Doctoral Dissertations

Abstract

Detector deadtime limits radiation measurement accuracy at high count rates, yet current methods rely on idealized paralyzable or non-paralyzable models. Real detectors exhibit hybrid behavior requiring advanced characterization approaches. This study explores deadtime characterization using two Monte Carlo simulation approaches: higher-order statistical analysis of inter-arrival times and simplified deadtime correction with hybrid models.

Using MATLAB (PULSE-WIZ), we analyzed full decay curves spanning ~4.5 half-lives of Cobalt-60 and Vanadium-52, examining coefficient of variation (CV), skewness, and kurtosis of inter-arrival times, plus normalized decay curves with Full Width at Half Maximum (FWHM) analysis. Hybrid models incorporated paralyzable and non-paralyzable components with dead times of 2.5–50 microseconds and paralysis factors of 0.1–0.99.

Results showed distinct sensitivity patterns among statistical measures. CV demonstrated strong correlation with paralysis factor via exponential relationship (PF = 0.0015e^(12.657×CV), R² = 0.9998), enabling direct paralysis factor determination. Normalized FWHM also showed high correlation (R² = 0.9878). Using FWHM-based paralysis factors and statistics, deadtime was predicted within 11–12% accuracy.

These techniques enable hybrid detector parameter determination using lab-accessible count rates. This work shows that higher-order statistical and decay curve analyses contain valuable diagnostic information typically discarded in conventional counting, enabling automated detector real-time performance assessment.

Advisor(s)

Usman, Shoaib

Committee Member(s)

Alajo, Ayodeji Babatunde
Castano Giraldo, Carlos Henry
Smith, Joseph D.
Al-Dahhan, Muthanna H.

Department(s)

Nuclear Engineering and Radiation Science

Degree Name

Ph. D. in Nuclear Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2025

Journal article titles appearing in thesis/dissertation

Paper I, found on pages 3–17, has been published in the proceedings of American Nuclear Society (ANS) Conference in Chicago IL, in June 2025.

Paper II, found on pages 18–41, has been submitted to Nuclear Technology journal.

Paper III, found on pages 42–71, has been submitted to Progress in Nuclear Energy Journal.

Pagination

xi, 74 pages

Rights

© 2025 Abdallah Wazzan , All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12552

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