Physical Sciences and Mathematics Commons^™

Simulative Investigation Of The Detection Of Modes Of Luminosity Variation In Astrophysical Sources, James Collins

Masters Theses & Specialist Projects

Five astronomical data analysis methods were evaluated, using computer simulation techniques, for minimum detection levels, periodicity detection, and parameter estimation sensitivities. The evaluation of these methods was accomplished using three basic waveforms with the addition of ten “random” noise samples from a Gaussian distribution of known parameters. The chi-square and t-test methods were evaluated in detecting low-amplitude variability and brightness level shifts. Results indicate both methods have a strong dependence on the estimation of the standard deviation (σ) where a 0.1 change in σ will affect detection rates by ten to twenty-five percent at the ninety-five percent confidence level. The …

Ultraviolet Radiation Effects On Rotifers, Syed Asim Hussain

Masters Theses & Specialist Projects

The purpose of this investigation was to study ultraviolet radiation effects on rotifers. The rotifer studied was Philodina acuticornis odiosa Milne. Isolation cultures were used to grow the rotifers individually in separate U-plate depressions. The source of ultraviolet radiation consisted of four mercury germicidal lamps used in combination to deliver a uniform flux of 315 uW/cm² over the sample. Five groups of rotifers, one control and four experimental groups of 96 each, were used. The rotifers used were 2-10 hours of age at the beginning of the experiment. The experimental groups were exposed to uv radiation for 3 minutes, …

Ultraviolet Photosimulated Thermoluminescence Of Lithium Flouride, Martin Payne

Masters Theses & Specialist Projects

TLD-100 (lithium fluoride) thermoluminescence dosimeters are widely employed for the detection of ionizing radiations. This paper shows that these dosimeters may also serve as practical germicidal ultraviolet radiation dosimeters. To measure ultraviolet radiation, the TLD-100 dosimeters are first exposed to 500,000 roentgens of gamma radiation and then annealed at 300°C. Subsequent dosage of ultraviolet radiation may be determined by observation of photostimulated thermoluminescence of the crystal. The presented data indicate that the thermoluminescence response is linear for exposures up to 6,000 µjoule/cm² and independent of exposure rate from 0.1 µ watt/cm² to above 50 µwatt/cm². Optical …

Determination Of (N, 2n) Reaction Isomeric Cross Section For 87rb, 112cd, 138bz, And 186w Using 14 Mev Neutrons, Hsiao-Chueh Kao

Masters Theses & Specialist Projects

The purpose of this investigation was to measure the cross section for each of the reactions 87_{Rb(n, 2n)} 86m_Rb, 112_{Cd(n, 2n)}111m_Cd, 138_{Ba(n, 2n)} 137m_Ba and 186_{W(n, 2n)} 185m_W at 14.7 ± 0.03 MeV incident neutron energy. The incident neutron flux was determined during each irradiation from the activity produced in copper or aluminum disks between which the isotopically enriched sample was sandwiched. The 63_{Cu(n, 2n)}62_Cu and 27_{Al(n, p)}27_Mg reaction cross sections were assumed to be 593 ± 45 mb and 73 ± 5 …

X-Ray Induced Luminescence Of Sapphire And Ruby, Ivan Collier Jr.

Masters Theses & Specialist Projects

Over the past decade the luminescence properties of sapphire (∝-AL₂O₃) and ruby (Al₂O₃:Cr₂O₃) have been the subject of many investigations because of their importance in materials technology. Sapphire and ruby are at present used as lasing materials, radiation dosimeters, and as optical windows. In order that these operations may be made more efficient, and that other useful luminescent properties may be systematically explored and developed, much attention has been given to understanding the luminescent mechanisms from the standpoint of the physics of the solid state. However, mechanisms have …

-Ray Induced Luminescence Of Ruby, Wayne Cooke

Masters Theses & Specialist Projects

Since the advent of the laser there has appeared a multitude of scientific papers describing the various parameters that would affect the lasing action of the ruby laser. Many investigations have been carried out to determine the efficiency of the R-line fluorescence in ruby: however very little work has been done concerning the X-ray-induced luminescence of ruby.

Certainly the applications to laser technology would be of sufficient importance to merit a study of ruby under continuous irradiation, although this was not the main stimulus that motivated this investigation. The original program of study was undertaken to determine if there existed …