Cully, ChristopherPatrick, Matthew Ryan2022-10-062022-10-062022-08-05Patrick, M. R. (2022). Measuring energetic electron precipitation using high altitude balloons and X-ray (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/115352https://dx.doi.org/10.11575/PRISM/40352This work develops experimental methods to infer the energy spectra and total fluxes of energetic electron precipitation using X-ray spectrum measurements from high altitude balloons. The problem of mapping between the energies and fluxes of secondary X-ray radiation and the causative precipitating electron spectrum is addressed using Monte-Carlo simulations and computer models of the detectors. The inverse problem of determining the electron spectrum from X-ray measurements is solved from first principles by treating the underlying ill-conditioning using regularization and preconditioning methods. Validation of the technique using simulations of the precipitating electrons and detector demonstrates that the inverse problem is solvable for realistic experimental noise levels in the measured X-ray spectra. The problem of over-fitting models to the available data is solved using cross-validation techniques, which models precipitating electron spectra without assumptions about the amount of information that can be reliably determined from experimental measurements. X-ray spectrometer measurements from two University of Calgary high altitude balloon flights and a NASA BARREL balloon flight are analyzed using the developed methods. The resulting electron spectra are compared with the electron spectra obtained using conventional fitting techniques to show that exponential or mono-energetic models can under-fit the available data, which is problematic. A comparison between the BARREL balloon data and a RBSP (Radiation Belt Storm Probe) spacecraft measurement of the electron spectrum prior to scattering shows that the approximate energy range over which the applicable scattering processes in the radiation belts operate can be determined using only the balloon data. The average electron flux measured from the balloon is shown to be consistent with the RBSP measurements. Data from an X-ray detector flown aboard a University of Calgary high altitude balloon are used to derive a precipitating electron flux of $4.8\times10^8\mbox{ electrons}/\mbox{cm}^2/\mbox{second}$. Data from a NASA BARREL balloon flight and associated RBSP measurements are used to show an available precipitating flux of $8.4\times10^6\mbox{ electrons}/\mbox{cm}^2/\mbox{second}$, with $5.2\times10^6\mbox{ electrons}/\mbox{cm}^2/\mbox{second}$ actually precipitating based on the balloon data. The precipitation is consistent with strong scattering in the energy range of 75 to 275 keV.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.xray spectroscopyelectron precipitationhigh altitude balloonPhysicsdoctoral thesis