Whole body personnel monitoring via ionization detection

J.E Koster,P.A Steadman,C.R Whitley,J.A Bounds,P.L Kerr

doi:10.1109/23.682691

J.E Koster, P.A Steadman + Show 3 more

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https://doi.org/10.1109/23.682691

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Abstract

A project between Fernald EMP and LANL is to field a monitor for the detection of alpha-emitting contamination on a human body. Traditional personnel monitoring for alpha emitters involves either frisking with a probe or pressing against large detectors in order to overcome the short range of alpha particles. These methods have a low alpha collection efficiency, and can miss contamination on less accessible surfaces. We have investigated the sensitivity and practicality of measuring the entire subject simultaneously using the technique of ionization monitoring. The goal is to create a booth that personnel step into quickly during egress from radiological facilities. The detection technique relies on a breeze of air passing over the subject. Alpha emission produces copious ions in the ambient air which are transported by the air current to an ion collector, resulting in a small electrical current proportional to the amount of contamination. Results indicate a conservative sensitivity of 3000 disintegrations per minute localized to one of five areas of the body in a measurement lasting less than 2 minutes.

Highlights

Alpha emission produces copious ions in the ambient air which are transported by the air current to an ion collector, resulting in a small electrical current proportional to the amount o f contamination
Results indicate a conservative sensitivity of 3000 disintegrations per minute ionization quickly attaches to a neutral air molecule creating equal numbers of positive and negative ions
This paper presents the use of ionization monitoring to only some fraction of the 140,000 ion pairs must detect the presence of actinides on the body in a sensitive, reach the Long-Range Alpha Detection (LRAD)-based ionization monitor in order to register simultaneous measurement

Summary

11. MONITORCONSTRUCTION

LANL is to field a monitor for the detection o f alpha-emitting contamination on a human body. Traditional personnel monitoring for alpha emitters involves either frisking with a probe or Radioisotopes can be detected via the ionization produced pressing against large detectors in order t o overcome the short range of alpha particles. These methods have a low alpha collection efficiency, and can miss contamination on less accessible surfaces. In a small (liters or less) volume of air, alpha particles are well-suited to such ionization monitoring because of their short range and high rate of practicality of measuring the entire subject ionization. Results indicate a conservative sensitivity of 3000 disintegrations per minute ionization quickly attaches to a neutral air molecule creating equal numbers of positive and negative ions. The relatively slow recombination rate of ions in the diffuse ion cloud allows

INTRODUCTION

RESULTS

Variability and Reproducibility

CONCLUSIONS