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Platinum and beyond: studies of ultra-heavy nuclei in the galactic cosmic rays

Donnelly, Justin (2004) Platinum and beyond: studies of ultra-heavy nuclei in the galactic cosmic rays. PhD thesis, Dublin City University.

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Abstract

The DIAS-ESTEC Ultra-Heavy Cosmic Ray Experiment (UHCRE) flew on board the Long Duration Exposure Facility (LDEF) spacecraft in low earth orbit for 69 months. The experiment consisted of a large number (~2 0 0 ) of solid-state nuclear track detector stacks and its objective was to determine the charge abundance spectrum o f ultra-heavy (Z >70) galactic cosmic rays at energies of a few GeV/nucleon. Many hundreds of such ultra-heavy cosmic rays were detected, including 35 actinides (Z > 8 8 ), making this the largest sample of such data to date. An overview of our current knowledge of the ultra-heavy cosmic-ray flux is presented in Chapter 1. Charge, energy and isotopic spectra are examined and the clues they present to cosmic-ray origin discussed. Current theories of fractionation of the cosmic-ray source matter during transport and suggested sources o f such matter are outlined. The possible insights provided by ultra-heavy cosmicray measurements are then suggested. Chapter 2 discusses the configuration o f the UHCRE and the LDEF spacecraft. Solid-state nuclear track detectors, detector processing and data extraction are discussed. Chapter 3 contains information on detector calibration and error analysis and discusses a Monte-Carlo simulation o f the apparatus used to corroborate the error estimates. Chapter 4 describes the corrections performed on the raw data for detector bias, detector-processing anomalies and fragmentation within the apparatus. The final charge-abundance spectra are presented. Chapter 5 outlines the conclusions which can be drawn from the data, comparing the results with theoretical predictions and other spacebased observations. The experiment’s impact on theories o f the origin of the cosmic rays is discussed.

Item Type:Thesis (PhD)
Date of Award:2004
Refereed:No
Supervisor(s):Kennedy, Eugene T.
Uncontrolled Keywords:cosmic rays; ultra-heavy cosmic-ray flux
Subjects:Physical Sciences > Astronomy
Physical Sciences > Astronomy > Astrophysics
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Physical Sciences
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:17307
Deposited On:24 Oct 2012 16:09 by Fran Callaghan. Last Modified 09 Oct 2013 13:00

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