Date of Award

Summer 8-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Advisor

Charles T. Hess

Second Committee Member

George Bernhardt

Third Committee Member

Samuel Hess

Additional Committee Members

Tom Stone

Sean Birkel

Abstract

7Be and 210Pb activities were measured in air sampling filters collected at The University of Maine campus from 2014 to 2019. The activities of 7Be were in the range of 1.178-98.8 Bq, with an average value of 32.13 Bq. The activities of 210Pb were in the range of 0.091 to 13.64 Bq, and an average value of 3.029 Bq. The distributions of activity for both radionuclides are lognormal. Both 7Be and 210Pb show seasonal variation with maximum values in the summer and minimum values in the fall, and the 7Be/210Pb ratio shows a clear seasonal variation with maxima in the spring and summer and minima in the winter. The measured activities of the two radionuclides are correlated (R=0.593, P

These results are compared with a sample of results from the literature, selected for similar latitude, showing consistency with some sampling sites in Europe, notably those with some influence from both oceanic and continental air flows. The likely mechanism for the seasonal variation in both radionuclides is increased atmospheric mixing in the warmer months, although a possible explanation for the variation in 7Be/210Pb ratio is influx of oceanic air at the sampling site during the spring. Further research includes correlating the 7Be data with the 11-year solar cycle and adjusting for its effects, and a more detailed analysis and classification of air flows arriving at the sampling site, and correlation between different air masses (oceanic versus continental, for example) and the measured radionuclide activities.

Additional Files
MAESTRO spectrum files.zip (1503 kB)
Compressed digital archive of raw MAESTRO spectrum files saved in .spe format used in generating the data for the thesis.
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