Actinides in the cosmic rays and their detection

I have made a measurement of the elemental abundance of cosmic rays with atomic number 70 < Z < 83. I made this measurement as part of the Extended Analysis of the Trek detector (Extended-Trek for short). The original Trek detector consisted of 150 stacks, each of 16 sheets, of BP-1 glass exposed on the Russian space station Mir. In the original analysis of Trek 245 cosmic-ray events were analyzed. The cosmic-ray elemental abundance pattern observed by Trek is strongly inconsistent with the prevailing model of cosmic-ray sources. For Extended-Trek I re-analyzed 146 events in the ∼100 stacks which were calibrated with relativistic gold ions at two zenith angles. These correspond to a collecting area of approximately 0.7 m2. The Extended-Trek analysis improved the resolution of cosmic-ray charge to 0.35e over 0.39e--0.45 e in the original Trek analysis and confirmed the cosmic-ray abundance pattern observed by Trek. I have developed a new computer code for the calculation of energy loss of charged particles due to ionization of matter. It is valid for highly charged nuclei and relativistic (gamma ≈ 2) to ultrarelativistic (gamma > 100) energies. In addition to describing the theoretical aspects of the construction of this code, I test its validity both by experiment and comparison to other codes. I have made a new determination of the empirical response function of BP-1 glass to relativistic charged particles. The data strongly suggest that this response function becomes extremely simple at low energies. In addition, I have found a very small relativistic rise in BP-1, which, though it is a clue to track formation, does not impair the performance of present or future BP-1 cosmic-ray detectors. I have made a measurement of the abundance of Ir in the Galactic cosmic rays. This is the first measurement of an odd-Z element in this region of cosmic-ray charge, other odd-Z elements in this region having natural abundances too low to make statistically significant determinations of abundance. The most abundant isotope of Ir experiences bound-state beta-decay in the Galactic cosmic rays. Finally, I give a series of recommendations for next-generation cosmic-ray detectors based on the conclusions reached in this study.