Date of Award

8-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Engineering and Science

Advisor

DeVol, Timothy A

Committee Member

Serkiz , Steven

Committee Member

Fjeld , Robert

Abstract

The primary objective of this study was to design, test, and model the electrostatic field in a gas-filled radiation detector constructed with either a carbon nanotube (CNT) or a CNT array as the anode. Tungsten anodes of 500 to 4μm diameters were used to observe the gradual decrease in operating voltage with a decreasing anode diameter and estimate efficiencies of CNT anodes in a coaxial design. An electrostatic model (Maxwell 3D/2D) was used to model the resulting electric field associated with a single CNT in the coaxial configuration as well as to optimize the pitch (distance between individual CNTs in an array) of the CNT array in a parallel plate configuration to maximize the electric field at a fixed operating voltage. Experimental results indicate that a coaxial design with three different size CNTs (40nm diameter and 35, 40, and 105μm lengths) at an operating voltage of 10V would result in beta detection in the ionization region with absolute efficiencies of 1.13x10-6, 1.31x10-6, and 7.18x10-7 % respectively. The coaxial design electrostatics model resulted in smaller dimensions of the electric field than that for the 'mean free path for ionization' which is consistent with the ionization region operation. The parallel plate configuration electrostatics model maximized the electric field with a CNT array of 100nm diameter 40μm length CNTs with a pitch of 50μm.

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