A low-energy, low-exposure-rate, guarded-field ionization
chamber system with a sensitive volume of approximately 1040 cm³ and an exposure-rate range from 60 mR/h to less than 0.5 mR/h
was designed, constructed and calibrated. The calibration was
effected by constructing and calibrating a 60 cm³ volume transfer
chamber of similar design against...
An ionization chamber was constructed, using a fiberglass wall
sphere, for the purpose of measuring background radiation. The
system consists of the fiberglass wall chamber, 38.85 liters in
volume, air filled, not sealed, used in conjunction with a precision
capacitor, nulling voltage supply and electrometer. It was calibrated
against a...
The objective of this study was to determine the distribution of
leakage radiation from two unshielded diagnostic-type X-ray tube
housings. This information was used to determine the shielding required
in the housings to bring them into compliance with the definition
of a diagnostic-type protective tube housing, as set forth by...
A pulse reader for ionization chambers has been developed,
tested, and calibrated. An insulated gate field effect transistor
(IGFET) was used to detect the pulses and Victoreen Model 362
Pocket Chambers were used as ionization chambers. The energy
dependence of the Victoreen Model 362 Pocket Chamber was determined
to be...
The relationship of x-ray tube housing temperature to duty
cycle was studied for a superficial therapy x-ray installation, a
dental radiographic installation, and a rotating-anode medical diagnostic
installation. Thermistors were used to measure the tube
housing temperature at points selected to be representative of
thermal conditions on the surface of...
The purpose of this study was to investigate the distribution
and magnitude of scattered radiation from a typical
mobile radiographic examination as an aid in evaluating
the potential health hazards of the scattered radiation.
Also discussed are current radiation protection standards and
recommendations for mobile radiography.
A Manonite phantom represented...
A major challenge in ethanol production using lignocellulosic feed stock is
inefficient utilization of hemicellulose, which accounts for 30-40% of lignocellulosic
biomass. Xylose, comprising >60% of recoverable sugars from hemicellulose is a
major product of the hemicellulose hydrolysis. Utilization of this carbon source would
significantly increase the ethanol yield from...
This study examines stream channel erosion processes in a small urbanizing watershed influenced by deposits of the Columbia Basin catastrophic floods: Kelley Creek, a 12-km² tributary of Johnson Creek, located just east of Portland, Oregon. Information on landscape history, stream channels, and sediment dynamics was compiled. The effects of future...
Disposal of chlorinated hydrocarbons is a major environmental concern due to the lack of a satisfactory means of safe remediation at all contaminated locations. Current technologies rely primarily on incineration, a process that can lead to dangerous byproducts such as dioxin. If the chlorine substituent can be removed prior to...
High-altitude color infrared photography is found to be
an effective tool for forest inventory in the Umpqua National Forest
of southwestern Oregon. Intelligent resource management requires
the rapid, accurate, and economical inventory results that can be
supplied by remote sensing. Color infrared film is shown to possess
properties that make...