface developed at Institute of Experimental and Applied Physics of Czech Technical University in Prague. The detectors were used in tracking mode allowing them to operate as an "active nuclear emulsion". The actual flight time of BEXUS-7 with Medipix-2 on 8th October 2008 was over 4 hours, with 2 hours at stable floating altitude of 26km. BEXUS-9 measurements of 3.5 hour duration by Timepix, Medipix-2 and ST-6 Geiger telescope instruments took place in arctic atmosphere till ceiling altitude of 24km on 11th October 2009. Stratospheric balloon platform is the optimal realization for such in-situ measurements of atmospheric ionization. Optimal not only because of the high altitudes reached, but also due to its slow ascent velocity for statistically relevant sampling of the ambient environment for improving cosmic ray induced ionisation rate model inputs. The flight opportunity for BEXUS student projects was provided by Education department of the European Space Agency (ESA) and Eurolaunch - Collaboration of Swedish National Space Board (SNSB) and German Space Agency (DLR). The scientic goal was to check energetic particle type altitudinal dependencies, simultaneously testing proper detector calibration by detecting fluxes of ionizing radiation while evaluating instrumentation endurance and performance. Extensive dataset of different types of cosmic ray particle image tracks were acquired in the stratospheric radiation ...
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