2014/06/23 by Carl Blaksley, Blaksley, Carl
Physics and Astronomy · #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High Energy Physics - Experiment (hep-ex) #Instrumentation and Detectors (physics.ins-det) #Instrumentation and Methods for Astrophysics (astro-ph.IM) #astro-ph.HE #astro-ph.IM #hep-ex #physics.ins-det
paper · pdf · doi:10.48550/arxiv.1406.5818
Ph.D. Thesis, University Paris Diderot (Paris 7); Defended 19th November, 2013
arxiv created 2014/06/23 · arxiv updated 2014/06/24
In this thesis, an introduction to the Ultra-High Energy Cosmic Ray (UHECR) field is given, including air shower physics, UHECR astrophysics, and experimental techniques. The current questions in UHECR physics are mentioned, along with the experimental challenges encountered in the field. The physics of air fluorescence is also presented, and the JEM-EUSO experiment is introduced in detail. The original contributions in this thesis are divided into experimental work on photodetection aspects of JEM-EUSO and phenomenological studies of UHECR composition and source statistics. A comprehensive introduction to photomultiplier tubes (PMTs) and single photoelectron counting are given, and the measurement of PMT efficiency with an uncertainty of a few percent is discussed in detail. An experimental setup for measuring the air fluorescence yield is also introduced, and tests of the EUSO-Balloon high voltage power supply prototype are presented. A setup for sorting the JEM-EUSO PMTs is developed, including the assembly and calibration of data acquisition hardware and the development of acquisition and analysis software. This system is used to perform an absolute calibration of the EUSO-Balloon focal surface, along with measurements of the PMT pixel width and dead-space. In the phenomenological part of this work, it is shown that a distribution of source maximum energies must be considered in order to understand the energy spectrum and the composition of UHECRs. The number of sources which can be expected to contribute to the UHECR sky is also studied, finding that on the order of 1 source(s) contributes more than 50% of the flux at 100 EeV.