Detection Limits of NaI Scintillator Detector Based Aerial Source Detection Systems

TL;DR

This paper evaluates the detection limits of NaI scintillator-based aerial radiation detection systems, analyzing how factors like altitude and relative speed affect their sensitivity for nuclear material detection.

Contribution

It provides a quantitative analysis of the minimum detectable activity (MDA) for NaI detectors as a function of distance, speed, and altitude, including case studies for specific nuclear materials.

Findings

MDA increases exponentially with vehicle height.

MDA increases with relative speed, proportional to speed plus its square root.

Detection limits vary for different nuclear isotopes.

Abstract

Aerial source detection systems have the capability to rapidly provide radiological data over a large area of land. Sodium Iodine (NaI) scintillator based aerial radiation detection systems of compact physical sizes have the potential aid nuclear security applications in a cost-effective manner when deployed on aerial vehicle systems. The Minimum Detectable Activity (MDA) of NaI scintillator airborne detectors is qualitatively evaluated as a function of detector-source distance and as a function of detector-source relative speed. It is found that the MDA increases exponentially with vehicle height and that MDA increases directly proportionally with the relative speed plus the square root of the relative speed. Furthermore, detection limits of an aerial detection system are evaluated in a case study. MDA is evaluated for the nuclear materials U-238 and Pu-239 as defined by the IAEA Safeguards Glossary Table II and MDA is evaluated for arbitrarily selected isotopes found in Table I.2 of the IAEA document TECDOC-1344.