Title

A study on muon drift tube health monitoring with a concentration in temperature and gas composition

Date of Award

2010

Degree Name

M.S. in Electrical Engineering

Department

Department of Electrical and Computer Engineering

Advisor/Chair

Advisor: John Weber

Abstract

This thesis is focused on the temperature and gas composition aspects of a Health Monitoring System for a nuclear material detection chamber powered by Muon Drift Tube arrays. This technology was developed with the purpose of providing a safer, more effective volume imaging technique to detect threat material. By using an array of these tubes to enclose a scan area, one would be able to detect the entrance and exit vectors of the muons going across in order to generate an accurate 3-D representation of the matter where colors would dictate density levels (correlating to a material's nuclear number). Each of the tubes on the detector array have a tungsten wire going across their center and are filled with a mixture of gases that is designed to be excited by the passage of muons through the tube.A high positive potential is placed on the wire to attract electrons dislodged by the muon passage. The signal caused by the work of the electrons is then amplified, time tagged and sent to a computer system for 3-D image generation.The relevance of the research subject comes from the fact that the performance of these detectors is very sensitive to variations in both physical and environmental conditions in terms of accuracy and consistency in operation. These variables include, but are not limited to, conditions such as temperature, pressure, humidity, gas composition, magnetic field, wire gravitational effects and other factors that come from detector aging. As a result of these constraints, it is essential to understand the behavior of the detector when affected by these conditions to try to develop a design in which the detector can maintain consistent performance. Through research and experimentation one can generate enough data to not only analyze detector performance under these variables but also to use the data to develop a control system that 'learns' to adjust through automatic configuration of the electronics. Nuclear terrorism ranks high on the top threats to humanity in the next century; muon tomography technology represents a leap in a field of ever increasing importance since it not only presents a safer scanning mechanism but is also able to detect threat material hidden in dense containers. Scientists agree that the technology currently used at US borders, which mainly involves x-ray and gamma detectors, is inefficient for detecting nuclear materials isolated with layers of lead or steel. Any terrorist organization that has the technology to represent a nuclear threat in the future will ultimately also have the resources to develop better ways to hide their material from detection. This technology, when implemented correctly, could ultimately help upset those efforts. With such an important duty on its shoulders and millions of dollars ultimately spent to implement the technology, it is essential to guarantee the lowest percentage of detector error regardless of variations in its physical and environmental conditions.

Keywords

Detectors Design and construction, Muons Effect of temperature on, Three-dimensional display systems, Nuclear terrorism Prevention

Rights Statement

Copyright 2010, author

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