No description available.

No description available.

Thesis (M.S.)--University of Michigan, 1968.

A self-powered neutron detector (SPND) is a device that, coupled with a current meter, provides a readout proportional to neutron population. This thesis discusses the design parameters of an array of such devices, their characteristics, and the use of these devices as a self-powered neutron spectrometer (SPNS) to provide information about the energy distribution in a neutron radiation field. Neutron absorption in an appropriate material produces subsequent beta emissions. In a SPND, some of these beta particles will cross a non-conducting region and stop in a collector material. A net exchange of charge between these regions can be read as a current flowing between the emission region and the collector region. One potential SPNS design was modeled using a Monte Carlo simulation of the device's interaction with a radiation field. The Monte Carlo program used predicts the beta flux which is proportional to the current that would be produced by an actual device. Various beta emitting materials were considered for this device, and a sensitivity study of each was included. The design considered is comprised of a concentric set of these cylindrical SPND detector elements which, in themselves, are currently available technology. / Graduation date: 1999

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on Mar. 13, 2007). PDF text: xiii, 159 p. : ill. (some col.) UMI publication number: AAT 3223008. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

No description available.

Thesis (M.S.)--University of Michigan, 1963.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Feb. 17, 2009). PDF text: xiii, 110 p. : ill. ; 3 Mb. UMI publication number: AAT 3326861. Includes bibliographical references. Also available in microfilm and microfiche formats.

Neutron bombardment of bipolar transistors creates cluster defects in semiconductor material. The clusters are small volumes of semiconductor material containing several hundred atoms displaced from their proper lattice sites owing to collision processes. They act as recombination centers in transistor bases, reducing minority carrier lifetime and consequently reducing transistor current gain. The damage is permanent to the semiconductor device and can only be corrected by thermally annealing the transistor. Copious test data available on bipolar transistors d.c. gain (hFE) response to incident fast neutron fluences confirm their mathematically derivable functional relationships. This report develops a neutron fluence detector system based upon the current gain (hFE) degradation. An approximate model extending these results to include the effects of temperature is developed. A probe containing an npn silicon planar transistor with associated components to allow hFE measurements is designed. A thermal sensor is also designed. More precise neutron data is obtained by correcting for d.c. current gain versus ambient temperature error. The design of the probe is the major contribution in this report. In addition to the computer simulation of the probe model a system architecture and implementation is presented. The detector system is comprised of the probe and associated data acquisition I/O circuitry. A microcomputer processes the probe data to calculate the neutron fluence received.

published_or_final_version / Physics / Master / Master of Philosophy